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PubMed1990

Red or rufous albinism in southern Africa.

Red or rufous albinism is a rare type of oculocutaneous albinism described, but not as yet fully investigated, in Africa and New Guinea. Twelve rufous albino subjects from 10 families participated in this preliminary study. The prevalence of rufous albinism was found to be approximately one in 8,580 among school children in the negroid population. The combination of the unusual red skin colour, ginger to reddish hair colour, low susceptibility to sun damage, and minimal visual problems, in affected individuals, suggested that they form a group which is distinct from the brown and other types of albinism. The mode of inheritance was found to be recessive. Tyrosinase assays showed that rufous albinos are tyrosinase positive and on electron microscopy studies normal melanosomes and melanocytes were observed in hair bulbs and skin. Visual evoked potential testing did not show the gross decussation abnormalities of the optic pathway detected in other types of albinism. Rufous albinism might be at one end of the spectrum of types of oculocutaneous albinism and, because affected people have such mild symptoms, their inclusion in this group might be debatable.

Adolescent↗
PubMed1994

The in vitro differential binding of benzoylecgonine to pigmented human hair samples.

Only fragmentary information on the relationship between hair pigmentation (melanin) and the cocaine/benzoylecgonine content of hair samples is available. The in vitro incorporation of benzoylecgonine into the shafts of black, brown, and blond samples of human hair was accomplished. Post digestion analysis and wash samples demonstrate the relative incorporated ions of benzoylecgonine to be black > brown > blond. Melanin content seems to be important. Lightly pigmented blond hairs may be less appropriate samples for benzoylecgonine and cocaine analysis.

Binding Sites↗
PubMed1985

Suppression of antibody response by excess dietary zinc exposure during certain stages of ontogeny.

A study was made of the effects of excess dietary zinc on the antibody response to sheep red blood cells (SRBC) in mice. C57BL/6J mice were divided into 10 different dietary groups and exposed to diets containing zinc in normal (50 ppm) or excess (2000 ppm) concentrations during gestation/lactation/postweaning development in the sequences (1) 50/50/50; (2) 50/50/2000; (3) 2000/50/50; (4) 2000/2000/50; (5) 2000/50/2000; (6) 50/2000/50; (7) 50/2000/2000; (8) 2000/2000/2000; (9) 50/50/50 (pair-fed); and (10) chow/chow/chow. Mice in group 8 had severe signs of copper deficiency at 8 weeks of age, such as reduced plasma copper, lowered plasma hematocrit, and achromotrichia. Mice receiving 2000 ppm zinc during gestation had fewer offspring per litter (measured at 2 weeks of age) and more nonviable births than mice given 50 ppm zinc during gestation. The growth curve of mice exposed to excess zinc in the 50/50/2000 group was identical to that of the control (50/50/50) group. Growth curves for all other groups were reduced by varying amounts. The plaque-forming cell response to SRBC was reduced only in the groups receiving 50/2000/2000 and 2000/2000/2000 ppm zinc (P less than 0.05); this reduced response was not associated with atrophy of the lymphoid organs. Splenic cell surface markers and mitogenic responsiveness were similar in the 50/50/50 and 2000/2000/2000 groups. These results suggest that the immune response is more susceptible to dietary manipulation during development than after the immune response has been developed.

Animals↗
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↗
PubMedDate not supplied

Post-genome integrative biology: so that's what they call clinical science.

Medical science is increasingly dominated by slogans, a characteristic reflecting its growing bureaucratic and corporate structure. Chief amongst these slogans is the idea that genomics will transform the public health. I believe this view is mistaken. Using studies of the genetics of skin cancer and the genetics of skin pigmentation, I describe how recent discoveries have contributed to our understanding of these topics and of human evolution. I contrast these discoveries with insights gained from other approaches, particularly those based on clinical studies. The 'IKEA model of medical advance'--you just do the basic science in the laboratory and self-assemble in the clinic--is not only damaging to clinical advance, but reflects a widespread ignorance about the nature of disease and how clinical discovery arises. We need to think more about disease and less about genes; more in the clinic and less in the laboratory.

Animals↗
PubMed1998

Morphologic and hematologic characteristics of storage pool deficiency in beige rats (Chédiak-Higashi syndrome of rats).

Characterization of beige rats as having a platelet storage pool deficiency (SPD) was undertaken. Platelets from beige rats, an animal model of Chédiak-Higashi syndrome (CHS), completely lacked the ability to aggregate when stimulated with high dosages of collagen (50 micrograms/ml), and lacked secondary aggregation induced by adenosine diphosphate (ADP). Concentrations of ADP, ATP, and serotonin in the platelets of beige rats were significantly lower than those of control rats. However, platelet count remained within normal values. Electron microscopy revealed that platelets had fewer dense granules, whereas other organelles had normal structure. This morphologic and functional evidence confirms that platelets of beige rats have the typical characteristics of SPD.

Adenosine Diphosphate↗
PubMed1999

Genetic studies in Medzev, a village in south-eastern Slovakia. 3. Morphogenetic traits.

Eleven anthropometric traits, five indices and eight anthroposcopic and behavioural traits have been studied in the population of Medzev, which is located in the region Spis in South-Eastern Slovakia. An attempt has been made to compare the results of the present study with other population groups in Slovakia, particularly with an ethnogenetically related population from North-Eastern Slovakia (Chmel'nica). Barring zygomatic breadth in males, biogonial breadth in females, biacromial breadth und jugomandibular index in both sexes, hair pigmentation, ear lobe attachment and arm folding, the remaining traits show no significant differences between the Medzev and Chmel'nica population. On the whole, these two populations are closer to each other than to any other Slovakian group.

Adult↗
PubMed1999

Cytochrome P450 CYP2D6 genotypes: association with hair colour, Breslow thickness and melanocyte stimulating hormone receptor alleles in patients with malignant melanoma.

We previously identified associations between polymorphism in the cytochrome P450 CYP2D6 gene and outcome in several cancers. We have now examined the hypothesis that homozygosity for the mutant alleles, CYP2D6*4 and CYP2D6*3, is associated with susceptibility and outcome in malignant melanoma. Outcome was assessed by Breslow thickness. We first confirmed previous reports that these mutant alleles are associated with increased susceptibility to malignant melanoma. For example, the frequency of homozygosity for CYP2D6*4 was significantly greater (P = 0.006, chi-squared 1 d.f. = 7.4, odds ratio 2.2, 95% confidence interval 1.2, 3.9) in cases (9.1%) than in control individuals (4.3%). The frequency of homozygosity for the mutant alleles was next examined in the malignant melanoma cases grouped on the basis of characteristics associated with malignant melanoma risk. Homozygosity was significantly more common (P = 0.038) in cases with red/blonde hair than in those with brown/black hair. We found no associations between the CYP2D6 genotype and sex, skin type or eye colour. The possible association of CYP2D6 with outcome was assessed by comparing genotype frequencies in patients with tumours of Breslow thickness < 1.5 mm with those whose tumours were > or = 1.5 mm. In patients with red/blonde, but not brown or black hair, homozygosity for CYP2D6*4 was significantly associated with thicker lesions in a multivariate model (P = 0.036). We further examined the association of CYP2D6*4 homozygosity with red/blonde hair by classifying patients on the basis of homo- or heterozygosity for wild-type or val92met, asp294his or asp84glu melanocyte stimulating hormone receptor (MC1R) alleles. None of the nine patients with brown/black hair with the asp294his allele were homozygotes for CYP2D6*4. By contrast, in the patients with red/blonde hair, three of five cases with asp294his were homozygotes for the mutant CYP2D6 allele. The difference in the frequency of CYP2D6*4 homozygotes in the red/blonde cases with wild-type MC1R alleles compared with those with asp294his was significant (exact P = 0.029). No associations between val92his or asp84glu and CYP2D6 alleles were identified.

Cytochrome P-450 CYP2D6↗
PubMed1999

Hereditary melanoblastoma in miniature pigs and its successful therapy by devitalization technique.

Applying selective breeding for 10 years we established the MeLiM (Melanoblastoma-bearing Libechov Minipigs) strain. Melanoblastoma (MB) in this strain shows a hereditary occurrence. Cutaneous tumours are usually nodular, multiple and distributed on various parts of body. They appear in darkly pigmented animals already at the birth or during two months thereafter (57% of all animals). Numerous organ metastases mainly into the spleen, lymph nodes and lungs are regularly ascertained in animals with cutaneous MB. Tumour cells were surprisingly found also in the inner organs of phenotypically healthy minipigs in which no cutaneous MBs were observed visually (27% of all animals). About 34% of all affected piglets die during the first 2 months of age. These features document a malignancy of this tumour in the MeLiM strain. Original surgical technique was applied in more than 40 affected minipigs at 1-2 months of age. It consists in a devitalization (ischemization) of one of cutaneous tumours by the mattress sutures conducted around the tumour base without any excision of tumour tissue. This simple procedure causes a total destruction of MB cells in all cutaneous tumours as well as in all organ metastases during 4-6 months. Animals treated by this technique were fully healed of tumour cells and no relapses were observed. This technique could bring similar positive results also in therapy of human MB.

Animals↗
PubMed1999

A review of cutaneous disease in African-American patients.

It is often difficult to determine the role race may play in diagnosis, most notably in patients with deeply pigmented skin. Among the members of any population, there are a significant range of skin colors and hair types which makes generalizing impossible. Deep pigmentation can mask anticipated cutaneous reactions or predispose to severe postinflammatory hypopigmentation and hyperpigmentation. It is imperative that professionals in dermatology recognize reactions in patients with deeply pigmented skin in order to diagnose and treat effectively.

Black People↗
PubMed2000

The incorporation of cocaine and metabolites into hair: effects of dose and hair pigmentation.

The relationship between xenobiotic concentrations in hair and the degree of systemic xenobiotic exposure is poorly defined. The purpose of this study was to evaluate the effect of dose, time, and pigment on the hair incorporation of cocaine (COC) and its metabolites, benzoylecgonine (BE), ecgonine methyl ester (EME), and norcocaine (NCOC). COC was administered by the i.p. route to male Long-Evans (LE) rats at three doses (5, 10, and 20 mg/kg) once daily for 5 days. Fourteen days after the initial injection, the hair was collected and analyzed by gas chromatography/mass spectrometry for the compounds of interest. COC, EME, and NCOC were preferentially incorporated into pigmented hair in a dose-dependent manner. None of the analytes were detected in nonpigmented hair. The plasma pharmacokinetic profile of each analyte was determined at each dose. After normalizing for the plasma concentrations, the incorporation of COC into pigmented hair was 2 orders of magnitude greater than BE. The time course of COC and metabolite distribution into hair was also investigated from 1 h to 14 days after a single dose. After COC disappears from plasma, there is a 3-day delay before maximal hair concentrations are reached in pigmented hair. In nonpigmented hair, concentrations of BE and COC did not exceed 0.25 ng/mg and were undetectable after 4 h and 2 days, respectively. This study demonstrates that the pigment-mediated differences in the incorporation of COC and its metabolites noted at 14 days after dosing are also evident a few hours after drug administration.

Animals↗
PubMed2000

Defects in the cappuccino (cno) gene on mouse chromosome 5 and human 4p cause Hermansky-Pudlak syndrome by an AP-3-independent mechanism.

Defects in a triad of organelles (melanosomes, platelet granules, and lysosomes) result in albinism, prolonged bleeding, and lysosome abnormalities in Hermansky-Pudlak syndrome (HPS). Defects in HPS1, a protein of unknown function, and in components of the AP-3 complex cause some, but not all, cases of HPS in humans. There have been 15 inherited models of HPS described in the mouse, underscoring its marked genetic heterogeneity. Here we characterize a new spontaneous mutation in the mouse, cappuccino (cno), that maps to mouse chromosome 5 in a region conserved with human 4p15-p16. Melanosomes of cno/cno mice are immature and dramatically decreased in number in the eye and skin, resulting in severe oculocutaneous albinism. Platelet dense body contents (adenosine triphosphate, serotonin) are markedly deficient, leading to defective aggregation and prolonged bleeding. Lysosomal enzyme concentrations are significantly elevated in the kidney and liver. Genetic, immunofluorescence microscopy, and lysosomal protein trafficking studies indicate that the AP-3 complex is intact in cno/cno mice. It was concluded that the cappuccino gene encodes a product involved in an AP-3-independent mechanism critical to the biogenesis of lysosome-related organelles. (Blood. 2000;96:4227-4235)

Adaptor Protein Complex alpha Subunits↗
PubMedDate not supplied

[Morphology of hairs on the head and other parts of the body in the residents of Africa].

The morphology of hairs from the head, beard, chest, armpits, and pubis was studied in indigenous population of Sudan, Sierra-Leone, Cote d'Ivoir, Ruanda, Nigeria, Gambia, Kenya, Uganda, Burundi, Zaire, Southern African Republic, Angola, Benin, and Guinea Bissau. A total of 327 hair specimens were examined. A number of new parameters of hairs were determined: thickness, number of cuticle pattern lines per mm, optic edge pattern, cuticle patterns, methods for detecting the cortical and medullar layers, width of hair layers and their transverse sections. The resultant morphological signs are new specific signs for African residents (Negroid) which can be used in forensic medical studies for identifying the race appurtenance of hairs.

Africa↗
PubMed2001

Progressive cerebellar, auditory, and esophageal dysfunction caused by targeted disruption of the frizzled-4 gene.

Wnt signaling has been implicated in the control of cell proliferation and in synapse formation during neural development, and these actions are presumed to be mediated by frizzled receptors. In this paper we report the phenotype of mice carrying a targeted deletion of the frizzled-4 (fz4) gene. fz4(-/-) mice exhibit three distinct defects: (1) progressive cerebellar degeneration associated with severe ataxia, (2) absence of a skeletal muscle sheath around the lower esophagus associated with progressive esophageal distension and dysfunction, and (3) progressive deafness caused by a defect in the peripheral auditory system unaccompanied by loss of hair cells or other auditory neurons. As assayed using a lacZ knock-in reporter, fz4 is widely expressed within the CNS. In particular, fz4 is expressed in cerebellar Purkinje cells, esophageal skeletal muscle, and cochlear inner hair cells, and the absence of Fz4 in these cells is presumed to account for the fz4(-/-) phenotype. In contrast to the early cell proliferation and patterning effects classically ascribed to Wnts, the auditory and cerebellar phenotypes of fz4(-/-) mice implicate Frizzled signaling in maintaining the viability and integrity of the nervous system in later life.

Alleles↗