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Biomedical subjects

C Cao

Publications and source records attributed to C Cao.

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

Association of vitamin D receptor gene polymorphism with periodontal diseases in Japanese and Chinese.

We examined whether polymorphisms in the vitamin D receptor (VDR) gene are associated with the incidence of adult periodontitis (AP) and early-onset periodontitis (EOP) in case-controlled studies of Japanese and Chinese subjects. Restriction fragment length polymorphisms in the VDR gene detected by digestion with Taq I were found to be significantly associated with the occurrence of AP or EOP, suggesting that the VDR genotype a risk factor for periodontitis.

Adult↗
PubMed2001

Diagnosing primary and metastatic renal cell carcinoma: the use of the monoclonal antibody 'Renal Cell Carcinoma Marker'.

The diagnosis of primary or metastatic renal cell carcinoma (RCC) can be difficult, especially in small biopsies, because of the wide variety of histologic appearances and clinical presentations that RCC can assume. An immunomarker specific for RCC is currently not available. We tested the relevant diagnostic use of the Renal Cell Carcinoma Marker (RCC Ma), a monoclonal antibody, against a normal human proximal tubular brush border antigen. Immunostaining using RCC Ma and the avidin-biotin-peroxidase complex technique was performed on archival tissues from primary and metastatic tumors of renal or nonrenal origin. A total of 122 of 153 primary RCCs (79.7%) were positive [clear cell (84%), papillary (96%), chromophobe (45%), sarcomatoid (25%), and collecting duct (0%)], with > or =10% of tumor cells stained in 93% of cases. None of the 64 primary renal tumors other than RCC, including 15 oncocytomas, was positive. Fifteen of 146 (10.2%) nonrenal primary tumors were positive (5 of 17 breast tumors, 8 of 8 parathyroid adenomas, and 2 of 7 embryonal carcinomas). Forty-two of 63 (67%) metastatic RCCs were positive with > or =10% of cells being stained in 83% of them. Two of 108 (2%) metastases from tumors other than RCCs were positive, both of which were metastatic breast carcinomas; however, only 10% (2 of 19) of metastatic breast carcinomas were positive. RCC Ma is an excellent marker for primary RCC, which should facilitate its diagnosis in a small biopsy. Although RCC Ma remains highly specific (98%) for metastatic RCC, a negative result may not rule out metastatic RCC because of a rather low sensitivity and a focal staining pattern in some of the positive cases. RCC Ma may also facilitate the differential diagnosis between oncocytoma and other types of RCC when they are composed mostly of eosinophilic cells.

Antibodies, Monoclonal↗
PubMed2001

A four-day study to evaluate the anti-plaque efficacy of an experimental triclosan-containing dentifrice.

Four-day, non-brushing studies have been used successfully to demonstrate the anti-plaque efficacy of triclosan-containing dentifrices. The treatment effects observed are variable, likely due to differences in formulation, study design and measurement techniques. This randomized, double-blind crossover study was conducted to evaluate the anti-plaque efficacy of an experimental, multiple-benefit, triclosan-containing dentifrice versus two currently marketed sodium fluoride dentifrices in a four-day, lingual-brushing model on subjects in Beijing. People's Republic of China. Subjects brushed the lingual surfaces for 30 seconds, and before expectorating, swished the saliva/dentifrice slurry over the buccal surfaces for an additional 30 seconds. This procedure was repeated. Subjects performed their assigned brushing regimen twice daily for four days under supervision. On Day 5, plaque was measured using the Turesky Modification of the Quigley-Hein Plaque Index. There were highly significant treatment effects in favor of the experimental triclosan-containing dentifrice for whole mouth, buccal and lingual sites when compared to either of the sodium fluoride dentifrices (p < 0.0001).

Adolescent↗
PubMed2001

[A study on affecting factors on dental care demands by logistic regression model].

OBJECTIVE: To develop probability model for dental visits based on analysis of the factors affecting people's dental services utilization in urban area of Beijing, thus providing some evidence for forecasting further demanded dental care and building the more efficient oral health care delivery system. METHODS: A cross-sectional survey was conducted amnog 1,517 subjects of all age groups in Beijing selected by stratified, clustering, random sampling. The first model of dental care demand--probability model for dental visits was established with logistic regression. RESULTS: Awareness of oral health showed the most important relationship. Different social background and economic factors also had great effects on demand. Higher demand for care were existed among those who suffered from a disease that was painful or resulted in poor oral function. CONCLUSIONS: It is suggested that dental care has different characters from general health service. Utilization of dental service is largely determined by people's awareness, income and insurance system. So oral health education should be extended in order to promote the effective demands and reduce the potential demands. Rational oral health insurance system should be set up to provide some priority to certain people, thus stimulating the supply of dental care and improving the utilization of dental service. Since raising price for care will restrain the low-incomer's basic demand, and it will neither add the profit nor improve people's oral health, the price decision should be considered carefully. At last, oral health care should be emphasized on children and adolescent as priority age groups based on the conclusion from demand model.

Dental Care↗
PubMed2001

[A study on the bioavailability of fluoride added into milk].

OBJECTIVE: To assess the bioavailability of fluoride added into milk. METHODS: Eight subjects were studied by testing fluoride levels in blood and urine samples collected after drinking fluoridated milk and fluoridated water respectively, according to pharmacokinetics and cross control method. RESULTS: The bioavailability of fluoride in fluoridated milk reached 80.2% in blood analysis and 84.8% in urine analysis. The result was about 20.0% lower as compared with fluoridated water. CONCLUSION: Fluoride bioavailability in fluoridated milk is still high and sufficient.

Adult↗
PubMed2001

[The efficacy of the chlorhexidine chip following scaling and root planing (SRP) and compared to SRP alone].

OBJECTIVE: To evaluate the clinical efficacy and safety of the adjunctive use of Chlorhexidine Chip (CHX; commercial name, Perio Chip) following scaling and root planing (SRP) in periodontitis. METHODS: One center, blinded, randomized, split-mouth and active control study was designed. Sixty-five adult periodontitis patients were enrolled into the baseline after SRP. Each subject had at least one tooth with pocket depth of 5 mm or more and bleeding on probing (BOP) in each side of the mouth. Then the tooth was selected as a target and its parameters of probing depth (PD), attachment loss (AL), BOP, gingival index (GI), plaque index (PI) and staining index (SI) were recorded. Each side of mouth was randomly assigned to one of two treatments--drug placement after SRP or SRP alone. All the adverse events and parameters were recorded at time of 3-month, 6-month and meanwhile the patients received oral hygiene instruction and scaling. The same was conducted at 6-week, 4.5-month except for recording of parameters and scaling of the target teeth. RESULTS: Reduction of PD and gain of attachment at 6-month in group of SRP plus CHX (1.32 mm, 0.94 mm) were significantly higher than those in group of SRP alone (0.77 mm, 0.40 mm) (P < 0.001). Forty-four point six percent (44.6%) of patients reflected adverse reactions related to drug placement. Toothaches, the main reactions, were mild to moderate in nature and spontaneously resolved within 2-4 days. CONCLUSIONS: The chlorhexidine chip is indeed a safe and effective control-delivered drug for topical use when patient in his supportive periodontal therapy.

Adult↗
PubMed2000

X-Ray structures of the universal translation initiation factor IF2/eIF5B: conformational changes on GDP and GTP binding.

X-ray structures of the universal translation initiation factor IF2/eIF5B have been determined in three states: free enzyme, inactive IF2/eIF5B.GDP, and active IF2/eIF5B.GTP. The "chalice-shaped" enzyme is a GTPase that facilitates ribosomal subunit joining and Met-tRNA(i) binding to ribosomes in all three kingdoms of life. The conserved core of IF2/eIF5B consists of an N-terminal G domain (I) plus an EF-Tu-type beta barrel (II), followed by a novel alpha/beta/alpha-sandwich (III) connected via an alpha helix to a second EF-Tu-type beta barrel (IV). Structural comparisons reveal a molecular lever, which amplifies a modest conformational change in the Switch 2 region of the G domain induced by Mg(2+)/GTP binding over a distance of 90 A from the G domain active center to domain IV. Mechanisms of GTPase function and ribosome binding are discussed.

Amino Acid Motifs↗
PubMed2000

Pseudosubstrate inhibition of protein kinase PKR by swine pox virus C8L gene product.

The interferon-induced protein kinase PKR is activated upon binding double-stranded RNA and phosphorylates the translation initiation factor eIF2alpha on Ser-51 to inhibit protein synthesis in virally infected cells. Swinepox virus C8L and vaccinia virus K3L gene products structurally resemble the amino-terminal third of eIF2alpha. We demonstrate that the C8L protein, like the K3L protein, can reverse the toxic effects caused by high level expression of human PKR in yeast cells. In addition, expression of either the K3L or C8L gene product was found to reverse the inhibition of reporter gene translation caused by PKR expression in mammalian cells. The inhibitory function of the K3L and C8L gene products in these assays was found to be critically dependent on residues near the carboxyl-termini of the proteins including a sequence motif shared among eIF2alpha and the C8L and K3L gene products. Thus, despite significant sequence differences both the C8L and K3L proteins function as pseudosubstrate inhibitors of PKR.

3T3 Cells↗
PubMed2000

Characterization of a novel human immunodeficiency virus type 1 neutralizable epitope within the immunodominant region of gp41.

Previously, we generated human monoclonal antibodies using peripheral blood mononuclear cells from an asymptomatic human immunodeficiency virus type 1 (HIV-1)-seropositive donor. One of these monoclonal antibodies (designated clone 3, CL3) recognized 10 amino acids (GCSGKLICTT) within the immunodominant region (cluster I) of the transmembrane envelope glycoprotein gp41 and neutralized infection of target cells with different laboratory isolates. Because the epitope recognized by CL3 has two cysteine residues that could potentially produce a disulfide loop in gp41, we analyzed binding of our monoclonal antibody to the cyclic and linear motif of the peptide sequence IWGCSGKLICTTAVP (residues 600-614). The CL3 antibody did not bind to the synthetic cyclic peptide but did recognize the linear form. Two polyclonal rabbit sera against both the linear and cyclic peptides were then generated. Both antisera bound to viral glycoproteins gp41 and gp160, but neither sera neutralized HIV-1 laboratory isolates. Using a set of alanine-substituted IWGCSGKLICTTAV peptides, we analyzed binding of polyclonal antisera and CL3. The profile of binding of polyclonal antisera to these peptides was different from that of CL3 to the same peptides. This suggests that CL3 recognized a unique neutralizable core epitope, which was not immunogenic in either the cyclic or the linear IWGCSGKLICTTAVP peptides used as immunogens in the rabbits.

Amino Acid Sequence↗
PubMed2000

On molecular polarizability: 3. Relationship to the ionization potential of haloalkanes, amines, alcohols, and ethers

The relationship between the ionization potential and the parameters molecular electronegativity and molecular polarizability for haloalkanes, amines, alcohols, and ethers was investigated. There is no good linear correlation between the ionization potential Ip and molecular electronegativity chi(eq) alone for these compounds. Ip can be modeled well with three parameters: chi(eq), polarizability effect index (PEI) of an alkyl group, and atomic polarizability (P). Further, a single expression for predicting the Ip values of aldehydes, esters, nitriles, and carboxylic acids was developed: Ip(Rz)(eV) = Ip(MeZ) + 1.4544delta chi(eq) - 1.6435delta sigmaPEI(Ri). Here Ip(MeZ) is the experimental ionization potential of monosubstituted methane MeZ. Delta chi(eq) and delta sigmaPEI(Ri) are the difference in the molecular electronegativity and the difference in the polarizability effect index of alkyl groups attached to the functional group Z between molecules MeZ and RZ, respectively.

Journal Article↗
PubMed2000

Leukocyte functions in 2 cases of Papillon-Lefèvre syndrome.

AIM: To investigate the rôle of leukocytes in the pathogenesis of Papillon-Lefevre syndrome (PLS). METHODS: Peripheral blood polymorphonuclear neutrophils (PMNs), monocytes (MNs) and gingival crevicular fluid (GCF) were obtained from 2 cases of PLS with typical features. The chemotaxis of PMNs and MNs were evaluated using a modified Boyden chamber. The adherence of PMNs was determined by adherence of PMNs to petri dishes. Interleukin-8 (IL-8) in GCF was detected by sandwich ELISA. Elastase activity in GCF was measured with a low molecular weight substrate (S-2484) specific for granulocyte elastase. RESULTS: PMNs from both patients showed depressed chemotactic response to FMLP and IL-8. Total amounts of IL-8 in GCF from the 2 patients were much higher than those of the normal controls. Elastase activity was not significantly different from that of the controls. The adherence of PMN and the chemotaxis of MN in the 2 patients were normal. CONCLUSION: The depressed chemotactic response of PMN leads to decreased recruitment of PMN and/or release of lysozyme from PMN in the diseased gingival tissue, increasing the susceptibility of PLS patients to periodontal infection.

Adult↗
PubMed2000

High-level expression of a truncated wall-associated protein A from the dental cariogenic Streptococcus mutans.

Streptococcus mutans plays a primary role in the formation of dental caries. Previously, in our laboratory, an S. mutans genomic library was prepared, and the wapA gene was cloned into the shuttle vector, pSA4/4B2. To generate overexpression of wapA and to facilitate efficient purification of the WapA protein for use as an immunogen, an expression vector with the strong tac promoter was used. In order to answer questions regarding the optimization of solubility and expression based on gene size or the hydrophobicity of the protein product, 12 truncated constructs of the wapA gene were prepared using PCR. The truncated products were subcloned into the pGEX-6P-1 glutathione S-transferase (GST) fusion vector and expressed in E. coli BL21. The fusion proteins were analyzed by SDS-PAGE and confirmed by analysis with anti-GST and anti-WapA antibodies. Our study suggests that abrogation of the wapA promoter is necessary for expression of this gene in this expression system. Deletion of the signal peptide and the hydrophobic C terminus of WapA increased expression compared with the full-length construct, and truncation at the protease cleavage site of the C-terminal region greatly increased the stability of the protein without a loss in reactivity with the anti-WapA antibody. Western immunoblot analysis with anti-WapA antiserum clearly showed that the majority of the epitopes of the GST-WapA fusions are located in the N-terminal region of WapA. The immunogenicity of the various WapA fusion products is being examined in mice and rats to further map the immunologically dominant regions of the protein. This method effectively increased the expression of WapA and should contribute to the further understanding of gene expression of E. coli, as well as aid in the characterization of this protein for future immunologic evaluation.

Antigens, Bacterial↗
PubMed2000

2-year observation of attachment loss in a rural Chinese population.

BACKGROUND: Risk indicators for periodontitis seem to vary with study population. The purpose of this study was to determine whether risk indicators of additional attachment loss differ between generations of Chinese villagers in a rural area of China over a 2-year period. METHODS: The study population consisted of 310 subjects aged 15 to 44. In each subject, 2 quadrants from either the upper or lower jaw were randomly selected and 6 sites on each tooth were examined. Clinical parameters included plaque scoring system (PSS), calculus index (CI), probing depth (PD), attachment level (AL), and sulcus bleeding index (SBI). The second examination was done 2 years after the first. RESULTS: In the 15- to 24-year-old age group, mean PSS, CI, and SBI were significantly higher in subjects with additional attachment loss > or =3 mm (AL+) than in those without attachment loss (AL-). In the 25- to 34-year-old age group, mean PD was significantly higher in AL+ than in AL-, and mean PD and AL were significantly higher in AL+ than in AL- in the 35- to 44-year-old age group. Although the number of subjects with AL+ increased with age, the mean number of sites with AL+ per subject did not differ by generation. In addition, smokers tended to exhibit attachment loss more often than non-smokers. CONCLUSIONS: The present results suggest that the clinical parameters associated with attachment loss differ between generations and that gingival inflammation is likely associated with the onset of periodontitis more strongly than progression of periodontitis, whereas PD and/or AL are associated with the progression of periodontitis.

Adolescent↗
PubMed2000

[Assessment of malaria DNA vaccines in mice and monkeys].

Cholera toxin B subunit is a good carrier protein and an effective adjuvant which can boost both cellular and humoral immunity. DNA fragments encoding B cell, Th cell and CTL epitopes of P. falciparum CS, MSA-1, MSA-2 and RESA antigens were cloned down-2 stream of cholera toxin B subunit gene in the same reading frame. High titer of anti-malaria epitopes antibodies and strong cellular immunogenicity were elicited after Balb/c mice were immunized three times with 100 micrograms recombinant plasmid DNA dissolved in 100 microliters PBS. A total of 120 vaccinees were challenged with mouse Plasmodium yoelli to investigate if cross protection existed. The protective efficacy was about 60%-80%. Four rhesus monkeys were challenged with 10(8) of P. cynomalgi, better results were obtained in the groups immunized with mixed plasmids including NANP, AWTE.

Animals↗
PubMed2000

[Translation initiation function of the regulation element in the operon of cholera toxin A].

To demonstrate that there existed translation coupling between cholera toxin A subunit gene and B subunit gene, and give the answer why the expression level of B gene is five times more than that of A gene, alpha report system for the investigation of translation coupling was constructed by using lacZ gene as reporter. Frame-shift mutation was introduced near the C terminal of ctxA gene, and the ribosome would read through its normal stop codon. The report plasmid was constructed and it was found that the expression level of lacZ gene decreased five times after the frame-shift mutation. The translation of cholera toxin B subunit gene was translational coupled with A subunit gene, and was responsible for the differential expression level of the two genes.

Cholera Toxin↗
PubMed2000

[A new model of translational control of gene expression in polycistron++ of AB5 entrerotoxin].

The expression level of the B subunit gene of cholera toxin (ctx) and E. coli heat labile toxin (ltx) is five to seven times more than that of A subunit gene. In these studies, a 80 basepair translation regulation element was found located in the structure gene of A gene of both toxin operon which consists of three translation initiation region. Site-directed mutation of the initiation codon of TIR3 resulted in the 9 time decrease of the expression of the downstream cistron which was translational coupled with A gene. The results indicated that translation from the internal of A gene and translation coupling are responsible for the differential expression level of the A and B gene of AB5 enterotoxin.

Bacterial Toxins↗