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B Blazer-Yost

Publications and source records attributed to B Blazer-Yost.

9 recordsLinked to original sources
PubMed1991

Relationship of the aldosterone-induced protein, GP70, to the conductive Na+ channel.

Although one of the primary effects of aldosterone is to increase apical membrane Na+ conductance, as yet none of the proteins induced by the hormone in renal epithelia have been shown to be related to the conductive Na+ channel. Because the toad urinary bladder aldosterone-induced glycoprotein, GP70, has recently been localized to the apical surface of this Na+ transporting epithelium, whether GP70 is associated with the Na+ channel was examined. The specificities of a monoclonal antibody used to characterize GP70 (mAb 20) and a polyclonal antibody raised against the purified bovine renal papillary Na+ channel (anti-CH) were compared: GP70 was specifically immunoprecipitated by both mAb 20 and anti-CH. Moreover, the sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile of mAb 20 purified toad urinary bladder membrane preparations was similar to those reported for bovine and A6 cell Na+ channels. Under nonreducing conditions, a single, very large protein was evident; reduction yielded GP70, a 140-kd polypeptide, and a number of minor bands. Interestingly, only GP70 was induced by aldosterone. Thus, GP70 appears to be associated with the toad urinary bladder conductive Na+ channel; whether GP70 is an integral subunit of the channel or whether it functions as a regulatory moiety remains to be determined. Whatever the case, because GP70 is induced by aldosterone, it likely has a central role in Na+ channel modulation.

Aldosterone↗
PubMed1985

Aldosterone-induced proteins: characterization using lectin-affinity chromatography.

Aldosterone-stimulated Na+ transport in toad urinary bladder is associated with the synthesis of a specific group of proteins whose induction appears to be related to the natriferic effect of the hormone. These aldosterone-induced proteins (AIPs) occur in two slightly different molecular weight classes (around 70 kDa), each class being composed of several proteins with discrete isoelectric points (range, 5.5-6.0). Because glycosylation is a common cause of such electrophoretic polymorphism and microheterogeneity, we examined whether these proteins are glycoproteins. Tunicamycin (a specific inhibitor of N-linked glycosylation) inhibited aldosterone-stimulated Na+ transport and AIP synthesis without affecting overall protein synthesis. The vast majority of epithelial cell proteins did not bind to the mannose-specific lectin, concanavalin A-sepharose. In contrast, both classes of AIPs bound to concanavalin A-sepharose, but the affinities of the higher and lower molecular weight proteins were markedly different: the former were readily eluted with 0.2 M alpha-methyl-D-mannoside alone, whereas the latter could only be eluted with 0.4 M alpha-methyl-D-mannoside in combination with high concentrations of NaCl (2.5-5.0 M). These studies indicate that 1) glycosylation is important in the natriferic response to aldosterone, 2) the AIPs are N-linked mannose-containing glycoproteins, and 3) the electrophoretic polymorphism of the AIPs is due, at least in part, to differences in glycosylation. Furthermore, concanavalin A-affinity chromatography provides a simple means for the partial purification of these putative "effectors" of the cellular action of aldosterone.

Aldosterone↗
PubMed1982

Aldosterone-induced proteins in renal epithelia.

Similar aldosterone-induced proteins have been demonstrated in two renal epithelia, the urinary bladder of the toad, Bufo marinus, and epithelia formed by cells of the A6 line derived from the kidney of the toad, Xenopus laevis. The proteins are induced along with the stimulation of Na+ transport but their synthesis is not dependent on Na+ transport per se. In view of the similar characteristics of the aldosterone-induced proteins in these two different epithelia, we suggest that they may have an important role in aldosterone-induced Na+ transport.

Aldosterone↗
PubMed1979

Characterization of renal defects in dogs with a syndrome similar to the Fanconi syndrome in man.

Ten adult dogs with multiple spontaneous defects of renal tubular reabsorption were studied. Clinical signs included polydipsia, polyuria, and glycosuria for 2 to 12 months. Eight of the dogs were Basenjis. Urinalyses revealed hyposthenuria, glycosuria, and amino aciduria in most dogs. Renal function was normal in 5 dogs and slightly reduced in the remainder. Moderate metabolic acidosis had developed in 3 dogs. Renal clearance studies revealed reduced tubular reabsorption of glucose, phosphate, sodium, potassium, and uric acid. Abnormal glucose tubular maximal curves were found. Results of oral glucose tolerance tests were normal. Two patterns of abnormal amino aciduria were evident: generalized amino aciduria and a pattern similar to that of cystinuria in dogs. Radiography of long bones and bone densitometry did not reveal any skeletal abnormalities. Five of the dogs died within 90 days of diagnosis; death was due to acute renal failure associated with profound dehydration, acidosis, and papillary necrosis. The other dogs remained stable without treatment after 18 months. Histopathology of kidneys did not reveal uniform abnormalities; some dogs had variable and nonspecific changes and others were normal. Electron microscopy did not reveal ultrastructural abnormalities in renal tubular cells. It was concluded that the syndrome in these dogs represents a new entity of renal disease in dogs, similar to idiopathic Fanconi syndrome in man.

Animals↗
PubMed1979

Late-onset nonketotic hyperglycinemia and spinocerebellar degeneration.

Investigation of a 15-year old boy with progressive optic atrophy and spinocerebellar degeneration revealed elevated plasma, cerebrospinal fluid, and urine glycine concentrations. During an oral glycine loading test, the patient's plasma glycine concentration rose to a higher level than control values, although the initial rate of rise was slower; there was no concomitant rise in the plasma serine concentration. An oral serine loading test resulted in a prompt rise of both glycine and serine serum concentrations. The renal glycine clearance was elevated, and the renal tubular glycine reabsorption was diminished. These findings of decreased intestinal uptake and increased renal tubular glycine clearance suggest that a generalized derangement of glycine entry into cells may account for the phenotypic manifestations of the disorder.

Adolescent↗
PubMed1979

On the clinical significance of the plasma alpha-amino-n-butyric acid:leucine ratio.

The ratio of plasma alpha-aminobutyric acid to plasma leucine that has been proposed as a specific biochemical marker of alcoholic liver injury, was measured in normal children an children with a variety of metablic disorders. The ratio was found to be lower in children that in adults. It was elevated in children with Reye's syndrome, tyrosinemia, homocystinuria, nonketotic hyperglycinemia, and ornithine transcarbamylase deficiency. The results indicate that an elevated ratio is not specific for adults with alcoholic liver injury and that the ratio may be high even without the presence of clinically apparent hepatic disease. An altered ratio may reflect the presence of an inherent metabolic defect.

Adult↗
PubMed1979

Amino acid content of rat renal cortex and the response to in vitro incubation.

The concentration of aspartic acid, threonine, serine, glycine, and alanine is significantly higher in newborn rat renal cortex than in the adult tissue, while phenylalanine and histidine are higher in the adult. When adult cortical slices are placed in bicarbonate buffer at room temperature for 20 min there is a 30-60% decrease in the levels of all amino acids except for lysine, which is slightly higher, and methionine and serine, which do not change. Under the same conditions, newborn cortical slices reveal a similar decrease in only glycine, tyrosine, histidine, and the branched-chain amino acids. On subsequent in vitro incubation of the cortical slices at 37 degrees C for 120 min the concentrations in adult tissue remain at the lower values observed on removal from buffer at room temperature except that glutamic acid, glycine, and lysine levels decrease further and serine increases to the concentration found in fresh tissue. Newborn tissue when incubated at 37 degrees C for 120 min shows amino acid concentrations comparable to unincubated fresh tissue for all except aspartic acid, glutamic acid, serine, and phenylalanine, which reach levels higher than unincubated tissue. The ability of newborn tissue to maintain amino acid pools may play a role in the enhanced transport of some amino acids resulting from preincubation at 37 degrees C (Reynolds et al. Science 184: 68-69, 1974; Reynolds and Segal, Biochim. Biophys. Acta 406: 513-525, 1976).

Aging↗
PubMed1979

Free amino acids in the plasma and urine of dogs from birth to senescence.

Plasma and urinary amino acid concentrations were determined from a cross-sectional sample of dogs of all ages. Reference or base line values for these components were established for five different age groups. A general decrease in urinary excretion of amino acids for each gram of creatinine was found during the developmental period. This decrease was not correlated to changes in plasma concentrations, which varied for the individual amino acids. The decrease did appear to be related to the functional maturation of the kidney. Several methylated basic amino acids were identified in the urine. Of these, NG, NG- and NG,N'G-dimethylarginine, and trimethyllysine had not been previously reported as constituents of dig urine, but are major components of the urinary amino acids, expecially in newborn animals. The 3-methylhistidine is also excreted in large amounts by dogs and measurable quantities of this compound appear in the plasma. These findings suggest an active metabolic function for methylated amino acids in the dog.

Aging↗