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Biomedical subjects

M Alam

Publications and source records attributed to M Alam.

At least 19 recordsLinked to original sources
PubMed1992

Left ventricular response to submaximal exercise in endurance-trained athletes and sedentary adults.

This investigation examines the hypothesis that athletes increase stroke volume with submaximal exercise through an augmentation of left ventricular (LV) end-diastolic volume and a reduction of LV end-systolic volume, whereas sedentary adults only increase stroke volume modestly, because LV end-diastolic volume does not increase. Upright bicycle exercise was performed by 17 endurance-trained male athletes and 15 sedentary men. M-mode echocardiograms were obtained during submaximal exercise at predetermined heart rates. Athletes, at a heart rate of 130 beats/min, increased their stroke volume 67% from 72 +/- 18 ml to 120 +/- 26 ml (p less than 0.001). This resulted from an increase of LV end-diastolic volume from 119 +/- 23 to 152 +/- 28 ml (p less than 0.001) and a reduction in LV end-systolic volume from 46 +/- 14 to 31 +/- 9 ml (p less than 0.001). Sedentary men at the same heart rate increased stroke volume 22% from 63 +/- 15 to 77 +/- 21 ml (p less than 0.05). LV end-diastolic volume did not change (96 +/- 20 vs 97 +/- 28 ml) (p = not significant), but LV end-systolic volume decreased (33 +/- 11 vs 20 +/- 9 ml) (p less than 0.001). In conclusion, athletes increased cardiac output through a more prominent augmentation of stroke volume than sedentary subjects at submaximal exercise. This was accomplished through an augmentation of LV end-diastolic volume. This may have a conserving effect on myocardial oxygen consumption at these levels of exercise.

Adult↗
PubMed1992

Synthesis and antiviral activity of methyl derivatives of 9-[2-(phosphonomethoxy)ethyl]guanine.

A number of methyl derivatives of 9-[2-(phosphonomethoxy)ethyl]guanine (PMEG, 1) have been synthesized and tested in vitro for anti-herpes and anti-human immunodeficiency virus (HIV) activity. Among these analogues, (R)-2'-methyl-PMEG [(R)-3] and 2',2'-dimethyl-PMEG (7) demonstrated potent anti-HIV activity in the XTT assay with EC50 values of 1.0 and 2.6 microM, respectively. The corresponding (S)-2'-methyl-PMEG [(S)-3] was found to be less potent against HIV. In addition, the (R) and (S) enantiomers of 9-[3-hydroxy-2-(phosphonomethoxy)propyl]guanine (HPMPG, 8) were prepared for comparison of biological activity, and shown to be active and equipotent against herpesviruses, but inactive against HIV.

Antiviral Agents↗
PubMed1992

Serial echocardiographic studies following thrombolytic treatment in myocardial infarction with special reference to the atrioventricular valve plane displacement.

Echocardiographic recording of the atrioventricular (AV) valve plane displacement was used for serial studies of left ventricular (LV) function in 27 patients with first-time acute myocardial infarction (MI) treated with a thrombolytic agent within 4 h of the onset of symptoms and showing noninvasive signs of early reperfusion. The recordings were made immediately before or during thrombolytic therapy and 24 h, 1 week, 1 month, and 2 months after attempted reperfusion. Regional LV function was assessed by recording the amplitude of systolic descent of the AV plane toward the apex at 4 different sites on left ventricle corresponding to the septal, anterior, lateral, and posterior walls from apical 4- and 2-chamber views. Global LV function was assessed using the mean value of the AV plane displacement from the above 4 sites (AV mean). In 15 patients with anterior MI, the displacement at the septum and anterior wall was significantly decreased compared with the posterior and lateral walls at baseline. The displacement had increased significantly after 1 week, 1 month, and 2 months (p less than 0.01, p less than 0.01, and p less than 0.001). The AV mean also increased significantly (p less than 0.01) during the study period. A corresponding regional increase was observed in inferior MI. The AV mean remained unchanged, however, during the follow-up period. It is concluded that the easy visualization and the simplicity of recording the AV plane displacement makes the method a valuable non-invasive tool for serial echocardiographic studies following acute MI treated with a thrombolytic agent.

Echocardiography↗
PubMed1992

Mechanism of functional mitral regurgitation during acute myocardial ischemia.

The mechanism and temporal manifestation of functional mitral regurgitation after acute myocardial ischemia were examined in eight dogs. Regional ischemia was produced by selective microembolization of the left circumflex coronary artery. Mitral regurgitation and regional left ventricular wall motion abnormalities were evaluated with use of Doppler color flow mapping and two-dimensional echocardiography, respectively. Measurements were made at baseline (before embolization) and were repeated at 30 min and 3 weeks after embolization. Mitral regurgitation developed in all dogs 30 min after embolization and completely subsided 3 weeks later. There was no evidence of mitral valve prolapse, mitral anulus dilation or left ventricular segmental dyskinesia at any time during the study. Regional wall motion analysis showed only hypokinesia of the left ventricular segment overlying the papillary muscle at 30 min with subsequent normalization of the segment at 3 weeks. Mitral regurgitation was accompanied by an increase of the end-systolic distance between the mitral anulus plane and the point of coaptation of the mitral leaflets. This distance was 0.5 +/- 0.1 cm at baseline, increased to 0.9 +/- 0.1 cm 30 min after the embolization (p less than 0.001) and returned to near baseline (0.6 +/- 0.1 cm) 3 weeks after the embolization. These data indicate that mitral valve prolapse, mitral anulus dilation and regional left ventricular dyskinesia are not necessary conditions for the development of functional mitral regurgitation after acute myocardial ischemia. Instead, hypokinesia of the ventricular segment overlying the papillary muscle and leading to retraction of the mitral leaflets toward the apex appears to be a sufficient condition for incomplete leaflet coaptation.

Animals↗
PubMed1992

Left ventricular shape is the primary determinant of functional mitral regurgitation in heart failure.

OBJECTIVES: The aim of this study was to examine the temporal association between the onset of functional mitral regurgitation and the development of changes in left ventricular shape, chamber enlargement, mitral anulus dilation and regional wall motion abnormalities during the course of evolving heart failure. BACKGROUND: Despite extensive characterization, the exact etiology of functional mitral regurgitation in patients with chronic heart failure remains unknown. METHODS: Heart failure was produced in seven dogs by multiple sequential intracoronary microembolizations. Serial changes in left ventricular chamber volume and shape were evaluated from ventriculograms. Changes in mitral anulus diameter and ventricular regional wall motion abnormalities were evaluated echocardiographically. The presence and severity of mitral regurgitation were determined with Doppler color flow mapping. Measurements were obtained at baseline and then biweekly until mitral regurgitation was first observed. RESULTS: No dog had mitral regurgitation at baseline but all developed mild to moderate regurgitation 12 +/- 1 weeks after the first embolization. The onset of mitral regurgitation was not associated with an increase in left ventricular end-diastolic volume relative to baseline (58 +/- 3 vs. 62 +/- 3 ml), mitral anulus diameter (2.4 +/- 0.1 vs. 2.4 +/- 0.1 cm) or wall motion abnormalities of left ventricular wall segments overlying the papillary muscles. In contrast, the onset of mitral regurgitation was accompanied by significant changes in global left ventricular shape evidenced by increased end-systolic chamber sphericity index (0.22 +/- 0.02 vs. 0.30 +/- 0.01) (p < 0.01) and decreased end-systolic major axis/minor axis ratio (1.71 +/- 0.05 vs. 1.43 +/- 0.04) (p < 0.001). CONCLUSIONS: These data indicate that transformation of left ventricular shape (increased chamber sphericity) is the most likely substrate for the development of functional mitral regurgitation.

Angiography↗
PubMed1992

Haemodynamic significance of the atrioventricular plane displacement in patients with coronary artery disease.

Echocardiographic quantitative assessment of the atrioventricular plane displacement (AVPD) in systole towards the apex has been used to estimate global left ventricular (LV) function. The study population consisted of 106 patients with coronary artery disease (CAD) with or without previous myocardial infarction and 40 age-matched healthy subjects. The AVPD was recorded from the apical four- and two-chamber views at four sites corresponding to the septal, lateral, anterior and posterior walls of the left ventricle. A mean displacement (AVmean) was calculated from the above sites. AVmean was significantly decreased in patients with CAD compared to healthy subjects (P less than 0.001). In patients in whom the left ventricular ejection fraction (LVEF) was calculated from cineangiograms a good correlation between AVmean and LVEF was found (r = 0.89, P less than 0.001, SEE = 6.4). Selecting an AVmean of 10 mm or more to define a normal LVEF (greater than or equal to 55%) resulted in a sensitivity of 92% and a specificity of 87% in predicting a normal versus abnormal left ventricular systolic function. It is concluded that the ease of recording the AVPD by echocardiography provides a simple and valuable noninvasive method to assess global left ventricular function in patients with CAD.

Adult↗
PubMed1992

Longitudinal systolic shortening of the left ventricle: an echocardiographic study in subjects with and without preserved global function.

The atrioventricular (AV) plane displacement was studied by echocardiography in 79 subjects (45 healthy subjects and 34 patients with acute myocardial infarction or chronic congestive heart failure). From apical 4- and 2-chamber views the displacement of the AV plane towards the apex in systole was recorded at 4 sites in the left ventricle (LV) corresponding to the septal, anterior, lateral, and posterior walls and the mean value from the above 4 sites (AV-mean) was calculated. In addition, in healthy subjects, the AV plane displacement at right ventricular free wall was also recorded. The AV-mean correlated well with the echocardiographic ejection fraction determined by biplane area-length method (r = 0.96, P less than 0.001). The correlation was also high when the percentage of the left ventricular shortening along the long axis was used (r = 0.97, P less than 0.001). The correlation between ejection fraction and AV-mean was also good when separate analysis was made for the subjects with preserved ejection fraction (r = 0.86, P less than 0.001) and decreased ejection fraction (r = 0.82, P less than 0.001). The right ventricle had a significantly higher AV plane displacement (P less than 0.001) than the LV. The study also includes determination of the muscular excursions of the septal and posterior walls along the short axis of the left ventricle from the parasternal long axis view. The AV plane displacement of the respective walls was relatively greater (P less than 0.001) compared to concentric contractions. The septal and posterior wall excursions along the short axis correlated poorly with the AV plane displacement of the respective walls (r = 0.55, P less than 0.01 and r = 42, P less than 0.05).

Adult↗
PubMed1992

Occurrence of resistance to vibriostatic compound 0/129 in Vibrio cholerae 01 isolated from clinical and environmental samples in Bangladesh.

Fifty-one Vibrio cholerae 01 strains isolated from 734 natural water and plankton samples and 31 rectal swabs were examined. Of these strains, 32 (62.7%) were found to be resistant to vibriostatic compound 0/129. When antibiograms using the antibiotics ampicillin, tetracycline, chloramphenicol, trimethoprim-sulfamethoxazole, furoxan, and gentamicin were done, it was observed that there was a correlation of sensitivity to 0/129 with selected antibiotics. Only the Ogawa E1 Tor (72% of strains resistant) and Inaba classical (28% of strains resistant) biotypes of V. cholerae 01 showed resistance to 0/129. On the other hand, all Inaba E1 Tor and Ogawa classical strains were susceptible to 0/129. The 32 0/129-resistant and 19 0/129-sensitive isolates of V. cholerae 01 were tested for the presence of plasmid DNA. Only two strains isolated from the environment were found to carry a plasmid, and they were also found to be resistant to 0/129 and gentamicin. Thus, 0/129 resistance, although more common than previously suspected, is concluded not to be plasmid mediated in the strains tested in this study.

Animals↗
PubMed1992

E2 prostaglandins modulate cell proliferation in the small intestinal epithelium of the rat.

Groups of Sprague-Dawley rats were administered 1 mg/kg indomethacin subcutaneously, indomethacin subcutaneously plus 200 micrograms/kg oral 15-R-15 methyl-prostaglandin E2 (MePGE2) or oral MePGE2 twice daily for 10 days. The animals were treated with antibiotics to prevent mortality. Two control groups were used: control 1 was given placebo and control 2 was treated with antibiotics. All rats were killed 4 h after injection of a metaphase blocker, and the proliferative activity of the distal small intestine was examined in histological sections by means of the cumulative mitotic index (MI). A reduction in the number of villous cells was observed in the rats given antibiotics (p < 0.05 vs. control 1). The small intestinal villi of the rats treated with indomethacin had fewer cells than those of both control groups (p < 0.05) whereas the crypts contained more cells (p < 0.05) and had a higher MI than those of the controls (p < 0.05 vs. controls 1 and 2). These changes were reverted by the prostaglandin analogue. The number of cells of the small intestinal crypts and the cumulative MI in the rats who received indomethacin and the prostaglandin analogue were similar to controls, and they were significantly lower than the values observed in the animals treated with indomethacin (p < 0.05). The animals treated with the prostaglandin analogue and placebo developed a marked hyperplasia of the small intestinal villi (p < 0.05 vs. both control groups), but the atrophy of the villi induced by indomethacin was not prevented by simultaneous administration of the analogue.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Left atrial contribution to ventricular filling during the course of evolving heart failure.

BACKGROUND: Abnormal left ventricular (LV) filling has been observed in patients with heart failure and is characterized by marked heterogeneity of mitral inflow velocity. In the present study, the contribution of the left atrium to LV filling was examined in eight dogs during the course of evolving heart failure. METHODS AND RESULTS: Heart failure was produced by multiple sequential intracoronary embolizations with microspheres. Pulsed Doppler echocardiography was used to measure mitral inflow velocity at baseline, before embolization, and at 3, 8, 15, 23, and 33 weeks after initiation of microembolization. The early rapid LV filling (Ei) and late left atrial filling (Ai) components were quantitated based on the time-velocity integral of the early and late mitral inflow velocity waveforms, respectively. Ei decreased progressively from 7.6 +/- 1.5 cm at baseline to 4.0 +/- 0.4 cm at 33 weeks (p less than 0.01). In contrast, Ai initially increased from 1.8 +/- 0.9 cm at baseline to 2.7 +/- 0.4 cm at 3 weeks (p less than 0.01) and subsequently decreased gradually to below baseline values reaching 0.8 +/- 0.4 cm at 33 weeks (p less than 0.01). These temporal changes of Ei and Ai were accompanied by a gradual reduction of LV ejection fraction (56 +/- 5% versus 22 +/- 2%) (p less than 0.01) (baseline versus 33 weeks) and by a gradual increase of LV end-diastolic wall stress (24 +/- 7 versus 92 +/- 8 g/cm2) (p less than 0.01), left atrial dimension (2.4 +/- 0.2 cm to 3.3 +/- 0.3 cm) (p less than 0.01), and left atrial fractional shortening (22 +/- 3% versus 15 +/- 2%) (p less than 0.01). CONCLUSIONS: The initial rise in left atrium contribution to LV filling may represent a compensatory response to the diminution of the rapid early component of LV filling. With further progression of LV dysfunction, the left atrium contribution to LV filling gradually decreased. This reduction may be mediated by increased workload imposed on the left atrial myocardium due to increased LV diastolic wall stress, which, over time, may have lead to intrinsic left atrium dysfunction.

Animals↗
PubMed1992

Transesophageal echocardiographic findings in patients with orthotopic heart transplantation.

This study was performed to determine the diagnostic value of TEE in recipients of orthotopic heart transplantation. Findings on TEE were compared with those of TTE in 30 patients with orthotopic heart transplantation. Transesophageal echocardiography identified left atrial appendage and flow across the interatrial septum ... findings not detected by TTE. In addition, pronounced bulging of the interatrial septum was seen in six patients by TEE and not by TTE. Spontaneous echo contrast (smoke) in the atria was detected by TEE in 14 patients and by TTE in one patient. Abnormal geometry of the atria and donor-recipient atrial anastomosis was identified in all patients by TEE and TTE. Our findings suggest that TEE should be selectively utilized in the operating room, in patients with suspected atrial thrombi, and in those with clinically significant right ventricular volume overload to assess integrity of interatrial anastomosis.

Echocardiography↗
PubMed1992

Biopharmaceutical studies of spirobishexahydropyrimidine.

Oral administration of spirobishexahydropyrimidine showed an increase in the activity of serum transaminases, lactate dehydrogenase and alkaline phosphatase. Biological half life and other pharmacokinetic parameters showed rapid absorption and slow elimination of the drug.

Alanine Transaminase↗
PubMed1992

Antiinflammatory and antipyretic activity of vicolides of Vicoa indica DC.

Vicolides A,B, C and D, the sesquiterpene lactones isolated from V. indica exhibited antiinflammatory activity against cotton pellet granuloma in rats at dose level of 10 mg/kg body weight, sc. Highly significant activity was observed with vicolides C and D. They reduced the protein content, acid and alkaline phosphatase, glutamate-pyruvate transaminase and glutamate oxaloacetate transaminase activities in liver and serum. Significant reduction in ascorbic acid content in adrenals was also observed in treated animals. The highly significant antiinflammatory activity of vicolides C and D can be attributed to their chemical structures. Vicolide D has an epoxy angeloyl group while vicolide C has 3,4 epoxy group and an ester moiety in the molecule. Vicolide D possesses antipyretic activity at 250 mg/kg body weight, po dose. It may be due to the presence of epoxy angeloyl group in the molecule.

Adrenal Glands↗