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Biomedical subjects

M Shindo

Publications and source records attributed to M Shindo.

At least 235 records · Page 13Linked to original sources
PubMed1987

Evidence for mutual inhibition of opposite Ia interneurones in the human upper limb.

The H-reflex technique was used to collect indirect evidence for changes in excitability of the interneurones mediating reciprocal Ia inhibition between wrist extensors and flexors. Stimulating the radial nerve results in an inhibition of the flexor carpi radialis (FCR) H-reflex and evidence has previously been presented that the early phase of inhibition is mediated by extensor-coupled Ia interneurones (Ext Ia INs), i.e. by inhibitory interneurones fed by muscle spindle Ia afferents from wrist extensors. Variations in the level of this inhibition were used to assess changes in excitability of Ext Ia INs. Stimulation of group I fibres from flexors was shown to depress the "reference" Ia inhibition, i.e. to inhibit the Ext Ia INs. The central latency of this interneuronal inhibition was compatible with a disynaptic linkage between flexor Ia afferents and Ext Ia INs. Its threshold and time course profile could almost exactly be superimposed on those of reciprocal Ia inhibition from flexors to extensor carpi radialis (ECR) motoneurones (MNs). This suggests that the Ia inhibitions to extensor MNs and extensor Ia INs are collateral effects mediated by the same flexor-coupled Ia interneurones. In two subjects, in whom it was possible to elicit an H-reflex in the ECR, inhibition of flexor-coupled Ia interneurones by activation of extensor Ia interneurones could similarly be demonstrated.

Adult↗
PubMed1987

Physical work capacity and effect of endurance training in visually handicapped boys and young male adults.

The purpose of the present study was to evaluate the relationship between several physical fitness parameters and eyesight divided into 3 grades in visually handicapped boys and young male adults, and to investigate the effect of mild exercise training on physical and psychic symptoms as well as cardiorespiratory fitness. Four subjects were totally blind (TB), 6 were semi-blind (SB) and 27 had amblyopia (AM). Physical fitness tests consisted of maximal oxygen uptake (Vo2max), maximal pedalling speed and power, maximal stepping rate, and isometric knee extension strength. Compared with AM and SB groups, the TB group was inferior in all physical fitness parameters. Especially, Vo2max, in TB (26 ml.kg-1.min-1) was about 56% of that in age-matched Japanese sighted subjects and was significantly low compared with the AM and SB groups. Both muscle strength and maximal pedalling power corresponded to about 50% that of the age-matched sighted group. Six SB and 4 TB students (mean = 17.7 years) were trained for 6 weeks on a bicycle ergometer at an intensity of 50% VO2max. Training was undertaken for 3 days per week and maintained for 60 min per session. After training, physical and psychic symptoms determined by the Cornell Medical Index improved significantly. These results indicate that low physical work capacity in visually handicapped boys and young male adults is due to the lack of physical activity, and that mild endurance training is effective in improving physical and psychic symptoms as well as cardiorespiratory fitness.

Adolescent↗
PubMed1987

Changes in presynaptic inhibition of Ia fibres at the onset of voluntary contraction in man.

1. Two independent methods were used, in man, to assess changes in presynaptic inhibition of I a terminals at the onset of selective voluntary contractions: (1) measurement of the amount of heteronymous monosynaptic I a facilitation (from the quadriceps muscle to soleus motoneurones) to provide an assessment of the amount of ongoing presynaptic inhibition exerted on the I a fibres responsible for the facilitation; (2) measurement of the inhibition of H reflexes 40-60 ms after a short vibration to the tibialis anterior tendon to estimate the excitability of the interneurones mediating presynaptic inhibition from tibialis anterior I a afferents to the I a afferents of the test H reflex (soleus or quadriceps). 2. At the onset of an isolated voluntary plantar flexion of the foot (gastrocnemius-soleus contraction) the heteronymous facilitation from quadriceps to soleus was increased, reflecting a decreased presynaptic inhibition of the quadriceps I a terminals on soleus motoneurones. Vibratory inhibition of the soleus H reflex was decreased, reflecting an inhibition of transmission of presynaptic inhibition to homonymous soleus I a afferent terminals. 3. At the onset of the same gastrocnemius-soleus contraction there was, on the contrary, an increased vibratory inhibition of the quadriceps H reflex indicating a facilitation of transmission of presynaptic inhibition to homonymous quadriceps I a afferent terminals. 4. At the onset of an isolated voluntary knee extension (quadriceps contraction) the opposite pattern was seen: the heteronymous facilitation from quadriceps to soleus was decreased and the vibratory inhibition of a soleus H reflex was increased, whereas the vibratory inhibition of the quadriceps H reflex was decreased. 5. These results indicate that presynaptic inhibition of I a afferent terminals on motoneurones of contracting muscles is decreased, permitting I a activity to contribute to excitation of voluntarily activated motoneurones. On the contrary, presynaptic inhibition of I a fibres to motoneurones of muscles not involved in the contraction is increased. It is argued that the former must be supraspinal in origin. 6. It is concluded that the control of presynaptic inhibition of I a fibres at the onset of movement may be organized so as to aid in achieving selectivity of muscle activation, i.e. so as to increase motor contrast.

Adult↗
PubMed1987

Antihypertensive and volume-depleting effects of mild exercise on essential hypertension.

After a general clinical observation period of over 4 weeks, 20 essential hypertensive subjects (Japanese) were randomly divided into two groups. One group (n = 10; 4 men and 6 women; 51.4 +/- 2.8 years of age) agreed to physical training using bicycle ergometer exercise with the intensity at blood lactate threshold for 60 minutes three times a week for 10 weeks, while the other group (n = 10; 4 men and 6 women; 51.0 +/- 2.9 years of age) did no particular physical training and was followed once a week as the control. Changes in blood pressure, hemodynamics, and humoral factors of the exercised group were compared with values in the controls. The following significant changes were found only in the exercised group. Blood pressure was significantly (p less than 0.01) reduced. Whole blood and plasma volume indices were significantly reduced (p less than 0.05, p less than 0.01, respectively). The change in ratio of serum sodium to potassium positively correlated with the change in systolic blood pressure (r = 0.76, p less than 0.02). Plasma norepinephrine concentrations both at rest and at the workload of blood lactate threshold during graded exercise tests were significantly reduced (p less than 0.05, p less than 0.02 respectively) after 10 weeks of exercise training. The change in the resting level of plasma norepinephrine positively correlated with that in the mean blood pressure. No such changes were observed in the control group. In both groups, body weight and urinary sodium excretion showed no statistically significant changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Effect of mild aerobic exercise on serum lipids and apolipoproteins in patients with coronary artery disease.

The effects of mild aerobic exercise on serum lipids, apolipoproteins and lecithin-cholesterol acyltransferase (LCAT) activity were examined in 11 male patients with coronary artery disease and 4 healthy male controls. The mild aerobic exercise program involved exercise intensity at 50% of maximal oxygen uptake, as determined from the blood lactate threshold, for 60 min periods 3 times per week for 10 weeks. Following mild aerobic exercise, serum levels of high density lipoprotein cholesterol (HDL-C) were increased significantly from 50 +/- 7 mg/dl to 59 +/- 11 mg/dl (p less than 0.05) with a simultaneous increase in apolipoprotein A-I (apo A-I) in normal controls. The LCAT activity was significantly increased from 65 +/- 22 nmol/ml/hr to 99 +/- 30 nmol/ml/hr in normal controls (p less than 0.05). Furthermore, maximal oxygen uptake (VO2max) was significantly increased in normal controls. In contrast, no significant changes were found in HDL-C, apo A-I, apo B, VO2max and body weight in patients with coronary artery disease. There was significant correlation between the initial HDL-C level and the change in HDL-C level following the exercise program in the combined group of normal controls and patients with coronary artery disease.

Aerobiosis↗
PubMed1987

Echocardiographic and electrocardiographic measures in obese children after an exercise program.

The influence of an exercise training on anthropometric changes and cardiac dimensions was studied in 18 obese children (age 10 to 11 years). Eighteen obese children participated in a jogging program, 5 days/week, for 1 or 2 years and 15 normal weight children (age 10 to 11 years) in the control group participating in their regular physical education class. Anthropometric measurements, echocardiograms and electrocardiograms were obtained before and after the exercise programs. The weight, degree of obesity and resting heart rate had decreased after 1 year of the exercise training. Left ventricular end-diastolic dimension increased after 1 year of the exercise training. Left ventricular wall thickness did not change. The total voltage in SV1 + RV5 decreased after 3 months of the exercise training but returned to pre-training voltage after 1 year of training. There was no change after 2 years of training. In conclusion, 1 year of exercise in obese children decreased resting heart rate and increased left ventricular end-diastolic dimension and left ventricular mass.

Anthropometry↗
PubMed1987

[Fourteen cases of mucosal melanomas of the oral cavity].

Fourteen cases of mucosal melanomas of the oral cavity were treated from January, 1970 to April, 1986 in our department. The patients were 10 males and 4 females and in their fifth and sixth decades with the primary sites in the upper gingiva and palates in the majority. The 3 and 5 year survival rates were 21.4% and 14.3% respectively, with unfavorable prognosis in comparison with cutaneous melanoma. The clinical stages were as follows: stage Ia (1), Ib (8), II (5), which affected the prognosis. The depth of invasion, as described by Breslow et al., were beyond 1.50 mm except in one case, which might be a significant prognostic factor in the study of mucosal melanoma of the oral cavity. Seventy one percent had neck node metastases and 35% had distant metastases. The high occurrence of metastases might be related to their poor prognosis.

Adult↗
PubMed1987

A long-term aerobic exercise program decreases the obesity index and increases the high density lipoprotein cholesterol concentration in obese children.

The effects of long-term supervised aerobic exercise on the body weight, serum lipids and high density lipoprotein cholesterol (HDL-C) were studied in 41 obese children (21 boys, 20 girls) initially aged 11-years-old. The 2 year training program was performed during the daily school life. The intensity of training consisted of running 20 minutes seven times per week at a pace which corresponds to the blood lactate threshold. No dietary intervention was done. The obesity index significantly decreased after 1 year of aerobic exercise in both boys and girls by 55 percent and 48 percent respectively. Since the lean body mass increased throughout the 2 year study while the total body weight decreased, the weight loss is attributed to a decrease in fat. The concentration of HDL-C significantly increased in both boys and girls in the first year, 16 percent and 19 percent respectively and was a slightly lower value in the second year. After 2 years a significant reduction in the girls' serum triglyceride concentration was observed. However, the total cholesterol in serum was unaltered in either boys or girls throughout the 2 year study. In conclusion, a long-term supervised aerobic exercise program in obese children is beneficial and resulted in significant weight reduction with concomitant improvement of lipoprotein metabolism.

Child↗
PubMed1986

Effect of acute exercise on plasma immunoreactive-atrial natriuretic factor.

The effect of acute exercise on plasma immunoreactive-atrial natriuretic factor (IR-ANF) was studied in 5 healthy young males subjected to graded exercise on a bicycle ergometer at four different work intensities (approx. 30, 50, 70, and 90% VO2max respectively). Except for the final exercise period, which was continued until exhaustion, all the others were of 30 min duration. Venous blood samples were obtained in the last 2 min of each exercise period. The plasma IR-ANF response to exercise was similar to that of heart rate and systolic blood pressure in that mild exercise in the first stage (corresponding to approx. 30% VO2 max) caused a striking increase of plasma IR-ANF concentrations with a further augmentation in the next stages and a levelling off at exhaustion. Plasma arginine-vasopressin (AVP) and aldosterone (ALDO) rose significantly only in the last two stages, and the highest concentrations were observed at exhaustion. In conclusion, acute exercise stimulates ANF secretion in proportion to the intensity of exercise, while concomitant increases in plasma AVP and ALDO occur only when the work load exceeds the blood lactate (BLA) threshold.

Adult↗
PubMed1986

Auditory brain stem responses and nonsense monosyllable perception test findings for patients with auditory nerve and brain stem lesions.

A nonsense monosyllable audiometric test was administered to 15 patients with eighth nerve or brain stem disorders caused by tumor, hemorrhage, encephalitis, and degenerative disease. Auditory brain stem responses (ABR) were abnormal in all patients. ABR abnormalities were defined by the absence of some or all waves or by prolongation of the wave V-I interval. The discrimination scores of the nonsense monosyllables were significantly lower in patients with completely absent ABR, with partial ABR series involving wave I, or with severely prolonged wave V-I intervals (over 3 SD). However, in patients with wave I only or with only moderately prolonged wave V-I intervals (less than 3 SD), test scores were within normal range. It is concluded that: 1. perception of nonsense monosyllables could be, though need not be, affected in patients with brain stem lesions; 2. eighth nerve lesions severely disrupt auditory comprehension as well as perception of nonsense monosyllables.

Adult↗
PubMed1986

Changes in polysynaptic Ia excitation to quadriceps motoneurones during voluntary contraction in man.

Homonymous Ia facilitation of quadriceps (Q) motoneurones (MNs) was significantly larger during (and at the onset of) a very weak Q voluntary contraction than at rest. This increase in Ia facilitation only appeared with a conditioning-test interval within the narrow range of 5-9 ms, which fits the time course of the recently described polysynaptic Ia excitation to Q MNs. This suggests that interneurones mediating polysynaptic Ia excitatory effects to Q MNs receive a strong descending excitation during such a contraction. It is therefore argued that these interneurones might mediate part of the descending command to Q MNs during voluntary contraction.

Electric Stimulation↗
PubMed1986

Evidence for interneuronally mediated Ia excitatory effects to human quadriceps motoneurones.

The possibility was investigated that interneuronal pathways contribute to Ia excitation of quadriceps motoneurones in normal man. Two techniques were used: the indirect spatial facilitation technique for investigating summation of Ia excitatory effects in interneurones which may be interposed in pathways to quadriceps motoneurones; the post-stimulus time histogram method for time course measurement of the firing probability of voluntarily activated motor units following femoral nerve stimulation. The spatial facilitation technique was applied while using the quadriceps H reflex to assess the excitability of the whole motoneurone pool: the comparison was made between the excitatory effects of two conditioning stimuli applied either separately or together. Summation of effects at a premotoneuronal level is suggested if facilitation of the reflex evoked on combined conditioning stimulation is larger than the algebraic sum of facilitations evoked by separate stimuli. Quadriceps tendon tap and electrical stimulations applied to either the femoral nerve or to two of its branches, the nerves to the vastus lateralis and vastus medialis muscles, were used as conditioning stimuli. Since these stimuli were very weak (their strength being about at the threshold for facilitation of the test reflex), it can be assumed that they activated predominantly Ia fibres. The facilitation of the quadriceps H reflex evoked on combined stimulation was significantly larger than the algebraic sum of facilitations evoked by separate stimuli. In many experiments, although conditioning stimuli did not evoke any reflex facilitation when applied alone, a significant facilitation appeared on combined stimulation. This 'extra' facilitation of the reflex on combined stimulation appeared with a central latency of 4-5 ms. It is argued that the only mechanism compatible with such a latency is summation at a premotoneuronal level. Post-stimulus time histograms (p.s.t.h.s) of voluntarily activated quadriceps motor units were made following femoral nerve stimulation. Stimulation was triggered at a fixed delay time after the activation of the motor unit. A special attempt was made to set this delay so that the motoneuronal after-hyperpolarization following the spike would partially prevent the discharge evoked by a monosynaptic excitatory post-synaptic potential (e.p.s.p.). At stimulus strengths near motor threshold, femoral nerve stimulation regularly evoked an early increase in firing probability of motor units with the same latency as the H reflex.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1985

Cutaneous facilitation of transmission in Ib reflex pathways in the human upper limb.

Group I effects from wrist extensors to flexors, i.e. an early inhibition followed by a relative facilitation which are thought to be Ia and Ib in origin respectively, were compared in control conditions and when preceded by a weak cutaneous stimulation. Stimulating the skin of the dorsal side of fingers II-III, which did not modify the test reflex size when applied alone, increased Ib facilitation. By contrast this Ib effect was not changed by stimulation of the skin of the palmar side. It has previously been shown that heteronymous Ib inhibition in the lower limb during voluntary contraction is facilitated by cutaneous stimulation from restricted receptive fields. Thus, present results lend support to the idea that cutaneous facilitation of transmission in Ib reflex pathways might be functional in curtailing exploratory movements.

Adult↗
PubMed1985

Running velocity at blood lactate threshold of boys aged 6-15 years compared with untrained and trained young males.

Running velocities at the blood lactate threshold, which was estimated by the velocity just below 2 mmol X l-1 of blood lactate, were measured in sixty-six 6- to 15-year-old boys during a graded exercise stress test on the track and compared with those of twenty-three 16- to 18-year-old young males and eighteen 18- to 23-year-old untrained young males. The boys were divided into five age groups: 6-7, 8-9, 10-11, 12-13, and 14-15. The mean velocity at the lactate threshold of all age groups was significantly higher than that of untrained young males and not different from that of trained young males. There was no significant difference between boys of all age groups, but a significant negative correlation between the velocity at the lactate threshold and bone maturity score (RUS score) of more than 200 was found in boys. Heart rates and percent maximal heart rate at the lactate threshold were dependent on age. These were significantly inversely related to the chronological age and RUS score. These results suggest that maturation is one of the factors influencing lactate threshold.

Adolescent↗