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Biomedical subjects

J Cheng

Publications and source records attributed to J Cheng.

At least 127 records · Page 7Linked to original sources
PubMed2001

Polymorphic markers in the SRD5A2 gene and prostate cancer risk: a population-based case-control study.

It has been suggested that the activity of the steroid 5alpha-reductase type II enzyme (encoded by the SRD5A2 gene) may be associated with prostate cancer risk and that population differences in this enzyme's activity may account for part of the substantial racial/ethnic disparity in prostate cancer risk. To provide etiological clues, we evaluated the relationships of four polymorphic markers in the SRD5A2 gene, specifically, A49T (a substitution of threonine for alanine at codon 49), V89L (a substitution of leucine for valine at codon 89), R227Q (a substitution of glutamine for arginine at codon 227), and a (TA)n dinucleotide repeat, with prostate cancer risk in a population-based case-control study in China, a population with the lowest reported prostate cancer incidence rate in the world. Genotypes of these four markers were determined from genomic DNA of 191 incident cases of prostate cancer and 304 healthy controls using PCR-based assays, and serum androgen levels were measured in relation to these genotypes. All study subjects had the wild-type AA genotype of the A49T marker, and 99% had the RR genotype of the R227Q marker. For the V89L marker, prevalences of the LL, VV, and VL genotypes among controls were 35%, 21%, and 45%, respectively. Compared with men with the VV genotype, those with the LL genotype had a statistically nonsignificant 12% reduced risk (odds ratio = 0.88, 95% confidence interval, 0.53-1.47). In addition, men with the LL genotype had significantly higher serum levels of testosterone and significantly lower serum levels of 5alpha-androstane-3alpha,17beta-diol glucuronide than men with other genotypes. Men heterozygous for the (TA)0 allele of the (TA)n marker had a modest, statistically nonsignificant risk reduction (odds ratio = 0.67; 95% confidence interval, 0.39-1.12) compared with men homozygous for the (TA)0 allele, along with significantly higher serum dihydrotestosterone levels. The observed V89L genotype prevalences and the association between V89L genotypes and serum androgen levels support the hypothesis that genotypes associated with lower levels of 5alpha-reductase activity are more common in low-risk populations. Although we found no statistically significant associations of these SRD5A2 polymorphisms with prostate cancer risk, a small effect of these markers cannot be ruled out because of the rarity of certain marker genotypes. Larger studies are needed to further clarify the role of these markers and to elucidate whether genetic diversity of the SRD5A2 gene, alone or in combination with other susceptibility genes, can help explain the large racial/ethnic differences in prostate cancer risk.

Adult↗
PubMed2001

[Screening and characterization of human phage antibody to hepatitis C core antigen].

OBJECTIVE: To screen and characterize human phage antibody (ScFv) against hepatitis C core antigen. METHODS: The recombinant phages were panned by core antigen that was coated in a microtiter plate. After three rounds of biopanning, 48 clones were determined specific to core antigen. The specificity of each ScFv colone was determined by ELISA. The coding gene for HCV protein ScFv has been sequenced. RESULTS: Phage antibody for HCV core protein had a specific combination character with core antigen of hepatitis C virus. The DNA sequence data showed that the ScFv gene included 774 bp. CONCLUSIONS: Human single chain antibody to hepatitis C core antigen has been identified by means of the phage display technology.

Amino Acid Sequence↗
PubMed2001

[The language healing system of deaf children based on wavelet transform].

In the language healing system of deaf children, the wavelet transform method is employed to describe the time-varying characteristics of speech signals, improve the resolution of speech spectrum and make the speech characteristics more obvious. The speech spectrum information shown in this system is easier for deaf children to observe and understand and it is of great importance to the language healing of deaf children.

Child↗
PubMed2001

[The complexity measure and its application to EEG analysis].

In this paper are reviewed the conceptions, characteristics and application of the complexity measure in studying EEG. The reviewers expound the advantages and problems of using complexity measure in the analysis of EEG in different physiological states and deem it a new way to study and understand the human brain function.

Algorithms↗
PubMed2001

[Study on weekly low doses of mifepristone for contraception].

OBJECTIVE: To study whether weekly low dose of mifepristone (5 mg or 10 mg) is sufficient to prevent pregnancy. METHODS: Thirty-nine women were randomly allocated to take mifepristone 5 mg (group A) or 10 mg (group B) doses once weekly starting on cycle day 2-3. The serum levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were determined by enzymeimmunoassay (EIA), and estradiol (E2) and progesterone (P) levels by radioimmunassay (RIA). Serum mifepristone concentrations were measured by high performance liquid chromatography (HPLC). Morphometric analyses and progesterone receptor (PR), Dolichus biflorus agglutinin (DBA-lectin) and integrin alpha v beta 3 of endometrium were also measured. RESULTS: There were 4 pregnancies out of 64 cycles in group A, and 3 out of 68 cycles in group B. Normal LH and FSH peak could be detected in the first treatment cycles, LH peak appeared on 15-17 d. The concentrations of P were (51.93 +/- 7.91) nmol/lL and (69.00 +/- 21.29) nmol/L in group A and B respectively. The average level of E2 was (407.81 +/- 89.27) pmol/L in group A, and (557.85 +/- 204.69) pmol/L in group B. Serum mifepristone level could be detected within 36 hours. The PR concentration in endometrium decreased significantly, but not of DBA-lectin, integrin alpha v beta 3. CONCLUSIONS: Administration of mifepristone 5 mg or 10 mg once weekly does not inhibit ovulation completely. The follicular phase prolonged slightly, and E2 levels were low following treatment. The endometrium showed delayed development. The clinical contraceptive effectiveness needs to be improved.

Adult↗
PubMed2001

Modeling of organic pollutant destruction in a stirred-tank reactor by ozonation.

Destruction of organic contaminants in water by ozonation is a gas-liquid process which involves ozone mass transfer and fast irreversible chemical reactions. Ozonation reactor design and process optimizing require the modeling of the gas-liquid interactions within the reactor. In this paper a theoretical model combining the fluid dynamic and reaction kinetic parameters is proposed for predicting the destruction rates of organic pollutants in a semi-batch stirred-tank reactor by ozonation. A simple expression for the enhancement factor as our previous work has been applied to evaluate the chemical mass transfer coefficient in ozone absorption, 2,4-dichlorophenol (2,4-DCP) and 2,6-DCP or their mixture are chosen as the model compounds for simulating, and the predicted DCP concentrations are compared with some measured data.

Absorption↗
PubMed2001

Purification and functional reconstitution of intact ral-binding Gtpase activating protein, RLIP76, in artificial liposomes.

We have recently shown that RLIP76, a ral-binding GTPase activating protein, mediates ATP-dependent transport of glutathione-conjugates (GS-E) and doxorubicin (DOX) (S. Awasthi et al., Biochemistry 39,9327,2000). Transport function of RLIP76 was found to be intact despite considerable proteolytic fragmentation in preparations used for those studies, suggesting either that the residual intact RLIP76 was responsible for transport activity, or that the transport activity could be reconstituted by fragments of RLIP76. If the former were true, intact RLIP76 would have a much higher specific activity for ATP-hydrolysis than the fragmented protein. We have addressed this question by comparing transport properties of recombinant RLIP76 and human erythrocyte membrane RLIP76 purified in buffers treated with either 100 or 500 microM serine protease inhibitor, PMSF. The purity and identity of recombinant and human erythrocyte RLIP76 was established by SDS/PAGE and Western-blot analysis. These studies confirmed the origin of the 38 kDa protein, previously referred to as DNP-SG ATPase, from RLIP76. Higher PMSF concentration resulted in lower yield of the 38 kDa band and higher yield of intact RLIP76 from both human and recombinant source. In contrast, the substrate-stimulated ATPase activity in presence of DNP-SG, doxorubicin, daunorubicin, or colchicine were unaffected by increased PMSF; similarly, ATP-dependent transport of doxorubicin in proteoliposomes reconstituted with RLIP76 was unaffected by higher PMSF. These results indicated that limited proteolysis by serine proteases does not abrogate the transport function of RLIP76. Comparison of transport kinetics for daunorubicin between recombinant vs human erythrocyte RLIP76 revealed higher specific activity of transport for tissue purified RLIP76, indicating that additional factors present in tissue purified RLIP76 can modulate its transport activity.

ATP-Binding Cassette Transporters↗
PubMed2001

[Identification of key toxicants in a bleaching effluent--a case study].

The toxicity identification evaluation (TIE) was conducted with a toxic bleaching effluent to identify its toxic components. Toxicity characterisation procedures (phase I) indicated that the primary toxicants in the effluent were volatile, and could be reduced by sodium thiosulfate. Toxicity-based fractionation techniques (phase II) were conducted, and the oxidation organic chloridates were found not to be the major toxicants. Deletion approach of phase III confirmed that the toxicity decreased with the decrease of free and total residual chlorine concentrations, indicating that Cl2, HClO and ClO- were identified as primary toxicants in the effluent.

Chlorine↗
PubMed2001

ATP sensitive K+ channel may be involved in the protective effects of preconditioning in isolated guinea pig cardiomyocytes.

OBJECTIVE: To develop a cellular model of preconditioning by a brief period of hypoxia in isolated guinea pig cardiomyocytes and to determine whether or not an ATP sensitive K+ (KATP) channel is involved in ischemic preconditioning. METHODS: Single myocytes were isolated from the ventricle of adult guinea pigs. The experimental chamber allowed the cells to be exposed to low O2 pressure. During hypoxic preconditioning, the cells were equilibrated with normaxic solution for 10 minutes and then exposed to hypoxia for 5 minutes, followed by 10 minutes of reoxygenation. The cells were then subjected to 20-180 minutes of hypoxia and reoxygenation. Ionic currents were studied with the patch clamp technique in whole-cell and cell-attached configurations. RESULTS: A 5-minute hypoxic preconditioning offered a significant protection from cell injury in subsequent hypoxia-reoxygenation. After a latency of more than 15 minutes, hypoxia induced a time-independent outward K+ current which could be blocked by 5 mumol/L glibenclamide. At 10 mV, the current increased from 78 +/- 15 pA to 1581 +/- 153 pA (P < 0.01, n = 18). However, the latency to develop KATP channel currents (IKATP) was greatly shortened in preconditioned cells, and the current was increased acceleratively. At 10 mV, the current more than 4 nA was recorded in preconditioning cells. In the single channel recordings, the time interval from the first channel opening to maximum opening was also markedly abbreviated in preconditioned cells. CONCLUSION: Isolated guinea pig cardiomyocytes can be preconditioned with a brief period of hypoxia. This hypoxic preconditioning may modify the KATP channel, and make the channel open more readily during the second hypoxia.

Adenosine Triphosphate↗
PubMed2001

bcl 10 gene mutation in hepatocellular carcinoma.

OBJECTIVE: To detect the mutation frequency of the bcl 10 gene in the early and advanced stages of hepatocellular carcinoma (HCC). METHODS: Genome DNA samples were extracted from 46 cases of fresh HCC tumor tissues and their non-tumor adjacent tissues. Polymerase chain reaction-single strand conformation polymorphism method was used to detect point mutations of the three exons of the bcl 10 gene. For each individual exon, six random samples from those showing abnormal DNA bands were sequenced to verify those mutations. The relationship between serum alpha-fetoprotein (AFP) level and bcl 10 mutation, between the tumor size and bcl 10 mutation was also analyzed. RESULTS: Among the 46 samples, 26 cases (56.5%) were found to have mutations in exon 1, 5 out of the 6 cases were shown to have 5744 C-->G mutation by sequencing; 25 cases (54.3%) were found to have mutations in exon 2, 4 out of the 6 cases were shown to have 11,311 T deletion mutation by sequencing. Twenty-one cases (45.7%) were found to have mutations in exon 3, all of the 6 cases selected for sequencing were shown to have 14,116 C-->T mutation. Statistical analysis showed that neither serum alpha-fetoprotein level nor the size of hepatocellular carcinoma has a significant relationship with bcl 10 mutation. CONCLUSION: The bcl 10 gene has a high mutation frequency in liver cancer.

Adaptor Proteins, Signal Transducing↗
PubMed2001

[Biocompatibility of HA/TCP biphasic ceramics with co-cultured human osteoblasts in vitro].

The biocompatibility of HA/TCP ceramic was evaluated by investigation of attachment and growth of osteoblasts on biomaterial, as well as monitoring the effects of biomaterial on expression of functional phenotypes of co-cultured osteoblasts in vitro. When co-cultured with HA/TCP ceramics, osteoblasts firstly attached to the surface of HA/TCP disk, then attached to notches and grew into the micropores of biomaterial during further culture period. At last, the ceramics were almost packed with osteoblasts. Additionally, osteoblasts co-cultured with HA/TCP were similar to osteoblasts cultured under normal condition in osteoblastic phenotypes; the secreted lots of collagen type I, possess strong activity of Alkaline Phosphatase and mineralized extracellular matrix. The fact that osteoblasts could grow well on HA/TCP ceramics and the biomaterial did not affect their physiological function suggest that HA/TCP ceramic is biocompatible with human osteoblasts.

Biocompatible Materials↗
PubMed2001

[Effects of air staging with absorbents on trace metal during coal combustion].

Staged combustion was carried out on laboratory-scale pulverized coal combustion with different absorbents. The experiment indicated staged combustion increased emission of submicron particles, which went against the control of trace elements, especially for those of high volatile elements, such as Cu, Ni. The thermodynamics calculation also indicate the transformation of trace metal was different with different atmosphere, suboxidized and reduced species were more easily formed under reduced condition. In both conditions, absorbents show a certain absorptive ability to trace metal, and different absorbent had different ability. For unstaged combustion, kaolinite was the best for Co, Cr and Ni; dolomite for Be, and CaO for Cu. But for under staged condition, HZ- dolomite was the best for Be, Cr and Ni; Kaolinite for Co and Cu.

Absorption↗
PubMed2001

[The role of released cytochrome C from mitochondria in the apoptosis of HUVECs induced by hydrogen peroxide].

OBJECTIVE: To explore the role of mitochondria and from which released cytochrome C in the apoptosis of HUVECs induced by H2O2. METHODS: HUVECs were cultured with H2O2 of 100 mol/L for 24 hrs. H2O2 was added after that HUVECs were precultured with CsA (cyclosporin A) for 30 mins. The cell samples were collected at different time points for DAPI staining and counting of apoptotic cell number. Simultaneously, the changes of mitochondrial permeability was observed by Rhoadmine 123 accumulation. The changes of the cytochrome C concentrations in plasma and mitochondria were determined by western blot. RESULTS: HUVECs exhibited obvious apoptosis after being processed by H2O2. The apoptotic cell number increased since 4 hrs of culturation of HUVECs with H2O2, and reached peak level at 12 hrs. And the HUVEC apoptosis induced by H2O2 could be inhibited significantly by CsA. H2O2 could lead to the decrease of mitochondrial cytochrome C concentration, which in turn lead to the increase of cytoplasmic cytochrome C concentration. Similarly, mitochondrial Rhoadmine 123 concentration decreased and the mitochondrial permeability increased. But CsA could obviously inhibit the changes of both mitochondrial Rhoadmine 123 and permeability. CONCLUSION: H2O2 could induce cytochrome C releasing to cytoplasma which lead to endothelial apoptosis. And CsA could inhibit the apoptosis by maintaining the normal function of mitochondrial membrane.

Apoptosis↗
PubMed2001

[Epidemiological observation on effect of Leptospiral outer membrane vaccine].

OBJECTIVE: To study the safety and effect of Leptospiral outer membrane vaccine. METHODS: Eighty thousands dosages of Leptospiral outer membrane vaccine were vaccinated in Jingzhou and Shishou city Hubei prevince. Temperaure, side-effects such as Local edema with in 48 hours as well as the incidence of Leptospirsis within a year among those were vaccinated and unvaccinated were observed. RESULTS: (1) No any severe side-effect and abnormal reaction, was found, only 2 case suffered from slight fever and local edema which receded in 48 hrs. (2) Effects of Leptospiral outer membrane vaccine were as follows: 2 cases were attacked by lacterohaemorrhagiae in vaccination group and 47 cases in control group, so the protection rate 95.57% and confidence interval (CI) was 85.43% - 98.20%. Fifteen hebdomadis cases were found in control group. The protection rate of this vaccine reached 100.00%, CI 77.08% - 100.00%. CONCLUSION: Safty and protective effect were well showed when type of bacteria was concordant with that in vaccination district.

Adolescent↗
PubMed2001

[The effect of Lipopolysacharide (LPS) on morphology and function of human umbilical endothelial cells (HUVECs)].

OBJECTIVE: To study the effects of LPS on the morphology and function of HUVECs, so as to explore the roles of activated vascular endothelial cells (VEC) by LPS in systemic inflammatory reaction, sepsis and MOF. METHODS: HUVECs primarily cultured in vitro were employed as the model. Inverted microscope was used to observe the effects of LPS on the morphology of HUVECs. ELISA was used to assess the IL-6 content. The expression of ICAM-1 was determined by immunofluorescent staining method with confocal laser-scanning fluorescence microscope. RESULTS: The morphology of HUVECs could be altered by LPS to become long cord-like in shape. The smallest dose of LPS for stimulating the secretion of IL-6 from HUVEC was 1 ng/ml, and the effect was enhanced parallel to the increase of the concentration of LPS and reached top level at 8 postburn hours. The expresson of ICAM-1 on the nucleic and cytoplasmic membrane of HUVECs increased obviously after HUVECs was cultured with LPS (10 ng/ml) for 24 hours when observed by laser confocal scanning light microscope. CONCLUSION: The morphology and function of HUVECs could be evidently affected by LPS. As a result, LPS might play important roles in the increase of vascular permeability, the promotion of leukocytic adherence, and the initiation of inflammatory cascade reaction.

Cell Line↗
PubMed2001

[Screening and characterization of human phage antibody to hepatitis virus C NS5A antigen].

OBJECTIVE: To screen and characterize human phage antibody against hepatitis C virus (HCV)NS5A antigen. METHODS: The recombinant phages were panned by recombinant HCV NS5A antigen which was coated in a microtiter plate; after five rounds of biopanning, 35 clones were obtained and demonstrated specific to NS5A antigen. The specific binding capacity of the ScFv antibody to HCV NS5A antigen was determined by ELISA. RESULTS: HCV NS5A phage antibody had a specific combination capacity with hepatitis C virus NS5A antigen. The DNA sequence data showed that the ScFv gene was composed of 789 bp and codes for a peptide of 262 amino acid residues. CONCLUSIONS: Human single chain antibody to hepatitis C virus NS5A antigen has been identified by means of the phage display technology.

Antibodies, Viral↗
PubMed2001

[Histopathological observation of experimental slight viral myocarditis].

To study the diagnostic method of slight viral myocarditis in the field of forensic pathology, slight viral myocarditis model was induced in Balb/c murine by coxsackie virus B3. Organs of hearts, livers, spleens, lungs and kidneys were examined through routine pathological methods. Pathological changes at different levels of these organs were observed. The results indicated that viral myocarditis was a kind of disease with multiple organ alterations and that the pathological observation and comprehensive analysis of multiple organs was one of the useful methods for diagnosing slight viral myocarditis.

Animals↗