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Biomedical subjects

T Hata

Publications and source records attributed to T Hata.

At least 595 records · Page 33Linked to original sources
PubMed1980

On the base-stacking in the 5'-terminal cap structure of mRNA: a fluorescence study.

The fluorescence at 370 nm of the 7-methylguanosine residue (m7G) is found to be quenched when the base residue is involved in a stacking interaction with the adenosine residue in the cap structure m7G5' pppA of an eukaryotic mRNA. On the basis of the observed degree of quenching, the amounts of the stacked and unstacked forms in the cap structure have been determined at various temperatures and pH's. It has been found that at pH 6.2 effective enthalpy and entropy in the unstacked leads to stacked change are delta H degrees = 4.4 +/- 0.1 kcal/mole and delta S degrees = - 14.3 +/- 0.2 e.u., respectively. The pka value for the m7G residue is found to be 7.7 at 10 degrees C and 7.3 at 30 degrees C. The stacked structure seems to be less favourable in the deprotonated form that occurs in the higher pH solution. A similar analysis of some other cap structures indicates that the stacked form in m7G5' pppN structure is favourable if N is a purine nucleoside or a 2'-O-methylpyrimidine nucleoside but not for an unmethylated pyrimidine nucleoside.

Adenosine↗
PubMed1980

Effects of two angiotensin II analogues on blood pressure, plasma aldosterone concentration, plasma renin activity and creatinine clearance in normal subjects on different sodium intakes.

Two angiotensin II analogues (AIIA), 1-sarcosine, 8-isoleucine angiotensin II ([Sar, Ile]-AII) and 1-sarcosine, 8-alanine angiotensin II ([Sar, Ala]-AII), were infused in six normal volunteers on high, regular and low sodium diets. The agonist and antagonist activities of these AIIA on blood pressure (BP), plasma aldosterone concentration (PAC), creatinine clearance and plasma renin activity were examined. Both AIIA had agonistic pressor activities in subjects on high and regular sodium diets, [Sar, Ile]-AII being more potent than [Sar, Ala]-AII. Both AIIA caused similar elevation of PAC in subjects on high and regular sodium diets, and an equally fall in PAC in subjects on a low sodium diet. Both AIIA strongly antagonized the rise in BP, the increase in PAC and the reduction of Ccr induced by AII administration in subjects on all three sodium diets. The results indicate that both AIIA can be used to examine the activity of the renin-angiotensin system in patients with hypertension, and they also suggest that AII interaction with its receptors differs in different target tissues.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1980

Long-term effects of captopril in hypertension.

Captopril was given for treatment of hypertension alone or in combination with diuretics to 32 patients for 1- to 4-mo periods. The decrement of mean blood pressure after 1 and 2 mo correlated with pretreatment plasma renin activity (PRA) and the response of blood pressure to infusion of an angiotensin II antagonist. These correlations were no longer apparent after 4 mo of treatment. When subjects with a decrement of mean blood pressure that exceeded 13 mm Hg were compared with nonresponders, responders not only had higher control PRA and higher PRA at 1 mo of treatment, but also had decreased plasma aldosterone levels, decreased urinary aldosterone excretion, and increased serum postassium levels that persisted over the 4 mo of observation. The reduction of plasma aldosterone correlated with the fall of mean blood pressure. Urinary kallikrein, catecholamines, electrolytes, and endogenous creatinine clearance did not change in response to treatment. These findings indicate that the antihypertenisve activity of captopril on long-term administration probably depends in part on the blockade of angiotensin II, but other mechanisms cannot be excluded.

Adolescent↗
PubMed1980

Urinary catecholamine response to glucagon in young and elderly patients with essential hypertension.

The role of the sympathetic nervous system (SNS) in essential hypertension was evaluated by examining the response of urinary catecholamines to the intramuscular injection of glucagon in both young and elderly normal subjects (total 16) and in both young and elderly patients with essential hypertension (total 16). Urine was collected for 2 hours before glucagon injection and for 2 and 4 hours after injection, for determination of adrenaline and noradrenaline. The increments of urinary adrenaline and noradrenaline after glucagon injection were significantly higher in young hypertensive than in young normotensive subjects or in normotensive and hypertensive elderly subjects. The observation that the reactivity of the SNS is increased in young patients with essential hypertension lends support to the hypothesis that the SNS is more important in the maintenance of hypertension in the young than in the elderly.

Adult↗
PubMed1980

Experimental partial sympathicotonia, and effects of some drugs on it in restraint and water immersion stressed animals.

The contractile response to acetylcholine (ACh) of the isolated duodenum from the restraint and water immersion stressed (RWIS) mouse was found to be enhanced by the stress for 1 hr and reach a maximum in 3 hr stress followed by a decrease. It was clarified that this rise in the response is not due to the change in the affinity to ACh but due to the increase of the intrinsic activity. The contractile response to KC1 was augmented only when concentration of KC1 was high, While the response to BaCl2 was little enhanced in the stressed animal. The relaxing response to noradrenaline (NA) of the isolated duodenum from rat, on the other hand, was reduced by the stress. Such reduced response to NA was observed to be more marked than the enhanced response to ACh in the vas deferens isolated from the stressed animal. The pretreatment to the RWIS mouse with either antiadrenergic or cholinergic drugs resulted in the clear-cut blockade of the enhancement of response to ACh of the isolated duodenum from this animal. These results contrasted to the effects on the reduced response to ACh of the isolated duodenum from the SART stressed (repeated cold stressed) mouse. The pre-administration of psychotropic drugs showed marked suppression on the enhancement of response of the duodenum of the RWIS animal, though there was a quantitative difference between the RWIS and SART animals. The pretreatment with a neurosedative, Neurotropin (NSP) was also found to show similarly marked suppressive action. From these results, it was considered that the duodenum and the vas deferens of the RWIS animal are in the state of the sympathicotonia, namely partial sympathicotonia.

Acetylcholine↗
PubMed1980

Blood pressure response to an angiotensin II antagonist in thyrotoxic patients with and without high blood pressure.

An angiotensin II antagonist, [sacrosine1, isoleucine8] angiotensin II, was infused into thyrotoxic patients. Blood pressure was monitored before and during the infusions to investigate whether the renin-angiotensin-aldosterone system was involved in the maintenance of blood pressure in normotensive and hypertensive thyrotoxic patients. Five out of 17 normotensive patients with hyperthyroidism showed more than a 10 mmHg decrease in mean blood pressure in response to the infusion (responders), while the remaining 12 patients showed no substantial change in blood pressure (non-responders). The infusion caused little change in blood pressure in 8 hyperthyroid patients with systolic hypertension. The mean levels of serum thyroxine, triiodothyronine, plasma renin activity and plasma aldosterone concentration in the normotensive responders were significantly higher than the values in the normotensive non-responders. There were no significant differences in these laboratory values between the hypertensive patients and the normotensive non-responders except that serum triiodothyronine levels were significantly higher in the hypertensive patients. The present study indicates that increased activity of the renin-angiotensin-aldosterone system is involved in the maintenance of blood pressure in most normotensive patients with severe hyperthyroidism, while hypertension in patients with hyperthyroidism is not angiotensin II dependent.

1-Sarcosine-8-Isoleucine Angiotensin II↗