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Biomedical subjects

G Chen

Publications and source records attributed to G Chen.

At least 397 records · Page 22Linked to original sources
PubMed1999

The health status of the Singaporean population as measured by a multi-attribute health status system.

BACKGROUND: This paper presents an assessment of the health status of the Singaporean population by the Health Utilities Index (HUI) Mark 3 system. The HUI approach is a generic health status measure that uses a Multi-Attribute Health Status Classification (MAHSC) system. The assessment describes the health status of the population on eight aspects or dimensions of health: seeing, hearing, speaking, walking, use of hands and fingers, feelings, memory and thinking, and pain. DISCUSSION: Differences in health status among different socio-economic and demographic groups are discussed. CONCLUSION: The results of the study may help to better understand population health and health care needs and to plan health care services.

Adult↗
PubMed1999

Supplementation of N-acetylcysteine inhibits NFkappaB activation and protects against alloxan-induced diabetes in CD-1 mice.

Reactive oxygen species (ROS) are involved in the destruction of pancreatic beta cells and the development of insulin-dependent diabetes mellitus (IDDM). However, the cellular mechanism responsible for beta cell death is still unclear. We hypothesize that activation of NFkappaB by ROS is the key cellular signal in initiating a cascade of events leading to beta cell death. Thus, enhancement of pancreatic GSH, a known antioxidant and key regulator of NF-kappaB, should protect against IDDM. Weanling CD1 mice (n=5) were injected with alloxan (50 mg/kg i.v.) to induce IDDM. Using EPR spin trapping techniques, we demonstrated that alloxan generated ROS in the pancreas 15 min after administration. Activation of NFkappaB in pancreatic nuclear extracts was observed 30 min after alloxan injection, as assessed by an electrophoretic mobility shift assay. Fasting blood glucose levels were monitored for 14 days. Supplementation with N-acetylcysteine (NAC, 500 mg/kg), a GSH precursor, inhibited alloxan-induced NFkappaB activation and reduced hyperglycemia. Thus, NFkappaB activation by ROS may initiate a sequence of events leading to IDDM. Inhibition of NF-kappaB activation by NAC attenuated the severity of IDDM. This research will contribute to the understanding of the etiology of IDDM and may lead to the development of better strategies for disease prevention.

Acetylcysteine↗
PubMed1999

[DNA content and cell cycle phase analysis in uterine sarcomas and its clinical significance].

OBJECTIVE: To investigate the relationship among DNA content, cell cycle phase analysis with the clinical-pathological features and prognosis of uterine sarcomas. METHODS: DNA content and cell cycle phase analysis were performed on 75 paraffin-embedded specimens of uterine sarcomas using flow cytometry. RESULTS: Both the aneuploidy rate and DNA index (DI) in specimens from advanced stage and poorly-differentiated cases were significantly higher than those in specimens from early stage and well-differentiated cases (P < 0.05). S-phase fraction (SPF) and proliferation index (PI) were significantly higher in advanced stage than those in early stage (P < 0.05). The 5-year suvival rates for DNA aneuploid and diploid patients were 27% and 76%, respectively (P < 0.01). The 5-year suvival rates for patients with a SPF > 20% and those with SPF < or = 20% were 10% and 56% respectively (P < 0.01). CONCLUSION: DI, SPF, PI and clinical stage are the most important factors affecting the prognosis.

Aneuploidy↗
PubMed1999

[Experimental study of ta chengchi tang decoction for relieving lung injury during acute necrotizing pancreatitis].

The objectives of the study were to investigate the changes of leukocyte adhesiveness and tumor necrosis factor (TNF) in the early stage of acute necrotizing pancreatitis (ANP), to go further into the relation of those changes to lung injury of ANP, and to evaluate the prohibitive effect of ta chengchi tang Decoction on leukocyte adhesion and TNF secretion. 14 canines were randomly divided into 3 groups. The treatment group (n = 5): experimental ANP model treated with ta chengchi tang Decoction; the saline control group (n = 5): experimental ANP model treated with normal saline; and the sham operative group (n = 4). The adhesion of leukocytes to vascular endothelial cells and TNF activities in serum and in bronchi-alveolar lavage fluid (BALF) were observed and measured, and the degrees of lung injury were assessed. The results showed that the adhesiveness of leukocytes was markedly increased and the activities of TNF were elevated in peripheral blood and BALF during ANP; that the leukocyte adhesiveness in the treatment group was weaker than that in the saline group (P < 0.05) and the serum and BALF TNF activities were also significantly lower than those in the saline group (P < 0.01); and that the degrees of lung injury in the treatment group were significantly milder than those in the saline group. These indicate that the increased leukocyte adhesiveness and hypersecretion of TNF take part in the pathogenesis of lung injury in ANP, and ta chengchi tang Decoction is demonstrated an efficacious medicine for alleviating the degree of lung injury mediated by both the leukocyte adhesion and TNF in ANP.

Animals↗
PubMed1999

[Immunophenotyping in myelodysplastic syndromes].

OBJECTIVE: To evaluate the values of immunophenotyping in the diagnosis and prognosis of myelodysplastic syndromes (MDS). METHODS: Surface markers of mononuclear marrow cells were analyzed by indirect immunofluorescence for a panel of monoclonal antibodies in 32 patients with MDS. RESULTS: Expression of myeloid antigen increased significantly while lymphoid antigen decreased. The antigen expression was correlated with the FAB subtype of MDS, Immature myeloid cells (CD13+, CD33+) was being increased and the lymphoid antigen expression decreased with the RA/RAS evolving to RAEB and RAEB-t. Compared with normal marrow, the number of CD34+ cells was not significantly different in RA/RAS subtypes but significantly higher in RAEB/RAEB-t subtypes. The expression of early marrow cell antigens (CD38, HLA-DR, CD99R and CD9) was significantly increased. The expression of CD34 and other early antigen was predictive for transformation and poor survival. CONCLUSION: Surface marker analysis of mononuclear marrow cells may be a useful tool for the diagnosis and prognosis of MDS.

Adult↗
PubMed1999

[Effect of electroacupuncture and 7-NI on penicillin-induced epilepsy and their relation with intrahippocampal NO changes].

In order to investigate the effect of 7-nitroindazole (7-NI) on penicillin-induced epilepsy and the relationship between NO and anti-epileptic effect of electro-acupuncture, computerized physiological polygraph and NO-sensitive electrode with potentiostat were respectively used to record the total power spectrum (TPS) of EEG and the concentration of NO in rat hippocampus pretreated with electro-acupuncture or 7-NI for 30 min before penicillin. The results showed that the TPS of EEG and concentration of NO in hippocampus increased greatly after the epilepsy induction. Treatment with electroacupuncture inhibited the TPS of EEG sharply (P < 0.01). The latency and threshold of epilepsy induction were decreased by 7-NI, but paroxysm abated and the TPS was inhibited (P < 0.05) as compared with the control group. Both pretreatments with 7-NI and electroacupuncture decreased the NO concentration (P < 0.01). The above results suggest that the propagation of penicillin-induced seizures is facilitated by nNOS, but with some increase in the latency and threshold of induction. Electroacupunture may inhibit seizure through decreasing nNOS transcription in hippocampus.

Animals↗
PubMed1999

[The effect of the molecular triggers of hemostatic activity on thrombosis in early stage of electrical injuries].

OBJECTIVE: To evaluate the mechanisms of thrombosis in the early stage of electrical injury. METHODS: Endothelin-1(ET-1), prostacylin(PGI2), platelet alpha-granule membrane protein (Gmp-140), thromboxane (TXB2), and plasminogen(PLG-A) were measured in 26 patients with electrical injury. RESULTS: It was found that GMP-140 and ET-1 increased significantly(P < 0.01), PLG-A showed a significant change 2 weeks after the injury, while there was an imbalance between TXB2 and PGI2. CONCLUSION: It is believed that change in one or several mediators mentioned above may trigger thrombosis after electrical injury.

Adolescent↗
PubMed1999

Clinicopathologic, immunophenotypic and ultrastructrual analyses of ATLL patients with cutaneous involvement.

OBJECTIVE: To study 4 cases of adult T-cell leukemia/lymphoma (ATLL) associated with cutaneous lesions for clinicopathology, immunophenotype, human T-cell leukemia/lymphoma virus type I (HTLV-I) provirus DNA and their ultrastructure. At the same time, HTLV-I provirus DNA of ATLL patients were also compared with 18 cases of cutaneous lymphoma (CL), two cases of actinic reticuloid as well as two cases of lymphocytic infiltration. METHODS: Immunohistochemistry studies were carried out on the infiltrating cells using monoclonal antibodies against CD45-RO, CD20, CD68 on paraffin-embedded sections by ABC method and using monoclonal antibodies against CD3, CD4 and CD8 with indirect immunofluorescence (IIF) on frozen sections. Skin biopsies were examined by electron microscope. Serum and bone marrow cells were tested for antibodies against HTLV-I-associated antigen by IIF, and HTLV-I provirus DNA was examined by PCR method. RESULTS: The research showed four patients with ATLL manifesting cutaneous lesions, were subsequently found with additional systemic symptoms, as extensively enlarged superficial lymph node, abnormal increased IL-2 receptor, flower-like cells in their peripheral blood and marrow. The HTLV-I provirus DNA was positive in the peripheral blood, bone marrow, cutaneous lesions and lymph node biopsy specimens by using PCR amplification of specific HTLV-I fragment while 18 cases of the CL were negative for HTLV-I. The special ultrastructure of skin lesions was also found in ATLL patients. CONCLUSIONS: The cutaneous involvement in ATLL is a type of cutaneous T cell lymphoma (CTCL) but shows some differential immunological markers for differential diagnosis. The examination of HTLV-I antibodies or HTLV-I provirus DNA is necessary for diagnosis of ATLL. The ultrastructural characteristics in skin lesions of ATLL were of atypical lymphocytes and mononuclear cells invading the epidermis, and the mononuclear cells are possessing the phagocytic function and phagocytizing the degenerated epidermic cells or lymphocytes.

Aged↗
PubMed1999

Augmentation of antitumor effect of adenovirus-mediated CD suicide gene therapy by cotransfer of interleukin 2 gene in melanoma-bearing mice.

OBJECTIVE: To investigate the antitumor effect of combined adenovirus encoding E. coli cytosine deaminase (AdCD) and adenovirus encoding murine interleukin 2 (AdIL-2) on murine melanoma. METHODS: C57BL/6 mice were inoculated s.c. with B16F10 melanoma cells and 3 days later received injections of AdCD and/or AdIL-2 at the site of tumor inoculation followed by administration of 5-flurocytosine (5FC) 300 mg/kg per day for 10 days. RESULTS: Mice receiving AdCD/5FC/AdIL2 therapy developed tumors more slowly and survived much longer when compared with mice treated with AdCD/5FC, AdIL2, AdlacZ/5FC, or PBS. Immunological analysis illustrated that combined treatment could enhance NK activity and CTL activity. Flow cytometry demonstrated that AdCD/5FC/AdIL2 therapy increased the expression of MHC-1 and CD80 molecules on freshly isolated tumor cells. The CD4+ and CD8+ T cell infiltration in the tumor increased significantly after the combined therapy. CONCLUSIONS: Our data showed that combined transfer of CD suicide gene and IL-2 gene could inhibit the tumor growth more significantly. The increased specific and non-specific antitumor immunity might be responsible for the enhanced therapeutic effect.

Adenoviruses, Human↗
PubMed1999

[Study on the expression of myeloid markers and CD34 antigen in adult acute lymphoblastic leukemia].

OBJECTIVE: To analyse the expression of myeloid markers and CD34 antigen on lymphoblasts in adult ALL and its relationship with prognosis. METHOD: Immunophenotypes were examined using indirect immunofluorescence method in 102 de novo ALL. RESULTS: The incidence of myeloid antigen expression in adult ALL was 21.6% and the commonest one was CD33 (15.7%). There was a higher incidence of myeloid antigens expression in ALL-L2 than in ALL-L1 (25.6% vs 5.3%, P = 0.05). CD34 was expressed in lymphoblasts from 30 of 56 patients (53.6%). Incidence of CD34 expression in B-ALL was higher than that in T-ALL (61.7% vs 11.1%, P < 0.01). No relationship between CD34, myeloid antigens and cell maturity was found within B-ALL. There was no relation between expression of myeloid antigens and CD34. The CR rate in My(+)-ALL was lower than that in My(-)-ALL (52.6% vs 80.0%, P < 0.025), and was no relation with CD34 expression. In addition, Ph chromosome and/or bcr/abl fusion gene was positive in 35.9% of the patients, and CR rate of Ph positive patients was higher than that in Ph negative patients. CONCLUSION: Expression of myeloid antigens was related to FAB subtype and cell maturity in adult ALL. There was no relationship between myeloid antigen expression and CR rate. A higher incidence of CD34 expression was found in Pro-B-ALL than in common-ALL and Pre-B-ALL. Expression of CD34 had no relation with CR rate.

Adolescent↗
PubMed1999

Effect of WT1 gene expression on cell growth and proliferation in myeloid leukemia cell lines.

OBJECTIVE: To investigate the effects and mechanism of Wilms' tumor (WT1) antisense oligonucleotides (AS-oligomers) on proliferation and apoptosis in myeloid leukemia cell lines. METHODS: K562 and HL-60 cells were cultured in presence of WT1 oligomers. Both cell lines express WT1 gene with no p53 protein expression. Cells growth, apoptosis and expression of WT1, bcl-2 genes were analysed using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenylmetrazolium bromide (MTT) colorimetric assay, flow cytometry and reverse transcription-polymerase chain reaction (RT-PCR) methods. RESULTS: WT1 antisense oligonucleotides inhibited cellular proliferation of K562 cells and the effect was concentration-dependent. When cultured at concentration of 200 micrograms/ml oligomers, growth inhibition was 46.2% for antisense oligonucleotide cultivated group and 28.1% for sense oligonucleotide cultured group (P = 0.008) respectively. WT1 antisense oligonucleotide can induce apoptosis of K562 and HL-60 cells. Percentages of apoptotic cells in antisense oligonucleotide and sense oligonucleotide treated groups were 30.88% versus 13.62% for K562 cells and 40.15% versus 4.23% for HL-60 cells. However the growth of HL-60 cells and expression of bcl-2 gene were unaffected. CONCLUSIONS: The WT1 gene is related with proliferation and apoptosis of leukemic cells. Effect of anti-apoptosis may be independent of the cellular p53 status and bcl-2 expression. WT1 gene may play an important role in leukemogenesis.

Apoptosis↗
PubMed1999

cDNA cloning and sequence analysis of hepatitis G virus genome isolated from a Chinese blood donor.

OBJECTIVE: To obtain full-length sequence of a Chinese hepatitis G virus (HGV) strain (HGVch) and investigate the genetic characteristic of HGVch and its identity to other isolates. METHODS: Reverse transcription (RT) and nested-PCR were used to screen HGV RNA positive serum and amplify cDNA fragments. A positive serum without known hepatitis virus markers was selected for isolating HGV RNA template. The HGV genome was divided into 12 overlapping fragments and directly cloned into pGEM-T vector. Sequences were determined by dideoxy terminus-end method of DNA sequencing and then analyzed by computer. RESULTS: The twelve fragments of HGVch cover 9213 nucleotides in length, containing a large open reading frame (ORF) encoding 2873 animo acids polyprotein that began with a methonine residue and ended at termination codon. HGVch is about 86.5%-89.5% identical to other known HGV isolates at the nucleotide level and about 93.9%-96.2% at the deduced animo acid level. CONCLUSION: HGV is a non-A-E hepatitis causal agent, proved to be related with posttransfusion hepatitis in all over the world. Chinese HGV isolate has very close relationship to other isolates from Africa, Europe, Japan, without significant difference across the entire genome. It is suggested that the sequences of HGV isolates are very conservative and the evolution is very slow.

Blood Donors↗
PubMed1999

[The mechanisms of arsenic trioxide-induced apoptosis in hematopoietic malignant cells].

OBJECTIVE: To understand if arsenic trioxide (As2O3) is related to the alteration of mitochondrial transmembrane potentials (delta psi m) and its possible mechanisms. METHODS: Acute promyelocytic leukemia (APL) cell line NB4, chronic lymphoblastic leukemia (CLL) cell line SKW-3, Burkitt's lymphoma cell line Namalwa and other acute myeloid leukemia cell lines HL-60 and U937 were used as in vitro models. The delta psi m was detected by the double staining of propidium iodide (PI) and Rhodamine 123(Rh123), while apoptosis was confirmed by cell viability, sub-G1 cell content as well as gel electrophoresis of genomic DNA and morphological observation. In addition, cellular content of malondialdehyde (MDA) was detected. RESULTS: In the cells sensitive to As2O3-induced apoptosis, the delta psi m was disrupted with As2O3 treatment. The disulfide-bond reducing agent dithiothreitol (DTT) significantly blocked As2O3-induced delta psi m collapse and apoptosis. For example, with 1 mumol/L As2O3 treatment for 48 hours, PI- Rh123- cells was increased to (16.0 +/- 2.5)%, and DTT simultaneous treatment reduced PI- Rh123- cells and apoptotic cells to (2.9 +/- 0.2)%, and (1.8 +/- 0.3)%, respectively. On the other hand, As2O3 also significantly induced MDA production in NB4(0.479 +/- 0.044, P < 0.01) and SKW-3 (0.168 +/- 0.018) nmol/L, P < 0.01) cells, whereas the effect could not be blocked by DTT. CONCLUSIONS: The disruption of the delta psi m is the key event of As2O3-induced apoptosis, and the essential mechanisms may be related to the oxidation of thiols; the reactive oxygen species are involved with apoptosis induced by As2O3, but they are not the main points.

Apoptosis↗
PubMed1999

Subclasses of warm autoantibody IgG in patients with autoimmune hemolytic anemia and their clinical implications.

OBJECTIVE: To explore the mechanism of autoimmune hemolysis and establish a more sensitive test for autoimmune hemolytic anemia (AIHA). METHODS: IgG subclasses were tested in 40 patients with idiopathic or secondary AIHA by Coombs test with monoclonal antibodies. Hb, TBil, RC and FHb, as hemolytic parameters, were used to analyze the clinical implications of subclasses of AIHA warm autoantibody IgG. RESULTS: In most patients IgG incomplete warm autoantibody was IgG1 (27 patients), but IgG3 (20 patients), rarely IgG2 (14 patients) and IgG4 (9 patients) also occurred. Three groups were analyzed: Group A included 20 patients with IgG3; Group B included 14 patients with IgG1 bit without IgG3; Group C included 6 patients without IgG1 and IgG3. There were significant differences (P < 0.01) between groups in Hb, TBil, RC and FHb. Moreover, we also found that the sensitivity of Coombs test with polyclonal antiserums was 90.0%, while that of Coombs test with monoclonal antibodies was 97.5%. The effect of treatment was worst in patients with positive IgG3 autoantibody, whose hemolysis recurred frequently. CONCLUSION: IgG3 autoantibody was the most effective in bringing about red cell destruction, IgG1 autoantibody was less effective, IgG2 even less, whereas IgG4 autoantibody was shown to hardly affect red cell survival. Coombs test with monoclonal antibodies was more sensitive than that with polyclonal antiserums. Patients' respondence to treatment correlated with the type of IgG subclasses.

Adult↗
PubMed1999

Epstein-Barr virus infection in nasopharyngeal lymphoid hyperplasia.

OBJECTIVE: To detect whether Epstein-Barr virus (EBV) harbors in nasopharyngeal lymphoid hyperplasia (NPLH) which is frequently to be seen in Guangzhou, a high-incidence area of nasopharyngeal carcinoma (NPC), and to explore the relation between NPLH and development of NPC. METHODS: Twenty-four 10% formalin-fixed, paraffin-embedded biopsies oef patients with NPLH and elevated serum IgA antibody titer (> or = 1:20) against viral capsid antigen of EB virus (IgA/VCA) were collected from the archives of the Department of Pathology, Sun Yat-sen University of Medical Sciences during the period of January to June, 1993. PCR plus Southern blotting hybridization for detection of EBV DNA W-fragment and in situ hybridization for detection of EB virus encoded small RNAs (EBERs) were performed. All the patients were followed up more than 5 years. RESULTS: Twenty-two of 24 (91.7%) NPLH tissues contained EBV DNA. A few definitely EBERs positive B-lymphocytes could be found in 17 out of 24 specimens (70.8%). Neither NPC nor any EBV-associated malignancies were developed in all of these 24 patients up to date. CONCLUSION: Most of the NPLH tissues taken from the patients with an elevated serum IgA/VCA titer carry EBV, which is harbouring in the nuclei of a few infiltrating and hyperplastic B-lymphocytes. The NPLH without epithelial dysplasia can not be recognized as a precancerous lesion, and EBV infection in these lesions is not an important event, having no substantial significance in development of NPC.

Capsid↗