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S Quan

Publications and source records attributed to S Quan.

At least 55 records · Page 3Linked to original sources
PubMed1998

[The effect of interleukin-1 beta interleukin-8 in the pathogenesis of experimental colitis and evaluation of interleukin-1 receptor antagonist therapy].

OBJECTIVE: To study the effect of interleukin-1 beta and interleukin-8 in the pathogenesis of colitis and evaluate the therapeutic effect of interleukin-1 receptor antagonist(IL-1ra). METHODS: A rat model of chronic experimental colitis was induced by administration of trinitrobenzenesulfonic acid (TNBS, 30 mg) in 50% ethanol 0.25 ml. IL-1ra was then administered intravenously with a dosage of 7 mg/kg at different times. Hydrocortisone (3 mg) i.v. administration was served as control. Tissue expression of IL-1 beta mRNA and IL-8 mRNA was then studied by in situ hybridization before and after IL-1ra administration. Histological examination and tissue myeloperoxidase (MPO) and superoxide dismutase (SOD) activities detection were also made to assess the severity of colitis. RESULTS: An acute inflammation with ulcers, neutrophil infiltration and crypt abscess developed that evolved into a chronic inflammation with abundant fibrous connective tissue hypertrophy at 21 days. And it then recurs only after 10 mg TNBS administration. Activities of MPO and SOD correlated with severity of inflammation. Expression of IL-1 beta mRNA was detected in macrophages in lamina propria and submucosa during the whole period of inflammation. It could be also present in epithelial cells in the 3rd day of colitis. While IL-8 mRNA expression appeared at the 3rd day, and disappeared at 21th day when colitis turned into chronic. After IL-1ra administration, the expression of these two interleukins could not be detected, accompanied with alleviation of histological manifestation, decrease of MPO activity and elevation of SOD activity. CONCLUSIONS: IL-1 beta and IL-8 were involved in the pathogenesis of colitis. IL-1ra has preventive and therapeutic effect to colitis.

Animals↗
PubMed1997

Concordance between hepatitis C virus serotyping assays.

Hepatitis C virus testing has evolved from a simple enzyme-linked immunosorbent assay (ELISA) to complex molecular tests including qualitative and quantitative polymerase chain reaction (PCR) as well as multiple methods to determine geno and serotypes. Serotyping assays have been described and are being further refined to aid describing the epidemiology of hepatitis C virus (HCV) infection and may have a role in predicting response treatment. This study describes the concordance between two serotyping assay systems, a recombinant immunoblot assay Chiron RIBA Strip Immunoblot Assay (SIA) and a more competitive ELISA peptide assay, using PCR as the standard. Serotype was successfully determined in 144/202 (71%) patients by the Murex ELISA assay and 179/202 (89%) by the Chiron strip immunoblot assay (SIA) assay (P < 0.001). Concordance between restriction fragment length polymorphism (RFLP) and the Murex assay was 139/144 (97%) between RFLP and the Chiron SIA was 171/179 (96%) and between the Murex and Chiron SIA was 136/144 (94%). These assays provided a reliable, simple, and rapid method of determining HCV serotype.

Cohort Studies↗
PubMed1997

Typing of hepatitis C virus antibody with specific peptides in seropositive blood donors and comparison with genotyping of viral RNA.

BACKGROUND AND OBJECTIVES: Serotyping of antibody to hepatitis C virus (anti-HCV) with specific peptides has been developed as an alternate method for typing HCV infections. The method does not require a prior amplification of viral RNA sequences from the sample. Identification of the viral genotype may be relevant for prognosis and clinical management. MATERIALS AND METHODS: We used a previously described HCV serotyping assay (RIBA HCV Serotype SIA kit, Chiron Corp.) to investigate the serotype in 191 samples from blood donors selected for anti-HCV patterns (positive and indeterminate), ALT levels, and the presence or absence of viral RNA. The serotypes were compared with the genotypes obtained from typing the 5'-noncoding region of the viral RNA in 82 viremic samples. RESULTS: We were able to obtain the viral serotype in 85% (114/134) of samples positive for anti-HCV but in only 3.5% (2/57) of the indeterminates. Lack of anti-NS4 in the sample was significantly associated with both untypable results and the presence of HCV serotypes other than serotype 1. The overall correlation with genotyping was 78% (64/82), rising to 95.5% (64/67) if only samples that could be both genotyped and serotyped were considered. The assay was easy to perform, gave reactivity patterns easy to interpret, and performed with high proficiency on anti-HCV-positive samples lacking detectable levels of viral RNA. CONCLUSIONS: This is a practical and useful method for typing HCV infections in the clinical setting. The poor ability of the Core peptides to give the serotype in samples lacking anti-NS4 and the lack of specific peptides to recognize HCV types other than 1, 2, and 3 are, however, some aspects of the method that need improvement in the future.

Antibodies, Viral↗
PubMed1997

Monooxygenase-like sequence of a Rhodococcus equi gene conferring increased resistance to rifampin by inactivating this antibiotic.

A DNA clone from Rhodococcus equi conferring low-level rifampin resistance through the ability to inactivate this antibiotic via its decomposition was identified. The iri (inactivation of rifampin) gene consisted of an open reading frame of 1,437 bp encoding a 479-amino-acid sequence strongly resembling those of monooxygenases acting upon phenolic compounds or involved in polyketide antibiotic synthesis. When expressed in Escherichia coli, the gene conferred resistance to a > 50-micrograms/ml concentration of the drug.

Amino Acid Sequence↗
PubMed1997

Ribosylative inactivation of rifampin by Mycobacterium smegmatis is a principal contributor to its low susceptibility to this antibiotic.

Mycobacterium smegmatis inactivates rifampin by ribosylating this antibiotic. The gene responsible for this ability was cloned and was shown to confer low-level resistance to this antibiotic (MIC increase, about 12-fold) in related organisms. A 600-bp subclone responsible for ribosylating activity and resistance carried an open reading frame of 429 bp. Targeted disruption of the gene in M. smegmatis resulted in mutants with much increased susceptibility to rifampin (MICs of 1.5 instead of 20 microg/ml) as well as the loss of antibiotic-inactivating ability. Also, disruption of this gene led to a much lower frequency of occurrence of spontaneous high-level rifampin-resistant mutants.

Amino Acid Sequence↗
PubMed1997

Rapid and specific detection of Sin Nombre virus antibodies in patients with hantavirus pulmonary syndrome by a strip immunoblot assay suitable for field diagnosis.

To develop a rapid antibody test for Sin Nombre hantavirus (SNV) infection for diagnosis of hantavirus pulmonary syndrome (HPS) in field settings where advanced instrumentation is not available, a strip immunoblot assay bearing four immobilized antigens for SNV and a recombinant nucleocapsid protein antigen of Seoul hantavirus (SEOV) was prepared. The SNV antigens included a full-length recombinant-expressed nucleocapsid (N) protein (rN), a recombinant-expressed G1 protein (residues 35 to 117), and synthetic peptides derived from N (residues 17 to 59) and G1 (residues 55 to 88). On the basis of the observed reactivities of hantavirus-infected patient and control sera, we determined that a positive assay requires reactivity with SNV or SEOV rN antigen and at least one other antigen. Isolated reactivity to either viral rN antigen is indeterminate, and any pattern of reactivity that does not include reactivity to an rN antigen is considered indeterminate but is unlikely to represent hantavirus infection. Fifty-eight of 59 samples from patients with acute SNV-associated HPS were positive according to these criteria, and one was initially indeterminate. Four of four samples from patients with HPS due to other hantaviruses were positive, as were most samples from patients with SEOV and Puumala virus infections. Of 192 control serum samples, 2 (1%) were positive and 2 were indeterminate. Acute SNV infection was distinguishable from remote SNV infection or infection with hantaviruses other than SNV by the presence of G1 peptide antigen reactivities in the former. The strip immunoblot assay shows promise for the detection of SNV antibodies early in the course of HPS.

Antibodies, Viral↗
PubMed1997

[Commercial identification and resources survey on Chinese drug radix Ranunculi ternati].

Based on the collection of commercial products field investigation in distribution areas and main production places, and consultation of over 200 specimens the identification of traditional Chinese drug Maozhaocao was carried out. The results show that the present source of commercial "Maozhaocao" derives from 2 species of genus Ranunculus. The main species is Ranunculus ternatus, while R. polii is used only in a few regions. A resources survey of the drug was also conducted.

Conservation of Natural Resources↗
PubMed1997

Differentiation of human CD34+CD38- cord blood stem cells into B cell progenitors in vitro.

Umbilical cord blood CD34+CD38- cells are a rare, quiescent, primitive progenitor subpopulation lacking expression of lymphoid and myeloid lineage specific antigens. Although myeloid, erythroid, and megakaryocytic differentiation from these cells has been described, B lineage differentiation has not been demonstrated previously. We report here that highly enriched human B cell progenitors can be consistently generated from CD34+CD38- cord blood cells using long-term culture on the murine stromal line, S17, in the absence of added cytokines. After 6-8 weeks, cell numbers increased up to 160-fold, and cultures contained > 80-90% CD10+CD19+ B progenitors. Consistent with previous reports describing delayed myeloid cell differentiation from CD34+CD38- cells, production of B cell progenitors from CD34+CD38- cord blood cells was delayed 2-4 weeks relative to cultures initiated with either CD34+CD38bright or CD34+CD38dim progenitors. Addition of Flt3 ligand to long-term cultures resulted in a 2-3-fold greater increase in the number of CD19+ cells generated after 4-8 weeks. The selective outgrowth of B cell progenitors using this culture model will be useful for a range of in vitro studies using primitive hematopoietic progenitors.

ADP-ribosyl Cyclase↗
PubMed1996

Completion of the nucleotide sequence of sunn-hemp mosaic virus: a tobamovirus pathogenic to legumes.

Sunn-hemp mosaic virus (SHMV) is a member of the tobamovirus group of plant viruses. The nucleotide sequence of the 5'-untranslated region, the 129 kD protein gene, and a portion of the 186 kD protein gene of SHMV was determined. The 4,683 nucleotides (nts) reported here completes the sequence of the SHMV genome and complements previous work (Meshi, Ohno, and Okada, Nucleic Acids Res. 10, 6111-6117 [1982]; Mol. Gen. Genet. 184, 20-25 [1981]) to provide the first complete nucleotide sequence for a tobamovirus that is pathogenic to leguminous plants.

Amino Acid Sequence↗
PubMed1996

New strip immunoblot for the confirmation of HTLV-I/II infection.

In The Netherlands, anti-human T-cell lymphotropic virus type I (HTLV-I) blood donor screening became mandatory in January 1993. Donations reactive in the enzymelinked immunosorbent assay (ELISA) screening test are confirmed with Western blot analysis (WB). Only WB-positive or indeterminate blood donors are notified and retested by polymerase chain reaction (PCR) [1]. In accumulated data of the Dutch Blood Banks, only 2% of donors repeatedly positive in the anti-HTLV-I/II ELISA were WB-positive and all of these were also PCR-positive. However, 75% of the ELISA-positive blood donors have indeterminate WB results. In these cases the ELISA reactivities are nonspecific since all WB-indeterminate donors are negative in PCR [2]. Current WB confirmation thus leads to the notification and often to the deferral of many WB-indeterminate blood donors as well as to high costs for PCR testing, illustrating the need for a more specific serological confirmatory assay. The aim of our study was to evaluate a newly developed anti-HTLV-I/II Recombinant Immunoblot Assay (RIBA) to confirm samples reactive to screening tests with a special emphasis on the ability of this test to resolve WB-indeterminate results in blood donors, without compromising the sensitivity.

Blotting, Western↗
PubMed1995

Detection of hepatitis C after liver transplantation. Four serologic tests compared.

To determine the best method for detecting HCV infection in immunosuppressed patients, stored frozen serum from 101 liver transplant recipients was tested for hepatitis C virus. Each sample was tested by four assays. HCV RNA was detected by both polymerase chain reaction (PCR) and branched DNA signal amplification. Antibody to HCV was determined using second-generation enzyme-linked immunoassay (EIA) and recombinant immunoblot assay. Forty one transplant recipients met the working definition for true positives of HCV infection. Of these "true positives," 98% were positive by HCV RNA PCR assay, 88% by b-DNA signal amplification assay, 88% by anti-HCV EIA, and 63% demonstrated two or more reactive bands on recombinant immunoblot. Five of 57 (9%) HCV-antibody negative recipients had HCV RNA detected by both methods. Of 44 HCV enzyme-linked immunoassay (EIA) repeatedly reactive samples, the recombinant immunoblot was negative in 2 and indeterminate in 13. HCV RNA was present in 9 of 13 recombinant immunoblot indeterminate sera. Nine EIA repeatedly reactive sera were negative by both tests for HCV RNA. In liver transplant recipients, HCV infection is best determined by measurement of HCV RNA. Antibody formation may be delayed or suppressed in a minority of patients despite > 10(9) equivalents/L (> 10(6)/mL) of HCV RNA in serum. Recombinant immunoblots with a single reactive band pattern often indicate HCV infection in immunosuppressed patients.

Hepacivirus↗
PubMed1995

Evaluation of a novel serotyping system for hepatitis C virus: strong correlation with standard genotyping methodologies.

Direct sequencing and analysis of viral genomes are definitive methods for identifying various hepatitis C virus (HCV) genotypes. However, HCV genome sequencing methods are cumbersome and unsuitable for analyzing large numbers of clinical samples. We have developed a convenient, reliable, and reproducible RIBA strip immunoblot assay system for determining HCV serotype. Briefly, the assay consists of an immunoblot strip on which there are five lanes of immobilized serotype-specific HCV peptides from the nonstructural (NS-4) and core regions of the genomes of HCV types 1,2, and 3. HCV serotype is deduced by determining the greatest intensity of reactivity to the NS-4 serotype-specific HCV peptide band in relation to the intensity of the human immunoglobulin G internal control bands on each strip. HCV core peptide reactivity is used only in the absence of NS-4 reactivity. We used this assay to successfully serotype a high percentage of sera from well-documented HCV-infected patients. Our serotyping results correlated 99% with the findings from the standard restriction fragment length polymorphism genotyping methods. Less than 5% of the serum samples were untypeable. For a selected group of alpha interferon-treated patients we observed that the nonresponders (76.2%) and a majority of the responders who relapsed (72.2%) had type 2 HCV infection. A small population (n= 8) of complete responders was split 3:4:1 as type 1, type 2, and type 3, respectively. Our data indicate that this new serotyping assay has the potential to be a highly specific and reliable method for typing of HCV infection in patients.

Genotype↗
PubMed1994

Evaluation of indeterminate c22-3 reactivity in volunteer blood donors.

BACKGROUND: Approximately 25 percent of blood donor sera that are repeatably reactive for hepatitis C virus (HCV) on second-generation enzyme immunoassay (EIA 2.0) are indeterminate on second-generation recombinant immunoblot assay (RIBA 2.0), and over 76 percent of these results are due to single reactivity to the HCV recombinant antigen c22-3. STUDY DESIGN AND METHODS: Data are presented on 46 volunteer allogeneic blood donors who were reactive on EIA2.0 and c22-3 indeterminate in RIBA 2.0. Index and follow-up samples were evaluated by using a panel of five synthetic peptide EIAs, a prototype strip immunoblot assay that uses synthetic peptides in addition to recombinant protein (RIBA 3.0), and polymerase chain reaction (PCR) for HCV RNA. RESULTS: All 46 donations had normal alanine aminotransferase values; only 2 (4.3%) reacted for antibody to hepatitis B core antigen. With a panel of 12 synthetic peptides spanning the entire sequence of the c22-3 recombinant antigen, 33 plasmas (72%) reacted to one peptide or none, including 19 plasmas with reactivity restricted entirely to the N-terminal peptide (1-15 amino acids) of c22-3. With RIBA 3.0, 28 donations (61%) were nonreactive, including 25 that reacted with one peptide or none in EIA. Of these 25 plasmas, 18 reacted with the N-terminal sequence only. All 46 index donations were tested by PCR; the single PCR-positive unit reacted with four HCV peptides, was positive by RIBA 3.0, and reacted for antibody to hepatitis B core antigen. Twenty-six index donors were successfully recalled 3 to 7 months after their index donation. None seroconverted to positivity in RIBA 2.0, 1 was nonreactive, and 25 remained positive for c22-3 only. The restricted epitope reactivity in peptide EIA and RIBA 3.0 was maintained over time in all cases. All 26 of the follow-up samples tested negative by PCR. CONCLUSION: On the basis of the restricted peptide reactivity and PCR negativity of index and follow-up samples, it is concluded that the majority of c22-3 RIBA 2.0-indeterminate results are due to nonspecific cross-reactivity to restricted (principally, N-terminal) regions of HCV core antigen.

Alanine Transaminase↗
PubMed1994

Hepatitis C in HIV-infected patients with and without AIDS: prevalence and relationship to patient survival.

BACKGROUND: Limited information is available about the prevalence of hepatitis C virus in patients with human immunodeficiency virus in relation to specific risk factors or about the influence of hepatitis C virus coinfection on survival. This retrospective study addressed these questions. METHODS: The study population consisted of 512 predominantly non-intravenous drug-using male homosexuals, 224 of whom had AIDS. Samples positive for hepatitis C virus antibody by second-generation enzyme immunoassay were further tested by means of strip immunoblot assay, and for hepatitis C virus RNA by means of polymerase chain reaction amplification. A randomly selected set of enzyme immunoassay-negative samples was also tested for hepatitis C virus RNA and, if hepatitis C virus RNA positive, by a second-generation recombinant immunoblot assay. RESULTS: The prevalence of hepatitis C virus infection unaccounted for by intravenous drug use or transfusion was 11.7% by enzyme immunoassay, and 87% of sera positive by enzyme immunoassay were also positive by second-generation recombinant immunoblot assay or hepatitis C virus RNA analysis. Hepatitis C virus RNA was detectable in 53% of enzyme immunoassay-positive samples but in only about 1% of enzyme immunoassay-negative samples. Hepatitis C virus coinfection did not influence survival of HIV-infected patients with or without manifestations of AIDS. CONCLUSIONS: Hepatitis C virus infection in nontransfused, non-intravenous drug-using patients with HIV infection is several times more prevalent than in volunteer blood donors, suggesting homosexual transmission of hepatitis C virus. About half of patients seropositive for hepatitis C virus antibody have detectable hepatitis C virus RNA, and serologically occult hepatitis C virus viremia is rare. Hepatitis C virus coinfection does not appear to adversely influence survival.

Acquired Immunodeficiency Syndrome↗