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Biomedical subjects

H Koga

Publications and source records attributed to H Koga.

At least 379 records · Page 21Linked to original sources
PubMed1987

High-performance liquid chromatography measurement of antimicrobial concentrations in polymorphonuclear leukocytes.

High-performance liquid chromatography was used to determine the penetration of 19 antimicrobial agents into human polymorphonuclear leukocytes. The ratios of the intracellular concentration to the extracellular concentration of ampicillin, piperacillin, cefazolin, ceftizoxime, cefpimizole, and ceftazidime were all less than 0.6. Lincomycin showed a high intracellular-to-extracellular ratio (3.0), while clindamycin achieved a ratio of 15.5, which was the highest ratio of all of the 19 tested antibiotics. Ratios for rifampin, isoniazid, chloramphenicol, and trimethoprim were 8.2, 1.1, 9.6, and 6.1, respectively. Six quinolone-class antimicrobial agents had ratios from 2.2 to 8.2. Flucytosine showed a penetration ratio of 4.6. Clindamycin uptake was temperature dependent and occurred best with live polymorphonuclear leukocytes; sodium fluoride, adenosine, and puromycin were inhibitory. The results obtained in this study correlate well with the results of other studies involving radioisotopic methods. This indicates that high-performance liquid chromatography is a useful method for determining the intracellular penetration of antimicrobial agents.

Adenosine↗
PubMed1987

Multimodal responses of preoptic and anterior hypothalamic neurons to thermal and nonthermal homeostatic parameters.

The hypothesis that thermosensitive neurons in the preoptic anterior hypothalamic nuclei (POAH) have a principal role in central thermoregulation is based on numerous findings, suggesting correlations between the activity of thermosensitive neurons and thermoregulatory responses. Such relationships have been observed during thermal (local and peripheral) and pharmacological stimulation, during modulation of neural inputs from extra-POAH brain regions, and during actual thermoregulatory responses. Recent studies using in vitro slice preparations and conscious animals have revealed that 40-70% of POAH thermosensitive neurons respond to nonthermal homeostatic parameters such as local osmolality, blood pressure, and nonthermal emotional stimuli. About two-thirds of the POAH thermosensitive neurons, which responded in monkeys during bar press thermoregulatory tasks, changed their activity during bar press feeding behavior. A high degree of convergence of thermal and nonthermal homeostatic signals on the POAH neurons, together with abundant neural connections between the POAH and divergent areas of the brain, suggests that POAH thermosensitive neurons may be involved in the coordination of thermoregulation and nonthermal autonomic and behavioral responses controlled from the hypothalamus.

Angiotensin II↗
PubMed1986

The antimicrobial activity of ciprofloxacin against Legionella species and the treatment of experimental Legionella pneumonia in guinea pigs.

The antimicrobial activity of ciprofloxacin was tested against 15 standard reference strains, and 37 clinical and environmental strains of Legionella pneumophila by an agar dilution method, using a new growth medium (B-SYE agar) which we devised. The minimal inhibitory concentrations of ciprofloxacin were found to be inoculum dependent, and ranged from 0.02 to 0.06 mg/l at 10(4) cfu inoculum and 0.02 by 0.125 mg/l at 10(6) cfu inoculum. The most potent antibacterial activity was shown by rifampicin, followed by ofloxacin, ciprofloxacin, enoxacin, norfloxacin, erythromycin and pipemidic acid in that order. The therapeutic efficacy of ciprofloxacin in experimental guinea pig pneumonia due to L. pneumophila was fairly good with a survival rate of 80%. From other data of ours, its effectiveness in experimental pneumonia was equal to or greater than that of erythromycin. Further studies would be appropriate to investigate the possibility of using ciprofloxacin for the treatment of human L. pneumophila infection.

Animals↗