Biomedical subjects

H Muratani

Publications and source records attributed to H Muratani.

At least 37 records · Page 2Linked to original sources

PubMed1999

Factors related to impairment of activities of daily living.

OBJECTIVE: We examined the factors related to the impairment of activities of daily living (ADL). METHODS: ADL was evaluated by using ADL-20, which consists of 20 items from 4 major categories of activities; mobility, self-care, instrumental, and communication. The patients' gender, birth date, clinical diagnosis, past history, life styles, physical findings, laboratory data, and details of therapy were also recorded. Patients A total of 1,163 outpatients aged 50 years or older were included. Data from 1,093 patients were analyzed. RESULTS: We divided the subjects into two groups; Group I having full marks of ADL-20 (n=582) and group II exhibiting an impairment of ADL (n=511). Multiple logistic analysis revealed that in both sexes age and stroke were common independent factors related to the impairment of ADL. Other factors associated with impairment of ADL were smoking in men and presence of proteinuria in women. The presence of hyperlipidemia was associated with preservation of the ADL in women. CONCLUSION: The results demonstrated significant associations of smoking in men and the presence of proteinuria in women with the impairment of ADL in elderly Japanese outpatients. There appears to be a sex difference in the risk factors of impairment of ADL.

Activities of Daily Living↗

PubMed1999

[Clinical experience of image-guided neurosurgery with a frameless navigation system (StealthStation)].

We have applied the frameless navigation system (StealthStation) to various neurosurgical procedures to examine its usefulness. The system consists of a UNIX based workstation that creates triplanar and 3-dimensional images; an infrared optical digitizer with camera array; a reference-light-emitting diode (LED) array (e.g., reference array); and pointer probe modified by the addition of LEDs. This system was used to assist in placing a minimal skin incision and craniotomy in 4 cases, to determine the tumor/brain interface in 2 cases, to target the subcortical lesion in one case, and to correlate bony structure with a skull base tumor in 3 cases. The combined use with magnetic source imaging of the somatosensory cortex allowed a fast orientation of eloquent areas in 2 cases with peri-Rolandic tumor. This system, thus, was proved to be a useful adjunct to open-tumor biopsy or resection.

Adult↗

PubMed1999

[Carbamazepine induced hyponatremia].

Carbamazepine (CBZ) is a drug which can induce the syndrome of inappropriate antidiuretic hormone (SIADH). Until 1980's, there were reports regarding CBZ-induced SIADH, but it is rarely reported these days. We here report two cases of CBZ-induced SIADH. Hyponatremia in these cases was rapidly improved by withdrawal of administration of CBZ. According to the previous reports, the rate of hyponatremia in patients receiving CBZ is not small. It ranges from 48% to 31%. As CBZ is frequently used for patients with epilepsy and neuralgia, not only their blood CBZ concentration but also their serum Na level should be monitored.

Adult↗

PubMed1998

Effects of meal ingestion and active standing on blood pressure in patients > or = 60 years of age.

Postprandial hypotension and orthostatic hypotension occur often in elderly patients. In the present study, we examined hemodynamic and humoral responses to meal ingestion and active standing in 20 patients > or = 60 years of age who were free of apparent autonomic and cardiac dysfunction. For a time-control study, water was given instead of a meal to 19 of the 20 patients. After the meal ingestion, there was a fall in systolic blood pressure (BP) in 6 patients of > 20 mm Hg, whereas the fall in systolic BP during the control study was not > 20 mm Hg in any patient. The low-frequency power of the systolic BP wave, an index of peripheral sympathetic activity, was significantly increased only in the patients without postprandial hypotension. The postprandial changes in systolic BP were correlated with the changes in the low-frequency power of the systolic BP wave (r = 0.61; p < 0.01), but they were not correlated with the changes in plasma norepinephrine, insulin, cardiac output, or parameters obtained by the spectral analysis of the RR interval. The systolic BPs in the upright position were comparable after the meal and the water ingestion. Thus, the effects of meal ingestion and upright position on BP are not additive. Dysfunction of peripheral sympathetic control of vascular tone may contribute to the postprandial hypotension in elderly patients.

Aged↗

PubMed1998

Contribution of alpha 2-adrenoceptors in caudal ventrolateral medulla to cardiovascular regulation in rat.

The inhibitory action of alpha 2-agonists on the cardiovascular neurons has been elucidated in the rostral ventrolateral medulla (RVLM) but not in the caudal ventrolateral medulla (CVLM). Our study aimed to clarify whether microinjection of clonidine into the CVLM elicits any cardiovascular effect and whether endogenous alpha 2-adrenoceptor-mediated mechanisms contribute to the tonic activity of the CVLM neurons. In male Sprague-Dawley rats (7-9 wk old, 270-320 g) anesthetized with urethan, unilateral microinjection of 8 nmol of clonidine into the CVLM (n = 10) increased mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) by 12.1 +/- 1.8 mmHg (mean +/- SE, P < 0.01) and 25.8 +/- 4.8% (P < 0.01), while heart rate (HR) remained unaltered. Unilateral microinjection of 2 nmol of SKF-86466, a selective blocker of the alpha 2-adrenoceptors, into the CVLM (n = 10) decreased MAP, HR, and RSNA (-11.6 +/- 2.6 mmHg, -26 +/- 7 beats/min, and -15.3 +/- 1.7%, respectively, P < 0.01 for each). Artificial cerebrospinal fluid caused neither a cardiovascular effect nor a sympathetic response. Prior injection of SKF-86466 into the ipsilateral CVLM attenuated the effects of clonidine. Bilateral microinjection of muscimol into the RVLM abolished the effects of both clonidine and SKF-86466 injected into the CVLM. The pressor and sympathoexcitatory effects of clonidine injected into the CVLM suggest a neuroinhibitory action of the drug on the CVLM neurons. In addition, the depressor and sympathoinhibitory effects of SKF-86466 injected into the CVLM indicated that activation of alpha 2-adrenoceptors by endogenous ligand inhibits CVLM neurons. The effects of clonidine and the alpha 2-adrenoceptor antagonist in the CVLM require the integrity of the RVLM.

Adrenergic alpha-Agonists↗

PubMed1998

Prolonged NOS inhibition in the brain elevates blood pressure in normotensive rats.

Systemic inhibition of nitric oxide synthase (NOS) evokes hypertension, which is enhanced by salt loading, partly via augmented sympathetic activity. We investigated whether inhibition of brain NOS elevates blood pressure (BP) in normotensive rats and, if so, whether the BP elevation is enhanced by salt loading. After a 2-wk low-salt (0.3%) diet, male Sprague-Dawley (SD) rats were divided into four groups. Groups 1 and 2 received a chronic intracerebroventricular infusion of 0.5 mg . kg-1 . day-1 of NG-monomethyl-L-arginine (L-NMMA), and groups 3 and 4 were given artificial cerebrospinal fluid (aCSF). Groups 1 and 3 were placed on a high-salt (8%) diet, whereas groups 2 and 4 were on a low-salt diet. On day 9 or 10, group 1 showed significantly higher mean arterial pressure (MAP) in a conscious unrestrained state (129 +/- 3 mmHg vs. 114 +/- 3, 113 +/- 1, and 108 +/- 3 mmHg in groups 2, 3, and 4, respectively, P < 0.05). On a high-salt diet, response of renal sympathetic nerve activity but not of BP to air-jet stress was significantly larger in rats given L-NMMA than in rats given aCSF (29 +/- 4% vs. 19 +/- 3%, P < 0.05). When the intracerebroventricular infusions were continued for 3 wk, MAP was significantly higher in rats given L-NMMA than in rats given aCSF irrespective of salt intake, although the difference was approximately 7 mmHg. Thus chronic inhibition of NOS in the brain only slightly elevates BP in SD rats. Salt loading causes a more rapid rise in BP. The mechanisms of the BP elevation and its acceleration by salt loading remain to be elucidated.

Animals↗

PubMed1998

Relationship between serum cholesterol and the risk of acute myocardial infarction in a screened cohort in Okinawa, Japan.

Coronary heart disease (CHD) is rare in Japanese subjects and serum cholesterol levels are low. However, no data have been published relating the effect of serum cholesterol levels to the incidence of acute myocardial infarction (AMI) in Japan. Data from a large community-based mass screening registry are available for the geographically isolated island of Okinawa, Japan (1980 census, 1.11 million). A total of 38,053 participants (17,859 men and 20,194 women) whose serum cholesterol levels were determined in the 1983 mass screening were examined to determine whether they had experienced AMI. Every case of AMI that occurred during a 3-year period (1 April 1988 to March 1991) throughout Okinawa was recorded in a separate registry. The total number of cases of AMI was 1,021 (674 men and 347 women). Of these, 65 patients (41 men and 24 women) were identified by name, sex, birth date, and zip code in the mass screening registry. The cumulative incidence of AMI increased with the serum level of cholesterol: 42.1 (serum cholesterol < or = 167 mg/dl), 133.5 (serum cholesterol 168-191 mg/dl), 188.9 (serum cholesterol 192-217 mg/dl), and 323.0 (serum cholesterol > or = 218 mg/dl) per 100,000 screened subjects. Multiple logistic analysis was conducted to examine the effect of serum cholesterol on the risk of AMI with adjustment for other variables such as sex, age, systolic and diastolic blood pressure, and proteinuria. The adjusted odds ratio (95% confidence interval) of the observed serum levels of cholesterol was 1.66 (1.29-2.15) with a reference serum cholesterol level of < or = 167 mg/dl. The risk of AMI increased in proportion to the serum level of cholesterol. Serum cholesterol is an independent predictor of AMI in Okinawa, Japan.

Adolescent↗

PubMed1998

Ouabain-like immunoreactivity in the medulla oblongata of rats.

An isomer of ouabain, the ouabain-like compound (OI,C), may participate in the regulation of body fluid volume and vascular tone. Forebrain regions, especially the hypothalamus, are reported to be sites of OLC action in the central nervous system. The medulla oblongata is another critical area involved in central cardiovascular regulation. We reported that the microinjection of either monoclonal antibody to ouabain T8B11 or Fab fragment of digoxin-specific antibody into the rostral ventrolateral medulla significantly decreased mean arterial pressure and renal sympathetic nerve activity in anesthetized normotensive rats (TERUYA et al.: J. Clin. Invest. 99: 2791-2798, 1997). Using T8B11, we examined the ouabain-like immunoreactivity in the medulla oblongata of normotensive rats. In periodate-lysine-paraformaldehyde fixed tissues, ouabain-like immunoreactive neurons were detected in the nuclei and regions in the medulla oblongata including the ventrolateral medulla, ventromedial medulla, nucleus ambiguus, caudal raphe nuclei, nucleus of solitary tract, and dorsal motor nucleus of the vagus. When an Fab fragment of digoxin-specific antibody was used as a first antibody, the digoxin-like immunoreactive neurons were distributed in almost the same pattern as those observed with the use of T8B11. In the brain fixed with the "three-step" procedure developed by YAMADA et al. (1987), which was used in a previous ouabain immunohistochemical study of the hypothalamus, ouabain-like immunoreactivity in the medulla oblongata was much weaker in intensity and less restricted in distribution than that in the hypothalamus. These findings suggest that ouabain-like immunoreactivities are present in the medulla oblongata with a manner of distribution different from that seen in the hypothalamus. Some ouabain-immunopositive nuclei and regions in the medulla oblongata, especially the rostral ventrolateral medulla, may be other OLC action sites.

Animals↗

PubMed1998

Demographic study of first-ever stroke and acute myocardial infarction in Okinawa, Japan.

We performed a cross-sectional survey of stroke and acute myocardial infarction (AMI) in Okinawa, Japan with a census population of about 1.2 million. A total of 3,644 cases of first-ever stroke and 898 cases of initial acute myocardial infarction (AMI) were detected. The age-adjusted annual incidence rate for stroke was 105 per 100,000 standard population of Japan, and that of AMI was 26. The case-fatality rate of stroke within 28 days of onset was 12.8%, and that of AMI was 22.2%. Of the stroke cases, 51.4% were diagnosed as brain infarction, 38.7% as brain hemorrhage, and 9.3% as subarachnoid hemorrhage. The diagnosis of stroke subtypes were confirmed by computed tomography or magnetic resonance imaging in 98.4% of all stroke cases. In Okinawa, the incidence rate of AMI was still considerably lower than that in the Western population, and the rate of stroke was similar to that in the Western population.

Adult↗

PubMed1997

Role of ouabain-like compound in the rostral ventrolateral medulla in rats.

To determine whether ouabain-like compound (OLC) exerts modulatory influences on the activity of vasomotor neurons in the rostral ventrolateral medulla (RVLM), we examined the effects of microinjecting ouabain, digoxin-specific antibody Fab fragments, and mAb against ouabain on the rat RVLM. Microinjection of ouabain into the unilateral RVLM of anesthetized normotensive rats elicited dose-dependent increases in mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA). The pressor and sympathoexcitatory effects of ouabain in the RVLM were reversed by microinjections of an M2 muscarinic antagonist, gallamine, or digoxin-specific antibody Fab fragments. Furthermore, a prior microinjection in the RVLM of gallamine, digoxinspecific antibody Fab fragments, or kainic acid or intravenous injection of hexamethonium all prevented the pressor and sympathoexcitatory effects induced by a subsequent microinjection of ouabain. Microinjections of either digoxinspecific antibody Fab fragments or gallamine per se significantly decreased baseline MAP and RSNA. Injection of digoxin-specific antibody Fab fragments attenuated the effects of a subsequent injection of gallamine. Microinjection of mAb against ouabain, but not nonspecific IgG, also significantly decreased baseline MAP and RSNA. These results suggest that OLC in the RVLM contributes to the tonic activity of vasomotor neurons in anesthetized normotensive rats, and the action of OLC in the RVLM is at least partly mediated by M2 muscarinic mechanisms.

Animals↗

PubMed1997

Leser-Trélat sign with anaplastic ependymoma--an autopsy case.

A 36-year-old Japanese male, who 7 years previously had been diagnosed as having an ependymoma in the left parietal region, had received surgery, chemotherapy and radiotherapy. He later developed a rapid growth of multiple skin lesions on his back and extremities, which coincided with a regrowth of the tumor. Postmortem examination revealed that the ependymoma showed anaplastic transformation and necrosis; however, no malignancy was observed in the extracranial organs. The skin lesions were histologically diagnosed as seborrheic keratoses. We have, therefore, diagnosed the patient as having Leser-Trélat sign associated with anaplastic ependymoma.

Adult↗

PubMed1997

[Endogenous digitalis-like factor].

Evidence suggests the existence of a Na,K-ATPase inhibitor, so called endogenous digitalis-like factor (EDLF), in plasma. This substance has been postulated to enhance renal tubular sodium excretion and to increase peripheral vascular resistance. Recently, plant ouabain or its isomer (ouabain-like compound, OLC) was purified from human plasma and bovine hypothalamic extract. The OLC is considered to be a candidate for the EDLF. The OLC has been implicated in the pathogenesis of sodium-dependent hypertension. Furthermore, accumulating evidence suggests central nervous system as a site of hypertensinogenic action of OLC.

Animals↗

PubMed1996

Current status of antihypertensive therapy for elderly patients in Japan.

To assess how elderly Japanese hypertensive patients are treated by specialists, we conducted a cross-sectional survey. A total of 1,163 outpatients aged 50 years or older were studied. Hypertension was diagnosed in 939 of these patients, and 827 were receiving drug therapy. The average blood pressure during therapy was 143 +/- 16/81 +/- 10 mmHg. In patients aged 70 years or older, systolic blood pressure during antihypertensive therapy was significantly higher (p < 0.01) and diastolic blood pressure was significantly lower (p < 0.01) than the corresponding values in those aged 50 to 59 years or 60 to 69 years. The calculated mean blood pressures were similar in the different age groups. The rate of monotherapy in the patients aged 70 years or older was 58.8%, which was significantly higher (p < 0.01) than the rates of monotherapy in the other age groups. Calcium channel blockers were prescribed in about 80% of patients, irrespective of age or comorbidity. Of the patients receiving calcium channel blockers, 43.5% were treated with monotherapy. This rate significantly (p < 0.01) increased with advancing age. Diastolic blood pressures were significantly lower (p < 0.05) in patients with stroke and in those with ischemic heart disease, diabetes mellitus, or dyslipidemia, as compared with patients with no comorbidity. Among patients aged 70 years or older, the difference in systolic blood pressure between those with ischemic heart disease and those with no comorbidity was not significant. Blood pressure in elderly hypertensive patients was reduced to a level similar to that in younger patients. The target blood pressure was influenced by the presence of comorbidity. Furthermore, specialists showed a high preference for the use of calcium channel blockers in the management of hypertension.

Activities of Daily Living↗

PubMed1996

Mild mental stress increases insulin sensitivity in healthy young men.

We examined if mental stress alters insulin sensitivity and renal sodium handling in 11 normotensive young men. Following a 60-minute period of equilibration, we performed euglycemic hyperinsulinemic glucose clamp for 150 minutes. The clamp period was divided into three phases; control phase for 90 minutes (I), mental arithmetic phase for 30 minutes (II), and recovery phase for 30 minutes (III). Blood pressure, heart rate and glucose disposal rate (M value) significantly elevated during phase II of the stress study. In a time control study, in which mental arithmetic was not loaded during phase II, blood pressure was kept constant and the changes in M value from phase I to phase II were significantly smaller than those in the stress study. In both studies, fractional excretion of sodium did not significantly change throughout the study period. Thus, insulin sensitivity concerning glucose metabolism increased in response to mild mental stress. However, the effect of insulin on sodium handling was not altered by the stress.

Adult↗

PubMed1995

Modulation of baroreflex function by angiotensin II endogenous to the caudal ventrolateral medulla.

Neurons in the ventrolateral medulla (VLM) mainly determine the tonic sympathetic activity. The caudal VLM (CVLM) relays baroreflex signals to the rostral VLM. We have reported that endogenous angiotensin II (ANG II) contributes to the ongoing activity of the VLM neurons. In the present study, we examined if ANG II endogenous to the CVLM modulates the baroreflex function in anesthetized normotensive Sprague-Dawley rats. Changes in renal sympathetic nerve activity (RSNA) in response to changes in mean arterial pressure (MAP) induced by i.v. infusion of phenylephrine and nitroglycerin were recorded before and after bilateral microinjection of [Sar1, Thr8]-ANG II, an ANG II antagonist, into the CVLM. The ANG II antagonist injection into the CVLM significantly increased MAP and RSNA by 17.6 +/- 8.0 mmHg (mean +/- S.D.) and 36.3 +/- 18.1%, respectively. It also significantly increased the baroreflex sensitivity (BS) from -0.49 +/- 0.38 to -0.74 +/- 0.37%/mmHg during nitroglycerin infusion. In contrast, the BS examined by phenylephrine infusion was not altered by the pretreatment with ANG II antagonist. Injection of artificial CSF affected neither the baseline values of MAP and RSNA nor the BS. These results suggest that ANG II endogenous to the CVLM exert a modulating role in baroreflex control of RSNA.

Adrenergic Fibers↗

PubMed1995

Brain angiotensin II contributes to the development of hypertension in Dahl-Iwai salt-sensitive rats.

OBJECTIVE: To examine the role of brain angiotensin II in the development of salt-induced hypertension in Dahl-Iwai salt-sensitive (DIS) rats. METHODS: Male DIS and Dahl-Iwai salt-resistant (DIR) rats aged 5 or 6 weeks were implanted with an intracerebroventricular cannula, and either chronic intracerebroventricular infusion of 5 micrograms/day CV-11974, a non-peptide type-1 angiotensin II receptor antagonist or artificial cerebrospinal fluid (aCSF) was started. The rats were fed a diet containing 8% sodium chloride. RESULTS: On day 11 or 12 of chronic infusion, DIS rats given CV-11974 intracerebroventricularly exhibited a significantly lower mean arterial pressure than DIS rats given aCSF intracerebroventricularly or intravenous infusion of CV-11974. In DIR rats, intracerebroventricular infusion of CV-11974 did not alter the mean arterial pressure. Sodium and water balances were similar in all of the groups. Plasma vasopressin and noradrenaline levels did not differ among the groups, although the plasma renin concentration was significantly lower in DIS rats given aCSF intracerebroventricularly. Arterial baroreflex control of heart rate and pressor response to intravenous injection of phenylephrine were not altered in rats given CV-11974 intracerebroventricularly. CONCLUSION: The integrity of the brain renin-angiotensin system is necessary for the development of salt-induced hypertension in DIS rats.

Angiotensin II↗

PubMed1995

Alterations of alpha 1-adrenergic receptor densities in right and left ventricles of spontaneously hypertensive rats.

To clarify whether alpha 1-adrenergic receptors contribute to cardiac hypertrophy, we examined alpha 1-adrenergic receptor densities in the right and left ventricles of 5- and 20-week-old spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) using [3H]prazosin. Also, we analyzed a pharmacologically distinct subtype of alpha 1-adrenergic receptors by pretreatment with chloroethylclonidine. The ratio of right ventricular weight to body weight as well as left ventricular weight to body weight was higher in SHR than in WKY at 5 weeks of age. At 20 weeks of age, only the left ventricular weight to body weight ratio was higher in SHR. At 5 weeks of age, the right and left ventricular alpha 1-adrenergic receptor densities in SHR were greater than those in WKY (LV 1760 vs. 1275, RV 2543 vs. 1521 fmol/mg protein). At 20 weeks of age, only right ventricular alpha 1-adrenergic receptor density remained higher in SHR (1425 vs. 885 fmol/mg protein). The percentage of pharmacologically distinct alpha 1A receptor was higher in the right ventricle of SHR than in that of WKY at 5 weeks of age (25% vs. 18%). There were no significant differences in the dissociation constants among the alpha 1-adrenergic receptor assays. These findings suggest that an increase in alpha 1-adrenergic receptors might be involved in cardiac hypertrophy in the early phase of hypertension in SHR.

Adrenergic alpha-Antagonists↗

PubMed1995

Alpha 2-adrenoceptors in brain and kidney during development of hypertension in Dahl-Iwai salt-sensitive rats.

BACKGROUND: Both renal and extrarenal factors have been considered to contribute to the development of hypertension in Dahl salt-sensitive rats, but contents of both factors have not been established precisely. AIM: To clarify the role of those factors in the sympathetic nervous system, we examined the regulation of alpha2-adrenoceptors in the lower brainstem and the renal tubular basolateral membranes simultaneously during the development of salt-induced hypertension in Dahl-Iwai salt-sensitive rats. METHODS: Dahl-Iwai salt-sensitive or resistant rats were fed a high (8.0% NaCl)- or low (0.3%)- salt diet from 4 to 6 or 10 weeks of age. At 4, 6 and 10 weeks of age, the plasma membranes of the lower brainstem and the renal tubular basolateral membranes were obtained simultaneously and alpha 2-adrenoceptors were quantified by a radioligand binding assay using 3H-rauwolscine. RESULTS: In the salt-sensitive rats, systolic blood pressure was significantly higher in those fed a high-salt diet than in those fed a low-salt diet. In the salt-resistant rats, both the high- and the low-salt groups showed similar blood pressure levels. At 6 weeks of age, alpha 2-receptor densities of the salt-sensitive rats fed a high-salt diet were lower in the lower brainstem and higher in the renal basolateral membranes than those fed a low-salt diet. In contrast, in the salt-resistant rats, both the high- and the low-salt groups had similar densities. At 10 weeks of age, the difference between the high- and the low-salt groups in the salt-sensitive rats disappeared in both the brainstem and the renal basolateral membranes. CONCLUSIONS: Alpha 2-adrenoceptor regulation in the brainstem and the renal basolateral membranes differs between Dahl-Iwai salt-sensitive and salt-resistant rats. The modulation of alpha 2-adrenoceptors by a high salt intake may be essential particularly in the early phase of the development of salt-induced hypertension.

Animals↗