Biomedical subjects

X Cao

Publications and source records attributed to X Cao.

At least 217 records · Page 12Linked to original sources

PubMed1998

[The effects of intraperitoneal injection of IL-2 recombinant adenovirus and/or IL-3 recombinant adenovirus on the hematological recovery of murine model receiving high dose chemotherapy].

OBJECTIVE: To investigate the effect of Ad-IL-2 and/or Ad-IL-3 on the hematological recovery of murine model receiving high dose chemotherapy. METHODS: Ad-IL-2 and/or Ad-IL-3 were i.p. injected into experimental mice after high dose cyclophosphamide(200 mg/kg). RT-PCR analysis of peritoneal cells and cytokine levels in murine serum were detected to confirm gene transfering. The number of peripheral WBC, femur MNC and CFU-GM in bone marrow were observed continuously. RESULTS: After i.p. injection of Ad-IL-2 and/or Ad-IL-3, the transfected IL-2 and IL-3 gene were identified by RT-PCR analysis of peritoneal cells, high level of IL-2 and/or IL-3 were detected in murine serum. After i.p. injection of AD-IL-3, the number of WBC, femur MNC and CFU-GM in bone marrow significantly increased, while i.p. injection of Ad-IL-2 had no effect on improving hematological recovery. And the effect of i.p. injection of both Ad-IL-2 and Ad-IL-3 was not significantly different from that of injection either of them. CONCLUSION: i.p. injection of Ad-IL-3 can increase hematological recovery after high dose chemotherapy.

Adenoviruses, Human↗

PubMed1998

[The construction and application of adenovirus vector coexpressing the heterodimer of human IL-12].

OBJECTIVE: To construct the recombinant adenovirus vector co-expressing the heterodimer of human interkeukin-12. METHODS: The full-length cDNA encoding human IL-12 subunits p40 or p35 was cloned by RT-PCR separately. The cDNA was ligated with encephalomyocarditis internal ribosome entry site (IRES), placed under the control of CMV promoter, and inserted into E1-substituted adenovirus vector pAx1cw to produce the bicistronic coexpression vector. Subsequently, the hIL-12 recombinant adenovirus vector was cotransfected into 293 cells together with EcoT22I-digested Ad5 DNA-TPC, and the replication-deficient hIL-12 recombinant adenoviruses was generated efficiently by homologous recombination. RESULTS: The human IL-12 recombinant adenoviruses were obtained with the titers of 2.1 x 10(9) pfu/ml. 48 hours after the infection of the 293 cells, HepG2 cells and human primary skin fibroblasts with hIL-12 recombinant adenoviruses, the hIL-12 expressions were detected by ELISA (30-50 ng/10(6) cells/24 h). The expressed hIL-12 could stimulate the in vitro proliferation and IFN-gamma production of human PMNC. CONCLUSION: Prepared hIL-12 recombinant adenovirus vector can express biologically active hIL-12 and can be potentially used in cancer gene therapy.

Adenoviruses, Human↗

PubMed1998

[Observation of enalapril on treating the patients with left ventricular diastolic dysfunction].

The effects of enalapril on 50 patients with left ventricular diastolic dysfunction (LVDD), confirmed by clinical features and radionuclid ventriculography, were assessed in a randomized, double-blind, and controlled method for eight weeks. The results showed that left atrial diameters (LAD), interventricular septum thicknesses (IVST) and left ventricular mass indexes (LV-MI) except left ventricular diameters (LVD) were decreased in the enalapril treatment group. The left ventricular diastolic function parameters such as the early peak filling velocity (EPAV), the atrial peak filling velocity (APAV), the deceleration of early peak filling velocity (DC) and the isovolumic relaxation time (IRT) were improved, the NYHA class and the exercise tolerance were increased, the left ventricular ejection fraction (LVEF), and the cardiac index (CI) were not altered in the enalapril treatment group. The patients with LVDD were well tolerated with enalapril. The parameters mentioned above were not altered in control group. It is suggested that enalapril is an effective drug in the treatment of LVDD.

Adult↗

PubMed1998

[Therapeutic effects of combined suicide gene and cytokine gene therapy on erythroleukemia-bearing mice].

OBJECTIVE: To explore the antitumor effect of combined transfer of suicide gene and GM-CSF gene in erythroleukemia-bearing mice. METHODS: Adenovirus harboring E. coli. cytosine deaminase (CD) gene (Ad-CD) and/or GM-CSF gene (Ad-GM-CSF) were used for the treatment of erythroleukemia-bearing mice. The mice were inoculated with FBL-3 erythroleukemia cells subcutaneously and 3 days later received Ad-CD followed by 5-fluorocytosine (5FC) treatment with or without Ad-GM-CSF. RESULTS: The mice received Ad-CD/5FC and Ad-GM-CSF developed tumors more slowly and survived much longer than those received Ad-CD/5FC alone, Ad-GM-CSF alone, control virus Ad-LacZ/5FC or PBS. Combined transfer of CD gene and GM-CSF gene induced a higher specific CTL activity than control therapies did. Pathological examination illustrated that there were tumor necrosis and massive lymphocyte infiltration in the mice after the combined therapy. CONCLUSION: Combined transfer of suicide gene and cytokine gene could synergistically inhibit the growth of erythroleukemia cells in the mice and induce tumor specific immunity of the host.

Adenoviruses, Human↗

PubMed1998

[Studies on the in vivo induction of differentiation of the erythroleukemia cells by the antigen-pulsed dendritic cells modified with GM-CSF gene].

OBJECTIVE: To investigate the function and mechanism of dendritic cells in the immunotherapy for tumors. METHODS: C57BL/6 mice inoculated with erythroleukemia cells were used as models. Inhibition or induction of tumor cell differentiation was observed by fluorescence-activated cell sorting (FACS) and transmission electron microscopy. RESULTS: After pulsed with FBL-3 antigen, the GM-CSF gene transfected dendritic cells inhibited the proliferation of the tumor cells. The expression of CD14 was increased and the expressions of MHC-II, B7-1, B7-2 and VCAM-1 were also up-regulated. Erythroleukemia cells in different differentiating stages were observed in tumor tissues. Under transmission electron microscope, the volumes of FBL-3 cells were reduced, the amount of lysosome and hetero-chromatin became plentiful, the nucleocytoplasmic ratio was decreased, and apoptosis was revealed in erythroleukemia cells. The CD8+ cells were increased in peripheral blood and tumor tissues. CONCLUSION: The antigen-pulsed dendritic cells modified with GM-CSF gene could induce in vivo the erythroleukemia cells to differentiate into monocytes.

Adenoviruses, Human↗

PubMed1998

Avascular necrosis of the femoral head: MR imaging with radiological and histological correlation.

OBJECTIVE: To assess the value of MR in the diagnosis of avascular necrosis (AVN) of the femoral head. METHODS: MR images in 34 consecutive patients (26 men and 8 women) with AVN (57 hips) were reviewed. All lesions were confirmed by radiographic, radionuclide, computed tomographic, and/or histologic examination. Eleven specimens were obtained after total replacement of the hip. Four hips underwent biopsy. All MR images were obtained using a 0.35 T superconductive imaging unit with SE sequence. Specimens were cut coronally into 5 mm thick section and radiographs were obtained. RESULTS: There were four types of MR patterns of AVN. Type one appeared liner or patchy low signal area in the superoanterior portion of the femoral head. In type two, a band or ring of low signal intensity was found surrounding a central area of high signal intensity on T1WI and intermediate signal intensity on T2WI. The low signal band or ring consisted of thickened trabecular bone, mesenchymal and fibrous tissue, and amorphous acidophilic cellular debris. The central zones within the ring were composed of necrotic bone and marrow that had not been reached by the repair process. In type three, the focal subchondral region showed intermediate signal intensity on T1WI and high signal on T2WI surrounded by a low signal ring. The low signal ring consisted of thickened trabecular bone and little mesenchymal tissue. The central area was composed of mesenchymal tissue rich in capillaries and cystic necrotic zones. In type four, the signal intensity of femoral head was inhomogeneous on both T1WI and T2WI. There were low signal bands in the femoral neck surrounding the necrotic zone. Only limited areas of some lesions had signal intensity isointense with fat on T1WI and T2WI. The inhomogeneous area of low signal intensity consisted of a mixture of necrotic bone and marrow, amorphous cellular debris. The first type of MR pattern corresponded to the early stage of radiograph, and the third type of MR pattern to stage 5. The second and fourth type of MR patterns correlated less with the radiographic stage. CONCLUSIONS: MR imaging plays an important role in the diagnosis of AVN of femoral head especially in the early detection of AVN. The MR patterns of AVN is not correlated with radiographic stages exactly.

Female↗

PubMed1998

[Hepatectomy for hepatolithiasis treatment of 354 cases].

OBJECTIVE: To evaluate the effect of hepatectomy for hepatolithiasis. METHOD: 354 patients with hepatolithiasis underwent hepatectomy in the past 10 years. The results were analysed retrospectively, including clinical findings, distribution of stones, patterns of operation, postoperative complications, and residual stones. The clinical data of the patients before 1990 were compared with those thereafter. RESULT: Left hepatolithiasis was the most common form (323 patients). Left lateral lobectomy and left hepatectomy were most commonly employed (91.2%). 166 of the patients underwent concurrent cholangiojejunostomy. 13.8% patients had residual stones, and postoperative complications occurred in 60 patients, including 4 deaths. Few patients were reoperated on and the incidence of residual stones was lower after 1990. 88% the patients showed excellent or good result. CONCLUSION: Hepatectomy is a procedure for the management of hepatolithiasis, but still requires combined plasty of stenotic intrahepatic bile ducts and cholangiojejunostomy to reduce the incidence of residual stones and recurrence.

Adolescent↗

PubMed1998

[Immunohistochemical studies on wholemounts of the cornea and iris-ciliary body after corneal transplantation].

OBJECTIVE: To study the phenotype of the cells involved in the pathogenesis of allograft rejection after corneal transplantation. METHODS: Wholemounts of the cornea and iris-ciliary body were isolated and prepared from normal rats and those after penetrating corneal transplantation. Immunohistochemical stainings were carried out on these wholemounts using monoclonal antibodies to CD3 (T cell), CD4 [T-helper (Th) cell], CD8 [T-suppressor (Ts) cell], macrophages, dendritic cells, B lymphocytes, major histocompatibility complex (MHC) class II antigen and transforming growth factor-beta (TGF-beta). RESULTS: All the cells mentioned above except B lymphocytes were positive and present in a small number in the peripheral cornea and limbus of normal rats. A massive influx of CD3, CD4, CD8 positive cells, macrophages, dendritic cells, MHC class II and TGF-beta positive cells not only into cornea but also into the iris was observed 7 days after allograft corneal transplantation. Whereas no B cell was found in the allograft. Such a cellular response was not found in the rats in which corneal transplantation with autologous cornea was performed. CONCLUSION: T cells, Th cells, Ts cells, macrophages, dendritic cells, MHC class II positive cells and TGF-beta positive cells are involved in the pathogenesis of corneal allograft transplantation. The involvement of the iris and ciliary body may promote or aggravate the allograft rejection.

Animals↗

PubMed1998

[Studies on trigonometric transform enhancement of chest radiograph based on its anatomical feature].

In this paper, we present a novel trigonometric transform contrast enhancement method for digital chest radiograph, which is based on the anatomical feature of the image processed. With automatic segmenting chest image into a lung region and a non-chest region, a positive linear transform and a negative one are used in lung region and the other region respectively. Therefore, it can enhance the contrast both in lung regions and in mediastinum region up to entire dynamic range of display device.

Algorithms↗

PubMed1998

[An automatic method segmenting lung regions from digital chest radiograph].

It is difficult to process digital chest image with ordinary method because of the wide dynamic range of chest radiograph. Anatomically adaptive processing is a better method for chest image, but it needs automatic segmentation of the image. In this paper, an effective method for segmenting lung regions from digital chest radiograph is presented. This method automatically calculates the lung/mediastinum-subdiaphragmatic threshold according to the histogram of chest image processed.

Humans↗

PubMed1998

Selective inhibition of cell proliferation and BCR-ABL phosphorylation in acute lymphoblastic leukemia cells expressing Mr 190,000 BCR-ABL protein by a tyrosine kinase inhibitor (CGP-57148).

The excessive proliferation of the myeloid marrow compartment in Philadelphia chromosome (Ph)-positive acute and chronic leukemias has been largely attributed to a hyperactive and autonomously acting hybrid tyrosine kinase BCR-ABL, a product of the fusion between the second exon of the c-ABL proto-oncogene and 5' portions of the BCR gene on chromosome 22. This specific molecular event, amenable to attack with specifically designed inhibitors, has recently been successfully influenced by the drug CGP-57148 in mammalian cells transfected with full-length BCR-ABL gene and expressing full-length p210Bcr-Abl protein, as well as in primary human leukemic cells expressing p210Bcr-Abl fusion protein. In view of the heterogeneity of BCR-ABL transcripts associated with various phenotypes, we investigated the effect of CGP-57148 on p190Bcr-Abl- and p210Bcr-Abl-expressing, patient-derived cell lines and primary intact blast cells. In particular, we were interested in whether the variations in molecular events and/or the phenotype of Ph-positive cells would affect their susceptibility to the specific tyrosine kinase inhibitor CGP-57148. We have demonstrated that the sensitivity of human cells with lymphoblastic immunophenotype expressing p190Bcr-Abl protein is comparable to that for leukemic myeloid cells expressing p210Bcr-Abl protein. After documenting profound and phenotype-independent suppression of both autophosphorylation and cell growth, we explored the importance of time and dose of exposure on the manifestation and stability of the induced events. Although there were variations between target cells, in vitro exposure for 24-48 h induced extensive and apparently irreversible apoptosis in BCR-ABL-expressing but not other normal or BCR-ABL-negative leukemic cells. These findings support the potential use of CGP-57148 to purge Ph-positive cells from autologous bone marrow in vitro. Another important finding was the comparable suppressive effect of temporary CGP-57148 exposure on both clonogenic KBM-5 cells and the whole cell population. Exposure time and dose appeared to be important variables among various cell types. Moreover, effective doses appeared uniformly harmless to cells lacking BCR-ABL protein functioning as tyrosine kinase. Thus, the continuous exposure of target cells, at least during the initial period of 24-48 h, may prove to be an important variable in the design of in vitro and in vivo therapy using tyrosine kinase inhibitors.

Apoptosis↗

PubMed1997

Effects of gamma-aminobutyric acid, progesterone and ionophore A23187 on acrosome reaction of tree shrew sperm in vitro: examination of acrosome reaction with an improved fluorescence microscopy.

A number of acrosome reaction (AR) initiators have been found to be effective in inducing AR of human, laboratory and domestic animal sperm. Using an improved simple fluorescence microscopy, effects of gamma-aminobutyric acid (GABA), progesterone and ionophore A23187 on sperm AR of tree shrew, a useful animal model in biomedical research, have been investigated. Spontaneous AR in 4.92-7.53% of viable sperm was observed. Complete AR in 10.31-18.25% of viable tree shrew sperm was obviously induced by 5 microM and 10 microM calcium ionophore A23187, 1 mM GABA, and 5 microM progesterone, and there were no significant differences between their abilities to initiate complete AR. No significant differences of AR percentages between 1- and 2-h treatments with A23187, progesterone and/or GABA were observed. These results suggested that the responses of tree shrew sperm to these AR initiators are similar to that of human and other mammalian sperm.

Acrosome↗

PubMed1997

Neurokinin-1 receptor antagonist SR140333: a novel type of drug to treat cerebral ischemia.

Substance P (SP) has been implicated in immune responses and could increase glutamate release, and inflammatory reactions are known to be able to potentiate ischemic damage. We have previously found that SP was over-expressed in cerebral ischemia and speculated that SP may play a role in exacerbating ischemic damage. In this study, we examined whether a neurokinin-1 (NK-1) receptor antagonist, SR140333, would have an effect on brain ischemia. Intra-cerebroventricular (i.c.v.) administration of SR140333 (30 micrograms) markedly reduced (37.1 +/- 7.8%, p < 0.001) infarct volume measured 24 h after focal cerebral ischemia in the rat. The SR140333-treated group also exhibited a significantly improved neurological function reflected by the neurological deficit score. The results represented the first demonstration that a NK-1 receptor antagonist may be a novel type of drug for treatment of cerebral ischemia.

Animals↗

PubMed1997

Long term chronic recordings from peripheral sensory fibers using a sieve electrode array.

The use of an implanted micromachined silicon sieve electrode array to make long term chronic recordings from the glossopharyngeal nerve is described. The implant consists of an array of small holes in a silicon substrate, four of which are surrounded by electrodes connected with an integrally fabricated ribbon cable to a percutaneous headcap. Using this device we have been able to monitor the integrity of the electrodes from the time of implantation and subsequently to record evoked sensory responses from mechanoreceptors on the tongue.

Animals↗

PubMed1997

Bifunctional fusion between nerve growth factor and a transferrin receptor antibody.

The cDNAs encoding the variable regions of the heavy and light chains of a murine antibody specific for the human TfR were cloned and a human chimera (gamma1, kappa) was produced. A gene fusion was created by joining the 3' end of the coding region of the human nerve growth factor (NGF) precursor to the 5' end of the heavy chain variable region of the chimeric antibody. When expressed with the unmodified light chain in mammalian cells, the protein fusion is properly processed, assembled, and secreted. Subsequent purification and characterization established the uncompromised bifunctional activities of the protein, relative to the unmodified components, as demonstrated by its ability to both bind to the human TfR and induce neurite outgrowth in primary sympathetic or spinal ganglia and in trkA-transfected pheochromocytoma cells. The ability to generate biologically active NGF fused to a TfR targeting antibody, which was previously shown to cross the blood-brain barrier, may offer a novel way to deliver NGF and other neurotrophic factors to the central nervous system.

Animals↗

PubMed1997

Involvement of MHC class I molecule and ICAM-1 in the enhancement of adhesion and cytotoxic susceptibility to immune effector cells of tumor cells transfected with the interleukin (IL)-2, IL-4 or IL-6 gene.

To investigate the molecular and cellular mechanisms involved in the reduced tumorigenicity and increased immunogenicity of interleukin-2 (IL-2)-, IL-4- or IL-6-gene-transfected B16 melanoma vaccine, we have analyzed the functional and phenotypic properties of these genetically engineered melanoma cells in the present study. The cytokine-gene-transfected B16 melanoma cells showed stronger adhesion to the lymphokine-activated killer (LAK) cells or cytotoxic T lymphocytes (CTL), and higher sensitivity to cytotoxicity of LAK cells or CTL. Using fluorescence-activated cell sorting analysis, we found that both MHC class I and ICAM-1 expression were increased after IL-2, IL-4 or IL-6 gene transfection. The increased level of MHC class I and ICAM-1 expression seems to be responsible for the high sensitivity of these gene-transfected B16 cells to LAK or CTL cytotoxicity because anti-(MHC class I) or anti-ICAM-1 mAb could inhibit the adhesion and cytotoxicity increment simultaneously. The CTL induction was partly inhibited by anti-ICAM-1 mAb and was completely blocked by anti-MHC class I mAb. These results suggested that the decreased tumorigenicity of IL-2-, IL- 4-, and IL-6-gene-transfected B16 melanoma cells may be partly due to the increased sensitivity to effector cell cytotoxicity mediated by increased expression of ICAM-1 or MHC class I molecules on the tumor cell surface after cytokine gene transfection.

Animals↗

PubMed1997

Diffusion behavior of lipid vesicles in entangled polymer solutions.

Dynamic light scattering was used to follow the tracer diffusion of phospholipid/cholesterol vesicles in aqueous polyacrylamide solutions and compared with the diffusive behavior of polystyrene (PS) latex spheres of comparable diameters. Over the range of the matrix concentration examined (Cp = 0.1-10 mg/ml), the diffusivities of the PS spheres and the large multilamellar vesicles exhibited the Stokes-Einstein (SE) relation, while the diffusivity of the unilamellar vesicles did not follow the increase of the solution's viscosity caused by the presence of the matrix molecules. The difference between the diffusion behaviors of unilamellar vesicles and hard PS spheres of similar size is possibly due to the flexibility of the lipid bilayer of the vesicles. The unilamellar vesicles are capable of changing their shape to move through the entangled polymer solution so that the hindrance to their diffusion due to the presence of the polymer chains is reduced, while the rigid PS spheres have little flexibility and they encounter greater resistance. The multilamellar vesicles are less flexible, thus their diffusion is similar to the hard PS spheres of similar diameter.

Acrylic Resins↗

PubMed1997

Anti-interleukin-6 antibodies inhibit herpes simplex virus reactivation.

Herpes simplex viruses (HSVs) infect epithelial cells, become localized in neurons, and can reactivate in response to a variety of stimuli, including ultraviolet light and hyperthermia. The sequence of gene activation during viral replication is known, but the molecular linkage between exogenous stimuli and HSV reactivation has not been determined. It was hypothesized that interleukin (IL)-6 acts as a signal between exogenous stimuli and neurons, stimulating HSV reactivation from latency. Mouse corneas were infected with HSV-1, and ocular reactivation was induced 5-7 weeks later by thermal stress or corneal exposure to ultraviolet light. Anti-IL-6 monoclonal antibodies were administered to the latently infected mice 8-12 h before the reactivation stimulus. Treatment with anti-IL-6 antibodies resulted in significantly lower frequencies of ocular reactivation compared with those in mice treated with a control immunoglobulin. These results support the hypothesis that IL-6 plays a role in HSV reactivation from latency.

Animals↗