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Biomedical subjects

G Desai

Publications and source records attributed to G Desai.

At least 19 recordsLinked to original sources
PubMed2004

Differential detection of Newcastle disease virus strains by degenerate primers based RT-PCR.

Degenerate primers based RT-PCR (previously described by [Avian Dis 26 (1997) 837]) has been used for the detection and differentiation of Newcastle disease (ND) viruses. Two sets of primers (A+B and A+C), with common forward primer and distinct reverse degenerate primers, designed from fusion protein gene encoding for cleavage site, could differentiate virulent and avirulent Newcastle disease viruses (NDV). Both sets of primers amplified "F" gene sequence of virulent (velogenic and mesogenic) viruses, whereas in avirulent strains, amplification was only with primer set A+C. Total 10 NDV isolates and two clinical samples including both known and unknown pathotypes, were checked. Based on amplification results 5 viruses were found to be virulent type and 6 as avirulent with one of the two clinical samples, earlier positive by RT-PCR using non-degenerate "F" gene specific primers was found negative in this study. The technique has been found to be a simple and quick for the detection and differentiation of virulent and avirulent NDV, which is important for control of the disease in the events of the outbreaks.

Animals↗
PubMed2000

Characterization of an Indian bluetongue virus isolate by RT-PCR and restriction enzyme analysis of the VP-7 gene sequence.

The reverse transcription-polymerase chain reaction (RT-PCR) was standardized to amplify the VP-7 gene sequences of an Indian isolate of bluetongue virus serotype 23. Using two different sets of primers, a sequence of 1156 bp comprising the complete coding sequence of the VP-7 gene and its 770 bp internal sequence were amplified. The sensitivity of RT-PCR, using these two sets of primers individually was 40 pg and 4 pg, with the external and internal primers, respectively, whereas the nested PCR was 100-fold more sensitive than the single PCR with the external primers. Further, by restriction enzyme digestion of the 1156 bp amplicon, using CfoI, PstI and TaqI enzymes, the Indian isolate was found to be genetically different from isolates from the United States and Australia. RT-PCR and restriction enzyme digestion were applied to detect virus directly in blood samples taken from sheep suspected of bluetongue virus infection.

Animals↗
PubMed1999

Pressure-jump studies of the folding/unfolding of trp repressor.

The dimeric protein, trp apo-repressor of Escherichia coli has been subjected to high hydrostatic pressure under a variety of conditions, and the effects have been monitored by fluorescence spectroscopic and infra-red absorption techniques. Under conditions of micromolar protein concentration and low, non-denaturing concentrations of guanidinium hydrochloride (GuHCl), tryptophan and 8-anilino-1-naphthalene sulfonate (ANS) fluorescence detected high pressure profiles demonstrate that pressures below 3 kbar result in dissociation of the dimer to a monomeric species that presents no hydrophobic binding sites for ANS. The FTIR-detected high pressure profile obtained under significantly different solution conditions (30 mM trp repressor in absence of denaturant) exhibits a much smaller pressure dependence than the fluorescence detected profiles. The pressure-denatured form obtained under the FTIR conditions retains about 50 % alpha-helical structure. From this we conclude that the secondary structure present in the high pressure state achieved under the conditions of the fluorescence experiments is at least as disrupted as that achieved under FTIR conditions. Fluorescence-detected pressure-jump relaxation studies in the presence of non-denaturing concentrations of GuHCl reveal a positive activation volume for the association/folding reaction and a negative activation volume for dissociation/unfolding reaction, implicating dehydration as the rate-limiting step for association/folding and hydration as the rate-limiting step for unfolding. The GuHCl concentration dependence of the kinetic parameters place the transition state at least half-way along the reaction coordinate between the unfolded and folded states. The temperature dependence of the pressure-jump fluorescence-detected dissociation/unfolding reaction in the presence of non-denaturing GuHCl suggests that the curvature in the temperature dependence of the stability arises from non-Arrhenius behavior of the folding rate constant, consistent with a large decrease in heat capacity upon formation of the transition state from the unfolded state. The decrease in the equilibrium volume change for folding with increasing temperature (due to differences in thermal expansivity of the folded and unfolded states) arises from a decrease in the absolute value for the activation volume for unfolding, thus indicating that the thermal expansivity of the transition state is similar to that of the unfolded state.

Bacterial Proteins↗
PubMed1999

Application of obstetric ultrasound to determine the most suitable parameters for the aging of formalin-fixed human fetuses using manual measurements.

The aim of this study was to find the most suitable manual measurements to estimate the age of preserved fetuses. A new technique was used to make successful ultrasonic measurements on 86 out of 100 preserved fetuses under conditions simulating the intrauterine environment. The ultrasonographic images of the preserved specimens were very similar to those of live fetuses. Ultrasonic measurements of standard parameters, and the ages derived from them, were computed directly by the ultrasound scanning machine. Manual measurements were made of the same parameters using established techniques and standard tables for estimating fetal age. The measurements and the ages obtained for each parameter by the two techniques were statistically compared using the limits of agreement (Bland and Altman, 1986). Of the manual measurements used in the estimation of fetal age, foot length was found to be the most suitable parameter for practical use. Biparietal diameter was equally good, but the head circumference was the most precise, especially when used in conjunction with the formulae developed for ultrasonic measurements. Crown-rump length was found to be unsuitable to age fetuses beyond the first trimester due to distortion of the spine caused by compression in storage.

Cadaver↗
PubMed1996

Altered growth and attachment of rabbit crypt colonocytes isolated from different developmental stages.

The rabbit colon was used to establish an in vitro model for examining development-related cellular changes in colonocyte function. Colonic epithelia from newborn, weanling, and adult animals were separated from the muscle and subjected to enzymatic digestion. A mixture of 0.05% Pronase, 0.015% collagenase IV, and 0.023% DTT was determined to be optimal for the isolation of newborn and weanling colonocytes. This solution yielded significantly more cells and of greater viability than a 0.1% Pronase, 0.03% collagenase IV, 0.07% DTT mixture that is optimal for adult colonocytes. The epithelial origin of the colonocytes was confirmed by immunofluorescent staining of cytokeratins. The isolation procedure resulted in a crypt-enriched population and the cell yield/g of mucosa increased with age as did the crypt depth. Colonocyte viability of adults but not of newborns and weanlings, declined from 24 to 72 h. When grown on plastic, the newborn and weanling colonocytes show a approximately 2-fold increase in number, DNA and protein content over 48 h. In contrast, for all three parameters the adult colonocytes revealed only a approximately 10% increase. The colonocytes also showed an age-related decline in attachment to extracellular matrices. Colonocytes showed maximal attachment to Matrigel and collagen IV; newborn and weanling colonocytes show > 80% attachment, whereas adult colonocytes showed only a 45% attachment. The efficacy of attachment to Matrigel compared with that on plastic also differed with age, representing 9.3-, 5.5-, and 4.4-fold increase in adult, weanling, and newborn colonocytes, respectively. Newborn and weanling colonocytes grown on Matrigel for 48 h, showed a significant, 15% increase in cell number, DNA, and protein content compared with those grown on plastic. There was no difference in these parameters when adult colonocytes grown on Matrigel were compared with those grown on plastic. In summary, we have established an in vitro model for studying colonic epithelial cells at different stages of development.

Age Factors↗
PubMed1995

Killing of Histoplasma capsulatum by macrophage colony stimulating factor-treated human monocyte-derived macrophages: role for reactive oxygen intermediates.

The interaction of human macrophages with the yeast-form of Histoplasma capsulatum was studied. The use of culture and a short-term assay period instead of microscopy gave direct evidence of the fungicidal activity of human macrophages. The present study reports the novel finding of fungicidal activity of macrophages derived from monocytes in the presence of macrophage colony-stimulating-factor (MCSF). The induction of fungicidal activity by this cytokine was dose dependent. MCSF at 10,000 U/ml was optimal with 73(SD3)% killing. Inhibition of macrophage killing by superoxide dismutase (SOD), but not catalase (CAT) or N-monomethyl-L-arginine (NMMA), established the role of the superoxide anion in the killing mechanism. The fungistatic activity of MCSF-derived human macrophages in a 24-h assay was also dose dependent and was not inhibited by SOD, CAT or NMMA. MCSF at 10,000 U/ml produced optimal macrophage fungistatic activity, 34.6(SD4)%.

Arginine↗
PubMed1995

Diagnosis of intestinal microsporidiosis by examination of stool and duodenal aspirate with Weber's modified trichrome and Uvitex 2B strains.

Severe, chronic diarrhea is a frequent complication of human immunodeficiency virus disease, and intestinal microsporidiosis is being recognized with increasing frequency in patients with AIDS. Noninvasive, cost-effective techniques are needed to optimize its diagnosis. Weber's modified trichrome stain (MTS) and the fluorochrome Uvitex 2B stain were used to detect microsporidial spores in smears of stool and duodenal aspirate (DA) samples received from human immunodeficiency virus-infected patients for examination for ova and parasites. Of 305 samples (292 stool and 13 DA samples) from 140 patients examined by MTS, 83 samples from 26 (18.6%) of the patients were positive for microsporidia (23 patients diagnosed initially and 3 diagnosed upon review). A subset of the samples studied by MTS consisting of 108 smears of stool and DA specimens from 60 patients was examined by Uvitex 2B. All 44 samples positive by MTS were also positive by Uvitex 2B. In addition, seven specimens and three patients were initially detected as positive by Uvitex 2B only (all three patients were positive also by MTS upon review). Confirmation of the diagnosis was obtained for 24 of 26 smear-positive patients by duodenal biopsy and/or stool transmission electron microscopy. Of 114 patients with stained smears negative for microsporidia, 23 had duodenal biopsies which showed no microsporidia. For the 43 patients who underwent duodenal biopsy, the sensitivity of both the MTS and the Uvitex 2B methods compared with biopsy results was 100%. Of six patients with negative duodenal biopsies and positive stained smears, four had microsporidia demonstrated by stool transmission electron microscopy. The examination of stool and DA smears stained by Uvitex 2B and/or MTS is a sensitive, noninvasive test for diagnosis of intestinal microsporidiosis which can be successfully implemented in a clinical laboratory. Strict adherence to precise diagnostic criteria is necessary to avoid incorrect results. The simultaneous use of both staining methods enhances performance and may provide greater accuracy, especially for patients with light infections.

AIDS-Related Opportunistic Infections↗
PubMed1994

Residential radon exposure and lung cancer in Sweden.

BACKGROUND: Residential radon is the principal source of exposure to ionizing radiation in most countries. To determine the implications for the risk of lung cancer, we performed a nationwide case-control study in Sweden. METHODS: The study included 586 women and 774 men 35 to 74 years of age with lung cancer that was diagnosed between 1980 and 1984. For comparison, 1380 female and 1467 male controls were studied. Radon was measured in 8992 dwellings occupied by the study subjects at some time since 1947. Information on smoking habits and other risk factors for lung cancer was obtained from questionnaires. RESULTS: Radon levels followed a log-normal distribution, with geometric and arithmetic means of 1.6 and 2.9 pCi per liter (60.5 and 106.5 Bq per cubic meter), respectively. The risk of lung cancer increased in relation to both estimated cumulative and time-weighted exposure to radon. In comparison with time-weighted average radon concentrations up to 1.4 pCi per liter (50 Bq per cubic meter), the relative risk was 1.3 (95 percent confidence interval, 1.1 to 1.6) for average radon concentrations of 3.8 to 10.8 pCi per liter (140 to 400 Bq per cubic meter), and it was 1.8 (95 percent confidence interval, 1.1 to 2.9) at concentrations exceeding 10.8 pCi per liter. The estimates of risk were in the same range as those projected from data in miners. The interaction between radon exposure and smoking with regard to lung cancer exceeded additivity and was closer to a multiplicative effect. CONCLUSIONS: Residential exposure to radon is an important cause of lung cancer in the general population. The risks appear consistent with earlier estimates based on data in miners.

Adult↗
PubMed1994

Clinical features of microsporidiosis in patients with AIDS.

Microsporidia are protozoan parasites responsible for significant gastrointestinal disease in patients infected with human immunodeficiency virus. We report the clinical features of 20 patients with chronic diarrhea for whom microsporidian spores were identified by modified trichrome staining of stool smears and confirmed by biopsy and/or electron microscopy of stool. Of the 18 microsporidian protozoa identified to the species level, 14 (78%) were Enterocytozoon bieneusi and four (22%) were Septata intestinalis. The mean CD4 count in these patients was 35 +/- 29 cells/mm3. Parameters of absorption, specifically absorption of fat and D-xylose, and levels of zinc were strikingly abnormal in patients who were tested. Treatment with albendazole led to clinical responses in six of 10 patients, and dietary manipulation resulted in clinical improvement in eight of nine patients. We recommended that patients with chronic, intermittent diarrhea and CD4 counts of < 100 cells/mm3 be further evaluated for microsporidia by modified trichrome staining of stool and light and electron microscopy of small bowel biopsy specimens. Antiprotozoal therapies are currently experimental, but some patients who have been treated with these therapies have dramatic responses. We also recommend that special attention be paid to the measurement of parameters of absorption with appropriate modification of diet.

AIDS-Related Opportunistic Infections↗