PubMed Health⌕ Search

Biomedical subjects

T Tak

Publications and source records attributed to T Tak.

At least 37 records · Page 2Linked to original sources
PubMed1992

Detection of acute myocardial infarction with digital image processing of two-dimensional echocardiograms.

We have previously described the ability of a computer-based image digitizing system to assess early textural changes in acute canine myocardial infarction. To determine whether this technique could be applied to human beings, we studied 12 patients with a first acute transmural myocardial infarction and five normal subjects. Two-dimensional echocardiograms were performed on days 1 and 8 in normal subjects and on days 1 (day of admission), 2, 3, 5, and 14 in the patient population. All recording parameters on the echocardiography machine were kept identical for serial studies. The mean period between hospitalization and first echocardiogram was 11.1 hours (range 4 to 20 hours). End-diastolic frames from the two-dimensional echocardiographic images were digitized and displayed on a monitor. The mean pixel intensity (MPI) (+/- SD) in the region of asynergy (area of myocardial infarction) and a normal area were determined. In normal volunteers, no significant change in MPI was noted between anteroseptal and lateral areas on two separate two-dimensional echocardiographic studies, which were performed 7 days apart (anteroseptal: MPI, 21.6 +/- 1.1 vs 21.8 +/- 0.4, p = not significant) and (lateral: MPI, 21.5 +/- 1.2 vs 21.4 +/- 1.4, p = not significant). In patients with myocardial infarction, a significant increase in MPI was noted on the first day of myocardial infarction between normal and infarcted myocardium (20.4 +/- 2.0 vs 24.3 +/- 2.3, p less than 0.05) and progressively increased thereafter until day 14 (20.5 +/- 1.7 vs 31.9 +/- 3.7, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography↗
PubMed1992

Effect of loading conditions on Doppler-derived transmitral flow indices in normal subjects and patients with coronary artery disease.

The influence of alterations in preload and afterload on left ventricular diastolic filling using echocardiography was examined in nine normal volunteers (NLS) and nine patients (PTS) with coronary artery disease. The sequential interventions used were handgrip to increase afterload, nitroglycerin to decrease preload, and nifedipine to decrease afterload. Transmitral flow was measured using pulsed-Doppler echocardiography. Measurements were made pre- and post interventions. With increase in afterload using handgrip, the A and E wave velocities and the A/E ratio increased in both groups: 0.62 +/- 0.14 versus 0.86 +/- 0.17 in NLS; 0.75 +/- 0.45 versus 0.84 +/- 0.50 in PTS (P less than 0.05). Following administration of nitroglycerin to reduce preload, the A wave velocities increased, the E wave velocity decreased in both groups, and the A/E ratio increased 0.57 +/- 0.11 versus 0.67 +/- 0.13 in NLS; 0.78 +/- 0.40 versus 0.91 +/- 0.44 in PTS (P less than 0.05). Following use of nifedipine, the A and E wave velocities decreased in both groups with an increase in the A/E ratio in the patient group 0.83 +/- 0.13 versus 0.89 +/- 0.11 (P = NS). Thus, both normal subjects and patients with coronary artery disease had similar changes in Doppler-derived indices of left ventricular filling following interventions that changed left ventricular preload and afterload.

Adult↗
PubMed1991

A novel highly unsaturated fatty acid moiety of lipo-oligosaccharide signals determines host specificity of Rhizobium.

In Rhizobium leguminosarum biovar viciae, the nodABC and nodFEL operons are involved in the production of lipo-oligosaccharide signals which mediate host specificity. The structure of these metabolites and those produced in nod mutants links the nodE and nodL genes to specific chemical features of the signal molecules. A nodE-determined, highly unsaturated fatty acid and a nodL-determined O-acetyl substituent are essential for the ability of the signals to induce nodule meristems on the host plant Vicia sativa.

Fabaceae↗
PubMed1991

Normalization of Doppler indices of diastolic dysfunction during pacing is a sign of ischemic mitral regurgitation.

Twenty-three patients with angina who were undergoing diagnostic cardiac catheterization underwent cardiac pacing with simultaneous hemodynamic and Doppler echocardiographic evaluation to assess the effects of pacing-induced ischemic on mitral valve velocity. Seventeen patients had significant coronary artery disease, and six patients had normal coronary arteries. Doppler and hemodynamic measurements were performed at rest and immediately after pacing was discontinued to 91% +/- 7% of maximal predicted heart rate. Seven patients experienced new or significant increases in severity of mitral regurgitation after pacing as revealed by Doppler examination. This group had a significant increase (p = 0.007) in early but not in late peak filling velocities immediately after pacing was discontinued, with a resultant decrease in late to early ratios, which decreased from 1.01% +/- 0.12 to 0.70% +/- 0.19 (p = 0.006). Left ventricular end-diastolic pressure increased significantly from 16.7% +/- 6.8 mm Hg to 29.4% +/- 5.3 mm Hg after cardiac pacing (p less than 0.001). Patients with coronary disease who did not develop mitral regurgitation also had significant increases in left ventricular end-diastolic pressure from 18.7% +/- 5.8 mm Hg to 24.3% +/- 8.6 mm Hg (p less than 0.05). There were no changes in late or early wave amplitude, late to early ratio, or other Doppler measurements in any of the other groups. We conclude that mitral regurgitation caused by pacing-induced myocardial ischemia normalizes Doppler indices of mitral inflow, which in turn, may mask persistent or worsened left ventricular diastolic dysfunction.

Adult↗
PubMed1991

Cardiac MRI cine and color Doppler in valvular disease: correlative imaging.

Cardiac cine field echo MRI and color Doppler were performed in 13 patients with aortic regurgitation (n = 4) or multiple valvular diseases (n = 9). The size, shape, and direction of regurgitation jets correlated well. Color Doppler was better able to follow flow jets in oblique planes. Cine MRI was better able to evaluate patients with marked cardiac dilatation.

Aortic Valve Insufficiency↗
PubMed1990

Accuracy of Doppler ultrasound in evaluating changes of left ventricular diastolic properties.

In order to evaluate the effect of an increase in preload caused by contrast medium (Renografin-75) on Doppler echocardiographic indices of left ventricular diastolic properties, left ventricular pressure using a catheter tip micromanometer and pulsed-Doppler measurement of transmitral flow signals were measured simultaneously in 15 patients with coronary artery disease pre- and post-left ventricular angiography. After left ventricular angiography, changes in indices determined from left ventricular pressure were significant: left ventricular end-diastolic pressure increased from 17 +/- 2 mmHg to 24 +/- 2 mmHg (mean +/- SE) (P less than 0.001), maximum -dP/dt increased from 1,129 +/- 63 to 1,307 +/- 90 mmHg/sec (P less than 0.005), and time constant decreased from 73 +/- 2 to 67 +/- 1 msec (P less than 0.01). Changes in Doppler-derived indices were also significant: A/E ratio decreased from 0.99 +/- 0.08 to 0.81 +/- 0.07 (P less than 0.01), peak velocity of early diastolic filling increased from 0.61 +/- 0.03 to 0.79 +/- 0.03 M/sec (P less than 0.01), and deceleration rate increased from 3.1 +/- 0.2 to 4.6 +/- 0.2 M/sec 2 (P less than 0.01). Changes in Doppler echocardiographic indices (DR, acceleration half time, deceleration half time, and A/E ratio) were accompanied by changes in time constant and maximum -dP/dt after left ventricular angiography. However, the correlations between changes in hemodynamic indices and changes in Doppler echocardiographic indices were poor (r = 0.06 to 0.67).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

A biovar-specific signal of Rhizobium leguminosarum bv. viciae induces increased nodulation gene-inducing activity in root exudate of Vicia sativa subsp. nigra.

Flavonoids in root exudate of leguminous plants activate the transcription of Rhizobium genes involved in the formation of root nodules (nod genes). We report that inoculation with the homologous symbiont R. leguminosarum bv. viciae results in an increased nod gene-inducing activity (Ini) in root exudate of V. sativa subsp. nigra, whereas inoculation with heterologous Rhizobium strains results in exudates with nod gene-inducing activity comparable to that of uninfected plants. Ini can be demonstrated by using either of the isogenic indicator strains containing an inducible nod promoter fused to the Escherichia coli lacZ reporter gene and the regulatory nodD gene of R. leguminosarum bv. viciae, R. leguminosarum bv. trifolii, or R. meliloti. The presence of genes nodDABCEL of R. leguminosarum bv. viciae appeared to be essential for induction of Ini. Mutation of the genes nodI and nodJ causes a delay of Ini, whereas gene nodF appears to be required for both the timely appearance and the maximum level of Ini activity. The nodE gene is responsible for the biovar specificity of induction of Ini by Rhizobium spp. Ini is caused by a soluble heat-stable factor of rhizobial origin. This Rhizobium-produced Ini factor has an apparent molecular weight between 1,000 and 10,000 and does not originate from flavonoid precursors.

Cells, Cultured↗
PubMed1989

Symbiotic properties of rhizobia containing a flavonoid-independent hybrid nodD product.

A hybrid nodD gene consisting of 75% of the nodD1 gene of Rhizobium meliloti at the 5' end and 27% of the nodD gene of Rhizobium trifolii at the 3' end activates the six tested inducible nod promoters of Rhizobium leguminosarum, R. trifolii, or R. meliloti to maximal levels, even in the absence of flavonoids. In strains containing such a constitutive activating nodD gene, transcription of nod genes started at the same site as in flavonoid-induced strains containing a wild-type nodD gene. In contrast to heterologous wild-type nodD products, the constitutive activating nodD gene does not cause a limitation of the host range. Furthermore, R. leguminosarum, R. trifolii, and R. meliloti strains containing the constitutive activating nodD gene induce (pseudo) nodules on tropical leguminous plants. Comparison of the symbiotic properties of rhizobia containing the constitutive nodD hybrid gene with those of rhizobia containing various wild-type nodD genes indicates that the activation of the nodD product by flavonoids is of crucial importance during the process of infection thread formation and, surprisingly, also during nitrogen fixation.

Bacterial Proteins↗
PubMed1989

Ultrasonic tissue characterization of acute canine myocardial infarction.

This study assessed changes in left ventricular texture on two-dimensional (2-D) echocardiography after experimental myocardial infarction. In 13 dogs, the left anterior descending coronary artery (LAD) was occluded for 3 h, followed by 1 h of reperfusion and sacrifice. Two-dimensional echocardiography was performed pre-LAD occlusion, 3 h post occlusion and 1 h after reperfusion by placing a 5 MHz transducer on the chest wall. After sacrifice, triphenyltetrazolium chloride staining was performed on 1 cm thick left ventricular cross-sectional slices. Five dogs served as controls (shams). Two-dimensional echocardiograms were digitized and in the region of left ventricular asynergy (area of myocardial infarction), and adjacent normal area, the mean pixel intensities (+/- SD) were calculated. There was no significant change in the mean pixel intensity from 0 through 4 h in the lateral (22.8 +/- 1.3 and 23.4 +/- 1.8) and anteroseptal (23.2 +/- 1.9 and 22.6 +/- 1.9) regions in sham operated dogs. In dogs undergoing LAD occlusion, the mean pixel intensity from the pre- to post occlusion period showed no significant change in the lateral (normal) area, 24.4 +/- 2.7 versus 24.7 +/- 2.9. In the area of wall motion abnormality (area of myocardial infarction) the mean pixel intensity increased from 25.4 +/- 2.7 to 33.7 +/- 4.5, P less than 0.01. There was no significant change in the mean pixel intensity between the 3 h post occlusion and post reperfusion period in either the lateral (normal) or anteroseptal areas of the left ventricle. The area of left ventricular asynergy corresponded to the area of myocardial infarction on triphenyltetrazolium chloride stain.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1989

Platelet activation in patients with mitral valve prolapse.

An increased frequency of thromboembolic events in patients with mitral valve prolapse has been demonstrated. It has been suggested that this association may be related to increased systemic platelet activity. Beta-thromboglobulin (BTG) is a platelet specific protein secreted during the platelet release reaction, with BTG levels reflecting ongoing platelet activation. Plasma BTG levels were measured in 14 normal volunteers, 23 patients with mitral valve prolapse and nonthickened mitral leaflets (group 1) and 13 patients with mitral valve prolapse and thickened mitral leaflets (group 2). The BTG level was 8.1 +/- 4.6 ng/mL (mean +/- SD) in normal subjects, 9.6 +/- 5.5 ng/mL in the nonthickened mitral valve prolapse group and 10.0 +/- 5.7 ng/mL in thickened mitral valve prolapse group. There was no significant difference in the BTG levels between groups. Five patients with multiple valvular prolapse did not show elevation of BTG levels. The present study did not demonstrate increased BTG levels in neurologically asymptomatic mitral valve prolapse patients.

Adult↗
PubMed1988

Comparison of Doppler echocardiographic and hemodynamic indexes of left ventricular diastolic properties in coronary artery disease.

Transmitral flow velocity was measured by Doppler echocardiography in 15 patients with coronary artery disease simultaneously with high-fidelity recording of left ventricular pressure. Doppler echocardiographic recordings were also performed in 14 age- and heart rate-matched normal subjects. Statistically significant differences (p less than 0.05) in acceleration half-time (55.3 +/- 8.2 vs 70.4 +/- 14.9 ms), deceleration half-time (83.1 +/- 17.9 vs 109.5 +/- 18.1 ms), deceleration rate (4.9 +/- 0.9 vs 3.1 +/- 0.9 m/s2), peak velocity of early diastolic left ventricular inflow (E wave) (0.78 +/- 0.13 vs 0.61 +/- 0.13 m/s) and A/E ratio (0.74 +/- 0.20 vs 0.98 +/- 0.31) between normal subjects and patients were noted. There was no significant difference in peak velocity of atrial systolic flow (A wave) between normal subjects and patients. Correlation between transmitral flow indexes and hemodynamic indexes of left ventricular diastolic properties were poor, with r values ranging from 0.02 to 0.65. Significant correlations between deceleration rate versus maximal isovolumic left ventricular pressure decrease (maximum -dP/dt) and A wave versus maximum -dP/dt (p less than 0.05) were found (0.53 and 0.65, respectively). Deceleration rate was the most sensitive index of isovolumic relaxation assessed by hemodynamic methods, whereas the A/E ratio was a poor indicator of hemodynamic measurements of isovolumic relaxation. An abnormal deceleration rate had 100% specificity for detecting abnormal maximum -dP/dt, while abnormal acceleration half-time, deceleration half-time and A/E ratio had 80% specificity for detecting abnormal time constant. The deceleration rate, acceleration half-time, deceleration half-time and A/E ratio had a predictive value of 60 to 100% for the detection of abnormal maximum -dP/dt and time constant.

Adult↗
PubMed1988

Value of digital image processing of two-dimensional echocardiograms in differentiating active from chronic vegetations of infective endocarditis.

The ability of a computer-based image digitizing system to differentiate "active" from "chronic" valvular vegetations was evaluated. Twenty-two patients with newly diagnosed infective endocarditis were studied prospectively by serial two-dimensional echocardiograms. Two comparable images (active and chronic) from the same patient taken several weeks apart (range, 4-17 weeks) after initiation of therapy were obtained at end diastole with identical gain settings. The images were digitized, magnified, and displayed on a high-resolution color monitor. The mean pixel intensity of the valvular vegetation in the active stage was 20.6 +/- 3.6 (mean +/- SD), which increased to 34.4 +/- 4.3 in the chronic stage (p less than 0.01). Because there was some overlap of values, an additional standardization procedure was used in the last eight patients. In these eight patients, the mean pixel intensity of the vegetations in the active stage was 17.5 +/- 1.1, and it increased at 4 weeks to 25.0 +/- 1.2 (p less than 0.05) and further increased in the chronic stage to 33.6 +/- 3.1 (p less than 0.05). There was no overlap of values between the active and chronic stages. Three clinical states are of particular interest: 1) The mean pixel intensity of the vegetations remained unchanged (23 vs. 24) in one patient who did not respond to antibiotic therapy. 2) The mean pixel intensity of the vegetations fell from 35 to 24 when one patient developed reinfection of the same valve, and with treatment, mean pixel intensity once again increased to 34. 3) The mean pixel intensity of the vegetations in five patients with culture negative infective endocarditis was low (21.6 +/- 1.9) and increased (33.6 +/- 6.0, p less than 0.05) during the chronic stage. The mean vegetation size was 0.73 +/- 0.30 cm2 in the active stage and decreased to 0.56 +/- 0.24 cm2 (p less than 0.05) in the chronic stage; however, in six of 22 patients (27%), vegetation size did not decrease with clinical cure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

2-D echocardiographic analysis of interventricular septal motion: concept of an anterior and posterior part to the septum.

2-D echocardiography was performed in 50 patients with transmural anteroseptal (group 1) or inferior myocardial infarction (group 2). Twenty-four patients with myocardial infarction had diagnostic coronary arteriography. Twenty-five normal subjects served as controls. The interventricular septum was subdivided into proximal and distal halves. In the parasternal long axis view (PSLAX), interventricular septum asynergy was seen in 96% of patients of group 1 and none in group 2. In the apical four chamber view (A4C), the proximal interventricular septum was abnormal in 48% of group 2 patients, but only one patient in group 1. The distal half of the interventricular septum in the A4C was abnormal in 48% of patients in group 1 and 12% in group 2. Complete asynergy of the interventricular septum in the PSLAX view was seen in 80% of patients with proximal stenosis in the left anterior descending artery (LAD) in association with anteroseptal myocardial infarction. Distal asynergy in this view was noted in all patients with a stenosis distal to the first septal perforator. In conclusion, the PSLAX visualizes the anterior interventricular septum and demonstrates wall motion abnormalities associated with anteroseptal infarction; complete asynergy of the interventricular septum in the PSLAX view suggests an anteroseptal infarction with proximal LAD stenosis; the A4C visualizes the posterior interventricular septum and proximal wall motion abnormalities are seen in inferior infarction while distal septal wall motion abnormalities occur in anteroseptal or inferior infarction.

Adult↗
PubMed1987

Flavonoids induce Rhizobium leguminosarum to produce nodDABC gene-related factors that cause thick, short roots and root hair responses on common vetch.

Rhizobium leguminosarum produced a factor(s) that caused thick, short roots (Tsr phenotype) as well as root hair induction (Hai phenotype) and deformation (Had phenotype) in Vicia sativa plants upon incubation with root exudate or with one of the nod gene inducers naringenin or apigenin; this was a nodDABC gene-dependent process. Detection of the Hai and Had phenotypes was much more sensitive than that of the Tsr phenotype.

Fabaceae↗
PubMed1986

Ambulatory ECG recording during competitive parachute jumping in apparently healthy young men: more evidence for intermittent vagal dominance during enhanced sympathetic activity.

Using two-channel 24-hour ambulatory ECG recording we studied seven healthy young men during one day of parachute jumping competition (day 1), as compared to one control day (day 2). A symptom limited exercise test was also performed on day 2. Maximal heart rates attained during exercise testing were of the same order as during parachute jumping. In the phases just prior to 'exit', short periods of striking sinus arrhythmia with slow atrial rhythm were present in 3 subjects. Only one of these had slow atrial rhythm during the control day. Atrial and ventricular premature complexes, when present, disappeared with higher heart rates under all circumstances. No AV conduction disturbances were found.

Adult↗