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Biomedical subjects

S Kitazawa

Publications and source records attributed to S Kitazawa.

At least 199 records · Page 11Linked to original sources
PubMed1982

The interaction of cephalosporin antibiotics with renal cortex of rats: accumulation to cortical slices and binding to purified plasma membranes.

The interaction of cephalosporin antibiotics with renal cortex of rats has been examined in vitro by means of cortical slice uptake and binding assay to plasma membranes and other subcellular fractions, including the comparative study with p-aminohippurate. The uptakes of cephalexin and cephaloridine by cortical slices were concentrative, and were strongly inhibited in the presence of 2,4-dinitrophenol, ouabain, nitrogen gas and probenecid. In the case of cefazolin, the degree of concentrative uptake and influence of inhibitors were low. Cephalexin, cephaloridine and p-aminohippurate specifically bound to the basolateral membranes, compared to brush border membranes and other subcellular fractions. Cefazolin binding to basolateral membranes was relatively small. These results suggest that the specificity of cephalexin and cephaloridine bindings to the basolateral membranes could be related to the interaction with the organic acid transport system at the antiluminal side. Thus, an examination of cephalosporin interaction with plasma membranes from renal cortex could offer an appropriate in vitro model system to study the renal transport of these antibiotics.

Animals↗
PubMed1982

[Parenteral administration of diphenylhydantoin in the pre- and post-operative course on plasma level measurement].

In the neurosurgical care, postoperative convulsion, the especially in the early postoperative course, is one of major complications because it can spoil an otherwise good surgical result. The present study was intended to investigate the prophylactic use of anticonvulsants on chemical measurement of their plasma levels. Parenteral diphenylhydantoin (DPH) given just before craniotomy failed to maintain high level of DPH in the postoperative course even with pretreatment of oral DPH. On the other hand, preoperative oral phenobarbital administration maintained fairly high level in spite of no prescription on the operative day. Intravenous DPH of 250 mg immediately after craniotomy resulted in fairly high level of DPH throughout the early postoperative course in cases of pretreatment of oral DPH. In reviewing the pharmacokinetics of anticonvulsants, the prophylactic use of anticonvulsants in the early postoperative course was discussed.

Adult↗
PubMed1981

A simple method for the isolation of basolateral plasma membrane vesicles from rat kidney cortex. Enzyme activities and some properties of glucose transport.

A procedure for preparing basolateral membrane vesicles from rat renal cortex was developed by differential centrifugation and Percoll density gradient centrifugation, and the uptake of D-[3H] glucose into these vesicles was studied by a rapid filtration technique. (Na+ + K+)-ATPase, the marker enzyme for basolateral membranes, was enriched 22-fold compared with that found in the homogenate. The rate of D-glucose uptake was almost unaffected by Na+ gradient (no overshoot).

Alkaline Phosphatase↗
PubMed1978

Stability and the biological activity of eel calcitonin in rats.

Hypocalcemic effect in rats of eel calcitonin was more persistent that that of porcine calcitonin and it was as persistent as that of salmon calcitonin I. Eel calcitonin was more stable than porcine or salmon calcitonin I when incubated in vitro with rat or human serum. Incubation in vitro with rat kidney or liver extract for 1 hour at 37 degrees C caused an almost complete inactivation of porcine calcitonin. On the other hand, both eel and salmon calcitonin I were inactivated less markedly and in the similar manner. The relationship between the hypocalcemic effect of calcitonins and the inactivation is discussed.

Animals↗
PubMed1977

Interpretation of dissolution rate data from in vitro testing of compressed tablets.

To find if theoretically and experimentally a relation existed between the dissolution rate theory of Kitazawa, Johno & others (1975) and that of Wagner (1969), a study was undertaken with uncoated caffeine, aspirin and proxyphylline tablets using two dissolution methods. Although the original treatment for surface area of drug available for dissolution was quite different between the two dissolution theories, the dissolution rate constants obtained were in fair agreement. Hence it might not be always necessary to take into consideration changes in the surface area as a function of dissolution rate, and the 1n W infinity/(W infinity) versus time plot devised by Kitazawa & others might be a useful and simple means of obtaining the dissolution rate constant of an active ingredient from a dosage form such as compressed tablet.

Aspirin↗
PubMed1977

A comparison of the dissolution rates of caffeine tablets in a rotating-basket with those in a Sartorius dissolution tester.

Uncoated caffeine tablets of four different hardnesses were tested for dissolution rate by the Sartorius (S.S. method) and by the rotating basket method of the U.S.P. XVIII. In both methods the dissolution rate decreased with increasing hardness, and the rate obtained with the S.S. method was always less than that by the U.S.P. method. This result cannot be explained as being due only to the difference in the volume of dissolution medium. Also it was difficult to ensure that the characteristic changes in the process of dissolution paralleled the curves obtained from a plot of % caffeine dissolved vs time. Accordingly, the dissolution rate constants were calculated from the slope of each straight line in a plot of ln W infinity/(W infinity --W) vs time.

Caffeine↗