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Biomedical subjects

S M Bonsib

Publications and source records attributed to S M Bonsib.

61 records · Page 4Linked to original sources
PubMed1984

Fibromuscular dysplasia: an unusual cause of hypertension in the transplant recipient.

A transplant recipient developed hypertension from unsuspected fibromuscular dysplasia of the donor renal artery. We believe this is the first reported case of this disease transmitted by transplantation. Successful repair of the stenosis was obtained by resection of the stenotic area and reanastomosis to the internal iliac artery. While the diagnosis of fibromuscular hyperplasia was not suspected in our donor prior to organ retrieval, its eventual occurrence in the transplanted kidney suggests that when the donor clinical picture is appropriate the lesion should be searched for prior to use of the organs.

Adult↗
PubMed1975

Factors contributing to the inhibition of aspartate aminotransferase by dicarboxylic acids.

At pH 8.0 aspartate aminotransferase (L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1) reacts with the modified substrate, erythro-beta-hydroxy-L-aspartate, to form a mixture of enzyme-substrate complexes absorbing at 492 nm. A variety of dicarboxylic acids were studied spectrophotometrically as competitive inhibitors of this reaction. All of the inhibitory dicarboxylic acids form a complex with the enzyme, absorbing at 362 nm. In addition, some of the dicarboxylic acids form a protonated complex absorbing at about 435 nm. This complex, which is the conjugate acid of that absorbing at 362 nm, is formed only by those dicarboxylic acids which can assume a configuration in which the two carboxyl groups are positioned as in maleic acid. Bulky substituents, such as aromatic rings or even methyl groups, prevent the formation of the protonated complex, presumably because of steric restrictions at the active site. Substitution of the central carbon atom of glutaric acid by heteroatoms of increasing charge density results in a progressive decrease in inhibitory effectiveness, at pH 8, primarily due to a loss of this pH-dependent stabilization of the enzyme-dicarboxylic acid complex. Acids with an aromatic ring are among the most potent dicarboxylic acid inhibitors of this enzyme in spite of the fact that they do not undergo the pH-dependent stabilization of their enzyme complexes. From these observations it was concluded that the affinity of aspartate aminotransferase for dicarboxylic acids is determined as much by the mechanism of binding as by the solvation and steric effects.

Animals↗
PubMedDate not supplied

The macula densa tubular basement membrane: a unique plaque of basement membrane specialization.

The inner (luminal) surface of the macula densa (MD) basement membrane (BM) was exposed by solubilization of the overlying epithelium permitting examination of its structural features by scanning electron microscopy (SEM). Nineteen macula densa BM were identified in five autopsy kidneys and seven renal biopsies by this SEM technique. The MD BM consists of an oval plaque of specialized BM, restricted to the glomerular hilum and arteriolar aspect of the thick ascending limb of Henle. It contains haphazardly oriented shallow tunnels, slender pleats, and bridges of BM which do not resemble any other nephron BM examined by this technique. The MD BM, critically located between MD and lacis cells appears to firmly anchor the MD to the juxtaglomerular apparatus and may amplify the extent of interaction between lacis cell processes or lacis cell interstitial space and MD cell processes.

Basement Membrane↗
PubMedDate not supplied

Cytokeratin-containing globular filamentous bodies in renal oncocytoma.

Eighty-four cortical neoplasms were studied for cytokeratin and vimentin expression by immunohistochemistry and for intermediate filament aggregates by electron microscopy. Twenty oncocytomas expressed cytokeratin, 16 in a distinctive punctate pattern. These same 16 tumors also contained small globular filamentous bodies (GFB) by electron microscopy. The GFB were characterized by a matrix of intermediate-sized filaments with incorporation of diverse cell organelles such as endoplasmic reticulum, lysosomes, mitochondria, and lipid. The GFB were not within a unit membrane. Although 11 of 64 carcinomas also contained intermediate filament aggregates, only 2 of these solely expressed cytokeratin, and this was restricted to a few cells in small foci. Small GFB were also present in 5 carcinomas by electron microscopy. Three mixed clear and granular cell carcinomas contained only rare cells, whereas 2 sarcomatoid carcinomas, both of rhabdoid cell phenotype, contained numerous GFB that coexpressed vimentin and cytokeratin. Cytokeratin-containing GFB are common in oncocytomas but are uncommon in carcinoma, and, when numerous, may provide a diagnostically useful immunohistochemical feature with which to distinguish oncocytoma from its carcinoma congeners.

Adenoma↗
PubMedDate not supplied

Renal chromophobe cell carcinoma: limitations of paraffin-embedded tissue.

Chromophobe cell carcinoma of the kidney is distinguished from other renal cortical tumors by the ultrastructural presence of numerous cytoplasmic vesicles of unknown composition. Failure to detect vesicles in paraffin-embedded tissue in the archival material of 10 putative chromophobe cell tumors stimulated an investigation into the effects of fixatives and dehydrating solvents on vesicle integrity. We found that although vesicles are removed by dehydrating agents during paraffin embedding, osmium tetroxide postfixation prevents vesicle loss during dehydration for electron microscopy. We conclude that paraffin-embedded tissue is useless for histochemical studies of vesicle composition and cannot be employed for the ultrastructural confirmation of a histologic diagnosis of chromophobe cell carcinoma since the intracellular vesicles are no longer present.

Adenocarcinoma↗
PubMedDate not supplied

Diffuse intimal fibromuscular dysplasia with multiorgan failure.

A woman presented with a rapid onset of hypertension, angina pectoris, peripheral vascular disease, renal involvement, and a large liver cyst. Surgical removal of the liver cyst precipitated renal and liver failure and a terminal arrhythmia. At autopsy, there was intimal fibromuscular dysplasia involving the arteries to the heart, liver, kidneys, and intestines and evidence of recent infarction of the intestines, kidney, and liver. This case illustrates that intimal fibromuscular dysplasia (FMD) can be a diffuse and rapidly progressive disease. Some treatments currently being evaluated for preventing restenosis following angioplasty may find use in treating this uncommon disease.

Diagnosis, Differential↗