The relationships between streptococcal species and periodontopathic bacteria in human dental plaque

The existence of antagonistic and commensal relationships between microorganisms was investigated. The predominant cultivable flora in 172 plaque samples from active and non-active sites in 32 human subjects with destructive periodontitis was determined. The presence of putative periodontopathic organisms (Bacteroides gingivalis, Bacteroides intermedius, Bacteroides forsythus, Wolinella recta, Actinobacillus actinomycetemcomitans, and Eikenella corrodens) in a site was correlated with the absence of certain viridans streptococci (Streptococcus sanguis, Streptococcus uberis and Streptococcus intermedius), and vice versa. A strong commensal relationship was found between B. gingivalis and Strep. intermedius. The second study involved 3 subjects with intractable periodontitis whose plaque harboured large numbers of one or more of these periodontopathic organisms. This plaque contained fewer organisms capable of inhibiting the growth of the periodontopathic strains in vitro when compared with a clinically-healthy control subject. Intermediate levels of inhibitors were found in plaque taken from non-active lesions. The majority of inhibitors in plaque from the healthy control were viridans streptococci. Hydrogen-peroxide production by these organisms appears to be the principal mechanism of growth inhibition for periodontopathic organisms. Bacterial interactions may thus be causally related to both periodontal health and disease.     

Detection of antiendometrial antibodies in patients with endometriosis: methodological issues.

OBJECTIVE: To determine if methodological reasons explain previous inability of a single investigator to detect antiendometrial antibodies in patients with endometriosis by indirect immunofluorescence (IIF). DESIGN: Sera of selected patients were tested by standard IIF and recently reported methodology. Alternate diluent experiments were conducted to explain discordant results. SETTING: Sera were obtained preoperatively, and testing was completed in an institutional research laboratory. Results are compared with surgical findings. PATIENTS/PARTICIPANTS: Patients, seven with endometriosis and six without endometriosis, 40 years of age or less who are presenting for gynecological surgery. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Indirect immunofluorescence was graded according to the presence or absence of cytoplasmic staining, intensity of the staining, and the lowest dilution at which staining was observed. RESULTS: The standard IIF method repeatedly demonstrated the presence of cytoplasmic staining for the presence of antiendometrial antibodies in patients with endometriosis, whereas modified methods did not produce similar positive staining results. During the alternate dilution experiments, when fluorescein isothiocyanate conjugate (FITC) was diluted in animal sera, negative results were obtained. CONCLUSIONS: The variations used in alternate methodology and failure to titrate FITC reported by other investigators are possible reasons for false-negative results reported.     

Interaction between wild-type, mutant and revertant forms of the bacterium Streptococcus sanguis and the bacterium Actinobacillus actinomycetemcomitans in vitro and in the gnotobiotic rat

In vitro, Streptococcus sanguis inhibits the growth of Actinobacillus actinomycetemcomitans, a presumed aetiological agent of localized juvenile periodontitis. When provided with glucose and good aeration, a growing culture of Strep. sanguis was found to produce hydrogen peroxide at concentrations in excess of the maximum LD50 reported for strains of A. actinomycetemcomitans. This concentration of hydrogen peroxide also inhibits the growth of the producer organism. A mutant of Strep. sanguis was isolated that lacked the ability to produce alpha-haemolysis on blood agar. This mutant had less than 3 per cent of its parent's level of pyruvate-oxidase activity, and made no detectable hydrogen peroxide. In vitro, the mutant had also lost the ability to inhibit the growth of A. actinomycetemcomitans. A spontaneous revertant, isolated by its ability to produce alpha-haemolysis, was found to have regained parental levels of pyruvate-oxidase activity and hydrogen-peroxide production and could inhibit the growth of A. actinomycetemcomitans in vitro. A gnotobiotic rat model was used to demonstrate that Strep. sanguis and A. actinomycetemcomitans interact in vivo and that this interaction depends on hydrogen-peroxide production by Strep. sanguis.     

Capillary junctions of the rat are not affected by osmotic opening of the blood-brain barrier

Summary Osmotic opening of the blood-brain barrier had no effect on the structure of the interendothelial tight junctions located within approximately 9 m² of brain capillary endothelial plasma membrane (junction-containing) examined in this study. These tight junctions restrict the passive diffusion between the blood and the brain and constitute the anatomic basis of the blood-brain barrier. Increased permeability of the blood-brain barrier in the cerebral cortex of the right hemisphere of rats, induced by an infusion of a hypertonic solution of arabinose and monitored with the protein tracer horseradish peroxidase (HRP), was evidenced by the extravasation of the tracer into the extracellular compartment of the brain. Freeze-fracture analysis of the capillaries from the same tissue revealed no alterations in the intramembrane components of the endothelial tight junctions. The junctions, which consist of 8–12 highly anastomosed parallel ridges situated on the PF fracture face of the endothelial plasmalemma, showed no loss of ridge continuity or intraridge connections, and were identical to zonulae occludentes from control capillaries. Consistent labeling of numerous vesiculo-tubular elements by HRP in the endothelia of experimental tissue and the threedimensional nature of these elements observed in platinum replicas support the interpretation that these structures represent transendothelial conduits which are continuous with the luminal and abluminal surfaces of the endothelial cells. Absence of similar structures in control endothelia is taken as evidence that their presence in experimental tissues is a direct response to the osmotic insult. It was concluded, therefore, that during osmotic opening of the blood-brain barrier passage of HRP across the endothelium of brain capillaries is not by an inter-endothelial route due to disruption of tight junctions but rather by a transendothelial route due to amplified vesicular activity.Supported by the Natural Science and Engineering Council of Canada     

Religiosity,Spirituality, and Socioemotional Functioning in Mothers of Children with Autism Spectrum Disorder

Religious beliefs, religious activities, and spirituality are coping resources used by many mothers of children with autism spectrum disorder (ASD). This study examined whether and how these resources were related to maternal socioemotional functioning. Mothers of children with ASD completed questionnaires assessing religiosity, spirituality, and a wide range of outcome variables, including stress, depression, self-esteem, life satisfaction, positive affect, and sense of control. Analyses revealed that religious beliefs and spirituality were associated with better positive outcomes and, to a lesser extent, lower levels of negative outcomes. Of the two predictors, spirituality accounted for more unique variance in positive outcomes. In contrast, religious activities were related to more negative outcomes and lower levels of positive outcomes.     

Regional node dissection for melanoma: techniques and indication

Because virtually all microscopic nodal disease left untreated in melanoma patients will progress to clinically apparent macroscopic nodal disease, there is worse prognosis with macroscopic nodal disease, and ineffective systemic treatment currently exists, one must be cautious in favoring an observation approach to the regional basin in patients with a positive sentinel lymph node (SLN) in the hopes of avoiding the potential morbidity of a therapeutic node dissection. In the few patients with untreated microscopic nodal disease, the prognosis will be significantly worsened. Until further data are available, melanoma patients with a positive SLN by H&E analysis should proceed to a complete lymph node dissection.     

Magnetic resonance imaging temporarily alters blood-brain barrier permeability in the rat

Exposure to a short (23.2 min) standard clinical magnetic resonance imaging (MRI) procedure elicits a temporary dysfunction of the blood-brain barrier in rats. Monitoring of the increased permeability of rat brain frontal cortex microvessels with the protein tracer horseradish peroxidase and freeze-fracture electron microscopy, revealed an amplified vesicle-mediated transport of tracer across the microvessel endothelium to the albuminal basal lamina and extracellular compartment of the brain parenchyma. Recovery of normal blood-brain function, as evidenced by exclusion of protein tracer from subendothelial basal lamina and neuropil extracellular milieu, was complete 15-30 min following cessation of the MRI exposure. These findings raise the possibility that exposure to clinical MRI procedures may also temporarily alter central blood-brain permeability in human subjects.