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The Role of Dimethylaminoethanol in Cosmetic Dermatology
Abstract
Skincare formulations for the improvement of aging skin are increasingly important consumer products. Here, we review available data on one such agent — 2-dimethylaminoethanol (DMAE) or deanol — that has recently been evaluated in a placebo-controlled trial. DMAE is an analog of the B vitamin choline and is a precursor of acetylcholine. Although the role of acetylcholine as a neurotransmitter is well known, growing evidence points to acetylcholine as a ubiquitous cytokine-like molecule that regulates basic cellular processes such as proliferation, differentiation, locomotion, and secretion in a paracrine and autocrine fashion. Indeed, this modulatory role may contribute to the cutaneous activity of DMAE. Thus, the benefits of DMAE in dermatology include a potential anti-inflammatory effect and a documented increase in skin firmness with possible improvement in underlying facial muscle tone. Studies are needed to evaluate the relative efficacy of DMAE compared with other skin-care regimens (e.g., topical antioxidant creams, α-hydroxy acids).
... The mechanism of action of DMAE in the skin is not totally elucidated yet (Baumann, 2002;Morissette et al., 2007;Deccache et al., 2010). It is known that DMAE is similar to choline, being a precursor of a cetylcholine neurotransmitter (Baumann, 2002;Deccache et al., 2010;Uhoda et al., 2002;Grossman, 2005), which would stimulate the muscles of the face causing a tensor effect in the skin known as lifting effect (Perricone, 2001). . ...
... Besides the possible interference of the cholinergic neurotransmitter, there are also theories concerning the antiinflammatory effects of DMAE, which are still not totally understood (Morissette, 2007;Grossman, 2005). Another mechanism would be acting on collagen synthesis in dermis, which has cholinergic receptors (Giannoccaro et al., 2007). ...
... It can be noticed that studies must be accomplished in order to evaluate the effectiveness of topical products containing . DMAE as a tensor agent on the face skin (Baumann, 2002;Grossman, 2005). The aim of this paper was to develop formulations containing DMAE. ...
The aim of this paper was to develop formulations increased of DMAE and evaluate their physical-chemical stability and rheological behavior. Eleven formulations containing 3% DMAE pidolate or 3% DMAE acetamidobenzoate were developed and both preliminary stabilities tests and rheological measurements were carried out. They were considered stable during all period of study. The type of DMAE did not modify the viscosity of the emulsion and all presented pseudoplastic behavior with hysteresis area. An increase of hysteresis area could be observed with DMAE addition. The results point that the type of DMAE can influence the physical stability of the final product.
... 4000`lerde ve Eski Yunan`da M.S. 130-200`de ve de Galenos`unyazdığı Local Remedies isimli kitabında kozmetiklere ilişkin unsurlara rastlanılmıştır [1][2][3] . Günümüzdegünlük bakımın vazgeçilmez unsuru olan kozmetik ürünlerinbeklenen veya hedeflenen özellikleri için bileşimlerinde yer alan hammadde veya sistemlerin etkisi oldukça önem kazanmış, dolayısıyla yeni hammaddelerin üretimi ve yeni teknolojilerin kullanımında artışa neden olmuştur [4][5][6][7][8][9][10][11] . Doğal hammaddelerde; yeni doğal bileşenler, Avrupa`da 1960 yılı sonlarında başlayan 'yeşil hareket' ile kozmetik endüstrisinde önem kazanmış, bitkisel, deniz, mineral vb. ...
... Dermisdeki üç ana bileşen olan kollajen, GAG ve elastin birçok yaşlanma karışıtı/anti-aging bilimsel çalışmaya konu olmuştur ve kırışıklık giderici kremden cilt dolgu ürünlerine kadar değişen ürün gruplarında yer almaktadırlar 17 . Günümüzde yenilikçi kozmetik ürünlerden beklentilerin önemli bir kısmını oluşturan yaşlanma karşıtı ürünler, dünyada kozmetik pazarının yaklaşık beşte birini oluşturmaktadır 11 . Klinikte "daha iyi görünmek", doğrudan "daha genç görünmek" anlamı taşımamaktadır. ...
... Plusieurs crèmes anti-rides qui possèdent des effets «liftants instantanés» contiennent des amines secondaires ou tertiaires (diméthylaminoéthanol (DMAE), triéthanolamine, méthyl-diéthanolamine, etc.) à des concentrations pouvant atteindre 25 %. Des données cliniques objectives existent sur l'effet anti-ride d'un gel facial de DMAE 3 % (337 mM) [6]. Des travaux récents de notre groupe ont démontré que le DMAE induit la vacuolisation cellulaire dépendante de la V-ATPase in vitro (> 1 mM, appliqué pendant 30 minutes ou plus) (figure 1B) dans les fibroblastes dermiques de lapin, l'épithélium cutané humain [4] et le muscle lisse en culture (figure 1B). ...
... Un épaississement de l'épiderme et une présence de cellules vacuolaires in vivo, après l'application de DMAE (3 %, 1 h) sur la surface interne de l'oreille de lapin, ont été observés (coupes histologiques) [4]. Nous avons proposé comme interprétation que la base cellulaire de l'effet anti-ride très rapide des amines appliquées sous la forme d'une crème persistante constitue une expansion cellulaire vacuolaire médiée par la V-ATPase, plutôt que le résultat d'une hypothétique interférence avec la transmission nerveuse cholinergique, proposée sans base expérimentale dans le passé [6]. Les effets cosmétiques pourraient malheureusement ne pas être dissociables de conséquences néfastes de la cytopathologie vacuolaire. ...
... However, due to DMEA's lower solubility compared to its family members N-methyldiethanolamine (MDEA) or N-methylethanolamine (MMEA), TMEDA/DMEA-based fuels catalyzed with inorganic copper salts are unstable without the addition of an organic solvent such as methanol. Consequently, as methanol provides a lower specific impulse compared to those amines, stable formulations of PAHyp 0 also exhibit Additionally, DMEA is considered safe to handle, as it is commonly used in skincare products [18]. To study the chemical stability, the spectra of compounds were recorded using a Nicolet iS50 ATR FT-IR spectrometer. ...
This work presents an experimental study on the hypergolic behavior of variants of N,N,N’,N’-tetramethylethylenediamine (TMEDA)/N,N-dimethylethanolamine (DMEA) system, named PAHyp 0, with 93 wt% hydrogen peroxide. Two different copper-based catalyst and one cobalt-based catalytic agent were dissolved in the fuels to trigger the pre-ignition reactions. When employing copper chloride dihydrate, the resultant fuel requires methanol (ternary system) as a stabilizing agent, whereas both carboxylic salts of copper and cobalt dissolved in TMEDA/DMEA deliver a stable formulation (binary system) without the need for any organic solvent. Shadowgraph high-speed imaging was used to capture the ignition process and pressure wave development of over 30 fuel samples in a modified drop test. An ignition/stability envelope was proposed to map the safe and unstable formulations. It was demonstrated that the concentration of TMEDA should be no more than 50% in the binary system, while the amount of methanol should fall within a concentration window of 33 to 50% in the ternary system. Lower loadings of catalyst, ranging from 0.5 to 1.0 wt%, are required to deliver stable fast-igniting fuels. Three promising formulations catalyzed with 1 wt% copper salts were selected to perform impinging jet fire experiments. Impinging jets yielded significantly lower ignition delay times than drop tests due to the better mixing conditions. However, it was verified that ignition may fail for low values of jet velocities, below 0.8 m/s, and for high jet velocities, exceeding 14 m/s. An attempt to explain the ignition and non-ignition events was made by using the fundamentals of explosion limits of the hydrogen/oxygen system and oxidation reactions at low temperature. Remarkably, ultra-fast ignitions of about 10 ms were measured by the impinging jet setup within near-optimal operational conditions. Therefore, TMEDA/DMEA-based fuels with reduced catalyst loadings (0.5–1.0 wt%) offer new opportunities in aerospace propulsion and should be further studied.
... In natural raw materials, new natural components have gained importance in the cosmetics industry with the 'green movement' that started in Europe at the end of 1960, and plant, marine, mineral, etc. originated and even organic cosmetic raw materials, mixtures and finished products have quickly found their place in the market (Grossman, 2005). The demand for natural cosmetic raw materials has increased the share of cosmetics in the global market. ...
There are many snail slime (secretion) creams in the cosmetic industry. Many of them are formulated with herbal or synthetic allantoin when the cream ingredients are read. However, natural snail secretion also contains many bioactive components (glycoproteins, fatty acids, polyphenols, vitamins, etc.) other than allantoin. For this reason, cosmetic effectiveness decreases in products that do not contain natural snail secretion. It is not easy to reach the natural snail slime cream due to the limited collection of secretions from the appropriate snail species and limited sustainable methods. While the secretions are collected from snails by traditional methods (exposure to stresses such as salt and electricity application), animals are usually harmed or killed. If the method used for secretion collection is not suitable, animals are exposed to stress and release skin irritants. In addition, the secretion of each snail species does not have the suitable ingredients in the production of cosmetics. In this study, various essential oils and ozone were sprayed with cold steam into the porous chamber containing the snails in a specially designed device. Secretion was collected, from live snails (Helix aspersa) suitable for use in cosmetics, without being exposed to stress. Then the cream was formulated with this secretion. Microbiological and physicochemical analyzes were made in the cream produced. As the results; secretion containing important bioactive components was obtained from the appropriate snail species with sustainable methods, and the analysis results showed that the cream formulated with the addition of the secretion was qualified and suitable for use.
... The strong interest of the food industry is related to its nutritional content, such as proteins, unsaturated fatty acids [11], vitamins, and minerals, which makes caviar to be considered for cosmetic purposes as well [12,13]. Also occurring in fish like sardines and salmon, dimethylaminoethanol (DMAE) is a substance frequently used with antiaging appeal due to several possible mechanisms that are constantly investigated [14][15][16][17]. Within this scenario, besides the need to invest in natural raw materials, cosmetic product developers are more than ever investing in new sensory technologies to survive in this competitive market. ...
Abstract The high consumption of antiaging cosmetics represents an outstanding opportunity for the development of new processes and attractive products in the cosmetic industry. Stability studies and sensory analyses are critical steps in the development process and production chain. Here we present a potential antiaging cosmetic product with innovative sensory characteristics. Caviar extract antioxidant properties were firstly evaluated by the DPPH method since it is an important mechanism against skin aging. Ca-alginate beads containing 2% of caviar extract and 0.2% of black pigment were prepared to obtain spheres similar to caviar. The beads were incorporated in a gel phase (hydroxyethylcellulose 2.5%) containing 3% of dimethylaminoethanol. Stability was evaluated in different storage conditions (sunlight exposure, 5 ± 2 °C, 37 ± 2 °C and r.t.) through the parameters: appearance, color and odor, pH (6-7), density (0.98-1.14 g.mL-1), centrifugation and average size. After approval by the Committee for Ethics in Research (n° 3.503.061), 30 volunteers tested the new formulation and answered a questionnaire. At 2%, caviar extract was able to scavenge 10.9% ± 0.58 of DPPH radical. Formulations showed good stability after 90 days, even considering the average size (7.47 ± 0.41 - 8.4 ± 0.65 mm2). 90% of the sensory test participants reported that they would buy the new product. Therefore, the new product developed demonstrates a promising potential as an attractive cosmetic product.
... It has been used in the treatment of hyperkinetic disorders and may lead to positive behavioral changes in patients with senile (73,74). It has also skin-firming effects in cosmetology by increased contractility and adhesion in skin cells (75). ...
Low levels of nutrient intake are common in industrialized countries. This has negative implications on health and is associated with chronic diseases. Supplementation of vitamins, minerals, and key nutrients to optimal levels may, therefore, be beneficial for individual health and for the health economy. Although the use of supplements has become very common, due to a lack of monitoring, there is very limited data on the efficacy of supplementation with different formulas. In this study, we present the results of a randomized controlled study on the efficacy of a novel formulated nutraceutical, N247, in 250 healthy volunteers aged 26–75 years and a placebo control group ( n = 35). The broad-spectrum formulation of N247 includes essential vitamins, minerals, and trace elements that are adequately balanced in regard to synergies and related metabolic functions. Moreover, tolerance, safety, and nutrient availability is an important aspect of daily, long-term use of N247. After 3 months of regular N247 use, levels of vitamins and minerals in serum were significantly increased in the N247 group compared with the control group and a placebo group, with excellent compliance rates. Coupled with additional natural ingredients that aim to increase the potency of the nutrients, N247 may represent a novel and beneficial supplement for individuals with nutritional deficiencies.
Clinical Trial Registration: https://clinicaltrials.gov/ , identifier: NCT04054505.
... Além disso, é considerado um modulador de citocinas e regulador da função celular, crescimento e diferenciação da pele (21) . ...
Objetivo: Verificar a influência de um protocolo na otimização do processo de cicatrização de queimadura decorrente do uso da criolipólise. Métodos: Trata-se de um relato de caso descritivo, em um indivíduo do sexo feminino o qual se submeteu ao procedimento de criolipólise na região abdominal superior e inferior, sendo que após o procedimento a paciente foi acometida por queimadura grau 2 na região do abdômen superior. Foi aplicado protocolo de otimização do processo cicatricial com o uso do laser vermelho 660nm, carboxiterapia e fator de crescimento. Resultados: Após sete dias, a pele da região da queimadura apresentou-se com aspecto vermelho escuro no centro e nas bordas ainda com processo inflamatório, sem prurido e sem bolhas. No décimo quinto dia de tratamento, verificou-se delimitação da área dos piltiers e a pele com sinais de cicatrização, com a área de queimadura delimitada. No segundo mês, observa-se processo de cicatrização das bolhas e com melhora da coloração e pigmentação. Posteriormente, com três meses de tratamento da queimadura, visualiza-se uma pele firme, lisa e sem cicatriz aparente demonstrando total recuperação do tecido. Conclusão: O protocolo demonstrou-se eficaz para a otimização de cicatrização da queimadura pela criolipólise, melhorando de maneira satisfatória a textura e pigmentação da pele, bem como o processo cicatricial, quando comparadas com o tecido não lesado pela queimadura.
... In einer Studie führte die Applikation einer dreiprozentigen DMAE-Zubereitung im Gesicht nach 16 Wochen zu einer Verbesserung von Falten und periokulä-ren Dunkelverfärbungen, zu einer Verminderung der Nasolabialfalten sowie zu einer Straffung der Halshaut. Diese Effekte nahmen auch nach zweiwöchiger Anwendungspause nicht ab [79]. ...
Falten reduzieren, die Haut straff halten und einen frischen Teint herbeizaubern — diese Versprechungen machen Cosmeceuticals. Sie enthalten meist effektivere Inhaltsstoffe als herkömmliche Kosmetika.
... The FEEDAP Panel considers that the damage to tissues upon direct contact with DMAE is a result of the corrosive nature of DMAE. Conversely, low concentrations of DMAE are not expected to cause corrosion of tissues; the compound is safely used in cosmetics 28 in concentrations of about 3% (Grossman, 2005). It is noted that DMAE is not genotoxic, and the concentrations of DMAE in Taminizer D (≤ 0.1%) are sufficiently low that skin exposure to the product is unlikely to cause any local or systemic toxicity. ...
Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of Taminizer D (dimethylglycine sodium salt) as a feed additive for chickens for fattening, based on a dossier submitted for the modification of the terms of authorisation of the additive. The product is authorised in the European Union for chickens for fattening at the maximum content of 1,000 mg/kg complete feedingstuffs. The applicant proposed the introduction of an additional manufacturing process, which introduces an impurity (dimethylamino-ethanol (DMAE)) in the additive at concentrations up to 0.09%. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) considered that the proposed modification would not substantially affect the previous assessment as related to the safety of the environment and the efficacy of the product. Since the safety of the active substance was established, the current assessment has dealt with the impurity DMAE. Considering the toxicological profile of DMAE, the estimated intake by the target animal and consumers, and making use of the Threshold of Toxicological Concern (TTC) approach, the Panel concluded that Taminizer D, manufactured by the DMAE route, is safe for both chickens for fattening and consumers, up to the maximum level of 1,000 mg/kg feed. The FEEDAP Panel extends its conclusions about Taminizer D produced by the original method to cover also Taminizer D produced by the new DMAE method. There is minimal risk to users from dust produced as a result of normal handling of the additive. Taminizer D is not irritant to skin but may be irritant to eyes; it is regarded as a potential skin sensitiser. The FEEDAP Panel recommended to set a specification for the DMAE content in the additive. © 2018 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority.
... Michel Pistor in 1952 [1]. This therapy is achieved by directly injecting a suitable biocompatible and fully absorbable product into the dermis layer to further maintain or restore youthful skin condition while achieving the effect of activating and anti-aging. ...
... Follow-up study among DMAE gel users for up to 1 year had demonstrated a good safety profile. The improvement of skin firmness with possible augmentation of face muscle tone may be caused by DMAE's anti-inflammatory properties (Grossman, 2005). Other the other hand, paeoniflorin (In traditional Chinese medicine as Baishao), which is extracted from the roots of Paeonia lactiflora had been found to protect cells from DNA damage caused by UV-B in both human and hairless mouse keratinocytes culture. ...
Cosmeceuticals are topical cosmetic-pharmaceutical hybrids used to maintain and improve appearance
and beauty of the skin. The strong demand from the consumers to constantly look youthful and flawless
has driven the research and development as well as sale volume of cosmeceuticals. Present studies show
that many cosmetic products, which were assumed to be inert in the past, may modulate dermatological
structure or function. The key players of cosmeceuticals are anti-aging therapy along with bleaching
agent, sunscreen, and hair cosmeceuticals. This book chapter aims to explore the safety, toxicity and
efficacy of these cosmeceuticals. Challenges and possible advancement potentials would be discussed.
As patients are increasingly seeking advice from physicians and pharmacists regarding cosmeceuticals,
the authors hope to provide health care professional and pharmaceutical scientists a resource that
would aid to educate patients in using evidence-based cosmeceuticals to enhance their appearance and
alleviate dermatological problems.
... The lifting effect of the DMAE on facial skin, especially on wrinkles around the eyes, refers to its possible mechanism of action, which leads to an increase of the acetylcholine levels on the skin, restoring the muscle tone and firmness 5 , and also adhesion of epidermis and dermis cells 6 . Furthermore, an increase in skin acetylcholine levels can influence collagen synthesis in the dermis, once that scientific studies show that cholinergic receptors located on the surface of cells such as keratinocytes, fibroblasts, and endothelial cells, can modulate cellular proliferation, secretion, differentiation, migration, and viability [6][7][8] . Many studies in vitro have tried to elucidate the effects of DMAE on isolated cells, however, with controversial results. ...
The aim of this study was to analyze the effects of formulations containing DMAE pidolate and DMAE acetoamidobenzoate on the skin. Four areas of five swines were submitted to following treatments during 15 days: C (Control), S (Silicone = 80 % DC*LC Blend (R)), F1 (DMAE acetoamidobenzoate), F2 (DMAE pidolate). Measures of the thickness of epidermis and stratum corneum, and the density population of fibroblasts and leukocytes in papillary dermis were obtained. We also assessed possible variations in birefringence of dermis collagen bundles. Means of the data was compared using ANOVA followed by the Tukey test. The F1 and F2 groups showed a thicker epidermis than the control group (p < 0.01), but did not demonstrate a significant difference in the number of fibroblasts and leukocytes, as well as in the birefringent areas of collagen bundles, in comparison with the control groups. The DMAE-supplemented formulations enhanced viable epidermis thickness, but did not modify structures related with mechanical properties of the skin.
... It will Increases new cell growth; has a moisturizing effect on the skin and will smoothen and soften the skin. [20]. ...
... DMAE is the precursor to choline and may increase acetylcholine levels. 48 DMAE inhibits production of the age-related pigment lipofuscin, which accumulates in all aging tissues. This is significant because cells with increased lipofuscin cause lysosomes to perform poorly, which leads to increased accumulation of poorly functioning mitochondria and increased ROS production. ...
... DMAE, that shares with EGb the characteristic of improving brain alert and focus [38], has only one hydroxyl group with possible antioxidant ability suggesting that other mechanism should contribute to explain the observed effects of DMAE. However, the role of DMAE in dermatology including a potential anti-inflammatory effect and a documented increase in skin firmness with possible improvement in underlying facial muscle tone [39] could be a conjunction of many actions including its antioxidant activity. On the other hand, the incorporation of chemical compounds into the cell is a function of their lipophilicity. ...
Recently, a number of synthetic drugs used in a variety of therapeutic indications have been reported to have antiaging effects. Among them, Dimethylaminoethanol (DMAE), an anologue of dietylaminoethanol, is a precursor of choline, which in turn allows the brain to optimize the production of acetylcholine that is a primary neurotransmitter involved in learning and memory. The data presented here includes new information on the ability of the compound to scavenge specific free radicals, assessed by Electron Spectroscopic Resonance (EPR), to further analyze the role of DMAE as an antioxidant. DMAE ability to directly react with hydroxyl, ascorbyl and lipid radicals was tested employing in vitro assays, and related to the supplemented dose of the compound.
... In this study the topical use of DMAE was found to decrease forehead lines and fine wrinkles around the eyes, and improve lip shape and fullness and the overall appearance of aging skin. 123 The authors of the study concluded that "the benefits of DMAE in dermatology include a potential antiinflammatory effect and a documented increase in skin firmness with possible improvement in underlying facial muscle tone." ...
This performance is about the materialization of the performer's thoughts and feelings on the stage. In the performance, imagination becomes spatial. The stage is a place for the appearance of the invisible. Yasu Ohashi says: "The actors aim at our senses, our body, and our unconscious and not at our intellect. Their gestures try to envision the invisible world."
... However, some instant anti-aging lifting effects clinically observed in patients during the treatments led to a fairly large use of DMAE in cosmetic and dermatologist-prescribed anti-aging formulations (Perricone 2000). Clinical observations have reported the safety and the efficacy of DMAE in improving the overall appearance of aged skin, in reducing forehead lines, periorbital fine wrinkles and under-eye dark circles and in provoking a lifting effect (Grossman 2005). Furthermore, in a study performed in human volunteers, Uhoda et al. (2002) demonstrated a decrease in the mechanical anisotropy of the skin after a single application of a DMAE containing gel. ...
Dimethylaminoethanol (DMAE) has been used in anti-aging formulations but few scientifically based data address its efficacy. The aim of this study was to evaluate the effects of DMAE-based formulations on hairless mice and human skin. Formulations containing with or without DMAE were applied to the dorsum of hairless mice. Histopathological and histometric evaluations were carried out after seven days. Formulations were also applied to the ventral forearm and the lateral periocular area of human volunteers. Stratum corneum water content and skin mechanical properties were analyzed using Corneometer and Cutometer, before and after a single and repeated application. Histometric evaluations showed that formulations with or without DMAE increased the viable epidermis thickness, but only the DMAE-supplemented formulation led to increased dermal thickness. DMAE also induced increase in collagen fiber thickness, which was observed in the histopathological study. After the single and the 8-week period application on human skin, formulations with and without DMAE enhanced the stratum corneum water content in the forearm skin. Mechanical properties were not significantly modified. So, we can suggest that DMAE action is related to its effects on the dermis as observed in the histopathological and histometric studies and showed hydration effects on skin.
... The benefits of DMAE may include a potential anti-inflammatory effect and an increase in skin firmness with possible improvement in underlying facial muscle tone. 42 Ubiquinone (coenzyme 10) is present in almost all living cells, excluding some bacteria and fungi. It is a strong antioxidant in cells. ...
The research and development of cosmeceuticals is booming in recent years. Many substances, either from botanical, animal, or chemically synthesized sources, are tested or investigated as the active ingredients in cosmeceuticals. The interactions between cosmeceuticals and skin are complex, depending on the specific composites in cosmeceutical products, condition of the skin or general health status of a subject, and the environment where the action occurs. As such, careful preclinical or clinical evaluation of efficacy and safety is a prerequisite for the development of a specific cosmeceutical product. This article reviews some of the ingredients that are currently in use or might be potential candidates in cosmeceuticals of different categories.
... The 'cosmeceutical' agent 2-dimethylaminoethanol (DMAE) is an ingredient of numerous antiwrinkle creams; in the lay press, it has been dubbed 'an instant anti-aging face-lift.' 1 Some objective clinical information is available about DMAE: a placebo-controlled trial consisting of a 337 mmol L )1 (3%) DMAE facial gel applied for 16 weeks showed efficacy in attenuating wrinkles of various sizes and improving lip shape and the fullness of skin. 2 The agent was well tolerated during the trial and its 1-year extension. Another randomized, double-blind, split-face study using 3% DMAE showed a nonsignificant trend towards increased skin firmness. ...
The 'cosmeceutical' agent 2-dimethylaminoethanol (DMAE) is a tertiary amine found in high concentration in numerous topical antiwrinkle preparations.
We hypothesized that a 337 mmol L(-1) (3%) DMAE reservoir applied to the skin could reproduce the cytopathology induced by other amines by maintaining a millimolar drug concentration within a certain depth of the skin layers, and that vacuolar cell expansion could account for the very rapid effect on the apparent skin fullness.
Morphological and functional assays were applied to cultured rabbit dermal fibroblasts treated with tertiary amines in vitro. A morphological verification of the vacuolization caused by topical DMAE was also attempted in vivo using the inner skin of the rabbit ear and in vitro using primary cultures of human cutaneous epithelial cells.
Fibroblasts responded to DMAE (2.5-10 mmol L(-1)) by massive vacuolization (0.5-4 h; phase contrast observations). Triethanolamine, another chemical frequently used topically, was also active in this respect (10 mmol L(-1)). The vacuolar adenosine triphosphatase inhibitor bafilomycin A1 prevented DMAE- or triethanolamine-induced vacuolization; adding bafilomycin A1 or cell washout slowly reversed the established vacuolization induced by DMAE. Further effects of DMAE in cultured fibroblasts included a moderate cytotoxicity (10 mmol L(-1)) that was abated by bafilomycin A1 cotreatment, a concentration-dependent mitotic arrest (2.5 mmol L(-1)) and transient and mild effects on cell ploidy. The epidermis of the rabbit external ear was significantly thickened and exhibited clear perinuclear swelling indicative of vacuolization in response to 3% DMAE (1 h; paraffin tissue sections). Cultured human cutaneous epithelial cells responded to DMAE by vacuolization (inhibited by bafilomycin A1 cotreatment).
The vacuolar cytopathology induced by concentrated organic amines may be the cellular basis of the antiwrinkle effect of DMAE.
Dicamba is a popular herbicide with rising use but is also notorious for volatility drift. Inspired by meclofenoxate, which we show to be highly herbicidal, we developed a derivative of dicamba with an ester‐bond to 2‐dimethylaminoethanol. It remained herbicidal but is non‐volatile, entering plants intact and hydrolyzing inside leaves to dicamba and 2‐dimethylaminoethanol. This pro‐dicamba is compatible with the relatively novel dicamba monooxygenase tolerance technology, suggesting pro‐dicamba might be a suitable, non‐volatile replacement for dicamba.
El modelado mandibular es una causa frecuente de consulta en medicina estética debido al impacto en la autoestima de las pacientes que al envejecer pierden la línea mandibular. Por eso el objetivo de este trabajo fue estudiar el efecto del tratamiento combinado utilizando fórmulas lipolíticas y de estimulación celular para la disminución de la grasa submentoniana, bolas de Bichat y remodelado mandibular. Se evaluaron 159 mujeres (47,1 ± 11,7 años). La fórmula lipolítica (aplicación subcutánea) contiene L-carnitina, fosfatidilcolina e hidrolizado de algas rojas, cafeína, silicio orgánico y troxerutina. La fórmula intradérmica para reafirmar la línea mandibular contiene hidrolizado de algas rojas, silicio orgánico, myricelineTM, péptidos biomiméticos y DMAE. Se aplicaron inyecciones de la fórmula intradérmica en la línea mandibular y pliegue cutáneo del surco nasomentoniano, en conjunto con una formula lipolítica en la zona submentoniana y bolas de Bichat. 45% de las pacientes presentaron niveles de grasa submentoniana leve, 25% moderada y 30% grave. Todas las pacientes lograron una reducción significativa de la papada, mayor definición de la línea mandibular y disminución de las arrugas y de los pliegues de la piel producto del tejido adiposo localizado, mejorando significativamente la tersura de la piel. Análisis de imágenes mostraron una disminución (p<0,05) del 2% en el ángulo mentocervical y un 10% en el área tratada. Este estudio proporciona evidencias semicuantitativas de que la combinación de una fórmula intradérmica reafirmante con una lipolítica subcutánea es un método mínimamente invasivo, seguro y eficaz para la reducción de la grasa submentoniana, y el remodelado de la definición de la línea mandibular con efectos apreciables de rejuvenecimiento de la piel.
One of the effective methods to mitigate late side effects of radiotherapy is to use radioprotectors that reduce harmful effects of ionizing radiation on living cells. Nowadays there are no ideal and multifunctional radioprotectors. In this connection, the research priority is the search for new radioprotectors able to protect healthy cells from side effects of radiation therapy. A promising compound that can be used as a radioprotector is deanol aceglumate. Deanol aceglumate is known as a low-toxic nootropic drug. In addition, there is evidence of its hepatoprotective and antioxidant activity. The aim of the study is to investigate the potential properties of deanol aceglumate to protect human fibroblasts (hTERT) from gamma-radiation and C-12 ions and to select the optimal time of cell incubation with deanol aceglumate prior to irradiation. The effect of radiation was evaluated by the criteria of the time of cells doubling and cells clonogenic activity. It is shown that deanol aceglumate at a concentration of 1000 mcM has a radioprotective effect on human fibroblasts exposed to gamma radiation. The optimal time of the cells incubation prior to irradiation is 24 hours in order to achieve the highest radioprotective effect. Deanol aceglumate at a concentration of 1000 mcM does not protect normal cells when exposed to C-12 ions beyond Bragg Peak. It has been found that deanol aceglumate radioprotective properties depend significantly on the quality of ionizing radiation. The use of deanol aceglumate can be a promising way to reduce the ionizing radiation-induced diverse effect on normal human cells during radiation therapy of cancer patients.
O conceito de beleza segue padrões em que a aparência jovem da pele é extremamente valorizada. No entanto, o envelhecimento cutâneo trata-se de um processo natural que ocorre devido a fatores intrínsecos (genéticos, hormonais) e extrínsecos (radiação solar, poluição, má alimentação), que resultam em manifestações como flacidez, rugas, marcas de expressão, manchas e ressecamento da pele. Os produtos magistrais são fortes aliados nesses tipos de tratamentos, pois permite aos prescritores associações de ativos que atuam em todas as manifestações de uma pele envelhecida, promovendo o seu rejuvenescimento, por meio de ativos firmadores, clareadores, hidratantes, antioxidantes, dentre outros. Esse trabalho objetivou traçar o perfil das formulações magistrais que foram dispensadas para o tratamento/prevenção do envelhecimento cutâneo. Como metodologia foi realizado um estudo descritivo, transversal, qualitativo, a partir da coleta de informações do Livro Geral de Formulações aviadas de março de 2021 a maio de 2021 de uma farmácia de manipulação de Vitória -ES. A pesquisa constatou que 16,4% das formulações de uso tópico são para envelhecimento cutâneo, sendo 64,6% dessas formulações prescritas por dermatologista, na qual apresenta como público predominantemente as mulheres. Os ativos de maior frequência foram ácido hialurônico, Cerasomosides e Hyaxel® e as formas farmacêuticas mais empregadas foram creme (27,3%) e gel (21,8%). No requisito, associações entre os ativos, 23,85% apresentaram incompatibilidades. Diante dos resultados obtidos faz-se necessário a constante atuação e capacitação do farmacêutico com o propósito de evitar possíveis erros nas formulações, que possam vir a prejudicar a efetividade e a segurança do tratamento, impactando na saúde do paciente.
The employment of adipose tissue in cosmetic procedures is well stablished, nevertheless the usual methods have their disadvantages. There is evidence that stem cells contained within adipose tissue can successfully be used in cosmetic practices. This paper emphasizes in a new developed technique that optimizes a unique and highly innovative adipogenic growth factor “cocktail”, described further in the article, that promotes subsequent engraftment upon transplantation and that induces adipogenic differentiation with great efciency. This technique was employed for a facelift procedure, performed in six steps with signicant results in skin quality improvement, volume data and patient satisfaction. This was demonstrated on patients with acne scars or even burn scars, or for rejuvenation purposes.
Objective: The 21st century's progress in medicine and cosmetology triggered the search for effective and safe new cosmetics and procedures to fight with such problems as wrinkles or stretch marks. The study aimed to use the synergy of silanols with boron compounds and to develop treatment methods supported by an fractional-ablative laser.
Methods: Sixty-seven Caucasian people were enrolled in this study: 33 patients with facial and neck wrinkles and 34 patients with stretch marks. Preparations containing methylsilanetriol were pressed into the skin by means of oxygen infusion which were followed by the fractional-ablative laser treatments.
Results: The effectiveness of removal of wrinkles was better if combination therapy was used in the form of transdermal delivery of methylsilanetriol combined with laser therapy. The effectiveness of stretch marks removal by combination therapy was comparable to a two laser treatments and more effective than one laser therapy. Moreover, the use of products based on methylsilanetriol stabilized with boric citrate resulted in shortening the period of regeneration after the treatment with fractional-ablative laser by 29-58%.
Conclusion: The gel based on methylsilanetriol developed in this study can be successfully used after all laser treatments, but also those related to skin pricking to accelerate regeneration.
Cosmetic creams are available as oil‐in‐water emulsions for the day and water‐in‐oil formulations for the night. They can be classified according to their purpose in mainstream products, natural cosmetics, cosmeceuticals, and OTC products. Moisturizing, revitalizing, smoothing, and antiaging creams represent the most common categories of cosmetic creams. A well‐balanced cream improves skin texture and moisture, reduces pigmentation and age spots, and gives the skin a fresh, younger look. The ingredients required for the formulation of moisturizers are predominantly substances of the natural moisturizing factor (NMF) such as amino acids, urea, and sodium lactate/citrate, furthermore glycerin and sorbitol. Various vitamins allow the vitalization of the skin. The antiaging effect is based on vitamins, peptides, and special substances as well as on all antioxidants. A blend of vegetable oils with high linoleic contents smooths the skin. An effective cream contains ingredients from all categories and additional substances of desired focus. Cosmeceuticals (active cosmetics) comprise special ingredients for typical tasks and problems. Examples include agents against sunburn, acne, herpes, cornea, moisture loss on the tibia, and many others.
Falten reduzieren, die Haut straff halten und einen frischen Teint herbeizaubern — diese Versprechungen machen viele Cosmeceuticals. Sie enthalten meist effektivere Inhaltsstoffe als herkömmliche Kosmetika. Besonders Produkte, die einer vorzeitigen Hautalterung entgegenwirken, sind im Trend. Die Wirksamkeit ist zwar oft wissenschaftlich belegt; allerdings gibt es bei der Anwendung einige Risiken, die Dermatologen und Kosmetiker nicht außer Acht lassen sollten.
This chapter examines dimethylethanolamine performance on steel reinforcement corrosion in concrete for the industrial or microbial environment. An economical approach for addressing sulphuric acid induced corrosion degradation problems of steel‐reinforced concrete structures include the use of admixtures in concretes. Splitting of the steel‐reinforced concrete samples followed after the lapsing of the experimental period for electrochemical experiments, for obtaining the steel‐rebar for gravimetric corrosion evaluation. The Normal and the Weibull analyses of nondestructive corrosion rate data, the mean corrosion rate models from steel‐reinforced concrete samples with C4H11NO admixtures exhibited reductions relative to what obtained from the blank samples. An economical approach for addressing sulphuric acid induced corrosion degradation problems of steel‐reinforced concrete structures include the use of admixtures in concretes. Different types of admixtures are of interests to corrosion researchers and these include admixture substances that could improve concrete resistance to chemical attack and admixtures that could mitigate steel‐reinforcement corrosion.
The Food, Drug, and Cosmetic Act defines drugs as products that cure, treat, mitigate or prevent disease, or affect the structure or function of the human body [1]. The dermatology and cosmetic industries recognize “cosmeceuticals” as cosmetics that have drug-like benefits. The term “cosmeceutical” was first used by Dr. Albert Kligman to describe a cosmetic product that exerts a therapeutic benefit in the appearance of the skin, but not necessarily a biologic effect on skin function, which would then classify it as a drug [2–4]. The Food and Drug Administration does not recognize or regulate cosmeceuticals. The symbiotic relationship between a drug and a cosmetic has become increasingly evident with the rapid growth of the cosmeceutical industry over the last decade. There are now both prescription cosmeceuticals and over-the-counter cosmeceuticals available to consumers. This arbitrary distinction varies in different countries. For example, drugs such as tretinoin, available only by prescription in the United States, are sold as over-the-counter cosmeceuticals in Central America. Antiperspirant is also regulated as a drug in the United States while being considered a cosmetic in Europe.
Skin is the organ most exposed to environmental sunlight. Many in vitro and in vivo studies on skin have now unambiguously gathered evidence of the ultraviolet (UV) radiation involvement in the development of human skin pathologies such as sunburn, aging, autoimmunity, immunosuppression and cancer. Thus, the toxic effects of UV from natural sunlight and therapeutic artificial lamps are a major concern for human health. The mechanisms by which UV radiation promotes skin damage have been under intense investigation for decades, and much progress has been made in identifying the molecular alterations associated with changes in cellular functions. Furthermore, these studies are providing potential targets for molecular therapies. The aim of this chapter is to summarize the general knowledge available in the field of UV-induced skin damage, with an emphasis on the discussion of molecular markers of cellular senescence and inflammation. Besides the biological consequences of photodamage, this chapter also deals with technologies available for the detection of phototoxicity and characterization of the molecular action of nanostructures, and shows how helpful such approaches can be with a view to improving the photoprotection provided by skin products.
Vitamin C is commonly used to treat aged skin. It has shown regenerative effects on skin wrinkles, texture, strength, and evenness of tone through its roles as an antioxidant, tyrosinase inhibitor, and inducer of collagen synthesis. Available vitamin C formulations on the anti-aging skin care market vary by their pH, packaging, and vehicle, which may decrease absorption, and therefore, the efficacy of the product.
The purpose of this study was to assess the subjective efficacy, wearability, tolerance and overall preference of two professional vitamin C topical serums and sunscreens in Caucasian females using a split face method.
A virtual split-face study of 39 Caucasian women compared two popular vitamin C and SPF product combinations - C-ESTA® Face Serum and Marini Physical Protectant SPF 45 (Jan Marini Skin, San Jose, CA; Products A) and CE Ferulic® and Physical Fusion UV Defense SPF 50 (Products B; SkinCeuticals Inc, Garland, TX). The products were assigned to each subject's left or right side of the face, and subjects rated and compared products through 5 online surveys at baseline, 24 hours, days 3, 7, and 14.
Over 86% of the 35 subjects who completed the study preferred the smell and 83% preferred the feel and application of vitamin C Serum A over Serum B. Seventy-one percent of subjects preferred the feel and application of Sunscreen A over Sunscreen B. Results also showed a significant skin texture improvement and skin tone with Products A vs Product B. Products A trended higher for multiple additional categories.
Products A exhibited superior anti-aging benefits than Products B. Subjects preferred the smell, feel, and application of Products A and experienced significantly less irritation than Products B. Overall, Products A were preferred over Products B with subjects willing to pay more for Products A over Products B.
J Drugs Dermatol . 2014;13(10):1208-1213.
Adipose tissue is commonly used in plastic surgery procedures and is also a rich source of mesenchymal stem cells (MSCs). Since MSCs are functionally plastic cells, adipose tissue may provide a promising cell source for regenerative medicine applications. We have developed two mixed growth factor formulations (termed "dermal" and "fat" factor formulations) to be used with autologous adipose tissue to help induce the regeneration of human skin and subcutaneous tissue. In this study, we investigate the effect of these formulations on proliferation and differentiation of MSCs obtained from human bone marrow and from adipose tissues. Lower concentrations of both formulations had no effect on MSC proliferation, but induced rapid adipogenic differentiation. At higher concentrations, both formulations induced MSC death. There was no evidence of osteogenesis ormalignant transformation at any concentration, as judged by absence of foci formation, inability of the cells to be serially passaged and absence of colonies in methylcellulose matrix. Thus, at optimal doses these factor formulations promote rapid differentiation of MSCs into adipogenic cells, with no evidence of cell transformation or osteogenic induction. These studies have implications for wound healing and tissue regeneration, as well as cosmetic applications to enhance the deficits seen in aging skin and in facial volume loss.
DMAE glycolate (DG) and sunscreens have been used associated in anti-aging dermocosmetic formulations. Despite extensive use of these substances, methods for quantification of DG as raw material and in cosmetic formulations, especially when associated, are not described in the literature. RP-HPLC and non-aqueous titration methods, with determination potentiometric end-point (PT), were developed and validated for rapid assay of DG as raw material and in a topic emulsion in association with sunscreens. Both methods are simple, selective, linear, accurate and precise. The PT method was chosen for stability study of DG in the formulation developed. The proposed formulation presented good stability performance as regards aspect, pH, apparent viscosity, and SPF, with less than 5% of DG degradation compared to initial conditions.
Topical "anti-aging" products, with their seemingly limitless list of ingredients, make extensive claims to reduce wrinkles, fine lines, and sun damage, among others. Sales in the United States alone for cosmeceutical products are expected to increase by 7.4% per year to $8.2 billion by 2012. However, in this enormous industry, there has been a significant lack of rigorous controlled trials of efficacy. It is difficult for both dermatologists and consumers to make informed decisions in a market that is yet to be clearly defined and regulated. We elucidate the scientific basis for, as well as the literature behind, common active ingredients found in products intended to reverse photoaging, discuss some interesting new activities, and provide a review of several comprehensive studies on over-the-counter (OTC) products.
2-Dimethylaminoethanol (DMAE) (also known as deanol) has been used as an ingredient in skin care, and in cognitive function- and mood-enhancing products. It is marketed as a free base or salt, and in theory, the two forms should be equally effective and able to substitute for each other in pharmaceutical formulations. Detecting possible alterations in the active principle is a basic part of preformulation studies. Accordingly, this study compared DMAE and DMAE bitartrate to identify potential alterations or differences between the free base and the salt that might compromise the long-term stability of cosmetic preparations at different temperatures, and also compared the behavior of the base substance and derivative alone and in solution. Samples were analyzed with different physicochemical methods such as differential scanning calorimetry, ultraviolet and infrared spectroscopy, and nuclear magnetic resonance spectroscopy.
One of the main objectives for an aesthetic surgery patient seeking consultation is a desire to look younger and reverse the appearance of aging. Most of these patients also use topical creams in addition to undergoing surgical procedures. Over-the-counter (OTC) anti-aging products are a billion-dollar industry to which even young patients who wish to prevent the aging process contribute.
Many OTC products advertise dramatic results, but there have been relatively little scientific data to support these claims. We reviewed the literature on ingredients commonly found in OTC anti-aging creams. We conclude that although many different compounds are marketed as anti-aging products, studies proving their efficacy are limited. Vitamin C and alpha-hydroxy acids have been the most extensively researched products, and their anti-aging capabilities have been demonstrated in the literature. There have also been some promising studies on vitamin A and vitamin B derivatives. Moisturizers have been shown to increase skin hydration and improve the overall appearance of skin. Studies also indicate that pentapeptides can be effective in decreasing facial wrinkles and roughness. However, botanicals, which have become popular over the last few years, require significantly more research to formulate any positive conclusions for their topical application. As aesthetic surgeons, it behooves us to educate ourselves on the most common ingredients found in topical anti-aging products and their efficacy.
The authors have no financial interest in and receive no compensation from the manufacturers of any of the products mentioned in this article.
The aging population and a desire to maintain a youthful appearance have propelled the recent surge in the U.S. cosmeceuticals market. The rapidly growing number of products claiming to diminish fine lines and wrinkles, decrease redness, smooth texture, and fade discoloration has lead to much confusion and misinformation among dermatologists and consumers alike. Cosmeceuticals can be a useful adjunct to prescription medications and office procedures. Therefore, it behooves us as dermatologists to understand the science behind these products to better educate ourselves and our patients. We present an update of the following categories of cosmeceuticals: antioxidants, growth factors, peptides, anti-inflammatories/botanicals, polysaccharides, and pigment-lightening agents.
Tricutan is a combination product of herbal extracts traditionally used for treatment of skin conditions, together with dimethylaminoethanol. The effectiveness of Tricutan in improving skin firmness and elasticity in photoaged facial skin was examined in a randomised, placebo-controlled, double-blind, split-face study in 28 women, 34-67 years old. Treatment with Tricutan and placebo was given for 4 weeks. Skin firmness and elasticity was evaluated using the speed of propagation of ultrasound shear waves in the skin as end point (Reviscometer RVM 600). The study was completed by 25 women. The Tricutan treatment resulted in a significantly reduced propagation speed indicating increased firmness. There was no immediate effect by Tricutan application on propagation speed. At self evaluation the women evaluated the treatment effect of Tricutan to be significantly better than the treatment effect of placebo. The clinical evaluation also showed Tricutan to give a significantly better treatment result than placebo. Tolerance to Tricutan was generally good. However, three women did not complete the study because of mild irritative contact dermatitis. The results show that Tricutan can increase skin firmness both objectively and subjectively. Further studies are warranted, especially to investigate if Tricutan can delay the need for surgical face-lift procedures.
Paramyosin, a major structural component of thick filaments in invertebrates has been isolated, purified and characterized from whole adult Drosophila melanogaster extracts and a specific polyclonal antibody against it has been prepared. Paramyosin has been identified on the basis of several criteria, including molecular weight, α-helicity, species distribution, capability of fiber formation in vitro and sequence. We have used the immunopurified polyclonal antibody to isolate eight clones from a λgtl1 expression library of Drosophila 1 to 22 h embryo cDNA. The largest clone (pJV9) has been sequenced and encodes the coiled-coil region of D. melanogaster paramyosin that is 47% identical to Caenorhabditis elegans paramyosin.Indirect immunofluorescence in semi-thin sections of adult flies show fluorescence mainly in tubular muscle. Freshly prepared tubular myofibrils decorated with the immunoabsorbed antibody show the A region in the sarcomere as the specific localization of paramyosin. The amount of paramyosin in tubular synchronous muscles of insects appears to be five times higher than in fibrillar insect muscles. There are at least three paramyosin isoforms as shown by isoelectrofocusing separation. The more acidic and less abundant form is phosphorylated as shown by 32P in vivo labeling experiments in adult flies.The developmental pattern of expression of Drosophila paramyosin is presented. This mesoderm-specific protein, immunologically undetectable during gastrulation and early phases of germ band formation, progressively increases during organogenesis to the adult stage. Interestingly, it is also expressed as a major maternal product in the insoluble cytoskeletal fraction of the mature oocyte.
The programmed cell death of the stratified squamous epithelial cells comprising human epidermis culminates in abrupt transition of viable granular keratinocytes (KC) into dead corneocytes sloughed by the skin. The granular cell-corneocyte transition is associated with a loss in volume and dry cell weight but the mechanism for and biological significance of this form of keratinocyte apoptosis remain obscure. We show that terminally differentiated KC extrude into the intercellular spaces of living epidermis the cytoplasmic buds containing randomly congregated components of the cytosol as well as filaggrin, a precursor of the natural moisturizing factor. The discharge of secretory product is reminiscent of holocrine secretion, suggesting the term 'apoptotic secretion' for this novel, essential step in the process of cornification. The secretory product may become a part of the glycocalyx (a.k.a. 'intercellular cement substance' of epidermis) and serve as a humectant that counterbalances the osmotic pressure imposed by the natural moisturizing factor located in the stratum corneum comprised by corneocytes. The apoptotic secretion commences upon secretagouge action of acetylcholine which is synthesized and released by KC. A combination of a cholinergic nicotinic agonist and a muscarinic antagonist which increases intracellular calcium levels is required to trigger the apoptotic secretion. Analysis of the relative amounts of cholinergic enzymes and receptors expressed by KC capable of secretion and the pharmacological profiles of secretion regulation revealed an upward concentration gradient of free acetylcholine in epidermis which may provide for its unopposed secretagogue action via the m1 muscarinic and the alpha7, and alpha9 nicotinic receptor types expressed by KC at the latest stage of their development in the epidermis.
An increasing body of knowledge indicates that the cholinergic system is not confined to the nervous system, but is practically ubiquitous. The present paper will address the question of the non-neuronal cholinergic system in vascular endothelial cells (EC). In tissue sections of human skin, immunohistochemical studies using confocal laser scanning microscopy showed ChAT (choline acetyltransferase) activity in the EC of dermal blood vessels. Positive ChAT immunoreactivity was also demonstrated in monolayer cultures of human umbilical vein EC (HUVEC) and a human angiosarcoma EC line (HAEND). That the synthesizing enzyme is not only present in EC, but also active was shown by measuring ChAT activity. Thus, in HUVEC cultures, ChAT activity amounted to 0.78 +/- 0.15 nmol x mg protein(-1) x h(-1) (n = 3), but was only partially (about 50%) inhibited by the ChAT inhibitor bromoacetylcholine (30 microM). In HPLC measurements, a concentration of 22 +/- 2 pmol acetylcholine (ACh) per 10(6) cells was found (n = 6). However, using a cholinesterase-packed analytical column to check the identity of the acetylcholine peak, the peak height was found to be reduced, although a significant peak still remained, indicating the existence of a compound closely related to ACh. Further immunocytochemical experiments indicated that EC in vitro also express the vesicular acetylcholine transporter (VAChT) system. Preliminary immunoelectron microscopic studies suggest a topographical association of VAChT with endothelial endocytotic vesicles. The presented experiments clearly demonstrate the existence of essential elements of the cholinergic system (ChAT, VAChT, ACh) in the human endothelium. The biological functions of ACh synthesized by endothelial cells are the focus of ongoing research activity.
Premature skin aging, or photoaging, results largely from repeated exposure to ultraviolet (UV) radiation from the sun. Photoaging is characterized clinically by wrinkles, mottled pigmentation, rough skin, and loss of skin tone; the major histologic alterations lie in dermal connective tissue. In recent years, a great deal of research has been done to explain the mechanism by which UV induces dermal damage. This research has enabled the identification of rational targets for photoaging prevention strategies. Moreover, studies that have elucidated photoaging pathophysiology have produced significant evidence that topical tretinoin (all-trans retinoic acid), the only agent approved so far for the treatment of photoaging, also works to prevent it. This article summarizes evidence mainly from studies of human volunteers that provide the basis for the current model of photoaging and the effects of tretinoin.
Acetylcholine is synthesized and released by human epidermal keratinocytes and modulates the adhesion and motility of these cells, To understand the molecular basis of the effects of acetylcholine on keratinocytes, we investigated the presence, pharmacology, structure, and function of nicotinic acetylcholine receptors in human epidermal keratinocytes. Patch-clamp studies indicated that keratinocytes express acetylcholine receptors with ion gating and pharmacologic properties similar to those observed so far only in neurons, and containing the 3 subunit. Specific binding of the receptor-specific ligand 125I--bungarotoxin revealed approximately 5500 binding sites per cell on undifferentiated keratinocytes in cell cultures and approximately 35,400 binding sites per cell on mature keratinocytes freshly isolated from human neonatal foreskins, Antibody binding and polymerase chain reaction experiments demonstrated the presence of 3, 2, and 4 nicotinic receptor subunits. Binding of subunit-specific antibodies indicated that nicotinic receptors were associated with the suprabasal keratinocytes in epidermis and localized to the cell membranes of differentiated keratinocytes in cell cultures. Acetylcholine and the nicotinic agonist nicotine increased cell-substrate and cell-cell adherence of cultured keratinocytes and stimulated their lateral migration. The specific antagonists -bungarotoxin and mecamylamine caused cell detachment and abolished migration. Thus, a nicotinic receptor expressed in keratinocytes may mediate acetylcholine control of keratinocyte adhesion and motility.Keywords: radioligand binding, immuofluorescence, polymerase chain reaction, patch clamp
We have reported previously that human keratinocytes synthesize and secrete acetylcholine and that muscarinic cholinergic drugs have effects on keratinocyte proliferation, adhesion, and migration. This study defines the location of muscarinic acetylcholine receptors in human epidermis and describes some pharmacologic and molecular properties of these receptors. Confocal microscopy employing the anti-muscarinic receptor monoclonal antibody M35 visualized the receptors in the intercellular areas of normal human epidermis. Using immunoelectron microscopy, the receptors appeared to be attached to the keratinocyte plasma membranes. Functional, high-density (Bmax = 8.3 nmol/2 106 cells) and high-affinity (Kd = 21.5 nM) muscarinic receptors were demonstrated by saturable binding of the reversible radioligand [3H]quinuclidinyl benzilate to the surfaces of freshly isolated epidermal cells at 0°C. Receptor proteins were separated by gel electrophoresis. An apparent isoelectric point of pH 4.3 was determined in immunoblots of sodium-cholate-solubilized receptors separated on isoelectric-focusing gels. Three protein bands, two at approximately 60 kDa and one at 95 kDa, were visualized in immunoblots of membrane-bound or solubilized receptors separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis. The covalent, irreversible ligand [33H]propylbenzilylcholine mustard confirmed these results. Thus, human keratinocytes express a heterogeneous population of muscarinic cholinergic receptors. Because human keratinocytes also express nicotinic cholinergic receptors, endogenously secreted acetylcholine may control different biologic processes in these cells by activating different types of their cholinergic receptors.Keywords: immunoelectron microscopy, radioligand binding, immunoblotting, monoclonal antibody M35, confocal microscopy
Acetylcholine mediates cell-to-cell communications in the skin. Human epidermal keratinocytes respond to acetylcholine via two classes of cell- surface receptors, the nicotinic and the muscarinic cholinergic receptors. High affinity muscarinic acetylcholine receptors (mAChR) have been found on keratinocyte cell surfaces at high density. These receptors mediate effects of muscarinic drugs on keratinocyte viability, proliferation, adhesion, lateral migration, and differentiation. In this study, we investigated the molecular structure of keratinocyte mAChR and their location in human epidermis. Polymerase chain reaction amplification of cDNA sequences uniquely present within the third cytoplasmic loop of each subtype demonstrated the expression of the m1, m3, m4, and m5 mAChR subtypes. To visualize these mAChR, we raised rabbit anti-sera to synthetic peptide analogs of the carboxyl terminal regions of each subtype. The antibodies selectively bound to keratinocyte mAChR subtypes in immunoblotting membranes and epidermis, both of which could be abolished by preincubating the anti-serum with the peptide used for immunization. The immunofluorescent staining patterns produced by each antibody in the epidermis suggested that the profile of keratinocyte mAChR changes during epidermal turnover. The semiquantitative analysis of fluorescence revealed that basal cells predominantly expressed m3, prickle cells had equally high levels of m4 and m5, and granula cells mostly possessed m1. Thus, the results of this study demonstrate for the first time the presence of m1, m3, m4, and m5 mAChR in epidermal keratinocytes. Because keratinocytes express a unique combination of mAChR subtypes at each stage of their development in the epidermis, each receptor may regulate a specific cell function. Hence, a single cytotransmitter, acetylcholine, and muscarinic drugs may exert different biologic effects on keratinocytes at different stages of their maturation.
Damage to human skin due to ultraviolet light from the sun (photoaging) and damage occurring as a consequence of the passage of time (chronologic or natural aging) are considered to be distinct entities. Photoaging is caused in part by damage to skin connective tissue by increased elaboration of collagen-degrading matrix metalloproteinases, and by reduced collagen synthesis. As matrix metalloproteinase levels are known to rise in fibroblasts as a function of age, and as oxidant stress is believed to underlie changes associated with both photoaging and natural aging, we determined whether natural skin aging, like photoaging, gives rise to increased matrix metalloproteinases and reduced collagen synthesis. In addition, we determined whether topical vitamin A (retinol) could stimulate new collagen deposition in sun-protected aged skin, as it does in photoaged skin. Sun-protected skin samples were obtained from 72 individuals in four age groups: 18-29 y, 30-59 y, 60-79 y, and 80+ y. Histologic and cellular markers of connective tissue abnormalities were significantly elevated in the 60-79 y and 80+ y groups, compared with the two younger age groups. Increased matrix metalloproteinase levels and decreased collagen synthesis/expression were associated with this connective tissue damage. In a separate group of 53 individuals (80+ y of age), topical application of 1% vitamin A for 7 d increased fibroblast growth and collagen synthesis, and concomitantly reduced the levels of matrix-degrading matrix metalloproteinases. Our findings indicate that naturally aged, sun-protected skin and photoaged skin share important molecular features including connective tissue damage, elevated matrix metalloproteinase levels, and reduced collagen production. In addition, vitamin A treatment reduces matrix metalloproteinase expression and stimulates collagen synthesis in naturally aged, sun-protected skin, as it does in photoaged skin.
Previous studies have demonstrated that muscarinic acetylcholine receptors (mAChRs) are expressed by human skin fibroblasts (HSF). We have identified the molecular subtypes of these receptors by reverse transcription-polymerase chain reaction (RT-PCR), using m1-m5 subtype-specific primers. These experiments showed that only mRNAs for m2, m4, and m5 mAChR subtypes are present in HSF. The RT-PCR products were characterized by restriction analysis and Southern blotting. Northern blot analysis showed the presence of m2 and m4 mAChR RNA. Rabbit antibodies were raised using a synthetic peptide as immunogen corresponding to the C-terminus of the m2 protein and were used to visualize fibroblast mAChRs. Cell membranes of HSF in cell culture and specimens of normal human skin had a unique staining pattern specific for anti-m2 antibody, as well as for antibodies against m4 and m5. In Western blots of fibroblast proteins, the antibodies visualized the m2 receptor at 65 kDa, m4 at 70 kDa, and m5 at 95 kDa. The function of fibroblast mAChRs was examined by measuring muscarinic effects on intracellular free Ca2+ concentration ([Ca2+]i). Muscarine increased transiently [Ca2+]i in cultured HSF. This effect could be abolished by the muscarinic antagonist atropine. Thus, the results of this study showed that HSF express m2, m4, and m5 mAChR subtypes, and that fibroblast mAChRs are coupled to the regulation of [Ca2+]i. J. Cell. Biochem. 74:264–277, 1999. © 1999 Wiley-Liss, Inc.
Acetylcholine acts as a neurotransmitter in the central and peripheral nervous systems in humans. However, recent experiments demonstrate a widespread expression of the cholinergic system in non-neuronal cells in humans. The synthesizing enzyme choline acetyltransferase, the signalling molecule acetylcholine, and the respective receptors (nicotinic or muscarinic) are expressed in epithelial cells (human airways, alimentary tract, epidermis). Acetylcholine is also found in mesothelial, endothelial, glial, and circulating blood cells (platelets, mononuclear cells), as well as in alveolar macrophages. The existence of non-neuronal acetylcholine explains the widespread expression of muscarinic and nicotinic receptors in cells not innervated by cholinergic neurons. Non-neuronal acetylcholine appears to be involved in the regulation of important cell functions, such as mitosis, trophic functions, automaticity, locomotion, ciliary activity, cell-cell contact, cytoskeleton, as well as barrier and immune functions. The most important tasks for the future will be to clarify the multiple biological roles of non-neuronal acetylcholine in detail and to identify pathological conditions in which this system is up- or down-regulated. This could provide the basis for the development of new therapeutic strategies to target the non-neuronal cholinergic system.
The pharmacotherapy of minimal brain dysfunction (MBD) is reviewed.
Studies using central nervous system (CNS) stimulants (amphetamines and methylphenidate, deanol, pemoline, caffeine), antidepressants (imipramine and desipramine), anticonvulsants (phenytoin and primidone), antianxiety agents (chlordiazepoxide, hydroxyzine, meprobamate), antipsychotic agents (phenothiazines, thioxanthenes, butyrophenones) and miscellaneous agents (benztropine, thyrotropin-releasing hormone, megavitamins) are discussed.
When drugs are indicated, the CNS stimulants are the agents of choice in the treatment of MBD. The use of tricyclic antidepressants in MBD is regarded as investigational and warrants careful monitoring to minimize toxicities. Anticonvulsants have been ineffective in controlling behavior problems; however, phenytoin may be helpful in auditory perception problems. Anti-anxiety and antipsychotic agents are not as desirable as the CNS stimulants for treatment since they do not decrease distractibility or increase attention spans.
Deanol, a putative acetylcholine precursor, has been used as a treatment for childhood hyperactivity for years. Efficacy has not been satisfactorily established, however. Seventy-four children referred for problems with learning, including many with hyperactivity, were screened for neurological or psychiatric illness, then given deanol, methylphenidate, or placebo in a double-blind fashion for 3 months. Maintenance dose for methylphenidate was 40 mg daily; for deanol, 500 mg. Behavior rating forms, reaction time, and a series of standard psychometric tests were given before and after treatment. Both drugs showed significant improvement on a number of tests; the pattern and degree of change differed slightly for the two. In this paradigm, deanol thus appeared to improve performance in children with learning and behavior disorders. The mechanism of action remains speculative; proof that deanol increases acetylcholine is scanty, and there is a theoretical basis for actually assuming an anticholinergic effect. Further clinical studies on deanol are indicated.
Administration of choline chloride, deanol, or Deaner ® to rats subsequently killed by microwave irradiation caused an increase in the concentration of both choline and acetylcholine in the corpus striatum, indicating that synthesis of brain acetylcholine can be stimulated in vivo by elevating the tissue concentration of its precursor. This finding suggests that the concentration of free choline in brain is below that necessary for a maximal rate of synthesis of acetylcholine, and raises the possibility that the availability of choline in brain may regulate the rate of synthesis of acetylcholine. These results also provide biochemical evidence for the view that the clinical effects of deanol result from its conversion to acetylcholine.
Acetylcholine signals through two types of unrelated membrane receptors referred to as nicotinic (nAChR) and muscarinic (mAChR) acetylcholine receptors. Nicotinic acetylcholine receptors were the first neurotransmitter receptors to be purified, cloned, and sequenced, and much is known about these proteins. In contrast, until 5 years ago relatively little was known about the muscarinic receptors. Since then there has been an explosion of information concerning the structure, signaling, and regulation of what is now known to be a family of muscarinic receptors. This review discusses the five identified members of the mAChR family and their coupling to the multiple G proteins that allow mAChRs to modulate many different types of signal transduction pathways. The five members of this family that have been identified so far have striking homology in their hydrophobic membrane domains but possess distinct cytoplasmic domains between the fifth and sixth membrane-spanning regions. These cytoplasmic domains appear to contain important determinants for receptor/G protein interaction and are likely to contain phosphorylation sites that regulate these interactions. mAChR agonists have been shown to induce phosphorylation of mAChR in intact cells, and the evidence that suggests that receptor phosphorylation may play a role in the regulation of receptor function is discussed.
Muscarinic receptors can be pharmacologically classified into 3 types at the present time, however, five genes for the receptor have been identified. The muscarinic receptor types have unique antagonist selectivity, distribution and are linked to specific second messenger systems. The interaction between the muscarinic receptor types and G proteins may depend on the systems in which the receptors are integrated. Expression of the cloned gene in mammalian cells will be useful in delineating the relationships between the pharmacological types of muscarinic receptors and their genes and studying the interactions between the receptor, G proteins, and second messenger coupling.
The ADP-Fe(II)-H2O2 system generates OH free radicals which can be trapped by 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) thus yielding a measurable signal by electron spin resonance spectroscopy. The amount of DMPO-OH spin adduct formed under certain conditions decreased considerably, if dimethylaminoethanol (DMAE), p-chlorophenoxyacetic acid (PCPA) or centrophenoxine (CPH) were present in comparable concentrations to that of DMPO. It has been demonstrated that such an effect cannot be attributed to any interference of the tested compounds with the Fe(II) and its oxidability by H2O2. The reaction of DMAE with OH free radicals was demonstrated also by using other spin traps. These spin traps reacted with OH free radicals either not at all (phenyl-tert-butylnitrone, PBN) or only to a slight extent (alfa-pyridyl-l-oxide-N-tert-butylnitrone, 4-POBN). DMAE was also a competitive OH free radical scavenger with proline and hydroxyproline, both of which have recently been shown to react with OH free radicals to form nitroxyl free radicals. On the basis of the experimental results, the OH free radical scavenger property of DMAE can be regarded as firmly established. This result supports the molecular mechanism proposed for the explanation of the anti-aging effects of CPH in terms of the membrane hypothesis of aging.
The amnesias characteristic of Alzheimer's disease and other age-related dementias are refractory to conventional pharmacotherapy. A recent strategy is to combine present drugs, to improve their memory enhancing effect. We utilize mice weakly trained on active avoidance in a T-maze in order to compare the effect on retention test performance of cholinergic drugs given alone and in two-drug and three-drug combinations. All drugs were injected intraventricularly immediately after training. Memory retention was tested one week later. A dose-response curve was determined for each of four drugs (arecoline, edrophonium, oxotremorine, deanol) and for several of their fixed-ratio combinations. The results indicate that each drug and each combination improved retention test performance up to an optimal dose; the improvement decreased with further increases in dose. A striking reduction (as much as 95%) in the optimal dose for enhanced retention was observed with these two-drug combinations, and further reduction with a three-drug combination. The practical implications of planned drug interactions as an improved means of treating amnesias associated with aging are under investigation.
Water-insoluble protein fractions increase in the brain cortical tissue and liver of rats during aging in both sexes. This suggests a possible increase in the cross-linking of proteins which may be due to the formation of, for example, hydroxyl free radicals during several metabolic processes. In vivo application of centrophenoxine causes a reversal of this phenomenon in old rats. In vitro experiments show that the generation of hydroxyl free radicals by chemical systems like homolysis of H2O2 by redox coupling with Fe2+ leads to Fe3+ conversion, results in the cross-linking of bovine serum albumin and the mixed proteins of liver or brain homogenates of young rats. The cross-linked proteins have a very much increased molecular weight, they become mostly insoluble even in 6 M urea. Dimethylaminoethanol, the effective part of the centrophenoxine molecules, is able to diminish the extent of cross-linking, acting most probably as a free-radical scavenger. The results are discussed in terms of the "membrane hypothesis of aging". A molecular basis is proposed for the anti-aging effect of centrophenoxine.
Administration of 2-dimethylaminoethanol (deanol) to mice induced an increase in both the concentration and the rate of turnover of free choline in blood. Treatment with deanol also caused an increase in the concentration of choline in kidneys, and markedly inhibited the rates of oxidation and phosphorylation of intravenously administered [3H-methyl]choline. In the liver, deanol inhibited the rate of phosphorylation of [3H-methyl]choline, but did not inhibit its rate of oxidation or cause an increase in the level of free choline. These findings suggest that deanol increases the choline concentration in blood by inhibition of its metabolism in tissues. Deanol may ultimately produce its central cholinergic effects by inhibition of choline metabolism in peripheral tissues, causing free choline choline to accumulate in blood, enter the brain, and stimulate cholinergic receptors.
We previously reported that normal human keratinocytes express muscarinic receptors, and that acetylcholine induces attachment of these cells to each other. We have now studied the ability of human keratinocytes to synthesize, secrete, and degrade acetylcholine. To detect and localize the synthesizing enzyme choline acetyltransferase and degrading enzyme acetylcholinesterase, cultured cells and cryostat sections of normal human skin were pre-incubated with specific monoclonal antibodies and stained with an avidin-biotin complex/alkaline phosphatase. The choline acetyltransferase activity was assessed by the conversion of [3H]acetyl CoA to [3H]acetylcholine, and newly synthesized [3H]acetylcholine was detected using thin-layer chromatography. The acetylcholinesterase activity was measured spectrophotometrically. Both cholinergic enzymes were present in cultured keratinocytes, and in basal, spinous and granular epidermal cell layers. Choline acetyltransferase was visualized in the vicinity of cell nuclei, and acetylcholinesterase was observed in or near cell membranes. Newly synthesized acetylcholine was detected in both cell homogenates and culture supernatants. The estimated Vmax of the synthesis of labeled acetylcholine by homogenized keratinocytes was about 20 pmoles acetylcholine produced/mg protein/min at 37 degrees C. A single keratinocyte synthesized a mean of 2 x 10(-17) moles, and released 7 x 10(-19) moles acetylcholine per minute. Both cell homogenates and culture supernatants exhibited similar acetylcholinesterase activities indicating that human keratinocytes secrete acetylcholinesterase, too. Thus, we have demonstrated that normal human keratinocytes possess choline acetyltransferase and acetylcholinesterase, and synthesize, store, release, and degrade acetylcholine. Because human keratinocytes can also respond to acetylcholine, we believe that keratinocyte acetylcholine works in the epidermis as a local hormone.
Muscarinic receptor density increased by approximately 36% after differentiation induced by retinoic acid (Bmax, control = 126 +/- 13 fmol/mg protein; Bmax, retinoic acid-treated = 170 +/- 17 fmol/mg protein; P < 0.05), corresponding to a 170% increase in receptor content per cell. The affinity of [3H]NMS for the receptors was somewhat lower in the retinoic acid-treated cells (Kd, control = 0.14 +/- 0.04 nM; Kd, retinoic acid-treated = 0.25 +/- 0.04 nM; P < 0.05). Reverse transcriptase/polymerase chain reaction analysis using subtype-specific primers revealed that undifferentiated Sk-N-SH cells transcribed mRNA for all 5 receptor subtypes; this pattern was not affected by retinoic acid treatment. [3H]NMS displacement curves with subtype selective receptor ligands (pirenzepine, m1; AFDX-116, m2; 4-DAMP, m3) indicated the predominant expression of m3 and m1 receptor subtypes, and differentiation did not affect the pharmacological profile of the expressed receptor populations. The present results indicate that differentiation induces selective changes in the expression and activity of muscarinic receptors in a neuronal cell line.
In human embryonic lung fibroblasts, transforming growth factor-beta 1 (TGF-beta 1) induced a time-dependent down-regulation of M2 muscarinic receptor binding sites as measured with the nonselective hydrophilic ligand [3H]N-methylscopolamine (NMS). This down-regulation was slow, with 58% loss of all receptors after 24 hr of treatment. The affinity of [3H]NMS for the remaining sites was unaltered by TGF-beta 1. The loss in [3H]NMS binding was accompanied by reduced adenylyl cyclase activity and functional desensitization of M2 muscarinic receptors. Northern blot analyses showed a 72% decrease in the steady state levels of m2 muscarinic receptor mRNA after 24-hr TGF-beta 1 treatment. Recovery of m2 muscarinic receptor mRNA after TGF-beta 1 treatment was slow, with a half-life of approximately 8 hr. There was no effect of TGF-beta 1 on the m2 muscarinic receptor mRNA half-life measured in the presence of actinomycin D, but the rate of m2 muscarinic receptor gene transcription measured with nuclear run-on assay was reduced by 50%, indicating reduced gene transcription. Cycloheximide (10 micrograms/ml) pretreatment abolished the TGF-beta 1 effect, indicating that de novo protein synthesis was required for receptor downregulation. In summary, we have shown that TGF-beta 1 induced desensitization and down-regulation of M2 muscarinic receptor protein and gene that was mediated through reduction in the rate of m2 receptor gene transcription.
Human epidermal keratinocytes synthesize, secrete, and degrade acetylcholine and use their cell-surface nicotinic and muscarinic cholinergic receptors to mediate the autocrine and paracrine effects of acetylcholine. Because acetylcholine modulates transmembrane Ca2+ transport and intracellular metabolism in several types of cells, we hypothesized that cholinergic agents might have similar effects on keratinocytes. Nicotine increased in a concentration-dependent manner the amount of 45Ca2+ taken up by keratinocytes isolated from human neonatal foreskins. This effect was abolished in the presence of the specific nicotinic antagonist mecamylamine, indicating that it was mediated by keratinocyte nicotinic acetylcholine receptor(s). The sequences encoding the α5 and α7 nicotinic receptor subunits were amplified from cDNA isolated from cultured keratinocytes. These subunits, as well as the α3, β2, and β4 subunits previously found in keratinocytes, can be components of Ca2+-permeable nicotinic receptor channels. To learn how activation of keratinocyte nicotinic receptors affected the race of cell differentiation, we measured the nicotinic cholinergic effects on the expression of differentiation markers by cultured keratinocytes. Long-term incubations with micromolar concentrations of nicotine markedly increased the number of cells forming cornified envelopes and the number of cells staining with antibodies to suprabasal keratin 10, transglutaminase type I, involucrin, and filaggrin. The increased production of these differentiation-associated proteins was verified by Western blotting. Because nicotinic cholinergic stimulation causes transmembrane Ca2+ transport into keratinocytes, and because changes in concentrations of intracellular Ca2+ are known to alter various keratinocyte functions, including differentiation, the subcellular mechanisms mediating the autocrine and paracrine actions of epidermal acetylcholine on keratinocytes map involve Ca2+ as a second messenger.
Human epidermal keratinocytes possess cholinergic enzymes, which synthesize and degrade acetylcholine, and express both nicotinic and muscarinic classes of cholinergic receptors on their cell surfaces. These receptors bind acetylcholine and initiate cellular response. The presence in keratinocytes of a functional cholinergic system suggests a role for acetylcholine in most, if not all, aspects of keratinocyte function. Autocrine and paracrine acetylcholine are required to sustain the viability of keratinocytes in vitro, and cholinergic drugs can alter keratinocyte proliferation, adhesion, migration, and differentiation. Acetylcholine employs calcium as a mediator for its effects on keratinocytes. In turn, changes in calcium concentration may affect expression and function of keratinocyte cholinergic enzymes and cholinergic receptors. At different stages of their differentiation, keratinocytes may demonstrate unique combinations of cholinergic enzymes and cholinergic receptor types. This would allow basal, prickle, and granular keratinocytes to respond to acetylcholine differently, in accordance with their functions at each stage of keratinocyte development in epidermis.
1. Acetylcholine (ACh) represents one of the most exemplary neurotransmitters. In addition to its presence in neuronal tissue, there is increasing experimental evidence that ACh is widely expressed in pro- and eukaryotic non-neuronal cells. Thus, ACh has been detected in bacteria, algae, protozoa, tubellariae and primitive plants, suggesting an extremely early appearance of ACh in the evolutionary process.
2. In humans, ACh and/or the synthesizing enzyme, choline acetyltransferase, has been demonstrated in epithelial cells (airways, alimentary tract, urogenital tract, epidermis), mesothelial (pleura, pericardium) and endothelial and muscle cells. In addition, immune cells express the non-neuronal cholinergic system (i.e. the synthesis of ACh can be detected in human leucocytes (granulocytes, lymphocytes and macrophages)), as well as in rat microglia in vitro.
3. The widespread expression of non-neuronal ACh is accompanied by the ubiquitous expression of cholinesterase activity, which prevents ACh from acting as a classical hormone.
4. Non-neuronal ACh mediates its cellular actions in an auto- and paracrine manner via the activation of the widely expressed nicotinic and muscarinic acetylcholine receptors, which can interfere with virtually all cellular signalling pathways (ion channels and key enzymes).
5. Non-neuronal ACh appears to be involved in the regulation of basic cell functions, such as mitosis, cell differentiation, organization of the cytoskeleton, cell–cell contact, secretion and absorption. Non-neuronal ACh also plays a role in the regulation of immune functions. All these qualities together may mediate the so-called ‘trophic property’ of ACh.
6. Future experiments should be designed to analyse the cellular effects of ACh in greater detail. The involvement of the non-neuronal cholinergic system in the pathogenesis of chronic inflammatory diseases should be investigated to open up new therapeutic strategies.
Previous studies have demonstrated that muscarinic acetylcholine receptors (mAChRs) are expressed by human skin fibroblasts (HSF). We have identified the molecular subtypes of these receptors by reverse transcription-polymerase chain reaction (RT-PCR), using m1-m5 subtype-specific primers. These experiments showed that only mRNAs for m2, m4, and m5 mAChR subtypes are present in HSF. The RT-PCR products were characterized by restriction analysis and Southern blotting. Northern blot analysis showed the presence of m2 and m4 mAChR RNA. Rabbit antibodies were raised using a synthetic peptide as immunogen corresponding to the C-terminus of the m2 protein and were used to visualize fibroblast mAChRs. Cell membranes of HSF in cell culture and specimens of normal human skin had a unique staining pattern specific for anti-m2 antibody, as well as for antibodies against m4 and m5. In Western blots of fibroblast proteins, the antibodies visualized the m2 receptor at 65 kDa, m4 at 70 kDa, and m5 at 95 kDa. The function of fibroblast mAChRs was examined by measuring muscarinic effects on intracellular free Ca2+ concentration ([Ca2+]i). Muscarine increased transiently [Ca2+]i in cultured HSF. This effect could be abolished by the muscarinic antagonist atropine. Thus, the results of this study showed that HSF express m2, m4, and m5 mAChR subtypes, and that fibroblast mAChRs are coupled to the regulation of [Ca2+]i.
It is still a matter of debate whether HRT improves the physical quality of sun damaged skin.
To compare in a prospective longitudinal study the effects of climacteric aging controlled or not by HRT upon the tensile properties of facial skin.
A total of 140 women aged 40-52 years were enrolled in the study. The HRT group comprised 90 volunteers and a control group encompassed 50 non recipient volunteers. Yearly measurements of tensile functions of facial skin were performed for 5 years. A computerized suction device equipped with a 2-mm diameter hollow probe derived tensile variables quantifying skin distensibility, viscosity and elasticity.
Climacteric aging was characterized by increased skin distensibility (1.1% per year) and viscosity (1.3% per year) mirrored by a decrease in elasticity (1.5% per year). HRT helped mitigate such changes. However, the HRT efficacy was not similar in all volunteers. Groups of good and poor responders were clearly identified as far as benefit on skin elasticity was concerned.
The beneficial effect of HRT upon climacteric skin aging of the face is confirmed, at least in a subgroup of menopausal women.
Aging of the skin is a complex phenomenon resulting from the interaction of several intrinsic and extrinsic factors [1]. Due to the cosmetic disfigurement it produces and its psychological impact, especially to women, aging of the skin has become an issue of great social significance and concern. Intrinsic aging is an inevitable, genetically programmed process, the underlying mechanisms of which remain largely unknown. No prevention or effective treatment is currently available [1]. Among extrinsic influences (wind, heat, cigarette smoke, chemicals, etc.), ultraviolet radiation appears to be the single most important factor associated with aging of the skin [2]. Photoaging refers to gross and microscopic cutaneous changes induced by cumulative exposure to ultraviolet radiation (UVR). These changes are superimposed on the background of intrinsic aging [2]. Increased recreational sun exposure, including excessive sunbathing, the depletion of stratospheric ozone, the use of UVR in the treatment of various skin diseases, are some of the causes that have led to increased prevalence of photoaging during the last decades. The clinical importance of photoaging lies mostly on the potential for the development of precancerous lesions or skin cancer [3]. In contrast to intrinsic aging, photodamage can be prevented by sun avoidance and proper sun protection [2]. Furthermore, overwhelming clinical and histological evidence indicate that skin changes of photoaging can be reversed by the use of topical retinoids [4].
The in vivo visco-elastic characteristics of skin depend on a series of physiopathological parameters. Among them, the age-related intrinsic tensile properties and the preconditioning of the tissues set under tension by the hypodermal volume might be of importance.
To revisit the influence of age and body mass on the firmness and mechanical anisotropy of the skin as determined by the velocity of the shear wave propagation.
Resonance running time measurements (RRTM) were performed on the mid volar forearm in 110 adults of both sexes. In each subject 16 RRTM were collected at four different precise angles with regard to the limb axis. We recorded the lowest, the highest and the mean multidirectional RRTM as well as the coefficient of variation (CV) of the latter value. In addition, the body mass index (BMI) was calculated.
Age and BMI did not influence the minimum RRTM. In contrast, the maximum RRTM as well as the mean and CV of the multidirectional RRTM, significantly rose in a progressively increasing proportion of the subjects older than 60 years. These changes were only encountered in subjects with a normal BMI ranging from 18 to 25. Sex-related differences were not disclosed.
The intrinsic skin tension lines identified by the minimum RRTM are not significantly altered with age and BMI variations. In contrast, skin laxity identified by larger maximum and mean multidirectional RRTM may increase after 60 years of age in subjects with a normal BMI. This is accompanied by increased skin mechanical anisotropy identified by CV values of the multidirectional RRTM over 40%.
Premature skin aging, or photoaging, results largely from repeated exposure to ultraviolet (UV) radiation from the sun. Photoaging is characterized clinically by wrinkles, mottled pigmentation, rough skin, and loss of skin tone; the major histologic alterations lie in dermal connective tissue. In recent years, a great deal of research has been done to explain the mechanism by which UV induces dermal damage. This research has enabled the identification of rational targets for photoaging prevention strategies. Moreover, studies that have elucidated photoaging pathophysiology have produced significant evidence that topical tretinoin (all-trans retinoic acid), the only agent approved so far for the treatment of photoaging, also works to prevent it. This article summarizes evidence mainly from studies of human volunteers that provide the basis for the current model of photoaging and the effects of tretinoin.
Tretinoin and AHAs are dependable components of any skin-rejuvenation program. These products are well studied, and the results are predictable. Antioxidants make biologic sense; the initial claims were far-reaching, but there is evidence to support their use in the prevention of photoaging. Microdermabrasion has many potential applications. Epidermal level treatment is enjoying popular appeal; however, the efficacy for epidermal level treatment of photoaging has yet to be established. New products and treatments will come, and others will go. Most importantly, clinicians should remain scientists, not salespeople, in the quest for the silver bullet to combat photoaging.
The present study was designed to identify and characterize muscarinic acetylcholine receptors in normal human melanocytes. We used subtype-specific oligonucleotide primers to localize the five genetically defined mAChR mRNAs (ml through m5) by reverse transcription-polymerase chain reaction. These experiments showed that all five mAChR subtype mRNAs are expressed in melanocytes. The PCR products were verified by restriction analysis and Southern blotting. Receptors were visualized in cultures of normal human melanocytes and specimens of normal human skin by subtype-specific rabbit anti-receptor polyclonal antibodies. Radioligand binding assays with the lipophilic drug [3H]quinuclidinyl benzilate demonstrated approximately 9,000 high affinity binding sites/cell. Micromolar concentrations of muscarine or carbachol transiently increased intracellular Ca2+, which could be attenuated by atropine, demonstrating coupling of the receptors to mobilization of intracellular free Ca2+. Lower concentrations of muscarine induced spontaneous repetitive spike-like increases of intracellular Ca2+ which is characteristic for the activation of muscarinic receptors. These results indicate that normal human skin melanocytes express the ml, m2, m3, m4, and m5 subtypes of classic muscarinic acetylcholine receptors on their cell membrane and that these receptors regulate the concentration of intracellular free Ca2+, which may play an important physiologic role in melanocyte behavior and skin pigmentation.
As was shown in a recent review by this author (Ann. N.Y. Acad. Sci., 928: 187-199, 2001), oxyradicals cannot be considered only as harmful by-products of the oxidative metabolism, but living cells and organisms implicitly require their production. This idea is supported by numerous facts and arguments, the most important of which is that the complete inhibition of the oxyradical production by KCN (or by any block of respiration) kills the living organisms long before the energy reserves would be exhausted. This new theoretical approach not only helps our understanding of the normal functions of the living organisms, such as the basic memory mechanisms in the brain cells, but also helps in identifying the site-specific, radical-induced damaging mechanisms that represent the undesirable side effects of oxygen free radicals. First of all, these effects make the cell plasma membrane vulnerable and cause a series of intracellular functional disorders, as described by the membrane hypothesis of aging (MHA). The logical way for any antiaging intervention therefore should be to increase the available number of loosely bound electrons inside the plasma membrane that are easily accessible for OH(*) free radical scavenging. The present review summarizes the available knowledge regarding the theory of the use of membrane-related antiaging pharmaca, like centrophenoxine (CPH), tested in both animal experiments and human clinical trials. A modified, developed version of CPH coded as BCE-001 is also reported.
This study was performed to characterize the mechanism of choline transport into human keratinocytes. Uptake of [3H]choline was measured both in the HaCaT cell line and in native keratinocytes. Uptake in HaCaT cells was linear with time at least up to 10 min. There was little dependence of choline transport on sodium. Choline uptake was slightly stimulated by extracellular H+ with the pH optimum being 7.5. The uptake rate was saturable and indicated participation of a single transport system (Kt = 14.8 +/- 1.0 micro M, Vmax = 1.0 +/- 0.01 nmol per 10 min per mg protein). The choline uptake into HaCaT cells was inhibited by unlabeled choline, hemicholinium-3, and acetylcholine. The prototypical organic cation tetraethylammonium showed very little affinity for the choline uptake system in these cells. Several cationic drugs such as diphenhydramine, clonidine, and atropine also interacted with the transport system. Choline uptake in normal keratinocytes was very similar to that in HaCaT cells with respect to substrate specificity and affinity. We conclude that keratinocytes express a Na+ independent, high-affinity choline transport system. This system accepts many pharmacologically important organic cations as substrates. It is similar or identical to the choline carrier described in intestinal epithelial cells and in endothelial cells of the blood-brain barrier. The choline carrier seems to have relevance not only for the uptake of cationic drugs into the keratinocytes but also for the biosynthesis of skin lipids.
Beyond subjective assessments, the effect of skin tensors is difficult to assess. The present 2-phase randomized double-blind split face study was designed to compare the effect of a gel containing 3% 2-dimethylaminoethanol (deanol, DMAE) with the same formulation without DMAE.
In a first pilot study, sensorial assessments and measures of the skin distension under suction were performed in eight volunteers. In a second study conducted in 30 volunteers, shear wave propagation was measured.
Large interindividual variations precluded any significant finding in the first study. The DMAE formulation showed, however, a significant effect characterized by increased shear wave velocity in the direction where the mechanical anisotropy of skin showed looseness.
The DMAE formulation under investigation increased skin firmness.
Cutaneous aging is a complex biological phenomenon affecting the different constituents of the skin. To compare the effects of intrinsic and extrinsic aging processes, a total of 83 biopsies were collected from sun-exposed and protected skin of healthy volunteers representing decades from the 1st to the 9th (6-84 years of age). Routine histopathology coupled with computer-assisted image analysis was used to assess epidermal changes. Immunoperoxidase techniques with antibodies against type I and type III collagens and elastin were used to quantitatively evaluate changes in collagen and elastic fibers and their ultrastructure was examined by transmission electron microscopy. Epidermal thickness was found to be constant in different decades in both sun-exposed and protected skin; however, it was significantly greater in sun-exposed skin (P = 0.0001). In protected skin, type I and III collagen staining was altered only after the 8th decade, while in sun-exposed skin the relative staining intensity significantly decreased from 82.5% and 80.4% in the 1st decade to 53.2% and 44.1% in the 9th decade, respectively (P = 0.0004 and 0.0008). In facial skin the collagen fiber architecture appeared disorganized after the 4th decade. The staining intensity of elastin in protected skin significantly decreased from 49.2% in the 1st decade to 30.4% in the 9th decade (P = 0.05), whereas in sun-exposed skin the intensity gradually increased from 56.5% in the 1st decade to 75.2% in the 9th decade (P = 0.001). The accumulated elastin in facial skin was morphologically abnormal and appeared to occupy the areas of lost collagen. Collectively, the aging processes, whether intrinsic or extrinsic, have both quantitative and qualitative effects on collagen and elastic fibers in the skin.
Human skin, like all other organs, undergoes chronological aging. In addition, unlike other organs, skin is in direct contact with the environment and therefore undergoes aging as a consequence of environmental damage. The primary environmental factor that causes human skin aging is UV irradiation from the sun. This sun-induced skin aging (photoaging), like chronological aging, is a cumulative process. However, unlike chronological aging, which depends on the passage of time per se, photoaging depends primarily on the degree of sun exposure and skin pigment. Individuals who have outdoor lifestyles, live in sunny climates, and are lightly pigmented will experience the greatest degree of photoaging. During the last decade, substantial progress has been made in understanding cellular and molecular mechanisms that bring about chronological aging and photoaging. This emerging information reveals that chronological aging and photoaging share fundamental molecular pathways. These new insights regarding convergence of the molecular basis of chronological aging and photoaging provide exciting new opportunities for the development of new anti-aging therapies. This article reviews our current understanding and presents new data about the molecular pathways that mediate skin damage by UV irradiation and by the passage of time.
Smoking is associated with aberrant cutaneous tissue remodeling, such as precocious skin aging and impaired wound healing. The mechanism is not fully understood. Dermal fibroblasts (DF) are the primary cellular component of the dermis and may provide a target for pathobiologic effects of tobacco products. The purpose of this study was to characterize a mechanism of nicotine (Nic) effects on the growth and tissue remodeling function of DF. We hypothesized that the effects of Nic on DF result from its binding to specific nicotinic acetylcholine receptors (nAChRs) expressed by these cells and that downstream signaling from the receptors alters normal cell functioning, leading to changes in skin homeostasis. Using RT-PCR and Western blotting, we found that a 24-hour exposure of human DF to 10 micro M Nic causes a 1.9- to 28-fold increase of the mRNA and protein levels of the cell cycle regulators p21, cyclin D1, Ki-67, and PCNA and a 1.7- to 2-fold increase of the apoptosis regulators Bcl-2 and caspase 3. Nic exposure also up-regulated expression of the dermal matrix proteins collagen type Ialpha1 and elastin as well as matrix metalloproteinase-1. Mecamylamine (Mec), the specific antagonist of nAChRs, abolished Nic-induced alterations, indicating that they resulted from a pharmacologic stimulation of nAChRs expressed by DF. To establish the relevance of these findings to a specific nicotinergic pathway, we studied human DF transfected with anti-alpha3 antisense oligonucleotides and murine DF from alpha3 nAChR knockout mice. In both cases, lack of alpha3 was associated with alterations in fibroblast growth and function that were opposite to those observed in DF treated with Nic, suggesting that the nicotinic effects on DF were mostly mediated by alpha3 nAChR. In addition to alpha3, the nAChR subunits detected in human DF were alpha5, alpha7, beta2, and beta4. The exposure of DF to Nic altered the relative amounts of each of these subunits, leading to reciprocal changes in [(3)H]epibatidine-binding kinetics. Thus, some of the pathobiologic effects of tobacco products on extracellular matrix turnover in the skin may stem from Nic-induced alterations in the physiologic control of the unfolding of the genetically determined program of growth and the tissue remodeling function of DF as well as alterations in the structure and function of fibroblast nAChRs.
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Age and body mass index-related changes in cutaneous shear wave velocity Vitamin A antagonizes de-creased cell growth and elevated collagen-degrading matrix metalloproteinases and stimulates collagen accumulation in naturally aged human skin
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