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At least 631 records · Page 35Linked to original sources
PubMed1988

Immune mechanisms of tissue destruction in vivo.

In vivo rejection responses are initiated by specific T cell recognition of foreign histocompatibility antigens expressed by tissue allografts, but it is not certain if the effector mechanism mediating the actual tissue injury is also antigen specific. To directly assess the specificity of the effector phase of in vivo rejection responses, we constructed B6 less than----greater than A/J allophenic mice which are genetic mosaics whose individual cells express either H-2b or H-2a histocompatibility antigens, but not both. Trunk skin from B6 less than----greater than A/J allophenic mice was grafted onto immunoincompetent H-2b nude mice and allowed to heal and regrow hair that was both black and white, reflecting the genetic mosaicism of the allophenic grafts. One month after engraftment, the H-2b nude animals were reconstituted with syngeneic H-2b T cells reactive against H-2a allodeterminants. An obvious rejection response ensued involving antigen-nonspecific inflammatory destruction of the epidermis and complete hair loss. Despite the intensity of the nonspecific inflammatory response, the allophenic skin grafts survived Importantly, the allophenic grafts regrew hair and the predominant color of that hair was black, providing visual proof that syngeneic B6 melanocytes and hair follicle cells had not been destroyed. Thus, destruction of skin allografts is mediated by antigen specific effector T cells that assess individual cells within the dermis of the graft for expression of foreign histocompatibility antigens.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Results of ophthalmic examinations of 29 alpacas.

Analysis of the results of ophthalmic examinations of 29 alpacas (Lama pacos) revealed a direct relationship among coat color, iris color, and ocular fundus pigmentation. Alpacas with light-pigmented coats had iris color that included combinations of gray, blue, and brown, and had reduced pigmentation of the ocular fundi. Alpacas with dark coats had brown irides and pigmented ocular fundi. Eleven alpacas had evidence of ophthalmic conditions, including bilateral conjunctivitis (1); formation of a superficial corneal scar (1); formation of posterior synechiae and anterior cataracts (4); development of a deep corneal scar with anterior synechiae, buphthalmia, a subluxated lens, and cataracts (1); development of focal incipient primary cataracts (2); formation of vitreous opacities (1); and development of a unilateral optic nerve coloboma (1).

Animals↗
PubMed2004

Low incidence of iris pigmentation and eyelash changes in 2 randomized clinical trials with unoprostone isopropyl 0.15%.

OBJECTIVE: To assess whether iris color and eyelash changes occur with the use of unoprostone for 2 years. DESIGN: The 2 clinical trials described herein were prospective, randomized, double-masked, active-controlled, parallel group, multicenter studies. PARTICIPANTS: A total of 1131 patients with primary open-angle glaucoma or ocular hypertension participated in 2 clinical trials and received either unoprostone isopropyl 0.15% (659), timolol maleate 0.5% (331), or betaxolol hydrochloride 0.5% (141), 1 drop per eye twice daily for up to 24 months. METHODS: Color photographs (1:1 magnification) were taken of the iris and eyelid of each patient at baseline and at regular intervals thereafter through month 24 using a standardized camera system. Photography included 7 views of each eye plus a calibration photograph and a patient identification photograph, for a total of 16 photographs per patient per visit. Two independent (masked) readers subjectively compared baseline iris colors to subsequent visits. Side view photographs of the upper and lower eyelashes were used for the eyelash length analysis, with each having sufficient depth of field and a sufficient number of eyelashes in focus. Similarly, frontal eyelash views were used for the eyelash density analysis. MAIN OUTCOME MEASURES: Changes from baseline in iris color and eyelash length and density within and between treatment groups. RESULTS: Seven cases of iris color change (1.06%) were confirmed in patients treated with unoprostone for up to 24 months; no confirmed cases were reported in the timolol or betaxolol groups. In the unoprostone group, cases of iris color change were confirmed at months 12 (1 case), 18 (2 cases), and 24 (4 cases). No clinically relevant differences were observed among treatment groups for changes from baseline in eyelash length or density. CONCLUSION: Although iris hyperpigmentation and abnormal eyelash changes may occur after treatment with unoprostone, the incidence of these events appears to be low in the 2-year clinical study.

Adult↗
PubMed1994

Molecular basis of mouse microphthalmia (mi) mutations helps explain their developmental and phenotypic consequences.

Mutations in the mouse microphthalmia (mi) gene affect the development of a number of cell types including melanocytes, osteoclasts and mast cells. Recently, mutations in the human mi gene (MITF) were found in patients with Waardenburg Syndrome type 2 (WS2), a dominantly inherited syndrome associated with hearing loss and pigmentary disturbances. We have characterized the molecular defects associated with eight murine mi mutations, which vary in both their mode of inheritance and in the cell types they affect. These molecular data, combined with the extensive body of genetic data accumulated for murine mi, shed light on the phenotypic and developmental consequences of mi mutations and offer a mouse model for WS2.

Alleles↗
PubMed1984

Lead and cadmium concentrations in the hair of fishermen from the Subae River basin, Brazil.

Previous studies have shown heavy pollution by lead and cadmium in the Subae River basin, State of Bahia, Brazil, caused by a lead smelter. Concentrations of these metals were determined in scalp hair of fishermen from three riverside towns and from a reference town. Increased levels for both metals were associated with increasing proximity to the smelter. Mean concentrations of lead and cadmium were higher among fishermen with straight hair than among those with curly hair. The effects of hair washing, hair type, and color and age on metal concentrations in fishermen's hair were studied.

Absorption↗
PubMed1991

Evidence for alpha-MSH binding sites on human scalp hair follicles: preliminary results.

Alpha-MSH, considered an important pigmentation hormone, binds to melanocytes and is thought to stimulate melanogenesis through a cyclic-AMP-dependent mechanism. The binding of alpha-MSH to follicular melanocytes has been investigated in human hair of different colors, ranging from black to blond and senile white. Hairs were plucked, the follicles were cut off, and an alpha-MSH binding assay, using a radiolabeled alpha-MSH analogue, was performed on these bulbs. As controls of each assay, fragments of hairs of the same person were used. The results show a dose-response relationship and the assay seems to be specific for alpha-MSH, because other peptides such as ACTH, beta-LPH and beta-endorphins do not compete for binding sites as alpha-MSH does. These binding sites seem to be present only on melanin synthesizing melanocytes, since the controls and follicles of senile white hair, which do not contain active melanocytes, show negative results. All the assays were performed on raw material, i.e., whole plucked hair follicles. This is the first time that binding sites for alpha-MSH have been demonstrated on human scalp hair follicles. In addition, their presence was found to be associated with active melanin production; their absence was demonstrated on senile white hair follicles.

Binding Sites↗
PubMed1982

[Occurrence of white Japanese field vole (Microtus montebelli) in the laboratory].

Some field voles with a white coat color were found in the breeding process in the laboratory, originated from a wild population captured in the riverside of the Arakawa in Okegawa, Saitama prefecture in Japan. They had been raised in a room and fed with pelleted feed for herbivore. An attempt was made to analyze their breeding records and mode of inheritance for the white coat color. As a result, the average litter size was 3.80 +/- 1.52, and the age of the first birth was 121 +/- 46.8 in days. This shows that most of the characters of the white voles are not different from those of the agouti ones. From the results of the mating tests, it might be concluded that an autosomal recessive gene was responsible for the appearance of the white coat color.

Animals↗
PubMed1992

Menkes' disease: report of a case and determination of eumelanin and pheomelanin in hypopigmented hair.

We report a male infant with Menkes' disease who showed, at the age of 3 months, slow growth, hair abnormalities such as pili torti and white hair, and low levels of serum copper and ceruloplasmin. The exceptionally bright portions of his hair contained eumelanin and pheomelanin at levels only half those of normal Japanese controls. After subcutaneous administration of copper-histidinate for 2 months, his scalp hair changed to dark brown.

Ceruloplasmin↗
PubMedDate not supplied

Protective effect of superoxide dismutase against hair graying in a mouse model.

Oxygen free radicals play a role in the aging process, and the protective effect of various antioxidants has been intensively studied, in particular for cutaneous aging. Besides hereditary factors, free radical-mediated damage to melanocytes of the hair follicle has been considered as a mechanism for aging of the hair. It was the aim of this study to evaluate the role of photosensitization reactions for hair graying and to demonstrate potential protective effects of superoxide dismutase (SOD). Mice with black hair were depilated with the fingertips on a surface of 6 x 2.5 cm on both sides of the dorsum. The right side received five applications of a SOD-containing gel before exposure to psoralen (concentration 0.5 mg/mL) plus UV-A (365 nm, 4 J/cm2). The left side was pretreated in the same way with a gel free of SOD. When the hair started growing again, the SOD-protected side was covered with black hair, whereas the hair on the vehicle-treated side was gray or white in 27 of the 30 animals studied. The 0.01% SOD concentration was as protective as the 0.1% concentration. Heat-inactivated SOD, applied in another five animals, was not protective. Using fluorescent labeling of the SOD with fluorescein isothiocyanate, epifluorescence microscopy and digital imaging processing, we show that SOD applied to the skin surface penetrates through the follicular appendages, as well as through the unbroken stratum corneum. Our findings suggest that superoxide radicals, generated by interaction of UV-A light with the sensitizer, initiated the formation of secondary products with well-known DNA-damaging effects, such as lipid peroxidation products and tumor necrosis factor alpha. SOD prevented the damage to melanocyte DNA by dismutating superoxide. Photosensitization may be another mechanism for hair graying, which can be influenced by antioxidants. Given the large number of exogenous and endogenous sensitizers, this mechanism deserves further study for human hair graying.

Animals↗
PubMed1998

Black hair follicular dysplasia, an autosomal recessive condition in dogs.

Using histology, a coat color abnormality and the subsequent hair loss were diagnosed as black hair follicular dysplasia. A pedigree analysis of an affected litter and literature review suggests that this is inherited as an autosomal recessive trait. The melanocyte stimulating hormone receptor gene is ruled out by using linkage analysis.

Animals↗
PubMed1993

Pili trianguli et canaliculi: a distinctive hair shaft defect leading to uncombable hair.

Uncombable hair syndrome refers to a clinical disorder characterized by scalp hairs arranged in bundles in all directions that resist to brush and comb. Several entities may lead to spun-glass hair. As a rule the syndrome becomes obvious during the first years of life. The hair is normal in quantity, and increased fragility is not a common feature. The hair is often dry with silvery blond color. Under the light microscope the hairs may appear normal. Scanning electron microscopy shows a characteristic triangular, kidney- or heat-shaped diameter with typical longitudinal canalicular deformation. We present a 9-year-old girl with the typical clinical features of pili trianguli et canaliculi. Investigation by scanning electron microscopy confirmed the diagnosis. In addition the girl had enamel defects of the teeth and nail abnormalities that classify for a subtype of ectodermal dysplasia.

Child↗