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Biomedical subjects

C Su

Publications and source records attributed to C Su.

At least 73 records · Page 4Linked to original sources
PubMed1998

[Preparation of monoclonal antibodies against hepatitis E and its application].

OBJECTIVE: To study the particle of hepatitis E virus (HEV) and its significance in specific diagnosis for hepatitis E (HE). METHODS: Four strains of monoclonal antibodies (McAb) against HEV, 5B12, 5F1, 5B9 and 4G10, were prepared with HEV antigen (used as immunogen) expressed by genetic engineering and detected by indirect enzyme-linked immunosorbent assay (ELISA) with purified synthetic polypeptide antigen. RESULTS: The monoclonal anti-HEV prefared could produce inhibitory reaction with anti-HEV positive serum and combined specifically with HEV particle forming virus-antibody complex seen clearly under electron microscope. CONCLUSION: McAb against HEV so prepared with high specificity can be used to detect and identify HEV.

Antibodies, Monoclonal↗
PubMed1998

Detection of gsp oncogene in growth hormone-secreting pituitary adenomas and the study of clinical characteristics of acromegalic patients with gsp-positive pituitary tumors.

OBJECTIVE: To investigate the incidence and clinical characteristics of gsp oncogene positive growth hormone-secreting adenomas of Chinese acromegalic patients. METHODS: Continuously 40 patients were studied. Serum hormone levels of pituitary and target glands were measured and growth hormone (GH)-TRH stimulating tests were done before transsphenoidal or transfrontal hypophysectomy. Deoxyribonucleic acid (DNA) was extracted from the frozen tumor tissue, and the DNA fragment encompassing codon 201 and 227 of the Gs alpha gene was amplified by polymerase chain reaction (PCR). Point mutations at codon 201 and 227 were detected using PCR direct sequencing method in order to get the incidence of gsp oncogene in GH secreting adenomas. RESULTS: Of 40 tumors studied, 22 (55%) were gsp positive. The point mutation from CGT (Arg) to TGT (Cys) at codon 201 was detected in 21 pituitary tumors, but the point mutation from CAG (Gln) to CTG (Leu) at codon 227 of the Gs alpha gene was found in only 1 tumor. All of the point mutations are heterozygous. The number of gsp positive patients which have 30% or more decrease of serum GH concentration after glucose inhibition is less than that of gsp negative patients (P = 0.042). Compared to gsp negative patients, most of gsp positive patients showed paradoxical response to TRH stimulation (P = 0.002). There were more gsp positive patients with the tumor diameter less than 25 mm (P = 0.029) and with normal GH levels in OGTT after surgery (P = 0.007). CONCLUSIONS: Gsp mutation is one of the major intrinsic defects in the pathogenesis of growth hormone-secreting pituitary tumors and the identification of gsp mutation can be a reference for classification and prognosis of GH tumors.

Acromegaly↗
PubMed1998

[A new rat brain-glioma model].

OBJECTIVE: To build a new rat brain glioma model with LacZ as a reporter gene. METHODS: Plasmid BAG was transfected into C6 glioma cell. The cell cycle, cell proliferation, malignant infiltrative ability of wild and transfected glioma cell were observed. Rat glioma model was built using stereotaxic implantation. RESULTS: There was no difference between transfected and wild glioma cell in cell growth characteristics and tumorigenesis. CONCLUSIONS: It was easy to observe the infiltrative area on cellular level from the rat glioma model made by transfected tumor cell. The method is satisfactory for radiation and chemotherapeutic trials of glioma.

Animals↗
PubMed1998

[Non-invasive determination of human oxygen metabolism during exercise].

Human muscle oxygenation during exercise was studied with near - infrared spectroscopy (NIRS). Ten athletes performed a 12 min aerobic cycling exercise with increasing workloads. Muscle oxygen content (OC), blood lactate (Bla) and heart rate (HR) were measured continuously throughout the test. The values measured showed a linear correlation (r = -0.962) between Bla and OC during aerobic exercise. The athletes and controls were also selected to compare the variation of OC, Bla and HR under exercise of the same workload. In addition, the muscle oxygen decrease and recovery during sprint were determined and discussed. The results demonstrated that NIRS provides an advantageous method for evaluation of oxygen supply and consumption in working muscles during exercise of varying intensity.

Evaluation Studies as Topic↗
PubMed1998

[Researches on immunogenicity identification of recombinant Sj22.6(rSj22.6) kDa antigen gene of schistosoma japonicum].

AIM: To identify the immunogenicity and the potentiality of rSj22.6 as a candidate vaccine antigen for schistosomiasis japonica. METHODS: rSj22.6 was tested by Western blot with specific antibodies to identify its immunogenicity. The rSj22.6 protein was isolated and purified by SDS-PAGE and injected twice into rabbits to raise antirSj22.6 serum that was tested by Western blot to recognize the native protein of adult S. japonicum and SEA. C57 mice were immunized with rSj22.6 and challenged with S. japonicum cercariae to identify the protective immunity raised by rSj22.6. RESULTS: rSj22.6 could be recognized by specific antibodies and could stimulate the rabbits to produce high level of anti-rSj22.6 antibodies. Anti-rSj22.6 serum could recognize an adult native protein with the same molecular weight as rSj22.6. The preliminary immune-challenge test resulted in significant reduction in adult worm burden. CONCLUSION: rSj22.6 possesses immunogenicity in stimulating rabbits to produce high level of specific antibody and has protective role as a candidate vaccine antigen against S. japonicum infection.

Animals↗
PubMed1998

[Researches on the nucleotide sequencing of the recombinant Sj 22.6 kDa antigen gene of Schistosoma japonicum].

AIM: To sequence the cloned gene in pGSj24 and to identify the encoded protein. METHODS: The cloned gene in pGSj24 was digested from the recombinant plasmid by EcoRI, ligated into the M13mp19 vector and sequenced by automatic sequencer. The sequence was analyzed by Goldkey DNA and Protein Analytical Program and DNASIS Program. RESULTS: The pGSj24 cloned gene was demonstrated to be 840 bp containing one opened reading frame (ORF) with an initiation codon ATG at position 23 nt and a termination codon TAA at position 596 nt, encoding a protein with a molecular weight of 22.6 kDa. At the upstream and downstream of the ORF there were termination codons, so the encoded protein was unable to be larger. However, there was a termination codon TAA at position 11 nt, suggesting why the 22.6 kDa protein expressed separately. The nucleotide sequence of the pGSj24 cloned gene shared 95% identity with that of the corresponding part of S. japonicum 22.6 kDa antigen gene, and 99.7% identity in the encoding part. The deduced amino acid sequence analysis showed a sequence motif known as EF-Hand calcium binding domain, several endoplasmic reticulum targeting sequences and microbodies C-terminal targeting signals. The possible antigen determinants were predicted within the amino acid fragments of 29-32aa, 63-68aa and 87-101aa. CONCLUSIONS: The cloned gene in pGSj24 is the gene that encodes Sj22.6 kDa antigen.

Amino Acid Sequence↗
PubMed1998

[Screening and characterization of Schistosoma japonicum reinfection-related cDNA clones].

AIM: To obtain cDNA clones coding for S. japonicum (Sj) reinfection-related specific immunologic molecules for vaccination or diagnosis. METHODS: An adult S. japonicum cDNA library, of which the cloning efficiency is 3.13 x 10(6), with directional inserts in the vector lambda gt11, was screened with pooled serum from 43 reinfected human cases in a schistosomiasis-endemic area with high level of Sj specific-lgG4 antibodies. Primers located several bases away from the insert position on the lambda gt11 arm were used to amplify the insert fragments by standard PCR. SILVER SEQUENCE (PCR-silver) DNA sequencing system was then used to sequence selected positive clones with relatively large inserts and homology comparison with GenBank database was also carried out. RESULTS AND CONCLUSION: Eleven phage plaques were defined as positive out of the 8.6 x 10(4) phage plaques immunoscreened by human specific lgG4 antibody. GenBank database retrieval showed that 4 new Sj gene clones including Sj reinfection-related specific protein-encoding gene and Sj mitochondrial protein-coding gene have been obtained.

Adolescent↗
PubMed1997

Phosphorylation can modulate the association of different sets of RNA binding proteins with the Vg1 localization signal RNA.

As assayed by both in vivo and in vitro UV-crosslinking techniques, four RNA binding proteins, with apparent molecular weight of 56, 54, 42, and 40 kilodaltons, associated specifically with the Xenopus Vg1 mRNA localization signal (LS) RNA. The 56 and 54 kD proteins were assigned as the masking proteins described previously, on the basis of their thermal stability and the effect of phosphorylation on RNA binding activity. The 42 and 40 kD proteins associated with the LS RNA at a lower extract concentration than the masking proteins did in vitro. Dephosphorylation will eliminate the RNA binding activities of all four proteins. However, either raising the extract concentration or phosphorylating the extract by the catalytic domain of protein kinase A had opposite effects on the crosslinking efficiencies of these two sets of RNA binding proteins. Phosphorylation might regulate this protein exchange process in vitro.

Animals↗
PubMed1997

A 120 kilobase resolution contig map of the rice genome.

92% of the rice genome (4.3 x 10(8) bp, 2n = 24) was covered by 631 contigs of various length, which were generated by fingerprinting from a representative and genetically stable bacterial artificial chromosome (BAC) library of the Guang Lu Ai 4 (a O. Sativa variety) genome with the average insert of 120 kb in length. To form the contig map, 565 molecular markers of RFLP, STS, cDNA and anchor set derived from two O. Sativa varieties were by colony hybridization mapped to the contigs, which were then assigned to and ordered along the particular chromosomes according to the marker colinearity. Being highly conserved DNA sequences shared among the genomes of rice, barley, wheat, oat, maize, sorghum and sugar cane, 89 anchor markers mapped help to identify the rice genes through the information provided by the maps of relative genomes, and vice versa. Numerous repeated DNA sequences of various length were identified and mapped to the chromosomes. Physical distances have been determined for hundreds pairs of adjacent markers, which would facilitate the identification by map-based cloning the rice genes of interest. The accuracy of clone overlaps in contigs was further confirmed by the existence in contigs of well fit stacks of marker-lodged clones independently identified by hybridization. Large scale DNA sequencing of individual chromosomes could now be initiated simply by selecting and sequencing the minimally overlapped BAC clones of the contigs.

Alkyl and Aryl Transferases↗
PubMed1997

Isotypic antibody responses of a population in an endemic area of schistosomiasis japonica and their epidemiologic significance.

The present study was designed to explore if there exists a correlation between predominant isotype-defined antibody levels and reinfection in low age groups of the population in an endemic area of schistosomiasis japonica in China. One hundred and thirty-eight individuals aged 3-25 years old were selected for serological investigations including the levels of IgG, IgG4, IgM and IgE, detected by ELISA with soluble egg antigen and soluble adult worm antigen. Results show that age is a determinant for SEA-specific IgG, IgG4, and IgE, and SWA-specific IgG and IgG4 antibody levels, which increased with age, and that SEA- and SWA- specific IgG4 antibody levels are risk factors of reinfection, ie, the risk of reinfection occurrence of the population with high level of SEA or SWA-specific IgG4 is 2.83 or 2.40 times, respectively, that with low level of SEA or SWA-specific IgG4, suggesting that in the endemic area of schistosomiasis japonica, there exists a possibility that in the population aged 3-25 years, SEA and SWA-specific IgG4 antibodies mediate a blocking immunity response.

Adolescent↗
PubMed1996

Purification and characterization of linoleate 8-dioxygenase from the fungus Gaeumannomyces graminis as a novel hemoprotein.

The fungus Gaeumannomyces graminis, which causes the major root disease of wheat known as "take-all," can metabolize linoleic acid to (8R)-hydroperoxylinoleic acid. The enzyme linoleate 8-dioxygenase abstracts hydrogen and introduces molecular oxygen in an antarafacial way at C-8. We have now purified the enzyme 1000-fold to a specific activity of 1.8 micronol/min/mg of protein. Acetone powder of mycelia of G. graminis was subjected to extraction and ammonium sulfate precipitation with solubilization. The 8-dioxygenase was purified by hydrophobic interaction chromatography, size-exclusion chromatography, anion-exchange chromatography, and immobilized metal ion affinity chromatography. The active enzyme appeared to consist of four subunits since the active enzyme had an apparent molecular mass of 520 kDa determined by gel filtration, while SDS-polyacrylamide gel electrophoresis showed a protein band of 130 kDa. Spectroscopy indicated the presence of heme. The characteristic pyridine ferrohemochrome alpha-band was found at 557 nm and the beta-band at 525 nm. The purified protein showed an absorption maximum at 408 nm (gamma, Soret). The absorption maximum shifted to 429 nm after reduction with dithionite and to 421 nm after treatment of the reduced enzyme with carbon monoxide. BW A4C, a hydroxamic acid derivative, inhibited the enzyme by >90% at 10 microM. The pH optimum was 7.2-7.4, the isoelectric point was 5.2 by chromatofocusing, and the Km values were 8 microM for linoleic acid and 30 microM for oxygen. We conclude that linoleate 8-dioxygenase appears to be a tetrameric hemoprotein distinct from other fatty-acid dioxygenases.

Chromatography, Affinity↗
PubMed1996

[Invasion of fibrosarcoma cells transfected with PAI-2 gene].

The effect of PAI-2 on the invasion of fibrosarcoma cells in vitro and in vivo was investigated. The control cells (C+, C+ pem) and PAI-2 transfectants (C+ exp) were used in the assay of the degradation of isotopically labelld 3H-ECM and were injected sc into athymic/nude mice. Recombinant PAI-2 could inhibit efficiently the degradation of 3H-ECM by tumor cells (86.5%). The PAI-2 transfectants remained tumorigenic in nude mice, but tumors originating from the PAI-2 transfectants showed histologically the presence of a thick capsule which was absent in tumors from control cells.

Animals↗
PubMed1996

[Spasmolytic effects of crebanine on isolated gallbladder and Oddi's sphincter in vitro].

The study has shown that the contraction induced by histamine, Ca2+ and K+ in the biliary system of guinea-pigs is antagonized by crebanine in vitro. The antagonism presents a depression of the maximal response of the dose-response curve for the agonists in a non-competitive manner. Crebanine blocks the release of calcium from intracellular storage on isolated gall-bladder. The spontaneous activity of the oddi's sphincter in vitro is inhibited by crebanine. The initial phasic and the ionic contraction induced by K+ (40 mmol/L) in the isolated oddi's sphincters of guinea-pigs are inhibited by crebanine.

Animals↗
PubMed1995

Escherichia coli O157:H7 infection in humans.

OBJECTIVE: To review the clinical relevance of Escherichia coli O157:H7 infection, including the epidemiology of the infection and its clinical presentations, pathogenesis, microbiology, diagnosis, treatment, and prevention. DATA SOURCES: Articles on E. coli O157:H7 were identified through MEDLINE and the bibliographies of relevant articles. STUDY SELECTION: All articles and case reports describing E. coli O157:H7 and its infection were selected. DATA EXTRACTION: The data were abstracted without judgments about study design. Data quality and validity were assessed by independent author reviews. DATA SYNTHESIS: Infection with E. coli O157:H7 presents with a wide spectrum of clinical manifestations, including asymptomatic carriage, nonbloody diarrhea, hemorrhagic colitis, the hemolytic-uremic syndrome, and thrombotic thrombocytopenic purpura. Not only is E. coli O157:H7 an important agent for hemorrhagic colitis, it is also one of the leading causes of bacterial diarrhea. Patients at extremes of age have an increased risk for infection and associated complications. Transmission of E. coli O157:H7 is primarily food-borne. Undercooked meat is the most common culprit, and secondary person-to-person spread is also important. The organism produces at least two Shiga-like toxins that differ antigenically, physicochemically, immunologically, and in their biological effects. These toxins are thought to have direct pathogenic significance in E. coli O157:H7 infection. This infection is usually diagnosed from a positive stool culture, from the presence of Shiga-like toxins, or both. Timely collection (within 7 days of illness onset) of a stool sample for culture is imperative for a high recovery rate. Treatment is primarily supportive and includes the management of complications as necessary. Antibiotic therapy has not been proved beneficial. Important public health measures include educating the public on the danger of eating undercooked meat, increasing physician awareness of E. coli O157:H7 infection, and mandating case reporting. CONCLUSIONS: Infection with E. coli O157:H7 presents with many clinical manifestations and should be included in the differential diagnosis for any patient with new-onset bloody diarrhea. Development of the hemolytic-uremic syndrome or thrombotic thrombocytopenic purpura should raise strong suspicion of E. coli O157:H7 infection and should lead to prompt evaluation. If infection is confirmed, it should be reported to public health officials.

Escherichia coli↗
PubMed1995

Human IL-12 p40 homodimer binds to the IL-12 receptor but does not mediate biologic activity.

IL-12, a heterodimeric cytokine, consists of two disulfide-linked subunits, p40 and p35. We investigated the role of p40 in ligand binding and signal transduction by expressing this subunit alone in COS cells. Culture media of the transfected COS cells exhibited specific dose-dependent binding to KIT225/K6 cells, a human T cell line that expresses IL-12R. Analysis of the culture media by SDS-PAGE and Western blotting demonstrated the presence of 40-kDa monomers and 80-kDa disulfide-linked homodimers. The two p40 species were purified and identified by N-terminal sequencing and proteolytic peptide mapping. Characterization of the p40 proteins for binding and bioactivity showed that both the p40 monomer and dimer inhibited 125I-labeled IL-12 binding to IL-12R, but the 80-kDa species, having a 50% inhibitory concentration (IC50) of 20 to 70 ng/ml, was at least 20-fold more effective than the monomer. Although neither the monomer nor the dimer stimulated human PHA-blast proliferation, the 80-kDa dimer inhibited IL-12-induced proliferation in a dose-dependent manner with an IC50 of 65 ng/ml. The results suggest that the IL-12 p40 subunit contains the essential epitopes for receptor binding. However, a proper conformation required for high affinity binding is achieved only when p40 is associated with a p35 subunit or another p40 subunit. When p40 is associated with a p35 subunit, the heterodimer acts as an agonist mediating biologic activity. However, when p40 associates with another p40, the homodimer behaves as an antagonist in vitro.

Animals↗
PubMed1995

Studies on linoleic acid 8R-dioxygenase and hydroperoxide isomerase of the fungus Gaeumannomyces graminis.

Linoleic acid is sequentially converted to 7S,8S-dihydroxy-9Z,12Z-octadecadienoic acid by the 8R-dioxygenase and hydroperoxide isomerase of the fungus Gaeumannomyces graminis, which is a common pathogen of wheat. The objective of this study was to separate and characterize the two enzyme activities. The isomerase activity was found mainly in the microsomal fraction of the mycelia and the 8R-dioxygenase in the cytosol. The 8R-dioxygenase could be partially purified by ammonium sulfate precipitation, gel filtration, ion exchange chromatography or isoelectric focusing. The 8R-dioxygenase was unstable during purification, but it could be stabilized by glutathione, glutathione peroxidase and ethylenediaminetetraacetic acid. Several protease inhibitors reduced the enzyme activity. Gel filtration with Sephacryl S-300 showed that most 8R-dioxygenase activity was eluted with the front with little retention. Isoelectric focusing in the presence of ethylene glycol (20%) indicated an isoelectric point of pl 6.1-6.3. The enzyme was retained on strong anion exchange columns at pH 7.4 and could be eluted with 0.3-0.5 M NaCl. Incubation of the enzyme with 0.1 mM linoleic acid led to partial inactivation, which may indicate product inhibition. Paracetamol and the lipoxygenase inhibitor ICI 230,487 at 30 microM inhibited the 8R-dioxygenase by 44 and 58%, respectively. 8R-hydroperoxy-9Z,12Z-octadecadienoic acid was isolated from incubations of linoleic acid with the partially purified enzyme or with the cytosol in the presence of p-hydroxymercuribenzoate. The hydroperoxide was rapidly converted by the hydroperoxide isomerase in the microsomal fractions to 7S,8S-dihydroxy-9Z,12Z-octadecadienoic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗