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Biomedical subjects

T Sakamoto

Publications and source records attributed to T Sakamoto.

At least 1,171 records · Page 65Linked to original sources
PubMed1981

[Echocardiographic study of mitral and tricuspid valve openings in normal subjects (author's transl)].

The purpose of the present echocardiographic study is to determine the timing and order of both mitral and tricuspid valve openings in normal subjects and to provide the basic data for evaluating diastolic hemodynamics in cardiac patients. The subjects consisted of three groups: (i) 30 normal young cases in which the opening of both valves was recorded, (ii) 8 cases with idiopathic atrial fibrillation in which the relationship between preceding R-R and early diastolic intervals was determined, and (iii) 10 cases in which the effect of the direction of the ultrasonic beam on mitral valve echograms was evaluated. By applying dual echocardiography or phonoechocardiography, the interval from the aortic component of the second heart sound (IIA) to the point of maximal anterior opening (E), the isovolumic relaxation period from IIA to the onset of opening (D') and opening slope of the anterior leaflet were measured in each valve echogram. Careful recording was mandatory for measurements because even slight angulation of the transducer toward the mitral ring induced the timing of D' point and opening slope to vary. Respiratory variation was observed on the movements of both valves. During inspiration mitral valve opening occurred further from IIA or did not change in timing, but the tricuspid valve opened prematurely. During expiratory phase, the mitral valve opened nearly simultaneously with the tricuspid valve. The measurements were: IIA-E interval = 99.8 +/- 13.1 (mean +/- SD), 104.5 +/0 20.6 msec; IIA-D' interval = 47.2 +/- 9.9, 48.3 +/- 13.1 msec; opening slope = 301 +/- 76, 264 +/- 59 mm/sec, in mitral and tricuspid valve echograms, respectively. In cases with atrial fibrillation, these measurements were nearly constant regardless of varied preceding R-R intervals in 8 mitral and in one tricuspid valve echograms. It was expected from observing the effect of R-R intervals on valve opening in a case of valvular disease that diastolic hemodynamics could be evaluated by analysing the timing and order of both valvular openings, especially in relation to the preceding R-R intervals in atrial fibrillation.

Adolescent↗
PubMed1980

Studies on anticoccidial agents. 13. Synthesis and anticoccidial activity of nitropyridine-2- and -3-sulfonamides and derivatives.

Eight nitropyridinesulfonamides and pyridinesulfonamide N-oxides as their bioisosteres were prepared and evaluated for anticoccidial activity. Of these compounds, 2-, 4- and 5-nitropyridine-3-sulfonamides and pyridine-2- and -3-sulfonamide N-oxides were found to be active against Eimeria tenella. Thus, the relative positions, ortho or meta, of the substituents in nitropyridine-3-sulfonamides and pyridinesulfonamide N-oxides are important for anticoccidial activity. N-Substituted analogues of 5-nitropyridine-3-sulfonamide were also prepared and optimal anticoccidial activity was attained with the sulfonamide and its lower N-alkyl derivatives. The mode of action of 5-nitropyridine-3-sulfonamide was examined and found to be active in the sporozoite and the first schizogony stages.

Animals↗
PubMed1980

An appraisal of radical pancreatoduodenectomy based on glucagon secretion.

In an attempt to elucidate changes in endocrine functions of the pancreas associated with radical pancreatectomy for periampullary cancer, plasma levels of insulin (IRI) and pancreatic glucagon (IRG) were measured during arginine infusion in ten patients with periampullary cancer both before and after pancreatoduodenectomy. The response of plasma IRI to arginine which was impaired before the surgery showed further impairment after the surgery. This finding is consistent with the previous results obtained in such patients by oral glucose tolerance testing. Also, the response of plasma IRG was subnormal preoperatively and was found to be impaired postoperatively. Both maximum and integrated secretion of IRG during arginine infusion decreased after the surgery in all instances. From these findings, it is concluded that pancreatoduodenectomy aggravates the already disordered pancreatic endocrine functions, as indicated by arginine infusion in patients with periampullary cancer.

Adult↗
PubMed1980

[Production of various cerebral infarction models in the dog by means of occlusion of intracranial trunk arteries (author's transl)].

Knowing that, by use of a surgical microscope and a unilateral temporal approach, all of the bilateral trunk arteries at the base of the skull in dogs can be identified and treated, we succeeded in producing various infarction models by means of simultaneously occluding the vessels in various combinations. These infarction models include: unilateral or bilateral complete cerebral hemisphere infarction models, a unilateral hemispheric and contralateral cerebral mantle infarction model, a unilateral thalamic and contralateral cerebral mantle infarction model, etc. In the anterior thalamic infarction model, the severity of infarction foci can be regulated by the time of vessel occlusion, and chronic experiments achieved. In the other infarction models, however, severe edema is seen following recirculation after more than one hour occlusion, making them unsuitable as models for chronic infarction. Nontheless, it is thought that such models have great value as models of brain edema and these various models for cerebral infarction in the dog will prove valuable in clarifying many of the outstanding problems with regard to the basic science of the cerebral hemispheres.

Animals↗
PubMed1980

[Changes of tissue pH in dog brain during ischemia--alkaline shift (author's transl)].

Brain pH changes during ischemia were observed by the newly established histochemical technique in Dr. Kogure's laboratory (Miami). The technique utilizes intravascular injection of neutral red as a pH indicator. Its use is based on the fact that neutral red is red in acid and yellow in alkaline pH. Thalamic infarction model in dogs was used in this experiment. The methods of producing this model by temporary occlusions of brain arteries have been published elsewhere. The animals were anesthetized with sodium thiopental, immobilized with pancronium bromide, and artificially ventilated with room air. Blood gases and blood pH were adjusted to normal. Before the experimental procedure, 3 ml/kg of a 5% saline suspension of neutral red was injected slowly into the femoral artery. After occlusions of cerebral arteries, the brain was frozen in situ by pouring liquid nitrogen into the bottomless cup. The frozen brain was mounted on a cryostat at -20 degrees C and sliced coronally in 10 micron thickness. Color differences in the serial sliced brain surface were observed. No change in the color was observed in the sham operated brains. Thirty minutes following occlusion, the color of the thalamus is reddish, and it was estimated that this area became acidotic. 1 hour following occlusion, too, the thalamus is acidotic. But 2 hour following occlusion, the color of the thalamus became yellowish, indicative of alkaline shift. From this experimental results, it is considered that the pH of ischemic brain changes dynamically, that is, ischemic brain becomes acidotic in the early stage of ischemia but with the lapse of time alkaline shift occurs.

Animals↗
PubMed1980

[A ruptured aneurysm associated with pituitary tumor (author's transl)].

The aneurysm case associated with brain tumor is not so rare. Most of aneurysms are non-ruptured and found incidentally during the examination for brain tumor. We have experienced with 4 aneurysm cases associated with brain tumor among 1,280 aneurysm cases during these 17 years. One out of 4 cases was of ruptured aneurysm associated with pituitary tumor. This rare case and review of the literature were described.

Adenoma↗