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S Homma

Publications and source records attributed to S Homma.

At least 145 records · Page 8Linked to original sources
PubMed1996

Estrogen modifies the baroreceptor-induced responses of supraoptic vasopressin neurons in the ovariectomized rat.

Effects of estrogen (E2) and estrogen plus progesterone (EP) on the baroreceptor-induced response of the spontaneous discharge activity in the supraoptic (SON) vasopressin (AVP) neurons were examined in ovariectomized (OVX) female rats. An increase or a decrease in arterial blood pressure induced by intravenous injection of phenylephrine or nitroprusside, resulted in an inhibition or an acceleration of the discharge activity in the identified AVP neurons. The slopes that were derived from a least squares regression line for the arterial blood pressure and baroreceptor-induced responses of AVP neurons in both OVX + E2 and OVX + EP rats were statistically smaller (P < 0.05) than that in the control OVX rat. These results suggest a functional relationship between ovarian endocrine and autonomic functions in the female rat.

Animals↗
PubMed1996

Variability of right ventricular functional recovery after lung transplantation.

BACKGROUND: The purpose of this study was to assess by echocardiography the effects of lung transplantation on recovery of right ventricular (RV) function in patients with preoperative RV dysfunction. METHODS: Fourteen (20%) of 71 lung transplant recipients were identified by echocardiography as manifesting abnormal RV function before lung transplantation. These 14 patients were selected for follow-up echocardiographic study 8 months after transplantation. RESULTS: RV function improved significantly in the study group. Mean RV end-diastolic area decreased from 26.8 +/- 7.9 cm2 to 20.1 +/- 4.7 cm2 (P < 0.01); mean RV end-systolic area decreased from 21.5 +/- 6.8 cm2 to 13.1 +/- 4.2 (P < 0.01); and mean RV fractional area change (FAC) increased from 20.4 +/- 3.3% to 35.8 +/- 8.9% (P < 0.001). A subgroup of four patients, however, exhibited no change in RV function. Patients who achieved improvement in RV function tended to be younger, had shorter duration of disease before transplantation, and had higher pulmonary arterial (PA) pressures before transplantation (PA systolic, 89 +/- 28 mmHg vs. 38 +/- 11 mmHg, P < 0.001; PA diastolic, 42 +/- 11 mmHg vs. 19 +/- 3 mmHg, P < 0.002). Each of the eight patients with primary pulmonary hypertension exhibited improvement in RV function (mean delta FAC +20.6 +/- 5.9%), while two of three patients with emphysema and both patients with idiopathic pulmonary fibrosis failed to achieve improvement in RV function (mean delta FAC +2.3 +/- 1.2%). CONCLUSIONS: Improvement of RV function assessed by echocardiography occurs after lung transplantation, even in patients with severe preoperative RV dysfunction. However, the degree of improvement is variable and may depend on the degree of RV after-load reduction and the presence or absence of intrinsic myocardial disease. RV ejection parameters do not distinguish between these two possibilities.

Adolescent↗
PubMed1996

Testosterone-dependent induction of metallothionein in genital organs of male rats.

Metallothioneins (MTs) are a group of cysteine-rich heavy-metal-binding proteins. We have investigated MT gene expression in the ventral and dorsolateral lobes of the prostate and coagulating gland of male Wistar rats. In intact rats, both MT mRNA and MT were present in the dorsolateral lobe and coagulating gland but not in the ventral lobe. Orchidectomy caused involution of the above organs, and both MT mRNA and MT were considerably decreased or become undetectable. An injection of testosterone propionate into orchidectomized rats restored not only the size of these organs, but also MT mRNA and MT concentrations, particularly in the dorsolateral lobe and coagulating gland. In the dorsolateral lobe, no selective uptake of Zn2+ preceding the increase in MT was observed, suggesting that Zn2+ ions are not associated with the increased expression of the MT gene. The present result suggests that of the male auxiliary genital organs, the dorsolateral lobe and coagulating gland, but not the ventral lobe, contain MT, the biosynthesis of which is regulated by testosterone.

Animals↗
PubMed1996

Osmolality- and angiotensin-induced responses in the AV3V neurons are affected by estrogen in the ovariectomized rat.

The effect of hyperosmolality (300, 320 mosmol/kg H2O) and angiotensin II (A II, 10(-8) and 10(-6) M) was tested on a total of 64 neurons within the periventricular part of the anteroventral third ventricle (AV3V) region in brain slice preparations obtained from ovariectomized (OVX) rats with or without chronic treatment of estradiol-17 beta (E2). Hypertonic perfusion with a 320 mosmol/kg H2O but not a 300 mosmol/kg H2O medium caused a significant increase in the firing discharge rate in OVX animals. Perfusion with either hypertonic medium had no effect in E2-treated rats. The neuronal firing discharge rate of neurons in OVX rats was increased following perfusion with 10(-6) M A II, but not affected following perfusion with 10(-8) M A II. In E2-treated rats, perfusion with neither 10(-8) nor 10(-6) M A II had any effect. These data suggest a dynamic relationship between the ovarian endocrine function and the central mechanisms regulating dipsogenic behavior and/or release of vasopressin in the female rat.

Angiotensin II↗
PubMed1996

Intravascular ultrasound imaging of human cerebral arteries.

The aim of this study was to assess the feasibility of imaging cerebral arteries in vitro with intravascular ultrasound and to establish a correlation between echographic images and corresponding histological architecture. Intravascular ultrasound imaging was performed using a 30-MHz, 4.3F ultrasound probe. Twenty-two arterial segments were obtained at autopsy from 6 patients and were imaged fresh. Arteries were then processed for histological examination and comparisons were made between echographic and histological findings. The correlation between luminal area measurements as determined histologically and by intravascular ultrasound was tested by linear regression analysis. Intravascular ultrasound demonstrated a three-layered appearance in normal cerebral arteries but not in those affected by severe atherosclerosis. Overall, ultrasound correctly identified the presence of a plaque in 83% of patients. Intravascular ultrasound sensitivity and specificity, respectively, were 100 and 80% for calcium deposits and 83 and 75% for fibrous tissue. Intravascular ultrasound and histological measurements correlated well for the determination of luminal area (r = 0.89). Intravascular ultrasound provides accurate characterization of the arterial lumen and geometry, as well as the presence and histological features of atherosclerotic plaque. Thus, it appears to have a great potential for an earlier and more accurate diagnosis of atherosclerosis and may serve to guide new interventional techniques being utilized in the treatment of cerebrovascular diseases.

Aged↗
PubMed1996

Near-infrared estimation of O2 supply and consumption in forearm muscles working at varying intensity.

We estimated a blood flow index, O2 supply index, and O2 consumption index from near-infrared (NIR) signals during venous occlusion imposed at rest and immediately after handgrip exercise with loads equal to 5, 10, 15, 20, 25, and 30% of the maximum voluntary contraction. We also estimated forearm blood flow (BFfa) by strain-gauge plethysmography and forearm O2 consumption (VO2fa) by the invasive method. There was a significant correlation between the rate of increase in total hemoglobin during venous occlusion obtained from NIR signals and BFfa in each subject (r = 0.853 approximately 0.981, P < 0.001). There was also a significant correlation (r = 0.854 approximately 0.944, P < 0.001) between the O2 consumption index estimated from NIR signals and VO2fa. The mean values for O2 supply index in five subjects increased with exercise intensity, while the O2 consumption index showed no further increase about 25% of maximum voluntary contraction. We found significant positive correlations between the O2 supply index and BFfa (r = 0.986, P < 0.001) and the O2 consumption index and VO2fa (r = 0.976, P < 0.001) during exercise at 5-30% of maximum voluntary contraction. These results demonstrate that analysis of NIR signals during venous occlusion provides an advantageous method of estimation of O2 supply and consumption in working muscles during exercise of varying intensity.

Adult↗
PubMed1996

Aortic atheromas and acute ischemic stroke: a transesophageal echocardiographic study in an ethnically mixed population.

PURPOSE: Proximal aortic atheromas have been suggested as a potential ischemic stroke determinant in the elderly, especially in cases of unexplained (cryptogenic) stroke. Our aim was to assess the potential role of proximal aortic atheromas as an independent risk factor for stroke by comparing their frequency in patients with acute ischemic stroke and in stroke-free control subjects. The frequency of atheromas was also compared among different ethnic groups. PATIENTS AND METHODS: A case-control study was conducted in 106 patients with acute ischemic stroke and 114 stroke-free control subjects. The presence of atheromas of the proximal portion of the aorta was assessed by biplane transesophageal echocardiography. Atheromas were categorized on the basis of their thickness (0.2 to 0.4 cm, small; > or = 0.5 cm, large) and complexity (i.e., ulceration or mobility). The association between aortic atheromas and ischemic stroke was tested, controlling for patients' demographic variables and stroke risk factors. In stroke patients, subgroup analyses were performed to test the associations between aortic atheromas and stroke diagnostic subtypes (determined cause versus cryptogenic) and presence and degree of carotid stenoses by duplex Doppler examination. RESULTS: The frequency of large aortic atheromas was greater in stroke patients than in controls (26% versus 13%; crude odds ratio [OR] 2.4, 95% CI 1.2 to 4.7); ulcerated or mobile atheromas also tended to be more frequent in stroke patients (12% versus 5%; OR 2.5, 95% CI 1.0 to 6.8). Differences were entirely attributable to the subgroup of patients aged 60 years or older, in whom the frequency of ulcerated or mobile atheromas was particularly high among cryptogenic stroke patients (22% versus 8% in control subjects; OR 3.4, 95% CI 1.1 to 11.2). Multivariate analysis showed the presence of large atheromas to be independently associated with stroke in the entire study group (adjusted OR 2.6, 95% CI 1.1 to 5.9) and in the older subgroup (OR 2.4, 95% CI 1.1 to 5.7). Carotid stenosis > or = 60% was more frequent with increasing size and complexity of aortic atheromas but had low predictive value (16%) for presence of large atheromas; moreover, 36% of patients with mild or no carotid stenosis had large or complex aortic atheromas. No significant differences were found in the frequency of atheromas by ethnic group. CONCLUSIONS: Proximal aortic atheromas > or = 0.5 cm in size are a risk factor for ischemic stroke in patients aged 60 years or older. Ulcerated or mobile atheromas may play a role in explaining some cryptogenic strokes in the elderly. The risk for stroke of patients with aortic atheromas may be similar across different ethnic groups. The absence of carotid stenosis does not exclude aortic atheromas as a potential cause for ischemic stroke.

Acute Disease↗
PubMed1996

Immunohistological evaluation on respiratory lesions of pigs intranasally inoculated with Actinobacillus pleuropneumoniae serotype 1.

Nine-week-old pigs were inoculated intranasally with 6.10 X 10(3) (group 10(3)), 10(5) (group 10(5)) and 10(7) (group 10(7)) colony-forming unit of Actinobacillus pleuropneumoniae (App) serotype 1 designated HA-337 strain, respectively. One pig in group 10(5) and 2 pigs in group 10(7) died with dispnea and hemorrhagic pleuropneumonia within 20 to 48 hr post inoculation (PI). All pigs necropsied on 7 days in groups 10(5) and 10(7) had focal fibrous pleuropneumonia. Histologically, pulmonary lesions were classified into three stages; peracute, acute and subacute. Fatal cases in group 10(7) had peracute lesion composed of severe edema, hemorrhage and necrobiosis of alveoli, with mononuclear cells infiltration in the dilated interlobulus. The fatal case in group 10(5) had acute pulmonary lesion composed of focal or linear infiltration of round and fusiform cells that frequently showed swirling pattern in alveoli. The surviving cases in group 10(5) and 10(7) had subacute lesion composed of multifocal pulmonary necrosis surrounded by fibrous tissue. The swirling pattern was clearly seen in demarcation zone. Immunohistochemically, App antigens scattered as intact bacteria in alveoli, dilated interlobular septa and pleura, and lymph vessels in peracute and acute lesions. Areas of necrosis were also stained weakly. Although no antigen was detected in cytoplasm of macrophages and infiltrated cells in peracute lesions, App antigen was detected as positively stained mass in cytoplasm of some macrophages in acute lesions. In subacute lesions, App antigens were recognized as intact bacteria in necrotic areas and among the swirling pattern cells of demarcation zone. Macrophages had App antigens as a large mass of pigment in the cytoplasm in area of fibrosis.

Actinobacillus Infections↗
PubMed1996

[Changes in intestinal motility after massive small bowel resection with a reversed jejunal segment].

To evaluate the functioning and effectiveness of a 20-cm reversed jejunal segment after 75-80% massive small bowel resection (MSBR), and whether migrating polarity changes or not, we continuously measured the postoperative bowel motility (using bipolar electrodes and/or contractile strain gage force transducers) in interdigestive and postprandial conscious dogs in short- (2-5 weeks) and long-term (6-10 months) after surgery. The fasting migrating myoelectric (or motor) complex (MMC) arising from the duodenum was often interrupted at the jejunum above the proximal anastomosis and did not migrate smoothly to the reversed segment or terminal ileum. In addition, brief small discordant contractions were frequent in the jejunum above the proximal anastomosis and the proximal part of the reversed segment. The duodenal MMCs predominantly propagated to the ileum through the inherent anatomic continuity of the bowel. These findings of the MMC propagation pattern are very similar in short- and in long-term after surgery. The duration of the postprandial period without duodenal MMC activity was markedly longer in short-term, but shorter in long-term (both were significantly longer than in controls). Marked dilatation of the jejunum and reversed jejunal segment was noted across the proximal anastomosis. These results suggest that the transit time and passage of intestinal contents can be delayed and stagnated for at least 10 months after MSBR with a 20-cm reversed jejunal segment. Although, reports on the polarity of peristalsis in the reversed segment in long-term followup have been contradictory in both experimental and clinical studies, this results support the conclusion that the reversed jejunal segment maintains its inherent propagative polarity and pattern over a long postoperative period.

Anastomosis, Surgical↗
PubMed1996

PMA and ionomycin differently affect atrial natriuretic peptide stimulated cyclic GMP production in rat mesangial cells.

How 4 beta-phorbol 12-myristate 13-acetate (PMA) and ionomycin (Io), a calcium ionophore, affect on the atrial natriuretic peptide (ANP) stimulated cyclic-3',5'-guanosine monophosphate (cGMP) production in cultured rat mesangial cells was examined. Cultured mesangial cells were prepared by isolated glomeruli from Sprague Dawley rats employing the sieving method and were used between the 3rd and 15th passage for experiments. cGMP and protein contents were measured by radioimmunoassay and Lowry method. Incubations with effectors were carried out either in the presence or absence of 0.5 mM 1-methyl-3-isobutyl-xanthine (MIX). The intracellular concentration of calcium ([Ca2+]i) was determined by using the Fura-2 method. Pretreatment with PMA, an activator of protein kinase C (PKC), attenuated ANP stimulated cGMP production in a time- and dose-dependent fashion, while alpha PDD (an inactive analog of PMA) did not inhibit cGMP production. PMA inhibition was reversed by addition of staurosporine, a protein kinase C inhibitor. Io attenuated ANP stimulated cGMP production in the absence but not in the presence of MIX. These findings suggested that PMA acts on ANP receptor or guanylate cyclase via activation of PKC in rat mesangial cells. Io may inhibit ANP stimulated cGMP production via activation of cyclic nucleotide phosphodiesterase.

1-Methyl-3-isobutylxanthine↗
PubMed1996

The clinical features and treatment of arteriosclerosis obliterans with diabetes.

The objective of this study was to clarify the differences, if any, in the clinical features between diabetic and nondiabetic patients with arteriosclerosis obliterans (ASO) and to select the optimal treatment for diabetic patients with ASO. The 171 patients with ASO studied were classified into nondiabetic and diabetic groups. Each group was subdivided into an intermittent claudication (IC) group and ulcer and necrosis (ULC) group. The frequency of complications with cardiac and cerebral vascular diseases and risk factors of arteriosclerosis were analyzed. Ankle and brachial blood pressure and ankle/brachial pressure index (API) were measured, and blood rheological parameters of filterability using Nuclepore filter membrane and viscosity of whole blood and plasma were measured. Three indexes of walking distance were measured by our ASO-Treadmill protocol to evaluate quantitatively the effect of treatment. There were 95 diabetic patients with ASO and 76 nondiabetic patients. Of the nondiabetic patients, 81 had IC and 14 had ULC, and of the diabetic patients, 63 had IC and 13 had ULC. The diabetic group showed more frequent complications with coronary heart disease (56.5 vs. 25.6%), but the two groups showed the same frequency of cerebrovascular diseases (30%). The diabetic ULC subgroup showed higher fasting plasma glucose than the diabetic IC subgroup. The API of the ULC subgroup was significantly lower than that of the IC subgroup in the nondiabetic patients, whereas that of the ULC subgroup was not significantly lower than that of the IC subgroup in the diabetic patients. Stenotic lesions of arteriography in both the nondiabetic and diabetic ULC subgroups demonstrated a tendency toward multisegmental and below-knee lesions compared with the two IC subgroups. For blood rheology-related factors, the diabetic ASO subgroup demonstrated a significantly elevated fibrinogen level compared with the normal control value, for patients of average age. After walking exercise treatment, a significant increase in the walking distance was obtained. After treatment with Cilostazol, prostaglandin I2 analog, and LDL apheresis, the rheological indexes were significantly improved, while the API did not change. We conclude that therapeutic improvement of blood rheological properties would be effective for prolongation and improvement of the quality of life for diabetic patients with ASO.

Aged↗
PubMed1996

A simplified method for the estimation of glutathione peroxidase activity and selenium concentration in bovine blood.

Twelve hybridoma clones were established that produced mouse monoclonal antibodies to bovine erythrocyte glutathione peroxidase. In these monoclonal antibodies, GPF-1, GPI-2, and GPJ-1, which showed marked reaction to this enzyme, were examined for reactivity to erythrocyte lysates from 12 different species of animals and from humans and for the inhibition of glutathione peroxidase activity. GPF-1 and GPJ-1 reacted markedly with glutathione peroxidase in erythrocyte lysates from ruminants and pigs and inhibited enzymatic activity. Conversely, GPI-2 showed positive reaction to hemolysate from all mammals used, except for mice, and did not inhibit enzymatic activity. To determine the concentration of bovine glutathione peroxidase in erythrocyte lysates, a sandwich ELISA was developed using GPJ-1, both as a coated antibody and as a peroxidase-labeled antibody. This ELISA system was a sensitive procedure with a detection limit of 6 ng/ml for glutathione peroxidase protein. Using blood samples from 121 cows, optical density by this ELISA was well correlated with the glutathione peroxidase activity and with the selenium concentration in bovine whole blood. The sandwich ELISA using GPJ-1 is a rapid and simple screening method to estimate glutathione peroxidase activity and selenium concentration in bovine whole blood.

Animals↗