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Biomedical subjects

M A Rahman

Publications and source records attributed to M A Rahman.

At least 73 records · Page 4Linked to original sources
PubMed1995

Reductions in muscle sympathetic nerve activity after long-term metoprolol for dilated cardiomyopathy: preliminary observations.

OBJECTIVE: To determine whether efferent muscle sympathetic nerve activity diminishes in subjects with dilated cardiomyopathy who improve after long term treatment with metoprolol. METHODS: Microneurographic, echocardiographic, plethysmographic, and neurohumoral data were obtained immediately before and 20 months after the addition of beta blockade in seven subjects with idiopathic dilated cardiomyopathy with clinical deterioration despite conventional treatment. RESULTS: Six subjects (three men, three women, aged 24-62 years) were restudied after a mean (SEM) of 20 (2.4) months treatment with metoprolol (45.8 (2.6) mg/d). Long term treatment was associated with decreases in left ventricular end diastolic and end systolic diameter (P < 0.005), left ventricular mass index (P < 0.05), and atrial natriuretic factor (P < 0.05), and increases in fractional shortening (P < 0.05) and mean blood pressure (P < 0.05). There was a 50% reduction in peroneal muscle sympathetic nerve activity (from 49.2 (10.1) to 24.5 (4.7) bursts/min; (P < 0.005) and a 62% decrease in calf vascular resistance (from 56.2 (4.4) to 21.2 (5.7) units; P < 0.005). This reduction in pulse synchronous nerve activity was not simply a function of bradycardia (heart rate fell from 94.2 (4.6) to 62.8 (5.7) beats/min; P < 0.005) since muscle sympathetic burst incidence also decreased (from 51 (8.7) to 37.5 (5.2) bursts/100 heart beats; P < 0.05). Similar haemodynamic improvement was observed in the seventh subject, who was switched to sotalol 200 mg/d and restudied after 20 months, but burst frequency was 50% higher and calf vascular resistance 93% higher. CONCLUSIONS: Muscle sympathetic nerve activity and calf vascular resistance decrease in patients with dilated cardiomyopathy who improve after long term treatment with metoprolol. Inhibition of central sympathetic outflow may be one mechanism by which metoprolol benefits such subjects.

Adrenergic beta-Antagonists↗
PubMed1995

Comparison of candoxatril and atrial natriuretic factor in healthy men. Effects on hemodynamics, sympathetic activity, heart rate variability, and endothelin.

The purpose of these experiments was to compare the effects of endopeptidase inhibition with oral candoxatril on systemic and forearm hemodynamics and muscle sympathetic nerve activity with responses to a low-dose atrial natriuretic factor infusion. Eleven healthy men received at random on three separate days either intravenous saline, natriuretic factor (1.6 pmol/kg per minute) plus saline, or oral candoxatril (200 mg) plus saline. Measurements were made at baseline and 30, 60, and 90 minutes after interventions. Atrial natriuretic factor lowered diastolic pressure (P < .01), central venous pressure (P < .001), forearm blood flow (P < .05), and forearm vascular compliance (P < .05) but had no effect on systolic pressure, heart rate or its variability, stroke volume, sympathetic nerve activity, plasma norepinephrine, or endothelin-1. Plasma epinephrine increased (P < .01). Candoxatril lowered central venous pressure (P < .001) and increased systolic pressure (from 116 +/- 6 to 120 +/- 7 mm Hg; P < .05), endothelin (from 4.6 +/- 1.1 to 6.8 +/- 3.2 pmol/L; P < .02), and epinephrine (P < .05), without affecting any other variables. Candoxatril and atrial natriuretic factor lowered central venous pressure in healthy men without causing a reflex increase in sympathetic nerve activity or norepinephrine, yet epinephrine rose. This suggests that both interventions may specifically inhibit sympathetic nerve traffic to muscle at physiological plasma atrial natriuretic factor concentrations. However, whereas the peptide lowered blood pressure, candoxatril increased systolic pressure. These contrasting hemodynamic responses may be related to differences in plasma atrial natriuretic peptide concentration and to altered endothelin metabolism by candoxatril.

Administration, Oral↗
PubMed1995

Optimum concentration and application time of 1,6-hexanediol as a dentin primer.

The optimum concentration and application time for an experimental dentin primer composed of an aqueous solution of 1,6-hexanediol were determined by measuring the wall-to-wall polymerization contraction gap width of a commercial light-activated resin composite in a cylindrical dentin cavity prepared in an extracted human molar. Contraction gap formation was completely prevented only when the dentin cavity wall was primed with 45 wt% 1,6-hexanediol for 60 s. There were no significant differences in tensile bond strength among primers composed of 20.0-57.5 wt% 1,6-hexanediol. These results suggest that the optimum concentration and application time are 45 wt% and 60 s, respectively.

Analysis of Variance↗
PubMed1995

Study on Mycobacterium tuberculosis: the primary drug resistance pattern.

The study was carried out to investigate the primary drug resistance pattern of tubercle bacilli isolated from the pulmonary tuberculosis patient attended in Shyamoli TB clinic, Dhaka. Sputum from 961 suspected tuberculous patients were randomly collected and stained by Ziehl-Neelsen (Z.N) stain. 135 were microscopically positive for Acid Fast Bacilli (AFB). Among them 30 patients were excluded from the study as they received antitubercular treatment before. So only 105 microscopically positive cases were cultured on Lowenstein-Jensen (L-J) media and 100 showed pure growth and rest 5 were contaminated with fungus. These 100 cases were studied on 4 antitubercular drugs. Out of these 100 isolates, 91 were M. tuberculosis and rest 9 in the nonchromogen group of mycobacteria other than tuberculosis (MOTT) species. Among 91 M. tuberculosis species, 89 (97.80%) to Isoniazid (INH), 73 (80.21%) to Rifampicin (RMP) and 91 (100%) to Streptomycin (SM) and Ethambutol (ETHM) were sensitive. Of the 9 MOTT species, 4 (44.44%) to SM, 7 (77.78%) to ETHM were sensitive and all (100%) were resistant to INH and RMP. Among the 100 isolates, 27 (18 M. tuberculosis and 9 MOTT) were resistant to 4 drugs either single or in combination. Of the 18 (66.67%) M. tuberculosis species, 16 (59.26%) to RMP, and 2 (7.41%) to RMP and INH were resistant. Of the 9 (33.33%) MOTT species, 4 (14.81%) to RMP and INH, 3 (11.11%) to RMP, INH and SM and 2 (7.41%) to RMP, INH, SM and ETHM were resistant.

Antitubercular Agents↗
PubMed1994

Autoantibodies in systemic lupus erythematosus.

Various autoantibodies are found in systemic lupus erythematosus. Anti-double-stranded DNA antibodies are the most pathognomonic and among the most extensively studied. Genetic studies of these antibodies and their idiotypes suggest that high-affinity IgG anti-double-stranded DNA antibodies are produced by a process of somatic mutation and clonal expansion favoring sequences with accumulated positively charged amino acids in the complementarity-determining regions. The antigens that trigger this process are not known, but recent studies have suggested that a DNA-protein complex may be implicated. At the tissue level, these antibodies may react directly with membrane proteins or indirectly via complexes with DNA, histones, and heparan sulfate. Serologic studies have sought to establish links between clinical features and the presence of particular non-DNA-binding autoantibodies. Of particular interest have been antibodies to proteins with nucleic acid-binding potential, such as Sm, SS-A (Ro), and SS-B (La).

Antibodies, Anti-Idiotypic↗
PubMed1994

Intracellular processing of immune complexes formed on the surface of glomerular epithelial cells.

Immune complexes formed on the surface of glomerular epithelial cells (GEC) resolve slowly and therefore result in inflammation of the glomerular capillary wall, as in the case of human membranous glomerulonephritis. The metabolic defect in the processing of these complexes has not been identified. Immune complexes of cationic bovine gamma-globulin (BGG) and anti-BGG were formed on cultured GEC, and their intracellular processing was followed by tracing the fate of radioiodinated and colloidal gold-labeled anti-BGG in the endosomal, lysosomal, and extracellular compartments. It was determined that the complexes were rapidly internalized in endosomes (50% saturation achieved in 10 min). The rate of expulsion of complexes was much slower (50% of internalized complex exteriorized in approximately 90 min). Of the internalized anti-BGG, < 5% were proteolytically degraded, suggesting an inefficient lysosomal processing. This aspect was studied further by separating anti-BGG colloidal gold-loaded vesicles by low-speed centrifugation and quantitating the lysosomal enzymes acid phosphatase and beta-galactosidase. At equilibrium approximately 10% of total cellular enzymes was associated with the vesicles. It was concluded that immune complexes are rapidly internalized by the GEC. However, lysosomal processing of the complexes is slow and inefficient. The majority of accumulated endosomes route back to the plasma membrane and discharge their contents in the medium in the form of free antibody.

Animals↗
PubMed1994

All elevated creatine kinase is not neuroleptic malignant syndrome.

Creatine kinase (CK) is an enzyme that is found widely in muscle tissues. Raised levels would occur when there is muscle damage. Raised levels are used as one of the diagnostic criteria for Neuroleptic Malignant Syndrome (NMS). This study looks at CK levels in 30 psychotic inpatients without NMS and compares them with 10 patients with NMS. It was found that 67% of the patients without NMS had raised CK levels, 20% of whom had levels in excess of 1000 IU/L. The rest had a two to five-fold increase over normal limits. Raised levels were associated with the use of intramuscular injections and physical restraints, situations which are well known to result in muscle injury. All the NMS patients had raised CK levels but 40% had levels below 1000 IU/L. Our findings support the idea that CK levels, though helpful, should be interpreted with care as raised levels are nonspecific.

Antipsychotic Agents↗
PubMed1993

Parathyroid hormone in urinary stone patients.

To evaluate the role of parathyroids in calculus disease, the parathyroid hormone levels were determined in 22 control subjects and 42 stone (14 with bladder stone and 28 with kidney stone) patients. Serum calcium, inorganic phosphate, alkaline phosphatase and parathyroid hormone and urinary excretion of calcium and inorganic phosphate were determined. It was found that normocalcemic and normocalciuric stone patients had slightly higher levels of parathyroid hormone (irrespective of the site of the stone) and the difference was not statistically significant as compared with control subjects although some of the patients with calculus disease were hyperparathyroid. Serum alkaline phosphatase was increased while there was an increase in urinary calcium excretion in kidney stone patients and oxalate in all patients as compared with control subjects. The increase in inorganic phosphate was, however, not different from the control subjects. The subclinical hyperparathyroidism and stone formation in these patients are not correlated.

Adult↗
PubMed1993

A study on socio-economic and intermediate variables on fertility.

"In this paper an attempt has been made to examine fertility differentials of currently married rural women [in Bangladesh] by their socioeconomic (viz, education of women, land ownership and family type) and demographic (viz, age at the first marriage, duration of breast feeding and duration of post partum amenorrhoea for the child) characterisation. This study is based on data collected from 995 currently married women of childbearing age. It has been found that women's (i) level of education (ii) age at first marriage (iii) duration of breastfeeding and (iv) duration of post-partum amenorrhoea, are inversely related with fertility. Joint family shows higher fertility than that of nuclear family and land ownership reveals [a] U-shaped relationship with fertility."

Amenorrhea↗
PubMed1992

Cloning, sequencing, and expression of the Escherichia coli peptide methionine sulfoxide reductase gene.

The gene encoding peptide methionine sulfoxide reductase was cloned from an Escherichia coli genomic library using an oligonucleotide probe based on the amino-terminal sequence of the protein. The nucleotide sequence revealed that the gene codes for a polypeptide of 212 amino acid residues with a calculated molecular weight of 23,314. The protein has been overexpressed in E. coli and is present as a soluble active species.

Amino Acid Sequence↗
PubMed1992

Penile calcification in maintenance hemodialysis patients.

Penile calcification was detected in 6 of 32 patients (19%) with end-stage renal disease (ESRD) using soft tissue x-ray techniques. Having been maintained on hemodialysis for a minimum of one year, all the affected patients showed clinical evidence of secondary hyperparathyroidism and calcification in the blood vessels of some other tissues. All had erectile impotence, while in 1 patient gangrene of the penis developed. Penile calcification is probably more common in ESRD patients than realized and should be looked for as a possible cause of impotence in male patients treated with maintenance hemodialysis.

Adult↗
PubMed1992

Spinal infection by Mycobacterium xenopi in a non-immunosuppressed patient.

A previously fit 77-year-old woman was found to have a paravertebral abscess. This was aspirated, yielding Mycobacterium xenopi, but no other pathogens. Antituberculosis chemotherapy with four first-line agents was commenced, with some response but continuing pain. Reports of extrapulmonary M. xenopi infections are rare. Most previous cases have involved immunosuppressed patients. This is the first reported case of spinal M. xenopi infection in a non-immunosuppressed patient, but radiological evidence suggests that previous tuberculous infection may have damaged the lumbar vertebrae, rendering them susceptible to infection by M. xenopi.

Abscess↗
PubMed1992

Synthesis of 2-(3-substituted-1,2,4-oxadiazol-5-yl)-8-methyl-8-azabicyclo [3.2.1]octanes and 2 alpha-(3-substituted-1,2,4-oxadiazol-5-yl)-8-methyl-8- azabicyclo[3.2.1]oct-2-enes as potential muscarinic agonists.

Radioligand binding affinities of seven muscarinic receptor ligands which possess an oxadiazole ring side chain have been determined in rat heart, rat brain, and m1- or m3-transfected CHO cell membrane preparations to determine the selectivity for subtypes of muscarinic receptor. The ratios of binding constants in brain membranes were measured as an indicator of potential agonist activity against [3H]QNB and [3H]Oxo-M. These muscarinic ligands did not discriminate the subtypes of muscarinic receptors. Six muscarinic ligands which have a 3-amino- or 3-methyl-1,2,4-oxadiazol-5-yl groups attached to the 8-methyl-8-azabicyclo[3.2.1]oct-2-ene or 8-methyl-8-azabicyclo[3.2.1]octane head group show binding constants between 2.04 x 10(-6) and 1.79 x 10(-5) M in rat heart, rat brain, and m1- or m3-transfected CHO cell membrane preparations. 1-Methyl-2-[3-amino-1,2,4-oxadiazol-5-yl]piperidine shows low binding constants of approximately 10(-4) M in rat heart and rat brain. (1R,5S)-2-[3-Amino-1,2,4-oxadiazol-5-yl]-8-methyl-8-azabicyclo- [3.2.1]oct-2-ene [(1R,5S)-17] was the most active compound.

Animals↗
PubMed1992

A comparison of expiration dating period estimation methods.

Two methods of estimating expiration date have been compared. For a drug whose potency is expected to decrease with time, method 1 fits a linear regression line to the stability data, calculates a 95% lower confidence limit of the true degradation line, and estimates the expiration date by comparing the confidence limit with the lower specification limit. Method 2 calculates a 95% lower confidence limit b1 of the slope of the true degradation line, constructs a new line y" using b1 as its slope, and finally estimates the expiration date by comparing y" with the lower specification limit. In this work we show that in most practical situations, method 1 estimates greater expiration date than method 2.

Chemistry, Pharmaceutical↗
PubMed1992

Frequent oropharyngeal shedding of Epstein-Barr virus in homosexual men during early HIV infection.

OBJECTIVE: To determine the frequency of Epstein-Barr virus (EBV) oropharyngeal shedding during HIV infection in homosexual men in the Multicenter AIDS Cohort Study. DESIGN: The cohort consisted of 210 men who were HIV-seronegative at their baseline study visit, 39 of whom seroconverted to HIV at a later date, and 73 asymptomatic and mildly symptomatic men with HIV infection of indeterminate duration. METHODS: EBV in throat washings was detected by transformation of newborn cord blood lymphocytes. RESULTS: EBV was isolated from 49% (35 out of 71) of the HIV-seropositive and 16% (33 out of 204) of the HIV-seronegative homosexual men tested at their baseline visit. Elevated EBV shedding frequency was noted 6 months before, as well as during the first HIV-seropositive clinic visit, in the men who seroconverted to HIV. Seronegative men who shed EBV at their baseline visit seroconverted to HIV within a shorter period than did non-shedders during 5 years of follow-up. Shedding of EBV was not significantly associated with either abnormal T-cell numbers, clinical symptoms or risk for development of AIDS. CONCLUSIONS: There is an increased rate of EBV shedding in HIV-seropositive homosexual men that occurs very early in the course of HIV infection.

Acquired Immunodeficiency Syndrome↗