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Biomedical subjects

H Fujioka

Publications and source records attributed to H Fujioka.

At least 379 records · Page 21Linked to original sources
PubMed1982

Biopharmaceutical studies on hydantoin derivatives. III. Physico-chemical properties, dissolution behavior, and bioavailability of the molecular compound of 1-benzenesulfonyl-5,5-diphenylhydantoin and antipyrine.

Physico-chemical properties, dissolution profiles, and bioavailability of the molecular compound composed of equimolar amount of 1-benzenesulfonyl-5, 5-diphenylhydantoin (BSDH) and antipyrine were studied. The spectral and thermal analyses suggest that the intermolecular force in the molecular compound is attributed to the hydrogen bond between 3-NH of BSDH and 5-C = 0 of antipyrine. In the aqueous media, the molecular compound decomposed to the constituents and there was no interaction between them. The dissolution behavior of BSDH from the molecular compound was characteristic, the high supersaturation being present for a long time, while the dissolution of antipyrine from the molecular compound was slow and continued for a long time. The dissolution profile of the molecular compound was truly reflected on the bioavailability in dogs. With respect to BSDH, the rate and the extent of bioavailability of the molecular compound were excellent. On the other hand, the absorption of antipyrine from the molecular compound was sustained for a long time. BSDH and antipyrine had no influence one another on the intrinsic rate constant of transport through the intestinal membrane and on the pharmacokinetic constants such as the volume of distribution and the elimination rate constant.

Administration, Oral↗
PubMed1982

Dorsal column stimulation in man: facilitation of primary afferent depolarization.

The effects of cervical epidural dorsal column stimulation on the negative and slow positive waves of the spinal cord potentials recorded from the posterior epidural space at the lumbar enlargement, in response to intense stimulation of the tibial nerve in five neurologically normal subjects during neuroleptanesthesia were studied. Single pulses applied to the cervical dorsal cord near the midline produced slow positive potentials preceded by negative waves in the dorsal spinal cord at the level of the lumbar enlargement. The negative wave, believed to represent synchronized activities of interneurons, was inhibited up to 100 to 120 msec by conditioning dorsal column stimulation. The slow positive wave, though to represent primary afferent depolarization, was facilitated for more than 100 msec with transient inhibitor for 10 to 40 msec. The results suggest that the pain-alleviating effect of dorsal column stimulation in man may be at least partly due to orthodromic and/or antidromic activation of descending inhibitory pathways which inhibit the responsible cells and facilitate primary afferent depolarization.

Adolescent↗
PubMed1981

Biopharmaceutical studies on hydantoin derivatives. I. Physico-chemical properties of hydantoin derivatives and their intestinal absorption.

The physico-chemical properties of a series of hydantoin derivatives and their intestinal absorption from solution were studied. The introduction of the benzenesulfonyl group at the 1-position of the hydantoin ring greatly affects the physico-chemical properties: the acid dissociation constants were increased 1000-fold and the partition coefficients were increased 100- to 1000-fold in the chloroform/water system and 10- to 100-fold in the n-octanol/water system. The solubilities of 1-benzenesulfonylhydantoin derivatives increased with increasing pH of the solution at pH more than 5, but the solubilities of the 1- unsubstituted hydantoin derivatives were scarcely dependent on the pH of the solution in the pH 1 to 8 region. The intestinal absorption from solution was found to be caused by the passive transport according to the first-order kinetics. The rate constants of absorption of 1-benzenesulfonylhydantoin derivatives were rather large even under the condition where they were 99% ionized in the solution than that of the corresponding 1-unsubstituted hydantoin derivatives which exist mainly as the unionized from under the same condition. The intestinal absorption from a solution and the partitioning to chloroform produced linear free energy relationships to each other for the 1-benzenesulfonylhydatoin derivatives and for the 1-unsubstituted hydantoin derivatives independently. However when the partition coefficients in the n-octanol/water system were applied, the hydroxyl derivatives were found to deviate from linear relationships. On the basis of the results, a suggestion was made on the in vivo behavior and the bioavailability.

Animals↗
PubMedDate not supplied

Heat shock cellular stress on aged gut-associated lymphocytes; mRNA expression of inducible heat shock protein gene and protooncogenes.

To investigate the effects of senescence and cellular stress on gut mucosal lymphocytes, we used heat shock (HS) to determine the mRNA expression of an inducible HSP70-family gene (HSP68) and two nuclear protooncogenes (c-fos and c-myc) from gut-associated (GA) lymphocytes of aged (> or = 24 month) and young (3-4 month) mice. First, with temperatures of 37-44 degrees C, the maximal HS effect on expression of inducible HSP68 mRNA was at 41 degrees C, and that of c-fos and c-myc at 42 degrees C; with HS durations of 0-6 h at 42 degrees C, the maximal effect was at 1 or 2 h in the young GA lymphocytes. Second, without HS (37 degrees C), inducible HSP68 mRNA was not expressed in the GA lymphocytes of both age groups. The expression of c-fos and c-myc mRNA was greater in the aged GA lymphocytes than in the young, and c-myc mRNA was more highly expressed than c-fos mRNA in both age groups. Third, with HS (42 degrees C) for 30 min to 6 h, followed by recovery (37 degrees C) for up to 6 h, the peak expression of inducible HSP68 mRNA in the aged GA lymphocytes was reduced, but occurred at the same time as seen in the young (2 h) and declined faster during the recovery period. The peak expression of c-fos mRNA in the aged GA lymphocytes was earlier than that of the HSP68 mRNA in both age groups (1 h); the intensity of expression was decreased at all time points in the aged and declined more rapidly during the recovery period, whereas the peak expression of c-myc mRNA in the aged GA lymphocytes after HS was retarded in time (2 h) but also reduced in amount, when compared to that of the young, and during recovery the expression declined more rapidly in the aged than in the young. However, the recovery kinetics of the above three mRNAs remained unaltered in the lymphocytes from two different ages. To summarize our conclusions: First, prior to HS cellular stress, aged GA lymphocytes did not show mRNA expression of HSP68 but augmented mRNA expression of the nucleoprotooncogenes c-fos and c-myc. These findings suggest that senescent lymphocytes are more active metabolically in vivo than are young ones without significant activation of an inducible HSP70 family gene.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMedDate not supplied

Chondroitin-4-sulphate (proteoglycan), a receptor for Plasmodium falciparum-infected erythrocyte adherence on brain microvascular endothelial cells.

Adherence of Plasmodium falciparum parasitized erythrocytes to the microvascular endothelium is mediated by different receptors expressed by endothelial cells. The study of the adherence of P. falciparum-infected erythrocytes to Saimiri monkey brain microvascular endothelial cells revealed the presence of an additional receptor, which was identified and further characterized. This receptor was also found on the surface of primary human lung endothelial cells (HLEC). We developed two mAbs to this receptor which very efficiently blocked the adherence of parasite strains to Saimiri brain endothelial cells (SBEC). The ability of these mAb to bind to SBEC was partially blocked by chondroitin-4-sulphate (CSA). Competitive inhibition assays on adherence of parasitized red blood cells (PRBC) showed that CSA, but not hyaluronic acid, chondroitin-6-sulphate, dermatan sulphate, keratane sulphate, heparan sulphate or chondroitin-4S-disaccharide, was able to almost completely inhibit PRBC adherence. The same effect was obtained with chondroitinase ABC and AC, but not B, hyaluronidase or heparinase. These results strongly suggest that a member of the chondroitin-glycosaminoglycan family, CSA, represents an additional receptor used by P. falciparum PRBC to cytoadhere to microvascular endothelial cells.

Animals↗