Biomedical subjects

T Horio

Publications and source records attributed to T Horio.

386 records · Page 22Linked to original sources

PubMedDate not supplied

Activity of nadifloxacin against methicillin-resistant Staphylococcus aureus isolated from skin infections: comparative study with seven other fluoroquinolones.

The in vitro susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) to nadifloxacin and seven other fluoroquinolones (norfloxacin, ofloxacin, enoxacin, ciprofloxacin, lomefloxacin, tosufloxacin and sparfloxacin) was evaluated. The MRSA isolates were isolated from 114 skin infections between 1991 and 1994. Nadifloxacin exhibited the lowest minimum inhibitory concentration and there were no MRSA isolates resistant to nadifloxacin, while there were some resistant to all of the other seven fluoroquinolones. The minimum concentrations of these drugs needed to cause 50% inhibition of the isolates increased dramatically from 1991 to 1992, but has hardly changed since 1992.

Anti-Infective Agents↗

PubMedDate not supplied

Enhanced effect of clarithromycin on neutrophil function in vitro.

An in vitro study was carried out to investigate the effect of clarithromycin, a new oral macrolide, on neutrophil reactive oxygen species generation and chemotaxis. It was found that neutrophil-generated O2-, H2O2 and OH. levels were significantly increased by clarithromycin at concentrations of 50 micrograms/ml (P < 0.05). The drug also significantly increased chemotaxis (P < 0.05). These results indicate that clarithromycin may enhance the activation of neutrophils in vivo.

Anti-Bacterial Agents↗

PubMedDate not supplied

Effect of pyridone carboxylic acid anti-microbials on the generation of reactive oxygen species in vitro.

The effects of ofloxacin, ciprofloxacin and balofloxacin on the reactive oxygen species (ROS) levels generated by human neutrophils was examined in vitro; ROS generated in a cell-free, xanthine-xanthine oxidase system was also assessed. The species investigated were superoxide radical anion (O2-), hydrogen peroxide (H2O2) and hydroxyl radical (OH*). Both ofloxacin and ciprofloxacin markedly decreased the levels of O2-, H2O2 and OH* generated by human neutrophils. On the other hand, these drugs did not affect any of the ROS examined in the xanthine-xanthine oxidase system. Balofloxacin showed no significant effect on ROS generated by either system. The present study indicates that ofloxacin and ciprofloxacin may exert an anti-inflammatory action by reducing the potent ROS species excessively generated by neutrophils at the sites of inflammation.

Anti-Infective Agents↗

PubMedDate not supplied

Effect of keigai-rengyo-to, a Japanese kampo medicine, on neutrophil functions: a possible mechanism of action of keigai-rengyo-to in acne.

On the basis of recent reports that keigai-rengyo-to (TJ-50), an oral Japanese Kampo (herb) medicine, is clinically effective in treating acne, and that tetracyclines are effective against acne by acting directly as an antioxidant on infiltrated neutrophils, we investigated the effect of TJ-50 on the generation of reactive oxygen species (ROS), using human neutrophils and a cell-free, xanthine-xanthine oxidase system. The species investigated were superoxide radical anion (O2-), hydrogen peroxide (H2O2), and hydroxyl radical (OH.). In addition, neutrophil chemotaxis, phagocytosis and calcium concentration, [Ca2+]i in neutrophils were also assessed. TJ-50 significantly decreased neutrophil-generated O2-, H2O2 and OH. in a dose-dependent manner. Three kinds of ROS generated in the cell-free system were also reduced in the presence of TJ-50. On the other hand, the medicine did not markedly affect neutrophil chemotaxis, phagocytosis or [Ca2+]i in neutrophils. Our results indicate that the clinical effectiveness of TJ-50 in the treatment of acne may be due partly to its antioxidant action on infiltrated neutrophils.

Acne Vulgaris↗

PubMedDate not supplied

Effects of roxithromycin on adhesion molecules expressed on endothelial cells of the dermal microvasculature.

The objective of the study was to investigate the pharmacological action of roxithromycin, an oral macrolide antibiotic. The effects of roxithromycin on the cytokine-induced expression of endothelial leukocyte adhesion molecule (E-selectin) and intracellular adhesion molecule (ICAM)-1 on endothelial cells of the dermal microvasculature were investigated in vitro using flow cytometry. Roxithromycin at a concentration of 0.5 microgram/ml, which is lower than the therapeutic plasma concentration (ordinary daily dose, 150-300 mg), significantly inhibited the expression of E-selectin and ICAM-1 on endothelial cells of the dermal microvasculature induced by tumour necrosis factor-alpha. We conclude that roxithromycin may exert its anti-inflammatory action by inhibition of the in vivo expression of adhesion molecules on dermal microvascular endothelial cells.

Anti-Bacterial Agents↗

PubMedDate not supplied

Concentration of roxithromycin in the lesions of acne vulgaris.

Roxithromycin, a macrolide antibiotic, is used in the treatment of acne vulgaris, although there have been no reports on its concentration in lesions when administered orally. We investigated the concentration of roxithromycin in acne vulgaris lesions in five patients who received 150 mg roxithromycin orally twice daily for 2 weeks. The mean concentration of roxithromycin in the lesions was 0.54 microgram/ml. These results suggest that roxithromycin accumulates at therapeutic levels in the pilosebaceous system.

Acne Vulgaris↗

PubMedDate not supplied

The effect of ultraviolet radiation on the water-reservoir functions of the stratum corneum.

The stratum corneum plays an important role in keeping the skin surface supple and flexible. After exposure to sunlight, the skin may become dry and scaly. In the present study, the water content, hygroscopicity and water-holding capacity of the stratum corneum were examined after ultraviolet B (UVB) exposure to the guinea pig skin. Manually depilated back skin was exposed once to 1, 2 and 3 times the minimal erythema dose of UVB, and a time course study was performed. Our study demonstrated the following: The water content, water-holding capacity and hygroscopicity decreased after UVB irradiation. They decreased roughly dependent on UVB dose. The decreased water content and water-holding capacity were noted on day 1 and persisted until day 10 to 14. In contrast, the decrease in hygroscopicity became apparent 3 days after exposure and returned to the preirradiated state on day 7. The impaired functional parameters were partially prevented by topical application of a sunscreen. These results indicate that a single exposure to UVB can damage the function of the stratum corneum.

Absorption↗

PubMedDate not supplied

Rotation-induced Taylor vortex enhances filtrate flux in plasma separation.

Techniques of plasma filtration with rotating flat membranes are capable of producing a Taylor vortex and concomitantly reducing concentration polarization by formed elements. The present study describes filtration characteristics of a small-sized rotating filter that is superior to a capillary filter in terms of filtrate flux. The rotating filter with a surface area of 60 cm2 was composed of two concentric cylinders, with the inner cylinder mobile, with a flat polycarbonate membrane (pore diameter: 0.8 micron), and the outer cylinder fixed. Filtration experiments were performed using bovine blood to determine filtrate flux at rotational speeds from 600 to 4,500 rpm. Photographic observations using aluminum powder revealed that many Taylor vortices were present in the radial gap (0.6 mm). Filtrate flux increased with transmembrane pressure until a maximum filtrate flux of 0.02 cm/min at 600 rpm, 0.42 cm/min at 1,800 rpm, 0.60 cm/min at 3,600 rpm, and 0.69 cm/min at 4,500 rpm were reached at a blood flow rate of 100 ml/min. Based on the filtration resistance model, values for fractional filtration resistance of the red blood cell polarization layer ranged from 0.25 to 0.80 at a rotational speed of 3,600 rpm, whereas those of a capillary filter range from 0.80 to 0.90. This indicates that Taylor vortices promote back diffusion of red blood cells accumulated on membrane surfaces. Thus, the filtrate flux of a rotating filter is two orders of magnitude higher than that of a capillary filter because of the back diffusion of red blood cells facilitated by Taylor vortices.

Animals↗