INTRODUCTION Melanotic variant of oncocytic metaplasia of the nasopharynx is an extremely rare condition. CASE REPORT A 73-year-old Japanese man presented with nasal congestion and chill. Nasoscopic examination revealed multiple black nodules around the bilateral torus tubarius. The nodules were biopsied to determine the histology. The clinical differential diagnosis was malignant melanoma or...

1). If these lesions were at the level of the RPE, one would expect themtobevisualizedonFAFimaging.However, theywere completely silent on FAF imaging, suggesting that they may be located deeper than the RPE, at the level of the choriocapillaris.Wedistinguished 3 types of lesions basedon theirmultimodal imaging characteristics in APMPPE. Type 1 lesions seem to be located at the level of the chor...

The light and electron microscopic features of pigmented cells in the adult dog pineal gland have been described. The presence of pigmented cells was a constant characteristic of the dog pineal gland, though wide variations in the amount of pigment could be found among different animals. Conversely, the localisation of pigmented cells was very constant on the basal surface of the proximal regio...

Although the incomplete degradation of phagocytosed outer segment discs is thought to result in the formation of lipofuscin, there has to date been no proof of this concept. We report for the first time that cultured human retinal pigment epithelial (RPE) cells fed daily doses of isolated rod outer segments for periods of up to 3 months were capable of developing intracellular autofluorescent g...

Two enzymes, P-galactosidase and N-acetyl-fi-glucosaminidase, have been detected in pigment epithelial cells of cattle. The optimum activity for N-acetyl-P-glucosaminidase is at pH 5; in contrast, /3-galactosidase exhibits a broad activity maximum from approximately pH 4 to 6, with a "shoulder" in the latter range. Differential centrifugation of .25M sucroseethylenediamine tetraacetic acid (EDT...

Cytoplasmic microtubules (MTs) continuously grow and shorten at free plus ends. During mitosis, this dynamic behavior allows MTs to capture chromosomes to initiate their movement to the spindle poles; however, the role of MT dynamics in capturing organelles for transport in interphase cells has not been demonstrated. Here we use Xenopus melanophores to test the hypothesis that MT dynamics signi...

A 34-year old man was admitted to hospital because of persistent fever and massive hepatosplenomegaly. His past history included excision of a melanoma of the right ear at the age of 16. A blood cell count showed anemia, thrombocytopenia and normal white blood cell (WBC) count with normal differential count. Neutrophils and monocytes containing black pigment were detected in the peripheral bloo...

Lipofuscin pigment granules (LPG) have been implicated as a marker of cellular aging. We have quantitated the content of LPG in human retinal pigment epithelium (RPE) as a function of age. Furthermore, topographic distribution of LPG within individual eyes was measured. Microspectrofluorometric determination of the distribution of LPG in human RPE cells revealed a progressive accumulation of LP...

PURPOSE Lipofuscin accumulates in human retinal pigment epithelium (RPE) cells with age and may be the main factor responsible for the increasing susceptibility of RPE to photo-oxidation with age. As the composition, absorption, and fluorescence of lipofuscin undergo age-related changes, the purpose of this study was to determine whether photoreactivity of lipofuscin granules also changes with ...

Mepacrine uptake into platelets and bone marrow megakaryocytes was analyzed to further characterize the dense granule defects in a group of seven mouse pigment mutants that have characteristics of platelet storage pool disease (SPD). In contrast to our previous studies using electron microscopy, this method revealed that all mutants had normal numbers of dense granules. However, total mepacrine...