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Biomedical subjects

S Alam

Publications and source records attributed to S Alam.

At least 91 records · Page 5Linked to original sources
PubMed1984

Emergency valve replacement during acute carditis--case reports.

Two patients are described with acute rheumatic carditis and severe heart failure who failed to respond to aggressive medical treatment with steroids, salicylates, inotropic agents and afterload reduction. In both cases, cardiac catheterization revealed severe aortic and mitral regurgitation with preserved myocardial contractility. Emergency double valve replacement was successfully performed with marked improvement in both patients. The diagnosis and evaluation of the condition, as well as the unique problems confronted in the post-operative course are discussed.

Acute Disease↗
PubMed1983

Correlation of E. coli K-1 bacteremia and capsular polysaccharide antigenemia in acute and chronic infection.

The K-1 polysaccharide is an important virulence factor in human E. coli infections. Using E. coli 016K1, we investigated the kinetic association of bacteremia and K-1 antigenemia in acute lapine and canine infections and in a chronic infection model of neutropenic rats. Additionally, we assessed the presence of K-1 antigenemia in E. coli K-1 bacteremic patients. K-1 was measured by a solid phase radioimmunoassay (RIA) using cross-reactive equine anti-Group B meningococcal IgM. In acute infections, none of the dogs or rabbits developed antigenemia even with a bacteremia of 2 X 10(4) CFU/ml or 5 X 10(5) CFU/ml, respectively. Antigenemia appeared in the rabbit only with an infecting dose of greater than or equal to 5 X 10(8) CFU. In the rat model we observed an initial bacteremia of 10(3) CFU/ml, which increased to 10(6) CFU/ml at 24 hrs. However, antigenemia was most often delayed, appearing in only greater than or equal to 30 hrs postinfection. Percent mortality was directly associated with the degree of bacteremia and antigenemia. In acute human E. coli K-1 bacteremia, 11 of 22 (50%) of patients were positive for K-1 antigenemia. The data demonstrated that K-1 polysaccharide was not usually detectable in the early stages of bacteremia, but occurred only after prolonged infection or very high infecting doses. The RIA to measure K-1 antigenemia would not be a useful diagnostic tool.

Acute Disease↗
PubMed1983

Lack of effect of nitroglycerin on the transmural variation of tissue pH during fixed coronary stenosis.

A new MpH-measuring system was used to investigate the mechanism of action of intravenous NTG on pacing-induced myocardial ischemia during critical stenosis. In ten anesthetized open-chest dogs, two MpH electrodes were placed in a segment supplied by the CCA, one superficial and one deep. Atrial pacing at a rate 50 beats/min higher than baseline was instituted for a period of 10 min (Pacing I). Critical stenosis was then applied to the CCA. Three more similar periods of atrial pacing were instituted during critical stenosis. Pacing II was without any intervention, Pacing III was after the intravenous administration of a bolus of NTG, and Pacing IV was after the intravenous administration of NTG + A. NTG (metamarinol) during critical stenosis and atrial pacing did not alter preload and did not reduce afterload more than critical stenosis and atrial pacing alone. It did not significantly alter flow in the CCA measured by an electromagnetic flow meter. Consequently, the magnitude of fall in both endo- and epicardial MpH during critical stenosis and atrial pacing was no different with or without the administration of NTG. That under these conditions NTG failed to reduce the degree of myocardial ischemia suggests that the beneficial effects of NTG during fixed critical stenosis are determined primarily by its ability to reduce the determinants of myocardial oxygen demand, and not by a direct effect on the ischemic myocardium per se. The study also demonstrates for the first time a significant transmural gradient in MpH in the canine heart, even in the normal resting state.

Animals↗
PubMed1981

Sensitive measurement of endotoxin by radio-rocket immunoelectrophoresis using [125I] Staphylococcus aureus protein A.

Antibody directed against the core glycolipid antigen (CGL) of the mutant Salmonella minnesota Re 595 has been shown to cross-react with endotoxin from bacteria within the group Enterobacteriaceae. Using this cross-reactive CGL antibody we have developed a sensitive (250 pg) radio-rocket immunoelectrophoretic technique to measure endotoxin. We used the principles of rocket immunoelectrophoresis and increased the sensitivity by using 125 I-labelled staphylococcal protein A which serves as a sensitive probe to bind to the Fc portion of the IgG complexed with antigen. The rocket-shaped [125I] protein A labelled immune complexes were detected by radioautography. The sensitivity is 100-fold greater than conventional Coomassie brilliant blue staining. Measurement of CGL was inhibited by normal human serum. However, the assay had the capacity to quantitate endotoxin in buffer extracts of clinically isolated Escherichia coli, Serratia marcescens, Klebsiella pneumoniae but not Pseudomonas aeruginosa. Analysis of various preparations of CGL obtained from different investigators demonstrated wide variation in their immunoreactivity. Because of the significant cross-reaction to detect various endotoxins this method has the potential to measure endotoxemia and assess the immunochemical quality of various endotoxin preparations. Additionally, the technique of using [125I] protein A has wide applicability for the sensitive measurement of other antigens.

Antigens, Bacterial↗
PubMed1981

Anxiolytic effects of low dosage nitrous oxide-oxygen mixtures administered continuously in apprehensive subjects.

We observed the effect of low doses of nitrous oxide on the cardiovascular and respiratory systems, the cortisol output in blood and saliva, and the degree of sedation and analgesia of 20 volunteers. A psychologic screening inventory was also performed. We found nitrous oxide, at low dosage, to be primarily an anxiolytic and not an analgesic or amnesic agent. The nasally inhaled concentrations necessary to induce an anxiolytic effect varied from subject to subject, ranging from 30% to 65% and averaging 35% to 40%. This finding justifies the use of the gas to relieve anxiety instead of nonvolatile parenterally administered psychosedatives and narcotics. Nitrous oxide is preferable because its action is established within several minutes, it is rapidly eliminated at the conclusion of a procedure, and the sensorium is clear after five or six minutes. The gas is simply and safely administered with fail-safe apparatus designed specifically for this purpose. The technic is admirably suited for use in ambulatory care units where minor surgical or dental procedures are performed.

Adolescent↗
PubMed1977

Radiocardiography in clinical cardiology.

Quantitative radiocardiography provides a variety of noninvasive measurements of value in cardiology. A gamma camera and computer processing are required for most of these measurements. The advantages of ease, economy, and safety of these procedures are, in part, offset by the complexity of as yet unstandaridized methods and incomplete validation of results. The expansion of these techniques will inevitably be rapid. Their careful performance requires, for the moment, a major and perhaps dedicated effort by at least one member of the professional team, if the pitfalls that lead to unrecognized error are to be avoided. We may anticipate more automated and reliable results with increased experience and validation.

Heart Aneurysm↗
PubMed1976

The effect of allopurinol on oxypurine excretion in xanthinuria.

In a patient with xanthine urolithiasis secondary to hereditary xanthinuria (xanthine oxidase deficiency), allopurinol administration resulted in a 20 per cent increase in oxypurine excretion and an elevation of the urinary xanthine/hypoxanthine ratio from 4.08 to 6.53. The rise in this ratio suggests that residual xanthine oxidase activity may have been present. It is possible that the excessive re-utilization of hypoxanthine and xanthine in this disease prevents the allopurinol-induced inhibition of de novo purine biosynthesis that is seen in normal subjects.

Allopurinol↗
PubMedDate not supplied

On the mechanism of growth of cells (Bacillus amyloliquefaciens) in the mixed aqueous two-phase system.

The growth of Bacillus amyloliquefaciens in the aqueous two-phase system, made up of polyethylene glycol, dextran, and water, was investigated. Generally, Bacillus partitions in the dextran phase, but the magnitude of the separation depends largely on the overall composition of polymers in the phase system. The kinetics of growth of Bacillus amyloliquefaciens was studied in the polyethylene glycol-rich continuous phase, dextran-rich dispersed phase, and in the mixed phase. From the kinetic data it appears that increasing the overall polymer composition causes the cells to adsorp at the interface. On the other hand, partition measurements indicate that increasing polymer concentrations make the cell partitioning more one-sided. This anomaly is explained by studying the interfacial adsorption of cells via dynamic surface tension measurements.

Adsorption↗
PubMedDate not supplied

Monoclonal antibodies for treatment of gram-negative infections.

Monoclonal antibody technology has permitted researchers to dissect out the protective antibody response to conserved regions of gram-negative bacillary lipopolysaccharides (endotoxins). Some anticore antibodies can bind to lipid A and have a neutralizing, but not opsonic, activity; these antibodies are usually IgM. IgG antibodies to outer core regions may be weakly opsonic. The outcome of animal protection studies is critically dependent on the choice of challenge organism, dose, timing and rate of antibody administration, and additional factors such as antimicrobial therapy. Protective activity against a wide variety of gram-negative bacillary challenges with the IgM anticore and lipid A reactive antibody, which we have designated E5, is reviewed. Protection in a therapeutic model is demonstrable when the antibody is used in conjunction with appropriate antimicrobial therapy. This antibody is now being assessed in clinical trials. Optimal use of monoclonal antibodies may involve a "cocktail" of antibodies with complementary binding specificities.

Animals↗
PubMedDate not supplied

Purification and characterization of phospholipase C preferentially hydrolysing phosphatidylcholine in Tetrahymena membranes.

A phospholipase C (PLC) activity that preferentially hydrolyses phosphatidylcholine to diacylglycerol and phosphorylcholine was found to be present in Tetrahymena pyriformis, strain W and most of its activity was recovered in the membrane fraction. This enzyme was extracted with 1% Triton X-100 from the membrane fraction and purified to apparent homogeneity by sequential chromatographies on Fast Q-Sepharose, hydroxyapatite HCA-100S, Mono Q and Superose 12 gel filtration columns. The purified enzyme had specific activity of 2083 nmol of diacylglycerol released/mg of protein/min for dipalmitoylphosphatidylcholine hydrolysis. Its apparent molecular mass was 128 kDa as determined by SDS-polyacrylamide gel electrophoresis and was 127 kDa by gel filtration chromatography, indicating that the enzyme is present in a monomeric form. The enzyme exhibited an optimum pH 7.0 and the apparent Km value was determined to be 166 microM for dipalmitoylphosphatidylcholine. A marked increase was observed in phosphatidylcholine hydrolytic activity in the presence of 0.05% (1.2 mM) deoxycholate. Ca2+ but not Mg2+ enhanced the activity at a concentration of 2 mM. This purified phospholipase C exhibited a preferential hydrolytic activity for phosphatidylcholine but much less activity was observed for phosphatidylinositol (approximately 9%) and phosphatidylethanolamine (approximately 2%).

1,2-Dipalmitoylphosphatidylcholine↗
PubMedDate not supplied

Scavenger activity in monocyte-derived macrophages from atherothrombotic strokes.

Foam cells are lipid-laden macrophages derived primarily from circulating mononuclear cells and are a characteristic feature of atheromatous lesions. The exact role of these foam cells in the pathogenesis of atherosclerotic lesions remains uncertain, but one potential function is to take-up and process excess interstitial arterial lipoproteins, suggested by their extraordinary ability to engulf enormous quantities of modified low density lipoproteins by the so-called "scavenging pathway." To test this possibility, monocytes from 15 atherothrombotic brain infarct patients and age and sex matched controls were isolated and cultured for 7-8 days in 20% normal serum. The monocyte-derived macrophages were investigated for their ability to bind, internalize and degrade both native and modified (acetylated) LDL labelled with 125Iodine. While native LDL was metabolized similarly, stroke macrophages displayed significantly reduced ability to scavenge modified LDL. These findings suggest that insufficient processing of interstitial arterial cholesterol by monocyte-derived macrophages may contribute to the aggravation of atheroma formation. This inadequacy is likely further compromised by reduced levels of serum high density lipoprotein since the absence of a cholesterol-acceptor will promote the slow but continued accumulation of lipids and the formation of foam cells.

Cells, Cultured↗
PubMedDate not supplied

Regional anesthesia: preferred technique for venodilatation in the creation of upper extremity arteriovenous fistulae.

Owing to the overall poor medical health of patients with end-stage renal disease, we have sought alternatives to the use of general anesthesia for access procedures. Furthermore, since local anesthesia (1) does not offer the motor block that is sometimes desired and (2) can be difficult to maintain when a large amount of vein needs to be transposed, we examined whether regional blocks can be useful for the creation of new arteriovenous fistulae (AVF). From August 2002 to January 2005, 41 patients scheduled for AVF placement underwent a regional block with the use of a lidocaine and ropivacaine mixture using a nerve stimulator. Either axillary, interscalene, or infraclavicular blocks or a combination was used. Intraoperative duplex ultrasonography was used to assess the degree of venodilatation of the basilic and cephalic veins before and after the block. The site of each measurement was marked on the skin and selected by a clearly identifiable branch point. Each measurement was recorded three times and was made in the (1) native state, (2) after application of a tourniquet with opening and closing of the hand for 15 seconds, and (3) after placement of the block. The average age of the patients was 65 +/- 14 years (SD), with ages ranging from 33 to 91 years, and the prevalence of diabetes mellitus was 50%. Complete brachial plexus block was achieved in 34 patients (83%). Sensory block was accomplished within 10 to 15 minutes and usually lasted 4 to 6 hours. Motor block was accomplished in 10 to 25 minutes. Venodilatation was not noted in patients whose blocks did not work (n = 7) or whose vein was found to be phlebitic on exploration (n = 3). The degree of venodilatation noted as a percentage increase after application of the tourniquet compared with the native state for these 34 patients (in whom the block worked) was 37% for the distal cephalic, 31% for the midcephalic, and 32% for the midbasilic vein. The degree of venodilatation noted as a percentage increase after placement of the block compared with after tourniquet application for these 34 patients was 42% for the distal cephalic, 19% for the midcephalic, and 26% for the midbasilic vein. No instances of systemic toxicity, hematomas, or nerve injury from the block were noted. Accesses placed included 20 radiocephalic AVF, 8 brachiobasilic AVF, 8 brachiocephalic AVF, 2 arteriovenous grafts, 2 radiobasilic AVF, and 1 brachial vein AVF.Regional block is a safe and, in our opinion, preferred technique for providing anesthesia for upper extremity vascular surgery. The venodilatation observed is augmented compared with that using a tourniquet and may allow more options for access placements.

Adult↗
PubMedDate not supplied

In-hospital mortality after acute myocardial infarction in Lebanon: incidence, associations, and influence of newer treatment regimens.

PURPOSE: To study the incidence of in-hospital mortality following acute myocardial infarction in Lebanon, and its relationship to demographic, clinical variables, and therapeutic strategies. PATIENTS & METHODS: Consecutive admissions due to myocardial infarction to 18 medical centers in various regions of Lebanon were entered into the Lebanese Myocardial Infarction Study, conducted between January and July 1996. Information was obtained on age, gender, time of onset of symptoms, delay to hospital arrival, mode of transport, and coronary risk factor analysis. The patients were followed up in hospital for analysis of modes of therapy, complications and mortality. RESULTS: There were 44 in-hospital deaths among the 433 admissions (10.2%), which is a rate lower than those previously reported from Lebanon. Less than half the patients presented within 6 hours of onset of symptoms and only 28% received thrombolytic therapy. The mortality rate was higher in older age groups, those presenting with cardiogenic shock or pulmonary edema, those with a history of angina, infarction or heart failure, and those who developed recurrent ischemia or infarction during their hospital stay. Furthermore, occurrence of ventricular arrhythmias, mechanical complications, congestive heart failure and left bundle branch block was associated with a higher mortality rate. Treatment with angiotensin converting enzyme inhibitors, beta-blockers, aspirin, heparin, nitrates and thrombolytics significantly reduced mortality rates. CONCLUSIONS: The results reveal improvement in the survival of patients after acute myocardial infarction to values similar to those reported from Western countries. Further effort should be expended to enhance early arrival to the hospital, increased thrombolytic therapy and to implement treatment strategies supported by large clinical trials such as use of aspirin, ACE inhibitors and beta-blockers.

Adult↗