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Biomedical subjects

A Ohta

Publications and source records attributed to A Ohta.

At least 307 records · Page 17Linked to original sources
PubMed1981

Activation of adenylate cyclase of rat brain by lipid peroxidation.

The relationship between adenylate cyclase activity in the synaptic membrane fraction (M1) of rat brain and lipid peroxidation of these membranes was examined. In the presence of 5 mM dithiothreitol (DTT), 1 to 10 microM Fe/+ activated adenylate cyclase 2- to 4-fold. Of several metal ions, Fe2+ was the most effective. Other enzymes in M1, such as Mg2+-ATPase, (Na+-K+)-ATPase, 5'-nucleotidase, acetylcholinesterase, and phosphodiesterase, were not activated by Fe2+ plus DTT. Activation of adenylate cyclase by Fe2+ plus DTT was accompanied by production of malondialdehyde, a product of lipid peroxidation. Formation of malondialdehyde was completely parallel with enzyme activation. Ascorbic acid or a NADPH system also stimulated enzyme activity and caused lipid peroxidation. Activation of the enzyme and lipid peroxidation induced by Fe2+ plus DTT, ascorbic acid, or NADPH was completely prevented by simultaneous addition of N,N'-diphenyl-p-phenylenediamine, an inhibitor of lipid peroxidation. This inhibitor also prevented the decrease in turbidity of the enzyme preparation induced by Fe2+ plus DTT. The stimulatory effects of NaF, guanylyl-5'-imidodiphosphate and calmodulin, respectively, and that of Fe2+ plus DTT on the enzyme activity were additive. Activation of adenylate cyclase by Fe2+ plus DTT was only observed in brain synaptic membranes, not in erythrocyte ghosts, liver plasma membranes, or cardiac sarcolemma. These results indicate that lipid peroxidation of synaptic membranes was accompanied by specific stimulation of adenylate cyclase activity.

Adenosine Triphosphate↗
PubMed1981

Genetic analysis of human lymphocyte proteins by two-dimensional gel electrophoresis: 1. Detection of genetic variant polypeptides in PHA-stimulated peripheral blood lymphocytes.

Approximately 250 phytohemagglutinin (PHA)-stimulated peripheral blood lymphocyte polypeptides from three unrelated healthy males were compared by high-resolution two-dimensional gel electrophoresis and double-label autoradiography. Comparisons by all possible pairwise combinations of [14C]leucine-labeled proteins from an individual and [3H]leucine-labeled proteins from another revealed that only three polypeptides differed qualitatively among the three individuals. The degree of variation in lymphocyte polypeptides between different individuals was similar to that in fibroblast polypeptides reported previously. Among the three variant polypeptides, two polypeptides with mol. wt. 64,000 and mol. wt. 37,000 coexisted with a polypeptide with the same molecular weight, and they showed the behavior expected of two allelic gene products separated in the isoelectric focusing dimension by charge differences. Analysis of [14C]leucine labeled peripheral blood lymphocyte proteins, from the parents of each individual, by two-dimensional gel electrophoresis indicated that the variant polypeptides with mol. wt. 64,000 and mol. wt. 37,000 in the propositus were inherited from one of his parents. The data indicate that genetic analysis of PHA-stimulated peripheral blood lymphocyte proteins is feasible by high-resolution two-dimensional gel electrophoresis in combination with double-label autoradiography and pedigree analysis.U

Adult↗
PubMed1981

Cloning of the uvrC gene of Escherichia coli: expression of a DNA repair gene.

We have cloned the uvrC gene of Escherichia coli, using an F' plasmid carrying the uvrC region as a source of DNA. Two plasmids, pSC101 and pBR322, were used as cloning vectors. The recombinant plasmids were selected for their ability to complement the uvrC defect of E. coli strains AB1884 and N177. We conclude that the uvrC structural gene is contained in a 1.9-kilobase DNA fragment. The protein encoded by the uvrC gene appears to have a monomer molecular weight of 64,500 as analyzed by denaturing polyacrylamide gel electrophoresis. Strains containing multicopy uvrC+ plasmids overproduce a factor that is missing in lysates of uvrC- mutants and required for an in vitro model repair reaction. The expression of uvrC+ hybrid plasmids suggests that the structural gene is separated by at least 0.8 kilobase from the regulatory region.

DNA Repair↗
PubMed1981

Cloning of genes involved in membrane lipid synthesis: effects of amplification of phosphatidylglycerophosphate synthase in Escherichia coli.

The structural gene (pgsA) for the CDP-diacylglycerol:sn-glycero-3-phosphate phosphatidyltransferase (EC 2.7.8.5, phosphatidylglycerophosphate synthase) from Escherichia coli has been cloned, using pSC101 as the vector. The resulting hybrid plasmids not only correct the lack of in vitro synthase activity in pgsA strains but also cause an amplification (6- to 40-fold over wild-type levels) in enzymatic activity in direct proportion to the copy number of the plasmids found in vivo. The cloned gene also corrects the abnormally low level of polyglycerophosphatides found in pgsA strains and actually increases the level of phosphatidylglycerol to above that normally found in E. coli. The degree of alteration in phospholipid composition brought about by these hybrid plasmids is not of the order expected if fluctuations in enzyme levels in vivo were an important regulatory mechanism in phospholipid metabolism. The isolated hybrid plasmids have been mapped by restriction endonuclease analysis. The presence and location of other genetic markers have also been established. The above data, along with analysis of deletion derivatives of these plasmids and subcloning of appropriate restriction fragments, have established the position of the pgsA locus on the hybrid plasmids. From this data, the position of the pgsA locus has been determined to le between flaI and uvrC on the E. coli genetic map.

Cloning, Molecular↗
PubMed1977

Membrane phospholipid synthesis and phenotypic correlation of an Escherichia coli pss mutant.

A pair of putatively isogenic pss(Ts) and pss+ (phosphatidylserine synthetase structural gene) strains was constructed and analyzed, together with the revertants, for the physiological consequences of cessation of the optimal synthesis of phosphatidylethanolamine (PE). Their in vivo and in vitro abilities to synthetize PE and the growth rates at different temperatures were determined. The rate of PE synthesis by OS2101 pss(Ts) was inversely related to the culture temperature. OS2101 in a low-salt broth medium stopped division and formed filamentous cells with declining viability upon the elevation of culture temperature from 27 to 42 or 44 degrees C, whereas the syntheses of deoxyribonucleic acid, ribonucleic acid, and protein were not affected. Proper concentrations of cations such as Na+, K+, NH4+, and Mg2+ or of sucrose could remedy the division and growth of OS2101 at the restrictive temperature without restoring normal PE synthesis. A remedial effect other than osmotic protection of these effectors and an adaptive regulatory mechanism for PE formation are suggested.

Bacterial Proteins↗
PubMedDate not supplied

Newborn with congenital arteriovenous fistulas of the abdominal wall complicated by a ductus arteriosus aneurysm.

A case of congestive heart failure in a neonate resulting from a congenital abdominal arteriovenous fistula is described; an aneurysm of the ductus arteriosus was also found in the patient. Abdominal aortography was performed and demonstrated dilated feeding arteries, including the hypogastric arteries, which communicated with a dilated umbilical vein. Ligation of the feeding arteries and the umbilical vein led to resolution of the heart failure. Transient liver dysfunction occurred, however. Symptoms improved dramatically upon removal of the ligature from the umbilical vein. Although there is one previous report of an arteriovenous fistula involving the umbilical vein, we know of no prior report of a congenital arteriovenous fistula in association with a ductus arteriosus aneurysm.

Abdominal Muscles↗
PubMedDate not supplied

Primary mitral valve sarcoma in infancy.

Primary cardiac sarcoma is a rare tumor, found especially in children, particularly in the left side of the heart. This report describes a rare case of primary mitral valve sarcoma in a 7-month-old male infant with hemiparesis and heart murmur who underwent mitral valve replacement because of excessive invasion of the mitral valve by the tumor. The patient remains well, free of recurrence and cerebral metastasis, and without adjuvant therapy 18 months after the operation.

Angiography↗
PubMedDate not supplied

Deterioration in learning and memory of fear conditioning in response to context in aged SAMP8 mice.

This study examined age-dependent deficits in the learning and memory of fear conditioning, using a newly developed senescence-accelerated mouse (SAMP8) model of age-related brain dysfunction and its genetically related inbred strain (SAMR1). The mice were classically conditioned to tone by giving aversive foot shocks in a distinct experimental box (context). After conditioning, fear in response to the original context without the tone and to the tone in a different context were tested with no shocks. Freezing behavior was used as a reliable index of fear. At 4 and 8 months, contextual fear was weaker in the accelerated senescence-prone SAMP8 mice than in the accelerated senescence-resistant SAMR1 mice. However, at 1 and 2 months, both SAMP8 and SAMR1 mice showed significant contextual fear to equivalent levels. Aging did not affect the fear response to tone. These results indicate that SAMP8 mice have age-related learning and memory deficits in their fear response evoked by contextual but not explicit tone stimuli. Age-related hippocampal dysfunction is suggested to be the cause of these age-related deficits in contextual fear conditioning in SAMP8 mice.

Aging↗