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Biomedical subjects

M Desai

Publications and source records attributed to M Desai.

At least 19 recordsLinked to original sources
PubMed1994

Flagellin gene profiling of Helicobacter pylori infecting symptomatic and asymptomatic individuals.

Diversity within and around the flagellin (fla) A gene of Helicobacter pylori was studied by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) analysis and genomic Southern blot hybridization profiling. Four distinct pattern types were identified by DdeI restriction analysis of the 1.5-kb flaA amplicon of 55 strains. Most strains (73%) had the same flaA RFLP type, but subtypic variation was evident in some strains. No consistent associations were observed for selected strain subsets between the DdeI flaA profiles and phenotype (motility and cytotoxicity), urease gene profile or patient symptomatology. A subset of seven (F-1 profile) and four (F-2 profile) strains with identical HindIII digest patterns provided further evidence that the flaA gene was relatively highly conserved within H. pylori. By contrast, the flaA gene blot hybridization profiles were more diverse and consistent with greater variation at restriction sites in adjacent regions of the genome. We conclude that analyses of polymorphisms within the flaA gene provide limited discrimination between strains of H. pylori. The flaA genomic blot profiles offer greater potential for molecular typing purposes, although no associations with other pathogenicity factors or disease symptoms could be deduced.

Blotting, Southern↗
PubMed1992

Ribosomal RNA gene restriction fragment diversity amongst Lior biotypes and Penner serotypes of Campylobacter jejuni and Campylobacter coli.

Diversity based on ribosomal RNA gene-restriction endonuclease digest patterns was detected amongst 42 strains of Campylobacter jejuni and 18 strains of C. coli including representatives of 53 different Penner serotypes. HaeIII ribopatterns were coded for numerical analysis which showed that all except two were different including those of several strains of the same serotype (P2 and P20). At the 30% similarity level, four groupings were formed in the analysis of which three corresponded to C. jejuni, C. coli and C. lari phenotypes respectively. Eight strains (13%) were atypical as their phenotypic and ribopattern associations did not correspond. Ribopattern fragments of 3.0, 5.0 and 9.3 kb were characteristic of the majority of C. jejuni, whereas 1.5, 2.2-, 2.3- and 4.7-kb fragments were commonly present in C. coli. These fragments provided novel species-specific markers. We conclude that HaeIII ribotyping was as discriminatory as Penner serotyping of C. jejuni and C. coli and may even provide a basis for distinguishing between strains of the same serotype and for identifying new groups within the thermophilic campylobacters.

Bacterial Typing Techniques↗
PubMed1992

Persistent truncus arteriosus--an autopsy study of 16 cases.

Sixteen specimens of heart with persistent truncus arteriosus were studied to evaluate the anatomic features. Using the Collet and Edwards classification, type I truncus arteriosus was the most frequent (62.5%). Using Van Praagh's classification type A1 was the most common (43.7%). There were two cases which could not be classified according to the Collet and Edwards classification. The truncal valve was tricuspid in 75% of the cases and bicuspid in the remaining 25%. In all 6 cases with interruption of the aorta, the truncal valve was committed to the right ventricle. The ventricular septal defect was subtruncal in all except 1 case. There was variation in the thickness of the posterior limb of the septal band and the ventriculo-infundibular fold. Absence of the ventriculo-infundibular fold in 3 cases led to truncal tricuspid continuity. Right-sided aortic arch and interruption of the aorta were frequently associated arch anomalies.

Abnormalities, Multiple↗
PubMed1992

Functional analysis of the N-terminal domain of Tat protein of the human immunodeficiency virus type 1.

The Tat protein of human immunodeficiency virus type 1 (HIV-1) is a potent trans-activator of the viral long terminal repeat (LTR). The N-terminal region of Tat is rich in proline and acidic residues analogous to the activation domains of other transcription factors such as GAL-4 and CTF/NF-1. Several basic residues are also present in this region. To investigate the role of these structural features in the Tat-mediated trans-activation, we have chemically synthesized and evaluated Tat analogs with alanine or glutamine replacing one or more of these amino acid residues. Our data show that substitution of Glu-2, His-13, or all the proline in the Pro-Xaa3-Pro triad drastically reduced activity. In contrast, changes at Arg-7, Lys-12 and any one proline residue in the triad moderately reduced, and substitution of Lys-19 showed little effect on, activity. These results show that the native structure of the N-terminal 19 amino acid sequence is essential for Tat function, and that the overall topology of this domain and not the acidic residues alone appears necessary for trans-activation.

Amino Acid Sequence↗
PubMed1991

pH dependence of hydrochloric acid diffusion through gastric mucus: correlation with diffusion through a water layer using a membrane-mounted glass pH electrode.

Solute diffusion coefficients (D) can indicate a dependence upon actual solute concentrations. Here a single compartment has been utilized, in which effective HCl diffusion to a membrane-mounted glass pH electrode can be measured across the pH spectrum. The study has investigated HCl diffusion through both mucus and water layers as a function of HCl concentration. The observed dynamic responses of a liquid-film and mucus-coated electrodes over a range of HCl concentrations suggest that the speed at which equilibrium is attained is pH dependent; equilibrium was reached rapidly under more acidic and alkaline conditions. Estimated values of DHCl also indicate a strong pH dependence for both liquid film and mucus. In both instances, a greater than 10-fold reduction in DHCl at pH 7.5 as compared with that at pH 3.5 has been demonstrated. Furthermore, estimated values of DHCl are approximately 4-fold smaller through the mucus gel, as compared with a water layer. The findings indicate that the most powerful influence on diffusional resistance is pH itself, whereby a marked drop in H+ diffusion is likely to occur towards neutral pH irrespective of the composition of the gel barrier. Possible implications of the findings are discussed in relation to mucosal protection from acid.

Animals↗
PubMed1991

Hypochlorous acid mobilizes cellular zinc.

Neutrophil oxidants, in particular hypochlorous acid (HOCl), can cause injury to healthy tissues at sites of inflammation. Some of this injury may be caused by oxidant-induced mobilization of metals. We examined the ability of HOCl to mobilize Zn2+ in target tissues. Arterial endothelial cell cultures and heart tissue sections were incubated for 90 s in buffered saline, pH 7.3, containing a suspension of N-(6-methoxy-8-quinolyl)-p-toluenesulfonamide (100 nmol/mL), a Zn(2+)-specific fluorescent chelator, and were subsequently exposed to 200 microM HOCl for 5 min. The cellular fluorescence was analyzed histologically and showed a marked increase in intensity after HOCl treatment, which was indicative of an increase in cellular free Zn2+ concentration. Incubation of HOCl-treated tissues with dithiothreitol, a membrane-permeable metal chelator, caused a sharp decline in cellular fluorescence. This study shows for the first time that HOCl can mobilize cellular Zn2+. In view of the multiple cellular roles played by Zn2+, its mobilization by oxidants at sites of inflammation may contribute to the observed injury. The ability of dithiothreitol to chelate the mobilized Zn2+ suggests that it may be able to reverse Zn(2+)-mediated injury.

Aminoquinolines↗
PubMed1991

Analytical performance of EMIT cyclosporine assay evaluated.

We evaluated the EMIT Cyclosporine Assay (Syva Co., Palo Alto, CA), using the Cobas-Mira analyzer to assess the precision, accuracy, and analytical recovery from whole-blood samples supplemented with cyclosporine. We also performed comparative analysis of whole-blood samples containing cyclosporine from liver and kidney transplant patients by using EMIT, HPLC, and RIA (IncStar Cyclo-Trac, SP assay). Before assay by EMIT or RIA, cyclosporine was extracted from whole blood with methanol. For the HPLC method, whole blood containing cyclosporine was hemolyzed with 300 mL/L acetonitrile in water; cyclosporine was extracted from the hemolysate with acetonitrile. The within-run and between-run CVs for the EMIT assay of cyclospoprine were 9.9% (means = 72.6, SD = 7.2 micrograms/L; n = 20) and 13.5% (means = 75.0, SD = 10.1 micrograms/L; n = 26) for the low control; 3.5% (means = 194.7, SD = 6.8 micrograms/L; n = 20) and 8.1% (means = 189.0, SD = 15.3 micrograms/L; n = 26) for the medium control; and 7.0% (means = 332.5, SD = 23.3 micrograms/L; n = 20) and 7.1% (means = 340.0, SD = 24.2 micrograms/L; n = 24) for the high control (Bio-Rad, whole-blood controls). Analytical recovery of cyclosporine from drug-supplemented samples averaged 99% for EMIT, 104% for HPLC, and 90% for RIA over a concentration range of 50-500 micrograms/L. Analysis of 196 specimens by HPLC (x) vs EMIT (y) gave the following regression statistics: y = 1.27x + 16.44; IncStar's RIA (x') vs EMIT: y = 1.12x' - 2.50; HPLC vs RIA: x' = 1.10x + 23.87.

Chromatography, High Pressure Liquid↗
PubMed1990

Botulinum type F neurotoxin. Large-scale purification and characterization of its binding to rat cerebrocortical synaptosomes.

1. A large-scale purification procedure has been developed for Clostridium botulinum type F neurotoxin. Commencing with 160 litres of bacterial culture, 101 mg of purified type F neurotoxin with a specific toxicity of 2 x 10(7) mouse LD50 (median lethal dose).mg-1 were obtained. 2. Purified type F neurotoxin was labelled to high specific radioactivity (900-1360 Ci/mmol) without loss of biological activity using a chloramine-T procedure. Of the two neurotoxin subunits, the heavy chain was preferentially radiolabelled. 3. Radiolabelled type F neurotoxin displayed specific saturable binding to rat synaptosomes. At least two pools of acceptors were evident: a low content of high-affinity acceptors sites [KD approximately 0.15 nM; Bmax (maximal binding) 20 fmol/mg] and a larger pool of lower-affinity sites (KD greater than 20 nM; Bmax greater than 700 fmol/mg). Both pools of acceptors were sensitive to trypsin and neuraminidase treatment, which suggests that protein and sialic acid residues are components of the synaptosomal acceptors. 4. Experiments investigating competition among botulinum neurotoxin types A, B, E and F for acceptors on rat brain synaptosomes showed that type F neurotoxin binds to acceptor molecules which are completely distinct from those of the other three neurotoxins.

Animals↗
PubMed1990

Identification of a child with short stature.

The objective of this study was to determine the utility of Indian Council of Medical Research's (ICMR) height percentile standards in comparison to Tanner's, in the evaluation of children with short stature. The study consisted of an initial survey of the heights of 500 consecutive new cases brought to the Out Patient Department. The heights were assessed by both ICMR and Tanner's standards. Only 10% were below the 5th percentile of ICMR standards while as many as 32% were below the 3rd percentile of Tanner's standards. Two hundred children who were referred to the endocrine clinic primarily for short stature and who were below the 3rd percentile of Tanner's standards were then evaluated. Of these 200 short children 132 (66%) were also below the 5th percentile of ICMR standards. The major causes of short stature in those below the 5th percentile of ICMR standards were endocrine (56.8%). In the group between the 5th percentile of ICMR standards and 3rd percentile of Tanner standards the major cause of growth retardation was normal variant short stature (67.8% of cases in this group). Correlation of the child's height with the mid-parental height was seen in 90.4% in this group but in only 16.6% of those below the 5th percentile of ICMR standards. The ICMR standards may, therefore, be more suitable than Tanner's standards for the identification of a short child from the lower socio-economic groups.

Anthropometry↗
PubMed1990

Fulminant hepatic necrosis caused by adenovirus type 5 following bone marrow transplantation.

A 34-year-old patient was transplanted from an HLA-identical sister for high grade non-Hodgkin's lymphoma in first complete remission. One month post-transplant, he developed hepatitis and haemorrhagic cystitis. He died 2 months post-transplant from fulminant hepatic failure. Adenovirus type 5 was cultured from urine, and characteristic adenovirus inclusions were seen in the liver. Striking paracrystalline arrays of adenoviruses were seen in the liver on electron microscopy. Reactivation of adenovirus infection is increasingly recognized post-BMT, but this complication of type 5 infection is unusual, and we describe in detail this second reported case.

Adenoviridae Infections↗
PubMed1989

Improved myocardial oxygen utilization following propranolol infusion in adolescents with postburn hypermetabolism.

The purpose of this study was to determine if propranolol (0.5 mg/kg and 1 mg/kg), administered intravenously (IV) at the height of the postburn hypermetabolic response, would decrease myocardial oxygen requirements, without adversely affecting overall oxygen delivery or total body oxygen consumption. To test this hypothesis, six nonseptic patients age 17 +/- 3 years with burns over 82% +/- 11% total body surface area were given propranolol with continuous hemodynamic monitoring. Propranolol was administered to these patients 20 +/- 15 days postburn. Two clinically derived indices of myocardial oxygen consumption, pressure-work index (PWI) and rate-pressure product (RPP), were used to estimate the energy expenditure of the working heart. Both PWI and RPP were significantly decreased from baseline after 0.5 mg/kg propranolol, 31% for PWI (P less than .001) and 30% for RPP (P less than .01). Similarly, a decrease from baseline was seen after 1.0 mg/kg propranolol, 32% for PWI (P less than .001) and 35% for RPP (P less than .01). Cardiac index (L/min/m2) demonstrated no significant change [7.4 +/- 1.1 (prepropranolol), 6.5 +/- 1.3 (after 0.5 mg/kg propranolol), and 6.8 +/- 1.0 (after 1.0 mg/kg propranolol)] and exceeded the upper limits of normal (hyperdynamic state) throughout the study. Oxygen delivery index (962 +/- 209 mL/min/m2) and oxygen consumption indices [(254 +/- 78 mL/min/m2 by Fick method and 236 +/- 78 mL/min/m2 by inspired and expired gases)] were elevated at baseline and unaffected by propranolol. The decrease in PWI and RPP was achieved mainly by propranolol's effect to lower both heart rate and BP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗