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Biomedical subjects

K S Roth

Publications and source records attributed to K S Roth.

64 records · Page 4Linked to original sources
PubMed1978

Developmental aspects of maleic acid-induced inhibition of sugar and amino acid transport in the rat renal tubule.

The transport of alpha-aminoisobutyric acid and alpha-methyl-d-glucoside by isolated tubules from Sprague-Dawley rats at different stages of development follows a separate age-dependent pattern for each substrate. The effects of 6 M maleic acid on transport processes differ for amino acids and sugars and become manifest at distinct points during development. Maximum inhibition by maleic acid occurs at a time subsequent to maturity of these transport systems. In an effort to explain these transport phenomena, the uptake and metabolism of 14C-labeled maleic acid by the newborn or adult renal tubule was studied, showing significant binding by the tubule membrane, penetration of the cell by diffusion, and no conversion to 14CO2. Maleic acid has no demonstrable effect on the membrane-associated enzymes which are thought to play a role in the transport of small molecules.

Age Factors↗
PubMed1978

The ontogeny of sugar transport in kidney.

Concentrative uptake of alpha-methyl-d-glucoside (AMG) by isolated renal tubule fragments from the newborn Sprague-Dawley rat has been demonstrated and the validity of this phenomenon confirmed by an in vivo demonstration of AMG uptake by the newborn kidney cortex. A kinetic analysis of the entry phenomenon in the newborn tubule reveals the presence of two distinct membrame transport systems for AMG, only one of which is present in the adult tubule. All transport of sugar in both newborn and adult tubules was phlorizin-sensitive, but was only partially ingibited in Na+-free buffer. Glucose was shown to inhibit uptake competitively on the shared, high capacity system. Uptake on the high affinity system in the newborn represents 15-20% of the total at physiologic sugar concentrations. It is concluded that active sugar transport is a characteristic of the newborn rat kidney and that the isolated tubule preparation is a more accurate reflection of this phenomenon than is the renal cortical slice.

Age Factors↗
PubMed1977

Ontogeny of glycine transport in isolated rat renal tubules.

Isolated renal tubule preparations were made from newborn Sprague-Dawley rats and used to study initial entry rate kinetics of glycine. The results were compared to those obtained in the isolated tubule preparation from the adult rat kidney. While initial rates of glycine uptake were identical for newborn and adult tubules, significant differences in influx kinetics were demonstrated. Of the two apparent transport Km systems shown to be present in the newborn tubule, the high-affinity, low-capacity system accounts for about 40% of total glycine uptake at physiologic concentrations. The high-affinity, low-capacity system of the adult tissue accounts for about 10% of total uptake at the same concentration range. The data lend strength to the argument against the concept that the physiologic hyperglycinuria of the newborn rat is due to either impaired ability to concentrate glycine intracellularly or to absence of one or more transport mechanisms for glycine.

Animals↗
PubMed1976

Effect of maleic acid on the kinetics of alpha-methyl-D-glucoside uptake by isolated rat renal tubules.

ALPHA-Methyl-D-glucoside has been used to study the invitro mechanism of the effect of maleic acid on sugar transport, using isolated rat renal tubule fragments. 6 mM maleate maximally inhibits the ability of the tubule to establish a concentration gradient for this model sugar with no evidence of ultrastructural changes. This inhibition is due to a 100% increase in efflux, as well as to a 50% decrease in influx with more prolonged incubation. The data presented here are consistent with those of other workers, but their work does not explain our results, which therefore deserve further investigation by other techniques.

Animals↗
PubMedDate not supplied

Asymptomatic gross hematuria followed by persistent microhematuria.

A case of a previously healthy, 13-year-old male with IgA nephropathy is presented in order to illustrate clinical onset and differential diagnosis of this rather common clinical entity. The laboratory and histopathological diagnosis is illustrated and discussed, as well, together with a brief discussion of possible pathogenesis. In this disorder, in which approximately 11% of affected patients experience spontaneous remission, future development of molecular probes to determine prognosis is of great importance.

Adolescent↗
PubMedDate not supplied

Urinary tract infections in children.

This article will review the clinical and laboratory characteristics of urinary tract infection in children. The diagnostic workup, the current recommended treatment and the long-term prognosis will also be reviewed.

Child↗