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Biomedical subjects

S Iwase

Publications and source records attributed to S Iwase.

At least 145 records · Page 8Linked to original sources
PubMed1991

Age-related changes of sympathetic outflow to muscles in humans.

Muscle sympathetic nerve activity (MSA) was recorded microneurographically from the tibial nerve in 40 healthy male subjects aged 18 to 75. Passive and graded head-up tiltings were loaded on the subjects. The effects of aging on the resting activity of muscle sympathetic nerve in supine position at rest (burst number per minute), increase in MSA from the resting level by orthostasis (slope of the regression line between sine of the tilt angle and MSA bursts per minute), and the MSA in upright standing position were analyzed. The resting MSA increased with age, and a significant positive correlation was observed between age and resting activity (Y = -6.83 +/- 0.876X, r = .882, p less than .001). The MSA was enhanced by head-up tilt linearly with the sine of the tilt angle, and a significant negative correlation was observed between age and the MSA increase by orthostasis (Y = 57.6 - 0.582X, r = . 843, p less than .001). Standing MSA increased significantly but less remarkably than resting MSA. It was concluded that aging increases the resting activity, but there is less increase in the standing activity of sympathetic outflow to muscles in humans.

Adolescent↗
PubMed1991

Changes in muscle sympathetic nerve activity during sleep in humans.

We microneurographically recorded muscle sympathetic nerve activity (MSA) during sleep in 12 healthy volunteers while simultaneously recording EEG, EOG, ECG, respiration, and blood pressure and determined the number of pulse-synchronous MSA bursts per minute (burst rate) for non-rapid eye movement (nonREM) sleep and rapid eye movement (REM) sleep. MSA decreased during nonREM sleep with progressively deeper sleep stages. During REM sleep, the burst rate of MSA increased and was associated with marked fluctuations in arterial blood pressure. During sleep stage 2, MSA bursts occurred approximately 1 second after spontaneous K-complexes. We conclude that (1) the decreases in MSA during nonREM sleep stages may indicate sleep-stage dependent central suppression of MSA activity; (2) increases in MSA during REM sleep suggest instability of the autonomic nervous system; and (3) a common pathway may exist for MSA bursts and K-complexes.

Adolescent↗
PubMed1991

Postprandial hypotension: microneurographic analysis and treatment with vasopressin.

To clarify the mechanism of postprandial hypotension (PPH), we made microneurographic analyses of patients with PPH and 10 healthy controls by recording multi-unit vasoconstrictive impulses of muscle sympathetic nerve activity (MSNA) directly from the tibial nerve fascicles during a glucose tolerance test. Oral intake of 75 grams glucose in 225 ml of water produced significant and prolonged hypotension in all patients and an increase in MSNA in all healthy subjects. Insulin and glucose responses were not significantly correlated with arterial blood pressure reduction. PPH was prevented by an infusion of vasopressin (0.3 U/min) given before glucose intake. These results suggest that PPH is caused by the lack of sympathetic compensation for the systemic hypotensive stress of splanchnic blood pooling that occurs after food ingestion, and that prior treatment with vasopressin reduces the portal venous flow by constricting the splanchnic vessels in patients with PPH.

Adult↗
PubMed1991

Muscle sympathetic nerve responsiveness to static contraction is not altered under hypoxia.

The purpose of this study was to determine if response in muscle sympathetic nerve activity (MSNA) to static muscle contraction alters or not during peripheral chemoreceptor stimulation with hypoxia. MSNA was recorded from the tibial nerve using a microneurographic technique in seven healthy subjects in a sitting position. They performed a static handgrip exercise (SHG) for 2 min under normobaric normoxia and hypobaric hypoxic conditions corresponding to an altitude of 4,000 m (460 mmHg). MSNA represented as burst rate and total sympathetic nerve activity (TSNA) (burst rate X mean burst amplitude) at rest increased by 7.7 bursts/min and by 60%, respectively, compared to those under normoxia. During the exercise, MSNA increased over control values before exercise both under normoxia and hypoxia. TSNA increased during the first and second minute of SHG by 19% (p greater than 0.05) and 35% (p less than 0.05) in normoxia and by 15 (p greater than 0.05) and 34% (p less than 0.05) in hypoxia over the control value, respectively, while the absolute intensity of MSNA during SHG was higher under hypoxia. The response of MSNA to SHG which showed algebraic sums was the same under normoxia and hypoxia, that might relate to consist of afferent pathways independent from carotid chemoreflex.

Adult↗
PubMed1991

[Effects of muscle relaxant E-0646 on human stretch reflex and responses].

The experiment examined the effects of a muscle relaxant E-0646 on short latency stretch reflex (SLR) and long latency stretch responses (LLRs) of lower leg muscles in 5 healthy male subjects, aged 24-41 years. An AC servomotor produced an ankle rotation of comfortably seated subjects in the direction to stretch the triceps surae muscle for the SLR and the tibialis anterior muscle for the LLRs. Following control measurements, after the oral administration of 50, 100, 150, and 300 mg of E-0646, the SLR and LLRs were recorded every 2 hours for 4 or 6 hours with simultaneous blood sampling to measure E-0646 plasma levels. Electromyograms (EMGs) of the soleus and tibialis anterior muscles were recorded with surface electrodes on each muscle belly. A precision potentiometer was used to measure the ankle angle. The soleus SLR, evoked by a torque pulse (7 msec duration) of one of 5 different amplitudes, decreased 2 hours after the 300 mg administration. A SLR decrease was also found in a simple relationship between the integrated SLR EMG and the angular velocity at 20 msec after the torque onset, in which the slope and intercept of the relationship changed. The plasma E-0646 level roughly correlated with the SLR decrease. No significant change of the SLR was observed when dosage was less than 150 mg. The LLRs of the tibialis anterior muscle were tested under the instruction "resist when perturbed" during a weak isometric contraction against a constant plantar flexion torque.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Low frequency components of the body's center of gravity and blood circulation.

The purpose of this study was to clarify how low frequency components of the body's center of gravity, mainly 1 minute waves (1-MWs), are related to the mechanism of compensation for the venous blood pooling in the legs during static standing in humans. The 1-MWs of foot pressure center, oscillations of body circumferences and other parameters were analyzed with cross-power spectral analysis. The 1-MW of the calf's blood volume propagated to the chest via the venous system. This was inversely synchronized with the 1-MW of the body's center of gravity. It was speculated that muscular pumping of the calf related to the 1-MW of the body's center of gravity might be compensating for the venous blood pooling in the legs.

Adult↗
PubMed1991

[Altered expression of protooncogenes during clinical course in an AML case transformed from MDS].

The changes of expression of oncogenes in the mononuclear cells of MDS case was studied during his clinical course, in series. His bone marrow was considered to maintain its function partly in initial stage, since both peripheral blood and bone marrow responded to clinical episodes. However, his hematopoietic function was gradually impaired with the disease evolution to AML. We examined the expression of four oncogenes in the mononuclear cells of his three clinical stages, early RAEB-t, RAEB-t and AML, to study the cause of transformation from MDS to AML. Early RAEB-t cells expressed all oncogenes studied other than c-myb, while only c-myc was weakly observed in RAEB-t. AML cells expressed c-myc, c-jun and c-myb, except for c-fms. The expression of c-fms and c-jun of early RAEB-t was considered to reflect the monocytosis induced by infections, and the expressions of c-myb and c-myc of AML cells were regarded as one of malignant signs of tumor transformation. These findings suggest that the evolutional transformation of MDS to AML was affected by the altered expression of oncogenes.

Anemia, Refractory, with Excess of Blasts↗
PubMed1990

Identification of sudomotor activity in cutaneous sympathetic nerves using sweat expulsion as the effector response.

In a warm environment at ambient temperatures between 25 degrees and 38 degrees C (relative humidity 50%-60%) the relationship between sympathetic activity in cutaneous nerves (SSA) and pulses of sweat expulsion was investigated in five young male subjects. The SSA was recorded from the peroneal nerve using a micro-electrode. Sweat expulsion was identified on the sweat rate records obtained from skin areas on the dorsal side of the foot, for spontaneous sweating and drug-induced sweating, using capacitance hygrometry. Sweat expulsion was always preceded by bursts of SSA with latencies of 2.4-3.0 s. This temporal relationship between bursts of SSA and sweat expulsion was noted not only in various degrees of thermal sweating but also in the sweating evoked by arousal stimuli, or by painful electric stimulation. The amplitude of the sudomotor burst was linearly related to the maximal rate of increase of the corresponding sweat expulsion, the amplitude of the expulsion and the integrated amount of sweat produced for the duration of the expulsion. The results provide direct evidence that sweat expulsion reflects directly centrally-derived sudomotor activity.

Adult↗
PubMed1990

Skin sympathetic activity in the tibial nerve triggered by vibration applied to the hand.

The effect of vibration applied to the hand on skin sympathetic activity (SSA) in the lower limbs was studied in five healthy subjects. SSA from the right tibial nerve at the popliteal fossa, plethysmogram from the right index toe and perspiration from the sole of the right foot were measured when vibration of 100 m/s2 at 60 Hz was applied to the left palm for 1 min. The SSA response to vibration exposure differed among subjects, but every subject showed an increase in SSA from the tibial nerve when vibration was applied to the hand. Decrease in amplitude of plethysmogram from the toe was also found in all subjects. One subject displayed a remarkable increase in perspiration on the sole of the foot together with a great increase in SSA. The present findings indicated that even vibration exposure of the hand triggers sympathetic activity in the tibial nerve innervating the foot, and causes vasoconstriction of the toe and perspiration on the sole of the foot.

Adult↗
PubMed1990

Changes in muscle sympathetic nerve activity and calf blood flow during static handgrip exercise.

To test the function of sympathetic vasco-constrictor nerves on blood flow in resting limbs during static muscle contraction, muscle sympathetic nerve activity (MSNA) to the leg muscle was recorded from the tibial nerve microneurographically before, during and after 2 min of static handgrip (SHG). Simultaneously, calf blood flow (CBF) was measured by strain gauge plethysmography. An increase in MSNA, a decrease in CBF and an increase in calf vascular resistance (CVR) in the same resting limb occurred concomitantly during SHG. However, the increase in CVR was blunted in the second minute of handgrip when MSNA was still increasing. The results indicated that the decrease of CBF during SHG reflects the increase in MSNA, while the dissociation between MSNA and CVR at the later period of SHG may be related to metabolic change produced by the vasoconstriction.

Adult↗
PubMed1990

Heat-induced finger vasoconstriction controlled by skin sympathetic nerve activity.

Finger blood flow (BF) and skin sympathetic nerve activity (SSA) to the glabrous side of the hand were measured during immersion of the hand in a water bath in which temperature (Tw) was raised every 10 min by steps of 2 degrees C from 35 or 37 to 41 degrees C. The experiments were conducted during the summer in rooms in which ambient temperature was 28-32 degrees C or 35 degrees C. The nine healthy male subjects were wearing summer clothes. Finger BF through vessels located deep in the skin was measured by using laser-Doppler flowmetry (ALF-2100, Advance). With the use of a tungsten microelectrode SSA was recorded directly from the median nerve at the wrist or antecubital fossa of the tested arm. With finger vessels already dilated at Tw of 35 or 37 degrees C, finger BF decreased, with a concomitant increase in the SSA bursts as Tw rose to 39-41 degrees C. We confirmed in one subject that anesthetic blockade of the median nerve at the site proximal, but not distal, to the recording site blocked responses to the step rise in Tw in the SSA bursts and in finger BF. From these results we conclude that, with the subject in a warm state, blood vessels of the finger respond to local heating with vasoconstriction, and this finger vasoconstriction is evoked reflexively, largely through the increased sympathetic outflow to the resistance vessels of the finger.

Adult↗
PubMed1990

[A microneurographic analysis of minor reflex sympathetic dystrophy with increased skin sympathetic activity--report of a case].

A 48-year-old man developed swelling, redness, and allodynia in his left palm. Routine physical and neurological examinations revealed no abnormal findings except for left palmar hyperhidrosis. A clinical diagnosis of minor reflex sympathetic dystrophy with causalgia was made. Skin sympathetic activity (SSA), dominating palm sweating and skin vasoconstriction, and discharges of single afferent fiber from the rapidly adapting-type I (RA-I) unit were recorded microneurography from the median nerve at the cubital fossa. SSA obtained from the affected side was significantly increased compared with that from the normal (right) side. The receptive field of RA-I unit in this case was larger than those of normal controls. Enlargement of the receptive field might suggest presence of collateral sprouting in the injured nerve fibers. Allodynia in the left palm was suspected to be resulted from misdirect sprouting between A alpha . beta to A delta . C fibers. Excessive sympathetic out flow to the skin is considered to be the cause of palmar hyperhidrosis, swelling with redness, and lowered pain threshold, since pain threshold is under regulation of SSA. It is concluded that these sensory and autonomic symptoms were resulted from increased sympathetic out flow to the skin and collateral sproutings in the peripheral nerve fibers.

Humans↗
PubMed1989

A rare case of recurrent vasodepressive attacks of 2-hours duration: analysis of the mechanism by muscle sympathetic nerve activity recording.

Muscle sympathetic nerve activity was recorded in a 57-year-old male patient suffering from severe hypotensive attacks with bradycardia for 10 years. Continuous blood pressure recording demonstrated frequent drastic falls in pressure. Disappearance and reappearance of muscle sympathetic nerve activity coincided with the onset and termination of attacks. Awakening from sleep or emotional and/or cardiovascular stress seems to trigger hypotension. Cardiac pacemaker was not useful in limiting the attack, because right ventricular pacing caused abrupt falls in both blood pressure and heart rate.

Bradycardia↗
PubMed1989

Simultaneous determination of reducing monosaccharides by capillary zone electrophoresis as the borate complexes of N-2-pyridylglycamines.

Reducing monosaccharides were derivatized to N-2-pyridylglycamines and separated as their borate complexes by capillary zone electrophoresis, using a capillary tube (50 microns i.d., 65 cm) of fused silica containing 200 mM borate buffer (pH 10.5) as carrier. The derivatives of 12 saccharides were completely separated in ca. 25 min, with high resolution, at an applied potential of 15 kV. On-column uv monitoring allowed detection of these derivatives at the 10-pmol level, and quantification by the relative peak area method allowed reproducible determination of these saccharides at least in the concentration range of 10-100 mM in reaction solutions. This method was applied to the determination of the monosaccharide compositions of various carbohydrate materials to demonstrate its usefulness.

Aminopyridines↗
PubMed1989

Factors causing hyperkalemia in premature infants.

In order to clarify the causative factors of hyperkalemia in premature infants, 48 newborn infants less than 2000 gm birthweight were examined during the first 48 hours of life. They were divided into two groups: group A (n = 19), which had more than 7 mEq/liter of serum potassium level, was defined as a hyperkalemic group; group B (n = 29) had less than 6.9 mEq/liter of serum potassium level throughout this study period. In group A hyperkalemia occurred on the first day of life and continued throughout the study period. Five of group A infants had arrhythmia, one of whom died from cardiac arrest on the second day of life. Laboratory findings (serum creatinine, creatine phosphokinase, electrolytes, blood gas analysis, calorie balance, and renal function) were compared between the two groups. On the first day of life, serum creatinine and creatine phosphokinase concentrations were significantly elevated and calorie intake was decreased in group A when compared with group B. On the second day of life, calorie intake, urine volume, creatinine clearance, and base excess were significantly decreased in group A. A significant decrease was observed in the serum calcium level in group A on the second day of life when compared with admission data. These data suggest that neonatal hyperkalemia may occur in the sick newborn infants with renal dysfunction when combined with metabolic acidosis and catabolic state.

Acidosis↗
PubMed1989

Relationship between plasma atrial natriuretic peptide concentrations and cardio-thoracic ratio during the early neonatal period.

Twenty-seven neonates were examined at 2.6 +/- 1.5 hours of age (stage 1) and 21 +/- 4.9 hours of age (stage 2) to clarify the relationship between cardio-thoracic ratio (CTR) on chest roentgenograms and plasma atrial natriuretic peptide (ANP) concentration. Among 22 infants who showed elevated plasma ANP, 14 had gained body weight (group A), while 8 other infants had lost weight (group B) at stage 2. The remaining 5 infants had decreased plasma ANP concentrations combined with weight loss at stage 2 (group C). All infants of group B had a patent ductus arteriosus. The plasma ANP concentration and CTR of groups A and B increased during the study period, while those of group C decreased. A linear relation was found between plasma ANP concentration and CTR in all cases (p less than 0.02). This study indicates that increased plasma levels of ANP are associated with an increased CTR.

Atrial Natriuretic Factor↗
PubMed1989

Role of atrial natriuretic peptide in the diuresis of a newborn infant with the syndrome of inappropriate antidiuretic hormone secretion.

A fullterm infant had fetal distress and stained amnion. He underwent an exchange blood transfusion at 12 hours after birth because of hyperbilirubinemia. He developed oliguria combined with high urine osmolality during the first 27 hours of life despite normal creatinine clearance. The diagnosis of the syndrome of inappropriate antidiuretic hormone secretion (SIADH) was made on the basis of high urine osmolality, low plasma osmolality and elevated plasma arginine vasopressin (AVP) concentration. We determined the plasma atrial natriuretic peptide (ANP) concentration for the first 4 days of life. After 27 hours after birth, urine volume increased while plasma AVP concentration remained high. On the other hand, plasma ANP concentration gradually increased after 27 hours of life. We speculate that ANP may play an important role in producing the spontaneous diuresis in the newborn infant with SIADH.

Atrial Natriuretic Factor↗