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Biomedical subjects

T Yasuda

Publications and source records attributed to T Yasuda.

At least 883 records · Page 49Linked to original sources
PubMed1982

Biological activity of chemically synthesized analogues of lipid A. Demonstration of adjuvant effect in hapten-sensitized liposomal system.

The adjuvant effect of synthetic analogues of lipid A was investigated in mice in vivo. Two of the five synthetic lipid A analogues showed adjuvant activity when they were incorporated into dipalmitoylglycerophosphocholine-cholesterol-dipalmitoylglycerophosphate liposomes sensitized with trinitrophenylaminocaproylglycerophosphoethanolamine. The minimum structure for an adjuvant effect in the liposomal immunogen system was 1-monophosphate of 6-0-(2-deoxy-2-tetradecanoylamino-6-0-tetradecanoyl-D-glucopyranosyl)-2-deoxy-2 -tetradecanoyl-amino-3,4-di-O-tetradecanoyl-D-glucopyranose.

Adjuvants, Immunologic↗
PubMed1982

Studies of catalysis by ribonuclease U2. Steady-state kinetics for transphosphorylation of oligonucleotide and synthetic substrates.

The values of the steady-state kinetic parameters for the RNase, U2 catalyzed transphosphorylation were measured for several di- and trinucleotides such as ApXp (X = A, C, G, or U), ApYpGp, and YpApGp (Y = C or U). The pH dependence of kcat/Km for ApUp indicated a dependence for catalysis upon an unprotonated group with pK = 3.8 and two proton-associated groups with pK = 4.4 and 5.0. As judged from kcat/Km values, ApUpGp and ApCpGp are better substrates than the corresponding parent dimers, ApUp and ApCp, respectively. By contrast, the kcat/Km for UpApGp was about 1/20 relative to that of the parent dimer, ApGp. The results were compared for possible thermodynamic and structural information about the chemical consequences. The inhibition of the RNase U2 catalyzed reaction of ApUp by a series of nucleosides and nucleotides was also studied. Evidence for similarities and dissimilarities in the binding and catalysis by RNase U2 and RNase T1 is presented.

Base Sequence↗
PubMed1982

Hemodynamic effects of prostaglandin E1 during cardiopulmonary bypass in infants and children.

Effects of prostaglandin E1 (PGE1) and phenoxybenzamine (POB) on the hemodynamics during cardiopulmonary bypass (CPB) were studied in 30 infants and children. Patients were grouped into three; PGE1 was given to ten patients, POB to another ten, and the other ten patients served as the control. Vasodilating drugs were withheld. PGE1 was infused at 0.01 to 0.02 microgram/kg/min during CPB, and POB at 1.0 mg/kg within the initial 10 minutes of bypass. There was a significant drop in arterial and venous pressure at the time of initiation of bypass in both the PGE1 and POB groups. In the PGE1 group in particular, such a stable hemodynamic condition of over 60 mm Hg in mean arterial pressure, 7.5 to 12.5 cmH2O in central venous pressure, 1300 to 1700 dynes . sec . cm -5 in systemic vascular resistance was maintained throughout CPB, as compared with the other two groups. PGE1 contributed to an adequate diuresis and the preservation of platelets. Our findings indicate that PGE1 has potential clinical advantages for application during CPB.

Alprostadil↗
PubMed1982

Accuracy of localization of acute myocardial infarction by 12 lead electrocardiography.

Until recently, ECG accuracy in localizing acute myocardial infarction (AMI) could be assessed only by comparing the ECGs with autopsy findings. This approach, however, preselected patients, including only those who died. It is possible that this postmortem group of patients would be different from the whole population of patients with AMI. Myocardial imaging with 99mTc-pyrophosphate offers the advantage of directly localizing the region of injured myocardium in the acute phase of AMI. In 34 patients with confirmed AMI and focal uptake of 99mTc-pyrophosphate, serial ECGs were obtained and interpreted by two independent observers. The sensitivity and specificity of serial ECGs in determining the location of AMI in the five left ventricular (LV) wall segments were determined: (1) in the anterior wall sensitivity was 86.7% and specificity was 89.5%; (2) in the lateral wall sensitivity was 73.7% and specificity was 80.0%; (3) in the high lateral wall sensitivity was 80.0% and specificity was 87.5%; (4) in the inferior wall sensitivity was 87.5% and specificity was 100%; (5) in the "true" posterior wall sensitivity was 83.3% and specificity was 86.4%. Overall, in the 170 LV wall segments (five per patient) examined, scans localized with a sensitivity of 81.9% and a specificity of 88.8%. After four patients with LBBB were excluded, sensitivity increased to 87.1%. Overall, localization of AMI by serial ECG was accurate in 85.9% of the 34 patients included in the study.

Adult↗
PubMed1982

Immunogenicity of liposomal model membranes sensitized with spin-labeled haptens and topographical distribution of haptens on the membranes.

The relation between the in vitro immunogenicity of phosphatidylcholine liposomes containing 2,4-dinitrophenyl-6-N-aminocaproylphosphatidylethanolamine (DNP-Cap-PE) as a hapten and the topographical distribution of the haptens on lipid membranes was studied. In distearoylphosphatidylcholine liposomes, the immunogenicity increased with increase of cholesterol content in the liposomal membranes. The electron spin resonance spectra of spin-labeled DNP-Cap-PE in distearoylphosphatidylcholine liposomes indicated that cholesterol affected the topographical distribution of spin-labeled DNP-Cap-PE on the membranes. In the absence of cholesterol, a considerable amount of haptens was clustered on the distearoylphosphatidylcholine membranes, but with increase of cholesterol, random distribution of the haptens on the membranes increased. The cholesterol-dependent change in the topographical distribution of the haptens on the membranes paralleled the change of immunogenicity, i.e., the immunogenicity was low when haptens were clustered on the liposomal membranes. Haptens arranged at a proper distance on the membranes may be required for optimum immune response.

Animals↗
PubMed1982

In vitro and in vivo antibacterial activity of T-1982, a new semisynthetic cephamycin antibiotic.

The activities of T-1982 (sodium 7 beta-[(2R, 3S)-2-(4-ethyl-2, 3-dioxo-1-piperazine-carboxamido)-3-hydroxybutanamido]-7 alpha-methoxy-3-[(1-methyl-1H-tetrazol-5-yl)thiomethyl]-3-cephem-4-carboxylate) against various gram-positive and gram-negative bacteria were compare with those of cefmetazole, cefoxitin, cefazolin, and cefoperazone. T-1982 was active against both gram-positive and gram-negative bacteria, including genera resistant to the other cephalosporins. T-1982 exhibited greater activity than did cefmetazole, cefoxitin, cefazolin, or cefoperazone against Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Serratia marcescens and was also highly active against Bacteroides fragilis. T-1982 was as stable to various beta-lactamases as were cefmetazole and cefoxitin. The therapeutic activities of T-1982 in mice experimentally infected with various gram-negative bacteria were superior to those of cefmetazole, cefoxitin, cefazolin, and cefoperazone.

Animals↗
PubMed1982

Forssman antibody levels in sera of cancer patients.

By means of SRBC lysis in agarose gel and Forssman (F) liposome lysis assay, serum levels of F antibodies were determined in various cancer patients. F antibody titers of the patient's sera were shown to be lower than that of normal controls. Following radical surgery, F antibody titers were elevated significantly in most of the patients with advanced gastric, colorectal and lung cancer. Similar tends of anti-A antibody titers were observed in group O and B patients with advanced cancer.

ABO Blood-Group System↗
PubMed1982

Studies on protein binding of antibiotics. IV. Effect of the binding of drug to 100,000 X g supernatant fluid of rabbit liver homogenates on urinary excretion.

The extent of the binding of beta-lactam antibiotics to 100,000 X g supernatant fluid of rabbit liver homogenates was investigated. Urinary excretion tended to decrease as the extent of the binding to 100,000 X g supernatant fluid increased. Predicting urinary excretion was achieved using the binding to 100,000 X g supernatant fluid and other physicochemical factors. A good coincidence resulted from multiple regression analysis. [14C]Benzylpenicillin binding proteins in rabbit liver were investigated and revealed that the affinity of cefoperazone was much stronger than that of cefazolin.

Animals↗
PubMed1982

Studies on protein binding of antibiotics. V. Effect of the binding of drug to 100,000 X g supernatant fluid of human liver homogenates on urinary excretion.

To characterize the effect of the binding of antibiotics to tissue protein on urinary excretion, we examined the extent of the binding of 9 penicillins and 9 cephems to 100,000 X g supernatant fluid of human liver homogenates. The correlation analysis revealed a significant simple correlation between the binding to 100,000 X g supernatant fluid of liver homogenates and urinary excretion. Drugs with lesser binding were mainly excreted in the urine, conversely, urinary excretion of highly bound drugs exhibited lower values. The prediction with regard to urinary excretion of healthy subjects was done by multiple regression analysis using the binding to 100,000 X g supernatant fluid and other physicochemical factors. The values predicted for urinary excretion coincided well with the observed values.

Anti-Bacterial Agents↗
PubMed1982

Electron microscopic demonstration of close contact between intracellular mycobacteria and the phagosomal membrane.

Ultrathin sections of granulomatous lung lesions of tuberculous mice were subjected to electron microscopy to observe the intraphagosomal behaviour of mycobacteria. The close contact between the external surface of the bacterial cell wall and the phagosomal membrane was a characteristic feature, This was also observed with ultrathin sections of a mycobacterial specimen harvested from the homogenate of such lungs. The significance of this event was interpreted in relation to the mechanism of mycobacterial infection.

Animals↗
PubMed1982

A novel type of lymphocyte-macrophage association revealed electron microscopically in tuberculous lung lesions of mice.

Electron microscopic survey of tuberculous lung lesions of mice revealed a novel type of lymphocyte-macrophage association. The finger-like projections with sharp or blunt tips of lymphocytes area formed as if pushing deeply the macrophage membrane to form pockets matching the shape of the projections. Intimate membrane contact occurs between these two cells, particularly at the leading edges. The biological significance of this morphological event remains to be a subject for future study.

Animals↗