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Biomedical subjects

Y Shimazu

Publications and source records attributed to Y Shimazu.

At least 37 records · Page 2Linked to original sources
PubMed1995

Reactions of copper(II)-oligopeptide complexes with hydrogen peroxide: effects of biological reductants.

Cu(II) complexes with oligopeptides containing histidyl residue in the second or third position could scarcely activate hydrogen peroxide (H2O2), but they could activate H2O2 to yield hydroxyl radical (.OH) in the presence of biological reductants such as cysteine and ascorbic acid. Further, DNA single strand breakage was also observed during the reactions of Cu(II)-glycylglycylhistidylglycine (GGHG) with H2O2 in the presence of same biological reductants.

Amino Acid Sequence↗
PubMed1994

CHO.K1 cell mutants sensitive to active oxygen-generating agents. I. Isolation and genetic studies.

Nine mutants isolated from CHO.K1 cells with increased sensitivity to the lethal effect of plumbagin (PG), a powerful superoxide generator, were classified into five groups, A-E, according to their sensitivity to PG and methyl viologen (MV). Two mutants of group B (Pa13 and Pb4) were sensitive to both drugs, and two mutants of group C (Pa14 and Pa15) were moderately sensitive to PG and extremely sensitive to MV. To mitomycin C (MMC) these mutants showed cross-sensitivity; especially Pa13 and Pb4 (group B) were highly sensitive to MMC. Genetic complementation analyses of these four mutants were carried out using MV sensitivity. Sensitivity group B was divided into two complementation group, I and II. Pa14 and Pa15 belonged to the same complementation group III. These four mutants were also classified into three complementation groups for MMC sensitivity. Because Pa13 and Pb4 were also sensitive to cis-diamminedichloroplatinum(II), they may have a defect in the repair of DNA crosslinks induced by these agents. A complementation group IV (Pa2 and Pa8) was also suggested based on the studies of MMC sensitivity.

Animals↗
PubMed1994

Oxidative DNA damage induced by Cu(II)-oligopeptide complexes and hydrogen peroxide.

At physiological pH values, Cu(II)-tetraglycine and Cu(II) complexes with peptides containing a histidyl residue at the N-terminal caused DNA strand breakage in the presence of H2O2, whereas Cu(II) complexes with peptides containing histidyl residue in the second or third position did not. Because of the correlation between the generation of hydroxyl radical and DNA strand scission, a mechanism for the reaction is proposed.

Amino Acid Sequence↗
PubMed1994

[Clinical analysis of MRSA pneumonia. Niigata Research Group of MRSA.ABK].

Aged or immuno-compromised patients were mostly affected, by pneumonia caused by infection of MRSA, and more than half of the cases were superinfected with glucose-nonfermentative Gram-negative rods including Pseudomonas aeruginosa. These patients were treated with a monotherapy of arbekacin (ABK) by intravenous drip administration or with a combination of ABK and imipenem/cilastatin, ceftazidime or antifungals. The clinical efficiencies were 55.6% in 11 monotherapy cases and 83.3% in combined therapy. MRSA was eradicated in 31.9% of the patients. These results are comparable with, or superior to the vancomycin therapy in the treatment of MRSA pneumonia. When MRSA is isolated from sputum of pneumonia patients, the discrimination between colonization and infection is important, but the diagnosis is very difficult in many clinical cases before the initiation of chemotherapy. The number of bacteria and the grade of inflammation should be carefully scored before starting a chemotherapy.

Aged↗
PubMed1993

DNA single strand breakage by copper(II) complexes and hydrogen peroxide at physiological conditions.

The conversion of the closed circular double stranded supercoiled DNA (pBR322) to the nicked circular form and linear form was used to investigate DNA nicking induced by the reactions of Cu(II) complexes with hydrogen peroxide (H2O2). As a result, the dose-response curve for the CuII(en) (en:ethylenediamine) mediated H2O2 dependent DNA nicking was observed. For a fixed concentration of CuII(en)2 (1 mM), the concentration of H2O2 producing a maximum extent of DNA nicking was 100 mM. On the other hand, for a fixed concentration of H2O2 (100 mM), the concentration of CuII(en)2 was 1 mM. That is, when the concentration ratio of H2O2 to CuII(en)2 was 100, a maximum extent of DNA nicking was observed. This result is a good accordance with that observed by thiobarbituric acid (TBA) and ESR-spin trapping methods. This result gives first experimental evidence that Cu(II) complex did cause the DNA damage in the presence of H2O2. On the other hand, CuII(edta) (edta: ethylenediaminetetraacetic acid) did not cause the DNA strand breaks with the reaction of H2O2, but it was activated by addition of the biological reductant such as ascorbic acid in the presence of H2O2 to cause the DNA strand breaks.

Ascorbic Acid↗
PubMed1993

In vitro maturation and fertilization of preovulatory dog oocytes.

Mature beagle bitches were injected with exogenous gonadotrophins to induce superovulation. Preovulatory oocytes were collected at 72 h after intravenous injection of human chorionic gonadotrophin and cultured for 72 h in a modified Krebs-Ringer bicarbonate solution containing 10% fetal calf serum and 30 mg gentamicin sulfate l-1. Control oocytes were collected from ovaries of anoestrous bitches and cultured for 72 h. All oocytes were at the germinal vesicle stage when collected. At 72 h of culture, a significantly larger population (31.9%) of preovulatory oocytes reached metaphase II, compared with the control group (12.1%). Ejaculated beagle spermatozoa were washed and preincubated for 4 h, then capacitated spermatozoa were added to the oocytes. The kinetics of sperm penetration into the ooplasm did not differ between the two groups of oocytes, but the development of male and female pronuclei was observed more frequently in oocytes collected from preovulatory follicles. These results suggest that preovulatory maturation is required for the normal development of canine oocytes, although they are ovulated at the germinal vesicle stage.

Animals↗
PubMed1992

Maturation, fertilization, and development of dog oocytes in vitro.

Preovulatory oocytes were collected from ovaries of beagle bitches that had received superovulatory treatment. They were cultured in a modified Krebs-Ringer bicarbonate solution containing 10% fetal calf serum and 30 mg/L gentamicin sulfate for up to 72 h. About 32% of oocytes reached metaphase II by 72 h of culture. When these in vitro-matured oocytes were inseminated with ejaculated beagle spermatozoa that had been preincubated for 4 h, sperm penetration of the zona pellucida started about 1 h after insemination, and both male and female pronuclei were seen in the ooplasm at 8 h after insemination. At 18-20 h after insemination, oocytes were transferred to Whitten's medium and cultured for 76-78 h. The first cleavage was observed at 48 h after insemination, and 15 of 45 oocytes developed to the 2-8-cell stage. These results demonstrate that in vitro-matured canine oocytes can be fertilized and develop to the 8-cell stage in vitro.

Animals↗
PubMed1992

[A study of falls experienced by institutionalized elderly].

This study was conducted to determine what factors are related to falls, conditions contributing to falls and the associated injuries. Subjects who had lived in 3 institutions for the elderly in the western region of Shizuoka Prefecture were chosen. Subjects (n = 181) had an average age of 76.4 +/- 7.8 years, and all were interviewed regardless of their history of falls. For those who had experienced falls further interviews were conducted. The following results were obtained: 1) There were 64 subjects (35.4% of the subjects) who had experienced falls, some having experienced multiple falls (for a total count of 89 falls). 2) The frequency of falls of differed by sex or age was significantly. The frequency of females was significantly higher than that of males. The frequency for those in their 70's was lower than in other age groups. 3) At the time of experiencing falls the majority of subjects had hypertension, eye symptoms, insomnia, paralysis, functional restrictions, were going up or down stairs, working, and had difficulty reading characters in newspapers, had experiences of stumbling or need of medical attention within for the past 2 years. Results of this study showed that, while the use of tranquilizers or hypnotics were not statistically significant, they were closely connected to and increase in falls among the aged. 4) In the causes of falls, intrinsic factors figured in 34 (34.0%) cases, and the extrinsic factors in 66 (66.0%). 5) Both falls and fall-caused external injuries were higher among females than males. Furthermore, female subjects mainly suffered contusions and fractures while male subjects mainly suffered abrasions.

Accidental Falls↗
PubMed1991

[A study of falls experienced by the aged among users of preventive health examination services].

In order to determine what factors are related to falls and the effect on the aged, a study was conducted on subjects aged 60 years and over who had undergone preventive health examinations in the western region of Shizuoka Prefecture. Subjects (n = 305) had an average age of 64.4 +/- 3.8 years, and all were interviewed regardless of their history of falls. For the 66 cases who had experienced falls, further questions prepared in advance, were included. The following results were obtained: 1) There were 66 subjects (21.6% of the subjects) who had experienced falls with some experienced multiple falls for a total count of 91 falls. 2) The frequency of falls of female subjects was significantly higher than that of males. Further, with respect to the type of injuries suffered, in the case of many of the female subjects, these took the form of contusions. 3) The majority of subjects who experienced falls were engaged in farming and most of the falls were work-related. 4) Results of this study showed that, while not statistically significant, cerebrovascular diseases are closely connected to falls and increases the falls coefficient among the aged.

Accidental Falls↗
PubMed1990

[An experimental and clinical study of energy-protein metabolism and host defense-repair mechanism in postoperative period--a significance of administration of branched chain amino acid].

The aim of this study is to evaluate in vivo the effect of branched chain amino acid (BCAA). Experimentally, hepatic energy production and protein synthetic rate were measured in gastrectomized rat which was infused BCAA postoperatively. Clinically, following indices were examined in prospectively randomized patients who underwent abdominal operation and were administered with conventional total parenteral nutrition keeping Calorie/N ratio about 150, including nitrogen balance, urinary 3-methylhistidine, retinol binding protein, B lymphocyte percentage and lymphocyte blastogenesis by phytohemagglutinin. Furthermore, plasma BCAA with their keto-analog level, Factor XIII and opsonic activity were determined in another group of patients who received full strength load of BCAA immediately after subtotal or total gastrectomy, in a controlled prospective randomized double-blinded manner. Results obtained from above mentioned measurements exhibited significant improvement by the administration of BCAA. From these findings, it is suggested that BCAA sustains energy-protein metabolism, supports immunocompetence and promotes wound healing under moderately stressed condition where catabolic response is physiologically compensated.

Adult↗
PubMed1986

[Clinical study of protein and amino acids metabolism in surgical infection--significance of administration of branched chain amino acids].

Anastomotic leakage and fistula of alimentary tract are accompanied by peritonitis because of exudation of contents in the digestive canal. In order to inquire about metabolism of protein and amino acids in surgical infection, this study was performed by the method of a time related cross-over trial, comparing high branched chain amino acids (BCAA) solution with low BCAA solution. The following results were obtained. When metabolism is physiologically compensated in infection, it was suggested that there appeared to be gluconeogenesis, ureagenesis and a liver disturbance accompanied in the early phase of sepsis. Administration of BCAA leads to an inhibition of muscle protein break down and a promotion of visceral protein synthesis in the case of severe infection. Administration of BCAA enriched amino acids solution have an important therapeutic measure under severe stressed condition and a significant role in medicine.

Adult↗
PubMed1976

Evidence that the gene uvrB is indispensable for a polymerase I deficient strain of Escherichia coli K-12.

Conclusive evidence in presented to show that the gene uvrA is dispensable, but the uvrB is indispensable for an Escherichia coli strain carrying gene polA1. We constructed strains E139 (sup-126 polAl uvrB59) and E159 (sup-126 polAl uvrA43) where mutations polAl, uvrB59 and uvrA43 are amber mutations and mutation sup-126 is an amber suppressor mutation effective at 30 degrees C but not at 42 degrees C. At 42 degrees C, strain E139 is inviable but strain E159 viable whereas both are viable at 30 degrees C. Revertants of E139 viable at 42 degrees C occurred spontaneously at a frequency of about 3 X 10(-4). One of the revertants was shown to be caused by suppressor mutation, designated spu, rather than back mutation of the gene uvrB59 or polAl or amber suppressor mutation. Viabilities of the revertants varied from 10(-3) to 1.0 at 42 degrees C compared with those of 30 degrees C. At 42 degrees C, all the revertants with normal viabilities at 42 degrees C were non-filamentous in contrast to the filamentous character of E139. However, strain E159 was viable at 42 degrees C despite its filamentous character. We conclude that the gene uvrB is involved not only in excision repair but also in normal growth in a polA background.

DNA Repair↗
PubMed1971

Temperature-sensitive recovery of a mutant of Escherichia coli K-12 irradiated with ultraviolet light.

URT-43 is a mutant of Escherichia coli K-12 which gives a much larger number of survivors when ultraviolet (UV)-irradiated bacteria are incubated on agar medium at 30 C than when they are incubated on the medium at 41 C, although in both cases the number of survivors is fewer than that given by its wild-type ancestor. The UV sensitivity of this mutant was found to be markedly influenced by the presence of a high concentration of NaCl or sucrose in the plating medium. Thus, when irradiated bacteria were plated on agar medium containing 2% NaCl or 0.5 m sucrose at 30 C, they exhibited a resistance similar to that of their wild-type ancestor. At 30 C, there was also an extensive recovery in liquid M9 medium supplemented with all of the nutrients required for growth and NaCl or sucrose. At 41 C, however, the recovery was greatly inhibited. Direct chemical analysis of thymine dimers has revealed that no significant amount of the dimer was released from deoxyribonucleic acid during the period of extensive recovery. It was concluded, therefore, that the temperature-sensitive recovery of URT-43 does not accompany excision of the bulk of pyrimidine dimers. To learn the gene function involved in the recovery, double mutants carrying an additional mutation either in a uvr or a rec gene have been investigated for their UV sensitivities and recovery in liquid medium. It was found that recA(-) and recB(-) derivatives retain the ability of undergoing an efficient recovery at a low temperature, whereas uvrB(-) and uvrC(-) derivatives have completely lost this ability. For these reasons, it was concluded that the mechanism responsible for the recovery of URT-43 involves the function controlled by the uvr genes. The results of photoreactivation suggested that most of the entities dealt with during recovery were pyrimidine dimers.

Agar↗