Influence of transferable genetic determinants on the outcome of typing methods commonly used for Enterococcus faecium

A variety of methods is used for a molecular typing of Enterococcus spp. and related gram-positive bacteria including macrorestriction analysis using pulsed-field gel electrophoresis (PFGE), ribotyping, rapid amplification of polymorphic DNA (RAPD), and amplified fragment length polymorphism (AFLP). To test the influence of transferable determinants on the outcome of different typing methods commonly used for enterococci, we established a homogenous strain collection of 24 transconjugants resulting from filter matings with antibiotic-resistant Enterococcus faecium. As expected, AFLP, RAPD, and PFGE all identified our model bacteria as strongly related. However, distinct differences in the resolving and discriminatory power of the tested methods could be clearly addressed. In PFGE, 22 of 24 transconjugants possessed less than a three-band difference to the recipient pattern and would be regarded as strongly related. Three different RAPD PCRs were tested; in two reactions, identical patterns for all transconjugants and the recipient were produced. One RAPD PCR produced an identical pattern for 18 transconjugants and the recipient and a clearly different pattern for the remaining 6 transconjugants due to a newly appearing fragment resulting from acquisition of the tetL gene. AFLP clusters all transconjugants into a group of major relatedness. Percent similarities were highly dependent on the method used for calculating the similarity coefficient (curve-based versus band-based similarity coefficient). Fragment patterns of digested plasmids showed the possession of nonidentical plasmids in most transconjugants. PFGE still could be recommended as the method of choice. Nevertheless, the more-modern AFLP approach produces patterns of comparable discriminatory power while possessing some advantages over PFGE (less-time-consuming internal standards). Plasmid fingerprints can be included to subdifferentiate enterococcal isolates possessing identical macrorestriction and PCR typing patterns.     

Age-related changes in prefrontal activity during walking in dual-task situations: A fNIRS study

Background

Previous studies suggest that the human gait is under control of higher-order cognitive processes, located in the frontal lobes, such that an age-related degradation of cognitive capabilities has a negative impact on gait.

Methods

Using functional Near-Infrared-Spectroscopy (fNIRS) we investigate the frontocortical hemodynamic correlates of dual-task walking in two conditions. 15 young and 10 older individuals walked on a treadmill while completing concurrent tasks that had either visual (checking) or verbal-memory (alphabet recall) demands. We compared subjects' motor performance, as well as their prefrontal activity in single- and dual-task walking.

Results

Our behavioral data partly confirm previous accounts on higher dual-task costs in stepping parameters (i.e., decreased step duration) in old age, particularly with a visual task and negative dual-task cost (i.e., improved performance) during the verbal task in young adults. Functional imaging data revealed little change of prefrontal activation from single- to dual-task walking in young individuals. In the elderly, however, prefrontal activation substantially decreased during dual-task walking with a complex visual task.

Conclusion

We interpret these findings as evidence for a shift of processing resources from the prefrontal cortex to other brain regions when seniors face the challenge of walking and concurrently executing a visually demanding task.     

Structural genomic variation in childhood epilepsies with complex phenotypes

A genetic contribution to a broad range of epilepsies has been postulated, and particularly copy number variations (CNVs) have emerged as significant genetic risk factors. However, the role of CNVs in patients with epilepsies with complex phenotypes is not known. Therefore, we investigated the role of CNVs in patients with unclassified epilepsies and complex phenotypes. A total of 222 patients from three European countries, including patients with structural lesions on magnetic resonance imaging (MRI), dysmorphic features, and multiple congenital anomalies, were clinically evaluated and screened for CNVs. MRI findings including acquired or developmental lesions and patient characteristics were subdivided and analyzed in subgroups. MRI data were available for 88.3% of patients, of whom 41.6% had abnormal MRI findings. Eighty-eight rare CNVs were discovered in 71 out of 222 patients (31.9%). Segregation of all identified variants could be assessed in 42 patients, 11 of which were de novo. The frequency of all structural variants and de novo variants was not statistically different between patients with or without MRI abnormalities or MRI subcategories. Patients with dysmorphic features were more likely to carry a rare CNV. Genome-wide screening methods for rare CNVs may provide clues for the genetic etiology in patients with a broader range of epilepsies than previously anticipated, including in patients with various brain anomalies detectable by MRI. Performing genome-wide screens for rare CNVs can be a valuable contribution to the routine diagnostic workup in patients with a broad range of childhood epilepsies.     

Phantom testis syndrome: prevalence, phenomenology and putative mechanisms

Chronic phantom pain has been found in up to 78% of limb amputees and is a major complication of limb amputation. Less is known about phantom phenomena after the amputation of other, i.e. visceral, parts of the body. In a retrospective design, we identified 539 patients in whom one testis was removed between 1995 and 2005. The operative technique was a unilateral standard radical inguinal orchiectomy. The underlying pathology in all cases was a testicular germ cell tumour. All patients received a detailed questionnaire asking about the occurrence of phantom testis pain (pain felt in the removed testis), phantom testis sensations (non-painful sensations as if the removed testis was still intact) and hallucinations (illusionary perceptions on the removed testis). Furthermore, we asked about the occurrence and clinical presentation of pain before and after surgery and about pre-operative testicular pain. Out of 238 respondents, 125 patients (53%) reported any kind of phantom experience. The prevalence of phantom testis pain was 25% (60/238), non-painful phantom sensations 16% (37/238) and male gonad hallucinations 12% (28/238). Patients with phantom symptoms reported pre-operative pain in the removed testis more often than patients without phantom symptoms. This study presents first data on the clinical characteristics and possible mechanisms of the phantom testis syndrome after surgical removal of one testis.     

Dendritic cell activating peptides induce distinct cytokine profiles

High-mobility group box 1 protein (HMGB1), a DNA-binding nuclear and cytosolic protein, is a pro-inflammatory cytokine released by monocytes and macrophages. HMGB1 as well as its B box domain induce maturation of human dendritic cells (DCs). This report demonstrates that the B box domain induces phenotypic maturation of murine bone marrow-derived dendritic cells (BM-DCs) as evidenced by increased CD86, CD40 and MHC-II expression. The B box domain enhanced secretion of pro-inflammatory cytokines and chemokines: IL-1beta, IL-2, IL-5, IL-8, IL-12 and tumor necrosis factor (TNF)-alpha, but not IL-6 and IL-10. Furthermore, four peptides whose sequences correspond to different regions of HMGB1 induced production of IL-1beta, IL-2 and IL-12 (p70), but not IL-10 and IL-6 in mouse BM-DCs. Interestingly, these peptides differed in their capacity to induce TNF-alpha, IL-5, IL-18 and IL-8. B box domain as well as peptide-activated DCs acted as potent stimulators of allogeneic T cells in a mixed leukocyte reaction. DCs exposed to HMGB1 peptides induced proliferation of ovalbumin-specific syngeneic T cells. These DC-activating peptides could serve as an adjuvant in immunotherapeutic or vaccine context and the selective activity of these different peptides suggests a means to customize the functional properties of DCs.     

Extrinsic versus intrinsic cues in avian paraxial mesoderm patterning and differentiation.

Somitic and head mesoderm contribute to cartilage and bone and deliver the entire skeletal musculature. Studies on avian somite patterning and cell differentiation led to the view that these processes depend solely on cues from surrounding tissues. However, evidence is accumulating that some developmental decisions depend on information within the somitic tissue itself. Moreover, recent studies established that head and somitic mesoderm, though delivering the same tissue types, are set up to follow their own, distinct developmental programmes. With a particular focus on the chicken embryo, we review the current understanding of how extrinsic signalling, operating in a framework of intrinsically regulated constraints, controls paraxial mesoderm patterning and cell differentiation.