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At least 1,711 records · Page 95Linked to original sources
PubMed1995

Vesicular monoamine uptake by digitonin-permeabilized PC12 cells: inhibitory effect of neuromodulators and drugs on the amine transport.

Vesicular amine transport is crucial for activity of monoaminergic neurons since translocation of cytosolic amine to storage vesicles is required for both exocytotic release and reuptake of the neurotransmitter. We developed a convenient assay system for vesicular amine transport based on permeabilizing the plasma membrane of pheochromocytoma PC12 cells with digitonin at concentrations of 100 to 150 microM. Serotonin (5HT) is a better substrate than either epinephrine or norepinephrine in this assay system. In the presence of 2 mM ATP, 5HT uptake by the permeabilized cells increased linearly for at least 30 min at 25 degrees C, whereas without addition of exogenous ATP, 5HT uptake reached an apparent plateau after 20 min incubation. Reserpine (500 nM) completely blocked the ATP-dependent 5HT uptake in this system whereas nomifensine (10 microM) had no effect, indicating specificity for vesicular transport. Treatment of intact PC12 cells with AMP dose-dependently decreased 5HT uptake with an EC50 of 20-30 microM as measured after cell permeabilization. Treatment of the intact PC12 cells with forskolin and phorbol 12-myristate 13-acetate prior to permeabilization also down-regulated vesicular 5HT transport, whereas the addition of either of these agents into the reaction mixture for the amine uptake by already permeabilized cells did not alter the vesicular uptake activity. Thus, the system can be applied to studies on regulation of the vesicular amine transport by physiological signaling molecules, intracellular messengers, and drugs.

Adenosine Monophosphate↗
PubMed1999

In vitro scanning saturation mutagenesis of all the specificity determining residues in an antibody binding site.

For the first time, each specificity determining residue (SDR) in the binding site of an antibody has been replaced with every other possible single amino acid substitution, and the resulting mutants analyzed for binding affinity and specificity. The studies were conducted on a variant of the 26-10 antidigoxin single chain Fv (scFv) using in vitro scanning saturation mutagenesis, a new process that allows the high throughput production and characterization of antibody mutants [Burks,E.A., Chen,G., Georgiou,G. and Iverson,B.L. (1997) Proc. Natl Acad. Sci. USA, 94, 412-417]. Single amino acid mutants of 26-10 scFv were identified that modulated specificity in dramatic fashion. The overall plasticity of the antibody binding site with respect to amino acid replacement was also evaluated, revealing that 86% of all mutants retained measurable binding activity. Finally, by analyzing the physical properties of amino acid substitutions with respect to their effect on hapten binding, conclusions were drawn regarding the functional role played by the wild-type residue at each SDR position. The reported results highlight the value of in vitro scanning saturation mutagenesis for engineering antibody binding specificity, for evaluating the plasticity of proteins, and for comprehensive structure-function studies and analysis.

Amino Acids↗
PubMed1973

Drugs and pregnancy.

Explore the source record for details and available documents.

Abnormalities, Drug-Induced↗
PubMed1985

Management of gallbladder perforation by percutaneous cholecystostomy.

Percutaneous cholecystostomy was employed successfully as an alternative to cholecystectomy for the treatment of acute cholecystitis with perforation in an elderly woman. The procedure, performed portably in the cardiac care unit, was selected because progressive cardiac and renal decompensation made the patient an extremely poor surgical risk.

Aged↗
PubMed1991

The positive inotropic drugs DPI 201-106, BDF 9148, and veratridine increase ouabain toxicity and [3H]ouabain binding in guinea pig heart.

The interaction of three positive inotropic compounds, which are modulators of sodium channels, with the cardiac glycoside ouabain was investigated in isolated guinea pig atria. In the presence of DPI 201-106 (3 x 10(-7) M), of its new acetidine derivative BDF 9148 (10(-7) M), or of veratridine (10(-6) M), the threshold ouabain concentration to induce toxicity was lowered by a factor of 2. This effect can be explained by the observation that specific equilibrium [3H]ouabain binding in intact atria was elevated by these compounds in the appropriate concentrations. The binding results were analyzed by means of a previously established model of "positive cooperative ouabain binding to intact myocardium," which describes the relationship between cellular sodium homeostasis and ouabain binding. The extent to which the compounds increased ouabain binding was in good quantitative agreement with the observed shift in the threshold concentration of ouabain toxicity. The increase of specific [3H]ouabain binding is likely initiated by a gain in cytosolic sodium. It takes place at the cellular level only, since a direct enhancement of [3H]ouabain binding to isolated cardiac membranes was not found. In conclusion, at least under some conditions, new inotropic drugs acting as sodium channel modulators can increase the risk of digitalis toxicity.

Animals↗
PubMedDate not supplied

Differential effects of heart rate modification training on college students, older males, and patients with ischemic heart disease.

Seventy male subjects participated in a six session study of feedback-mediated heart rate modification. Three groups of subjects were compared: (1) college students, (2) patients with ischemic heart disease, and (3) healthy males, age-matched to the patients. The groups did not differ in heart rate during rest or in response to a perceptual-motor tracking task. However, the college students produced significantly larger changes in cardiac rate than the other two groups when instructed to modify heart rate (speed or slow) and provided with exteroceptive feedback. The patients showed the poorest overall feedback performance. These differences between groups were greater for speeding than for the slowing task. Relationships were explored between feedback performance and resting heart and respiration rate, drug regime, and personality questionnaires. The results were consistent with the hypothesis that interdependence between psychological stimuli and cardiovascular events is reduced in heart disease.

Adult↗