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Biomedical subjects

M Lahav

Publications and source records attributed to M Lahav.

At least 145 records · Page 8Linked to original sources
PubMed1979

Subepithelial fibrous tissue in failed corneal grafts. A histopathologic study.

Clinical observation of corneal grafts often reveals subepithelial whitish opacities or membranes. To further understand the phenomenon, we undertook a histopathologic study of the changes in this region in failed human corneal grafts. Thinning and thickening of the epithelium, breaks in Bowman's membrane, and growth of subepithelial fibrous tissue were observed. Close association was found between the subepithelial fibrous growth, the breaks in Bowman's membrane, and stromal inflammation.

Basement Membrane↗
PubMed1979

Effect of leukocyte hydrolases on bacteria. XIII. Role played by leukocyte extracts, lysolecithin, phospholipase a2, lysozyme, cationic proteins, and detergents in the solubilization of lipids from Staphylococcus aureus and group A streptococci: relation to bactericidal and bacteriolytic reactions in inflammatory sites.

The bactericidal and bacteriolytic effects of lysolecithin (LL) and egg-white lysozyme (LYZ) on Staph. aureus and group A streptococci and the solubilization of phospholipids from the bacterial membranes by these agents was studied. Low concentrations of lysolecithin (1--10 microgrames/ml) are highly bactericidal for Steph. aureus and group A streptococci, but induce neither bacteriolysis nor solubilization of a substantial amount of membrane phospholipids. On the other hand, while LL at greater than 50 micrograms/ml causes substantial lipid release, a combination of LL and LYZ is absolutely needed to solubilize lipids from streptococci. This combination is, however, not bacteriolytic for this microrganism. The solubilization of lipids from staphylococci by LL is much faster than that induced in streptococci by LL + LYZ. The solubilization of the bulk of membrane lipids from staphylococci can also be achieved by Triton X-100 and by sodium lauryl sulfate and from group A streptococci by Triton X-100 plus LYZ. A variety of other detergents (e.g., Cetavlon, sodium taurocholate, cetyl pyrdinium chloride) have no lipid-releasing properties even in the presence of LYZ. The release of lipids by LYZ (in the presence of LL) from group A streptococci is related to its enzymatic activity, on a still unknown substrate, but not to its cationic nature as this muramidase cannot be replaced by a variety of cation substances (histone, polylysin, leukocyte cationic proteins, polymyxin B, and spermidine). The release of lipids from staphylococci by LL is not inhibited by a variety of anionic and cationic polyelectrocytes (heparin, liquoid, chondroitin sulfate, DNA histone, and polylysine) which markedly inhibit the release of lipids from group A streptococci by LL and LYZ. Streptococci that had been cultivated in the presence of subinhibitory concentrations of penicillin G lose their membrane phospholipids to a larger extent and by much smaller concentrations of LL and LYZ, as compared to controls, suggesting that the interference with the synthesis of the peptidoglycan increases the accessibility of the cell membrane to the lipid-releasing agents. The mechanism by which LL collaborates with LYZ in lipid release is still not known. The possible role of bacterial lipids and lyso compounds in the control of bacterial survival in inflammatory sites is briefly discussed.

Cell Membrane↗
PubMed1979

Effect of leukocyte hydrolases on bacteria. XIV. Bacteriolytic effects of human sera, synovial fluids, and purulent exudates on Staphylococcus aureus and Streptococcus faecalis: modulation by Cohn's fraction II and by polyelectrolytes.

Normal sera and plasma, derived from humans, calves, rats, rabbits, horses, human synovial fluids, inflammatory exudates, and leukocyte extracts, when sufficiently diluted are highly bacteriolytic for Staph, aureus, Strep. faecalis, B. sutilis and to a variety of gram-negative rods. On the other hand, concentrated serum or the other body fluids are usually not bacteriolytic for these bacterial species. While the lysis of Staph, aureus and B. subtilis by diluted serum is not lysozyme dependent, lysis of Strep. faecalis is absolutely dependent on the concentration of lysozyme. The lytic factor in human serum is present in Cohn's fractions III, IV, and V. It is nondialyzable, resistant to heating for 75 degrees C and 20 min, and acts optimally at pH 5.0. Like leukocyte extracts, synovial fluids, and inflammatory exudates, it lyses only young staphylococci. The inability of concentrated serum to lyse Staph. aureus and Strep. faecalis is due to the presence in the gamma globulin fraction of a potent inhibitor, which can be partly removed by dilution of by adsorption upon the homologous bacteria. Lysis of the bacteria is also strongly inhibited by Cohn's fraction II (gamma globulin) by high-molecular-weight DNA, heparin, liquoid, and histone. The possible role played by serum globulin in the protection of bacteria against degradation by leukocyte is discussed.

Animals↗
PubMed1979

Ocular changes in rabbits with corticosteroid-induced ocular hypertension.

Rabbit eyes with steroid-induced ocular hypertension were investigated in order to evaluate the histochemical abnormalities in the chamber angle region. The right eye of 14 rabbits was treated by dexamethasone 1% 3 times daily for 3 to 5 weeks. The eyes were stained by haematoxylin-eosin, periodic acid Schiff, fibrin, colloidal iron, and alcian blue with and without hyaluronidase. All treated eyes developed elevated intraocular pressure up to 4 weeks after treatment. These globes showed alcian-blue-positive hyaluronidase-sensitive staining in the amorphous material adjacent to Schlemm's canal and in the cytoplasmic granules of trabecular endothelial cells. There was no increase in incorporation of radioactive thymidine into nuclei of endothelial cells as seen by autoradiography. These results provide further support for the idea that there is abnormal accumulation of acid mucopolysaccharides in the chamber angle in steroid-induced ocular hypertension.

Animals↗
PubMed1978

Primary mediastinal choriocarcinoma in a male metastatic to the choroid.

A rare metastatic choroidal tumor from primary mediastinal choriocarcinoma in a male is described. This tumor secreted gonadotrophins and showed the histopathologic characteristics of cytotrophoblast and syncytiotrophoblast cells. Early metastatic disease resulted in rapid death; the development of the choroidal metastatic lesion was diagnosed at autopsy.

Adult↗
PubMed1978

Experimental chalcosis: a comparison between in vivo and in vitro findings.

The ocular changes following the introduction of a copper foreign body in the eye of rabbits were studied by histological, histochemical, and quantitative analysis. The findings are compared with previously reported changes observed in vivo. The efficacy of ophthalmoscopy and electroretinography in the early detection of chalcosis is compared with the efficacy of a new method, diagnostic X-ray spectrometry.

Animals↗
PubMed1978

Subretinal pigment cells in malignant melanoma of the choroid.

On examining 54 globes that harbored choroidal malignant melanomas, we found 28 tumors to be composed of spindle cells; 24, of mixed cells; and two, of epitheloid cells. In 80% of the tumors studied, pigment-laden cells had accumulated away from the tumor region and at the periphery of the subretinal space. The number of cells increased in proportion to the extent of retinal detachment, a finding that related directly to the size of the tumor.

Atrophy↗
PubMed1978

An unusual macular lesion simulating a neoplasm.

A 55-year-old woman with reticulum cell sarcoma of the stomach presented with a sudden decrease in vision and acute blood loss anaemia with thrombocytopenia. Superficial retinal haemorrhages were present in both eyes. These haemorrhages were absorbed gradually, yet a large macular mass appeared in the right eye which simulated a neoplasm. This mass disappeared over a period of a few weeks leaving minimal changes in the pigment epithelium and remarkably good visual acuity.

Diagnosis, Differential↗
PubMed1978

Medulloepithelioma of the ciliary body in the goldfish (Carassius auratus).

A medulloepithelioma of the ciliary body in the right eye of a 1-year-old goldfish (Carassius auratus) had spindle and epithelial cells arranged either in columns or around a central lumen. Vitreous-like material was found within the tumor. A medulloepithelioma is a most unusual tumor in fish in which ocular tumors are rare.

Animals↗
PubMed1978

Localization of beta receptors in the anterior segment of the rat eye by a fluorescent analogue of propranolol.

A fluorescent analogue of propranolol, 9-AAP, was injected intravenously in order to detect beta-adrenergic receptors in the anterior segment of the albino rat eye. Specific 9-AAP fluorescence was noted along cell membranes of the ciliary epithelium and to lesser extent in the walls of blood vessels in the ciliary processes and episclera at the limbus. The iris showed maximum 9-AAP binding in the region of the sphincter muscle. These data suggest that 9-AAP may label beta receptors in the anterior segment of the rat eye.

Adrenergic beta-Antagonists↗
PubMed1978

Fuch's heterochromic iridocyclitis: an electron microscopic study of the iris.

The irides of two patients with Fuch's heterochromic iridocyclitis were investigated by electron microscopy. The main findings were abnormal melanocytes with relatively few, small, and at times immature melanin granules, abundance of plasma cells, and membranous degeneration of nerve fibers. The defective melanin production may be due to abnormal adrenergic innervation, either primary or secondary to the inflammatory process. The cause for this inflammatory reaction was not evident in this study.

Cataract↗