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Biomedical subjects

Y Yamauchi

Publications and source records attributed to Y Yamauchi.

At least 19 recordsLinked to original sources
PubMed1999

Type A behavior is associated with an increased risk of left ventricular hypertrophy in male patients with essential hypertension.

OBJECTIVE: To determine whether type A behavior, which is associated with a risk of coronary heart disease, affects left ventricular hypertrophy in patients with essential hypertension. DESIGN: Cross-sectional study of 88 untreated patients with mild to moderate essential hypertension (33 men, mean +/- SEM age 54 +/- 1 years). METHODS: We measured the type A behavior score using a standardized questionnaire, left ventricular mass index using M-mode echocardiography and 24 h mean ambulatory blood pressure (recorded every 30 min). Beat-to-beat blood pressure was also measured using a Finapres device in patients at rest and during mental stress (counting backward) to determine the blood pressure response to stress. RESULTS: The left ventricular mass index was correlated with the type A behavior score (r = 0.214, P < 0.05), age (r = 0.266, P < 0.05), 24 h mean systolic and diastolic blood pressures (r = 0.391, P < 0.001, and r = 0.382, P < 0.001, respectively), systolic blood pressure both at rest and during stress (r = 0.255, P < 0.05, and r = 0.215, P < 0.05, respectively), and the variability of both systolic and diastolic blood pressures at rest (r = 0.253, P < 0.05, and r = 0.321, P < 0.01, respectively). Stepwise multiple linear regression analysis demonstrated that age was associated with an increase in the left ventricular mass index for both sexes (P = 0.004 for males, P = 0.003 for females). The type A behavior score predicted a greater increase in left ventricular mass index in men (P = 0.018) but not in women. The 24 h mean systolic blood pressure was associated with a greater increase in left ventricular mass index in women (P < 0.001) but not in men. CONCLUSION: Type A behavior is an independent risk factor for left ventricular hypertrophy in male patients with essential hypertension.

Blood Pressure↗
PubMed1999

Real-time 3-D model-based navigation system for endoscopic paranasal sinus surgery.

This paper presents a three-dimensional (3-D)-model-based navigation system for endoscopic sinus surgery treating paranasal sinusitis. Endoscopic surgery is becoming more common because of its low invasiveness. Its problem with disorientation, however, is one of the toughest barriers for the novice and may lead even an expert to commit serious surgical errors, e.g., causing cerebrospinal fluid (CSF) leakage or blinding the patient. To prevent such complications and optimize training, our system aids in navigation by showing a single perspective view of the patient and the endoscope models. This virtual endoscope has a viewing cone with a simulated light to indicate the viewing direction and visual field in real-time. The system's three clipping planes automatically follow the endoscope and help keep the surgeon aware of the endoscope's actual position. An experiment comparing the system to conventional navigation using a triplanar display showed that the perspective view was referenced very frequently, giving a positive impressions, while the triplanar display was almost completely ignored, apparently because it was too difficult to interpret immediately.

Adult↗
PubMed1999

A new model rat with acute bronchiolitis and its application to research on the toxicology of inhaled particulate matter.

The aim of the present study was to establish a useful animal model that simulates humans sensitive to inhaled particulate matter (PM). We have developed a new rat model of acute bronchiolitis (Br) by exposing animals to NiCl2 (Ni) aerosols for five days. Three days following the Ni exposure, the animals developed signs of tachypnea, mucous hypersecretion, and bronchiolar inflammation which seemed to progress quickly during the fourth to fifth day. They recovered from lesions after four weeks in clean air. To assess the sensitivity of the Br rats to inhaled particles, two kinds of PM of respirable size were tested with doses similar to or a little higher to the recommended threshold limit values (TLVs) for the working environment in Japan. Titanium dioxide (TiO2 = Ti) was chosen as an inert and insoluble particles and vanadium pentoxide (V2O5 = V), as a representative soluble and toxic airborne material. The Br rats exposed to either Ti or V were compared the pathological changes in the lungs and the clearance of particles to those in normal control or Br rats kept in clean air. The following significant differences were observed in Br rats: 1. delayed recovery from pre-existing lesions or exacerbated inflammation, 2. reductions in deposition and clearance rate of inhaled particles with the progress of lesions. The present results suggest that Br rats are more susceptible to inhaled particles than control rats. Therefore, concentrations of particulate matter lower than the TLVs for Japan, which have no harmful effects on normal lungs, may not always be safe in the case of pre-existing lung inflammation.

Acute Disease↗
PubMed1999

[A case of Guillain-Barrè syndrome with severe sciatica preceding motor paralysis in the lower extremities].

A 62-year-old man was referred to our clinic for a three-day history of intractable sciatic pain. The pain was so severe that he could not sleep for days. Initially there was no neuronal sign except for the pain, nor any abnormality in lumbar CT and MRI. Cerebrospinal fluid sampled on the third hospital day revealed elevated protein (192 mg.dl-1) with minimal cells. On the 4th hospital day motor weakness of lower extremities appeared and he developed complete flaccid paraplegia in a week without loss of sensation. He was diagnosed as Guillain-Barrè syndrome. For the relief of this pain, intermittent injection of 4 ml 0.25% bupivacaine from lumbar epidural catheter was started on the admission day. By using patient controlled analgesia system, we could treat his repetitive demand timely and well control the pain. The leg weakness started to recover slowly from the 13th hospital day and at the same time the pain started to diminish rapidly in a few days. From the 20th hospital day he started to have rehabilitation in walking and recovered completely in two months without complication. We should remember that sudden onset of severe pain is one of early symptoms of Guillain-Barrè syndrome.

Analgesia, Epidural↗
PubMed1998

Stable expression of antisense Rb-1 RNA inhibits terminal differentiation of mouse myoblast C2 cells.

To determine the roles of the retinoblastoma gene (Rb-1) in skeletal muscle differentiation in vitro, we isolated C2 myoblasts stably expressing an antisense RNA directed to the 3'-untranslated region (3'UTR) of Rb-1 mRNA. The levels of Rb-1 mRNA and its product (pRb) in the clones transfected with antisense Rb were markedly decreased to 25-35% of those in the control clone. Cell growth of the clones was accelerated, especially in medium containing low concentrations of fetal calf serum. Even in differentiation medium with a low mitogen level, the antisense Rb clones proliferated as single-nucleated myoblast-like cells without expressing the sarcometric myosin heavy chain protein, whereas the control clone formed highly multinucleated myotubes after 4 days of culture under the same conditions. Under this condition, the levels of Rb-1 mRNA and pRb in the antisense Rb clones were 30-50% of those in the control clone, and no divergent increase in the Rb-family protein p107 expression was observed. This inhibited differentiation was abrogated by reintroducing expression vectors for the sense 3'UTR of Rb-1 mRNA or Rb-1 mRNA lacking its 3'UTR to the clone transfected with antisense Rb. In the antisense Rb clone cultured in differentiation medium, the amounts of MyoD and myogenin mRNA were markedly decreased on the 2nd day of culture in the differentiation medium. The expression of cell cycle-promoting genes including E2F-1 and cyclin D1 was up-regulated throughout the experiment. These results demonstrate that pRb is essential for the completion of terminal differentiation in C2 cells.

Actins↗
PubMed1998

A mutant strain of mouse FM3A cells defective in apoptotic DNA fragmentation.

A mutant strain of mouse FM3A cells was defective in apoptotic DNA fragmentation. Upon DNA damage by UV-radiation, the strain did not form DNA fragments, though it accumulated a large amount of p53 protein as did wild-type cells. No DNA fragmentation was observed when the strain was subjected to other kinds of DNA damaging agents such as X ray-radiation, or addition of etoposide to the culture medium. Other well-known biological stimulations inducing apoptosis, serum depletion or addition of TNF-alpha to the culture medium, also failed to cause DNA fragmentation in the cells. Using this apoptosis-deficient strain, we characterized another apoptotic reaction, export of phosphatidylserine to the cell surface. This molecule was exported onto the surface in both wild-type and the mutant cells when cells were treated with TNF-alpha and cycloheximide. Thus, the export of phosphatidylserine is suggested to be independent of the pathway for apoptotic DNA fragmentation.

Animals↗
PubMed1998

Apoptosis was promoted at a nonpermissive temperature in DNA replication-defective temperature-sensitive mutants of mouse FM3A cells.

Apoptosis was promoted at the nonpermissive temperature in some temperature-sensitive (ts) mutant strains of mouse FM3A cells deficient in initiation of DNA replication. We examined expression of cell cycle regulation genes in the four ts mutant strains and found that two strains, tsFT107 and tsFT111, exhibited marked accumulation of p53 protein by a posttranscriptional mechanism at 16 h after temperature up-shift. These two strains also exhibited high levels of p21 mRNA expression, repression of cyclin A and D1 mRNAs, and obvious accumulation of underphosphorylated retinoblastoma protein. Only these two strains died by apoptosis at day 3 after up-shift, although no change was observed in the level of bax mRNA. These results suggest the existence of two types of responses after temperature up-shift in the four temperature-sensitive cell strains of the initiation of DNA replication: one type directs inappropriate DNA replication that then may produce endogenous DNA damage, p53-mediated cell cycle arrest, and subsequent apoptosis, while the other type exhibits only the p53-independent cell cycle arrest.

Animals↗
PubMed1998

Age-dependent changes in metallothionein levels in liver and kidney of the Japanese.

Samples of liver, renal cortex, and medulla were obtained from 55 forensic autopsies (0- to 95-yr-old Japanese). Metallothionein (MT) was determined by the Ag-hem or Cd-hem method. Zinc (Zn), copper (Cu), and cadmium (Cd) were determined by atomic absorption spectrophotometry. The mean levels of MT were 250 micrograms/g in the liver, and 394 micrograms/g (cortex) and 191 micrograms/g (medulla) in the kidney. Age-dependent changes were observed in both the liver and kidney. In the liver, MT level decreased during infancy and increased thereafter with age. Similar age-dependent changes in the levels of Zn and Cu were observed. In the kidney cortex, MT level increased with age, although no correlation was found after middle age. The levels of Cd and Zn also increased with age until middle age; however, they decreased thereafter. These results suggest that age-dependent changes in renal MT levels are associated with accumulation of Cd.

Adolescent↗
PubMed1998

Does myocardial thallium-201 SPECT combined with electron beam computed tomography improve the detectability of coronary artery disease?--comparative study of diagnostic accuracy.

OBJECTIVE: The aim of this study is to evaluate the diagnostic accuracy of myocardial 201Tl SPECT combined with EBT for detecting CAD. METHODS: The study was based on 34 patients with suspected CAD, who had EBT and myocardial 201Tl SPECT. The CAD was diagnosed by the findings of coronary arteriography. Sensitivity, specificity and accuracy of EBT, myocardial 201Tl SPECT and the combined diagnosis on a per vessel basis and a per-patient basis were studied. RESULTS: The sensitivity for detecting CAD of myocardial 201Tl SPECT, EBT and the combined diagnosis was 85%, 77%, and 62%, respectively. No significant difference in the accuracy of myocardial 201Tl SPECT, EBT and the combined diagnosis was observed on a patient basis and per vessel basis. In the over 70 yr age subgroup, the sensitivity and accuracy of EBT for detecting LAD lesion were significantly superior to those of myocardial 201Tl SPECT. Regardless of age-based subgroups and gender, the combined diagnosis did not contribute to an improvement in diagnostic accuracy. CONCLUSION: Although the sensitivity of EBT for detecting LAD lesion in patients over 70 yr of age was significantly higher than that of myocardial 201Tl SPECT, in the detectability of CAD, combined use of myocardial 201Tl SPECT and EBT offers no improvement.

Adult↗
PubMed1998

Morphometric analysis of lymphatic and blood vessels in human chronic viral liver diseases.

The purpose of this study was to elucidate the morphometric changes occurring in hepatic lymphatics in human chronic viral liver diseases and to investigate the relationship between liver fibrosis, liver inflammation, and these changes. The lymphatic vessels were stained intensely by enzyme histochemistry for 5'-nucleotidase, whereas blood vessels stained well for alkaline phosphatase. We performed a morphometric analysis to estimate the number of lymphatic and blood vessels and their areas, using computer graphics software (NIH Image). Both the number of lymphatics in the specimens and their areas were increased according to the degree of liver fibrosis, but neither showed any relationship with the degree of activity of hepatitis. Neither the number nor the areas of the blood vessels showed any obvious relationship with the degree of fibrosis or the activity of chronic hepatitis. Correlation between clinical and laboratory data and the sizes and number of the lymphatics supported these morphological data. Our results clarified that the sizes and number of lymphatics are related to the stage of fibrosis in chronic viral liver diseases. This is thought to be due to increased lymph production, which is caused by the disturbance of the microcirculation associated with liver fibrosis.

5'-Nucleotidase↗
PubMed1998

Possible mechanism of ECG features in patients with idiopathic ventricular fibrillation studied by heart model and computer simulation.

The possible contribution of localized conduction delay and abnormal action potentials to ventricular fibrillation (VF) was studied by applying an anisotropic cardiac computer model to clinical cases of the Brugada-type electrocardiogram (ECG), which shows right bundle branch block (RBBB), a normal QT interval, ST-segment elevation, and late r' in leads V1 and V2. The anisotropic heart model was composed of 50,000 discrete units with a spatial resolution of 1.5 mm and was mounted in a human torso model. The longitudinal/transverse conduction velocity ratio was 3:1. For the normal ECG, a conduction velocity of 0.75 m/s was required. In the abnormal area of the right anterior epicardial wall, the conduction velocity was set at 0.2 m/s, with decreasing action potential amplitude and 10% prolonged action potential duration. The ECG features of ST-segment elevation and Brugada-type right bundle branch block pattern were simulated. The action potential duration was able to change dynamically with coupling interval of stimulation, with a ratio of 9% for normal ventricular muscle and 50% for Purkinje fibers. Five successive stimuli were applied to the left lateral epicardium 300 ms after the first sinus excitation, and sustained VF was induced with the transmural conduction delay at the right anterior ventricle as a block increasing the vulnerability. At the initiation of VF, reentry circuits were shown around the border zone of the right epicardium and were very heterogeneous around the conduction delayed area and septal area. In an area with the characteristics of nontransmural conduction delay, sustained VF was prevented, and the pattern of transient right bundle branch block appeared on the simulated ECG and body surface potential maps. The late r' wave was calculated in the precordial leads and right anterior site on the body surface potential maps. These results suggest that increased multipolarity in the border zone between the Purkinje fibers and delayed conduction area in the right ventricle might play an important role as a functional block for the persistence of VF.

Action Potentials↗
PubMed1998

Psychobehavioral factors involved in the isolated office hypertension: comparison with stress-induced hypertension.

OBJECTIVE: To investigate the psychobehavioral factors involved in the isolated clinic blood pressure elevation and hypertension induced by mental stress. DESIGN AND METHODS: We studied 73 untreated patients with essential hypertension defined as World Health Organization stage I or II (28 men and 45 women, mean age 55 +/- 11 years). The amount of isolated clinic blood pressure elevation was examined in terms of the difference between clinic and daytime ambulatory blood pressures. Blood pressure (measured using a Finapres device) and R-R interval (measured electrocardiographically) were continuously monitored with subjects at rest and under mental stress (counting backward) to examine the cardiovascular response to the stress. Psychobehavioral characteristics such as anger, anxiety, tension, type A behavior pattern, and nervousness were evaluated and scored using structured interviews and self-reporting questionnaires. RESULTS: The anger score was inversely correlated to the clinic-ambulatory blood pressure difference for the systolic (r = -0.308, P < 0.01) and diastolic (r = -0.233, P < 0.05) blood pressures. The score for type A behavior pattern tended to be inversely correlated to the clinic-ambulatory blood pressure difference for diastolic blood pressure (r = -0.209, P < 0.1). The nervousness score was positively correlated to stress-induced increase in the systolic (r = 0.249, P < 0.05) and diastolic (r = 0.232, P < 0.05) blood pressures. The clinic-ambulatory blood pressure difference was not related to the blood pressure rise induced by mental stress (r = 0.170 for systolic blood pressure; r = 0.112 for diastolic blood pressure). CONCLUSION: The isolated clinic blood pressure elevation and hypertension due to mental stress were related to different psychobehavioral factors.

Adult↗
PubMed1998

The effects of exogenous epinephrine on a convulsive dose of lidocaine: relationship with cerebral circulation.

In order to understand why exogenous epinephrine decreases the convulsive dose of lidocaine, the authors investigated cerebral circulation and plasma lidocaine concentrations in Wistar rats under general anesthesia. In the first experiment, baseline evaluations of each rat's electroencephalogram (EEG), mean arterial pressure (MAP), regional cerebral blood flow (r-CBF), cerebrospinal fluid (CSF) pressure, and cerebral perfusion pressure (CPP) were made. The rats were then assigned to one of three groups: Group L (n=6) received intravenous lidocaine (5 mg/kg/min); Group LE (n=6) received intravenous lidocaine (5 mg/kg/min) and epinephrine (2.5 kg/kg/min); and Group E (n=5) received intravenous epinephrine (2.5 microg/kg/min). Cumulative doses of lidocaine at the onset of EEG spike activity in Groups L and LE were compared. Blood-brain barrier (BBB) permeability was evaluated by observing extravasation of Evans blue (EB) dye. In the second experiment, additional rats were allocated to two treatment groups: Group L' (n=6) received intravenous lidocaine (5 mg/kg/min); Group LE' (n=6) received intravenous lidocaine (5 mg/kg/min) and epinephrine (2.5 microg/kg/min). Brain tissue oxygen partial pressure (PtO2) was monitored during infusion, and arterial and sagittal sinus blood samples were obtained immediately after the onset of EEG spike activity to determine plasma lidocaine concentration. The convulsive dose of lidocaine was significantly decreased when lidocaine was administered with epinephrine (Group L: 61.5+/-5.3 mg/kg (mean+/-SD); Group LE: 30.1+/-4.0 mg/kg) (p < 0.05), but there were no significant differences in plasma lidocaine concentration among these groups. R-CBF, CSF pressure, and CPP immediately before EEG spike activity were higher in Group LE than in Group L. Neither decreased PtO2 nor extravasation of EB was observed in rats treated with epinephrine and lidocaine, excluding cerebral ischemia and BBB breakdown from possible mechanisms by which epinephrine decreased the convulsive dose of lidocaine. None of the rats in Group E exhibited EEG findings suggestive of a preconvulsive state, ruling out a convulsive effect of epinephrine itself. The results suggest that an increase in lidocaine supply to the brain caused by increased CBF causes the low cumulative dose of lidocaine at the onset of convulsion in rats given lidocaine plus epinephrine.

Adrenergic Agonists↗
PubMed1998

Catheter ablation of ventricular tachycardia in patients with right ventricular dysplasia: Identification of target sites by entrainment mapping techniques.

OBJECTIVE: To identify target sites for radiofrequency ablation of ventricular tachycardia (VT) by entrainment mapping techniques in patients with arrhythmogenic right ventricular dysplasia. METHODS: Entrainment mapping and radiofrequency ablation of eight VTs was performed in seven patients. Radiofrequency ablation was applied at 31 reentry circuits sites that were classified based on findings during entrainment. RESULTS: By entrainment criteria the 31 sites were classified as: exit sites (n = 12), proximal sites (n = 6), and outer loop sites (n = 13). Radiofrequency current application terminated VT at 7 of 31 sites: 2 of 12 exit sites (17%), 4 of 6 proximal sites (67%), and 1 of 13 outer loop sites (8%). CONCLUSION: Radiofrequency ablation terminated VTs most often at sites proximal to the exit as opposed to outer loop sites and exit sites (P = 0.05). The critical isthmus for ablation of VT in right ventricular dysplasia often may be distant to the exit.

Arrhythmogenic Right Ventricular Dysplasia↗
PubMed1998

[A case of the active intestinal tuberculosis detected during the examination of the right pleural effusion].

A 76-year-old female was admitted to our hospital because of fever and the right pleural effusion. On the analysis of pleural effusion, the total cell count was 6720/microliter with 95% lymphocytes, and ADA was 38.1 U/l. The culture of pleural effusion was negative, and the smear and PCR for Mycobacterium were also negative. For examinations, we performed eterography that showed cicatricial strictures of intestine. X-ray examination of the colonated colonoscopy showed ulcers (circular type), shortening of the colon, Bauhin's value insufficiency and diverticulum-like deformity. Then, she was diagnosed as intestinal tuberculosis. The smear and PCR of biopsy specimens from the lesion were positive, and antituberculotic therapy was effective. Finally, the culture of pleural effusion for Mycobacterium tuberculosis was positive after 8 weeks. We thought intestinal examination may be useful for the diagnosis of tuberculosis, when lymphocyte-rich exudative pleural effusion of unknown etiology is seen.

Aged↗
PubMed1998

Reactive hemophagocytosis in systemic lupus erythematosus.

A patient with systemic lupus erythematosus (SLE) developed reactive hemophagocytosis. This case did not show any underlying diseases such as infection or malignancy other than SLE itself. The mechanisms inducing hemophagocytosis in SLE seem to be heterogeneous and remain to be elucidated. Although an immune complex-mediated mechanism in cases with acute lupus hemophagocytic syndrome has been proposed, we suggest the possible involvement of IL-1beta as the pathogenesis of our case.

Adult↗
PubMed1998

CJ-12,373, a novel topoisomerase II inhibitor: fermentation, isolation, structure elucidation and biological activities.

A novel isochroman carboxylic acid CJ-12,373 was isolated from Penicillium sp. CL22557. CJ-12,373 inhibits both DNA gyrase-mediated supercoiling and relaxation without the formation of a cleavage intermediate, suggesting that CJ-12,373 inhibits DNA gyrase at a stage distinct from the religation step. CJ-12,373 is not selective for procaryotic DNA gyrase as it also inhibits relaxation mediated by eukaryotic topoisomerase II. The antimicrobial potency of CJ-12,373, however, is largely attributed to its inhibition of DNA gyrase.

Anti-Bacterial Agents↗