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Biomedical subjects

K Kurata

Publications and source records attributed to K Kurata.

At least 163 records · Page 9Linked to original sources
PubMed1985

Distribution of neurons related to a hindlimb as opposed to forelimb movement in the monkey premotor cortex.

Single cell recordings were made from the premotor cortex (lateral part of area 6) of a monkey trained to perform either a distal hindlimb or forelimb movement separately. Out of 175 movement-related neurons, 59 neurons showed modulation of activity only prior to the hindlimb movement, and the majority of them was distributed in a focal region around the superior precentral sulcus, several mm posteromedial to the genu of the arcuate sulcus. The hindlimb focus was separate from a focal region for forelimb movement-related neurons, which lay immediately posterior to the genu of the arcuate sulcus.

Animals↗
PubMed1985

Requirement of methionine for the replication of canine distemper virus in Vero cells.

The replication of canine distemper virus (CDV) in Vero cells was found to require certain amino acids such as arginine, methionine and valine. The deprivation of methionine caused the most marked reduction in virus yield. In cells cultured in medium deprived of methionine, the early processes of viral replication such as adsorption, penetration and uncoating of virus occurred at normal rates, but the syntheses of viral RNA and protein were markedly reduced. The addition of S-adenosylmethionine to methionine-free medium resulted in the growth of CDV to the level obtained in cells with complete medium. Moreover, cycloleucine, which is known to reduce the methylation of mRNA by inhibiting the synthesis of S-adenosylmethionine, also inhibited the growth of CDV, and the addition of methionine or S-adenosylmethionine reversed the inhibitory effect of cycloleucine. The possibility of an inhibition of methylation of mRNA in methionine-deprived cells is discussed.

Animals↗
PubMed1985

Contrasting neuronal activity in supplementary and precentral motor cortex of monkeys. I. Responses to instructions determining motor responses to forthcoming signals of different modalities.

The present report contrasts neuronal activity in two motor cortical fields after instructions that determine which of two sensory signals will trigger a movement and which will not. The goal of the study was to determine possible differential roles of the two cortical fields in the process of preparing to move in response to one external cue and to ignore another. Single-cell recordings were made from the supplementary motor area (SMA) and the precentral motor area (PCM) of monkeys trained to perform key-press movements in two different modes. In the auditory mode, an instruction signal warned the animal to prepare to start the movement promptly in response to a forthcoming 1,000-Hz tone burst (trigger signal), but to remain motionless if the signal was vibrotactile (nontrigger signal). In the tactile mode, the trigger and nontrigger signals were reversed: a different instruction signal warned the animal to prepare to perform the key-press movement in response to the vibrotactile cue, but to withhold it in response to the 1,000-Hz tone. The instruction signals were auditory tones of 300 Hz for the auditory mode and 100 Hz for the tactile mode. Out of 259 task-related SMA neurons, 128 (49%) responded to instructions. Three types of instruction responses were observed: 1) 95 neurons showed continuous instruction-induced activity changes lasting until the occurrence of the movement-triggering signal, regardless of whether an intervening nontrigger signal occurred. 2) 24 neurons showed increased activity until the occurrence of the nontriggering signal, after which the activity subsided. When there was no nontrigger signal, the activity increased during a period when the nontrigger signal might have been given. 3) Nine neurons responded with a transient, short-latency discharge after the instruction. The responses of SMA neurons to two instructions were often different. Forty-four SMA neurons exhibited a selective response to only one of the two instructions. In 43 neurons the response was differential, with the magnitude of activity increase or decrease being at least three times greater after one instruction than the other. In the remaining 41 neurons the response was nondifferential. Out of 112 task-related PCM neurons, 25 (22%) responded to the instructions. In the majority of them (21 neurons), the instruction response was nondifferential.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

Contrasting neuronal activity in supplementary and precentral motor cortex of monkeys. II. Responses to movement triggering vs. nontriggering sensory signals.

This report compares neuronal activity in the supplementary motor area (SMA) and the precentral motor cortex (PCM) in response to auditory and vibrotactile signals that required a monkey either to start a key-press movement or to refrain from initiating such a movement. Confirming previous reports (3, 9), a vibrotactile stimulus that triggered movement gave rise to two phases of neuronal activity in PCM neurons: a short-latency response time-locked to the occurrence of the vibrotactile stimulus, and a response related to the time of onset of the movement. When the animal was required to refrain from moving in response to the vibrotactile signal, the short-latency response was often attenuated and there was rarely any later activity. There was no attenuation of the short-latency response to the nontriggering vibrotactile stimulus in the anterior part of the postcentral somatosensory cortex. As reported previously (23), short-latency stimulus-locked responses of SMA neurons to a vibrotactile signals were less frequent and the magnitude of the responses was smaller than in the PCM. However, the properties of the later-occurring responses of SMA neurons were often different from those of PCM neurons. Many SMA neurons responded to both the triggering and nontriggering vibrotactile signals. Twenty-nine SMA neurons responded to the nontriggering signal only and not to the movement-triggering signal. Most of the PCM neurons were active after the auditory signal only when the signal was a trigger to start the key-press movement; three neurons exhibited a slight activity increase after the nontriggering auditory signal. In contrast, a number of SMA neurons responded to the nontriggering auditory signal as well as the movement-triggering auditory signal. Twenty-three neurons responded exclusively to the nontriggering auditory signal. These results indicate the extent to which SMA neuronal activity, in contrast to that of the PCM, is related to factors other than the execution of movement.

Animals↗
PubMed1984

[A study on relation between premotor cortex and forelimb movement: analysis of neuronal activity].

The aim of this study is, first, to examine the existence of topographical organizations in the premotor cortex in monkeys trained rigorously to move his proximal and distal forelimb separately. The second aim is to observe premotor cortex neuronal activity in association with simple movement triggered by sensory signals of three different modalities (visual, auditory, and somatosensory). Premotor cortex was defined as the lateral part of frontal agranular cortex where intracortical microstimulation could not evoke muscle contraction at intensity below 50 microA. Neurons related to the distal forelimb movement formed three foci in the premotor cortex. Neurons related to the proximal forelimb movement distributed widely in the premotor cortex without forming any distinct focus. Movement-related premotor neurons showed less modulation of discharge frequency in association to the movement than motor cortex neurons, and some of them responded selectively to one or two sensory signals triggering the movement. These results suggests that premotor cortex contributes less directly to the execution of simple movements, but may play an important role in controlling or organizing complex movements.

Acoustic Stimulation↗
PubMed1983

[A simple and direct radioimmunoassay for serum and urinary metanephrine].

A simple, direct and specific radioimmunoassay for serum and urinary metanephrine was developed, in which we used 125I-Synephrine and specific antiserum generated in rabbits by injecting with metanephrine conjugated with bovine serum albumin as described by Grota and Brown. The sensitivity of the assay was 2 pg/tube. Intra- and inter-assay coefficients of variation were 2.6 approximately 7.8% and 5.0 approximately 9.6%, respectively. The recoveries of metanephrine added at two levels of 250 pg/ml and 500 pg/ml to ten serum samples and ten urine samples (hydrolyzed and diluted) were 96.7 and 108% in serum, and 94.8 and 103% in urine, respectively. Normal values of serum metanephrine were 40.3 +/- 25.8 pg/ml (mean +/- SD) from 20 normal subjects. Normal values of 24 hour urinary metanephrine excretion were 12.5 +/- 6.7 ug/day from 24 normal subjects. Serum metanephrine values for 7 patients with pheochromocytoma were 210 approximately 628 pg/ml. Urinary metanephrine values for 9 patients with pheochromocytoma 8.7 approximately 302 ug/day.

Adrenal Gland Neoplasms↗
PubMed1983

Responses of pyramidal tract neurons in the postcentral cortex to tactile inputs.

Pyramidal tract neurons were recorded from postcentral cortex of awake monkeys and their responses to step indentation and vibratory stimulus were studied. The majority of them exhibited slowly adapting response to the indentation stimulus but failed to show phase-locked response to 50-200 Hz vibrations. The response properties appeared to be in contrast to those of non-pyramidal tract neurons whose responses were largely quickly adapting.

Adaptation, Physiological↗
PubMed1982

Alteration of NADH-diaphorase and cytochrome b5 reductase activities of erythrocytes, platelets, and leucocytes in hereditary methaemoglobinaemia with and without mental retardation.

NADH-diaphorase and cytochrome b5 reductase activities of platelets and leucocytes, as well as erythrocytes, were found to be deficient in a patient with hereditary methaemoglobinaemia associated with moderate mental retardation and non-progressive neurological disturbance, in which hyperactive reflexes and involuntary movements were notable. In another methaemoglobinaemic patient with no mental or neurological abnormalities, these enzyme activities were defective in erythrocytes but normal in platelets and leucocytes. The first case was a generalised cytochrome b5 reductase deficiency with non-progressive encephalopathy. It is suggested that the detection of cytochrome b5 reductase activity in platelets, in addition to that in leucocytes, is useful for the assessment of a generalised enzyme defect. Genetical involvement of the present cases is discussed in association with the diaphorase gene loci in humans.

Adolescent↗
PubMed1982

Measurement of plasma renin activity by a simple solid phase radioimmunoassay.

A solid phase RIA in which an antibody adsorbed onto polystyrene balls was developed to determine PRA. Complete inhibition of converting enzyme and angiotensinase during enzymatic reaction was achieved by phenyl methyl sulfonyl fluoride and EDTA combination. Pepstatin A was found to be an effective agent to block angiotensin I generation during the RIA, and the sample can be directly incubated at room temperature for RIA without any special treatment to inhibit renin activity. The intra- and interassay coefficients of variation (CV) were 5.5-6.9% and 3.7-8.2%, respectively. The recovery was 91.9-117% of added angiotensin I. The assay is sufficiently sensitive and reliable for routine use and correlates acceptably (r = 0.996) with an established RIA. The antibody-adsorbed balls were compared to the soluble antibody with respect to thermodynamic parameters. It was found that the apparent equilibrium constant of the antibody-adsorbed ball was reduced to approximately 1/2 sec of soluble antibody, which was predominately due to the decrease in unitary entropy change by adsorption.

Angiotensin I↗
PubMed1982

Evaluation of two different HEDP content kits: stability study against dilution both in vivo and in vitro.

Two different HEDP content kits (Kit A, HEDP: 1 mg, SnCl2. 2H2O: 0.5 mg; and Kit B, HEDP: 10 mg, SnCl2. 2H2O: 0.5 mg) were evaluated for their stability against dilution 99mTc-HEDP solutions prepared from these two kits were diluted from 10 to 6000fold with 0.9% NaCl solution just before evaluation both in vivo and in vitro. In the case of Kit A, significant soft tissue uptake in vivo and released free pertechnetate in vitro were observed by diluting the 99mTC-HEDP solution. On the other hand, 99mTc-HEDP prepared from Kit B was found to be sufficiently stable against dilution. The stability after preparation of each diluted 99mTc-HEDP was also greatly affected by its HEDP concentration. Preliminary analysis of absorption spectra for each 99Tc-HEDP indicated the possibility of two different 99mTc-HEDP complex formation by varied HEDP concentration. These results indicated that a cold reagent like Kit A might cause a higher soft tissue uptake due to its dilution in vivo during a clinical study for bone scanning.

Animals↗