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Biomedical subjects

M Kuwabara

Publications and source records attributed to M Kuwabara.

At least 235 records · Page 13Linked to original sources
PubMed1985

Interference with a conformational change in the haemagglutinin molecule of influenza virus by antibodies as a possible neutralization mechanism.

A possible mechanism of neutralization of influenza virus by antibodies to the haemagglutinin molecule is proposed in addition to the generally accepted mechanism of blocking attachment to host cell receptors. This proposed mechanism involves interference with a low-pH-induced conformational change in the haemagglutinin molecule by bivalent binding of antibodies, which results in inhibition of the fusion step in the viral replication process.

Antibodies, Monoclonal↗
PubMed1985

Radiation sensitization of Escherichia coli B/r by 2'-chloro-2'-deoxythymidine under various irradiation conditions.

In order to elucidate the mechanism of sensitization of E. coli B/r cells to X-irradiation by 2'-chloro-2'-deoxythymidine (2'Cl-TdR), the survival curves of the cells in which 2'Cl-TdR was incorporated into DNA were obtained following X-irradiation under various conditions. The marked sensitization of E. coli cells by 2'Cl-TdR to the killing action of X-rays was observed, when E. coli cells labelled with 2'Cl-TdR were exposed to X-rays in the absence of oxygen as well as in the presence of oxygen. The sensitization factor calculated from inactivation constants from survival curves irradiated in the absence of O2 was about a half of that obtained in the presence of O2. Under the conditions where 2'Cl-TdR was not incorporated into the DNA of E. coli cells, the presence of 2'Cl-TdR in the cell suspension fluid at the time of irradiation caused no sensitization of the cells to X-irradiation. The sensitization factor for 2'Cl-TdR obtained under N2O was almost same as that obtained under N2. It was also observed that the sensitization factor obtained in the presence of glycerol at a concentration of 1 mol dm-3 under N2 was similar to that obtained in the absence of glycerol. These results indicated that the direct effect of ionizing radiation on DNA was closely associated with the sensitization of E. coli B/r cells by 2'Cl-TdR and that the radical at the C-2' position of the deoxyribose moiety in DNA produced by X-irradiation was transformed into lethal damage for E. coli cells even in the absence of O2. However, this transformation occurred more efficiently in the presence of O2 than in the absence of O2.

Dose-Response Relationship, Radiation↗
PubMed1985

[Experimental and clinical studies on cefmetazole in the field of internal medicine].

Susceptibilities in various types of clinical isolates to cefmetazole (CMZ) were determined by the disk method and the serial agar dilution method for MIC measurement. CMZ showed high antibacterial activity for all Gram-positive cocci except E. faecalis, and for H. influenzae, E. coli, Klebsiella sp. and Proteus sp.. CMZ was administered on 33 patients with infections, mainly biliary tract infections, in the field of internal medicine. The clinical efficacy of the drug was 86.7% for infections of the biliary tract, 80.0% for respiratory tract infections, 100% for urinary tract infections and 76.7% for all cases. There were no adverse reaction or changes in laboratory findings caused by CMZ in any of the patients.

Adolescent↗
PubMed1985

Identification of bile alcohols in human bile.

Human gallbladder bile was examined for bile alcohols. Following isolation and hydrolysis, the bile alcohols were analyzed by capillary gas-liquid chromatography-mass spectrometry. The following bile alcohols were identified with certainty by direct comparison with reference standards: 5 beta-cholane-3 alpha,-7 alpha,23,24-tetrol; 5 beta-cholane-3 alpha,7 alpha,12 alpha,24-tetrol; 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol; 27-nor-5 beta-cholest-25-ene-3 alpha,7 alpha,-12 alpha,24-tetrol; 3 alpha,7 alpha,12 alpha-trihydroxy-27-nor-5 beta-cholestan-24-one; 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol; 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25,26-hexol; 5 beta-cholestane-3 alpha,7 alpha,24-triol; 5 beta-cholestane-3 alpha,7 alpha,25-triol; 5 beta-cholestane-3 alpha,7 alpha,26-triol; 5 alpha-cholestane-3 alpha,7 alpha,12 alpha,24-tetrol; 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24-tetrol; 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol; 5 beta-cholestane-3 alpha,7 alpha,12 alpha,26-tetrol; (24R)- and (24S)-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentols; 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,26-pentol; 5 beta-cholestane-3 alpha,7 alpha,12 alpha,-25,26-pentol; 5 beta-cholestane-3 alpha,7 alpha,12 alpha,26,27-pentol; 26-methoxy-5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol. There also existed two norcholestanetetrols and three cholestanetetrols with two hydroxyl substituents on the nucleus and two in the side chain. The human biliary bile alcohols occurred mainly as sulfate esters and in lesser amounts as glucuronoconjugated and unconjugated forms. The amount of total bile alcohols was about 0.9 mg (0.7-1.2 mg) in 1 g of bile solid, or 0.16 mumol (0.07-0.24 mumol) in 1 ml of gallbladder bile.

Bile↗
PubMed1985

Damage in DNA irradiated with 1.2 MHz ultrasound and its effect on template activity of DNA for RNA synthesis.

When aqueous DNA solution was irradiated with 1.2 MHz continuous ultrasound in the presence of cysteamine, the number of ultrasound-induced double-strand breaks of DNA was not influenced, but the number of ultrasound-induced single-strand breaks of DNA was reduced to about one-fifth that of the irradiated control. When the effect of cysteamine on the template activity of the ultrasound-irradiated DNA was investigated, the cysteamine was found to exert a leveling effect on the linear decrease of the template activity against ultrasonic intensity. Since cysteamine was known as an effective radical scavenger, the results of the experiment were regarded to suggest that (1) the double-strand breaks were exclusively induced by the mechanical effect of ultrasound, (2) the majority of single-strand breaks were produced by water radicals arising from cavitation, (3) the initial part in the decrease of the template activity was due to the double-strand breaks arising from mechanical effect, and (4) the further decrease of the template activity depended mainly on the single-strand breaks arising from water radicals.

Cysteamine↗
PubMed1984

Sensitization of Escherichia coli B/r to X-irradiation by 2'-chloro-2'-deoxythymidine.

The sensitizing effect of 2'Cl-TdR has been investigated from the viewpoint of the formation of free radicals at the C-2' position of 2'Cl-TdR when reacted with hydrated electrons. E. coli B/r cells were incubated in growth medium containing 2'Cl-TdR. Centrifugation experiments using CsCl equilibrium density gradients were carried out to confirm the incorporation of 2'Cl-TdR into DNA of the cells. The sedimentation profiles of DNA from cells grown in a medium containing 2'Cl-TdR were found at relatively heavier density positions in comparison with those of DNA from control cells. This result confirms that 2'Cl-TdR was incorporated into DNA. E. coli B/r cells which incorporated 2'Cl-TdR were more sensitive than the control cells for killing by X-irradiation under aerobic conditions. On the other hand, no difference in U.V.-inactivation curves between the cells grown in growth medium containing 2'Cl-TdR and the control cells was observed. From experiments using alkaline sucrose density gradient centrifugation, an increase in the frequency of radiation-induced single strand breaks of E. coli DNA containing 2'Cl-TdR was observed, compared with those of DNA from control cells. These results reveal that the sensitization of 2'Cl-TdR originates from an increase of damage at the sugar moiety in DNA.

Cell Survival↗
PubMed1984

[Fundamental and clinical evaluation of ceftriaxone in the field of obstetrics and gynecology].

Ceftriaxone (Ro 13-9904, CTRX), a newly developed third-generation cephem antibiotic, reportedly has an antibacterial spectrum of wide-range and shows a much greater activity than cefazolin especially against Gram-negative bacteria and satisfactory effectiveness against anaerobes. In the gyneco-obstetric infections, the relation between the level in the intrapelvic organs and MIC is an important subject in many respects. The levels in the blood and each tissue determined in 54 cases, as presented in Fig. 2, show that a high concentration can be maintained for a long time. In particular the half-life time in the uterine artery and cubital vein was 8.2 hours and 7.8 hours, respectively, which was longer than that of any other existing antibiotics. This fact suggests that CTRX exhibits sufficient efficacy when administered intravenously even in a small dosage of 1 g in the present study. The clinical efficacy was good or above in all the 7 cases treated. There was neither clinical adverse reaction nor laboratory test abnormality found during and after the administration in any of the 54 cases in the fundamental study and 7 cases in the clinical study. It is suggested from the above-mentioned results that CTRX is an unprecedentedly useful antibiotic with an antibacterial spectrum of wide-range.

Adult↗
PubMed1984

[Clinical studies on cefoxitin in the treatment of respiratory tract infections].

The clinical effects of cefoxitin (CFX) were studied in 31 cases of respiratory tract infections. The results were as follows: As for the clinical effects, CFX was excellent in 5 cases, good in 13, fair in 8 and poor in 5 out of 31 patients; the efficacy rate was 58.1%. The efficacy rate was 57.1% in bronchopneumonia, 61.1% in pneumonia and 50.0% in acute exacerbation of chronic respiratory tract infections. The efficacy rate was 70.6% in the group of 4 g/day or less and 42.9% in the group of 6 g/day or more. The efficacy rate was 50.0% in 6 cases that had not been responded to other antibiotics previously. As for side effects, skin eruption was observed in only 1 patient. No abnormality was observed in laboratory tests due to CFX. In conclusion, CFX is a useful drug in the treatment of respiratory tract infections.

Adult↗
PubMed1984

[Total pelvic exenteration for primary and locally recurrent rectal cancer].

Thirteen patients with advanced carcinoma of the lower colon and no evidence of extrapelvic metastasis were submitted to total pelvic exenteration with urinary diversion. The operative mortality rate was 7.7%. Determinate 5-year survival rate of 40% was achieved. Local recurrence of rectal cancer following abdominoperineal resection is rarely amenable to limited resection. Six patients with deeply invading recurrent lesions had pelvic exenteration combined with sacral resection. This procedure seems a reasonable treatment for palliation and the chance of cure in selected patients. CT examination of the pelvis is very valuable for the early detection and localization of recurrence.

Adult↗