Biomedical subjects
Publications and source records attributed to L Xu.
The morphological characters and commercial idendification on medicinal materials named "Hailong" has been reported. The results of identification of 48 commercial samples indicated "Hailong" is adulterated with Halicampus koilomatodon, Trachyrhamphus serratus and Microphis boaja, Solenognathus güntheri besides three species accepted by Pharmacopoeia.
The SEM observation of the medicinal meterials "Hailong" have been carried out. The results showed there are significantly difference among 7 species "Hailong".
The morphological characters and commercial identification on Haima has been reported. The results of identification of 60 commercial samples indicated that all of Haima was the species accepted by Pharmacopoeia. Hippocampus kelloggi, H. histrix, H. kuda and H. trimaculatus were mainly used in Hainan, Guangdong and Fujian Province; H. japonicus was mainly used in Shandong and Liaoning Province; Imported Haima was H. histrix.
A reverse transcription polymerase chain reaction assay with nested primers (RT-nested PCR) deduced from the 5' untranslated region of HGV genome was established to detect HGV RNA. By using this assay, we tested the serum samples of 106 paid blood donors, 80 intravenous drug users and 168 cases with viral hepatitis in Shenzhen, China. The positive rates of HGV RNA were 8.5%, 46.3% and 7.7%, respectively. The positive rates of HGV RNA in 61 cases with chronic hepatitis B and 33 cases with chronic hepatitis C were 8.2% and 21.2%. Among the 33 cases with chronic hepatitis C, the positive rate of HGV RNA in 15 cases infected with HCV by blood or blood products was 40.0%, compared with 1.7% in 18 cases without exposure to blood or blood products (P<0.05). The results of this study suggest that HGV infection is common in paid blood donors; the intravenous drug user is the population at high risk for HGV infection; the patients with post-transfusion chronic hepatitis C are often supperinfected with HGV.
Three lot of HBsAg autologous red cell agglutination kits (ARCA kit) have been qualified in lab, clinical trial and the stability confirmation have been performed. The sensitivity of the kits is 1ng/ml HBsAg. A, B, O, AB type of peripheral blood or antiagglutinated specimens can be used for assay. No Holk effect has been found. The repeated rate of 10 samples assayed for five times reached 100%. The specimens collected from HAV, HCV, Schistosoma Japonicum infected patients or RF positive patients do not interfere the test. The specificity of the kits is very high. 1712 clinical specimens were inspected comparing with the EIA kits in market. The relativity between the two methods is 0.985. 18 of the 26 specimens which two methods did not accord with each other have been confirmed. The false positive and missing detected for ARCA kits is 1, 3 and for EIA kits are 6, 8 respectively. ARCA kits are stable in 4 degrees C and 22 degrees C for more than one year. The kits can stand in 35 degrees C, 45 degrees C for 45 and 10 days without losing activity respectively.
OBJECTIVE: To elucidate the expanding response of cord blood CD34+ cells to human hematopoietic growth factors (HGFs) and evaluate their grafting efficiency. METHODS: CD34+ cells were isolated from umbilical cord blood by using a high-gradient magnetic cell sorting system (MACS), expanded with HGFs in a liquid culture system and evaluated of grafting efficiency with a panning assay on an adult bone marrow stroma. RESULTS: The percentage of CD34+ CD38- subset in cord blood was much higher than that in bone marrow or peripheral blood. Treatment with a combination of HGFs, including SCF, IL-3, IL-6, G-CSF,and Epo increased hematopoietic progenitor cells by nearly 100 fold and nucleated cells by more than 500 fold. 68.0%-89.6% of the CD34+ cells treated with HGFs (GM-CSF or IL-3, alone or in combination) seeded in the pre-irradiated marrow stroma, whereas only 36% of the untreated ones did. CONCLUSION: It is possible to expand cord blood CD34+ cells ex vivo and to improve their grafting efficiency with HGFs.
A rapid high performance liquid chromatography for determination of demethylvancomycin in neonate serum has been developed. The procedure involved a simple protein precipitation by acetonitrile-isopropanol (1:1) and then the sample was chromatographed on a reversed phase C18 column with UV detection at 236 nm. The mobile phase was CH3CN: 0.05 mol/L KH2PO4 = 8:92 (V/V). The calibration curve was Y = 35,721.89X - 13,031.54, r = 0.9998 and he detection limit was 0.3 mg/L. The average recovery was 94.7% +/- 1.2%. Intra-day and inter-day RSD were 2.23% and 2.62% respectively. It can be concluded that this method meets the requirement for routine clinical application. This method has been used to determine serum concentration of demethylvancomycin in neonates. The data obtained showed that the method was simple, rapid, sensitive and precise.
Fourty eight recombinant plasmids containing CA repeats were isolated from human chromosome 8q24.1 band-specific pUC19 library. Among them, inserted DNA fragments from 12 plasmids were sequenced, and one new highly polymorphic (CA)n microsatellite was obtained (coding: D8S7F). It contained 11 alleles. The estimated heterozygosity reached 0.84 and 0.83 among Chinese Han Nationality people and American Anglo-Saxons respectively. It was assigned to chromosome 8 by using a human-rodent hybrid cell panel.
Germline mutations of the neurofibromatosis 2 (NF2) gene are associated with an increased incidence of gliomas and glial harmartomas, suggesting a role for the NF2-encoded protein, merlin, in glial growth control. Using monoclonal and polyclonal anti-merlin antibodies for Western blotting and immunohistochemistry, we evaluated the cellular pattern of merlin expression in the normal human central nervous system (CNS), reactive gliosis; and NF2-associated glial hamartomas. In the normal CNS, merlin is widely expressed in coarse cytoplasmic granules in both glia and neurons, with less pronounced expression in other cells. Merlin is also expressed in reactive astrocytes and in the astrocytes of NF2-associated glial hamartomas. In reactive astrocytes, however, merlin is also present at the cell membrane and in cellular processes, suggesting redistribution of the protein in activated cells. Merlin is structurally related to ezrin, radixin and moesin, which are also expressed in the CNS, as demonstrated by Western blotting. The pattern of merlin expression, however, is distinct from that of ezrin, which has been previously described, and that of moesin, in which immunohistochemistry with an anti-moesin antibody showed expression in endothelial cells, glia and neurons in a membranous or diffuse cytoplasmic pattern. These findings imply that merlin has widespread and specific functions in the human central nervous system.
Mouse mammary tumor virus (MMTV) causes mammary carcinomas and T-cell tumors in mice. MMTV variants that induce T-cell tumors have a large deletion within the U3 region of the long terminal repeat (LTR) compared to MMTV strains that induce mammary tumors. We provide evidence here that T-cell tropic MMTV strains lack a redundant binding site for a cellular protein called NBP (negative regulatory element binding protein). The lack of NBP-binding sites in T-cell tropic MMTV strains presumably leads to higher levels of transcription in T-cells during the MMTV life cycle and an increased incidence of mutagenic integration events.
NF2 (neurofibromatosis 2, encoding the merlin protein) gene mutations and chromosome 22q loss have been demonstrated in the majority of sporadic and NF2-associated schwannomas, but many schwannomas fail to demonstrate genetic evidence of biallelic NF2 gene inactivation. In addition, the role of the merlin-related ERM family members (ezrin, radixin, and moesin) remains unclear in these tumors. We therefore studied expression of NF2-encoded merlin as well as ezrin, radixin, and moesin in 22 vestibular and peripheral schwannomas that had been evaluated for NF2 mutations and chromosome 22q loss. Western blotting and immunohistochemistry with antibodies directed against the amino and carboxy termini of merlin demonstrated loss of merlin expression in all studied schwannomas, including 12 tumors lacking genetic evidence of biallelic NF2 gene inactivation. Western blotting with antibodies directed against ezrin, radixin, and moesin, however, showed expression of these proteins in all schwannomas. In addition, immunohistochemistry with an antibody to moesin revealed widespread expression in tumor and endothelial cells. These data indicate that the specific loss of merlin is universal to schwannomas and is not linked to loss of ezrin, radixin, or moesin expression.
OBJECTIVE: To investigate the expression of nm23-H1 in epithelial ovarian cancer. METHODS: A total of 55 specimens from patients with epithelial ovarian cancers, 15 patients with serous cancers, 7 with mucinous cancers, 17 with endometrioid cancers and 16 with adenocarcinomas, were examined for the expression of nm23-H1 by means of the immunohistochemical technique. RESULTS: The total positive rate was 23.64% (13/55). The tissular nm23-H1 immunostaining had significantly higher expression in mucinous cancer (57.14%) than in other histologic types of epithelial ovarian cancer (P < 0.05). Compared to that in the primary tumor, nm23-H1 expression in the omental metastatic tumor in the same patient was reduced. CONCLUSIONS: The expression rate of nm23-H1 is higher in the primary tumors than in the metastatic tumors and is different in various histologic subtypes of epithelial ovarian cancer. The expression of nm23-H1 may participate in the inhibitory process of tumor invasion.
OBJECTIVE: To explore the distribution frequencies of vitamin D receptor (VDR) gene polymorphisms in Chinese and the relationship between VDR genotypes and bone mineral density (BMD) or serum osteocalcin level in Chinese women. METHODS: Polymorphisms of VDR gene were analyzed by polymerase chain reaction (PCR) to amplify the DNA sequence and three restriction enzymes (namely BsmI, ApaI and TaqI) to digest the PCR products in 223 subjects. Some of the VDR genotypes were also confirmed by Southern hybridization analysis. BMD was measured at the spine and proximal femur by dual-energy X-ray absorptiometry (DEXA). Serum osteocalcin concentrations were determined by radioimmunoassay. RESULTS: Chinese had high frequencies of "b,a,T" alleles, 95%, 75% and 95% respectively, which were much different from Caucasians. "BB" or "AA" genotype had tendency for higher BMD at some sites in the group of young women, whereas in the group of postmenopausal women, "bb" or "aa" genotype had relationship with lower BMD at femoral neck and trochanter. Furthermore, no relationship were found between VDR genotypes and the serum osteocalcin level in Chinese women. CONCLUSIONS: Allele frequencies of VDR gene in Chinese are different from those in Caucasians. VDR gene polymorphisms are associated with BMD in Chinese, but in a different pattern from other reports. Further study on predicting function of VDR for osteoporosis is necessary.
OBJECTIVE: To evaluate the relationship of E-cadherin (E-CD) expression to cellular DNA content and biological behavior of gastric cancer. METHODS: E-CD expression and cellular DNA content were quantitatively measured by flow cytometry and immunofluorescence methods in 80 cases of formalin-fixed, paraffin-embedded gastric cancer. Systematic pathological examinations and follow up were performed for all cases. RESULTS: E-CD expression was significantly reduced in all cases of gastric cancer, fluorescence Index (FI) of E-CD expression was 0.67 +/- 0.11 in gastric cancer, 1.0 +/- 0.07 in normal gastric mucosa (P < 0.001). The reduction of E-CD expression was also found in 2 cases of early gastric cancer. Tumors with a decrease in E-CD expression occurred significantly more frequently in undifferentiated, diffuse growth pattern Borrmann 4 type, positive lymph node (LN) metastasis and infiltrated serosa type gastric cancer, of which survival time was within 5 years (P < 0.001). E-CD expression was also reduced in gastric cancer with the number of LN metastasis above 5, metastasis to more than group 2. E-CD expression was lower in uneuploid cancer than that in diploid cancer (P < 0.01). The value of DI and PI with negative E-CD expression was significantly higher than that of positive E-CD expression (P < 0.01). CONCLUSION: Down-regulation of E-CD expression correlates with bad biological behavior and poor prognosis of gastric cancer. The reduction of E-CD expression may take place during early time of gastric cancer. Quantitative analysis of E-CD expression may have some value in evaluating the intensity of LN metastasis of gastric cancer.
Our previous work showed the existence of low molecular weight tumor suppressors in human fetal tissues. In this paper, two tumor cell suppressors were isolated and purified from methanol extract of human fetal liver by C18 reversed-phase medium pressure chromatography, gel filtration on Sephadex LH-20, and high-performance liquid chromatography, directed by suppression of growth of HL-60 cells. The structures of the suppressors were identified to be 7-ketocholesterol and 7-beta-hydroxycholesterol. Under the condition of in vitro agar plate culture, 7-ketocholesterol and 7-beta-hydroxycholesterol showed preferentially inhibitory effects on the growth of both human and murine leukemic cell lines including human HL-60 and murine S-180 cells, but less effective on the growth of normal human and murine bone marrow granulocyte-macrophage progenitors (CFU-GM).
The purpose of this study was to determine whether sustained local production of murine IFN-beta (mIFN-beta) could inhibit the tumorigenicity and metastasis of human and murine tumor cells implanted into nude mice. Human melanoma cells (A375SM), renal carcinoma cells (SN12PM6), and colon carcinoma cells (KM12SM) were transfected with mIFN-beta or a control neomycin resistance vector. All cell lines grew well in culture. Tumor cells were injected into the subcutis, kidney, spleen, or lateral tail vein of nude mice. Parental or control transfected cells produced local tumors and experimental or spontaneous lung metastases, whereas mIFN-beta-transfected cells did not. In vivo survival experiments using [125I]IdUdR-labeled cells showed that by day 7 after s.c. implantation, all IFN-beta-transfected cells died. IFN-beta transfection prevented the outgrowth of parental or control-transfected cells only when they were injected together with transfected cells into one site, suggesting that IFN-beta promoted a local lysis of the bystander cells. Similar indirect antitumor activity was demonstrated in various human (KM12SM and SN12PM6) and murine (CT-26 colon carcinoma, RENCA renal cell carcinoma, and 3LL Lewis lung carcinoma) tumors. The IFN-beta-transfected tumor cells stimulated a high level of nitric oxide production by murine macrophages under in vitro and in vivo conditions, which correlated with the vigorous nonspecific antitumor activity. Collectively, these results demonstrate that local production of IFN-beta can eradicate tumor cells of different histology by inducing inducible nitric oxide synthase expression in infiltrating cells.
It is well known that the scattered-radiation (SR) results in degradation of the images contrast in digital X-ray radiograph. The main reason affecting radiographic image quality is the SR arising from interaction of the photons with object being radiographed and veiling glare from detector system in the II-TV chai imaging system. With the aim of improving the image quality, we employed the Gaussian function to approximate the scattered point spread function (PSF) and determined the fraction of SR, rho and the parameter, sigma experimentally on an individual system; then we built an inverse filter to process the digital chest X-ray images, which were acquired with the same system and transformed in 2-D Fourier tansform operation. The images processed were corrected by using a variable weihting factor and the resulting images are shown in this paper. The method provides a useful way for solving the problem of correction of the SR in digital X-ray images.
This paper describes an in vitro method to study how interactions between cell suspensions incubated in two culture compartments can occur by diffusion of small molecules through a dialysis membrane. This consists of in vitro cultures of a human PBMC suspension, divided into two parts separated by a dialysis membrane. In one of the cultures, a mitogenic monoclonal antibody (mAb) is added. The porosity of the membrane permits cytokines secreted by activated cells to pass while blocking the antibodies. As a model, PBMC from the same blood donor were divided into two parts and one portion was incubated with an anti-CD3 monoclonal antibody (OKT3 Ortho-Cilag), known to induce IL-2 secretion whereas the other was enclosed in a dialysis bag without antibody. After a 4 day incubation, the cells incubated outside the bag proliferate and secrete cytokines which pass through the membrane and induce cell proliferation inside the bag. This method could complement the currently used methods for the analysis of antibody-mediated cell activation.