Biomedical subjects

Y Chiba

Publications and source records attributed to Y Chiba.

At least 109 records · Page 6Linked to original sources

PubMed1998

[Removal of retained transvenous pacemaker electrodes under cardiopulmonary bypass].

A case of breakage and removal of a retained transvenous pacemaker electrode is described. A 22-year-old woman with complete A-V block underwent implantation of a transvenous pacemaker system on the left anterior chest wall in 1989. Three years later, a new generator was implanted on the right chest wall because of local infection of the pacemaker pockets. The old electrodes could not be removed and were left in place. Beginning in 1995, the patient complained of anterior chest pain. A chest roentgenogram revealed that one of the pacemaker electrodes had broken at the right costoclavicular ligament and a fragment was floating in the superior vena vava. The retained electrodes were removed under tot cardiopulmonary bypass. These electrodes had become firmly encased with fibrous tissue within the right ventricle and atrium, but they were easily removed under direct vision duting complete cardiac arrest. The postoperative course was uneventful and the patients had no further complaint.

Adult↗

PubMed1998

Effects of depletion of leukocytes and platelets on cardiac dysfunction after cardiopulmonary bypass.

BACKGROUND: This study examined the effects of the depletion of leukocytes and platelets from circulated blood on cardiac function after cardiopulmonary bypass in 37 patients who underwent coronary artery bypass grafting or aortic valve replacement. METHODS: Leukocytes and platelets were removed continuously using a blood cell separator, beginning immediately after the start of the operation and ending 1 hour after the release of the aortic cross-clamp in 19 patients (LPD group), but not in the remaining 18 patients (control group). Blood cell counts and levels of thromboxane B2, 6-keto-prostaglandin F1alpha, leukocyte elastase, complements C3a and C4a, thrombin-antithrombin III complex, and D-dimer were determined periodically during and after the operation. The cardiac index, the difference between the central and peripheral core temperatures, and the doses of catecholamines and vasodilators required to support the circulation in the early postoperative period also were assessed. RESULTS: Leukocyte and platelet counts and levels of leukocyte elastase, thromboxane B2, thromboxane2/6-ketoprostaglandin F1alpha, thrombin-antithrombin III complex, and D-dimer were significantly lower in the LPD group than in the control group before and after the release of the aortic cross-clamp and during the perioperative period. There were no significant differences in the levels of 6-keto-prostaglandin F1alpha or complements C3a and C4a between the two groups. The catecholamine dose was significantly lower in the LPD group than in the control group (1.1 +/- 2.5 versus 5.0 +/- 5.2 mg/kg, respectively). Fewer patients required the use of nitroprusside as a vasodilator in the LPD group than in the control group (1/19 versus 12/18, respectively). CONCLUSIONS: The depletion of leukocytes and platelets using a blood cell separator prevents the deterioration of cardiac function after cardiac operations using cardiopulmonary bypass.

6-Ketoprostaglandin F1 alpha↗

PubMed1998

Tumor angiogenesis as a prognostic marker in operable non-small cell lung cancer.

BACKGROUND: Recent evidence suggests that tumor angiogenesis is associated with patient outcome in a number of malignancies. However, little is known about the significance of tumor microvessel density as evaluated by an anti-CD34 antibody in patients with lung cancer. METHODS: Tumor tissues were obtained from 101 patients with operable non-small cell lung cancers. Immunohistochemical detection of tumor-associated microvessels was performed using anti-CD34 antibodies directed against endothelial markers. Average counts of the three most vascular areas on a X200 field were recorded. RESULTS: Staining for CD34 was easy to interpret because of specific and minimal background staining. The Kaplan-Meier method showed a statistically significant difference between the microvessel count and overall survival. The microvessel count was identified as the only significant and independent prognostic marker. In both univariate and multivariate analyses, the microvessel count was significantly related to the development of hematogenous metastasis but failed to associate with the development of nodal metastasis. CONCLUSIONS: Tumor vascularity is an independent prognostic factor and important for the development of hematogenous metastasis.

Adult↗

PubMed1998

Prolongation of total permissible circulatory arrest duration by deep hypothermic intermittent circulatory arrest.

OBJECTIVE: We determined whether the duration of permissible circulatory arrest could be prolonged by deep hypothermic intermittent circulatory arrest. METHODS: Twenty-five beagles were cooled on bypass to 18 degrees C to initiate deep hypothermia that was maintained for 3 hours. Five protocols were then studied: group 1, uninterrupted bypass during hypothermia; group 2, arrest for 40 minutes during hypothermia; group 3, arrest for 60 minutes during hypothermia; group 4, arrest for 80 minutes during hypothermia; and group 5, intermittent circulatory arrest, consisting of six cycles of 20 minutes of arrest followed by 10 minutes of systemic recirculation during hypothermia (total, 120 minutes of arrest). The oxyhemoglobin concentration in the brain was measured with near infrared spectrophotometry. RESULTS: In groups 2, 3, and 4, the oxyhemoglobin concentration in the brain decreased continuously after arrest, finally reaching a plateau after 24.9 +/- 1.2 minutes. This finding suggested that the available cerebral oxyhemoglobin was depleted. In contrast, the available cerebral oxyhemoglobin was not depleted during hypothermic intermittent arrest in group 5. The mitochondrial respiratory control index was significantly lower in group 4 than in the other groups (p < 0.05). However, there were no significant differences in the respiratory control index for groups 1, 2, 3, and 5. Moreover, the formation of brain edema was significantly lower in group 5 than in the other groups (p < 0.05). CONCLUSIONS: These results indicate that deep hypothermic intermittent arrest can increase the duration of total permissible circulatory arrest and will be a useful modality when prolonged arrest is anticipated.

Animals↗

PubMed1998

Enhanced colonic and rectal absorption of insulin using a multiple emulsion containing eicosapentaenoic acid and docosahexaenoic acid.

The aim of this study was to test the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on insulin absorption from rat intestinal loops in situ, using a water-in-oil-in-water (W/O/W) multiple emulsion. The enhancement effect of these long-chain polyunsaturated fatty acids was compared with that of free fatty acids having a C18 alkyl chain. The emulsion (insulin dose, 50 units/kg) was administered directly into the colonic and rectal loops. Both EPA and DHA strongly enhanced insulin absorption and induced hypoglycemia after colonic and rectal dosing. Comparing the pharmacological availability, the order of effectiveness with respect to the enhanced absorption of insulin was DHA >/= EPA > C18 unsaturated fatty acids >> C18 saturated fatty acid at both sites. DHA showed greater effects upon rectal dosing than upon colonic dosing. Histological studies revealed that the emulsion incorporating DHA did not induce gross morphological changes in the structure of the intestinal mucosa. Our results indicate that a W/O/W multiple emulsion incorporating DHA is a possible means of facilitating the intestinal absorption of insulin without inducing any serious damage to the epithelial cells.

Animals↗

PubMed1998

Deep hypothermic intermittent circulatory arrest--an adjunct technique for operations on aneurysms involving the aortic arch.

Aneurysms involving the aortic arch were repaired in 12 patients using a technique known as deep hypothermic intermittent circulatory arrest (DHICA). This technique consists of repeated cycles of 20 min of circulatory arrest and 10 min of cerebral and systemic reperfusion. Aneurysms were of the following types: 2 true atherosclerotic aneurysm, 8 aortic dissections, and 2 traumatic aneurysm. There were 2 operative deaths caused by coagulopathy as a result of hepatic failure and difficulty with left ventricular venting. The frequency of circulatory arrest ranged from 2 to 5 cycles, and total circulatory arrest ranged from 20 to 71 min (mean 43.6 min). The lowest tympanic temperature ranged from 17.7 to 19.2 degrees C. No permanent cerebral complications occurred in 10 patients. We believe that this adjunct technique offers excellent results in the surgical treatment of aneurysms involving the aortic arch.

Adult↗

PubMed1998

[Molecular mechanisms of the hyperresponsiveness of airway smooth muscle in bronchial asthma].

Nonspecific airway hyperresponsiveness (AHR) is a common feature of allergic bronchial asthmatics, but the underlying mechanisms of AHR have yet to be elucidated. The importance of AHR in the pathogenesis of asthma has been suggested by its relevance to the severity of this disease. There is thus a need to understand the underlying mechanisms of AHR for the sake of asthma therapy. In allergic asthmatics, airway smooth muscles (ASMs) obtained from in vivo hyperresponsive patients have in vitro hyperresponsiveness to cholinergic agonists. It is therefore possible that the mechanisms responsible for the AHR exist, at least in part, on the ASM site. Although ASM is known to contract in response to acetylcholine via muscarinic M3 receptors and this contractile response is augmented during AHR, no alteration in muscarinic receptor density in ASM has been demonstrated in various AHR models. It is thus likely that augmented intracellular signaling might be a possible reason for the AHR. In fact, recent investigations demonstrated increases in the levels of GTP binding protein, Ca2+ mobilization and inositol 1,4,5-trisphosphate generation and so on in hyperresponsive ASM.

Animals↗

PubMed1998

Legionnaires' disease diagnosed by bronchoalveolar lavage.

A 51-year-old woman who had been on steroid therapy for systemic lupus erythematosus (SLE) developed a high fever 3 days after visiting a hot spring resort. Chest X-ray films revealed an interstitial, pneumonia-like shadow in the left lung field, which increased rapidly with a worsening of her symptoms. She died of multiple organ failure one week after the onset of the pneumonia. Although the serum antibody titer was negative, Legionella pneumophila was recovered from her bronchoalveolar lavage (BAL) fluid. BAL seems to be a useful method to diagnose Legionnaires' disease.

Antibodies, Bacterial↗

PubMed1998

The utility of Hayashi's quantification theory type 2 for the rapid assessment of the epidemiological survey in the developing countries--in a case of the vaccine coverage survey in Yunnan Province, China.

It is difficult to conduct the epidemiological survey with accurate statistical theory in the developing countries due to the problems especially emerged in the developing countries such as no availability of the accurate population data, limitation of the time for survey, geographical obstacle and financial problems. In the consideration of the health needs in those countries, results of the epidemiological survey should be reflected in the present health projects as rapidly as possible. The authors conducted the survey for the immunization coverage of oral poliomyelitis vaccine(OPV) in China by the questionnaire and interview. The data was analyzed by using the Hayashi's quantification theory type 2 and made clear about the relationship between the health behaviors for immunization among residents and several factors. It is considered that this theorem can provide the obvious numeral materials about multi-factorial cause effect relationship for the decision making and is useful for the rapid assessment or initial survey in the developing countries.

Chi-Square Distribution↗

PubMed1998

Characterization of muscarinic receptors in rat bronchial smooth muscle in vitro.

This study was undertaken to assess the important muscarinic receptor subtype in acetylcholine (ACh)-induced rat bronchial smooth muscle contraction. Ring smooth muscle strips of the left main bronchus were used. Isometrical contraction was measured in response to ACh in cumulative concentrations (10(-7)-10(-3) M) with and without preincubations with the muscarinic receptor antagonists, pirenzepine (an M1 antagonist), methoctramine (an M2 antagonist), and 4-diphenylacetoxy N-methylpiperidine (4-DAMP; an M1/M3 antagonist). Preincubation with these antagonists resulted in concentration-dependent rightward shifts of the concentration-response curves to ACh. pA2 values (means+/-sem) were 8.80+/-0.10 for 4-DAMP, 7.03+/-0.06 for pirenzepine and 5.91+/-0.36 for methoctramine, indicating that the most important muscarinic receptor mediating ACh-induced contraction of rat bronchial smooth muscle is of the M3 type.

Acetylcholine↗

PubMed1998

[Enhanced ultrasonography in the diagnosis of renal tumors].

At present, we have two methods of enhanced ultrasonography in the diagnosis of renal tumors. One is the ultrasound B-mode imaging enhancement under renal arterial infusion of carbon dioxide microbubbles, a contrast agent for US, and the other is the color Doppler signal enhancement under intra-venous injection of galactose-based echo contrast agent, SH/TA-508. Renal cell carcinoma were imaged from the very beginning of the injection of CO2 through the time complete washout from the kidney. On the other, intra-tumor color Doppler signals were remakedly emphasized after SH/TA-508 administration. Enhanced ultrasonography is useful in the detection of small renal cell carcinoma and differential diagnosis of renal masses.

Aged↗

PubMed1998

[A new operative technique of posttraumatic syringomyelia: thecoperitoneal shunt].

The authors report a successful case of operative treatment for a patient with a traumatic syringomyelia. A 33-year-old male presented with arm pain and right sided sensory loss due to posttraumatic syringomyelia. Magnetic resonance image showed syringomyelia from the upper cervical cord to the lower thoracic cord. Based on the hypothesis of Ball and Dayan, and Williams, a thecoperitoneal shunt operation was performed. The proximal shunt catheter was placed in the subarachnoid space rostral to the injury level and the distal shunt catheter was introduced percutaneously into the peritoneum. Postoperative radiological studies showed improvement and progressive clinical deterioration stopped. The advantages of this surgery are that it is less invasive to the spinal cord, and that there is a lower shunt malfunction rate because of the use of a D-L catheter which develops less shunt obstruction. Furthermore, we were able to evaluate shunt flow from the valve. In spite of multicystic syrinx, we were easily able to determine the placement of the shunt catheter for this operation. For these reasons, the thecoperitoneal shunt can be placed before further expansion of the syrinx. We think that this method is safer for patients with incomplete cord injury than S-P shunt or S-S shunt.

Adult↗

PubMed1998

[A case of type A dissecting aneurysm who are complicated by paraplegia at the 4th day after emergent operation].

The 62-year-old man was admitted to our hospital with chief complaints of chest and back pain. He was diagnosed type A acute dissecting aneurysm by chest computed tomography, and underwent urgent operation, replacement of the ascending aorta and resuspension of the aortic valve. He was recovered without any neurologic complications. However, he was complicated by paraplegia at the 4th postoperative day. We suspect that is due to early thrombotic occlusion of the false lumen where the anterior spinal arteries branch by the operation.

Aortic Dissection↗

PubMed1998

Abdominal aortic aneurysmectomy in the octogenarian.

The risks, results, and postoperative quality of life were evaluated in 11 patients aged 80 years or older who underwent resection of an abdominal aortic aneurysm (AAA). The operative mortality was 9% (1/11). Three patients underwent urgent operation, 1 for impending rupture, 1 for contained rupture, and 1 for rupture into the sigmoid colon. Preoperative risk factors such as hypertension, electrocardiographic abnormalities, and respiratory dysfunction were found in about half of the patients. Neither operative mortality nor long-term survival were influenced by the preoperative risk factors. The quality of life enjoyed by these patients was not adversely affected by AAA resection. Surgical treatment of AAA should be undertaken in selected octogenarians to prevent rupture. Physiologic status rather than chronologic age should determine which patients undergo aneurysm resection.

Aged↗

PubMed1997

A novel allosteric potentiator of AMPA receptors: 4--2-(phenylsulfonylamino)ethylthio--2,6-difluoro-phenoxyaceta mide.

We report that a novel sulfonylamino compound, 4-[2-(phenylsulfonylamino)ethylthio]-2,6-difluoro-phenoxyacetam ide (PEPA), selectively potentiates glutamate receptors of the AMPA subtype. PEPA (1-200 microM) dose dependently potentiated glutamate-evoked currents in Xenopus oocytes expressing AMPA (GluRA-GluRD), but not kainate (GluR6 and GluR6+KA2) or NMDA (zeta1 + epsilon1-epsilon4), receptor subunits. PEPA was effective at micromolar concentrations and, in contrast to the action of cyclothiazide, preferentially modulated AMPA receptor flop isoforms. At 200 microM, PEPA potentiated glutamate responses by 50-fold in oocytes expressing GluRCflop (EC50 approximately 50 microM) versus only threefold for GluRCflip; a similar preference for flop isoforms was observed for other AMPA receptor subunits. Dose-response analysis for GluRCflop revealed that 100 microM PEPA produced a sevenfold increase in AMPA receptor affinity for glutamate. PEPA produced considerably weaker potentiation of kainate-evoked than glutamate-evoked currents, suggesting modulation of the process of receptor desensitization. In human embryonic kidney 293 cells transfected with AMPA receptor subunits, PEPA either abolished or markedly slowed the rate of onset of desensitization and potentiated steady-state equilibrium currents evoked by glutamate with subunit (GluRC >/= GluRD > GluRA) and splice-variant (flop > flip) selectivity similar to that observed in oocytes. Our results show that PEPA is a novel, flop-preferring allosteric modulator of AMPA receptor desensitization at least 100 times more potent than aniracetam.

Animals↗

PubMed1997

Molecular analysis of eight biochemically unique glucose-6-phosphate dehydrogenase variants found in Japan.

We analyzed the molecular mutations of eight known Japanese glucose-6-phosphate dehydrogenase (G6PD) variants with unique biochemical properties. Three of them were caused by novel missense mutations: G6PD Musashino by 185 C-->T, G6PD Asahikawa by 695 G-->A, and G6PD Kamiube by 1387 C-->T. Predicted amino acid substitutions causing asymptomatic variants G6PD Musashino (62 Pro-->Phe) and G6PD Kamiube (463 Arg-->Cys) were located in regions near the amino or carboxyl end of the polypeptide chain, whereas an amino acid change 232 Cys-->Tyr causing a class 1 variant G6PD Asahikawa was located in the region where amino acid alterations in some class 1 variants were clustered. The other five variants had known missense mutations, namely, G6PD Fukushima, 1246 G-->A, G6PD Morioka, 1339 G-->A, and G6PD Iwate, G6PD Niigata and G6PD Yamaguchi, 1160 G-->A, which cause variants, G6PD Tokyo, G6PD Santiago de Cuba, and G6PD Beverly Hills, respectively.

Anemia, Hemolytic, Congenital Nonspherocytic↗

PubMed1997

Effect of spinal cord preconditioning on paraplegia during cross-clamping of the thoracic aorta.

BACKGROUND: Paraplegia is a devastating complication of operations for thoracic or thoracoabdominal aneurysms. Preconditioning the brain with sublethal ischemia induces resistance to subsequent ordinarily lethal ischemia (ischemic tolerance). We investigated whether ischemic tolerance could be induced by preconditioning canine spinal cord. The role of heat-shock proteins (HSP) in this process was investigated. METHODS: In experiment 1, the preconditioning group (n = 6) had aortic cross-clamping for 20 minutes, whereas controls (n = 6) had no cross-clamping. After 48 hours the aorta was cross-clamped for 60 minutes in both groups. Neurologic examination was performed 24 hours later and the spinal cord was studied for immunohistochemically. In experiment 2, either 48 hours after 20 minutes of clamping or after sham operation (n = 4), HSP were investigated immunohistochemically. RESULTS: In experiment 1, 3 of 6 controls became paraplegic but none of the 6 preconditioning group dogs became paraplegic. The HSP appeared on sections from all 6 PC dogs and 3 control dogs that did not exhibit paraplegia. In experiment 2, HSP were present in clamped animals but could not be detected after sham operation. CONCLUSIONS: Ischemic tolerance was induced by preconditioning the canine spinal cord, in which HSP are believed to be involved.

Animals↗

PubMed1997

The RY sequence is necessary but not sufficient for the transcription activation of a winged bean chymotrypsin inhibitor gene in developing seeds.

A winged bean Kunitz-type chymotrypsin inhibitor (WCI) is expressed in seeds and tuberous roots. In seeds, the expression of WCI is restricted to the period between the mid- and late-maturation stage. To understand the mechanisms that regulate the expression of WCI genes, we analyzed the promoter activity of the upstream region of the WCI-3b gene, which encodes a major WCI protein, in transgenic tobacco plants. By using a series of constructs with 5' deletions in the upstream sequences, the region between -882 and -623, relative to the transcription start site, was shown to contain multiple sequences which are responsible for high level expression in mid-maturation stage seeds. However, when this region was fused to the cauliflower mosaic virus 35S core promoter in both orientations, the chimeric promoters showed only a weak transcription activity in transgenic tobacco plants. Further analyses using internal deletion constructs revealed that the region between -882 and -174 is required for the transcription activation. Disruption of the RY sequence at -517, which is conserved in many seed protein genes, resulted in a drastic reduction of the transcription activity in seeds. These results suggest that sequences necessary for high level induction of the WCI-3b gene transcription in developing seeds are dispersed in the region between -882 and -174, and that the RY sequence is one of these sequences.

Chymotrypsin↗