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Biomedical subjects

T Ohno

Publications and source records attributed to T Ohno.

At least 883 records · Page 49Linked to original sources
PubMed1979

Plasma branched-chain amino acids in cold- and heat-acclimatised rats.

The concentrations of plasma branched-chain amino acids, valine, isoleucine and leucine, were significantly elevated in cold-acclimatised rats, while these values were significantly reduced in heat-acclimatised rats, in both 2-week and 4-week temperature acclimatisation.

Acclimatization↗
PubMed1979

Pontine and non-pontine pathways mediating early mossy fiber responses from sensorimotor cortex to cerebellum in the cat.

Stimulation of the cat's sensorimotor cortex evokes a short-latency mossy fiber field potential (N2) in the pars intermedia of the cerebellum. The fraction of the response carried by each of the six cerebellar peduncles was determined by comparing the field potentials before and after electrolytic lesions of individual cerebellar peduncles. The response evoked from the contralateral cerebrum is 3.5 times as large as that evoked from ipsilateral cerebrum. The size of the N2 wave from contralateral cerebral cortex is reduced to about half of the original size after electrolytic lesion of either the brachium pontis (BP) or the restiform body (RB) ipsilateral to the recording site, while only a small reduction in the size of N2 is observed after lesions of contralateral BP and RB. This indicates that inputs responsible for the generation of the N2 wave from contralateral cerebral cortex enter the cerebellum primarily through ipsilateral BP and RB. In contrast, the N2 wave from ipsilateral cerebral cortex is reduced by approximately one quarter following lesions of any one of the four RB's and BP's. Fibers in the brachium conjunctivum do not contribute to these responses. Observation on the P2 field potential, representing postsynaptic firing of granule cells, suggest that the cerebro-ponto-cerebellar and cerebro-reticulo-cerebellar mossy fiber pathways converge onto granule cells. Furthermore, these two inputs must arrive within 3 ms of each other in order to activate the granule cells. In addition, it is shown that BP lesions reducing the mossy fiber input lead to an increase in the climbing fiber input.

Animals↗
PubMed1979

Strict relationship between dialyzed serum concentration and cellular life span in vitro.

To determine the extent of the contribution of growth factor level on the life span of human diploid fibroblasts in vitro, the growth rate changes of IMR-90 cells under altered dialyzed serum (d-FBS) concentrations were investigated at different population doubling levels (PDL). As the PDL increased, the cells showed an accelerated requirement for d-FBS in order to maintain a constant growth rate, thus indicating a rapid loss of responsiveness of the cells to serum growth factors. A similar relationship was observed when the growth rate was extrapolated to zero and the cellular life span was predicted from this relationship. The cells cultured with 0.3% and 10% d-FBS ceased their growth at 54 and 76 PDL, respectively, while their predicted life span was 58 and 80--85 PDL, respectively. The cells cultured with 0.3% d-FBS responded poorly to an increase in the d-FBS concentration after entering phase III. These results suggest that the serum growth factor level is one of the determinants of cellular life span in vitro.

Cell Division↗
PubMed1979

Human breast carcinoma antigen is immunologically related to the polypeptide of the group-specific glycoprotein of mouse mammary tumor virus.

We have shown [Mesa-Tejada, R., Keydar, I., Ramanarayanan, M., Ohno, T., Fenoglio, C. & Spiegelman, S. (1978) Proc. Natl. Acad. Sci. USA 75, 1529--1533] that an antigen immunologically related to gp52, a 52,000-dalton glycoprotein of the mouse mammary tumor virus, can be identified in sections of human breast cancer by means of an indirect immunoperoxidase technique. The specificity of the reaction was established by absorption experiments which revealed that only purified gp52, or material containing it, served to eliminate the IgG molecules responsible for the immunohistochemical reaction in the human breast tumors. We show here that the cross-reactivity between the human and murine tumor antigens is due to the polypeptide rather than the polysaccharide components of gp.52. Sugar-free gp52 prepared by deglycosylation with a mixture of glycosidases was as fully effective as the intact gp52 in removing from anti-MMTV the IgG responsible for the reaction with the human tumor antigen. In contrast, the isolated polysaccharide of gp52 was unable to exert blocking activity.

Animals↗
PubMed1979

Thermoregulatory nonshivering thermogenesis in men, with special reference to lipid metabolism.

The existence of thermoregulatory nonshivering thermogenesis, with special reference to lipid metabolism, was investigated in men. Acute cold exposure (10 degrees C, 60 min) produced a marked increase in heat production, with concomitant elevation of plasma free fatty acid (FFA) level, modest increase of ketone body concentration and lowered respiratory quotient (R.Q.). The correlation of heat production to plasma FFA levels was significantly positive; that is, subjects with higher heat production showed higher plasma FFA levels. Moreover, correlation of either heat production or plasma FFA levels to R.Q. was significantly negative, respectively. On the other hand, exposure to cold after an administration of nicotinic acid, which has a suppressive effect on FFA mobilization from adipose tissue, resulted in less cold-elevated heat production, a significant fall of plasma FFA and ketone body concentrations, and no change in R.Q. Although no visible or only slight shivering was observed in control cold exposure study, greater shivering occurred in the nicotinic acid cold exposure study. These results appear to indicate that nonshivering thermogenesis as a source of heat production achieved by enhanced utilization of lipids is also present in men.

Adult↗
PubMed1979

Seasonal variation of plasma glucagon concentrations in men.

In an attempt to understand a role of glucagon in seasonal acclimatization in men, measurements of plasma glucagon, blood free fatty acids (FFA), blood glucose, blood ketone body (beta-hydroxybutyrate) and hematocrit were made in 13 male and 8 female college staff members, aged 20 to 42, once a month for one year. Blood samples were obtained at 4:00 to 5:00 p.m, between meals. Average monthly temperatures during the study were as follows; Jan. -7.8, Feb. -5.6, March -3.7, Apr. 4.6, May 11.4, June 18.3, July 23.9, Aug. 22.0, Sept. 14.7, Oct. 7.5, Nov. 1.4, Dec. -4.2 (degrees C). Plasma glucagon, blood FFA and blood ketone body exhibited significant monthly variation in both sexes. Plasma glucagon as well as blood FFA level was significantly higher in winter (Dec., Jan., Feb.) than in summer (June, July, Aug), whereas blood ketone body level was lower in winter than in summer. Plasma glucagon level was significantly lower in female than in male subjects. A significant positive correlation was observed between plasma glucagon and blood FFA levels throughout the year. Seasonal variations of blood glucose and hematocrit were not observed. These results suggest that seasonal variation in glucagon secretion is associated with seasonal changes in ambient temperatures as one of the strategies for climatic acclimatization through regulation of lipid metabolism.

Acclimatization↗
PubMed1979

Characterization of factors stimulating differentiation of mouse myeloid leukemia cells from a Yoshida sarcoma cell line cultured in serum-free medium.

A clone, YS-T22, of cells from Yoshida sarcoma cell line, YSSF-212T, grown in "serum-free" culture medium produced factors stimulating differentiation of mouse myeloid leukemia cells (M1) to macrophages and granulocytes. The formation of macrophages and granulocytes was accompanied by induction of phagocytosis, locomotive activity, and lysosomal enzyme activities. The rates of induction of these differentiated phenotypes were proportional to the concentration of the factor added and the period of treatment. The factor stimulating differentiation of M1 cells was a heat-labile, nondialyzable proteinaceous substance that was inactivated by trypsin but not by ribonuclease or glycosidases. On diethylaminoethyl cellulose chromatography, the factor stimulating differentiation of M1 cells from conditioned medium of YS-T22 cells was eluted in various fractions with or without activity of the colony-stimulating factor.

Animals↗