Oral Microbiome and Gingival Transcriptome Profiles of Ligature-Induced Periodontitis

This investigation evaluated the relationship of the oral microbiome and gingival transcriptome in health and periodontitis in nonhuman primates (Macaca mulatta). Subgingival plaque samples and gingival biopsies were collected from healthy sites and at sites undergoing ligature-induced periodontitis. Microbial samples were analyzed with 16S amplicon sequencing to identify bacterial profiles in young (3 to 7 y) and adult (12 to 23 y) animals. The gingival transcriptome was determined with a microarray analysis and focused on the expression level of 452 genes that are associated with the development of inflammation and innate and adaptive immune responses. Of the 396 total operational taxonomic units (OTUs) identified across the samples, 81.8% were detected in the young group and 99.5% in the adult group. Nevertheless, 58 of the OTUs composed 88% of the signal in adults, and 49 OTUs covered 91% of the OTU readouts in the young group. Correlation analyses between the microbiome members and specific gingival genes showed a high number of significant bacteria-gene correlations in the young healthy tissues, which decreased by 75% in diseased tissues. In contrast, these correlations increased by 2.5-fold in diseased versus healthy tissues of adult animals. Complexes of bacteria were delineated that related to specific sets of immune genes, differing in health and disease and in the young versus adult animals. The correlated gene profiles demonstrated selected pathway overrepresentation related to particular bacterial complexes. These results provide novel insights into microbiome changes with disease and the relationship of these changes to specific gene profiles and likely biologic activities occurring in healthy and diseased gingival tissues in this human-like periodontitis model.

Gabapentin in naive childhood absence epilepsy: results from two double-blind, placebo-controlled, multicenter studies

Efficacy and safety of gabapentin monotherapy were evaluated in 33 children with newly diagnosed absence epilepsy in two identical, double-blind, placebo-controlled trials in which a 2-week double-blind treatment phase was followed by a 6-week open-label phase. Primary efficacy criterion was seizure frequency change from baseline to end of double-blind treatment derived from quantified electroencephalograms. Primary efficacy analyses compared treatment differences in the 2-week double-blind phase. Gabapentin did not significantly decrease or increase seizure frequency compared with placebo. Low dosages with possibly subtherapeutic plasma levels may have contributed to the lack of demonstrable efficacy. Somnolence and dizziness were the only adverse events reported by at least two patients during gabapentin treatment. No clinically important changes in laboratory assessments or other safety parameters were observed. Gabapentin monotherapy at dosages ranging from 9.7 through 19.1 mg/kg/day is well tolerated in pediatric patients aged 4 through 12 years with absence epilepsy.

An in vitro study of the characteristics of a computer-aided radiographic evaluation (CARE) system for longitudinal assessment of density changes

In recent years, several systems for computerized analysis of radiographs have been introduced, most of which use digital conversion of the image followed by subtraction of consecutive images to assess changes. This paper introduces a computer-based qualitative and quantitative radiographic evaluation system based on the CADIA algorithm. Problems associated with computerized radiographic analysis are discussed and evaluation criteria for this type of system are suggested. These criteria include evaluation of system noise and threshold setting, reproducibility, and establishment of the system working curve (validity). The CARE system noise ranged from a -10 to +10 CADIA value and the threshold was set on 13 for all measurements. The reproducibility was high, both for the radiographic technique and for repeated measurements. The working curve was established and showed the system's ability to detect small density changes of 0.048 O.D. which corresponds to 0.27 mm of aluminium thickness or compact bone equivalent. The linear range of the curve was between 0.7 and 1.8 O.D. By controlling the exposure parameters it was possible to work within the linear range of the curve. Based on these evaluation criteria, the CARE system can be used to quantitatively evaluate small density changes on sequential radiographs for early detection of caries and periodontal disease.

Ulnar neuropathy after median sternotomy

Ulnar neuropathy is a known complication of median sternotomy surgery, and its precise cause is not clear. The authors hypothesize that a "double-crush" phenomenon caused by intraoperative compression of the brachial plexus occurs in a patient with preexisting, previously undiagnosed slowing of ulnar nerve conduction. Eighty-four arms in 42 patients scheduled for cardiac surgery were studied. Pre- and postoperative history and physical examinations were performed by separate blinded examiners; however, the nerve conduction studies were performed by a single examiner. Fifteen arms (18%) in 11 patients (26%) clinically demonstrated postoperative neuropathy. After surgery, all symptomatic patients had considerable slowing of their preoperative conduction studies. A direct correlation appears to exist between preoperative slowing of ulnar nerve conduction and postmedian sternotomy neuropathy. A careful preoperative evaluation including nerve conduction studies may detect the predisposed patient; the surgeon attempting postoperative cubital tunnel decompression is cautioned that the lesion may not be an isolated one.

Ictal EEG changes with corpus callosum section

Corpus callosum section diminishes but does not completely abolish secondary bilaterally synchronous interictal EEG discharges, yet often causes cessation of generalized seizures. The effects of corpus callosum section on ictal EEG patterns have not been described. We contrasted ictal EEG patterns before and after anterior callosotomy in 18 patients and before and after total callosotomy in 10 patients. Bilaterally synchronous seizure onset was disrupted in 5 of 11 anterior section patients and 5 of 5 total section patients. Seven of 18 anterior section patients and 5 of 10 total section patients had more localized seizure onset after the procedure; localization to the frontal lobe was observed after anterior or total section, but only total section patients had newly demonstrated posterior locations of seizure onset. These data suggest that the mechanisms by which bilaterally synchronous interictal and ictal discharges are generated differ. Although brainstem or diencephalic structures may contribute to formation of interictal bilateral synchrony, the corpus callosum may be the only pathway used in producing apparent bilateral synchronous seizure onset in patients with secondarily generalized seizures.

Cloning and expression of the leukotoxin gene from Actinobacillus actinomycetemcomitans

The leukotoxin produced by Actinobacillus actinomycetemcomitans has been implicated in the etiology of juvenile periodontitis. To initiate a genetic analysis of the role of this protein in disease, we have cloned the leukotoxin gene in Escherichia coli. Recombinant colonies carrying toxin gene sequences were isolated by screening a genomic A. actinomycetemcomitans library with a DNA probe for the leukotoxin gene from a related bacterium, Pasteurella haemolytica. To demonstrate that the cloned A. actinomycetemcomitans DNA contained a functional leukotoxin gene, protein extracts of E. coli containing the A. actinomycetemcomitans clone were tested directly for leukotoxic activity against human cell lines in chromium release assays. A construct containing the entire cloned region produced a functional toxin. No cytotoxicity was seen when extracts from cells containing plasmids with deletions in the putative coding region were used. Furthermore, the toxin produced by the cloned gene has the same target cell specificity as the leukotoxin extracted directly from A. actinomycetemcomitans. These results indicate that sequences encoding a functional leukotoxin have been cloned and are expressed in E. coli. Southern blot analysis of DNA from leukotoxin-producing (Lkt+) and non-leukotoxin-producing (Lkt-) strains indicated that the Lkt- strain also contained a copy of the gene.

Implantation of Bacteroides gingivalis in nonhuman primates initiates progression of periodontitis

Although periodontitis is a bacterial disease, its multidimensional nature and its bacterial complexity have made it difficult to definitively prove that specific microorganisms initiate the disease process. The successful implantation of a rifampin-resistant strain of the putative periodontal pathogen Bacteroides gingivalis into the periodontal microbiota of monkeys (Macaca fascicularis) resulted in an increase in the systemic levels of antibody to the microorganism and rapid and significant bone loss.

Distribution of indicator bacteria and Vibrio parahaemolyticus in sewage-polluted intertidal sediments

The impact of a sewage point source on the bacterial densities in an intertidal mud flat in Boston Harbor, Mass., was investigated. The area, Savin Hill Cove, acts as a receiving basin for a combined storm and sewage outlet (CSO). Preliminary examination of sediments and overlying water at high tide demonstrated that fecal coliforms were present in sediments at abundances 2 to 4 orders of magnitude higher than in the overlying water column. The following bacterial counts were determined from sediments along a sampling transect extending 460 m from the CSO: total bacteria by epifluorescent microscopy, heterotrophic bacteria by plate counts on nutrient-rich and nutrient-poor media, fecal coliforms and enterococci by membrane filtration, and Vibrio parahaemolyticus by a most-probable-number technique with a resuscitation step. Median sediment grain size, average tidal exposure, carbon/nitrogen ratio, and total organic carbon were also measured. All bacterial indices, except for V. parahaemolyticus, declined significantly with distance from the outfall. Multiple regression analysis indicated that tidal exposure (low tides) may affect densities of total bacteria. Fecal coliforms and enterococci were still present in appreciable numbers in sediments as far as 460 m away from the CSO. In contrast, V. parahaemolyticus densities did not correlate with the other bacterial counts nor with any of the environmental parameters examined. These results indicate that intertidal sediments which adjoin point sources of pollution are severely contaminated and should be considered as potentially hazardous reservoirs of sewage-borne diseases.