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T Ohara

Publications and source records attributed to T Ohara.

At least 37 records · Page 2Linked to original sources
PubMed2001

Analysis of methicillin-resistant Staphylococcus aureus isolates by proton magnetic resonance spectroscopy.

OBJECTIVES: To evaluate the stability and(1)H nuclear magnetic resonance ((1)H NMR) differences among bacterial strains, we analysed(1)H NMR spectra for 50 methicillin-resistant Staphylococcus aureus (MRSA) isolates from 42 patients. METHODS: (1)H NMR spectra for 50 MRSA isolates were obtained at 30 degrees C using a JNM-GX 270 NMR spectrometer at a field strength of 6.34 Tesla (270 MHz for(1)H). DNA fingerprints were obtained by pulsed-field gel electrophoresis (PFGE). RESULTS: Each strain had eight to nine specific resonance features in the 0.5-4.5 ppm spectral region. These features were found in all strains, but the intensity of each feature varied between strains. Six resonance features (A-F) were selected for investigation. The relative integrated intensity (mean+/-SD, normalized to feature C = 1) of each feature was: feature A, 0.49+/-0.16; feature B, 3.93+/-0.81; feature D, 0.38+/-0.22; feature E, 1.51+/-0.96; feature F, 2.18+/-0.47. Within-strain reproducibility of feature intensities for A, B, D and F was good (coefficient of variation < 10%) for replicate cultures, analyzed on separate days. Feature E showed poor within-strain reproducibility. Storage at 4 degrees C for 4 months or disintegration of the micro-organisms by ultrasound did not alter(1)H NMR spectra. Two isolates from different patients, but the same hospital, showed indistinguishable NMR spectra, and were also indistinguishable in PFGE. Five strains with distinct PFGE patterns showed differences in NMR spectra outside the range of within-strain variation. CONCLUSIONS: It is possible to analyse the whole molecular structure of MRSA by(1)H NMR. With this technique, we established that there are detectable, reproducible differences in quantitative cell composition between MRSA strains.(1)H NMR spectroscopy appears to have potential as a useful tool for epidemiological typing of bacteria.

DNA Fingerprinting↗
PubMed2001

Overexpression of co-stimulatory molecules in peripheral mononuclear cells of Helicobacter pylori-positive peptic ulcer patients: possible difference in host responsiveness compared with non-ulcer patients.

BACKGROUND/AIM: Helicobacter pylori is the principal cause of gastritis and peptic ulcer disease. However, H. pylori-positive patients do not always have peptic ulcer. This study was carried out in order to determine the difference in host immune reaction to H. pylori between patients with peptic ulcer and those without. METHODS: Ten H. pylori-positive patients with peptic ulcer, 10 H. pylori-positive non-ulcer patients, and 10 healthy volunteers were examined for expression of surface molecules in peripheral blood mononuclear cells. The surface molecules were stained with immunofluorescence-labelled specific antibodies and analysed by flow cytometry. RESULTS: More mononuclear cells expressed molecules ICAM-1, VLA-4, Leu-M3 in H. pylori-positive ulcer patients than in non-ulcer patients and healthy volunteers. There were also more cells expressing CD28, SLe(x), CD4, HLA-DR, and NU-B2 in H. pylori-positive ulcer patients than in non-ulcer patients and healthy volunteers. There were fewer cells expressing CD8 in H. pylori-positive ulcer patients than in non-ulcer patients and healthy volunteers. CONCLUSION: H. pylori infection may cause immunological reactions which are reflected in peripheral mononuclear cells. However, the activity and characteristics of peripheral mononuclear cells, in terms of expression of adhesion molecules, may differ between ulcer and non-ulcer patients who are infected with H. pylori.

Adult↗
PubMed2001

Effects of diacetyl monoxime and cytochalasin D on ventricular fibrillation in swine right ventricles.

Whether or not the excitation-contraction (E-C) uncoupler diacetyl monoxime (DAM) and cytochalacin D (Cyto D) alter the ventricular fibrillation (VF) activation patterns is unclear. We recorded single cell action potentials and performed optical mapping in isolated perfused swine right ventricles (RV) at different concentrations of DAM and Cyto D. Increasing the concentration of DAM results in progressively shortened action potential duration (APD) measured to 90% repolarization, reduced the slope of the APD restitition curve, decreased Kolmogorov-Sinai entropy, and reduced the number of VF wave fronts. In all RVs, 15-20 mmol/l DAM converted VF to ventricular tachycardia (VT). The VF could be reinduced after the DAM was washed out. In comparison, Cyto D (10-40 micromol/l) has no effects on APD restitution curve or the dynamics of VF. The effects of DAM on VF are associated with a reduced number of wave fronts and dynamic complexities in VF. These results are compatible with the restitution hypothesis of VF and suggest that DAM may be unsuitable as an E-C uncoupler for optical mapping studies of VF in the swine RVs.

Action Potentials↗
PubMed2001

Patterns of wave break during ventricular fibrillation in isolated swine right ventricle.

Several different patterns of wave break have been described by mapping of the tissue surface during fibrillation. However, it is not clear whether these surface patterns are caused by multiple distinct mechanisms or by a single mechanism. To determine the mechanism by which wave breaks are generated during ventricular fibrillation, we conducted optical mapping studies and single cell transmembrane potential recording in six isolated swine right ventricles (RV). Among 763 episodes of wave break (0.75 times x s(-1) x cm(-2)), optical maps showed three patterns: 80% due to a wave front encountering the refractory wave back of another wave, 11.5% due to wave fronts passing perpendicular to each other, and 8.5% due to a new (target) wave arising just beyond the refractory tail of a previous wave. Computer simulations of scroll waves in three-dimensional tissue showed that these surface patterns could be attributed to two fundamental mechanisms: head-tail interactions and filament break. We conclude that during sustained ventricular fibrillation in swine RV, surface patterns of wave break are produced by two fundamental mechanisms: head-tail interaction between waves and filament break.

Action Potentials↗
PubMed2001

Non-invasive diagnosis of concealed Wolff-Parkinson-White syndrome by detection of concealed anterograde pre-excitation.

Electrophysiological findings suggest that concealed anterograde conduction through accessory pathways may exist even during sinus rhythm in patients with so-called concealed Wolff-Parkinson-White (WPW) syndrome. To evaluate the pre-excitation characteristics in various types of WPW syndrome, high-resolution electrocardiograms were analyzed in 81 consecutive WPW syndrome patients and 50 age-matched normal subjects. The WPW group consisted of 30 cases of concealed WPW diagnosed by electrophysiological study, 38 cases of manifest WPW in which apparent delta waves were constant, and 13 cases of intermittent WPW in which the delta waves appeared periodically. The duration of the low-amplitude, high-frequency components of the signal-averaged filtered QRS complex that preceded the earliest upstroke of the surface QRS, including any delta waves (preceding potential duration, PPD), and the duration of low amplitude signals less than 10 microV (I-LAS10) or 20 microV (I-LAS20) were measured as parameters of pre-excitation. The PPDs in concealed and intermittent WPW were both significantly longer than in manifest WPW or in control subjects (6.8+/-2.7 ms, 7.9+/-3.5 ms vs 2.3+/-3.2 ms, 1.0+/-1.6 ms, both p<0.0001). Abnormally prolonged PPDs (>4 ms) were observed in 90% of concealed WPW cases and 76.9% of intermittent WPW, but in only 4% of normal subjects and 31.6% of manifest WPW. Both I-LAS10 and I-LAS20 in the 3 types of WPW syndrome were significantly longer than in normal subjects. The initial portion of the filtered QRS in concealed WPW closely resembled that of intermittent WPW. These results strongly suggest that in concealed WPW anterograde conduction through accessory pathways does occur and produces small amounts of pre-excitation even during sinus rhythm. The study concluded that, despite its name, concealed WPW is not completely concealed, and that non-invasive diagnosis during sinus rhythm is possible by using high-resolution electrocardiography to detect the concealed anterograde pre-excitation.

Electrocardiography↗
PubMed2001

Abnormal myocardial free fatty acid utilization deteriorates with morphological changes in the hypertensive heart.

The left ventricle's morphological adaptation to high blood pressure is classified into 4 patterns based on mass and wall thickness. The geometric changes caused by maladaptation to pressure overload possibly relate to progression of contractile dysfunction with abnormal energy metabolism. The present study assessed whether the geometric adaptation of the left ventricle (LV) to high blood pressure relates to changes in myocardial energy metabolism, especially free fatty acid (FFA) utilization. Thirty-five patients with essential hypertension underwent echocardiography and dual isotopes myocardial scintigraphy using iodine-123 labeled 15-p-iodophenyl-3-(R,S)-methylpentadecanoic acid (BMIPP, an analogue of a FFA) and thallium-201 (Tl-201). Systolic (endocardial fractional shortening; %FS) and diastolic indices (the ratio of early to atrial filling waves; E/A) of LV function were also assessed. Quantitative myocardial BMIPP uptake was evaluated by the BMIPP/TI-201 myocardial uptake ratio (B/T). The subjects were divided into 4 groups based on LV mass and wall thickness: (1) concentric hypertrophy (CH), (2) eccentric hypertrophy (EH), (3) concentric remodeling (CR), and (4) normal geometry (N). The %FS was lower in the EH group than in the other groups. The mitral E/A ratio in the CH group was lowest. B/T was significantly decreased in the EH group compared with the N group (p < 0.05). B/T correlated with the mitral E/A ratio significantly (p < 0.05, r = 0.42), whereas there was no relationship between %FS and B/T. These results indicate that the geometric changes occurring in hypertensive hearts strongly correlate with alternations in cardiac function and with abnormal myocardial FFA metabolism, and that the latter is associated with diastolic abnormality, but not with systolic function.

Aged↗
PubMed2001

Evaluation of the AMPLICOR CMV, COBAS AMPLICOR CMV monitor and antigenemia assay for cytomegalovirus disease.

The AMPLICOR CMV (qualitative DNA assay by PCR), COBAS AMPLICOR CMV Monitor (quantitative DNA assay by PCR), and antigenemia assay were tested for their ability to diagnose cytomegalovirus (CMV) infection in 115 immunocompromised patients. The AMPLICOR qualitative assay and the antigenemia assay were positive for all nine patients with a clinical diagnosis of CMV disease. The AMPLICOR quantitative assay was negative for one of the nine patients. In 106 patients without CMV disease, the AMPLICOR qualitative test was positive in 22, the quantitative test was positive in 23, and the antigenemia test was positive in 55 patients. The AMPLICOR qualitative and quantitative assays had specificities of 79% and 78% in patients without CMV disease, while that of the antigenemia assay was 48%. Diagnostic efficiencies were 79% for the AMPLICOR qualitative assay, 69% for the AMPLICOR quantitative assay, and 48% for the antigenemia assay. All three tests yielded positive results before, or at the same time as, the onset of CMV disease in most cases, which suggests they can be used to predict disease before the onset of symptoms. During antiviral treatment, test results tended to decrease quantitatively and finally became negative; negative results were followed by remission of symptoms. This suggests that the AMPLICOR quantitative assay and the antigenemia assay could be useful for monitoring therapeutic efficacy. The AMPLICOR qualitative and quantitative assays, as well as the antigenemia assay were considered effective for all of the following: diagnosing CMV disease, predicting the onset of disease, and evaluating the effectiveness of antiviral chemotherapy. The antigenemia assay was at times difficult to perform in the case of severely neutropenic patients, whereas the AMPLICOR assays could be used in such cases.

Antigens, Viral↗
PubMed2000

Flow cytometry as a strategy to study the endosymbiosis of algae in Paramecium bursaria.

BACKGROUND: The stable symbiotic association between Paramecium bursaria and algae is of interest to study such mechanisms in biology as recognition, specificity, infection, and regulation. The combination of algae-free strains of P. bursaria, which have been recently established by treating their stocks of green paramecia with herbicide paraquat (Hosoya et al.: Zool Sci 12: 807-810, 1995), with the cloned symbiotic algae isolated from P. bursaria (Nishihara et al.: Protoplasma 203: 91-99, 1998), provides an excellent clue to gain fundamental understanding of these phenomena. METHODS: Flow cytometry and light microscopy have been employed to characterize the algal cells after they have been released from the paramecia by ultrasonic treatment. Algal optical properties such as light scattering and endogenous chlorophyll fluorescence intensity have been monitored for symbiotic and free-living strains, and strains at stages of interaction with a host. RESULTS: Neither algal morphology nor chlorophyll content has been found to be altered by sonication of green paramecia. This fact allows to interpret in adequate degree changes in the optical properties of symbiont that just has been released from the association with a host (decreased forward light scatter and chlorophyll fluorescence signals). Optical characterization of both symbiotic and free-living algal strains with respect to their ability to establish symbioses with P. bursaria showed that chlorophyll content per cell volume seems to be a valuable factor for predicting a favorable symbiotic relationship between P. bursaria and algae. CONCLUSIONS: Flow cytometry combined with algae-free paramecia and cloned symbiotic algae identifies algal populations that may be recognized by host cells for the establishment of symbioses.

Animals↗
PubMed2000

Mechanisms of ventricular fibrillation induction by 60-Hz alternating current in isolated swine right ventricle.

BACKGROUND: The mechanisms by which 60-Hz alternating current (AC) can induce ventricular fibrillation (VF) are unknown. METHODS AND RESULTS: We studied 7 isolated perfused swine right ventricles in vitro. The action potential duration restitution curve was determined. Optical mapping techniques were used to determine the patterns of activation on the epicardium during 5-second 60-Hz AC stimulation (10 to 999 microA). AC captured the right ventricles at 100+/-65 microA, which is significantly lower than the direct current pacing threshold (0.77+/-0.45 mA, P:<0.05). AC induced ventricular tachycardia or VF at 477+/-266 microA, when the stimulated responses to AC had (1) short activation CLs (128+/-14 ms), (2) short diastolic intervals (16+/-9 ms), and (3) short diastolic intervals associated with a steep action potential duration restitution curve. Optical mapping studies showed that during rapid ventricular stimulation by AC, a wave front might encounter the refractory tail of an earlier wave front, resulting in the formation of a wave break and VF. Computer simulations reproduced these results. CONCLUSIONS: AC at strengths less than the regular pacing threshold can capture the ventricle at fast rates. Accidental AC leak to the ventricles could precipitate VF and sudden death if AC results in a fast ventricular rate coupled with a steep restitution curve and a nonuniform recovery of excitability of the myocardium.

Animals↗
PubMed2000

Nerve sprouting and sudden cardiac death.

The factors that contribute to the occurrence of sudden cardiac death (SCD) in patients with chronic myocardial infarction (MI) are not entirely clear. The present study tests the hypothesis that augmented sympathetic nerve regeneration (nerve sprouting) increases the probability of ventricular tachycardia (VT), ventricular fibrillation (VF), and SCD in chronic MI. In dogs with MI and complete atrioventricular (AV) block, we induced cardiac sympathetic nerve sprouting by infusing nerve growth factor (NGF) to the left stellate ganglion (experimental group, n=9). Another 6 dogs with MI and complete AV block but without NGF infusion served as controls (n=6). Immunocytochemical staining revealed a greater magnitude of sympathetic nerve sprouting in the experimental group than in the control group. After MI, all dogs showed spontaneous VT that persisted for 5.8+/-2.0 days (phase 1 VT). Spontaneous VT reappeared 13.1+/-6.0 days after surgery (phase 2 VT). The frequency of phase 2 VT was 10-fold higher in the experimental group (2.0+/-2.0/d) than in the control group (0.2+/-0.2/d, P<0.05). Four dogs in the experimental group but none in the control group died suddenly of spontaneous VF. We conclude that MI results in sympathetic nerve sprouting. NGF infusion to the left stellate ganglion in dogs with chronic MI and AV block augments sympathetic nerve sprouting and creates a high-yield model of spontaneous VT, VF, and SCD. The magnitude of sympathetic nerve sprouting may be an important determinant of SCD in chronic MI.

Adrenergic beta-Antagonists↗
PubMed2000

Angiographic and clinical outcome of a new self-expanding intracoronary stent (RADIUS): results from multicenter experience in Japan.

The RADIUS coronary stent featuring a multisegmented slotted tube design and self-expanding nitinol delivery system has a high radial force and flexibility, uniform expansion, and contours to the shape of the vessel. Successful stent deployment was achieved in 104 stable angina patients (106 lesions; 44% LAD, 19% circumflex, and 37% RCA). Mean minimal lumen diameter (MLD) increased from 0.77 +/- 0.46 mm to 2.88 +/- 0.61 mm and mean percent diameter stenosis (% DS) decreased from 73 +/- 14% to 6 +/- 13% immediately after the procedure. At 6-month follow-up, two patients (2%) underwent urgent target revascularization, and cerebral bleeding occurred in one patient (1%). Angiographic follow-up was performed in 94 lesions (89%) and mean MLD and mean % DS were 2.08 +/- 0.92 mm and 30% +/- 24%, respectively. Stent restenosis (>50% diameter stenosis at follow-up) was observed in 16 (17%) of all lesions. The high success rate for stent deployment, low incidence of major adverse cardiac event, and lower restenosis rate after stent implantation indicate that the RADIUS stent is useful for coronary intervention.

Adult↗
PubMed2000

Successful transplantation of a cadaveric kidney with post-infectious glomerulonephritis.

This report describes a successful renal Tx in a patient with chronic renal failure, caused by dysplastic kidneys, who received a cadaveric kidney with post-infectious glomerulonephritis. Sequential renal biopsies were performed at 12 h before Tx, and at 1 h and on days 8 and 58 post-Tx. Post-operative hematuria disappeared on day 9 and proteinuria on day 13. Normal graft function was observed within 1 month, with histologic resolution. Our study suggests that while the donor kidney facilitates deposition of certain immune reactants, this is a host (environmental) problem and when transplanted into a new host (new environment), the problem is no longer sustained.

Adolescent↗