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Biomedical subjects

Yun Ma

Publications and source records attributed to Yun Ma.

49 records · Page 3Linked to original sources
PubMed2004

[Adsorption characteristics of three types of surfactants in soils].

Surfactants after entering soil may interact with other xenobiotics of sufactant and alter their behaviors. These interactions are very complex, and depend heavily on a range of parameters including surfactant concentration in soil-water, its CMC and adsorption characteristics of sufactant and pollutant etc. In this paper, batch sorption experiment was employed to study the adsorption characteristics of three types of surfactants, viz. an anionic, a cationic, and two nonionic surfactants, in 6 soils. The results showed that the adsorption isotherms of cetyltrimethylammonium bromide (CTMAB) were L-shape, with distribution coefficients (Kd) varied between 300 to 4800 L x kg(-1) in lower concentration range. The adsorption isotherms of sodium dodecyl benzene sulfonate C12 LABS, OP and Tween-20 were L- or S-shape, depending on surface-active molecular and soil properties. The affinity of anionic and nonionic surfactants to soil was weaker than that of cationic surfactant. The Kd for C12 LABS, Tween-20 and OP was within 5.3-39, 0.13-0.44 and 4.4-22.4 L x kg(-1), respectively. For sodium dodecyl benzene sulfonate, Kd was positively correlated with soil clay fraction, and the charge property of soil was also influential in its sorption. For OP and Tween-20, the empirical relations of Kd to soil properties, clay, silt, sand contents, and surface area, were established by using regression analysis. Cationic exchange capacity showed a strong positive correlation with the maximum adsorption capacity of soils, which might indicate that the ionic exchange mechanism played an important role in adsorption of CTMAB.

Adsorption↗
PubMed2003

Cytochrome P4502D6(193-212): a new immunodominant epitope and target of virus/self cross-reactivity in liver kidney microsomal autoantibody type 1-positive liver disease.

Cytochrome P4502D6 (CYP2D6), target of liver kidney microsomal autoantibody type 1 (LKM1), characterizes autoimmune hepatitis type 2 (AIH2) but is also found in patients with chronic hepatitis C virus (HCV) infection. To provide a complete linear epitope B cell map of CYP2D6, we tested peptides spanning the entire sequence of CYP2D6. In addition to confirming previously described antigenic sites, we identified four new epitopes (193-212, 238-257, 268-287, and 478-497). CYP2D6(193-212) is immunodominant and was the target of 12 of 13 (93%) patients with AIH2 and 5 of 10 (50%) HCV/LKM1-positive patients. Because LKM1 is present in both AIH2 and a viral infection, we tested whether Abs to CYP2D6(193-212) arise through cross-reactive immunity between virus and self. We identified a hexameric sequence "RLLDLA" sharing 5 of 6 aa with "RLLDLS" of HCV(2985-2990) and all 6 aa with CMV(130-135). Of 17 CYP2D6(193-212)-reactive sera, 11 (7 AIH and 4 HCV) reacted by ELISA with the HCV homologue, 8 (5 AIH and 3 HCV) with the CMV homologue, and 8 (5 AIH and 3 HCV) showed double reactivity. Autoantibody binding to CYP2D6(193-212) was inhibited by preincubation with HCV(2977-2996) or CMV(121-140). Recombinant HCV-nonstructural protein 5 and CMV-UL98 proteins also inhibited Ab binding to CYP2D6(193-212). Affinity-purified CYP2D6(193-212)-specific Ab inhibited the metabolic activity of CYP2D6. The demonstrated similarity and cross-reactivity between CYP2D6(193-212) and two unrelated viruses suggests that multiple exposure to viruses mimicking self may represent an important pathway to the development of autoimmunity.

Adolescent↗
PubMed2003

[Effects of yi-fu-ning soft capsule on sex hormone, NO, NOS, SOD and MDA levels in ovariectomized rat serum].

OBJECTIVE: Through investigating the changs of sex hormone, nitric oxide (NO), nitric oxide synthase (NOS), superoxide dismutase (SOD) and malonaldehyde (MDA) in the serum of ovariectomized, rats, the mechanism of cardiovascular disease occurring in post-menopause rats and the effect of Yi-Fu-Ning soft capsule (YFN) on above-menticned indexes were discussed. METHOD: Fifty female mature Sprague-Dawley rats were randomly divided into 5 groups: sham operation, ovariectomy (OVX), OVX with diethylstilbestrol tables (DT), OVX with YFN (high dose and low dose). After administrating drugs of 4 weeks, sex hormone, NO, NOS, SOD and MDA levels in rat serum were detected. RESULT: In ovariectomized rats serum, with the drop of E2 concentration, NO, NOS, SOD levels decreased, while MDA content increased. And the E2 concentration was correlated with other index levels. YFN can obviously regulate above-mentioned indexes. CONCLUSION: The cardiovascular disease occurring in post-menopause rats is possibly due to the decrease of serum sex hormone, which cause the disease through the loss of the NO and damage of the free radical. YFN can prevent and cure the cardiovascular disease by regulating above-mentioned indexes in post-menopause rats.

Animals↗
PubMed2003

[Laboratory study of the yi-fu-ning soft gelatin capsules in treating climacteric syndrome].

OBJECTIVE: To study the therapeutic mechanism of YFN on climacteric syndrome by investigating the effect of Yi-Fu-Ning soft gelatin capsules (YFN), which can nourish the kidney and activate blood, on serum sex hormone levels and hypothalamic monoamine transmitters contents in ovariectomized rats. METHOD: Fifty female mature Sprague-Dawley rats were randomly divided into 5 groups:sham operation;ovariectomy(OVX);OVX with diethylstilbestrol tablets(DT);OVX with YFN(high dose and low dose). After drugs had been given for 4 weeks, hypothalamic monoamine transmitters (NE, DA, 5-HT, 5-HIAA) contents were detected by fluorospectrophotometric method and serum sex hormone by radioimmunoassay. Adrenal gland index, uterus index and thymus index were also determined. RESULT: YFN could obviously improve serum E2 and increase adrenal gland and uterus index in OVX rats (P < 0.01 or P < 0.05). It could reduce hypothalamic 5-HT and 5-HIAA, which were increased in OVX rats(P < 0.01); It could also increase reduced NE and DA in OVX rats and reduce the ratio of 5-HT to NE and 5-HT to DA(P < 0.01). CONCLUSION: YFN can regulate procreate endocrine in various ways and ameliorate the function of hypothalamic monoamine neurotransmitter in OVX rats. So it can stabilize inner condition of body and relieve symptoms of climacteric syndrome.

Animals↗
PubMed2002

Key residues of a major cytochrome P4502D6 epitope are located on the surface of the molecule.

Eukaryotically expressed CYP2D6 is the universal target of liver kidney microsomal Ab type 1 (LKM1) in both type 2 autoimmune hepatitis (AIH) and chronic hepatitis C virus (HCV) infection. In contrast, reactivity to prokaryotically expressed CYP2D6 protein and synthetic peptides is significantly lower in HCV infection than in AIH. The aim of the present study was to characterize LKM1 reactivity against a panel of eukaryotically expressed CYP2D6 constructs in the two conditions. LKM1-positive sera obtained from 16 patients with AIH and 16 with HCV infection were used as probes to perform a complete epitope mapping of CYP2D6. Reactivity to the full-length protein and 16 constructs thereof was determined by radioligand assay. We found that antigenicity is confined to the portion of the molecule C-terminal of aa 193, no reactivity being detectable against the aa sequence 1-193. Reactivity increases stepwise toward the C-terminal in both AIH and HCV, but the frequency of reactivity in the two conditions differs significantly between aa 267-337. To further characterize this region, we introduced a five and a three amino acid swap mutation selected from the homologous regions of CYP2C9 and HCV. This maneuver resulted in a substantial loss of LKM1 binding in both conditions, suggesting that this region contains a major epitope. Molecular modeling revealed that CYP2D6(316-327) is exposed on the surface of the protein, and may represent a key target for the autoantibody. These findings provide an initial characterization of the antigenic constitution of the target of LKM1 in AIH and HCV infection.

Adolescent↗
PubMed2002

Antibodies against homologous microbial caseinolytic proteases P characterise primary biliary cirrhosis.

BACKGROUND/AIMS: Antibodies to caseinolytic protease P(177-194) (ClpP(177-194)) of the proteolytic subunit of the Clp complex of Escherichia coli (E. coli) are uniquely present in primary biliary cirrhosis (PBC). Molecular mimicry between the regulatory subunit ClpX and the principal T-cell epitope of pyruvate dehydrogenase complex (PDC-E2) in PBC, has been proposed to account for this. Since ClpP is highly conserved among bacteria we investigated whether the micro-organisms triggering these antibodies may be other than E. coli. METHODS/RESULTS: E. coli ClpP(177-194) is homologous with ClpP peptides of Yersinia enterocolitica (YEREN) and Haemophilus influenzae (HAEIN). Enzyme linked immunosorbent assay (ELISA) reactivity to these peptides was tested in 45 patients with PBC, 44 pathological and 32 healthy controls. Reactivity to at least one of the ClpP peptides was observed in 21 (47%) PBC patients, 5.8% pathological and 3.1% healthy controls (P<0.01 for all). Among these 21 seropositive PBC patients, 15 (71%) reacted to ECOLI ClpP(177-194), alone or in association with YEREN and/or HAEIN peptides, compared to three (14.2%) reactive with YEREN, two (9.5%) with YEREN/HAEIN and one (4.7%) with HAEIN peptide. Simultaneous reactivity to homologous sequences was due to cross-reactivity as confirmed by competition ELISAs. CONCLUSIONS: The PBC-specificity of anti-microbial ClpP reactivity is confirmed: the questions as to primary trigger(s) and relevance to PBC pathogenesis remain open.

Adenosine Triphosphatases↗
PubMed2002

Antibodies to conformational epitopes of soluble liver antigen define a severe form of autoimmune liver disease.

Prevalence and clinical relevance of antibodies to soluble liver antigen (tRNP((Ser)Sec)/SLA) in autoimmune hepatitis (AIH) have been investigated using partially purified or prokaryotically expressed antigen. The aim of this study was to improve the detection of anti-tRNP((Ser)Sec)/SLA by establishing an immunoassay that was able to identify antibodies directed to conformational epitopes and to investigate the clinical implication of this autoantibody in autoimmune liver disease. By using eukaryotically expressed tRNP((Ser)Sec)/SLA as target in a radioligand assay (RLA), 81 patients with autoimmune liver disease (AILD) (33 type 1 AIH, 31 type 2 AIH, and 17 autoimmune sclerosing cholantitis [ASC]), 147 pathologic, and 56 healthy controls were investigated. RLA results were compared with those obtained using a commercial enzyme-linked immunosorbent assay (ELISA) and immunoblot. Reactivity to tRNP((Ser)Sec)/SLA was present in 58% of patients with type 1 and type 2 AIH, 41% with ASC, but in only 3 pathologic controls. RLA was similarly disease-specific but remarkably more sensitive than ELISA and immunoblot. A prospective study showed that anti-tRNP((Ser)Sec)/SLA-positive patients run a severe clinical course, having worse histology, needing longer to achieve remission, relapsing and requiring liver transplantation or dying more frequently than anti-tRNP((Ser)Sec)/SLA negative patients. Anti-tRNP((Ser)Sec)/SLA production was favored by the possession of DR3 and A1-B8-DR3 in AIH type 1 and ASC, and prevented by the possession of A2 in all 3 types of AILD, particularly in type 2 AIH. In conclusion, anticonformational tRNP((Ser)Sec)/SLA reactivity is frequent in type 1 and type 2 AIH and ASC, defining patients with a worse prognosis.

Autoantibodies↗
PubMed2002

[Nucleic acid quantifying assay of hepatitis B virus].

OBJECTIVE: To explore the relation between the nucleic acid content of hepatitis B virus and hepatitis B virus markers, liver function and its pathological state. METHODS: Thirty-nine patients suffering from chronic hepatitis B with positive HBsAg were performed liver puncture for histopathological examination. Fluorescence ration PCR analysis was used for HBV DNA quantifying assessment. Hepatitis B virus markers were detected by ELISA. RESULTS: Serum HBV DNA content was related to hepatitis B virus markers. There was no correlation between HBV DNA level and the Scheuer grade in patients with positive HBsAg, and no obvious correlation between serum glutamic pyruvic transaminase level and HBV DNA content. CONCLUSIONS: There is a significant correlation between HBeAg and HBV DNA, but not between liver inflammation stage and serum HBV DNA content.

Adolescent↗
PubMed2002

CTLA-4 gene A/G polymorphism associated with diabetes mellitus in Han Chinese.

OBJECTIVE: To investigate the association of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) gene A/G polymorphism with susceptibility to diabetes mellitus in Han Chinese. METHODS: An A/G transition at position 49 of exon 1 was analyzed in 31 patients with type 1 diabetes, 31 patients with type 2 diabetes, and 36 controls were analyzed by polymerase chain reaction-restriction fragment length polymorphism analysis. RESULTS: A highly significant increase in the frequency of the G allele was seen in patients with type 1 diabetes compared with controls (66.1 % vs. 34.7%, respectively; P < 0.0005; OR = 3.670) . This reflected an increase in the GG genotype in patients (48.4% vs. 22.2%, respectively; P =0.025; OR =3.281) and a significant decrease in the AA genotype (16.1 % vs. 52.8%, respectively; P = 0.002). The allele frequencies of A and G in patients with type 2 diabetes were not significantly different from controls(A/G, 50.0/50.0% vs. 65.3/34.7%; P = not significant) . The distribution of genotype, however, differed significantly. This difference reflected an increase in the AG genotype in patients (54.8% vs.25.0%, respectively; P=0.012; OR=3.643) and a decrease in the AA genotype (22.6% vs. 52.8%, respectively; P=0.011). CONCLUSIONS: CTLA-4 49 AA is protective from diabetes mellitus, whereas, CTLA-4 49 G allele (both as homozygotes and as heterozygotes ) confers an increased risk of diabetes mellitus.

Abatacept↗
PubMed2002

[Summarization of the clinical and laboratory study on the rhubarb in treating chronic renal failure].

OBJECTIVE: To review the clinical and laboratory study on the rhubarb in the treatment of Chronic Renal Failure (CRF). METHOD: Documents of clinical and mechanism study on chinese medicine rhubarb including the simple rhubarb and the rhubarb complex prescription in which rhubarb is the main effective ingredient in recent 10 years were searched and summarized. RESULT: Clinical application involving dosage forms, prescriptions, usage and effect of the rhubarb and its prescriptions in the treatment of the CRF and their laboratory study progress wre summarized. CONCLUSION: Rhubarb and all kinds of its complex prescriptions have an assured effect on CRF and their mechanism includes many ways such as ameliorating azotemia, preventing nephritic compensatory hypertrophy and high metabolism situation, and so on. So the rhubarb can be used as an ideal medicine in treating CRF in a long period of time and will have a very brilliant prospect.

Animals↗
PubMed1998

Aflatoxin sufferer and p53 gene mutation in hepatocellular carcinoma.

AIM:To study the p53 gene mutation and its relationship to aflatoxin B1 exposure in hepatocellular carcinoma (HCC).METHODS: Restriction fragment length polymorphism analysis method was used in 62 HCC samples, and DNA direct sequencing in another 45 HCC samples.RESULTS: In HCC and AFB1 high and low-risk areas, 36/52 (69%) and 2/10 (20%) cases were found losing the HaeIII allele respectively, suggesting one of the base G mutation at the p53 gene codon 249. Similar results appeared in DNA direct sequencing, 20/35 (57%) and 1/10 (10%) respectively mutated at the codon 249 third base G to C transversion.CONCLUSION: In HCC after AFB1 exposure, mutation of p53 gene is fixed at codon 249 third base and take the form of G to T transversion. This is a definite marker of mutation which is induced by AFB1 mutagen. It is applicable for molecular epidemiologic survey of the sufferers of AFB1 among HCC cases and for discovering more unknown natural AFB1 contaminated areas.

Journal Article↗
PubMed1998

Orientated thermotherapy of ferromagnetic thermoseed in hepatic tumors.

AIM:To study the thermotherapeutic effects of implanted ferromagnetic thermoseeds in high frequency electromagnetic field in hepatic tumors.METHODS:The ferromagnetic thermoseeds made of nickel-copper alloy, which has a lower Curie temperature, were implanted into hepatic tumors of mice. The high frequency electromagnetic field was then applied in vitro to make the ferromagnetic thermoseeds produce the hyperthermia. Before and after thermotherapy, the tumor size, pathologic alteration and animal survival period were assessed.RESULTS:The temperature at the central area of the tumor could be heated up to 50°. Most of tumors in mice disappeared with a large amount of tumor necrosis. The survival period of mice was prolonged.CONCLUSION:This thermotherapy is beneficial to directional selection and temperature control for treatment of hepatic tumors.

Journal Article↗