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Biomedical subjects

T Mahmood

Publications and source records attributed to T Mahmood.

At least 19 recordsLinked to original sources
PubMed2003

A study to validate the colonoscopy simulator.

BACKGROUND: The aim of this study was to investigate the relation between clinical experience and performance with regard to colonoscopic procedures performed on the HT Immersion Medical Colonoscopy Simulator. The hypothesis is that the performance of novice, intermediate, and experienced operators is different on simulators, just as it is on real patients. METHODS: 25 Postgraduate doctors were recruited and divided into three groups according to their level of colonoscopic experience. Candidates were asked at random to perform colonoscopy on module 3 or 4 of the HT Immersion Medical Colonoscopy Simulator. Modules 3 and 4 have built-in complex loops, and can demonstrate the candidate's ability either to avoid or undo the loop. Candidates in the first group, termed "novice," each had performed fewer than 10 colonoscopies and included four preregistration house officers (PRHOs), five specialist trainee resistrars (SpRs) and two consultants. This novice group had completed 80 episodes among them. In the second group, termed "intermediate," each candidate had performed between 11 and 100 colonoscopies, and the candidates included five SpRs and two research fellows. This intermediate group had completed 65 episodes. Members of the third group, termed "experienced" each had performed more than 101 colonoscopies, and included one SpR and six consultants. This experienced group had completed 45 episodes between them. A time result of 3,600 s (1 h) was used to denote perforation. RESULTS: The experienced group were shown to perform better than the intermediate group, which in turn performed better than the novice group. The assessment was based on multiple factors including time taken to complete the test, percentage of the colonic mucosa visualized, incidence of colonic perforations, and path length used. The results were highly significant statistically for all these factors ( p < 0.000) except in path length used. CONCLUSIONS: This study demonstrated that operators who differ in terms of their clinical experience and technical ability also differ in their performance of simulated colonoscopy. Thus, the findings have shown the simulator technology to be a powerful discriminator of manipulative skills in colonoscopy. The clinical differences that exist between novices and experts in terms of experience and technical expertise in endoscopic procedures are reflected by statistically significant differences in performance on the simulator. It is therefore reasonable to argue that improving proficiency on the simulator may translate into improvements in clinical practice. This study has validated the use of the HT Medical Immersion Colonoscopy Simulator to discriminate among subjects with different levels of experience.

Colonoscopy↗
PubMed2003

RFLP linkage analysis and mapping genes controlling the fatty acid profile of Brassica juncea using reciprocal DH populations.

An RFLP linkage map, comprising 300 linked and 16 unlinked loci, was constructed using reciprocal DH populations of Brassica juncea. The linked loci were organized into 18 linkage groups and seven unlinked segments, covering a total map distance of 1,564 cM. The A and B genomes were identified. The chi(2) test showed that 96.1% of the common intervals in the two populations differed non-significantly for recombination fractions, thus strongly suggesting the absence of sex-based differences for recombination fractions in B. juncea. Two QTLs, E(1a) and E(1b), significantly affected erucic acid content, and individually explained 53.7% and 32.1%, respectively, and collectively 85.8% of the phenotypic variation in the population. The QTLs E(1a) and E(1b) showed epistasis, and the full model including epistasis explained nearly all of the phenotypic variation in the population. The QTLs E(1a) and E(1b) were also associated with contents of oleic, linoleic and linolenic acids. Three additional QTLs (LN(2), LN(3) and LN(4)) significantly influenced linolenic acid content. The QTL LN(2) accounted for 35.4% of the phenotypic variation in the population. Epistatic interactions were observed between the QTLs E1a and LN(2). The stability of the detected QTLs across years and locations, and breeding strategies for improving the fatty acid profile of B. juncea, are discussed.

Canada↗
PubMed2003

Molecular mapping of seed aliphatic glucosinolates in Brassica juncea.

An RFLP genomic map with 316 loci was used to study the inheritance of aliphatic glucosinolates in Brassica juncea using doubled-haploid (DH) populations developed from a cross between RLM-514, an agronomically superior non-canola quality B. juncea (high erucic acid and high glucosinolates), and an agronomically poor canola quality B. juncea breeding line. Two QTLs (GSL-A2a and GSL-A2b) associated with 3-butenyl were consistent across years and locations, and explained 75% of the phenotypic variance in the population. Three QTLs (GSL-A2a, GSL-F, GSL-B3) affected 2-propenyl and explained 78% of the phenotypic variance in the population. For total aliphatic glucosinolates, five QTLs explained 30% to 45% of the total phenotypic variance in the population in different environments. Several QTLs (GSL-A7 and GSL-A3) were highly inconsistent in different environments. Major QTLs (GSL-A2a and GSL-A2b) associated with individual glucosinolates were non-significant for total aliphatic glucosinolates. A marker-assisted selection strategy based on QTLs associated with individual glucosinolates rather than total aliphatic glucosinolates is proposed for B. juncea.

Chromosome Mapping↗
PubMed2002

Fallopian tube ciliary beat frequency in relation to the stage of menstrual cycle and anatomical site.

BACKGROUND: The cyclical changes in ciliary structure and motion within the human Fallopian tube are well documented. Previous investigators have studied ciliary beat frequency (CBF) in relation to menstrual cycle and anatomical site, but with conflicting results. METHODS: Using a technique that records variations in light intensity, we have studied the changes in CBF in relation to the menstrual cycle and anatomical site. Fallopian tubes were collected from 26 women who underwent hysterectomy for benign conditions. Menstrual history, hormone profile and endometrial biopsy results were used to determine the stage of the cycle. Fourteen women were in the proliferative phase, and 12 women in the secretory phase. RESULTS: Mean CBF for all subjects was 5.3 plus minus 0.2 Hz. There was no significant difference in CBF in relation to anatomical site. In the fimbrial region the ciliary beat was faster in the secretory (5.8 plus minus 0.3 Hz) as compared with the proliferative phase (4.9 plus minus 0.2 Hz), P < 0.02. CONCLUSIONS: It is possible that this increase in fimbrial CBF may contribute to ovum retrieval and transport after ovulation. However, the reproductive significance of the changes in CBF in relation to the menstrual cycle needs further investigation.

Cilia↗
PubMed2002

Sumatriptan challenge in bipolar patients with and without migraine: a neuroendocrine study of 5-HT1D receptor function.

An association between bipolar disorder and migraine has been lately recognized and an abnormality of central serotonergic function is suggested as the underlying neurophysiological disturbance. To examine the role of serotonin in bipolar disorder and migraine, we used the neuroendocrine challenge paradigm, and we chose sumatriptan, a 5HT1D agonist, as the pharmacological probe. We studied nine bipolar patients with migraine, nine bipolar patients without it, seven migraine patients, and nine matched normal controls. A post-hoc analysis showed subsensitivity of serotonergic function, reflected in a blunted growth hormone response to sumatriptan challenge in bipolar patients who also suffered from migraine.

Adult↗
PubMed2002

Effect of angiotensin II on ion transport across human Fallopian tube epithelial cells in vitro.

Angiotensin II type 1 receptors have been identified in Fallopian tube epithelia. Polarized confluent human Fallopian tube epithelial cell cultures were used under short-circuit conditions to study the actions of angiotensin II on electrogenic ion transport. The results demonstrate that angiotensin II increases baseline short-circuit current, implying a net transport of negatively charged ions from a basal to apical direction. This effect was inhibited by the selective angiotensin II type 1 receptor antagonist losartan. The effects of angiotensin II on short-circuit current were rapid in onset, brief in duration, and although less than those achieved with ATP, similar in amplitude to those described for other epithelia with angiotensin II. These findings reflect a significant retention of function for these cells in monolayer culture. Immunohistochemistry using the antibody 6313/G2, which is directed against a specific sequence in the extracellular domain of the angiotensin II type 1 receptor, confirmed that the receptor was retained in cultured cells. The results indicate that angiotensin II plays a role in regulating the composition of Fallopian tube secretions.

Adult↗
PubMed2002

Role of dexamethasone in acute bacterial meningitis in adults.

OBJECTIVE: To evaluate the role of dexamethasone as adjunctive therapy in adult acute bacterial meningitis (ABM) in two groups of patients treated with antibiotics alone or a combination of antibiotics and dexamethasone. DESIGN: Systematic sampling interventional open cohort study. SETTING: Department of Medicine (Medical Unit II), Jinnah Postgraduate Medical Centre, Karachi. PATIENTS: Sixty eight patients aged 12-85 years admitted in Medical Unit II and diagnosed to have ABM. Patients were divided into two groups. Group A received anti-microbial therapy for 14 days (a combination of benzyl penicillin 6 million units I/V 6 hourly and chloramphenicol 1 gm I/V 6 hourly) and group B received the same antimicrobial therapy with dexamethasone 0.6 mg/kg/day in 3 divided doses for 4 days. MAIN OUTCOME MEASURES: Differences in mortality and morbidity in the two groups and differences in the CSF inflammatory parameters between the two groups of patients. RESULTS: There was early resolution of fever, headache and altered consciousness in group B as compared to group A. Cranial nerves involvement was lower in group B. There was no difference in the occurrence of other focal neurological deficits between the two groups. CSF inflammatory parameters (glucose, protein and WBC count) were significantly better in group B by day 5. No complications attributable to dexamethasone were seen in group B. CONCLUSION: There was early resolution of symptoms and CSF inflammatory parameters in the group that received dexamethasone as adjuvant therapy. Mortality was lower in the group treated with dexamethasone but the difference was not statistically significant. Dexamethasone should be administered to all adults patients with ABM.

Adolescent↗
PubMed2002

Amoebic versus pyogenic liver abscess.

OBJECTIVES: To study the differences between the clinical presentation and complications of amoebic and pyogenic liver abscess. To correlate the diagnostic significance of Entamoeba Indirect Haemagglutination test (E.IHA) in establishing the diagnosis of amoebic liver abscess. DESIGN: Open cohort observational study. SETTING: Department of Medicine (Medical Unit II) Jinnah Postgraduate Medical Centre, Karachi. PARTICIPANTS: Fifty two patients aged 13-70 years admitted in Medical Unit II and diagnosed to have liver abscess. INTERVENTIONS: Group A comprised of patients clinically diagnosed to have amoebic liver abscess and received Metronidazole 500mg iv x 8 hourly for atleast 10 days or more if patient developed complications. Group B comprised of patients diagnosed to have pyogenic abscess and received Cefotaxime 1g iv x 8 hourly for the same duration or more if complicated (antibiotic reviewed in accordance with culture and sensitivity report). MAIN OUTCOME MEASURES: Differences in the clinical presentation, complications and diagnostic parameters between the two groups of patients. RESULTS: It was not possible to differentiate between amoebic and pyogenic liver abscess on clinical grounds, routine investigations and imaging techniques. Aspiration of pus, especially if the abscess was multiple, was most helpful in differentiating the two types of abscesses. Serological test of E.IHA was highly specific and sensitive for amoebic liver abscess. CONCLUSION: Majority of liver abscesses in Karachi are due to Entamoeba Histolytica. Pyogenic abscess though less frequent, must be excluded by pus aspiration and culture and sensitivity. E.IHA is a good rapid method of discriminating between the two types of abscesses.

Adolescent↗
PubMed2001

The different behaviors of skeletal muscle cells and chondrocytes on PEGT/PBT block copolymers are related to the surface properties of the substrate.

The attachment, proliferation, morphology, and differentiation of two cell types-skeletal muscle cells and chondrocytes-were investigated on different compositions of poly(ethylene glycol) and poly(butylene terephthalate) segmented block copolymers. Four weight percentages (40, 55, 60, and 70%) and two different molecular weights (300 and 1000 Da) of poly(ethylene glycol) were tested. Varying the weight percentage and molecular weight of poly(ethylene glycol) resulted in different behaviors for skeletal muscle cells and chondrocytes. The attachment of skeletal muscle was the highest (similar to tissue culture polystyrene) when copolymers containing 55 wt % of poly(ethylene glycol) were used, regardless of the poly(ethylene glycol) molecular weight. Maximum proliferation and differentiation of skeletal muscle cells was achieved when copolymers containing 55 wt % and 300 Da molecular weight of poly(ethylene glycol) were used. In contrast, the weight percentage and molecular weight of poly(ethylene glycol) had no significant effect on chondrocyte attachment and proliferation; the attached chondrocytes retained a differentiated phenotype only when a 70 wt % of poly(ethylene glycol) was used. Cell behavior was correlated with the surface properties of the copolymer films, as indicated by contact-angle measurements. These results suggest that an optimized wt % and molecular weight of poly(ethylene glycol) will be useful depending on the specific cell type.

Animals↗
PubMed2001

Serotonin and bipolar disorder.

With the emergence of specific pharmacological probes for various serotonin (5-HT) receptors and radio-ligands for central 5-HT, it has now become possible to investigate its role in the pathogenesis of bipolar disorder more closely. This paper critically reviews the scientific literature regarding the relationship between bipolar disorder and serotonergic systems. The evidence suggests that central serotonergic activity is reduced in the depressive phase of bipolar disorder. Similar findings have been reported in bipolar patients when euthymic, indicating that that lower 5-HT activity could be a trait marker for bipolar disorder. Findings reported in the manic phase of this illness are inconsistent.

Biomarkers↗
PubMed2001

The effect of cAMP on ion transport in Fallopian tube epithelial cells in vitro.

The coupled movement of ions and water across epithelia determines the composition and volume of fluid present in the lumen of organs. The second messenger cAMP is important in effecting electrolyte and water transport in many transporting epithelia; however, its role in Fallopian tube transport is uncertain. We have conducted electrophysiological studies on Fallopian tube epithelial cell monolayers in Ussing chambers and have demonstrated that exogenously added cAMP and agents that generate its intracellular production results in an increase in short-circuit current consistent with the transport of net electrical charge from a basal to mucosal direction. In contrast to the known effects of ATP in this tissue, the increase in short-circuit current was not explicable in terms of electrogenic chloride secretion as it was not affected by the chloride channel inhibitors, 4-acetamido-4'-isothiocyanostilbene-2,2-disulphonic acid 1 mmol/l (SITS) and frusemide. Instead the current was reduced by the sodium channel inhibitor, amiloride, and was therefore, in part, explicable in terms of electrogenic Na+ absorption. These findings will enhance our understanding of the physiological mechanisms responsible for human Fallopian tubal fluid formation and composition.

Adenosine Triphosphate↗
PubMed2001

Ultrasonographic appearance of Ascaris lumbricoides in the small bowel.

Roundworm infestation, one of the most common helminthic diseases worldwide, is caused by Ascaris lumbricoides, one of the largest parasites that infests the human bowel. A lumbricoides is virtually universal at some stage of childhood in semitropical and tropical regions. This study describes our experience with the ultrasonographic appearance of intestinal ascariasis in 84 patients, 2.5 to 42 years of age, examined over 2 years beginning October 1997. The patients' conditions ranged from acute intestinal obstruction to no clinical features pertaining to obstruction. Ultrasonographic examination was performed with an Echocee power Doppler real-time unit with a variable-frequency 3.7-MHz convex, 7.5-MHz linear probe. In longitudinal section the Ascaris worm presented as a linear intraluminal mass with 3 or 4 linear echogenic interfaces; in the cross section, it was round, sometimes appearing as a "target" sign. Some worms also showed serpentine movements. Sonographic examination of the patients in the left lateral decubitus position after ingestion of water improved detection and visualization of the worms in some cases. It is concluded that A lumbricoides in the small bowel has a sonographic appearance that can be recognized by the wary observer.

Adolescent↗
PubMed2000

Angiotensin II in human seminal fluid.

The renin-angiotensin system (RAS) and angiotensin II are important in sperm function and male fertility. Angiotensin II type I (AT1) receptors have been identified in developing and ejaculated human spermatozoa, and angiotensin can stimulate sperm motility, the acrosome reaction and binding to the zona pellucida. However, there is little information on the availability of the hormone to spermatozoa during the reproductive process. Seminal plasma and blood plasma obtained from normal and subfertile subjects was extracted, and angiotensin content was analysed by radioimmunoassay. Values obtained for blood angiotensin II were within the normal range at 16.0 +/- 3.1 pg/ml (mean +/- SEM). Values for seminal plasma were usually 3-5 fold higher, at 51.6 +/- 9.3 pg/ml (n = 34, P < 0.0001). High performance liquid chromatography analysis showed that approximately 80% of the immunoreactive angiotensin was attributable to angiotensin II itself. However, seminal plasma angiotensin II concentrations were not correlated with blood angiotensin II, sperm concentration or sperm motility. The results show that immunoreactive angiotensin from a source other than the circulation is available to spermatozoa in human ejaculates. The results are consistent with the concept that angiotensin II has an important role in male fertility.

Angiotensin II↗
PubMed1999

Comparison of the growth patterns and morphological characteristics of mechanically and enzymatically isolated fallopian tube epithelial cells.

This study set out to compare the growth patterns and morphological characteristics of human fallopian tube epithelial cells isolated: (1) mechanically; and (2) enzymatically. Cells were cultured in medium supplemented with fetal bovine serum and antibiotics and their epithelial nature was established by immunocytochemistry for cytokeratins. Primary cultures were polygonal in shape with centrally located nuclei, irrespective of the isolation method. Cells isolated enzymatically exhibited a higher growth rate, but the survival rate was poor after more than 2-3 passages. Mechanical isolation gave a lower yield of cells, but had a higher survival rate when sub-cultured, even beyond 8 passages. Thus, mechanically isolated cells might be useful for longer term cultures, whereas enzymatically isolated cells are best only for short-term work.

Adult↗
PubMed1999

Axial flow fields in cuffed end-to-side anastomoses: effect of angle and disease progression.

OBJECTIVE: to visualise the axial flow fields in standard and cuffed end-to-side anastomoses (ESA). DESIGN: in vitro experiments using a flow rig, custom-built glass models and frame-by-frame video analysis of flow patterns in standard and cuffed ESA. SUBJECTS: glass models of standard or cuffed (1 cm or 2 cm high) ESA of angles 15, 30, 45 and 60 degrees. RESULTS: the cross-sectional area of standard ESA is much smaller than that of ESA between graft and cuff. The size of the vortex in the anastomotic zone of both standard and cuffed ESA increased with increasing ESA angle and cuff height, but did not change with flow rate. The presence of the vortex maintains a zone of flow separation and low shear at the heel of standard and graft/cuff anastomoses. CONCLUSIONS: the observations explain the clinical findings of intimal hyperplasia (IH) at the heel of PTFE/cuff anastomoses. The improved patency rates of cuffed ESA may be due not to decreased IH, but to an increased ability of the cuff to accommodate IH before causing a significant stenosis.

Anastomosis, Surgical↗