Search PubMed⌕ Search

Biomedical subjects

T Mano

Publications and source records attributed to T Mano.

At least 109 records · Page 6Linked to original sources
PubMed1998

Characteristic MR features of encephalitis caused by Epstein-Barr virus: a case report.

An 8-year-old girl showed symptoms of encephalitis during acute Epstein-Barr virus (EBV) infection. The diagnosis of EB virus infection was made by changes in the titres of EB virus-specific antibody. Cranial MRI demonstrated abnormal low and high signal intensities in the striatal body (putamen and caudate nucleus) on T1-weighted and T2-weighted images, respectively, during the acute phase. These abnormal findings had almost completely resolved 1 month later. EBV infection should be considered when lesions are localised to the basal ganglia.

Caudate Nucleus↗
PubMed1998

Isolated lissencephaly sequence with balanced chromosome translocation involving 17p13.3.

We describe a patient with isolated lissencephaly sequence (ILS) who had a de novo balanced translocation with breakpoint at 8p11.23 and 17p13.3. She developed infantile spasms and had severe developmental delay. There was no apparent deletion of 17p13.3 on fluorescence in situ hybridization (FISH) analysis. The breakpoint was located centromeric to the Miller-Dieker syndrome (MDS) marker (D17S379), and telomeric to the marker D17S1566, which is located centromeric to the LIS1 gene. This is the second reported case of ILS with balanced translocation. It is suspected that the breakpoint of 17p13.3 in this patient is located in the responsible gene for ILS.

Brain↗
PubMed1998

Effects of thyroid hormone on catecholamine and its metabolite concentrations in rat cardiac muscle and cerebral cortex.

Clinical and experimental data suggest that thyroid hormone affects the actions of catecholamine (CA). However, the serum or tissue levels of CA during thyroid disorders have not been well defined. Accordingly, we investigated the levels of CA and their metabolites in the cardiac muscle, the cerebral cortex, and the plasma of rats with hyperthyroidism and hypothyroidism versus euthyroid animals. The Neurochem analyzer system (ESA, Inc., Bedford, MA) was used in such determinations. The cardiac muscles of hyperthyroid rats exhibited a 16% decrease in the levels of 1-dopa, 3-methoxytyramine (3-MT) and homovanillic acid (HVA) as compared with those in euthyroid rats. The levels of norepinephrine (NE) in cardiac muscle of these rats increased significantly (5.2-fold) relative to the levels in euthyroid rats. NE was undetectable in the cardiac muscles of the hypothyroid rats. Epinephrine (E) and dopamine (DA) were not detected in the cardiac muscles of the rats with either thyroid disorder. Levels of E and 3,4-dihydroxymandelic acid (DOPEG) were detected only in the cerebral cortex of hyperthyroid rats. The cerebral cortex levels of 3-methyoxytyramine (3-MT), 3,4-dihydroxyphenylacetic acid (DOPAC), metanephrine (MN), and homovanillic acid (HVA) were all significantly increased in the hyperthyroid versus the euthyroid rats. The cerebral cortex levels of DA, NE, normetanephrine (NMN), and VMA in the hyperthyroid rats all showed a significant decrease. Levels of NE, NMN, and DOPAC in the cerebral cortex increased significantly in the hypothyroid rats. The level of VMA was undetectable in cerebral cortex of such animals. Data from studies on cardiac muscle and cerebral cortex indicate that the changes in CA and CA metabolites are responsible in part for the cardiovascular and the central nervous system symptoms observed in hyperthyroidism and hypothyroidism.

Animals↗
PubMed1998

Vitamin E and coenzyme Q concentrations in the thyroid tissues of patients with various thyroid disorders.

To clarify the different roles of free radical scavenging systems in various thyroid disorders, we measured the levels of alpha-, beta-, and gamma-tocopherols and coenzyme Q in the thyroid tissues of patients with thyroid tumors and Graves' disease using high-performance liquid chromatography. The levels of alpha-tocopherols and gamma-tocopherols in the thyroid tissue of patients with papillary carcinoma and the level of gamma-tocopherol in the thyroid tissue of patients with malignant lymphoma were elevated compared with those in normal thyroid tissues. The level of coenzyme Q was reduced in the thyroid tissue of patients with Graves' disease and follicular and papillary thyroid carcinomas. These findings imply that vitamin E and coenzyme Q as scavengers play some role in thyroid follicular cell hyperfunction or dysfunction.

Graves Disease↗
PubMed1998

Responses of muscle sympathetic nerve activity to lower body positive pressure.

To evaluate the response of vasomotor sympathetic nerve activity to lower body positive pressure (LBPP), muscle sympathetic nerve activity (MSNA) was microneurographically recorded from the tibial nerve in 10 healthy young men, along with hemodynamic variables and echocardiogram, during exposure to incremental LBPP at 10, 20, and 30 mmHg in the supine position. MSNA was suppressed to a similar extent (27%) at 10- and 20-mmHg LBPP. However, at 30-mmHg LBPP, MSNA tended to increase but was still nearly at the control value. Mean arterial pressure was elevated (11%), total peripheral resistance markedly increased (36%), and stroke volume and cardiac output tended to decrease at 30-mmHg LBPP. Heart rate remained unchanged throughout the procedures. Left atrial dimension significantly increased during 10- and 30-mmHg LBPP, indicating an increased cardiac filling. These results suggest that the inhibitory effect of the cardiopulmonary baroreflex on MSNA at 10- and 20-mmHg LBPP could be counteracted by the sympathoexcitatory effect of the intramuscular pressure-sensitive mechanoreflex at 30-mmHg LBPP. However, the increment of total peripheral resistance at 30-mmHg LBPP may not depend exclusively on this small enhancement of MSNA.

Adult↗
PubMed1998

Gender difference in age-related changes in muscle sympathetic nerve activity in healthy subjects.

Muscle sympathetic nerve activity (MSNA) was measured directly along with blood pressure at rest in 69 healthy women (20-79 yr old) and 76 age-matched healthy men (16-80 yr old). All were nonobese and normotensive. In the women and men the MSNA was positively correlated with age (women: y = 0.788x - 5.418, r = 0.846, P < 0. 0001; men: y = 0.452x + 12.565, r = 0.751, P < 0.0001). The regression intercept of y was significantly lower (P < 0.0001) in the women than in the men, and the regression slope was significantly steeper (P < 0.0001) in the women. The MSNA was lower in women than in men among those <30 (P = 0.0012), 30-39 (P = 0. 0126), and 40-49 yr old (P = 0.0462) but was similar in women and men among those 50-59 (P = 0.1911, NS) and >/=60 yr old (P = 0.1739, NS). The results suggest that MSNA increases with age in women and men and that the activity is markedly lower in young women than in men but is markedly accelerated with age.

Adolescent↗
PubMed1998

Head-up suspension in humans: effects on sympathetic vasomotor activity and cardiovascular responses.

We hypothesized that muscle sympathetic nerve activity (MSNA) and cardiovascular responses to the conventional head-up tilt (HUT) are different from those to head-up suspension (HUS) because of antigravity muscle activity. The MSNA from the tibial nerve, heart rate, blood pressure, stroke volume, cardiac output, and calf blood flow were measured in 13 healthy young subjects. Left atrial diameter was measured by two-dimensional echocardiography in another nine subjects. The resting MSNA and cardiovascular responses at a low level (20 degrees) of orthostasis were similar during both modes. At higher levels (40 and 60 degrees), the responses of MSNA, heart rate, stroke volume, and cardiac output were significantly stronger and there was a smaller reduction in calf blood flow during HUT than during HUS (P < 0.05). Left atrial diameter was decreased significantly from the resting values during HUT and HUS without any significant difference between the modes of orthostasis. The results provide evidence that the engagement of antigravity muscles during HUT may have additive effects on sympathetic vasoconstrictor and cardiovascular responses to orthostatic stress.

Adult↗
PubMed1998

Microneurographic research on sympathetic nerve responses to environmental stimuli in humans.

The sympathetic nervous system plays an important role to maintain the homeostasis of vital functions in humans against environmental stimuli. Sympathetic nerve responses to environmental stimuli in humans have been assessed conventionally using rather indirect methods by analyzing the responses of effector organs or by measuring the changes in plasma norepinephrine level. Meanwhile, the microneurography technique has enabled us to approach the sympathetic nervous system in humans more directly. By applying this technique, it has become possible to investigate how the human sympathetic nervous system responds to different kinds of environmental stimuli. In this paper, the usefulness of microneurography as a research tool in environmental physiology is shown together with a review of microneurographic findings on sympathetic nerve responses to environmental stimuli in humans.

Aging↗
PubMed1998

Sympathetic nerve responses in humans to short and long term simulation of microgravity.

The present paper aimed to review findings obtained by our researches to elucidate sympathetic nerve mechanisms of cardiovascular deconditioning in humans exposed to short and long term simulation of microgravity. Sympathetic nerve activity in humans has been so far investigated using indirect methods by analyzing the activities of effector organs, such as heart rate, blood flow, blood pressure, sweating etc. or by measuring the plasma nor-adrenaline level. Now we have a technique called microneurography which has enabled us to measure directly the sympathetic nerve activity form human peripheral nerves. The microneurography technique was used for the first time before, during and after the Space Shuttle "Neurolab" mission launched in April 1998 to elucidate how sympathetic nerve activity in astronauts is modified by exposure to microgravity in space. In this paper, we would like to present our recent findings concerning sympathetic nerve responses to short and long term microgravity simulated by different methods.

Bed Rest↗
PubMed1998

Changes in muscle sympathetic nerve activity and effect of breathing maneuvers during microgravity induced by parabolic flight in humans.

UNLABELLED: This study aimed to clarify how muscle sympathetic nerve activity (MSNA) in humans, which plays an important role in blood pressure control against gravity, is altered under microgravity (microG) conditions, and how the MSNA change is modified by breathing maneuvers. Ten subjects seated themselves in a jet aircraft with their knees extended. MSNA was recorded microneurographically from the left tibial nerve with simultaneous monitoring of ECG, blood pressure, respiration, and intrathoracic blood volume estimated by the impedance method during parabolic flight in a jet aircraft. In half of the parabolas, their respiration was controlled at 0.25 Hz by a metronome. RESULTS: MSNA was enhanced under hypergravity just before microG entry, and immediately suppressed by microG induced by parabolic flight. The suppression was more marked with controlled than with uncontrolled respiration (51.6 +/- 7.2 vs 82.8 +/- 2.5%, mean +/- SE, 1G=100%). MSNA changes during microG correlated significantly to changes in blood pressure and intrathoracic blood volume. The blood pressure fall 10 to 15 sec after microG entry was less prominent with controlled than with uncontrolled respiration. We conclude that changes in arterial blood pressure and intrathoracic blood volume modulate MSNA during microG induced by parabolic flight, depending largely on breathing maneuvers.

Adult↗
PubMed1998

Muscle sympathetic nerve activity and plasma norepinephrine during 6 degrees head-down bed rest.

Alterations in autonomic function are evident during spaceflight. These conditions are also simulated by ground-based experimental models of a microgravity environment such as 6 degrees head-down bed rest (BR). They include a reduction in baroreflex function, a decrease in vagal tone and a loss of circulatory blood volume during weightlessness. However, it is not clear whether vasomotor sympathetic outflow, which controls peripheral vascular tone neurally, and plasma norepinephrine concentration will change or not during weightlessness. The purpose of the present study is to examine changes in vasomotor sympathetic nerve activity during six days of 6 degrees head-down BR. Vasomotor sympathetic nervous activity was evaluated by the direct recording of muscle sympathetic nerve activity (MSNA) by a use of microneurographic technique. MSNA on the sixth day during BR was the same as that in a horizontally supine position before BR (before BR; 15.4 +/- 1.6 bursts/min, during BR; 16.7 +/- 3.5 bursts/min), though plasma norepinephrine concentrations during BR were reduced by 25% compared with those before BR (before BR; 263 +/- 33 pg/ml, during BR; 193 +/- 79 pg/ml, p < 0.05). This dissociation cannot be determined precisely, but it suggests the possibility of peripheral changes in terminal sympathetic nerve endings, etc.

Adult↗
PubMed1998

Sympathetic nerve response to muscle during anteroposterior acceleration in humans.

This study aimed to elucidate the effects of linear acceleration on muscle sympathetic nerve activity (MSNA) in humans. Eight healthy young male volunteers were seated in a linear accelerator (sled) during the recording of their electrocardiogram, blood pressure with the Finapres, thoracic impedance and respiration curve. MSNA was recorded from the tibial nerve by microneurography. At a fixed distance of sled movements in an anteroposterior direction, eight modes of stimulation with peak accelerations at 0.05, 0.10, 0.15, and 0.20 G (gravity) in sinusoidal or step mode were applied to each subject. Each movement was repeated for 5 cycles. Both the total activity and the burst rate of MSNA decreased during acceleration, and the level of the decrease was proportional to the level of the acceleration, whereas the average heart rate, thoracic impedance and mean arterial pressure did not change significantly. These results suggests that moderate linear acceleration may suppress MSNA in humans.

Acceleration↗
PubMed1998

Effects of lower body positive pressure on muscle sympathetic nerve activity.

To elucidate the role of vasomotor sympathetic nerve activity response to lower-body positive pressure (LBPP), muscle sympathetic nerve activity (MSNA) along with blood pressure, electrocardiogram, transthoracic impedance and echocardiogram were recorded in ten healthy young men at 10, 20 and 30 mmHg LBPP in the supine position. We found that MSNA was suppressed (27%) at both 10 and 20 mmHg LBPP but tended to increase at 30 mmHg LBPP. Mean arterial pressure (11%) and total peripheral resistance (36%) increased despite a tendency toward decreased stroke volume and cardiac output at 30 mmHg LBPP. Heart rate remained unchanged. The left atrial dimension significantly increased during 10-30 mmHg LBPP, indicating an increase in cardiac filling. These results suggest that LBPP at levels less than 20 mmHg suppressed MSNA by the translocation of blood from the lower body to the thorax, thus stimulating the cardiopulmonary baroreceptors which in turn inhibited vasomotor sympathetic nerve activity. However, LBPP at 30 mmHg tended to enhance MSNA through the activation of intramuscular (pressure-sensitive) receptors which could counteract the inhibitory effect of cardiopulmonary baroreflexes on MSNA.

Adult↗
PubMed1998

[A case of juvenile type dentatorubral-pallidoluysian atrophy (DRPLA) with psychomotor retardation since infancy].

We report here a case of an 11-year-old boy with juvenile type of dentatorubral-pallidoluysian atrophy (DRPLA). His psychomotor development has been delayed since infancy and cerebellar ataxia was noted at the age of 2 years, indicating an early onset. At the age of 6 years, he had progressive myoclonus epilepsy (PME) and underwent a series of neuroradiological, electrophysiological and pathological examinations, which failed to reveal the etiology. Gene analysis performed at the age of 11 years revealed an expanded CAG repeat at the DRPLA locus in both the patient and his asymptomatic father. In the absence of a positive family history, a diagnosis of DRPLA may be difficult due to its clinical variability. We conclude that DRPLA should be taken into account in the differential diagnosis of childhood PME and that gene analysis should be performed to confirm a diagnosis of DRPLA.

Anticipation, Genetic↗
PubMed1997

Response to vestibular stimulation of sympathetic outflow to muscle in humans.

The objective of the present study was to determine the effect of vestibular stimulation on the sympathetic outflow to muscle in humans. Fourteen healthy volunteers were studied while in the supine position with electrocardiography, blood pressure monitoring and electro-oculography. The muscle sympathetic nerve activity (MSNA) was recorded directly from the bilateral tibial nerves by using microneurographic double recording technique. Caloric vestibular stimulation was loaded by alternate irrigation with 50 ml of cold (10 degrees C) water and 50 ml of hot (44 degrees C) water into the left and right external meatus. After cold water irrigation, two MSNA response peaks were elicited, respectively, before and after the maximum slow phase velocity (SPV) of nystagmus. The first peak of the MSNA enhancement was caused by non-specific factors because its time course coincided with that in cold pressor test with immersion of the subject's hand in ice/water (4 degrees C). Transient suppression of MSNA after cold water irrigation in the period of maximum SPV of nystagmus was observed by cross correlogram analysis between the SPV of the nystagmus and MSNA. After hot water irrigation, only one MSNA response peak was elicited after the period of strong nystagmus. The second peak of MSNA enhancement evoked by cold irrigation (379.4 +/- 221.8%, with the control value set as 100%, mean +/- SE) was significantly higher than that evoked by hot irrigation (243.0 +/- 14.5%). The degree of MSNA enhancement by either cold (the second peak) or hot stimulation was proportional to the maximum SPV of the nystagmus. There was no significant difference between the MSNA responses ipsilateral to and contralateral to the irrigated side. In conclusion, the caloric vestibular stimulation can influence the bilateral sympathetic outflow to muscle in humans. The degree of MSNA enhancement is proportional to the magnitude of vestibular excitement indicated by maximum slow phase velocity of the nystagmus.

Adult↗
PubMed1997

The recruitment pattern of single vasoconstrictor neurons in human.

The aim of this study is to determine the recruitment pattern among individual vasoconstrictor neurons under the baroreceptor-mediated influence in man. Spikes of single vasoconstrictor units were detected from microneurograms with a template-matching method. A total of 39 single vasoconstrictor units were detected. Single vasoconstrictor units were different from each other in their susceptibility to be activated in response to changes in the R-R interval or blood pressure. The units with higher firing probability had a shorter threshold R-R interval and a higher threshold diastolic blood pressure than units with lower firing probability. In sympathetic responses consisting of only one spike (single-spike responses), units with a lower threshold frequently appeared and units with a higher threshold joined mull-spike responses. The units with a short threshold R-R interval tended to have a long inhibitory latency from R wave, suggesting low conduction velocity. The correlation between firing probability and firing threshold and that between appearance in single-spike response and multi-spike response suggest a hierarchical manner of recruitment of vasoconstrictor units. For beat-to-beat responses, however, some deviation from the hierarchical recruitment was also observed.

Adult↗