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Biomedical subjects

S K Shapiro

Publications and source records attributed to S K Shapiro.

At least 19 recordsLinked to original sources
PubMed1983

Unilateral papilledema in 'benign' intracranial hypertension (pseudotumor cerebri).

Three patients with benign intracranial hypertension ([BIH], or pseudotumor cerebri) had verified increased CSF pressure and unilateral papilledema. One patient had slowly progressive loss of visual acuity until unilateral optic nerve sheathotomy was performed. One patient had spontaneous venous pulsation in the unaffected eye. The diagnosis of BIH must be considered even in the absence of bilateral papilledema.

Adolescent↗
PubMed1980

Conversion of 5'-methylthioadenosine into S-adenosylmethionine by yeast cells.

5'-Methylthio[U-14C]adenosine was used as a culture supplement for Candida utilis. The resulting S-adenosylmethionine was hydrolyzed into its structural components. Virtually none of the label of the pentose was found in the carbohydrate part of the intracellular S-adenosylmethionine. Much of it was present in the four-carbon chain of the methionine part of the sulfonium compound. The (U-14C)-labeled adenine of 5'-methylthio[U-14C]adenosine did not contribute to the labeling of the amino acid components of the sulfonium compound.

Adenosine↗
PubMed1980

Familial pseudotumor cerebri and the empty sella syndrome.

The empty sella syndrome may be a later complication of pseudotumor cerebri, based on the relationships of clinical features of both and their visual complication. Pseudotumor cerebri may follow a genetic predisposition but further research is needed to confirm this.

Adult↗
PubMed1978

5-Methylthioribose kinase. A new enzyme involved in the formation of methionine from 5-methylthioribose.

The presence of a previously unidentified enzyme, tentatively designated 5-methylthioribose kinase, has been demonstrated in cell-free extracts of Enterobacter aerogenes. The enzyme catalyzes the ATP-dependent phosphorylation of 5-methylthioribose. ADP is one of the products of the reaction and, based on functional group analyses, the other product is 5-methylthioribose 1-phosphate. A 40-fold purified enzyme preparation has been obtained from a cell-free extract of E. aerogenes. Activity of the partially purified enzyme is totally dependent on the presence of a divalent cation and a sulfhydryl reagent. The substrate specificity of the enzyme is quite narrow, and the Km values for ATP and 5-methylthioribose are 7.4 X 10(-5) M and 8.1 X 10(-6) M, respectively. These results suggest that 5-methylthioribose kinase may be a primary enzyme involved in the recycling of the methylthio group of 5-methylthioribose back into methionine.

Cations, Divalent↗
PubMed1977

Function of S-adenosylmethionine in germinating yeast ascospores.

Germination and outgrowth of ascospores of Saccharomyces cerevisiae 4579 require both methionine and adenine, whereas leucine is only required for outgrowth. The methionine requirement may be satisfied by S-adenosylmethionine, but this sulfonium compound will not substitute for adenine. Between 30 and 70 min of protein synthesis is initially required for the completion of germination in strain 4579. The inhibition of S-adenosylmethionine synthetase by trifluoromethionine prevents both germination and protein synthesis. During the initial stages of germination, the S-adenosylmethionine synthetase, S-adenosylmethionine decarboxylase, and transfer ribonucleic acid methyltransferases increased significantly, indicating that polyamines and/or the methylation of transfer ribonucleic acid are required for the initiation of germination.

Adenine↗