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Biomedical subjects

A Desai

Publications and source records attributed to A Desai.

At least 73 records · Page 4Linked to original sources
PubMed1999

A comparison of virus isolation, indirect immunofluorescence and nested multiplex polymerase chain reaction for the diagnosis of primary and recurrent herpes simplex type 1 and type 2 infections.

134 swabs in viral transport medium were received from 126 patients with suspected clinical HSV-1 and HSV-2 infections. They were tested by (i) nested multiplex polymerase chain reaction NMPCR (strongly positive specimens had visible bands on both rounds of PCR) without prior extraction, (ii) culture in primary rhesus monkey kidney, E6-Vero, RD and HEp-2 cells and (iii) antigen detection by immunofluorescence (IF). Antigen detection employed four novel pools (A-D) of monoclonal antibodies (Mab): A was HSV-1 specific, B was HSV-2 specific while C and D were generic. In comparison to NMPCR the sensitivity and specificity of (i) culture was 59% (22/37) and 100% (134/134), (ii) IF by Pool A was 59% (16/27) and 100% (117/117), (iii) IF by Pool B was 40% (4/10) and 100% (130/130) and (iv) IF by Pools C and D were 60% (18/30) and 100% (96/96). Specimens positive by culture were more likely to be strongly positive by NMPCR (chi2 P = 0.004). Typing by each method concurred on all occasions. NMPCR was cost effective, easier to perform and was the most sensitive method for HSV detection. It should become the method of choice for HSV diagnosis.

Base Sequence↗
PubMed1999

Loxosceles spider venom induces the production of alpha and beta chemokines: implications for the pathogenesis of dermonecrotic arachnidism.

Bites from the brown recluse spider and other Loxosceles arachnids result in dermonecrotic skin lesions. Neutrophils (PMN) are essential to the development of Loxosceles-induced skin lesions, but paradoxically, in vitro PMN activation is inhibited by direct exposure to Loxosceles venom. Neutrophil activation occurs in response to a myriad of soluble mediators that include members of both the alpha and beta chemokine families. Because arachnid envenomation results in the exposure of several different cell types to venom, we investigated venom-induced expression of alpha and beta chemokines in both endothelial cells (human umbilical vein; HUVEC) and epithelial cells (A549 pneumocytes). Chemokine-specific capture enzyme immunoassays (EIA) were used to measure Loxosceles deserta venom-induced alpha chemokines: interleukin-8 (IL-8), growth-related oncogene-alpha (GRO-alpha), and beta chemokines: monocyte chemoattractant protein-1(MCP-1), and regulated on activation, normal T cell expressed and secreted (RANTES) in cell-free conditioned media from HUVEC and A549 cell monolayers. Exposure of HUVECs (8 h) to Laxosceles venom resulted in the production of IL-8 (5.2+/-1.30 ng/ml), MCP-1 (1.44+/-0.11 ng/ml) and GRO-alpha (1.97+/-0.15 ng/ml) in a dose and time-dependent manner. Exposure of A549 cell monolayers to venom resulted in IL-8 (7.74+/-0.30 ng/ml), and MCP-1 (2.61+/-0.31 ng/ml), but neither GRO-alpha nor RANTES accumulated during an 8-hour incubation period. Chemokines accumulated in a venom dose and time-dependent manner. Neither cell type secreted RANTES in response to Loxosceles venom. These data indicate that Loxosceles spider venom is a potent inducer of alpha and beta chemokines in both endothelial and epithelial cell types. Based on the established roles of IL-8, MCP-1, and GRO-alpha, in inflammation, these observations have relevance to the pathophysiology of Loxosceles-induced dermonecrosis.

Cells, Cultured↗
PubMed1999

Loxosceles deserta spider venom induces NF-kappaB-dependent chemokine production by endothelial cells.

BACKGROUND: Loxosceles spider evenomation in man frequently results in disfiguring necrotic skin lesions. Recent studies suggest that several proinflammatory mediators participate in lesion development. We have observed that Loxosceles deserta venom induces production of the chemokines interleukin-8, growth-related oncogene alpha, and monocyte chemoattractant protein-I by human umbilical vein endothelial cells. Members of the Rel/Nuclear factor (NF)-kappaB family of transcription factors are important regulators of many genes involved in immune and inflammatory responses. We hypothesized that Loxosceles-venom-induced chemokine expression in human umbilical vein endothelial cells is mediated by NF-kappaB. METHODS: Human umbilical vein endothelial cell monolayers were exposed to activating concentrations of Loxosceles deserta venom. Nuclear extracts of these monolayers were analyzed by electrophoretic mobility shift assay. A direct cause and effect linkage between NF-kappaB activation and chemokine expression by Loxosceles venom was established through examination of the effect of SN50 on interleukin-8 and monocyte chemoattractant protein-1 production using a whole-cell enzyme immunoassay. SN50 is a cell-permeable peptide that specifically blocks cytosolic to nuclear translocation of NF-kappaB. Furthermore, the venom-induced synthesis of chemokine mRNAs was investigated by RNase protection assays. RESULTS: Loxosceles deserta venom induces the activation of NF-kappaB in human umbilical vein endothelial cells. Antibodies to p50 and p65, but not to p52, c-Rel, or Rel B, induce supershifts of the DNA-protein complexes formed by oligonucleotide probes and nuclear extracts from venom-activated human umbilical vein endothelial cells. SN50 peptide inhibits NF-kappaB translocation and interleukin-8 and monocyte chemoattractant protein-1 production in activated human umbilical vein endothelial cells. CONCLUSIONS: Loxosceles deserta venom induces synthesis of interleukin8 and monocyte chemoattractant protein-1 mRNAs in human umbilical vein endothelial cells. The expression of chemokines occurs via an NF-kappaB-dependent pathway.

Cells, Cultured↗
PubMed1999

Effect of elevated temperature and light on the stability of butorphanol tartrate.

The purpose of this investigation was to determine the short-term stability of butorphanol tartrate in presence of diluents. A 10-mg/mL solution of butorphanol tartrate was diluted to 5 mg/mL using normal saline, 5% dextrose in water (D5W), or sterile water for injection. The diluted solutions were divided into two groups. The effect of temperature was tested by placing one group of sealed amber vials at room temperature and at 37 degrees C. The effect of light was studied by placing a second group in amber and clear vials, then exposing them directly to light. At regular time intervals over a period of 5 weeks, the solutions were analyzed for butorphanol tartrate and degradation products using a high-performance liquid chromatography assay. The concentration of butorphanol tartrate remained practically unchanged, indicating that butorphanol tartrate is not affected by heat or light in the presence of any of the diluents over a period of 5 weeks.

Butorphanol↗
PubMed1999

Intracellular glutathione redox status modulates MCP-1 expression in pulmonary granulomatous vasculitis.

A wide spectrum of human lung diseases is characterized by the presence of granulomas. Although understanding of the pathways leading to their development remains incomplete, data from in vitro studies suggest that neutrophils, monocytes, and their secreted products (eg, hydrogen peroxide, H2O2) influence the pathogenesis of pulmonary granulomatous disease through the regulation of local chemokine and cytokine production. Using a well-characterized rat model of glucan-induced pulmonary granulomatous vasculitis, we sought to determine the role of intracellular glutathione (GSH) redox status in the expression of monocyte chemoattractant protein-1 (MCP-1). Previous studies have revealed that vascular wall MCP-1 expression is obligatory for granuloma development and that both neutrophils and hydrogen peroxide are required for MCP-1 induction. Because in vitro expression of MCP-1 is in part mediated by the redox-sensitive transcription factors nuclear factor-kappa B (NF-kappaB) and activator protein-1 (AP-1), we studied their activation as a function of varying intracellular GSH redox status in the pathogenesis of glucan-induced pulmonary granulomatosis. Infusion of particulate yeast cell wall glucan into rats resulted in a rapid decrease in intracellular GSH concentrations which was accompanied by the activation of NF-kappaB and AP-1. The pattern of AP-1 and NF-kappaB activation in turn correlated temporally with the expression of MCP-1. Administration of L-buthionine-S, R-sulfoximine, a specific inhibitor of gamma-glutamyl cysteine synthetase, resulted in a significant reduction in intracellular GSH pools. GSH depletion resulted in a more than 100% increase in pulmonary MCP-1 concentrations and increased cytosolic to nuclear translocation of NF-kappaB while having no effect on AP-1 levels. These observations suggest that in the pathogenesis of pulmonary granulomatous disease, intracellular glutathione redox status modulates the expression of MCP-1 through redox-sensitive transcription factors.

Animals↗
PubMed1998

Fluorescent speckle microscopy, a method to visualize the dynamics of protein assemblies in living cells.

Fluorescence microscopic visualization of fluorophore-conjugated proteins that have been microinjected or expressed in living cells and have incorporated into cellular structures has yielded much information about protein localization and dynamics [1]. This approach has, however, been limited by high background fluorescence and the difficulty of detecting movement of fluorescent structures because of uniform labeling. These problems have been partially alleviated by the use of more cumbersome methods such as three-dimensional confocal microscopy, laser photobleaching and photoactivation of fluorescence [2]. We report here a method called fluorescent speckle microscopy (FSM) that uses a very low concentration of fluorescent subunits, conventional wide-field fluorescence light microscopy and digital imaging with a low-noise, cooled charged coupled device (CCD) camera. A unique feature of this method is that it reveals the assembly dynamics, movement and turnover of protein assemblies throughout the image field of view at diffraction-limited resolution. We found that FSM also significantly reduces out-of-focus fluorescence and greatly improves visibility of fluorescently labeled structures and their dynamics in thick regions of living cells. Our initial applications include the measurement of microtubule movements in mitotic spindles and actin retrograde flow in migrating cells.

Animals↗
PubMed1998

Anaphase A chromosome movement and poleward spindle microtubule flux occur At similar rates in Xenopus extract spindles.

We have used local fluorescence photoactivation to mark the lattice of spindle microtubules during anaphase A in Xenopus extract spindles. We find that both poleward spindle microtubule flux and anaphase A chromosome movement occur at similar rates ( approximately 2 microm/min). This result suggests that poleward microtubule flux, coupled to microtubule depolymerization near the spindle poles, is the predominant mechanism for anaphase A in Xenopus egg extracts. In contrast, in vertebrate somatic cells a "Pacman" kinetochore mechanism, coupled to microtubule depolymerization near the kinetochore, predominates during anaphase A. Consistent with the conclusion from fluorescence photoactivation analysis, both anaphase A chromosome movement and poleward spindle microtubule flux respond similarly to pharmacological perturbations in Xenopus extracts. Furthermore, the pharmacological profile of anaphase A in Xenopus extracts differs from the previously established profile for anaphase A in vertebrate somatic cells. The difference between these profiles is consistent with poleward microtubule flux playing the predominant role in anaphase chromosome movement in Xenopus extracts, but not in vertebrate somatic cells. We discuss the possible biological implications of the existence of two distinct anaphase A mechanisms and their differential contributions to poleward chromosome movement in different cell types.

Adenylyl Imidodiphosphate↗
PubMed1998

Tubulin and FtsZ structures: functional and therapeutic implications.

The microtubule cytoskeleton has lagged nearly a decade behind the actin cytoskeleton with respect to structural information on the basic polymer subunit. This structural inferiority complex has finally been lifted by two recent papers describing the structures of the alpha beta tubulin dimer and FtsZ, a protein similar to tubulin that is essential for cell division in prokaryotes.

Bacterial Proteins↗
PubMed1998

Localization of nod, nif, and acidic exopolysaccharide determinants on a large plasmid in slow-growing cowpea Rhizobium sp. S2.

Slow-growing cowpea Rhizobium sp. S2, a pigeon pea isolate, showed excessive synthesis of exopolysaccharide (EPS) and nod factor(s) only when grown in the presence of corresponding host root exudate (RE) or naringenin (a flavonoid present in RE of pigeon pea). muc- strain, a plasmid-cured derivative of the parent strain, showed negligible EPS production and failed to synthesize the nod factor(s) under similar growth conditions. The nod factor(s) was extracted and partially purified from the total EPS of the culture supernatant of S2 grown in the presence of either RE or naringenin by the butanol-soluble, ethyl acetate-insoluble method. The parent strain also showed ex-planta nitrogenase activity, whereas in muc- it was not detectable. In contrast to observations of the location of nod, nif- and EPS-synthesizing genes on the chromosome in commonly studied cowpea Rhizobia and Bradyrhizobium sp. colony blot and dot blot hybridization studies revealed the presence of nod (common nod genes), nif (nif KDH); and EPS (pss) determinants to be on the large plasmid in the parent strain and therefore absent in muc-, which is a plasmid-cured derivative.

Genes, Bacterial↗
PubMed1998

Anxiety and depression among HIV-infected heterosexuals--a report from India.

The aim of the study was to study factors related to anxiety, depression, and suicidal ideation among HIV-seropositive heterosexuals soon after being tested for their HIV status for the first time. Anxiety, depression, and suicidal ideation were assessed among 51 HIV-seropositive heterosexual men and women with various stages of HIV infection. All assessments were done between 4 and 6 weeks after revelation of positive serostatus. Psychosocial variables such as quality of family relationships and substance use and sociodemographic details such as gender, income, education, and residence were studied for their association with psychiatric morbidity. Illness details studied for their association with psychiatric morbidity included stage of HIV infection, spouse's HIV status, presence of physical illness, and pain. Depression was present in 40% and anxiety in 36% of the sample. Serious suicidal intent was seen in 14%. Multiple regression analysis indicated that presence of pain, concurrent alcohol abuse, poor family relations, and presence of AIDS in the spouse were significant factors associated with depression, anxiety, and suicidal ideation.

Adult↗