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Biomedical subjects

R Sheikh

Publications and source records attributed to R Sheikh.

14 recordsLinked to original sources
PubMed2006

Efficacy of isoniazid prophylaxis in renal allograft recipients.

The efficacy of isoniazid (INH) prophylaxis in renal allograft recipients who are on long-term immunosuppression in a region highly prevalent for tuberculosis (TB) was studied. INH (300 mg/d in patients weighing more than 35 kg and 5 mg/kg/d in patients with <35 kg body weight) together with Pyridoxine 50 mg/d for 1 year was started in randomly assigned renal allograft recipients. Occurrence of clinical tuberculosis during the initial 2 years posttransplantation was observed in the risk group and patients at no risk. Risks were defined as acute rejection episodes and exposure to antirejection therapy, past history of TB completely or incompletely treated, radiological evidence of past tuberculosis, history of tuberculosis in close contacts. Among 480 patients registered in the study, INH prophylaxis was given to 219 randomly assigned renal allograft recipients. Results were compared among patients developing TB during the initial 2 years posttransplantation in both the groups. Risk factors were analyzed for comparison in both groups. No significant difference was observed in terms of past history of TB, TB in close contacts, episodes of acute rejection during the initial 3 months, and comorbidities such as cytomegalovirus infection, hepatitis C virus infection, and posttransplant diabetes. One patient from the INH group and 10 patients from the non-INH group developed TB during the initial 2 years posttransplantation (P < .0001). None of patients required discontinuation of INH. INH was observed to be safe and effective as a chemoprophylactic agent in renal allograft recipients.

Antitubercular Agents↗
PubMed2005

Dynamic force-sharing in multi-digit task.

BACKGROUND: Dynamic hand grasping implies sophisticated motor coordination. Most knowledge on motor synergies used in grasping is deduced from experiments based on static precision grip. This experiment was aimed at better understanding the mechanisms of finger force-sharing in an active, dynamic hand task under repetitive strain conditions. METHODS: A multi-digit task consisting of holding a cylinder with the digit tips, in which the thumb and the finger opposed each other, was investigated during repetitive unidirectional wrist flexion and extension cyclic motion. Finger and thumb forces and wrist angular position were simultaneously recorded during repetitive wrist motion against 0.3-0.6 Nm load in 10 healthy adults. FINDINGS: Load torques acting during wrist movements produced in-phase increases of the thumb and the finger forces with the wrist extension and the wrist flexion, respectively. Digit forces increased proportionally to the applied load. The alternating rise of thumb and finger forces changed instantaneously at the end of the flexion and extension phases of the movement, respectively. Six subjects predominantly used the index finger, two the middle finger, one the ring finger, and the remaining one used the small finger during wrist flexion against 0.6 Nm to perform the task. Variations among individual finger forces were negatively correlated during the phase of constant rotational velocity of the wrist flexion. Repeated measures ANOVA revealed that the percentage of individual finger contribution to the total fingers' force significantly varied during the wrist flexion (P<0.0001) and among wrist flexion cycles (P<0.0001) in each subject. INTERPRETATION: Variations in finger force-sharing among cycles were not necessitated by task dependent activities, as the task was identical. These findings indicated that motor coordination of repeated multi-finger task allowed redundant solutions in finger force-sharing. The force-sharing variation may reflect a minimal intervention principle of the central nervous system controlling only the goal-directed parameters and might help to prevent muscle fatigue in repetitive tasks through modulation of activity in multi-digit muscles.

Adult↗
PubMed2003

Influence of peg design and cement mantle thickness on pull-out strength of glenoid component pegs.

Fixation of the glenoid component is critical to the outcome of total shoulder arthroplasty. In an in vitro study, we analysed the effect of surface design and thickness of the cement mantle on the pull-out strength of the polyethylene pegs which are considered essential for fixation of cemented glenoid components. The macrostructure and surface of the pegs and the thickness of the cement mantle were studied in human glenoid bone. The lowest pull-out forces, 20 +/- 5 N, were for cylindrical pegs with a smooth surface fixed in the glenoid with a thin cement mantle. The highest values, 425 +/- 7 N, were for threaded pegs fixed with a thicker cement mantle. Increasing the diameter of the hole into which the peg is inserted from 5.2 to 6.2 mm thereby increasing the thickness of the cement mantle, improved the mean pull-out force for the pegs tested.

Arthroplasty, Replacement↗
PubMed2001

Prognostic significance of the labeling of Adnab-9 in pancreatic intraductal papillary mucinous neoplasms.

BACKGROUND: Pancreatic intraductal papillary mucinous neoplasms (IPMN), morphologically resembling colonic adenomas, often have an indefinable malignant potential. We used a monoclonal antibody (MAb) raised against colonic adenomas, Adnab-9, to identify patients with a better prognosis. METHODS: We assessed Adnab-9-labeled sections of these neoplasms from 50 patients, 13 pancreatic adenocarcinomas, and 32 colonic adenomas using standard immunohistochemical techniques. RESULTS: 26% of the IPMNs labeled with Adnab-9 as compared to 0% of pancreatic ductal cancers or surrounding benign tissues, (p < 0.001) and 53% of adenomas (p < 0.025). Labeling in IPMNs was usually seen in the noninvasive epithelium suggesting that Adnab-9 is a premalignant marker in these lesions. Labeling of invasive IPMN's identified a group of patients with a superior overall survival (p = 0.027). CONCLUSION: Adnab-9 labeling-characteristics appear similar for both IPMNs and adenomatous polyps, suggesting that they are analogous lesions. Adnab-9 labeling may also be a useful prognostic marker for invasive intraductal papillary mucinous neoplasms.

Adenocarcinoma, Mucinous↗
PubMed1998

Gastro-oesophageal reflux disease in primary care: an international study of different treatment strategies with omeprazole. International GORD Study Group.

OBJECTIVE: To assess the efficacy of omeprazole in patients presenting with troublesome reflux symptoms. DESIGN: Randomized, double-blind, parallel-group, placebo-controlled comparison. SETTING: Primary care. SUBJECTS: Patients were recruited using a symptom-based questionnaire for diagnosis of gastro-oesophageal reflux disease. INTERVENTIONS: After endoscopy, patients without endoscopic oesophagitis were randomized to omeprazole 20 mg (Ome20), omeprazole 10 mg (Ome10) or placebo once daily for 4 weeks (n = 261) and those with oesophagitis (except circumferential/ulcerative) were randomized to receive either Ome20 or Ome10 once daily for 4 weeks (n = 277). Patients not symptom-free at 4 weeks received open treatment with Ome20 once daily for a further 4 weeks. Those symptom-free at 4-8 weeks were followed up for 6 months off treatment, to see whether their symptoms recurred. MAIN OUTCOME MEASURE: Complete upper GI symptom relief during week 4 on Ome20 or Ome10 in patients with or without endoscopic oesophagitis. RESULTS: Forty one percent of all patients on Ome20 and 35% on Ome10 reported complete relief from upper GI symptoms during week 4, whilst 73% of the patients on Ome20 and 62% on Ome10 obtained sufficient control. Complete relief during week 4 was reported by 19% of endoscopy-negative patients on placebo, and sufficient control by 35%. Endoscopic healing at 4 weeks occurred in 76% of oesophagitis patients on Ome20 and in 56% on Ome10. After 6 months off treatment, 90% of patients with oesophagitis and 75% of endoscopy-negative patients reported symptomatic relapse. CONCLUSION: Both 10 mg and 20 mg of omeprazole gave effective relief of symptoms, although 20 mg gave superior healing in patients with oesophagitis. After cessation of treatment, symptomatic relapse was rapid and frequent in both endoscopy-positive and endoscopy-negative patients.

Adolescent↗
PubMed1996

Effects of continuous infusion fentanyl citrate on cerebrovascular and systemic prostanoids in postsurgical newborn piglets.

BACKGROUND: Newborns admitted to the intensive care unit undergo multiple painful procedures. Fentanyl citrate (FC) is one of the most commonly used drugs for pain relief in the newborn. Although it has been reported that one of the biological effects of fentanyl is hemodynamic stability, the response of systemic and/or cerebrovascular prostanoids to FC infusions have not been studied. METHODS: To examine the effects of continuous intravenous (IV) infusion of FC on systemic and cerebrovascular prostanoid concentrations, two groups of spontaneously breathing newborn piglets (1-3 days old) were studied. The study group (n = 6) and the control group (n = 8) were respectively given a loading dose of 30 micrograms/kg IV over 15 minutes, immediately followed by a continuous IV infusion of 10 micrograms/kg/hr for 6 hours, or a placebo (PB) solution of 5% dextrose in a similar fashion. Cerebrospinal fluid (0.5 mL) from cisterna magna puncture and blood samples (1.0 mL) from the sagittal sinus vein and carotid artery were collected serially before and after FC or PB infusion for drug and PG determinations. FC was measured by high pressure liquid chromatography (HPLC), and the prostanoids were measured using enzyme immunoassay (EIA) kits. RESULTS: FC infusion induced marked elevations in 6-ketoPGF1 alpha (300%, p < 0.001) and TXB2 (150%, p < 0.001) at 30 minutes, and remained elevated up to 2 hours of infusion. In addition, systemic 6-ketoPGF1 alpha increased by 180% (p < 0.001) and PGE2 concentrations fell dramatically at 30 minutes (87%, p < 0.001) and did not return to normal levels during the infusion time (83% to 81%, p < 0.001 to p < 0.01). CSF 6-ketoPGF1 alpha and TXB2 levels increased by 152% and 80%, respectively (p < 0.001), but PGE2 decreased by 76% (p < 0.001), at 6 hours of infusion. An inverse relationship existed between FC, and sagittal sinus PGE2 levels (r = 0.46, p < 0.03) and systemic PGE2 levels (r = 0.602, p < 0.02). CONCLUSION: The data suggest FC is rapidly transported across the blood brain barrier and the effects on cerebrovascular prostanoids, particularly PGE2 is rapid and prolonged. PGE2 appears to be the primary responsive prostanoid. The magnitude of the response, as evidenced by the early and sharp reductions in systemic and cerebrovascular concentrations, suggest vasoconstriction, with possible adverse effects on organ blood flow and metabolic activity. However, further studies are required to evaluate the effects on organ blood flow and metabolism.

Analgesics, Opioid↗
PubMed1992

Screening of marine algae of karachi for haemagglutinin activity.

Ethanol extracts of 66 species of marine benthic algae, collected from the coastal areas of Karachi, Pakistan, were tested for haemagglutination against human erythrocytes of blood groups A, B, AB and O. Out of 23, 16 and 27 species of green, brown and red seaweeds only 12,5 and 14 species respectively exhibited a positive test for the bioactivity of haemagglutinins i.e. the activity was found in half of the investigated species of Chlorophyta and Rhodophyta but only in one third of Phaeophyta.

Journal Article↗
PubMed1981

The relative conformational stability of the alcohol dehydrogenase alleloenzymes of the fruitfly Drosophila melanogaster.

The effect of temperature on four purified alleloenzymes of the alcohol dehydrogenase (Adhs, Adhf, AdhD and Adhn-5) of the fruitfly Drosophila melanogaster was investigated in detail. Initial-velocity studies showed that the naturally occurring Adhf and Adhs enzymes differed only in their temperature optima, and evidence of kinetic adaptation to high and low temperature was not apparent. All four alleloenzymes denatured irreversibly on heating purified enzyme solutions at pH 6.0. This technique revealed only small differences in thermostability between Adhf and Adhs, although the two mutant enzymes from AdhD and Adhn-5 were considerably more labile. Electrophoresis of the enzymes though a stable transverse temperature gradient proved to be a discriminating and reproducible technique. Enzymes of different net charge were compared on the same polyacrylamide gel. The Adhf enzyme was shown to be significantly less stable than the Adhs enzyme. Subunit interchange was observed at temperatures below the point at which the unfolding occurred. At pH 4.0, the Adhf/Adhs heterodimer was as stable as the Adhs homodimeric enzyme, and more stable than the Adhf homodimer. Adhn-5 and AdhD alleloenzymes were relatively thermolabile. The stability of the alleloenzymes towards urea denaturation was studied by urea-gradient electrophoresis. Only small differences in stability between the Adhf and Adhs enzymes were observed. The AdhD and Adhn-5 mutants were denatured at the same urea concentration, which was much lower than in the case of the wild-type enzymes. Except at pH 4.0, subunit dissociation could not be distinguished from the unfolding of the monomer.

Alcohol Oxidoreductases↗