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PubMed1992

Scanning electron microscopy of the mucosal surface of the forestomachs and abomasa of grey, white and black Karakul lambs.

Homozygous grey and white Karakul lambs suffer from a lethal genetic factor causing death after weaning. Previous studies revealed large milk-filled rumens in the grey and white lambs which was attributed to a significant decrease in the number of myenteric ganglia and neurons in the rumen wall. This study was undertaken to determine the effect of milk on the epithelial lining of the forestomachs of affected grey and white lambs. In the forestomachs of the black lambs the polygonal epithelial cells were tightly packed, seemed to overlie one another and cytoplasmic projections occurred on the cell surfaces. In the grey and white lambs the epithelium had an eroded appearance due to sloughing of the surface cells and the cytoplasmic projections were lower and had a weathered appearance compared to the black lambs. No obvious differences could be detected in the abomasa of grey, white and black lambs. It is concluded that the milk in the forestomachs of the grey and white lambs is responsible for the epithelial changes.

Abomasum↗
PubMed1992

A comparative study of the thickness of the tunica muscularis in the forestomach and abomasum of grey, white and black Karakul lambs.

Homozygous grey Karakul lambs are born with a lethal genetic factor responsible for death and weaning age. When put on a high roughage diet under field conditions they develop distended, thin-walled rumens and sand impacted abomasa. Homozygous white Karakul lambs have a similar factor but survive for a longer period. Black Karakul lambs are not affected. The present study was undertaken to compare by image analysis the thickness of the tunica muscularis of the forestomach and abomasum of 24-hour old grey, white and black Karakul lambs. One square centimetre samples were taken from equivalent areas in each case of the rumen, reticulum, omasum and abomasum of 38 embalmed Karakul lambs. Haematoxylin and eosin stained histological sections of each sample were studied with a Vids 2 Image Analyzer and the thickness of the circular and longitudinal muscle layers was measured. An analysis of variance indicated a significant difference between the groups in the thickness of the tunica muscularis of the rumen, reticulum and abomasum; the grey group displaying the thinnest and the black group the thickest. The omasa were not affected. The study indicates a reduction in thickness of the tunica muscularis of the homozygous grey and white lambs when compared to normal black lambs.

Abomasum↗
PubMed2003

[Function of the hypothalamo-pituitary-adrenal system in mice with ectopic overexpression of agouti protein].

Agouti protein (AP) is known to antagonise the effects of melanocortins (ACTH, MSH) on the melanocortin receptors which participate in regulation of central and peripheral HPA links. This study aimed at estimation of effects of dominant mutation Agouti yellow (Ay-ectopic overexpression Agouti protein) on the HPA axis function in mice. Male mice of C57B1/6J strain of Ay/a- and a/a genotypes (control animals, lack of AP), were used. We demonstrated that basal corticosterone level in the Ay mice matched those of control animals. Stress-activated corticosterone level (p < 0.02) and sensitivity of adrenal to low doses ACTH in vitro and in vivo were higher in Ay mice compared with control mice. Dexamethazone-inhibition of stress-reactivity was more intensive in Ay/a than in a/a mice (p < 0.0007).

Agouti Signaling Protein↗
PubMedDate not supplied

A study of the photolightening mechanism of blond hair with visible and ultraviolet light.

In this study the photolightening behavior of blond hair was investigated. The results demonstrated that visible (VIS) and ultraviolet (UV) light lighten blond hair through different mechanisms. VIS light was found to contribute much more to the lightening of blond hair than UV light, and acted directly, while UV light only lightened blond hair that had been washed following irradiation. VIS and UV light both, however, lightened to a similar degree isolated melanin granules and decomposed melanin granules that were exposed on a cross section of blond hair. These results indicate that melanin granules are equally sensitive to both forms of light while blond hair is most sensitive to VIS light. The results also indicate that hair tissues, excluding melanin granules, are damaged by UV light but not by VIS light. Based on these facts, the hypothetical lightening mechanism of UV light is assumed to be that UV light preferentially attacks and damages hair tissues rather than melanin granules. This occurs only after the hair is washed, as the washing process removes the melanin granules that effuse from loose hair fibers. In contrast, VIS light preferentially attacks and decomposes the melanin granules rather than other tissues, and also results in the lightening of blond hair but without the need for subsequent washing. We also found that while VIS light destroys the structure of isolated melanin granules, UV light does not act in a similar manner. Consequently, it is proven that VIS and UV light attack different sites of the melanin granule, even though the lightening rates from both light sources are similar.

Hair↗
PubMed2004

[MC1R--the key gene in mammalian melanin synthesis].

The study of the molecular regulation mechanism of melanin synthesis during animal development has become a new focus recently . The synthesis and production of melanin during animal development are regulated by many genes. This paper summarized the molecular function mechanism of melanocortin-1-receptor (MC1R) gene and the relationship between the consequences of polymorphic variation of the gene and melanin traits, in addition to summarized the identification and mutation of MC1R gene in birds. Furthermore, the melanin synthesis mechanism in birds is also discussed here.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

A study of the photolightening mechanism of red hair with visible and ultraviolet light: comparison with blond hair.

The photolightening behavior of red hair was investigated. Red hair was found to lighten to a similar extent by irradiation from both ultraviolet (UV) and visible (VIS) light. Under the same irradiating conditions, blond hair was lightened by VIS light but did not lighten by UV light until it was washed after irradiation (1). These different photolightening behaviors of red and blond hair are supposed to be due to differences in their melanin compositions. The dominant type of melanin in red hair is pheomelanin; while blond hair investigated in the previous work contained both eumelanin and pheomelanin, with mainly eumelanin (2). Consequently, in this investigation, the photolightening behaviors of red and blond hair were compared to clarify the differences in photosensitivity between the two types of melanin.

Hair Color↗
PubMedDate not supplied

The importance of socio-economic status and individual characteristics on the prevalence of head lice in schoolchildren.

Pediculosis is a common infestation in schoolchildren but little is known about the factors influencing its prevalence. The aim of this study was to determine the prevalence of head lice in schoolchildren in Ghent and to investigate the independent association between individual characteristics of the child, socio-economic status (SES) of the family and head lice. The prevalence of head lice at baseline and 14 days after treatment advice was determined by the wet combing method in a total of 6,169 schoolchildren age 2.5 to 12 years from Ghent (Belgium). Age, sex, educational level and hair characteristics of the child, SES of the family, and number of children in the family was collected by the school health department. The prevalence of head lice was 8.9%. The only statistically significant factors at the child level are SES, the number of children in the family, hair length and hair colour. Treatment failure was recorded in 41% of the children positive at baseline screening and was significantly related to hair colour and SES. This study demonstrated that the prevalence of head lice is determined by clustering of children rather than by characteristics of the child. The management of head lice should take a community-based approach equally involving families, schools, health care professionals and the government.

Animals↗
PubMed2005

[Attractin].

Explore the source record for details and available documents.

Agouti Signaling Protein↗
PubMed2005

Eyebrow colour in diabetics.

BACKGROUND: Hair colour may be affected by a metabolic disease. Systematic investigations in diabetics are missing. OBJECTIVE: A clinical study was performed to evaluate whether dark colour of eyebrows in greying males is associated with diabetes or not. SETTING: Academic teaching hospital, inpatient and outpatient department. METHODS: In an uncontrolled analysis two groups of male patients between 50 to 70 years of age were investigated for evidence of diabetes mellitus. Inclusion criteria were original scalp hair colour brown to black with more than 50% greying hair, no chemotherapy, hormone (except insulin) or interferon treatment, current or previous, no artificial colouring of hair, and absence of total alopecia. Group A consisted of 50 males with dark eyebrow colour, group B of 50 males with greying of eyebrows. A careful medical history and clinical examination was performed. In patients without known diabetes, blood sugar levels (profile during the day) and HbA1c were evaluated. RESULTS: In group A 38 of 50 patients (76%) were diabetics type II. The mean duration of diabetes was 3.4 years (SD 6.8 years; range 1 year to 31 years). Six patients were diagnosed as having diabetes for the first time. In group B 9 of 50 patients (18%) were diabetics, two of type I and 7 of type II. One patient with a newly detected diabetes type II was seen. The mean duration of diabetes was 4.1 years (SD 7.6 years; range: 1 year to 39 years). The difference in diabetes frequency is statistically highly significant (two-sided t-test: p<0.0001). Odds ratios (OR) for diabetes are higher in greying males with dark eyebrows (OR 3.17) vs. those with greying eyebrows and scalp hair (OR 0.19) in this age group. CONCLUSIONS: In male diabetics at the age of 50 years or more greying of the eyebrows seems to be inhibited or delayed. The presence of dark eyebrows with greying scalp hair in males might be a clinical sign for patients at risk of diabetes type II.

Aged↗
PubMedDate not supplied

[The site of the action of the angora-Y gene and its interaction with the fuzzy-Y gene in the mouse].

The site of action of the goY mutant gene was determined in the aggregation chimaeras C57BL-goY/goY----DBA (+/+). Chimerism was detected by mosaicism of coat pigmentation and electrophoretic pattern of glucose phosphate isomerase. In 28-day-old chimaeras the regions of light-brown coat alternated black coat, stripes of short hairs alternated those of long hairs. These stripes of different length and width extended from spine in lateral-ventral direction. The hairs plucked from long hairs stripes had a similar length that those of goY/goY mice of same age, but the hairs plucked from short hair stripes corresponded to the hair length of +/+ mice. These data show that the goY gene acts in epidermal cells of hair follicles and its expression is autonomous. It has been established that in double homozygotes goY/goYfzY/fzY both mutant genes are expressed: the considerable increase of hair length as compared to norm--the effect of the goY gene and curly coat--the effect of the fzY gene. In goY/goYfzY/fzY mice during the formation of G1 guard hairs the incomplete expression of the goY gene is observed that is due to the suppression of hair growth by the fzY mutant gene. The fzY gene does not suppress the growth of G2 hairs and therefore the full expression of the goY gene occurs in goY/goYfzY/fzY adult mice.

Animals↗