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Biomedical subjects

C A Baker

Publications and source records attributed to C A Baker.

At least 55 records · Page 3Linked to original sources
PubMed1985

Stimulation of cyclic GMP formation in smooth muscle cells by atriopeptin II.

Addition of synthesized atriopeptin II (AP-2), a 23 amino acid peptide of rat atria, to rat thoracic aorta smooth muscle cells results in the stimulation of cyclic GMP production by the cells. The EC50 for the effect is 81 nM and a 7 fold increase occurs at 10 microM AP-2. Cyclic GMP levels increased within 15 seconds after the addition of AP-2 and were maximal at 5 minutes. Cyclic GMP levels in primary rabbit kidney cells were increased 15 fold by 10 microM AP-2. However, no increase in cyclic GMP was detected in WI-38 fibroblast cells after the addition of 10 microM AP-2. Cyclic AMP levels were not affected by AP-2 in any of these cell systems. The effect upon cyclic GMP accumulation was specific for AP-2; none of the other compounds or peptides tested affected cyclic GMP levels.

Animals↗
PubMed1984

COLLEAGUE: a comprehensive online medical library for the end user.

COLLEAGUE, from BRS/Saunders, is an online information service intended for use by health professionals. This article describes both the databases and services available through COLLEAGUE and shows specific search examples. Special COLLEAGUE features are highlighted as well as the differences between COLLEAGUE and both BRS/AFTER DARK and the BRS Search System. In addition, the role of the librarian in end user searching and future directions for COLLEAGUE are discussed.

Canada↗
PubMed1983

Cardiac-slowing amidines containing the 3-thioindone group. Potential antianginal agents.

A series of 3-thioindolamidines (and 3-indolamidines) related to mixidine (1) was studied for cardiac-slowing properties, following the discovery of activity for prototype thioindole 2. Structure-activity relationships were explored, leading to many potent antitachycardiac agents (6-9, 12, 13, 15-17, 20, 23, 24, 30, 34, 35, 45, and 47-49). Relative to 2, cardiac-slowing activity is enhanced by substitution of the indole nitrogen with small (C1-C3) saturated alkyl groups (6-9), unsaturated alkyl groups (12, 13, and 15-17), or a methoxyethyl group (20); replacement of the N-methyl group with alkyl (23) or phenyl groups (24); and extension of the ethylene bridge by two methylene units (34). Dethio (i.e., 3-indole) analogues of 2 with alkyl substitution on the indole nitrogen (47-49) have greater activity as well. Several potent compounds were also found to have minimal myocardial depression (6-9, 13, 45, and 47). Secondary pharmacological testing is reported for thioindoles 2, 6, 7, 9, and 28.

Amidines↗
PubMed1983

Predominant bacteria in an activated sludge reactor for the degradation of cutting fluids.

For the first time, an activated sludge reactor, established for the degradation of cutting fluids, was examined for predominant bacteria. In addition, both total and viable numbers of bacteria in the reactor were determined so that the percentage of each predominant type in the total reactor population could be determined. Three samples were studied, and a total of 15 genera were detected. In each sample, the genus Pseudomonas and the genus Microcyclus were present in high numbers. Three other genera, Acinetobacter, Alcaligenes, and Corynebacterium, were also found in every sample but in lower numbers. In one sample, numerous appendaged bacteria were present, and one of these, the genus Seliberia, was the most predominant organism in that sample. However, in the other two samples no appendaged bacteria were detected. Six genera were found in this reactor which have not been previously reported in either cutting fluids in use or in other activated sludge systems. These genera were Aeromonas, Hyphomonas, Listeria, Microcyclus, Moraxella, and Spirosoma. None of the predominant bacteria belonged to groups of strict pathogens.

Journal Article↗
PubMed1982

Dependence of salivary drug concentration on salivary flow rate.

Saliva drug concentrations are a function of the saliva flow rate at which they are collected. Increased saliva flow rate tends to restore the salivary concentration towards the free unbound plasma concentration of drug. For those drugs excluded from the saliva relative to their free plasma concentration, stimulation increases the observed drug levels in the saliva. For those drugs concentrated in the saliva relative to their free plasma concentration, stimulation decreases the observed drug levels in the saliva.

Amitriptyline↗
PubMed1979

Amniocentesis and antenatal sex determination in the rhesus monkey (Macaca mulatta).

Antenatal sex was correctly identified in 87.5% of the rhesus monkeys studied by evaluation of sex chromatin bodies in the exfoliated cells present in amniotic fluid. Fluid samples were obtained by either amniocentesis, amnioscopy, or by cesarean section at 80--120 days of gestation. Amniotic fluid concentrations of progesterone, total estrogen, and testosterone were correlated with fetal sex. Concentrations of these hormones decreased over the time period examined. Amniocentesis is a simple procedure which provides for routine fetal sex determination.

Amniocentesis↗
PubMed1977

The number of umbilical vessels in the squirrel monkey (Saimiri sciureus).

The number of vessels present in the umbilical cords of 40 nonsurviving squirrel monkey fetuses an neonates has been determined by gross and histologic examination. Four umbilical vessels were present in 72.5% of the cords and 27.5% contained three vessels. Coincident fetal malformations are noted.

Animals↗
PubMed1977

Spontaneous malformations in squirrel monkey [Saimiri sciureus] fetuses with emphasis on cleft lip and palate.

Gross examination of a group of surviving and nonsurviving squirrel monkeys has revealed a high incidence of cleft lip and cleft primary palate defects with an associated anophthalmia. These defects, as well as single incidences of diaphragmatic aplasia, scoliosis, internal hydrocephalus, and funnel chest, are noted or described and discussed with reference to sex and parentage.

Animals↗
PubMed1976

Antenal sex determination using amniotic fluid of the baboon (Papio sp.).

Antenatal determination of sex in the baboon was performed by evaluating the percentage of sex chromatin bodies present in the epithelial cells of amniotic fluid obtained during or immediately following cesarean section. Female sex chromatin patterns revealed a mean of 39.2% positive sex chromatin; the mean in males was less than 5%. This procedure is accurate and simple to perform.

Amniotic Fluid↗
PubMed1975

Intracytoplasmic membrane formation and increased oxidation of glycerol growth of Gluconobacter oxydans.

Gluconobacter oxydans is well known for the limited oxidation of compounds and rapid excretion of industrially important oxidation products. The dehydrogenases responsible for these oxidations are reportedly bound to the cell's plasma membrane. This report demonstrates that fully viable G. oxydans differentiates at the end of exponential growth by forming dense regions at the end of each cell observed with the light microscope. When these cells were thin sectioned, their polar regions contained accumulations of intracytoplasmic membranes and ribosomes not found in undifferentiated exponentially growing cells. Both freeze-fracture-etched whole cells and thin sections through broken-cell envelopes of differentiated cells demonstrate that intracytoplasmic membranes occur as a polar accumulation of vesicles that are attached to the plasma membrane. When cells were tested for the activity of the plasma membrane-associated glycerol dehydrogenase, those containing intracytoplasmic membranes were 100% more active than cells lacking these membranes. These results suggest that intracytoplasmic membranes are formed by continued plasma membrane synthesis at the end of active cell division.

Cell Membrane↗
PubMed1975

Regulation of the ammonia assimilatory enzymes in Salmonella typhimurium.

The regulation of glutamate dehydrogenase (EC 1.4.1.4), glutamine synthetase (EC 6.3.1.2), and glutamate synthase (EC 2.6.1.53) was examined for cultures of Salmonella typhimurium grown with various nitrogen and amino acid sources. In contrast to the regulatory pattern observed in Klebsiella aerogenes, the glutamate dehydrogenase levels of S. typhimurium do not decrease when glutamine synthetase is derepressed during growth with limiting ammonia. Thus, it appears that the S. typhimurium glutamine synthetase does not regulate the synthesis of glutamate dehydrogenase as reported for K. aerogenes. The glutamate dehydrogenase activity does increase, however, during growth of a glutamate auxotroph with glutamate as a limiting amino acid source. The regulation of glutamate synthase levels is complex with the enzyme activity decreasing during growth with glutamate as a nitrogen source, and during growth of auxotrophs with either glutamine or glutamate as limiting amino acids.

Ammonia↗
PubMed1974

Regulation of serine transhydroxymethylase activity in Salmonella typhimurium.

The regulation of serine transhydroxymethylase (EC 2.1.2.1.; l-serine:tetrahydrofolic-5,10-hydroxymethyltransferase) has been investigated in Salmonella typhimurium LT2. Our results indicate that limitation of a methionine auxotroph for methionine does not cause derepression of this enzyme as reported for Escherichia coli. However, a sixfold decrease in specific activity was observed when S. typhimurium cells were grown in glucose minimal medium supplemented with serine, glycine, methionine, adenine, guanine, and thymine. None of these compounds added to the growth medium individually produced more than a 42% reduction of wild-type enzyme activity. This enhanced repression by the combination of compounds suggests a form of cumulative repression of this enzyme. Growth of serine and thymine auxotrophs, with the respective requirement of each limiting, did not result in increased enzyme activity. However, growth of a purine auxotroph with a limiting amount of either guanine or inosine resulted in a five- to sevenfold increase in enzyme activity. A second condition causing significant derepression (fourfold increase) above the levels observed with cells grown in minimal medium was the addition of 0.5 mug of trimethoprim per ml, an inhibitor of the dihydrofolate reductase activity. (A partial report on this work was presented at 1974 meeting of the American Society for Microbiology.)

Adenine↗