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Biomedical subjects

Y Hamada

Publications and source records attributed to Y Hamada.

At least 595 records · Page 33Linked to original sources
PubMed1978

In vitro reversal of indomethacin-blocked ovulation by prostaglandin F2alpha.

An in vitro perfused ovary preparation was used to study the role of prostaglandin F2alpha (PGF2alpha) in follicle rupture. The administration of PGF2alpha alone has been shown to restore indomethacin-blocked ovulation in rabbits and monkeys. In the model used, ovulation consistently occurred when human chorionic gonadotropin (hCG) was given to the intact rabbit prior to ovarian removal. hCG-induced ovulation was blocked in both perfused and in situ control ovaries by indomethacin (10 mg/kg intravenously 6 hours after hCG) given to the intact animal. The addition of PGF2alpha (1 mg/200 ml) to the perfusion fluid restored ovulation in the isolated ovary as compared with the in situ ovary (P less than 0.005) and with the perfused, untreated ovary (P less than 0.01). Following removal and perfusion of both ovaries from rabbits treated with indomethacin, ovulation occurred following the addition of PGF2alpha to the perfusate, but did not occur without PGF2alpha (P less than 0.05). These data indicate that indomethacin can block ovulation and that ovulation can be restored by the addition of PGF2alpha to the perfusion system, further supporting the significance of PGF2alpha in the process of follicular rupture.

Animals↗
PubMed1977

Flow velocity of cardiac lymph and contractility of the heart: an experimental study.

The flow velocity of cardiac lymph in various abnormal conditions of the heart and in control situations was studied experimentally in dogs. The time needed for the cardiac lymph node to become stained after injection of contrast medium into the muscle layer of the left ventricular apex was measured as an indicator in determining flow velocity of cardiac lymph. Left ventricular contractility was studied simultaneously. The hypoxic dogs had a short staining time with a vigorous cardiac beat. (Short staining time means accelerated lymph flow through the heart). The hearts in which the coronary sinus was ligated revealed the shortest staining time with an insignificant contractile change. The exsanguinating dogs had a long staining time with reduced contractility. The dogs with ventricular fibrillation had the longest staining time. When the heart rate was fixed by pacing, the staining time reflected contractile change. The contractile force of the heart plays an important role in the flow velocity of cardiac lymph.

Animals↗
PubMed1977

[Biochemical studies of acebutolol-the beta1 specificity of acebutolol (author's transl)].

Effects of acebutolol on carbohydrate and lipid metabolism in rats and on adenylate cyclase of heart and liver in dogs were investigated to determine the beta receptor blocking properties of the compound. Acebutolol exhibited the beta blocking activity and inhibited the increase of serum lactate concentration induced by adrenaline. This inhibition was about one-sixth as potent as that of propranolol. In hyperglycemic and free fatty acid effects of adrenaline, acebutolol inhibited the adrenaline-induced free fatty acid increase more effectively than hyperglycemia induced by adrenaline. In the inhibition of stimulated adenylate cyclase activity in the heart and liver, acebutolol was more active on the heart than on liver. Relative beta1 specificity of acebutolol was 93.2. Inhibition of propranolol on adenylate cyclase activity was more potent than that of acebutolol on both tissues, but showed no specificity. These results suggest that acebutolol is beta1 selective, although its beta blocking potency is less than that of propranolol.

Acebutolol↗
PubMed1977

Gamete interactions in vitro.

A method was devised that allowed observation of individual sperm in vitro in the presence or absence of unfertilized eggs. Sperm traversing microcapillary tubes in the absence of eggs moved in linear tranjectories. Sperm in the environs of unfertilized eggs moved in erratic paths, owing to repeated adherence of the sperm head to the wall of the microcapillary tube. However, translational velocity was unaltered. Increased adhesiveness was not noted when sperm were exposed to unfertilized eggs following removal of the cumulus oophorus with hyaluronidase. Gamete interactions in vitro were also studied at varying sperm to egg ratios. When gametes were mixed at high sperm to egg ratios (approximately 10(6):1) the cumulus oophorus was rapidly dissolved, and sperm became adherent to the zona pellucida. At low ratios (approximately 10(2):1), the cumulus oophorus remained intact. Binding of sperm to individual cumulus cells was noted. A hypothesis is presented that cumulus oophorus plays a role in fertilization by selectively trapping mature sperm within the perimeter of the egg and, in so doing, extending the duration of time in which gametes remain within close proximity, thus increasing the likelihood of egg contact by capacitated sperm.

Adhesiveness↗