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Biomedical subjects

K Takebe

Publications and source records attributed to K Takebe.

At least 253 records · Page 14Linked to original sources
PubMed1976

Evidence of nycterohemeral periodicity in stress-induced pituitary-adrenal activation.

Plasma ACTH and corticosterone were measured under basal conditions and after ether or tourniquet stress during the nadir (a.m.) and zenith (p.m.) of the nycterohemeral pituitary-adrenal cycle. Exogenous ACTH was also given at these 2 times to assess adrenal sensitivity to ACTH and the maximal adrenal capacity for corticosterone secretion. Ether stress caused a greater rise in plasma ACTH in the a.m. than in the p.m., even though basal plasma ACTH and corticosterone concentrations were lower in the a.m. than in the p.m. When given in the p.m., pentobarbital anesthesia depressed plasma corticosterone and ACTH to the a.m. level; under these conditions the rise in plasma ACTH produced by tourniquet stress was the same in the a.m. and p.m. Both tourniquet and ether stresses caused maximal activation of adrenal corticosterone secretion, but ether produced a much greater rise in plasma ACTH. It is concluded that: (1) the greater ether-induced rise in plasma ACTH in the a.m. than in the p.m. is probably due to the lower plasma (and probably tissue) corticosterone concentration at that time; (2) the plasma ACTH concentration for inducing maximal adrenal activation is relatively low; and (3) the higher basal levels of plasma corticosterone in the p.m. than in the a.m. are due to a slight increase in basal ACTH secretion in the p.m.

Adrenocorticotropic Hormone↗
PubMed1976

Studies on ACTH dynamics in cultured adenohypophyseal cells: effect of adrenalectomy or dexamethasone in vitro.

Basal or hypothalamic extract-induced ACTH or TSH secretory capacity as well as intracellular ACTH content were assessed in cultured rat adenohypophyseal cells after various pretreatments of the donor animals. Medium and intracellular ACTH or TSH were measured by radioimmunoassay. Ten-day to 2-month adrenalectomy enhanced, whereas dexamethasone pretreatment suppressed, both synthesis and secretion of ACTH in the adenohypophyseal cells. Dexamethasone may also impair the replication of the adenohypophyseal cells in vivo, as indicated by the smaller number of cells obtained per animal in the dexamethasone-treated group. No significant increase in TSH secretion was observed when adenohypophyseal cells were derived from rats fed propyl-thiouracil (PTU) for 3 weeks instead of from intact rats.

Adrenal Glands↗
PubMed1976

Studies on fast feedback mechanisms by endogenous glucocorticoids.

Negative feedback in the hypothalamic-pituitary-adrenal axis by exogenous glucocorticoids has been well established, but it is still in doubt whether ACTH-releasing factor (CRF) activity in the hypothalamus is inhibited by endogenous glucocorticoids under conditions of stress. In our first experiment, CRF activity in the hypothalamus of rats was significantly increased, 2 min after onset of immobilization, for 2 min; a rapid drop of CRF activity followed immediately. On the other hand, the concentration of plasma corticosterone changed more slowly; it was increased at 5 min, and showed a progressive further increase until 17 min after the administration of the immobilization stress. A high plateau level persisted for the next 8 min, after which the concentration of plasma corticosterone fell, reaching the control level at 40 min. In order to test for negative feedback inhibition by endogenous glucocorticoids in the hypothalamic-pituitary-adrenal axis, a 2nd immunobilization stress was administered to rats 5 or 23 min after the 1st stress, and hypothalamic CRF activity and plasma corticosterone were examined after the 2nd stress. When the 2nd stress was applied 5 min after the start of the 1st stress, during the phase of a gradual increase of endogenous glucocorticoids, CRF activity was not increased 2 min after the 2nd stress. In contrast, an increase of CRF activity and plasma corticosterone was observed when the 2nd stress was administered 23 min after the onset of the 1st stress, during the phase of a high plateau level of endogenous plasma corticosterone. These data suggest that CRF activity in the hypothalamus is governed by a fast feedback, rate-sensitive mechanism.

Adrenocorticotropic Hormone↗
PubMed1976

Time course of hypothalamic CRF activity after the administration of two different stresses.

The time course of hypothalamic corticotropin-releasing factor (CRF) activity after the administration of ether stress was different from that after immobilization stress. The maximal response CRF activity was observed 2 min after ether stress, followed by a precipitous decrease 5 min after the stress. A gradual increase of CRF activity was subsequently observed for several minutes with fluctuated changes. Thus, response pattern was vibratory. But under immobilization stress, markedly fluctuant changes of CRF activity seen in the case of ether stress did not appear after the maximal response observed at 2 min, indicating that the response pattern was not vibratory. On the other hand, the concentration of plasma corticosterone increased significantly 5 min after the ether or immobilization stress with the peak value around 17 min.

Animals↗
PubMed1976

Gait analysis in stroke patients to assess treatments of foot-drop.

By using the combined, computerized analysis of stroboscopic photography, pattern recognition devices, electromyography and foot switch outputs, gait patterns were studied in 15 stroke patients with foot-drop. Three patients were treated with a peroneal nerve stimulator for five weeks; six received intensive physical therapy; and six received both physical therapy and biofeedback training three times a week for five weeks. Each patient was examined at initial visit and after five weeks. Based upon case evaluations, both the patients with the stimulator treatment and those with biofeedback training showed and maintained improvement of gait pattern following the treatment period. This result suggests that the biofeedback and peroneal-stimulator technique may have a common mechanism that should be exploited in the rehabilitation of stroke patients.

Cerebrovascular Disorders↗
PubMed1976

Biofeedback treatment of foot drop after stroke compared with standard rehabilitation technique (part 2): effects on nerve conduction velocity and spasticity.

Peroneal nerve conduction velocity (NCV) was determined in 20 hemiplegic patients with chronic foot drop. At the initial visit, relative slowing of NCV of the affected leg was observed. The patients were randomly separated into two groups, and treated for five weeks by different therapies--group 1 by conventional physical exercise and group 2 by physical exercise plus biofeedback training. Of these patients, six with severe spasticity were selected from each group to investigate the change of spasticity by patellar tendon reflex. Although with biofeedback remarkable improvement of function was observed (and reported in an earlier paper), there was no significant change of NCV and spasticity.

Autonomic Nervous System↗
PubMed1975

A sensitive and simple in vitro assay for corticotropin-releasing substances utilizing ACTH release from cultured anterior pituitary cells.

Graded doses of rat hypothalamic extract (HE) were added to dishes containing dispersed, pooled rat adenohypophyseal cells cultured for several days. ACTH secretion into the medium gave a linear log-dose response curve over a 100-fold range between 0.01 and 1 mg of NIH-HE (0.0125-1.25 rat hypothalamus). Forty percent of the maximal ACTH secretion in response to a given dose of HE occurred within 3 min. No decrease in intracellular ACTH occurred at any time or with any dose of HE, indicating that secretion was always balanced by production. ACTH secretion stopped as soon as HE-containing medium was replaced by medium without HE. The same cultured cells could be satisfactorily used in repetitive assays performed on the same or different days.

Adrenocorticotropic Hormone↗
PubMed1975

Inhibition of luteinizing hormone secretion induced by synthetic LRH by long-term treatment with glucocorticoids in human subjects.

The response of luteinizing hormone to a single injection of synthetic LRH was established in 6 women and 7 men following an intramuscular dose of 0.2mg or 0.1mg. Significant increases of serum LH were observed in 30 min. Pretreatment with metyrapone for one day (4.5 g/sugject injection of synthetic LRH (0.1 MG/SUBJECT). Seven women, 21-48 years of age who were treated with prednisolone for a least 11/2 months were examined for responsiveness of the anterior pituitary to a single injection of synthetic LRH (0.2 MG). The secretion of LH was markedly suppressed and maximal serum levels of LH WERE OBSERVED 90 MIN FOLLOWING LRH injection.

Adult↗
PubMed1975

Peroneal nerve stimulator in rehabilitation of hemiplegic patients.

Of nine hemiplegic patients having foot-drop who were test-treated with the Philips functional electronic peroneal stimulator, only three who tolerated continued use of the stimulator for five weeks had improvement in function. Findings in these cases indicate that to be selected for trial use of a stimulator a hemiplegic patient should fulfill the following criteria: (1) be in the hospital, (2) be ambulant with or without a cane and/or short leg brace, (3) have no severe contracture of the ankle joint, (4) have no severe spasticity, (5) have no obvious lower motor neuron lesions, (6) be cooperative and intelligent, (7) have no severe manual difficulty (he should be able to put on the stimulator without assistance), and (8) be able to tolerate the discomfort from the stimulation.

Adult↗
PubMed1975

Patterns of muscular activity around the hip joint in ambulatory children with cerebral palsy. An electromyographic study.

Effect of posture and voluntary movements on hip muclses in eithteen spastic ambulatory children with cerebral palsy were examined electromyographically. Five normal adults were also examined as controls. In each posture, subluxation hips showed greater activity than concentric and normal hips, and the activity pattern was mostly that of either the flexion or the extension synergies in voluntary movements. The concentric hips did not show the characteristic pattern.

Adolescent↗
PubMed1975

Biofeedback treatment of foot-drop after stroke compared with standard rehabilitation technique: effects on voluntary control and strength.

The effectiveness of biofeedback training was compared to conventional physical therapy training in 20 adult hemiparetic patients with chronic foot-drop. They were randomly placed into two groups of ten patients each: the first group treated over five weeks with therapeutic exercise and the second group treated over five weeks with therapeutic exercise plus biofeedback training. In the second group receiving the biofeedback training the increase in both strength and range of motion was approximately twice as great as in the first group. The improvement displayed by even the first group of patients suggests that a potential for functional improvement exists that is often unexploited. The addition of biofeedback facilitates the process. Four patients in the biofeedback group achieved and retained conscious control of dorsiflexion; three of them are now able to walk without the use of the short leg brace.

Adult↗
PubMed1975

Slowing of nerve conduction velocity in hemiplegia: possible factors.

A study of nerve conduction velocities in ulnar and peroneal nerves bilaterally in 27 hemiplegic patients revealed a statistically significant slowing in the affected limbs compared with the unaffected limbs, and a slowing of both compared with the standards for completely normal subjects. These results suggest that the upper motor lesion affects the function of the lower motor neuron. Proposed causes include a demonstrated lower skin temperature, a possible atrophic thinning of the fibers and other less plausible factors.

Action Potentials↗