Staphylococcal pathogenicity island interference with helper phage reproduction is a paradigm of molecular parasitism

Staphylococcal pathogenicity islands (SaPIs) carry superantigen and resistance genes and are extremely widespread in Staphylococcus aureus and in other Gram-positive bacteria. SaPIs represent a major source of intrageneric horizontal gene transfer and a stealth conduit for intergeneric gene transfer; they are phage satellites that exploit the life cycle of their temperate helper phages with elegant precision to enable their rapid replication and promiscuous spread. SaPIs also interfere with helper phage reproduction, blocking plaque formation, sharply reducing burst size and enhancing the survival of host cells following phage infection. Here, we show that SaPIs use several different strategies for phage interference, presumably the result of convergent evolution. One strategy, not described previously in the bacteriophage microcosm, involves a SaPI-encoded protein that directly and specifically interferes with phage DNA packaging by blocking the phage terminase small subunit. Another strategy involves interference with phage reproduction by diversion of the vast majority of virion proteins to the formation of SaPI-specific small infectious particles. Several SaPIs use both of these strategies, and at least one uses neither but possesses a third. Our studies illuminate a key feature of the evolutionary strategy of these mobile genetic elements, in addition to their carriage of important genes—interference with helper phage reproduction, which could ensure their transferability and long-term persistence.     

Effect of ozone on periodontopathogenic species—an in vitro study

The in vitro study was aimed to determine the effect of ozone on periodontopathogenic microorganisms. Ozone was generated for 6 s–2 × 24 s (corresponding to 0.56 mg–2 × 2.24 mg of ozone) against 23 mainly anaerobic periodontopathogenic species. Agar diffusion test was used as a screening method. Then, the killing activity was tested in a serum-free environment and with 25% v/v inactivated serum. Further, the effect of ozone on bactericidal activity of native serum was analyzed against Fusobacterium nucleatum, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans. Agar diffusion test showed a high efficacy of ozone against microorganisms, especially against Porphyromonas gingivalis. This result was confirmed by the killing tests; most of the strains in a concentration of 10⁵ were completely eliminated after twofold 18-s application of ozone. Only four of the six potentially “superinfecting” species (Staphylococcus aureus, Enterococcus faecalis, Enterobacter cloacae, Candida albicans) survived in part. Addition of heat-inactivated serum reduced the killing rate of ozone by 78% after 6-s and by 47% after twofold 18-s exposures; no strain was completely eradicated after any application of ozone. The bactericidal effect of native serum was enhanced after application of ozone; no effect was visible on the included A. actinomycetemcomitans strain which was found to be completely resistant to the bactericidal action of serum. In conclusion, (a) ozone has a strong antibacterial activity against putative periodontopathogenic microorganisms, and (b) the bactericidal effect is reduced in the presence of serum. Ozone may have potential as an adjunctive application to mechanical treatment in periodontitis patients.     

Asymmetric segregation and self-renewal of hematopoietic stem and progenitor cells with endocytic Ap2a2

The stem cell-intrinsic model of self-renewal via asymmetric cell division (ACD) posits that fate determinants be partitioned unequally between daughter cells to either activate or suppress the stemness state. ACD is a purported mechanism by which hematopoietic stem cells (HSCs) self-renew, but definitive evidence for this cellular process remains open to conjecture. To address this issue, we chose 73 candidate genes that function within the cell polarity network to identify potential determinants that may concomitantly alter HSC fate while also exhibiting asymmetric segregation at cell division. Initial gene-expression profiles of polarity candidates showed high and differential expression in both HSCs and leukemia stem cells. Altered HSC fate was assessed by our established in vitro to in vivo screen on a subcohort of candidate polarity genes, which revealed 6 novel positive regulators of HSC function: Ap2a2, Gpsm2, Tmod1, Kif3a, Racgap1, and Ccnb1. Interestingly, live-cell videomicroscopy of the endocytic protein AP2A2 shows instances of asymmetric segregation during HSC/progenitor cell cytokinesis. These results contribute further evidence that ACD is functional in HSC self-renewal, suggest a role for Ap2a2 in HSC activity, and provide a unique opportunity to prospectively analyze progeny from HSC asymmetric divisions.     

Cross Validation of the b Test in a Large Known Groups Sample

The b Test (Boone, Lu, & Herzberg, 2002a) is a measure of cognitive performance validity originally validated on 91 non-credible participants and 7 credible clinical comparison groups (total n?=?161). The purpose of the current study was to provide cross-validation data for the b Test on a known groups sample of non-credible participants (n?=?212) and credible heterogeneous neuropsychological clinic patients (n?=?103). The new data showed that while the original E-score cut-off of ≥155 achieved excellent specificity (99%), it was associated with relatively poor sensitivity (41%). However, the cut-off could be substantially lowered to ≥82, while still maintaining adequate specificity (≥90%) and raising sensitivity to 68%. Examination of non-credible subgroups revealed that b Test sensitivity in feigned mild traumatic brain injury (mTBI) was 58%, whereas in non-credible patients claiming depression and psychosis, cut-off sensitivity was 76% and 67%, respectively. These data suggest that the b Test may have a particular role in detection of non-credible cognitive symptoms associated with feigned psychiatric symptoms, and that fabricated deficits in processing speed and vigilance/visual scanning, detected by the b Test, are more prominent in feigned psychiatric presentations than in feigned mTBI. Further, b Test failures in patients with somatoform disorders were common, indicating that the b Test may have a specific use in detection of non-consciously created cognitive dysfunction associated with somatoform conditions.     

Chronic Social Stress in the Community and Associations with Psychological Distress: A Social Psychological Perspective

Chronic social stress is strongly related to psychological distress in vulnerable groups such as the frail elderly and ill people. Little, however, is known about these phenomena in the general population. The validity and reliability of a new brief measure, the Bergen Social Relationships Scale (BSRS), were investigated in a Norwegian county; the prevalence of chronic social stress was measured using the BSRS, and the associations of chronic social stress and social support with three measures of psychological distress were investigated. Respondents with high BSRS scores had experienced longstanding, important interpersonal relationship problems rather than fleeting stressful incidents. Women reported higher levels of chronic social stress, 60% reporting positively on at least one of the six BSRS items, compared with 50% among men. Social support was negatively and significantly associated with various measures of psychological distress. Chronic social stress was positively and significantly associated with psychological distress. These effects were independent of one another. No buffering effect of social support on social stress was observed. The present data support the importance of positive social ties to health, but suggest that social stress is an independent aspect of social environment with regard to health. If social support and social stress have direct and independent effects on mental health, as the present results indicate, intervention on the one will not necessarily modify the other. Intervention programmes may need to consider explicitly both the lighter and the darker sides of social relationships in building environments that support mental health.     

The potential association between gingival crevicular fluid inflammatory mediators and adverse pregnancy outcomes: a systematic review

Objectives

The association between periodontal disease and adverse pregnancy outcomes (APO), primarily preterm birth (PTB), is still controversially discussed in the literature. Therefore, the aim of the present systematic review was to analyze the existing literature on the potential association between inflammatory mediators detected in gingival crevicular fluid (GCF) and APO.

Materials and methods

MEDLINE (PubMed) and EMBASE databases were searched for entries up to April 2012 and studies were selected by two independent reviewers.

Results

The majority of the eight studies included confirmed a positive association between GCF mediators, such as interleukin-1β, prostaglandin E₂, and tumor necrosis factor-alpha, and APO. Due to the heterogeneity and variability of the available studies, no meta-analysis could be performed.

Conclusions

A positive association between GCF inflammatory mediator levels and APO/PTB might be present but the results need to be considered with great caution because of the heterogeneity and variability among the studies. Further studies with an adequate number of patients allowing for an appropriate analysis are warranted to definitely confirm this association.

Clinical relevance

The present findings suggest that an association between GCF inflammatory mediator levels and APO might exist.