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Biomedical subjects

Y Yasuda

Publications and source records attributed to Y Yasuda.

At least 361 records · Page 20Linked to original sources
PubMed1984

In vivo and in vitro comparisons of biological activities of bovine, ovine and rat CRF (corticotrophin-releasing factor).

The biological activity of partially purified bovine hypothalamic CRF (corticotrophin- releasing factor) was compared to those of synthetic CRFs (ovine, rat) sauvagine and vasopressin in vivo and in vitro. ACTH-primed hypophysectomized rats with heterotopically transplanted pituitaries and medial basal hypothalamic ablation (H-T + MBHA ), and intact rats pre-treated with chlorpromazine, morphine and Nembutal (C-M-N) were used for in vivo CRF assays. Perifused rat adenohypophyseal fragments were employed for in vitro studies. CRF-A (void volume fractions, 'big' CRF) and CRF-B (Kav = 0.583) purified from bovine hypophyseal stalk, synthetic ovine and rat CRF, and sauvagine all induced significant stimulation of ACTH and/or corticosterone secretion in these systems. Synthetic ovine and rat CRF and sauvagine showed comparable CRF potency. The CRF dose-response slopes for bovine CRF were somewhat steeper than those for ovine CRF or sauvagine in the in vitro system. Vasopressin had the least steep dose-response slope. Intravenous bolus administration of ovine CRF caused a more prolonged (greater than 20 min) elevation of plasma ACTH compared to a relatively short duration after bovine CRF-A. These data suggest that bovine hypothalamus contains substance(s) which exhibits different CRF characteristics from those of ovine CRF.

Adrenocorticotropic Hormone↗
PubMed1984

Heterogeneity of activity of the prolactin-releasing factor in the bovine hypothalamo-neurohypophysial complex.

Fresh samples of bovine hypothalamic median eminence or hypophysial stalk extracted with 0.1 M-HCl and fractionated on Sephadex G-100 had two prolactin-releasing factor (PRF) components, the major one in the void volume (PRF-A) and the minor one in an elution position (partition coefficient (Kav) = 0.333) immediately after PRF-A (PRF-B). Similar fractionation of bovine posterior pituitary extracts showed two PRF peaks: PRF-A and another in a more retarded position than PRF-B (Kav = 0.645; PRF-C). Storage of bovine stalk extract at -20 degrees C for 1 year caused a shift from higher molecular weight PRF into PRF-C. Thyrotrophin-releasing hormone stimulated prolactin secretion, but its dose-response slope and chromatographic mobility were quite different from those for bovine tissue extracts. Secretion of prolactin induced by extracts of bovine hypophysial stalk is calcium dependent and is inhibited by dopamine.

Animals↗
PubMed1983

Cross transfer effects of muscular training on blood flow in the ipsilateral and contralateral forearms.

Blood flow in the right and left forearms was determined by venous occlusion plethysmography in ten healthy male subjects before and after training with a hand ergometer. The subjects in group A and B were trained using work loads of 1/3 and 1/2, respectively, of maximum grip strength 6 days/week for 6 weeks. It was found that the blood flow in the left (untrained or contralateral) forearm during exhaustive training of the right hand increased gradually with increasing training periods, and that after 6 weeks of training, grip strength, endurance and peak blood flow of the forearm increased significantly not only in the trained forearm, but also in the untrained forearm. From these results, it is suggested that the increase of blood flow in the contralateral limb after training may, at least in part, be related to the cross transfer effect of muscular endurance.

Adult↗
PubMed1983

Effect of disruption by sonication under different conditions on the activity of glucose dehydrogenase from resting spores of Bacillus subtilis.

The activity of glucose dehydrogenase present in resting spores of Bacillus subtilis varied strikingly with the conditions for disrupting the spores by sonic treatment, namely, the time and strength of sonication, and the type and pH of the solution used for suspending the spores. When the resting spores were sonicated for 30 min at a current of 1.45 A in 100 mM phosphate buffer in the range of pH 6.0 to 6.6 or in deionized water, the enzyme activity of the former suspension was approximately 10 times higher than that of the latter suspension. However, the enzyme activity of the latter was markedly stimulated in the presence of sodium chloride. The glucose dehydrogenase from resting spores disrupted in 100 mM phosphate buffer (pH 6.6) was a salt-independent, active enzyme with a molecular weight of about 120,000, whereas the enzyme from resting spores disrupted in deionized water was a salt-dependent, inactive one with a molecular weight of about 55,000. A high concentration of dipicolinic acid strongly inhibited activation by a salt of inactive glucose dehydrogenase from resting spores in deionized water, suggesting one of its several important roles in vivo.

Bacillus subtilis↗
PubMed1983

Fusion of Sendai viruses or subviral envelope components with chicken erythrocytes observed by freeze-fracture electron microscopy.

Four different types of envelope of Sendai virus or subviral components, that is, infectious and non-infectious virions, reassembled envelope particles (REP), and Tween-ether-treated envelope fragments (TE), were studied comparatively for membrane interactions with chicken erythrocytes by freeze-fracture electron microscopy, specifically for membrane alteration by envelope fusion. The freeze-fracture replicas of the attachment of the four envelopes in the cold exhibited a common pattern of impressions with attached envelopes, although the fracture plane traversed from erythrocyte to envelope at the periphery of the contact areas of three of the envelopes but not of TE, where the fracture plane mostly cut only through erythrocyte membranes impressed with TE. The freeze-fracture replicas of the four envelopes reacting with erythrocytes after a short incubation period at 37 C exhibited distinctive features: infectious virions and REP displayed evidence of envelope fusion, but non-infectious virions and TE showed a particular pattern of envelope association without fusion. Our data demonstrate that the pattern specific for envelope fusion is the formation of a continuous membrane from envelope to cell membrane in a cross fracture of an erythrocyte.

Animals↗
PubMed1983

[Preparation of experimental hypertension in mini-pigs].

Attempts at inducing experimental hypertension by loading with NaCl have been undertaken in six Göttingen mini-pigs (G-mini-pigs). In this connection, a paraperitoneal nephrectomy method was established and the renin-angiotensin-aldosterone system after bilateral nephrectomy was investigated. Paraperitoneal nephrectomy was considered to be a safe and convenient method because the operation was accompanied with little hemorrhage and completed in a short time. Using three animals, the renin-angiotensin-aldosterone system was examined after surgical removal of bilateral kidneys. After removal of both kidneys, plasma renin activity decreased rapidly while plasma renin substrate gradually increased. Plasma angiotensin II and aldosterone levels underwent a striking increase. This increase of plasma renin substrate was considered to be due to the presence of an endogenous renin-like substance, while angiotensin II and aldosterone levels appeared to undergo secondary stimulation. Plasma cortisol showed a transient appeared to undergo secondary stimulation. Plasma cortisol showed a transient increase after removal of the two kidneys and they remained at a low level, which implies that the adrenocortical function was normal. In the other three animals, hypertension was induced by NaCl loading and unilateral nephrectomy and the blood pressure remained increased persistently. Concomitantly with this phenomenon, plasma renin activity was gradually suppressed and the aldosterone level showed a similar tendency. It is suggested that sustained hypertension can be induced in G-mini-pigs by NaCl loading combined with unilateral nephrectomy.

Animals↗