Search PubMed⌕ Search

Biomedical subjects

M Saeed

Publications and source records attributed to M Saeed.

At least 145 records · Page 8Linked to original sources
PubMed1991

A clinicopathological analysis of ovarian tumours.

We performed a retrospective analysis of patients with ovarian tumors who were admitted to the Aga Khan University Hospital from January 1985 to December 1989. Sixty one cases were reviewed. Mean age of the whole group was 44 years. Majority of the patients presented with abdominal pain and distention. Most frequent physical finding was a palpable mass on pelvic or abdominal examination. Overall these patients had a higher incidence of breast cancer than expected in the general population. Two-thirds of the tumors were malignant. Comparison of the patients with malignancy against those with benign tumors failed to show any correlation with parity. Majority of the patients with malignant disease were above forty and had ultrasound showing a cystic mass over 10 cms in size. Cancer was mostly epithelial in origin, with widespread disease (stage III or IV) at the time of presentation. Benign tumors, mostly of germ cell type, were predominantly seen in patients under the age of forty with ultrasound showing cystic mass of any size from under 5 cms to over 10 cms.

Adult↗
PubMed1990

Predicting death from initial disease severity in very low birthweight infants: a method for comparing the performance of neonatal units.

OBJECTIVES: To investigate (a) which clinical variables and physiological measures of disease severity best predict death in very low birthweight infants and (b) their use in comparing mortality between two neonatal units. DESIGN: Retrospective study of two cohorts of very low birthweight infants from overlapping time periods who received mechanical ventilation. SETTING: Two neonatal intensive care units (hospitals A and B). SUBJECTS: 262 Very low birthweight infants, 130 in hospital A, 132 in hospital B. MAIN OUTCOME MEASURE: Death in hospital. RESULTS: In hospital A the mean level of oxygenation in the first 12 hours of life, whether measured as inspired oxygen requirement (FIO2), arterial/alveolar oxygen (a/AO2) ratio, or alveolar-arterial oxygen difference (A-aDO2), was more closely associated with death than any of four "traditional" risk factors: low birth weight, short gestation, the diagnosis of respiratory distress syndrome, and male sex. Mean pH in the first 12 hours was as strongly associated with death as birth weight. Multiple logistic regression models were derived in infants from hospital A using the four traditional risk factors with measures of oxygenation and pH. The validity of each model was then tested in infants from hospital B. The model based on the four traditional risk factors alone predicted death in hospital B with only 31% sensitivity. Adding mean a/AO2 ratio and mean pH increased its sensitivity to 75%, and when mean a/AO2 ratio was replaced by mean FIO2 its sensitivity increased further to 81%. Based on crude mortality rates alone, the odds of death in hospital A versus hospital B were 0.67 (95% confidence interval 0.37 to 1.23). After correcting for traditional risk factors and mean FIO2 and mean pH, however, the odds of death in hospital A increased to 3.27 (1.35 to 7.92; p less than 0.01). This increased risk persisted after adjusting for the time difference between each cohort. CONCLUSIONS: Crude comparisons of hospital mortality can be highly misleading. Reliable assessment of neonatal outcome is impossible without correcting for major risk factors, particularly initial disease severity. International agreement on a minimum core dataset of clinical and physiological information could improve neonatal audit and help to identify effective treatments and policies.

Gestational Age↗
PubMed1990

Effects of nicardipine, a calcium antagonist, on myocardial salvage and high energy phosphate stores in reperfused myocardial injury.

The current study determined the effectiveness of nicardipine, a 1,4-dihydropyridine calcium antagonist, in preserving reperfused myocardium in a cat model of temporary coronary occlusion and ascertained if replenishment of myocardial phosphate stores during reperfusion as defined by phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy was indicative of salvage. Twenty open chest, anesthetized cats were studied with use of a snare ligature around the proximal left anterior descending coronary artery, with a coil sutured to the epicardial surface overlying the distribution of the artery. Peak areas of phosphocreatine, inorganic phosphate and adenosine triphosphate (ATP) NMR signals were measured during 1 h of occlusion followed by 1.5 h of reperfusion. Infarct size and jeopardy area were determined in vitro by simultaneous infusion of phthalocyanine blue dye and triphenyltetrazolium chloride into the aorta and the left anterior descending coronary artery, respectively, after 5 h of myocardial reperfusion. Nicardipine-treated and control groups had similar jeopardy area values (41.2 +/- 1.6% versus 47.4 +/- 3.1% of the left ventricle), but infarct area was significantly reduced in the nicardipine-treated group (3.2 +/- 1.1% versus 24.9 +/- 7.5% of jeopardy area, p less than 0.01). High energy phosphate compounds remained markedly altered during reperfusion in both groups. No significant improvement in phosphocreatine or inorganic phosphate recovery was observed in animals pretreated with nicardipine despite an 87% reduction in infarct size. Myocardial ATP was greater during reperfusion in the nicardipine-treated compared with the control group (average over initial 90 min of reperfusion 58 +/- 6% versus 46 +/- 3% of baseline values, p less than 0.05), suggesting improved recovery of ATP. However, the measured levels of high energy phosphate compounds during reperfusion and their ratios did not correlate with infarct size and thus were not predictive of myocardial salvage.

Adenosine Triphosphate↗
PubMed1990

Chloroplastic regulation of apoplastic alpha-amylase activity in pea seedlings.

Photobleaching of pea (Pisum sativum L.) seedling leaves by treatment with norflurazon (San 9789) and 7 days of continuous white light caused a 76- to 85-fold increase in the activity of the primary alpha-amylase, a largely apoplastic enzyme, over normally greening seedlings. Levels of chlorophyll were near zero and levels of plastid marker enzyme activities were very low in norflurazon-treated seedlings, indicating severe photooxidative damage to plastids. As levels of norflurazon or fluence rates were lowered, decreasing photobleaching of tissues, alpha-amylase activity decreased. Levels of leaf beta-amylase and starch debranching enzyme changed very little in norflurazon-treated seedlings. Infiltration extraction of leaves of norflurazon-treated and normally greening seedlings indicated that at least 57 and 62%, respectively, of alpha-amylase activity was in the apoplast. alpha-Amylase activity recovered from the apoplast of photobleached leaves of norflurazon-treated seedlings was 18-fold higher than that for green leaves. Inhibitors of photosynthesis (DCMU and atrazine) and an inhibitor of chlorophyll accumulation that does not cause photooxidation of plastid components (tentoxin) had little effect on levels of alpha-amylase activity, indicating norflurazon-caused loss of chlorophyll and lack of photosynthesis did not cause the large induction in alpha-amylase activity. An inhibitor of both abscisic acid and gibberellin synthesis (paclobutrazol [PP333]) and an analog of norflurazon which inhibits photosynthesis but not carotenoid synthesis (San 9785) caused only moderate (about five-fold) increases in alpha-amylase activity. Lincomycin and chloramphenicol increased alpha-amylase activity in light grown seedings to the same magnitude as norflurazon, indicating that the effect of norflurazon is probably through the destruction of plastid ribosomes. It is proposed that chloroplasts produce a negative signal for the regulation of the apoplastic alpha-amylase in pea.

Journal Article↗
PubMed1990

Amylases in Pea Tissues with Reduced Chloroplast Density and/or Function.

Pea (Pisum sativum L.) tissues with reduced chloroplast density (e.g. petals and stems) or function (i.e. senescent leaves and leaves darkened for prolonged periods) were surveyed to determine whether tissues with genetically or environmentally reduced chloroplast density and/or function also have significantly different amylolytic enzyme activities and/or isoform patterns than leaf tissues with totally competent chloroplasts. Native PAGE followed by electrophoretically blotting through a starch or beta-limit dextrin containing gel and KI/I(2) staining revealed that the primary amylases in leaves, stems, petals, and roots were the primarily vacuolar beta-amylase (EC 3.2.1.2) and the primarily apoplastic alpha-amylase (EC 3.2.1.1). Among tissues of light grown pea plants, petals contained the highest levels of total amylolytic (primarily beta-amylase) activity and considerably higher ratios of beta- to alpha-amylase. In aerial tissues there was an inverse relationship between chlorophyll and starch concentration, and beta-amylase activity. In sections of petals and stems there was a pronounced inverse relationship between chlorophyll concentration and the activity of alpha-amylase. Senescing leaves of pea, as determined by age, and protein and chlorophyll content, contained 3.8-fold (fresh weight basis) and 32-fold (protein basis) higher alpha-amylase activity than fully mature leaves. Leaves maintained in darkness for 12 days displayed a 14-fold (fresh weight basis) increase in alpha-amylase activity over those grown under continuous light. In senescence and prolonged darkness studies, the alpha-amylase that was greatly increased in activity was the primarily apoplastic alpha-amylase. These studies indicate that there is a pronounced inverse relationship between chloroplast function and levels of apoplastic alpha-amylase activity and in some cases an inverse relationship between chloroplast density and/or function and vacuolar beta-amylase activity.

Journal Article↗
PubMed1990

Reversible and irreversible injury in the reperfused myocardium: differentiation with contrast material-enhanced MR imaging.

Thrombolytic agents are being used with increasing frequency to produce reperfusion of acute myocardial infarction in humans. This study was designed to assess the potential of a magnetic resonance (MR) contrast agent, the manganese chelate of N,N'-bis(pyridoxal-5-phosphate) ethylenediamine-N,N'-diacetic acid (DPDP), in differentiating between reversible and irreversible myocardial injury during reperfusion. Ischemia was produced in rats by occlusion of the left coronary artery for either 15 minutes (n = 10) or 2 hours (n = 10), followed in both cases by 30 minutes of reperfusion. Signal intensity (SI) was measured before and after (every 15 minutes for 1 hour) the administration of Mn-DPDP. Prior to intravenous injection of the contrast agent, no significant difference in SI was observed between normal and reversibly or irreversibly injured myocardium. Mn-DPDP produced greater enhancement of SI of the irreversibly injured region compared with normal myocardium. There was no differential enhancement of the reversibly injured region compared with normal myocardium. Thus, Mn-DPDP is useful in discriminating reversible from irreversible injury in reperfused myocardium.

Animals↗
PubMed1989

Ligand stabilization of cholinesterases.

Stabilization of fetal bovine serum (FBS) acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) (AChE) and human butyrylcholinesterase (acylcholine acylhydrolase, EC 3.1.1.8) (BuChE) by ligands and inhibitors was studied as a function of physical and chemical perturbation. Denaturation of AChE occurred as a binary exponential function in the temperature range studied (50-56 degrees C); the slower fraction progressively diminished as the temperature was increased. Inclusion of ligands or inhibitors stabilized AChE as a function of temperature, ligand concentration and time. The rank order in which ligands stabilized AChE was: edrophonium greater than decamethonium greater than pralidoxime chloride much greater than procainamide. BuChE denaturation was retarded by ligands in the order: decamethonium greater than procainamide greater than edrophonium greater than pralidoxime. A plot of the quotient of the fast/slow ratio against the log of the 50% inhibitory concentration (I50) for ligands providing substantial protection yielded a linear relation, suggesting that these compounds stabilized AChE by a common mechanism involving the anionic site of the active center. Urea-induced cholinesterase denaturation was also retarded by these ligands.

Acetylcholinesterase↗
PubMed1989

Prevention of hemodialysis fistula thrombosis. Early detection of venous stenoses.

Venous dialysis pressures were measured consecutively in 168 chronic hemodialysis patients for 265 patient-years of monitored dialysis. Venous dialysis pressure greater than 150 mm Hg measured by the protocol were considered elevated. Seventy-three patients had elevated venous dialysis pressures and 58 agreed to undergo elective venography (fistulogram). Fifty of 58 patients studied (86%) had significant venous stenoses. A combination of percutaneous transluminal angioplasty (PTA) and surgical revision were used to electively treat these stenoses. Early detection and treatment of these stenoses decreased fistula thrombosis and fistula replacement threefold compared with our earlier experiences. Patients with elevated venous dialysis pressure who were venogramed and treated had an occurrence of fistula thrombosis similar to patients with normal dialysis pressure (0.15 and 0.13 episodes per patient year of dialysis respectively, P = NS). In contrast patients with elevated venous dialysis pressure who refused elective fistulogram and treatment averaged 1.4 episodes of thrombosis per patient year of dialysis (P less than 0.001) compared to both other groups). We conclude that elevated venous dialysis pressure is a reliable method of detecting fistula stenoses and that the elective treatment of these stenoses significantly decreases fistula thrombosis and fistula loss.

Angioplasty, Balloon↗
PubMed1989

Nisoldipine as a vasodilator in endothelium-deprived large coronary arteries of isolated working rabbit hearts.

The effect of nisoldipine on the vasoconstrictor effect of histamine on coronary vascular resistance, cardiac performance and myocardial oxygen consumption was determined in this study. In a supported working heart preparation a perfluorochemical emulsion (FC-43) was used a perfusate. To enhance the sensitivity of the large coronary arteries to vasoconstrictor stimuli, the endothelium was removed mechanically from the large coronary arteries. The changes in coronary artery diameter were documented by colour arteriography. Nisoldipine reduced the constriction of coronary arteries and the decrease in coronary flow induced by histamine. Nisoldipine abolished or reduced the decrease in cardiac output, left ventricular end systolic pressure, dP/dt and myocardial oxygen consumption. In the supported working heart preparation, nisoldipine is an effective dilator of large coronary arteries deprived of endothelial lining.

Animals↗
PubMed1989

Interventional uroradiology.

Major interventional uroradiologic techniques including percutaneous nephrostomy, vascular augmentation and reduction procedures, percutaneous cyst aspiration, chronic peritoneal dialysis catheter manipulation and urethroplasty are reviewed. A brief history of the development and techniques for performing these procedures are included. The results of clinical series are assessed and their role in patient management is addressed. The development of these procedures has had a significant impact on patient care by providing effective nonoperative therapy.

Angioplasty, Balloon↗
PubMed1989

Magnetic resonance spectroscopy of the heart. Overview of studies in animals and man.

Magnetic resonance spectroscopy (MRS) has been used effectively in the evaluation of cardiac physiology. Studies have been done at various levels of complexity extending from isolated hearts to man. Correlation of high-energy phosphate compounds with contractile function is achieved by simultaneous or immediate sequential measurement of ventricular contractile function and the phosphorus-31 MR spectra. Studies in isolated hearts have monitored the response to ischemia of normal and hypertrophic hearts and the preservation of myocardial function and high- energy phosphate stores by drugs administered prior to the ischemic event. Regional myocardial ischemia has been evaluated by simultaneous monitoring of myocardial regional segment length by sonomicrometry and regional myocardial 31P MRS in the intact heart of larger animal models. Function and metabolism have been assessed in man by the combined application of cine MRI and 31P MRS acquired with a surface coil.

Animals↗
PubMed1989

Occlusive and reperfused myocardial infarcts: differentiation with Mn-DPDP--enhanced MR imaging.

To assess whether the administration of manganese N,N'-bis(pyridoxal-5-phosphate)ethylenediamine-N,N'-diacetic acid (DPDP) permits differentiation between occlusive and reperfused infarcts, the authors subjected rats to either 6 hours of left coronary artery occlusion (n = 13) or 2 hours of occlusion followed by 4 hours of reperfusion (n = 10) before magnetic resonance (MR) imaging. Electrocardiographic-gated T1-weighted images were obtained before and for 1 hour after injection of 400 mumol/kg of Mn-DPDP. On T1-weighted images obtained before injection of Mn-DPDP. no significant differences in signal intensity were observed between normal and infarcted regions. Use of Mn-DPDP permitted delineation of the area of infarction. The pattern of enhancement in the injured zone was different for occlusive and reperfused myocardial infarcts. In rats with occlusive infarcts, In rats with occlusive infarcts, three well-defined zones were seen. Epicardium and endocardium were enhanced, while the midmyocardial zone was hypointense. The midmyocardial signal intensity gradually increased during the 60 minutes after injection. In rats with reperfused infarcts, the injured area was uniformly and intensely enhanced. Histologic examination confirmed the presence and location of myocardial infarct. Mn-DPDP may improve the detection and delineation of acute myocardial infarcts, demonstrate perfusion of the infarct, and permit discrimination between reperfused and occlusive infarcts.

Animals↗
PubMed1989

Demarcation of myocardial ischemia: magnetic susceptibility effect of contrast medium in MR imaging.

Dysprosium diethylenetriamine-pentaacetic acid-bis (methylamide) (DTPA-BMA), a new nonionic contrast medium for magnetic resonance (MR) imaging, produces signal loss on T2-weighted images because of induced magnetic field gradients. The potential of this agent to delineate myocardial ischemia was investigated in 10 rats with acute (30 minutes) occlusion of the left coronary artery. T2-weighted MR images were acquired before and for 1 hour after intravenous administration of 1 mmol/kg of Dy-DTPA-BMA. Before administration of the contrast medium, signal intensity (SI) in the ischemic region was significantly greater than that in the normal myocardium; however, the borders of the ischemic region were not consistently distinct. The contrast medium caused marked decrease in SI of normal myocardium (18% +/- 3% of the control value), only slight decrease in the jeopardized region (76% +/- 6% of the control value), and no discernible effects on heart rate or blood pressure. Substantial contrast between normal and ischemic myocardium persisted for 1 hour. Moderate signal loss was observed in skeletal muscle. Dy-DTPA-BMA has the potential to demarcate the myocardial area in jeopardy as a region of high signal intensity because it erases signal preferentially in the normal myocardium.

Animals↗
PubMed1988

Povidone-iodine sclerosis of pelvic lymphoceles: a prospective study.

Twelve patients presented for percutaneous catheter drainage of 13 postoperative pelvic lymphoceles. Six patients with 7 lymphoceles were treated with povidone-iodine sclerosis prior to catheter removal. Only 1 lymphocele (which continued to drain large amounts of fluid during and after the sclerosis procedure) recurred. Six patients with 6 lymphoceles had their percutaneous catheters removed without sclerosis. Fluid collections recurred in 3 instances, necessitating repeat percutaneous drainage (2 patients) or surgery (1 patient). Percutaneous therapy is the treatment of choice for patients with postoperative lymphoceles. Povidone-iodine sclerosis is often effective in preventing reaccumulation of fluid once the lymphocele cavity is collapsed.

Adult↗
PubMed1988

Hemodialysis-associated subclavian vein stenosis.

This study was undertaken to evaluate hemodialysis-associated subclavian vein stenosis (SVS) and to clarify treatment of this condition. Forty-seven patients underwent upper arm venography to evaluate fistula dysfunction. Subclavian vein stenosis was documented in 12. Eleven of 12 had elevated venous dialysis pressure (196 +/- 8.9 mm Hg), and six had arm edema. All 12 had previously undergone subclavian cannulation on the side of the fistula. Thirty-five patients showed no evidence of subclavian vein stenosis. Twelve of these 35 patients (mean venous dialysis pressure 113 +/- 2.3 mm Hg) had undergone previous subclavian cannulation on the side of the fistula. The mean age of the fistula at the time of venogram in patients with subclavian vein stenosis was 17.0 months versus 5.8 months in patients with ipsilateral subclavian cannulation without subclavian vein stenosis. Percutaneous transluminal angioplasty (PTA) was performed on 11 of 12 patients with SVS lowering venous dialysis pressure and restoring patency to the fistula in 100%. Lesions recurred in two of 11 patients and were successfully retreated with PTA. We conclude that SVS is a common dialysis problem that is amenable to treatment with PTA. Elevated venous dialysis pressures are a sensitive indicator of this condition.

Angioplasty, Balloon↗
PubMed1988

Lysolecithins as endothelium-dependent vascular smooth muscle relaxants that differ from endothelium-derived relaxing factor (nitric oxide)

The effects of lysolecithin (lysophosphatidylcholine) derived from egg yolk as well as of synthetic lysolecithins with different aliphatic chain lengths on tension development of rabbit aortic strips were investigated. Lysolecithins caused slowly progressing, dose-dependent relaxation that was inhibited by hemoglobin, methylene blue, and nordihydroguiaretic acid. Indomethacin caused no inhibition of relaxation. The degree of relaxation was endothelium-dependent and appeared to be related to the activation of guanylate cyclase [GTP pyrophosphate-lyase (cyclizing), EC 4.6.1.2]. Superoxide dismutase failed to influence relaxation. Lysolecithins with the longest aliphatic chain were the most potent relaxants of aortic strips. The experiments suggest a role of lysolecithins through their weak detergent action on membrane dynamics of endothelial cells, resulting in the production of cyclic GMP and the relaxation of arterial smooth muscle. Lysolecithins differ in several respects from endothelium-derived relaxing factor. Endothelium-derived relaxing factor is an unstable humoral substance released from endothelium and is identical to nitric oxide, itself a labile substance causing vascular relaxation and cyclic GMP accumulation. Lysolecithins may represent a different type of endothelium-dependent muscle relaxant.

Acetylcholine↗