摘要:

The uveitogenicity of melanin has been a controversial subject for a long time, presumably as a result of the use of ill‐defined preparations in the experiments. We have developed procedures for the preparation of purified uveitogenic melanins from the retinal pigment epithelium and choroid that are free from pathogenic retinal photoreceptor proteins. The active melano‐antigen is located at the surface of the melanin granules and is probably identical in both tissues. It retains its pathogenicity in hot polar detergent and during in vitro proteolysis, but it is inactivated by macrophage phagocytosis and hydrolysis in hot hydrochloric acid. Lewis rats immunized with microgram doses of bovine retinal pigment epithelial or choroidal melanin develop severe experimental autoimmune anterior uveitis (EAAU) about 10 days later. Retinitis and pinealitis are not observed. Skin melanin prepared in a similar way evokes EAAU as well, but it is only weakly pathogenic. EAAU cannot be transferred by serum, and its development can effectively be inhibited by antibodies to the inciting antigen and by cyclosporin. Vitamin E treatment of the animals causes a delay in its onset. The results indicate that cell‐mediated immunity plays a dominant role in the pathogenesis of EAAU. This is the first time it has been shown that purified ocular and skin melanins are able to induce an autoimmune disease. The relevance of this finding for the study of melanin‐related immunopathology in man is di

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1993.tb00574.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Intrinsic melanogenic inhibitors with high molecular weights have been isolated from Greene's amelanotic hamster melanoma by DEAE ion‐exchange and gel filtration chromatographies. The native molecular weights of two partially purified inhibitors have been determined to be 15 kDa (β‐type) and 67 kDa (γ‐type), respectively, using HPLC gel filtration. Both types of inhibitors, despite their inability to directly inhibit isolated tyrosinase, have been shown to markedly inhibit melanin formation in cultured B16 cells. In contrast to the β‐type inhibitor, the γ‐type inhibitor can induce depigmentation in B16 cells without abolishing their internal tyrosinase activity. Further, it has been determined that both inhibitors contain various amounts of unsaturated fatty acids, C15:1, C18:1, C18:2, C18:3, C20:3, and C20:4, which exhibit depigmentary activities on cultured B16 cells. C15:1 is low in the β‐type, but high in the γ‐type whereas C18:3 is high in the β‐type but low in the γ‐type. These results suggest that the differential action of these inhibitors is most likely due to the composition of th

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1993.tb00575.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The pattern of octamer sequence‐specific DNA binding proteins expressed in human melanoma was examined in nuclear extracts of seven surgically‐isolated tumors, short‐term cultures of these tumors, and 25 human melanoma cell lines to determine the in vivo and in vitro distribution of the melanocytic‐associated Oct‐M1 and Oct‐M2 octamer binding activities. In the biopsy tissue and cultured melanoma cells of a metastasis from the cerebellum, two other binding activities (N‐Oct‐2 and N‐Oct‐6) in addition to the Oct‐M1, Oct‐M2 and the generally expressed Oct‐1 protein were detected; this profile was consistent with that seen in normal human and mouse brain tissue. Melanoma tissue removed from lymph nodes and cell lines established from them also showed Oct‐1, Oct‐M1, Oct‐M2, and N‐Oct‐2. N‐Oct‐2 was distinguished from the comigrating Oct‐2A activity by failure to react with Oct‐2A‐specific antibody. All but one of the 25 melanoma cell lines exhibited Oct‐1, Oct‐M1, and Oct‐M2 and/or N‐Oct‐2 activity, whereas cultured normal melanocytes expressed only Oct‐1 and Oct‐M1. In contrast to murine fibroblasts, which express only Oct‐1, human fibroblast strains also expressed Oct‐2A binding activity, which was confirmed by reactivity with Oct‐2A antibody and the presence of Oct‐2A mRNA and indicated that Oct‐2A has a more general role than that of a lymphoid‐specific transcription factor. Overall, the results indicate that expression of neural‐specific Oct factors in human melanoma is (1) aberrant compared with normal melanocytes, (2) can be modulated by the surrounding tissue in a brain metastasis, and (3) may be p

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1993.tb00576.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Vitiligo, a skin disease, characterized by the spontaneous loss of melanin, has been described in several animals as well as in humans. Most of the reports of large domestic animals have dealt with clinical investigations without morphological data. In this report, the histological and ultrastructural characteristics of two cases of vitiligo in water buffaloes(Bubalus bubalis)are presented. Interestingly, many of the ultrastructural observations for vitiliginous buffaloes resemble those previously described for other species, e.g., humans, mouse, and chicken. These data suggest that one or more forms of human vitiligo may have a similar etiopathogenesis to that of the buffalo. Therefore, it is proposed that vitiliginous buffalo may prove to be a useful animal model for the human disease.

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1993.tb00577.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The red abdominal skin of the neon tetraParacheirodon innesiand the cardinal tetraP. axelrodiwas found to blanch at night or in the dark. Melatonin added to the bathing medium caused blanching of the red skin. Microscopic observations of the erythrophores indicated that the erythrosomes aggregated in response to norepinephrine, melanin‐concentrating hormone (MCH), and melatonin. Of these compounds, melatonin was the most effective. By contrast, many erythrophores were refractory to MCH. Alpha‐melanophore‐stimulating hormone, isoproterenol, adenosine, and ATP each caused dispersal of the pigment to some extent. Isoproterenol dispersed the pigment only when an alpha‐adrenergic blocker, tolazoline, was present. It appears that the change in color of the abdominal skin is primarily due to increased secretion during the night of the pineal hormone melatonin, while other hormonal and nervous factors may modify the distribution of the pigment in the erythr

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1993.tb00578.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Like melanophores of many teleosts, those of the dark chub,Zacco temmincki, and the common minnow,Z. platypus(Cyprinidae, Cypriniformes) responded to norepinephrine (NE) by the aggregation of pigment. It was further found that some melanophores were responsive to acetylcholine (ACh) in the same way. The response to NE was blocked by an alpha‐adrenergic blocker, phentolamine, whereas the response to ACh was not. By contrast, two muscarinic cholinoceptor antagonists, namely, atropine and scopolamine, effectively blocked the action of ACh. The pigment aggregation due to the liberated sympathetic neurotransmitter was blocked by phentolamine but not by cholinergic blockers. These results suggest that, although the melanophores of these species are controlled in an orthodox manner by the sympathetic nervous system, some of them possess extra muscarinic cholinoceptors that also mediate the aggregation of pigment. The present report is the first to describe the presence of cholinoceptors on the chromatophores in species of fish other than those that belong to the order Siluriformes. The evolutionary implications of these findings are discusse

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1993.tb00579.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

In an orange‐colored variant of the medaka fish,Oryzias latipes, which is homozygous forballele, the melanophores represent a tissue‐specific differentiation, manifesting an amelanotic appearance in the skin, an incomplete melanogenesis in the choroid and the peritoneum, and mosaic phenotype‐like melano‐iridophores in the peritoneum. In a wild‐type strain of this species carrying theBgene, all melanophores are terminally differentiated irrespective of the tissues in which they are located. This indicates that the deficiency ofBgene impairs the differentiation of melanophores in the medaka. Electron microscopy disclosed that the deficiency ofBgene causes deterioration of melanogenesis to occur inside the melanosomes and that the manner of deterioration in the melanophores in the skin, the choroid and the peritoneum is different. The ubiquitous occurrence of reflecting platelet‐laden melanophores in the peritoneum of this variant and the total absence of a mosaicism in pigment cells of the wild‐type strain indicate that the deficiency ofBgene predestines melanoblasts distributed in this tissue to an ambiguous state with regard to their differentiation. Little difference is observed between melanosomes maturation in pigment epithelial cells of the orange‐colored variant and the wild‐type strain, indicating an innocent role of theBgene in thei

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1993.tb00580.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1993.tb00581.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1993.tb00582.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1993.tb00583.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY