Biomedical subjects

C Gao

Publications and source records attributed to C Gao.

At least 55 records · Page 3Linked to original sources

PubMed2001

[Phosphorus sorption and desorption of agricultural soils under different land uses].

The potential of P loss from soils under different land uses in Taihu Lake watershed was evaluated by laboratory experiment. It was shown that although the P sorption capacity of paddy soils under oxidized conditions were little lower than that of dryland soils the risks of P loss from the former via runoff and leaching were lower than that from the latter, because the soil P levels of the former were much lower than that of the latter. For most paddy soils the P sorption capacity increased and the P release decreased under reduced conditions than that under oxidized conditions and this was attributed to the formation of amorphous Fe2+ hydroxides which have a greater surface area and more P sorption sites than well-crystallized Fe3+ oxides.

Adsorption↗

PubMed2001

The roles of the N-terminal portions of various tachykinins in promoting salivation.

OBJECTIVES: In order to determine the active sites for salivation of various tachykinins, the regulatory roles of the N-terminal portion of various newly-synthesized tachykinins were studied after i.p. injection of rats using the submandibular glands as model organs. METHODS: N-shortened oligopeptides from kassinin, eledoisin, neurokinins A (NKA) and NKB were synthesized by the multipin peptide synthesis method. Amino acids were eliminated one by one to form octa- to undeca-peptides adjoining the inactive or less active heptapeptides and various heptapeptides, in which an amino acid in position 8 (Xaa8), numbering as in an undecapeptide, was replaced with Tyr, Phe, Ile or Val. RESULTS: The N-terminal amino acids in positions 1 to 4 could be activators or inhibitors, depending on whether the C-terminal heptapeptide was inactive or less active. The Xaa8 residue, in combination with amino acids in positions 5 and 6, seemed to be very important in determining the sialogogic activity of a heptapeptide. The discrimination between NKA and NKB appeared due to the N-terminal amino acid sequence in positions I to 4 including Phe or Ser in position 6. CONCLUSIONS: It is concluded that the N-terminal amino acids in positions I to 4 serve as either activators or inhibitors depending upon the sialogogic activity of the C-terminal heptapeptide, in which particular amino acids in positions 5, 6 and 8 regulate its activity.

Analysis of Variance↗

PubMed2001

[The role of AT1 receptor and cyclin kinase inhibitor p27 protein in angiotensin II-induced hypertrophy of mesangial cell].

OBJECTIVE: To investigate the role of p27 and AT1 receptor in the hypertrophy of mesangial cell (MC) induced by angiotensin II (Ang II). METHODS: p27 protein of MC lysate was detected with Western blotting analysis. The degree of cultured MC hypertrophy was estimated through [3H] thymidine incorporation and [3H] leucine incorporation. The effect of reducing p27 expression on cell hypertrophy was analysed with p27 antisense oligodeoxynucleotide (ODN) phosphorothioate. The extracellular matrix (ECM) protein (type IV collagen and fibronectin) of MC lysate was examined with ELISA. RESULTS: Ang II stimulated p27 expression of MC cultured in normal glucose DMEM. MC stimulated by Ang II revealed hypertrophy as well as increased [3H] leucine incorporation, decreased [3H] thymidine incorporation and increased ECM. p27 antisense ODN transfection abolished the effect of Ang II mentioned above. Losartan lowered p27 level of MC stimulated by Ang II and attenuated MC hypertrophy induced by Ang II; meanwhile [3H] leucine incorporation and ECM level decreased, [3H] thymidine incorporation increased. The effect of Losartan was dose-dependent. CONCLUSION: Ang II induced MC hypertrophy by increasing p27 protein level through AT1 receptor. Because the cell cycle is controlled by the interplay between the positive and negative cell cycle regulatory proteins (CCRP), further research is needed to study the expression of the positive and negative CCRP in MC in order to understand better the role of CCRP in MC hypertrophy induced by Ang II.

Angiotensin II↗

PubMed2001

Detailed deletion mapping on chromosome region 9p21 in human periampullary neoplasms.

OBJECTIVE: To further define the extent of chromosome 9p21 deletion in periampullary neoplasms. METHODS: The loss of heterozygosity at 5 microsatellite polymorphic markers on chromosome 9p21 was detected by polymerase chain reaction (PCR), polyacrylamide gel electrophoresis (PAGE) and silver staining in 35 specimens of periampullary neoplasms and their matching blood samples. RESULTS: Fifty percent (4/8) of pancreatic cancer cases showed the loss of heterozygosity at one or more microsatellite loci, with the more frequent sites of D9S974 (37.5%) and D9S942 (28.6%), and some showing consecutive allelic loss. Sixty-two point five percent (5/8) of ampullary carcinoma cases showed loss of heterozygosity at one or more of the loci, frequent site of loss being D9S942 (42.9%) and the next most frequent being IFNA (37.5%) and D9S171 (37.5%). Loss of one locus was observed in 14.2% (1/7) of insulinoma. CONCLUSION: The minimal common region of chromosome deletion in periampullary neoplasms is defined between the D9S974 and D9S942 loci within a 15 kb interval in 9p21, suggesting the involvement of a novel tumor suppressor gene in their carcinogenesis.

Adolescent↗

PubMed2001

[Biomaterials used in tissue engineering for cartilage regeneration].

In this paper are reviewed the research reports on biomaterials used in recent years in the field of tissue engineering for cartilage regeneration. The preparation of these biomaterials are also discussed. Finally, ideas are proposed to solve the problems in the field of cartilage tissue engineering.

Biocompatible Materials↗

PubMed2001

[Non-filamentous activated sludge bulking caused by the deficiency of nitrogen].

The effect of nitrogen deficiency on activated sludge bulking was studied specially in some experiments carried on a sequencing batch reactor fed with beer wastewater in this paper. The experimental results showed that the sludge settled properly at a influent BOD/N value of 100/4. When the value of BOD/N was 100/3 and 100/2 respectively, non-filamentous activated sludge bulking caused by an excessive growth of viscous Zoogloea with high moisture content occurred. When the value of influent BOD/N was 100/0.94, more serious non-filamentous bulking occurred. Furthermore, the effect of nitrogen deficiency on the nitrogen sources and phosphorus sources utilization rate and the COD removal rate was studied in the experiments.

Bacteria↗

PubMed2001

[Modulation of the activity of human alpha1 (I) procollagen gene promoter by basic fibroblast growth factor (bFGF)].

OBJECTIVE: To investigate the modulating effect of bFGF on the proliferation of human cutaneous fibroblasts and on the activity of human alpha1 (I) procollagen gene promoter. METHODS: Human cutaneous fibroblasts were cultured and subcultured by tissue block culture technique. The influence of different concentrations of bFGF on the proliferation of fibroblasts was determined by ELISA method with BrdU incorporated into fibroblast DNA. Three plasmids containing various lengths of 5prime prime or minute flank sequences of human alpha1 (I) procollagen gene and CAT as reporter gene were constructed and transfected into the fibroblasts by FuGENE transfection reagent. The quantitative expression of the fibroblast CAT was determined by ELISA after treatment with bFGF. RESULTS: After 24 hours of treatment of the fibroblasts by serial concentrations (0.25 ng/ml similar 64.00 ng/ml) of bFGF in DMEM containing 2% (v/v) or 10% (v/v) FCS, the BrdU incorporation into DNA was determined. The proliferating rate of the fibroblasts differed significantly from each other in all the groups (P < 0.05). After the fibroblasts were transfected with the three plasmids and treated thereafter by 4 ng/ml and 16 ng/ml of bFGF for 24 hours, the relative CAT expression values were determined. It indicated that the expression value was evidently different between bFGF processing and control groups (P < 0.05). CONCLUSION: bFGF might inhibit the proliferation of human cutaneous fibroblasts and exert negative regulating effect on the human alpha1 (I) procollagen gene promoter sequence in dose -- dependent pattern.

Cell Division↗

PubMed2001

[The effects of astragalus and shenmai injections on macrophage function in burned mice].

OBJECTIVE: To explore the dynamic postburn change in macrophage function in burned mice within 120 hrs after injury, and to investigate the effects of astragalus and shenmai injections on the macrophage function and surrvival rate of burned mice. METHODS: The mice were divided into 13 groups according to postburn time and handling methods, i,e, normal control (A), burn control (B), normal mice with astragalus (NA), normal mice with shenmai (NS), burned mice with astragal (BA), burned mice with shenmai (BS) 2 postburn hour (2 PBH), 6 PBH, 12 PBH, 24 PBH, 48 PBH, 72 PBH, 120 PBH groups. The changes in the various macrophage functions at different postburn time points and after the use of astragalus and shenmai injections were determined by means of phagocytic and RT-PCR methods. RESULTS: (1) Within 120 PBHs, the phagocytic function of murine macrophages decreased evidently. The ACP activity decreased obviously. The expression of IL-15 mRNA fluctuated and that of TNF mRNA enhanced significantly. (2) Five days after the application of astragalus in dose of 2 500 mg . kg(-1) .d(-1), the phagocytic function of macrophages and ACP activity increased markedly (P < 0.01). The expressions of IL-15 and TNF mRNAs were not influenced. The survival rate of mice was not increased. (3) Five days after the application of shenmai injection in dose of 2.5 ml . kg(-1) . d(-1), the phagocytic function of macrophages and ACP activity increased significantly (P < 0.01), while the expression of IL-15 mRNA exhibited no change. But the expression of TNFalpha mRNA decreased obviously (P < 0.01). Moreover, the survival rate of burned mice was evidently raised (P < 0.05). CONCLUSION: Peritoneal administration of shenmai injection at early postburn stage could significantly improve the macrophage function of burned mice, and it increase the survival rate of mice.

Acid Phosphatase↗

PubMed2001

[Construction of Ag85B DNA vaccine for Mycobacterium tuberculosis and its immunogenicities].

OBJECTIVE: To construct pcDNA3-Ag85B recombinant and evaluate its immunogenicity and types of immune response induced by recombinant pcDNA3-Ag85B. METHODS: Ag85B gene of Mycobacterium tuberculosis was inserted into pcDNA3 to construct DNA vaccine pcDNA3-Ag85B. BALB/c mice were intramuscularly immunized with DNA vaccine, saline and pcDNA3, respectively. The levels of anti-Ag85B antibody were examined with ELISA and the transcripts of IL-2, IL-4, IL-10 and IFN-gamma of spleen lymphocytes stimulated with recombinant Ag85B were tested with RT-PCR at the end of 6th week of inoculation. RESULTS: Compared with control group, the specific antibody levels against Ag85B were much higher and the IL-2 and IFN-gamma transcripts were up regulated in the pcDNA3-Ag85B group. There was no change of IL-4 and IL-10 expressions in three groups. CONCLUSION: The pcDNA3-Ag85B stimulated the specific antibody products and induced the Th1 type cell immunity.

Animals↗

PubMed2001

[Simultaneous determination of cobalt and nickel in catalyst by microwave digestion-dual wavelength equal absorption spectrophotometry].

Catalyst samples are digested in a microwave digestion system. The optimum parameters for microwave digestion are selected. Cobalt and nickel in the mixture of Co2+ and Ni2+ with 4-(2-pyridylazo) resorcinol (PAR) can be determined simultaneously by dual-wavelength equal absorption spectrophotometry. By means of the combination of two methods, Co2+ and Ni2+ in catalyst can be determined rapidly, accurately, and contamination problems avoided. The linear ranges are 0-30 micrograms.25 mL-1 for Co2+ and 0-25 micrograms.25 mL-1 for Ni2+. The recoveries of Co2+ and Ni2+ in synthetic samples are between 98.2%-103.6% and between 97.9%-103.7%, respectively. The relative standard deviations of analytical results in catalyst samples are less than 2.2% for Co2+ and less than 1.8% for Ni2+, and relative errors are less than +/- 2.5% for Co2+ and Ni2+.

Catalysis↗

PubMed2000

p53-dependent induction of heat shock protein 27 (HSP27) expression.

Transcriptional activation of the p53 target genes plays a critical role in the cellular response to DNA damage, hypoxia, cellular stress and other signals regulating the cell cycle and apoptosis. The discovery of new p53 target genes continues to reveal novel mechanisms of action of this multifaceted protein. We used cDNA arrays to search for p53-regulated genes in prostate cancer cells. In this report, we describe robust induction of heat shock protein 27 (hsp27) in prostate cancer cells (DU145, LNCaP, PC3) following wild-type p53 expression from an adenoviral p53 expression vector (AdWTp53). A mutant p53 (R175H)-containing adenoviral expression vector did not induce hsp27. hsp27 expression was not altered in prostate cancer cells following expression of cyclin-dependent kinase inhibitors: p21(waf1/cip1) and p27(kip1) from adenoviral expression vectors. Treatment of cells with staurosporine, an apoptosis-inducing agent, did no affect hsp27 expression. These observations provide evidence that induction of hsp27 expression was wild-type p53-specific and was not due to non-specific effects of cell growth arrest and/or apoptosis. Previous studies and the experiment reported here show induction of hsp27 expression in response to androgen ablation, a physiological state that induces apoptosis in prostatic epithelial cells. The nature of p53 and hsp27 interactions in the regulation of apoptosis and/or cell growth needs to be further defined.

Adenoviridae↗

PubMed2000

Histamine H3 receptor-mediated suppression of inhibitory synaptic transmission in the submucous plexus of guinea-pig small intestine.

Conventional intracellular microelectrodes and marker injection techniques were used to study the actions of histamine on inhibitory synaptic transmission in the submucous plexus of guinea-pig small intestine. Bath application of histamine (1-300 microM) reversibly suppressed both noradrenergic and non-adrenergic slow inhibitory postsynaptic potentials in a concentration-dependent manner. These effects of histamine were mimicked by the selective histamine H(3) receptor agonist R(-)-alpha-methylhistamine but not the selective histamine H(1) receptor agonist, 6-[2-(4-imidazolyl)ethylamino]-N-(4-trifluoromethylphenyl) heptanecarboxamide (HTMT dimaleate), or the selective histamine H(2) receptor agonist, dimaprit. The histamine H(3) receptor antagonist, thioperamide, blocked the effects of histamine. Histamine H(1) and H(2) receptor antagonists did not change the action of histamine. Hyperpolarizing responses to focal application of norepinephrine or somatostatin by pressure ejection from micropipettes were unaffected by histamine and R(-)-alpha-methylhistamine. The results suggest that histamine acts at presynaptic histamine H(3) receptors on the terminals of sympathetic postganglionic fibers and intrinsic somatostatinergic nerves in the small intestine to suppress the release of the inhibitory neurotransmitters, norepinephrine and somatostatin.

Animals↗

PubMed2000

Use of terminal transferase-dependent antisense RNA amplification to determine the transcription start site of the Snrpn gene in individual neurons.

We describe here a very sensitive technique for RNA structure analysis and the determination of transcription start sites and demonstrate its use for mapping the start site of the imprinted Snrpn gene in individual hippocampal neurons. The method is adapted from reverse transcription-terminal transferase-dependent PCR (RT-TDPCR) to include amplification of the antisense sequence by in vitro transcription just prior to the final PCR step. The method should be useful for analysis of all genes for which variation in promoter usage and/or differences in RNA secondary structure may be specific to a given cell type or developmental stage.

Animals↗

PubMed2000

p53 regulates the expression of the tumor suppressor gene maspin.

Maspin has been shown to inhibit tumor cell invasion and metastasis in breast tumor cells. Maspin expression was detected in normal breast and prostate epithelial cells, whereas tumor cells exhibited reduced or no expression. However, the regulatory mechanism of maspin expression remains unknown. We report here a rapid and robust induction of maspin expression in prostate cancer cells (LNCaP, DU145, and PC3) and breast tumor cells (MCF7) following wild type p53 expression from an adenovirus p53 expression vector (AdWTp53). p53 activates the maspin promoter by binding directly to the p53 consensus-binding site present in the maspin promoter. DNA-damaging agents and cytotoxic drugs induced endogenous maspin expression in cells containing the wild type p53. Maspin expression was refractory to the DNA-damaging agents in cells containing mutant p53. These results, combined with recent studies of the tumor metastasis suppressor gene KAI1 and plasminogen activator inhibitor 1 (PAI1), define a new category of molecular targets of p53 that have the potential to negatively regulate tumor invasion and/or metastasis.

Adenoviridae↗

PubMed2000

Delivery of a retroviral vector expressing human beta-glucuronidase to the liver and spleen decreases lysosomal storage in mucopolysaccharidosis VII mice.

Mucopolysaccharidosis VII (MPS VII) is caused by beta-glucuronidase (beta-gluc) deficiency and results in lysosomal storage due to the inability to degrade glycosaminoglycans. Transfer of a beta-gluc gene into the liver reduces hepatic pathology as well as storage in other organs via uptake of secreted protein. A Moloney murine leukemia-based retroviral vector expressing the human beta-gluc cDNA was injected intravascularly into MPS VII mice during hepatocyte replication, which was induced with im injection of an adenoviral vector that transiently expressed hepatocyte growth factor (Ad.CMV. HGF). This procedure resulted in transduction of approximately 1% of hepatocytes, 1% of normal liver enzyme activity, and a reduction in lysosomal storage in the liver at 3.5 months. Surprisingly, controls that received retroviral vector without HGF had transduction of nonparenchymal cells in the liver, significant levels of enzyme and RNA in the liver at 2 but not 3.5 months, and reduced lysosomal storage at 3.5 months. Transduction was also achieved in the replicating cells of the spleen, where lysosomal storage was reduced. An approach using a retroviral vector without a growth factor might temporarily reduce lysosomal storage in the liver and spleen in humans. Addition of HGF might be used to augment and prolong gene transfer.

Animals↗

PubMed2000

Biomechanical and morphological properties in rat large intestine.

Intestinal stress-strain distributions are important determinants of intestinal function and are determined by the mechanical properties of the intestinal wall, the physiological loading conditions and the zero-stress state of the intestine. In this study the distribution of morphometric measures, residual circumferential strains and stress-strain relationships along the rat large intestine were determined in vitro. Segments from four parts of the large intestine were excised, closed at both ends, and inflated with pressures up to 2kPa. The outer diameter and length were measured. The zero-stress state was obtained by cutting rings of large intestine radially. The geometric configuration at the zero-stress state is of fundamental importance because it is the basic state with respect to which the physical stresses and strains are defined. The outer and inner circumferences, wall thickness and opening angle were measured from digitised images. Subsequently, residual strain and stress-strain distributions were calculated. The wall thickness and wall thickness-to-circumference ratio increased in the distal direction. The opening angle varied between approximately 40 and approximately 125 degrees with the highest values in the beginning of proximal colon (F=1.739, P<0.05). The residual strain at the inner surface was negative indicating that the mucosa-submucosal layers of the large intestine in no-load state are in compression. The four segments showed stress-strain distributions that were exponential. All segments were stiffer in longitudinal direction than in the circumferential direction (P<0.05). The transverse colon seemed stiffest both in the circumferential and longitudinal directions. In conclusion, significant variations were found in morphometric and biomechanical properties along the large intestine. The circumferential residual strains and passive elastic properties must be taken into account in studies of physiological problems in which the stress and strain are important, e.g. large intestinal bolus transport function.

Animals↗

PubMed2000

Histomorphometry and strain distribution in pig duodenum with reference to zero-stress state.

The morphometry at no-load and zero-stress states and residual circumferential strains were determined along the pig duodenum in vitro in seven pigs. The no-load state was obtained by cutting eleven 2-mm-wide rings at 10% intervals along the duodenum. The zero-stress state was obtained by cutting the rings radially. The zero-stress state provides a standard morphological state to describe tissue since internal and external forces do not affect the tissue. The morphometric measures were obtained from digitized images, and the layer thicknesses were measured from histological sections. The mucosal and serosal circumferences, the wall thickness, and the wall thickness-to-mucosal radius ratio were largest in the proximal end of the duodenum (f > 1.9, P < 0.05). The thickness of the submucosal stratum compactum layer and the opening angle increased in distal direction (f = 2.3, P < 0.05 and = 6.5, P < 0.001). The residual strain at the mucosal surface was negative, indicating that the mucosa-submucosa layers of duodenum in no-load state are in compression. Distension experiments showed that the residual strain makes the stress distribution through the wall more uniform in the pressurized state. In conclusion, the large circumferential residual strains must be taken into account in the study of physiological problems, in which the stresses and strains are important, eg, the bolus transport function.

Animals↗

PubMed2000

Hepatocyte transplantation in rats with decompensated cirrhosis.

Hepatocyte transplantation improves the survival of laboratory animals with experimentally induced acute liver failure and the physiological abnormalities associated with liver-based metabolic deficiencies. The role of hepatocyte transplantation in treating decompensated liver cirrhosis, however, has not been studied in depth. To address this issue, cirrhosis was induced using phenobarbital and carbon tetrachloride (CCL(4)) and animals were studied only when evidence of liver failure did not improve when CCL(4) was held for 4 weeks. Animals received intrasplenic transplantation of syngeneic rat hepatocytes (G1); intraperitoneal transplantation of syngeneic rat hepatocytes (G2); intraperitoneal transplantation of a cellular homogenate of syngeneic rat hepatocytes (G3); intraperitoneal transplantation of syngeneic rat bone marrow cells (G4); or intrasplenic injection of Dulbecco's modified Eagle medium (DMEM) (G5). After transplantation, body weight and serum albumin levels deteriorated over time in all control (G2-G5) animals but did not deteriorate in animals receiving intrasplenic hepatocyte transplantation (G1) (P <.01). Prothrombin time (PT), total bilirubin, serum ammonia, and hepatic encephalopathy score were also significantly improved toward normal in animals receiving intrasplenic hepatocyte transplantation (P <. 01). More importantly, survival was prolonged after a single infusion of hepatocytes and a second infusion prolonged survival from 15 to 128 days (P <.01). Thus, hepatocyte transplantation can improve liver function and prolong the survival of rats with irreversible, decompensated cirrhosis and may be useful in the treatment of cirrhosis in humans.

Animals↗