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Biomedical subjects

E Murakami

Publications and source records attributed to E Murakami.

At least 37 records · Page 2Linked to original sources
PubMed1997

Peptides derived from cardiovascular G-protein-coupled receptors induce morphological cardiomyopathic changes in immunized rabbits.

An experimental model of early-stage cardiomyopathy was created by immunizing rabbits for 1 year with synthetic peptides corresponding to the sequence of the second extracellular loop of either beta-adrenoceptors or M2-muscarinic receptors. Thirty male rabbits were used and divided into three groups: a control group (n = 10), a group immunized with the peptide corresponding to the beta-adrenoceptor (beta 1 group) (n = 10) and a group immunized with the peptide corresponding to the M2-muscarinic receptor (M2 group) (n = 10). If the sera from both groups of immunized rabbits high-titres of anti-peptide antibodies were found throughout the study period but not in the sera from control rabbits or in the preimmune sera of immunized rabbits. No significant cross-reaction with peptides other than those used for immunization was found. The myocardial receptor density of both immunized groups displayed a strong trend toward receptor up-regulation. This was significant in the beta 1 group but not in the M2 group. Both groups of immunized rabbits displayed significantly enlarged ventricles and thinner walls, as compared with the control group. However, in contrast to the beta 1 group, which showed enlarged cavities in both left and right ventricles, the M2 group was mainly affected in the right ventricles. Moreover, morphological examinations of the hearts of rabbits from both immunized groups demonstrated focal myofibrillar lysis, loss of myofilament, mitochondrial swelling and condensation, sarcoplasmic vacuolation, deposition of dense granules in the sarcoplasm and the myofibrils. One of the sex control rabbit hearts which were examined showed mild degenerative changes in the myocardium and scant mononuclear cell infiltration. However, when all the control rabbit hearts were examined by electron microscopy, no significant alterations were found. These results suggest that immunization by peptides, corresponding to the target sequences for anti-receptor autoantibodies in idiopathic dilated cardiomyopathy, induces morphological changes in the heart similar to those found in the human disease.

Amino Acid Sequence↗
PubMed1997

Plasma adrenomedullin concentrations and cardiac and arterial hypertrophy in hypertension.

It has been reported that plasma concentrations of adrenomedullin (AM), a novel vasodilator peptide, are higher in patients with essential hypertension than those in normotensive subjects. To clarify the clinical significance of increased levels of AM in patients with essential hypertension, in this study we examined the relationship between plasma concentrations of AM and the structure of the left ventricle or carotid artery. Plasma AM concentrations; renin activity; and norepinephrine, epinephrine, and creatinine concentrations in 50 patients with untreated essential hypertension without renal dysfunction and heart failure were measured. We also measured the mean wall thickness of the left ventricle and left ventricular mass index by M-mode echocardiography and intimal-medial thickness and arterial distensibility of the carotid artery by ultrasonography. Hypertensive patients were divided into two groups: hypertensives with and those without left ventricular hypertrophy. Plasma AM concentrations in hypertensive patients with left ventricular hypertrophy were significantly higher than in hypertensive patients without left ventricular hypertrophy (7.87+/-2.70 vs 5.74+/-1.65 fmol/mL, P<.01). In all hypertensive patients, plasma AM concentrations were not correlated with blood pressure, plasma renin activity, plasma norepinephrine, plasma epinephrine, or plasma creatinine concentration. Plasma AM concentrations were positively correlated with left ventricular mass index or mean wall thickness (r=.37, P=.009; r=.40, P=.004, respectively) and inversely correlated with carotid artery distensibility (r=-.33, P=.02), whereas plasma AM concentrations were not correlated with intimal-medial thickness. These results suggest that the observed elevation of plasma AM in patients with essential hypertension with normal renal function may be partly related to cardiac hypertrophy and decreased carotid artery distensibility.

Adrenomedullin↗
PubMed1997

Effects of ACE inhibitors versus calcium antagonists on left ventricular morphology and function in patients with essential hypertension.

We compared the effects of two long-term antihypertensive treatments (ACE inhibitors vs. Ca antagonists) on left ventricular hypertrophy (LVH) and LV function in patients with essential hypertension and LVH. After a washout period of at least 4 wk, ceronapril or delapril was administered to 18 patients and nifedipine or nicardipine to 15 patients for 6 months. Mean blood pressure (MBP), LV mass (LVM), LV fractional shortening (FS), systolic time intervals (ejection time/pre-ejection period ratio = ET/PEP), and isovolumic relaxation time (IRT) were examined in the pretreatment phase and after 6 months of treatment. MBP and LVM significantly and similarly decreased after treatment in both groups (ACE inhibitors vs. Ca antagonists, delta MBP: -17.1 +/- 1.3 vs. -16.9 +/- 1.6%; delta LVM: -11.7 +/- 2.7 vs. -10.0 +/- 3.8%, both p = not significant). ACE inhibitors produced significant beneficial changes in FS, ET/PEP, and IRT after treatment as compared with Ca antagonists (ACE inhibitors vs. Ca antagonists, delta FS: 11.8 +/- 3.3 vs. 5.1 +/- 4.1%, p < 0.05; delta ET/PEP: 11.9 +/- 2.3 vs. 4.7 +/- 6.4%, p < 0.05; delta IRT: -12.0 +/- 3.4 vs. -3.8 +/- 6.1%, p < 0.05). The results indicate that both ACE inhibitors and Ca antagonists induce significant and similar reductions in blood pressure and LVM in hypertensive patients. ACE inhibitors produce significant improvements in LV function in both systolic and diastolic phases as compared with Ca antagonists.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Changes in nitric oxide generated by the oxidation of oxymyoglobin by nitrite.

We found that nitric oxide (NO) was produced during the oxidation of oxymyoglobin by nitrite, by using a NO-selective electrode system, which enabled us to measure NO in phosphate solution, continuously and quantitatively. When 500 microM nitrite was added in the solution of oxymyoglobin (65 microM in heme), oxymyoglobin was oxidized to metmyoglobin in a sigmoidal manner. During the reaction, NO was generated quickly at the initial lag phase, and reached its peak (NO approximated to 30 microM), before the burst oxidation of oxymyoglobin occurred. Then, NO content was gradually decreased. By the addition of the increased concentration of nitrite (1 mM or 2 mM) to oxymyoglobin solution (65 microM in heme), the production rate of NO was much accelerated and the amounts of NO were increased, in good accordance with the accelerated oxidation of oxymyoglobin by nitrite. These results suggest that NO is involved in the oxidation of oxymyoglobin by nitrite.

Animals↗
PubMed1997

Production of nitric oxide (NO) during the oxidation of human oxyhemoglobin by nitrite: application of a NO-selective electrode for the measurement of NO.

By using a nitric oxide (NO) selective electrode system. NO produced during the oxidation of human hemoglobin by nitrite was monitored. When 160 microM oxyhemoglobin (in heme) was reacted with 500 microM nitrite. NO was generated quickly at the initial lag phase of the oxidation of oxyhemoglobin by nitrite and decreased gradually during the second burst phase of the reaction. While the oxidation of oxyhemoglobin by nitrite proceeded in a sigmoidal manner including the initial lag phase and second burst phase. The maximal amount of NO produced under this condition was estimated to be 48 microM. According to the increase of nitrite concentrations added, the amounts of NO produced at the initial phase increased, being in good accordance with the increased rate of the oxidation of oxyhemoglobin. These results strongly suggest the critical role of NO in the oxidation mechanism of oxyhemoglobin by nitrite.

Electrodes↗
PubMed1997

[Survey of sensitivities of clinical isolates to antibacterial agents (annual report)].

Research groups were formed in 20 institutions nationwide to investigate carbapenem resistance of clinical isolates. Activities of various antibacterial agents, principally carbapenems, were tested against clinical isolates collected from these institutions. The broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) of 17 antibacterial agents for 1,326 strains of 11 bacterial species isolated at the institutions between October and December 1994. The results are as follows: 1. Carbapenems exhibited strong antibacterial activities against MSSA and Streptococcus pneumoniae. Their activities against Enterococcus faecalis were comparable to that of ABPC. Carbapenems showed low activities against MRSA. 2. OFLX exhibited the greatest antibacterial activity against Haemophilus influenzae, followed by MEPM. Antibacterial activities of the other carbapenems were comparable to those of FMOX, CTM, and ABPC. 3. The carbapenems showed high activities against Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and Bacteroides fragilis group. Their activities were greater than those exhibited by other beta-lactam antibacterial agents. The carbapenems also exhibited stronger antibacterial activities against Serratia marcescens than the other beta-lactam antibacterial agents, but some resistant strains were detected. 4. The antibacterial activities of carbapenems against Pseudomonas aeruginosa were comparable to those of CAZ, AZT, AMK.

4-Quinolones↗
PubMed1996

A nitric oxide-sensitive electrode: requirement of lower oxygen concentration for detecting nitric oxide from the tissue.

In order to directly detect nitric oxide (NO) liberated from isolated tissue, a practical and convenient method using a nitric oxide-sensitive electrode is described. To avoid the nonselective signal caused by ionic substances, the electrode was covered with three layers but remains permeable for gaseous substances. In a solution bubbled with 20% oxygen (pO2, approximately 150 mm Hg), administration of S-nitroso-N-acetyl-d, l-penicillamine (SNAP) at concentrations greater than 10(-7) mol/L elicited an electrode response. Based on a comparison with the chemical determination of NO released from SNAP, the electrode may be able to detect nitric oxide around nmol/L. At least 30 nmol NO per liter in anoxic conditions was reported to be detected by this electrode (Matsui, 1995). In a specially designed small chamber, the electrode was attached on the surface of endothelial side of the isolated aorta of the guinea pig. When carbachol was added to the chamber, the electrode responded when the solution was bubbled with 20% but not with 40% or 95% of oxygen, suggesting a much faster decomposition of nitric oxide in the presence of higher concentrations of oxygen. The electrode response to carbachol was abolished in the presence of NG-monomethyl-L-arginine or nitro arginine. These results suggest that the electrode method described in this manuscript is suitable for detecting nitric oxide liberated from isolated tissues when comparatively low oxygen levels are present in the physiological salt solution.

Animals↗
PubMed1996

Clinical significance of pressor responses to laboratory stressor testing in hypertension.

We investigated the relation between pressor responses to laboratory stressors and 24-hour blood pressure (BP) variability or left ventricular mass. Mental arithmetic tests, isometric hand grip exercise, and bicycle ergometer exercise were carried out in middle-aged normotensive subjects (n=10) and in age-matched WHO stage I (n=23) and stage II (n=11) patients with essential hypertension. Mental arithmetic was associated with a greater rate of increase in plasma epinephrine than in norepinephrine, and handgrip exercise was associated with a greater rate of increase in plasma norepinephrine than in epinephrine in all three groups. Bicycle ergometer exercise caused a remarkable increase in plasma norepinephrine and a mild increase in plasma epinephrine in all three groups. In mental arithmetic tests, pressor responses of hypertensive patients were significantly greater than those of normotensives. The pressor response during mental tests was significantly correlated with the value of 24-hour BP variability in all subjects (r=0.56, p< 0.01). The pressor response to handgrip increased with the stage of hypertension. A good correlation existed between the pressor response to handgrip and the left ventricular mass index in the subjects (r=0.73, p < 0.001). There was no difference in the pressor response to ergometer exercise between any of the groups. The findings suggest that the pressor response to mental stress reflects BP variability and that the response to handgrip is correlated with target-organ disease associated with hypertension, especially the degree of cardiac hypertrophy.

Adult↗
PubMed1996

Effects of intermittent food restriction and refeeding on energy efficiency and body fat deposition in sedentary and exercised rats.

The effects of body weight cycling on energy metabolism and body fat accumulation were examined in sedentary and exercised rats. Ten rats were sacrificed before the experiment to obtain basal data, and then 90 rats were divided into three groups; control (CN), food restricted (FR) and weight cycling (WC). Food intake in rats of the FR group was restricted constantly to 70% of the intake of the CN group. The rats of WC group were subjected to four bouts of weight cycling consisting of 7-days food restriction followed by 7-days refeeding, but were fed the same total amount of dietary energy as that of the FR group throughout the experimental period. The rats of all groups were meal-fed twice a day. Half of the rats in each group were exercised by running on a treadmill (30 min/day) throughout the experimental period. The body weight, abdominal adipose tissue weight, body fat, body protein and energy restoration for the study in both sedentary and exercised groups were greater in the WC group than in the FR group. The resting metabolic rate of the WC group after four bouts of weight cycling was lower than that of the FR group in the sedentary rats, but this difference was not observed in the exercised rats. Also, the thermic effect of food (TEF) in the sedentary rats for 6 h after a meal was significantly less in the WC group as compared to that of the FR group. However, the TEF for the exercised rats was not different between the two groups. The serum insulin level, activities of lipogenic enzymes and lipoprotein lipase in adipose tissue for the sedentary rats of the WC group were higher than those of the FR group, but did not differ in the exercised rats. These results suggest that weight cycling increases body fat deposition and energy efficiency by decreasing energy expenditure, particularly the TEF, and that exercise training can alleviate the effects of weight cycling on the energy metabolism.

Adipose Tissue↗
PubMed1996

[A case of thoracic meningioma presenting paraplegia at 4.5 years after removal of a falx meningioma].

A case of a thoracic meningioma presenting paraplegia 4.5 years after removal of a falx meningioma is reported. A 73-year-old woman, complaining of diplopia, was admitted to our department. Neurological examination revealed right abducens palsy. CT demonstrated a well-enhanced right frontal mass beneath the falx. The mass was totally removed under right frontal craniotomy. Its histology was transitional meningioma with rich fibroblasts. 4.5 years after craniotomy, she complained of progressing gait disturbance and nocturnal leg pain. Neurological examination revealed paraplegia, complete loss of leg sensation, loss of patellar and ankle reflex, bilateral positive Babinski reflex and urinary disturbance. Rectal function and anal reflex were preserved. Thoracic MRI demonstrated an intradural extramedullary mass which was well enhanced with Gd-DTPA at Th6-7. Under laminectomy, the mass was totally removed. Its histology was transitional meningioma with rich psammoma bodies and whirl formations. 4 months after removal, her palsy and sensory loss were almost completely recovered. We were able to find 15 cases of combined intracranial and spinal meningiomas in the literature. A young woman of neurofibromatosis suffered from tentorial, intraventricular and C1-2 meningiomas. Of 15 cases without neurofibromatosis including our case, 4 cases were of young boys and 11 cases were of women. Their initial symptoms originated from intracranial meningiomas in 8 cases. Multiple intracranial meningiomas were revealed in only 4 cases. In 9 cases, one case presented a combination of one intracranial meningioma and one spinal meningioma. Histology of intracranial meningioma was almost the same that of spinal meningioma in almost half of the 10 cases. These findings suggest the multi sentricity theory of multiple meningiomas originating in other neuroaxial compartments. Severe spinal dysfunction was recovered after removal in our case. Rectal function and anal reflex were preserved. These anorectal findings suggest that spinal dysfunction is either complete or incomplete. Motor evoked potentials are hopeful tools which can select reversible spinal motor dysfunctions.

Aged↗
PubMed1996

[A case of acromegaly associated with variegated spinal disorders].

A case of acromegaly associated with variegated spinal disorders was reported. The spinal disorders were multiple cervical disc herniations, spinal epidural cavernous angioma, multiple ossification of the spinal ligament and lumbar canal stenosis. A 51-year-old woman with acromegaly, complaining of disturbances of delicate hand movement and gate, consulted our department. Her past history included diabetes mellitus, hypertension and progressing enlargement of her extremities. Serum growth hormone level was 65.7 ng/ml and somatomedin-c level was 746 ng/ml. Brain MRI showed a pituitary tumor extending to the right cavernous sinus. Cervical MRI revealed disc herniations at C5/6 and C6/7. Thoracic MRI revealed osteoporosis, ossification of the posterior longitudinal ligament and multiple ossification of yellow ligament. Lumbar MRI disclosed ossification of yellow ligament and canal stenosis. Anterior fusion of C5-C7 and an intracapsular removal of the pituitary tumor were performed. Its pathology was that of eosinophilic adenoma. After 3 months, she suffered from paraparesis. On repeating MRI examination with Gd-DTPA, a spinal epidural mass was found at T4. Under laminectomy of Th3-5 and Th8-11, the epidural mass and ossified yellow ligament were removed. The epidural mass was cavernous angioma. She was able to walk without any assistance. An association of spinal canal stenosis with acromegaly is well known. But the association of disc herniation and with the ossification of spinal ligaments is rather rare in the literature. Spinal epidural cavernous angioma is very rare. We discussed the etiological aspects and the management of spinal disorders with acromegaly.

Acromegaly↗
PubMed1995

Assessment of working skeletal muscle oxygenation in patients with chronic heart failure.

Patients with chronic heart failure (CHF) are frequently limited by muscle fatigue resulting from impaired skeletal muscle blood flow. Accordingly, we assessed working skeletal muscle oxygenation in such patients using near-infrared (NIR) spectroscopy. Nine normal subjects (mean age 52 years) and 12 patients with CHF (mean age 60 years) were studied. NIR spectroscopy was used to monitor relative changes in oxygenated hemoglobin (Hb) and myoglobin (Mb) (oxy Hb/Mb), deoxygenated Hb and Mb (deoxy Hb/Mb), and total (oxy + deoxy) Hb and Mb (total Hb/Mb) contents in the vastus lateralis muscle at rest, during warm-up (0 W, 30 cycles/min for 3 min), incremental maximal supine bicycle exercise (ramp protocol, 15 W/min, 50 cycles/min), and recovery. At peak exercise the patients exhibited reduced heart rate, systolic blood pressure, peak exercise oxygen consumption (VO2; 15 +/- 3.0 ml/kg/min vs 32 +/- 8.5 ml/kg/min), and workload (99 +/- 23.4 W vs 183 +/- 68.4 W) as compared with the normal subjects. The respiratory quotient was comparable in both groups. In the normal subjects, oxy Hb/Mb was increased from the warm-up period to the early phase of exercise, followed by a progressive decrease to peak exercise. In the recovery phase, oxy Hb/Mb was increased abruptly. For these patients, change in oxy Hb/Mb followed a pattern similar to that seen in normal subjects, and oxy Hb/Mb was decreased earlier in contrast to that in the normal subjects. There was a significant difference in the change of oxy Hb/Mb during warm-up, early phase exercise, and recovery between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise Test↗
PubMed1995

Vasospastic angina in two sisters.

Vasospastic angina was observed in two sisters. The 52-year-old younger sister presented with rest angina at midnight and in the early morning. The coronary arteriogram showed no significant organic stenosis. Vasospasm to the left anterior descending and right coronary arteries was induced by the intracoronary administration of acetylcholine. The 57-year-old elder sister complained of rest and effort angina. Her coronary arteriogram was also normal. Vasospasm to the left circumflex and right coronary arteries was provoked by acetylcholine. In both cases, human leukocyte antigen DQw3 was negative. In the present cases, genetic factors may partly contribute to the mechanism of vasospastic angina.

Acetylcholine↗