Biomedical subjects

M M Rodrigues

Publications and source records attributed to M M Rodrigues.

201 records · Page 12Linked to original sources

PubMedDate not supplied

Lipofuscin pigment over benign and malignant choroidal tumors.

This study has shown that lipofuscin pigment may accumulate in RPE cells and macrophages over several types of benign and malignant choroidal tumors. The color of the pigment, however, varies with the nature and color of the underlying lesion. On the surface of deeply pigmented tumors the lipofuscin pigment may produce an orange color, whereas over amelanotic lesions it may appear brown or reddish-brown. On the surface of vascular tumors, such as choroidal hemangiomas, the lipofuscin is almost invisible ophthalmoscopically but may be demonstrated with fluorescein angiography. Although the presence of such pigment accumulation is suggestive of a malignant melanoma, it is not diagnostic and may occur over benign simulating lesions as well.

Choroid↗

PubMedDate not supplied

Lipid deposits posterior to impermeable intracorneal lenses in rhesus monkeys: clinical, histochemical, and ultrastructural studies.

Synthetic materials are being evaluated for their potential long-term use in corneal refractive surgery. Clinical and histopathologic studies were performed with polymethylmethacrylate (PMMA) and polysulfone intracorneal lenses in rhesus monkey eyes that were followed for up to 3 years. The 5 mm diameter lenses were placed in the deep posterior corneal stroma of four eyes. Fine, polychromatic crystalline deposits formed a layer posterior to the implants. Enucleated eyes had the corneas either frozen for histochemistry or fixed for electron microscopy. Special stains included oil red 0 and filipin on fresh frozen tissue. The cornea, with a PMMA intracorneal lens showed myriad crystalline aggregates in the deep corneal stroma behind the implant. These crystalline deposits stained positively with oil red 0 and with filipin indicating the presence of neutral fat as well as unesterified cholesterol. The polysulfone implant showed no evidence of crystalline deposits histologically but was surrounded by homogeneous aggregates that could represent nonspecific reaction to the lens material or protein deposits. Electron microscopy of all four corneas revealed dissolved lipid aggregates and laminated electron dense material that were most abundant posterior to the implant where the keratocytes appeared disintegrated. The PMMA lens appeared to induce lipid keratopathy.

Animals↗

PubMedDate not supplied

Spectrum of trabecular pigmentation in open-angle glaucoma: a clinicopathologic study.

In eight patients with chronic open-angle glaucoma and associated trabecular pigmentation, trabeculectomy and peripheral iridectomy specimens were studied by light and electron microscopy. Clinically, three patients displayed signs of classic pigmentary glaucoma (Group 1). In the other cases chronic open-angle glaucoma was associated with varying degrees of expression of the full pigmentary glaucoma syndrome (Group 2). Histopathologic examination of peripheral iridectomy and trabeculectomy specimens from Group 1 showed: (1) marked focal atrophy and hypopigmentation of iris pigmented epithelium with an apparent delay in melanogenesis. The dilator muscle was thickened except for occasional thinned areas. (2) The trabeculectomy specimens revealed excessive amounts of pigmented epithelial melanosomes and moderate accumulation of electron-dense basement membrane-like material in the juxtacanalicular meshwork. Similar specimens from Group 2 showed: (1) minimal hypopigmentation of the iris pigmented epithelium with normal melanogenesis. The iris stroma and dilator muscle were normal. (2) Trabeculectomy specimens displayed excessive electron-dense basement membrane-like material in the juxtacanalicular meshwork and minimal to moderate accumulation of melanosomes.

Adolescent↗