Cariogenicity of Candida albicans of distinct genotypes among 3-5-year-old Uygur children in Kashgar, China- a case-control study.

BACKGROUND: In recent years, the opportunistic fungus C.albicans has been linked to ECC.It is important to investigate the relationship between the distribution of C.albicans and early childhood caries (ECC) in 3-5-year-old Uygur and Han children in Kashgar, and the role of C.albicans of distinct genotypes in caries. METHODS: Two hundred fifty-six Uygur and 141 Han children were enrolled in the study. The identified C.albicans isolates were genotyped based on 25S rDNA Polymerase Chain Reaction(PCR) amplification, and their acidogenicity, aciduricity, and adhesiveness were examined. Moreover, secreted aspartic protease (Sap) activity and SAP1-5 transcriptional levels were compared in the ECC and caries-free (CF) groups of Uygur children. RESULTS: C.albicans detection rate was significantly higher in Uygur children than in Han children (44. 5% vs. 31. 2%; χ2= 6.739, P = 0.009);the A genotype was dominant in Uygur and Han children with ECC, the C genotype was dominant in Uygur CF children(P = 0.022). C.albicans acidogenicity and growth were more pronounced in the Uygur ECC group than in CF group, especially at pH 4.0 and 4. 5(pH 4.0, P = 0.012; pH 4. 5, P = 0.029); the average ratios of glass-wall adhesion and the Sap activity was higher in ECC group than in CF group(P < 0.01), and SAP2(P < 0.001) and SAP5(P = 0.001) were expressed more robustly in ECC group. CONCLUSIONS: The strong acidogenicity and aciduricity, Sap activity, and high SAP2 and SAP5 expression might be closely associated with ECC. C.albicans potentially plays a key role in the progression of caries, which most readily affects genotype A carriers and could be attributed to person-to-person environmental variation.

Hydrazinolyzed cellulose-g-polymethyl acrylate as adsorbent for efficient removal of Cd(II) and Pb(II) ions from aqueous solution.

Hydrazinolyzed cellulose-graft-polymethyl acrylate (Cell-g-PMA-HZ), an efficient adsorbent for removal of Cd(II) and Pb(II) from aqueous solution, has been prepared by ceric salt-initiated graft polymerization of methyl acrylate from microcrystalline cellulose surface and subsequent hydrazinolysis. The influences of initial pH, contact time, and temperature on adsorption capacity of Cell-g-PMA-HZ as well as adsorption equilibrium, kinetic and thermodynamic properties were examined in detail. As for Cd(II) adsorption, kinetic adsorption can be explained by pseudo-second-order, while adsorption isotherm fits well with Langmuir isotherm model, from which maximum equilibrium adsorption capacity can be derived as 235.85 mg g-1 at 28 °C. Further thermodynamic investigation indicated that adsorption of Cd(II) by adsorbent Cell-g-PMA-HZ is endothermic and spontaneous under studied conditions. On the other hand, isotherm of Pb(II) adsorption fits well with Freundlich isotherm model and is more likely to be a physical-adsorption-dominated process. Consecutive adsorption-desorption experiments showed that Cell-g-PMA-HZ is reusable with satisfactory adsorption capacity.

A polylactic acid degrading lipase from Bacillus safensis: Characterization and structural analysis.

A polylactic acid degrading triacylglycerol lipase (TGL) was identified from Bacillus safensis based on genome annotation and validated by real-time quantitative PCR. TGL displayed optimal activity at pH 9.0 and 55 °C. It maintained stability at pH 9.0 and temperatures 45 °C. The activity of TGL was found to benefit from the presence of potassium sodium ions, and low concentrations of Triton X-100. The TGL could erode the surface of polylactic acid films and increase its hydrophilicity. The hydrolysis products of polylactic acid by TGL were lactate monomer and dimer. TGL contains a classical catalytic triad structure of lipase (Ser77, Asp133, and His156) and an Ala-X-Ser-X-Gly sequence. Compared with some lipases produced by the same genus Bacillus, TGL is highly conserved in its amino acid sequence, mainly reflected in the amino acid residues that exercise the enzyme activity, including the catalytic activity center and the substrate binding sites.

Biodegradation of polylactic acid by a mesophilic bacteria Bacillus safensis.

A mesophilic bacterial strain, Bacillus safensis PLA1006, was isolated from landfill soil and was tested for growth on polylactic acid (PLA) emulsion medium. The strain formed clear zones on the medium and produced protease and lipase. The macroscopic morphology of the PLA films was not changed significantly after treatment with Bacillus safensis PLA1006 but the films were whitened. Weight loss of PLA films was about 8% after 30 days of incubation with Bacillus safensis PLA1006 in mineral salt medium. Scanning electron microscopy revealed etching on the surface of PLA film treated by Bacillus safensis PLA1006. This also caused an increase in hydrophilicity of the PLA films surface. Attenuated total reflectance - Fourier transform infrared spectroscopy analysis of PLA films after treated by Bacillus safensis PLA1006 showed no new absorption peaks but a decrease in the intensity of all absorption peaks. The hydrolysis products of PLA by the strain contained monomers and oligomers of lactic acid. Zymogram detection showed that proteases may play a role in the degradation of PLA.

[The prevalence of Candida albicans and its relationship with early childhood caries among children of Uygur and Han nationalities in Kashi city].

OBJECTIVE: To explore the relationship between the prevalence of Candida albicans and early childhood caries(ECC) among 3-5 years old children of Uygur and Han nationalities in Kashi city, Xinjiang province. METHODS: Totally 397 generally healthy children(Uyghurs 256, Hans141) aged 3-5 years were recruited randomly in Kashi city using the stratified cluster random method. Dental plaque samples were collected from carious tooth tissues of children with ECC and from supragingival tooth sites of caries free(CF) children, respectively. Plaque samples were cultured and Candida albicans were isolated selectively by using CHROM agar candida medium. The isolates were further identified using methods of germ tubes test, Gram stain and PCR molecular biology. The data were analyzed using Pearson χ(2) test and Spearman analysis. RESULTS: The prevalenses of Candida albicans were 44.5% (114/256) in Han children and 31.2%(44/141) in Urgur children, respectively(P=0.009). Candida albicans could be isolated from 48.8% (124/254) of ECC children, while 23.8% (34/143) of CF ones(P=0.000). The frequencies of Candida albicans acquisition of boys and girls of Uygur children were 51.2%(66/129) and 37.8%(48/127), respectively (P=0.031). The frequencies of Candida albicans acquisition increased with the decayed missing filled tooth (dmft) scores. For both Uygur and Hanchildren, the detection rates of Candida albicans were correlated with dmft scores(Uygur r=0.350, P=0.001; Han r=0.276, P=0.000). CONCLUSIONS: The oral Candida albicans distributions were different in Uygur and Han ethnic groups. There were significant correlations between the presence of Candida albicans and ECC severityas well as score of dmft. There was a difference of the Candida albicans distributions between boys and girls among Uygur children. Candida albicans might be one of the important cariogenic microorganisms in ECC.