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Biomedical subjects

W Chen

Publications and source records attributed to W Chen.

At least 343 records · Page 19Linked to original sources
PubMed2000

Structure and expression of a membrane component of the inhibin receptor system.

The purification and cloning of a membrane-anchored proteoglycan with affinity for inhibin A are described. Bovine pituitary membranes were isolated, and membrane-anchored proteins were solubilized and used as an enriched source of inhibin binding protein. The extract was passed over an inhibin A affinity column, and a protein, designated p120, was identified as an inhibin-binding moiety. A partial amino acid sequence was determined for the protein, which matched two human complementary DNAs (cDNAs) in the database. The full-length cDNA predicts a 1336-amino acid glycoprotein. Full-length p120-encoding cDNAs were isolated from human testis RNA and cloned into expression vectors. Two p120 messenger RNA transcripts of 4.6 kb and 2 kb are detected in rat pituitary by RNA blot analysis. Similar analysis of rat testis RNA revealed transcripts of identical molecular mass, albeit at lower abundance. To determine the cellular localization of p120 in pituitary and testis, an antibody directed against the predicted extracellular domain of the protein was generated and used in an immunohistochemical analysis of thin tissue sections. p120 immunostaining is coincident with FSHbeta immunopositive gonadotrope cells in rat pituitary. p120 staining is intense in the testicular Leydig cells, which bind iodinated inhibin but not iodinated activin. In summary, an inhibin-binding protein has been isolated that is produced in tissues that are targets of inhibin action.

Activin Receptors↗
PubMed2000

Lentiviral vector transduction of hematopoietic stem cells that mediate long-term reconstitution of lethally irradiated mice.

Lentiviral vectors efficiently transduce human CD34(+) cells that mediate long-term engraftment of nonobese diabetic/severe combined immunodeficient mice. However, hematopoiesis in these animals is abnormal. Typically, 95% of the human cells in peripheral blood are B lymphocytes. To determine whether lentiviral vectors efficiently transduce stem cells that maintain normal hematopoiesis in vivo, we isolated Sca-1(+)c-Kit(+)Lin(-) bone marrow cells from mice without 5-fluorouracil treatment, and transduced these cells in the absence of cytokine stimulation with a novel lentiviral vector containing a GFP (green flourescent protein) reporter gene. These cells were transplanted into lethally irradiated C57Bl/6 mice. In fully reconstituted animals, GFP expression was observed in 8.0% of peripheral blood mononuclear cells for 20 weeks posttransplantation. Lineage analysis demonstrated that a similar percentage (approximately 8.0%) of GFP-positive cells was detected in peripheral blood B cells, T cells, granulocytes and monocytes, bone marrow erythroid precursor cells, splenic B cells, and thymic T cells. In secondary transplant recipients, up to 20% of some lineages expressed GFP. Our results suggest that quiescent, hematopoietic stem cells are efficiently transduced by lentiviral vectors without impairing self-renewal and normal lineage specification in vivo. Efficient gene delivery into murine stem cells with lentiviral vectors will allow direct tests of genetic therapies in mouse models of hematopoietic diseases such as sickle cell anemia and thalassemia, in which corrected cells may have a selective survival advantage.

Animals↗
PubMed2000

Age-related patterns of the clustering of cardiovascular risk variables of syndrome X from childhood to young adulthood in a population made up of black and white subjects: the Bogalusa Heart Study.

The age-related patterns of clustering of cardiovascular risk variables of Syndrome X from childhood to adulthood were examined in a community-based sample of black and white children (aged 5-10 years, n = 2,389), adolescents (aged 11-17 years, n = 3,371), and young adults (aged 18-37 years, n = 2,115). In the analysis of clustering, insulin resistance index, BMI, triglycerides/ HDL cholesterol ratio, and mean arterial pressure were used either as categorical variables (age-, race- and sex-specific values >75th percentiles) to calculate risk ratios (observed frequency/expected frequency) or as continuous variables (normal scores based on ranks) to compute intraclass correlations. In the total sample, the risk ratio for clustering of adverse levels of all 4 variables was 9.8 for whites (P < 0.01) versus 7.4 for blacks (P < 0.01); the intraclass correlation was 0.33 for whites (P < 0.001) versus 0.26 for blacks (P < 0.001). Both the risk ratio and intraclass correlation were significantly higher in whites than in blacks in the total sample. The intraclass correlations of the 4 variables were significant (P < 0.001) in all race and age-groups, and they were higher during preadolescence and adulthood than during adolescence. Furthermore, unlike risk ratios, intraclass correlations showed a continuous increase with age during adulthood. When BMI was adjusted, the intraclass correlations involving the other 3 variables were reduced by approximately 50%, and the age-related pattern was no longer evident. These results suggest that the degree of clustering of risk variables of Syndrome X varies with age from childhood to adulthood and is likely influenced by the age-related changes in obesity and the attendant insulin resistance.

Adolescent↗
PubMed2000

The use of archival bone marrow specimens in detecting B-cell non-Hodgkin's lymphomas using polymerase chain reaction methods.

The detection of B-cell non-Hodgkin's lymphoma (B-NHL) involving the bone marrow (BM) can be enhanced by assessing immunoglobulin heavy chain (IgH/JH) gene rearrangement using PCR. While the fresh BM aspirate has been the most commonly used specimen, the utility of archival BM tissues has not been extensively evaluated. We studied the BM from 13 patients with nodal B-NHL (7 low-grade and 6 intermediate grade), which were categorized into three groups based on the histologic finding of lymphoma (H) and the presence of a monoclonal IgH/JH band by PCR using fresh BM aspirates (M): (1) H(+)/M(+), 4 cases; (2) H(+)/M(-), 4 cases; and (3) H(equivocal)/M(-), 5 cases. Archival tissues available for study included paraffin-embedded trephine biopsy (TB)/aspirate clots (AC) and air-dried aspirate smears (AS). All TB (13/13) and a subset of AC (5/13) were B5-fixed, and all these tissues failed to yield analyzable DNA. In contrast, sufficient DNA was consistently obtained in AC that were formalin-fixed (8/13). Of these 8 cases, 2/3 of group 1, 3/3 of group 2, and 0/2 of group 3 had a monoclonal IgH band. Using DNA extracted from microdissected lymphoid aggregates morphologically evident in the AC sections, additional positive cases were identified: 1/3 of group 1 and 2/2 of group 3. In those 5 cases that did not have formalin-fixed TB/AC, sufficient DNA was extracted from AS in all cases; one additional positive case was identified in group 1. Overall, 4/4 (100%) of group 1, 3/4 (75%) of group 2, and 2/5 (40%) of group 3 showed molecular evidence of lymphoma. To conclude, archival BM specimens are a useful source of DNA for molecular detection of B-NHL involvement, and formalin appears to be a better fixative than B5. The use of these samples may improve the overall detection sensitivity.

Adult↗
PubMed2000

[DNA polymorphism of Pvu II site in the lipoprotein lipase gene in patients with type 2 diabetes mellitus].

OBJECTIVE: To study the relationship between the lipoprotein lipase(LPL) gene and type 2 diabetes mellitus (DM) and its lipid metabolism. METHODS: PCR-RFLP method was used to determine the DNA polymorphism of 6th intron at LPL gene in 127 DM patients and 125 controls. RESULTS: The allele frequencies in case and control groups were 69.3%, 63.6% for "P+" and 30.7%, 36.4% for "P-", respectively; the frequencies of genotypes were 48.0%, 44.8% for P+/P+, 42.5%, 37. 6% for P+/P- and 9.45%, 17.6% for P-/P-, respectively. There was no significant difference in frequencies of genotypes or alleles between the two groups. The LPL Pvu II polymorphism in Chinese population was similar to that in Japanese population, and was different from that in European and American population. CONCLUSION: The LPL-Pvu II-RFLP in Chinese population is not significantly associated with type 2 diabetes mellitus. The significant difference of Pvu II-RFLP among various races was observed.

Adult↗
PubMed2000

Impact of Helicobacter pylori eradication on the development of MALT, gland atrophy and intestinal metaplasia of the antrum.

BACKGROUND: Chronic Helicobacter pylori infection leads to the development of mucosa-associated lymphoid tissue (MALT), gland atrophy, intestinal metaplasia, and in certain individuals, gastric lymphoma and adenocarcinoma. We conducted a prospective study to determine the effect of H pylori eradication on the development of MALT, gland atrophy and intestinal metaplasia. METHODS: From July 1995 to October 1996, 63 consecutive patients with H pylori-associated peptic ulcer disease were enrolled in a bacterial eradication trial. The grade of MALT and the degree of gastritis of the antrum were assessed using Wotherspoon's scale and the Sydney system before treatment, and at eight weeks and one year after H pylori eradication therapy. RESULTS: During the study period, 43 patients received complete follow-up. In the patient group with eradication failure (n = 22), MALT score was significantly decreased at the end of the eighth week (p < 0.05) but returned to the initial level by one year of follow-up. There were no changes in the scores for inflammation, neutrophil activity, gland atrophy or intestinal metaplasia at the end of the eighth week and at one year following H pylori eradication therapy. In contrast, there was a marked reduction in the MALT, inflammation, and activity scores at eight weeks (p < 0.01, < 0.05 and < 0.05, respectively) and one year after treatment (p < 0.05, < 0.001 and < 0.001, respectively) in the patient group with successful eradication (n = 21). However, no significant changes in gland atrophy and intestinal metaplasia were observed during the follow-up period. CONCLUSIONS: Eradication of H pylori leads to regression of MALT in the stomach, but the degrees of gland atrophy and intestinal metaplasia remain unchanged, even after one-year of follow-up.

Adult↗
PubMed2000

[The relationship between nonalcoholic fatty liver and insulin resistance with abnormal glucose metabolism].

OBJECTIVE: To explore the correlation of nonalcoholic fatty liver (called "fatty liver" for short) and insulin resistance with abnormal glucose metabolism. METHODS: The subjects were 48 patients with fatty liver, while the controls were 15 normal persons. Oral glucose tolerance test (OGTT) and insulin release test were performed; and the area under curve of serum glucose (AUCSG), area under curve of insulin (AUCIns) and insulin sensitivity index (AUCSG/AUCIns) were calculated. RESULTS: The insulin level in fatty liver group was significantly higher than that in normal control group at 60 min, 120 min and 180 min after glucose intake (P<0.01) with the postpond peak. The blood glucose level in the fatty liver group was significantly higher than that in normal control group at all time intervals except at 180 min after glucose intake (P<0.05). The AUCIns and AUCSG in the patient group were significantly higher than in the control group 209.56 vs 124.22, 24.72 vs 19.96, respectively (P<0.01). The insulin sensitivity index in the patient group was significantly lower than that in the control group (P<0. 05). There is no significant difference in the insulin sensitivity index between different degree of fatty liver (P>0.05). CONCLUSION: It is evident that patients with fatty liver have insulin resistance with abnormal glucose metabolism, which is not related with the extent of fat infiltration in the liver, suggesting that insulin resistance with abnormal glucose metabolism is a very important contributor to the pathogenesis of fatty liver.

Adult↗
PubMed2000

Expression of vascular endothelial growth factor in liver tissues of hepatitis B.

OBJECTIVE: To study the relationship between vascular endothelial growth factor (VEGF) and grading (G) and staging (S) of hepatitis B (HB). METHODS: Immunohistochemical staining was performed with VEGF monoclonal antibody in 250 biopsies of HB. RESULTS: The types of VEGF expression in liver tissues were of plasma type, sinusoidal membrane type and sinusoidal endothelial cell type. VEGF was mainly secreted by hepatocytes, and was also positively expressed in liver sinusoidal endothelial cells, fat-storing cells, myofibroblast and monomorphological nuclear cells. And it was negative in vascular endothelial cells and hepatocytes which had not significant damage, suggesting that the expression of VEGF was enhanced with the increase of G (chi(2)=90.43, P<0.01). VEGF was positively expressed on those whose scores of S were lower, while strongly positively expressed on those whose scores of S were higher. There was also a significant difference between them (chi(2)=115.74, P<0.01). CONCLUSION: The expressions of VEGF are related to G and S of HB

Endothelial Growth Factors↗
PubMed2000

[A study of transgenic IFV cattle integrated with human serum albumin gene].

The mammary gland expression vector (pcDNA 3.1-GCALBm) containing the full-length sequence of human serum albumin (hALB) cDNA and intron 1 as well as the goat beta-casien gene promoter and 5' up-stream regulatory sequence was constructed. The vector was micro-injected into bovine IVF eggs. The embryos were in vitro cultured to the late stage of morulae, and then few embryo cells were aspirated for the implantation detection of target gene integration and SRY DNA sequence using nested-PCR. Afterwards, ten integrated embryos were selected to transfer into eight recipients and three were pregnant. The pregnant rate was 37.5%(3/8). However, two were miscarried in mid-trimester but one was pregnant at term to deliver a male transgenic cattle integrated with hALB mini-gene. The transgenic efficiency was 12.5% (1/8).

Animals↗
PubMed2000

Rapid initial removal of chylomicron remnants by the mouse liver does not require hepatically localized apolipoprotein E.

Apolipoprotein E (apoE) is a ligand for the low density lipoprotein receptor (LDLR) and the low density lipoprotein receptor-related protein (LRP). The aim of the present study was to clarify the role of hepatically localized apoE in the rapid initial removal of chylomicron remnants by using the isolated perfused liver. Radiolabeled chylomicron remnants were perfused in a single nonrecirculating pass into the livers of C57BL/6J (wild-type) mice, apoE-knockout mice, and apoE/LDLR-knockout mice for a period of 20 min. Aliquots of the perfusate leaving the liver were collected at regular intervals and the rate of removal of radioactivity was determined. At a trace concentration of chylomicron remnants (0.05 microgram of protein per ml), wild-type mouse livers removed at a steady state of 50-55% of total chylomicron remnants perfused per pass; livers from apoE-knockout mice had the same capacity as wild-type mouse livers. When the concentration of remnants was increased to 12 microgram of protein per ml, a level at which it has been shown that LDL receptor and LRP are near saturation, the capacity of the wild-type mouse livers to remove chylomicron remnants was decreased to 10-25% per pass, confirming that the removal mechanisms were nearing saturation. However, instead of finding a greater reduction in the removal rates or impairment in chylomicron remnant removal, livers from apoE-knockout mice were just as efficient as those from wild-type mice in removing remnants. Livers of mice that lacked both apoE and the LDLR also had a similar rate of removal at relatively low remnant concentrations (0.05-0.5 microgram/ml), but had reduced capacity in removing remnants at a relatively high concentration (4-12 microgram/ml) of chylomicron remnants ( approximately 20% per pass). The rate of removal at these concentrations, however, was similar to that attributed to the LRP in previous studies. Chylomicron remnants, whose apolipoproteins were disrupted by trypsinization, were removed at a normal rate by wild-type mouse livers but there was almost no removal by apoE-knockout mouse livers. At higher concentrations, however, the removal of apolipoprotein-disrupted chylomicron remnants was decreased. Our present findings do not support the hypothesis that hepatically localized apoE is a critical factor in the rapid initial removal of chylomicron remnants by either of the major pathways but do suggest that hepatically localized apoE can be added to lipoproteins to accelerate their uptake, although this process may have a limited capacity to compensate for apoE deficiency on lipoproteins.

Animals↗
PubMed2000

Interspousal transmission of TT virus: low efficiency and lack of apparent risk factors.

BACKGROUND: The TT virus (TTV) is a newly identified human DNA virus and little is known about its non-parenteral transmission. The aim of the present study was to explore the prevalence of TTV infection in spouses of index cases and the related risk factors. METHODS: Serum TTV-DNA was studied in spouses of 41 subjects with TT viremia. For couples in which both husband and wife had TT viremia, nucleotide sequences of the open reading frame-1 region were analyzed by phylogenetic tree constructions. RESULTS: Three (7%) of 41 spouses were positive for TTV-DNA. No differences were noted between index patients with seropositive spouses and those without seropositive spouses with regard to clinical characteristics, including parenteral risk factors and exposure duration. Nucleotide sequence comparison and phylogenetic tree analysis of the viral genome in three TTV-infected couples revealed the isolates to be closely related in two, with a homology of 97 and 98%, respectively. CONCLUSIONS: These results suggest that interspousal transmission of TTV does occur; however,the efficiency of transmission is low compared with hepatitis C virus and GB virus-C. There are no apparent risk factors for transmission between spouses and further studies are needed to clarify other modes of non-parenteral transmission.

Adult↗
PubMed2000

[Progress on studies of nikkomycin structure and some genes related to nikkomycin biosynthesis].

Nikkomycin is a kind of new antifungal antibiotics. More than 20 biologically active nikkomycin structures have been isolated and the main active structures are nikkomycins X, Z, I, J. Here, we introduce the progress on the studies of nikkomycin structures, the relationships between nikkomycin structure and biological activity, and genes related to nikkomycin biosynthesis.

Aminoglycosides↗
PubMed2000

[Construction and nucleotide sequence assay of human anti-HBs variable region single-chain antibody gene].

The VH and Vk gene which were acquired using phage display technology have been combined by a linker encoding a flexible peptide (Gly4 Ser)3 to form a single-chain. Its nucleotide sequence was assayed after cloning the scFv gene into middle plasmid. The successful construction of single-chain gene lays the foundations for the subsequent expression and production of double functional antibody.

Amino Acid Sequence↗
PubMed2000

[Computerized surgical simulation with 3D reconstruction of upper limbs].

This paper reports our study on how to realize computerized surgical simulation through reconstructing 3D anatomy of upper limbs. CT images and serial sections of upper limbs were matched to reconstruct 3D images. We compiled the computer programs of 3D reconstruction and surgical simulation with borland C++ computer language, and built 3D digital model of anatomic structure of upper limbs. The results showed that all structures reconstructed could be displayed alone, in any group or totally. While operating, we could choose one of three segments of the upper limbs model and operate on any parts and in any direction. The surgical simulation system could be used to design operative schemes, choose the best operative paths, and teach the processes of operations and anatomy. It could run in 586-personal computers.

Arm↗
PubMed2000

[Chronic low dose follicle stimulating hormone step-up regimen in the treatment of polycystic ovary syndrome related anovulatory infertility with clomiphene resistance].

OBJECTIVE: To assess the efficacy and safety of chronic low-dose follicle stimulating hormone (FSH) step-up regimen in ovulation induction of polycystic ovary syndrome(PCOS) related infertile patients with clomiphene (CC) resistance. METHODS: Nine PCOS related infertile patients with CC resistance were enrolled for ovulation induction by chronic low-dose FSH step-up regimen, using urinary FSH (Metrodin) or recombinant human FSH (Gonal-F) 5 cycles respectively. Follicular development was monitored by transvaginal ultrasonography and serum estradiol (E2) measurements. RESULTS: Nine out of ten cycles ovulated, among them 5 had monofollicle development, one achieved single pregnancy. No ovarian hyperstimulation syndrome(OHSS), local or systemic side effect was seen. CONCLUSION: Chronic low-dose FSH step-up regimen is an effective and safe choice in inducing ovulation for CC-resistant PCOS infertile cases. Transvaginal ultrasonography and serum E2 measurement are equally important for appropriate dose adjustment and avoidance of cancellation or OHSS.

Anovulation↗
PubMed2000

Comet assay and cytokinesis-blocked micronucleus test for monitoring the genotoxic effects of X-ray radiation in humans.

OBJECTIVE: To assess the genotoxic effects of X-ray radiation on human populations. METHODS: The single cell gel electrophoresis (SCGE) and cytokinesis-blocked micronucleus (CBMN) test were applied as biological dosimeters to detect DNA damage and abnormalities in human peripheral lymphocytes of subpopulation exposed to X-ray radiation. The subjects were divided into four groups: 12 radiation-patients; 13 intervention-radiation-therapy doctors; 32 radiation-diagnostians; 28 controls. RESULTS: The average comet lengths of the four groups were 128.17 +/- 4.49 microns, 88.09 +/- 5.39 microns, 72.68 +/- 2.57 microns and 32.87 +/- 0.57 microns, respectively. The difference in average comet length between any two groups was highly significant (P < 0.01). The average micronucleated cell (MNC) rates (@1000) of the four groups were 12.33 +/- 0.85, 9.75 +/- 1.02, 8.48 +/- 0.66 and 3.18 +/- 0.36, respectively. The difference of MNC rates of Group 1 vs 3, 1 vs 4, 2 vs 4 and 3 vs 4 was highly significant (P < 0.01), and the difference of Group 1 vs 2 was significant (P < 0.05), but there was no difference of MNC rate in Group 2 vs 3 (P > 0.05). CONCLUSIONS: This study showed that both the comet assay and the CBMN test could be used to monitor populations exposed to X-ray radiation, but the comet assay seems to be more sensitive than the CBMN test.

Adult↗