Search PubMed⌕ Search

Biomedical subjects

N Yamaguchi

Publications and source records attributed to N Yamaguchi.

At least 919 records · Page 51Linked to original sources
PubMed1976

Growth hormone release following thyrotrophin-releasing hormone injection into patients with anorexia nervosa.

The effect of thyrotrophin-releasing hormone (TRH) or luteinizing hormone-releasing hormone (LH-RH) on plasma levels of growth hormone (GH), prolactin (PRL), thyrotrophin (TSH), and luteinizing hormone (LHY, were studied in patients with anorexia nervosa. The basal plasma GH levels were elevated in 6 of 11 patients studied. Intravenous injection of synthetic TRH T500 mug) significantly raised the plasma GH levels in 9 of 11 patients. The peak values of plasma GH after TRH ranged from 6.0 to 31.5 ng/ml. Plasma GH concentrations also increased following the administration of synthetic LH-RH (100 mug) 1 of 7 patients. The intravenous injection of saline solution caused no significant change in plasma GH in these patients. The plasma LH responses to LH-RH were significantly blunted in all patients, whereas the plasma PRL and TSH responses to TRH were almost normal in the patients examined. These results suggest that the hypothalamo-pituitary function regulating GH and LH secretion is altered in patients with anorexia nervosa.

Adolescent↗
PubMed1976

Correlation between changes in endogenous catecholamine release from the heart and various physiological responses in anesthetized dogs.

Correlations between the concentration of endogenous catecholamines in coronary sinus blood and various physiological responses to adrenergic stimulation were studied in anesthetized dogs. Plasma catecholamine levels both in coronary sinus and aortic blood were measured by means of a modification of the radiometric-enzymatic assay for tissue catecholamines, and found to be 0.769 +/- 0.110(S.E.) and 0.972 +/-0.127(S.E.) ng/ml, respectively, under basal conditions. Circulating catecholamine levels increased after the intracoronary injection of 6-hydroxydopamine, which has an indirect sympathomimetic action. Both the increment in catecholamine release from the heart and the intensity of physiological response were dose-related. A frequency-dependent increase in coronary sinus blood catecholamine levels occurred during right cardioaccelerator nerve stimulation. Maximum values were observed with a stimulation frequency of 10 Hz, at which maximum physiological responses were obtained. A highly significant correlation was found between endogenous catecholamine levels in coronary sinus blood and the dp/dt of left ventricular pressure (r = 0.750, p less than 0.001), as well as mean coronary blood flow (r =0.706, p less than 0.001). The present preparation may prove to be a reliable means of studying the role of the sympathetic system in regulating cardiac function.

Animals↗
PubMed1975

Temperature-sensitive mutants of chemically transformed epithelial cells.

The first temperature-sensitive mutants of epithelial cells transformed with chemical carcinogens have been isolated. Like the wild-type transformed parental cells, the mutants readily grow in agar suspension at 36 degrees, but in contrast to the wild type, they do not do so at 40 degrees. Detailed studies of one of these mutants, TS-223, indicate that at high temperature it also has reduced cloning efficiency in monolayer culture and a lower saturation density. Scanning electron microscopy revealed that at 40 degrees confluent cultures of TS-223 consist of a monolayer of generally flat polygonal cells, whereas 36 degrees cultures contain many patches of piled-up cells that are spherical and have rougher surface membranes. All of these cellular changes are reversible with upward or downward temperature shifts. The temperature-sensitive lesion appears to reside in a host cell gene which modulates expression of the transformed cell phenotype. These mutants may provide a useful system for elucidating the minimal biochemical changes required for expression of the transformed phenotype in epithelial cells.

Animals↗
PubMed1975

Temperature-sensitive mutants of simian virus 40 selected by transforming ability.

Eight temperature-sensitive mutants of simian virus 40 which transform rat cells at 32.5 C but not at 38.5 C have been isolated. All the mutants were also temperature sensitive for replication in African green monkey kidney cells and five of them were classified into a single complementation group. No mutant incapable of transforming rat cells at either temperature was isolated.

Animals↗
PubMed1975

Characterization of T antigen in cells infected with a temperature-sensitive mutant of simian virus 40.

T antigen induced in African green monkey kidney cells by a temperature-sensitive mutant of simian virus 40, defective in a function required for cell transformation, was characterized. The number of T antigen-positive cells estimated by an immunofluorescent techniques was almost equal at permissive (32.5 C) and restrictive (38.5 C) temperatures, but was slightly reduced when the infected cells were incubated at a higher temperature (40.5 C). However, a complement fixation test indicated that the amount of T antigen induced by the mutant is not significantly different from that induced by wild-type virus at 40.5 C. These results suggest that the T antigen-inducing ability of the mutant is not defective. Two distinct molecular species of T antigen were induced by the mutant at the permissive temperature, whereas only one form was observed at the restrictive temperature. The larger molecular form (14 to 15S) induced by the mutant at the permissive temperature was more heat labile than that induced by wild-type virus, suggesting that the mutated gene product is a component of the larger molecular form.

Animals↗
PubMed1975

Correlation between the response of the heart to sympathetic stimulation and the release of endogenous catecholamines into the coronary sinus of the dog.

The relationship between the increase in catecholamine levels of the coronary sinus blood and the amplitude of various cardiac responses to adrenergic nerve stimulation was studied in anesthetized dogs. Plasma catecholamine levels in both coronary sinus and aortic blood were measured by a modification of the radiometric enzymatic assay for tissue catecholamines and were found to be 0.622 plus or minus 0.104 (SE) ng/ml and 0.933 plus or minus 0.116 ng/ml, respectively, under basal conditions. The catecholamine levels in coronary sinus blood increased linearly during right cardioaccelerator nerve stimulation up to a frequency of 10 Hz. At this frequency, maximum values were observed in both coronary sinus blood catecholamine levels and cardiac responses. The correlation between the response in heart rate, mean coronary blood flow, and dP/dt of left ventricular pressure and the increase in endogenous catecholamine levels of coronary sinus blood was significant, but the relationship was nonlinear. The present experimental design may prove to be a reliable means of studying the role of the sympathetic nervous system in the regulation of cardiovascular function in vivo.

Animals↗
PubMed1975

Growth hormone and prolactin release after injection of thyrotropin-releasing hormone in patients with depression.

The effects of thyrotropin-releasing hormone (TRH) on the release of growth hormone (GH), prolactin (PRL) and thyrotropin (TSH) were investigated in patients with depression. Intravenous injection of synthetic TRH (500 mug) caused a significant increase in plasma GH (peak value: 7.7 minus 35.0 ng/ml) in 8 of 13 patients with mental depression. After clinical recovery these patients had no response of plasma GH to TRH. TRH administration did not raise plasma GH in normal subjects examined. Plasma PRL responses to TRH were significantly enchanced (P smaller than 0.05) in depressed patients compared with control subjects. Plasma TSH responses to TRH were significantly blunted in patients with depression (P smaller than 0.05). These results suggest disorders in the hypothalamo-pituitary function in depression.

Adult↗
PubMed1975

Transition of nystagmus types in unilateral labyrinthine diseases.

In order to clarify changes in spontaneous and positional nystagmus which occurred during the course of peripheral labyrinthine diseases, 31 patients with Ménières disease (17 cases), aural vertigo of unknown etiology (9 cases), and sudden deafness (5 cases) were tested repeatedly using ENG. The testing of each case was made 4.8 times on the average with an average interval of 7.2 days. Twenty-four cases (77.4%) showed more than two of the following four types which are listed in serial order of occurrence: spontaneous (or direction-fixed positional) nystagmus toward the involved ear; geotropic direction-changing positional nystagmus; spontaneous (or direction-fixed positional) nystagmus toward the opposite ear; and apogeotropic direction-changing positional nystagmus. Thus, the above-mentioned order may be regarded as the uniform pattern in the nystagmus transition caused by acute unilateral labyrinthine diseases.

Adult↗