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Biomedical subjects

M Shimizu

Publications and source records attributed to M Shimizu.

At least 883 records · Page 49Linked to original sources
PubMed1993

Forskolin and phorbol myristate acetate inhibit intracellular Ca2+ mobilization induced by amitriptyline and bradykinin in rat frontocortical neurons.

Regulations of the increase in intracellular Ca2+ concentration ([Ca2+]i) and inositol 1,4,5-trisphosphate (IP3) production by increasing intracellular cyclic AMP (cAMP) levels or activating protein kinase C (PKC) were studied in rat frontocortical cultured neurons. Amitriptyline (AMI; 1 mM), a tricyclic antidepressant, and bradykinin (BK; 1 microM) stimulated IP3 production and caused transient [Ca2+]i increases. Pretreatment with forskolin (100 microM, 15 min) decreased the AMI- and BK-induced [Ca2+]i increases by 33 and 48%, respectively. However, this treatment had no effect on the AMI- and BK-induced IP3 productions. Dibutyryl-cAMP (2 mM, 15 min) also decreased the AMI- and BK-induced [Ca2+]i increases by 23 and 47%, respectively. H-8 (30 microM), an inhibitor of protein kinase A (PKA), attenuated the ability of forskolin to inhibit the AMI- and BK-induced [Ca2+]i increases, suggesting that the activation of cAMP/PKA was involved in these inhibitory effects of forskolin. On the other hand, forskolin treatment had no effect on 20 mM caffeine-, 10 microM glutamate-, or 50 mM K(+)-induced [Ca2+]i increases. Pretreatment with phorbol 12-myristate 13-acetate (PMA; 100 nM, 90 min) decreased both the AMI-induced [Ca2+]i increases and the IP3 production by 31 and 25%, respectively. H-7 (200 microM), an inhibitor of PKC, inhibited the ability of PMA to attenuate the [Ca2+]i increases. PMA also inhibited the BK-induced IP3 production and the [Ca2+]i increases.(ABSTRACT TRUNCATED AT 250 WORDS)

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1993

Increased left atrial chamber stiffness in hypertrophic cardiomyopathy.

OBJECTIVE: To investigate left atrial chamber stiffness and its influence on left atrial and left ventricular functions in hypertrophic cardiomyopathy. DESIGN: Prospective study. SETTING: Department of internal medicine in a university teaching hospital. PATIENTS: Five control subjects, six patients with essential hypertension, and 11 patients with hypertrophic cardiomyopathy. INTERVENTIONS: Measurement of left atrial pressure by a tip micromanometer and of real-time left atrial volume from left atrial cineangiograms. MAIN OUTCOME MEASURE: Left atrial stiffness constant determined by fitting the ascending limb of the v loop of the left atrial pressure-volume relation to an exponential curve. RESULTS: The mean (SD) left atrial chamber stiffness constant was significantly larger in patients with hypertrophic cardiomyopathy than in controls (0.063 (0.018) v 0.041 (0.006), p < 0.05) and was correlated with left ventricular wall thickness (r = 0.560, p < 0.01). Left atrial reservoir volume (left atrial emptying volume before atrial contraction) was significantly smaller in patients with hypertrophic cardiomyopathy than in the controls (7.3 (2.1) v 12.5 (4.4) ml/m2, p < 0.01) and was inversely correlated with the left atrial chamber stiffness constant (r = -0.598, p < 0.01). The cardiac index was inversely correlated with the left atrial chamber stiffness constant (r = -0.542, p < 0.01). CONCLUSIONS: Left atrial chamber stiffness was increased in patients with hypertrophic cardiomyopathy and this affected the left atrial reservoir function. This may in turn have affected cardiac output.

Atrial Function, Left↗
PubMed1993

Collagen remodelling in myocardia of patients with diabetes.

AIMS: To investigate collagen remodelling in the interstitium of the heart in patients with diabetes. METHODS: Immunohistochemical study of the biopsied myocardium using type specific anticollagen antibodies (I, III, IV, V, VI) was performed in 12 patients with non-insulin dependent diabetes mellitus and six non-diabetic patients. There was no history of hypertension or coronary artery stenosis in any of the patients. RESULTS: Noticeable accumulations of collagen types I, III, and VI in the myocardial interstitium were recognised in both groups, but little accumulation of types IV or V was found. Types I and III mainly stained in the perimysium and perivascular region, while type VI predominantly stained in the endomysium. There was no disease specific accumulation of collagen in diabetes mellitus. The percentage of total interstitial fibrosis in the myocardium was significantly higher in the diabetic group than in the control group (p < 0.05). Although the percentages of collagen types I and VI did not differ between the two groups, the percentage type of III was significantly higher in the diabetic group than in the controls (p < 0.01). CONCLUSIONS: Collagen remodelling mainly as a result of an increase in collagen type III in the perimysium and perivascular region, occurs in the hearts of patients with diabetes.

Adult↗
PubMed1993

Abdominal aortic aneurysms in familial hypercholesterolemia--case reports.

Familial hypercholesterolemia (FH) is a genetic disease characterized by high serum cholesterol levels and premature coronary atherosclerosis. Hypercholesterolemia is one of the factors promoting the arteriosclerotic process and is a major cause of aortic aneurysm. Few data are available, however, about abdominal aortic aneurysms (AAAs) in patients with FH. In this study, the clinical and angiographic characteristics of AAAs found in patients with FH were investigated. Thirty-one cases (23 men, 8 women, aged fifty +/- fourteen years) were examined by coronary angiography, thoracic and abdominal aortography, and clinical data. Abdominal aortography detected abdominal aneurysms in 8 cases (26%), all of whom were men, including 4 cases (50%) that were complicated by diabetes mellitus. The abdominal aneurysm patients manifested severe coronary atherosclerosis, severe abdominal aortic irregularity, and higher blood pressure than the nonaneurysm FH patients. These findings suggest that AAAs are an important and prevalent feature in FH, especially in men with diabetes mellitus and high blood pressure.

Adult↗
PubMed1993

2'-Hydroxymatteucinol, a new C-methyl flavanone derivative from Matteccia orientalis; potent hypoglycemic activity in streptozotocin (STZ)-induced diabetic rat.

The CHCl3 extract of Matteccia orientalis showed very strong hypoglycemic activity in streptozotocin (STZ)-induced diabetic rats. A new C-methyl flavanone derivative, 2'-hydroxymatteucinol (3) was isolated from the hypoglycemic activity bearing fraction, along with two known compounds, demethoxymatteucinol (1) and matteucinol (2). The structures of these isolated compounds were elucidated by spectroscopic methods. One of the compounds isolated from CHCl3 extract, 2'-hydroxymatteucinol (3), showed dose-dependent hypoglycemic activity, and a blood sugar lowering effect was observed even at the dose of 10 mg/kg (p.o.) in STZ-induced diabetic rats.

Animals↗
PubMed1993

Closure of ventricular septal rupture caused by acute myocardial infarction using a transaortic balloon catheter.

We report a case of successful transaortic closure of a postinfarction ventricular septal rupture using a Swan-Ganz catheter. The method markedly reduced a left-to-right shunt and the improved hemodynamic condition of the patient, an 81-year-old woman, was maintained for about a week before surgical treatment. Inflation of the balloon with water made the balloon visible via echocardiography and was effective in maintaining inflation and echocardiographic follow-up.

Aged↗
PubMed1993

Preload dependency of left atrial pump function in hypertrophic cardiomyopathy.

In our previous study, we reported that the left atrial contribution to left ventricular filling was decreased to a greater extent in patients with hypertrophic cardiomyopathy than in those with myocardial infarction or normal subjects during lower body negative pressure (LBNP)-induced preload reduction. To clarify the factors responsible for this difference in response, we examined changes in left atrial hemodynamic and M-mode echocardiographic indices during LBNP in patients with hypertrophic cardiomyopathy and myocardial infarction. The same degree of decrease in left atrial preload and afterload was found in both groups. Moreover, we detected no change in the left atrial fractional shortening during left atrial systole (%LAFS) in patients with hypertrophic cardiomyopathy, in contrast to a significant increase found in patients with myocardial infarction. These results showed that the greater decrease in the left atrial contribution in hypertrophic cardiomyopathy during LBNP could not result from differences in changes in left atrial preload or afterload, suggesting that it may be closely related to limitations in the compensatory augmentation of left atrial contractility.

Atrial Function, Left↗
PubMed1993

Functional limitation of recruitable collaterals in human subjects--ST segment deviation on intracoronary electrocardiogram during transient coronary occlusion induced by balloon inflation.

Three patients showed ST elevation on precordial electrocardiogram and ST depression on intracoronary electrocardiogram during angioplasty of the left anterior descending coronary arteries (LAD). While none of the patients had spontaneously visible collaterals, all showed transient recruitable collaterals to the LAD. No evident collaterals into the diagonal branches were observed. Possibly, if the intracoronary electrocardiogram represents the potential changes of the epicardial surface in the vicinity of the guidewire tip, then endocardial ischemia may have developed even though epicardial ischemia was not observed, due to relatively sufficient blood flow through the recruitable collaterals to the LAD. ST elevation on the precordial electrocardiogram may have represented epicardial and endocardial ischemia of the diagonal branches, where the recruitable collaterals could not protect against transmural ischemia. These phenomena suggests that the recruitable collaterals are functionally limited during acute coronary occlusion, even though the collaterals are well developed.

Aged↗
PubMed1993

Involvement of alpha 1- but not alpha 2-adrenergic systems in the antagonizing effect of paeoniflorin on scopolamine-induced deficit in radial maze performance in rats.

Paeoniflorin, a major constituent of peony root (1 mg/kg, p.o.), attenuated scopolamine-induced deficit in radial maze performance. Both prazosin (0.5 mg/kg, i.p.) and yohimbine (0.3 mg/kg, i.p.) neither impaired radial maze performance by itself nor augmented the scopolamine-induced performance deficit. Prazosin significantly blocked the antagonizing effect of paeoniflorin on the scopolamine deficit, whereas yohimbine did not affect the paeoniflorin effect. These data suggest that the alpha 1-adrenergic but not alpha 2-adrenergic systems are involved in the antagonizing effect of paeoniflorin on the scopolamine deficit in radial maze performance in rats.

Animals↗
PubMed1993

Involvement of beta-adrenergic systems in the antagonizing effect of paeoniflorin on the scopolamine-induced deficit in radial maze performance in rats.

Paeoniflorin, a major constituent of peony root, has been demonstrated to attenuate the radial maze performance deficit produced by scopolamine. In the present study, to investigate the possible involvement of beta-adrenergic systems in the paeoniflorin antagonism of the scopolamine deficit, the effects of two beta-adrenoceptor antagonists, propranolol and atenolol, on the paeoniflorin effect were examined in male Wistar rats. Paeoniflorin (1 mg/kg, p.o.) significantly attenuated the scopolamine HBr (0.3 mg/kg, i.p.)-induced deficit in the choice accuracy in radial maze performance without changing the running time prolonged by scopolamine. Neither D,L-propranolol HCl, a lipophilic beta-antagonist, at 3 mg/kg, i.p. nor atenolol, a hydrophilic beta 1-antagonist that is known to hardly ever cross the blood-brain barrier, at 1 mg/kg, i.p. impaired maze performance by itself or aggravated the scopolamine-induced deficit in radial maze performance. Both antagonists, however, completely blocked the antagonizing effect of paeoniflorin on the scopolamine deficit. These data suggest that the beta-adrenergic systems, especially peripheral beta 1-adrenergic systems, are involved in the antagonizing effect of paeoniflorin on the scopolamine deficit in radial maze performance in rats.

Animals↗
PubMed1993

Encapsulation of chicken egg yolk immunoglobulin G (IgY) by liposomes.

Encapsulation of antibodies isolated from chicken egg yolk (IgY) in egg lecithin/cholesterol liposomes was attempted. IgY was successfully encapsulated into the liposomes by using the dehydration-rehydration method. Electron microscopic observation demonstrated that the liposomes prepared by this method were large multilamellar vesicles with a diameter of several microns. The encapsulation efficiency was improved by increasing the rehydration temperature to 60 degrees C. The cholesterol/lecithin ratio also affected the efficiency, giving the highest value at a ratio of 1/4 (mol/mol). Some efflux of glucose through the liposomal membranes was observed, particularly for the liposome with a low cholesterol content, but that of IgY was not detected, irrespective of the cholesterol content. Encapsulation reduced the activity loss of the IgY antibodies under acidic conditions. IgY encapsulated in the liposomes was also markedly resistant to pepsin hydrolysis, which usually results in complete loss of activity with unencapsulated IgY, suggesting that liposomal encapsulation is an effective means for protecting IgY under gastric conditions.

Animals↗
PubMed1993

Emulsifying and oil-binding properties of bovine serum albumin and its enzymatic hydrolyzate.

Bovine serum albumin (BSA) was hydrolyzed with proteases, and the emulsifying and oil-binding properties of the hydrolyzates were then studied. By limiting hydrolysis with trypsin, the emulsifying activity index (EAI) increased about 40% above its original level. In order to find out which peptides contributed to the good emulsifying properties of the hydrolyzate, the peptides adsorbed onto the emulsified oil globule surface were extracted and analyzed. SDS-polyacrylamide gel electrophoresis showed that a peptide with a molecular weight of about 24kDa was preferentially adsorbed onto the oil surface. This 24kDa peptide was found to be fairly hydrophobic and corresponds to the third domain of BSA, residues 377-582. In spite of the preferential adsorption characteristics of the 24kDa peptide, this peptide itself had a lower EAI value than that of the whole hydrolyzate. The contribution of some small hydrophilic peptides, as well as the 24kDa peptide, to the good emulsifying properties of the BSA hydrolyzate was suggested.

Adsorption↗
PubMed1993

Effects of oral administration of chlormadinone acetate on canine prostatic hypertrophy.

Seven of the 25 dogs (4 to 15 years old) with benign prostatic hypertrophy (BPH) at the teaching hospital of Nippon Veterinary and Animal Science University from 1989 through 1990 were treated orally with chlormadinone acetate (CMA), a synthetic anti-androgen, 2 mg/kg/day, twice a day for 3 or 4 weeks. Prostatic size was measured by radiography and ultrasonography before and after CMA treatment, and prostatic volume was calculated from the images. Semen quality was examined in 3 of the dogs with BPH. Peripheral blood samples were collected and plasma levels of LH, 4-androstenedione, 5 alpha-dihydrotestosterone, testosterone and estradiol-17 beta were measured. Clinical signs disappeared within 10 days after the start of CMA treatment. The mean (+/- S.E.) prostatic volume 3 or 4 weeks after treatment decreased to 39 +/- 4% of the pretreatment volume. The mean level of plasma testosterone in the dogs with BPH before treatment was significantly lower than that in the normal dogs (P < 0.01). In 6 of the CMA-treated dogs the levels of all hormones examined, except LH, were significantly lower after CMA treatment than before (P < 0.05). The sperm count and motility decreased and the percentage of abnormal sperms increased after CMA treatment. These results demonstrate that, although CMA treatment in dogs with BPH inhibits testicular function, the prostatic volume is markedly reduced and clinical signs disappear in a short period after the therapy. However, a relapse of BPH was observed approximately 6 months after oral CMA treatment in some dogs.

Administration, Oral↗
PubMed1993

Appearance of a regenerating (reg) gene protein in pancreatic islets of remission BB/Wor//Tky rats.

Remission of diabetes, i.e. significant amelioration from absolute insulin-dependency, has been sometimes observed in diabetic BB/Wor//Tky rats which were treated with insulin. In remission BB/Wor//Tky rats, plasma glucose levels improved to near normal level and insulin content was also preserved as much as that between diabetic and non-diabetic rats. In this process, we hypothesized that autoimmune insulitis was suppressed and remaining islet B-cells was restored from severe destruction by recovering in number and/or function. While, recently, a novel regenerating (reg) gene, identified in the regenerating pancreatic islets of surgical models, is reported to be related to the replication of pancreatic B-cells in vitro. Based on these findings, we histologically investigated whether the reg protein could be actually expressed or not in the islets from remission BB/Wor//Tky rats. As expected, reg protein was observed in the islets from remission BB/Wor//Tky rats mainly in accordance with pancreatic B-cells. Thus, the present findings suggested that the regeneration of pancreatic B-cells represented by the expression of reg protein might be, at least in part, relevant to remission induced by insulin therapy in spontaneously occurring Type 1 diabetes in BB/Wor//Tky rats.

Animals↗
PubMed1993

The effects of chemotherapy including cisplatin on vitamin D metabolism.

Plasma concentrations of three major vitamin D3 metabolites, 25-hydroxyvitamin D3 (25-OHD3), 24R, 25-dihydroxyvitamin D3 (24,25-(OH)2D3), and 1 alpha, 25-dihydroxyvitamin D3 (1,25-(OH)2D3), were determined serially in patients with gynecological malignancies treated by chemotherapy which included cisplatin. While 25-OHD3 and 24,25-(OH)2D3 levels did not change regularly, 1,25-(OH)2D3 decreased significantly (50%) after only one or two courses of the treatment in all cases. In concert with declining 1,25-(OH)2D3, the PTH levels increased two or three times. The results were explained by the impairment by cisplatin of mitochondrial function in proximal tubules in the kidney.

24,25-Dihydroxyvitamin D 3↗