Biomedical subjects
Publications and source records attributed to Chun Wang.
Posttraumatic foreign bodies in the heart or great vessels is rare, which may cause cardiac tamponade, bleeding, shock, infection, embolism, arrhythmia, valve dysfunction, etc. The foreign bodies can be removed by surgery or percutaneous intervention. In this report we reviewed our experience in managing posttraumatic foreign bodies in 13 patients at our institution from 1992 to 2002.
The emergence of acquired drug resistance is a major hurdle in the successful treatment of leukemia. Researches indicated that the main mechanisms of most cancers included so-called "pump" and "nonpump" resistance. We studied the mechanisms involved in the drug resistance of HL-60/ADR and found that its drug resistance was associated with the simultaneous overexpression of XIAP and MRP. We compared the reversal effects of XIAP and MRP ASO used in combination and separately. Reverse transcription-PCR and Western blot were applied to examine the changes of mRNA and protein levels, respectively. The results showed that XIAP and MRP ASO used separately could down-regulate the expression of XIAP and MRP in HL-60/ADR cells, respectively. XIAP and MRP ASO used in combination did not enhance the inhibition expression of XIAP and MRP of HL-60/ADR cells. The apoptosis of co-transfection group was significantly higher than XIAP ASO (P<0.05). The cytotoxicity was determined by MTT cell viability/proliferation assay. When used in combination the sensitivity of HL-60/ADR cells to DNR was increased significantly compared with XIAP or MRP ASO used separately (P<0.05). The results indicated that both XIAP and MRP were involved in the drug resistance mechanisms of HL-60/ADR cells. The sensitivity to DNR could be enhanced significantly when XIAP and MRP ASO used in combination.
Apoptosis resistance is an important mechanisms of drug resistance mediated by bone marrow stromal cells (BMSCs). BMSCs influence tumor cells survival through several mechanisms including direct cell-cell contact and the effects of soluble factors. In this research we investigated the role of X-linked inhibitor of apoptosis protein (XIAP) in the apoptosis resistance mediated by stromal cells in HL-60 cells and the signaling pathway involved. We found that bone marrow stromal-derived soluble factors and direct cell contact both prevented apoptosis of HL-60 cells. XIAP is upregulated by direct cell contact but not by soluble factors. Phosphatidylinositol 3-kinase (PI3K) and Akt were activated and LY294002 downregulated XIAP and increased apoptosis in HL-60 cells co-cultured with BMSCs. The results indicated that PI3K/Akt/XIAP is an important pathway involved in the apoptosis resistance of HL-60 cells co-cultured with BMSCs by direct cell contact. Inhibition of this signaling pathway may provide a new therapeutic strategy for acute myeloid leukemia treatment.
PURPOSE: To test the post-critical period stability of perineuronal nets by comparing the expression of antigens on aggrecan (a chondroitin sulfate proteoglycan (CSPG) recognized by the monoclonal antibody Cat-301) in the lateral geniculate nucleus (LGN) and striate cortex (A17) of adult Y-blocked cats and cats made strabismic and amblyopic as kittens. The comparison tested the idea that pre- and post-critical period loss of synchronous activity would differentially affect the perineuronal net of Y-type neurons in LGN and A17. METHODS: Seven adult cats, two normal, three convergent strabismic amblyopic, and two monocularly Y-blocked cats, were used in this study. The strabismic amblyopic cats had been made monocularly esotropic (by tenotomy) at 14 days of age. The Y-block was created acutely by a pressure cuff placed on the optic nerve behind the left eye in adult cats. The efficacy of both procedures was tested electrophysiologically. Frontal frozen sections were incubated with the Cat-301 antibody and the labeling visualized using a DAB kit. The sections were counterstained with cresyl violet. In each section, Cat-301-stained cells with well-defined nucleoli were counted under a 20x objective with a computer-based quantitative microscope image analysis system. RESULTS: The percentage of positively labeled cells was reduced in LGN laminae that received input from the deviated eye in amblyopic cats and from the pressure-blocked eye in Y-blocked cats compared with normal cats. Surprisingly, the non-blocked laminae of the Y-blocked cats also showed a significant reduction in positively labeled neurons when compared to normals or to strabismic cats. In the visual cortex of both hemispheres of strabismic and Y-blocked cats, the density of immunopositive neurons was significantly reduced compared with normal. The effect was most pronounced in layers IV-VI for Y-blocked cats and in layer IV for strabismic amblyopic cats. CONCLUSIONS: The results demonstrate that surface expression of aggrecan in adult cat LGN and A17 of adult cat is reduced both by chronic developmental loss of synchronous input from the two eyes and by acute changes in synchronous input in adulthood. Thus both pre- and post-critical plasticity in the expression of epitopes of aggrecan can be demonstrated. The uniform distribution of Cat-301 labeling tangentially within cortical layers of strabismic amblyopic cats indicates that the reduction in immunoreactivity observed with strabismus induced early in life is not simply eye-specific. Indeed, comparison of the immunopositivity of Y-blocked and strabismic animals, both in LGN and cortex, suggests that even after the critical period is ended, the physical removal of monocular Y-type afferent activity and weakening of binocular feedback connections between cortex and thalamus can alter the stability of the perineuronal nets surrounding the affected neurons.
OBJECTIVE: To determine the potential effects of pioglitazone on beta-cell function in metabolic syndrome patients with impaired glucose tolerance and probe into the possible mechanisms. RESEARCH DESIGN AND METHODS: Twenty-two subjects were treated with pioglitazone 30 mg/day for 4 months. At baseline and after treatment, each subject underwent an IVGTT. The acute insulin response (AIRg), the glucose disappearance rates (coefficients K) and the ratio of Deltainsulin/Deltaglucose (DeltaI/DeltaG) were calculated according to IVGTT results. Hyperglycemic clamp study was conducted to determine the second-phase insulin response, insulin sensitivity index (ISI) and glucose infusion rate (GIR). Euglycemic-hyperinsulinemic clamp study was made to measure the glucose disposal rate (GDR). Plasma glucose, free fatty acids (FFAs), serum insulin and proinsulin levels were measured. RESULTS: AIRg unchanged (P = 0.25) after treatment, whereas the values of coefficients K (P < 0.01) and DeltaI/DeltaG increased (P < 0.05). The second-phase insulin response and GIR were both demonstrated marked increments (P < 0.01 and P < 0.01, respectively). Pioglitazone therapy also resulted in improvement of ISI value (P < 0.05). And the increment of GDR during the euglycemic-hyperinsulinemic clamp was also significant (P < 0.01). Furthermore, a decrease in fasting proinsulin level was observed (P < 0.001). And plasma glucose, FFAs and serum insulin levels all declined. The increase of DeltaI1/DeltaG1 was positively correlated with the improvement of GDR (r = 0.536, P = 0.089). And a positive relationship was observed between the change in the second-phase insulin response and change in K value (r = 0.682, P = 0.021). CONCLUSIONS: Short-term pioglitazone therapy improved beta-cell dysfunction, the mechanism might involve the attenuation of insulin resistance.
In mammalian striate cortex (V1), two distinct functional classes of neurones, the so-called simple and complex cells, are routinely distinguished. They can be quantitatively differentiated from each other on the basis of the ratio between the phase-variant (F1) component and the mean firing rate (F0) of spike responses to luminance-modulated sinusoidal gratings (simple, F1/F0 > 1; complex, F1/F0 < 1). We investigated how recurrent cortico-cortical connections affect the spatial phase-variance of responses of V1 cells in the cat. F1/F0 ratios of the responses to optimally oriented drifting sine-wave gratings covering the classical receptive field (CRF) of single V1 cells were compared to those of: (1) responses to gratings covering the CRFs combined with gratings of different orientations presented to the 'silent' surrounds; and (2) responses to CRF stimulation during reversible inactivation of postero-temporal visual (PTV) cortex. For complex cells, the relative strength of the silent surround suppression on CRF-driven responses was positively correlated with the extent of increases in F1/F0 ratios. Inactivation of PTV cortex increased F1/F0 ratios of CRF-driven responses of complex cells only. Overall, activation of suppressive surrounds or inactivation of PTV 'converted' substantial proportions (50 and 30%, respectively) of complex cells into simple-like cells (F1/F0 > 1). Thus, the simple-complex distinction depends, at least partly, on information coming from the silent surrounds and/or feedback from 'higher-order' cortices. These results support the idea that simple and complex cells belong to the same basic cortical circuit and the spatial phase-variance of their responses depends on the relative strength of different synaptic inputs.
A novel reversed-phase high-performance liquid chromatographic (HPLC) method has been established for the determination of a newly developed anti-cancer agent desoxyepothilone B (dEpo B) in nude mice plasma. The sample preparation involved deproteination of 200 microl of plasma sample first, followed by liquid-liquid extraction of the resultant supernatant with chloroform. The compound taxol was used as the internal standard. Chromatographic separations were carried out on a 250 mm x 4.6 mm Zorbax SB-phenyl column with acetonitrile-0.25% orthophosphoric acid (50/50, v/v) as mobile phase and UV detection at 250 nm. For dEpo B and taxol at the concentration level of 10 microg/ml in nude mice plasma, the absolute extraction recoveries were 85.3 and 87.2%, respectively. The linear quantification range of the method was 0.1-100 microg/ml in nude mice plasma with linear correlation coefficients greater than 0.999. The within-day and between-day relative standard deviations (R.S.D.s) for dEpo B at 0.5, 2.5 and 10 microg/ml levels in nude mice plasma fell in the range of 2.8-4.8 and 1.5-4.6%, and the within-day and between-day recoveries were in the range of 96.5-101.7 and 97.7-101.2%, respectively.
A novel hybrid hydrogel system based on N-(2-hydroxypropyl)methacrylamide copolymers was proposed. It consisted of the hydrophilic polymer backbone and a pair of oppositely charged peptide grafts. Two distinct pentaheptad peptides (CCE and CCK) were anticipated to create a dimerization motif and serve as physical cross-linkers. Consequently, the graft copolymers CCE-P and CCK-P self-assembled into hybrid hydrogels in situ; the process was modulated by the formation of antiparallel heterodimeric coiled-coils. This approach possesses an advantage to decrease the steric hindrance of the polymer backbone on the "in-register" alignment of peptide grafts. Indeed, equimolar mixtures of the graft copolymers, CCE-P/CCK-P, have been observed to self-assemble into hydrogels in PBS solution at neutral pH at concentrations as low as 0.1 wt %. Circular dichroism spectroscopy, sedimentation equilibrium experiments, and microrheology revealed that the self-assembly process corresponded to the two-stranded alpha-helical coiled-coil formation between CCE and CCK. Moreover, the formation of hybrid hydrogels was reversible. Denaturation of the coiled-coil domains with guanidine hydrochloride (GdnHCl) solutions resulted in disassembly of the hydrogels. Removal of GdnHCl by dialysis caused coiled-coil refolding and hydrogel reassembly. Scanning electron microscopy results demonstrated that the concentration of the graft copolymers had a significant impact on the structure and morphology of self-assembled hydrogels.
The interaction between carbamazepine (CBZ) and bovine serum albumin (BSA) was studied using fluorescence spectroscopy (FS) and ultraviolet spectroscopy (UV). The experimental results showed that the CBZ could insert into the BSA and quench the inner fluorescence of BSA by forming the CBZ-BSA complex. It was found that both static quenching and non-radiation energy transfer were the main reasons leading to the fluorescence quenching. The apparent binding constants (K) between CBZ and BSA were found to be 1.8 x 10(4) (27 degrees C) and 2.8 x 10(4) (37 degrees C) and the binding site values (n) were 0.97 (27 degrees C) and 1.01 (37 degrees C), respectively. According to the Forster theory of non-radiation energy transfer, the binding distances (r) between CBZ and BSA were 3.6 nm and 3.4 nm at 27 degrees C and 37 degrees C, respectively. The process of the binding was a spontaneous molecular interaction in which entropy increased and Gibbs free energy decreased, indicating that the interaction between CBZ and BSA was mainly driven by the hydrophobic force.
Through the flow injection analysis experiments, we discovered that an unsaturated complex of Cu(II) and polyamines (spermine, spermidine, putrescine) had a strongly catalytic effect on luminol-H(2)O(2) chemiluminescence (CL) reaction, and that the CL intensity is proportional to the concentrations of polyamines. Based on the automatic formation of an unsaturated complex of polyamines and Cu(II) when the solution containing polyamines passed through a column packed with solid Cu(OH)(2), a new flow injection chemiluminescence analysis method was proposed for the determination of polyamines. The effects of pH, buffer concentration, the concentration of chemiluminescence reagent, and the influence of mixing coil length were examined. Under optimal conditions, the linear range was from 1.0 x 10(-7) mol L(-1) to 1.0 x 10(-5) mol L(-1), and the detection limits were 0.17, 0.38, 0.44 pmol for spermine, spermidine, and putrescine, respectively. Compared with other methods, the advantages of this method include convenience, time-saving and low cost.
The mucosal surface of the gastrointestinal (GI) tract is the first line of defense against foreign pathogens and toxins ingested orally. The content of the GI tract is constantly being sampled by the immune system through specialized epithelial cells known as M-cells, which are present in the Peyer's patches of the gut, providing a thin covering over lymphoid tissue. In this way, once a harmful entity is found an immune response can be activated to eliminate the threat. Many bacterial pathogens, such as Yersinia, Listeria, Salmonella, and Shigella, have evolved ways of exploiting M-cells to gain entrance to the body. The Yersinia species is of particular interest since its extracellular protein invasin provides one of the most direct and efficient manners of host cell invasion. Invasin binds to a subset of beta1 integrin receptors located on the apical membrane of intestinal M-cells, thereby facilitating the bacteria's entry into the cells and the lymphatic system underneath. This mechanism is highly specific and effective, making the invasin protein a very attractive modality for use in the oral delivery of molecules that include therapeutic genes and gene-based vaccines. This article provides a brief overview of the molecular structure and properties of the Yersinia invasin as related to the protein's ability to facilitate binding and entry into M-cells. Also discussed are several innovative approaches that demonstrate the use of invasin as an effective targeting agent for biological and synthetic gene carrier systems, and the future prospect of developing invasin-based oral gene delivery formulations.
OBJECTIVE: To evaluate the effect of modified culture method used to cytogenetic analysis and the clinically significance of chromosomal abnormalities to multiple myeloma (MM). METHODS: Mononuclear cells were isolated from bone marrow aspirate of 20 MM patients; and then cultured for 3 days without any cytokines, and 6 days in the presence of IL-6 (10 ng/mL) and GM-CSF (30 ng/mL) before RHG banding analysis; the remained part of aspirates were treated directly. Eight cases of iron deficiency anemia were taken as control. RESULTS: The experiment was failure in 2 cases because of blood clot, and another 2 cases could be analyzed only by direct method due to inadequate cells. The karyotype abnormalities were found from 4 cases of 16 available patients. Of them, three cases had complex karyotypes. The abnormalities were detected after 6 days culture with addition of cytokines. No abnormalities were detected from those groups of directly analysis and 3 day culture. Meantime, the clinical data showed that the patients with cytogenetic abnormalities were in stage III, and had a high percentage of MM cells (25%-56%) in their bone marrow, and also poor responses to prior chemotherapy. No cytogenetic abnormalities were found from control individuals in all groups. CONCLUSION: Extended culture in the presence of cytokines could improve the efficiency of cytogenetic analysis to MM. Complex karyotype was common cytogenetic abnormalities in MM patients with poor response to chemotherapy.
OBJECTIVE: To explore the specific locus deletion of the long arm of chromosome 13 and its relationship with the clinical behavior and prognosis of multiple myeloma (MM). METHODS: FISH analysis was performed on bone marrow smears from 68 patients with MM to study the deletion of Rb-1 gene and locus 13q14.3 on chromosome 13. The statistic value of its effect on clinical features were determined. RESULTS: 35 out of the 68 (51%) cases were found with deletion of chromosome 13; deletion of Rb-1 gene were found in 29 (43%) cases; deletion of locus 13q14.3 were found in 23 out of 44 (52%) cases; the analysis results were same in 66% of the cases (29/44) with the above two probes. Chi-square test showed that partial deletion of chromosome 13 was associated with clinical behavior, early chemotherapy response and 1 year survival. CONCLUSION: Deletion of Rb-1 gene and locus 13q14.3 were both common cytogenetic changes in MM patients with effect on the biological behavior of the disease.
OBJECTIVE: To explore the role of X-linked inhibitor of apoptosis protein (XIAP) in the fibronectin (Fn)-adhesion mediated drug resistance of HL-60 cells. METHODS: Culture plates were coated with Fn and bovine serum albumin (BSA) (as control), respectively. Colorimetric CCK-8 assay was used to determine the effects of Fn on the cytotoxicity of DNR to HL-60 cells. Intracellular DNR accumulation was assayed with flow cytometry. Reverse transcription-PCR and Western blot were used to examine the mRNA expression and XIAP, bcl-2, MRP and mdr1 proteins, respectively. HL-60 cells were added to Fn coated Culture plates. The fully phosphorothioate antisense oligonucleotide (AS-ODNs) and the control ODNs of XIAP were delivered into HL-60 cells in the form of liposome-ODN complexes. IC(50) was calculated by linear regression of survival percent versus drug concentration. RESULTS: HL-60 cells adhered to Fn-coated plates had a significant survival advantage over those grown on BSA coated plates and in suspension when exposed to DNR, the IC(50) of Fn group being significantly higher than that of BSA group and suspension group (0.526 micromol/L vs 0.132 micromol/L, 0.123 micromol/L, respectively, P < 0.05). XIAP was up-regulated significantly in Fn group compared with BSA group and suspension group (P < 0.05), whereas there was no difference in the expressions of bcl-2, MRP and mdr1 among the three groups (P > 0.05). The intracellular concentration of DNR in Fn-adhered HL-60 cells was similar to that in BSA group and suspension group (P < 0.05). AS-ODNs of XIAP down-regulated the XIAP expression in Fn-adhered HL-60 cells. In addition, AS-ODNs sensitized HL-60 cells to the cytotoxic effects of DNR. CONCLUSION: The increased XIAP protein level contributes to the drug resistance induced by adhesion to Fn. AS-ODNs of XIAP might reverse the drug resistance.
OBJECTIVE: To analyse the relationship of T lymphocyte and granulocyte chimerism following allogeneic peripheral blood cell transplantation and the occurrence of relapse, graft failure and graft versus host disease. METHODS: 21 patients underwent allogeneic peripheral blood stem cell transplantation (allo-PBSCT). Fluorescence-activated cell sorter (FACS) sorted CD3+ T lymphocytes and CD15+ granulocyte from peripheral blood of all the patients were analyzed for short tandem repeats in 7 days interval for 1 month starting from the day of PBSCT, then 1 month interval for 6 months, and then 3 months interval to the end of one year. RESULTS: Chimerism of granulocyte was higher than T lymphocyte on day 7 posttransplant in 4 patients given myeloablative conditioning. The median donor chimerism of granulocyte and T lymphocyte was 95% and 55% respectively. The other 17 patients had higher chimerism of T lymphocyte than granulocyte on day 7, which was 60% (15%-76%) and 0% (0%-40%) respectively. 20 patients reached complete donor chimerism (CDC) on day 21 (14-102 days) for T lymphocyte and on day 14 for granulocyte, except one relapsed on day 28. Seven patients had decreasing mixed chimerism when disease relapsed or graft failure occurred. T cell donor chimerism decreased earlier than myeloid cells, however, bone marrow sample and granulocyte still remained in complete donor chimerism or stable mixed chimerism, bone marrow smear showed normal at the same time. CONCLUSION: Blood leukocyte subset chimerism analysis, especially T cell chimerism analysis may provide earlier information of engraftment, relapse and graft failure than blood and bone marrow samples, therefore immunomodulatory therapies may be given to recipients earlier and overall survival may be improved.
This study was purposed to investigate the clinical significance of the amount and activated status of T cell subsets, B cells, NK cells in peripheral blood from patients with myelodysplastic syndrome (MDS). The proportion of T cells, B cells, NK cells in peripheral blood from 30 patients with MDS and their surface activation markers of CD28, CD45RA, CD45RO, CD69, HLA-DR were analyzed by flow cytometry. Twenty-two patients were in the low risk group (RA + RAS) while eight patients were in the high risk group (RAEB + RAEBT). The result showed that the amounts of T cells (CD3+ cells) in peripheral blood from patients with MDS were lower than those in control group. The amounts of naive CD4+ cells (CD4+ CD45RA+ cells) in MDS patients were lower than those in control. The expression rates of early activation marker (CD69) and late activation marker (HLA-DR) on CD3+ cells in MDS patients were significantly higher than those in control. The abnormalities of the immunologically competent cells were mainly observed in the low risk group (RA + RAS), and were characterized by the high expression rates of CD69+ and HLA-DR+ on CD3+ cells, the decrease of B cell amounts. The amount abnormalities of T cell subsets were mainly observed in high risk group (RAEB + RAEBT), and were characterized by the decrease of CD3+ cells and CD3+ CD4+ CD8- cells (Th cells) amounts without high expression of the CD69 and HLA-DR, the decrease of NK cells amounts. It is concluded that there are the abnormalities of T cell subsets and function in the patients with MDS and may change with disease progression, so the measurement of amount and activated status of T cell subsets in peripheral blood from MDS patients can have predictive role for diagnosis of disease progression and guide of therapy.
BACKGROUND & OBJECTIVE: The manifestations of old acute myelogenous (AML) patients have their special biological and clinical characteristics, with lower response rate to therapy and shorter survival time. This study was to investigate the prognostic factors of elderly patients with AML retrospectively. METHODS: 77 patients aged> or =60 years with AML from 1994 to 2005 were admitted to our study and all the possible prognostic factors were analyzed with Kaplan-Meier survival analysis. The significant factors were further analyzed by Cox proportional hazard model analysis. RESULTS: Seventy-two patients were evaluated. The patients aged 60-70 (median survival time was 350 days) had significantly longer survival time than those aged more than 70 (median survival time is 60 days)(P<0.001), which their CR ratios were 71.4% and 29.4% (P=0.001). The patients with performance status 0 or 1 (median survival time was 402 days) had significantly longer survival time than those with performance status 2, 3 or 4 (median survival time was 31 days)(P<0.001), which their CR ratios were 75% and 15% (P<0.001). The patients with primary AML (median survival time was 98 days) had significantly longer survival time than those with secondary AML (median survival time was 32 days)(P=0.007), which their CR ratios were 50% and 0% (P=0.023). The patients treated with sub-standard dosage of anthracycline (median survival time was 293 days) had significantly longer survival time than those treated with reduced dosage of anthracycline (median survival time was 35 days)(P=0.006), which their CR ratios were 63.6% and 33.3% (P=0.02). The patients with bone marrow blast cell ratio< or =50% (median survival time was 98 days ) had significantly longer survival time than those with bone marrow blast cell ratio >50% (median survival time was 55 days)(P=0.006). The patients with favorable karyotype (median survival time was 293 days) had significantly longer survival time than those with unfavorable or normal karyotype (median survival time was 31 days)(P=0.005). The patients without CD34 expression (median survival time was 201 days) had significantly longer survival time than those with CD34 expression(median survival time was 36 days)(P<0.001). The patients with the peripheral blood white blood cell count (PBWBC)>10x10(9)/L (50%) had significantly higher CR ratio than those with PBWBC< or =10x10(9)/L (25%)(P=0.043). The patients received chemotherapy (50%) had significantly higher CR ratio than those received supportive therapy (0%)(P=0.001). In the stepwise COX proportional hazard regression model, all the seven factors related to OS remained independent and significant. CONCLUSIONS: Factors, including age >70, PS 2 to 4, percentage of blasts in bone marrow >50%, secondary AML, unfavorable karyotype, expression of CD34, lower dosage.
AIM: To study the interaction between strychnine and bovine serum albumin. METHODS: Fluorescence spectroscopy and ultraviolet spectroscopy were used. RESULTS: The static quenching and the non-radiation energy transfer are the two main reasons to leading the fluorescence quenching of BSA. The apparent combining constants (K(A)) between strychnine and BSA are 3.72 x 10(3) at 27 degrees C, 4.27 x 10(3) at 37 degrees C, 4.47 x 10(3) at 47 degrees C and the combining sites are 1.01 +/- 0.03. The combining distance (r = 3.795 nm) and energy transfer efficiency (E = 0.0338) are obtained by Förster's non-radiation energy transfer mechanism. CONCLUSION: The interaction between strychnine and BSA was driven mainly by hydrophobic force.