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Biomedical subjects

K Shiono

Publications and source records attributed to K Shiono.

At least 19 recordsLinked to original sources
PubMed1990

[Study on the relation for physical properties of masticatory jelly and masticatory muscle activity].

To measure the masticatory force used for everyday foods it is desirable to base the measurements on one mouthful of food. However, one mouthful of food changes in size and hardness. The purpose of this study is to establish a formula for estimating a correlation between the amount and force of mastication, active potentials and their integrated values, and the concerned material's size and hardness no matter they are same or unified. It is possible to measure the amount of mastication for normal foods without recording electromyographically. The effective method for recording the hardness of the jelly is the application of needle plunger. The thickness divided by the hardness and multiplying the value with the volume of the material, an estimated formula is thereby established to correlate with the integrated values of mastication.

Bite Force↗
PubMed1989

[Trends of the patients with malocclusion on dental clinic of pediatric dentistry].

The factors which determine the situation of continuation in malocclusion treatment and characteristic of patient with malocclusion in pediatric dentistry were estimated from the status and the trend of patients undergoing denture guidance at the outpatient clinic for pediatric dentistry. The following results were obtained. 1. Among the patients undergoing denture guidance, a majority were females. Among the different types of malocclusion, the reversed occlusion was the most frequent, being 54.3% among all malocclusions. 2. In particular the age for first visit was from under 3 years of age with reversed occlusion, and at this age, females were more numerous than males. 3. The first examination for denture guidance was related to the time which made effective diagnosis possible, and the patients with reversed occlusion had their first examinations consistently from 3 years of age, and the patients with crowding had their first examinations from 6 years of age to 11 years of age. 4. From the difference between the age of first visit and first examination, it was shown that the patients with reversed occlusion did not have their first examination under 3 years of age and for the patients with crowding who visited first at 3, 4 and 5 years of age, the first examination was performed after 6 years of age. The patients with crowding in the group who came for consultation by reference were later about two years compared with other two groups in the difference of motivation for visiting. 5. It is suggested that the factors which had an influence upon the situation of continuation of malocclusion treatment were; an existence of the use of an appliance, a substantial program of correspondence in regard to dental care for malocclusion before malocclusion treatment and concrete indication of the treatment.

Child↗
PubMed1985

Studies on YM-12617: a selective and potent antagonist of postsynaptic alpha 1-adrenoceptors.

YM-12617, 5-[2-[[2-(2-ethoxyphenoxy)ethyl]-amino]propyl]-2 -methoxybenzenesulfonamide HCl is a structurally new type of extremely potent alpha 1-adrenoceptor antagonist. Its alpha-adrenoceptor blocking properties have been compared with those of prazosin, phentolamine and yohimbine using both pharmacological and 3H-ligand binding techniques in vitro and in vivo. In the isolated rabbit aorta, a tissue known to contain mainly alpha 1-adrenoceptors at postjunctional sites, YM-12617 competitively antagonized noradrenaline-induced contraction with a pA2 value of 10.11. Although YM-12617 was also a competitive antagonist toward clonidine at prejunctional alpha 2-adrenoceptors in the isolated rat vas deferens, its affinity for these receptors (pA2 = 6.41) was 5,000 times lower than that displayed for the postjunctional alpha 1-adrenoceptors in the isolated rabbit aorta. YM-12617 displaced both 3H-WB 4101 and 3H-clonidine binding to rat brain membranes; however, the affinity of YM-12617 for alpha 1-adrenoceptors (pKi = 9.64) was 3800 times higher than that for alpha 2-adrenoceptors (pKi = 6.06). Based on pA2 values obtained in the isolated tissues and pKi values in the binding assays, YM-12617 was 2-18, 36-117 and 1,740-5,750 times more potent than prazosin, phentolamine and yohimbine in antagonizing alpha 1-adrenoceptors, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1985

Cardiovascular pharmacology of nicardipine in animals.

The haemodynamic, antianginal and antihypertensive effects of nicardipine, a vascular selective calcium antagonist, were studied in experimental animals. In the canine isolated coronary artery, nicardipine relaxed potassium-induced contraction and suppressed 3,4-diaminopyridine-induced rhythmic contractions more effectively than nifedipine, verapamil or diltiazem. In anaesthetised rats, nicardipine prevented the elevation of ST segment induced by intracoronary injection of methacholine. In anaesthetised dogs, nicardipine produced a greater vasodilatation in vertebral, carotid, and coronary vessels than in mesenteric, femoral, and renal vessels and did not affect myocardial oxygen consumption. In conscious monkeys, nicardipine given intravenously lowered blood pressure and gave rise to reflex tachycardia but did not prolong the A-V conduction time. Nicardipine given orally lowered blood pressure in spontaneously hypertensive rats (SHR), renal hypertensive rats (RHR), and deoxycorticosterone acetate/salt hypertensive rats (DOCA/Salt), as well as in normotensive rats. Long-term treatment with nicardipine given orally for 12 weeks effectively lowered high blood pressure in the three types of hypertensive rats, reduced cardiac hypertrophy in SHR and DOCA/Salt rats, and prevented mortality from stroke in DOCA/Salt rats. Combined treatment with nicardipine and a beta-adrenoceptor blocking agent (indenolol) showed an antihypertensive effect similar to that obtained with nicardipine alone. Conscious renal hypertensive dogs given repeated oral administration of nicardipine for 14 days did not develop tolerance to the hypotensive activity of nicardipine. Under the same conditions, tolerance to hydralazine developed within 4 days.

Animals↗
PubMed1985

Autonomic and antihypertensive activity of oral amosulalol (YM-09538), a combined alpha- and beta-adrenoceptor blocking agent in conscious rats.

The autonomic and antihypertensive activities of amosulalol (YM-09538) were studied in conscious rats. Single oral administration of amosulalol antagonized the phenylephrine-induced pressor and isoproterenol-induced positive chronotropic responses with DR10 values of 11.5 and 13.6 mg/kg in pithed rats, respectively, indicating that the compound inhibits both alpha 1- and beta 1-adrenoceptors to almost the same extent in agreement with previously reported results in vitro. Amosulalol was approximately 50 times less potent than prazosin and 12 times more potent than labetalol at alpha 1-adrenoceptors, and it was approximately as effective as labetalol and 2 times more potent than propranolol at beta 1-adrenoceptors. In spontaneously hypertensive rats (SHR), renal hypertensive rats and DOCA/salt hypertensive rats, a single oral administration of amosulalol (3-30 mg/kg) lowered acutely systolic blood pressure with a duration of over 6 hr and was found to be approximately 50 times less potent than prazosin and 3 times more potent than labetalol in lowering blood pressure. Propranolol did not cause such an immediate hypotensive effect. Amosulalol and labetalol did not increase heart rate, whereas prazosin induced a tachycardia in the hypertensive rats. Repeated oral administrations of amosulalol and labetalol (50 mg/kg/day, b.i.d., for 12 weeks) produced not only an antihypertensive effect without evidence of tolerance, but also reductions in plasma renin activity (PRA) and heart rate in SHR with established hypertension. We conclude that alpha-adrenoceptor blockade by amosulalol might account for its antihypertensive activity and that its beta-adrenoceptor blockade might inhibit reflexogenic increases in heart rate and PRA due to the reduction in blood pressure.

Adrenergic alpha-Antagonists↗
PubMed1983

Influence of tooth-to-denture-base discrepancy on space closure following premature loss of deciduous teeth.

Influence of tooth-to-denture-base discrepancy on so-called physiologic migration of the first molar was studied on serial dental casts of 116 boys and girls, obtained through a dental health program for school children in an area in which there was no dentist. The alteration of spaces following premature loss of deciduous molars was examined comparing the anterior to posterior discrepancies between tooth and denture base. Modes of space alteration showed positive correlation with the size of the discrepancy, especially in the mandibular dental arches. The space deficiency in the posterior region seemed to have a positive effect on the mesial migration of the first molar. Mesial migration of the first molar seems to be pathologic rather than physiologic and is strongly affected by tooth-to-denture-base discrepancies. Space maintenance does not seem to be useful, because it is not necessary in minimum discrepancy cases and is not effective in severe discrepancy cases.

Adolescent↗
PubMed1982

Antihypertensive and adrenoceptor blocking properties of new sulfonamide-substituted phenylethylamines.

Studies on the structure-activity relationship using 9 new 3-sulfamoylphenylethylamines revealed that YM-09538, YM-09649 and YM-09686 were competitive antagonists at both beta- and post-synaptic alpha-receptors. The following order of adrenoceptor blocking activities was obtained : propranolol greater than labetalol greater than YM-09538 greater than YM-09649 greater than YM-09686 for beta-receptors and prazosin greater than YM-09686 greater than YM-09649 greater than YM-09538 greater than phentolamine greater than labetalol for postsynaptic alpha-receptors. In contrast to phentolamine, three YM-compounds showed low affinities for presynaptic alpha-receptors similar to prazosin and labetalol. These antagonists except propranolol effectively lowered blood pressure in conscious SHR and their relative effectiveness parallels the postsynaptic alpha-blocking activity. At hypotensive doses, phentolamine markedly and prazosin, YM-09686 and YM-09649 moderately increased heart rate, whereas YM-09538 and labetalol failed to increase the rate. These results indicate that the postsynaptic alpha-blocking activity of YM-compounds contributes to their hypotensive activities and that both beta-blocking and low presynaptic alpha-blocking activities contribute to attenuation of the tachycardia.

Animals↗
PubMed1980

Physiological and light-electron microscopical studies of parietal cells and G cells before and after selective vagotomy with pyloroplasty.

The function of residual parietal cells and G cells following selective vagotomy with pyloroplasty (SV + P) in 21 duodenal ulcer patients was assessed by light-electron microscopical studies of gastroendoscopic biopsy material and determination of gastric acid secretion and serum gastrin levels. The postoperative decrease in number of parietal cells was not so great when compared with the reduction of acid secretion. However, the ultrastructural changes of parietal cells suggested hypofunction of the cells. In addition, the response of parietal cells to histalog stimulation was also decreased according to morphological observations under electron microscope. Basal plasma gastrin was significantly increased (p < 0.01) one month after surgery. Integrated gastrin response (IGR) to meat extract and insulin hypoglycemia stimulation was also increased significantly (p < 0.01) six months postoperatively. The G cells were still increasing in number six months after SV + P, and G cell hyperplasia became more remarkable after one year. Emiocytotic figures were observed in denervated G cells which were stimulated by meat extract or insulin hypoglycemia. On the basis of the findings of this study, it is considered necessary to conduct complete vagotomy on the parietal cell region when SV + P is performed.

Adult↗
PubMed1980

Effects of beta-adrenergic blocking drugs in hypertensive rats.

Antihypertensive effects of three beta-adrenergic blocking drugs, acebutolol, propranolol, and practolol were studied for 11 weeks. Spontaneously (SHR); one-clip, two-kidney (CLIP); and deoxycorticosterone and salt (DOC) hypertensive rats were used. The drugs were given orally, 100 mg/kg per day, 5 days per week before development of hypertension. Propranolol inhibited blood pressure (BP) increase significantly in SHR. Acebutolol and practolol also lowered BP in SHR. Three drugs did not affect BP in CLIP, but an apparent inhibition was seen when the results were analyzed including the cases of which BP stayed below 150 mmHg. Either of three drugs did not show antihypertensive effects in DOC. Acebutolol rather increased BP more rapidly. Practolol also increased BP slightly more rapidly. Cerebral stroke was seen in DOC. The incidences of the stroke in the groups given the solvent, acebutolol, propranolol, and practolol were 3/6, 4/7, 2/6, and 3/6, respectively. Acebutolol seemed to cause stroke earlier with the more rapid BP elevation. Acebutolol, propranolol, and practolol decreased incidence of the vascular disease in CLIP. Propranolol also decreased it in DOC. Plasma renin activity was suppressed by these drugs in SHR and CLIP. The mechanisms of antihypertensive effects of beta-adrenergic blocking drugs are unknown. The present study denies those due to inhibition of cardiac function, or renin release from the kidney. A better experimental model is necessary to study this. The possibility that acebutolol and other beta-blockers might accelerate BP elevation and incidence of stroke must be reexamined.

Acebutolol↗
PubMed1980

Variation of plasma and kidney renin activities among substrains of spontaneously hypertensive rats.

Plasma and kidney renin activity (PRA, KRA) were determined in the spontaneously hypertensive (SHR) rats, the stroke-resistant and -prone substrains (SHRSR, SHRSP) from 5 to 30 weeks of age. Results were compared with those of two normotensive strains, Wistar-Kyoto (WKY) and Donryu (DON) rats. PRA in the SHRSP at 20 and 30 weeks of age were significantly increased when compared to other strains of rats (P < 0.01). In SHRSP rats at these ages, blood pressure exceeded the critical level of 220 mmHg and cerebral lesions were observed in 41% at autopsy. There were no significant differences in PRA among other hypertensive and normotensive strains. KRA in three substrains of the SHR were normal or subnormal as compared to WKY and DON rats. These results indicate that a direct role of the renin-angiotensin system in the SHR and its substrains can be excluded in the initiation and the maintenance of hypertension. However, the activated renin-angiotensin system in SHRSP rats in the course of malignant hypertension at 20 weeks of age and later, could participate in raising blood pressure above the levels of the SHR and SHRSR. Considering out data and others, there are many similarities in renin profile between the SHR and its two substrains, and human essential hypertension in which PRA can be classified as low, normal or high.

Aging↗
PubMed1978

Antihypertensive and antidiuretic effects of 3-hydrazino-6-[N, N-bis (2-hydroxyethyl) amino]-pyridazine (L 6150) in rats.

3-Hydrazino-6-[N,N-bis (2-hydroxyethyl)amino]-pyridazine (L 6150) has been reported as an antihypertensive vasodilator drug. We determined antihypertensive effect of L 6150 for 11 weeks in spontaneously hypertension due to clipping (CLIP). The effects of hydralazine (HZ) and ecarazine (EZ) were also determined for comparison. L 6150, HZ, and EZ showed antihypertensive effects in SHR, DOC and CLIP hypertensive rats. These drugs increased heart rate in SHR and DOC rats. In CLIP hypertension heart rate tended to be higher for 9--10 weeks after the treatments. These treatments diminished incidence of the vascular disease in DOC and CLIP. We also determined renal effects of L 6150, HZ and EZ in normal rats. These drugs decreased urine volume, and excretion of osmotically active solutes, Cl, Na, and K for 180 min after bicarbonate saline load. It is concluded that L 6150 is an antihypertensive drug with characteristics of the vasodilator in rats.

Animals↗