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At least 397 records · Page 22Linked to original sources
PubMed1991

Glyphosate skin binding, absorption, residual tissue distribution, and skin decontamination.

Glyphosate is a broad-spectrum postemergence translocated herbicide. Its interactions with skin and potential systemic availability through percutaneous absorption was studied by skin binding, skin absorption, residual tissue distribution, and skin decontamination. Glyphosate in a final formulation (Roundup) undiluted and diluted with water 1:20 and 1:32, would not partition into powdered human stratum corneum (less than 1%). In vitro percutaneous absorption through human skin into human plasma as receptor fluid was no more than 2% over a concentration range of 0.5-154 micrograms/cm2 and a topical volume range of 0.014-0.14 ml/cm2. Disposition of glyphosate following iv administration of 93 and 9 micrograms doses to rhesus monkeys was mainly through urine excretion, 95 +/- 8 and 99 +/- 4% in 7 days, respectively. Percutaneous absorption in vivo in rhesus monkey was 0.8 +/- 0.6% for the low dose (25 micrograms/cm2) and 2.2 +/- 0.8% for the high dose (270 micrograms/cm2). No residual 14C was found in organs of the monkeys euthanized 7 days after the topical application. Washing the skin application site with soap and water removed 90 +/- 4% of applied dose, and washing with water only removed 84 +/- 3% of applied dose. Both soap and water and water only were equal in ability to remove glyphosate from skin over a 24 hr skin application period. About 50% of the initially applied dose could be recovered after 24 hr. Glyphosate is very soluble in water and insoluble in most organics (octanol/water log P = -1.70) and therefore not compatible with the lipid-laden stratum corneum.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed2006

Bicyclic monoterpene diols stimulate release of nitric oxide from skin cells, increase microcirculation, and elevate skin temperature.

Bicyclic monoterpene diols (BMTd) stimulate nitric oxide synthesis in melanoma and neuronal cells, representing cell types arising from embryonic neural crest tissue. This study shows that an equimolar mixture of the BMTd's 2,3-cis/exo-pinanediol and 2,3-cis/exo-camphanediol stimulates nitric oxide synthesis in epithelial cells of the skin, specifically normal human epidermal keratinocytes (NHEK) and normal human microvascular endothelial cells (HMVEC). A 1 mM mixture increased nitric oxide 3-fold in HMVEC in the first 24 h after treatment, and a 2 mM mixture produced an equivalent increase in NHEK. We hypothesized that an increase in nitric oxide in skin would lead to an increase in microcirculation, thereby increasing skin temperature. We found that twice daily application of 1mM BMTd lotion significantly increased arm skin temperature by 0.5 degrees C in 14 days compared to placebo, while a 2 mM mixture significantly increased skin temperature by 0.3 degrees C in 7 days (P < or = 0.05; ANOVA). A single application of a 2 mM BMTd mixture applied 30 min before a 30 min cold challenge (6 degrees C), maintained facial skin temperature 1.4 degrees C above untreated control sites (P < or = 0.05; ANOVA). We also tested whether BMTd treatment would benefit people with dark circles under their eyes. Twenty-six panelists with dark undereye circles completed 2-week, twice daily application of a lotion containing the 1mM mixture to one eye while the other eye was untreated. Seven of 26 subjects showed a reduction of darkness of undereye circles (P < or = 0.05; paired t test). Application of 2 mM BMTd lotion to lips resulted in a significant increase in their redness, as measured by the erythema index (P < or = 0.05; ANOVA). These results show that a mixture of BMTd's increases nitric oxide, and application to skin increases microcirculation and skin temperature.

Boranes↗
PubMed1999

Identification and occurrence of mRNAs for components of the kallikrein-kinin system in human skin and in skin diseases.

Bradykinin and kallidin are released during dermal injury and inflammation as a result of activation of kallikreins which cleave high- and low-molecular weight kininogen (HMW and LMW kininogen, respectively). In the skin, kinins are involved, e.g., as co-mitogens in cellular proliferation or in processes propagating pain and inflammation. The aim of our study was to investigate the specific occurrence of mRNAs for components of the kallikrein-kinin system in normal human skin and in skin biopsies of patients with selected skin diseases (psoriasis, lichenificated atopic eczema, basalioma). In normal skin, reverse transcription polymerase chain reaction (RT-PCR) with specific primer pairs followed by separation of products by polyacrylamide gel electrophoresis (PAGE) revealed the presence of mRNAs for tissue kallikrein, for the B2 and the B1 bradykinin receptors, but not for kininogen. In biopsies of lichenificated atopic eczema and basalioma, additionally, the mRNAs for HMW and LMW kininogen were detected, whereas in psoriatic skin mRNA for HMW kininogen was not expressed. These differences in mRNA expression may reflect the different contribution of kallikrein-kinin system components to the maintenance of chronic skin diseases like psoriasis. In acute dermal reactions occurring in lichenificated atopic eczema or in basalioma, tissue mRNA for HMW kininogen appears to be arisen from sources not pre-existing in normal skin.

Adult↗
PubMed1990

The ontogenesis of skin and organ characteristics in the Syrian golden hamster. I. Skin compartments and subcutaneous adipocytes.

The quantitative relations between the 4 skin compartments [epidermis, stratum (str.) papillare, str. reticulare, panniculus carnosus], the hair follicle density and adipocyte size were investigated histometrically in a total of 464 golden hamsters of both sexes of the acromelanic white inbred strain Bio 1.5 and agouti coloured outbred strain Han:AURA. The overall regular course of ontogenesis from the 1st to the 365th day of life showed discontinuous impairments of the skin layer thickness in the shoulder and sacral region due to the spontaneous growth cycles of hair. Active phases of hair growth could be determined on days 15-25, 50-60 and 80-110 from measurements of the hair follicle density as well as skin thickness. In particular, the thickness of the str. reticulare was closely correlated to the growth cycles. By contrast, the epidermis, str. papillare and skin muscle thickness showed an age-dependent development. Also, no correlation was found between the size of inguinal adipocytes and hair growth cycle, which is in contrast to the data from the literature for small laboratory rodents. Only differences in skin muscle thickness could be found in the sites studied in the shoulder and sacral regions. Overall, the skin compartments, the skin follicle density and adipocyte size were found to be stable to effects such as animal strain, sex and skin localization.

Adipose Tissue↗
PubMed2000

Effect of skin pretreatment with fatty acids on percutaneous absorption and skin retention of piroxicam after its topical application.

The enhancing effect of several fatty acids from different subclasses: saturated (lauric acid), mono-unsaturated (oleic acid) and poly-unsaturated (linoleic and linolenic acids) in the percutaneous absorption of piroxicam was investigated. These fatty acids were applied on the skin membrane in three different ways: included in the vehicle, as a pretreatment or both. An increase in piroxicam flux value was found for lauric and oleic acids in the following order: skin pretreatment with 5% fatty acids followed by application of gels containing 5% fatty acids>skin pretreatment with 5% fatty acids followed application of control gel>gel containing 5% fatty acids without skin pretreatment. For linoleic and linolenic acids, the piroxicam flux in the two pretreatment experiments was almost the same, although higher than when fatty acids were included in the formulation. Skin pretreatment with 5% linolenic acid in propylene glycol followed by application of control gel or a gel containing 5% linolenic acid, showed the highest enhancing capacity. After skin pretreatment with fatty acids, the lag time values decreased nearly three times compared to those obtained when the same fatty acids were included in the formulation. The amount of piroxicam retained in the skin after pretreatment with fatty acids was found to be very similar for all fatty acids and 3-fold higher than in the experiments without skin pretreatment.

Administration, Topical↗
PubMed1996

Kinetics and localisation of PpIX fluorescence after topical and systemic ALA application, observed in skin and skin tumours of UVB-treated mice.

In this study the kinetics and localisation of protoporphyrin IX (PpIX) fluorescence in skin and skin tumours were examined after topically (20% for 4h) or systemically (200 mg/kg,i.p.) administered 5-aminolaevulinic acid (ALA). As a model we used hairless mice with skin lesions (actinic keratoses and squamous cell carcinoma), which were induced by daily UVB irradiation. The epidermis of the skin surrounding the tumours (T) was altered (AS); owing to the UVB irradiation, the epidermis was thicker and less elastic. Therefore, non-UVB-irradiated mice were used to assess fluorescence of normal skin (NS). Light from a halogen lamp was used to excite at 500 +/- 20 nm and fluorescence was detected through a filter that passes light of 670 +/- 50 nm. Maximal fluorescence following i.p. ALA was observed 2 h post injection (p.i.) and was three times less than after topically applied ALA. Furthermore, after i.p. ALA a lower T selectively (T/NS) could be obtained than after topically applied ALA. Maximal fluorescence following topically applied ALA was achieved 6 h after the end of the 4 h application time. At that interval fluorescence of T was twice as high as directly after the application period. Furthermore, T selectivity (T/NS) after topical ALA at the interval of maximal fluorescence was higher than at the interval directly after application. With fluorescence cryomicroscopy localisation of fluorescence in the skin at the interval of maximal fluorescence was determined after both administration routes. For both cases fluorescence was mainly located in T, epidermis and hair follicles. Fluorescence in subcutis could only be observed at 2 h post i.p. ALA and a 6 h post topical ALA. No fluorescence could be observed in muscle. We conclude that, in this model and with these ALA doses, a higher fluorescence intensity and selectivity (T/NS) was achieved after topically applied ALA than after systemically administered ALA. These results make topically applied ALA more favourable for ALA-PDT of superficial skin tumours in this model. In general these results imply that by optimising the time after ALA application the efficacy and selectivity of topical ALA-PDT for skin tumours may be improved.

Administration, Topical↗
PubMed2001

Autofluorescence of human skin is age-related after correction for skin pigmentation and redness.

When measuring the skin fluorescence in vivo, the absorption of chromophores such as melanin and hemoglobin often contribute predominantly to the changes in fluorescence and obscure the information from the fluorophores. We measured in vivo the collagen-linked 375 nm fluorescence (excitation: 330 nm) and 455 nm fluorescence (excitation: 370 nm) from nonexposed buttock skin of healthy volunteers. Skin pigmentation and redness of the same sites were quantified by reflectance of the skin at 555 nm and 660 nm. Multiple regression analysis was used to find the correlation between the fluorescence and skin pigmentation and redness. The fluorescence was corrected for the impact of pigmentation and redness according to the equation found in the regression analyses. The age-related trend of the fluorescence was evaluated. The 375 nm fluorescence showed positive relation to age, whereas the 455 nm fluorescence showed no significant relation to age. The increasing rate of the 375 nm fluorescence (logarithm transformed) was 2% per year, which is comparable with previously published data. The results suggest that the correction of the autofluorescence intensity for skin pigmentation and redness is valid, and the 375 nm skin autofluorescence may be used as a biologic marker of skin aging in vivo.

Adult↗
PubMed2004

Comparison of risk factor profiles concerning self-reported skin complaints and objectively determined skin symptoms in German office workers.

The correspondence between impact factor profiles of self-reported skin sensation and of objectively determined skin symptoms was examined using data from the ProKlimA project (1994-1999). A sub-sample of 925 office workers participated in measurements of skin hydration and sebum content and responded to a questionnaire assessing sensory perception. The calculation of multiple logistic regression models revealed a significant increased risk for female sex [Odds ratio (OR): 2.3; confidence interval (CI): 1.4-3.6], poor software (OR: 2.2; CI: 1.3-4.0), unfavorable job characteristics (OR: 1.8; CI: 1.1-2.8), allergic illness (OR: 1.5; CI: 1.1-2.2) and the use of skin cream (OR:2.6; CI: 1.6-4.4) on the subjective perception of skin sensation. Regarding the objective medical examination of the skin humidity a significant increased risk was detected for a high concentration of Total Volatile Organic Compounds (OR: 2.5; CI: 1.3-4.8) and a low relative humidity (OR:1.9; CI: 1.1-3.4). The likewise objectively measured low sebum content is not associated with environmental variables. The impact profiles on subjective vs. objective outcome variables differ in a clear and typical way. Skin related sensory perception is mainly influenced by job-related and personal impacts. Indoor environmental characteristics affect skin hydration. We conclude the need to develop, to adapt and to use objective clinical methods applicable for field monitoring parallel to questioning.

Adult↗
PubMed1995

Skin paddle salvage in the fibula osteocutaneous free flap with secondary skin paddle vascular anastomosis.

The fibular osteocutaneous free flap has become a popular choice for the reconstruction of bone and skin defects. A potential drawback has been the reported unreliability of the skin paddle. Previous studies have emphasized total loss of the overlying skin paddle, if the expected perforating vessels are not present either in the intermuscular septum or in the soleus. Two cases are presented in which the skin paddle was found to be supplied by vessels arising from the proximal peroneal artery. there were no intraseptal or intramuscular vessels in the osteocutaneous septum which connected to the overlying skin paddle. The skin island was salvaged by performing independent microsurgical anastomoses of the fibular graft and the skin paddle. Both patients had complete survival of the fibula and overlying skin paddle.

Aged↗
PubMed1998

Side effects from the pulsed dye laser: the importance of skin pigmentation and skin redness.

The pulsed dye laser is the treatment of choice for port-wine stains. In this study we evaluate the importance of preoperative skin pigmentation and skin redness for the development of side effects from one treatment with the pulsed dye laser. A risk assessment is performed and skin reflectance measurement objectifies postoperative pigmentary changes. Fourteen human volunteers (skin types I to V) were laser-treated on the inside of the proximal brachium. Photographic documentation was used for blinded, clinical evaluation of side effects 3 and 6 months postoperatively. Skin was artificially reddened using topical application of 10% nicotinic acid cream. The development of pigmentary alterations and texture changes depended on the preoperative pigmentation and redness degrees. The risk of inducing clinically visible pigmentary alterations and texture changes increased with higher preoperative skin pigmentation and redness degrees, and with the application of increasing laser doses. Pigmentary alterations were induced at a lower fluence level than texture changes. The risk of side effects was higher 3 months postoperatively than 6 months postoperatively, substantiating a gradual disappearance of side effects. Skin reflectance measurements documented postoperative hyperpigmentation that faded partially from 3 to 6 months postoperatively. This is the first human experimental model for port-wine stains which provides quantitative data on the relationship between preoperative skin colours and postoperative clinically disturbing side effects.

Administration, Cutaneous↗
PubMedDate not supplied

A reliable and cost-effective in vitro assay of skin viability for skin banks and burn centers.

The tetrazolium salt, MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide), was used to evaluate the viability of fresh native human skin and cryopreserved human skin under a wide variety of conditions. Viability of fresh and cryopreserved skin was determined with our modification of the MTT assay, and compared with the well-described tetrazolium reductase assay. The MTT assay provides a precise and reproducible index of viability for both fresh and cryopreserved skin. In comparison, the tetrazolium reductase assay (1) is subject to higher levels of variability and, (2) underestimates the viability of fresh native skin. The precision, simplicity, and economy of the MTT assay support its utility in the routine assessment of skin viability in skin banks, burn centers, and skin biology research units.

Burn Units↗
PubMedDate not supplied

Clinical trials of a biosynthetic temporary skin replacement, Dermagraft-Transitional Covering, compared with cryopreserved human cadaver skin for temporary coverage of excised burn wounds.

Human cadaver allograft skin (HCAS) is widely used for covering excised burn wounds when limited available skin donor sites or the overall patient condition does not permit immediate grafting with autologous skin. However, recurring problems are associated with HCAS including limited supply, variable quality, ultimate immune rejection, and the potential for bacterial and viral disease transmission. These problems speak for the need for development of a dependable substitute for HCAS. We evaluated the ability of a biosynthetic analogue of human skin to temporarily close excised burn wounds in humans. Dermagraft-TC (Advanced Tissue Sciences, Inc.) (DG-TC) is composed of human neonatal fibroblasts cultured on a synthetic dressing (Biobrane; Dow Hickam, Inc.) that consists of nylon mesh fabric covered with a thin layer of silicone rubber membrane, which provides an epidermal "barrier." The material is stored frozen and thawed immediately before use. DG-TC is semitransparent, thus facilitating continuous observation of the underlying wound surface. Burn wounds in 10 patients (mean age 33.5 years, mean burn size 39.9% total body surface area) were surgically excised. Two variants of the DG-TC skin analogs were tested: a material that was cryopreserved to maintain fibroblast viability (DG-TC Red) and a material that was frozen without efforts to maintain fibroblast viability (DG-TC Blue). A control site on each patient received cryopreserved HCAS. Each study site was approximately 1% total body surface area. When clinically indicated, patients were returned to the operating room where the skin replacements were removed, the wound bed was evaluated and prepared for grafting, and the wounds were closed with meshed split-thickness autograft skin. The results showed that adherence to the wound and subsequent autograft "take" were excellent with both DG-TC variants and were at least equivalent to HCAS. No evidence of immune rejection of DG-TC was seen, whereas in four patients evidence of epidermal sloughing/rejection was noted in the HCAS control sites, which limited persistence of those grafts on the wound. Further clinical trials with this skin analogue are in progress.

Adolescent↗
PubMed1993

Skin anatomy and antigen expression after burn wound closure with composite grafts of cultured skin cells and biopolymers.

Closure of large skin wounds (i.e., burns, congenital giant nevus, reconstruction of traumatic injury) with split-thickness skin grafts requires extensive harvesting of autologous skin. Composite grafts consisting of collagen-glycosaminoglycan (GAG) substrates populated with cultured dermal fibroblasts and epidermal keratinocytes were tested in a pilot study on full-thickness burn wounds of three patients as an alternative to split-thickness skin. Light microscopy and transmission electron microscopy showed regeneration of epidermal and dermal tissue by 2 weeks, with degradation of the collagen-GAG implant associated with low numbers of leukocytes, and deposition of new collagen by fibroblasts. Complete basement membrane, including anchoring fibrils and anchoring plaques, is formed by 2 weeks, is mature by 3 months, and accounts for the absence of blistering of healed epidermis. All skin antigens tested (involucrin, filaggrin, laminin, collagens IV and VII, fibronectin, and chondroitin-sulfate) were expressed by 16 days after grafting. This cultured skin analogue provides an experimental alternative to split-thickness skin graft that develops histiotypic markers of skin anatomy and antigen expression after wound closure.

Adolescent↗
PubMed2006

Norepinephrine modulates the inflammatory and proliferative phases of wound healing.

BACKGROUND: Injury results in the massive release of norepinephrine (NE) into the peripheral circulation. Recent investigations have demonstrated functional adrenoreceptors on the cellular mediators of cutaneous wound healing and NE-induced phenotypic alterations in immune cells have been demonstrated in vitro. Despite this, there is little description of how NE might alter the phases of wound healing in vivo. The purpose of this study was to compare cutaneous wound healing in norepinephrine-intact and norepinephrine-depleted mice. METHODS: Norepinephrine-depleted (NED) mice were generated by chemical axotomy with 6-hydroxydopamine and compared with norepinephrine-intact (NEI) animals (n = 6-12 per group, per time point). Using an excisional wound model, neutrophil recruitment was measured by myeloperoxidase assay. Macrophage recruitment and angiogenesis were measured by immunohistochemistry and re-epithelialization was determined histologically. The development of incisional wound disruption strength was determined over time. Finally, macrophage scavenger function was assessed by an in vitro latex bead phagocytosis assay. RESULTS: Wounds from NEI mice demonstrated greater neutrophil infiltration than NED wounds (24, 72 hours; p < 0.05). Wound macrophage recruitment was initially higher in NEI animals (24 hours, p < 0.05), but was eventually surpassed by that of NED animals (120 hours, p < 0.05). Angiogenesis was decreased while re-epithelialization was accelerated in NEI animals (p < 0.05). Wound disruption strength and macrophage scavenger function were unaltered between NED and NEI mice. CONCLUSIONS: Norepinephrine modulates the inflammatory and proliferative phases of wound healing in a temporally defined, cell-specific manner. By increasing recruitment of innate immune cells and expediting wound closure, norepinephrine appears to play a protective role in defense against infection.

Animals↗
PubMed1988

Hairless mouse skin is limited as a model for assessing the effects of penetration enhancers in human skin.

The permeability coefficient of 5-fluorouracil through human abdominal and hairless mouse skins was used as an indicator of the relative effects of 12-h pretreatment of the skins with either penetration-enhancer mixtures [including laurocapram (Azone), decylmethylsulfoxide, oleic acid, and propylene glycol] or saline (control). After treatment with saline, fluxes of 5-fluorouracil through the two skin types were similar, but the mouse skin showed exaggerated responses to all the penetration-enhancer formulations. There was no consistent relationship between enchancer effects on the two skin types, and we conclude that the hairless mouse model should not be used to predict the effects of penetration enhancers in human skin. After treatment with saline, hairless mouse skin sharply increased in permeability after approximately 50 h hydration, suggesting that the stratum corneum had started to disrupt, whereas the flux through human skin remained unchanged.

Animals↗
PubMed2005

Skin-infiltrating neutrophils following exposure to solar-simulated radiation could play an important role in photoageing of human skin.

BACKGROUND: The pathophysiology of photoageing of the skin has been studied extensively. Matrix metalloproteinases (MMPs) originating from keratinocytes and fibroblasts are thought to play a primary role in this process. Although neutrophils are potent producers of a wide array of proteolytic substances and are present in sunburned skin, their contribution to the pathophysiology of photoageing has been described only in murine studies. OBJECTIVES: To determine the role of neutrophils in photoageing of human skin. METHODS: Healthy white-skinned volunteers were recruited and their sun-protected buttock skin was exposed to solar-simulated radiation (SSR) in dose-response and time-course studies. Punch biopsies were taken and the influx of neutrophils and the expression of neutrophil elastase and MMPs was studied using immunohistochemical techniques and in situ zymography. RESULTS: Neutrophil elastase and MMPs were detected only in skin irradiated with erythemogenic doses (> or = 1 minimal erythema doses) of SSR. Immunohistochemical double staining demonstrated neutrophils to be the major source of MMP-1, MMP-8 and MMP-9. In situ zymography showed elastase, collagenase and gelatinase enzyme activity in those cells. CONCLUSIONS: Our study suggests that neutrophils participate in the process of photoageing of human skin as they infiltrate the skin and release enzymatically active elastase (neutrophil elastase), collagenase (MMP-1) and gelatinase (MMP-9).

Adult↗
PubMedDate not supplied

Neuropeptides in the skin: interactions between the neuroendocrine and the skin immune systems.

The interaction between components of the nervous system and multiple target cells in the cutaneous immune system has been receiving increasing attention. It has been observed that certain skin diseases such as psoriasis and atopic dermatitis have a neurogenic component. Neuropeptides released by sensory nerves that innervate the skin and often contact epidermal and dermal cells can directly modulate functions of keratinocytes, Langerhans cells (LC), mast cells, dermal microvascular endothelial cells and infiltrating immune cells. Among these neuropeptides the tachykinins substance P (SP) and neurokinin A (NKA), calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP) and somatostatin (SOM) have been reported to effectively modulate skin and immune cell functions such as cell proliferation, cytokine production or antigen presentation under physiological or pathophysiological conditions. Expression and regulation of their corresponding receptors that are expressed on a variety of skin cells as well as the presence of neuropeptide-specific peptidases such as neutral endopeptidase (NEP) or angiotensin-converting enzyme (ACE) determine the final biological response mediated by these peptides on the target cell or tissue. Likewise, skin cells like keratinocytes or fibroblasts are a source for neurotrophins such as nerve growth factor that are required not only for survival and regeneration of sensory neurons but also to control responsiveness of these neurons to external stimuli. Therefore, neuropeptides, neuropeptide receptors, neuropeptide-degrading enzymes and neurotrophins participate in a complex, interdependent network of mediators that modulate skin inflammation, wound healing and the skin immune system. This review will focus on recent studies demonstrating the role of tachykinins, CGRP, SOM and VIP and their receptors and neuropeptide-degrading enzymes in mediating neurogenic inflammation in the skin.

Animals↗
PubMed2006

Relationship between skin response to ultraviolet exposure and skin color type.

Sun exposure is responsible for detrimental damage ranging from sunburn to photoaging and skin cancer. This damage is likely to be influenced by constitutive pigmentation. The relationship between ultraviolet (UV) sensitivity and skin color type was analyzed on 42 ex vivo skin samples objectively classified from light to dark skin, based on their values of individual typology angle (ITA) determined by colorimetric parameters. The biologically efficient dose (BED) was determined for each sample by quantifying sunburn cells after exposure to increasing doses of UV solar-simulated radiation. Typical UV-induced biologic markers, other than erythema, such as DNA damage, apoptosis and p53 accumulation, were analyzed. A statistically significant correlation was found between ITA and BED and, ITA and DNA damage. Interestingly, DNA lesions were distributed throughout the whole epidermal layers and the uppermost dermal cells in light, intermediate and tanned skin while they were restricted to suprabasal epidermal layers in brown or dark skin. Our data support, at the cellular level, the relationship between UV sensitivity and skin color type. They emphasize the impact of DNA damage accumulation in basal layer in relation to the prevalence of skin cancer.

Apoptosis↗