Year in review in Intensive Care Medicine 2012. II: Pneumonia and infection, sepsis, coagulation, hemodynamics, cardiovascular and microcirculation, critical care organization, imaging, ethics and legal issues.

Journal ArticleSCOPUS: re.jSCOPUS: re.jinfo:eu-repo/semantics/publishe

Towards a better understanding of the development of the strength in Asymmetrical Friction Connections (AFC)

In the current design practice, the strength of Asymmetric Friction Connections (AFCs) is calculated considering the friction force developed at both sliding interfaces using the bolt tension reduced by the moment – shear - axial interaction (MPV) effect. However, available models do not consider the friction induced by the bolt assembly force, termed assembly effect, or the bolt inclination effect, which is the increase in the AFC strength due to the horizontal component of the bolt tension produced when the bolt inclines. This paper proposes a model for quantifying the strength of AFCs considering the assembly, MPV, and inclination effects for the cases: i). Before the slotted plate breakaway, ii). Bolts inclining up to the angle defined by the bole hole oversize and termed bolt elastic inclination, iii) Bolts inclination angles larger than the angle defined by the bole hole oversize and produced by bolt flexural yielding and termed bolt yielding inclination. The proposed model is validated from the testing of an AFC scaled prototype, and from the quasi – static testing of 18 AFCs in real scale and assembled with Bisalloy 500 shims, and 2 M16 Grade 8.8 bolts with bolt grip lengths between 52.5mm and 172.5mm. It is shown that before breakaway the hysteresis loop is linear, and the peak strength depends only on the assembly effect. For the bolt elastic inclination, the hysteresis loop shape is bilinear, and the peak strength depends on the combined action of the assembly, MPV, and inclination effects. For the bolt yielding inclination, the hysteresis loop is square and pinched and the average strength across the plateau of the hysteresis loop depends on the MPV and inclination effects. For the three cases considered, the proposed model predicts the AFC strength with accuracies of 76% – 120%. The proposed model shows the horizontal component of the bolt tension from the bolt inclination effect was 6% - 28% of the AFC strength for the bolt elastic inclination, and 38% - 53% of the AFC strength for the bolt yielding inclination

Modeling recursive RNA interference.

An important application of the RNA interference (RNAi) pathway is its use as a small RNA-based regulatory system commonly exploited to suppress expression of target genes to test their function in vivo. In several published experiments, RNAi has been used to inactivate components of the RNAi pathway itself, a procedure termed recursive RNAi in this report. The theoretical basis of recursive RNAi is unclear since the procedure could potentially be self-defeating, and in practice the effectiveness of recursive RNAi in published experiments is highly variable. A mathematical model for recursive RNAi was developed and used to investigate the range of conditions under which the procedure should be effective. The model predicts that the effectiveness of recursive RNAi is strongly dependent on the efficacy of RNAi at knocking down target gene expression. This efficacy is known to vary highly between different cell types, and comparison of the model predictions to published experimental data suggests that variation in RNAi efficacy may be the main cause of discrepancies between published recursive RNAi experiments in different organisms. The model suggests potential ways to optimize the effectiveness of recursive RNAi both for screening of RNAi components as well as for improved temporal control of gene expression in switch off-switch on experiments

Contrasting prefrontal cortex contributions to episodic memory dysfunction in behavioural variant frontotemporal dementia and alzheimer's disease

Recent evidence has questioned the integrity of episodic memory in behavioural variant frontotemporal dementia (bvFTD), where recall performance is impaired to the same extent as in Alzheimer's disease (AD). While these deficits appear to be mediated by divergent patterns of brain atrophy, there is evidence to suggest that certain prefrontal regions are implicated across both patient groups. In this study we sought to further elucidate the dorsolateral (DLPFC) and ventromedial (VMPFC) prefrontal contributions to episodic memory impairment in bvFTD and AD. Performance on episodic memory tasks and neuropsychological measures typically tapping into either DLPFC or VMPFC functions was assessed in 22 bvFTD, 32 AD patients and 35 age- and education-matched controls. Behaviourally, patient groups did not differ on measures of episodic memory recall or DLPFC-mediated executive functions. BvFTD patients were significantly more impaired on measures of VMPFC-mediated executive functions. Composite measures of the recall, DLPFC and VMPFC task scores were covaried against the T1 MRI scans of all participants to identify regions of atrophy correlating with performance on these tasks. Imaging analysis showed that impaired recall performance is associated with divergent patterns of PFC atrophy in bvFTD and AD. Whereas in bvFTD, PFC atrophy covariates for recall encompassed both DLPFC and VMPFC regions, only the DLPFC was implicated in AD. Our results suggest that episodic memory deficits in bvFTD and AD are underpinned by divergent prefrontal mechanisms. Moreover, we argue that these differences are not adequately captured by existing neuropsychological measures

Single- versus two- layer intestinal anastomosis: a meta-analysis of randomized controlled trials

BACKGROUND: To compare single- with two- layer intestinal anastomosis after intestinal resection: a meta-analysis of randomized controlled trials. METHODS: Randomized controlled trials comparing single- with two-layer intestinal anastomosis were identified using a systematic search of Medline, Embase and the Cochrane Library Databases covering articles published from 1966 to 2004. Outcome of primary interest was postoperative leak. A risk ratio for trial outcomes and weighted pooled estimates for data were calculated. A fixed-effect model weighted using Mantel-Haenszel methods and a random-effect model using DerSimonian-Laird methods were employed. RESULTS: Six trials were analyzed, comprising 670 participants (single-layer group, n = 299; two-layer group, n = 371). Data on leaks were available from all included studies. Combined risk ratio using DerSimonian-Laird methods was 0.91 (95% CI = 0.49 to 1.69), and indicated no significant difference. Inter-study heterogeneity was significant (χ(2 )= 10.5, d.f. = 5, p = 0.06). CONCLUSION: No evidence was found that two-layer intestinal anastomosis leads to fewer post-operative leaks than single layer. Considering duration of the anastomosis procedure and medical expenses, single-layer intestinal anastomosis appears to represent the optimal choice for most surgical situations

Pain, psychological distress and health-related quality of life at baseline and 3 months after radical prostatectomy

BACKGROUND: Inadequate management of postoperative pain is common, and postoperative pain is a risk factor for prolonged pain. In addition to medical and technical factors, psychological factors may also influence the experience of postoperative pain. METHODS: Pain was measured postoperatively at 24, 48, and 72 hr in hospital and after 3 months at home in 140 patients undergoing radical prostatectomy (RP). Patients answered questionnaires about anxiety and depression (HAD scale) and health-related quality of life (SF-36) at baseline and 3 months after surgery. RESULTS: In the first 3 postoperative days, mild pain was reported by 45 patients (32%), moderate pain by 64 (45%), and severe pain by 31 (22%) on one or more days. High postoperative pain scores were correlated with length of hospital stay and with high pain scores at home. Forty patients (29%) reported moderate (n = 35) or severe (n = 5) pain after discharge from hospital. Patients who experienced anxiety and depression preoperatively had higher postoperative pain scores and remained anxious and depressed 3 months after surgery. The scores for the physical domains in the SF-36 were decreased, while the mental health scores were increased at 3 months. Anxiety and depression were negatively correlated with all domains of the SF-36. CONCLUSION: There is a need for nurses to be aware of the psychological status of RP patients and its impact upon patients' experience of postoperative pain and recovery. The ability to identify patients with psychological distress and to target interventions is an important goal for future research

Synchrony and Physiological Arousal Increase Cohesion and Cooperation in Large Naturalistic Groups

Separate research streams have identified synchrony and arousal as two factors that might contribute to the effects of human rituals on social cohesion and cooperation. But no research has manipulated these variables in the field to investigate their causal – and potentially interactive – effects on prosocial behaviour. Across four experimental sessions involving large samples of strangers, we manipulated the synchronous and physiologically arousing affordances of a group marching task within a sports stadium. We observed participants’ subsequent movement, grouping, and cooperation via a camera hidden in the stadium’s roof. Synchrony and arousal both showed main effects, predicting larger groups, tighter clustering, and more cooperative behaviour in a free-rider dilemma. However, synchrony and arousal interacted on measures of clustering and cooperation: such that synchrony only encouraged closer clustering — and encouraged greater cooperation—when paired with physiological arousal. The research has implications for understanding the nature and co-occurrence of synchrony and physiological arousal in rituals around the world. It also represents the first use of real-time spatial tracking as a precise and naturalistic method of simulating collective rituals

Thermotolerance and molecular chaperone function of the small heat shock protein HSP20 from hyperthermophilic archaeon, Sulfolobus solfataricus P2

Small heat shock proteins are ubiquitous in all three domains (Archaea, Bacteria and Eukarya) and possess molecular chaperone activity by binding to unfolded polypeptides and preventing aggregation of proteins in vitro. The functions of a small heat shock protein (S.so-HSP20) from the hyperthermophilic archaeon, Sulfolobus solfataricus P2 have not been described. In the present study, we used real-time polymerase chain reaction analysis to measure mRNA expression of S.so-HSP20 in S. solfataricus P2 and found that it was induced by temperatures that were substantially lower (60°C) or higher (80°C) than the optimal temperature for S. solfataricus P2 (75°C). The expression of S.so-HSP20 mRNA was also up-regulated by cold shock (4°C). Escherichia coli cells expressing S.so-HSP20 showed greater thermotolerance in response to temperature shock (50°C, 4°C). By assaying enzyme activities, S.so-HSP20 was found to promote the proper folding of thermo-denatured citrate synthase and insulin B chain. These results suggest that S.so-HSP20 promotes thermotolerance and engages in chaperone-like activity during the stress response