Biomedical subjects

T Mano

Publications and source records attributed to T Mano.

At least 127 records · Page 7Linked to original sources

PubMed1997

Altered response in cutaneous sympathetic outflow to mental and thermal stimuli in primary palmoplantar hyperhidrosis.

Skin sympathetic nerve activities (SSNAs) were recorded simultaneously from the tibial and peroneal nerves by microneurography at an ambient temperature of 25 degrees C in five subjects with primary palmoplantar hyperhidrosis. The resting of the tibial SSNA innervating the sole (glabrous skin) increased moderately (36.5 +/- 1.5 bursts/min), while mental arithmetic provoked marked responses (1,003.3 +/- 457.4% compared with the resting level) in the hyperhidrosis group compared with the control normohidrosis group (n = 5, 25.3 +/ 4.2 bursts/min and 142.2 +/- 58.4%, respectively). Differentiation of the tibial SSNA into sudomotor (innervating sweat glands) and vasoconstrictor (innervating presphincter of skin vessels) revealed that this SSNA enhancement was attributable to not only sudomotor but also vasoconstrictor components during mental arithmetic. In contrast, the responses in the peroneal SSNA (innervating the dorsum pedis, hairy skin) of the hyperhidrosis group were only slightly changed, exhibiting no significant difference from those in the normohidrosis group. Reflex bursts elicited by sound and electric stimulation were normal in amplitude and latency. When the ambient temperature was elevated to 30 degrees C, the tibial SSNAs became more enhanced than did the peroneal SSNAs. The tibial SSNA was markedly enhanced in the hyperhidrosis group (290.0 +/- 78.5%) compared with the normohidrosis group (78.3 +/- 25.4%). We conclude that the excessive responses in SSNA to the plantar glabrous skin to both mental and thermal stimuli may be responsible for the profuse sweating in subjects with primary palmoplantar hyperhidrosis.

Acoustic Stimulation↗

PubMed1997

Effect of heat stress on muscle sympathetic nerve activity in humans.

To elucidate the effect of heat stress on the sympathetic nervous system, we evaluated changes in muscle sympathetic nerve activity (MSNA), plasma arginine vasopressin (AVP), tympanic temperature, skin blood flow, cardiac output, mean blood pressure, and heart rate in 9 subjects in response to acute heat stress induced by raising the ambient temperature from 29 to 34 degrees C and then to 40 degrees C. With the heat exposure, MSNA was significantly increased with a significant increase in tympanic temperature. Skin blood flow and heart rate were also significantly increased, while mean blood pressure tended to decline and cardiac output tended to increase. The combination of the increased MSNA and skin blood flow may have caused the redistribution of the circulatory blood volume from the muscles to the skin, facilitating convection heat loss. The increases in MSNA counteracted the lowered blood pressure during heat exposure. Thus, the increased MSNA may play an important role both in thermoregulation and in the maintenance of blood pressure against heat stress.

Adult↗

PubMed1997

Differentiation of dys- and demyelination using diffusional anisotropy.

We attempted differential diagnosis of dysmyelination and demyelination in childhood using magnetic resonance diffusion weighted imaging. Pelizaeus-Merzbacher disease, one of the dysmyelination disorders, demonstrated diffuse high intensity of the cerebral white matter on T2-weighted images, which demonstrated diffusional anisotropy on diffusion weighted images. On the other hand, high intensity lesions on T2-weighted images in Krabbe disease, one of the demyelination disorders, lost diffusional anisotropy. Another demyelination disorder, Alexander disease-related disorder, also lost its diffusional anisotropy. In contrast to relatively high signal of the lesions on diffusion-weighted images in Krabbe disease (high signal type), the lesions in Alexander disease-related disorder showed low signal on diffusion-weighted images (low signal type). These results suggest that diffusion-weighted images will be clinically useful to differentiate dysmyelination from demyelination; both of them demonstrate similar high intensity lesions of the white matter on T2-weighted images.

Adult↗

PubMed1997

Prediction of the changes in cardiac output in association with preload reduction therapy in patients with hypertensive heart failure.

In treating patients with acute hypertensive heart failure we often try preload-reduction therapy using diuretics or vasodilators, but this may frequently produce a considerable decrease in cardiac output, particularly in hypertensive patients with diastolic dysfunction. Therefore, it is important from the clinical standpoint to predict the change in cardiac output following preload-reduction therapy. The objective of this study was to assess whether the change in cardiac output in association with preload-reduction therapy is predictable before treatment by analysis of mitral flow velocity patterns in patients with hypertensive heart failure. Changes in left ventricular volumes and cardiac output in association with preload-reduction therapy and Doppler echocardiographic parameters of the mitral flow velocity pattern before treatment were studied in 18 patients with hypertensive heart failure. Cardiac output increased in six patients with systolic dysfunction (fractional shortening < 25%). In the other 12 patients (those with normal systolic function), the changes in cardiac output were homogenous among the patients. In this subset there was a greater decrease in cardiac output in patients with a shorter deceleration time. Thus, analysis of deceleration time of the early diastolic filling wave before treatment may be useful in estimating the change in cardiac output following preload reduction in patients with hypertensive heart failure due to diastolic dysfunction.

Adult↗

PubMed1997

Changes in free radical scavengers and lipid peroxide in thyroid glands of various thyroid disorders.

To clarify whether the changes of free radicals and its scavengers are induced by thyroid disorders, we measured levels of free radical scavengers and checked O2 radical generating systems in the human thyroid gland. Thyroid specimens from patients with Graves' disease, follicular adenoma, and papillary and follicular carcinomas contained significantly higher concentrations of xanthine oxidase (XOD) and gluthathione peroxidase (GSH-PX), compared to those in the normal thyroid tissue. Catalase concentration was significantly lower in thyroid specimens from patients with Graves' disease and significantly lower in thyroid specimens from patients with follicular adenoma, compared to those in the normal thyroid tissue. Cu/Zn superoxide dismutase (Cu/Zn SOD) concentration was significantly lower in the specimens from follicular adenoma and papillary carcinoma and Mn SOD concentration was significantly higher in the specimens from papillary carcinoma than those in the normal thyroid tissue. The lipid peroxide concentration, expressed as malondialdehyde (MDA) concentration, was significantly higher in the specimens from papillary carcinoma than those in the normal thyroid tissue. These findings suggest that the levels of free radicals are increased and are scavenged and catalyzed in the thyroid of Graves' disease, whereas free radicals and lipid peroxide are not completely scavenged in papillary carcinoma tissues, suggesting that these substances affect some role in cell function of thyroid tumors.

Adenocarcinoma, Follicular↗

PubMed1997

Insights into the mechanism of the nitroprusside-induced increase in cardiac output in failing hearts: an attempt at its prediction with Doppler echocardiography.

Increased left ventricular (LV) diastolic pressure is consistently decreased by the administration of nitroprusside; however, nitroprusside-induced changes in cardiac output (CO) vary among patients with failing hearts. Although the variation has been considered to be related to interindividual inhomogeneity of LV diastolic performance, nitroprusside-induced changes in CO are not predictable before drug administration in individual subjects. We attempted to clarify whether nitroprusside-induced changes in CO may be predicted by analysis of the mitral flow velocity pattern in failing hearts. LV diastolic pressure was increased by the combination of the decrease in LV function and the volume expansion, and 15 conditions with LV end-diastolic pressure (EDP) > or =15 mm Hg were obtained in 8 dogs. In each condition, pulsed Doppler mitral flow velocity patterns were recorded simultaneously with hemodynamic variables before and during intravenous nitroprusside infusion. After nitroprusside administration, LV systolic pressure and LVEDP decreased in all dogs, and CO increased in eight conditions but decreased in seven conditions. CO was more likely to increase with administration of nitroprusside, and its change was greater in the conditions in which deceleration time of the early diastolic filling wave before nitroprusside infusion was longer (r = 0.56, p<0.05, n = 15). Better correlation was obtained with multiple-regression analysis, using the deceleration time and peak filling velocity at atrial contraction (r = 0.67, p<0.05, n = 15). The deceleration time correlated with LV dynamic compliance (r = 0.66, p<0.01, n = 30). Analysis of mitral flow velocity patterns may be useful in predicting nitroprusside-induced changes in CO in failing hearts.

Animals↗

PubMed1997

Skin sympathetic nerve activity in Guillain-Barré syndrome: a microneurographic study.

To assess autonomic dysfunction, skin sympathetic nerve activity (SSNA) of four patients with Guillain-Barré syndrome was microneurographically studied in the acute and remission phase. Autonomic symptoms such as sinus tachycardia, palmar hyperhidrosis, hypertension, and orthostatic hypotension were present in the acute phase, but all subsided during remission. Basal resting SSNA and the responses to various physical and mental stimuli were all increased in the acute phase and returned almost to normal during remission. Rate of response in sweat rate and blood flow against SSNA were kept proportionally constant during both the acute and remission phases. These findings suggest that some autonomic nerve symptoms of Guillain-Barré syndrome, particularly during the acute phase, are due to increased SSNA.

Acute Disease↗

PubMed1997

Sympathetic outflow to the skeletal muscle in humans increases during prolonged light exercise.

To investigate the effects of exercise duration on muscle sympathetic nerve activity (MSNA), heart rate, blood pressure (BP), tympanic temperature, blood lactate concentration, and thigh electromyogram were measured in eight volunteers during 30 min of cycling in the sitting position at an intensity of 40% of maximal oxygen uptake. MSNA burst frequency increased 18 min after exercise was begun (25 +/- 4 bursts/min at baseline and 36 +/- 5 bursts/min at 21 min of exercise), reaching 41 +/- 5 bursts/min at the end of exercise. Heart rate and systolic BP increased during exercise. Twenty minutes after commencement of exercise, however, both systolic and diastolic BP values tended to drop compared with the initial period of exercise. Tympanic temperature increased in a time-dependent manner, and the increment was significant 12 min after exercise was begun. Blood lactate concentration and integrated electromyogram showed no significant changes during exercise. The increased MSNA during prolonged light-intensity exercise may be a secondary effect of the drop in BP as a result of blood redistribution caused by thermoregulation rather than by metaboreflex.

Adult↗

PubMed1997

Band heterotopia or double cortex in a male: bridging structures suggest abnormality of the radial glial guide system.

A moderately retarded Japanese boy, with a normal male karyotype (46,XY), was diagnosed to have a subcortical band heterotopia or double cortex syndrome. The band heterotopia was relatively thick compared with that of other patients reported. On T2-weighted coronal MR sections, there were numerous radial linear structures between the cortex and the band, probably representing the trace of radial fibers. He had no family members with seizures or mental retardation. Over 50 described patients with this malformation have been female except two patients briefly mentioned by several investigators. Band heterotopia or the double cortex syndrome is inherited as a sex-linked dominant condition. Affected mothers may have affected daughters or sons with lissencephaly, suggesting a link between these disorders. This is the first detailed description of a male with band heterotopia.

Cell Movement↗

PubMed1997

Effects of three days of dry immersion on heart rate and blood pressure variabilities during head-up tilting in humans.

In this study we examined the effects of 3 days of dry immersion on heart rate variability (HRV) and blood pressure variability (BPV) in response to head-up tilting in 4 healthy young subjects aged 21 to 36 years. Resting value of the high-frequency (HF) power of BPV and HRV decreased, while the low-frequency (LF)/HF ratio of HRV and blood pressure increased after the dry immersion. The HF power of HRV decreased, while the LF/HF ratio of HRV and heart rate increased during head-up tilting before and after dry immersion. All powers of BPV and BP were unchanged during head-up tilting. The values of the decrease in the HF power of HRV and the increase in the LF/HF ratio during head-up tilting after dry immersion were larger than those before. These results suggest that 3 days of dry immersion altered the autonomic balance toward the sympathetic dominant at rest, and that cardiac function may play a crucial role in BP maintenance during head-up tilting compared with vasoconstrictor function.

Adult↗

PubMed1997

Sympathetic nerve response to microgravity induced by parabolic flight.

The aim of this study was 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 conditions. Subjects were seated in a jet aircraft with their legs extended. MSNA was recorded microneurographically from the tibial nerve of the sitting subjects with simultaneous monitoring of electrocardiogram, blood pressure, respiration, and intrathoracic blood volume during parabolic flights. In the Air Force training area, the aircraft made parabolas up to 10 times. At the entry to microgravity, intrathoracic blood volume increased, systemic blood pressure was elevated, and MSNA was suppressed. However, this MSNA suppression lasted only 10-15 sec, and then followed by an enhancement to the end of the parabolas. We conclude that MSNA is suppressed at the onset of microgravity during parabolic flight in response to loading of the cardiopulmonary volume receptor due to a cephalad body fluid shift. However, this MSNA suppression is transient during such dynamic gravitational changes as those induced by parabolic flight, probably modulated by arterial baroreceptors.

Adult↗

PubMed1997

A comparison of sympathetic vasomotor and cardiovascular responses to head-up tilt and to head-up suspension in humans.

Muscle sympathetic nerve activity (MSNA) from the tibial nerve, heart rate (HR), respiration and blood pressure (BP) changes were recorded in 7 healthy young adults to investigate the role of antigravity muscle activity on the reflex sympathetic vasomotor and circulatory responses during orthostatic stress. The conventional passive graded head-up tilt (HUT) with a foot-board and the graded head-up suspension (HUS) with a body harness that provide orthostasis without weight bearing by the legs were applied for 3 consecutive, sequential 5-min periods at the levels of 20, 40 and 60 degrees. The resting values and responses to the lower level (20 degrees) of orthostasis by both techniques were similar. However, the changes in MSNA and HR during the HUS at higher levels (40 and 60 degrees) were smaller with a slight increase in mean BP at 60 degrees than the HUT at the same levels and duration (p<0.05). Antigravity muscle activity during the HUT generates tension in the muscles and may activate muscle mechanoreceptors. Therefore, the reflex sympathetic vasomotor activity and circulatory responses to the HUT in humans are probably due to the additive effects of both the baroreflexes and muscle mechanoreflexes.

Adult↗

PubMed1997

Sympathetic control of hemodynamics during moderate head-up tilt in human subjects.

To confirm sympathetic control of hemodynamics during postural change, sympathetic nerve activity supplying the anterior tibial muscle (MSNA) was measured by microneurography and muscle blood flow (MBF) by the xenon washout method during graded head-up tilt from 0 degrees horizontal to 30 degrees in 5 degrees increments. MSNA was represented as the increase in burst rate with increased tilt angle. The increments of MSNA from 0 degree horizontal were statistically significant at all tilt angles. MBF decreased gradually with increasing tilt angle, with no difference noted from 5 to 15 degrees, but a significant decrease between 20 and 30 degrees. Mean blood pressure remained unchanged during graded tilt. The heart rate did not increase until a tilt angle of 10 degrees, with increments becoming significant beyond 15 degrees. These results demonstrated that MSNA plays an important role in hemodynamic regulation during incremental changes in posture, while tilt angle increased HR and other control mechanisms that may be involves.

Adult↗

PubMed1997

Microneurography as a tool to investigate sympathetic nerve responses to environmental stress.

Microneurography is an electrophysiological method to record impulse traffic in human peripheral nerve in situ. Using this method, not only sensory afferent nerve activity, but also postganglionic sympathetic efferent outflow leading to muscle (muscle sympathetic nerve activity-MSNA) and skin (skin sympathetic nerve activity-SSNA) can be recorded in human subjects. In this paper, the methodology of microneurography and following findings obtained by microneurography on sympathetic nerve responses to environmental stress in humans are reviewed. 1. MSNA is enhanced by gravitational stress, while being suppressed by simulated weightlessness through baroreflex mechanism to maintain hemodynamic homeostasis. 2. MSNA is enhanced by simulated high altitude through chemoreflex mechanism. 3. SSNA, which is composed of sudomotor and vasomotor discharges, plays an essential role in thermoregulation. There exist regional differences between SSNA responses to ambient temperature in the nerves innervating hairy and glabrous skin. The function of the sympathetic nervous system in humans has been so far generally analyzed indirectly by observing the effector organ activity or by measuring the plasma noradrenaline level. Meanwhile, a more direct method to approach the sympathetic nervous function in man, called microneurography, has been developed. By applying this technique, it is possible to investigate how the human sympathetic nervous system responds to different kinds of environmental stress (Mano, 1990, 1994). In this paper, the usefulness of microneurography as a research tool in environmental physiology is shown with a review of microneurographic findings on sympathetic nerve responses to environmental stress in human subjects.

Altitude↗

PubMed1997

Effects of positive and negative pressure breathing on muscle sympathetic nerve activity in humans.

To clarify the dynamic effects of short-term continuous positive-pressure breathing (CPPB) and continuous negative-pressure breathing (CNPB) on sympathetic nerve activity, we measured muscle sympathetic nerve activity (MSNA) in the tibial nerve together with blood pressure, heart rate, and central venous pressure (CVP) during spontaneous breathing: 5, 10, and 15 mm Hg (CPPB), and -5, -10, and -15 mm Hg (CNPB) for 5 min, respectively, in six healthy male volunteers. Increasing levels of CPPB at 5, 10, and 15 mm Hg produced increasing levels of MSNA, however, during CNPB, MSNA was virtually constant. Mean blood pressure decreased and heart rate increased during CNPB, while neither factor changed significantly during CPPB. CVP increased during CPPB and decreased during CNPB. These results suggest that CPPB and CNPB do not have the inverse effects on MSNA.

Adult↗

PubMed1997

Fine structure of crest synapses in the locus coeruleus of the Japanese macaque (Macaca fuscata), with special reference to noradrenergic neurons.

The crest synapse and its related structures in the locus coeruleus (LC) of the Japanese monkey, Macaca fuscata, were electronmicroscopically studied using noradrenaline (NA) immunohistochemistry and tannic acid fixation. About 20% to 25% of the noradrenergic input to the LC terminated at noradrenergic neurons. About 1/3 of these NA-NA connections formed crest synapses, although conversely, NA-immunoreactive (IR) terminals were found in 10% of all terminals forming crest synapses. The crests showing parent dendrites were clearly NA-IR, and definite nonNA-IR dendritic crests were not found. Thus, crest synapses were present almost exclusively on noradrenergic neurons in the monkey LC. The crests were composed of parallel postsynaptic membranes 120 to 130 nm in width and 550 to 610 nm in length, accompanied by a thick-dense material of cytoplasm, and regular single rows of electron dense subjunctional bodies which were arranged in approximately 8 transverse rows. A maximum of 12 electron-dense subjunctional bodies per row were counted in the middle section, and decreased bilaterally in number. The crests further contacted with the dendritic spiny processes of neighboring NA-IR neurons. These results suggest that the crest synapse is an evolved and powerful synaptic structure which makes it possible for noradrenergic neurons in the LC to fire simultaneously at a slow and constant frequency depending on the behavioral state.

Animals↗

PubMed1997

Sympatho-vagal responses in humans to thermoneutral head-out water immersion.

To clarify the role of autonomic nervous functions in cardiovascular adaptation to microgravity, heart rate variability (HRV) and blood pressure variability (BPV) were evaluated during thermoneutral head-out water immersion (HOI) of eight healthy young subjects 23 to 31 yr of age. The very low-frequency (VLF; 0.00-0.04 Hz) component of BPV tended to increase during HOI, whereas the low-frequency (LF; 0.04-0.15 Hz) component of BPV and the ratio of LF power to high-frequency (HF; 0.15-0.40 Hz) component (LF/HF ratio) of HRV decreased. The HF component of HRV increased in all the subjects during immersion up to the shoulder. Concomitantly, we found a decrease in heart rate and increases in stroke volume and cardiac output with no significant changes in BP and respiration rate during HOI. These results suggest that both vasomotor and cardiac sympathetic activities are suppressed and that the parasympathetic (vagal) activity is enhanced during HOI.

Adult↗

PubMed1996

Skin sympathetic nerve activity and event-related potentials during auditory oddball paradigms.

Skin sympathetic nerve activity (SSNA) from the tibial nerve and event-related brain potentials (ERPs) were recorded simultaneously during auditory oddball paradigms with a counting task in 10 healthy subjects to elucidate the relationships between the autonomic nervous system and the cognitive process. After the target tones. SSNA bursts were observed more frequently than after the non-target tones. Moreover, the amplitudes of SSNA bursts elicited after the target tones were higher than those elicited after the non-target tones. However, when subjects ignored the series of tones, there was no significant difference between the incidence of SSNA bursts after rare tones and frequent tones. The P300 latencies for the target trials with SSNA bursts were shorter than those for the target trials without SSNA bursts. The average ERP wave forms for the target trials with SSNA bursts showed larger positive deflection in the early part of the P300 component than those for the target trials without SSNA bursts. We conclude that SSNA is generated in relation to the conscious cognitive process, as well as to the reactive automatic process to changes in repeating stimuli. The early part of the P300 component, possibly P3a, may be related to the mechanisms that generate SSNA.

Adult↗