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Biomedical subjects

H Kambara

Publications and source records attributed to H Kambara.

At least 19 recordsLinked to original sources
PubMed1992

Heterogeneity within the nonstructural protein 5-encoding region of hepatitis C viruses from a single patient.

Nucleotide (nt) sequence heterogeneity of the hepatitis C virus (HCV) genome derived from a single carrier was investigated. A polymerase chain reaction (PCR) product of 311 bp in the putative nonstructural protein 5-encoding region was directly sequenced, while part of a PCR product was cloned, and sequence analyses were carried out for 27 independent clones. Although 14 of the 27 clones were conserved, ten other types of nt sequences were found. The difference was at most 3 nt (1.1%). A directly determined sequence showed the major sequence of the cloned products. Since most of the nt changes occurred in the third letter of a codon, these nt changes might not have originated from random misincorporation during the PCR. These results of natural divergence of genome population in a single carrier suggest that HCV is a typical RNA virus with a quasi-species nature due to high mutation rates.

Base Sequence↗
PubMed1992

High resolution-separation of DNA bands by electrophoresis with a long gel in a fluorescence-detection DNA sequencer.

A high-resolution separation of DNA bands is achieved by electrophoresis with a long gel in DNA base sequencing using fluorescence detection. We separate 760 and 761 base DNA fragments using the 93 cm migration electrophoresis optimized for the separation of DNA bands. A T7 DNA polymerase and an Mn++ buffer are used in sequencing reactions to obtain fluorescence peaks of uniform strength, and the peak areas in the spectrum are used for recognizing the peak number in a cluster of successive peaks. This method is successfully applied to the DNA fragment spectrum obtained by 93 cm migration electrophoresis, which results in a single-band differentiation of bands of 1040 base DNA.

Base Sequence↗
PubMed1992

Photodestruction of fluorophores and optimum conditions for trace DNA detection by automated DNA sequencer.

Although automated DNA sequencers are becoming popular, their sensitivity in detecting DNA bands is still around 10(-17) mole/band. The sensitivity of a system depends on the laser power, labeling fluorophore, and the fluorescence-collecting yield. The emission and photodestruction cross-sections of the fluorophores are critical in optimizing the irradiated laser power and the migration speeds of DNA fragments to achieve high sensitivity. We investigated photodestruction cross-sections of various fluorophores to optimize the irradiation laser power. In addition, we used a cylindrical lens system to improve the fluorescence-collecting yield of a DNA sequencer using side entry laser irradiation. Fluoresceine isothiocyanate (FITC) commonly used in fluorescence studies, is very photo-destructive, the cross-section of the destruction being about 3.8 x 10(-20) cm2 in buffer solution while that of Texas Red is 1.5 x 10(-21) cm2. When the time for DNA fragments to transit through the irradiated region is 11 s, the optimum laser powers are 0.9 mW, with an Ar laser (488 nm) for FITC-DNA, and 18 mW, with an He-Ne laser (594 nm) for Texas Red DNA. We have developed a DNA sequencer, with a cylindrical lens system which improves the fluorescence-collecting efficiency by a factor of 4, and an He-Ne laser (5 mW). Although the sequencer uses a slab gel, an ultra-high sensitivity of 5 x 10(-20) mole/band (S/N-4) was achieved under optimized conditions.

Autoanalysis↗
PubMed1992

Clinical evaluation of cardiac function by ambulatory ventricular scintigraphic monitoring (VEST): validation and study of the effects of nitroglycerin and nifedipine in patients with and without coronary artery disease.

Global left ventricular function and ECGs were continuously monitored by radionuclide ambulatory ventricular function monitoring (VEST) and validated against multigated blood pool analysis (MUGA) and left ventriculography in 26 subjects (study 1). Ejection fraction by VEST (Y) showed good correlation with Y = 5.5 +/- 0.79 X (r = 0.91), Y = 1.7 +/- 0.86 X' (r = 0.91), and Y = 11.6 + 0.68 X" (r = 0.82) to sitting and supine MUGA and left ventriculography, respectively. In study 2 left ventricular function and ECGs were evaluated at rest and during exercise without any drug (control), with nitroglycerin, and with nifedipine in 21 patients with coronary disease (group I) and six normal subjects (group II). In group I abnormal ejection fraction responses (exercise increase less than or equal to 6%) during the control exercise period were found in 15 patients (71%), ST segment abnormalities in seven (33%), and chest pain in four (18%). Control exercise increased end-diastolic volume (100 to 112 +/- 8%) and end-systolic volume (53 +/- 15% to 63 +/- 22%) and decreased the ejection fraction (47 +/- 15% to 43 +/- 21%). The ejection fraction during exercise increased after nitroglycerin (50 +/- 22%) or nifedipine (54 +/- 21%) (p less than 0.05). In group II the ejection fraction was unchanged between rest and exercise with or without nitroglycerin or nifedipine. Thus combined radionuclide and ECG monitoring by VEST could detect changes in left ventricular function at rest and during exercise over a prolonged period and demonstrated that nitroglycerin and nifedipine improved cardiac function in the ischemic setting with an increased ejection fraction in the upright position.

Coronary Disease↗
PubMed1992

Regional myocardial perfusion and glucose metabolism in experimental left bundle branch block.

BACKGROUND: Several authors have reported cases in which 201Tl scintigraphy demonstrated perfusion abnormality in the septum of patients with left bundle branch block (LBBB) and normal coronary arteriogram. The mechanism of this abnormality, however, remains to be clarified. METHODS AND RESULTS: To determine whether LBBB itself induces abnormal myocardial perfusion and ischemia and to elucidate its mechanism, we used an in vivo animal model. LBBB was induced by right ventricular pacing in 17 open-chest dogs. We examined myocardial perfusion and glucose uptake using 201Tl and 18F-labeled 2-fluoro-2-deoxy-D-glucose. 201Tl activity in the septum was reduced to 74.7 +/- 14.5% of its maximal activity, and mean activity was 86.5 +/- 5.3% in the free wall (p less than 0.05). 18F activity in the septum was also reduced compared with that in the free wall (67.4 +/- 12.1% versus 88.0 +/- 5.2%, p less than 0.05). Regional myocardial blood flow was significantly reduced in the septum compared with the free wall, averaging 0.53 +/- 0.18 ml/min/g versus 0.84 +/- 0.14 ml/min/g, respectively (p less than 0.01). Systolic thickening in the septum was reduced from 1.36 +/- 0.20 to 0.98 +/- 0.04 (p less than 0.01) after the induction of LBBB, and the intramyocardial pressure in the septum in diastolic phase, in which the major flow of left anterior descending coronary artery (LAD) exists, increased from 26.6 +/- 10.5 to 57.8 +/- 22.2 mm Hg (p less than 0.02). Mean aortic pressure, LAD flow, and lactate extraction rate showed no significant change. CONCLUSIONS: LBBB itself may reduce myocardial perfusion and glucose uptake in the septum because of impaired systolic thickening and augmented intramyocardial pressure in the septum; however, this is not necessarily related to septal ischemia.

Animals↗
PubMed1992

Coronary risk factors used to predict coronary artery disease by logistic regression analysis.

Risk factor analysis in coronary artery disease was conducted in 303 patients who underwent coronary arteriography to identify associations between personal characteristics and the prevalence of coronary heart disease. Age, sex, obesity, smoking, alcohol intake, hypertension, diabetes mellitus, serum uric acid, total cholesterol, LDL- and HDL-cholesterol, triglyceride, and atherogenic indices were statistically analyzed. All 13 variables were first compared between patients with positive and negative ergonovine tests. Only total cholesterol was significantly different, while significant differences in age, sex, history of diabetes, total cholesterol, LDL- and HDL-cholesterol, triglyceride and atherosclerotic indices were observed between patients with and without organic coronary artery stenosis. A multivariate analysis was performed, and the resulting equation was tested using the remaining patients. Logistic analysis of all 13 variables identified 5 (age, sex, diabetes mellitus, LDL- and HDL-cholesterol) which accounted for the differences between patients with and without significant coronary artery disease and that were validated in the test group. The sensitivity for prediction of coronary artery disease was 75.8%, specificity 68.5%, and predictive accuracy 71.5% in the test group. Thus, risk factor analysis appears to be very valuable in screening subjects with high-risk organic coronary stenosis and in optimizing the preventive and therapeutic modalities, but not in predicting vasospastic subjects.

Cholesterol↗
PubMed1992

Effect of diltiazem on stunned myocardium evaluated with 99mTc-pyrophosphate imaging in canine heart.

The effect of diltiazem on stunned myocardium was evaluated by measuring the myocardial uptake of 99mTc-PYP (pyrophosphate) in open chest experiments with dogs. Myocardial stunning was induced by a 30 min ischemic occlusion of the anterior descending coronary artery. Regional wall motion was monitored by echocardiography of the epicardium for 2 h during reperfusion. After a 30 min occlusion of the coronary artery, it was reperfused and 99mTc-PYP was injected, followed by 201Tl 2 h later. The ischemic area was defined by Evans blue dye, and the infarct area by TTC staining. No dogs showed infarcts or 201Tl defects in this study group. Five dogs of the control-1 group (C1, ischemic area = 19.1 +/- 3.2%) showed decreased regional wall motion during occlusion (15.5 +/- 3.5% of control), and a slow recovery from depressed motion after 2 h of reperfusion (20.3 +/- 9.3%) with uptake ratio (compared to the non-ischemic area uptake) of 99mTc-PYP (4.96 +/- 2.28). In contrast, both groups with diltiazem infusion (20 micrograms/kg/min), started either 30 min before ischemia (D1 = 5 dogs) or just after reperfusion (D2 = 5 dogs), showed significantly better recovery after 2 h of reperfusion (D1:115.4 +/- 36.0%, D2:109.2 +/- 44.2%) than C1 (p less than 0.05), D1 and D2 groups also showed suppressed 99mTc-PYP uptake ratio (D1:1.06 +/- 0.33, D2:2.34 +/- 2.05, p less than 0.05 vs C1) in spite of comparable ischemic area. Four dogs with small ischemic area (C2:5.3 +/- 5.0%) did not show increased 99mTc-PYP uptake (1.15 +/- 0.35), and regional wall motion after 2 h of reperfusion was 96.1 +/- 24.1% of the control value (p less than 0.05 vs C1). Thus, diltiazem was effective in enhancing the suppression of 99mTc-PYP uptake in the stunned myocardium, and similar results were obtained for small ischemic areas. The protective effect of diltiazem appears to be strongly related to the mechanism of 99mTc-PYP uptake.

Animals↗
PubMed1992

Positron emission tomography--usefulness in assessing myocardial viability.

Positron emission tomography (PET) using N-13 ammonia and F-18 fluorodeoxyglucose (FDG) has been used to evaluate myocardial viability in comparison with thallium-201 single photon emission computed tomography (SPECT), and left ventricular wall motion in comparison with contrast ventriculography. Forty patients with anterior myocardial infarction underwent stress and delayed resting perfusion imaging using Tl-201 SPECT and ammonia PET, a glucose metabolism study using FDG PET, and wall motion assessment with left ventriculography. Out of a total of 600 segments of left ventricular imaging, SPECT demonstrated 197 fixed perfusion defects, 99 with redistribution on delayed imaging and 304 normal segments. Of 197 segments with fixed defects, 24 (12%) were normal and 71 (36%) ischemic according to PET criteria. Nineteen of 28 with infarction and all of 12 with non-Q wave infarction showed a viable myocardium. Left ventricular wall motion was significantly better in patients with normal PET findings compared with those with ischemia or scar on PET. Post-PTCA PET revealed improved ammonia PET in 6 of 11 patients but reduced FDG uptake was noted only in 3. These data suggests that Tl-201 SPECT significantly underestimates myocardial viability and that PET imaging is a promising tool for assessing the presence of salvaged myocardium.

Angioplasty, Balloon, Coronary↗
PubMed1992

Viable myocardium identified by reinjection thallium-201 imaging: comparison with regional wall motion and metabolic activity on FDG-PET.

Reinjection thallium-201 scans were performed in 68 patients with coronary artery disease after the routine stress-delayed scans for more accurate identification of new fill-in. Following the stress and 3 hour delayed thallium-201 SPECT scans, 40 MBq (1.1 mCi) was injected at rest, and 10 min later, the reinjection SPECT scan was obtained. To determine whether the reinjection method can aid in identifying ischemic but viable myocardium, the thallium-201 findings were compared with regional wall motion on radionuclide ventriculography in 61 patients and with metabolic activity on positron emission tomography (PET) using F-18 fluorodeoxyglucose (FDG) in 18 patients. The reinjection scan identified new fill-in which had not been shown on the stress-delayed scans in 6 of the 22 patients (27%) or in 29 of the 105 segments (28%). Regional wall motion was preserved more in the segments that exhibited new fill-in after reinjection (wall motion score = 1.64 +/- 1.29) than in those without new fill-in (score = 2.72 +/- 1.04) (p < 0.01). In the comparative study with FDG-PET, persistent FDG uptake was observed in all segments with new fill-in (20/20 segments: 100%); whereas, it was seen in only 7 of the 28 segments (25%) without new fill-in after reinjection (p < 0.05). We concluded that the segments having new fill-in after reinjection may represent ischemic but viable myocardium. Thus, the reinjection thallium-201 scan should be performed to identify ischemic myocardium which occasionally cannot be detected by the routine stress-delayed thallium-201 scans.

Adult↗
PubMed1992

Regional metabolic abnormality in relation to perfusion and wall motion in patients with myocardial infarction: assessment with emission tomography using an iodinated branched fatty acid analog.

The clinical usefulness of single-photon tomography using both a beta-methyl-branched fatty acid analog, 123I-15-(p-iodophenyl)-3-methyl pentadecanoic acid (BMIPP) and 201TI was assessed in 4 normal subjects and 28 patients with myocardial infarction. A homogeneous distribution of the tracer in the left ventricular myocardium was observed in each normal subject. BMIPP uptake was decreased compared to 201TI (discordant) in 17/28 patients (61%) and in 49/196 myocardial segments (25%). Such discordant BMIPP uptake was observed more often in areas of acute myocardial infarction (59% at less than or equal to 4 wk versus 31% at greater than 4 wk after onset) (p less than 0.01) and areas supplied with revascularized arteries (74% for revascularized versus 28% for nonrevascularized areas) (p less than 0.01). In addition, the discordant BMIPP uptake was seen more often in the segments exhibiting a wall motion score lower than the perfusion score (46%) in comparison to segments showing a similar decrease in both the wall motion and perfusion scores (12%) (p less than 0.01). Thus, BMIPP imaging may play a major role in increasing our understanding of the relationship between perfusion and wall motion, particularly in patients with acute myocardial infarction and those who received revascularization therapy.

Fatty Acids↗
PubMed1991

Analysis of limiting factors of DNA band separation by a DNA sequencer using fluorescence detection.

The factors affecting the electrophoretic separation of DNA bands in DNA base sequencing using fluorescence detection are analyzed. All the factors contributing to DNA band spacing and band width are evaluated; DNA diffusion and thermal effects on gels are the main considerations. The dependence of the gel's electrical resistivity on gel temperature and the variation of temperature over gel thickness are associated with a broadening of DNA band width. As a result of the analyses the maximum separable base number is represented as a function of various electrophoretic variables. The best separations are possible with an electric field strength corresponding to gel thickness. The maximum separable base number increases as the gel thickness decreases. It also increases as the migration distance increases, but it becomes saturated and has an upper limit when the migration distance is long. This upper limit increases as gel thickness decreases. DNA fragments with 600 and 601 bases can be completely separated from each other under optimum conditions for a 0.2 mm thick gel plate. Furthermore, using the band spacing information, under the same conditions, 750 bases could be assigned separately.

Base Sequence↗
PubMed1991

Metabolic reserve in normal myocardium assessed by positron emission tomography with C-11 palmitate.

Positron emission tomography (PET) with C-11 palmitate has been used in estimating the myocardial utilization of free fatty acid. To assess the metabolic reserve in normal subjects, a PET study was performed at control and during dobutamine infusion at 2 hour intervals in 5 normal subjects. Following monoexponential curve fitting of the time activity curve of the myocardium, the clearance half time (min) and residual fraction (%) were calculated as indices of beta-oxidation of free fatty acid. A significant increase in the heart rate and systolic blood pressure were observed during dobutamine infusion (65 +/- 5 vs 100 +/- 29 bpm, p less than 0.05 and 119 +/- 12 vs 144 +/- 16 mmHg, p less than 0.01, respectively). The clearance half time and the residual fraction were significantly decreased (23.4 +/- 2.6 vs 15.8 +/- 2.3 min and 67.0 +/- 2.5 vs 58.6 +/- 4.0%, P less than 0.05, each). When the left ventricular myocardium was divided into 4 segments, these indices were similar at control and uniformly decreased without regional differences during dobutamine infusion. These data suggest that beta-oxidation of free fatty acid may be uniformly increased in the left ventricular myocardium in relation to the increase in cardiac work in normal subjects. PET with C-11 palmitate at control and during dobutamine infusion is considered to be promising in assessing metabolic reserve in the myocardium.

Adult↗
PubMed1991

Real time automated simultaneous double-stranded DNA sequencing using two-color fluorophore labeling.

We determined the base sequences of both strands of duplex DNA simultaneously with an automated DNA sequencer. Primers for each strand were labeled with two different dyes and chain extension reactions for both strands produced four DNA families: "A", "C", "G", and "T". An image splitting-prism and band-pass filters were mounted on a real time DNA sequencer to detect fluorescences from the two different dyes separately. As a result, one thousand bases of a clone could be determined at the same time.

Automation↗
PubMed1991

Evaluation and clinical use of early washout ratio of thallium-201 in normal and ischemic myocardium after dipyridamole-induced vasodilation using ring-type emission computed tomography.

Using newly developed ring-type emission computed tomography (SPECT), we investigated the washout ratio (WR) of T1-201 in the myocardium quantitatively with fast dynamic scanning after infusion of dipyridamole (0.57 mg/kg), and assessed the feasibility of early WR as a marker to detect coronary artery disease. Twenty-three patients with and 8 patients without coronary artery disease had serial SPECT images obtained every 5 min for 45 min and at 180 min after dipyridamole and subsequent T1-201 injection. The best appropriate transaxial slice was selected for WR analysis. Most appropriate diagnostic time was 25 min after infusion of T1-201 (WR-25). Normal WR-25 was 7.1 +/- 4.0%, 5.9 +/- 3.1% and 7.1 +/- 2.3% at the septum, anterior and lateral wall, respectively. Sensitivity, specificity and accuracy to identify coronary stenosis greater than 50% with a usage of abnormal WR-25, defined as WR-25 less than (mean of normals--1SD) in each region of inferest of the left ventricle (LV), were 96%, 100% and 97%, respectively. These results were better than those achieved by visual analysis (sensitivity 78%, specificity 100%, accuracy 84%). In patients with single as well as multivessel disease, the regional accuracy in assessing stenosis of more than 50% in the left anterior descending artery (LAD) and left circumflex artery (LCX) by WR-25 was 94% and 83%, respectively, which was significantly better than using visual methods (LAD 72% and LCX 50%; p less than 0.05). Thus, evaluation of early washout ratios (WR-25) after dipyridamole injection is a valuable method to increase sensitivity in assessing regional myocardial perfusion abnormality and is helpful in detection of ischemic heart disease, even with multivessel disease.

Adult↗
PubMed1991

Effects of cardiac sympathetic nervous system on the stunned myocardium experimental study with 123I-metaiodobenzylguanidine.

123I-Metaiodobenzylguanidine (123I-MIBG) uptake in the stunned myocardium was investigated in open chest dogs. 123I-MIBG is a tracer taken up in presynaptic adrenergic vesicles and reflects the function of the myocardial sympathetic nervous system. This study revealed that in the stunned myocardium without infarct, 123I-MIBG uptake was normal up to 40 minutes of ischemia and that exogenous noradrenaline improved deteriorated regional wall motion with increased uptake of 123I-MIBG. However, uptake of 123I-MIBG per flow decreased with infarct in ischemic areas, and it showed a linear relation with regional wall motion. Thus, in the absence of infarction 123I-MIBG is a tracer to differentiate stunning from more severe ischemia with persistent wall motion abnormality. Normal uptake and storage of 123I-MIBG in the stunned condition suggests that catecholamine release or second effector mechanism may relate to the mechanism.

3-Iodobenzylguanidine↗
PubMed1991

[Comparison of 99mTc-hexakis 2-methoxy-2-isobutyl isonitrile and 201Tl SPECT imaging for evaluation of coronary artery disease].

To evaluate clinical value of 99mTc-hexakis 2-methoxy-2-isobutyl isonitrile (MIBI) imaging for assessing coronary artery disease (CAD), 99mTc-MIBI SPECT imaging at post-exercise and at rest was compared with 201Tl SPECT imaging at post-exercise and 3 hours redistribution in 27 patients suspected with CAD. The sensitivities for detecting CAD patients were 94% (17/18) by both studies. The specificities were 71% (5/7) by 99mTc-MIBI and 57% (4/7) by 201Tl (p = NS). The sensitivities for detecting stenosed coronary arteries (greater than or equal to 75% stenosis) were also similar between 99mTc-MIBI (78%) and 201Tl (74%) (p = NS). The similar specificity values were obtained by 99mTc-MIBI (84%) and by 201Tl (82%) (p = NS). The patterns of abnormality (normal, ischemia and scar) were similar between 99mTc-MIBI and 201Tl images in 22 of the 25 cases (88%) and 117 of the 125 segments (94%). However, these patterns were occasionally different particularly in patients who received PTCA or CABG. Thus, 99mTc-MIBI SPECT imaging seems to be as accurate as 201Tl SPECT imaging for the detecting and evaluating CAD.

Adult↗