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Biomedical subjects

G Chen

Publications and source records attributed to G Chen.

At least 325 records · Page 18Linked to original sources
PubMed2000

[Study on clinical and laboratory features of preleukemia patients].

OBJECTIVE: To explore prospective diagnostic criteria for preleukemia. METHODS: A case control study of the discrepancies of clinical and laboratory features between patients with preleukemia and those with chronic aplastic anemia (CAA) or atypical paroxysmal nocturnal hemoglubinuria (a-PNH). RESULTS: There were eight variables of significance: (1) lymphocytoid micromegakaryocytes in marrow; (2) immature granulocytes in peripheral blood; (3) >or= 2% myeloblasts in marrow; (4) positive periodic acid schiff (PAS) staining of nucleated erythrocytes; (5) myeloid differentiation index >or= 1.8; (6) clonal karyotypic abnormalities; (7) negative sister chromatid differentiation; (8) > 4.0 cluster/colony ratio of granulocyte-macrophage colony-forming units (CFU-GM). The following criteria was assigned: A: To meet (1) and at least two of the other seven variables; B: To meet at least four of the eight variables. All of the patients with preleukemia met A or B and none of the patients with CAA or a-PNH did. CONCLUSION: Preleukemia is different from CAA or a-PNH. It has its own clinical and laboratory features, which may be useful for prospective diagnosis.

Adolescent↗
PubMed2000

[Study on the clinical characteristics of biphenotypic acute leukemia].

OBJECTIVE: To analyze the biological characteristics and the treatment outcome of adult biphenotypic acute leukemia. METHODS: Immunophenotypes were examined using indirect immunofluorescence method. Biphenotypic acute leukemia (BAL) was diagnosed according to EGIL scoring system. RESULTS: (1) The incidence of BAL in acute leukemia was 3.4%. Percentage for coexpression of B lymphoid and myeloid antigens was 68.4%, for T lymphoid and myeloid antigens 21.1%, for B, T lymphoid and myeloid antigens 10.5%. (2) CD(34) was expressed in 43.75% of the BAL cases. (3) Cytogenetic analysis revealed normal and abnormal karyotypes in 41.7% and 58.3% of the BAL cases, respectively. (4) Six of 19 patients achieved completed remission (CR), but the disease free survivals were all less than 6 months. Treatment outcomes were negatively related to the expression of CD(34) antigen and cytogenetic findings. The BAL patients were poorly responded to therapeutic regimens directed to AML. CONCLUSION: Coexpression of B/M antigens is the commonest subtype in BAL. BAL had a poor prognosis, especially treated with induction regimen directed to AML.

Acute Disease↗
PubMed2000

[Long-term expression of MHC-I gene in recipient mice].

OBJECTIVE: To explore the possibility of long-term expression of transferred MHC-I gene in recipient mice. METHODS: MHC-I gene of the donor mouse (C(57)BL/6) was transferred into the recipient (BALB/c) hematopoietic cells by retrovirus-mediated gene transfer technique, and the gene transferred cells were reinfused into the recipient mice. PCR, RT-PCR and FACS were used to assay the long-term expression of MHC-I gene in the recipient mice. RESULTS: The gene transferred mice hematopoietic cells and their G418-resistant CFU-GM were demonstrated to be able to express the MHC-I gene. The cells proliferation and differentiation had no change. The MHC-I gene could be expressed for a longer period in the recipient mice. CONCLUSION: This experiment makes ready for the further research on inducing transplantation tolerance through MHC-I gene transfer.

Animals↗
PubMed2000

[The regulation effects of growth factors on the procollagen gene expressions of human mandibular condylar cartilage cells].

OBJECTIVE: At the early stage of osteoarthrosis (OA) and joint damage, the cartilage cells proliferation increases dramatically, but this repair process is finally replaced by the progressive destruction of the cartilage. The reason, in accordance to the latest research, is the abnormal phenotype of the involved cartilage cell. This result suggests that the regulation of cartilage cell phenotype may be an effective way in the treatment of OA and other cartilage destructive diseases. In this study, the effects of transforming growth factor-beta(TGF-beta), insulin-like growth factor-I (IGF-I) and basic fibroblast growth factor (bFGF) on collagen expression of human mandibular condylar cartilage cells was investigated. METHODS: Chondrocytes were isolated from human fetus by enzymatic method. The second passage of the cells was used in this study. They were cultured in DMEM medium supplemented with 20% newborn calf serum (NCS). After the cells reached confluence, the medium was replaced by DMEM containing 0.4% NCS. Then the cells were exposed to different growth factors including IGF-I (10 ng/ml), TGF-beta (5 ng/ml) and bFGF (50 ng/ml). The steady state mRNA levels of different samples were examined by slot-blot hybridization. The results were analysed by Student t test. RESULTS: IGF-I had the least effects on the mRNA levels of three kinds of procollagen (type I, type II and type III). On the other hand, bFGF and TGF-beta could inhibit the expression of type II collagen by 0.352 and 0.685 times comparing with the control groups separately. TGF-beta increased type I collagen expression. Besides, bFGF and TGF-beta also increased the value of type I collagen/type II collagen. None of the three kinds of growth factors had obvious effects on the expression of type III collagen. CONCLUSION: IGF-I can maintain the chondrocyte differentiated phenotype, while TGF-beta and bFGF have inhibitory effects.

Cells, Cultured↗
PubMed2000

[Three-dimensional finite element stress analysis of supporting bone of mandibular posterior fixed bridge. Part III. Comparative analysis with stress of the cortical bone beneath different pontics of fixed bridge].

OBJECTIVE: To analysis stress of the cortical bone beneath different pontics of mandibular posterior fixed bridge by using three-dimentional finite element method. METHODS: According to the measured data, the characters of all components of fixed bridge and the supporting tissues, and the principals of finite element, the three-dimentional finite element model was developed on the basis of an adult mandible. The model consisted of 1363 nodes and 1134 elements after the fixed bridge was placed. Three different pontics were designed. Young's mudulus and Poisson's ratio were obtained from the literature for each type of tissue or materials in the model. The surfaces of pontic next to the mucosa beneath the pontic consisted of nine elements and the contact area were respectively reduced 1/3. It was assumed all materials in the model were homogeneous, isotropic and linearly elastic. One vertical load of 20 kg and one horizontal load of 20 kg were applied respectively on the occlusal surface of the abutments and the pontics of three different fixed bridge. Three-dimentional finite element stress analysis was used to calculate the epsilon max and the epsilon min of the cortical bone beneath pontics of fixed bridge. RESULTS: Under the vertical loading, the cortical bone beneath the pontics appeared compressive stresses, the stress values of the cortical bone beneath the pontics were respectively -0.211(-)-0.119 (epsilon max, kg/mm2), -0.355(-)-0.201 (epsilon min), -0.224(-)-0.125 (epsilon max), -0.375(-)-0.215 (epsilon min), -0.239(-)-0.133 (epsilon max), -0.395(-)-0.228 (epsilon min). Under the horizontal loading, the cortical bone beneath the pontics exhibited tensile stresses and compressive stresses. The stress values of the cortical bone beneath the pontics were respectively -0.004-0.283 (epsilon max, kg/mm2), -0.249(-)-0.009 (epsilon min), -0.0042-0.301 (epsilon max), -0.264(-)-0.0095 (epsilon min), -0.0045-0.322 (epsilon max), -0.281(-)-0.0101 (epsilon min). The stress in the cortical bone beneath the pontics increased when the area of contact was reduced, the stress values changed in 5%-7%, but the rules of stress distribution of three different pontics were similar. CONCLUSION: Stress values in the cortical bone beneath three pontics are small, and the change of stress in the cortical bone beneath the different pontics of mandibular posterior fixed bridge is small too.

Dental Abutments↗
PubMed2000

[Circadian rhythm changes of the levels of endogenous insulin in growing rat condylar cartilage after functional mandibular protrusion].

OBJECTIVE: In order to determine which time of the day is best to wear functional appliances in clinic, the author investigates the circadian rhythm of the level of endogenous Insulin in growing rat condylar cartilages and the changes after functional mandibular protrusion in daytime (8:00-20:00) or nighttime (20:00-8:00). METHODS: 72 4-week-old SD rats were divided equally and randomly into experimental and control groups, and the rats in experimental groups were put on the functional appliance in daytime (8:00-20:00) or nighttime (20:00-8:00). After 7 days, all rats were sacrificed at 0:00, 4:00, 8:00, 12:00, 16:00, 20:00 in a day. Radioimmunoassay methods were used to detect the levels of endogenous insulin in growing rat condylar cartilages. RESULTS: 1. The levels of endogenous insulin in the growing rat condylar cartilage displayed a significant circadian rhythm. The acrophase was about 12:13. 2. The circadian rhythm still existed after the rats had been put on the functional appliance. Both mesor and amplitude were significantly higher in the experimental groups than in the control group 3. The levels (both mesor and amplitude) of endogenous insulin in the condylar cartilage were significantly higher in the daytime-forced group than in the nighttime-forced group. CONCLUSION: 1. The growth and remodeling of the condylar cartilage in the growing rats shows significant circadian rhythm. The most active period of chordrocyte proliferation may occur during the daytime. 2. The circadian rhythm still exists after the rats have been put on the functional appliances. 3. Compared with nighttime appliance wearing, daytime appliance wearing may be more conductive to cell proliferation, so it may be more effective to stimulate the growth and remodeling of condylar cartilage in the growing rat. 4. Related to human beings, these data suggest that the best period for patients to wear the functional appliances might be from 20:00 pm to 8:00 am of the next day.

Animals↗
PubMed2000

[Purification of prothrombin in Nitschmann fraction III by membrane radial column ion-exchange liquid chromatography].

A method is described for the purification of human prothrombin complex concentrate (PCC) from Nitschmann fraction III by membrane radial column ion-exchange chromatography, which allows large sample volumes to be processed at low operation pressure. The Nitschmann fraction III (15 g) was mixed with 1,000 mL 0.06 mol/L Tris-HCl(pH 7.5). The centrifuged supernatant(10,000 r/min, 15 min, 20 degrees C) was applied onto a DEAE ion-exchange liquid chromatographic column(XK-16 DEAE fast flow Sepharose and DEAE membrane radical column chromatography) with almost the same excellent separation efficiency. The parameters of sample flow rate, elution flow rate and sample capacity were optimized.

Blood Coagulation Factors↗
PubMed2000

[Expression of c-fos mRNA following moderate lateral fluid percussion brain injury in rats].

This experiment was designed to study the expression of c-fos mRNA in brain following moderate lateral fluid percussion brain injury in rats and to observe the temporal pattern of its expressions following percussion. Male Sprague-Dawley rats were divided into normal control, sham operation control and injury groups. The rats of the injury group were subjected to moderate lateral fluid percussion injury (0.2 MPa). The injury group was then subdivided into 5 min, 15 min, 30 min, 1 h, 2 h groups according to the time elapsed after injury. The expression of c-fos mRNA was studied with reverse transcription polymerase chain reaction(RT-PCR) semi-quantitatively. c-fos mRNA in cortex and brain stem was expressed weakly in control groups. After 5 min of percussion, the expression of c-fos mRNA increased progressively and remained elevated up to 2 h after brain injury. This result suggested that the induction and expression of the c-fos mRNA in cortex and brain stem after fluid percussion brain injury were increased rapidly. The temporal pattern of induction in cortex was similar to that in brain stem.

Animals↗
PubMed2000

[Chaos in electroencephalogram].

The history and current situation of EEG study were reviewed in the paper, with an emphasis on the application and the latest developments of chaos in EEG analysis. The problems in present study and the proposals for future investigations were finally discussed.

Algorithms↗
PubMed2000

[Rat heart transplantation immune tolerance induced by blockade of B7-CD28 interaction].

OBJECTIVE: To study immune tolerance induced by blockade of B7-CD28 interaction after heart transplantation in rats. METHODS: A model of rat heterotopic heart allograft was established by using Ono's technique. CTLA-4-Ig was administered by intraperitoneal injection at dose of 100 micro. Survival times, histological changes, and the concentration of IL-2, IgG and IgM were measured after operation. RESULTS: Survival times were 31.60 +/- 1.82 days in experimental group and vs 7.25 +/- 0.71 days in control groups. In the experimental group, the graft survival time prolonged significantly (P < 0.01). Histological changes were characterized by mild scattered mononuclear infiltration and patchy myocyte injury in the experimental group (grade I - II). In the control group, the changes were characterized by severe lymphocyte infiltration, myocyte injury and necrosis, interstitial edema, and hemorrhage (grade IV). IL-2 was significantly decreased after operation (P < 0.01). IgG and IgM were not changed significantly in comparison with those in the control group (P > 0.05). CONCLUSION: The blockade B7-CD28 interaction can induce rat heterotopic heart allograft immune tolerance. It may provide a new way to treat immune rejection after transplantation.

Abatacept↗
PubMed2000

[A novel apoptotic related gene--homocysteine-induced gene HCY-2].

OBJECTIVE: To investigate the mechanisms resulting in cardiovascular diseases and birth defect. METHODS: Induced screening and differential display, Northern blot, and immunohistochemistry assay were applied to clone the homocysteine-induced gene HCY-2 and detect the expression of HCY-2 gene respectively. RESULTS: A novel HCY-induced full length cDNA--HCY-2 which encodes 142 amino acids was obtained from vascular smooth muscle cells of rats. Results of the Northern blot and immunohistochemistry assays suggest that it widely expresses in many kinds of tissues such as heart, kidney, brain, liver, and lung. In vitro, we transferred recombinant HCY-2 gene into endothelial cells and found that it could induce apoptosis and DNA injury. In vivo, HCY-2 gene could induce chicken embryo cells apoptosis and embryo malformation. CONCLUSIONS: The results indicated that HCY-2 gene might be a novel apoptosis-inducing gene and might be involved in the pathogenesis of cardiovascular diseases and birth defects induced by hyperhomocysteinemia.

Amino Acid Sequence↗
PubMed2000

Arginine vasopressin gene expression in supraoptic nucleus and paraventricular nucleus of hypothalamous following cerebral ischemia and reperfusion.

BACKGROUND: Our previous studies indicated that the increased arginine vasopressin (AVP) in ischemic brain regions of gerbils could exacerbate the ischemic brain edema. This experiments is further clarify the relation between AVP and cerebral ischemia at the molecular level. METHODS: The contents of AVP, AVP mRNA, AVP immunoreactive (ir) neurons in supraoptic nucleus(SON) and paraventricular nucleus (PVN) after cerebral ischemia and reperfusion were respectively determined by radioimmunoassay (RIA), immunocytochemistry (II C), situ hybridization and computed image pattern analysis. RESULTS: The contents of AVP in SON, PVN were increased, and the AVP ir positive neurons in SON and PVN were also significantly increased as compared with the controls after ischemia and reperfusion. And there were very light staining of AVP ir positive neurons in the other brain areas such as suprachiasmatic nucleus (SC) and periventricular hypothalamic nucleus (PE), but these have no significant changes as compared with the controls. During different periods of cerebral ischemia (30 approximately 120 min) and reperfusion (30 min), AVP mRNA expression in SON and PVN were more markedly increased than the controls. CONCLUSIONS: The transcription of AVP gene elevated, then promoting synthesis and release of AVP in SON, PVN. Under the specific condition of cerebral ischemia and reperfusion, the activity and contents of central AVP increased abnormally is one of the important factors which causes ischemia brain damage.

Animals↗
PubMed2000

[In-situ FTIR spectroscopic studies of electro oxidation of ethanol in alkaline media at a nm-Pt/GC electrode].

The electro-oxidation of ethanol on a nm-Pt/GC electrode in alkaline solutions was investigated by using cyclic Voltammetry and in-situ FTIR spectroscopy. The results demonstrated that the main product of ethanol oxidation was CH3COO-, only small quantity of CH3CHO was determined simultaneously. In contrast with the dual path reaction mechanism for the oxidation of ethanol in acid media, the oxidation of ethanol in alkaline media was revealed via the intermediate process of dissociative adsorption.

English Abstract↗
PubMed2000

[A new chemiluminescence immunoassay method for the determination of cancer embryo antigen].

A new chemiluminescent probe 10,10'-dimethyl-3,3'-disulfo-9,9'-biacridine DMDSBA) is used to label anti-CEA antibody, the molar incorporation is 1.15-1.32 mole of DMDSBA per mol anti-CEA; the conditions of labeling reaction, sandwich immunoassay and chemiluminescent reaction are studied. Moreover, a new double antibody sandwich chemiluminescence immunoassay is firstly established, the linear calibration ranges is 1.5-150.0 ng.mL-1 and the detection limit is 0.53 ng.mL-1. This method is used to detect cancer embryo antigen (CEA) in human serum, the results are well-matched with that of radio immunoassay.

Carcinoembryonic Antigen↗
PubMed2000

[In situ FTIR studies of CO adsorption on palladium loading zeolite electrode].

Adsorption of CO on palladium loading zeolite electrode supported on Pt or GC substrate was studied by in situ MSFTIR spectroscopy. The results demonstrated that the geometry of faujasite supercages favors the formation of bridge-bonded CO species. The enhanced IR adsorption of CO adsorbed on Pd clusters located in the supercages of zeolite has been observed for the first time, which is a new phenomenon and differs from the abnormal infrared effects discovered by our group and the surface enhanced infrared absorption phenomenon reported in the literature.

English Abstract↗
PubMed2000

[Study on mechanism of different PHAs during heating by FTIR].

In this paper, PHB, P(HO-co-HD), a various composition of P(HB-co-HV) copolymer and P(HB-co-HH) copolymer were studied both at normal temperature and in the process of increasing and decreasing temperature using FTIR spectroscopy technology. Results showed that FTIR spectra of PHAs with various compositions have distinguishing characteristics. Physical transformation occurred when PHAs were treated with heat denaturalization, and this physical process was reversible.

Bacteria↗