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Biomedical subjects

K Kohara

Publications and source records attributed to K Kohara.

At least 73 records · Page 4Linked to original sources
PubMed1996

Autonomic nervous function in essential hypertension in the elderly. Evaluation by power spectral analysis of heart rate variability.

Autonomic nervous function in elderly essential hypertensive patients was investigated by power spectral analysis of heart rate variability. Fifty-seven essential hypertensive patients participated in this study. They were divided into two groups: the middle-aged group (age < or = 59 years, n = 30) and the elderly group (age > or = 60 years, n = 27). All examinations were performed during hospitalization. Power spectral analysis of R-R interval was performed from Holter electrocardiogram every 10 min by the maximum entropy method to obtain the low frequency band (LFB; 0.04 to 0.15 Hz), which is an index of both sympathetic and parasympathetic nervous activity. Twenty-four-hour blood pressure measurement was performed by the cuffoscillometric method to evaluate the nocturnal decrease in blood pressure. Nondipper patients were defined as those whose nocturnal decrease in systolic blood pressure was < 10% of daytime blood pressure. Both LFB and HFB were significantly lower in elderly hypertensive patients than in middle-aged patients (P < .001 and P < .05, respectively). Elderly nondipper patients had further reduced power spectral densities throughout the day. Both LFB and HFB showed a negative correlation with age. However, the age-related decline of power densities was more prominent in dipper patients and was not statistically significant in nondipper patients. These findings indicate that the nondipper phenomenon is superimposed on age-related attenuation of autonomic nervous function in essential hypertension.

Aged↗
PubMed1996

Cardiovascular effect of oral calcium supplementation: echocardiographic study in patients with essential hypertension.

Oral calcium (Ca) supplementation mildly reduces blood pressure. The authors studied the effects of Ca supplementation on the cardiovascular system in patients with mild to moderate essential hypertension. Twelve patients aged forty-nine to seventy years (7 men and 5 women, mean age with 60.3 +/- 7.2 years) participated. The investigators orally administered Ca (1.0 g/day for one week) under hospitalization, adding to a dietary intake of Ca (0.6 g/day). Left ventricular function and systemic arterial compliance were evaluated by M-mode and pulsed Doppler echocardiographies before and after seven days of Ca supplementation. Left ventricular contractility and afterload were not changed. Preload indicated by end-diastolic volume was significantly decreased after Ca supplementation (109.6 +/- 8.5 vs 107.3 +/- 8.2 mL, P < 0.05). Myocardial relaxation evaluated by IIa-mitral valve opening time (87.7 +/- 6.7 vs 82.1 +/- 6.2 ms, P < 0.01) and maximum descending rate of the left ventricular posterior wall (10.6 +/- 1.0 vs 12.4 +/- 1.0 cm/s, P < 0.01), and atrioventricular net compliance assessed by the descending slope of rapid filling flow in the left ventricular inflow tract (2.63 +/- 0.24 vs 2.26 +/- 0.17 m/s2, P <0.05), as well as systemic arterial compliance (2.05 +/- 0.20 vs 2.73 +/- 0.26 mL/mmHg, P < 0.01) were significantly improved by Ca supplementation. Oral Ca supplementation improved the disturbed left ventricular diastolic function and systemic arterial compliance.

Administration, Oral↗
PubMed1996

Angiotensin-converting enzyme gene polymorphism in essential hypertensive patients in Japanese population.

Association between angiotensin-converting enzyme (ACE) gene polymorphism and essential hypertension in a Japanese population with the same socioeconomic background was investigated. Insertion-deletion (I/D) polymorphism of the ACE gene located on intron 16 was detected by polymerase chain reaction. Association between ACE gene polymorphism and family history of essential hypertension as well as the development of vascular damage in eye fundi were also investigated. Variation at ACE loci did not contribute to essential hypertension and the vascular damages in eye fundi. These results suggest that the ACE gene was not directly responsible for essential hypertension in this particular Japanese population with the same socioeconomic background.

Adult↗
PubMed1996

Near-death asthmatic reaction induced by disodium cromoglycate.

A near-death asthmatic reaction was induced by disodium cromoglycate (DSCG) as evidenced by positive skin and inhalation provocation tests. The patient's history revealed an episode of exacerbation by inhalation of DSCG. In spite of such an experience, he inhaled DSCG for relief of asthmatic attack, resulting in near-death exacerbation. This patient emphasizes the need to re-recognize that DSCG is not a reliever and the DSCG could cause fatal asthma.

Adult↗
PubMed1996

[A case of idiopathic orthostatic hypotension manifesting sick sinus syndrome due to sympathetic nervous dysfunction].

A 67-year-old woman with idiopathic orthostatic hypotension was presented. The patient started to experience faintness on standing since 1993. During a physical examination, her systolic blood pressure fell from 148 to 50 mmHg on standing. Blood pressure responses to the mental arithmetic test and hyperventilation stress were normal. However, cold pressor test failed to increase blood pressure. These observations, with the finding that phase IV response on Valsalva's maneuver was absent, indicate afferent sympathetic nervous dysfunction. Peripheral neuropathy including diabetes mellitus and involvement of central nervous system such as multiple system atrophy were excluded. Holter ECG examination revealed a 3.9 second sinus arrest and bradycardia (total beats 88901/day). the blunted responses of the heart rate to atropine as well as isoproterenol further suggested the presence of sick sinus syndrome. Amezinium administration significantly improved her orthostatic hypotension and eliminated sinus arrest. These findings indicate that sympathetic nervous dysfunction could account for at least a part of the sick sinus syndrome in this patient.

Aged↗
PubMed1996

[A 66-year-old woman with a patent ductus arteriosus and no significant progression of pulmonary arterial pressure over 17 years].

We report the case of a 66-year-old woman with a patent ductus arteriosus and no significant progression of pulmonary arterial pressure over 17 years. She was admitted to our hospital in 1978 because of palpitations on exertion and chest discomfort. Cardiac catheterization was done, and she was given a diagnosis of patent ductus arteriosus. Because the left-to-right shunt was small (15%) and because there was no evidence of pulmonary hypertension (38/18 mmHg), she was treated medically. In 1995 she was admitted again, to determine the cause of a cerebral infarction. The cerebral infarction was believed to have been caused by an embolism due to atrial fibrillation. She underwent cardiac catheterization again. The left-to-right shunt had increased to 41%, but the pulmonary artery pressure had not changed (27/14 mmHg). Intravascular ultrasound imaging was used to evaluate the ductus arteriosus. The diameter of the ductus was 4.4 mm and calcification was not observed. During the 17 years of follow-up, heart size increased slightly, but pulmonary artery pressure did not change. In addition, intravascular ultrasound was very useful for evaluating the condition of the ductus arteriosus.

Aged↗
PubMed1996

[A very old man with Crush syndrome].

A 90-year-old man fell into a marsh and was rescued 18 hours later. When he was admitted to our emergency room, physical examination revealed no remarkable findings except for many abrasions on his skin. Laboratory examination revealed a serum CPK level of 46, 904 IU/L, which had further increased to 84,678 IU/L by the following day. Oliguria developed on the second day, along with an increase in serum creatinine to 5.5 mg/dt. Hemodialysis was considered for the treatment of acute renal failure, but his renal function recovered soon by the continuation of conservative fluid therapy. Fluid therapy may be an effective and easy treatment for acute renal failure due to the crush syndrome, even in very old patients.

Acute Kidney Injury↗
PubMed1996

[Guidelines on treatment of hypertension in the elderly, 1995--a tentative plan for comprehensive research projects on aging and health-- Members of the Research Group for "Guidelines on Treatment of Hypertension in the Elderly", Comprehensive Research Projects on Aging and Health, the Ministry of Health and Welfare of Japan].

We propose the following guidelines for treatment of hypertension in the elderly. 1. Indications for Treatment. 1) Age: Lifestyle modification is recommended for patients aged 85 years and older. Antihypertensive therapy should be limited to patients in whom the merit of the treatment is obvious. 2) Blood pressure: Systolic BP > 160 mmHg, diastolic BP > 90 approximately 10 mmHg. Systolic BP < age + 100 mmHg for those aged 70 years and older. Patients with mild hypertension (140-160/ 90-95 mmHg) associated with cardiovascular disease should be considered for antihypertensive drug therapy. 2. Goal of Therapy for BP: The goal BP in elderly patients is higher than that in younger patients (BP reduction of 10-20 mmHg for systolic BP and 5-10 mmHg for diastolic BP). In general, 140-160/< 90 mmHg is recommended as the goal. However, lowering the BP below 150/85 should be done with caution. 3. Rate of Lowering BP: Start with half the usual dose, observe at the same dose for at least four weeks, and reach the target BP over two months. Increasing the dose of antihypertensive drugs should be done very slowly. 4. Lifestyle Modification: 1) Dietary modification: (1) Reduction of sodium intake is highly effective in elderly patients due to their high salt-sensitivity. NaCl intake of less than 10 g/day is recommended. Serum Na+ should be occasionally measured. (2) Potassium supplementation is recommended, but with caution in patients with renal insufficiency. (3) Sufficient intake of calcium and magnesium is recommended. (4) Reduce saturated fatty acids. Intake of fish is recommended. (2) Regular physical activity: Recommended exercise for patients aged 60 years and older: peak heart rate 110/minute, for 30-40 minutes a day, 3-5 days a week. (3) Weight reduction. (4) Moderation of alcohol intake, smoking cessation. 5. Pharmacologic Treatment: 1) Initial drug therapy. First choice: Long-acting (once or twice a day) Ca antagonists or ACE inhibitors. Second choice: Thiazide diuretics (combined with potassium-sparing diuretic). 2) Combination therapy. (1) For patients without complications, either of the following is recommended. i) Ca antagoinst + ACE inhibitor, ii) ACE inhibitor + Ca antagonist (or low-dose diuretics), iii) diuretic + Ca antagonist (or ACE inhibitor), iv) beta-blockers, alpha 1-blockers, alpha + beta blockers can be used according to the patho-physiological state of the patient. (2) For patients with complications. Drug(s) should be selected according to each complication. 3) Relatively contraindicated drugs. beta-Blockers and alpha 1-blockers are relatively contraindicated in elderly patients with hypertension in Japan. Centrally acting agents such as reserpine, methyldopa and clonidine are also relatively contraindicated beta-Blockers are contraindicated in patients with congestive heart failure, arteriosclerosis obliterans, chronic obstructive pulmonary disease, diabetes mellitus (or glucose intolerance), or bradycardia. These conditions are often present in elderly subjects. Elderly subjects are susceptible to alpha 1-blocker-induced orthostatic hypotension, since their baroreceptor reflex is diminished. Orthostatic hypotension may cause falls and bone fractures in the elderly.

Aged↗
PubMed1996

Effect of alacepril on 24-hour blood pressure in elderly hypertensive patients.

The effect of administration of an angiotensin-converting enzyme inhibitor, alacepril, on 24-hour blood pressure in the elderly hypertensive patients was investigated. Thirteen elderly hypertensive patients (mean age 71 +/- 5; 6 male and 7 female) participated in the present study. After 2 weeks of control period alacepril was administered 25-50 mg/day for 8 weeks. Ambulatory blood pressure monitoring with cuff-oscillometric method was performed at the end of both control and treatment periods. Alacepril administration for 8 weeks significantly decreased 24-hour blood pressure while it had little effect on heart rate. Daytime blood pressure was significantly decreased from 154 +/- 10/91 +/- 5 mmHg to 145 +/- 8/85 +/- 5 mmHg, while the change in nocturnal blood pressure was not significant: from 137 +/- 17/79 +/- 7 mmHg to 130 +/- 15/75 +/- 9 mmHg. Hyperbaric area of systolic blood pressure was also significantly decreased (from 295 +/- 185 mmHg x hour/day to 172 +/- 111 mmHg x hour/day), indicating that pressure load to the heart was effectively reduced. Administration of alacepril did not cause tachycardia in response to the decrease in blood pressure. Acrophase of both blood pressure and heart rate was changed to 11:00 a.m. These findings indicate that blockade of the renin-angiotensin system in the elderly hypertensive patients decreased blood pressure effectively without causing tachycardia or deterioration of diurnal variations of blood pressure. These hemodynamic changes produced by alacepril administration are favorable for the treatment of the elderly patients with cardiovascular disease.

Aged↗
PubMed1995

Molecular cloning and gene mapping of human basic and acidic calponins.

The nucleotide and deduced amino acid sequences of human basic and acidic calponins were determined. The basic calponin cDNA from human aorta (1496 bp) contained a single open reading frame (ORF) which encodes 297 amino acids (33,169 Da). The acidic calponin cDNA from human kidney (1607 bp) contained a single ORF which encodes 329 amino acids (36,412 Da). Basic calponin mRNA was expressed in only smooth muscle tissues, but acidic calponin mRNA was expressed in non-smooth muscle tissues as well as smooth muscle tissues. Fluorescent in situ hybridization revealed that basic and acidic calponin genes localize in 19p13.1-13.2 and 1p21-22 of human chromosomes, respectively.

Amino Acid Sequence↗
PubMed1995

Effect of dietary NaCl on tyrosine hydroxylase in the superior cervical ganglia of Dahl rats.

To investigate the involvement of peripheral catecholamines in the development of Dahl-Iwai salt-sensitive (DIS/Eis) hypertension, we performed immunohistochemical staining of tyrosine hydroxylase (TH) in the superior cervical ganglia (SCG) of DIS/Eis rats and Dahl-Iwai salt-resistant (DIR/Eis) rats, and in situ hybridization histochemistry for demonstration of TH mRNA localization in the SCG of these rats. DIS/Eis and DIR/Eis rats were fed on a high (8%) salt diet or on a low (0.3%) salt diet for 4 weeks. Nerve cells in the SCG of DIS/Eis high salt rats exhibited more intense TH-immunoreactivity (P < 0.01) and hybridization signals (P < 0.01) than those of the other experimental groups. These findings suggest that activation of peripheral sympathetic nerves may account for hypertension in DIS/Eis rats on a high salt diet.

Animals↗
PubMed1995

Amino acids in the medulla oblongata contribute to baroreflex modulation by angiotensin II.

We investigated the underlying mechanisms of baroreflex alteration produced by intravenous angiotensin II (ANG II) by monitoring the release of amino acids from the rostral ventrolateral medulla (VLM) using a brain microdialysis technique. Reflex changes in heart rate were elicited by bolus intravenous injection of phenylephrine (2-40 micrograms/kg) before and 120 min after the initiation of administration of a subpressor dose of ANG II (5.4 pmol/kg/min) or vehicle. The slope of the regression line obtained from changes in mean arterial pressure and heart rate elicited by phenylephrine was used as an index of baroreceptor reflex sensitivity. ANG II administration for 120 min significantly attenuated the baroreflex sensitivity (from -0.59 +/- 0.10 to -0.30 +/- 0.08 bpm/mmHg). This attenuation was accompanied with an increase in the release of glutamate and glycine from the VLM (+40% and +20%, respectively) at 120 min. Glycine perfusion into this area resulted in an attenuation of baroreflex sensitivity with a magnitude similar to that obtained with infusion of a subpressor dose of ANG II, whereas glutamate perfusion caused a resetting of baroreflex. These results suggest that glycine and glutamate are involved in cardiovascular regulation in the VLM. Furthermore, the augmented releases of these amino acids may account for the underlying mechanism of ANG II-induced attenuation of baroreflex function.

Amino Acids↗
PubMed1995

Left ventricular mass index negatively correlates with heart rate variability in essential hypertension.

To investigate the relationship between alterations of the autonomic nervous activity and left ventricular mass index in essential hypertensive patients, 24-h power spectral analysis of R-R intervals was performed using Holter electrocardiography. Fifty-three patients (mean age, 58.0 +/- 13.1 years; 30 men and 23 women) participated. The urinary excretions and plasma levels of catecholamines were also determined. Power spectral analysis of R-R interval was performed every 10 min by the maximum entropy method to obtain the low frequency band (LFB; 0.04 to 0.15 Hz), which is an index of both parasympathetic and sympathetic nervous activities, and the high frequency band (HFB; 0.15 to 0.4 Hz), which reflects parasympathetic nervous activity. LFB and HFB were averaged every hour to obtain hourly LFB and HFB levels. Total LFB and HFB were calculated as the summation of 24-h LFBs and HFBs. Left ventricular mass index showed a significant negative correlation with total LFB (r = -0.466, P < .001) and total HFB (r = -0.319, P < .02). These findings suggest that the level of end-organ damage correlates with neuronal alteration in essential hypertension.

Autonomic Nervous System↗
PubMed1995

Persistent inhibition of the pressor and aldosterone responses to angiotensin-II by TCV-116 in normotensive subjects.

TCV-116 is an orally active, nonpeptide antagonist of angiotensin-II type-1 receptor. The angiotensin-II antagonistic potency of TCV-116 was evaluated in normal volunteers. TCV-116 was administered at single doses of 1, 2.5, and 5 mg orally on separated days. Before, and 4, 8, and 24 h after the drug administration, angiotensin-II was infused intravenously at the rate of 2.5 to 40 ng/kg/min for 5 min each. At 2.5 mg of TCV-116, the pressor response to angiotensin-II was significantly suppressed at 4 and 8 hours after drug administration. TCV-116 at 5 mg produced a reduction of basal blood pressure and a suppression of pressor response to angiotensin-II, which persisted for 24 h. Aldosterone response to exogenous angiotensin-II was suppressed to 10% at 8 h after 5 mg of TCV-116 administration and remained suppressed to 48% until 24 h. These results suggest that TCV-116 is a highly potent and long-lasting antagonist of angiotensin-II receptor in man. The renin-angiotensin system may play a role in the regulation of blood pressure even in normotensive subjects.

Administration, Oral↗
PubMed1995

Autonomic nervous function in non-dipper essential hypertensive subjects. Evaluation by power spectral analysis of heart rate variability.

Autonomic nervous function was evaluated by means of power spectral analysis of heart rate variability in hospitalized dipper (n = 31) and non-dipper (n = 31) essential hypertensive subjects. Twenty-four-hour blood pressure (BP) measurement was performed by the cuff-oscillometric method to evaluate the nocturnal decrease of BP. The non-dipper subjects were defined as those whose nocturnal decrease of systolic BP was < 10% of daytime BP. Power spectral analysis of RR interval was performed from Holter ECG every 10 minutes by the maximum entropy method to obtain the low-frequency band (LFB, 0.04 to 0.15 Hz), which is an index of both parasympathetic and sympathetic nervous activities, and the high frequency band (HFB, 0.15 to 0.4 Hz), which reflects parasympathetic nervous activity. LFB and HFB were averaged every hour to obtain hourly LFB and HFB values. Total LFB and total HFB were calculated as the mean values of 24 hourly averaged LFBs and HFBs. Both LFB and HFB were significantly lower in non-dipper hypertensives than in dipper subjects throughout the day. In dipper hypertensives, LFB showed a nocturnal decrease, whereas HFB was significantly increased during the nighttime. However, these diurnal changes in LFB and HFB were significantly blunted in non-dipper subjects. These findings indicate that non-dipper hypertensive subjects were characterized with a decreased physiological circadian fluctuation on autonomic functions compared with dipper subjects. This alteration in the autonomic nervous function may explain the non-dipper phenomenon in essential hypertension.

Autonomic Nervous System↗
PubMed1995

[Searching for hepatitis C virus by immunoelectron microscopy and its morphology].

Many investigators have searched for the causative agent(s) of blood-borne non-A, non-B hepatitis in sera and liver from patients and experimental animals, and have reported various virus-like particles, morphologically resembling parvovirus, togavirus, picornavirus, hepadnavirus, paramyxovirus, papovavirus, retrovirus or bunyavirus. Despite extensive effort, none of these virus-like particles has been confirmed universally as an etiologic virus because of the absence of immunological identification. The frustration was solved by the success in cloning cDNA of the genome of hepatitis C virus (HCV), a major etiologic agent of human non-A, non-B hepatitis, in 1989, but the morphology of HCV remained in riddles. We attempted to visualize HCV by indirect immunogold electron microscopy, using specific antibodies to the putative HCV envelope 1 protein and succeeded in identifying HCV particle in HCV-RNA-rich plasma. Our study showed that HCV particles are 55-65 nm spherical particles with 6 nm fine surface spike-like projections, and have a 30-35 nm inner core.

Hepacivirus↗
PubMed1995

End-organ damage in essential hypertension in the elderly.

To elucidate the characteristics of end-organ damage in essential hypertension in the elderly, the progression of end-organ damage, with respect to deterioration of renal function and changes in the optic fundi, were compared between young and elderly essential hypertensive patients with the same left ventricular mass index (LVMI). Forty five elderly hypertensive patients (age > or = 65 years) were matched with 40 young patients (age < or = 55 years) for sex and LVMI. All studies were performed under hospitalisation to uniform the background of diet and daily activity. Compared with young hypertensive patients, elderly patients were characterised to have advanced end-organ damage. In young patients, the levels of progression of end-organ damage were significantly correlated with each other, while in elderly patients no relation was observed. In young patients, LVMI was significantly correlated with urinary and plasma noradrenaline, PRA and 24 h blood pressure. In elderly patients, LVMI correlated only with 24 h systolic blood pressure.

Adult↗