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Biomedical subjects

C Cao

Publications and source records attributed to C Cao.

At least 109 records · Page 6Linked to original sources
PubMed1997

[Interleukin-8, a regulator of inflammation in gingival crevicular fluid].

The role of interleuking-8 (IL-8), a neutrophil-attracting and-activating cytokine, was investigated in gingival crevicular fluid (GCF). ELISA was used to detect the levels of IL-8 in GCF collected from 54 adult periodontitis (AP) patients (105 teeth) and 24 healthy subjects (54 teeth). The results showed that 1. The role of IL-8 was dependent upon the concentration of IL-8 in GCF. IL-8, in the low concentration (< or = 30 micrograms/L), was positively correlated with bleeding index (r = 0.36, P < 0.01). While in the high concentration (> 30 micrograms/L), was negatively correlated with bleeding index and probing depth (r = -0.54 and r = -0.65 respectively, P < 0.01). In the majority of periodontitis sites (91%), the concentration of IL-8 in GCF were lower than 30 microliters/L. IL-8 most likely acted as pro-inflammatory factor in these teeth. 2. IL-8 was a two-way regulator of inflammation, pro-inflammation and anti-inflammation. The threshold of IL-8 between inducing and suppressing inflammation was approximately 30 micrograms/L. Within the confined range, IL-8 concentration greater than 30 micrograms/L could be inflammation suppressive, while a less-than-30 micrograms/L concentration of IL-8 might become inflammation inducing.

Adult↗
PubMed1997

[A longitudinal study of alveolar bone repair following non-surgical treatment in periodontitis].

The purpose of this study was to monitor post-treatment alveolar bone repair using digital subtraction radiography (DSR). 104 interproximal bone crestal sites were selected from 52 premolars in 9 periodontitis patients (6 male, 3 female, aged 29-63 years). Acrylic stents were used to ensure serial radiographs which were taken at initial visit, 2 weeks, and 1, 2, 3, 6, 9, 12 month(s) after scaling and root planning. Results showed: in some of the observed sites, small amount of bone increase was detected as early as two weeks after the non-surgical therapy. Statistically significant bone gain (P < 0.001) occurred at second month and peaked at 12 months after instrumentation. The increment of bone gain displayed an exponential curve. Three different patterns of alveolar bone reaction to treatment appeared among different patients. This study demonstrates that DSR is a sensitive and quantitative method in the monitor of bone fill after periodontal treatment.

Adult↗
PubMed1997

[An investigation on peri-implant status in different types of dental implant].

Clinical, biochemical and microbiological methods were used to study the peri-implant status in different types of dental implant. Sixteen normal healthy adults with 12 one-stage implants and 22 two-stage implants were included in this study. Clinical parameters, proportion of subgingival spirochetes, detection rate of spirochetes were found to be significantly higher around one-stage implants than those around two-stage implants. No significant difference in gingival crevicular fluid flow, levels of aspartate aminotransferase and alkaline phosphatase was found between these two types. The bleeding index score in sites which harbored spirochetes was significantly higher than that in sites without spirochetes. The present data suggested that accumulation of plaque and existance of periodontal pathogens maybe related to peri-implant inflammation. This study suggests that plaque control and regular recall should be emphasized in implant maintenance.

Adult↗
PubMed1997

[The evidence for existence of interleukin 8 inhibitor and its biological activity in gingival crevicular fluid].

In order to confirm the existence of Interleukin-8 (IL-8) inhibitor and its biological activity in gingival crevicular fluid (GCF), this study examined the GCF taken from 7 adult periodontitis (AP) patients. In neutralization test of IL-8, the results showed that the mean level of IL-8 was less than 1 ng/ml, which had been added into the GCF before ELESAs was performed to measure the amount of IL-8 in GCF. The mean level of IL-8 in the GCF of AP group was significantly lower than that of healthy group (P < 0.001). In biological activity test of IL-8 inhibitor, using pooled GCF taken from 8 AP patients (23 teeth), the results showed that the GCF (without recombinant human IL-8, rhIL-8) caused more white blood cell (WBC) migration than blank control group (physiological saline) did. When the amount of rhIL-8 increased in GCF from 0.1 microgram to 1 microgram, the WBC count increased by 18.6% which was less than the increase rate (49.1%) in control group with same dose of IL-8. In the saline group containing rhIL-8, the WBC chemotactic response appeared as an inverted "V"-shape curve. All these data suggested that 1. Certain kinds of IL-8 inhibitor exist in GCF which can "cleave" IL-8. 2. The level of IL-8 inhibitor(s) increases significantly in the GCF from periodontitis sites. 3. The GCF of adult periodontitis patient has strong chemotactic effects on WBC. IL-8 inhibitor(s) in GCF can slightly suppress the chemotactic effect induced by IL-8. When assessing the role of IL-8 in pathophysiology, the high and low dose of IL-8 might have different sense.

Adult↗
PubMed1997

[A promoter responsible for over-expression of cholera toxin B subunit in cholera toxin A subunit structure gene].

A promoter sequence, which promotes the transcription of cholera toxin B subunit gene, was found in cholera toxin A subunit structure gene. The transcription starts at the adenine Located at +833, that is 456bp upstream to the A of the initiation codon ATG of cholera toxin B gene. Under the control of the promoter, cholera toxin B subunit was over-expressed as high as 200 mg/L at an optimized culture condition. The chloramphenicol acetyl transferase gene and beta-galactosidase could also be efficiently expressed under the direction of the promoter. This promoter may be responsible for the 6 fold and 7 fold higher expression level of cholera toxin B subunit than cholera toxin A subunit in V. cholerae and Escheria coli respectively. The over-expression of CTB may be useful in preparing vaccine against cholera and facilitating the construction of peptide-bearing immunogenic hybrid proteins.

Base Sequence↗
PubMed1996

Endothelial cells of the rat brain vasculature express cyclooxygenase-2 mRNA in response to systemic interleukin-1 beta: a possible site of prostaglandin synthesis responsible for fever.

We previously showed that intraperitoneal injection of lipopolysaccharide induced cyclooxygenase-2 (COX-2) mRNA in as yet unidentified cells of blood vessels and leptomeninges in the rat brain and proposed a possible role of these cells as the source of prostaglandin E2 in the genesis of fever (Cao et al., Brain Res., 697 (1995) 187-196). In the present study, to proceed further with this line of research, we addressed the following two questions: first, does a pyrogenic dose of interleukin-1 beta (IL-1 beta), an endogenous pyrogen, induce COX-2 mRNA in the brain blood vessels and leptomeninges? Secondly, if it does, what type of cells are positive for COX-2 mRNA? Intraperitoneal injection of recombinant human IL-1 beta (30 micrograms/kg) induced fever in rats and an in situ hybridization study revealed that faint but significant COX-2 mRNA signals appeared in the blood vessels and leptomeninges at 1.5 h after the injection (the early rising phase of fever). The mRNA signals increased in number and intensity at 4 h (early plateau phase), decreased at 6.5 h (early recovery phase), and completely disappeared by 10 h after the injection (late recovery phase). The COX-2 mRNA positive cells in the blood vessels were likely to be the endothelial cells since the corresponding cells in the adjacent mirror-imaged section also expressed mRNAs for intracellular adhesion molecule-1 and the type-I interleukin-1 receptor, although those in the leptomeninges still remained unidentified. These results imply that circulating IL-1 beta acts on its receptor on the endothelial cells of the brain vasculature to induce COX-2 mRNA, which is possibly responsible for the elevated level of PGE2 seen during fever.

Animals↗
PubMed1996

Diagnosis of hepatitis C virus (HCV) infection by antigen-capturing ELISA.

BACKGROUND: Hepatitis C virus (HCV) is a major cause of non-A non-B hepatitis. Detection of circulating antibodies against HCV by enzyme-linked immunosorbent assay (ELISA) has provided the main approach for the diagnosis of HCV infection. Most ELISA kits use a mixture of core, NS3, NS4 and NS5 antigen as capture antigens and enzyme-labeled goat anti-human IgG as conjugate. OBJECTIVES: To establish an ELISA system based on the antigen-capturing principle, using a recombinant chimeric polyprotein containing four HCV antigenic components as antigen. STUDY DESIGN: HCV antigens were expressed in Escherichia coli as chimeric polyprotein either in inclusion bodies or in soluble form. Protein expressed in inclusion bodies was used as solid-phase antigen, and the antigen expressed in a soluble form was used as enzyme conjugate after being labeled with horseradish peroxidase (HRP). RESULTS: Genes coding HCV antigens were cloned and sequenced, chimeric polyproteins containing four immunodominant components (core, NS3, NS4 and NS5) were expressed in E. coli both in soluble and in inclusion body form. These two chimeric proteins retained the antigenicity of HCV antigens. Antibody-capturing ELISA using the chimeric antigens showed a sensitivity of 97% (97/100) and a specificity of 98% (97/99) using the reference panel from the National Institute for the Control of Pharmaceutic and Biological Products of China (NICPBC); the same assay showed a sensitivity of 97.9% (48/49) and a specificity of 100% (43/43) using the self-established reference panel. Antigen-capturing ELISA was set up using the antigen labeled with horseradish peroxidase as conjugate, and was shown to be as sensitive as (97.9%) and more specific than (100%) antibody-capturing ELISA using the reference panel in this work. The antigen-capturing ELISA also showed a high accordance (98.9%) with UBI HCV enzyme immunoassay (EIA) 4.0 kits (United Biomedical Inc. USA). CONCLUSION: Antigen-capturing ELISA provided a convenient, sensitive and more specific approach for the diagnosis of hepatitis C virus infection.

Journal Article↗
PubMed1996

Interaction between FtsZ and inhibitors of cell division.

The interaction between inhibitors of cell division and FtsZ were assessed by using the yeast two-hybrid system. An interaction was observed between FtsZ and SulA, a component of the SOS response, and the interacting regions were mapped to their conserved domains. This interaction was reduced by mutations in sulA and by most mutations in ftsZ that make cell refractory to sulA. No interaction was detected between FtsZ and MinCD, an inhibitory component of the site selection system. However, interactions were observed among various members of the Min system, and MinE was found to reduce the interaction between MinC and MinD. The implications of these findings for cell division are discussed.

Adenosine Triphosphatases↗
PubMed1996

[Tropisetron for the prevention of nausea and vomiting during chemotherapy: multicenter clinical study].

The antiemetic effect of tropisetron was studied in 97 cancer patients (67 men, 30 women) receiving cisplatin in doses of 75 mg/m2 or higher. On 279 chemotherapy cycles studied (max 6 per patient) 5 mg of tropisetron was administered once a day i.v on day 1 and p.o. on days 2 to 6. Efficacy preventing vomiting and nausea was measured in 24 hour period as: complete control O episodes, major control 1 to 2 episodes, minor control 3 to 4 episodes and no control 5 or more episodes. Satisfactory vomiting control (complete and major) was 69%, 63%, 82%, 88%, 96% and 96% in days 1 to 6 of cycle 1. Satisfactory nausea control (complete and major) for the same days was 70%, 66%, 72%, 85%, 92% and 97%. Similar data was obtained for the subsequent cycles. Complete vomiting control was obtained in 47%, 35%, 56%, 72%, 81% and 84% and for nausea in 42%, 39%, 48%, 64%, 81% and 87%. 19 patients presented adverse effects (19.6%). Only 2 headache episodes had a definite relation with the antiemetic drug. 12 patients discontinued the medication; 6 due to drug inefficacy, 2 to illness unrelated to the drug, 1 to lack of collaboration, and 3 due to other reasons. We conclude that tropisetron allows satisfactory control of acute and delayed vomiting in a high percentage of patients treated with high doses of cisplatin. The drug does not have significant secondary effects. Tropisetron administration in only one daily dose implies an evident advantage and a treatment cost reduction.

Adolescent↗
PubMed1996

[Experimental study on uptake of fluoride by dentin after pulsed Nd:YAG laser irradiation].

The purpose of this study was to determine the uptake of fluoride by dentin after pulsed Nd:YAG laser irradiation. Under SEM examination dentin lased by pulsed Nd:YAG laser appeared to be melted; there were no changes of calcium and phosphorus levels. Dentin irradiated by pulsed Nd:YAG laser and treated with 38% Ag(NH3)2F showed greater uptake and deep penetration of fluoride than topical application of fluoride alone, SEM examination revealed that CaF2-like and Ag3PO4-like deposits were formed on the dentin surface. These results suggested that pulsed Nd:YAG laser irradition could improve the absorption of fluoride in dentin.

Dentin↗
PubMed1996

[Studies on distribution patterns of modulator CGRP in different motoneuron pools in rats].

Using retrograde labelling combined with calcitonin gene-related peptide (CGRP) immunocytochemistry technique, distribution patterns of the content of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) were studied in two different motoneuron (Mn) pools supplying soleus (SOL, slow-twitch muscle) and extensor digitorium longus (EDL, fast-twitch muscle) of hindlimbs in rats during development. The Mn pools were identified with a novel retrograde tracer, choleragen B subunit (CB) coupled with colloidal gold (CB-Au, 5 nm particle, prepared by ourselves), which was injected into EDL or SOL. After the silver intensification for visualizing colloidal gold particles, CGRP immunocytochemistry were processed. The CB-Au retrogradely identified Mns in each Mn pool were counted and CGRP-LI intensity of Mns was evaluated as strong, moderate, weak and negative. The double labelling revealed different distribution patterns of CGRP-LI content between SOL and EDL Mn pools during development. Comparing the level of CGRP expression between the two Mn pools, SOL Mn pool had a higher ratio of neurons lacking CGRP-LI/weak CGRP LI and a lower proportion of strongly CGRP-LI labelled ones. These results suggest that the difference in content of CGRP-LI in Mns is related to the type of muscular motor activity.

Animals↗
PubMed1996

[The effect of sampling repetition on gingival crevicular fluid and aspartate aminotransferase activity].

The purpose of the present investigation was to evaluate the influence on sampling repetition of aspartate aminotransferase (AST) level with 10-minute intervals. Tests based on the composition of gingival crevicular fluid (GCF) for detection of active periodontitis and GCF require the repetition of sampling. Two 30-second samples of GCF were harvested with 10-minute intervals from 123 sites in 10 healthy subjects and 20 periodontitis patients. AST activity of the first samples in periodontitis subjects were approximately 7.8% greater than that of the second samples. The difference were not significant (P > 0.05). But in healthy subjects the difference were significant (P < 0.05). AST activity correlation positively with bleeding index (BI) and probing pocket depth (PD).

Adult↗
PubMed1995

Induction by lipopolysaccharide of cyclooxygenase-2 mRNA in rat brain; its possible role in the febrile response.

Cyclooxygenase 2 (COX-2) is a newly discovered isoform of cyclooxygenase that is inducible by lipopolysaccharide (LPS) or cytokines. This enzyme is considered to play a major role in inflammatory processes by catalyzing the production of prostaglandins. In the present study, induction of COX-2 mRNA in the rat brain by intraperitoneal injection of LPS was studied by the in situ hybridization technique with special attention paid to timing and sites of induction along with the time course of fever. In situ hybridization was carried out on sections of rat brain, 1 h (latent phase), 2.5 h (maximally febrile phase), 4 h (plateau phase), and 7 h (recovery phase) after the LPS injection, as well as on those from the brains of untreated and saline-injected rats. Injection of LPS induced COX-2 mRNA in the brain in two different constituents: neuronal cells and non-parenchymal cells of the blood vessels and leptomeninges. Induction in the neuronal cells was restricted to some telencephalic areas where the COX-2 mRNA signal was also detected in control animals. The signal was maximally enhanced by 50 to 80% over the basal level 1 h after LPS injection. The COX-2 mRNA signal was hardly detectable in neuronal and glial cells in other brain regions, including the preoptic area, either in control or LPS-injected rats. Strong COX-2 mRNA signals, however, appeared in the inner surface of blood vessels and the leptomeninges over the entire brain, including the preoptic area and its vicinity. The signals were not detectable in the brains of control rats and were most intense in the brains of rats treated with LPS for 2.5 h or 4 h. These results demonstrate that two major cell groups in the brain, neuronal cells and non-parenchymal cells, are responsible for the enhanced production of prostaglandins after systemic LPS treatment. Considering the site and timing of induction, we propose a possible role for blood vessels and leptomeninges as the source of prostaglandin E2 in the genesis of fever.

Animals↗
PubMed1995

Gene fusion of cholera toxin B subunit and HBV PreS2 epitope and the antigenicity of fusion protein.

A unique EcoRI site was introduced at the 3' end of cholera toxin B subunit (CTB) gene by site-directed mutagenesis, polynucleotides encoding 120-145aa epitope of HBV PreS2 were chemically synthesized and fused to the 3' end of cholera toxin B subunit gene. The fused gene was over-expressed (about 30 micrograms ml-1) in E. coli, and more than 95% of the fusion protein was secreted into the medium. The fusion protein expressed was purified by affinity chromatography. The chimera protein obtained bound to ganglioside GM1, and had the antigenicity of both cholera toxin B subunit and HBV PreS2 as confirmed by ELISA. After mice were immunized intramuscularly with the fusion protein, anti-CTB antibody and anti-PreS2 antibody were produced. These results indicated that the fusion protein retained not only the biological function of CTB but also the antigenicity and the immunogenicity of cholera toxin B subunit and HBV PreS2 epitope. This work provided a sound basis for further studies on the construction of engineered peptide vaccine.

Amino Acid Sequence↗
PubMed1995

[Inhibitory effect of anti-motoneuron serum on the neurite outgrowth of spinal cord explants (in vitro) and the cross-reactivity of serum to human and rat motoneurons].

The effects of rabbit anti-swine motoneuron serum (RAS), normal rabbit serum (NRS), skeletal muscle extracts (MET, 50 and 100 micrograms/ml) and brain extracts (BET, 50 and 100 micrograms/ml) on neurite outgrowth of neonatal rat spinal cord explants (in vitro) were studied after 5 days of treatment. In comparison with NRS (explants possessing neurite outgrowth accounted for 36.7%, n = 30), the neurite outgrowth of spinal cord explants was significantly accelerated by MET (96.7% of explants had neurite outgrowth), but inhibited by RAS (only 13.3% of the explants had neurite outgrowth). The cross-reactivity of RAS to the spinal motoneuron of swine, humans and rats were also demonstrated by immunocytochemical techniques.

Animals↗
PubMed1995

[Relationship between levels of aspartate aminotransferase in gingival crevicular fluid and periodontal disease activity].

This paper describes a longitudinal study in which clinical parameters and aspartate aminotransferase (AST) in gingival crevicular fluid (GCF) were monitored bimonthly over a 6-12 months period in 970 sites from 7 treated periodontitis patients. In this study, 21 out of 970 sites exhibited new attachment loss (AL) of at least 2mm between two consecutive visits. The GCF-AST levels and clinical parameters at sites with active tissue destruction (> or = 2mm AL within two months) were significantly higher than those at control sites on the same tooth. The GCF-AST levels and clinical parameters at sites with active tissue destruction decreased significantly after re-treatment. The measurement of GCF-AST could be an useful adjunctive criterion for detection of disease activity. However, it seems to be unsatisfactory in predicting disease activity.

Aspartate Aminotransferases↗
PubMed1995

A secretion expression system using promoter and signal peptide of cholera toxin B subunit gene.

A secretion expression plasmid vector pMC05S was constructed taking advantage of the promoter, signal peptide, and transcriptional terminator of cholera toxin B subunit gene and beta-galactosidase was overexpressed in E. coli and most of the expressed enzyme was secreted into periplasma when the lacZ gene was inserted downstream of the signal peptide sequence of pMC05S. The yield of beta-galactosidase by engineered E. coli reached 30 mg/L and most of the beta-galactosidase retained the activity of the enzyme. The appropriate host strain and medium were also investigated. This system provided a new approach for the expression of proteins that easily form inclusion bodies.

Base Sequence↗