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Biomedical subjects

A Lahiri

Publications and source records attributed to A Lahiri.

At least 109 records · Page 6Linked to original sources
PubMed1994

Anti-ischaemic and haemodynamic effects of elgodipine, a potent new generation calcium antagonist, in chronic stable angina.

The effects of oral elgodipine, a new dihydropyridine calcium antagonist on ischaemia and left ventricular function were assessed by a single blind placebo controlled study in 12 patients with chronic stable angina. Graded treadmill exercise and echocardiography/Doppler were performed before and 90 min after single oral doses of elgodipine of 20 mg, 40 mg and 60 mg, or placebo, given at weekly intervals. Elgodipine significantly increased exercise time by 1.1, 2.0 and 2.4 min, (P < 0.001 in each case) and time to onset of angina by 1.1 (P < 0.01), 1.9 (P < 0.001) and 2.6 min (P < 0.001) with increasing doses of the drug. Angina was abolished in 50% of patients with significant improvement in ST depression at peak exercise (P < 0.001) with the 60 mg dose. Blood pressure fell significantly at rest and peak exercise with a corresponding significant increase in heart rate. Ejection fraction was increased by 7.8% (P < 0.001) and 8.4% (P < 0.001) as was the stroke volume by 9.3 ml (P < 0.001) and 12.5 ml (P < 0.001) at 40 mg and 60 mg respectively. Peak mitral A to E velocity ratio and total peripheral resistance decreased significantly in a dose related linear trend. Only minor side effects were noted and no patient required withdrawal from the study. The results demonstrate that oral elgodipine is a potent anti-ischaemic agent. An improvement in the echocardiographic parameters of left ventricular systolic and diastolic function was also seen.

Aged↗
PubMed1994

Comparison of radionuclide ventriculography and 2D echocardiography for the measurement of left ventricular ejection fraction following acute myocardial infarction.

To compare the measurement of left ventricular ejection fraction obtained by two-dimensional echocardiography and by radionuclide ventriculography in patients following acute myocardial infarction, 49 consecutive patients with acute myocardial infarction underwent echocardiography and radionuclide ventriculography on the same day, pre-discharge. Left ventricular ejection fraction was assessed by two blinded observers for each method and reproducibility was also assessed for each technique. The limits of agreement for the differences in ejection fraction (%) between the two methods was--11.4, 12.2; the mean difference 0.4 was not significantly different from zero. The limits of agreement for the intra- and inter-observer differences in ejection fraction by radionuclide ventriculography were--9.4, 7.6 and -8.6, 11.0, respectively; the mean differences--0.9 and 1.2 were not significantly different from zero. The limits of agreement for the intra- and inter-observer differences by echocardiography were--5.8, 6.6 and--8.9, 9.5 respectively; the mean differences 0.4 and 0.3 were not significantly different from zero. Thus, two-dimensional echocardiography compares well with radionuclide ventriculography for the assessment of ejection fraction without the disadvantage of radiation.

Adult↗
PubMed1994

Myocardial imaging with technetium-99m-tetrofosmin: comparison of one-day and two-day protocols.

UNLABELLED: There is no evidence of myocardial redistribution after tetrofosmin injection, therefore, two separate injections are needed to differentiate scar from ischemia with this tracer. The injections can be given on the same day (one-day protocol) or on separate days (two-day protocol). As part of a Phase II clinical study, a one-day protocol was compared with a two-day protocol. METHODS: Fifty-five patients with suspected coronary artery disease were studied according to the following protocol: on the first day at rest, anterior, left lateral, left anterior oblique 40 degrees and 70 degrees images were acquired 30 min after injection of 8 mCi of tetrofosmin for 5 min each. Two days later, exercise and rest images were acquired on the same day. At peak exercise, 8 mCi of tetrofosmin were injected and 30 min later the same four standard planar images were recorded as on Day one. Four hours after the exercise injection, 24 mCi of tetrofosmin were injected at rest and imaging was repeated 30 min later. Qualitative comparisons between the one- and two-day protocols were performed in 50 patients in whom all data were available following blinded evaluation of images by three readers. RESULTS: All three readers reported identical results for the 26 patients. A difference in extent or location between the observers was found in seven patients, differences between normal and abnormal in eight patients, while discrepancies between ischemia and necrosis were noted in four patients. In five patients, an ischemic area was found according to the one-day protocol, but according to the data of the two-day protocol, this area was judged to be necrotic. One observer reported the opposite in one patient. These discrepancies between the reversibility of defects were restricted to the inferior wall. Comparison with 201Tl data showed no systematic pattern of variation. CONCLUSION: Tetrofosmin can be used in a one-day protocol. However, in planar imaging, the inferior wall should be reported with caution.

Coronary Disease↗
PubMed1994

Technetium-99m-tetrofosmin myocardial imaging: a comparison with thallium-201 and angiography.

UNLABELLED: Images recorded after intravenous administration of 99mTc-tetrofosmin were compared to those obtained with 201Tl in a series of 40 patients with angiographically documented coronary artery disease. These patients were part of a Phase II tetrofosmin study and presented anamnestic or laboratory evidence suggestive of ischemic heart disease. METHODS: Thirty-seven patients had one or more coronary obstructions greater or equal to 70% of luminal diameter. Three patients studied after bypass surgery or angioplasty had patent grafts, absence of disease progression or no significant restenosis. Twenty-six patients had evidence of previous myocardial infarction. All images were processed into a common display format by a core laboratory. They were identified by code and read by concensus of four investigators. Each segment was classified as normal or abnormal and these readings were combined and categorized into normal, reversible, fixed or mixed regional defects. RESULTS: There was good segmental correspondence between thallium and tetrofosmin (kappa values ranged from 0.43 to 1.00). The ability of thallium and tetrofosmin to recognize and localize myocardial infarction was excellent, since corresponding abnormalities were present in respectively 24 and 25 of the 26 patients with previous myocardial infarction. Abnormalities in noninfarcted territories were recognized with both tracers in 16 of 28 patients presenting with coronary lesions involving vessels unrelated to the infarct. CONCLUSION: In comparison to rest tetrofosmin, thallium redistribution shows more reversibility in areas with myocardial infarction but less reversibility in areas of myocardial ischemia. Current Phase II results suggest that tetrofosmin is a sensitive and reliable tracer for detecting myocardial infarction and ischemia. Results should be confirmed in a larger group of patients.

Aged↗
PubMed1993

Comparison of myocardial perfusion imaging with technetium-99m tetrofosmin versus thallium-201 in coronary artery disease.

Technetium-99m (Tc-99m) tetrofosmin, a new myocardial perfusion imaging agent, was evaluated at exercise and rest in 50 patients with documented coronary artery disease to determine myocardial kinetics, redistribution and ideal imaging time. Planar imaging was performed at 5, 30, 60, 90, 120 and 240 minutes after an injection of Tc-99m tetrofosmin (8 to 10 mCi) at peak graded ergometric exercise. Reinjection (24 to 30 mCi) was performed at rest, 4 hours after the stress injection and also on a separate day, and imaging was repeated. All patients underwent thallium-201 (Tl-201) exercise and redistribution (4-hour) imaging. Perfusion defect to normal, and heart to lung ratios were calculated for exercise Tc-99m tetrofosmin images at each time point. The mean +/- SD defect to normal ratios were 0.75 +/- 0.10, 0.75 +/- 0.10, 0.74 +/- 0.09, 0.73 +/- 0.10, 0.73 +/- 0.10 and 0.72 +/- 0.10 at 5, 30, 60, 90, 120 and 240 minutes, respectively (p = NS), suggesting absence of redistribution. There was a significant increase in lung uptake of Tl-201 during exercise (p < 0.05), but not with Tc-99m tetrofosmin (p = NS). Washout of Tc-99m tetrofosmin was calculated in a subset of patients (n = 23). Rapid background clearance enabled postexercise diagnostic imaging as early as 5 minutes after injection. Myocardial retention curves after rest injection suggested that the optimal time for imaging was approximately 30 minutes later. Slow myocardial washout (4%/hour after exercise and 0.6%/hour after rest injection) enabled diagnostic images to be obtained up to 4 hours after each study.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Prognostic value of noninvasive cardiac tests in the assessment of patients with peripheral vascular disease.

Two hundred thirty-six patients with peripheral vascular disease were prospectively studied to assess whether noninvasive cardiac investigations could predict prognosis better than simple clinical assessment. Clinical history, examination and resting electrocardiography were considered in all patients; exercise electrocardiography, Holter monitoring, radionuclide ventriculography and dipyridamole thallium imaging were performed in a subgroup of 168 patients. Follow-up for 6 to 30 months revealed major cardiac events in 21 patients. Cox survival analysis showed that clinical evidence of prior coronary artery disease was the best variable from clinical assessment that predicted cardiac events, with no other clinical variable adding to the statistical model. When variables from noninvasive cardiac assessment were added to the model, which included clinical evidence of coronary artery disease, dipyridamole thallium heart:lung ratio and left ventricular ejection fraction added significantly and incrementally to the prediction of cardiac events. Results of exercise electrocardiography or Holter monitoring did not add significantly. It is concluded that high lung uptake of thallium during dipyridamole stress, and impaired left ventricular ejection fraction help to identify patients with peripheral vascular disease who are at high cardiac risk, and should therefore be used for selecting subsequent cardiovascular medical, surgical and anesthetic management.

Aged↗
PubMed1993

Giant collagen plaques in Creutzfeld-Jakob disease. Report of two cases with ultrastructural studies.

We report two cases of Creutzfeld-Jakob disease with clusters of giant collagen fibers. To our knowledge, these abnormally large collagen fibers have never been described in patients with degenerative diseases of the central nervous system. The significance of the formation of such plaque-like large collagen fibers has as yet not been elucidated. It is felt that these represent a product of the degenerative process.

Adult↗
PubMed1993

99mTc-antimyosin antibody imaging for the detection of acute myocardial infarction in human beings.

111In-antimyosin imaging is a highly sensitive and specific technique for the detection of myocardial necrosis. Two new methods of labeling antimyosin with 99mTc have been developed, and were compared with the standard 111In-antimyosin imaging technique in 29 patients with acute myocardial infarction. Fourteen patients (group I) received directly labeled 99mTc-antimyosin, and 15 (group II) were given RP-1 conjugated 99mTc-antimyosin. 99mTc-antimyosin imaging was performed at 6, 12, and 24 hours, and 111In-antimyosin imaging was done at 24 and 48 hours following injection. The images were interpreted by three blinded observers. In group I, 99mTc-antimyosin uptake could be detected in 3, 6, and 12 cases at 6, 12, and 24 hours, respectively, compared with only 8 cases at 24 hours with 111In-antimyosin. At 48 hours all patients showed 111In-antimyosin uptake. In group II, 99mTc-antimyosin uptake could be detected in 2, 3, and 6 cases at 6, 12, and 24 hours, respectively, compared with 8 and 12 cases at 24 and 48 hours, respectively, with 111In-antimyosin. Gated blood pool studies could be obtained in all patients following 99mTc-antimyosin injection and could be used to identify regional wall motion abnormalities. The plasma half-lives of 99mTc-antimyosin in group I and group II were 2.67 +/- 0.3 hours and 4.23 +/- 0.3 hours, respectively, and the plasma half-life of 111In-antimyosin was 6.3 +/- 0.4 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

A multicentre, double-blind, placebo-controlled trial of quinapril in mild, chronic heart failure.

Angiotensin converting enzyme (ACE) inhibitors are of proven value in patients with severe chronic heart failure (CHF). Studies of the effects of ACE inhibitors on exercise capacity and quality of life in mild CHF have produced conflicting results. We have studied the effects of quinapril, a new ACE inhibitor with a relatively short plasma half-life, in mild CHF. Once daily (o.d.) dosing was compared with twice daily (b.i.d.) dosing in a three-way cross-over, double-blind, placebo-controlled trial. Thirty-two patients (two female), mean age 59 (range 32-76) years were enrolled in three cardiology centres in the U.K. in 29 patients, and non-ischaemic in three. The mean (range) radionuclide ejection fraction was 20.4% (8%-47%). Following full familiarization with the protocol, the treadmill exercise time (modified Bruce protocol) was determined for each patient during a placebo run-in phase, and at the end of each of three 8-week double-blind treatment phases with quinapril o.d., quinapril b.i.d. (maximal total daily dose 20 mg) and placebo. Three patients were withdrawn due to adverse events while receiving quinapril (unstable angina, exacerbation of CHF and arrhythmia); there were no deaths and no patient was withdrawn due to hypotension. Mean exercise time (the primary end-point) was 65 s and 53 s longer in patients receiving quinapril o.d. and b.i.d. respectively compared to placebo (both P < 0.01, ANOVA). There was no significant period effect during the trial and no significant difference between the two quinapril dosing regimens. Quinapril had no significant effect on secondary end-points including ejection fraction, functional class and quality of life.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

A double-blind comparison of a beta-blocker and a potassium channel opener in exercise induced angina.

This randomized, double-blind, parallel study compared the anti-anginal effects of nicorandil and atenolol in 37 patients with exercise-induced angina pectoris. At the end of a single-blind placebo period, patients were randomized and received either atenolol 50 mg o.d. or nicorandil 10 mg b.d. for 3 weeks. On the third week, the dosage was increased (nicorandil 20 mg b.d. or atenolol 100 mg o.d.) for the final 3-week period. Treadmill exercise tolerance tests were performed immediately before and 2 h after dosing at the end of the placebo period, and at the end of the third and sixth week of active treatment. Demographic characteristics and exercise performance with placebo were comparable between both treatment groups, and at the end of the treatment periods a significant improvement in exercise time was observed: an increase in the time to peak exercise of 1.33 +/- 0.29 min (mean +/- standard error of the mean) in atenolol-treated patients (P < 0.001), and of 1.47 +/- 0.40 min (P < 0.005) in nicorandil-treated patients. While the anti-anginal activity of the two drugs was comparable, their effects on the rate-pressure product heart rate x systolic blood pressure were clearly different; atenolol induced a decrease at peak exercise, but this parameter was not changed or was slightly increased with nicorandil. One patient with severe three-vessel disease died suddenly after 3 days of treatment with nicorandil 10 mg twice daily. The most frequent adverse effect in both groups was headache, which led to discontinuation of one patient in the atenolol group and of five patients in the nicorandil group.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Potent hemodynamic effects of bimakalim, a new potassium channel opener, in humans.

The cardiac hemodynamic effects of bimakalim, a new potassium channel opener, were evaluated in 12 normal volunteers by echocardiography (ECHO)/Doppler in a placebo-controlled, randomized double-blind, cross-over, dose-ranging study. A single oral dose (0.25-1 mg) was given at weekly intervals. Hemodynamic measurements were made at 0, 90, 120, and 240 min after drug intake and ECHO/Doppler was performed at 0 and 90 min. Reproducibility of the ECHO/Doppler study was assessed by comparing predose baseline values of the four different phases of treatment (placebo and 0.25, 0.5, and 1 mg) by analysis of variance (ANOVA), which showed no significant differences for left ventricular ejection fraction (LVEF). Doppler-derived stroke volume (SV), total peripheral resistance (TPR), and peak mitral early to late velocity ratio (PEV/PAV). ANOVA showed significant increases in LVEF (p = 0.0003) and SV (p = 0.03), however, and decreases in TPR (p = 0.002) and PEV/PAV (p = 0.005) after bimakalim treatment. Heart rate (HR) showed a dose-dependent increase, but systolic and diastolic blood pressure (SBP, DBP) did not change with bimakalim. Despite vasodilatory headaches, none of the volunteers discontinued the study. Bimakalim appears to be a potent vasodilating drug that may have an important role in management of patients with compromised LV function.

Administration, Oral↗
PubMed1993

Rate of change of left ventricular ejection fraction during exercise is superior to the peak ejection fraction for predicting functionally significant coronary artery disease.

OBJECTIVE: To detect and characterise rapid temporal changes in the left ventricular response to exercise in patients with ischaemic heart disease and to relate these changes to the functional severity of coronary artery disease. BACKGROUND: The gamma camera does not allow the detection of rapid changes in cardiac function during exercise radionuclide ventriculography, the monitoring of which may improve the assessment of patients with ischaemic heart disease. METHODS: A miniature nuclear probe (Cardioscint) was used to monitor continuously left ventricular function during exercise in 31 patients who had coronary angiography for suspected coronary artery disease. A coronary angiographic jeopardy score was calculated for each patient. RESULTS: The coronary jeopardy score ranged from 0 to 12 (median 4). Ejection fraction fell significantly during exercise from 46% to 34%. Patients were divided into two groups based on the response of their ejection fraction to exercise. In 14 patients (group I), the peak change in ejection fraction coincided with the end of exercise, whereas in the other 17 patients (group II) the peak change in ejection fraction occurred before the end of exercise, resulting in a brief plateau. The peak change in ejection fraction and the time to its occurrence were independent predictors of coronary jeopardy (r = -0.59, p < 0.001 for peak change and r = -0.69, p < 0.001 for time to that change). The rate of change in ejection fraction was the strongest predictor of coronary jeopardy (r = -0.81, p < 0.001). In group I the peak change in ejection fraction was a poor predictor severity of coronary disease (r = -0.28, NS), whereas the time to peak and the rate of change in ejection fraction were good predictors (r = -0.65 and r = -0.73, p < 0.01). In group II the peak, the time to the peak, and the rate of change in ejection fraction were good predictors of coronary jeopardy (r = -0.75, r = -0.61, and r = -0.83, p < 0.01). CONCLUSION: The rate of change of ejection fraction during exercise can be assessed by continuous monitoring of left ventricular function with the nuclear probe, and is the best predictor of functionally significant coronary artery disease.

Adult↗
PubMed1993

Fronted velars, palatalized velars, and palatals.

Articulatory and acoustic characteristics of various stop consonants in Czech, Hungarian, English, and Russian are compared: velars before back and before front vowels, palatalized velars, and palatals. The articulatory data consist of X-ray tracings and palatograms taken from the literature. The acoustic data consist of LPC spectra of brief intervals at stop release and at vowel onset. These data indicate that all of these consonant types are distinct. Contextual fronting of velars is a gradient effect, less extreme than phonemic palatilization of velars. True palatals are even further forward on the palate and contrast with contextually fronted velars before front vowels. Thus these consonant types should not be collapsed by feature systems.

Humans↗
PubMed1993

Indapamide reduces hypertensive left ventricular hypertrophy: an international multicenter study.

The effect of 6 months of treatment with indapamide (IND, 2.5 mg/day) on regression of left ventricular hypertrophy (LVH), an independent predictor of poor prognosis in hypertension, was compared by echocardiography to that of nifedipine (NFD, 40 mg/day), enalapril (ENL, 20 mg/day), atenolol (ATL, 100 mg/day), and hydrochlorothiazide (HCTZ, 25 mg/day) in four parallel double-blind studies in 151 hypertensive patients with a diastolic blood pressure between 95 and 120 mm Hg and a raised left ventricular mass index (LVMI) (mg/m2) (Devereux). Patients were randomized to IND or comparator following a 2-week washout (1 month in the IND vs. ATL study). Respective baseline and 6-month LVMI values (mg/m2) were: IND (n = 20) vs. HCTZ (n = 20): 151.4 +/- 6.3 and 125.70 +/- 4.6 (p < 0.001) vs. 141.3 +/- 6.6 and 135.6 +/- 8.3 (p = N.S.); IND (n = 22) vs NFD (n = 19): 144.1 +/- 5.3 and 125.1 +/- 4.3 (p < 0.001) vs. 170.4 +/- 6.6 and 148.2 +/- 6.2 (p < 0.001); IND (n = 9) vs. ENL (n = 9): 155.1 +/- 6.3 and 143.4 +/- 5.2 (p < 0.001) vs. 142.0 +/- 6.7 and 130.0 +/- 5.9 (p < 0.001); IND (n = 17) vs. ATL (n = 12): 146.2 +/- 5.1 and 130.8 +/- 6.5 (p < 0.001) vs. 156.7 +/- 8.4 and 142.9 +/- 10.3 (p < 0.01). All drugs significantly reduced diastolic blood pressure, and all except HCTZ induced a significant and similar reduction in left ventricular mass.

Adult↗
PubMed1993

Flow cytometric observations on the in vivo use of Fab fragments of a chimaeric monoclonal antibody to platelet glycoprotein IIb-IIIa.

Fluorescence flow cytometry (FC) was employed to monitor the platelet surface in humans receiving intravenous infusions of Fab fragments of a chimaeric (murine/human) construct of monoclonal antibody 7E3, which binds to the fibrinogen receptor (glycoprotein IIb-IIIa) and inhibits platelet aggregation. Platelet surface-bound chimaeric 7E3-Fab (c7E3-Fab) was measured using a fluorescein-conjugated polyclonal anti-7E3 antibody and residual c7E3-Fab binding capacity was measured using fluorescein-conjugated c7E3-Fab. Turbidometrically measured platelet aggregation response to ADP was shown to be a linear function (r = 0.9) of the logarithm of residual free binding sites for c7E3-Fab. The distribution of c7E3-Fab in the platelet population was unimodal at all time points following the infusion, demonstrating in vivo transfer of antibody to newly released circulating platelets. Clearance of platelet surface-bound antibody followed an exponential model but all circulating platelets were bearing c7E3-Fab at time points well beyond the lifespan of the platelets exposed to c7E3-Fab during the infusion. Ex vivo and in vitro mixing experiments showed that c7E3-Fab transfer between platelets was possible and suggested that differences in the in vivo kinetics between monovalent and bivalent forms of monoclonal antibodies might be relevant in their therapeutic application.

Adenosine Diphosphate↗
PubMed1993

Technetium-99m-1,2-bis[bis(2-ethoxyethyl) phosphino]ethane: human biodistribution, dosimetry and safety of a new myocardial perfusion imaging agent.

A novel 99mTc complex (1,2-bis[bis(2-ethoxyethyl)phosphino] ethane, 99mTc-tetrofosmin) has been developed to replace 201Tl in myocardial perfusion imaging. Biodistribution, safety and dosimetry of 99mTc-tetrofosmin were studied in 12 male volunteers, each at rest and during exercise. Safety parameters measured to 48 hr postinjection revealed no clinically significant long-term drug-related changes. Biodistribution was studied by acquiring whole-body or serial static images up to 48 hr postinjection. Technetium-99m-tetrofosmin shows good heart uptake (1.2%) with retention. Clearance is excellent from blood (< 5% by 10 min), liver (< 4.5% by 60 min) and lung. Sequestration of activity by skeletal muscle is enhanced during exercise. Radiation dosimetry calculations indicate that the effective dose, assuming a 3.5 hr bladder voiding period, is 32.9 x 10(-3) rad/mCi (8.9 x 10(-3) mSv/MBq) at rest and 26.7 x 10(-3) rad/mCi (7.1 x 10(-3) mSv/MBq) after exercise. Technetium-99m-tetrofosmin can produce high quality myocardial images from 5 min to several hours postinjection.

Heart↗