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Biomedical subjects

K Mitsui

Publications and source records attributed to K Mitsui.

At least 199 records · Page 11Linked to original sources
PubMed1985

Ultrasonic aspiration in coronary artery surgery.

With the aid of an ultrasonically powered aspiration device, the coronary artery to undergo distal anastomosis during aortocoronary bypass grafting can be exposed in the beating heart prior to institution of cardiopulmonary bypass and systemic administration of heparin. The thick adipose tissue and bridging muscles of the superficial layer are removed with almost no bleeding, leaving the vascular elements intact. The optimal site for anastomosis of the coronary artery is readily exposed and confirmed, and aortic cross-clamp time is minimized.

Coronary Vessels↗
PubMed1985

[Changes of peripheral lymphocyte subsets in patients with oral squamous carcinoma].

The distribution of peripheral lymphocyte subsets of 32 patients, who had undergone surgical removal of squamous carcinoma and have evaded recurrence was studied using OK series monoclonal antibodies. The T-lymphocyte subpopulation was reduced in patients who were tumor free for more than 3 years. The helper/inducer T-cell subpopulation was reduced in most of the patients studied, whereas little change was observed in the subpopulation of suppressor/cytotoxic T cells. Consequently the ratio of OKT 4+/OKT 8+ was reduced in accordance with the tumor free period.

Adult↗
PubMed1985

[Brain death].

Explore the source record for details and available documents.

Brain↗
PubMed1984

Necessity of polyamines for maximum in vivo synthesis of beta beta' subunits of RNA polymerase.

The possibility that polyamines can stimulate the in vivo synthesis of beta beta' subunits of RNA polymerase has been examined through the use of a polyamine-requiring mutant of Escherichia coli. Results from autoradiographic estimation and activity measurement of RNA polymerase in cell extracts prepared from polyamine starved and unstarved bacteria showed that polyamines stimulate the synthesis of beta beta' subunits of RNA polymerase 2- to 3.6-fold.

DNA, Viral↗
PubMed1984

Preferential stimulation of the in vivo synthesis of a protein by polyamines in Escherichia coli: purification and properties of the specific protein.

The possibility that polyamines can stimulate the synthesis of special kinds of proteins has been examined by using a polyamine-requiring mutant of Escherichia coli. It was found that the synthesis of some proteins, particularly one with a molecular weight (Mr) of 62K, was significantly stimulated following polyamine supplementation of polyamine-starved cells. The preferential stimulation of the synthesis of this polyamine-induced protein of Mr 62K (PI protein) was followed by the stimulation of overall protein synthesis by polyamines. PI protein was purified to homogeneity and some of its properties were examined. From studies on the effect of PI protein on MS2 RNA directed protein synthesis, it was shown that this protein stimulated the synthesis of RNA replicase by 2.2-fold in the presence of 1 mM spermidine.

Bacterial Proteins↗
PubMed1984

Modification of thiol groups of Jack bean urease with diazonium-1H-tetrazole.

Jack bean urease [EC 3.5.1.5] was modified with diazonium-1H-tetrazole (DHT). Reaction of DHT with the enzyme produced a characteristic absorption peak at 320 nm and led to complete loss of the enzymatic activity at a low concentration of DHT. Amino acid analysis of DHT-modified urease showed that only cysteine residues reacted with the reagent and other amino acid residues such as tyrosine, histidine, and lysine did not. The enzymatic activity was protected against DHT-inactivation by the addition of substrate. On the other hand, when the cysteine residues were modified with DHT, the enzyme was not converted to polymeric forms. Furthermore, the binding ability of urease with hydroxamic acid, a specific urease inhibitor, was virtually unaffected by DHT-inactivation. These results indicate that cysteine residues are specifically modified by DHT with concomitant loss of enzymatic activity and polymerization ability, but are not essential for the binding of hydroxamic acid to the enzyme.

Amino Acids↗
PubMed1984

Amino acid sequence around a cysteine residue in the active center of jack bean urease.

Cysteine residues in the active center of jack bean urease [EC 3.5.1.5] were modified with 14C-labeled diazonium-1H-tetrazole (DHT). The labeled enzyme was carboxymethylated with iodoacetic acid, and then hydrolyzed with trypsin. The tryptic digest was subjected to gel filtration on Sephadex G-50, yielding two radioactive fractions. The [14C]DHT-labeled peptide having a lower molecular weight, which was determined to be approximately 1,000 by the method of gel filtration, was further purified to homogeneity by ion-exchange chromatography on DEAE-Sephadex A-25. [14C]DHT-labeled cysteine was identified as cysteic acid after performic acid oxidation, and the amino acid sequence of the low-molecular-weight [14C]DHT-labeled peptide was determined to be Phe-Glu-Pro-Gly-Asp-Cys-Asn-Ser-Thr-Phe-Lys.

Amino Acid Sequence↗
PubMed1983

Differential stimulation by polyamines of phage DNA-directed in vitro synthesis of proteins.

The effect of polyamines on T7- and lambda rifd18 DNA-directed synthesis of proteins in an Escherichia coli cell-free system has been studied. When T7 DNA was used as a template, the degree of stimulation by spermidine of protein synthesis was larger with T7 RNA polymerase than with Mr 42 K protein, while the synthesis of Mr 13.5 K protein was not stimulated significantly by spermidine. The synthesis of T7 RNA polymerase was stimulated approx. 10-fold by 1 mM spermidine. When lambda rifd18 DNA was used as a template, the synthesis of beta beta' subunits of RNA polymerase was stimulated greatly by spermidine, while the synthesis of elongation factor Tu and ribosomal proteins was not stimulated significantly by spermidine. Spermidine stimulation of T7 DNA-directed synthesis of T7 RNA polymerase was at the level of both translation and transcription. The degree of stimulation by spermidine was greater at the level of translation. Putrescine stimulated the synthesis of T7 RNA polymerase and Mr 42 K protein to a small degree at the level of translation.

Bacteriophage lambda↗
PubMed1983

Effect of polyamines on synthesis and degradation of guanosine 5'-diphosphate 3'-diphosphate.

The effect of polyamines on the in vitro and in vivo synthesis and degradation on guanosine 5'-diphosphate 3'-diphosphate (ppGpp) has been studied in Escherichia coli. The presence of 2 mM spermidine lowered the optimal Mg2+ concentration for ppGpp formation from 17 mM to 11 mM. The formation of ppGpp in the presence of 2 mM spermidine and 11 mM Mg2+ was about 15% greater than that in the presence of 17 mM Mg2+. At a concentration of less than 11 mM Mg2+, spermidine was found to stimulate ppGpp formation greatly. Putrescine did not cause any effect. When a polyamine-requiring mutant of E. coli (EWH319) was starved for an amino acid by the addition of valine, spermidine stimulated ppGpp formation. The degradation of ppGpp was not influenced significantly by polyamines.

Bacterial Proteins↗
PubMed1983

Photo-oxidation of Jack bean urease in the presence of methylene blue.

Photo-oxidation of Jack bean urease was performed in the presence of a low concentration of methylene blue, which led to the complete loss of the enzymatic activity. The inactivation was more remarkable in an alkaline region than in an acidic region and prevented by the addition of histidine or methionine. Amino acid analysis of the oxidized enzyme revealed that the number of histidine residues had decreased to 73% that of the native enzyme, but the numbers of other amino acid residues were not significantly affected. Benzohydroxamic acid, a specific urease inhibitor, protected the active site of the enzyme against photo-oxidation. On the other hand, oxidation of the enzyme decreased its binding ability with caprylo- and benzohydroxamic acid to one-third. These results suggest that histidine residues are modified by photo-oxidation and are essential to both the enzymatic activity and the binding ability with hydroxamic acid.

Fabaceae↗
PubMed1982

Effects of cholesterol evulsion on susceptibility to perfringolysin O of human erythrocytes.

Human erythrocytes preincubated with a phosphatidylcholine suspension (preincubated cells) showed decreased susceptibility to perfringolysin O, the decrease being strongly affected by preincubation time and temperature, and the phosphatidyl choline concentration. The binding of the toxin to the preincubated cells also decreased with the preincubation time and reached minimum at 37 degrees C for 6 h. Through this preincubation, about 30% of cholesterol was removed from cells without lysis. The susceptibility of preincubated cells to the toxin seemed to be affected by the amount of cholesterol removed from cells, but not by the cholesterol content of cell membranes. This indicates that most of the cholesterol interactive with the toxin is removable from cell membranes by preincubation with phosphatidylcholine suspension, and that the residual cholesterol is firmly constituted in the membrane structure and cannot interact with the toxin. After cholesterol evulsion by the preincubated plasma method (Murphy, J.R. (1962) J. Lab. Clin. Med. 60, 86-109 and 60, 571-578), cells also exhibited lower susceptibility to the toxin and to saponins, but higher susceptibility to lysophosphatidylcholine.

Bacterial Toxins↗
PubMed1982

Age-development changes in susceptibility of erythrocytes to perfringolysin O.

Susceptibility to perfringolysin O of erythrocytes from mice of different ages was examined. Erythrocytes of mice younger than 5 weeks' old were more resistant to the toxin than those of young adult and adult mice. Erythrocytes of aged mice were about 3.5 times more susceptible to the toxin than erythrocytes from 4-week-old mice. The membrane cholesterol content of erythrocytes appeared to be maintained at a constant level throughout the ages of mice examined. About 5% of the total membrane cholesterol was supposed to provide receptor sites for the toxin from an experiment in which cholesterol was specifically extracted by liposomes. It was demonstrated in this experiment that susceptibility of erythrocytes to the toxin was lost in proportion to the reduction in the toxin binding. The susceptibility, however, of erythrocytes from young or aged mice was much lower or higher than expected from the changes in toxin binding. Therefore, two possibilities were raised to account for age-related alterations in the susceptibility of erythrocytes; not only expansion of a particular compartment of membrane cholesterol as a toxin receptor but also some activation of intracellular reactions leading to hemolysis might occur in senescence.

Aging↗
PubMed1982

High-molecular-weight hemolysin of Clostridium tetani.

Clostridium tetani excretes hemolysins of two size classes, a high-molecular-weight hemolysin (HMH), which was eluted near void volume of a Sepharose 6B column, and conventional tetanolysin (molecular weight, approximately 50,000). The total hemolysin activity in the culture supernatant increased sharply with growth of bacteria and remained at a high level during autolysis. The content of HMH, however, decreased from 41% at 4 h of culture to 0.4% at the early stage of autolysis. The cell bodies also exhibited hemolytic activity, 70% of which could be solubilized and separated into HMH and the 50,000 Mr tetanolysin as extracellular hemolysins. The activity ratio of HMH to the total solubilized hemolysins was 0.45, on the average, at 6 h of culture but was 0.23 at the middle of logarithmic growth. Partially purified HMH from both sources appeared as broken pieces of cytoplasmic membranes under an electron microscope. The ratio of proteins to phospholipids in HMH was found to 3.26, a value similar to that in cell membrane. The total cell hemolytic activity decreased by 90 or 75% upon addition of chloramphenicol or anti-tetanolysin serum, respectively, into a 6-h-old culture of bacteria. It is suggested that HMH is a complex of tetanolysin with a membrane fragment and releases the conventional tetanolysin during bacterial culture.

Bacterial Toxins↗