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Results for “Skin color”

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At least 19 recordsLinked to original sources
PubMed1977

Genetic and environmental determinants of skin color.

Skin reflectance measurements on a sample of 154 Black and 191 White same-sex twin pairs, attending Philadelphia area schools, are analyzed to determine the effects of genetic and environmental factors. The measurements obtained in July and August, on the forehead, inner upper arm, and flexor surface of the forearm with red, green, and blue filters, were reduced to one index which we call skin color. Analysis of this index using the path analysis of Rao et al. ('74) estimates the major variance components due to racial, residual genetic, and common environmental factors as 67%, 5%, and 22%, respectively.

Adolescent↗
PubMedDate not supplied

An examination of the relationship between race, skin color and a series of autonomic nervous system measures.

In the total population of 75 subjects, the skin albedo correlated significantly with skin resistance, a relationship which was not maintained when the total population was separated into its component subgroups of whites, blacks and Indians. The Indians, "anthropologically Caucasians" but skin color more akin to the blacks, exhibited mean skin reflectance and skin resistance intermediate to that obtained in the black and white groups respectively. Other differences and significant correlations between the autonomic functions in the three groups indicated a higher level of sympathetic tone in the Indians, although this could be attributed to the older age of this group. It was suggested from the results that skin color rather than race has a greater influence on skin resistance.

Acoustic Stimulation↗
PubMed1977

[Postmortem changes in skin color].

By the employment of the colorimetric method statistically significant objective data on postmortem changes in the colour of different parts of the skin have first been obtained. Histological and spectrophotometric studies were carried out in order to elucidate the causes of these changes. The colour of the cadavar skin as well as the colour of the human skin in life depends on primary pigments: hemoglobin, melanin, carotene and melanoid. A certain role is likely to be played by the main structural proteins of the derma and epidermis: collagen and keratin. The cadavar skin colour differs in variations of the dominant wave length and reflectance which are associated with postmortem redistribution of the blood under the effect of the gravity and qualitative transformation of oxyhaemoglobin into reduced haemoglobin. The distribution of melanin, carotene, and melanoid does not differ from that in life. The most specific index of the amount of melanin is the purity of colour and not reflectance.

Adult↗
PubMed1976

[Cutaneous side effects of systemic drugs. Part 4 of a synopsis. 6/7. Drugs affecting the central nervous system. C. Drug-induced photosensitivity. D. Drug-induced changes of skin color].

This, the fourth part of a synopisis of cutaneous side effects of drugs, covers the drugs affecting the central nervous system: antiepileptics, hypnotics, narcotics and psychopharmaceutics; the myorelaxants and antiallergics follow, and lastly there is a section on drug addiction and placebo. The various cutaneous side effects are listed in chart form referring to more than 500 sources. A drug index is attached for handy reference. The reviews of certain drug induced skin disorders are continued with tables covering photosensitivity and changes in skin colour. Phototoxicity, photoallergy and light sensitivity by porphyria are differentiated. The various pigmentation disorders, colour changes due to metal deposits as well as different localisations are included.

Anticonvulsants↗
PubMed1978

Skin color and nutrient photolysis: an evolutionary hypothesis.

Human populations native to areas of intense sunlight tend to be heavily melanized. Previous explanations for this relationship have invoked only weak selective pressures. To test the hypothesis that dark pigmentation may protect against photolysis of crucial light-sensitive vitamins and metabolites by ultraviolet light, folate was used as a model. It was found that exposure of human plasma in vitro to simulated strong sunlight causes 30 to 50 percent loss of folate within 60 minutes. Furthermore, light-skinned patients exposed to ultraviolet light for dermatologic disorders have abnormally low serum folate concentrations, suggesting that photolysis may also occur in vivo. Deficiency of folate, which occurs in many marginally nourished populations, causes severe anemia, fetal wastage, frank infertility, and maternal mortality. Prevention of ultraviolet photolysis of folate and other light sensitive nutrients by dark skin may be sufficient explanation for the maintenance of this characteristic in human groups indigenous to regions of intense solar radiation.

Biological Evolution↗
PubMed1978

[Cutaneous dyschromia in three cases of phenylketonuria. Quantitative ultrastructural study of the basal layer of the epidermis (author's transl)].

The authors have studied skin color modifications in 3 cases of phenylketonuria and have observed the characteristic changes; fair skin and fair hair. In addition they noted hundred of pigmented pin point or slightly larger patches in the two more affected patients, in the areas exposed to sunshine. With regard to the ultrastructural study of the epidermis basal layer, the proportion of melanocytes in the two most severe cases was slightly higher than in the normal skin of 6 control subjects. Langerhans cells could not be acertained. The more severe was the disease the greater was the tendency for a lower proportion of keratinocytes containing melanin. There is a certain parallelism between the skin color modifications the biochemical examinations (blood level of phenylalanin and tyrosine) and the ultrastructural changes. The higher the blood level of phenlalanine and/or the more pronounced the disorders of skin color, the more evident would be the ultrastructural changes: higher proportion of melanocytes that usually do not produce the melanosomes, and lower percentage of keratinocytes with melanin. On the other hand, the ultrastructure of the basal layer would suggest the seriousness of clinical manifestations and/or the intesity of the metabolic error.

Child↗
PubMed1978

An alternative phototherapy light combination.

Combinations of fluorescent lamps for phototherapy were evaluated in order to select one that maximizes blue light content (400 to 500 nanometers) for most effective photodegradation of bilirubin, maintains acceptable color balance for observing infant skin color, and requires minimal lamp replacement for low maintenance cost. The combination that best achieves these objectives consists of four special blue (Westinghouse F20T12-BB) and four broad spectrum (Verd-A-Ray F20T12-CC) lamps that produce blue radiation in excess of an array of eight conventional blue lamps, a spectrum closely approximating that of natural light, and at least 80% of the original blue radiation after 2,100 hours of use.

Biomedical Engineering↗
PubMed1979

The challenge of biophysics to dynamic dermatology.

Dermatologic biophysics has much to offer both clinical and investigative dermatology. For the clinician, the radiation biophysicist can provide accurate measurements of ionizing and nonionizing outputs, including those for PUVA, and critical evaluation of radiation safety measures. In optics, there is a need for accurate measurements of skin color and examination of the skin at moderate magnification. The biophysicist, with the biomedical engineer, can improve all the physical modality instrumentation used in practice. In investigative dermatology, there is the cellular biophysics of radiation. Doppler techniques for skin circulation, spectroscopy of living cells, and many other applications are suggested for current and future studies.

Biophysical Phenomena↗
PubMed2025

iTRAQ-based quantitative proteomics reveals reduced expression of KRT19, KRT7, and PSTDG in cutaneous specimens after kidney transplantation.

Clinical improvement in pigmentation is frequently observed after kidney transplantation. However, the underlying molecular and histological mechanisms remain unclear. We conducted a study to quantify the skin color change using a handheld reflected light colorimeter and to investigate protein expression changes in the skin before and after kidney transplantation. Paired skin biopsies were obtained from three patients who underwent kidney transplantation before and one month after transplantation. Protein expression was analyzed using iTRAQ-based quantitative proteomics. Differentially expressed proteins were identified and visualized using hierarchical clustering and volcano plots. Histopathological evaluation included hematoxylin and eosin (H&E), Masson's trichrome, and immunohistochemical (IHC) staining for keratin (KRT) 7, KRT19, and MelanA. Skin pigmentation of the arms, ankles, and abdomen had significant L-value improvement after kidney transplantation. Proteomic profiling identified 2148 proteins, with six proteins showing significant differential expression after transplantation. Among them, KRT7, KRT19, and prostaglandin D2 synthase (PTGDS) were significantly downregulated, potentially reflecting reduced epithelial stress and systemic inflammation. H&E and Masson's trichrome staining revealed a post-transplantation reduction in dermal pigmentation and collagen content. IHC showed decreased KRT7, KRT19, and MelanA expression after transplantation. Our results suggest that targeting KRT or prostaglandin pathways may offer new treatments for ESRD-related skin symptoms.

Humans↗
PubMed2021

Genetic Relationship Between Endometriosis and Melanoma.

Epidemiological studies have observed that risk of endometriosis is associated with history of cutaneous melanoma and vice versa. Evidence for shared biological mechanisms between the two traits is limited. The aim of this study was to investigate the genetic correlation and causal relationship between endometriosis and melanoma. Summary statistics from genome-wide association meta-analyses (GWAS) for endometriosis and melanoma were used to estimate the genetic correlation between the traits and Mendelian randomization was used to test for a causal association. When using summary statistics from separate female and male melanoma cohorts we identified a significant positive genetic correlation between melanoma in females and endometriosis (r g = 0.144, se = 0.065, p = 0.025). However, we find no evidence of a correlation between endometriosis and melanoma in males or a combined melanoma dataset. Endometriosis was not genetically correlated with skin color, red hair, childhood sunburn occasions, ease of skin tanning, or nevus count suggesting that the correlation between endometriosis and melanoma in females is unlikely to be influenced by pigmentary traits. Mendelian Randomization analyses also provided evidence for a relationship between the genetic risk of melanoma in females and endometriosis. Colocalization analysis identified 27 genomic loci jointly associated with the two diseases regions that contain different causal variants influencing each trait independently. This study provides evidence of a small genetic correlation and relationship between the genetic risk of melanoma in females and endometriosis. Genetic risk does not equate to disease occurrence and differences in the pathogenesis and age of onset of both diseases means it is unlikely that occurrence of melanoma causes endometriosis. This study instead provides evidence that having an increased genetic risk for melanoma in females is related to increased risk of endometriosis. Larger GWAS studies with increased power will be required to further investigate these associations.

endometriosis↗
PubMed1979

Black and white human skin differences.

This review of black and white human skin differences emphasizes the alleged importance of factors other than the obvious, i.e., skin color. Physicochemical differences and differences in susceptibility to irritants and allergens suggest a more resistant black than white skin. Differences appear to exist in the frequency of which several skin diseases occur among blacks and whites. A striking feature in this literature is the disagreement between authors. Common for much of this information is difficulty of interpretation, because of socioeconomic influences and other environmental factors.

Africa↗