Biomedical subjects

G Chen

Publications and source records attributed to G Chen.

At least 577 records · Page 32Linked to original sources

PubMed1997

[The design and application of a computer aided system for measuring the electroencephalographic effect].

A new computer system (including hardware and software design) was developed which could be used to record and analyze the electroencephalographic (EEG) signal. The EEG analog signal of four channels was first digitized at a sampling rate of 960 Hz through analog to digital converter and then stored in the Sun-386 computer for off-line analysis. Various EEG effect parameters were then generated from the aperiodic waveform analysis files, i.e., total number of waves/s and total voltage/s in various frequency ranges 1-3, 4-7, 4-11, and 12-30 Hz. From various EEG parameters derived from computer system, the total number or voltage in 12-30 Hz (TNW12-30, TV12-30) was considered as the best descriptor of EEG effect.

Anti-Anxiety Agents↗

PubMed1997

[Preliminary determination of the properties of HX-I refractory die material].

The setting time, the setting expansion ratio and the compatibility with impression materials of the HX-I refractory die material were determined. The results showed: the setting time was 11 +/- 3 min: the setting expansion ratio was 0.23%; the compatibility with impression materials was excellent between HX-I die material and agar or silicone rubber respectively, but the compatibility was bad between HX-I die material and alginate. These properties of HX-I die material were close to the ones of Lamina die material.

Dental Materials↗

PubMed1997

[Anti-virus effect of hepatocyte stimulating substance (HSS) on duck hepatitis B virus in vivo].

We used one day old Beijing ducklings infected by duck hepatitis B virus as experimental model to observe anti-virus effect of HSS. Beijing ducklings hatched within one day were injected intravenously with duck hepatitis B virus (DHBV). Positive DHBV-DNA in ducklings' sera were detected 7 days later. Serum samples were obtained from all ducklings before, during and after drug treatment at different times and stored at -70 degrees C. The collected samples were detected DHBV-DNA by dot-blot hybridization test at the same time. The therapeutic effects were evaluated by OD value of dot-blot and by the inhibitory rate of DHBV-DNA. The results showed that HSS (with 50 mg/kg/day and 200 mg/kg/day) were effective in inhibition of DHBV-DNA during and after drug treatment, especially in the HSS group of large dosage. The inhibitory effect appeared early and high dynamic. The inhibitory rate of DHBV-DNA during and after drug treatment were higher than the NS group (P < 0.05). No inhibitory effect was observed in NS group. The hepatic biopsy showed HSS groups had milder damage than NS group, indicating that the HSS could inhibit the replication of DHBV-DNA in Beijing ducklings.

Animals↗

PubMed1997

[Serological survey of human T lymphotropic virus type I (HTLV-1) IgG antibody in south region of Xinjiang].

Human T lymphotropic virus type-1 (HTLV-1) is endemic in southwestern Japan, Seychelles Islands, Caribbean basin, Brazil, and Sub Saharan Africa. Recently, the prevalence of HTLV-1 of domestic source has been reported from Beijing, Fujian and so forth. The object of our study is to know whether the prevalence of HTLV-1 is present in Xinjiang. We collected 2642 serm samples of various ages and different nationalities (Uigur, Han and Khalkhas) from south region of Xinjiang and tested for determination of HTLV-1 IgG antibody by IFA. The results showed that the total positive rate of HTLV-1 IgG was 0.34% (9/2642), of which Uigur nationality was 0.74% (8/1082), Khalkhas nationality was 0.21 (1/471), Han nationality was zero (0/1089). This data indicated that there are HTLV-1 infection among the population of Xinjiang and especially in Uigur and Khalkhas. Why did the minority nationalities have relatively high frequency of HTLV-1 infection? This needs to be studied further.

Adolescent↗

PubMed1997

[Core protein of hepatitis C virus expressed in transgenic mice is associated with the expression of Fas molecule].

Hepatitis C virus (HCV) is a leading cause of morbidity and mortality worldwide but the pathogenesis of liver cell injury and the molecular mechanism of persistent infection of HCV are not well understood. The aim of this work is to establish the animal model of HCV infection for studying the biosynthesis and pathogenesis of HCV structural protein in transgenic mice. The structural genes (C+ E1 + E2) and 5'-uncoding region gene (5'UCR) of HCV isolated from China was inserted into pcDNA3 vector. The transgenic mice were produced by microinfecting this plasmid into mouse (C57BL/6 x ICR) embryos and the integrated mice were identified. The expression of core protein of HCV and mFas molecule were confirmed by immunohistochemical analysis using monoclonal antibody. The results revealed that the expression of core protein was detected in many mouses' tissues with nuclear staining, while the heart tissue was with cytoplasmic staining. The expression level in tissues was indicated as: heart>lung>kidney>liver. At meantime, Fas molecule was detected in heart, kidney and liver tissues, and the expression of Fas was parallel to that of core protein. Transgenic mouse containing HCV structural gene was established and the expression of Fas molecule may be associated with the expression of core protein of HCV. The Fas system or other signaling pathway to the programmed cell death may play important roles in HCV infection. Our transgenic mouse will provide a useful animal model to critically address issues of immune pathogenesis, direct cytopathic potential and carcinogenesis of the structural protein of HCV.

Animals↗

PubMed1997

[The status and significance of mother-to-infant transmission of hepatitis C virus determined by nested polymerase chain reaction].

The antibodies to hepatitis C virus (HCV) and HCV RNA in sera from 11 mothers and their children born after 9-13 months were detected by several tests. It was shown that the positive rate of anti-HCV in infants was significantly lower by ELISA based on synthetic peptides (23.52%) than by second generation ELISA with recombinant antigens (2nd ELISA) (41.18%) (P<0.05). At birth, six babies were positive for anti-HCV in cord blood and venous blood by 2nd ELISA. Among them, serum anti-HCV disappeared in 5 cases after 1 to 5 months but was persistently detected in one cases. The anti-HCV positive sera from these six babies were tested by recombinant immunoblot assay (RIBA) and shown to be positive in 4 cases and indeterminate in 2 cases. By reverse-transcription polymerase chain reaction (RT-PCR), HCV RNA was found in 5 babies, three of them became negative 1-5 months after birth, two babies were positive with HCV RNA for 9 months and 13 months respectively. These findings suggested that the evaluation of the status of mother-to-infant transmission was limited by the low level of serum anti-HCV in infants, "passive transfer" of anti-HCV from mothers and different method of tests used. HCV RNA detection by RT-PCR is a more reliable marker to demonstrate the mother-to-infant transmission of HCV.

Enzyme-Linked Immunosorbent Assay↗

PubMed1997

[A seroepidemiological survey: antibody to HTLV-1 in sera from various populations in Guangdong Province].

A seroepidemiological survey of HTLV-1 infection in Guangdong Province was reported. 2224 serum samples from various populations were collected and antibodies to HTLV-1 in sera were detected with indirect immunofluorescent assay. Total seropositive rate was 1.57% (35/2224). The antibody positive rates of HTLV-1 in sera from healthy individuals (n = 1810), blood donors (n = 248), patients with T cell leukemia (n = 109) and patients with neurological diseases (n = 57) were 1.27%, 0.40 %, 7.30% and 5.26% respectively. There was a significant difference between the patients with T cell leukemia and the healthy individuals (P<0.005).

Antibodies, Viral↗

PubMed1997

[Preliminary study on the arsenic trioxide-induced NB4 cell apoptosis and its molecular mechanisms].

OBJECTIVE: To illustrate the possible cellular and molecular mechanisms of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia (APL). METHODS: APL cell line NB4 was used for in vitro studies. The effect of As2O3 on APL was studied by using flow cytometry, DNA electrophoresis, Narthern blotting and Western blotting. RESULTS: As2O3 induced NB4 cell apoptosis, while not inhibiting the growth and survival of two other leukemic cell lines (HL-60 and U937). Furthermore, As2O3 effectively down-regulated the expression of bcl-2 gene without changing the mRNA levels of other apoptosis-associated genes (including p53, c-myc, bax and bcl-XL). CONCLUSION: These might be one of the molecular mechanisms of As2O3 induced NB4 cell apoptosis.

Animals↗

PubMed1997

[Effects of arsenic trioxide on the subcellular localization of PML/PML-RARalpha protein in leukemic cells].

OBJECTIVE: In order to illustrate the possible roles of PML-RARalpha protein in arsenic trioxide (AsO3)-induced NB4 cell apoptosis. METHODS: Effects of As2O3 on the subcellular localization of PML-RARalpha in NB4 cells were studied. RESULTS: (1) Anti-PML serum staining was reduced and PML granules emerged in the perinuclear cytoplasm in a diffuse pattern in HL-60 cells under As2O3 treatment; (2) abnormal PML/PML-RARalpha granules were decreased; (3) NB4 cells accumulated anti-PML serum staining granules in the cytoplasms were increased and similar accumulation also found in apoptotic cells; and (4) pretreatment with all-trans retinoic acid (ATRA) for 24 or 48 hours did not alter the As2O3 effects. CONCLUSION: As2O3-induced apoptosis was independent of the retinoic acid signal pathway, and it might be regulated by PML/PML-RARalpha and/or other related genes.

Antineoplastic Agents↗

PubMed1997

[Pharmacokinetics of intravenous arsenic trioxide in the treatment of acute promyelocytic leukemia].

OBJECTIVE: In order to study the pharmacokinetics and metabolism of arsenic trioxide (As22O3), and its major side effects. METHODS: The clinical pharmacokinetics of intravenous As2O3 in 8 relapsed acute promyelocytic leukemia (APL) patients were studied by Gas-phase chromotography. RESULTS: (1) After 2 hour intravenous drips of 10mg As2O3, drug plasma maximal concentration (Cpmax) was 0.94 +/- 0.37mg/L(x +/- s), time to peak concentration (Tp) was 4hrs, T1/2 alpha and T1/2beta were 0.89 +/- 0.29hrs and 12.13 +/- 3.31hrs, respectively, apparent volume of distribution (Vc) was 3.83 +/- 0.45L, system clearance (CLs) was 1.43 +/- 0.17L/h and area under curve (AUC) was 7.25 +/- 0.97mg x h/L. Importantly, the continuous administration of As2O3 did not alter the pharmacokinetic behaviors. (2) During As2O3 therapy, 24-hour arsenic content in urine accounted for 1%-8% of the total dose (10mg) per day. And it decreased gradually after drug withdrawal. (3) Arsenic contents in nail and hair were increased continuously during As2O3 therapy. The peak concentrations could be five to seven-fold higher than that pre-treatment. It also decreased gradually after drug with drawal. CONCLUSION: As2O3 is a relatively safe and effective drug in the treatment of APL patients, in spite of certain accumulation in some tissues.

Adolescent↗

PubMed1997

[Correlation between the serum levels of interleukin-2 and soluble interleukin-2 receptor and the response to immunosuppressive therapy in severe aplastic anemia patients].

OBJECTIVE: To explore factors influencing the effectiveness of immunosuppressive therapy in severe aplastic anemia (SAA). METHODS: The serum levels of interleukin-2 (IL-2) and soluble IL-2 receptor (sIL-2R) of 22 SAA patients and 15 normal controls were measured by immunoenzyme assay. RESULTS: Comparing with the normal controls, 40.9% and 63.6% of the SAA patients had higher serum levels of IL-2 (>840ng/L) and of sIL 2R (>320 x 10(3) U/L), respectively. Those who had higher IL-2 levels and higher sIL-2R levels got better responses to cyclosporin A(CsA) and CsA plus antilymphocyte globulin (ALG). CONCLUSION: The serum levels of IL-2 and sIL-2R were correlated with the responsiveness to immunosuppressive therapy in SAA patients and might be useful for directing treatment.

Adolescent↗

PubMed1997

[HLA-DR-positive T lymphocytes in the bone marrow and peripheral blood of patients with severe aplastic anemia and their in vitro inhibitory effecton BFU-E and CFU-GM].

OBJECTIVE: [corrected] To elucidate the role of immunodysfunction in the pathogenesis of severe aplastic anemia (SAA). METHODS: HLA-DR+ T cells were detected in bone marrow (BM) and peripheral blood (PB) of 20 SAA patients and controls (9 for BM and 11 for PB). PHA-LYCM conditioned medium was prepared, and its in vitro effect on normal bone marrow BFU-E and CFU-GM was studied. RESULTS: The percentages of HLA-DR+ T lymphocytes in BM and PB of newly diagnosed SAA patients were significantly higher than that of controls (P<0.001), and that of recovered SAA (rSAA) patients after ALG therapy (P<0.05). Compared with controls, the PBA-LYCMs from newly diagnosed SAA patients showed significant inhibitory effect on normal BFU-E and CFU-GM (P<0.001). CONCLUSION: The activated T lymphocyte may play an important role in the pathogenesis of SAA.

Adolescent↗

PubMed1997

[Immunophenotyping study on the blood cells of the patients with paroxysmal nocturnal hemoglobinuria].

OBJECTIVE: To detect the expression of glycosyl-phosphatidyl-inositol (GPI) anchored protein on the blood cell membrane and its implication in the diagnosis of paroxysmal nocturnal hemoglobinuria (PNH). METHODS: The GPI anchored protein was detected by indirect immunofluorescence method with a panel of monoclonal antibodies (CD55, CD59, CD16, CD58, HIR2, CD15, CD2) in 22 PNH patients. RESULTS: The abnormal granulocytes and erythrocytes with deficient GPI anchored proteins were identified in all PNH patients whether the routine hemolysis tests for PNH, including Ham test and mCLST, were positive or negative. However, lymphocytes with PNH-defect were found in only 14 patients. CONCLUSION: GPI anchored protein assay provided sensitive and specific method for the diagnosis of PNH.

Adult↗

PubMed1997

[Study on the immunophenotype of myeloid cells in myelodysplastic syndromes and its clinical implications].

OBJECTIVE: To explore the immunophenotype of myeloid cells in myelodysplastic syndromes and its clinical implications. METHODS: A panel of monoclonal antibodies was used to detect CD13, CD33, CD15 and CD14 on the membrane surfaces of myeloid cells in the bone marrow from 51 patients with myelodysplastic syndromes (MDS), 21 with aplastic anemia (AA), 21 with paroxysmal nocturnal hemoglobinuria (PNH), and 15 normal subjects, by immunoenzymatic assay. The morphology and chromosome karyotype of bone marrow cells of MDS patients were also examined. RESULTS: CD14+ cells, CD13+ cells and CD33+ cells in the bone marrow were more in MDS patients than in normal controls, AA patients and PNH patients. CD15+ cells in the bone marrow were less in MDS patients than in normal controls. The percentages of CD14, CD13 and CD33 positive cells in the bone marrow of MDS patients were related to the percentage of myeloblast, the chromosomal aberrations and the response to treatment. CONCLUSION: There was an immunophenotypic misexpression of myeloid cells in MDS patients. Immunophenotype analysis of myeloid cells might be useful for the diagnosis and directing treatment in MDS patients.

Adolescent↗

PubMed1997

[Comparative study of two fusion retinoic acid receptor alpha in acute promyelocytic leukemia].

OBJECTIVE: To make a comparison of biological properties between PML-RARalpha and PLZF-RARalpha fusion proteins. METHODS: Receptor radioligand binding assay, receptor DNA binding assay and immunofluorescence methods were used. RESULTS AND CONCLUSION: PML-RARalpha and PLZF-RARalpha had similar ligand-binding affinities. Both could bind in vitro to retinoic acid response elements (RAREs) forming homodimers and to retinoic acid X receptor. However ,they differed in the relative binding affinities to different RAREs,the behavior of forming complex with RXR and the subcellular localization. More importantly, PML-RARalpha and PLZF-RARalpha could block different regulatory pathways mediated by PML or PLZF, through heterocomplex formation with wild-type PML or PLZF. The differences between PML-RARalpha and PLZF-RARalpha may in part explain the apparent resistance of APL with t(11;17) to differentiating effect of all-trans retinoic acid (ATRA).

DNA↗

PubMed1997

[Expression of CD45RA and CD45RO antigens and its implication in leukemias].

OBJECTIVE: To investigate the expression of CD45RA and CD45RO antigens in leukemias and its implication in the diagnosis and differential diagnosis of leukemias. METHODS: The expression of CD45 RA and CD45RO antigens and other markers on the surface of bone marrow or peripheral blood cells was investigated by indirect immunofluorescence in 104 cases of leukemias. Of them, 33 cases were ALL (23 of B-lineage ALL and 10 of T-ALL), 62 AML, and 9 B-CLL. RESULTS: Four patterns, CD45RA+/RO-, CD45 RA-/RO+, CD45RA+/RO+ and CD45RA-/RO-, were revealed. 87% of B-lineage ALL displayed CD45 RA+/RO-, 70% of T-ALL CD45RA-/RO+, and 78% of B-CLL CD45RA+/RO+, The frequency of the four patterns was 56% for CD45RA+/RO-, 18% for CD45RA-/RO+, 16% for CD45RA+/RO+ and 10% for CD45RA-/RO-, respectively in AML, and had no correlation with AML subtypes. CONCLUSION: CD45 isoform patterns could be served as supplementary tools for the differential diagnosis of B-lineage ALL, T-ALL and B-CLL.

Adolescent↗

PubMed1997

[In vitro study on arsenic trioxide-inducing apoptosis in primary acute promyelocytic leukemie cells].

OBJECTIVE: To illustrate mechanisms of arsenic trioxide(As2O3) in the treatment of acute promyelocytic leukemia (APL). METHODS: Cell-DNA content distribution, CD11b and CD33 antigens and nitroblue tetrazolium (NBT) reduction were evaluated in fresh APL cells from six APL patients treated in vitro with As2O3. RESULTS: As2O3 had double effects on the cells inducing apoptosis and inducing partial differentiation at higher and at lower drug concentrations, respectively. As2O3 (0.1 approximately 2.0 micromol/L) could rapidly modulate and degrade APL-specific marker molecule PML-RARalpha protein, which could play an important role in the effects of As2O3 on APL cells. CONCLUSION: As2O3 had double effects (induction of apoptosis and partial differentiation) on APL cells through the modulation and degradation of PML-RARalpha proteins.

Apoptosis↗

PubMed1997

[Colony formation of bone marrow hematopoietic progenitor cells in patients with severe aplastic anemia and its relation to the results of immunosuppressive therapy].

OBJECTIVE: To explore the defect of hematopoietic stem cell and analyze the relationship between the colony formation capacity of bone marrow hematopoietic progenitor cells and the results of immunosuppressive therapy (IST) in severe aplastic anemia (SAA) patients. METHODS: Methylcellulose semisolid culture was used. RESULTS: Thirty patients with SAA at diagnosis were studied. In 90% of the patients, the CFU-E and CFU-GM yields were strikingly decreased and in 56.7% of the patients there was no colony formation at all. Nevertheless, there was still 10% of the patients having normal CFU-E, BFU-E or/ and CFU-GM yields. After IST, 59.1% of the patients showed colony formation improvement. The difference between the results obtained pre- and post-IST(for CFU-E and BFU-E, P < 0.01, for CFU-GM, P < 0.05) was significant. In the majority of the patients, the colony formation capacities were still under the normal post-IST. Moreover, 22.7% of the patients remained no colony formation post-IST. The IST response rates between the patients with or without colony formation had no statistically difference (80% versus 50%, P < 0.05). The increment of colony formation appeared later than the therapeutic effect did, but frequently concurred with the appearance of magkaryocytes in the bone marrow smear. CONCLUSION: In the majority of SAA patients, the hematopoietic stem cells or progenitors were defective perhaps caused by immune damage; IST can improve the hematopoiesis in vitro and in vivo of SAA patients.

Adolescent↗