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PubMed1984

Alopecia areata: light and electron microscopic pathology of the regrowing white hair.

Light and electron microscopic studies have been carried out on fifteen regrowing white anagen hair follicles from seven patients with alopecia areata. Seven bulbs showed evidence of cell injury that was concentrated in cortical keratocytes. Lower bulb matrix cells appeared undamaged though in six bulbs apoptotic degeneration was seen in the lower bulb keratocytes, perhaps indicating early catagen transformation. Melanocytes were identified in all the bulbs except those from one patient. The number of melanocytes and their melanization were much less than in the normal pigmented follicle, and pigment transfer was rarely seen. It is proposed that alopecia areata is a disease of differentiating cortical keratocytes. The failure of pigmentation in the regrowing white hair may be post-inflammatory, but the various other pigmentary features of alopecia areata, especially the sparing of senile white hairs, suggest that pigmentary mechanisms in the hair bulb are of primary importance in the pathogenesis of this disorder.

Adult↗
PubMed1987

The effect of age and hair colour on human hairbulb tyrosinase activity.

We studied tyrosinase activity from human hairbulbs from 51 subjects, aged 5-72 years. We used anagen hairbulbs and grouped the subjects according to hair colour. We did not observe an age-dependent fall in hairbulb tyrosinase activity. We observed considerable inter-individual variation in activity, with a range of 8-342 pmol DOPA formed/three hairbulbs/30 min. The mean tyrosinase activity from red hairbulbs was significantly higher than the mean for the other hair colours. White hairbulbs did not express tyrosinase activity, and specific antibodies to tyrosinase were used to establish that tyrosinase antigen was absent from white hairbulbs.

Adolescent↗
PubMed1988

Plasma 5-S-cysteinyldopa as an index of melanogenesis.

Plasma 5-S-cysteinyldopa (5-S-CD) concentration measured in healthy volunteers in Edinburgh, Scotland (latitude 56 degrees N) showed only minor changes during the day. However, when measurements were performed over a 12-month period a significant rise in 5-S-CD concentration was found. Skin pigmentation and hair colour were not related to plasma 5-S-CD levels. Patients with psoriasis treated with ultraviolet-B or photochemotherapy (PUVA) developed an almost two fold increase in their plasma 5-S-CD level within the first five treatments, before pigmentation developed, subsequent increments of up to four times the pretreatment level being found in the PUVA group. Dithranol treatment caused an increase in plasma 5-S-CD in some psoriatic patients, suggesting a possible association between skin erythema and elevated 5-S-CD levels. The value of plasma 5-S-CD in the follow-up of patients with malignant melanoma does not seem to be invalidated by unavoidable exposure of the subjects to sunlight in a temperate climate such as that of South East Scotland.

Adult↗
PubMed1990

Pigmentary changes of the ageing skin.

In subjects older than 25-30 years the number of enzymatically active melanocytes detectable by the dopa reaction decreases by about 10-20% per decade, with exposed skin having approximately twice as many pigment cells as unexposed skin. Chronic exposure to sunlight may stimulate the epidermal melanocyte system rather than accelerating chronological ageing. The number of melanocytic naevi declines with age. Despite the decreased melanocyte density, photoaged skin has irregular pigmentation and, frequently, there is hyperpigmentation. This may be due to greater positivity of dopa of chronically irradiated melanocytes. Heterogeneity in skin colour in exposed areas of skin is due to uneven distribution of pigment cells, a local loss of melanocytes, and a modification in the interactions between melanocytes and keratinocytes. The most common pigmented lesions in sun-exposed skin include ephelides, actinic lentigo, pigmented solar keratoses and seborrhoeic keratoses, and lentigo maligna. The white spots in aged skin are usually stellate pseudoscars or idiopathic guttate hypomelanosis. Greying of the hair is due to progressive loss of melanocytes from the hair follicles. In vivo and in vitro studies are necessary to increase overall understanding of the processes involved and to improve treatment of the pigmentary changes in ageing skin.

Adult↗
PubMed1995

Enhancement of the depigmenting effect of hydroquinone by cystamine and buthionine sulfoximine.

Glutathione (GSH) performs several important biological functions, including quenching of reactive oxygen species, and protection of cells from toxic compounds such as quinones. The first step in the synthesis of GSH is catalysed by gamma-glutamylcysteine synthetase, an enzyme which is inhibited by cystamine and buthionine sulfoximine (BSO). In this study, we examined the possibility that the effect of hydroquinone (HQ) on pigmentation could be potentiated by inhibiting the production of GSH. In vitro studies using melanoma cell lines demonstrated that both cystamine and BSO could potentiate the inhibitory effects of HQ on tyrosinase activity and melanin content. A synergistic decrease in hair pigmentation was observed when a combination of HQ (2 or 4%) and BSO (5%) was applied to the dorsal skin of C57BL mice. In black hairless guinea-pigs, the application of HQ plus either BSO or cystamine resulted in a significant decrease in epidermal pigmentation when compared with any of the agents alone. The possibility exists that in the future a combination of HQ plus cystamine or BSO could be used to treat disorders such as melasma and post-inflammatory hyperpigmentation.

Animals↗
PubMed1995

Different growth rates of pigmented and white hair in the beard: differentiation vs. proliferation?

A considerable difference in growth rates of pigmented and white anagen beard hair (0.47 mm/day vs. 1.12 mm/day, on average) was measured in three individuals over a 3-year period. Nuclear differentiation in the suprabulbar region of hair shafts revealed an earlier, and more intensive, condensation of chromatin in pigmented hair than in white hair. As other differences (diameter, presence or absence of medulla) between the two hair types could be excluded, the results suggest earlier terminal differentiation of pigmented hair compared with white hair.

Adult↗
PubMed2005

Health status and plasma dioxin levels in chloracne cases 20 years after the Seveso, Italy accident.

BACKGROUND: The Seveso, Italy accident of 1976 exposed a large population to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD or simply dioxin). The accident resulted, mostly among children, in one of the largest ever-reported outbreaks of chloracne, the typical skin disorder due to halogenated-hydrocarbon compounds. OBJECTIVES: Approximately 20 years after the accident, we conducted an epidemiological study in Seveso to investigate (a) the health status of chloracne cases; (b) TCDD-chloracne exposure-response relationship; and (c) factors modifying TCDD toxicity. METHODS: From 1993 to 1998, we recruited 101 chloracne cases and 211 controls. Trained interviewers administered a structured questionnaire assessing, among other epidemiological variables, information on an extensive list of diseases. During the interview, individual pigmentary characteristics were determined. We measured plasma TCDD levels using high-resolution gas chromatography/mass spectrometry. RESULTS: Plasma TCDD was still elevated (> 10 ppt) in 78 (26.6%) of the 293 subjects with adequate plasma samples, particularly in females, in subjects who had eaten home-grown animals, and in individuals with older age, higher body mass index and residence near the accident site. After 20 years, health conditions of chloracne cases were similar to those of controls from the Seveso area. Elevated plasma TCDD was associated with chloracne [odds ratio (OR) = 3.7, 95% confidence interval (CI) 1.6-8.8, adjusted for age, sex and residence]. Chloracne risk was higher in subjects younger than 8 years at the accident (OR = 7.4, 95% CI 1.8-30.3) and, contrary to previous hypotheses, did not increase at puberty onset or in teenage years. Subjects with elevated TCDD levels and light hair colour had higher relative odds of chloracne (OR = 9.2, 95% CI 2.6-32.5). CONCLUSIONS: Dioxin toxicity in chloracne cases was confined to the acute dermatotoxic effects. Chloracne occurrence appeared related to younger age and light hair colour. Age-related dioxin elimination or dilution must be taken into account in interpreting these results.

Accidents, Occupational↗
PubMed2005

PTCH codon 1315 polymorphism and risk for nonmelanoma skin cancer.

BACKGROUND: The PTCH tumour suppressor gene is involved in the development of nearly all basal cell carcinomas (BCCs) of the skin and a fraction of squamous cell carcinomas (SCCs). A nonconservative Pro/Leu nucleotide polymorphism within PTCH exon 23 at codon 1315 was recently reported to be potentially important for the development of breast epithelial cell cancers. Objectives Accordingly, the status of PTCH codon 1315 was analysed for a possible association with the development of nonmelanoma skin cancers (NMSCs) in a pilot study. Because skin cancer risk is affected by specific population-dependent phenotypes such as skin and hair colour, codon 1315 was also analysed for normal allele frequency variation in human populations having differing extents of eumelanin vs. phaeomelanin. METHODS: The single nucleotide polymorphism in codon 1315 of the human PTCH gene was analysed in genomic DNA from six different populations comprising 472 blood samples and from 170 patients in four different categories with NMSC. Polymerase chain reaction and pyrosequencing were used to determine the allele frequencies. Allelic loss was furthermore determined in tumours following microdissection. RESULTS: The Pro/Pro genotype frequency ranged from 30% to 65% between populations, with a significant trend for a reduced frequency of the Pro/Pro genotype in populations having lighter pigmentation (P = 0.020). Pro/Pro frequency showed an increasing trend with increasing tumour case severity (P = 0.027). In 260 samples from 180 Swedish patients with NMSC and a control group of 96 healthy ethnically matched volunteers, no statistically significant pairwise differences between groups were detected in the PTCH codon 1315 allelic distribution, neither was a difference seen for multiple or early onset cases of BCC in the Swedish population. In Swedish patients with single tumours, allelic loss (loss of heterozygosity) was observed in 20 of 30 (67%) patients with BCC and four of 22 (18%) patients with SCC, with no preference in the allele lost. In contrast, the Pro/Pro genotype was frequent in seven U.S. patients having multiple independent BCCs. One of these patients was heterozygous, enabling allelic loss studies. Of 20 independent tumours, 11 had lost an allele; 10 of the 11 had lost Leu, suggesting nonrandom loss that favoured retention of Pro (P = 0.0059). CONCLUSIONS: Our results indicate an association between the eumelanin-to-phaeomelanin shift and a shift from the Pro/Pro genotype to Leu-containing genotypes. Failure to lose Pro during the shift to phaeomelanin may be associated with an increased population risk for BCC and increased individual risk for multiple BCC. During development of a tumour, the effect of Pro may be magnified by loss of the Leu allele.

Basal Cell Carcinoma↗
PubMed2006

HLA class II polymorphisms in Spanish melanoma patients: homozygosity for HLA-DQA1 locus can be a potential melanoma risk factor.

BACKGROUND: The association of melanoma with HLA class II loci is under extensive debate. Different investigators have found discrepant results due to, at least in part, sample size, patient series heterogeneity, choice of control population and differences in the techniques employed for the detection of HLA antigens and alleles. OBJECTIVES: This study was designed to analyse the possible association of melanoma with HLA class II loci with regard to different clinic pathological factors and to investigate other risk factors for melanoma susceptibility, such as HLA homozygosity. PATIENTS AND METHODS: HLA-DRB1, -DQA1 and -DQB1 genotyping was performed for 117 eastern Spanish patients presenting with primary melanoma. RESULTS: Although there were no significant alterations in the phenotypic frequencies of HLA-DQA1, -DQB1 or -DRB1 alleles in any subgroup of patients when compared with controls, patients exhibited a statistically significant increase in HLA-DQA1 homozygosity rate. This DQA1 homozygosity-specific association was particularly dependent on some features in melanoma patients such as light hair colour, skin type I or II, early age at diagnosis, absence of atypical naevi, or abscence of atypical naevus syndrome phenotype (aetiological fractions about 10-20%). Analysis of homozygosity for single DQA1 alleles showed an increased homozygosity rate for DQA1*0505 and DQA1*0301 in comparison with controls. These DQA1 alleles are in strong linkage disequilibrium with DQB1*0301 in white populations, and DQB1*0301 homozygous individuals were significantly increased in red in or fair-haired patients (relative risk 5.65). CONCLUSIONS: Our results indicate that the contribution of HLA class II alleles to primary melanoma incidence is not significant in the Spanish population. However, homozygosity for the HLA-DQA1 locus (and, perhaps, for the HLA-DQB1*0301 allele) might be considered a potential risk factor for developing melanoma depending on the person's genetic background and, perhaps, on certain environmental conditions.

Adult↗
PubMed2006

Oral zinc sulphate causes murine hair hypopigmentation and is a potent inhibitor of eumelanogenesis in vivo.

BACKGROUND: C57BL/6 a/a mice have been widely used to study melanogenesis, including in electron paramagnetic resonance (EPR) studies. Zinc cations modulate melanogenesis, but the net effect of Zn2+ in vivo is unclear, as the reported effects of Zn2+ on melanogenesis are ambiguous: zinc inhibits tyrosinase and glutathione reductase in vitro, but also enhances the activity of dopachrome tautomerase (tyrosinase-related protein-2) and has agonistic effects on melanocortin receptor signalling. OBJECTIVES: To determine in a C57BL/6 a/a murine pilot study whether excess zinc ions inhibit, enhance or in any other way alter hair follicle melanogenesis in vivo, and to test the usefulness of EPR for this study. METHODS: ZnSO(4).7H2O was continuously administered orally to C57BL/6 a/a mice during spontaneous and depilation-induced hair follicle cycling (20 mg mL-1; in drinking water; mean+/-SD daily dose 1.2+/-0.53 mL), and hair pigmentation was examined macroscopically, by routine histology and by EPR. RESULTS: Oral zinc cations induced a bright brown lightening of new hair shafts produced during anagen, but without inducing an EPR-detectable switch from eumelanogenesis to phaeomelanogenesis. The total content of melanin in the skin and hair shafts during the subsequent telogen phase, i.e. after completion of a full hair cycle, was significantly reduced in Zn-treated mice (P=0.0005). Compared with controls, melanin granules in precortical hair matrix keratinocytes, hair bulb melanocytes and hair shafts of zinc-treated animals were reduced and poorly pigmented. Over the course of several hair cycles, lasting hair shaft depigmentation was seen during long-term exposure to high-dose oral Zn2+. CONCLUSIONS: High-dose oral Zn2+ is a potent downregulator of eumelanin content in murine hair shafts in vivo. The C57BL/6 mouse model offers an excellent tool for further dissecting the as yet unclear underlying molecular basis of this phenomenon, while EPR technology is well suited for the rapid, qualitative and quantitative monitoring of hair pigmentation changes.

Administration, Oral↗
PubMed2007

p53 codon 72 Pro homozygosity increases the risk of cutaneous melanoma in individuals with dark skin complexion and among noncarriers of melanocortin 1 receptor red hair variants.

BACKGROUND: p53 has a common polymorphism at amino acid 72, encoding either arginine or proline. p53Arg and p53Pro exhibit differences in various biological activities, such as cell-cycle arrest and induction of apoptosis. Numerous epidemiological studies have examined the role of this polymorphism in several human malignancies, including cutaneous cancers, with contradictory results. OBJECTIVES: To investigate the germline frequency of p53 codon 72 polymorphism in malignant melanoma in a Mediterranean population, and to examine possible associations with various clinicopathological factors. METHODS: In this hospital-based case-control study we used allele-specific polymerase chain reaction for p53 codon 72 genotyping in blood specimens from 107 Greek patients with sporadic cutaneous melanoma and 145 healthy controls. RESULTS: After adjustment for age, sex and phototype the Pro/Pro genotype was associated with increased risk for cutaneous melanoma compared with the Arg/Arg genotype (adjusted odds ratio, OR 3.17, 95% confidence interval, CI 1.03-9.78). This correlation was more pronounced in subjects with phototypes III or IV (adjusted OR 9.56, 95% CI 1.56-58.46), dark skin (adjusted OR 10.96, 95% CI 1.64-73.28), dark eyes (adjusted OR 8.86, 95% CI 1.69-46.52) and dark hair (adjusted OR 3.17, 95% CI 1.01-9.95), and among noncarriers of melanocortin 1 receptor gene (MC1R) red hair polymorphisms (adjusted OR 2.99, 95% CI 1.02-8.78). CONCLUSIONS: p53 codon 72 Pro/Pro genotype could be a risk factor for the development of melanoma in the Greek population, especially in subgroups with darker skin pigmentation, as well as among noncarriers of the MC1R red hair polymorphic variants.

Adult↗
PubMed1989

Darkening of white hair in Parkinson's disease.

We describe a patient with long-standing Parkinson's disease who noted that his white hair turned grey and darkened 8 months after the addition of carbidopa to his established levodopa (L-dopa) therapy and 4 months after the introduction of bromocriptine.

Carbidopa↗
PubMed2006

Proopiomelanocortin (POMC): the cutaneous roles of its melanocortin products and receptors.

The precursor protein proopiomelanocortin (POMC) produces many biologically active peptides via a series of enzymatic steps in a tissue-specific manner, yielding the melanocyte-stimulating hormones (MSHs), corticotrophin (ACTH) and beta-endorphin. The gene for alpha-MSH is encoded for by the POMC gene, but alpha-MSH cannot be produced from POMC gene transcription and translation without these specific post-translational proteolytic steps taking place. The MSHs and ACTH bind to the extracellular G-protein-coupled melanocortin receptors (MCR), of which there are five subtypes. Two (MC1R and MC5R) show widespread cutaneous expression. ACTH and alpha-MSH bind to MC1R to influence both pigmentation and the immune system. MC5R regulates the sebaceous glands. Mutations in the MC1R gene lead to fair skin and red hair in humans, which is also seen with inactivating human POMC gene mutations. MC1R mutant receptor expression can also correlate with an increased incidence of the three commonest forms of skin cancer. Other mutations can occur in the POMC system or parallel interacting pathways, such as in prohormone convertase 1 and agouti signalling protein, a human homologue of murine agouti protein. However, they do not necessarily affect skin colour or function in humans, and further studies are needed to clarify these observations.

Animals↗
PubMed1992

Drug-induced hair colour changes.

Drug-induced hair colour changes are not a common adverse effect from medications. A wide variety of drugs have been implicated in causing hair colour changes but very few have data to support a true relationship. Of the drugs reported, chloroquine and cancer chemotherapeutic agents have the best evidence to support an association. Other drugs, such as p-aminobenzoic acid, calcium pantothenate, anthralin, chinoform, mephenesin, minoxidil, propofol, valproic acid, and verapamil await confirmatory data. Drug-induced causes should be considered in any patient with unexplained hair colour changes.

4-Aminobenzoic Acid↗
PubMed1995

Effects of N-methyl-D-aspartate (NMDA) on seasonal cycles of reproduction, body weight and pelage colour in the male Siberian hamster.

Siberian hamsters (Phodopus sungorus) transferred from stimulatory photoperiods (long days: LD) to inhibitory photoperiods (short days: SD) undergo testicular regression within 8 weeks. This reproductive response to photoperiod was blocked by systemic daily treatment with the glutamatergic agonist N-methyl-D-aspartate (NMDA: 20 mg/kg BW, sc). This powerful effect of NMDA demonstrates the potential for endogenous glutamate to regulate reproductive function. The overall aim of the subsequent studies was to investigate the site and mechanism of action of this glutamatergic agonist in order to identify potential mechanisms through which endogenous glutamate might act. To investigate whether the effect of systemic NMDA was via an effect on the circadian timing system, alterations in gonadal regression and recrudescence, seasonal coat changes (pelage) and body weight (BW) were examined. It would be predicted that long-term cycles of all these seasonal parameters would be affected if the action of NMDA were to perturb the transduction of photoperiodic information. Daily treatments with NMDA, which initially maintained reproductive function in hamsters exposed to SD, did not influence the time course of subsequent testicular recrudescence, nor did they influence long-term cycles of pelage and BW. Moreover, treatment with NMDA induced a dose-dependent increase in serum concentrations of LH within 15 min of systemic injection. These data are consistent with the hypothesis that systemic NMDA exerts it reproductive effects not via an action on the circadian system, but via an action on secretion of GnRH. To investigate potential central sites of action of glutamate, induction of the immediate early gene c-fos, an acute marker of cellular response, was evaluated immunocytochemically (ICC) in brain areas after treatment with NMDA. Although dual-label ICC studies revealed that NMDA did not induce c-fos within GnRH neurons, NMDA did induce c-fos in many cells in the region of the organum vasculosum of the lamina terminalis (OVLT), an area containing a large number of GnRH perikarya, and in the arcuate nucleus, a region close to GnRH secretory terminals in the median eminence. The lack of c-fos induction of GnRH cells argues against a direct effect of NMDA on GnRH neurons. Thus, we examined immunocytochemically the distribution of the common NMDAR1 glutamate receptor subunit to evaluate further the potential sites of glutamatergic action. As expected, NMDAR1-ir was widespread in perikarya throughout the brain, including the region of the OVLT and the arcuate nucleus.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of Variance↗
PubMed2005

Skeleton photoperiods alter delayed-type hypersensitivity responses and reproductive function of Siberian hamsters (Phodopus sungorus).

Photoperiod (day length) can modulate immune function. Whether these photoperiodic effects on immune function are mediated directly by a circadian photoperiodic time measurement system or indirectly by nonspecific (e.g. stressful) effects of light is unknown. To discriminate between these two possibilities, Siberian hamsters (Phodopus sungorus) were housed in either long or short photoperiods (LD 16 : 8 h or LD 8 : 16 h) or in 'skeleton' long or short photoperiods (LD 1 : 14 h: LD 1 : 8 h or LD 1 : 6 h: LD 1 : 16 h). In the skeleton photoperiods, both long- and short-day animals received 2 h of light per day. After 10 weeks in their respective photoperiods, hamsters were tested for an antigen specific immune response using a delayed type hypersensitivity (DTH) model. Reproductive and endocrine responses of hamsters in each of the skeleton photoperiods were equivalent to those in standard long or short days, respectively. Hamsters in skeleton short days and LD 8 : 16 increased DTH responses compared to hamsters in both long-day groups. DTH responses were equivalent in both long-day groups. These results suggest that the influences of day length on immune function potentially are due to circadian photoperiodic time measurement systems.

Animals↗