No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Periodontitis tends to be associated with sulfur-producing bacteria. This study uses a chromogenic sulfur detecting strip to compares whole saliva sulfur (SS) scores in subjects with and without periodontal diseases and examines the relationship between SS scores and clinical measures of periodontal status.Materials & Methods: Ninety-sex subjects were enrolled, mean age (SD) 36.5 (15.42), age range 22 to 82, percent males 52%, percent Caucasians 57%, percent cigarette smokers 33%. Periodontal evaluations including plaque index (PI), gingival index (GI), probing depth measurements (PD) and attachment levels (AL) were performed on 6 sites per tooth. Subjects were divided into 3 groups: periodontally healthy (no loss of attachment and no gingival bleeding, 17 subjects), gingivitis (no loss of attachment and presence of gingival bleeding, 54 subjects) and periodontitis (loss of attachment > 5 mm in 5 or more teeth, 25 subjects). A single chromogenic strip was used to collect a whole saliva sample from the mouth. Color reaction was scored based on a color chart. The scoring examiner was blinded to clinical status. Results: Good to moderate correlations were found between SS scores and PI (r=0.47, p=0.0001), GI (r=0.45, p=0.0001), PD (r=0.42, p=0.0001), and AL (r=0.30, p=0.002). Analysis of variance showed significant differences in SS scores among the three study groups (p = 0.0001); post-hoc analysis showed higher SS scores in periodontitis subjects than non-periodontitis subjects (p = 0.05). Nominal logistic regression adjusting for smoking showed the odds ratio of periodontitis increase by a factor of 12.76 for each increase of one unit of measure of SS. Conclusion: The results suggest that assessing whole saliva sulfur levels with a chromogenic strip has potential as a screening test for periodontal diseases. / Oral Biology

The iron-sulfur flavoprotein (Isf) from the acetate utilizing methanoarchaeon Methanosarcina thermophila was heterologously produced in Escherichia coli, purified to homogeneity, and characterized to determine the properties of the iron-sulfur cluster and FMN. Chemical and spectroscopic analyses indicated that Isf contained one 4Fe-4S cluster and one FMN per monomer. The midpoint potentials of the [4Fe-4S]2+/1+ center and FMN/FMNH2 redox couple were -394 and -277 mV respectively. The deduced amino acid sequence of Isf revealed high identity with Isf homologues from the CO2 reducing methanoarchaea Methanococcus jannaschii and Methanobacterium thermoautotrophicum. Extracts of H2-CO2-grown M. thermoautotrophicum cells were able to reduce Isf from M. thermophila using either H2 or CO as the reductant. Addition of ferredoxin A to the reaction further stimulated the rate of Isf reduction. These results suggest that Isf homologues are coupled to ferredoxin in electron transfer chains in methanoarchaea with diverse metabolic pathways. Reconstituted systems containing carbon monoxide dehydrogenase/acetyl-CoA synthase complex (CODH/ACS), ferredoxin A, Isf, and the designated electron carriers (NAD, NADP, F420, and 2-hydroxyphenazine) were used in an attempt to determine the electron acceptor for Isf. Isf was unable to reduce any of these compounds. Furthermore, 2-hydroxyphenazine competed with Isf to accept electrons from ferredoxin A indicating that ferredoxin A is a more favorable electron partner for 2-hydroxyphenazine. Thus, the physiological electron acceptor for Isf is unknown. Amino acid sequence alignment of Isf sequences revealed a conserved atypical cysteine motif with the potential to ligate the 4Fe-4S cluster. Site-directed mutagenesis of the cysteine residues in this motif, and the two additional cysteines in the sequence, was used to investigate these cysteine residue as ligands for coordinating the 4Fe-4S center of Isf. Spectroscopic and biochemical analyses were consistent with the conserved cysteine motif functioning as ligating the 4Fe-4S center. Redox properties of the 4Fe-4S and FMN centers revealed a role for the 4Fe-4S center in the transfer of electrons from ferredoxin A to FMN. / Ph. D.