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Biomedical subjects

A Srivastava

Publications and source records attributed to A Srivastava.

At least 19 recordsLinked to original sources
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

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

Perceptual development in relation to nutritional status.

The present study was conducted on 180 children in the age group 5-10 years. These children were divided accordingly their ages into 3 sub-groups i.e. 5-6, 7-8 and 9-10 years respectively. In each group 60 children were studied. For the assessment of perceptual skills each child was tested with the help of Picture Ambiguity Test. Responses to the ambiguous cards were scored with respect to time taken to react in each card and ability of the child to perceive figure and ground relationship i.e. centration and decentration. The observations showed that with increase in age, centration effect reduces and majority of the children start decentring their perception by middle childhood. Further, children in higher age group took lesser time to respond on different ambiguous cards. When the responses of well-nourished and undernourished children were compared for perceptual flexibility in terms of part-whole perception i.e. centration and decentration; no difference was observed between the two groups. There was a significant difference in the performance of well-nourished and undernourished children when time to respond on ambiguous card was compared. Well-nourished children took lesser time to respond on different ambiguous cards. These observations in general suggest that poor nutrition may result in impaired perceptual abilities in children.

Analysis of Variance↗
PubMed2001

Polymyositis--an unusual manifestation of chronic graft-versus-host disease.

Polymyositis is a rare autoimmune manifestation of chronic graft-versus-host disease (GVHD) characterized by muscle pain, weakness, and an increase in muscle-related enzymes that responds well to treatment with immunosuppressive agents such as steroids and cyclosporine. We describe a case in which polymyositis was the main manifestation of chronic GVHD that occurred 12 months after allogeneic bone marrow transplantation in a patient with acute lymphocytic leukemia (ALL). The polymyositis responded well to treatment with steroids and cyclosporine, with no relapse of symptoms on tapering of the medication.

Adolescent↗
PubMed2001

Correlation between p53 gene mutations and circulating antibodies in betel- and tobacco-consuming North Indian population.

Alterations in p53 tumour suppressor gene and its expression may be implicated in the pathogenesis of betel- and tobacco-related oral cancer. There is wide regional variation in betel- and tobacco-consuming habits in different parts of the Indian subcontinent. The purpose of this study was to determine the correlations between p53 gene mutations, protein accumulation and serum antibodies in oral precancer and cancer. We analysed 30 potentially malignant oral lesions (leukoplakia) and 30 oral squamous cell carcinomas (SCCs) from northern India because the betel quid-consuming habits are different from those prevalent in other regions of India. p53 mutations were analysed by polymerase chain reaction amplification of genomic DNA and direct sequencing, p53 protein accumulation by immunohistochemical analysis and circulating p53 antibodies by ELISA. p53 gene mutations, analysed within exons 5-9, were observed in five out of 30 (17%) potentially malignant oral lesions and seven out of 30 (23%) oral SCCs. All the mutations were base substitution mutations. Three missense and two nonsense mutations were observed in potentially malignant oral lesions, while six missense and one nonsense mutations were identified in oral SCCs. The probable hot spots for the mutations were identified at codons 126, 136 and 174, which have not been observed thus far. A good correlation was observed between p53 missense mutation, p53 antibodies and p53 protein accumulation in matched potentially malignant and malignant oral lesions. All the potentially malignant and cancerous lesions harbouring missense mutations showed accumulation of p53 protein and the majority of these patients showed circulating p53 antibodies suggesting that serological detection of p53 antibodies may serve as a surrogate marker for p53 alterations in oral lesions.

Adolescent↗
PubMed2001

Sequential anastomosis of accessory renal artery to inferior epigastric artery in the management of multiple arteries in live related renal transplantation: a critical appraisal.

In live related renal transplant program, management of multiple renal arteries (MRA) is technically demanding and used to be considered a relative contraindication because of increased risk of vascular and urologic complications. We present a retrospective analysis of the outcome of grafts with MRA and suggest certain guidelines. Of the 680 live related kidney transplantations done, 53 allografts had MRA. Cases were grouped according to the reconstruction technique: group A, MRA reconstructed ex vivo into a single renal artery (n=27); group B, MRA with multiple anastomoses in vivo (n =13); group C, MRA with sequential revascularization using inferior epigastric artery (n=11). We compared serum creatinine, acute tubular necrosis, rejection rates and the rewarm ischemia time between the three groups. Overall patient survival and graft survival were excellent (100 and 96%). Mean serum creatinine at 1 yr did not differ significantly between the three groups. Rewarm ischemia time was significantly less in group C (p<0.01). Incidence of acute tubular necrosis and rejection episodes was also less in group C although the difference was statistically significant only between group C and group B. We conclude that allografts with MRA can be used successfully in a live related renal transplantation program. Bench reconstruction should be done whenever possible. For reconstruction of an accessory vessel, inferior epigastric artery with sequential revascularization is recommended.

Adolescent↗
PubMed2001

Cyclosporin A withdrawal in live related renal transplantation: long-term results.

Cyclosporin A (CsA) withdrawal after 1 yr of stable graft function has been shown to be beneficial in cadaveric renal transplantation. This strategy could be even more suitable for 'immunologically advantaged' grafts as in live related renal transplantation. We report the long-term outcome of patients in a live related transplantation programme undergoing early (between 1989 and 1992) and late (1993 onwards) CsA withdrawal as compared with those on long-term low dose CsA (1993 onwards). Two-hundred and fifty-two patients were divided into three groups based on the following immunosuppressive protocol: group ECyW (n=99), early CsA withdrawal (9 months after transplantation); group LCyW (n=44), late CsA withdrawal (median 16 months, range 13--22 months after transplantation); and group LDCy (n=109), long-term low dose CsA. The median period of follow-up was 66 months after transplantation (range 43--84 months). There was no difference in the actuarial 6-yr patient or graft survival among the three groups. Acute rejection episodes were more frequent in ECyW (54.4%) than in LDCy (31.8%) and LCyW (23.8%) (p=0.001). The risk of developing late (> or =9 months) acute rejection was highest in ECyW 32/99 (32.3%) as compared with LCyW 8/44 (18.4%; p=0.08) and LDCy 8/109 (7.3%; p=0.0001). Of the 32 ECyW patients who developed acute rejection episodes after CsA withdrawal, 13 (40.6%) lost their grafts either due to uncontrolled acute rejection or to chronic rejection. Chronic rejection was higher in ECyW (24%) than in LCyW (11%; p=0.04) and LDCy (17%; p=0.17). Antihypertensive requirement was highest in patients maintained on low dose CsA. Graft function, as measured by serum creatinine levels, was significantly better in LCyW (1.24+/-0.4 mg%) as compared with ECyW (1.49+/-0.5 mg%) and LDCy (1.48+/-0.6 mg%). Early CsA withdrawal after live related renal transplantation is associated with a significant risk of acute rejection and subsequent chronic rejection. Slow withdrawal after 1 yr is safe and more economical than the long-term administration of low dose CsA.

Acute Disease↗
PubMed2001

Tuberculosis among allogeneic bone marrow transplant recipients in India.

Allogeneic bone marrow transplant recipients have severe impairment of cell-mediated immunity and hence a higher incidence of mycobacterial infections might be expected in regions where tuberculosis is common. We reviewed the case records of 217 patients who underwent allogeneic bone marrow transplantation during the period 1986-1999 at our center in India. Mycobacterial infections were diagnosed in three patients (1.38%). All patients presented with extrapulmonary disease. Two patients had disseminated tuberculosis with one of these being diagnosed on autopsy studies. The third patient had tuberculosis involving the cervical lymph node and dorsal spine. Two patients treated with antituberculous therapy are well. Infection with Mycobacterium tuberculosis is not a common problem in allogeneic bone marrow recipients even in an endemic area, but when it occurs, it is usually disseminated with predominantly extrapulmonary involvement.

Adult↗
PubMed2001

Choice of factor concentrates for haemophilia: a developing world perspective.

Provision of factor concentrates continues to be the single greatest challenge in providing effective haemophilia care in the developing world. While concerns for ultimate safety and very high purity dominate the selection of factor concentrates in developed countries, availability and cost are the pressing issues in developing countries. There certainly is concern for reasonable safety but purity is often considered an unaffordable luxury. Cost-effective protocols need to be designed for factor replacement in these countries where liberal on-demand therapy and prophylaxis are not possible. It is also essential to establish a good transfusion service for collecting adequate quantities of safe plasma. Support from government and health insurance is required to allow access to at least modest quantities of virus-inactivated factor concentrates. Depending on the situation in each country, factor concentrates may be imported, contract-fractionated or locally produced. Paradigms of effective management of this problem exist within the developing world. Until such time as these examples are widely emulated, less safe products will continue to be used in situations where a distinction frequent needs to be made between what is ideal and what is practical.

Blood Coagulation Factors↗
PubMed2001

Autoimmune liver disease in children.

BACKGROUND AND AIM: Autoimmune liver disease (AILD) in children progresses to cirrhosis and liver failure if not diagnosed and managed in time. We prospectively analyzed our patients with liver disease for autoimmune etiology and their outcome with treatment. METHODS: All patients with liver disease were evaluated with liver function tests, abdominal ultrasonography, endoscopy, liver biopsy, viral markers and investigations for Wilson's disease. Immunoglobin (Ig)M hepatitis A virus, hepatitis E virus (HEV) and IgM hepatitis B core antibody were tested if acute viral hepatitis was suspected. Antinuclear antibody (ANA), antismooth muscle antibody (SMA), and liver kidney microsomal antibody (anti-LKM-1) were done in all cases. Autoimmune liver disease was diagnosed when one or more autoantibodies tested positive (> 1:40), and no other etiology of liver disease was identified. We also applied criteria proposed by the International Autoimmune Hepatitis Group. Cases diagnosed to have AILD were treated with immunosuppressive drugs. RESULTS: Autoimmune liver disease constituted 3.9% (6/153; median age and duration of illness 8.5 years and 3 months, respectively) of chronic liver disease cases. Four patients had acute hepatitis-like presentation. Of the six cases, two each were ANA and SMA +; one was anti-LKM-1 +, and the other was positive for both SMA and anti-LKM-1. Three of the patients achieved remission with combination therapy of oral prednisolone (OP) and azathioprine (AZT), and one with only OP. The other two patients were not treated. Two of the patients in remission have been weaned off from immunosuppressive therapy, and one is in a withdrawal phase. Another patient, while in biochemical remission developed superimposed anicteric acute HEV infection. CONCLUSION: Although AILD is uncommon in children, its search is rewarding, as remission is achieved with immunosuppressive therapy. Superimposed acute viral hepatitis can occur in endemic areas.

Adolescent↗
PubMed2001

Inter-pregnancy folate and iron status of women in an inner-city population.

The purpose of the present study was to evaluate whether micronutrient supplementation improved the nutritional status of women with poor diets during the inter-pregnancy interval. Fifty-five women who had given birth to a low birth weight baby (<2.5 kg), and who planned to have a further pregnancy, were recruited to a prospective randomised study in East London, UK. Of the fifty-five mothers recruited, forty-four (78 %) met fewer than four of sixteen dietary reference values according to the information provided in a 7 d diet diary, and were categorised as having an 'inadequate' diet. Half of the mothers in the 'inadequate'-diet group were randomly assigned to receive a micronutrient and a single cell oil supplement containing docosahexaenoic acid. All participants received dietary advice based on analysis of their diet diaries, and general lifestyle advice on preparing for pregnancy. Mothers had a blood sample taken at 3 and 9 months post-partum to measure their folate, Fe stores and fatty acid status. Mean serum and erythrocyte folate levels increased significantly between 3 and 9 months post-partum in both the adequate-diet group and the supplemented group. At 9 months post-partum, over half of the unsupplemented, inadequate-diet group remained severely deficient in folate (serum folate <230 nmol/l) and had low serum ferritin levels (<15 microg/l). The high prevalence of inadequate diets in this inner-city population and the low motivation of women to participate in a nutrition programme suggests that consideration should be given to the provision of free folate and Fe supplements to all women in this and similar populations, or at least to women who have delivered a low birth weight baby, who plan further pregnancies.

Adolescent↗