Stephan Dähnhardt-Pfeiffer

This pilot study investigated the effects of a 12-week administration of a nutritional supplement containing special collagen peptides on the structural and molecular properties of the collagen fiber network in the human skin. For the assessments, the suction blister method and electron microscopical comparisons were used. Three suction blisters we...

Purpose Cellulose nanocrystals (CNC) play a promising role in the development of new advanced materials. The growing demand of CNC-containing products in the food industry will lead to an increased human exposure through oral uptake. To date, there is a dearth of studies reporting on the risks which CNC pose to human health following ingestion. In...

Epidermal barrier dysfunction can lead to xerotic skin and promote skin disorders like atopic dermatitis. Atopic skin is characterized by reduced water-retaining compounds, altered lipid composition and elevated skin pH. Against this background, a study was conducted to investigate the impact of a specific skin care product on epidermal barrier fun...

In this study, a 96‐well exposure system for safety assessment of nanomaterials is developed and characterized using an air–liquid interface lung epithelial model. This system is designed for sequential nebulization. Distribution studies verify the reproducible distribution over all 96 wells, with lower insert‐to‐insert variability compared to non‐...

Introduction: Basic therapy is of central importance in the treatment of atopic eczema. Using electron microscopic images, the morphology of epidermal skin barrier and its lipids was investigated after application of a lipid foam cream and basic cream. Methods: Patients with two contralateral comparable atopic eczema (local SCORAD 1-10) on the f...

Efficient chemical modification of cellulose nanocrystals (CNCs) by grafting commonly involves aprotic solvents, toxic reactants, harsh reaction conditions, or catalysts, which have negative effects on the particle character, reduced dispersibility and requires further purification, if products are intended for biomedical applications. This work, i...

Nummular (coin-shaped) and classical (flexural) atopic dermatitis differ morphologically, but no other distinguishing features are known. The aim of this study was to determine differences and similarities of both variants in children. Detailed interviews, clinical examinations, biophysical measurements and electron microscopic analyses were perfor...

A deficient epidermal barrier is a key feature of atopic dermatitis (AD) and comprises altered lipid and protein content and composition of the stratum corneum resulting in disturbed water balance. Clinically, eczematous lesions on dry skin and pruritus develop. Pruritic nodules occur in prurigo nodularis (PN), another chronic skin disease, which c...

Preparations containing pigments have been used since ancient times to protect against negative effects of solar radiation. Since the 1950s, sunscreen products containing micronized TiO2 and ZnO have been marketed. These products were soon regarded as cosmetically unattrac-tive due to their property of remaining as a white paste on the skin, a resu...

Zusammenfassung Hintergrund Wundheilungseffekte lassen sich im Modell der restrukturierten humanen Epidermis durch Erzeugung reproduzierbarer Schäden und der Beobachtung der Regeneration der Hautzellen objektivieren. Methoden und Ergebnisse In einer kürzlich veröffentlichten Studie wurde der Effekt einer Creme mit einer Zubereitung aus den oberirdi...

A better understanding of their interaction with cell-based tissue is a fundamental prerequisite towards the safe production and application of engineered nanomaterials. Quantitative experimental data on the correlation between physicochemical characteristics and the interaction and transport of engineered nanomaterials across biological barriers,...

Preparations containing pigments have been used since ancient times to protect against negative effects of solar radiation. In the 1950s, first sunscreens containing particulate ZnO and TiO2 appeared. Particle sizes in these products were such that light was scattered and reflected rendering preparations highly visible on skin. They were soon consi...

Introduction: An accelerated healing of superficial wounds was demonstrated in clinical trials with a topical comfrey preparation (Symphytum × uplandicum Nyman). The effect has previously not been examined in skin models. Methods: An established in vitro model of epidermal cells with the typical strata was used for the observation of effects of...

The transmembrane protein claudin-1 is a major component of epidermal tight junctions (TJs), which create a dynamic paracellular barrier in the epidermis. Claudin-1 downregulation has been linked to atopic dermatitis (AD) pathogenesis but variable levels of claudin-1 have also been observed in healthy skin. To elucidate the impact of different leve...

Background: The epidermal skin barrier and lipids that are integral to its structure are impaired in atopic dermatitis (AD). Current treatment guidelines include proactive therapy. Objective: This study assessed the effect of 12 weeks of proactive treatment with tacrolimus ointment 0.1% (TAC) compared with mometasone furoate cream (MF) on specific...

Steroid hormones became increasingly interesting as active pharmaceutical ingredients for the treatment of endocrine disorders. However, medical applications of many steroidal drugs are inhibited by their very low aqueous solubilities giving rise to low bioavailabilities. Therefore, the prioritized oral administration of steroidal drugs remains pro...

The pH of the skin surface increases with age and thus reduces epidermal barrier function. Aged skin needs appropriate skin care to counterbalance age‐related pH increase and improve barrier function. This confirmatory randomized study investigated the efficacy of water‐in‐oil (w/o) emulsions with either pH 4 or pH 5.8 in 20 elderly subjects after...

Investigation on the aged epidermal barrier function (pH, hydration, TEWL) and lipid bilayer (lipid lamellae, lipid ratio, FFA, CERs, CHOL).

Skin barrier repair therapies often involve the use of medicated and non-medicated topical preparations. To measure the effect of topical preparations, clinical (scoring systems, for example, Score of Atopic Dermatitis, Dermatology Quality of Life Index) and biophysical procedures (e.g., trans-epidermal water loss, skin hydration) are widely used....

Objective: Xerosis is a serious problem among the very old. It is a dermatological challenge caused by significant alterations in stratum corneum (SC) function and structure. Two negative changes in aged skin are: (i) the enhanced skin surface pH and (ii) the altered SC lipid content, composition and ordering. Methods: Therefore, we investigated...

Background: Atopic eczema (AE) is a chronic inflammatory and pruritic skin disease. There is still an unmet need for topical anti-inflammatory and anti-pruritic substances exhibiting an excellent safety profile. The endocannabinoid system is known to regulate various aspects of cutaneous barrier and immune functions, thus targeting it may be a val...

Background/aims: Dry skin, or xerosis, is a common condition and a key feature of skin diseases like atopic dermatitis (AD) and ichthyosis vulgaris. Foot xerosis may exist without underlying disease and could be related to very mild forms of AD or ichthyosis vulgaris. The synthesis of important skin lipids (cholesterol, free fatty acids and cerami...

Die Permeabilitätsbarriere spielt bei zahlreichen Hauterkrankungen eine Rolle. Besonders gut aufgeklärt ist die Bedeutung der Barriere bei ekzematösen Erkrankungen. Bei einem irritativ-toxischen Kontaktekzem ist die Störung der Permeabilitätsbarriere durch irritativ-toxische Noxen der erste Schritt in der Pathogenese. Nur nach Schädigung der Barrie...

Purpose: Two randomized, intra-individual comparison studies were performed in healthy subjects to evaluate the skin moisturization and barrier restoration potential of a new topical panthenol-containing emollient (NTP-CE) (Study 1), and its effect on skin microflora (Study 2). Methods: In study 1 (N = 23), two skin areas, one challenged with 0....

Echinacea purpurea extracts (purple coneflower) are known to have immunemodulatory effects. Several alkamides, as the major lipophilic constituents, bind to cannabinoid receptors 1 and 2. Since the endocannabinoid system is of importance in inflammatory skin diseases, anti-inflammatory activity of alkamides was investigated. Therefore the new lipophil...

Atopic dermatitis is the result of complex interactions between environmental and genetic factors influencing the epidermal structure and function, as well as the immune system. Epidermal changes, including the defective epidermal permeability barrier, have recently been intensively investigated recently and seem to be a hallmark of disease pathoge...

Patients with atopic dermatitis (AD) have an epidermal barrier dysfunction, which allows invasion of allergens to occur. Stratum corneum skin barrier is formed by corneocytes and extracellular lipids extruded from the epidermal lamellar bodies. In a controlled, randomized, double-blinded, right-left comparison study we investigated the effect of pi...

Background: The skin barrier plays a crucial role in the pathophysiology of atopic dermatitis. The quality of the skin barrier can be assessed using a new semi-quantitative method to measure intercellular lipid lamellae. This procedure was used to evaluate the influence of the topical application of the calcineurin inhibitor tacrolimus 0.1% ointme...

Therapy of atopic dermatitis encloses use of medicated and nonmedicated preparations. Results of clinical and biophysical procedures indirectly describe the condition of the impaired skin barrier (SB). Direct evaluation of SB integrity is only possible by electron microscopical visualization, e.g. intercellular lipid lamellae (ICLL) organization of...

Genetic defects leading to skin barrier dysfunction were recognized as risk factors for atopic dermatitis (AD). It is essential that drugs applied to patients with AD restore the impaired epidermal barrier to prevent sensitization by environmental allergens. We investigated the effect of 2 common treatments, a calcineurin inhibitor and a corticoste...

The skin's permeability barrier protects against extensive water loss and prevents the entry into the skin of harmful substances like irritants, allergens and microorganisms. The permeability barrier is mainly located in the stratum corneum and consists of corneocytes and a lipid-enriched intercellular domain. The barrier is formed during epidermal...

Tinea corporis is a superficial mycotic infection resulting in substantial epidermal changes. We determined skin barrier function, epidermal differentiation, and human-β-defensin 2 (hBD-2) protein expression in 10 patients with tinea corporis caused by Trichophyton rubrum (T. rubrum). We found disturbed skin barrier function as shown by a significa...

In this article, we report on the adaptation of high-pressure freezing and freeze-substitution (HPF-FS) for ultrastructural analysis of leaf tissue with special emphasis on chloroplasts. To replace the gas in the intercellular spaces, a mixture of water and methanol (MeOH) was employed. We compared three different supplements for FS--osmiumtetroxid...

High-pressure freezing (HPF) in combination with freeze substitution (FS) was used to analyse changes in the structure of barley chloroplasts during the daily change of light and darkness. In contrast to conventional treatment of samples, HPF-FS revealed substantial differences in chloroplast shape, volume and ultrastructure in the light period and...

We previously demonstrated that the aspartate protease cathepsin D is activated by ceramide derived from acid sphingomyelinase. Increased expression of cathepsin D in the skin has been reported in wound healing, psoriasis and skin tumors. We explored specific functions of cathepsin D during epidermal differentiation. Protein expression and enzymati...

Cryopreparation of skin samples: A comparison between ultrathin cryosections and resin embedded sections of human skin - Volume 9 Issue S02 - Roger Wepf, Stephan Pfeiffer, Tobias Richter, Katja Dunckelmann, Stefan Biel, K. -P. Wittern

Successive visualisation of identical plant cells by light and electron microscopy is reported. For this purpose segments of pea and barley leaves were prepared by high-pressure freezing, freeze-substitution, and low-temperature embedding. The use of Safranin O during low-temperature dehydration allowed, on one hand, staining of all cellular compon...

The effectiveness of sunscreens was originally achieved by incorporation of soluble organic UV absorbers such as cinnamates and others into cosmetic formulations. Determinations of the sun protection factor (SPF) of emulsions containing different organic UV absorbers clearly indicate that the efficacy depends on the absorption characteristics of ea...

Ceramides and glucosylceramides are pivotal molecules in multiple biologic processes such as apoptosis, signal transduction, and mitogenesis. In addition, ceramides are major structural components of the epidermal permeability barrier. The barrier ceramides derive mainly from the enzymatic hydrolysis of glucosylceramides. Recently, anti-ceramide an...

Ceramide is a pivotal molecule in signal transduction and an essential structural component of the epidermal permeability barrier. The epidermis is marked by a high concentration of ceramide and by a unique spectrum of ceramide species: Besides the two ceramide structures commonly found in mammalian tissue, N-acylsphingosine and N-2-hydroxyacyl-sph...

Electron microscopy visualisation and light microscopic investigations of three different application forms of titanium dioxide proved that neither surface characteristics, particle size nor shape of the micronised titanium dioxide result in any dermal absorption of this substance: Micronised titanium dioxide is solely deposited on the outermost su...

Current transmission electron microscopy techniques do not permit simultaneous visualization of skin ultrastructure and stratum corneum extracellular lipids. We developed a new procedure, which entails application of high-pressure freezing followed by freeze-substitution with acetone containing uranyl acetate, followed by low temperature embedding...

The stratum corneum requires ceramides, cholesterol, and fatty acids to provide the cutaneous permeability barrier. The lipids are organized in intercellular membranes exhibiting short- and long-periodicity lamellar phases. In recent years, the phase behavior of barrier lipid mixtures has been studied in vitro. The relationship of human stratum cor...

In order to help clarify the controversially discussed dermal uptake properties of micronized titanium dioxide (TiO ), we conducted extensive in vitro dermal absorption studies with ’Franz‐type’ diffusion cells on excised porcine skin. After biopsies and chemical fixation, the overall localization of TiO in the skin was analyzed by means of transmi...

A structure preservation of biological and organic samples, close to native state, can only be reached by cryo immobilization techniques. Cryo immobilization allows not only to preserve the high structural integrity but also to arrest dynamic processes in the μs- ms range. After freezing the sample and preparing the surface of interest, it is impor...