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Biomedical subjects

J B Armstrong

Publications and source records attributed to J B Armstrong.

At least 55 records · Page 3Linked to original sources
PubMed1977

Brain isoenzyme of creatine kinase. I. Purification of rabbit enzyme and production of specific antibodies.

Creatine kinase (EC 2.7.3.2) of rabbit brain (BB) was purified to hemogeneity as judged by sedimentation velocity analysis in the ultracentrifuge. Nevertheless, the purified enzyme contained as many as seven extraneous protein species when examined by disc electrophoresis in polyacrylamide gel. The purified preparation also showed antigenic heterogeneity when it reacted in agar gel double immunodiffusion analysis with antibodies produced against it in the rooster. At least some of the extraneous proteins appeared to arise from BB during storage. Subsequently BB was purified to hemogeneity by disc electrophoresis in polyacrylamide gel. It was excised from the gel and injected repeatedly with Freund's complete adjuvant into roosters. A single immunoprecipitin line was noted in agar gel double immunodiffusion analysis when partially pure enzyme reacted with the antibodies raised to the electrophoretically pure protein. These antibodies inhibited the enzymatic activity of BB in both soluble and insoluble immune complexes. They did not, however, form immunoprecipitates with or inhibit rabbit muscle (MM) or rabbit hybrid (MB) creatine kinases. The antibodies were therefore specific for BB and did not react with MM or MB.

Animals↗
PubMed1977

Brain isoenzyme of creatine kinase. II. Species specificity of enzyme and presence of inactive form in striated muscle of rabbit and man.

Antibodies specific for the brain isoenzymes (BB) of creatine kinase were prepared by the injection of the highly purified rabbit enzyme into roosters. The antibodies were found to cross-react only partially with BB of rat, guinea pig, sheep, monkey, and man, demonstrating that these proteins are not entirely identical with respect to their antigenic sites. A greater degree of species specificity seems to exist for BB than for the muscle isoenzyme (MM) suggesting that BB may have undergone considerable evolutionary modification. Developmentally mature rabbit cardiac and skeletal muscles contained large quantites of an enzymatically inactive BB which can be detected immunochemically. It is antigenically identical with active rabbit BB but the two proteins can be separated by DEAE-cellulose chromatography. Enzymatically inactive BB is also present in human skeletal muscle. The presence of MM in muscle provides sufficient catalytic function and may have permitted the evolution of inactive BB in an additional (noncatalytic) metabolic role.

Animals↗
PubMed1977

Brain isoenzyme of creatine kinase. III. Active and inactive forms in dystrophic muscle of vitamin E-dificient rabbit.

Rabbits were fed a vitamin E-deficient diet for 7 weeks. Control rabbits, paired for weight, were pair-fed an identical diet supplemented with vitamin E. After 3 weeks the expermental animals showed a rise in serum creatin kinase activity which was attributable to the muscle isoenzyme (MM). No rise in creatine kinase activity or appearance of MM was noted in the serum of the control rabbits. Total creatine kinase activity and MM activity were reduced in the gastrocnemii of the experimental animals while the activities of the brain (BB) and hybird (MB) isoenzymes were increased. The specific activity of BB based on immunochemically determined BB protein was not different from normal in either the experimental or control group. Activation of pre-existing inactive BB is probably not the explanation for increased BB activity in the gastroncnemii of the experimental group.

Animals↗
PubMed1977

Experimental studies on a mutant gene (p) causing premature death of Ambystoma mexicanum embryos.

The premature death (p) mutation is a recessive lethal, which, in the homozygous condition, gives rise to a complex of abnormalities. The mutant embryos develop only to stage 37, at which time disintegration of superficial tissue begins. Many of the abnormalities observed in sections of the stage-37 mutant embryo are related to its failure to establish a functioning circulatory system, or to the resulting edema and/or ascites that distend the abdomen and flanks. There are, however, abnormalities of heart, liver, gill and muscle development which cannot be attributed to lack of circulation and edema. All of these abnormalities can be indirectly related to the endoderm, particularly the anterior and dorsal endoderm. The findings, therefore, suggest that the mutation leads to a fairly general defect of the endoderm.

Ambystoma↗
PubMed1976

Diploid gynogenesis in the Mexican axolotl.

Gynogenetic diploid axolotls were produced by activating eggs with ultraviolet-inactivated sperm, and then subjecting the activated eggs to heat shock. Optimal conditions for ultraviolet inactivation of the sperm, and for suppression of the second meiotic division by heat shock, were established. Gynogenetic diploids produced by these procedures included progeny homozygous for recessive alleles carried by a heterozygous mother. Gynogenesis could, therefore, be used to uncover new mutations more rapidly than by conventional inbreeding techniques. However, some difficulty was encountered in recognizing mutant phenotypes because of the high incidence of abnormalities and deaths. Defective embryos probably resulted from a combination of heat-shock-induced damage to the eggs and the expression of deleterious recessive alleles carried by the mother.

Ambystoma↗
PubMed1976

Lipid composition of developing Xenopus laevis embryos.

The total lipid content, amount of phospholipid, proportions of major polar and neutral lipid classes, and the overall fatty acid composition were examined in Xenopus laevis embryos. No obvious differences were observed in any of the parameters between fertilization and hatching or between eggs produced by different females. The average lipid content per egg was 113 mug, 31.6 mug of which was phospholipid. The major phospholipids were phosphatidylcholine and sphingomyelin. The major fatty acids were palmitic and oleic acids, but polyunsaturated fatty acids were also present in substantial amounts. The results suggest that significant de novo synthesis of lipids does not occur until after hatching.

Animals↗
PubMed1975

The effect of salt on phospholipid fatty acid composition in Escherichia coli K-12.

The fatty acid compositions of the three major phospholipids of Escherichia coli K-12; phosphatidylethanolamine, phosphatidylglycerol and cardiolipin; were determined during growth in media differing in NaCl concentration. Significant differences in fatty acid composition of the phospholipids were observed in the stationary phase cultures, but no appreciable differences were found in early exponential cultures.

Cardiolipins↗
PubMed1975

A new method for the isolation of methionyl transfer RNA synthetase mutants from Escherichia coli.

Six methionine auxotrophs were isolated from an E. coli K-12 strain which required up to 100 times as much methionine for growth as a conventional auxotroph. In these mutants the methionyl-tRNA synthetase had an increased Km for methionine. The Km value for the mutants ranged from 0.48 to 1.63 mM, compared to 0.078 mM for the wild type. The Km (methionine) for S-adenosyl methionine synthetase was not altered.

Amino Acyl-tRNA Synthetases↗
PubMed1973

Lipolytic bacteria in the Ottawa river.

Lipolytic bacteria were isolated from two stations on Brewery Creek, an arm of the Ottawa River, during the winter of 1971-72. Total counts were approximately sevenfold higher at the more polluted downstream station, whereas lipolytic counts were about 100-fold higher. At this station, significantly more lipolytic bacteria grew on plates incubated at 20 C than at 4 C, suggesting that the population was comprised of both mesophiles and psychrophiles. However, at the upstream station, approximately the same number were obtained at both temperatures. A total of 434 isolates, mainly from the downstream station, were tentatively classified. The major groups were Pseudomonas, Acinetobacter-Moraxella, and Aeromonas. Though the total number of lipolytic bacteria was fairly constant throughout the winter, the relative abundance of the acinetobacters dropped from approximately 90% in November to less than 10% in March, and then increased. The aeromonads and pseudomonads showed the opposite trend. Most of the bacteria, though isolated at 4 C, also grew at 30 C. Lipolysis, however, was generally strongest at 20 C or below.

Aeromonas↗