Fumiko Hirata

Effect of short physical exercise on the levels of zinc and carbonic anhydrase isoenzyme activities in human erythrocytes

SummaryStudies of the influences of physical exercise of short duration (bicycle ergometer, 200 W for 30 min) on the activities of carbonic anhydrase isoenzymes (CA-B and CA-C types) and zinc concentration in erythrocytes were made on 5 untrained healthy male volunteers. The subjects were rested for 30 min after the exercise. There were significant decreases in the levels of zinc, CA-B, total carbonic anhydrase activity and CA-B-dependent activity immediately after exercise, but after 30 min of rest they all returned to their pre-exercise levels. No significant change in CA-C level or CA-C-dependent activity was found after exercise. Immediately after exercise, total carbonic anhydrase activity and CA-B-dependent activity following the addition of Zn2+ showed significant increases, compared with their respective activities without Zn2+ addition. However, no such effects were observed just before exercise or after rest; the addition of Zn2+ had no effect on CA-C-dependent activity at any time. A significant correlation was found between the changes in concentration of zinc and CA-B-dependent activity after exercise (r=0.711). The findings of the present study suggest that active CA-B enzymes are converted in part to inactive enzymes during acute physical exercise, possibly by decreased zinc binding. Moreover, the change in CA-B-dependent activity correlated well with the changes in pH and HCO3 concentrations in venous blood (r=0.853 and r=0.718, respectively). One may speculate that an adaptive decrease in CA-B-dependent activity in erythrocytes occurs with increased acidification in blood during heavy physical exercise of short duration.

Studies on bacterial aerosol. Part 10. Species classification and antibiotic susceptibility of airborne staphylococci in hospital

A new scheme for species-classification of staphylococci was applied to 124 strains of airborne staphylococci (A. S.) isolated from the air in hospital wards. For comparison, 204 strains of A. S. dispersed from healthy subjects and 521 strains of staphylococci isolated from their skin were also classified. In addition, both strains of A. S. in hospital wards and from the healthy subjects were tested for susceptibility to 11 major antibiotics (penicillin G, methicillin, cloxacillin, ampicillin, cephaloridine, erythromycin, chloramphenicol, streptomycin, tetracycline, kanamycin and gentamycin).The results obtained were as follows:1. One of the 124 strains of A. S. from the hospital wards was identified as Staphylococcus aureus (S. aureus). The remaining 123 strains of coagulase-negative staphylococci (CNS) were classified into S. epidermidis (35.5%), S. haemolyticus (11.3%) and other species, except for 41 strains (33.1%) which were not classified. Most of the staphylococcal strains isolated from the healthy human skin were identified as S. epidermidis (82.0%). On the other hand, a large number of unclassifiable strains (76.5%) were observed in A. S. from the healthy subjects.2. The airborne CNS strains from the hospital wards showed marked differences in minimal inhibitory concentration (MIC) for all antibiotics tested when compared to those from the healthy subjects. Particularly, half of them were resistant to penicillin G, methicillin, ampicillin and kanamycin. Similarly, the rate of airborne CNS strains in hospital wards was much higher for multi-drug resistance than those from the healthy subjects.The results suggest that some airborne CNS in hospital wards may act as opportunistic pathogens.