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Biomedical subjects

H Noda

Publications and source records attributed to H Noda.

At least 271 records · Page 15Linked to original sources
PubMed1987

Effects of increased adrenomedullary activity and taurine in young patients with borderline hypertension.

Recent studies showed that taurine, a sulphonic amino acid, could decrease blood pressure and increase sympathoadrenal tone in DoCA-salt-treated hypertensive rats. To determine whether taurine exerts its antihypertensive action in man in a similar fashion, we studied the effect of oral administration of taurine (6 g for 7 days) on blood pressure and plasma catecholamines in 19 young patients with borderline hypertension in a double-blind, placebo-controlled fashion. Systolic blood pressure in the 10 patients who were treated with taurine decreased by 9.0 +/- 2.9 mm Hg (mean +/- SE; p less than .05 by paired t test), compared with a 2.7 +/- 2.3 mm Hg decrease (NS) in the nine patients treated with placebo and diastolic blood pressure in the taurine-treated patients decreased by 4.1 +/- 1.7 mm Hg (p less than .05) compared with 1.2 +/- 3.0 mm Hg (NS) in the placebo-treated subjects. In the patients receiving taurine plasma epinephrine (E) decreased significantly, with a negligible decrease in plasma norepinephrine (NE). The effect of taurine on plasma catecholamines and the response of plasma E after the stimulation with glucagon was also studied in 12 borderline hypertensive and nine age-matched normotensive subjects. Basal plasma E was significantly higher in borderline hypertensive than in normal subjects, but basal plasma NE did not differ in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗
PubMed1987

Vasodilatory actions of alpha-human atrial natriuretic peptide and high Ca2+ effects in normal man.

To study vascular actions of synthetic alpha-human atrial natriuretic polypeptide (alpha hANP) in man, forearm blood flow (FBF) was measured by strain-gauge plethysmograph during the continuous infusion of 100 ng/min alpha hANP dissolved in 5% dextrose into the brachial artery in healthy subjects. alpha hANP increased FBF, with the concomitant increase in ipsilateral limb venous plasma concentrations of alpha hANP. Overall, there was a significant linear correlation between the decrements of ipsilateral forearm vascular resistance (FVR) during infusions of alpha hANP and initial FVR levels (r = -0.883, P less than 0.01). Moreover, alpha hANP, at the stepwise increasing doses of 20, 100, and 500 ng/min, increased FBF in a dose-related fashion: alpha hANP elicits a concentration-dependent vasodilation of forearm vascular beds. Concomitantly, infusions of alpha hANP caused a dose-dependent increase in ipsilateral limb venous plasma cyclic guanosine monophosphate (cyclic GMP). Overall, there were direct correlations of FBF either to ipsilateral venous plasma alpha hANP (r = 0.724, P less than 0.01) or to cyclic GMP concentrations (r = 0.637, P less than 0.01). Subsequently, isoosmolar CaCl2 solution was infused into the same brachial artery at a rate of 0.09 meq/min, and then, with a 2.5 +/- 0.2-mg/dl increase in ipsilateral venous serum calcium concentrations the incremental responses of both FBF and plasma cyclic GMP to alpha hANP were severely blunted. There was also a significant positive linear correlation between FBF and venous plasma cyclic GMP during infusions of alpha hANP with the simultaneous administration of CaCl2 (r = 0.807, P less than 0.01). Finally, the addition of CaCl2 infusion did not change the slope of the regression line of the FBF-plasma cyclic GMP relationship during infusions of alpha hANP. Evidence presented suggests that alpha hANP acts directly on the forearm vascular beds in man, eliciting its vascular relaxant effect, possibly by increasing cellular levels of cyclic GMP. Moreover, modest elevations of serum calcium inhibit the alpha hANP-dependent vasodilation, possibly through the suppression of cyclic GMP activation.

Adolescent↗
PubMed1987

Spontaneous growth hormone secretion and plasma somatomedin-C in children of short stature.

We studied 17 short prepubertal children, aged 7.5 to 17.0 years (mean +/- SD: 11.7 +/- 2.4) more than 2.0 SD below the mean height for their age and of delayed bone age (M +/- SD: 8.1 +/- 2.3), to clarify their physiological GH secretory status. The mean concentration of GH (MCGH) was calculated and was compared with the subjects' GH responses to insulin and arginine tolerance tests (IATT) and plasma somatomedin-C (SM-C). The mean 24-h MCGH value was 3.2 +/- 1.3 ng/ml (range 1.6-5.5). The mean peak GH response to the IATT was 13.0 +/- 7.5 ng/ml (range 2.4-33.9). In addition to the two patients with abnormally low GH responses to the IATT, seven with normal responses showed low 24-h MCGH values, a small number of GH pulses and low mean GH amplitude. The mean plasma SM-C in all patients was 0.60 +/- 0.20 U/ml. This was significantly lower than that of age-matched children of normal height (p less than 0.001). The 24-h MCGH was significantly correlated with plasma SM-C levels (r = 0.51, p less than 0.05) and with that of the first three hours of sleep at night (r = 0.84, p less than 0.01). These results indicate that: 1) some short children with normal GH response to pharmacological tests secrete a low amount of GH physiologically and 2) blood sampling during the first three hours of sleep as well as 24-hour sampling is suitable in evaluating the physiological secretion of GH.

Adolescent↗
PubMed1987

Value and limitation of gadolinium-DTPA contrast enhancement in the early detection of acute canine myocardial infarction.

This study was performed to determine whether the infarcted myocardium can be distinguished from the nuclear myocardium by gated nuclear magnetic resonance imaging (NMRI) and gadolinium (Gd)-DTPA contrast enhancement in the early hours after coronary artery ligation. Twenty-one dogs were used: three dogs with 3-hr ligation of the left anterior coronary artery (LAD) (group A); six dogs with 3-hr ligation of LAD, followed by 20-30 min of reperfusion (group B); six dogs with 6-hr ligation of LAD (group C); and six dogs with 12-hr ligation of LAD (group D). Gated NMRI was performed at the time of occlusion or reperfusion, followed by intravenous injection of 0.5 mM/kg of Gd-DTPA using a whole body NMR system. The effects of Gd-DTPA on gated NMRI could not be obtained in group A, but significant contrast enhancement after Gd-DTPA administration in T1-weighted image was obtained in four of six dogs in group B, four of six dogs in group C, and five of six dogs in group D. Then NMRI contrast that expresses the signal intensity ratio between the infarcted and normal myocardia showed a significant increase in groups B, C, and D. Thus, gated NMRI with Gd-DTPA has a limitation as to the early detection of acute myocardial infarction, such as in group A, but it may have a supplementary role in the detection of acute myocardial infarction since improved signal intensities between the normal and infarcted myocardium was obtained in groups B, C, and D.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Changes in N-acetyl-B-D-glucosaminidase and B-glucuronidase activities in milk during bovine mastitis.

To determine the N-acetyl-B-D-glucosaminidase (NAGase) and B-glucuronidase (B-Gase) activities in mastitic milk, basic enzyme assay conditions, distribution of NAGase and B-Gase, comparison of their activities with California Mastitis Test scores, and the effects of the milking process on their enzyme activities were examined. The mean NAGase and B-Gase activities in milk macrophages were about threefold higher than those of milk and blood polymorphonuclear cells. Very little NAGase activity appeared to be associated with blood mononuclear cells, whereas a relatively higher B-Gase activity was observed. California Mastitis Test scores of each group (1 to 5) appeared to be well correlated (r = 0.86 for NAGase and 0.92 for B-Gase) with the levels of NAGase and B-Gase activity. The milking process was least effective in the normal milk, but some variations of enzyme activities during milking in mastitic milk were found. Changes in NAGase and B-Gase activities in quarter milk were well monitored during the course of clinical mastitis.

Acetylglucosaminidase↗
PubMed1987

Application of the fluorometric DNA quantitative assay using 4'6-diamidine-2-phenylindole for the evaluation of lymphocyte blastogenic response.

A fluorometric DNA microassay using the fluorescent reagent 4'6-diamidine-2-phenylindole dihydrochloride (DAPI) was developed for evaluating a lymphocyte DNA synthesis assay. Triton X-100 (0.05 per cent) was added to the cultured lymphocytes, then DAPI (0.8 micrograms ml-1) was added as a DNA-specific fluorescent intercalating agent. Results are expressed as fluorescence intensity (FI) and stimulation index. FIs measured by DAPI fluorometric assay were highly correlated with [3H]-thymidine incorporation (r = 0.868, P less than 0.01, n = 28). The method is simple, reliable and widely applicable for evaluating blastogenic responses.

Animals↗
PubMed1986

The role of renal hemodynamics in the antihypertensive effect of captopril.

To evaluate the role of regional hemodynamics in mediating the long-term depressor effect of the converting enzyme inhibitor, captopril, at a low dose (37.5 mg/day), for 2 weeks, its systemic, renal, and forearm circulatory actions were determined in 12 patients with mild to moderate essential hypertension. After administration of captopril, there was a significant decline in mean blood pressure (average -12.1 +/- 1.9%) accompanied by a decrease in systemic vascular resistance (-9.1 +/- 3.3%), but cardiac output did not change. Although forearm vascular resistance was not altered, renal vascular resistance decreased considerably (-17.1 +/- 5.0%). Moreover, there was a highly significant (r = 0.891) correlation between the changes in mean blood pressure and renal vascular resistance. Plasma renin activity increased after therapy as plasma aldosterone decreased, while plasma norepinephrine slightly increased. The change in renal vascular resistance significantly (r = -0.617) correlated with the pretreatment level of plasma renin activity. These findings suggest that suppression of the renin-angiotensin system in essential hypertension induces selective vasodilation in the renal vasculature, which may play an important role in the long-term antihypertensive effect of the converting enzyme inhibitor. This renal vasodilator action appears to be the feature that distinguishes the converting enzyme inhibitor from conventional vasodilator drugs.

Adult↗
PubMed1986

Effect of a parafoveal microlesion made with an argon laser on smooth-pursuit eye movements of monkeys.

The significance of the parafoveal region in processing information about target velocity to initiate ocular pursuit was evaluated by making a small paracentral scotoma in monkeys trained to pursue a slowly moving target. In the experimental paradigms in which the image had to cross the scotoma, the small retinal lesion (greater than 2 degrees) gave a direct effect upon the ability of monkeys to pursue the target motion. The abnormal pursuit was characterized by a marked reduction of eye velocity. Evaluated from the initial portion of the pursuit immediately following the first corrective saccade, the eye velocity was as low as 50 to 60% of the target velocity. The abnormality was more pronounced in slow pursuit (15 to 20 degrees/s) than in fast pursuit (25 degrees/s). The data indicated that the small retinal region at the boundary of the macula plays an important role in sampling target velocity during the initial part of smooth-pursuit eye movement.

Animals↗
PubMed1986

Discharges of Purkinje cells in monkey's flocculus during smooth-pursuit eye movements and visual stimulus movements.

Modulations in discharges of Purkinje cells (P cells) associated with movements of visual patterns were studied in the flocculus of monkeys trained to execute smooth-pursuit eye movements and to suppress optokinetic nystagmus. One class of P cells responded to the movements of visual stimulus regardless of whether the eyes remained stationary (produced retinal-slip velocity) or moved with the stimulus produced eye velocity). These P cells processed high-order information concerning the absolute velocity of stimulus movements and thereby the eye velocity had already been incorporated in the visual responses (visuomotor P cells). The other class of P cells responded to visual inputs resulting from the retinal slip (visual P cells). The majority of visual P cells (82%) also modulated their activities during smooth pursuit. When sinusoidal trackings were executed against a stationary visual background, various types of interactions occurred in the P-cell responses between the converging visual and oculomotor inputs. The type of interaction was related to the preferred direction for the P cell during eye movements and the side of the peripheral receptive field.

Animals↗
PubMed1986

Effect of aging on sensorimotor functions of eye and hand movements.

Changes in coordinated eye and hand movements with aging were studied in normal young and elderly subjects. Electrooculograms, flexor and extensor electromyograms, and potentials representing hand movements were recorded and used to evaluate the performance in aiming tasks. The parameters that reflect motor functions did not change significantly with aging in both eye and hand movements. However, elderly subjects commonly showed increases in reaction times of the initial (open-loop) movements in both eye and hand movements. Interestingly, the time increments were almost equivalent in these two functionally distinct motor systems. The durations of error-correcting (closed-loop) movements also increased significantly with aging in both motor systems. These increases suggest that the aging effects are the manifestation of impairment in the sensory process.

Adult↗
PubMed1986

Relationship between oxidative metabolites of hydrazine and hydrazine-induced mutagenicity.

Hydrazine (Hz) mutagenicity was observed in a test using Escherichia coli B/r strain, WP2 uvrA and was enhanced by the addition of rat liver microsomal fraction containing a generating system, while the enhanced mutagenicity was diminished by the addition of metyrapone to the microsome-free levels. On the other hand, an NADPH-dependent difference spectrum of the metabolic intermediate of Hz-complex, characterized by a maximum level of 448 nm, was also inhibited by metyrapone. The results show that the oxidative intermediates, which are diimide and its precursor, hydrazine free radical [Biochem. Biophys. Res. Commun., 133 (1986) 1086], are responsible not only for hepatotoxicity but also for the enhancement of genotoxicity or mutagenicity.

Animals↗
PubMed1986

Changes in sensorimotor function associated with the degree of bradykinesia of Parkinson's disease.

Changes in coordinated eye and hand movements associated with the progress of bradykinesia were studied in 31 parkinsonian patients and 8 age-matched healthy subjects. Among the parameters expressing the changes in motor behaviour, the interval between the onset of eye and hand movements was most sensitive. This parameter reflected the difference in the progress of the symptom in the two motor systems. An increase in the reaction time of the hand response appeared in patients of grade II bradykinesia; this was observed for eye movements only in patients with grade III (severe) bradykinesia. While the changes in ocular reaction time remained within the physiological range, a lengthening of the reaction time, a reduction in peak velocity, a decrease in the open-loop gain, a prolongation of movement duration, and a slow build-up in EMG activity, appeared from an early stage in hand movement. These signs of motor disturbance may appear eventually in every motor system at an advanced stage, but their development is not synchronous in different motor systems. An analysis of the responses recorded simultaneously from the two motor systems examined made it possible to evaluate the changes in the sensorimotor processes with different grades of bradykinesia. A comparison between reaction times for eye and hand movements may be useful for assessing the degree of bradykinesia in parkinsonian patients.

Adult↗