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Biomedical subjects

T Toda

Publications and source records attributed to T Toda.

At least 325 records · Page 18Linked to original sources
PubMed1987

Cloning and characterization of BCY1, a locus encoding a regulatory subunit of the cyclic AMP-dependent protein kinase in Saccharomyces cerevisiae.

We have cloned a gene (BCY1) from the yeast Saccharomyces cerevisiae that encodes a regulatory subunit of the cyclic AMP-dependent protein kinase. The encoded protein has a structural organization similar to that of the RI and RII regulatory subunits of the mammalian cyclic AMP-dependent protein kinase. Strains of S. cerevisiae with disrupted BCY1 genes do not display a cyclic AMP-dependent protein kinase in vitro, fail to grow on many carbon sources, and are exquisitely sensitive to heat shock and starvation.

Amino Acid Sequence↗
PubMed1986

Enzyme-linked immunodetection of proteins on Coomassie blue-stained two-dimensional cellulose acetate membranes.

Cellulose acetate membrane on which proteins are separated by two-dimensional electrophoresis and visualized by Coomassie staining is directly subjected to an enzyme-linked immunodetection method using a horseradish peroxidase-conjugated second antibody. The Coomassie-stained and immunochemically stained spots are distinguishable by their colors, such as blue with Coomassie blue staining and purple with horseradish peroxidase staining. Two kinds of lighting make the distinction more apparent. Coomassie-stained protein patterns are clear in the transmitted light. However, the immunochemically stained protein spots are obvious in the reflected light, in which Coomassie-stained patterns are obscure. The procedures do not require proteins to transfer onto nitrocellulose paper in contrast to proteins in polyacrylamide gel. The simple procedure excludes the nonspecific binding of the first and second antibodies to blocking proteins such as bovine serum albumin or gelatin because blocking protein is not used. With this method, matching of the Coomassie blue-stained spot with the immunochemically stained spot is done accurately and easily.

Animals↗
PubMed1986

Purification and identification of intermediate catabolic products in the in vivo degradation of pig liver phosphofructokinase.

Phosphofructokinase (ATP:D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) was purified to homogeneity from pig livers. Polyclonal antibody against the enzyme was induced in a rabbit, and the IgG fraction was obtained by chromatography on a Protein A-Sepharose CL-4B column. The specific antibody was purified further by immunoaffinity chromatography on a phosphofructokinase-conjugated affinity column. Intermediate catabolic products of phosphofructokinase were extracted from fresh pig livers under conditions of inhibition of proteinases, concentrated by chromatography on an anti-phosphofructokinase IgG-conjugated affinity column, and purified by two-dimensional polyacrylamide gel electrophoresis. Their cross-reactivities to the purified phosphofructokinase were assessed by an immunoelectrotransfer blot method. The intact form of phosphofructokinase in pig liver was demonstrated as the major spot of 84 kDa on the blot. Polypeptides of 68, 64, 56, and 51 kDa showed apparent cross-reactivities to phosphofructokinase. The structural homology among them was confirmed by proteinase V8 digestion followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The possibility of artifacts in preparation was ruled out by an internal tracer method. Thus, it is concluded that the predominant isozyme of phosphofructokinase in pig liver (84 kDa) is in vivo degraded via intermediate catabolic products of 68, 64, 56, and 51 kDa.

Animals↗
PubMed1986

Ultrastructural study of malonaldehyde-induced arterial lesions in chickens.

The effects of malonaldehyde on the arteries of chickens were studied in a 4-week treatment of a subcutaneous injection of 1 ml of 50% malonaldehyde in corn oil per kg of body weight 3 times a week and/or ad libitum feeding of a 1% cholesterol containing diet. The malonaldehyde had little effect on plasma cholesterol and triglyceride levels. However, degenerate cells without stainable lipid were frequently observed in the arteries of these chickens. Ad libitum feeding of a 1% cholesterol-containing diet produced no significant degenerative changes in the arterial smooth muscle cells. A combination treatment of cholesterol feeding and malonaldehyde injections resulted in a significant increase in the number of degenerate cells without stainable lipid and lipid-containing cells in the plaque of the abdominal aortas. These results indicate that malonaldehyde is a potent angiotoxin.

Animals↗
PubMed1986

Cloning and characterization of the high-affinity cAMP phosphodiesterase of Saccharomyces cerevisiae.

A gene, PDE2, has been cloned from the yeast Saccharomyces cerevisiae that, when present in high copy, reverses the phenotypic effects of RAS2Val19, a mutant form of the RAS2 gene that renders yeast cells sensitive to heat shock and starvation. It has previously been shown that the RAS proteins are potent activators of yeast adenylate cyclase. We report here that PDE2 encodes a high-affinity cAMP phosphodiesterase that shares sequence homology with animal cell phosphodiesterases. These results therefore imply that the effects of RAS2Val19 are mediated through its changes in cAMP concentration.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1986

Effect of magnesium deficiency on ultrastructural changes in coronary arteries of swine.

The effects of magnesium (Mg) deficiency on the coronary arteries of 27 Yorkshire swine were studied by light and electron microscopy. The experimental animals were divided into 4 groups which received the following supplements: Group I, basal ration with adequate Mg (540 mg/kg diet), Group II, basal ration with insufficient Mg (270 mg/kg diet) Group III, 10% milk powder with adequate Mg (540 mg/kg diet), Group IV, 10% milk powder with insufficient Mg (270 mg/kg diet). Serum analysis indicated that dietary low Mg supplementation decreased cholesterol levels and increased phospholipid concentrations significantly. The highest magnitude and incidence of intimal thickening were observed in the coronary arteries of Group IV (p less than 0.003). No significant intimal thickening was detected in any of the other groups. Ultrastructural studies revealed a greater frequency of degenerated cells in Group III and IV (p less than 0.01). Numerous calcifications were observed in only Group IV. These data suggest that moderate Mg deficiency can promote atherosclerosis in combination with some atherogenic diet, and that the presence of smooth muscle cell degeneration is important in order for a magnesium deficiency to exert an effect on the coronary artery of swine.

Animals↗
PubMed1986

Differential expressions of essential and nonessential alpha-tubulin genes in Schizosaccharomyces pombe.

The fission yeast Schizosaccharomyces pombe has two alpha-tubulin genes and one beta-tubulin gene. Gene disruption experiments showed that the alpha 1-tubulin gene (NDA2) is essential whereas the alpha 2 gene is dispensable. The alpha 2-disrupted cells missing alpha 2 transcript and alpha 2 polypeptide could grow and sporulate normally. The alpha 2 gene, however, was expressed in the wild type and the alpha 1 mutant. Alpha 2-Tubulin was distinguished as an electrophoretic band and was assembled into microtubules. The alpha 2-disrupted cells had an increased sensitivity to an antimicrotubule drug thiabendazole, and the alpha 1(cold-sensitive [cs]) alpha 2 (disrupted) cells became not only cs but also temperature sensitive. Northern blot experiments indicated that alpha 2 transcription was minor and constitutive whereas alpha 1 transcription was major and modulated, depending on the gene copy number of the alpha 2 gene. The amounts of alpha 1 and alpha 2 polypeptides estimated by beta-galactosidase activities of the lacZ-fused genes integrated on the chromosome and by intensities of the electrophoretic bands in crude tubulin fractions, however, were comparable, indicating that alpha 2 tubulin is not a minor subtype. We assume that the cells of Schizosaccharomyces pombe have no excess tubulin pool. alpha 1 mutants would then be blocked in the cell cycle because only half the amount of functional alpha-tubulin required for growth can be produced by the alpha 2 gene. On the other hand, the alpha 2-disrupted cells became viable because the synthesis of alpha 1 tubulin was increased by transcriptional or translational modulation or both. The real cause for essential alpha 1 and dispensable alpha 2 genes seems to be in their regulatory sequences instead of the coding sequences.

Gene Expression Regulation↗
PubMed1986

A rapid silver staining method for identification of Mycobacterium leprae in histologic sections.

A few methods have been reported for the purpose of staining Mycobacterium leprae in paraffin sections, including Fite oil fuchsin method, auramine-rhodamine method, and Blanco-Fite silver method. Among these staining techniques, Fite oil fuchsin method and auramine-rhodamine method are popular. However, the Blanco-Fite silver method takes approximately 20 days. Therefore, we developed a new procedure for rapid identification of M. leprae in paraffin sections using another silver solution and found that the procedure gave stable and satisfactory results. This new method has proved superior to others in demonstrating a reliable staining for M. leprae.

Humans↗
PubMed1986

Exploring the function of RAS oncogenes by studying the yeast Saccharomyces cerevisiae.

The RAS oncogenes comprise a family of genes found to be activated in perhaps 10-20% of human cancers and which have been highly conserved in evolution. Homologs of the mammalian RAS exist in the yeast Saccharomyces cerevisiae (RAS1 and RAS2). We have shown that human ras proteins can complement the loss of RAS1 and RAS2 proteins in yeast, and hence are functionally homologous. Both human and yeast RAS proteins can stimulate the magnesium and guanine nucleotide-dependent adenylate cyclase activity present in yeast membranes. However, RAS proteins do not appear to stimulate adenylate cyclase in vertebrate cells. Our studies indicate that although RAS proteins are essential controlling elements of adenylate cyclase in yeast, they have other essential functions in that organisms. RAS proteins are themselves probably controlled by growth regulatory proteins.

Fungal Proteins↗
PubMed1986

[Two cases of recurrent gastrointestinal carcinoma treated with long-term THP].

Two patients with recurrent gastrointestinal carcinoma were treated with THP. Partial response was recognized in the local recurrent tumor of one patient and in liver metastasis of a second patient. THP was administered every three weeks at a dose of 60 mg per total body weight intravenously. The total dose of THP achieved was 720 mg in the first patient and 920 mg in the second. Despite the high dosage, neither cardiotoxicity nor alopecia was observed. These results suggest that the administration of THP may be efficacious and safe in the management of patients with recurrent gastrointestinal carcinoma.

Adenocarcinoma↗
PubMed1985

Plasma lipid peroxidation in hyperlipidemic chickens.

Laying and genetically defective non-laying hens were evaluated for plasma lipid and plasma peroxidation levels. The non-layers developed extreme hyperlipidemia as well as greatly increased levels of lipid peroxidation. It was concluded that the concurrent presence of lipid peroxidation products must be considered when evaluating hyperlipidemic causes of atherosclerosis in the chicken.

Animals↗
PubMed1985

In yeast, RAS proteins are controlling elements of adenylate cyclase.

S. cerevisiae strains containing RAS2val19, a RAS2 gene with a missense mutation analogous to one that activates the transforming potential of mammalian ras genes, have growth and biochemical properties strikingly similar to yeast strains carrying IAC or bcy1. Yeast strains carrying the IAC mutation have elevated levels of adenylate cyclase activity. bcy1 is a mutation that suppresses the lethality in adenylate cyclase deficient yeast. Yeast strains deficient in RAS function exhibit properties similar to adenylate cyclase deficient yeast. bcy1 suppresses lethality in ras1- ras2- yeast. Compared to wild-type yeast strains, intracellular cyclic AMP levels are significantly elevated in RAS2val19 strains, significantly depressed in ras2- strains, and virtually undetectable in ras1- ras2- bcy1 strains. Membranes from ras1- ras2- bcy1 yeast lack the GTP-stimulated adenylate cyclase activity present in membranes from wild-type cells, and membranes from RAS2val19 yeast strains have elevated levels of an apparently GTP-independent adenylate cyclase activity. Mixing membranes from ras1- ras2- yeast with membranes from adenylate cyclase deficient yeast reconstitutes a GTP-dependent adenylate cyclase.

Adenylyl Cyclases↗
PubMed1985

Angiotoxicity in swine of a moderate excess of dietary vitamin D3.

The effects of five different dietary levels of vitamin D3 on the coronary arteries of groups of 17-60 2-month old weanling Yorkshire swine were studied. Four groups were fed the following levels of vitamin D3 per ton of ration continuously for 4 months: group I--100,000 IU, group II--300,000 IU, group IV--2,000,000, and group V--4,000,000 IU. Swine in group III were fed the diet containing 100,000 IU of vitamin D3 per ton of ration for the first 2 months of the study after which they were fed a diet supplemented with 4,000,000 IU of vitamin D3 per ton of ration for the remaining 2 months of the study. The highest degree of intimal thickening of the coronary arteries was observed among group V. The thickened areas contained numerous lipid-containing cells and degenerate cells without stainable lipid. Electron microscopic examination revealed a greater frequency of degenerate cells without stainable lipid in the coronary arteries of groups III and IV than in groups I and II. These results suggest a possible link between excessive daily intake of vitamin D3 and the development of human coronary atherosclerosis.

Animals↗