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Biomedical subjects

H Tsuchida

Publications and source records attributed to H Tsuchida.

At least 55 records · Page 3Linked to original sources
PubMed1998

Role of intracellular Ca2+ stores in the inhibitory effect of halothane on airway smooth muscle contraction.

BACKGROUND: Halothane directly inhibits contraction of airway smooth muscle, mainly by decreasing the intracellular concentration of free Ca2+ ([Ca2+]i). The role of intracellular Ca2+ stores, sarcoplasmic reticulum, is still unclear. We investigated the role of sarcoplasmic reticulum in the inhibitory effect of halothane on contraction of airway smooth muscle by measuring [Ca2+]i and intracellular concentration of inositol 1,4,5-triphosphate ([IP3]i), a second messenger for release of Ca2+ from sarcoplasmic reticulum. METHODS: [Ca2+]i was monitored by measuring the 500-nm light emission ratio (F340/F380) of a Ca2+ indicator fura-2 with isometric tension of canine tracheal smooth muscle strip. During Ca2+-free conditions, carbachol (10(-5) M) was introduced with pretreatment of halothane (0-3%). During Ca2+-free conditions, 20 mM caffeine, a Ca2+-induced Ca2+ release channel opener, was introduced with or without halothane. We measured [IP3]i during exposure to carbachol and halothane by radioimmunoassay technique. RESULTS: Pretreatment with halothane significantly diminished carbachol-induced increases in [Ca2+]i by 77% and muscle tension by 83% in a dose-dependent manner. Simultaneous administration of halothane significantly enhanced caffeine-induced transient increases in [Ca2+]i and muscle tension in a dose-dependent manner, by 97% and 69%, respectively. Pretreatment with halothane abolished these responses. Rapid increase in [IP3]i produced by carbachol was significantly inhibited by 32% by halothane in a dose-dependent manner. CONCLUSIONS: Halothane, during Ca2+-free conditions, inhibits transient contraction of airway smooth muscle induced by muscarinic receptor stimulation, mainly by attenuating the increase in [Ca2+]i. Depletion of Ca2+ from sarcoplasmic reticulum via Ca2+-induced Ca2+ release channels also may contribute to the attenuation of the increase in [Ca2+]i by halothane.

Anesthetics, Inhalation↗
PubMed1998

Effects of halothane and isoflurane on beta-adrenoceptor-mediated responses in the vascular smooth muscle of rat aorta.

BACKGROUND: Although previous studies have proposed that anesthetics may influence signal transduction systems, their effects on the beta-adrenoceptor-mediated system have not been fully characterized in vascular smooth muscle. The aim of this study was to determine how halothane and isoflurane affect beta-adrenoceptor-mediated vasodilation in rat aorta and what mechanisms were involved. METHODS: Isometric tension and the intracellular calcium ion concentration ([Ca2+]i) were measured concomitantly in rat aortic strips from which the endothelium was removed. Strips precontracted with norepinephrine were dilated with the beta-adrenoceptor agonist, isoproterenol; the adenylyl cyclase activator, forskolin; or the membrane-permeable dibutyryl cyclic adenosine monophosphate (cAMP) with or without halothane or isoflurane. The effects of the anesthetics on each vasodilator were compared with the control responses. Beta-adrenoceptor binding characteristics and affinity for agonists were determined with [125I]-iodocyanopindolol with and without halothane or isoflurane. Furthermore, concentrations of cAMP induced by either isoproterenol or forskolin were measured with or without the anesthetics using an enzyme immunoassay procedure. RESULTS: Halothane and isoflurane attenuated vasodilation and [Ca2+]i decreases induced by isoproterenol, whereas both anesthetics only slightly affected vasodilation and [Ca2+]i decreases induced by forskolin and dibutyryl cAMP. Halothane and isoflurane had no effect on beta-adrenoceptor binding characteristics and affinity for agonists. Three percent halothane or 4% isoflurane significantly reduced cAMP levels induced by isoproterenol but not by forskolin. CONCLUSIONS: Halothane and isoflurane, at clinically relevant concentrations, can interfere with beta-adrenoceptor-mediated responses in the rat aorta at the steps after the agonist-receptor binding but before the adenylyl cyclase activation.

Adrenergic beta-Agonists↗
PubMed1998

Polysaccharides from Agaricus blazei stimulate lymphocyte T-cell subsets in mice.

Subset analysis of splenic lymphocytes using flow cytometry showed that the percentages of Thy1.2-(pan T-cells), L3T4-(CD4, helper T-cells), and Lyt2-(CD8, cytotoxic T-cells) positive cell populations were significantly increased in mice orally administered a hot water-soluble fraction from Agaricus blazei as compared with mice treated only with saline. 13C-NMR data indicates that the main component in the active polysaccharide is the complex of alpha-1,6- and alpha-1,4-glucan, which had already been shown to have anti-tumor activity against Sarcoma 180. It seems that the polysaccharide from Agaricus blazei may be an effective prophylactic, protecting humans against cancer by stimulating lymphocytes such as cytotoxic T-cells.

Adjuvants, Immunologic↗
PubMed1998

[Changes in circulation and end-tidal sevoflurane concentration during infusion of sevoflurane into vaporizer].

We observed the changes in circulation and endtidal sevoflurane concentration during the infusion of the anesthetic into a vaporizer, and investigated some techniques to prevent these changes during general anesthesia. The patients were randomly divided into three groups: conventional, high concentration (conc.) and low flow groups. Inspiratory concentration of sevoflurane was kept at 1.0% and the duration of the pause in sevoflurane supply was 90 sec. The high conc. group was exposed to 2.0% sevoflurane for 60 sec. just before and after the pause, and the low flow group had a low fresh gas flow (0.5 l.min-1) during the pause. An increase in blood pressure and a tendency towards tachycardia were observed in the conventional group, and the circulation was kept constant best in the low flow group. The lowest concentrations of sevoflurane during the pause were 0.46, 0.46 and 0.93% in the conventional, high conc., and low flow groups, respectively, and exposure to high concentration of the anesthetic could not prevent the decrease. These results indicate that low flow anesthesia is a useful technique to prevent undesirable changes in circulation and anesthetic concentration.

Anesthesia, Epidural↗
PubMed1998

Immunohistochemical study of human advanced glycation end-products (AGE) and growth factors in cardiac tissues of patients on maintenance dialysis and with kidney transplantation.

Cardiovascular disease is one of the most common complications of dialysis and renal transplant patients, and high levels of AGE are present in end-stage renal failure. To address the potential involvement of AGE and growth factors in the pathophysiology of cardiovascular complications, we performed immunostaining using cardiac tissues from autopsy cases of patients on maintenance dialysis (10 cases), long-term surviving renal transplant patients with functioning grafts (8 cases), control subjects with normal renal function (7 cases) and non diabetic subjects with mild renal insufficiency (8 cases). We used two types of AGE-antibodies, 6D12 [monoclonal anti-AGE antibody, recognizing N epsilon-(carboxymethyl) lysine(CML)-modified AGE] (oxidative AGE) and non-CML-PA [polyclonal, not recognizing CML], and antibodies against PDGFs, PDGF receptors and TGF beta. Positive 6D12 staining was observed in the coronary arterial walls and in macrophages. The accumulation of 6D12-reactive AGE in the coronary arterial walls of maintenance dialysis patients was significantly greater than that of control subjects (p < 0.05). Renal transplantation significantly reduced this accumulation (p < 0.05). On the other hand non-CML-PA mainly detected AGE in intracardiac arterioles and neural tissues. There was little difference in the accumulation of non-CML-AGE among the four groups. PDGFs and PDGF receptors were mainly detected in vascular endothelial cells and infiltrating cells of cardiac tissues of renal transplant patients, but not of maintenance dialysis patients. TGF beta was not detected in cardiovascular tissue of transplant patients. Our results indicated that the accumulation of oxidative AGE (CML-AGE) in the cardiac vascular tissue is one of the factors for cardiovascular complications of maintenance dialysis patients, and also that renal transplantation has a reducing effect on CML-AGE accumulation. PDGFs may be involved in the cardiovascular complications after renal transplantation.

Adult↗
PubMed1998

[The efficacy of low-dose propofol for intrathecal morphine-induced pruritus].

We investigated the efficacy and untoward effects of low doses of propofol for intrathecal morphine-induced pruritus. Twenty gynecological and obstetric surgical patients received spinal anesthesia with 0.5% tetracaine and phenylephrine, as well as 0.2 mg morphine. Seven of them (35%) complained pruritus graded according to the treatment necessary in the postoperative period. Propofol, 10 mg or 20 mg, successfully alleviated the pruritus in 6 patients out of 7. Further treatment was not necessary in 5 of them. One patient was resistant to treatments by 20 mg of propofol and 0.1 mg of naloxone. Three patients transiently fell in sleep even after administering 10 mg of propofol. The authors conclude that low dose propofol is effective in treating intrathecal morphine-induced pruritus, although it may transiently causes hypnosis in postoperative patients.

Adult↗
PubMed1998

[Two cases of clipping surgery of cerebral aneurysm under profound hypothermia with closed-chest extracorporeal circulation].

A 68-year-old female and a 47-year-old male patients underwent clipping surgery for giant basilar arterial and thrombotic internal carotid arterial aneurysms respectively with closed-chest extracorporeal circulation (femoro-femoral bypass). Profound hypothermia and continuous infusion of thiamylal were used to prevent brain damage. Blood outflow via the femoral vein was sufficient to induce profound hypothermia down to 20 degrees C. Hemodynamics were controllable without catecholamines during closed-chest extracorporeal circulation. Preoperative symptoms significantly improved and no neurological complication was observed in either case postoperatively. Right femoral phlebothrombosis was, however, observed in one case. In conclusion, profound hypothermia with closed-chest extracorporeal circulation is a safe technique to reduce the complications induced by open-chest technique, but special attention should be given to postoperative phlebothrombosis.

Aged↗
PubMed1998

[Preventive effect of fluid warmer system on hypothermia induced by rapid intravenous infusion].

The changes in body temperature induced by rapid intravenous infusion of lactated Ringer solution and the effect of a fluid warmer system (HOT LINE, Level 1 Technologies, Inc., Rockland, MD) were investigated in 35 patients undergoing cardiovascular surgery. The patients were divided into 5 groups by categories of the fluid temperature (-19 or -38 degrees C), infusion route (radial or right subclavian vein), and infusion rate of lactated Ringer solution (1000 or 250 ml for 30 min). Pulmonary arterial, esophageal, bladder, and forehead deep temperatures, which reflect core temperature, were significantly decreased by the rapid infusion of unwarmed solution (0.8-1.0 degree C, P < 0.05). In contrast, these temperatures were maintained in the warmed solution groups as well as in the group of slow infusion rate. With regard to the infusion route, there was no significant difference in the temperature between the radial vein and subclavian vein groups. Plantar deep temperature showed no significant change during this study. In conclusion, infusion of warmed solution using HOT LINE could prevent hypothermia induced by rapid intravenous infusion, and this effect is not greatly influenced by route of venous infusion.

Adult↗
PubMed1998

[Pain-free injection of propofol].

Pain on injection is one of the well-known side effects of propofol. Previous studies have shown several methods to alleviate this discomfort. We employed all these methods together to clarity whether pain-free injection of propofol was possible. Sixty adult patients premedicated with midazolam were studied. Control group patients (n = 20) received an induction dose of propofol via a vein on the dorsum of the hand at a slow injection speed with carrier i.v. fluid. Study group patients (n = 40) received i.v. fentanyl 0.1 mg, followed by bolus injection of cold propofol premixed with lidocaine (final concentration of lidocaine was 0.2%) in a forearm vein without carrier i.v. fluid. Eighteen patients (90%) in the control group experienced injection pain. In the study group, however, no patients complained of pain or discomfort. In conclusion, pain-free injection of propofol was possible when prior-administration of fentanyl, premixing of lidocaine, cooling to 4 degrees C, and rapid injection via a forearm vein without carrier i.v. fluid was the adopted precedure.

Adult↗
PubMed1998

[Circulatory changes at the time of anesthetic induction and endotracheal intubation--comparison of thiamylal induction group and propofol induction group].

We examined the circulatory changes after intravenous thiamylal with additional injection of thiamylal 1 minute before intubation and after propofol at the time of anesthetic induction and endotracheal intubation. Sixty ASA I or II patients were studied after the institutional and informed consents. We compared the following three groups. Group I (n = 20): Anesthesia was induced with thiamylal 5 mg.kg-1 and intubation with the aid of vecuronium 0.1 mg.kg-1. Group II (n = 20): Anesthesia was induced with thiamylal 3 mg.kg-1 and vecuronium 0.1 mg.kg-1. One minute before the intubation, the patients received additional thiamylal 4 mg.kg-1. Group III (n = 20): Anesthesia was induced with propofol 2.5 mg.kg-1 and intubation was performed with the aid of vecuronium 0.1 mg.kg-1. We examined the systolic, diastolic and mean blood pressures, heart rate, and rate pressure product (RPP) in the three groups. The examinations were performed before and after induction, soon after intubation, and every one minute after intubation for 5 minutes. After the endotracheal intubation, the systolic blood pressure and heart rate increased in Group I. But the systolic and diastolic pressures were significantly more stable in Group II and Group III. The change of the RPP was slight and most stable in Group II compared with the other two groups. We conclude that additional injection of thiamylal 4 mg.kg-1 following induction of anesthesia with thyamylal 3 mg.kg-1 1 minute before endotracheal intubation is an effective method for minimizing the increase in blood pressure and circulatory changes at the time of rapid induction of anesthesia and endotracheal intubation.

Adjuvants, Anesthesia↗
PubMed1997

Healing mechanisms of high-porosity PTFE grafts: significance of transmural structure.

A high-porosity structure facilitates endothelialization of polytetrafluoroethylene (PTFE) grafts. The mechanism for endothelial coverage, however, has been controversial. This study was designed to clarify the healing mechanisms of high-porosity PTFE grafts. Four types of PTFE grafts (n = 48) were studied after implantation in both carotid and femoral arteries of dogs. The grafts were standard (ST) PTFE [mean internodal distance (MID): 30 microm]; high-porosity (HP) PTFE (MID 90 microm), composite porosity (CP) PTFE (MID: inner layer, 90 microm; outer layer, 30 microm); and polyurethane-coated high-porosity (PCHP) grafts which had the outer surface covered with nonporous polyurethane. Patency rates at 18 weeks were ST 6/12, HP 8/12, CP 6/12, and PCHP 3/12 (P = 0.290). The rates of endothelialization (%, mean +/- SD) in the patent grafts were ST 25 +/- 7, HP 75 +/- 20,* CP 57 +/- 15,* and PCHP 17 +/- 5 (*P < 0.05 vs ST or PCHP). Rich transmural tissue incorporation was observed in the HP grafts. In contrast to the HP grafts, PCHP grafts had no outer tissue ingrowth, inner tissue incorporation was scant, and anastomotic intimal hyperplasia was pronounced. The edges of pannus ingrowth in the PCHP grafts were irregular, such that the anchoring of pannus was weak and easily detachable. Well-developed endothelial cells were observed in the HP and CP grafts, but nonendothelialized areas always occurred in the center of the grafts. Capillary openings were noted in the HP grafts; however, their number was small (0-8/graft) on electron microscopy and did not account for the degree of endothelialization observed. We conclude that the principal mechanism for endothelialization of PTFE grafts is ingrowth from the anastomoses rather than transmural endothelialization, even in high-porosity grafts. Transmural fibrocapillary incorporation of PTFE vascular grafts provides a key supporting structure essential to the progression and attachment of endothelial ingrowth from the anastomoses.

Animals↗
PubMed1997

Onset of vecuronium neuromuscular blockade at the hand with an arterio-venous shunt.

PURPOSE: To evaluate the onset of vecuronium neuromuscular blockade in the hand with an arterio-venous shunt for haemodialysis. METHODS: In 15 adult patients receiving haemodialysis for renal failure the onset of vecuronium-induced neuromuscular blockade after 0.08 mg-kg-1 vecuronium i.v. was measured. Using train-of-four mechanomyographic monitoring, the force of contraction of the adductor pollicis of both hands with and without arterio-venous shunt was measured simultaneously. RESULTS: The times from the injection to the first depression of twitch response (latent onset) and 95% twitch depression (onset) in the hand with and without arterio-venous shunt were 114.7 +/- 33.4 and 218.7 +/- 59.9 and 117.3 +/- 34.3 and 208.7 +/- 60.9 sec respectively. No difference in the onset of vecuronium neuromuscular blockade in the hand an arterio-venous shunt was demonstrated. CONCLUSION: The presence of an arteriovenous fistula does not modify the onset on neuromuscular blockade. Either arm can be used to monitor onset of neuromuscular blockade in chronic renal failure patients with an arterio-venous shunt in the hand for haemodialysis.

Adult↗
PubMed1997

Pharmacokinetic study of aniracetam in elderly patients with cerebrovascular disease.

The clinical pharmacokinetics of the cognitive enhancer, aniracetam (200 mg), was studied in elderly patients with cerebrovascular disease (CVD) and compared with those of young healthy volunteers. Six female hospitalized patients (mean age 84.5 years) were used in this study. The serum level of anisic acid and p-methoxyhippuric acid, major metabolites of aniracetam, reached a peak at 2 h after oral administration, and returned to basal level by 6 h. Mean creatinine clearance was 20-30 ml/min. The t1/2 of metabolites was increased by 4- to 7-fold in the elderly patients compared with young volunteers. This study showed that tmax, t1/2, and AUC were enlarged in the elderly; however, no clinical side effects were observed.

Adult↗
PubMed1997

Blockade of ATP-sensitive K+ channel abolishes the anti-ischemic effects of isoflurane in dog hearts.

BACKGROUND: Although isoflurane is reported to have a protective effect against ischemic damage on the myocardium, the mechanisms of this effect are not clear. Activation of adenosine triphosphate sensitive potassium (KATP) channels is indicated to protect myocardium during ischemia. Thus, it was hypothesized that if isoflurane could activate KATP channels, blockade of KATP channels would decrease its cardioprotective effect. METHODS: Mongrel dogs, anesthetized with morphine, urethane, and chloralose, were subjected to 15 min of left anterior descending coronary artery occlusion followed by 60 min reperfusion. The dogs were divided into three groups: the control group (n = 8), ISO group (n = 8) and ISOGC group (n = 8). In the ISO and ISOGC groups, 1 MAC of isoflurane was administrated during ischemia and reperfusion. In the ISOGC group, 0.3 mg/kg of glibenclamide, the KATP channel blocker, was given 45 min before ischemia. Full-thickness samples of myocardium were obtained and the concentrations of adenosine monophosphate, adenosine diphosphate, adenosine triphosphate (ATP), creatine phosphate and lactate in the endocardial portion of the myocardium were measured. RESULTS: The ischemia-reperfusion caused a 25.4% and 27.6% reduction of myocardial ATP in the control and ISOGC groups, respectively. In contrast, the ISO group showed only 11.0% reduction of ATP, which was significantly lower compared to the other groups (P < 0.01). CONCLUSIONS: Our results shows that blockade of the KATP channel abolishes cardioprotective effects of isoflurane in myocardial ischemia-reperfusion. The KATP channel may play a role in the ATP-sparing effect of isoflurane.

Adenosine Triphosphate↗
PubMed1997

[Clinical and diagnostic characteristics of Legionella pneumonia].

We have characterized clinical and diagnostic features in 18 cases of Legionella pneumonia. Age average of patients was 62.0 years old (male:female = 14:4) and underlying diseases were observed in 12 patients. Legionella pneumonia were diagnosed in 3, 5, 8 and 9 cases by culture, serum antibody measurement, urinary antigen detection and PCR, respectively. Sixteen cases were caused by L. pneumophila, while the other 2 cases were L. bozemanii pneumonia and L. pneumophila or L. dumoffii pneumonia. Chest X-rays of those patients showed multiple pneumonia shadows in 14 cases, alveolar shadows in 10 cases, pleural effusion in 5 cases. Blood-gas analysis on admission indicated hypoxemia in all cases with abnormal A-a DO2. Laboratory findings showed abnormal data in WBC, CRP, LDH, CPK and liver function tests (ex. GOT, GPT) in most cases. Serum antibody testing showed positive by 5 weeks after onset of pneumonia, but 10 cases of Legionella pneumonia diagnosed by other techniques were judged to be negative. In urinary antigen detection test, 6 and 2 cases showed positive 1 and 4 weeks after onset of pneumonia, respectively. Macrolide antibiotics were administered in all cases during the episode, but delay of macrolide administration was observed in 3 of 4 cases of dead outcome. Serum antibody measurement, urinary antigen detection and PCR, in addition to culture to bacteria, may be required for exact diagnosis of Legionella infection.

Adult↗
PubMed1997

[Type III procollagen N-peptide and hyaluronate in serum and dialysate of CAPD patients].

Long-term CAPD may develop peritoneal fibrosis, which is thought to be related to permanent loss of ultrafiltration capacity and sclerosing peritonitis. In CAPD patients, we examined the serum (P-) and effluent (D-) levels of type III procollagen N-peptide (P III P) and hyaluronate (HA), which are expected to change concomitantly with a local increase in submesothelial extracellular matrix of the peritoneum. We selected 40 CAPD patients (age: 46.3 +/- 11.3 years, time on CAPD: 33.6 +/- 26.2 months), who were not suffering from chronic liver disease, any inflammatory disease, nor peritonitis during the previous month. P-P III P, P-HA, D-P III P, and D-HA were measured by PET (values after 4-hour dwelling). D/P ratios (P III P 0.330 +/- 0.137, HA 5.68 +/- 6.44) suggested that their source was from the peritoneum. Although neither P-P III P nor log P-HA value had a significant correlation with age nor time on CAPD, both had significantly positive correlations (p = 0.0009, 0.0005, respectively) with time on total dialysis (including hemodialysis). D-P III P did not have a significant correlation with age nor time on total dialysis but had a significantly positive correlation (p = 0.0098) with D/P-creatinine. Although log D-HA had significantly positive correlations with time on CAPD and time on total dialysis (p = 0.0007, 0.0051, respectively), time on CAPD was first entered (F = 16.5) and time on total dialysis was removed (F to enter: 4) by stepwise regression analysis. In conclusion, a local increase in extracellular matrix of the peritoneum in CAPD patients, indicated by increases in P III P and HA in the effluent, may be related to higher peritoneal permeability and a longer duration of PD.

Adult↗
PubMed1997

[Stent graft treatment for two cases of DeBakey IIIb dissecting aortic aneurysm].

Two patients with DeBakey IIIb dissecting aortic aneurysms were treated with transluminally placed endovascular stent grafts. Surgery was required for both patients because the false lumens were not thrombosed for several months. Stent graft devices composed of several units of self-expandable Z stents covered with ultra-thin woven Dacron were inserted through 18 Fr sheathes via femoral arteries. The stent grafts were deployed successfully and blood flow into the false lumens was reduced immediately and finally thrombosed without blood leakage from the entries. The endoluminal stent graft treatment is minimally invasive operation in comparison with former surgical operations, and is useful for aortic aneurysms especially in high risk patients. However, improvement of the stent graft devices, including the delivery systems such as the dilator, sheath and pushing rod, which are incomplete, and developing better devices, is required to reduce delivery failure and to make the stent graft treatment more reliable.

Aged↗