Biomedical subjects

M Kihara

Publications and source records attributed to M Kihara.

At least 253 records · Page 14Linked to original sources

PubMed1986

Thyrotropin releasing hormone levels in human cerebrospinal fluid in various neurologic diseases.

Thyrotropin releasing hormone (TRH) in the human cerebrospinal fluid (CSF) of 102 patients with non-neurologic and neurologic diseases was measured by a specific TRH radioimmunoassay. TRH levels in CSF were 17.6 +/- 3.4 pg/ml (mean +/- SE) in non-neurologic diseases. TRH levels in CSF were significantly elevated in cases of spinal cord tumor and multiple sclerosis (acute phase). Elevated TRH levels in CSF were decreased in these diseases by operation or prednisolone treatment, respectively. From these data, it is suggested that TRH is present in the human CSF and that measurement of TRH levels in CSF may be a useful indicator of the activity of certain neurologic diseases.

Adolescent↗

PubMed1986

Genetic evidence for a switching and energy-transducing complex in the flagellar motor of Salmonella typhimurium.

The flaAII.2, flaQ, and flaN genes of Salmonella typhimurium are important for assembly, rotation, and counterclockwise-clockwise switching of the flagellar motor. Paralyzed and nonchemotactic mutants were subjected to selection pressure for partial acquisition of motility and chemotaxis, and the suppressor mutations of the resulting pseudorevertants were mapped and isolated. Many of the intergenic suppressor mutations were in one of the other two genes. Others were in genes for cytoplasmic components of the chemotaxis system, notably cheY and cheZ; one of the mutations was found in the cheA gene and one in a motility gene, motB. Suppression among the three fla genes was allele specific, and many of the pseudorevertants were either cold sensitive or heat sensitive. We conclude that the FlaAII.2, FlaQ, and FlaN proteins form a complex which determines the rotational sense, either counterclockwise or clockwise, of the motor and also participates in the conversion of proton energy into mechanical work of rotation. This switch complex is probably mounted to the base of the flagellar basal body and, via binding of the CheY and CheZ proteins, receives sensory information and uses it to control flagellar operation.

Chemotaxis↗

PubMed1986

Contribution of vasopressin to hypertension caused by baroreceptor denervation and nucleus tractus solitarius lesions in rats.

The purpose of this study was to examine, using pentobarbital-anesthetized rats, whether vasopressin contributes to hypertension caused by denervation of baroreceptors, in comparison to the contribution of vasopressin to hypertension caused by nucleus tractus solitarius (NTS) lesions. Bilateral baroreceptor denervation caused acute hypertension which was inhibited by intravenous injection of an antagonist of the vasoconstrictor action of vasopressin. Lesions of the NTS also produced an increased in blood pressure which was reduced by the vasopressin antagonist. The magnitude of the antagonist-induced hypotension was significantly greater in NTS hypertension than that in baroreceptor denervation hypertension. It is concluded, that in rats, vasopressin contributes to the neurogenic hypertension caused by baroreceptor denervation and NTS lesions. Thus, it appears that interruption of baroreceptor afferents at the NTS level is responsible for the vasopressin-mediated hypertension caused by NTS lesions but that it is not the only factor involved.

Animals↗

PubMed1986

Changes in hemodynamic characteristics in response to shaking stress with advancing age in spontaneously hypertensive rats.

Changes in hemodynamic parameters following "shaking" in 4, 12, 24 and 48 week old spontaneously hypertensive rats (SHR) and Wistar rats of the Kyoto strain (WKY) were analyzed. Mean arterial pressure (MAP) and cardiac output (CO) were measured in the following two conditions: (A) at rest, and (B) after shaking (these parameters were measured following a 3-sec rest after 5-sec of shaking). Both sets of data were compared in each age group between SHR and WKY. Heart rates (HR) in all age groups of SHR and WKY were significantly increased after shaking compared with those at rest. MAP in 4 week old SHR, but not in 4 week old WKY, was increased compared with that at rest. In 48 week old SHR and WKY, MAP after shaking was not increased compared with that at rest. This increased MAP induced by stress (shaking) in young SHR may be related to a causative factor in hypertension. CO in SHR did not indicate changes in shaking reaction as a result of increasing aging. Heart work index (HWI) after shaking in all age groups of SHR, including the prehypertensive stage, was significantly increased compared with that at rest; this was not the case in WKY. The intermittently increased heart work seen in response to stress may contribute to the early development of left ventricular hypertrophy in young SHR.

Aging↗

PubMed1986

Cardiovascular effects of L-glutamate and gamma-aminobutyric acid injected into the rostral ventrolateral medulla in normotensive and spontaneously hypertensive rats.

We studied the responses to chemical stimulation of the ventrolateral medulla in pentobarbital-anaesthetized, paralyzed, normotensive and spontaneously hypertensive (SHR) rats. When unilaterally injected into a circumscribed region of the rostral ventrolateral medulla, L-glutamate (0.16-1.6 nmol) elicited a dose-dependent increase in arterial pressure and heart rate. Bilateral microinjections of L-glutamate diethylester (63 nmol), an antagonist of excitatory amino acids, into the glutamate-sensitive sites markedly reduced arterial pressure and heart rate. gamma-Aminobutyric acid (GABA) (0.3-3 nmol) injected into the glutamate-sensitive sites caused a dose-dependent decrease in arterial pressure and heart rate. The depressor response to GABA was smaller in SHR than that in normotensive Wistar Kyoto rats (WKY), while there were no differences between WKY and SHR in the pressor response to L-glutamate. Thus, a depressor function involving the ventrolateral medulla appears to be diminished in SHR.

Animals↗

PubMed1986

Increased tissue level of atrial natriuretic polypeptide in the hypothalamus and septum of spontaneously hypertensive rats.

To elucidate the pathophysiological role of atrial natriuretic polypeptide (ANP) in the brain in hypertension, the tissue concentrations and contents of alpha-rat ANP-like immunoreactivity (alpha-rANP-Ll) in the hypothalamus and septum of 4-week or 18-week-old spontaneously hypertensive rats (SHR) were studied using a radio-immunoassay (RIA) for alpha-rANP and compared with those of age-matched Wistar-Kyoto rats (WKY). The concentration and content of alpha-rANP-Ll in these regions of both 4-week and 18-week-old SHR were significantly higher that those of WKY (P less than 0.05). High performance gel permeation chromatography coupled with the RIA showed that the gel filtration profile of alpha-rANP-Ll in SHR was essentially identical to that of WKY. Since the hypothalamus and septum are known to be critical areas for water and electrolyte balance, and blood pressure control, these results suggest that ANP plays a pathophysiological role in these brain regions of SHR.

Animals↗

PubMed1986

Responses of plasma atrial natriuretic polypeptide to isotonic volume expansion in conscious spontaneously hypertensive and chronically guanethidine-treated rats.

Responses of plasma immunoreactive atrial natriuretic polypeptide (IR-ANP) to isotonic volume expansion (100 ml/kg per h for 60 min) were investigated in conscious, unrestrained, chronically guanethidine-treated Sprague-Dawley rats and spontaneously hypertensive rats (SHR). Plasma IR-ANP increased during volume expansion and stabilized with continued infusion of isotonic solution. Guanethidine treatment did not alter resting and maximum responses of plasma IR-ANP. Spontaneously hypertensive rats and WKY showed similar plasma IR-ANP levels before volume expansion. Spontaneously hypertensive rats, however, exhibited earlier rises in plasma IR-ANP and larger increases in blood pressure, while maximum plasma IR-ANP response and total fluid retention (as judged from the weight gain) during volume expansion were similar in both groups. The present study suggests that: ANP release is regulated by the extent of filling of the circulation, sympathetic nervous system does not modulate release of ANP, and SHR have altered responses of ANP to volume overload, which may represent a compensatory mechanism that enables the SHR to eliminate excess sodium and fluid out of the circulation and thereby blunt further increases in blood pressure. In separate studies, we found that ether anaesthesia increases, while pentobarbital decreases the levels of plasma IR-ANP.

Animals↗

PubMed1986

[Tuberculosis in patients with malignant neoplasms].

Out of 810 patients autopsied at our institute between 1972 and 1985, tuberculosis was demonstrated in 12 (1.5%), all between 40 and 80 years of age, regardless of cancer type. Of 4,272 patients who underwent surgery for malignant neoplasms, 481 were examined for M. tuberculosis by culture in different specimens. All of eight positive cases were with sputum or bronchial mucus specimens, regardless of the site of primary cancer. Tuberculosis complicating malignant thymoma or Hodgkin's disease was found to be generalized and severe. Remarkable growth of elongated bacteria was observed in host macrophages in these immunodeficient patients, suggesting their altered intracellular environment. These findings warrant special attention to tuberculosis in hospital care of cancer patients, who are often immunodeficient.

Adult↗

PubMed1986

Comparison of various genetic hypertensive rat strains.

Comparative studies on nine genetic hypertensive rat strains [two stroke-prone spontaneously hypertensive rats (SHRSP) and Dahl salt-sensitive (DS) strains, and one strain each of spontaneously hypertensive rats (SHR), Lyon hypertensive rats (LH), Milan hypertensive strain (MHS), genetically hypertensive rats (GH) and Sabra hypertensive rats (SBH)] and their respective controls [two Dahl salt-resistent (DR) strains and one strain each of Wistar-Kyoto rats (WKY), Lyon normotensive rats (LN); Lyon low blood pressure rats (LL), Milan normotensive strain (MNS), genetically normotensive rats (GN) and Sabra normotensive rats (SBN) and their original strain, Sabra rats (SB)], in groups consisting of 6-10 males from each strain, were carried out at 10-12 weeks of age under the same experimental conditions. After checking the developmental course of blood pressure and changes in body weight, they were killed at 12 weeks of age for blood analysis and organ-weight examinations. The SHRSP and SHR showed markedly higher blood pressure levels and earlier blood pressure rises in comparison with other hypertensive strains, although they had higher blood pressure than their respective controls. Among various organ weights examined, all hypertensive strains commonly showed increases in left ventricular weight in proportion to blood pressure rises. Kidney weights were significantly decreased only in MHS compared with MNS, while they were either unchanged or significantly greater in other hypertensive strains. Weights of adrenal glands were greater in the two strains of DS and in LH than in their respective control strains. These comparative data indicate possible differences in the pathogenic mechanism involved in these genetic hypertensive rat strains.

Animals↗

PubMed1985

Alpha-human atrial natriuretic polypeptide is released from the heart and circulates in the body.

In order to clarify whether or not atrial natriuretic polypeptides are hormones in man, we have measured plasma alpha-human atrial natriuretic polypeptide (alpha-hANP)-like immunoreactivity (alpha-hANP-LI) with or without extraction procedure. alpha-hANP-LI was detected in plasma extracts from all 5 normal subjects and 7 patients with heart diseases. The alpha-hANP-LI concentration in normal peripheral plasma was 37.7 +/- 7.0 pg/ml (mean +/- SE). Plasma concentrations of alpha-hANP-LI in the coronary sinus obtained by cardiac catheterization were 3 to 10 times higher than those in the peripheral vein, inferior vena cava, right atrium, pulmonary artery and aorta. High performance gel permeation chromatography coupled with a radioimmunoassay (RIA) for alpha-hANP revealed that alpha-hANP-LI in normal peripheral plasma eluted at the position corresponding to that of authentic alpha-hANP without detectable amounts of high molecular weight forms. alpha-hANP-LI extracted from plasma taken from the coronary sinus of two patients also showed a single peak of alpha-hANP-LI co-eluting with alpha-hANP. In contrast, not only alpha-hANP but gamma-hANP and beta-hANP, high molecular weight forms, were present in the human atrial tissue. These results indicate that alpha-hANP is the predominant form of alpha-hANP-LI in human plasma and that this form generated in the atrial cardiocytes is preferentially released from these cells and circulates in the body.

Adult↗

PubMed1985

Existence of atrial natriuretic polypeptide in kidney.

Using a specific radioimmunoassay (RIA) for alpha-atrial natriuretic polypeptide (alpha-ANP), we have demonstrated the presence of alpha-rat ANP-like immunoreactivity (alpha-rANP-LI) in the rat kidney which is considered to be a target organ for atrial natriuretic polypeptides released from the heart. Most of alpha-rANP-LI was localized in the cortex. High performance gel permeation chromatography coupled with the RIA revealed that renal alpha-rANP-LI was eluted at the position of a low molecular weight form corresponding to alpha-rANP without detectable amounts of high molecular weight forms. This is in contrast to the observation that gamma-rANP, a high molecular weight form of 13k daltons, is the dominant form of alpha-rANP-LI in the rat atrium. In water-deprived rats, the concentration and content of alpha-rANP-LI in the kidney showed a significant decrease compared with control rats. In addition, the alpha-rANP-LI concentration and content in this organ revealed a substantial decrease after perfusion with physiological saline. These results indicate the existence of atrial natriuretic polypeptide (ANP) in the kidney and suggest that part of renal ANP may originate from the heart.

Animals↗

PubMed1985

Occurrence of atrial natriuretic polypeptide in brain.

In order to determine whether or not atrial natriuretic polypeptides (ANPs) exist in the brain, we have studied extracts from the rat brain using a specific radioimmunoassay (RIA) for alpha-atrial natriuretic polypeptide. The presence and widespread distribution of alpha-rat ANP-like immunoreactivity (alpha-rANP-LI) have been demonstrated in the rat brain. The highest concentration of alpha-rANP-LI (20-22 ng/g) is in the hypothalamus and the septum. Moderate concentrations of alpha-rANP-LI (2-8 ng/g) are also found in the midbrain, cerebral cortex, olfactory bulb, thalamus, pons-medulla and hippocampus. High performance gel permeation chromatography coupled with the RIA revealed that alpha-rANP-LI found in the rat brain consists of three components eluting at the positions of gamma-rat ANP (gamma-rANP), beta-rat ANP (beta-rANP) and alpha-rANP, respectively. Among these a low molecular weight form of alpha-rANP-LI emerging at the elution position corresponding to alpha-rANP is predominant in the rat brain. This is in contrast to the finding that gamma-rANP, a high molecular weight form of 13k daltons is the dominant form of alpha-rANP-LI in the rat atrium. These results clearly show that there exists a widespread neural system containing ANPs in the brain.

Animals↗

PubMed1985

Biochemical aspects of salt-induced, pressure-independent left ventricular hypertrophy in rats.

In an attempt to investigate the effect of chronic salt loading on heart size and biochemical composition, sixty 3-month-old male Wistar-Kyoto rats (WKY) were equally divided into two groups: One group was given 1% NaCl in drinking water, and the other group was given tap water as the control. After 7 months, five randomly selected rats from each group were examined for body weight (BW), indirect blood pressure (BP), hematocrit (Hct), and organ weights. Ventricles of the heart, aorta, and mesenteric arteries were biochemically analyzed for collagen (C) and noncollagenous protein NC) and deoxyribonucleic acid (DNA). Although here was no difference between the salt and control groups in BP (129 +/- 3 mmHg vs. 125 +/- 4 mmHg, mean +/- SE), BW (376 +/- 8 g vs. 372 +/- 5 g) and Hct (42.8% +/- 1.0% vs. 44.3% +/- 0.8%), left ventricular weight (857 +/- 19 mg vs. 788 +/- 8 mg) and kidney weight (2.59 +/- 00.9 g vs 2.31 +/- 0.05 g) were both significantly (P less than 0.01) greater in the salt group, whereas the weights of the right ventricle, aorta, and adrenal glands were equal. Biochemical analysis showed significant increase in NC/DNA ratio and total collagen content as well as decreased DNA concentration in the left ventricle of the salt group compared with the control, suggesting hypertrophy rather than hyperplasia of myocardial cells with concomitant activation of collagen synthesis. Since the manner of reactive collagen production appeared different from that reported for spontaneously hypertrophic rats (SHR) or in hypoxia- or aortic constriction-induced cardiac hypertrophy, some unique mechanism may be involved in salt-induced cardiac hypertrophy.

Adrenal Glands↗

PubMed1985

Extracranial metastasis of glioblastoma with sarcomatous component.

A case of glioblastoma with sarcomatous component is presented. Craniotomy was performed with total resection of the left occipital tumor. The patient received radiotherapy postoperatively but developed extracranial metastases only two months after the first surgical procedure.

Adult↗

PubMed1985

Zinc and vascular reactivity in rat mesenteric vessels: possible altered dihomo-gamma-linolenic acid metabolism in spontaneously hypertensive rats.

Zinc at a concentration of 0.4 microgram/ml potentiated pressor responses to norepinephrine in isolated perfused mesenteric vessels of SHR and WKY. At a higher concentration, 3.2 micrograms/ml, it inhibited responses to norepinephrine in WKY but produced no such inhibition in SHR. However, a transient potentiation was observed in SHR with the higher concentration. Pressor responses to potassium in WKY were not affected by zinc at either concentration. In SHR, however, the higher dose of zinc inhibited pressor responses to potassium. The low dose had no effect. Since effects of zinc may be mediated by release of DGLA, we suggest that in SHR DGLA release may be impaired.

8,11,14-Eicosatrienoic Acid↗

PubMed1985

The effects of indomethacin and PGE2 on vascular reactivity in spontaneously hypertensive rats: possible role of prostaglandins in the pathogenesis of hypertension.

Vascular reactivity was investigated in isolated perfused mesenteric vessels of young and adult SHR and age matched WKY. The primary objective was to investigate whether the difference in vascular reactivity between SHR and WKY would persist if endogenous prostaglandin synthesis was abolished and vascular reactivity restored with fixed exogenous quantities of PGE2. In young rats, when similar concentrations of PGE2 are infused in indomethacin blocked preparations, the difference in vascular reactivity between SHR and WKY is abolished. However, in adult rats the difference persists. It is concluded that enhanced prostaglandin synthesis in hypertension may participate in enhancing vascular reactivity.

Aging↗

PubMed1985

A case of polyradiculitis with hearing loss: analysis of auditory brain stem response.

A case of acute polyradiculoneuritis accompanied by rare complications of the VII, VIII and IX cranial nerve disorder was described. There was an elevation of the rubella virus antibody titer, which suggested the case had been infected before. Thirty-eight year-old woman complained of bilateral tinnitus and was proven audiometrically to have sensori-neural hearing loss. Electroacoustical examination disclosed that all the waves were suppressed and that wave I and V were barely detected, while wave II, III and IV were absent. The neurological and audiological disorders were successfully treated with corticosteroid, and the patient had neither sequelae nor recurrence.

Adult↗

PubMed1985

Zinc, copper, manganese, and selenium metabolism in patients with human growth hormone deficiency or acromegaly.

This study was designed to evaluate trace metal metabolism in patients with known abnormalities of human growth hormone (hGH). The mean concentration of zinc in plasma and urine decreased in patients with hGH deficiency after hGH injection, whereas, after adenomectomy, in patients with acromegaly, zinc increased in plasma, remained the same in erythrocytes, and decreased in urine. There was a negative correlation between plasma zinc and serum hGH levels and a positive correlation between urinary zinc excretion and serum hGH levels in acromegaly. In hGH deficiency, the copper content remained unchanged in plasma and erythrocytes and rose in urine after treatment; however, in acromegaly, the copper content increased in plasma and remained unchanged in erythrocytes and urine after surgery. The mean concentration of erythrocyte manganese did not change significantly after treatment in patients with hGH deficiency or acromegaly, but the pre-hGH treatment level of erythrocyte manganese in hGH deficiency was lower than in the controls. Plasma selenium concentrations were decreased in hGH deficiency and increased in acromegaly patients after therapy. These results suggest that hGH affects the metabolism of zinc, copper, manganese, and selenium.

Acromegaly↗