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Biomedical subjects

H Noda

Publications and source records attributed to H Noda.

At least 289 records · Page 16Linked to original sources
PubMed1986

Mossy fibres sending retinal-slip, eye, and head velocity signals to the flocculus of the monkey.

Discharges of mossy fibres were recorded from the cerebellar flocculus of monkeys trained to fixate a small visual target and to track the target when it moved slowly. The experimental paradigms used were designed to study neural responses to retinal-slip velocity, eye velocity, or head velocity, individually or in combination. Among 485 mossy-fibre units recorded from the flocculus, sixty-four units (or 13%) responded to movement of the visual stimulus in the horizontal plane. Two distinct groups of visual mossy fibres were found: they were designated 'visual units' (thirty-nine/sixty-four units or 61%) and 'visuomotor units' (twenty-five/sixty-four units or 39%). The visual units responded exclusively to the retinal-slip velocity. Stationary fixation was necessary for clear cyclic modulation of activity. Their responses declined when the retinal-slip velocity was reduced by eye movements in the same direction. The responses of the visual units were directionally selective and lagged behind the occurrence of 'turnabouts' (changes in direction of stimulus movement) and their peak discharges also lagged the occurrence of peak velocity. Each visual unit had a limited range of velocity sensitivity; in some units the range covered the velocity range of smooth-pursuit eye movements. The visuomotor units had visual receptive fields in the peripheral retina (outside of the central 10 deg); they received also oculomotor and vestibular signals. When the head was stationary, the visuomotor units responded to the target velocity (or visual stimulus velocity) which is the algebraic sum of the retinal-slip velocity and the eye velocity. Their responses reflected the retinal-slip velocity during stationary fixation and the eye velocity during smooth-pursuit eye movements. The responses to stimulus movements were, therefore, almost identical regardless of whether the eyes remained stationary or moved with the stimulus. In response to sinusoidal stimulus movements, the responses of the visuomotor units frequently preceded the stimulus velocity, and the phase lead relative to the velocity curve increased when the frequency of sinusoidal movements was increased. This reflected a relatively constant lead of neural discharges (circa 125 ms) during various frequencies. When the head was moved, the responses of the visuomotor units were dominated by the head velocity, and discharges in response either to the retinal-slip velocity or to the eye velocity (both in the direction opposite to the head velocity) were occluded.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1986

Discharges of neurons in the dorsal paraflocculus of monkeys during eye movements and visual stimulation.

Extracellular recordings were obtained from 319 input units and 304 Purkinje cells (P-cells) in the dorsal paraflocculus of alert monkeys trained to fixate a visual target. They changed discharge rates with either eye movement, eye position, or visual stimulus movement. Of the 319 input units, recorded in the granular layer or white matter, most were mossy fibers (MFs), but 90 (28%) showed characteristic cellular spikes. The latter units were probably granular cells (p-GC). Of the 319 input units, 163 (51%) showed bursts with saccades (burst units) and 62 (19%) showed a prelude on the average 124 ms prior to the onset of saccade (long-lead burst units). Sixty-five (20%) had tonic activity related to eye position and also showed bursts with saccades (burst-tonic units), and the remaining 29 (9%) showed only tonic activity (tonic units). MFs and p-GCs showed no significant differences in the proportion of each type of unit or in their response properties. The majority of burst units (63%) were pan directional, whereas all long-lead burst units had directional selectivity. The preferred directions of long-lead burst, burst tonic, and directionally selective burst units were found in all four quadrants. Position-related activity was found in 48% of the burst-tonic and tonic units to be linearly related to eye position and to show position threshold. The other units also had position thresholds but their activity was not monotonically related to fixation position. Six climbing fibers (CFs), 32 input units (including 13 p-GC), and 8 P-cells showed cyclic responses during sinusoidal movements of a visual pattern. One class of MF units (57%) responded only to the direction, whereas the others responded to both the direction and retinal-slip velocity. Both CF and P-cell units responded to sinusoidal retinal-slip velocity. Of 67 input units, 23 showed cyclic modulation in firing during sinusoidal eye movements in the horizontal plane. Nineteen were burst-tonic and four were tonic units. They also showed position sensitivity. The phase of the cyclic responses tended to lag behind the eye velocity during low-frequency trackings. Of 237 P-cells, 163 (68.8%) discharged with saccades (burst P-cells), 42 (17.7%) paused with saccades (pause P-cells), and 32 (13.5%) discharged with saccades in one direction and paused in the other (burst-pause P-cells). Position sensitivity was found in 38 P-cells; 12 were burst, 5 were pause, and 10 were burst-pause P-cells. Eleven did not respond with saccades.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1986

Biliary excretion of organic anions in diabetic rats.

Little definitive data are available concerning the effects of insulin deficiency on the hepatic uptake and biliary excretion of endogenous or xenobiotic substances. To expand our understanding of this area, male Sprague-Dawley rats were pretreated with streptozotocin (45 mg/kg i.v.) to induce uncontrolled diabetes. Four to five weeks later, diabetic rats exhibited elevations in serum glucose (640 +/- 13 mg/dl), biliary glucose (307 +/- 35 mg/dl), urine output (166 +/- 11 ml/24 hr), basal bile flow rate (73 +/- 2 microliter/min/kg), liver weight/body weight ratio and bile acid pool size. Polyphagia and generalized muscle atrophy were also evident. Plasma disappearance and biliary excretion of several organic anions were studied after i.v. administration. There were no differences between control and diabetic rats in the plasma elimination and biliary excretion of eosin, phenol-3,6-dibromphthalein disulfonate and sulfobromophthalein. Although hepatic uptake was unchanged, the biliary excretion of amaranth was decreased 30% in diabetic rats. There were no differences in bile flow rate in control or diabetic rats after administration of these four anions. In contrast, administration of indocyanine green, bromcresol green and rose bengal did not depress bile flow in diabetic rats as was observed in control rats. In addition, the rate of maximal biliary excretion was increased by 390, 240 and 151% for rose bengal, indocyanine green and bromcresol green, respectively. Plasma clearance of rose bengal was 65% higher in diabetic rats. Total body clearance and steady-state volume of distribution values for all other anions were not different after induction of diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Amaranth Dye↗
PubMed1986

[Liver regeneration and the immune system. III. Suppressor activity of splenic adherent cells activated in vivo by liver regeneration].

It has been shown in the previous reports the immune system of mice is activated during liver regeneration following partial hepatectomy and lymph node cells activated in vivo suppress the syngeneic mixed hepatectomized liver cell-lymphocyte reaction (sMLHLR). In this report, it is demonstrated that the suppressor activity of lymphocytes in vivo by liver regeneration exists in lymph node T cells and splenic adherent cells, but not in lymph node B cells. This suppressive activity of splenic adherent cells is blocked with indomethacin or aspirin. Each of these compounds in nontoxic doses inhibited macrophage-mediated suppression suggesting that the release of prostaglandins by macrophages played an essential role in inhibiting the sMLHLR.

Animals↗
PubMed1985

Spin trapping of a free radical intermediate formed during microsomal metabolism of hydrazine.

A radical formed during oxidative metabolism of hydrazine in rat liver microsomes was spin-trapped with alpha-phenyl-t-butylnitrone. The trapped species was identified as hydrazine radical by comparison of its ESR parameters and mass spectrum with those of the adduct formed during CuCl2 catalyzed oxidation of hydrazine. The requirement for oxygen and NADPH in the microsomal oxidation and the occurrence of a typical binding spectrum by difference spectroscopy suggest the involvement of the participation of the cytochrome P-450 enzyme system in the formation of hydrazine radical which must be a precursor of diimide during microsomal oxidation of hydrazine.

Animals↗
PubMed1985

Determination of blood concentration of valproic acid--a comparative study of methods.

The substrate labeled fluorescent immunoassay technique (SLFIA method) was examined in terms of clinical utility for the determination of blood levels of valproic acid (VPA) by comparing it to the enzyme-multiplied immunoassay technique (EMIT method). Both accuracy and precision were very high, and the correlation between the two was excellent (r = 0.985). Practically, the presence of hemoglobin in the sample had little influence on the accuracy. Results show that the SLFIA method is a useful means for the determination of blood concentration of VPA in epileptic patients.

Anticonvulsants↗
PubMed1985

The oxygen affinity of mammalian hemoglobins in the absence of 2,3-diphosphoglycerate in relation to body weight.

We studied the oxygenation of mammalian hemoglobins: mouse (Mus musculus molossinus), rabbit (Oryctolagus cuniculus domesticus), Japanese monkey (Macaca fuscata), man (Homo sapiens), sheep (Ovis aries), llama (Lama glama), pig (Sus scrofa domesticus), cow (Bos taurus domesticus) and horse (Equus caballus), in the absence of 2,3-diphosphoglycerate (DPG) and compared their oxygen affinity in relation to the body weight. The negative correlation between body weight and the oxygen affinity of the whole blood, observed by Schmidt-Nielsen and Larimer (1958), was not observed in the absence of DPG. Our results indicated that an adaptive evolution proposed for hemoglobin in terms of its oxygen affinity vs body weight of the animal can only be appreciated with DPG.

2,3-Diphosphoglycerate↗
PubMed1985

Effects of rifampicin and phenobarbital on the fate of isoniazid and hydrazine in vivo in rats.

After the intraperitoneal (i.p.) administration of isoniazid (INH) to male Wistar rats, the liver and plasma levels of hydrazine (Hz) and acetylhydrazine (AcHz), which are hazardous metabolites of INH and well known as mutagens, carcinogens and hepatotoxins, were determined by gas chromatography-mass spectrometry (GC-MS). The levels of Hz in rifampicin (RMP)- or phenobarbital (PB)-pretreated groups were lower than those in the control group, while the amount of AcHz was scarcely altered. In each of the pretreated groups a pronounced increase in the oxidative elimination rate of Hz was observed. These results are of important toxicological significance in INH therapy with RMP, since an active intermediate of Hz seems to be a hepatotoxin.

Acetylation↗
PubMed1985

Significant role of alpha 2-adrenoceptors in coronary artery spasm.

Ergonovine, methoxamine and clonidine were administered intravenously in order to clarify the mechanism of coronary artery spasm in canine experiments. After these administrations, 27.5% of the dogs treated with ergonovine, 59.5% of the dogs treated with methoxamine and 72.7% of the dogs treated with clonidine showed ST segment elevation. The combined application of propranolol with ergonovine or methoxamine could more easily induce ST segment elevation than a single application of ergonovine or methoxamine. Most cases of elevated ST segment returned to the normal after the administration of nitroglycerin and phentolamine. Yohimbine was completely effective for the restoration of normal ST segment. Plasma norepinephrine decreased to 20 +/- 8.0% of the control when ST segment elevation was induced. This is a significantly greater decrease than that seen without ST segment elevation (p less than 0.001). Concomitant with the restoration of normal ST segment, plasma norepinephrine increased after the administration of yohimbine. Methoxamine and clonidine increased (p less than 0.01) and yohimbine decreased (p less than 0.01) coronary vascular resistance. Coronary spasm was visualized on coronary arteriogram after the application of clonidine; also coronary vasodilation was visualized after the administration of yohimbine. These results confirm the hypothesis that coronary artery spasm is mediated by pre- and postsynaptic alpha 2-adrenoceptors.

Animals↗
PubMed1985

The effect of sodium and potassium loading on urinary kallikrein-like activity in young patients with borderline hypertension.

We studied the effects of a potassium supplement on urinary kallikrein excretion in a setting of high sodium intake after sodium deprivation with diuretics in young patients with borderline hypertension. Eleven patients, who took the potassium supplementation during the high sodium diet period, showed lower increments in mean blood pressure with salt loading than 12 patients without the potassium supplementation. In the non-potassium-supplemented patients, urinary kallikrein was increased significantly when plasma renin activity (PRA), plasma aldosterone concentration (PAC), and urinary aldosterone were increased during the diuretic treatment. It was decreased significantly when the other hormones were decreased during the sodium load. During the high sodium diet period, PRA, PAC and urinary aldosterone were greater in the potassium-supplemented patients than in the non-potassium-supplemented ones, but urinary kallikrein excretion was not higher when potassium was supplemented. Thus, the present results did not support the theory that the kallikrein-kinin system may be involved in the natriuretic and antihypertensive effects of potassium. In addition, these finding suggest that some kallikrein-modulating factor(s) may counteract the increased urinary kallikrein excretion with the augmented renin-angiotensin-aldosterone system during salt loading with potassium supplementation.

Adult↗