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Biomedical subjects

K Shimamoto

Publications and source records attributed to K Shimamoto.

At least 91 records · Page 5Linked to original sources
PubMed2000

Systemic lupus erythematosus with myocardial dysfunction due to microvasculopathy.

A 25-year-old Japanese woman with systemic lupus erythematosus (SLE) had myocardial dysfunction. Heart catheterization showed normal coronary anatomy. Left ventricular cineangiography demonstrated hypokinesis in the anterior and posterior segments. Myocardial scintigraphy revealed patchy defects in the regions unrelated to coronary arteries. These data suggested that the myocardial dysfunction was due to microvasculopthy. In addition, it was speculated that the microvasculopathy was caused by vasculitis but not by thrombi, since she did not have antiphospholipid syndrome. In support of this speculation, corticosteroid therapy without any thrombolytic agents was effective. This report represents the first live patient with SLE in whom myocardial dysfunction due to microvasculopathy has been demonstrated.

Adult↗
PubMed2000

Delayed onset of pulmonary hypertension associated with an appetite suppressant, mazindol: a case report.

The use of the appetite suppressant agents aminorex and fenfluramine derivatives has been reported as a risk factor for the development of pulmonary hypertension. A 29-year-old female developed pulmonary hypertension suspected to be due to an amphetamine-like appetite suppressant agent, mazindol ((+/-)-5-(p-chlorophenyl)-2,5-dihydro-3H-imidazo [2,1-a] isoindol-5-ol). She was admitted to Sapporo Medical University Hospital with dyspnea due to severe pulmonary hypertension. Twelve months prior to admission, she had taken mazindol continuously for a period of 10 weeks. As yet, her pulmonary hypertension has not completely improved. This is the first reported case of mazindol-associated pulmonary hypertension, which developed after a long latent interval, and it suggests that mazindol is also a risk factor for the development of pulmonary hypertension, making long-term follow-up necessary for patients taking this anorectic agent.

Adult↗
PubMed2000

Congestive heart failure after peripheral blood stem cell transplantation: role of cytokines.

A 32-year-old woman was admitted with the diagnosis of congestive heart failure (CHF) without organic heart disease after peripheral blood stem cell transplantation (PBSCT) for malignant lymphoma. Various cytokines have been reported to be released from stem cells after PBSCT and some have a suppressive effect on myocardial contractility; elevated levels of cytokines have been reported in dilated cardiomyopathy (DCM) and/or CHF patients. In the present case, elevated levels of interleukin (IL)-6 and tumor necrosis factor-alpha (TNF-alpha) were observed, and there was a parallel relationship between the recovery of cardiac function and the decrease of these cytokines, strongly suggesting that the release of IL-6 and TNF-alpha after PBSCT might have been important in the pathogenesis of the CHF.

Adult↗
PubMed2000

An experimental teleradiology transmission system using a high-speed ATM backbone network.

We evaluated the performance of an experimental teleradiology system based on a high-speed ATM backbone network. Image acquisition, transmission and the disk-to-display processing times were measured. Computerized tomography (CT) scans printed on 14 inch x 17 inch (36 cm x 43 cm) films were digitized and transferred over the network. The average time for the entire process was 1 min 30 s. Three radiologists interpreted 20 cases. For CT image interpretation, the reading time for one case ranged from 2 to 12 min (mean 6 min 46 s) on a monitor, and from 1 to 3 min (mean 1 min 31 s) with the original film. The ATM backbone network operating at 156 Mbit/s provided sufficient speed for remote consultation. However, further improvements in the operability of the system, especially the image viewing station, are necessary before it will be satisfactory for clinical use.

Computer Systems↗
PubMed2000

Effects of the Chinese medicine, TSJN on insulin resistance and hypertension in fructose-fed rats.

The aim of this study was to determine the effect of Tang-Shen-Jiao-Nang (TSJN), a Chinese medicine used to treat diabetes mellitus, on insulin resistance and hypertension in fructose-fed rats (FFR). Six-week-old male Sprague-Dawley rats were fed either normal rat chow (control) or a fructose-rich chow (FFR) for 6 wk. For the last 2 or 4 wk of a 6-wk period of either diet, the rats were treated by gavage with gum arabic solution as a vehicle (control or FFR) or TSJN (800 mg/kg/d; FFR+TS), and then we performed the euglycemic hyperinsulinemic glucose clamp technique to estimate insulin sensitivity. Systolic blood pressure was measured weekly for 6 wk. At the end of the glucose clamp, the soleus muscle was dissected out for determination of muscle fiber composition by ATPase methods. Systolic blood pressure was elevated at 2 wk after the start of the fructose-rich chow feeding and persisted thereafter throughout the study. Systolic blood pressure during the glucose clamp in the FFR group was significantly higher than that in the control group. Although there was no effect on systolic blood pressure in rats treated with TSJN for the last 2 wk of their 6-wk diet, those treated with TSJN for the last 4 wk of their 6-wk diet had lower systolic blood pressure than did the rats in the FFR group. The average rate of glucose infusion during the glucose clamp, as a measure of insulin sensitivity (M value), was significantly lower in the FFR than in the controls (10.9 +/- 0.6 and 15.4 +/- 0.4, mg/kg/min, for FFR and controls, respectively; p< 0.01). Treatment with TSJN for 2 wk significantly improved the M value compared to that of the control level (15.1 +/- 0.5 mg/kg/min). The composite ratio of type I fibers in the soleus muscle was significantly decreased in the FFR compared to controls (75.0 +/- 1.7 and 81.7 +/- 1.5%, for FFR and controls, respectively; p< 0.01), and treatment with TSJN for 2 wk led to a recovery composite ratio of type I fiber to the same level as that of the control group (78.7 +/- 1.7% in FFR + TS). The M value was significantly correlated with the compositions of type I and type II fibers (for type I fibers, r= 0.45, p < 0.01, for type II fibers, r= -0.44, p< 0.05). These results suggest that the Chinese medicine TSJN may improve insulin resistance, lower the systolic blood pressure, and modulate muscle fiber composition in hypertensive and insulin-resistant fructose-fed rats.

Animals↗
PubMed2000

Blood pressure control in Japanese hypertensives with or without type 2 diabetes mellitus.

Patients with type 2 diabetes mellitus and hypertension are thought to be at high risk for cardiovascular diseases. Recent guidelines for treatment of hypertension such as the JNC VI and WHO/ISH guidelines, recommend that antihypertensive agents be strated at as low as at 130/85 mmHg and that blood pressure be lowered to less than 130/85 mmHg. Our study was designed to clarify how well and to what extent blood pressure (BP) was controlled in Japanese hypertensive patients with or without type 2 diabetes mellitus. We interviewed two hundred physicians, randomly sellected from among the members of the Japanese Society of Hypertension (JSH) (n=98) and the Japanese Diabetes Society (JDS) (n=102) and obtained information regarding five most recent cases of hypertension with (n=954 in total) and their 2 most recent cases of hypertension without diabetes (n=371 in total). The achieved BP was below 140/90 mmHg in 40.5% of non-diabetic and 38.3% of diabetic hypertensives. The percentage of patients whose BP was less than 130/85 mmHg was 10.8% in nondiabetics and 11.4% in diabetics. The average number of hypotensive agents used was 1.46 in nondiabetics and 1.52 in diabetics. Physicians prescribed more ACE inhibitors and alpha-blockers in diabetics than in nondiabetics, although Ca-antagonists were administered in more than 70% of patients irrespective of whether or not they had diabetes. In contrast, fewer beta-blockers and diuretics were administered to diabetics. These results suggest that although Japanese physicians are considering the effects of hypotensive agents on metabolism and renal function when they treat diabetic hypertensives, the achieved blood pressure in both hypertensives with and those without diabetes is insufficient, with only one of ten patients having a blood pressure less than 130/85 mmHg even among diabetics. Improved blood pressure control will therefore be needed to treat high risk groups such as patients with diabetes mellitus.

Adrenergic alpha-Antagonists↗
PubMed2000

Endothelium-dependent coronary response is impaired in the myocardium at an early phase of post-infarct remodeling.

The aim of the present study was to characterize endothelium-dependent and -independent coronary functions in remodeling hearts after infarction. First, echocardiography showed that the left ventricular diastolic dimension and thickness of the non-ischemic region were increased by 25% and 20%, respectively, at 2 weeks after coronary ligation in the rabbit heart. In the second series of experiments, 2 weeks after coronary ligation or a sham operation, the heart was isolated and perfused with modified Krebs-Henseleit buffer at 75 mmHg, and effluent from the pulmonary artery was measured as total coronary flow (CF). Regional CF analysis by microspheres indicated that flow to the infarcted region as a percentage of total CF is negligibly small. There was no significant difference between CF responses to sodium nitroprusside (10(-9)-10(-5) mole/l) in the sham-operated and remodeling hearts. However, the increase in CF after acetylcholine (ACh: 10(-8)-10(-5) mole/l) injection was significantly reduced by approximately 50% in the remodeling hearts compared to that in the sham-operated hearts. Furthermore, the percent increase in CF by ACh (10(-5) mole/l) was inversely correlated with weight of the remodeling myocardium (r = -0.630, p < 0.05). These results suggest that endothelium-dependent vasodilatory function is impaired in the myocardium at the early stage of post-infarct remodeling and that this endothelial dysfunction is closely related to the degree of hypertrophy of the remodeling myocardium.

Acetylcholine↗
PubMed2000

[Insulin sensitizer and hypertension].

Insulin resistance syndrome is the theory that glucose intolerance, hyperinsulinemia, increased very low density lipoprotein triglyceride level, decreased high density lipoprotein cholesterol level, and hypertension are proposed consequences of insulin resistance. In this theory, insulin resistance and the resultant hyperinsulinemia are considered to raise blood pressure through 1) sympathetic nervous system activation, 2) renal sodium retention, 3) renin-angiotensin system stimulation, and 4) intracellular calcium accumulation in vascular smooth muscle. Indeed, metabolic disturbance and insulin resistance have been pointed out in essential hypertensives. The effect of insulin sensitizer on blood pressure have been investigated in human and animal experiments. It has been clarified that troglitazone reduces blood pressure in essential hypertensives and fructose fed rats. However, it has also been reported that troglitazone did not lower blood pressure in SHR and fructose fed rats. Further study will be necessary to clarify the effects of insulin sensitizer on blood pressure.

Animals↗
PubMed2000

[Insulin resistance syndrome and hypertension].

Insulin resistance syndrome is the theory that glucose intolerance, hyperinsulinemia, increased very low density lipoprotein triglyceride level, decreased high density lipoprotein cholesterol level, and hypertension are proposed consequences of insulin resistance. These metabolic disturbances have been shown to increase the risk of coronary artery disease. In this theory, insulin resistance and the resultant hyperinsulinemia are considered to raise blood pressure through 1) sympathetic nervous system activation, 2) renal sodium retention, 3) renin-angiotensin system stimulation, and 4) intracellular calcium accumulation in vascular smooth muscle. Indeed, metabolic disturbance and insulin resistance have been pointed out in essential hypertensives. Leptin is a recently discovered hormone produced by an adipocyte-specific ob gene, that contributes to the regulation of energy balance by informing the hypothalamus of the amount of adipose tissue in the body. As a result, the hypothalamus adjusts food intake, thermogenesis, and energy expenditure appropriately. It was clarified that ob gene expression and plasma leptin level in humans were highly correlated with the body mass index, insulin sensitivity and blood pressure. Thus, leptin could play a role in the pathophysiology of insulin-resistant hypertension.

Coronary Disease↗
PubMed2000

[Intracardiac floating thrombi in patients with acute pulmonary thromboembolism].

The mortality and morbidity associated with residual intracardiac floating thrombi in patients with acute pulmonary thromboembolism remain uncertain. Thirteen patients (2 men and 11 women, mean age 56 +/- 15 years) with pulmonary thromboembolism underwent echocardiography within 24 hours from onset of symptoms. Four patients (31%) had floating intracardiac thrombi in the right heart: 3 in the right atrium and one in the inferior vena cava. The time to evaluation by echocardiography was shorter than in the patients without thrombi. The thrombi disappeared shortly (3.2 +/- 2.4 hr) after thrombolysis without adverse effects in these patients. After thrombolysis, clinical symptoms improved and pressure gradient between the right ventricle and right atrium decreased significantly (p < 0.01) from baseline 47 +/- 6 to 26 +/- 5 mmHg. Major bleeding complications occurred in 3 (43%) of the patients who underwent thrombolysis. Right-side intracardiac floating thrombus was easily detectable by early echocardiography. Thrombolytic agents are likely to be effective in patients with intracardiac floating thrombi.

Acute Disease↗
PubMed1999

Substrate turnover by transporters curtails synaptic glutamate transients.

Although inhibitors of glutamate transport prolong synaptic currents at many glutamate synapses, the cause of the current prolongation is unclear. Transport inhibitors may prolong synaptic currents by simply interfering with synaptic glutamate binding to transporters, by inhibiting substrate translocation, or by promoting accumulation of ambient glutamate, which may act cooperatively at receptors with synaptic glutamate. We show that reversal of the membrane potential of astrocytes surrounding the synapse prolongs synaptic currents but does not decrease the apparent affinity of transporters or significantly alter glutamate-dependent kinetics of macroscopic transporter currents in excised membrane patches. Positive membrane potentials do not affect binding of a nontransported glutamate analog, nor do positive membrane potentials alter the number of transporters available to bind analog. We also test the hypothesis that glutamate accumulation during uptake inhibition by transporter substrates is the direct cause of synaptic current prolongations. Transporter substrates elevate ambient glutamate near synapses by fostering reverse transport of endogenous glutamate. However, increases in ambient glutamate cannot account for the prolongations of synaptic currents, because a nonsubstrate transport inhibitor does not foster reverse uptake yet it prolongs synaptic currents. Moreover, exogenous glutamate does not mimic synaptic current prolongations induced by substrate inhibitors. These results provide strong support for a major role of substrate translocation in determining the time course of the glutamate concentration transient at excitatory synapses.

2-Amino-5-phosphonovalerate↗
PubMed1999

The mechanisms of insulin sensitivity improving effects of angiotensin converting enzyme inhibitor.

It is well-known that angiotensin converting enzyme (ACE) inhibitor not only decreases blood pressure (BP) but also improves insulin sensitivity. To elucidate the mechanisms of these actions of ACE inhibitor, we evaluated its effect on both BP and insulin sensitivity (M-value) as estimated by the glucose clamp technique in essential hypertensives in comparison with the effect of angiotensin receptor (AT) antagonist. We also evaluated the effect of ACE inhibitor on BP, M-value and muscle fiber composition in fructose-fed rats (FFR) as an insulin-resistant hypertensive model with or without treatment with Hoe 140 (kinin receptor antagonist). In essential hypertensives, both ACE inhibitor and AT antagonist decreased BP and improved insulin sensitivity to the same extent. In FFR, ACE inhibitor also decreased BP and improved insulin sensitivity. Moreover, Hoe 140 showed no effect on these actions of ACE inhibitor. The composite ratio of type I fiber of soleus muscle was decreased significantly in FFR compared to control and ACE inhibitor produced a recovery of the composite ratio of type I fiber to the same as control. These results suggested that muscle fiber composition of skeletal muscle is linked to insulin resistance, and that ACE inhibitor may modulate muscle fiber composition through its vasodilative effect in hypertension. These results also suggest that for vasodilation, it is more important to inhibit angiotensin II than to block degradation of kinins or to improve insulin sensitivity by ACE inhibitor.

Angiotensin Receptor Antagonists↗
PubMed1999

The small GTP-binding protein rac is a regulator of cell death in plants.

Cell death plays important roles in the development and defense of plants as in other multicellular organisms. Rapid production of reactive oxygen species often is associated with plant defense against pathogens, but their molecular mechanisms are not known. We introduced the constitutively active and the dominant negative forms of the small GTP-binding protein OsRac1, a rice homolog of human Rac, into the wild type and a lesion mimic mutant of rice and analyzed H(2)O(2) production and cell death in transformed cell cultures and plants. The results indicate that Rac is a regulator of reactive oxygen species production as well as cell death in rice.

Amino Acid Sequence↗