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S Dash

Publications and source records attributed to S Dash.

At least 19 recordsLinked to original sources
PubMed2006

Identified baryon and meson distributions at large transverse momenta from Au + Au collisions at square root sNN=200 GeV.

Transverse momentum spectra of pi+/-, p, and p up to 12 GeV/c at midrapidity in centrality selected Au + Au collisions at square root sNN=200 GeV are presented. In central Au + Au collisions, both pi +/- and p(p) show significant suppression with respect to binary scaling at pT approximately >4 GeV/c. Protons and antiprotons are less suppressed than pi+/-, in the range 1.5 approximately < pT approximately < 6 GeV/c. The pi-/pi+ and p/p ratios show at most a weak pT dependence and no significant centrality dependence. The p/pi ratios in central Au + Au collisions approach the values in p + p and d + Au collisions at pT approximately >5 GeV/c. The results at high pT indicate that the partonic sources of pi+/-, p, and p have similar energy loss when traversing the nuclear medium.

Journal Article↗
PubMed2006

Strange baryon resonance production in sqrt s NN=200 GeV p+p and Au+Au collisions.

We report the measurements of Sigma(1385) and Lambda(1520) production in p+p and Au+Au collisions at sqrt[s{NN}]=200 GeV from the STAR Collaboration. The yields and the p(T) spectra are presented and discussed in terms of chemical and thermal freeze-out conditions and compared to model predictions. Thermal and microscopic models do not adequately describe the yields of all the resonances produced in central Au+Au collisions. Our results indicate that there may be a time span between chemical and thermal freeze-out during which elastic hadronic interactions occur.

Journal Article↗
PubMed2006

Non-specific immune parameters of brood Indian major carp Labeo rohita and their seasonal variations.

Different non-specific immune parameters and their seasonal changes in brood Indian major carp Labeo rohita reared in two major freshwater aquaculture regions of India viz. West Bengal and Orissa were investigated. It was undertaken for 2 consecutive years and included three main seasons of a year such as summer (March-May), rainy (July-September) and winter (November-January). Total serum protein, albumin and globulin levels were not significantly different throughout the year (p>0.01). Serum lysozyme and myeloperoxidase activities were lower (7.26+/-0.87mg/ml and, 0.54+/-0.11 OD, respectively) in winter as compared to any other season of the year. The bacterial agglutination titer was higher (p<0.01) in the rainy season (8.70+/-1.70) compared to summer and winter seasons (3.40+/-0.60 and 4.00+/-0.89, respectively). Haemagglutination and haemolytic activities did not vary (p>0.01) throughout the year. In blood smears, lymphocyte percentage was higher (75-80%) as compared to those of neutrophil (10-15%) and monocytes (5-10%) but eosinophilic granulocytes were present only in few cases. The differential leucocyte count did not vary significantly (p>0.05) in any season. This study indicated that certain non-specific immune parameters of this species can be modulated at certain times of the year.

Animals↗
PubMed2005

Passive transfer of maternal antibodies and their existence in eggs, larvae and fry of Indian major carp, Labeo rohita (Ham.).

Lack of immune competence in the early stages of life leads to severe mortality in larval stages of different fish species including Indian major carp (IMC). Investigation through indirect enzyme linked immunosorbent assay (ELISA) and agglutination test revealed a significant increase in specific serum antibody response in the brood fish of Indian major carp, Labeo rohita (Ham.) following immunisation with a virulent Aeromonas hydrophila bacterin 1 month prior to breeding, which was transferred to larvae through the egg. No significant differences (P > 0.05) in mean antibody levels in larvae at the 1st and 2nd weeks post-hatch was recorded while a slight rise in antibody level was observed in 3-week-old fry, perhaps due to exposure to A. hydrophila present in the aquatic environment. Immunised brood fish serum, egg and larval extracts in non-reducing sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and subsequent western blot analysis revealed an antibody molecule of approximate molecular weight 210 kDa. On challenge with virulent A. hydrophila, a significant reduction in mortality was recorded in immunised larvae and fry (58.0, 43.75 and 37.14% in the 1st, 2nd and 3rd week, respectively) relative to control fish (87.0, 79.0 and 76.4% in 1st, 2nd and 3rd week, respectively). The present study indicated the role of maternally derived antibody in protection of hatchlings of Indian major carp against specific pathogens.

Aeromonas hydrophila↗
PubMed2003

Stem-loop structures II-IV of the 5' untranslated sequences are required for the expression of the full-length hepatitis C virus genome.

The 5' and 3' untranslated regions (UTR) of the hepatitis C virus (HCV) genome contain stem-loop structures, which are important in viral gene expression and replication. In this study, the functional roles of the predicted stem-loop structures of HCV 5' UTR and 3' UTR in viral gene expression were examined using a chimeric clone of full-length HCV genomic cDNA clone and the gene for green fluorescent protein (GFP). High level expression of the HCV-GFP chimera in Huh-7 cells was accomplished by using a replication defective adenovirus that expresses T7 RNA polymerase and transcription plasmid containing full-length HCV-GFP chimera under the control of a T7 promoter. The HCV-GFP clone, with deletion of stem-loop I, expressed proteins in transfected Huh-7 cells at comparable levels to the wild type HCV clone. Other mutations of the 5' UTR, which either deleted or altered the base pairing of stem-loops II to IV, completely abolished the expression of HCV-GFP chimera. In contrast, deletion of 3' UTR sequences had no effect on HCV protein expression. These findings suggest that the stem-loop structures II to IV of HCV 5' UTR are necessary for protein expression, but that stem loop I is dispensable for protein translation. The stem-loop structures of 3' UTR of HCV genome appear to have no direct role in viral gene expression.

3' Untranslated Regions↗
PubMed2003

Raman scattering investigations of nanocrystalline thorium oxide.

Raman scattering investigations are carried out on nanocrystalline thorium oxide powders. Shift and broadening of the Raman peak associated with F2g phonons are observed for the nanocrystalline samples as compared with those of the bulk. The peak shift and broadening are found to increase further as the particle size decreases. A quantitative analysis of the Raman line shape is carried out with a Gaussian confinement model, and the estimated size is found to be consistent with that obtained from X-ray diffraction and transmission electron microscopy.

Crystallization↗
PubMed2001

Hepatitis C virus protein expression induces apoptosis in HepG2 cells.

The mechanisms of hepatocyte death and the events that lead to a high rate of chronic liver disease in patients infected with hepatitis C virus are not known. We established a HCV replication system in HepG2 cell culture and utilized this model to address the effect of HCV proteins on HepG2 cell growth and viability. After transfection of HepG2 cells with full-length RNA, a truncated RNA, or an antisense RNA, cell proliferation and cell viability were analyzed by thymidine uptake and the trypan blue exclusion method, respectively. Full-length RNA transfected HepG2 cells showed a decrease in cell proliferation and viability compared to cells transfected with HCV truncated RNA and antisense RNA control. A subset of cells expressing HCV proteins underwent apoptosis as documented by morphological studies, ultrastructural analysis, cell cycle analysis by flow cytometry, terminal transferase enzyme mediated end labeling of DNA, and DNA laddering. This study suggests that expression of HCV proteins can lead to cell death by apoptosis, which may be an important event in the pathogenesis of chronic hepatitis C virus infection in humans.

Apoptosis↗
PubMed2001

Transmission of HCV to a chimpanzee using virus particles produced in an RNA-transfected HepG2 cell culture.

It was demonstrated previously that HepG2 cells produce negative strand RNA and virus-like particles after transfection with RNA transcribed from a full-length hepatitis C virus (HCV) cDNA clone [Dash et al. (1997) American Journal of Pathology, 151:363-373]. To determine in vivo infectivity of these in vitro synthesized viral particles, a chimpanzee was inoculated intravenously with HCV derived from HepG2 cells. The infected chimpanzee was examined serially for elevation of liver enzymes, for the presence of HCV RNA in the serum by reverse transcription nested polymerase chain reaction (RT-PCR), anti-HCV antibodies in the serum, and inflammation in the liver. The chimpanzee developed elevated levels of liver enzymes after the second week, but the levels fluctuated over a 10-week period. HCV RNA was detected in the serum of the chimpanzee at the second, seventh and ninth weeks after inoculation, and remained positive up to 25 weeks. Liver biopsies at Weeks 18 and 19 revealed of mild inflammation. Nucleotide sequence analysis of HCV recovered from the infected chimpanzee at the second and ninth weeks showed 100% sequence homology with the clone used for transfection studies. Serum anti-HCV antibodies were not detected by EIA during the 25 weeks follow-up period. These results suggest that intravenous administration of the virus-like particles derived from RNA-transfected HepG2 cells are infectious, and therefore, the pMO9.6-T7 clone is an infectious clone. These results provide new information that in vitro synthesized HCV particles produced from full-length HCV clone can cause infection in a chimpanzee. This study will facilitate the use of innovative approaches to the study of assembly of HCV particles and mechanisms of virus infectivity in cell culture.

Alanine Transaminase↗
PubMed2001

Hepatitis C viral proteins affect cell viability and membrane permeability.

To determine the effect of hepatitis C virus (HCV) proteins on cell growth, Huh-7 cells were transfected with a full-length HCV cDNA (pMO9.6-T7 Rz) clone and HCV proteins were expressed using a replication-defective adenovirus that encodes the gene for the T7 RNA polymerase. Expression of HCV proteins from this full-length clone resulted in reduction in viability of transfected cells as measured by trypan blue viability assay. For identification and separation of cells expressing hepatitis C virus proteins by fluorescence microscopy and flow cytometry, GFP was cloned in the HCV full-length clone. Cells transfected with the HCV-GFP chimera clone produced high levels of accurately processed structural and nonstructural proteins similar to those of the HCV full-length clone, which could be detected by Western blot analysis. Cells expressing all HCV proteins lost membrane permeability and underwent apoptotic cell death, indicated by the appearance of a sub-G0 peak in cell cycle analysis, DNA fragmentation in a TUNEL assay, and microscopic detection of nuclear condensation. Using double-channel flow analysis we confirmed that high-level expression of HCV proteins affected membrane permeability and cell survival. These results suggest that expression of all structural and nonstructural proteins from HCV cDNA in hepatic cells induces apoptotic cell death, which might be an important event in chronic hepatitis infection in humans.

Apoptosis↗
PubMed2001

Inducible model to study negative strand RNA synthesis and assembly of hepatitis C virus from a full-length cDNA clone.

An inducible in vitro cell culture system was developed to assay HCV replication by direct biochemical means. A transcription plasmid containing a T7 promoter at the 5' end, full-length cDNA of the HCV genome, a ribozyme sequence from the antigenomic strand of hepatitis delta virus and a T7 terminator was prepared. To facilitate high-level transcription of HCV RNA, HepG2 cells were infected with replication deficient adenovirus containing the T7 RNA polymerase gene and later transfected with the transcription plasmid containing the full-length HCV genome. This transfection-based cell culture system expressed high levels of HCV structural (core, El and E2) and non-structural proteins (NS3 and NS5B) detectable by Western blot and immunofluorescence assays. Production of HCV RNA transcripts and presence of replicative negative strand of HCV was confirmed by ribonuclease protection assay indicating replication of HCV in the transfected HepG2 cell. The transfected HepG2 cells assembled 50-60 nm virus-like particles, which could be aggregated by anti-E2 antibodies. This model can be utilized for studying mechanisms of HCV replication, assembly of HCV particles and to test potential anti-HCV compounds.

Cloning, Molecular↗
PubMed2001

[Adenovirus induced acute hepatitis in non-human primates after liver- directed gene therapy].

OBJECTIVE: To define the role of lymphocyte subsets and investigate the efficiency of immunosuppression regimen in acute hepatitis in non-human primates after adenovirus mediated gene therapy. METHODS: Six rhesus monkeys were infused with E-1 deleted adenovirus (Ad) expressing E coli lacZ gene or luciferase by various routes. Four of 6 animals were immunosuppressed by cyclophosphamide and predenisone. Two monkeys were transfected with a lacZ containing plasmid with lipofectamine as the control. Lymphocyte subsets CD3, CD4, CD8, CD20 and MHC molecule beta2-microglobulin(beta2-MG) and HLA-DR in liver tissues were studied using immunohistochemical staining. RESULTS: Staining of beta2-MG and HLA-DR on the membranes of hepatocyte and increased numbers of CD3+, CD4+ and CD8+ T-lymphocytes were detected in the livers after gene transfer, while B-lymphocytes were absent. The monkeys developed a mild to moderate transient hepatitis. This was accompanied by adenovirus-mediated T-cell proliferation and neutralizing antibodies to adenovirus. Drug-induced immune suppression enhanced the ability of adenovirus- mediated gene transfer. The development of acute hepatitis and the accompanying immune abnormalities were delayed in immunosuppressed monkeys until after discontinuation of immunosuppressive therapy. Lipofectamine-mediated gene transfer was inefficient and no immune response and liver damage were observed in the livers. CONCLUSIONS: Increased numbers of beta2-MG, HLA-DR, CD3, CD4 and CD8 antigen positive cells are presented in the monkey livers after adenovirus-mediated gene therapy and induce mild to moderate transient hepatic inflammation. Immunosuppression regimen may prolong transgene expression and delay the development of acute adenoviral hepatitis.

Adenoviridae↗
PubMed2000

HCV RNA levels in hepatocellular carcinomas and adjacent non-tumorous livers.

To determine the antiviral effects of drugs targeted to hepatitis C virus (HCV) in chronic hepatitis patients, an accurate quantitative method with high sensitivity is needed. Reverse transcription nested polymerase chain reaction (RT-PCR) is the most sensitive method for the detection of HCV sequences in clinical specimens. However, this method is not quantitative. For this purpose, a quantitative competitive assay was developed that combines RT and PCR followed by image analysis to quantify HCV RNA. This assay targets the highly conserved 5' non-coding region of HCV and is based on the co-amplification of wild type HCV RNA with known amounts of mutant synthetic RNA. The mutant internal control used in these experiments differs from the wild type RNA by two nucleotide substitutions, which introduces an internal restriction enzyme site. In this report, this method was used to determine the levels of positive strand RNA in 11 HCV positive hepatocellular carcinomas (HCC) and compared these with adjacent non-tumorous liver tissue. To confirm that the difference in viral titers is not related to variations in the amount of RNA used in the assay, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) mRNA was also assessed by competitive RT-PCR in all tissue extracts. Using this competitive assay it was determined that HCV RNA levels in the liver and tumor samples ranged from 10(3) to 10(6) molecules per microg of total RNA which is similar to previous reports. Interestingly, the amount of HCV in all the non-tumorous liver specimens were found to be significantly higher (P<0.05) than the surrounding tumors, while the GAPDH mRNA levels were found to be similar in both liver and tumor. Competitive RT-PCR is a sensitive, accurate and reliable method to determine HCV titers in clinical specimens. Using this method it was determined that malignant tumor cells harbor less HCV as compared with the surrounding non-tumorous liver cells.

Carcinoma, Hepatocellular↗
PubMed2000

Detection of hepatitis C virus RNA sequences in B-cell non-Hodgkin lymphoma.

Serologic testing shows that hepatitis C virus (HCV) may have a role in the pathogenesis of B-cell non-Hodgkin lymphomas (B-cell NHLs). We tried to demonstrate HCV RNA sequences in paraffin-embedded tissue from B-cell NHLs by reverse-transcription double polymerase chain reaction (RT-PCR) and Southern blotting. We studied 31 consecutive cases of B-cell NHLs; lymph nodes from 32 patients with diseases other than B-cell NHL were negative controls. Positive-strand HCV RNA was tested with primers for the 5' untranslated region. Replicative negative strand HCV RNA was tested with strand-specific RT-PCR for the 5' untranslated region. Immunohistochemical staining for HCV was done using an antibody to HCV core protein. Positive-strand HCV RNA was detected in 8 patients with B-cell NHL; negative-strand HCV RNA was detected in 6 of these cases, indicating viral replication. All control cases were negative for HCV RNA. Immunohistochemistry showed no staining of lymphoma cells for HCV core proteins in any case. HCV and B-cell NHLs may be associated. RT-PCR on paraffin-embedded lymphoma tissue is an alternative method of testing for HCV. The value of immunohistochemistry could not be ascertained. The exact role of HCV in the pathogenesis of B-cell NHL needs to be studied further.

Adolescent↗
PubMed2000

Partial hepatectomy and laparoscopic-guided liver biopsy in rhesus macaques (Macaca mulatta): novel approach for study of liver regeneration.

BACKGROUND AND PURPOSE: Although valuable information has been gained using a rodent partial hepatectomy model to assess liver regeneration, the ability to apply this research to humans remains uncertain. Thus, liver regeneration was assessed in a non-human primate, the rhesus macaque (Macaca mulatta). METHODS: One animal underwent 60% hepatectomy, a second animal underwent 30% hepatectomy, and control surgery (cholecystectomy) was performed on two separate animals. Laparoscopic-guided liver biopsy was performed on days 1, 2, 7, 14, and 30 after surgery. Changes in hemoglobin concentration and alanine transaminase activity were assessed, and liver regeneration was evaluated by measuring the expression of Ki-67. RESULTS: All animals survived surgery and laparoscopy. Substantial liver regeneration was induced in the animal that underwent 60% hepatectomy. Excellent tissue specimens were obtained via laparoscopic-assisted liver biopsy. CONCLUSIONS: Sixty percent partial hepatectomy in rhesus macaques appears to be an excellent model for the study of hepatocellular regeneration. The procedure was safe, and effectively induced liver regeneration. In addition, laparoscopic-guided liver biopsy allows observation of changes in the liver remnant as regeneration develops, and provides excellent tissue specimens for analysis. Thus, this rhesus macaque partial hepatectomy model will allow further characterization of liver regeneration in a species closer to humans.

Animals↗
PubMed2000

Detection of hepatitis C virus RNA sequences in cholangiocarcinomas in Chinese and American patients.

OBJECTIVE: To investigate the role of hepatitis C virus (HCV) in the malignant transformation of bile duct cells. Tissues from 6 Chinese patients and 6 American patients with cholangiocarcinoma were studied. METHODS: RNA was extracted from the selected tumor areas of formalin-fixed, paraffin embedded sections, followed by reverse transcription double polymerase chain reaction (RT-PCR) and Southern blotting. RESULTS: Positive and negative strand HCV RNA sequences were detected in seven out of twelve patients with cholangiocarcinoma. A high positive rate was found in Chinese patients (83%) as compared to US patients (33%). CONCLUSION: Our finding suggests HCV may play a role in the malignant transformation of bile duct cells.

Adult↗
PubMed1999

Effect of schistosomiasis and hepatitis on liver disease.

Infection with hepatitis C virus (HCV) has become the most important public health problem in Egypt. In Egypt, viral hepatitis along with infection with Schistosoma mansoni is the major cause of chronic liver disease and liver cirrhosis. Although HCV infection is highly prevalent in Egypt, very little information is available on the distribution of the different genotypes of HCV. Our aims in this study were first to determine the prevalence of viral and parasite infections in patients with chronic liver disease and then to assess the distribution of HCV genotypes in these patients. In the present study, 151 individuals (50 with chronic liver disease, 51 with chronic diseases of organs other than the liver, and 50 apparently healthy persons) were investigated. The last 2 groups served as control groups. These individuals were subjected to routine liver function tests and detection of serum antibodies to bilharziasis, hepatitis B surface antigen (HBsAg), and HCV. Furthermore, the presence of hepatitis G virus (HGV) and HCV in the serum samples were tested for by a reverse transcription polymerase chain reaction (RT-PCR). Prevalence of different genotypes of HCV in patients positive for HCV were determined by RT-PCR using type-specific primers. Results of the study revealed that 84, 74, 12, and 20% of patients with chronic liver disease were positive for Schistosoma mansoni, HCV, HBsAg, and HGV, respectively, as compared to 51, 43.1, 2, and 4% of patients with other chronic diseases and 22, 6, 0, and 0% of apparently healthy individuals. One hundred percent of patients with chronic liver disease, 72.5% of those with other diseases, and 26% of normal controls were shown to have at least one of the studied infectious agents. Two or more of the agents were highly coincident in patients with chronic liver disease. In Egypt, HCV genotype 4a is highly prevalent, where it contributed 85% of the tested samples in comparison to 10, 2.5, and 2.5% for subtypes 1b, 2a, and 3a, respectively. In conclusion, these results suggest that in Egypt, HCV along with schistosomal parasite infection is the major risk factor for chronic liver disease. In most Egyptian patients, HCV genotype 4 is highly prevalent.

Adult↗
PubMed1999

Successful treatment of methotrexate induced nodulosis with D-penicillamine.

Accelerated nodulosis is a recognized complication of methotrexate (MTX) therapy in rheumatoid arthritis (RA). We describe 3 patients with accelerated nodulosis treated with D-penicillamine (D-Pen) while continuing MTX. The combination of D-Pen with MTX therapy resulted in regression of subcutaneous nodules in all patients, disappearance of pulmonary nodules in one patient, and resolution of vasculitic lesions in 2 patients. Clinical response was observed within the first few weeks of therapy and usually required moderate doses (500 mg/day). Our observations suggest that addition of D-Pen to MTX therapy can be an alternative therapeutic option for accelerated nodulosis in patients with RA.

Aged↗