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Biomedical subjects

A Srivastava

Publications and source records attributed to A Srivastava.

At least 91 records · Page 5Linked to original sources
PubMed2003

Cerebrotendinous xanthomatosis: neuroimaging findings in two siblings from an Indian family.

Cerebrotendinous xanthomatosis (CTX) is exceptionally rare in the Indian population. We present and discuss the clinical, radiological and histopathologic findings in 2 siblings with CTX. Both the patients had juvenile cataract, mental retardation and marked cerebellar ataxia. The Achilles tendon swelling was present in only 1 patient (Case 2). MR imaging showed typical bilateral and symmetrical involvement of the dentate nuclei, inferior olives, brainstem and cerebellar hemispheric white matter. Although the diagnosis of CTX was made in the 3rd decade in both our cases, early diagnosis is possible if neuroimaging is done in the early course of the disease.

Adult↗
PubMed2003

Association of cucumovirus and potyvirus with betelvine (Piper betle L.) as evidenced by ELISA and RT-PCR.

An attempt was made to detect various viruses of Piper betle grown at Mahoba and Banthara in India. DAC-ELISA and RT-PCR tests were performed in leaf sap samples of betelvine for detection of a cucumovirus (Cucumber mosaic virus) and potyvirus (Bean yellow mosaic virus) using specific antibodies and universal primers of respective viruses. DAC-ELISA could detect only CMV. However, RT-PCR detected both cucumovirus and potyvirus infection in betelvine samples. Association of CMV with betelvine was observed for the first time in the present study.

Antibodies, Viral↗
PubMed2002

Induction of apoptosis of peripheral blood mononuclear cells by antithymocyte globulin (ATG) in aplastic anemia: an in vivo and in vitro study.

Antithymocyte globulin (ATG) is the standard therapy for aplastic anemia (AA) patients who are not eligible for allogeneic bone marrow transplantation (BMT). The exact mechanism of action of ATG is still not known. Profound lymphopenia is observed throughout the treatment period with ATG and appears to contribute to its immunomodulatory effect. One of the possible mechanisms, which could account for ATG-mediated lymphopenia, is by induction of apoptosis of peripheral blood mononuclear cells (PBMCs). However, there is no conclusive evidence to support this mechanism. We investigated whether ATG could induce an in vivo apoptosis in PBMCs of 12 AA patients undergoing ATG therapy by terminal deoxynucleotidyltransferase (TdT)-mediated dUTP nick-end labeling (TUNEL) assay using flow cytometry. A significant increase in the percentage of apoptosis was observed in six patients. The median percentage prior to therapy was 3 percent (range: 1-10 percent), which increased to a peak median value of 27 percent (range 17-66 percent) with therapy. ATG also induced an in vitro apoptosis of normal PBMCs as demonstrated by Annexin V and TUNEL staining using flow cytometry. Induction of apoptosis was dose dependent: 52 percent of the PBMCs exhibited Annexin V positivity after incubation with ATG at a dose of 500 microg/ml for 6 h, and 37 percent of the PBMCs exhibited DNA fragmentation after incubation with ATG at a dose of 1000 microg/ml for 24 h as demonstrated by TUNEL assay. Thus, ATG induces in vivo apoptosis in PBMCs of AA patients undergoing therapy as well as an in vitro apoptosis in normal PBMCs, and apoptosis may be an important mechanism for ATG-induced lymphopenia.

Anemia, Aplastic↗
PubMed2002

Synthesis of glycosylated beta-amino acids as new class of antitubercular agents.

A series of glycosylated beta-amino acids was prepared and evaluated against Mycobacterium tuberculosis, M. avium, M. fortuitum and M. smegmatis. The compounds were designed to mimic the enzyme D-alanine racemase and glycosyl transferase involved in the biosynthesis of essential cell wall peptidoglycan and arabinogalactan. Though most of the compounds exhibited little activity, however, one showed significant activity against all the strains in cell culture and activity was confirmed by BACTEC method.

Amino Acids↗
PubMed2002

Prognostic variables in newly diagnosed children and adolescents with acute myeloid leukemia: Children's Cancer Group Study 213.

The objective of this study was to identify biologic parameters that were associated with either exceptionally good or poor outcome in childhood acute myeloid leukemia (AML). Among the children with AML who entered Children's Cancer Group trial 213, 498 patients without Down syndrome or acute promyelocytic leukemia (APL) comprise the basis for this report. Univariate comparisons of the proportion of patients attaining complete remission after induction (CR) indicate that, at diagnosis, male gender, low platelet count (< or =20 000/microl), hepatomegaly, myelodysplastic syndrome (MDS), French-American- British (FAB) category M5, high (>15%) bone marrow (BM) blasts on day 14 of the first course of induction, and +8 are associated with lower CR rates, while abnormal 16 is associated with a higher CR rate. Multivariate analysis suggests high platelet count at diagnosis (>20 000/microl), absence of hepatomegaly, < or =15% day 14 BM blast percentage, and abnormal 16 are independent prognostic factors associated with better CR. Univariate analysis demonstrated a significant favorable relationship between platelet count at diagnosis (>20 000/microl), absence of hepatomegaly, low percentage of BM blasts (< or =15%), and abnormal 16 with overall survival. Absence of hepatomegaly, < or =15% day 14 BM blast percentage, and abnormal 16 were determined to be independent prognostic factors associated with better survival.

Acute Disease↗
PubMed2002

Prospective evaluation of safety and efficacy of the supracostal approach for percutaneous nephrolithotomy.

OBJECTIVE: To prospectively evaluate the safety and efficacy of the supracostal approach for percu-taneous nephrolithotomy (PCNL), as it is usually avoided because of concerns about potential chest complications. PATIENTS AND METHODS: Between August 1998 and August 2001, 465 patients underwent PCNL. Supracostal access was obtained in 62 patients (63 renal units), comprising 13% of the procedures. The indications for a supracostal approach were staghorn, upper ureteric, superior calyceal stones and high-lying kidneys. The data were analysed for stone clearance, need for additional punctures and the complications associated with supracostal puncture. RESULTS: The supracostal was the only access in 63% of the PCNL procedures. Additional punctures were required mainly for staghorn stones (15 of 23). Overall, 90% of the patients were rendered stone-free or had clinically insignificant residuals with PCNL alone. In patients with staghorn stones, they were completely cleared in 84% of renal units. Significant chest complications developed in three (5%) patients, which required insertion of a chest tube. One (2%) patient developed haemothorax secondary to injury of the intercostal artery. All the patients recovered uneventfully. CONCLUSIONS: These results indicate that supracostal access provides high clearance rates with acceptable complications; it should not be avoided for fear of chest complications. A chest X-ray after surgery should be routine, to detect any complication.

Adult↗
PubMed2002

Cytogenetic, fluorescent in situ hybridization & reverse transcriptase-polymerase chain reaction analysis in acute promyelocytic leukaemia patients.

BACKGROUND & OBJECTIVES: The presence of t(15;17) or PML-RAR alpha fusion transcript is the diagnostic hallmark of patients with acute promyelocytic leukaemia (APL). Cytogenetic (CG), fluorescent in situ hybridization (FISH) and reverse transcriptase-polymerase chain reaction (RT-PCR) are mainly the techniques used for detecting this abnormality. The objective of this study was to compare and assess the role of CG, FISH and RT-PCR in the diagnosis of APL. METHODS: CG, FISH and RT-PCR analysis were performed in 29 patients with APL (28 M3, 1 M3v; 27 studied at diagnosis and 2 at relapse). RESULTS: Karotypes obtained in 25 patients revealed t(15;17) in 21 normal karyotype in 3 and trisomy 8 in 1 patient. In 26 patients FISH was positive for PML-RAR alpha fusion in both interphase (IP) and metaphase, two were negative and one patient had no cells for FISH analysis. IP FISH confirmed the fusion of PML-RAR alpha in all patients with t(15;17) detected by CG. RT-PCR was positive in the 22 patients analyzed (7 patients did not have RT-PCR). PCR was positive in the 3 patients with cytogenetically normal karyotypes and in one patient when karyotyping was a failure. CG detected 21 (72.4%) patients with t(15;17) of which additional chromosomal abnormalities were detected in 20 per cent of patients with successful karyotype. INTERPRETATION & CONCLUSION: FISH and RT-PCR were useful in detecting PML-RAR alpha fusion in cytogenetically normal patients and those in when karyotyping was a failure and can be used in routine analysis for rapid confirmation of t(15;17) in patients with acute myeloid leukaemia.

Adolescent↗
PubMed2001

Soluble phosphatidylserine binds to a single identified site in the C2 domain of human factor Va.

Factor V(a) (FV(a)) is a cofactor for the serine protease factor X(a) that activates prothrombin to thrombin in the presence of Ca(2+) and a membrane surface. FV(a) is a heterodimer composed of one heavy chain (A1 and A2 domains) and one light chain (A3, C1, and C2 domains). We use fluorescence, circular dichroism, and equilibrium dialysis to demonstrate that (1) the FV C2 domain expressed in Sf9 cells binds one molecule of C6PS with a k(d) of approximately 2 microM, (2) stabilizing changes occur in the FV C2 domain upon C6PS binding, (3) the C6PS binding site in the FV C2 domain is located near residue Cys(2113), which reacts with DTNB, and (4) binding to a PS-containing membrane is an order of magnitude tighter than that to soluble C6PS. Coupled with a recently published crystal structure of the C2 domain, these results support a model for the mechanism of C2-membrane interaction.

Amino Acid Sequence↗
PubMed2001

Two genes that map to the STSL locus cause sitosterolemia: genomic structure and spectrum of mutations involving sterolin-1 and sterolin-2, encoded by ABCG5 and ABCG8, respectively.

Sitosterolemia is a rare autosomal recessive disorder characterized by (a) intestinal hyperabsorption of all sterols, including cholesterol and plant and shellfish sterols, and (b) impaired ability to excrete sterols into bile. Patients with this disease have expanded body pools of cholesterol and very elevated plasma plant-sterol species and frequently develop tendon and tuberous xanthomas, accelerated atherosclerosis, and premature coronary artery disease. In previous studies, we have mapped the STSL locus to human chromosome 2p21. Recently, we reported that a novel member of the ABC-transporter family, named "sterolin-1" and encoded by ABCG5, is mutated in 9 unrelated families with sitosterolemia; in the remaining 25 families, no mutations in sterolin-1 could be identified. We identified another ABC transporter, located <400 bp upstream of sterolin-1, in the opposite orientation. Mutational analyses revealed that this highly homologous protein, termed "sterolin-2" and encoded by ABCG8, is mutated in the remaining pedigrees. Thus, two highly homologous genes, located in a head-to-head configuration on chromosome 2p21, are involved as causes of sitosterolemia. These studies indicate that both sterolin-1 and sterolin-2 are indispensable for the regulation of sterol absorption and excretion. Identification of sterolin-1 and sterolin-2 as critical players in the regulation of dietary-sterol absorption and excretion identifies a new pathway of sterol transport.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2001

Osmotic perturbations induce differential movements in the core and periphery of proteins, membranes and micelles.

Polymeric structures, namely, micelles, membranes and globular proteins share the property of two distinct regions: a hydrophobic core and a hydrophilic exterior. The dynamics of these regions of the polymeric structures were probed using selective fluorophores 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-anilinonaphthalene-8-sulfonate (ANS), respectively. Perturbation of the polymers by external osmotic pressure, ionic strength and temperature was monitored in the two regions using steady state measurements of fluorescence intensity and anisotropy. While the fluorescence lifetime of DPH and ANS did not change significantly, parallel change in steady state anisotropy values and the rotational correlation time indicated mobility in the probe/probe-domain. Osmotic perturbation of the polymers in electrolyte media led to decreased DPH mobility. Enhanced ellipticity at 222 nm in bovine serum albumin was observed in 1.5 M NaCl and sucrose media. ANS exhibited a decreased anisotropy with progressive dehydration in proteins in NaCl media, in dimyristoylphosphatidylcholine (DMPC) vesicles in sucrose media, and in neutral laurylmaltoside micelles in both NaCl and sucrose media. Thus, ANS showed responses opposite to that of DPH in these systems. A comparison with several domain selective probes indicated that DPH reported findings common to depth probes while ANS reported data common to interfacial probes used for voltage monitoring.

Anilino Naphthalenesulfonates↗
PubMed2001

Evaluation of total choline from in-vivo volume localized proton MR spectroscopy and its response to neoadjuvant chemotherapy in locally advanced breast cancer.

Results of the proton magnetic resonance spectroscopy carried out on normal, benign breast disease and locally advanced breast cancer patients are presented. The in-vivo MR spectra of malignant breast tissue of patients (n = 67) suffering from infiltrating ductal carcinoma are dominated by the water resonance, while the spectra of the unaffected contralateral breast tissue of these patients are mainly dominated by resonance arising from lipids which is similar to the spectra of normal breast tissue obtained from volunteers (controls, n = 16). In addition to the water and lipid peaks, in majority of the patients (approximately 80%) the water suppressed spectra showed a resonance at 3.2 ppm due to choline containing compounds (TCho) before treatment. In patients receiving neoadjuvant chemotherapy, absence/reduction in choline was observed in 89% of the patients. TCho was also observed in 2 of 14 benign lesions. The sensitivity and specificity of in-vivo MRS in detecting TCho in malignant tumours was 78% and 86%, respectively. Observation of TCho before treatment and its disappearance (or reduction) after treatment may be a useful indicator of response of locally advanced breast cancer to neoadjuvant chemotherapy.

Adult↗
PubMed2001

Rotational dynamics of surface probes in lipid vesicles.

Translational and rotational diffusion of fluorescent molecules on the surface of small biological systems such as vesicles, proteins and micelles depolarize the fluorescence. A recent study has treated the case of the translational dynamics of surface probes (M.M.G. Krishna, R. Das, N. Periasamy and R. Nityananda, J. Chem. Phys., 112 (2000) 8502-8514) using Monte Carlo and theoretical methods. Here we extend the application of the methodologies to apply the case of rotational dynamics of surface probes. The corresponding fluorescence anisotropy decays were obtained using the Monte Carlo simulation methods for the two cases: surface probes undergoing rotational dynamics on a plane and on a sphere. The results were consistent with the theoretical equations which show that Monte Carlo methods can be used to simulate the surface diffusion problems. The anisotropy decay for the rotational diffusion of a molecule on a planar surface is single exponential and the residual anisotropy is zero. However, residual anisotropy is finite for the case of rotational diffusion on a sphere because of the spatial averaging of the anisotropy function. The rotational correlation time in both the cases is (4Drot)(-1) with Drot being the rotational diffusion coefficient. Rotational dynamics of a surface bound dye in a single giant liposome and in sonicated vesicles were studied and the results were explained according to the theoretical equations. A fast component of fluorescence depolarization was also observed for sonicated vesicles which was interpreted as wobbling-in-cylinder dynamics of the surface-bound dye.

Carbocyanines↗
PubMed2001

Status and distribution of golden langurs (Trachypithecus geei) in Assam, India.

The distribution of golden langurs (Trachypithecus geei) is limited to a small area of western Assam in northeast India and Bhutan between the rivers Manas in the east, Sankosh in the west, and Brahmaputra in the south. It is one of the most seriously endangered primate species of India. A comparative analysis based on satellite images taken in 1988 and 1998 showed a 50% loss of original golden langur habitat. Data on population dynamics collected using line transect and total count methods are presented here. An average group size of 8.2 (range 4.0-22.0) individuals was recorded. A total of 1,064 individuals were counted living in 130 groups. The sex ratio was 1.9-2.5 adult females for each adult male. A low percentage of juveniles and infants suggests that the population is unstable. Most of the groups had only one adult male. Small group sizes, isolated distribution, proportionately few infants and juveniles, and degrading habitat are all causes of concern. Demographic trends indicate a decline in the golden langur population.

Animals↗
PubMed2001

Sex- and age-of-onset-based locus heterogeneity in asthma.

Asthma is a complex disease with a genetic component. The results of genome-wide linkage studies imply that locus heterogeneity is likely to be an important feature of the genetics of asthma. To attempt to reduce locus heterogeneity, we hypothesized that the following may form the bases for locus heterogeneity at some asthma susceptibility loci: sex of affected individuals, parental origin of alleles shared by affected sib pairs, and age of onset of wheeze. Analysis of such strata may assist in the identification of novel susceptibility loci, or reveal the basis for locus heterogeneity at previously identified loci. Genotype and phenotype data from genome-wide linkage searches for asthma susceptibility loci from three populations were analyzed. Some regions demonstrated evidence for linkage to affected individuals of a particular sex. There was evidence for excess maternal allele sharing at regions on chromosomes 9 and 11. Regions on chromosomes 2 and 6 were linked to late and early age at onset of wheeze in asthma, respectively. These analyses suggest that the bases that we selected for stratification may be appropriate at certain susceptibility loci for asthma, and may therefore assist in the fine mapping of such loci. Differences in such variables between studies may explain apparent nonreplication of linkage results.

Adolescent↗
PubMed2001

Long-term outcome of xenogenic dermal matrix implantation in immunocompetent rats.

BACKGROUND: Acellular dermal matrix (ADM) has been used successfully in the treatment of full-thickness skin injuries as an allogenic dermal substitute. To assess the efficacy of xenogenic ADM in such wounds, we examined the long-term wound healing and immunological responses to porcine ADM in a rat model. MATERIALS AND METHODS: Xenogenic and allogenic ADMs were produced by treating porcine (fresh or cryopreserved) or rat skin with dispase and Triton X-100. Full-thickness skin defects on the rat dorsum were implanted with porcine or rat ADMs and overlaid with split-thickness skin grafts (STSGs). Wounds were evaluated grossly and immunologically at 1, 6, and 12 months after surgery. RESULTS: Extensive wound contraction was seen in wounds implanted with porcine ADM, but healing was significantly (P < 0.01) better in the rat ADM or STSG groups at 6 and 12 months postsurgery. Sera obtained from porcine ADM-implanted rats reacted strongly with porcine ADM and specifically with the papillary dermis and basal lamina. One month postsurgery, extensive inflammation but few intact mast cells were seen in wounds implanted with porcine ADM and significant (P < 0.02) levels of residual porcine ADM were detectable immunologically. Little inflammation was evident in the STSG or rat ADM groups at any time. Significant lymphocyte proliferation (P < 0.05) occurred in the 6- and 12-month groups in response to porcine, but not rat, ADM. CONCLUSIONS: In wounds implanted with xenogenic ADM, a short-lived acute inflammatory response, long-lasting humoral and cell-mediated immune responses, and generally poor wound healing were observed.

Animals↗
PubMed2001

Adeno-associated virus 2-mediated transduction and erythroid lineage-restricted long-term expression of the human beta-globin gene in hematopoietic cells from homozygous beta-thalassemic mice.

Adeno-associated virus 2 (AAV), a nonpathogenic human parvovirus, has gained attention as a potentially useful vector for human gene therapy. Here, we report successful AAV-mediated stable transduction and high-efficiency, long-term, erythroid lineage-restricted expression of a human beta-globin gene in primary murine hematopoietic stem cells in vivo. Bone marrow-derived primitive Sca-1(+), lin(-) hematopoietic stem cells from homozygous beta-thalassemic mice were transduced ex vivo with a recombinant AAV vector containing a normal human beta-globin gene followed by transplantation into low-dose-irradiated B6.c-kitW(41/41) anemic recipient mice. Six months posttransplantation, tail-vein blood samples were analyzed by PCR amplification to document the presence of the transduced human beta-globin gene sequences in the peripheral blood cells. Semiquantitative PCR analyses revealed that the transduced human beta-globin gene sequences were present at approximately 1 copy per cell. The efficiency of the human beta-globin gene expression was determined to be up to 35% compared with the murine endogenous beta-globin gene by semiquantitative RT-PCR analyses. Peripheral blood samples from several positive recipient mice obtained 10 months posttransplantation were fractionated to obtain enriched populations of granulocytes, lymphocytes, and erythroid cells. PCR analyses revealed the presence of the human beta-globin gene sequences in granulocytes and lymphocytes, indicating multilineage reconstitution. However, only the erythroid population was positive following RT-PCR analyses, suggesting lineage-restricted expression of the transduced human beta-globin gene. Southern blot analyses of total genomic DNA samples isolated from bone marrow cells from transplanted mice also documented proviral integration. These results provide further support for the potential use of recombinant AAV vectors in gene therapy of beta-thalassemia and sickle-cell disease.

Anemia, Sickle Cell↗
PubMed2001

Infection of purified nuclei by adeno-associated virus 2.

Adeno-associated virus 2 (AAV), a nonpathogenic human parvovirus, requires co-infection with a helper virus for its optimal replication. Although AAV possesses a broad host range, certain cell types lack the machinery necessary for efficient entry into the cell and intracellular trafficking of AAV into the nucleus, where the viral second-strand DNA synthesis must occur before gene expression. We have demonstrated that in less-permissive mouse fibroblasts, the virus fails to transport to the nucleus due to altered endocytic processing. However, relatively little is known about the intracellular site of viral uncoating and transport of the virion across the nuclear envelope. Here, we provide evidence that AAV can efficiently enter intact nuclei purified from both permissive and less-permissive cell types. Furthermore, entry into the nucleus is time- and temperature-dependent, but is not saturable and seems to occur independently of the nuclear pore complex. We also demonstrate that purified nuclei contain all of the machinery necessary for uncoating and viral second-strand DNA synthesis even in the absence of a helper virus. These studies provide new insights into the basic biology of AAV and may also have implications for the optimal use of AAV vectors in human gene therapy.

3T3 Cells↗