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H Preiser

Publications and source records attributed to H Preiser.

At least 19 recordsLinked to original sources
PubMed1985

Radiation inactivation studies on the rabbit kidney sodium-dependent glucose transporter.

Rabbit kidney cortical brush-border membrane vesicles were irradiated in the frozen state with increasing doses of high energy electrons from a Van de Graaff generator. Sodium-dependent D-glucose and L-alanine transport showed a simple exponential loss of activity with increasing radiation dosage. Target size calculation based on these data gives estimates of 1.0 X 10(6) daltons for the glucose transporter and 1.2 X 10(6) daltons for the alanine transporter. A highly purified glucose transport protein extracted from rabbit kidney cortex was similarly irradiated both before and after reconstitution into liposomes. The target size of this purified glucose transporter was 343,000 daltons, based on inactivation of transport. The intensity of the major 165,000-dalton sodium dodecyl sulfate-gel electrophoresis band of this preparation was decreased by radiation. The decrease in staining intensity was dose-dependent, yielding a target size of 298,000 daltons, in situ. We propose that the purified glucose transporter reconstituted into liposomes is a tetramer comprised of 85,000-dalton subunits.

Alanine↗
PubMed1983

Isolation of the sodium-dependent d-glucose transport protein from brush-border membranes.

Rabbit kidney brush-border membrane vesicles were exposed to bacterial protease which cleaves off a large number of externally oriented proteins. Na+-dependent D-glucose transport is left intact in the protease-treated vesicles. The protease-treated membrane was solubilized with deoxycholate and the deoxycholate-extracted proteins were further resolved by passage through Con A-Sepharose columns. Sodium-dependent D-glucose activity was found to reside in a fraction containing a single protein band of Mr approximately equal to 165 000 which is apparently a dimer of Mr approximately or equal to 85 000. When reconstituted and tested for transport, this protein showed Na+-dependent, stereo-specific and phlorizin-inhibitable glucose transport. Transport activity is completely recovered and is 20-fold increased in specific activity. A similar isolate was obtained from rabbit small intestinal brush-border membranes and kidneys from several other species of animals.

Animals↗
PubMed1981

Alcaptonuria and sucrase-isomaltase deficiency in three offspring of a consanguineous marriage.

Intestinal brush border membrane hydrolases and HLA lymphocyte antigens have been examined in three siblings with sucrose intolerance and alcaptonuria, and their consanguineous parents. Sucrase-isomaltase activity was absent in the three patients, and corresponded with the gel electrophoresis of SDS-solubilized brush border membranes, which failed to demonstrate the protein band normally associated with sucrase-isomaltase complex. The activities of all brush border membrane enzymes in the mother were normal, while those of the father were generally low. The use of hydrolytic capacity ratios, however, permitted the designation of both parents as heterozygotes. Significant homogentisic aciduria was found only in the three propositi, and no effect of homogentisic acid on the sucrase activities of two normal, unrelated children could be demonstrated in vitro. The HLA lymphocyte antigen profiles of all seven family members demonstrated remarkable histocompatibility in five of them.

Adolescent↗
PubMed1979

A rapid method for the isolation of kidney brush border membranes.

A simple rapid method for the preparation of purified brush border membranes from rabbit kidney proximal tubules is described. The method is based on hypotonic lysis, Ca2+ aggregation of contaminants and differential centrifugation. In contrast to most other published methods, the brush border membranes are free of contamination by basolateral membranes.

Alanine↗
PubMed1979

Reconstitution into liposomes of glucose active transport from the rabbit renal proximal tubule. Characteristics of the system.

This paper describes the characteristics of Na+ -dependent D-glucose transport into liposomes made from soybean phospholipids into which have been reconstituted detergent-solubilized components from the rabbit renal proximal tubular brush border membrane. Conditions for optimal and quantitative reconstitution of glucose carriers are defined. Na+ -dependent D-glucose uptake occurs via a saturable system with a Km of 0.125--0.135 mM, is responsive to the volume of the internal liposomal space, and shows 'overshoot' as seen in natural membranes. The rate of Na+-dependent D-glucose uptake and the magnitude of the 'overshoot" are proportional to the concentration of protein used in reconstitution.

Animals↗
PubMed1975

Enzymes of the human intestinal brush border membrane. Identification after gel electrophoretic separation.

The postition of a number of human intestine brush border membrane enzyme activities in polyacrylamide gels after electrophoresis has been determined. These activities are, in order from the origin, maltase/glucoamylase, lactase/phlorizin hydrolase, maltase/sucrase/isomaltase, enteropeptidase, trehalase and gamma-glutamyl-transferase. Leucylnaphthylamide hydrolyzing activity was inactivated by sodium dodecylsulfate and its position was not determined. The positions of the activities have been correlated with the positions of protein bands previously determined. One such band situated between enteropeptidase and alkaline phosphatase has not been identified.

Alkaline Phosphatase↗
PubMed1975

Modification of an assay for trypsin and its application for the estimation of enteropeptidase.

A sensitive method for the estimation of trypsin and enteropeptidase is described. The use of alpha-N-benzoyl-DL-arginine-p-nitroanilide as substrate in combination with the Bratton-Marshall reaction increased the sensitivity of an established method to a degree which permits the determination of enteropeptidase at considerably lower activity levels than heretofore such as those expected in brush border membrane preparations from peroral biopsies of human small intestine.

Anilides↗
PubMed1972

Action potential parameters affecting excitation-contraction coupling.

In quantifying type B potentiation effects, given earlier merely qualitatively, it is found that Zn(2+), 1-50 microM, causes increases in action potential duration, twitch tension, and twitch contraction period time, which are all directly proportional to the log of the concentration. Hence, the duration of the action potential, i.e. the magnitude of its mechanically effective period, is a causal factor quantitatively determining the degree of mechanical activation in the isometric twitch. In higher concentrations of Zn(2+) up to 1000 microM, the spike duration and the contraction time continue to increase but the twitch tension is disproportionately smaller, evidently because the high zinc (500-1000 microM) raises the mechanical threshold of excitation-contraction (E-C) coupling and reduces the intrinsic strength of the contractile system. Eserine (1.5 mM) and also high Zn(2+) not only cause type B potentiation effects, but also slow the rise of the spike, thus causing retardation of the very onset of tension production, which is even greater for high Zn(2+) because of the raised mechanical threshold. This retardation is then succeeded by the faster tension output characteristic of type B potentiation resulting from spike prolongation. Thus, the changes in the consecutive, rising and falling phases of the action potential explicitly register their separate effects in the respective very earliest and directly following periods of twitch output; i.e., each phase of the action potential produces its own mechanical "transform." These transforms, and other effects, suggest that the release of activator Ca(2+) from the sarcoplasmic reticulum during E-C coupling can be graded in both the rate and the total amount of the release.

Action Potentials↗