Role of saliva in the caries experience and calculus formation of young patients undergoing hemodialysis.

OBJECTIVES: The aims of this study were to investigate the caries experience, periodontal status, oral hygiene habits, and salivary parameters of children and adolescents undergoing hemodialysis (HD) and to compare them with their healthy counterparts. METHODS: Fifty-two HD patients were matched for age, sex, ethnicity, and social class with 52 healthy subjects for analysis of the number of decayed, missing and filled teeth, plaque and gingival index, dental calculus accumulation, measurements of pocket depth, clinical attachment level, gingival recession, and bleeding on probing. Stimulated saliva samples were collected to assess salivary flow rate, pH and buffer capacity, and salivary concentrations of calcium, phosphate, and urea by colorimetric method. RESULTS: HD patients had lower dental caries (p = 0.004), greater plaque and calculus accumulation (p = 0.001), and reported flossing less often than the controls (p = 0.013). Regarding salivary analysis, HD patients showed significantly higher values of pH, buffer capacity, and salivary urea concentration when compared to the controls (p = 0.001). CONCLUSION: HD patients had lower caries experience, higher accumulation of dental plaque, and calculus deposition than their healthy counterparts, probably due to the differences found in their salivary biochemical parameters. CLINICAL SIGNIFICANCE: A significant number of children and adolescents undergoing hemodialysis are candidates for kidney transplantation and should receive complete pre-transplant dental exams and dental treatment. Our results open the way for the development of an individualized dental protocol for these patients with preventive measures and treatment of the poor oral health in HD patients.

A TonB-dependent outer membrane protein as a Bacteroides fragilis fibronectin-binding molecule.

The binding of Bacteroides fragilis to plasmatic fibronectin was investigated using strains isolated from healthy subjects and from patients with bacteremia. They were cultivated in a synthetic media in which variations in cysteine concentrations determined alterations in the oxidation-reduction potential (Eh). All the strains assayed were capable of adhering to plasmatic fibronectin when cultivated under oxidizing and reducing conditions. Bacteroides fragilis 1405 showed the greatest difference when the results under these conditions were compared and it was selected for further investigations. Chemical treatments suggested the involvement of a protein in the interaction between B. fragilis and plasmatic fibronectin. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis of outer membrane proteins (OMPs) revealed differences between the extracts obtained from cultures grown under the two conditions. Protein bands of c. 102, 100, 77, 73, 50 and 40 kDa were more highly expressed under oxidizing than reducing conditions. Dot blot analysis showed a stronger recognition of plasmatic fibronectin by OMPs obtained from cultures grown under higher Eh, and Western blot assays confirmed a band of c. 102 kDa as fibronectin-binding protein. This protein was sequenced and revealed to be a putative TonB-dependent OMPs. PCR analysis confirmed the presence of this gene in all the studied strains.

Streptomyces lunalinharesii sp. nov., a chitinolytic streptomycete isolated from cerrado soil in Brazil.

A novel chitinolytic actinomycete isolated from a Brazilian cerrado soil, designated strain RCQ1071(T), was assigned to the genus Streptomyces on the basis of chemical and morphological characteristics. The almost-complete nucleotide sequence of the 16S rRNA gene of strain RCQ1071(T) was determined and also placed this strain in the genus Streptomyces. Phylogenetic analyses of 16S rRNA gene sequences showed that strain RCQ1071(T) formed a long branch in a group related to Streptomyces albulus, sharing approximately 98 % sequence similarity. Levels of DNA-DNA relatedness between strain RCQ1071(T) and members of this group, namely S. albulus DSM 40492(T), Streptomyces noursei DSM 40635(T) and Streptomyces yunnanensis DSM 41793(T), were 38.3, 27.8 and 46 %, respectively, strongly indicating that strain RCQ1071(T) was not a member of any of these species. The relatively long branch length within a stable clade together with the phenotypic data strongly supported that strain RCQ1071(T) represented a novel species. Based on the combination of physiological, phylogenetic and genomic data, strain RCQ1071(T) is suggested to represent a novel species of the genus Streptomyces, for which the name Streptomyces lunalinharesii sp. nov. is proposed. The type strain is RCQ1071(T) (=ATCC BAA-1231(T) =CIP 108852(T) =DSM 41876(T)).

Streptomyces lunalinharesii spores contain chitin on the outer sheath.

Chitin from Streptomyces lunalinharesii spores, detected on its outermost surface layer, was isolated and characterized by chemical and spectroscopic methods, transmission electron microscopy and flow cytometry analysis. Gold-chitinase- and gold-lectin (Lycopersicum esculentum agglutinin, LEA)-conjugated labels were used in microscopy experiments, whereas a fluorescence-lectin (LEA) conjugate was used in flow cytometry analysis. Chitin isolation consisted of several steps of hot alkali and nitrous acid treatment, and the final material was obtained in the colloidal form. The infrared and the 13C CP/MAS NMR spectra of Streptomyces sp. colloidal chitin and colloidal chitin obtained from commercial crab shell chitin were very similar. Incubation of the spores with gold-labeled lectin, or gold-labeled recombinant chitinase, showed the presence of gold particles around the spore surface, indicating the specific binding of the lectin or the recombinant chitinase with the chitin present on the outermost surface. Flow cytometry analysis, using the fluorescence-lectin conjugate, confirmed these results. According to scanning electron microscopy, S. lunalinharesii presented spore surface ornamentation belonging to the spiny group. This is the first detailed characterization of chitin on the spore's outermost layer from a Streptomyces species.