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Biomedical subjects

M Ahmad

Publications and source records attributed to M Ahmad.

At least 217 records · Page 12Linked to original sources
PubMed1995

A genetic analysis of HIV-1 from Punjab, India reveals the presence of multiple variants.

OBJECTIVE: To determine the extent of HIV-1 genetic variation in Indian patients. DESIGN: To avoid any bias in selecting viral variants, HIV-1 DNA was amplified directly from the peripheral blood mononuclear cells of patients and sequenced. Genetic similarity between Indian sequences and other geographic isolates was analysed by phylogenetic analysis algorithms. METHODS: A fragment encompassing the C2/V3-V5 regions of HIV-1 gp120 was amplified from the lymphocyte DNA of 12 Indian patients. Multiple clones from each patient were sequenced. Nucleotide sequences encompassing about 650 base pairs were aligned for the Indian and other geographically distinct isolates. Inter-isolate relationships were analysed by means of distance, parsimony and neighbour-joining algorithms. RESULTS: Nucleotide sequence comparisons showed low interpatient variation. Amino-acid comparisons revealed a high degree of homology between Indian sequences in this study and those studied earlier. On distance and parsimony trees, most of the Indian sequences clustered together as subtype C. However, sequences from three patients also showed significant homologies and phylogenetic clustering outside of subtype C. CONCLUSIONS: The predominant strain of HIV-1 in India belongs to subtype C and little interpatient nucleotide sequence divergence in the majority of cases suggests recent spread of HIV-1 in this region. This study also presents the first evidence for non-C subtypes in the Indian population with two epidemiologically linked samples remaining unclassified for any existing env subtype. The presence of variant subtypes in Indian patients sheds light on the transmission routes of HIV-1 to India and emphasizes the need to include these sequences in vaccine development strategies.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Giant cell carcinoma of the lung.

A 50-year-old non-smoking, hypertensive female, presenting with superior vena caval compression, was found to have giant cell carcinoma of the lung. She received intensive combination chemotherapy. However she died in the following 36 hours, as a consequence of refractory hypotension.

Antibiotics, Antineoplastic↗
PubMed1995

Effect of some psychoactive drugs on stress induced alteration in plasma corticosterone level.

Psychoactive drugs such as chlorpromazine, fluphenazine, haloperidol, propranolol and diazepam were evaluated for their ability to block stress induced changes in Wistar albino rats. The stress induced changes were monitored as the difference in plasma corticosterone (PCS) levels, before and after the administration of minimum effective doses of psychoactive drugs. Significant results were obtained with diazepam at the dose of 5-10 mg/kg and to a lesser extent with propranolol 20 mg/kg. Other drugs, at their minimum effective doses showed no significant change in plasma corticosterone levels.

Animals↗
PubMed1995

Comparison of two bolus doses of esmolol for attenuation of haemodynamic response to tracheal intubation.

This prospective study was designed to compare the effectiveness of esmolol (either 100 mg or 200 mg) with a placebo in blunting the haemodynamic response to laryngoscopy and intubation. Seventy-five patients of ASA I or II scheduled for routine-surgery were selected and entered into a placebo-controlled study. Patients were randomly allocated to receive placebo, 100 mg or 200 mg of esmolol IV as part of an anaesthetic induction technique. There were no significant differences in the demographic distribution of the patients in the study. There was no statistical difference in the baseline heart rate (HR) and systolic blood pressure (SBP) between the three groups. One minute after the administration of the drug (prior to intubation) the differences in HR between the placebo group and both the 100 mg and 200 mg groups were significant (p < 0.05), and also at 1 min and 2 min following intubation for the 200 mg group (p < 0.05). In the 200 mg group there was a significant decrease, compared with placebo, in SBP at 1 min (p < 0.05) and at 2 min (p < 0.05) after intubation. In this study, adequate haemodynamic control following was obtained with the administration of 200 mg of esmolol.

Adrenergic beta-Antagonists↗
PubMed1994

Damage and mutagenesis of E. coli and bacteriophage lambda induced by oxathiolane and aziridinyl steroids.

lambda-Escherichia coli complexes exhibited remarkable sensitivity to the treatment with test steroidal derivatives in the presence of Cu(II). The decline in plaque-forming units after steroid treatment was more pronounced in complexes with some of the radiation repair-defective mutants of E. coli K-12, i.e., recA, lexA and polA, as compared to uvrA and wild-type strains. The red gene of lambda phage and recA gene of E. coli seem to have a complementary effect on the steroid-induced lesions. An enhanced level of mutagenesis was observed when steroid-treated E. coli cells were transformed with steroid-treated pBR322 plasmid DNA. A remarkable degree of c mutation was also observed when steroid I-treated phage particles were allowed to adsorb on steroid-treated wild-type bacteria. Moreover, the oxathiolane steroid treatment of lambda cI857-E. coli lysogen resulted in prophage induction in nutrient broth even at 32 degrees C. Thus on the basis of these results, the role of SOS repair system in steroid-induced mutagenesis and repair of DNA lesions in E. coli and bacteriophage lambda has been suggested.

Aziridines↗
PubMed1994

Human leukocyte interferon-alpha in cream, for the treatment of genital warts in Asian women: a placebo-controlled, double-blind study.

The purpose of this double-blind, placebo-controlled study was to determine and compare the clinical efficacy and tolerance of human leukocyte alpha-interferon (incorporated 2 x 10(6) IU/g) in hydrophilic cream to cure genital warts. Preselected Asian female patients (n = 150) aged 18-40 years (mean 22.5), with the clinical and biopsy-confirmed diagnosis of genital warts (mean 2.64), predominantly flat vaginal condylomas, were randomly allocated to 3 parallel groups. Each patient was given a coded tube containing 80 g placebo/active preparation with a graduated applicator. Patients were instructed to inject 6 g of the either alloted placebo/active cream deep into the vagina thrice a day for 3 consecutive days (group A) or 4 consecutive days (group B) per week, and if not cured the same treatment was extended to 3 more weeks (maximum 4 weeks active treatment). To assess the clinical efficacy patients were examined on a week-to-week basis. A total clearance of warts (biopsy-confirmed) was evaluated as a complete cure. Patients cured during the treatment were spared further treatment and were requested to visit us after 16 weeks for relapse control. As for the remaining patients, empty tubes were collected, and similarly coded replacement tubes were given for further treatment (in total 588 tubes were used). By the end of the treatment 57.2% lesions (227/397) were eliminated in all the groups: 48% patients in group A, 90% patients in group B, and 10% patients in placebo groups taken as completely cured.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Enhanced stability and potency of novel growth hormone-releasing factor (GRF) analogues derived from rodent and human GRF sequences.

Native human GRF(1-44)-NH2(hGRF44) is subject to biological inactivation by both enzymatic and chemical routes. In plasma, hGRF44 is rapidly degraded via dipeptidylpeptidase IV (DPP-IV) cleavage between residues Ala2 and Asp3. The hGRF44 is also subject to chemical rearrangement (Asn8-->Asp8, beta-Asp8 via aminosuccinimide formation) and oxidation [Met27-->Met(O)27] in aqueous environments, greatly reducing its bioactivity. It is therefore advantageous to develop long-acting GRF analogues using specific amino acid replacements at the amino-terminus (to prevent enzymatic degradation): residue 8 (to reduce isomerization) and residue 27 (to prevent oxidation). Inclusion of Ala15 substitution (for Gly15), previously demonstrated to enhance receptor binding affinity, would be predicted to improve GRF analogue potency. Substitution of [His1,Val2]-(from the mouse GRF sequence) for [Tyr1,Ala2]-(human sequence) in [Ala15,Leu27]hGRF(1-32)-OH analogues completely inhibited (24-h incubation) DPP-IV cleavage and greatly increased plasma stability in vitro. Additional substitution of Thr8 (mouse GRF sequence), Ser8 (rat GRF sequence), or Gln8 (not naturally occurring) for Asn8 (human GRF sequence) resulted in analogues with enhanced aqueous stability in vitro (i.e., decreased rate of isomerization). These three highly stable and enzymatically resistant hGRF(1-32)-OH analogues, containing His1, Val2, Thr/Gln8, Ala15, and Leu27 replacements, were then bioassayed for growth hormone (GH)-releasing activity in vitro (rat pituitary cell culture) and in vivo (SC injection into pigs). Enhanced bioactivity was observed with all three hGRF(1-32)-OH analogues. In vitro, these analogues were approximately threefold more potent than hGRF44, whereas in vivo they were eleven- to thirteenfold more potent.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

Variations in power output of the Piezon-Master 400 ultrasonic endodontic unit.

The present study was undertaken to see if there was any variability in the power output of Piezon-Master 400 ultrasonic files when driven using different generators, tranducers and file holders. The displacement amplitude of the oscillating tip of the file in air was used as a measure of the power output. The results showed that there was considerable variability in the power output of Piezon-Master 400 ultrasonic files of similar size and length when driven using different generators, transducers and file holders. In consideration of this, it is recommended that a calibration device be incorporated in the ultrasonic unit so that the operator will have some knowledge of when the unit is working at its maximum efficiency.

Electric Conductivity↗
PubMed1994

Physical mechanisms governing the hydrodynamic response of an oscillating ultrasonic file.

Ultrasonically driven vibrating files are known to enhance the efficiency of root canal debridement. This paper presents a phenomenological view of the hydrodynamic response of an oscillating ultrasonic file and the relationship between the file response and various physical factors such as file size and curvature, file surface properties, file velocity amplitude, root canal geometry, and the type of irrigant. Relevant hydrodynamic properties include the propensity of a file to produce stable and transient cavitation, steady streaming, and cavitation microstreaming. These relationships were explored by experiment. Sonoluminescence was employed as an indicator of transient cavitation activity and photographic analysis was utilized as a means for detecting steady streaming, microstreaming, and stable cavitation. Measurements failed to indicate any strong correlation between registered driving power and the propensity to produce transient cavitation. Files that were pitted or possessed salient edges were very effective at generating transient cavitation. When observed, transient cavitation activity generally occurred near the tip of the straight file, provided the wall-loading did not inhibit file motion. In all cases studied, steady streaming and stable cavitation were observed to varying degrees, depending on the amount of file to wall contact. Stable cavitation was probably enhanced by the addition of moderate amounts of dissolved gas into the irrigant. Although the imposition of file-wall contact served to inhibit the production of transient cavitation, this action had relatively little effect on the ability of a file to produce a nominal level of streaming, microstreaming, and stable cavitation. The relationship between these hydrodynamic properties and the process of root canal debridement is addressed. Observations suggest that it is not prudent to ascribe enhanced cleaning effects to any one phenomenon, for it is likely that several factors are involved to varying degrees depending on the local conditions of application.

Luminescent Measurements↗
PubMed1994

Some observations on the breakage of ultrasonic files driven piezoelectrically.

The incidence of breakage of Piezon-Master ultrasonic K files were evaluated. Three groups of unused files were subjected to three treatments, namely; free vibration in air without irrigation, free vibration in root canal while minimizing contact with the wall of canal in the presence of irrigation and light filing in root canal with free flow of irrigation. Cavitation produced by files in contact and free of contact with a glass surface was examined in order to observe the relationship between cavitation defects and breakage. In addition, the fractured and unfractured files were examined under a scanning electron microscope for the presence of cavitation pits. The results indicated that more files broke in air. In water, a higher incidence of breakage occurred when files were allowed to freely vibrate while no breakage occurred when the files were used in filing. All files generated cavitation which resulted in pitting of their surfaces. However, it was considered unlikely that the pits contributed to fracture. Fatigue cracks which could be the result of the manufacturing process were observed at some of the corners of the cross sections of the fractured files and could be the main contributory factor to fracture.

Chemical Phenomena↗
PubMed1994

Diode dosimetry of 103Pd model 200 seed in water phantom.

The relative dose distribution around the 103Pd model 200 implant seed was measured with a computerized data acquisition system employing a p-n junction silicon diode immersed in a water phantom. Data are acquired in polar coordinates by computer control of (1) the diode distance from the seed center and (2) the rotation angle of seed about a transverse axis. Transverse axis data are compared with thermoluminescent dosimeter (TLD) measurements and a Monte Carlo calculation by others.

Brachytherapy↗
PubMed1994

Topical 0.3% and 0.5% podophyllotoxin cream for self-treatment of molluscum contagiosum in males. A placebo-controlled, double-blind study.

BACKGROUND: Molluscum contagiosum is generally a self-limiting benign skin disease that affects mostly children and young adults. OBJECTIVE: The purpose of this multicenter, double-blind, placebo-controlled study was to compare the clinical efficacy and tolerance of 0.3% and 0.5% podophyllotoxin in a hydrophilic cream base to cure molluscum contagiosum in Asian males. METHODS: Preselected patients (n = 150), age range 10-26 years (mean: 15.4), harboring 1,125 lesions (mean: 7.5), with size ranging from 2 to 8 mm in diameter (mean spot size 3.2 mm) and biopsy-proven diagnosis of molluscum contagiosum, were randomly allocated to three parallel groups. Twenty-four (16%) patients had atopic dermatitis. Patients self-administered placebo, 0.3% or 0.5% podophyllotoxin cream, twice daily for 3 consecutive days, and if total elimination was not achieved with one trial (6 topical applications), the same treatment was extended to 3 more weeks (24 topical applications in 4 weeks). The duration of the study was 12 weeks with 6 months (on monthly basis) follow-up. By the end of the treatment 80 patients (52, 92 and 16% patients in the 0.3%, 0.5% and the placebo groups, respectively) were evaluated as completely cured. During the treatment 92 patients (61.3%) did not complain of any allergic or localized adverse symptoms. Tolerable moderate to mild frequent side effects were pruritus (20.6%) and erythema (18%), with no dropouts. No recurrence was seen after 9 months of follow-up. Response to the trial medications appeared to be directly proportional to the concentration of podophyllotoxin (p < 0.001). Self-medication was well accepted by all the patients. It was concluded that the 0.5% podophyllotoxin cream preparation was more efficacious than the 0.3% incorporation (p < 0.001) and can be considered a safe, home-based first line of therapy to cure molluscum contagiosum.

Adolescent↗
PubMed1994

Ca2+ preconditioning elicits a unique protection against the Ca2+ paradox injury in rat heart. Role of adenosine. Fixed.

Repeated Ca2+ depletion and repletion of short duration, termed Ca2+ preconditioning (CPC), is hypothesized to protect the heart from lethal injury after exposing it to the Ca2+ paradox (Ca2+ PD). Hearts were preconditioned with five cycles of Ca2+ depletion (1 minute) and Ca2+ repletion (5 minutes). These hearts were then subjected to Ca2+ PD, ie, one cycle of Ca2+ depletion (10 minutes) and Ca2+ repletion (10 minutes). Hearts subject to the Ca2+ PD underwent rapid necrosis, and myocytes were severely injured. CPC hearts showed a remarkable preservation of cell structure; ie, 65% of the cells were normal in CPC hearts compared with 0% in the Ca2+ PD hearts. LDH release was significantly reduced in CPC hearts compared with Ca2+ PD hearts (2.45 +/- 0.18 and 8.02 +/- 0.7 U.min-1 x g-1, respectively). ATP contents of CPC hearts were less depleted compared with the Ca2+ PD hearts (5.9 +/- 0.8 and 3.0 +/- 0.16 mumol/g dry weight, respectively). Addition of the adenosine A1 receptor agonist R-phenylisopropyl adenosine before and during Ca2+ PD provided protection similar to that in CPC hearts, whereas the nonselective adenosine A1 receptor antagonist, 8-(p-sulfophenyl)-theophylline, blocked the beneficial effects of CPC. CPC-mediated protection was aborted when hearts subjected to CPC were treated with pertussis toxin (the guanine nucleotide or G-protein inhibitor). The present study suggests that Ca2+ preconditioning confers significant protection against the lethal injury of Ca2+ PD in rat hearts. Cardioprotection appears to result from adenosine release during preconditioning and by Gi-protein-modulated mechanisms.

Adenosine↗
PubMed1994

Pattern of malignant bone tumour in northern areas of Pakistan.

A review of 280 primary malignant bone tumours diagnosed during 1984-1988 is presented. These constituted 3.14% of all malignant tumours. Male to female ratio was 2.3:1. Majority of these patients presented with rapidly growing mass, pain and deformity. Histologically, osteosarcoma was the most frequent (36.4%) primary malignant tumour. Male to female ratio was 3.31:1. More than 49% of these cases were in their second decade of life. In females the greatest frequency was in 10-15 years and in males 16-20 years age groups. Femur was the most frequent site. Other common malignant bone tumours included chondrosarcoma (22.1%), plasma cell myeloma (15.0%) and Ewings's sarcoma (8.6%). Miscellaneous cases of fibrosarcoma, chrodoma, adamentinoma and ameloblastoma were also seen. This study outlines the frequency, symptomatology and histological pattern of various malignant bone tumours in northern areas of Pakistan.

Adolescent↗
PubMed1994

Comparative anthelminthic efficacy and safety of Caesalpinia crista seed and piperazine adipate in chickens with artificially induced Ascaridia galli infection.

The antiascarid activity of Caesalpinia crista Linn. seeds, popularly known as Karanjwa, was evaluated in chickens of the Fumi breed, suffering from artificially induced Ascaridia galli infection. Eggs per gram (EPG) counts were determined in the droppings of chickens prior and after treatment with powdered C. crista at doses of 30, 40 and 50 mg/kg of body weight along with its extracts in water and methanol in amounts representing 50 mg/kg of crude powder. The crude drug at the dose rates of 40 and 50 mg/kg and its methanol extract induced a significant (P < 0.001) effect on post-treatment days 10 and 15 while the 30 mg/kg dose was efficacious (P < 0.05) on day 15 only. However, the aqueous extract did not show significant results. These results suggest that a 50 mg/kg dose of C. crista seed powder, its equivalent methanolic extract and piperazine (200 mg/kg) are equieffective in treating the ascarid infection of poultry. The crude C. crista powder appears to be potent and safer than its methanol extract on the basis of the side effects observed.

Animals↗