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Biomedical subjects

S Shimizu

Publications and source records attributed to S Shimizu.

At least 415 records · Page 23Linked to original sources
PubMed1997

Effect of amino acid and glucose administration during postexercise recovery on protein kinetics in dogs.

To examine the effect of the timing of amino acids (AA) and glucose (G) administration after exercise on protein kinetics, ten dogs fitted with chronic catheters in the artery and the femoral vein ran on a treadmill for 150 min. They were intraportally infused with a solution containing AA and G either right after (E) or 2 h after (L) the exercise. The protein kinetics were estimated using the arteriovenous difference of phenylalanine (Phe) coupled with the [2H5]Phe dilution method. The net balance of Phe across the hindlimb (HL) was negative after exercise. It became positive in E within 15 min after the start of the infusion, and it remained negative in L until the infusion was initiated. The uptake of Phe by the HL during the second half of the infusion period was higher in E than in L (10.9 +/- 6.6 vs. 5.4 +/- 2.3 nmol.kg-1.min-1, P = 0.049). During the infusion, protein synthesis in the HL was higher in E than in L (29.7 +/- 9.6 vs. 22.0 +/- 10.1 nmol.kg-1.min-1, P = 0.028), whereas proteolysis was comparable (18.7 +/- 5.7 vs. 16.5 +/- 11.1 nmol.kg-1.min-1. These results suggest that the early provision of the nutrients after exercise more effectively enhances protein accretion than nutrients administered later.

Amino Acids↗
PubMed1997

Confluent and reticulated papillomatosis responsive to minocycline.

Confluent and reticulated papillomatosis (Gougerot and Carteaud) is a distinctive clinico-pathologic entity of unknown etiology, whose relationship to fungi is still controversial. We report a 15-year-old Japanese male in whom Malassezia yeasts were found on direct microscopic examination. Treatment with oral itraconazole initially resulted in partial improvement but later became ineffective. The rash virtually disappeared with administration of minocycline. These observations indicate that the role of Malassezia yeasts in the pathogenesis of this disease is probably less important than that of microorganisms sensitive to minocycline.

Adolescent↗
PubMed1997

The effects of hypoxia on pHi in porcine coronary artery endothelium and smooth muscle. A novel method for measurements in endothelial cells in situ.

Endothelium-dependent relaxation of porcine coronary arteries is attenuated under hypoxic conditions. Recent evidence also indicates that pHi may modulate the release of the endothelium-derived relaxing factor. We tested the hypothesis that hypoxia-induced attenuation of endothelium-dependent relaxation is mediated by alterations in pHi. We developed a novel method for loading surface cells, whereby endothelial cell pHi could be measured in situ on the intact porcine coronary artery. Endothelial cells of arterial ring segments were selectively loaded with the fluorescent indicator BCECF-AM. Differential loading of the endothelial cell layer was verified by confocal microscopy. pHi of the endothelial cells in situ and of endothelium-denuded arteries was measured with a Photon Technology International spectrofluorimeter. The functional integrity of the endothelium was assessed by the endothelium-dependent relaxation to substance P in a paired adjacent ring. In the experimental protocol for pHi measurements, preparations were perfused with a physiological bicarbonate buffer (pH 7.4), stimulated with KCI (29 mmol/L), and then subjected to hypoxia and reoxygenation. The mean basal pHi in endothelial cells on the intact six arteries was 6.92 +/- 0.07. Addition of KCI to the perfusion medium decreased (P = .025) pHi to 6.79 +/- 0.07. Subsequent bubbling with N2 increased (P = .009) pHi to 7.00 +/- 0.06, which was reversed by reoxygenation. In contrast to the in situ endothelium, pHi of the smooth muscle was not significantly altered from its basal value of 7.24 +/- 0.06 (n = 5) by either KCI or hypoxia. This differential behavior corroborated the confocal data indicating differential dye loading. These data thus suggest that oxygen-sensitive alterations in pHi may be an important mechanism of signal transduction in endothelial cells.

Animals↗
PubMed1997

Oxygen uptake in maximally contracting muscle perfused at low flow with high O2 affinity erythrocytes.

To analyze the roles of blood flow and blood-tissue diffusion in determining oxygen (O2) availability to maximally exercising skeletal muscle, we investigated the influence of low flow on the O2 uptake (VO2)-venous PO2 (PVO2) relation with normal and high O2 affinity erythrocytes. We prepared normal and high O2 affinity erythrocytes by incubating human citrate-phosphate-dextrose-stored erythrocytes with and without cyanate. We perfused maximally contracting gastrocnemius muscle at 4-Hz isometric twitch with solutions containing normal and high O2 affinity erythrocytes for 3 min in anesthetized dogs. During stimulation, perfusion flow was maintained low at 50 ml.min-1.100 g-1 with a perfusion pressure of 50 mmHg. PVO2 for normal affinity erythrocytes (25.6 Torr) was significantly (p < 0.05) higher than that for high O2 affinity erythrocytes (15.9 Torr). Nevertheless, the VO2 for normal and high O2 affinity erythrocytes was approximately the same value, 6.5 ml.min-1.100 g-1 (p > 0.05). The O2 extraction rate was approximately 80% in normal and high O2 affinity erythrocytes. These results indicate that VO2 at low flow was independent of PVO2 in maximally contracting skeletal muscle, although PVO2 was reversely correlated with O2 affinity. We suggest that this PVO2-independency of VO2 at low flow is caused by long red-cell transit time in the capillary without diffusion-limitation and/or a 20% constant arterio-venous shunt of arterial O2 delivery.

Animals↗
PubMed1997

The endothelium-dependent, substance P relaxation of porcine coronary arteries resistant to nitric oxide synthesis inhibition is partially mediated by 4-aminopyridine-sensitive voltage-dependent K+ channels.

We examined the role of K+ channels in the endothelium-dependent relaxation which is resistant to nitric oxide (NO) synthase inhibition in porcine coronary artery. In the presence of 0.2 mM NG-nitro-L-arginine (L-NNA), a potent inhibitor of NO synthase, 10 nM substance P (SP) added to 9,11-dideoxy-11alpha,9alpha-epoxymethano-prostaglandin F2alpha (U46619) contractures elicited a relaxation. The L-NNA-resistant relaxation induced by SP was strongly inhibited by 5 mM tetrabutylammonium chloride (TBA), a non-specific inhibitor of K+ channels. Interestingly, 4-aminopyridine (4-AP, 1 mM), a relatively specific inhibitor of voltage-sensitive K+ channels, shortened the duration of SP response, but it had no effect on the peak of SP response. Although 4-AP has also been shown to inhibit Ca2+-activated K+ channels, the shortening effect of 4-AP in SP response was observed in the presence of 1 microM apamin, an inhibitor of small conductance Ca2+-activated K+ channels, or 100 nM charybdotoxin, and inhibitor of large conductance Ca2+-activated K+ channels. Moreover, although SP stimulates both L-NNA-resistant relaxation and endothelium-derived NO-dependent relaxation (EDNO) in porcine coronary arteries, a low concentration of 4-AP (1 mM) affected only the L-NNA-resistant response, but not the EDNO response. These are the first results to show that the L-NNA-resistant relaxation induced by SP, probably, endothelium-derived hyperpolarizing factor(s) (EDHF) response, is dependent on voltage-dependent K+ channels in porcine coronary artery.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1997

Experimental study of laparoscopic gastrectomy: intracorporeal Billroth I gastroduodenostomy.

Laparoscopic gastrectomy is now performed only for a partial resection that does not require anastomosis. We have been studying laparoscopic gastrectomy using the Billroth I method in animal models, and here we describe the surgical procedure. The gastrocolic ligament is divided along with the greater curvature, and the right gastroepiploic vessels are divided at their point of origin. The lesser omentum is dissected and the gastric antrum is divided using an endoscopic linear cutter. The anvil of a circular stapler is inserted into the duodenal bulb through the pyloric ring and ligated. An instrument for creating a pursestring suture is applied to the anterior wall of the stomach, and the circular stapler is inserted into the gastric lumen. Then Billroth I gastroduodenal anastomosis is performed with the stapler. After this anastomosis, four endoscopic linear cutters are applied to divide the gastric body, and the partial gastrectomy is completed. This animal experimental study has revealed that the Billroth I gastrectomy is easy to perform using a circular stapler and several linear cutters under laparoscopic guidance.

Animals↗
PubMed1997

[The feasibility of CEF (cyclophosphamide, epirubicin, 5-FU) regimen in the adjuvant setting of primary breast cancer].

In Japan, 5-FU/5-FU derivatives or the combination therapy of CAF (cyclophosphamide, CPA; adriamycin, ADM; 5-fluorouracil; 5-FU) have been commonly used for the adjuvant treatment of breast cancer. Recently, a combination of CEF (CPA; Epirubicin, EPI; 5-FU) has come to the stage of adjuvant setting, because the cardiotoxicity was reduced in EPI. In this study, we investigated the feasibility of 6 cycles of CEF (CPA 700 mg/m2, EPI 70 mg/m2, 5-FU 700 mg/m2; day 1 iv every 3-4 weeks) in the adjuvant treatment of primary breast cancer patients with nodal involvements. All 12 patients completed 6 cycles of CEF within 8 months. The median treatment duration was 6.2 months. More than Grade III side effects of neutropenia, nausea/vomiting and alopecia were observed in 7/12 (58.3%), 5/12 (41.7%) and 12/12 (100%), respectively. No serious side effects, including cardiotoxicity, were shown. CEF seems to be feasible regimen as an adjuvant treatment for breast cancer.

Adult↗
PubMed1997

Mechanism of nitric oxide production induced by H2O2 in cultured endothelial cells.

This study examined the mechanism of stimulation of nitric oxide (NO) synthesis induced by hydrogen peroxide (H2O2). To determine the role of Ca2+ on H2O2-induced NO synthesis in bovine aortic endothelial cells, the increases in intracellular Ca2+ and NO production induced by H2O2 were compared with the effects of the Ca2+ ionophore ionomycin in the same batches of endothelial cells. NO production was assessed by formation of [3H]citrulline from [3H]arginine, and changes in intracellular Ca2+ were measured using fluorescent indicator fluo-3 with a confocal laser scanning system. Both H2O2 (1-10 mM) and ionomycin (10(-7)-10(-5) M) increased intracellular Ca2+ and stimulated the synthesis of L-citrulline from L-arginine. Although H2O2 induced only a small increase in intracellular Ca2+, it markedly increased L-citrulline formation compared with ionomycin. Thus, stimulation of NO synthesis induced by H2O2 may involve the mechanisms other than the increases in intracellular Ca2+ in endothelial cells. In the particulate fraction from cultured endothelial cells, addition of exogenous H2O2 (1 mM) or catalase (100 U/ml) did not affect L-citrulline formation. However, co-administration of H2O2 and catalase stimulated L-citrulline formation. These findings suggested that not only the increases in intracellular Ca2+ but also the products by the reaction with H2O2 and catalase are likely to be involved in the stimulation of NO synthesis induced by H2O2.

Aniline Compounds↗
PubMed1997

[Molecular biology of apoptosis].

Apoptosis, a mechanism involving programmed cell death, is important for normal development and maintenance of tissue homeostasis of multicellular organisms. Apoptotic cells are defined by their fragmented nuclei with condensed chromatin, fragmented or condensed cytoplasm and formation of apoptotic bodies. The apoptotic signal transducing pathways activated by a variety of stimuli, including depletion of growth factors, heat shock, cytokines, DNA damaging reagents and crosslinking of Fas receptor, finally converge into the phylogenically conserved apoptotic main machinery, consisting of death-driving ICE-family proteases and anti-cell death protein Bcl-2. Recently, we noted that necrotic cell death induced by chemical hypoxia shares at least some part of the apoptotic main machinery. Using this system, we have shown that Bcl-2 prevents the loss of the mitochondrial membrane potential observed in both apoptotic and necrotic cell death. We also showed that the ICE protease cascade operates in apoptosis and that Bcl-2 functions upstream of the ICE prolease cascade. Here, we review the signal transducing pathway of the apoptotic main machinery.

Animals↗
PubMed1997

Bcl-2 and Bcl-xL block apoptosis as well as necrosis: possible involvement of common mediators in apoptotic and necrotic signal transduction pathways.

The proto-oncogene bcl-2 and a bcl-2-related gene bcl-x prevent apoptotic cell death induced by various treatments. Although a mechanism has been proposed that involves Bcl-2 activity on reactive oxygen species (ROS), we find that expression of Bcl-2 or Bcl-xL prevents cell death induced by withdrawal of oxygen (hypoxia) and that the cell death does not involve ROS, suggesting that Bcl-2 or Bcl-xL exerts an anti-cell death function by a mechanism other than through regulation of ROS activity. Using electron microscopy, and confocal and non-confocal fluorescence microscopy, we show that hypoxia induces both necrosis and apoptosis. Overexpression of Bcl-2 or Bcl-xL blocks hypoxia-induced apoptosis and, although to a lesser extent, necrosis. The anti-apoptotic proteins Bcl-2 and Bcl-xL effectively inhibit KCN-induced cell death which is characterized by necrotic features including apparently intact chromatin, remarkable mitochondrial swelling with loss of crista structure and loss of plasma membrane integrity. The necrotic cell death is also inhibited by inhibitors of ICE (interleukin-1 beta converting enzyme)(-like) proteases, the common mediators of apoptosis. These results indicate that Bcl-2/Bcl-xL and ICE(-like) proteases modulate both apoptotic and at least some forms of necrotic cell death, suggesting that both cell death pathways involve some common mediators.

Animals↗
PubMed1997

[Mitral valve remodeling using valvuloplasty, chordoplasty and ring annuloplasty].

Degenerative mitral valve disease is a major cause of mitral regurgitation and mitral valve repair has acquired greater importance as a surgical treatment of mitral regurgitation. Since 1991 we have used mitral valve repair to remodel the mitral valve leaflet, chordae tendineae and annulus. The final aim of our mitral valve remodeling technique is to correct the coaptation line of both leaflets. Forty-eight patients who underwent mitral valve repair were analyzed to evaluate the effect of the mitral valve reconstructive technique. We compared the left ventricular function and mitral valvular function by echocardiography and also the left ventricular pressure volume area, which reflects the oxygen consumption of the myocardium, before and after operation. The actuarial survival from all deaths, including one hospital death and one noncardiac death, was 95.8% at 60 months. Three patients have required reoperation because of recurrent regurgitation. Freedom from reoperation at 5 years was 93.8%. Left ventricular end-diastolic (122.3 +/- 45.8-->66.4 +/- 33.8 ml/ m2) and end-systolic volume indexes (39.6 +/- 19.5-->30.1 +/- 18.9 ml/m2) significantly decreased after mitral valve repair, and left ventricular volume overload was markedly reduced. Left ventricular ejection fraction and fractional shortening, which were apparently good before operation, were within the normal range after operation. Left ventricular inflow velocity and mitral pressure gradient were unchanged before and after repair. Mitral valve orifice area was 3.20 +/- 1.08 cm2 and did not show signs of mitral stenosis after repair. The reduction of left ventricular pressure volume area after repair was 53.6 +/- 12.4%, showing marked reduction of the oxygen consumption of the myocardium after successful mitral repair. Left ventricular and mitral valvular function is well preserved after mitral valve remodeling. Mitral valvular function after mitral repair exceeds that of the mitral valve replacement. Mitral valve remodeling procedures are very useful for patients with mitral regurgitation due to mitral valve prolapse.

Adolescent↗
PubMed1997

[T2*-contrast perfusion study--principles, theory and clinical utility in evaluating cerebral hemodynamics].

Contrast-enhanced dynamic study is easily feasible with a clinical MR system, for evaluating cerebral perfusion. A bolus of the paramagnetic contrast agents such as Gd-DTPA produces inhomogenity of the regional magnetic field between the capillaries and extravascular proton, and causes a decrease of signal intensity in the perfused region with T2*-weighted sequences. Echo planar imaging (EPI) is suitable for contrast-enhanced dynamic study, because it is markedly susceptible and provides high temporal-resolution. Tracer kinetic approaches are used for analysis of the dynamic data to acquire various perfusion parameters such as time delta R2* curve, rCBF, rCBV and MTT. T2*-weighted contrast-enhanced perfusion imaging is useful, especially, for detecting hyperacute ischemia and its therapeutic window, and depicting vasculature and ability of the brain tumors.

Blood Flow Velocity↗
PubMed1997

Detection of cytokine mRNA in unfractionated peripheral blood by reverse transcriptase polymerase chain reaction.

OBJECTIVE: To detect cytokine gene expression in unfractionated peripheral blood by reverse transcriptase-polymerase chain reaction (RT-PCR). DESIGN: Prospective study. SETTING: University hospital, Japan. SUBJECTS: 3 healthy volunteers and 3 severely infected patients. INTERVENTIONS: Peripheral blood was obtained and total RNA was extracted from 0.5 ml unfractionated whole blood with a 4 M guanidinium isothiocyanate mixture, 0.2 M sodium acetate, phenol, and chloroform. The mRNA was reverse transcripted, and interleukin-1 beta (IL-1beta) and tumour necrosis factor (TNF) cDNA were selectively amplified by synthetic primers with PCR. MAIN OUTCOME MEASURES: Establishment of cytokine gene expression in unfractionated peripheral blood. RESULTS: About 10 microg of total RNA was obtained from a 0.5 ml sample of blood. IL-1beta and TNF mRNA were not detected in blood from healthy volunteers, though they were detected in patients with severe infection. CONCLUSION: This method avoids artefactual gene activation and may be applicable to monitoring cytokine gene expression in various pathophysiological states.

Adult↗
PubMed1997

[Is TLFB method applicable to Japanese drinking population?: a methodological study on measurement of alcohol consumption].

In order to measure alcohol related problems, it is fundamental task to begin with to know the drinking quantity of the people. This study tries to explore the comparative, methodological possibilities of Timeline Follow Back (TLFB) as well as Self-Monitoring (SM) methods to measure drinking quantity, using the sample of Japanese and Sri Lankans. Especially TLFB method has not being so far utilized in Japan for this purpose. This pilot study has done in two stages. In the first stage, it has focused to get data on the correct drinking quantity up to two months period. After analyzing data of the first pilot survey, it was decided to reduce in the second-staged study the time frame to obtain data on drinking quantity only up to one month period. In the second-staged study, 37 Japanese and 36 Sri Lankans living in Japan has been selected. Results show that it is more appropriate SM method than TLFB method to investigate drinking quantity of the Japanese. Further it was evidenced that in order to employ TLFB method to investigate correct drinking quantity of the general Japanese population, it has to be further improved for overcoming ambiguity of respondents' memory on their alcohol consuming behavior. Moreover, it is understood that some characteristic drinking behaviors, influenced by Japanese drinking culture may be another barrier in getting correct drinking quantity data. However, the hypothesized notion of this cultural barriers was not supported. An alternative hypothesis "reflexive sensitivity to drinking", was implied.

Adult↗
PubMed1997

A case of Meckel's diverticulum complicated by stenosis of the colon.

Meckel's diverticulum is a common anomaly of the GI tract that is known to cause small intestinal obstruction. A 17-yr-old male who had no history of previous surgery was admitted with intermittent abdominal pain. A barium enema showed extraintestinal compression of the ascending colon, suggesting the existence of a congenital band. Laparoscopy revealed that the ascending colon was lifted up and compressed by the intestinal end of a Meckel's diverticulum with a fibrous band connecting to the umbilicus. The portion of the ileum including the Meckel's diverticulum was resected. This is the first case of stenosis of the colon caused by a Meckel's diverticulum.

Adolescent↗