bromochloroacetic-acid and Albinism

An experimental model of proliferative vitreoretinopathy was developed in the rabbit eye by injecting a solution of human platelet-rich plasma. In this model we evaluated the progression with time of intraocular inflammation and the rate and origin of cell proliferation. A sterile solution adjusted to 107 platelets was injected into the right eye of a total of 46 pigmented and 14 albino rabbits. Animals were sequentially sacrificed at days 7, 14, 21 and 1 month after injection. Clinical evaluation of vitreoretinal proliferation, using a classification in six grades, and of anterior segment inflammation assessed by a Laser Flare Meter, were done for 1 month after injection, before histopathological analysis. Eighty percent of eyes developed tractional retinal detachment in 1 month. Histopathology showed intense cell migration and proliferation in the area of the ciliary body, as early as the seventh day, then further increasing rapidly. Infiltrates were composed of cytokeratin- and vimentin-expressing cells. Abnormal expression of vimentin was also found in ciliary and retinal epithelia and in M¿ller cells. Inflammation measured by the Laser Flare Meter was maximal at day 11 and then reached a plateau at significantly higher levels than controls. Albino rabbits showed significantly lower grades of proliferation, as compared to pigmented rabbits. This study thus clarified some characteristics of experimental vitreoretinal proliferations that that proved similar to those in human diseases, such as the involvement of ciliary body and retinal pigment epithelium, the existence of inflammatory reactions preceding cell proliferation and strong changes in intermediate filaments. This may provide a simple and valuable model for antiproliferative assays and shed some light on the pathogenesis of intraocular proliferative disorders.

Topics: Albinism; Animals; Cell Division; Ciliary Body; Immunohistochemistry; Inflammation; Keratins; Lasers; Male; Rabbits; Retina; Vimentin; Vitreoretinopathy, Proliferative; Vitreous Body

Subcellular defects of hypomelanosis in tuberous sclerosis (TS) (28 subjects) were compared by light and electron microscopy with oThere forms of congenital circumscribed hypomelanosis that occur in nevus depigmentosus (ND) (8 subjects) and in piebaldism (PB) (4 subjects), respectively. On the light microscopic level in both TS and ND, the population density of functioning melanocytes was normal but each perikaryon was small, and dopa activity was decreased. On the ultrastructural level, the hypomelanotic skin and hair of TS were associated with a decrease in the synthesis, melanization, and size of melanosomes; the decrease in the size of melanosomes resulted in the aggregation of melanosomes (i.e., a melanosome complex) in the keratinocytes in all the specimens examined. In ND, ther were no obvious changes in the size and melanocytes. the hypomelanosis of ND is related to the decreased synthesis and also, perhaps, abnormal transfer of melanosomes. In PB the hypomelanosis of the skin and hair results from the absence of functional melanocytes. The hypermelanotic areas of PB, however, characteristically contain melanocytes that synthesize abnormal (sperical and granular) as well as normal (ellipsoidal and lamellar) melanosomes.

Topics: Adolescent; Adult; Albinism; Black People; Child; Child, Preschool; Dihydroxyphenylalanine; Female; Hair; Humans; Infant; Keratins; Male; Melanins; Melanocytes; Microscopy, Electron; Nevus; Organoids; Pigmentation Disorders; Skin; Skin Neoplasms; Tuberous Sclerosis; White People

Topics: Albinism; Animals; Chickens; Electrophoresis, Disc; Feathers; Keratins; Methods; Microscopy, Electron, Scanning; Molecular Weight; Mutation

Topics: Albinism; Black People; Body Temperature; Erythema; Humans; Keratins; Pellagra; Pigmentation; Skin; Sunburn; Ultraviolet Rays