[show abstract][hide abstract] ABSTRACT: BACKGROUND: The amount of UV rays that reach the ground as well as the UVA/UVB ratio depend on several factors such as latitude, season, cloud coverage and time of day, both UVA and UVB radiation are responsible of a great variety of skin disorders such as actinic keratoses, non-melanoma skin cancer and melanoma. METHODS: In this work the solar radiation of face and chest is calculated for 80 Mexican-mestizo volunteers using their melanin concentration relative to a non-photoexposed area which were obtained using diffuse reflectance spectrophotometry. RESULTS: The results show that the points of highest solar exposure are cheeks and cleavage, the points with lowest solar exposure are the chin and lower chest. It was also observed that the amount of solar exposure influenced the clinical assessment of skin phototype. CONCLUSION: The results support the concept that proper education on solar preventive measures mainly on the head and cleavage is fundamental to reduce the incidence of photaging and skin cancer, and that diffuse reflectance spectrophotometry can be used to reduce the effect of chronic sun exposure in the determination of the skin phototype.
Biomedical Spectroscopy and Imaging. 08/2013; 2:219-223.
[show abstract][hide abstract] ABSTRACT: Raman spectra of the skin of subjects with nickel allergy are analyzed and compared to the spectra of healthy subjects to detect possible biochemical differences in the structure of the skin that could help diagnose metal allergies in a noninvasive manner. Results show differences between the two groups of Raman spectra. These spectral differences can be classified using principal component analysis. Based on these findings, a novel computational technique to make a fast evaluation and classification of the Raman spectra of the skin is presented and proposed as a noninvasive technique for the detection of nickel allergy.
Journal of Biomedical Optics 06/2013; 18(6):61206. · 2.88 Impact Factor
[show abstract][hide abstract] ABSTRACT: The sticky platelets syndrome (SPS) is a procoagulant condition based on either arterial, venous, or capillary thrombi caused by hyperesponsive and hyperaggregable platelets. This is a frequent disease, which often remains clinically inapparent, until stressful events or combination with other factors increase the risk of developing SPS. The condition is due to a congenital platelet defect with autosomal dominant characteristics, leading to the increased platelet aggregability when they are challenged with epinephrine and adenosine diphosphate. Nowadays classification of this disorder is based on platelet reactivity to both ADP and epinephrine (SPS type 1), epinephrine alone (SPS type 2), and ADP alone (SPS type 3). The diagnoses of the syndrome depend on the functional aggregometer assay. This condition should be taken into account whenever a patient with thrombophilia is considered.
[show abstract][hide abstract] ABSTRACT: Bevacizumab is a humanized monoclonal IgG1 antibody against vascular endothelial growth factor type A, which is used as an anti-angiogenic in metastatic colorectal cancer, lung, kidney and breast cancer among other diseases. In ophthalmol-ogy it is used in very small amounts, therefore the stability and effectiveness of the drug over time becomes an issue. In this study the molecular stability of bevacizumab is determined using Raman spectroscopy as a function of the storage technique used. The results show that when the substance is stored in vials it keeps its molecular structure after four weeks of storage and when stored in syringes a constant degradation of its molecular structure occurs. These results indicate that for ophtalmic purposes bevacizumab can be stored in vials upto four weeks without any degradation of its molecular structure as seen by Raman spectroscopy. This study also shows that Raman spectroscopy can be a valuable tool to determine the integrity and molecular stability of clinical drugs.
Biomedical Spectroscopy and Imaging. 11/2012; 1(3):261-263.
[show abstract][hide abstract] ABSTRACT: In this work the thermal signature of melanoma and non-melanoma skin cancers is investigated in order to be used as a non-invasive aid in the diagnosis and the vascular assessment of these types of skin cancers. Thirty patients with melanoma and non-melanoma skin cancers were examined in order to obtain their temperature profile. The results show that there is a characteristic thermal signature for different types of skin neoplasms which not necessarily depend exclusively on their vascularity. Basal cell carcinomas and squamous cell carcinomas showed a larger range of vascularity, while the thermal profile remained basically constant for squamous cell carcinomas and varied a lot for basal cell carcinomas. In the case of melanomas they showed a high vascularity and an almost constant thermal signature which indicates that metabolic heat production is more relevant in assesing agressiveness. Basal cell carcinomas showed a big range in temperature profiles and a big range in vascularity, a correlation between vascularity and temperature profile was observed when analyzing each subtype of basal cell carcinoma, which indicates that the thermal behavior of basal cell carcinomas is highly dependent on their subtype. With squamous cell carcinoma a big range in vasculature was measured however the temperature range of their thermal profile did not change significantly which indicates that there might be a metabolic heat production – vasculature parameter that appears to remain constant. These results are a step forward in designing a thermal model for skin neoplasms.
24. 11th International Conference on Quantitative InfraRed Thermography, Naples, Italy; 06/2012
[show abstract][hide abstract] ABSTRACT: Knowledge of the existence of filaggrin (FLG) gene mutations might be helpful for a subclassification of patients with atopic dermatitis (AD) which can be used to introduce individualized treatments. In this work the filaggrin content in the skin is assessed using Raman spectroscopy and the results are compared to FLG genotyping of Mexican-mestizo patients. Results showed that the 2282del4 and R501X mutations present in the European population but absent in people of Asian or African descent are also present in the Mexican-mestizo population. The results also showed that patients with filaggrin gene mutations presented lower filaggrin concentrations measured using the vector correlation of their skin Raman spectra and a fixed spectrum of pure human recombinant filaggrin, these results indicate that Raman spectroscopy may be used as a noninvasive tool to detect FLG gene mutations.
[show abstract][hide abstract] ABSTRACT: Skin aging can be attributed to endogenous and exogenous factors which modify the hydration and protein structure of the skin which can be measured using Raman spectroscopy.
This study included 21 healthy adult volunteers, aged 32-81 years, Raman spectra were obtained from sun-protected and sun-exposed skin, also three millimeter punch biopsies of sun-exposed skin were collected and analyzed. The Raman spectra were analyzed using principal component analysis and the results were correlated with clinical and histological findings.
The principal component analysis of the Raman spectra shows that the first principal component (PC1) obtained from the sun-protected skin is related to the age of the subject, which can be taken as a measure of chronological aging, the second (PC2) and fourth (PC4) principal components obtained from Raman spectra of sun-exposed skin are related to the amount of solar elastosis and collagen, respectively.
In this work a relationship was found between histological properties of photoaged skin and noninvasive measurements based on Raman and principal components analysis (PCA). These relationships can be used to assess noninvasively the photoinduced damage and chronological characteristics of skin.
Skin Research and Technology 11/2011; 18(4):442-6. · 1.41 Impact Factor
[show abstract][hide abstract] ABSTRACT: The pathogenesis of melasma has not been clearly elucidated. Using Fontana Masson; diastase-resistant periodic acid-Schiff stains; and immunohistochemistry to stem cell factor (SCF), its receptor c-kit, anti-mast cell tryptase, and anti-collagen type IV antibody, we evaluated melasma lesions and compared them with perilesional skin and photoprotected skin. Samples were taken from lesional and photoprotected nonlesional skin in 24 patients. In other 24 patients, we took biopsies of lesional and perilesional skin. With Fontana Masson, we observed many pigmented basal cells protruding into the dermis of the melasma skin. Periodic acid-Schiff stain and anti-collagen type IV showed damage on the basal membrane in 95.5% and 83%, respectively, in melasma lesion. The immunoreactivity of SCF and the prevalence of mast cells were increased in the dermis of melasma compared with perilesional dermis. The expression of c-kit was significantly increased at lesional epidermis; a frequent protrusion of c-kit-positive basal cells into the dermis was evident in 70% versus that in 29% of perilesional skin. The expression of c-kit was increased at lesional dermis of melasma compared with perilesional skin. We found a low correlation between c-kit expression and prevalence of mast cells; these were increased in melasma skin. The results may suggest a role of SCF, c-kit, and mast cells in the pathogenesis of melasma. We were surprised by the unexpected evidence of damage to basal membrane (BM), which could facilitate the fall or the migration of active melanocytes and melanin into the dermis allowing the constant hyperpigmentation in melasma.
The American Journal of dermatopathology 05/2011; 33(3):291-5. · 1.30 Impact Factor
[show abstract][hide abstract] ABSTRACT: Background. Multiple modalities have been used in the treatment of melasma with variable success. Niacinamide has anti-inflammatory properties and is able to decrease the transfer of melanosomes. Objective. To evaluate the therapeutic effect of topical niacinamide versus hydroquinone (HQ) in melasma patients. Patients and Methods. Twenty-seven melasma patients were randomized to receive for eight weeks 4% niacinamide cream on one side of the face, and 4% HQ cream on the other. Sunscreen was applied along the observation period. They were assessed by noninvasive techniques for the evaluation of skin color, as well as subjective scales and histological sections initially and after the treatment with niacinamide. Results. All patients showed pigment improvement with both treatments. Colorimetric measures did not show statistical differences between both sides. However, good to excellent improvement was observed with niacinamide in 44% of patients, compared to 55% with HQ. Niacinamide reduced importantly the mast cell infiltrate and showed improvement of solar elastosis in melasma skin. Side effects were present in 18% with niacinamide versus 29% with HQ. Conclusion. Niacinamide induces a decrease in pigmentation, inflammatory infiltrate, and solar elastosis. Niacinamide is a safe and effective therapeutic agent for this condition.
Dermatology Research and Practice 01/2011; 2011:379173.
[show abstract][hide abstract] ABSTRACT: There is a broad diversity of moisturizers for the treatment of dry skin; however, we do not know their real effectiveness. The objective here was to evaluate different products through their capacity to increase the epidermal hydration level (EHL) and to reduce the transepidermal water loss (TEWL).
We evaluated twenty moisturizers in sixteen individuals. The analysis was made on volar forearm and basal measurements were made for EHL and TWEL with the later application of 8 gm of each moisturizer on a 2 cm2 area.
For the EHL we found significant differences among the products (p < 0.0001), but only 35% (n = 7) of the moisturizers registered ascending levels of hydration in the course of measurements. The variance analysis for TEWL also was significant (p < 0.0001).
In the short term only a few products induced a significant change in EHL. This study demonstrates the necessity to obtain objective information in order to avoid false publicity claims that may erroneously influence our prescription habits.
Gaceta medica de Mexico 01/2011; 147(3):270-4. · 0.13 Impact Factor
[show abstract][hide abstract] ABSTRACT: The Fitzpatrick skin phototype classification scheme has become the standard method for assessing the reaction of the skin to solar stimuli; this method can be easily biased by different factors, such as ethnicity or chronic sun exposure.
Diffuse reflectance spectrophotometry (DRS) is an objective and non-invasive method used in this work to determine constitutive skin color from the upper volar arm as an objective way of measuring skin pigmentation. A DRS-determined melanin index that accounts for skin pigmentation was obtained for 35 subjects of Hispanic origin, this melanin index was compared with the physician-diagnosed and self-reported skin phototypes.
The results show that at least for Hispanic individuals, there is a clear clinical distinction between subjects with skin phototype I and their DRS-determined melanin index; however, subjects with skin phototypes II-VI have a large melanin index overlap.
Clinical assessment of skin phototype can be complemented by using DRS.
Skin Research and Technology 11/2010; 16(4):397-400. · 1.41 Impact Factor
[show abstract][hide abstract] ABSTRACT: Filaggrin (FLG) gene mutations, which result in complete or incomplete loss of proFLG/FLG peptides, have been reported as an important predisposing factor for atopic dermatitis (AD) and secondary atopic phenotypes such as atopic asthma.
The presence of the protein FLG in the skin was evaluated at birth on 12 infants using Raman spectroscopy; these 12 infants were monitored for 1 year to see whether they developed AD. Three different statistical analysis procedures, two of which involved principal component analysis (PCA), were performed on the Raman spectra in order to determine the FLG content.
The infants who had a lower FLG content, determined using any of the three statistical analysis procedures proposed, were also the ones that clinically developed AD.
The results suggest that Raman spectroscopy and statistical analysis such as PCA could be used as an early detection procedure for FLG -related AD and as a possible quantitative marker for FLG gene mutations.
Skin Research and Technology 07/2010; 17(1):45-50. · 1.41 Impact Factor
[show abstract][hide abstract] ABSTRACT: Melasma is an abnormal acquired hyperpigmentation of the face of unknown origin, it is considered a single disease and very little has been found regarding its pathogenesis. It is usually assumed that melasma is due to excessive melanin production, but excessive retention or abnormal metabolism of this molecule has not yet been considered. In order to search for an alternate explanation for the excessive pigmentation in melasma the molecular structure and concentration of melanin in the stratum corneum of patients with melasma was analyzed using Raman spectroscopy and optical transmission spectroscopy, respectively. From this study it became apparent that in melasma melanin is concentrated in the deeper layers of the skin but its exteriorization remains the same as for healthy skin. Raman spectroscopy measurements showed degraded molecules of melanin in some subjects, which may help explain the variable success rate of the standard therapy.
Photodermatology Photoimmunology and Photomedicine 07/2009; 25(3):159-60. · 1.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: Melasma is an acquired hypermelanosis on sun-exposed areas. Its pathogenesis has not been clearly elucidated. Using histochemistry (Giemsa, Verhoeff-van Gieson and Fontana-Masson staining), we evaluated melasma lesions and compared them with nonlesional skin. Skin samples were obtained from lesional and nonlesional facial skin of 27 patients with melasma, and biopsies were also taken from normal control subjects. Mast cells and solar elastosis areas were evaluated using a computer-assisted image-analysis program. Lesional skin had abundant elastotic material compared with nonaffected skin (13.3 +/- 2.8% vs. 10.2 +/- 2.9%, P < 0.001). Mast cells were more prominent in the elastotic areas of melasma skin (173 +/- 57% vs. 145 +/- 57%, P = 0.04). Melasma could be a result of a cumulative sun exposure, in a microenvironment of cutaneous photoageing in which inflammatory cells, particularly mast cells, play a key role.
Clinical and Experimental Dermatology 05/2008; 33(3):305-8. · 1.33 Impact Factor