Biomedical subjects

J Yan

Publications and source records attributed to J Yan.

At least 91 records · Page 5Linked to original sources

PubMed2001

Immune response to a 26-kDa protein, alkyl hydroperoxide reductase, in Helicobacter pylori-infected Mongolian gerbil model.

BACKGROUND: The host immune response is thought to play an important role in the outcome of Helicobacter pylori infection. The successful development of the H. pylori-infected Mongolian gerbil model that mimics human disease has enabled study of the antibody response against H. pylori antigens. MATERIALS AND METHODS: Serum samples from ulcer and carcinogenesis models of H. pylori-infected gerbils were used to screen for H. pylori antigens that cause a humoral immune response in the infected hosts. H. pylori alkyl hydroperoxide reductase (AhpC) is one such antigen on which we report here. The tsaA gene encoding AhpC was amplified by PCR from H. pylori ATCC 43504 strain, cloned into pMAL(TM)-c2 expression vector and expressed in Escherichia coli. Maltose-binding protein fusion protein (MBP-AhpC) was purified by a MBP affinity column. Using purified recombinant AhpC protein as an antigen, the antibody response and changes of antibody levels against AhpC in the gerbil models were studied by Western blotting and ELISA. RESULTS: Antibody against AhpC was negative in the early stages of infection, and became positive in the gerbils with the emergence of gastric diseases such as chronic active gastritis, gastric ulcer and gastric cancer. The antibody levels (ELISA) increased gradually over time and were higher in gerbils with gastric ulcer than that in gerbils without ulcers. CONCLUSIONS: Use of the gerbil model that mimics human H. pylori infection is likely to provide insights into the role of H. pylori-specific antigens possibly related to the subsequent development of gastric diseases.

Animals↗

PubMed2001

Role of matrix metalloproteinases in colorectal carcinogenesis.

OBJECTIVE: To measure coexpression of matrix metalloproteinase (MMP)-2, MMP-7, and MMP-9 genes by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) in benign and malignant phases of colorectal carcinogenesis. SUMMARY BACKGROUND DATA: Matrix metalloproteinases degrade and remodel the extracellular matrix and have been implicated in facilitating carcinoma cells to invade and metastasize. MMP-2, MMP-7, and MMP-9 have been shown to be overexpressed in various carcinomas; however, simultaneous examination of these enzymes in human normal mucosa, adenoma, and carcinoma has not been performed to date. METHODS: Between January 1, 1998, and June 15, 2000, 40 patients underwent colectomy and harvest and snap-freezing of normal mucosa, adenoma, and carcinoma. Five patients had adenoma and carcinoma in the same specimen; 35 had either adenoma (n = 6) or carcinoma (n = 29). Taqman qRT-PCR methodology was used to measure MMP gene copy number and normalized to beta-actin RNA expression. RESULTS: The mean age was 62 +/- 4 years, with 22 men and 18 women. One fifth of the adenomas exhibited severe dysplasia. MMP-7 gene expression was significantly increased in adenomas (43 times normal mucosa) but did not increase further in carcinomas (50 times normal mucosa). MMP-2 and MMP-9 were not different in adenomas (1.8 and 1.4 times normal mucosa, respectively) but were elevated in carcinomas (2.2 and 1.8 times normal mucosa, respectively). There was no correlation between size or dysplasia in adenomas or AJCC stage in carcinomas and MMP gene expression. CONCLUSIONS: Overexpression of MMP-7 is an early event in the adenoma-to-carcinoma pathway, and expression does not appear to increase further in carcinomas. MMP-2 and MMP-9 appear to be primarily overexpressed in carcinomas. This may be one mechanism by which adenoma cells gain the ability to invade and carcinoma cells to metastasize.

Adenoma↗

PubMed2001

Serum immunoglobulin G immune response to Helicobacter pylori antigens in Mongolian gerbils.

The Mongolian gerbil model for Helicobacter pylori infection is an animal model that mimics human disease. We examined the serum immune response to H. pylori infection in gerbils by enzyme-linked immunosorbent assay (ELISA) and Western blotting, both with whole-cell (H. pylori) extracts. A total of 66 7-week-old specific-pathogen-free male gerbils were inoculated orogastrically with H. pylori strain ATCC 43504. Sera were collected 1, 2, 4, 8, 12, 26, 38, and 52 weeks after H. pylori inoculation. Sixty-nine noninfected gerbils and their sera were used as controls. The specificity of the ELISA was 95.7%. The frequency of seropositivity increased over time: 2 of 10 (20%), 7 of 10 (70%), and 7 of 7 (100%) samples of sera from inoculated gerbils were positive for H. pylori at 2, 4, and 8 weeks postinoculation, respectively. Western blot assays showed that the primary immunoglobulin G (IgG) response against low-molecular-mass (25-, 30-, and 20-kDa) proteins appeared after a lag period of 2 to 8 weeks after inoculation. Antibodies against 160-, 150-, 110-, 120-, 80-, 66-, and 63-kDa proteins were observed 12 weeks after inoculation. The early reactive 30-kDa protein was identified as a urease alpha subunit by N-terminal amino acid sequencing. After 26 weeks, two groups of animals could be distinguished: one group developed ulcers (n = 5), and the other developed hyperplastic polyps without ulcers (n = 19). Gerbils in the gastric ulcer group showed significantly higher serum anti-H. pylori IgG levels than did gerbils in the hyperplastic group (P = 0.001) as measured by ELISA. Furthermore, a higher proportion of animals developed antibodies to H. pylori proteins of 26, 25, and 20 kDa in the ulcer group than those animals with hyperplastic polyps (75 to 100% versus 17 to 50%) in Western blot assays. These results highlight the importance of the immune response of the host in the development of H. pylori-related gastric lesions.

Animals↗

PubMed2001

Immunohistochemical demonstration of alpha1,4-N-acetylglucosaminyltransferase that forms GlcNAcalpha1,4Galbeta residues in human gastrointestinal mucosa.

alpha1,4-N-acetylglucosaminyltransferase (alpha4GnT) is a glycosyltransferase that mediates transfer of GlcNAc to betaGal residues with alpha1,4-linkage, forming GlcNAcalpha1--> 4Galbeta-->R structures. In normal human tissues, glycoproteins having GlcNAcalpha1-->4Galbeta-->R structures at non-reducing terminals are exclusively limited to the mucins secreted from glandular mucous cells of gastric mucosa, Brunner's gland of duodenum, and accessory gland of pancreaticobiliary tract. Recently, we have isolated a cDNA encoding human alpha4GnT by expression cloning. Although alpha4GnT plays a key role in producing this unique glycan in vitro, the actual localization of alpha4GnT was not determined. In this study we examined the localization of alpha4GnT in various human tissues, including gastrointestinal mucosa, using a newly developed antibody against human alpha4GnT. The specificity of the antibody was confirmed by analyses of human gastric adenocarcinoma AGS cells transfected by alpha4GnT cDNA. Expression of alpha4GnT was largely associated with the Golgi region of mucous cells that produce the mucous glycoproteins having GlcNAcalpha1-->4Galbeta-->R, such as the glandular mucous cells of stomach and Brunner's gland. An immunoprecipitation experiment disclosed that two distinct mucin proteins, MUC5AC and MUC6 present in gastric mucin, carried the GlcNAcalpha1-->4Galbeta-->R structures. These results indicate that alpha4GnT is critical to form the mucous glycoproteins having GlcNAcalpha1-->4Galbeta-->R on MUC6 and MUC5AC in vivo.(J Histochem Cytochem 49:587-596, 2001)

Animals↗

PubMed2001

Lupus autoantigens: their origins, forms, and presentation.

The immune system has developed a number of mechanisms by which to distinguish self from foreign proteins. These mechanisms are found throughout the ontogeny of B and T cell development and include the deletion of autoreactive cells in central lymphoid organs and the induction of self-tolerance in the periphery. However, any failure of these mechanisms for self-tolerance may result in autoimmune disease. Efforts in our laboratory have been directed at understanding how autoimmunity is initiated and maintained in both the B and T cell compartment, with particular interest in the autoimmunity of systemic lupus erythematosus (SLE). This review will focus on our studies on the forms of self-antigens that may be involved in the original "antigenic sin" of SLE and in the role of B lymphocytes as autoantigen presenting cells. We will also discuss whether costimulation is a formal requirement for the induction and maintenance of autoimmunity. Finally, we have provided a model for how all of these individual elements may contribute to the autoimmune processes leading to pathology.

Animals↗

PubMed2001

High frequencies of HGV and TTV infections in blood donors in Hangzhou.

AIM: To determine the frequencies of HGV and TTV infections in blood donors in Hangzhou. METHODS: RT-nested PCR for HGV RNA detection and semi-nested PCR for TTV DNA detection in the sera from 203 blood donors, and nucleotide sequence analysis were performed. RESULTS: Thirty-two (15.8%) and 30 (14.8%) of the 203 serum samples were positive for HGV RNA and TTV DNA, respectively. And 5 (2.5%) of the 203 serum samples were detectable for both HGV RNA and TTV DNA. Homology of the nucleotide sequences of HGV RT-nested PCR products and TTV semi-nested PCR products from 3 serum samples compared with the reported HGV and TTV sequences was 89.36%, 87.94%, 88.65% and 63.51%, 65.77% and 67.12%, respectively. CONCLUSION: The infection rates of HGV and/or TTV in blood donors are relatively high, and to establish HGV and TTV examinations to screen blood donors is needed for transfusion security. The genomic heterogeneity of TTV or HGV is present in the isolates from different areas.

Base Sequence↗

PubMed2001

[Effects of comprehensive intervention on prognosis of isolated systolic hypertension in the elderly].

OBJECTIVE: To study the effects of comprehensive intervention on prognosis of isolated systolic hypertension in the elderly. METHODS: A 12-years prospective and controlled study was conducted with 207 elderly patients of isolated systolic hypertension enrolled. According to the study project and procedure, 99 patients were allocated to the intervention group and 108 patients in the control group. All the events of cardiovascular diseases, cerebrovascular disorders, nephrovascular diseases and death were recorded and analyzed. RESULTS: A 12-year consecutive follow-up showed that the incidence and mortality of cardiovascular diseases, cerebrovascular disorders, nephrovascular diseases and their ages at death were 41.49%, 26.60% and 75.6 years, respectively, in the intervention group, and 77.45%, 53.92% and 70.2 years, respectively, in the control group, with statistically significant difference. Survival rate in the intervention group was higher than that in the control group. CONCLUSION: Comprehensive intervention for a long time could remarkably improve their clinical prognosis of the elderly patients with isolated systolic hypertension.

Aged↗

PubMed2001

[Experimental and mechanism analyses on HCl emission control during PVC combustion in fixed beds].

Incineration of chloridated plastic (PVC) in solid wastes contributes much to HCl pollutant in air environment. The characteristics of HCl emissions and reduction during PVC combustion were conducted in a nearly isothermal, externally heated, horizontal quartz-tube reactor. With increasing temperature from 700 to 900 degrees C, the conversion of HCl increased leniently from 82.5% to 88.3%. High excess air factor enhanced a small amount of HCl existing in form of Cl2. The calcium-based sorbents including CaCO3, Ca(OH)2, Ca(CH3COO)2 exhibited high HCl capture efficiencies from 68% to 79%, while magnesium-based sorbent less than that of 3%. Influences of operational variables, i.e., size of sorbent, Ca/Cl molar ratio and combustion fume compositions, on the HCl reduction were discussed. From a point of view of equilibrium constant of dechloridization reaction the experimental results were explained in detail.

Hot Temperature↗

PubMed2001

High homologous nucleotide to GBV-C was amplified from DNA of MT2 and HeLa cells and PBMC of human and chimpanzee.

AIM: To determine whether the nucleotide sequences homologous to GBV-C genome exist in the DNA from cell lines of human origin and from peripheral blood mononuclear cells (PBMC) of human and chimpanzee. METHODS: DNA of MT2 cell, HeLa cell, and PBMC from six human and one chimpanzee were prepared by using PCR Temperate Preparation Kit. All of the DNA preparations were digested with DNase-free RN ase and then were extracted by phenol-chloroform method. By using these DNA as templates, direct nested-PCR (dPCR) respectively amplified with GBV-C 5'-NCR and NS3 primers were carried out. Nucleotide sequences of the dPCR products were analyzed and positions in chromosomes of the amplification fragments were detected by using primed in situ (PRINS) sequence-specific labeling with fluorescein. RESULTS: DNA fragments amplified with GBV-C 5'-NCR primers were obtained from the DNA of MT2 and HeLa cells and the DNA in 4 of 6 human PBMC samples. DNA fragments amplified with GBV-C NS3 primers were obtained from MT2 and HeLa cells and the DNA in 5 of 6 human PBMC samples and one chimpanzee PBMC sample. The homology of the nucleotide sequences from these amplification products compared with the reported GBV-C genome sequence was from 73.80 % to 79.15 %. Fluorescence staining spots by using PRINS were shown in the PBMC and their chromosomes with positive dPCR results. CONCLUSION: The nucleotide sequences with high homology to GBV-C genome at the 5'-NCR and/or NS3 region exist in the DNA of MT2 and HeLa cells and the PBMC DNA of human and chimpanzee. These sequences locate in the chromosomes of PBMC with positive dPCR results.

Animals↗

PubMed2001

Porphyromonas gingivalis lipopolysaccharide activated bone resorption of osteoclasts by inducing IL-1, TNF, and PGE.

AIM: To study the effects of Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) on inducing interleukin-1 (IL-1), tumor necrosis factor (TNF), prostaglandin E (PGE), and activating osteoclasts, in order to understand mechanism of osteoclast activation. METHODS: Pg-LPS was prepared by phenol-water method. IL-1, TNF, and PGE induced by Pg-LPS were isolated by chromatography. Ca2+ concentration was detected by atomic absorption spectrophotometry. Acid phosphatase and carbonic anhydrase in periodontal membranes were examined by histochemistry. RESULTS: Pg-LPS was able to stimulate peripheral blood mononuclear cells (PBMC) or the cells from human periodontal tissue secreting IL-1, TNF, and PGE. The outputs of these cytokines were increased in pace with the enhancement of Pg-LPS at the dose range of 0.5 - 5.0 mg/L. All of the three cytokines showed activities of accelerating Ca2+ release from rat calvarial bones, and the activity of PGE was the strongest. The amounts of both the acid phosphatase and carbonic anhydrase in the periodontal membranes of Pg-LPS injected rats were obviously increased (P < 0.01). In the periodontal membranes of Pg-LPS injected rats, the amount of activated osteoclasts were obviously increased in pace with Pg-LPS injection times (P < 0.01). However, the activating rates of osteoclasts were stable to approximately 65 % because of the increase of inactivated osteoclasts. CONCLUSION: Pg-LPS possessed strong activities to induce human PBMC and the cells from human periodontal tissue to produce IL-1, TNF, and PGE in a dose-dependent m anner within a certain concentration range of the LPS. Pg-LPS could efficiently activate osteoclasts, and the mechanism of osteoclast activation was probably associated with the increase of acid phosphatase and carbonic anhydrase.

Alprostadil↗

PubMed2001

[Characteristics of litter and its contained water in three succession communities in Dinghushan Mountain].

Studies on the characteristics of litter and its contained water in three succession communities in Dinghushan Mountain showed that the standing mass of litter was in the order of pine forest > mixed forest > broad-leaved forest, and the annual litterfall was broad-leaved forest > mixed forest > pine forest, indicating that the return rate of nutrients was lower in pine forest than in broad-leaved forest. The proportion of leaf litter decreased in the order of pine forest > mixed forest > broad-leaved forest, and that of branch, flower, and fruit litter was on the contrary, because the broad-leaved forest had the largest amount of branches and the biggest scope of canopy. The staturation water content of litter in pine forest, mixed forest and broad-leaved forest was 329.0%, 313.0% and 295.0%, respectively, showing no significant difference, but the water content of litter in three communities differed significantly, followed the order of broad-leaved forest > mixed forest > pine forest. The evaporation ratio of litter water to free water in broad-leaved forest, mixed forest and pine forest was 78.9%, 82.45% and 91.22%, respectively.

Biodegradation, Environmental↗

PubMed2001

Novel chromosomal alterations detected in primary nasopharyngeal carcinoma by comparative genomic hybridization.

OBJECTIVE: To gain a better understanding of genetic changes in Cantonese nasopharyngeal carcinoma (NPC). METHODS: Comparative genomic hybridization (CGH) was performed on 17 primary nasopharyngeal carcinomas. RESULTS: A novel copy number gain an chromosome 4q and loss of chromosome 1p were found at a high frequency (> 50%). CONCLUSIONS: Current analysis revealed a comprehensive profile of the chromosomal regions showing gain of chromosomes 4q, 12q, and 1q as well as loss of chromosomes 1p, 3p, 11q, 14q, 15q, 13q, Xq, 9q, 10p, 10q, and 16q. Frequently altered loci may encode oncogenes or tumor suppressor genes involved in the development of primary NPC.

Chromosome Aberrations↗

PubMed2001

[Frequent chromosomal gain of 4q and loss of 1p in primary nasopharyngeal carcinoma].

OBJECTIVE: To reveal the genetic changes of nasopharyngeal carcinoma (NPC) in Cantonese. METHODS: Comparative genomic hybridization (CGH) was performed on 17 primary NPC biopsy specimens to find out any gain or loss of genetic material. RESULTS: A novel copy number gain on chromosome 4q and loss of chromosome 1p were found at high frequency (> 50%). The other more common genetic alterations included gain of chromosomes 4q, 12q, and 1q as well as loss of chromosomes 1p, 3p, 11q, 14q, 15q, 13q, Xq, 9q, 10p, 10q, and 16q. CONCLUSION: Current analysis has revealed a comprehensive profile of the chromosomal changes in NPC. Frequently altered loci may encode oncogenes or tumor suppressor genes involved in the development of primary NPC.

Asian People↗

PubMed2001

[The survey of HIV prevalence among children between 0 to 7 years old in one county in China].

OBJECTIVE: To estimate the HIV prevalence among children between 0 to 7 years old in one county with HIV epidemic. METHODS: In September 2000, finger tip blood samples were collected from 619 children between 0 to 7 years old in three districts of one county with high HIV prevalence and tested for HIV antibody and HBV antigen. RESULTS: Among those 619 children, 11 were found HIV positive, with the prevalence of 1.8% (11/169). The HIV prevalence of three districts were 5.9% (10/169), 0.5% (1/206), and 0% (0/244), respectively. The possible channel associated with the HIV infection was mother-to-child transmission since none of the infected children had the history of blood transfusion. Twenty-four tested children were found HBV positive and the prevalence was 4.3 (24/619). CONCLUSION: There was higher HIV prevalence in children between 0 to 7 years old in certain areas. More intervenes are needed in the future to prevent the HIV spreading through mother-to-child transmission.

Child↗

PubMed2001

[Fine mapping of the loss of heterozygosity for chromosome 1pter-p36.11 in nasopharyngeal carcinoma].

OBJECTIVE: To construct a detailed mapping of the Chromosome 1pter-p36.11 deleted region (63.4 cM) in nasopharyngeal carcinoma (NPC) by polymerase chain reaction-loss of heterozygosity (PCR-LOH) analysis for the further research of NPC-related gene(s). METHODS: Biopsies from 47 cases of NPC patients were studied. DNA extracted from separated cancer cells and their corresponding non-cancer lymphocytes were amplified with PCR, followed by the analysis of LOH and microsatellite instability (MI) for 20 loci spanning Chromosome 1pter-p36.11 region with an average interval of 3.0 cM. RESULTS: 82.2% of NPC cases (37/47) showed at least one loci of LOH. The highest frequency of LOH was found at loci D1S234 on 1p36.13 (50.0%), with the LOH at loci D1S2644 on 1p36.22 slightly less (37.5%). The occurrence of LOH at D1S234 showed no significant difference for the cases at early stage and at advanced stage [60% (9/15) vs 50.0% (8/16) respectively, P > 0.05]. High frequencies of MI were detected at D1S243 on 1p36.33 (37.5%) and D1S199 on 1p36.21 (30.2%). CONCLUSIONS: There are two common deletion regions: one localized at 1p36.13 (D1S234, 2.0 cM) and the other at 1p36.22 (D1S436-D1S2644, 6.3 cM), with a MI loci at D1S199 between them. This suggests that one or more putative tumor suppressor gene(s) related to the early stage of NPC tumorigenesis may be encompassed in this zone.

Adult↗

PubMed2001

The affects of acupuncture at sibai and neiting acupoints on gastric peristalsis.

The frequency and amplitude of gastric peristaltic wave were significantly changed in 15 subjects when Sibai (ST 2) and Neiting (ST 44) acupoints of the Stomach Channel of Foot-Yangming were punctured. The results demonstrate that these acupoints are effective for treatment of stomach diseases, providing an experimental basis for the theory of channels and collaterals.

Acupuncture Points↗

PubMed2001

Identification of rice black streaked dwarf virus in different cereal crops with dwarfing symptoms in China.

This report describes isolation of virus particles from plants of rice, maize, wheat and sorghum with symptoms of dwarfing collected from two provinces of China, purification of double-stranded RNA (dsRNA) from the virus particles, and synthesis of full-length cDNAs of genome segments 9 (S9) and 10 (S10) by reverse transcription-polymerase chain reaction (RT-PCR). Sequence analysis showed that the S9 sequences of the Chinese isolates and a Japanese rice black-streaked disease virus (RBSDV) isolate were very similar (89.1-89.6% homology at nucleotide level and 92.3-92.9% and 95.8-98.6% homology at amino acid level for ORF1 and ORF2, respectively). Analogical similarity was found also for the S10 sequences of the isolates under comparison: 93.0-95.4% homology at nucleotide level and 96.2-97.0% homology at amino acid level. However, there was a relatively lower similarity for S9 and S10 segments ofthe Chinese isolates and an Italian maize rough dwarf virus (MRDV) isolate. The phylogenetic analysis indicated that the Chinese isolates that infect rice, maize, wheat and sorghum and cause similar symptoms could represent the same virus species, RBSDV.

Amino Acid Sequence↗

PubMed2001

[Study on FM100-HUE color vision in male workers exposed to lower concentration of carbon disulfide].

The effect of CS2 on color vision in workers exposed to CS2 was explored. The color discrimination in 191 exposed and 93 non-exposed male workers was studied by a Farnsworth Munsell 100-HUE (FM100-HUE) test. The results showed that the time weighted average (TWA) concentration of CS2, determined by Japan GC-17A gas chromatography, was (14.75 +/- 6.89) mg/m3 in a long rayon workshop and (16.30 +/- 5.42) mg/m3 in a short rayon workshop. Higher FM100-HUE color vision score was often in the exposed group (106.9) than in the controls (78.3). The discrimination to green and blue zone was also significantly impaired (P < 0.05). It is concluded that the color vision was disturbed in workers exposed to CS2. The workers should be followed by health surveillance.

Adult↗