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Biomedical subjects

T Miyazaki

Publications and source records attributed to T Miyazaki.

At least 181 records · Page 10Linked to original sources
PubMed1999

Lambda5 is required for rearrangement of the Ig kappa light chain gene in pro-B cell lines.

Lambda5 associates with V(pre-B) to form the surrogate light (L) chain. The phenotype of lambda5 knockout mice showed severe impairment of B cell development from pro-B to immature B cell stages. To investigate the function of the surrogate L chain at this stage, we restored expression of lambda5 to lambda5-deficient pro-B cell lines which were established from bone marrow cells of lambda5 knockout mice in the presence of IL-7 and a stromal cell line. Some of these lines are severely impaired in B cell development from pro-B to immature B cell stages as is seen in vivo in lambda5 knockout mice. Restoration of lambda5 protein by retroviral-mediated gene transfer into established lambda5-deficient pro-B cell lines induced rearrangement of the Ig kappa L chain genes after removal of IL-7 from the culture. Immunoprecipitation revealed that the restored lambda5 in the cell line is coupled with V(pre-B) to form the surrogate L chain. The results demonstrate that formation of a complete surrogate L chain, consisting of both lambda5 and V(pre-B), stimulates efficient rearrangement of the kappa L chain genes.

Animals↗
PubMed1999

A clinical study on the magnetic stimulation of the facial nerve.

OBJECTIVES: A clinical study on the usefulness of magnetic stimulation of the facial nerve, with special attention paid to the selection of the coil shape and stimulation procedures. STUDY DESIGN: The subjects consisted of 55 patients with Bell's palsy, 1 patient with a cerebellopontine angle (CPA) tumor, 1 patient with multiple sclerosis (MS), and 30 normal subjects. Three types of coils were used in this study; a 90-mm large single coil, a 40-mm small single coil, and a 20-mm small double coil. METHODS: The compound muscle action potentials (CMAPs) and long latency response were evoked by transcranial magnetic stimulation (TMS) with a 90-mm large single coil. The 40-mm small single coil was used to test blink reflex by aiming it at the supraorbital nerve as the target site. The subcutaneous activation of the infra-auricular facial nerve was performed with the 20-mm double coil. RESULTS: The reproducible CMAP and long latency responses were obtained from normal subjects with TMS. However, responses were observed only in patients with relatively mild Bell's palsy. The magnetic stimulation-evoked responses reflected the brainstem function in the patients with a CPA tumor and MS. CONCLUSION: Although magnetic stimulation remains inferior to conventional electric stimulation in some sense and requires further study, this method is potentially useful because it can stimulate the facial nerve continuously from the cortex to the periphery and can effectively evoke responses reflecting the brainstem function.

Adolescent↗
PubMed1999

Repetitive monomorphic ventricular tachycardia of left coronary cusp origin.

Repetitive monomorphic ventricular tachycardia with a morphology of inferior axis and left bundle branch block pattern in patients without structural heart disease commonly originates from the right ventricular outflow tract. We report the case of a 22-year-old man with an incessant, monomorphic ventricular tachycardia with a similar morphology originating from the left coronary cusp, which was confirmed by perfect pace mapping, local ventricular activation preceding the onset of QRS by 25 mse, and eliminated by a single delivery of low-energy (11 W) radiofrequency currents.

Adult↗
PubMed1999

Torsion of a functional ovarian cyst in a premenopausal patient receiving tamoxifen.

We report a case of torsion of an ovarian follicular cyst that developed during treatment with tamoxifen for breast cancer. A 40-year-old Japanese woman was admitted complaining of acute lower abdominal pain. Eight months earlier, she had undergone a partial mastectomy and local irradiation for ductal carcinoma of her left breast, estrogen receptor-positive stage I (T(1a) N(1b) M(0)). The administration of tamoxifen, 20 mg/day, and doxifluridine, 600 mg/day, were started immediately postoperatively. Pelvic examination after admission revealed the left ovarian cyst and enlarged uterus. Transvaginal ultrasonography and computed tomography revealed a multilocular cystic mass in the pelvic cavity. The pathological diagnosis of the tumor after total hysterectomy and bilateral salpingo-oophorectomy was a typical follicular cyst with torsion and uterine leiomyoma. This ovarian cyst was believed to have developed during tamoxifen administration.

Adult↗
PubMed1999

High-performance liquid chromatographic analysis of chlorhexidine in saliva after mouthrinsing.

A high-performance liquid chromatographic method was developed to quantify chlorhexidine in human saliva. After addition of an internal standard and acidic-deproteinization, saliva samples were chromatographed by the reversed-phase ion-pair system using pentanesulfonate as a counterion and the eluates were detected by a diode array detector. Under optimal conditions, the baseline separation of analytes was achieved within 4.5 min without interference from components in saliva matrix. The method showed high selectivity to salivary chlorhexidine, quantitative range (50. 0ng/ml-50.0 microg/ml), recovery (96.0-97.8%) and analytical precision (intra- and interassay CVs within 0.41%), permitting the effective application to both saliva and aqueous solutions. Chlorhexidine was found in saliva at microgram per milliliter levels for at least 8 h after mouthrinsing with 10 ml of an aqueous solution of chlorhexidine (0.1 or 1.0 mg/ml) for 1 min. The concentrations of salivary chlorhexidine were reduced by ingesting the acidic beverage and food, but not by ingesting the neutral beverage. The adsorption experiments in artificial saliva revealed that chlorhexidine was significantly adsorbed to saliva-coated hydroxyapatite, buccal epithelial cells and mucin. The proposed method will be a useful tool to study salivary chlorhexidine after oral application and its retention in the oral cavity.

Adsorption↗
PubMed1999

Suppression of arthritic bone destruction by adenovirus-mediated csk gene transfer to synoviocytes and osteoclasts.

Rheumatoid arthritis (RA) is characterized by a chronic inflammation of the synovial joints resulting from hyperplasia of synovial fibroblasts and infiltration of lymphocytes, macrophages, and plasma cells, all of which manifest signs of activation. Recent studies have revealed the essential role of osteoclasts in joint destruction in RA. Src family tyrosine kinases are implicated in various intracellular signaling pathways, including mitogenic response to growth factors in fibroblasts, activation of lymphocytes, and osteoclastic bone resorption. Therefore, inhibiting Src activity can be a good therapeutic strategy to prevent joint inflammation and destruction in RA. We constructed an adenovirus vector carrying the csk gene, which negatively regulates Src family tyrosine kinases. Csk overexpression in cultured rheumatoid synoviocytes remarkably suppressed Src kinase activity and reduced their proliferation rate and IL-6 production. Bone-resorbing activity of osteoclasts was strongly inhibited by Csk overexpression. Furthermore, local injection of the virus into rat ankle joints with adjuvant arthritis not only ameliorated inflammation but suppressed bone destruction. In conclusion, adenovirus-mediated direct transfer of the csk gene is useful in repressing bone destruction and inflammatory reactions, suggesting the involvement of Src family tyrosine kinases in arthritic joint breakdown and demonstrating the feasibility of intervention in the kinases for gene therapy in RA. off

Adenoviridae↗
PubMed1999

Synthesis and pharmacological evaluation of pyrroloazepine derivatives as potent antihypertensive agents with antiplatelet aggregation activity.

A series of 1-aminoalkyl-pyrrolo[2,3-c]azepin-8-one derivatives was synthesized and evaluated as alpha 1 adrenergic and serotonin 2 (5-HT2) receptor antagonists, with the aim of finding a novel antihypertensive agent potently exhibiting both activities. Some compounds with a 4-[4-(4-fluorobenzoyl)piperidino]butyl group at the 1-position exhibited both activities, and varied significantly in terms of the substituents at the 4-position of the pyrroloazepine ring. Among the compounds obtained in this study, (E)-1-[4-[4-(4-fluorobenzoyl)piperidino]-butyl]-4-hydroxyimino-7- methyl-1,4,5,6,7,8-hexahydropyrrolo[2,3-c]azepin-8-one (15a, SUN9221) displayed potent alpha 1-adrenergic antagonistic activity (pA2 = 8.89 +/- 0.21) and 5-HT2 antagonistic activity (pA2 = 8.74 +/- 0.22) in isolated guinea pig arteries. This compound exhibited antihypertensive activity and a duration of action equivalent to orally administered prazosin or doxazosin, 3 mg/kg, in conscious spontaneously hypertensive rats, as well as potent antiplatelet aggregation activity.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed1999

Ventricular fibrillation and shortening, alternans and after-depolarizations of epicardial monophasic action potentials during coronary occlusion and reperfusion: effect of repetition of ischemia.

The relationship between the occurrence of ventricular fibrillation (VF) and repolarization abnormalities of the ischemic and reperfused myocardium is poorly understood. The present study examined the temporal relationship between ischemia- and reperfusion-induced changes in monophasic action potential (MAP) configurations and the occurrence of VF, and assessed the effects of repetition of ischemia. The left anterior descending coronary artery of 32 anesthetized dogs was occluded twice for 5 min, 30 min apart, during constant atrial pacing while recording MAPs from the epicardial ischemic zone. During the first occlusion, shortening of the MAP duration at 90% repolarization (APD90) and an increase in MAP alternans, defined as the maximal difference in APD90 between 2 consecutive beats, were observed. Afterdepolarizations also occurred transiently in 35% of the animals during occlusion and in 29% upon reperfusion. VF occurred in 28% (9/32 of the dogs) during the first sequence, and the incidence was higher in the subgroups with maximal alternans > or =20 ms (p<0.05), maximal shortening rate > or =30%, and afterdepolarizations. During the second sequence, the incidence of VF was reduced to 9% (3/32, p<0.05), associated with a significant reduction in the MAP changes. Thus, repolarization abnormalities of the ischemic and reperfused myocardium appear to be related to the occurrence of VF. The amelioration of the repolarization abnormalities by repetition of ischemia may be involved in its antifibrillatory effect.

Action Potentials↗
PubMed1999

Gadolinium suppresses stretch-induced increases in the differences in epicardial and endocardial monophasic action potential durations and ventricular arrhythmias in dogs.

We tested whether acute pressure overloading of the left ventricle (LV) had spatially different effects on repolarization, thereby causing arrhythmias. The effects of gadolinium (Gd3+), a nonspecific blocker of stretch-activated channels were also examined. In anesthetized dogs, 5 s clamping of the ascending aorta (AC), separated by 5-min intervals, was repeated while monophasic action potentials (MAPs) were recorded from the LV endocardium and epicardium. Gd3+ was injected into the left atrium before the second (500 micromol) and third AC (2500 micromol) (n=10). In a separate group (n=7), the effects of Gd3+ in the presence of verapamil were examined. Epicardial MAP durations at 50% and 90% repolarization (APD50; APD90) shortened in response to LV pressure rise and elongation of the segment length induced by the first AC, whereas endocardial MAP durations remained unchanged. Thus, the difference in APD50 and APD90 increased. Consistent with these changes, premature ventricular contractions (PVCs) developed. Gd3+ had no effect on baseline MAP durations, however it prevented an AC-induced increase in the difference by suppressing epicardial MAP shortening. Gd3+ also reduced PVCs in a dose-dependent manner at plasma concentrations of 1-4 micromol/L. The effects were also evident after administration of verapamil. Thus, gadolinium suppressed an increase in the spatial dispersion of repolarization and arrhythmias via a mechanism of action different from that of verapamil.

Action Potentials↗
PubMed1999

Differences in the sensitivity to UVB radiation of two cultivars of rice (Oryza sativa L.) based on observation of long-lived radicals.

Free radicals with a long lifetime were observed in the leaves of two rice cultivars (Oryza sativa L.), Sasanishiki (UVB resistant) and Norin-1 (UVB sensitive), by electron spin resonance spectroscopy. The leaves of both cultivars grown with visible light show very similar ESR spectra composed of radical 1 (R1) and radical 2 (R2), which may be attributable to P700 cation radicals in the reaction center of photosystem I, and tyrosine cation radicals in the reaction center of photosystem II, respectively. The ESR spectrum composed of R1 and R2 radicals in the leaves of Sasanishiki grown under visible light with supplemental UVB was similar to that in the plant grown without supplemental UVB. On the other hand, the amount of R2 radicals in the leaves of Norin-1 grown under visible light with supplemental UVB was significantly smaller than that in the plant grown without supplemental UVB. It is suggested that the loss of R2 radicals in Norin-1 upon UVB irradiation is related to the instability of the plant.

Electron Spin Resonance Spectroscopy↗
PubMed1999

A resected case of pancreatic metastasis from primary renal cell carcinoma.

A 71-year-old man, who had received a right nephrectomy for a primary renal cell carcinoma 8 years earlier, and had two years later received a distal gastrectomy for duodenal ulcer, was admitted. In the subsequent clinical course, a solitary low echographical tumor was found in the pancreas. Abdominal computed tomography revealed a tumor of low density area, and celiac angiography revealed a hypervascular tumor stain of the pancreas. From the above findings, a diagnosis of pancreatic tumor was made, and a distal pancreatectomy was performed. Examination of the resected tissues confirmed the presence of a solitary tumor in the pancreatic tail. Histologically, the tumor corresponded to the initial renal cell carcinoma and pancreatic metastasis of renal cell carcinoma was diagnosed. We report a resected case of such a metastasis and review the literature.

Aged↗
PubMed1999

Resin content in cement liquids of resin-modified glass ionomers.

Qualitative and quantitative analyses were conducted on four kinds of resin-modified glass ionomer (RMGI) cement liquids, LC, LC II, LC III (hereinafter referred to as LCs) and VM, using HPLC and laser Raman spectroscopic methods. HPLC revealed that among the RMGI liquids LCs contain 31-32% HEMA (2-Hydroxyethyl methacrylate), and VM contains 18% of the same. The composition of RMGI cement liquids varied significantly between manufacturers. In Raman spectroscopic analyses, the spectra of liquids of various ratios of polyacrylic acid and HEMA were measured, and calculations were made on the peak intensity ratios of C=C stretch vibration to C=O stretch vibration, common in both HEMA and polyacrylic acid. The composition ratio of polycarboxylic acid to HEMA of commercial glass ionomer cements was assessed by the regression curve generated by a combination of peak intensity ratios and composition ratios. In addition, Raman spectroscopy was able to identity the differences in form of the methacryloyloxy group.

Carboxylic Acids↗
PubMed1999

Successful pregnancy in a woman with a human seminal plasma allergy. A case report.

BACKGROUND: Human seminal plasma allergy is an anaphylaxis caused by immediate hypersensitivity to human seminal plasma. The utilization of a condom is usually recommended as the primary means of preventing an allergic reaction. Infertility resulting from condom use, however, is an undesirable complication in many cases. Here we report on a successfully established pregnancy in a woman with seminal plasma allergy. CASE: A 29-year-old, married nulligravida with a human seminal plasma allergy consulted us to conceive. She showed a positive reaction to a skin-prick test with whole semen. In order to remove the seminal plasma, the sperm were washed three times using a continuous-step density gradient centrifugation method. Artificial insemination with the washed sperm was performed without anaphylactic symptoms. After six inseminations, pregnancy was achieved, and a healthy infant was delivered. CONCLUSION: Artificial insemination with sperm devoid of seminal plasma was very useful for establishing pregnancy in a woman with a human seminal plasma allergy.

Adult↗
PubMed1999

[Changes in nitric oxide-related compounds in endotoxemic rats].

NO-related compounds in the blood of septic rats were examined by chemiluminescence method. Rats were treated with 5 mg/kg or 10 mg/kg lipopolysaccharides (LPS) and followed for 30 h. We have determined and evaluated the concentrations of the total NO-related compounds in whole blood (Total-NO), those in plasma (Plasma-NO) and membrane bound-NO (Membranous-NO) in erythrocytes from the LPS-challenged rats. 1) Levels of Plasma-NO after 3 h and Membranous-NO after 7 h in the rats were significantly increased, peaked at 14 h, and then restored to control levels at 30 h. 2) At 7 h in the rats, latter NO levels were exhibited within 10 nM/mg protein. 3) The existence of Membranous-NO can be confirmed by the in vitro experiments of rat erythrocytes incubating with different NO-donors, NOC-3 or SIN-1. 4) Taken together, the determination of Membranous-NO may be an additional marker for pathophysiological states of septic stress.

Animals↗