Search PubMed⌕ Search

Biomedical subjects

T Yajima

Publications and source records attributed to T Yajima.

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

Developmental changes in the activities of prolinase and prolidase in rat salivary glands, and the effect of thyroxine administration.

As the salivary glands are interesting tissues to study proliferation, we studied the activities of prolinase and prolidase using Pro-Ala and Pro-Hyp as substrates, respectively, in developing rat salivary glands between day 1 and week 10 after birth. Developmental changes of prolinase activity in the submandibular and sublingual glands were similar to those in the parotid gland, which steadily increased and reached the adult level by 20-25 days after birth. However, the changes in the activity of prolidase in the submandibular and sublingual glands were different from those in the parotid gland: the activity in the parotid gland slowly increased with maturation and reached a maximum level on day 30, but the activity in the submandibular and sublingual glands continuously increased with maturation. When thyroxine was injected every two days from day 1 to day 19, both enzyme activities were induced precociously in the parotid gland but not in the submandibular and sublingual glands. On the study of regional distribution in rat tissues, the correlation coefficient between prolinase and prolidase activities was high in the peripheral but not high in the brain regions. These results indicate that the physiological roles of prolinase and prolidase are very similar but not the same.

Aging↗
PubMed1982

Ontogenesis of monoamine-synthesizing enzyme activities and biopterin levels in rat brain or salivary glands, and the effects of thyroxine administration.

Neonatal changes in the activities of tyrosine hydroxylase (TH) and tryptophan hydroxylase (TrpH) and in the content of the co-factor, biopterin, were studied in rat midbrain for the first 20 days after birth. Changes in TH activity in the parotid and submandibular glands were also examined. Changes in TH activity per unit weight in the developing rat brain were briefly similar to those in the salivary glands; the activity increased from day 2 or 4 to day 9 after birth, and remained constant or slightly decreased at day 12, then rapidly increased on day 16. TrpH activity in the midbrain increased about twofold up to day 16. The biopterin concentration in the brain increased, reached a maximum level on day 12 after birth, and thereafter decreased. The effect of hyperthyroidism in rats given 0.2 mg/kg i.p. of thyroxine every 2 days postnatally was studied on the activity of TH in rat salivary glands at 12-day-old rats. In parotid or submandibular gland of hyperthyroid rats, TH activity increased at day 12 postnatally. In comparison with the effect on TH activity in the salivary glands, TH activity in the midbrain on day 20 postnatally was not induced by hyperthyroidism. Furthermore, increase of the TrpH activity and biopterin and catecholamine levels in the midbrain of hyperthyroid rats was not found on day 20 after birth in comparison with the corresponding controls. From these data, we suppose that postnatal hyperthyroidism may cause precocious induction of TH in rat salivary gland, but may not increase the activity of TH or TrpH, and the level of their co-factor, biopterin, in rat midbrain.

Aging↗
PubMed1982

Effect of epidermal growth factor on collagen formation in liver-derived epithelial clone cells.

Biochemical and morphological studies were made on the effect of epidermal growth factor (EGF), isolated from male mouse submandibular gland, on collagen formation in clone RLC-18(4) epithelial cells from rat liver. EGF did not affect the number of these cells. EGF in the range of 0.5-500 ng/ml caused a dose-dependent increase in the content of hydroxyproline. It also increased the content of acidic glycosaminoglycans (AGAG), which are thought to be closely related to the formation of collagen fibers, and increased the activity of glutamine glucose-6-phosphate aminotransferase, an enzyme for AGAG synthesis but not that of N-acetyl-beta-glucosaminidase, an enzyme for AGAG degradation. It has no significant effect on the protein content of the cells. Studies on the effect of actinomycin D indicated that EGF may enhance de novo synthesis of hydroxyproline in liver epithelial cells and also that of glutamine glucose-6-phosphate aminotransferase, thus increasing the AGAG content of the cells. Antibody to EGF largely blocked collagen formation in the cells, even in the absence of EGF, indicating that EGF or EGF-like substances in the serum may affect collagen formation. In rat liver fibroblasts, EGF had little effect on collagen formation. These results show that EGF may act as a regulatory factor in collagen formation in liver epithelial cells, but not liver mesenchymal cells, in vitro.

Animals↗
PubMed1982

Effect of epidermal growth factor on collagen synthesis in osteoblastic cells derived from newborn mouse calvaria.

We investigated the effect of epidermal growth factor (EGF) on collagen and protein synthesis in clone MC3T30-E1, a cell line which retains osteoblast-like characteristics. EGF at concentrations of 2-50 ng/ml significantly the hydroxyproline content of the cell layer. These effects were completely abolished by the addition of anti-EGF rabbit serum. The addition of indomethacin did not affect these EGF-induced effects. Collagen fiber formation was also reduced by EGF; a fine and unstriated type of fibril was detected compared to the typical cross-striated fibrils seen in control cultures. EGF at concentrations of 2-50 ng/ml significantly decreased collagen synthesis in the cells, whereas protein synthesis was rather stimulated. Thus, the proportion of collagen to protein synthesized decreased markedly with increasing concentrations of EGF. Unrelated to its effect on collagen synthesis, EGF at concentrations of 0.4-50 ng/ml significantly increased the activity of prolyl hydroxylase, an enzyme involved in the biosynthesis of collagen. Since the plasma concentration of EGF in humans is sufficiently high to cause the observed effect, osteoblasts in vivo may be responsive to this peptide in the same manner as those observed in vitro.

Animals↗
PubMed1981

[In vitro studies on the activities of cephalothin against selected bacteria (author's transl)].

Cephalothin antimicrobial activities were studied against selected bacteria with special reference to the time of exposure of microbes to the drug assessed in broth medium. The minimal concentration of this drug producing 10(0)-10(1) reduction of colony forming unit (CFU) per ml after given exposure times -an approximation to the theoretical bacteriostatic concentration inhibiting increase or decrease of CFU- was designated as minimally reducing concentration (MRC). The concentration was determined after 6 h, 18 h and 42 h of incubation and designated as 6-h, 18-h and 42-h MRC, respectively. Conventional minimal inhibitory concentration (MIC) with 18 h exposure time was also studied. The minimal concentration of the drug yielding 99.9% reduction of CFU after an exposure to the drug was determined and designated as minimal lethal concentration (MLC). The determinations were made at 6 h, 18 h and 42 h of incubation and designated as 6-h, 18-h and 42-h MLC, respectively. The data indicated that the bacteriostatic concentration for Escherichia coli and Klebsiella sp. with brief exposure time (6-h MRC) was 2-4 times lower than the MIC. If the exposure time was prolonged (18-42 h), the bacteriostatic concentration increased and almost agreed with the MIC. A significant effect of inoculum size was observed on the MRC values for the Gram-negatives when the values were determined with the inoculum concentrations at 10(6)-10(7) CFU/ml and 10(3)-10(4) CFU/ml. In contrast to these Gram-negatives, the 6-h MRC for most strains of Staphylococcus aureus and Enterococcus roughly agreed with the MIC. If the ratio of bacteriostatic to bactericidal concentrations was used as the criterion, the mode of action of cephalothin appeared to be bactericidal for most of the Gram-negatives. This drug was bacteriostatic for a number of the Gram-positive strains, in particular to those of Enterococcus, especially when microbes were exposed to the drug over a brief period of time.

Bacteria↗
PubMed1980

Analysis of serum iron by gel permeation high-performance liquid chromatography.

A high-performance liquid chromatographic procedure for the determination of serum iron is reported. Serum iron extracted with methyl isobutyl ketone was converted to dibenzoylmethane chelate (molecular weight 725), and it was separated from excess dibenzoylmethane (molecular weight 224) by gel permeation chromatography. The chelate was determined by measuring ultraviolet absorption at 280 nm. Good reproducibility, recovery, and correlation with the conventional colorimetric method were observed.

Chromatography, High Pressure Liquid↗
PubMed1980

Characterization of acetate uptake by the colonic epithelial cells of the rat.

The characteristics of acetate uptake by colonic epithelial cells of the rat were studied. Clear saturation kinetics of acetate uptake were not observed in these experiments at either 0 degrees C or 30 degrees C. A decrease in the pH of the medium markedly increased the acetate uptake. The activation energy for acetate uptake derived from an Arrhenius plot was about 6.1 kcal/mole. Among the inhibitors tested, no effective inhibition of acetate uptake at 0 degrees C was observed. Metabolic inhibitors severely inhibited transport at 30 degrees C. Inhibition of acetate uptake by other short chain fatty acids, which was non-competitive, was observed. The finding that efflux from the cells was stimulated in the presence of compounds such as pyruvate and bicarbonate supported the notion of a close interrelationship between weak electrolyte transports in vivo. Although the H+ gradient across the cell membrane is suggested to be one of the factors determining the uptake rate, it seems difficult to explain all the results in this way.

Absorption↗
PubMed1980

Bacteriostatic and bactericidal activities of beta-lactam antibiotics enhanced by the addition of low concentrations of gentamicin.

The combined effects of low concentrations of gentamicin on certain beta-lactam antibiotics were studied by the agar plate method. the combination of gentamicin with cephalothin produced synergism against 17 of 26 strains of Escherichia coli and 19 of 27 strains of Klebsiella sp. if assessed at the bacteriostatic (minimal inhibitory concentration) level. Synergy against many more strains was apparent when bactericidal concentrations were used. Synergy against most of these strains was observed if bactericidal concentrations with brief exposure times (3 h) to the antibiotics were used for measurement. Additive effects were observed in almost all of the remaining strains. The combination of gentamicin and carbenicillin were synergistic against most strains of Pseudomonas aeruginosa when any bacteriostatic or bactericidal measurement was used as the criterion.

Bacteria↗