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Biomedical subjects

T Yajima

Publications and source records attributed to T Yajima.

At least 217 records · Page 12Linked to original sources
PubMed1980

Permissive role of L-thyroxine in induction of pancreatic amylase by cortisol in neonatal rats.

The effect of L-thyroxine (T4) on amylase activity in the developing rat pancreas has been investigated. Administration of T4 (0.2 microgram/g body wt) alone to intact rats on days 5-10 after birth did not induce pancreatic amylase but the enzyme was induced significantly by daily injection of cortisol (10 microgram/g body wt) alone into intact rats over the same period. In thyroidectomized, adrenalectomized rats pancreatic amylase was not induced by the injection of cortisol alone but it was induced by the administration of cortisol plus T4. Increase in enzyme activity was much less in thyroidectomized animals than in intact animals. These results suggested that T4 does not have a direct effect in increasing pancreatic amylase activity but plays a permissive role in increasing enzyme activity.

Adrenalectomy↗
PubMed1980

L-Thyroxine, cortisol and diet affect the level of amylase in the parotid gland of developing rats.

The effects of cortisol (10 microgram/g body weight) and L-thyroxine (T4; 0.2 microgram/g body weight) on the activity of parotid gland amylase in young rats were investigated. Administration of cortisol or T4 for 5 consecutive days from day 5 after birth caused the precocious appearance of amylase, T4 having almost twice the effect of cortisol. Cortisol and T4 did not have synergistic effects. In thyroidectomized-adrenalectomized rats, T4 increased amylase activity but cortisol did not. The increase in enzyme activity after day 20 was much less in rats thyroidectomized on day 10 than in rats adrenalectomized on day 10. These results suggest that T4 has a direct effect on the early increase of amylase activity (days 15-25) and that the action of glucocorticoid requires the presence of endogenous thyroid hormones. The hormone-induced level of amylase in intact rats was less than that of normal adult rats. Forced weaning of intact rats resulted in a further increase in amylase activity, suggesting that further amylase accumulation (after day 25) may be due to dietary factors.

Adrenalectomy↗
PubMed1980

Permissive role of L-thyroxine in the induction of stomach pepsinogen by cortisol in neonatal rats.

Subcutaneous injection of cortisol (10 micrograms/g body wt daily for 5 days) into normal neonatal rats increased the activity of stomach pepsinogen after day 5. L-Thyroxine (T4; 0.2 microgram/g body wt daily for 5 days) alone did not affect the activity but it somewhat enhanced the effect of cortisol. Even before day 5, when no effect of cortisol alone was observed, T4 plus cortisol increased pepsinogen activity. In adrenalectomized, thyroidectomized neonatal rats, injection of cortisol alone did not induce enzyme activity but cortisol together with T4 did induce it. Moreover, the increase in pepsinogen activity was depressed in rats thyroidectomized on day 10 but not in those thyroidectomized on day 15. These results suggest that T4 does not have a direct effect on the stomach but plays an important role in making the stomach responsive to glucocorticoids, resulting in increased pepsinogen activity.

Adrenalectomy↗
PubMed1980

Serum ferritin concentration and isoferrtin patterns detected by immunoradiometric assay.

Two-site immunoradiometric assay for serum ferritin was developed by anti-human liver ferritin antiserum applied on polyvinyl V-bottom microtiter plates. The coefficient of variation was 4.4-5.9% of liver ferritin dissolved in 1/4 diluted human serum at a concentration of 0.625-125 ng/ml. The lowest concentration (0.625 ng/ml) was statistically distinguishable from the background by Student's t test (p < 0.05). Isoferritin patterns of serum ferritin and tissue ferritins were examined by the combination of gel isoelectric focussing and 2-site immunoradiometric assay in order to explore any similarities in pIs within these ferritins. Although serum ferritin had wide range of pIs, its basic isomers corresponded well to those of liver and spleen ferritin. Geometric means and their 95% confidence limits in serum ferritin concentration were 70 ng/ml and 12-411 ng/ml, respectively, in sera of 205 healthy males (16-25 years), and 12 ng/ml and 1-211 ng/ml, respectively, in 421 healthy females (16-59 years).

Adolescent↗
PubMed1979

Effect of organic acid absorption on bicarbonate transport in rat colon.

The absorption of organic anions and the influence of these anions on the movement of HCO3- were studied in vivo in rat colon using a perfusion technique. The absorption of short chain fatty acids (SCFA's) such as acetate, propionate, and butyrate was much greater than that of succinate or lactate. With increasing initial concentration of SCFA up to 100 mmol . 1-1, SCFA absorption increased linearly in correspondence with HCO3- appearance. Final pCO2 level of the perfusion solution with SCFA was the same as the plasma level. Among the SCFA's, no significant differences in absorption or their effects on HCO3- appearance were observed. The presence of Na+ stimulated SCFA absorption, and the maximum value was obtained at more than 100 mmol . 1-1 of Na+. These results suggest that a specific system for HCO3- secretion activated by SCFA exists in the colon, and that this system may control the intraluminal pH by the alkalization of intestinal contents.

Acetates↗
PubMed1979

Determination of 6-methyladenine in DNA by high-performance liquid chromatography.

A method for the determination of 6-methyladenine (6MA) by high-performance liquid chromatography (HPLC) has been developed. DNA bases were separated by using the strong cation-exchange resin Zipax SCX. Purine bases were obtained by hydrolysis and dialysis of DNA and analysed by HPLC. 6MA in DNA from Escherichia coli was determined by the proposed method. It is suggested that the method could be applicable to analyses of 6MA from other biological sources.

Adenine↗
PubMed1979

Comparative bactericidal activities of beta-lactam antibiotics determined in agar and broth media.

Comparative bactericidal activities were determined utilizing a relatively large number of test strains, in both agar and broth media, with special reference to the time of exposure of the bacteria to certain beta-lactam antibiotics. It was apparent that the activities increase with time. The concentrations producing a 99.9% kill with cephalothin for Escherichia coli, Klebsiella sp., and carbenicillin for Pseudomonas aeruginosa were higher in broth than in agar. In contrast, those of benzylpenicillin for alpha-streptococcus (non-enterococcal) were higher in agar than in broth. If the bactericidal concentrations with 3-hour or 6-hour exposure to antibiotics were used as the criterion, these concentrations of carbenicillin for P. aeruginosa, and benzylpenicillin for alpha-streptococcus were, in particular, unusually high compared with the conventionally determined bacteriostatic concentrations (MICs).

Agar↗
PubMed1978

Terminal bronchiolar-alveolar (TB-A) units in circumfusion system cultures.

Long-term (more than 75 days) recirculating circumfusion system cultures of 15-day fetal mouse lungs gave rise to terminal bronchiolar-alveolar (TB-A) units detached from the respiratory tree. TB-A units established in serum-free microenvironments under reconstructed cellophane membranes became especially flat and optically accessible in fast-flowing 6-chamber systems devoid of a pulse pressure. Time-lapse cinephase movies showed that the alveoli was maintained debris-free by the phagocytosis of alveolar macrophages which entered the alveoli by penetrating the pneumocytic walls. The terminal bronchioles with active ciliary cells communicated with the alveoli and together they formed a flat fluid-filled tubule-like closed system composed of ultrastructurally typical differentiated cellular constituents, viz. types I and II pneumocytes, endocrine-like cells, ciliary cells. Clara cells, and septal cells. TB-A units were observed throughout 150 days of cultivation at which time their phase morphological differentiation remained stable and their functional activity observable as smooth-muscle contractions, ciliation, and alveolar macrophage phagocytosis. A 1000-foot motion-picture film complementing the descriptions of the TB-A units and the alveolar macrophages in the text is deposited with the Motion Picture Film Rental Collection of the Tissue Culture Association, Inc., at the W. Alton Jones Cell Science Center, Lake Placid, New York.

Basement Membrane↗
PubMed1977

Fetal mouse lung in circumfusion system cultures.

Fetal mouse lungs were cultivated, using the dual-rotary circumfusion system for tissue culture, and their histotypic development was surveyed for 75 days by phase-contrast and electron microscopy. Alveoli, terminal bronchioles and alveolar macrophages were photographed periodically with still and time-lapse phase-contrast microscopy. Their histotypic appearance was confirmed by electron micrographs of the 1- and 2 1/2-month-old specimens. These revealed typical alveoli surrounded by a basal lamina and composed of types I and II pneumocytes containing various lamellar-body forms within the type II cells, the alveolar lumen, and the alveolar macrophages. There was a shift from almost all type II cells in the 1-month-old alveoli to the presence of frequent type I cells as constituents of the alveoli in the 2 1/2-month-old cultures. The terminal bronchioles were tubules consisting of ciliated cells with Clara cells interspersed between them. The ciliated cells contained as many as 30 cilia or basal bodies per section and numerous microvilli. They were attached to each other and to the Clara cells by junctional complexes and accessory desmosomes which were generally in the apical ends of the cells. The Clara cells typically had glycogen granules interspersed between lamellae of the endoplasmic reticulum, contained numerous well dispersed mitochondria, occasional lysosome-like granules and crystalloid bodies which appeared to be tubular. Some Clara cells presented a moderatley dense secretory granule in the center of the whorl of the endoplasmic reticulum.

Animals↗
PubMed1977

Phagocytosis of collagen by human gingival fibroblasts in vitro.

Human gingival fibroblasts cultivated on collagen-coated cover slips had collagen fibrils in deep folds of the cell membranes after one hour and fully interiorized fibrils by 24 hours. In 5-day sections, fibrils were within dense bodies, some containing multiple dense granules (40 to 50 nm) aligned along the surface of the interiorized collagen fibrils.

Cell Line↗
PubMed1976

Biogenetic origin of the D-isoleucine and N-methyl-L-alloisoleucine residues in the actinomycins.

Studies with (14)C-labeled isoleucine stereisomers have established that l-alloisoleucine, d-alloisoleucine, and d-isoleucine may function as precursors for the biogenesis of d-isoleucine and N-methyl-l-alloisoleucine residues in actinomycin. l-[(14)C]isoleucine appears to be employed chiefly for d-alloisoleucine (and N-methylisoleucine [?] formation); however, its role in the biosynthesis of d-isoleucine and N-methylalloisoleucine remains unclear. The potential pathway of biosynthesis of d-isoleucine and N-methyl-l-isoleucine is discussed.

Amino Acids↗
PubMed1976

Ultrastructural and cytochemical studies on the remodelling of the tracheal cartilage.

Ultrastructural and cytochemical studies on the remodelling of the rat tracheal cartilage have been carried out. The thickness of the tracheal cartilage was constant, during the observation periods (1 to 54 days after birth). The external perichondrium of the tracheal cartilage consisted of active fibroblasts and intercellular fibrils. The inner part of this perichondrium was a chondrogenic layer, where appositional growth was taking place. On the other hand, the internal perichondrium contained fibroblast-like cells, which were nearly twice as large as the external perichondrial fibroblasts in size and were arranged in three or four layers. The cells had well developed organella and large vacuoles which contained numerous fragments of fibrils and/or glycosaminoglycan. Many cytoplasmic processes protruded to the cartilage matrix, where the intercellular fibrils were particularly irregular in arrangement. Some vacuoles included collagen fibrils. Based on an intense acid phosphatase activity in these vacuoles and other findings, the fibrils were thought to be phagocytosed collagen of the cartilage matrix. An extensive alkaline phosphatase activity was demonstrated on the plasma membrane of fibroblasts and chondroblasts in the external perichondrium. The present investigation revealed distinct functional difference between the external and internal perichondrium of the tracheal cartilage. It is resorbed at the internal perichondrium, while it appositionally grows at the external perichondrium. The fibroblast-like cells of the internal perichondrium play an essential role in resorption of the matrix in cartilage remodelling.

Acid Phosphatase↗