Effects of Various Dietary Fatty Acids on α-Amino-β-carboxymuconate-ε-semialdehyde Decarboxylase Activity in Rat Liver

In this study, we investigated the effects of short-chain, middle-chain, and long-chain fatty acids on the activity of rat liver α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase [EC 4.1.1.45] (ACMSD), a key enzyme of tryptophan-niacin metabolism. Moreover, we examined the cholesterol metabolism and lipid peroxidation in relation to ACMSD activity in rats. When diets containing 2%, 5%, and 10% levels of fatty acids were given to rats for a week, saturated fatty acids and elaidic acid (trans form) did not suppress the ACMSD activity in liver. But polyunsaturated fatty acids such as linoleic acid, linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) strongly suppressed the liver ACMSD activity. Five % sorbic acid and oleic acid tended to suppress the liver ACMSD activity weakly. On the other hand, this report indicated that there is no correlation between liver ACMSD activity and cholesterol levels of serum or liver, but there is a weak negative correlation between liver malondialdehyde concentration and liver ACMSD specific activity.     

Cytotoxicity and the effect of cationic peptide fragments against cariogenic bacteria under planktonic and biofilm conditions

This study evaluated the cytotoxicity and effect of fragments derived from three oral cationic peptides (CP): LL-37, D6-17 and D1-23 against cariogenic bacteria under planktonic and biofilm conditions. For cytotoxicity analysis, two epithelial cell lines were used. The minimum inhibitory concentration and the minimal bactericidal concentration were determined for the CP fragments and the control (chlorhexidine-CHX) against cariogenic bacteria. The fractional inhibitory concentration was obtained for the combinations of CP fragments on Streptococcus mutans. Biofilm assays were conducted with the best antimicrobial CP fragment against S. mutans. The results indicated that D6-17 was not cytotoxic. D1-23, LL-37 and CHX were not cytotoxic in low concentrations. D1-23 presented the best bactericidal activity against S. mutans, S. mitis and S. salivarius. Combinations of CP fragments did not show a synergic effect. D1-23 presented a higher activity against S. mutans biofilm than CHX. It was concluded that D1-23 showed a substantial effect against cariogenic bacteria and low cytotoxicity.     

Evaluation of (GTG)<Subscript>5</Subscript>-PCR for rapid identification of <Emphasis Type="Italic">Streptococcus mutans</Emphasis>

Repetitive sequence-based polymerase chain reaction (PCR) fingerprinting using the (GTG)(5) primer was applied for fast screening of bacterial strains isolated from dental plaque of early childhood caries (ECC)-affected children. A group of 29 Gram-positive bacteria was separated into a homogeneous cluster together with Streptococcus mutans reference strains and constituted an aberrant branch after the numerical analysis of (GTG)(5)-PCR fingerprints. Automated ribotyping with EcoRI restriction enzyme (RiboPrinter microbial characterization system) revealed high genetic heterogeneity among the tested group and proved to be a good tool for strain-typing purposes. Further characterization of the studied strains was achieved by extensive phenotyping and whole-cell protein fingerprinting and confirmed all the strains as S. mutans representatives. Obtained results showed rep-PCR fingerprinting with the (GTG)(5) primer to be a fast and reliable method for identification of S. mutans.     

健康与龋病口腔唾液中乳杆菌的发酵类群与表面性质

目的 研究口腔健康的成年人和龋病患者唾液中乳杆菌的发酵类群和表面性质。方法 糖酸以口腔健康的成年人和龋病患者为对象,取其早餐后2 h的无刺激全唾液分离乳杆菌,检验其对葡萄糖和葡萄糖酸钠发酵的情况;应用MATH（Microbiol Adhesion to Hydrocarbons）法测定菌体表面疏水性和电荷。结果 口腔健康的成年人与龋病患者唾液中乳杆菌各发酵类群的比例不同,前者表面疏水性和电荷比较高,后者比较低。结论 口腔健康的成年人和龋病患者唾液中乳杆菌的组成不同,表面性质也不同,特定种类的乳杆菌与龋病的发展相关。     

龋齿致病菌变形链球菌蛋白 Smu.260 的 制备、结晶及初级晶体学分析

变形链球菌 (Streptococcus mutans) 是最主要的龋齿致病菌,其基因 Smu.260 编码一个约 23 ku (200 个氨基酸 ) 的蛋白质. Smu.260的 DNA 片段被克隆到表达载体 pET28a 后在大肠杆菌 BL21(DE3) 菌株中表达得到很好的产量. 产物 Smu.260 蛋白通过 Ni²⁺亲和柱和分子筛两步法纯化,并发现纯化后的蛋白以两种形式存在,二聚体 (约46 ku) 和四聚体,前者呈亮黄色,后者无色. 采用悬滴气象扩散法得到了二聚体形式的晶体. 晶体的 X 射线衍射分辨率达到 2.3埃,晶体属正交空间群 P2₁2₁2₁,晶格参数为a=89.88埃, b=90.91埃, c=105.17埃. 晶胞不对称单元内估计含有一个二聚体,溶剂含量为 53％ .     

北票喇嘛洞三燕文化墓地人骨的牙病

本文对辽宁北标喇嘛洞三燕文化墓地出土人骨的牙病作了详细的观察。初步探讨了龋病和牙周病的罹患率与性别和年龄的关系,结果显示：（1）龋病的罹患率男女间差异不显著,而牙周病的罹患率性别差异显著。（2）龋病的罹患率与年龄变化具有一定关系,而牙周病的罹患率则与年龄变化关系密切。此外,对多生牙、先天缺额牙、融合牙、错位牙、第三臼齿的阻生情况也分别作了记录与分析。     

The Effect of the Common Bunt on the Growth of Wheat Seedlings and Calluses

The growth of wheat (Triticum aestivum L., cv. Zhnitsa) seedlings and calluses infected with spores of common bunt causal agent Tilletia caries (DC) Tul. was studied. Inoculation with the pathogenic fungus enhanced both in vivo and in vitro growth due to cell division activation and cell expansion. These growth characteristics were also retained in wheat calluses infected with T. caries and grown on the hormone-free Murashige and Skoog nutrient medium. This implies the production of hormone-like substances by the fungus itself or by the infected plant. At the phase of fungal penetration into the plants, infection resulted in IAA accumulation in seedlings. Later, the IAA content reduced to a control level and the phytohormone balance was shifted toward cytokinins. Similar changes in the IAA and cytokinin levels were observed during early fungus development on wheat callus tissues. Such a sequence of events is supposed to be required for successful fungal penetration and localization in plant tissues and for the establishment of compatible interactions between the pathogen and the host plant.     

Cariogenicity of soluble starch in oral in vitro biofilm and experimental rat caries studies: a comparison

Aims:  Common belief suggests that starch is less cariogenic than sugar; however, the related literature is quite controversial. We aimed to compare cariogenic and microbiological effects of soluble starch in both a standard animal model and an oral biofilm system, and to assess the possible substitution of the animal model.
Methods and Results:  Six-species biofilms were grown anaerobically on enamel discs in saliva and medium with glucose/sucrose, starch (average molecular weight of 5000, average polymerization grade of 31), or mixtures thereof. After 64·5 h of biofilm formation, the microbiota were quantitated by cultivation and demineralization was measured by quantitative light-induced fluorescence. To assess caries incidence in rats, the same microbiota as in the biofilm experiments were applied. The animals were fed diets containing either glucose, glucose/sucrose, glucose/sucrose/starch or starch alone. Results with both models show that demineralization was significantly smaller with starch than sucrose.
Conclusions:  The data demonstrate that soluble starch is substantially less cariogenic than glucose/sucrose.
Significance and Impact of the Study:  By leading to the same scientific evidence as its in vivo counterpart, the described in vitro biofilm system provides an interesting and valuable tool in the quest to reduce experimentation with animals.