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Biomedical subjects

S Cai

Publications and source records attributed to S Cai.

At least 37 records · Page 2Linked to original sources
PubMed2001

Characterization of the prfA virulence gene cluster insertion site in non-hemolytic Listeria spp.: probing the evolution of the Listeria virulence gene island.

The prfA virulence gene cluster is present between prs and ldh in the pathogenic L. monocytogenes and L. ivanovii, but absent from the non-pathogenic L. innocua and L. welshimeri. To probe the evolution of this virulence gene cluster, we sequenced the prs-ldh intergenic region in L. welshimeri and L. innocua. Two ORFs (ORFA and ORFB) were found in both species as well as in L. monocytogenes. Another ORF of unknown function (ORFZ) was found in L. monocytogenes and L. innocua, while two unique ORFs were present in L. welshimeri. ORFA and ORFB showed significant functional constraint, suggesting that further investigations in the functions of these genes, including possible roles in horizontal gene transfer or sequence deletion, are warranted. DNA sequences homologous to Tn1545 integration consensus sequences were found downstream of prs and ORFB, thus defining the likely junctions of the virulence gene island and indicating that the prs-ldh intergenic region may represent a Tn insertion hot spot. Our results are consistent with the hypothesis that a combination of horizontal gene transfer and deletion events mayhave been involved in the evolution of the prfA virulence gene cluster in Listeria.

Animals↗
PubMed2001

Subgingival occurrence and antimicrobial susceptibility of enteric rods and pseudomonads from Brazilian periodontitis patients.

The occurrence and in vitro antimicrobial sensitivity of isolates of enteric rods and pseudomonads were examined in 80 periodontitis patients, 17 to 58 years of age, in São Paulo, Brazil. Speciation and in vitro antimicrobial susceptibility testing were performed using the BBL Crystal enteric/nonfermenter system and the Etest for amoxicillin/clavulanic acid, ciprofloxacin and doxycycline. A total of 30 strains were isolated from 25 (31.2%) of the study subjects. Pseudomonas aeruginosa occurred in nine patients, Serratia marcescens in seven, and five other species were recovered in lower prevalence. All study organisms demonstrated high susceptibility to ciprofloxacin but exhibited variable susceptibility patterns to the other antimicrobial agents tested. In conclusion, the high occurrence of enteric rods and pseudomonads in these subjects may be important in the pathogenesis of periodontitis, and ciprofloxacin might be the antibiotic of choice to eradicate these pathogens from periodontal pockets.

Adolescent↗
PubMed2001

Phylogenetic analysis based on 18S rRNA gene and matK gene sequences of Panax vietnamensis and five related species.

Panax vietnamensis was discovered recently in Vietnam. Its bamboo-like rhizomes, called Vietnamese Ginseng, have attracted considerable attention because of their specific pharmacological activities. In order to define the taxonomic position of this new species and include it in the molecular authentication of Ginseng drugs, the 18S ribosomal RNA gene and matK gene sequences of P. vietnamensis were determined and compared with those of its related taxa, P. japonicus var. major and P. pseudo-ginseng subsp. himalaicus, besides previously reported P. ginseng, P. japonicus and P. quinquefolius. The 18S rRNA gene sequences were found to be 1809 bps in length. The sequence of P. vietnamensis was identical to that of P. quinquefolius, and presented one base substitution from those of both P. japonicus var. major and P. pseudo-ginseng subsp. himalaicus. The matK gene sequences of 6 taxa were found to be 1509 bps in length. The sequence of P. vietnamensis differed from those of P. japonicus var. major, P. pseudo-ginseng subsp. himalaicus, P. ginseng, P. japonicus and P. quinquefolius at 4, 5, 9, 9 and 10 nucleotide positions, respectively. The phylogenetic tree reconstructed by the combined 18S rRNA-matK gene analysis using the maximum parsimony method showed that P. vietnamensis was sympatric with other Panax species and had a close relationship with P. japonicus var. major and P. pseudo-ginseng subsp. himalaicus.

Amino Acid Sequence↗
PubMed2001

Tumor necrosis factor modulates fibroblast apoptosis, PMN recruitment, and osteoclast formation in response to P. gingivalis infection.

P. gingivalis is an important oral pathogen, which has been closely linked to periodontal disease as well as lesions of endodontic origin. Both infections are associated with a decrease in fibroblast numbers, formation of an inflammatory infiltrate, and bone resorption. The goal of this study was to investigate the role that the host response plays in the capacity of P. gingivalis to stimulate fibroblast apoptosis, PMN recruitment, and osteoclastogenesis. This was accomplished by the use of an in vivo calvarial model in mice with targeted deletion of TNF receptors p55 and p75 and matched wild-type mice. The results indicate that P. gingivalis induces fibroblast apoptosis in vivo and establish for the first time that this involves the stimulation of a host response. Moreover, bacteria-stimulated PMN recruitment and osteoclastogenesis were also dependent upon the host response. The results suggest that much of the damage caused by P. gingivalis infection, including fibroblast apoptosis, at least under some circumstances, results from stimulation of the host response rather than the direct effect of bacterial products. Furthermore, this may represent a more general mechanism by which bacterial challenge induces apoptosis of matrix-producing cells through the induction of TNF.

Animals↗
PubMed2001

Investigation on the rheological properties of hepatocellular carcinoma cells and their relevance to cytoskeleton structure.

OBJECTIVE: To investigate the relevance of the rheological properties, i.e., viscoelasticities and adhesion to basement membrane components coated surface, of both hepatocytes and hepatocellular carcinoma (HCC) cells to the cytoskeleton structure. METHODS: Micropipette aspiration technique was adopted to measure viscoelastic coefficients and adhesion forces to 2 microg/ml collagen IV/1.25 microg/ml laminin coated surface of the cells. Two kinds of cytoskeleton perturbing agents, colchicine and cytochalasin D, were used to treat both HCC cells and hepatocytes and the effects of these treatments on cell viscoelastic coefficients and cell adhesion forces were investigated. RESULTS: Upon treatment of cells with colchicine in a concentration range of 1 to 60 mg/L, the elastic coefficients, especially the first elastic coefficient K1, and adhesion forces of hepatocytes generally tended to increase or increased significantly while, in contrast, viscoelastic coefficients and adhesion forces of HCC cells decreased obviously. Upon treatment of cells with cytochalasin D in a concentration range of 0.25-5.00 mg/L, viscoelastic coefficients of both hepatocytes and HCC cells decreased uniformly, with a larger magnitude for the decrease in elastic coefficients and adhesion forces of HCC cells than for those of hepatocytes. Adhesion forces of hepatocytes and HCC cells onto collagen IV/laminin coated surface varied similarly as viscoelastic coefficients under the action of the cytoskeleton perturbing agents. A significant positive correlation existed between changes of HCC cell adhesion forces on collagen IV/laminin coated surfaces and those of cell elastic coefficients (P<0.01). CONCLUSIONS: The effects of cochicine and cytochalasin D on rheological properties of HCC cells differed significantly either in ways or extents from those on rheological properties of hepatocytes. These results might reflect the difference in the state of cytoskeleton structure and function among these two kinds of cells.

Carcinoma, Hepatocellular↗
PubMed2001

[Investigation on the mechanics of adhesion to the selective extracellular matrix coated surfaces of lung cancer cells].

The adhesion properties of tumor cells with extracellular matrix(ECM) are closely associated with their invasion and metastasis. Our work reported here was intended reveal the relevant biomechanical and biorheological manifestations of human lung cancer. Using micropipette aspiration technique, we investigated quantitatively the adhesive mechanics properties of high metastatic human giant cell carcinoma(PG) cells as well as low metastatic adenocarcinoma(PAa) cells of lung based on cell culture in vitro. The results showed that the adhesion forces of PAa and PG cells to collagen IV were significantly higher than those to glass surfaces, but at the lower concentrations(1.00 microgram/ml and 2.00 micrograms/ml) of collagen IV, the amplitude for the increase of adhesion forces of PG cells were less than the amplitude for that of PAa cells, and most of the adhesion force values of PAa cells to the coated surfaces of incorporation of laminin along with 2 micrograms/ml collagen IV were significantly greater than those of PG cells. At the lower concentrations(0.625 microgram/ml for PAa cells, and 0.625 microgram/ml, 1.25 micrograms/ml for PG cells) of laminin tested, the adhesion force values of PAa and PG cells all decreased, but the amplitude and level for the decreased values of adhesion forces of PG cells were greater than those for the PAa cells. In conclusion, the adhesive and proteolytic behaviour of cancer cells to extracellular matrix might be mediated mainly by tumor cell membrane receptors such as integrin receptors and laminin receptors, it might affect the biological characteristics and the metastasis of the tumor cells. The results may benefit to explain some questions in biomechanical views about how the highly metastatic PG cells are prone to migration and invasion.

Adenocarcinoma↗
PubMed2001

[Effects of surface pattern of polymers on adhesion characteristics of transformed human embryonic tendon cells].

Effects of surface pattern of polymers on adhesion characteristics of transformed human embryonic tendon cells (THETCs) have been examined by using a micropipette aspiration technique, which is a cellular mechanical method. The results showed that the adhesion characteristics of THETCs depend on the surface pattern of polymers, and the adhesion force of THETCs to porous films is higher than that to non-porous films and fibers. The adhesion force bears relationships with the aperture of porous films and has a stronger dependence on the large aperture (150-500 microns) than on the small aperture (< 150 microns) of porous films. The adhesion force of THETCs to fibers is increased slightly with the diameter of fibers (P > 0.05). These demonstrate that the tissue-engineered tendon scaffolds made of porous polymer foam with specially designated aperture, or of polymer fiber with specially designated diameter, may serve as a good attachment substrate for THETCs.

Biopolymers↗
PubMed2001

Telomerase activity and homozygous deletions of the p16 gene in liver metastases of colorectal carcinoma.

OBJECTIVE: To study the interaction between telomerase activity and abnormalities of the p16 gene in liver metastases of colorectal carcinoma. METHODS: Telomerase activity was detected by a non-isotopic PCR-based telomeric repeat amplification protocol (TRAP) assay, and homozygous deletions of the p16 gene were detected by a semiquantitative multiplex polymerase chain reaction in tissue samples from 24 liver metastases of colorectal carcinoma and 5 primary colorectal carcinomas. RESULTS: Telomerase activity was observed in 19 (79.2%) of 24 liver metastases of colorectal carcinoma. Telomerase activity was also observed in all 5 primary colorectal carcinomas and in 3 of their liver metastatic samples. The incidence of telomerase activity in liver metastases of colorectal carcinoma was not significantly correlated to tumor diameter, number of tumors, cirrhosis, and HBsAg. Homozygous deletions of the p16 gene were found in 9 of 24 (37.5%) liver metastases of colorectal carcinoma. Homozygous deletions of the p16 gene were observed in 2 of the 5 primary colorectal carcinomas and in 1 of the matching liver metastatic cancers. There was a correlation between telomerase activity and homozygous deletions of the p16 gene. CONCLUSIONS: There is a correlation between telomerase activity and homozygous deletions of the p16 gene in liver metastases of colorectal carcinoma, suggesting its crucial role in liver metastases. However, telomerase activation and homozygous deletions of the p16 gene might not be the initiating event in liver metastases of colorectal carcinoma.

Colorectal Neoplasms↗
PubMed2001

[Comparative effects of decreasing viscosity in different preparations of Chinese angelica root and ginseng].

OBJECTIVE: To compare the effects of different preparations of Chinese angilica root and ginseng on decreasing whole blood viscosity and plasma viscosity in rats. METHOD: The hemorheological method was used in vivo or in vitro and a Decreasing Viscosity Index (DIV) was defined as a comparative scalar. RESULTS: In the effect of the groups of Chinese angilica root on decreasing viscosity, the effect of whole root group was the best and the effect of main root group was better than that of the tributary root group. Meanwhile the same effect of transplant wild ginseng group was greater than that of dried raw ginseng group. CONCLUSION: This work provided some fundamental evidences for clinical application and pharmacological data for the quality evaluation.

Angelica sinensis↗
PubMed2001

[Ovarian carcinoma presents as distant metastases without detectable tumors of the origin disease at the first presentation].

OBJECTIVE: To study the characteristics, therapies and prognosis of the patients with epithelial ovarian cancer (EOC) that are initially categorized as extra-abdominal adenocarcinoma of unknown primary. METHODS: Twenty-five patients with EOC, who were treated in the Cancer Hospital of Fudan University from Jan. 1986 to Dec. 1997, and manifesting as extra-peritoneal or liver parenchyma metastases at the time of presentation, without detectable ovarian tumors, were retrospectively studied. RESULTS: Supraclavicular and inguinal lymph node metastases were common in this group of patients, with 6 and 5 cases respectively, and 6 patients with more than two sites metastases simultaneously. 16 patients (64%) were optimally surgical debulked. 20 patients with stage IV EOC initially presenting as extra-abdominal metastases experienced a better prognosis, with an estimated median survival of 24 months. Of whom the median survival was 30 months in patients presenting with pleural effusion or supraclavicular lymph node metastases Vs. 19 months in those with other sites spread (P = 0.0264). CONCLUSIONS: The prognosis of such cases, particularly for those with supraclavicular lymphadenopathy or malignant pleural effusion, is a lot better than other stage IV EOC patients, probably because of most of the patients initially presenting with distant metastases being generally in a good condition competent for aggressive surgery or multi-cycle chemotherapy.

Adult↗
PubMed2001

[Impact of quantitative and qualitative pathogen culture on the outcome of ventilator-associated pneumonia].

OBJECTIVE: To evaluate the impact diagnostic methods with either quantitative culture (QC) or qualitative routine culture (RC) on the outcome of VAP. METHODS: A prospective, controlled clinical trial in 93 consecutive VAP episodes of 31 patients receiving mechanical ventilation was conducted. VAP episodes were randomly and crossly divided into QC (43 episodes, underwent FOB-PSB-QC) and RC group (50 episodes, underwent ETA-RC). Empirical antibiotic treatment was given according to the attending physician and modified according to the results of culture and sensitivity. The outcomes of VAP were assessed. RESULTS: There were no differences with regard to mortality, super-infection rate, antibiotic resistance rate and cost of antibiotics when comparing QC versus RC diagnostic methods and management based on two diagnostic strategies. Inappropriate initial empirical antibiotic treatment led to a higher mortality (17.7%) when compared with those with appropriate treatment. CONCLUSION: The present study demonstrates that the outcome of VAP is probably more dependent on the adequacy of the initial antibiotic treatment than on the use of either diagnostic sampling.

Aged↗
PubMed2001

[Effects of Fas ligand expression on pancreatic islet allografts].

OBJECTIVE: To investigate the immune privilege of islet allgrafts induced by the Fas ligand (FasL) expressed by co-transplanted testicular Sertoli cells and the effects of FasL gene transfected into islet cells on pancreatic islet allografts. METHODS: The allogeneic islets and testicular cells from rats were co-transplanted into diabetic recipients. Pancreatic islet cells were firstly infected with the recombinant adenovirus AdV-FasL and then transplanted into the diabetic recipients. Allograft survival, islet function and apoptosis of infiltrative lymphocytes in allografts and gene-transfected islet allografts were observed. RESULTS: All the animals receiving islet allografts alone returned to a diabetic status in several days (mean survival time = 6.3 +/- 0.56 days). When the number of testicular cells co-transplanted with islets increased to 1 x 10(7), all the animals remained normoglycemic throughout the follow-up period (P < 0.05). Sertoli cells expressing FasL induced apoptosis of infiltrative lymphocytes in the allografts. In the group of FasL gene transfection, the rejection of allografts was accelerated and the allograft survival time shortened to 3.4 +/- 0.24 days (P < 0.05). Pancreatic islets infected with AdV-FasL demonstrated positive staining for FasL at the 24th hour and increased intensity at the 48th hour after transplantation. After the transplantation, apoptosis of FasL-transfected islet cells occurred. CONCLUSIONS: Co-transplantation of testicular Sertoli cells expressing FasL and islets can induce apoptosis of activated lymphocytes and allows long-term survival of allogeneic islets because of immune privilege. However, direct expression of FasL by islet allografts infected with AdV-FasL accelerates the islet rejection by islet cell apoptosis and granulocytic infiltration.

Animals↗
PubMed2001

[Clinicopathological and molecular genetic analysis in Chinese typical hereditary nonpolyposis colorectal cancer pedigrees].

OBJECTIVE: To investigate the clinicopathological and molecular genetic characteristics of Chinese hereditary nonpolyposis colorectal cancer (HNPCC) pedigrees. METHODS: Four Chinese HNPCC pedigrees were studied using microdissection, microsatellite instability analysis, immunohistochemistry staining and direct DNA sequencing for hMSH2 and hMLH1 genes. RESULTS: All five tumor tissues from 4 probands showed high level of microsatellite instability at more than 2 loci(RER + phenotype). Three of 4 cases lost hMSH2 protein expression and one case showed no hMLH1 protein expression. Three pathological germline mutations (2 on hMSH2 and 1 on hMLH1) were identified. CONCLUSIONS: Chinese typical HNPCC kindreds showed relatively frequent germline mutations of mismatch repair genes. Microsatellite instability analysis and immunohistochemistry staining might be the effective screening methods before direct DNA sequencing for the detection of mismatch repair genes. It is necessary to establish clinical criteria and molecular diagnostic strategies more suitable for Chinese HNPCC kindreds.

Adult↗
PubMed2001

Effects of free radicals and amyloid beta protein on the currents of expressed rat receptors in Xenopus oocytes.

OBJECTIVE: To investigate the effects of free radicals (FRs) and amyloid beta protein 1-40 (A beta 1-40) on the functions of expressed neurotransmitter receptors (NRs) in Xenopus oocytes. METHODS: Total RNA and messenger RNA (mRNA) was prepared from 3-month-old Wistar rat brain tissues with Promega kits and microinjected into maturated Xenopus oocytes (stages V-VI) with 50 nl (50 ng) for each oocyte. The microinjected oocytes were incubated with modified Bath's solution at 19.0 degrees C +/- 1.0 degree C for receptor expression and their currents were recorded with double electrode voltage clamp technique. Superoxide anion free radicals (SAFRs) were produced via a reaction system (HPX/XO) with hypoxanthine (HPX, 0.05 mol/L) and xanthine oxidase (XO, 0.1 U/L). In order to observe the effects of A beta and SAFRs on the expressed glutamate receptor, HPX/XO and A beta 1-40 were added to incubation solution at 12 h, 24 h and 96 h before recording. RESULTS: The results showed that the oocytes expressed functional NRs originating from rat brain tissues. These NRs included muscarinic acetylcholine (mACh), glutamate (Glu), dopamine (DA), serotonin (5-HT) and gamma-aminobutyric acid (GABA). The current characteristics of expressed receptors were inward currents carried by chloride ion with their equibrilium potentials close to -22 mV. The extent of effect on the current of expressed glutamate receptor from rat brain was different among different A beta concentrations and incubation times. A beta 1-40 at a concentration of 20 nmol/L had little effect on the currents of expressed rat brain glutamate receptors up to 24 h of incubation period; but the currents of glutamate receptor were significantly decreased (25% off, P < 0.01) in the treatment of 60 nmol/L A beta 1-40 over 24 h. Moreover, when 20 nmol/L A beta 1-40 was co-incubated over 12 h with SAFRs produced by the reaction system of HPX/XO, it was found that the currents of expressed rat brain glutamate receptors had been changed markedly. When the oocytes were co-treated with 60 nmol/L A beta 1-40 and SAFRs over a period of 12 h, the currents of glutamate receptor significantly decreased (21% off, P < 0.05), and the decreased percentage reached 52% over 24 h co-treatment with 60 nmol/L A beta 1-40 and SAFRs. In addition, vitamin E had a partial effect against this inhibitory effect. CONCLUSION: The results suggest that A beta has a kind of inhibitory effect upon the current of the glutamate receptor, similar to the effects of free radicals. The effects can be antagonized by vitamin E. These imply that A beta may play a role via inhibiting receptor function in the pathophysiology of Alzheimer's disease.

Amyloid beta-Peptides↗
PubMed2001

bcl 10 gene mutation in hepatocellular carcinoma.

OBJECTIVE: To detect the mutation frequency of the bcl 10 gene in the early and advanced stages of hepatocellular carcinoma (HCC). METHODS: Genome DNA samples were extracted from 46 cases of fresh HCC tumor tissues and their non-tumor adjacent tissues. Polymerase chain reaction-single strand conformation polymorphism method was used to detect point mutations of the three exons of the bcl 10 gene. For each individual exon, six random samples from those showing abnormal DNA bands were sequenced to verify those mutations. The relationship between serum alpha-fetoprotein (AFP) level and bcl 10 mutation, between the tumor size and bcl 10 mutation was also analyzed. RESULTS: Among the 46 samples, 26 cases (56.5%) were found to have mutations in exon 1, 5 out of the 6 cases were shown to have 5744 C-->G mutation by sequencing; 25 cases (54.3%) were found to have mutations in exon 2, 4 out of the 6 cases were shown to have 11,311 T deletion mutation by sequencing. Twenty-one cases (45.7%) were found to have mutations in exon 3, all of the 6 cases selected for sequencing were shown to have 14,116 C-->T mutation. Statistical analysis showed that neither serum alpha-fetoprotein level nor the size of hepatocellular carcinoma has a significant relationship with bcl 10 mutation. CONCLUSION: The bcl 10 gene has a high mutation frequency in liver cancer.

Adaptor Proteins, Signal Transducing↗
PubMed2001

[Expression of two types of melanoma antigens in hepatocellular carcinoma].

OBJECTIVE: To investigate the expression of melanoma antigen MAGE-4 and MAGE-10 mRNA in Chinese human hepatocellular carcinoma (HCC). METHODS: The expression of MAGE-4 and MAGE-10 mRNA in HCC tissues and the adjacent non-HCC liver tissues was studied using RT-PCR in 48 samples of HCC. Ten samples of cirrhosis and 10 samples of normal liver tissues were examined. The PCR products were sequenced. RESULTS: Of the 48 HCC samples studied, 15 (31.3%) and 14 (29.2%) expressed MAGE-4 and MAGE-10 mRNA respectively. In contrast, none of the HCC adjacent non-tumorous liver tissues were MAGE-4 and MAGE-10 mRNA detectable. Nor did liver tissues from cirrhosis and normal liver samples. The expression of the two genes in HCC showed no correlation with the serum level of AFP and the tumor size. CONCLUSION: MAGE-4 and MAGE-10 mRNA are specifically expressed in Chinese HCC samples.

Antigens, Neoplasm↗