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Biomedical subjects

X Cao

Publications and source records attributed to X Cao.

At least 289 records · Page 16Linked to original sources
PubMed1995

[Experimental study on the treatment of human hepatocellular carcinoma by fibroblast-mediated human IFN-alpha gene therapy in combination with adoptive chemoimmunotherapy].

In the present study, we observed the therapeutic effect of the fibroblast-mediated human IFN alpha gene therapy in combination with IL-2/AK/DOX adoptive chemoimmunotherapy on human hepatocellular carcinoma-bearing nude mice. Activated killer cells (AK) were prepared from human peripheral mononuclear cells co-stimulated in vitro with IL-2 and inactivated human hepatocellular carcinoma SMMC 7721 cells. The results demonstrated that (1) When the NIH3T3-IFN-alpha+ cells were implanted i.p. to the tumor-bearing nude mice, the growth of tumor was inhibited and the survival time of the mice was prolonged; (2) The growth of tumor was significantly inhibited when AK was injected i.v. and IL-2 was injected i.p. after the NIH3T3-IFN-alpha+ cells had been implanted; (3) The best therapeutic results could be achieved when NIH3T3-IFN-alpha+ cells were used in combination with IL-2/AK/DOX. All these results suggeste that the fibroblast-mediated human IFN-alpha gene therapy could be used to treat human hepatocellular carcinoma but better results can be obtained when used in combination with IL-2-based immunotherapy.

3T3 Cells↗
PubMed1995

[Time course of the effect of electroacupuncture on immunomodulation of normal rat].

Lymphocyte proliferation of splenocytes induced by concanavalin A (Con A) and the induction of IL-2 production test were used to study the effects of acupuncture on immunomodulation by stimulation of Zusanli (ST 36) and Lanwei (Extra 33) points of the rat's left leg. It was observed that the lymphocyte proliferation of splenocytes was increased in EA groups of 3 days (p < 0.05) 5 days (p < 0.001) and 7 days (P < 0.05). The parabolical curve could be found by currilinear regression (R2 = 0.9901). EA groups of 3 days and 5 days had a significantly increased induction of IL-2 production (P < 0.05). These results will be helpful to choose an optimal time for clinical treatment.

Animals↗
PubMed1995

[Human lens epithelial cell culture and its proliferative inhibition in vitro].

The cultures of human lens epithelial cells taken from both normal and cataractous lenses were established in vitro. The biological characteristics and the histological changes of the cells were investigated. 5-Fluorouracil (5-Fu), Homoharring tonine (HH) and Harmeline (H) were used for the inhibition of the proliferative cells in the experiment. The results revealed that the in vitro survival capacity of the human lens epithelial cells is limited and the proliferative capacity of the cells is negatively correlated to the donor age. HH and H can effectively inhibit the lens epithelial cell proliferation. Based on the results of this report, performing small and smoothly edged anterior capsulorhexis in extracapsular cataract extraction may possibly decrease the incidence of the post-operative opacification of the posterior capsule.

Adolescent↗
PubMed1995

Experimental renal artery stenosis and angioplasty. The mechanism of the angioplasty.

The mechanism of percutaneous transluminal renal angioplasty (PTRA) was studied in 18 dogs. The dogs were divided into two groups. Seven dogs were in the early group and eleven were within 1-3 weeks after PTRA. A 4/0 resorbable chronic catgut was used to ligate subtotally the renal artery to create fibromuscular dysplasia. PTRA was performed after renal artery stenosis for 6-8 weeks. The changes of ultrastructure of renal artery were studied. A contrary orientation balance hypothesis was proposed to explain the mechanism of PTRA.

Angioplasty, Balloon↗
PubMed1995

[Experimental study on in vivo hematopoietic regulation of interleukin-6 gene therapy].

Interleukin-6 (IL-6), a pleiotropic cytokine, is involved in extensive immune regulation and hematopoietic regulation. We observed the effect of fibroblast mediated human IL-6 gene therapy on hematopoiesis. The platelet counts started to increase at day 4 after implantation of IL-6 highly secreting fibroblast cells and peaked at day 10 and lasted at high level for 22 days. The neutrophil counts were elevated after their implantation, but WBC did not show any remarkable increase. The CFU-GM and CFU-MK in bone marrow and spleen were also increased significantly. The results demonstrated that fibroblasts mediated human IL-6 gene therapy can significantly augment in vivo hematopoietic functions in bone marrow and spleen and elevate the number of nuetrophils and platelets. This study provides a new approach to treat thrombopenia and chemotherapy or radiotherapy-induced hematopoietic suppression.

3T3 Cells↗
PubMed1995

Molecular dissection of the multifunctional poliovirus RNA-binding protein 3AB.

Genome replication of poliovirus, as yet unsolved, involves numerous viral polypeptides that arise from proteolysis of the viral polyprotein. One of these proteins is 3AB, an RNA-binding protein with multiple functions, that serves also as the precursor for the genome-linked protein VPg (= 3B). Eight clustered charged amino acid-to-alanine mutants in the 3AB coding region of poliovirus were constructed and analyzed, together with three additional single-amino acid exchange mutants in VPg, for viral phenotypes. All mutants expressed severe inhibition in RNA synthesis, but none were temperature sensitive (ts). The 3AB polypeptides of mutants with a lethal phenotype were overexpressed in Escherichia coli, purified to near homogeneity, and studied with respect to four functions: (1) ribonucleoprotein complex formation with 3CDpro and the 5'-terminal cloverleaf of the poliovirus genome; (2) binding to the genomic and negative-sense RNA; (3) stimulation of 3CDpro cleavage; and (4) stimulation of RNA polymerase activity of 3Dpol. The results have allowed mapping of domains important for RNA binding and the formation of certain protein-protein complexes, and correlation of these processes with essential steps in viral genome replication.

3C Viral Proteases↗
PubMed1995

[Antitumor effect of interleukin-2 gene-transfected tumor vaccine in combination with interleukin-6 gene-transfected tumor vaccine].

It has been shown that IL-2 and IL-6 can cooperate to induce immune responses more effectively. In order to increase the therapeutic efficacy of cytokine gene-transfected tumor vaccines, we treated the experimental pulmonary metastatic melanoma-bearing mice with IL-2 gene-transfected tumor vaccine and IL-6 gene-transfected tumor vaccine. After the combined treatment, the pulmonary metastases were reduced more significantly and the survival time of tumor-bearing mice was also prolonged more significantly. The CTL activity, NK activity and IL-2-induced LAK activity, IL-2 and TNF secretion from the splenocytes of the above tumor-bearing mice increased more significantly than that of tumor-bearing mice treated with IL-2 gene-transfected vaccine or IL-6 gene-transfected vaccine alone. These results demonstrated that the combined use of IL-2 gene-transfected tumor vaccine and IL-6 gene-transfected tumor vaccine could achieve more potent antitumor effect via more efficient activation of immune functions. The experiment outlines a novel approach to the cytokine gene therapy of cancer.

Animals↗
PubMed1995

[Pathological studies on the anti-invasive character of IL-6 gene transfected leukemia cells].

FBL-3 Leukemia cells transfected with IL-6 gene were expanded in vitro and inoculated into C57BL/6 mice subcutaneously. Tumor growth was observed and histologic analyses of the tumors in situ and the liver, spleen and bone marrow were performed at 14, 21, 28 and 35 days after inoculation. The mice inoculated with wild-type FBL-3 leukemia cells were used as the control. We found that the tumor invasiveness in the mice inoculated with FBL-3-IL-6+ occurred later than in the control group. The survival time of experimental mice was longer than in the control mice. The results demonstrated that inoculation of IL-6 high-secreting FBL-3 inhibited invasiveness of the leukemia cells, suggesting that the IL-6 gene transfected FBL-3 cells can be used as a vaccine to treat leukemia. The mechanism of the anti-invasiveness of IL-6 gene transfected leukemia cells needs further study.

Animals↗
PubMed1994

Studies with poliovirus polymerase 3Dpol. Stimulation of poly(U) synthesis in vitro by purified poliovirus protein 3AB.

The synthesis in vitro of poly(U) on a poly(A) template with oligo(dT)15 primer by poliovirus RNA polymerase 3Dpol (280 ng/ml) is strongly stimulated (50-100 fold) by the addition of purified poliovirus polypeptide 3AB. The synthesis of product continues linearly with time for up to 90 min. The reaction with 3Dpol alone can be reactivated and similarly enhanced by the addition of 3AB at 30 min of incubation. Optimal stimulation is achieved under conditions where the concentration of 3Dpol and of template is low, when the molar ratio of 3AB to 3Dpol is about 100:1 and that of 3AB to poly(A) is about 25:1. In the presence of 3AB, the yield of product made by 3Dpol is much increased but its size is unchanged. From a number of basic proteins and peptides tested, a few were found which also exhibited limited enhancement of polymerase activity. The stimulatory effect of 3AB is probably related to its ability to bind both the template-primer, poly(A).oligo(dT)15, and 3Dpol (Molla, A., Harris, K. S., Paul, A. V., Shin, S. H., Mugavero, J., and Wimmer, E. J. (1994) J. Biol. Chem. 269, 27015-27020). RNA synthesis on purified poliovirus RNA with oligo(dT)15 primer is enhanced by 3AB about 5-10 fold, and this reaction is highly sensitive to detergent.

Amino Acid Sequence↗
PubMed1994

alpha-Phenyl-tert-butyl-nitrone reduces cortical infarct and edema in rats subjected to focal ischemia.

The neuroprotective effects of the spin-trapping agent alpha-phenyl-N-tert-butyl nitrone (PBN) were evaluated in rats subjected to focal cerebral ischemia produced by permanent middle cerebral artery (MCA) and ipsilateral common carotid artery (CCA) occlusion. PBN was given i.p. at 100 mg/kg at initial times of administration of 0.5 h prior to ischemia (group 2), 0.5 (group 3), 5 (group 4) and 12 h (group 5) after ischemia. Additional doses of PBN (100 mg/kg) were administered as follows: Group 2, at 24 h; Group 3, at 5, 17, 29 and 41 h; Group 4, at 17, 29 and 41 h; Group 5, at 24 and 36 h. Animals were sacrificed 48 h after MCA occlusion and infarct volumes were calculated from triphenyetetrazolium stained 1.5 mm slices of the forebrain. PBN significantly attenuated cortical infarct volume and cerebral edema in all of the treated rats compared with those in ischemic control (group 1) rats, with no significant differences between the different PBN treated groups. The percentage of infarct volume in ischemic control rats was 22.7 +/- 1.0, while those in PBN-treated groups were: 9.6 +/- 2.0, P < 0.01 (group 2); 12.2 +/- 2.2, P < 0.01 (group 3); 11.1 +/- 2.9, P < 0.01 (group 4) and 14.4 +/- 2.5, P < 0.01 (group 5). Furthermore, neurological behavior tests showed that PBN decreased the neurological deficit scores in rats initially treated either prior to or for up to 12 h after ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Amflutizole, a xanthine oxidase inhibitor, inhibits free radical generation in the ischemic/reperfused rat cerebral cortex.

Free radical generation and release from the cerebral hemispheres of rats subjected to four-vessel occlusion elicited cerebral ischemia/reperfusion was monitored using a cortical cup technique with the spin-trapping agent alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN). Electron spin resonance (ESR) was used to detect the presence of free radical adducts of POBN in the cortical superfusates. Thirty min of ischemia plus reperfusion resulted in the release of .OH radical adducts during ischemia and especially in the initial stages of reperfusion. Pretreatment with the xanthine oxidase inhibitor, amflutizole (30 mg/kg) virtually abolished free radical formation and release. These results are consistent with earlier evidence that xanthine oxidase activity contributes to free radical formation in the ischemic/reperfused rat brain.

Animals↗
PubMed1994

Two independent pathways for transcription from the MMTV promoter.

The influence of progesterone receptor (PR) and glucocorticoid receptor (GR) on transcription from the mouse mammary tumour virus (MMTV) promoter was analyzed using cell-free transcription of DNA templates with a G-free cassette. Preincubation of the templates with either PR or GR stimulates the rate of transcription initiation 10-50 fold, whereas the recombinant DNA binding domain of GR is inactive. Mutations that inactivate the nuclear factor I (NFI) binding site, or NFI depletion of the nuclear extract, decrease basal transcription without influencing receptor-dependent induction. Recombinant NFI, but not its DNA-binding domain, restores efficient basal transcription of the depleted extract. Recombinant OTF1 or OTF2, but not the POU domain of OTF1, enhance MMTV transcription independently of NF1. In agreement with this finding, NFI and OTF1 do not cooperate, but rather compete for binding to the wild type MMTV promoter, though they have the potential to bind simultaneously to properly oriented sites. Our results imply the existence of two independent pathways for MMTV transcription: one initiated by NFI and the other dependent on octamer transcription factors. Only the second pathway is stimulated by steroid hormone receptors in vitro.

Base Sequence↗
PubMed1994

The effect of amflutizole, a xanthine oxidase inhibitor, on ischemia-evoked purine release and free radical formation in the rat cerebral cortex.

The efflux of hypoxanthine, xanthine and uric acid into cortical superfusates was studied with the cortical cup technique in the rat. Twenty minutes of four vessel occlusion followed by reperfusion results in a massive increase in the efflux of these purine metabolites. Amflutizole, 10 microM administered topically into the cortical cups, enhanced the ischemia-evoked release of hypoxanthine while it suppressed xanthine formation. Uric acid levels were not affected. Amflutizole also eliminated the ischemia/reperfusion-evoked generation of free radical adducts of alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) detected by electron spin resonance. These results are consistent with a block of xanthine oxidase by amflutizole and support the involvement of xanthine oxidase in free radical mediated tissue damage following ischemia/reperfusion.

Animals↗
PubMed1994

Modulation of autonomic responses in normal and denervated isolated canine atria by substance P.

The experiments were performed to determine whether the neuromodulatory effect of substance P (SP) could be demonstrated in the isolated atrium. Strips from the right (RA) and left atria (LA) of normal (control) and denervated canine hearts were placed in an isolated muscle bath, and isometric muscle tension was measured. Inotropic responses to direct muscarinic stimulation were obtained with 1 x 10(-9) to 1 x 10(-8) M acetylcholine (ACh), and responses to stimulation of the intramyocardial intrinsic cardiac nerves (ICN) were produced with nicotine (Nic), 1.0-10 x 10(-6) M. The same drugs were tested in the presence of 1 x 10(-6) M SP, which had no significant inotropic effects of its own. Responses to ACh were unaffected by SP. The primary negative inotropic response to Nic was greatly attenuated by SP in both control and denervated atria, whereas the secondary positive response in control atria was unaffected. This inhibition was very pronounced in LA but less so in the RA. We conclude that SP appears to modulate the responses of the ICN to nicotinic stimulation in a manner similar to that previously observed in intact animals. This mechanism may provide a means of direct modification of efferent cardiac responses by afferent nerves within the heart itself.

Acetylcholine↗
PubMed1994

1,25-Dihydroxyvitamin D3 transcriptionally activates the beta 3-integrin subunit gene in avian osteoclast precursors.

Osteoclasts are polykaryons and the principal, if not exclusive, resorptive cell of bone. They are members of the monocyte/macrophage family whose precursors differentiate under the influence of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. Bone resorption is dependent on osteoclast-bone attachment, and we have shown that the integrin alpha v beta 3 is critical to the resorptive process. Thus, we asked whether 1,25-(OH)2D3 enhances the expression of alpha v beta 3 on the surface of osteoclast precursors and if the steroid modulates expression of the beta 3-integrin subunit. We found that 1,25-(OH)2D3 promotes the plasma membrane appearance of alpha v beta 3 on avian bone marrow-derived osteoclast precursors and does so at physiological concentrations (10(-11) M) of the steroid. The effect is time dependent, appearing within 1 day of treatment. A full-length avian cDNA was cloned to explore the molecular mechanisms of beta 3 expression. The deduced amino acid sequence of the cDNA is 81% identical and 89% similar to that of human beta 3. Northern analysis demonstrates that beta 3 mRNA levels in vitamin D-treated osteoclast precursors mirror protein expression. Nuclear run-on experiments document the transcriptional nature of the event.

Amino Acid Sequence↗
PubMed1994

[Study on soluble proteins in human fetal lens].

Soluble proteins from corter of human fetal clear lenses were separated by column chromatography with Sepharyl S-300 (superfine) and determined by disc-PAGE and SDS-PAGE. The results documented from 18W, 21W (2 cases) and 24W fetal lenses suggested that a negative correlation tended to be presented between the age of fetus and fraction of alpha, beta 1 crystallins (r = -0.9542; r = -0.9674) and a positive correlation between the age of fetus and fraction of beta 2, gamma crystallins (r = 0.9666; r = 0.9970). There was no change in the alpha, beta 1, beta 2 crystallins on disc-PAGE. Among the fetuses of different ages, the blurred band of gamma crystallin seen in 18W and 21W fetal lenses was thickened in the 24W fetal lens. The SDS-PAGE showed that there was no significant difference among the polypeptides in each of alpha, beta 1, beta 2, gamma crystallins in the studied fetal lenses of different age groups. It is presumed that the normal lens is proportionally composed of four fractions of crystallin. This is hypothetically contributed to the maintenance of normal structure of the lens, why the proper proportion of four fractions of crystallins is depended either on proteins synthesis or on protein molecular assembly is not yet clear.

Chromatography, Gel↗
PubMed1994

The biological study of the cultured human lens epithelial cells in vitro.

The human lens epithelial cells (HLE) cultured in vitro was established in normal and cataractous lenses. The biological feature, histological characteristics and the ultrastructure of the cultured HLE cells were investigated. The results reveal that the proliferative capacity of the cultured HLE cells is reversely proportional to the donor age; the cultured HLE cells has the limited proliferative capacity in vitro. The relieve of the contact inhibition is the effective trigger of the HLE cell proliferation. This research work is possible to make a basis for the further study of the regeneration of the lens and the roles of the lens epithelial cells in the development of the cataract.

Adolescent↗