Metabolite-mediated modelling of microbial community dynamics captures emergent behaviour more effectively than species-species modelling

Personalized models of the gut microbiome are valuable for disease prevention and treatment. For this, one requires a mathematical model that predicts microbial community composition and the emergent behaviour of microbial communities. We seek a modelling strategy that can capture emergent behaviour when built from sets of universal individual interactions. Our investigation reveals that species-metabolite interaction (SMI) modelling is better able to capture emergent behaviour in community composition dynamics than direct species-species modelling. Using publicly available data, we examine the ability of species-species models and species-metabolite models to predict trio growth experiments from the outcomes of pair growth experiments. We compare quadratic species-species interaction models and quadratic SMI models and conclude that only species-metabolite models have the necessary complexity to explain a wide variety of interdependent growth outcomes. We also show that general species-species interaction models cannot match the patterns observed in community growth dynamics, whereas species-metabolite models can. We conclude that species-metabolite modelling will be important in the development of accurate, clinically useful models of microbial communities.

Extreme value analysis of gut microbial alterations in colorectal cancer

Gut microbes play a key role in colorectal carcinogenesis, yet reaching a consensus on microbial signatures remains a challenge. This is in part due to a reliance on mean value estimates. We present an extreme value analysis for overcoming these limitations. By characterizing a power-law fit to the relative abundances of microbes, we capture the same microbial signatures as more complex meta-analyses. Importantly, we show that our method is robust to the variations inherent in microbial community profiling and point to future directions for developing sensitive, reliable analytical methods.

Beta-blocker, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker, nitrate-hydralazine, diuretics, aldosterone antagonist, ivabradine, devices and digoxin (BANDAID(2) ): an evidence-based mnemonic for the treatment of systolic heart failure

Heart failure causes significant morbidity and mortality, with recognised underutilisation rates of guideline-based therapies. Our aim was to review current evidence for heart failure treatments and derive a mnemonic summarising best practice, which might assist physicians in patient care. Treatments were identified for review from multinational society guidelines and recent randomised trials, with a primary aim of examining their effects in systolic heart failure patients on mortality, hospitalisation rates and symptoms. Secondary aims were to consider other clinical benefits. MEDLINE and EMBASE were searched using a structured keyword strategy and the retrieved articles were evaluated methodically to produce an optimised reference list for each treatment. We devised the mnemonic BANDAID (2) , standing for beta-blocker, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker, nitrate-hydralazine (or potentially neprilysin inhibitor), diuretics, aldosterone antagonist, ivabradine, devices (automatic implantable cardioverter defibrillator, cardiac resynchronisation therapy or both) and digoxin as a representation of treatments with strong evidence for their use in systolic heart failure. Treatment with omega-3 fatty acids, statins or anti-thrombotic therapies has limited benefits in a general heart failure population. Adoption of this mnemonic for current evidence-based treatments for heart failure may help improve prescribing rates and patient outcomes in this debilitating, high mortality condition.

A national common massive transfusion protocol (MTP) is a feasible and advantageous option for centralized blood services and hospitals

BACKGROUND

A common national MTP was jointly implemented in 2011 by the national blood service (Blood Services Group) and seven participating acute hospitals to provide rapid access to transfusion support for massively haemorrhaging patients treated in all acute care hospitals.

METHODS

Through a systematic clinical workflow, blood components are transfused in a ratio of 1:1:1 (pRBC: whole blood-derived platelets: FFP), together with cryoprecipitate for fibrinogen replacement. The composition of components for the MTP is fixed, although operational aspects of the MTP can be adapted by individual hospitals to suit local hospital workflow. The MTP could be activated in support of any patient with critical bleeding and at risk of massive transfusion, including trauma and non-trauma general medical, surgical and obstetric patients.

RESULTS

There were 434 activations of the MTP from October 2011 to October 2013. Thirty-nine per cent were for trauma patients, and 30% were for surgical patients with heavy intra-operative bleeding, with 25% and 6% for patients with gastrointestinal bleeding and peri-partum haemorrhage, respectively. Several hospitals reported reduction in mean time between request and arrival of blood. Mean transfusion ratio achieved was one red cell unit: 0·8 FFP units: 0·8 whole blood-derived platelet units: 0·4 units of cryoprecipitate. Although cryoprecipitate usage more than doubled after introduction of MTP, there was no significant rise in overall red cells, platelet and FFP usage following implementation.

CONCLUSION

This successful collaboration shows that shared transfusion protocols are feasible and potentially advantageous for hospitals sharing a central blood provider.

The impact of clinical protocols in the management of severe sepsis: a prospective cohort study

This study aimed to assess the availability of clinical protocols and their effect on compliance to the Surviving Sepsis Campaign bundles and on mortality in severe sepsis in ten Singaporean adult teaching intensive care units (ICU). The presence of 11 protocols in the ICUs, steps taken based on the Johns Hopkins University Quality and Safety Research Group's model to translate protocols into practice, and organisational characteristics were assessed. Clinical and research personnel recorded characteristics of patients with severe sepsis who were admitted in July 2009, the achievement of sepsis bundle targets and outcomes. Hospital mortality was 39% for 128 patients. Fewer than half of the ICUs had protocols for early goal-directed therapy, blood cultures, antibiotics, steroids, lung-protective ventilation and weaning. Compliance rates with the resuscitation and management bundles were 18 and 3% respectively. Units with protocols were generally not more likely to achieve associated bundle targets. Steps from the Johns Hopkins model to measure performance, engage teams and sustain and extend interventions were taken in fewer than half of the available protocols. However, on logistic regression analysis, the number of protocols available per ICU was independently and inversely associated with mortality. In conclusion, clinical protocols are infrequently available in Singapore's ICUs and when present do not generally improve compliance to the sepsis bundles. These protocols may, however, be a surrogate marker of the quality of care as they are independently associated with decreased mortality. The use of an integrated and multifaceted approach to translate protocols into practice should be considered.

Accuracy of ProSeal™ Laryngeal Mask Airway Intracuff Pressure Estimation using Finger Palpation technique – A Prospective, Observational Study

The incidence of pharyngolaryngeal adverse events associated with laryngeal mask airways can be reduced by the use of manometry to limit the laryngeal mask airway intracuff pressures. We conducted a prospective, observational study in 80 patients undergoing general anaesthesia with the ProSeal™ laryngeal mask airway to determine the accuracy of a finger palpation technique compared to actual readings obtained from a handheld manometer by different anaesthesia personnel. The strength of association of estimated versus actual intracuff pressures, R, for nurse anaesthesia assistants, junior anaesthetists and senior anaesthetists were 0.21 (weak), 0.35 (moderate) and 0.78 (strong) respectively. Subgroup analysis showed that anaesthetists with more than three years of experience were more accurate than those with less than three years of experience. The actual versus estimated intracuff pressures were 4±17 vs 19±27 cmH2O ( P value <0.001) respectively. In all groups, the palpation technique tended to underestimate the actual intracuff pressure by a mean of 10.3 cmH2O. Palpation accuracy decreased when actual intracuff pressures were >80 cmH2O. These findings suggest that cuff pressure manometry should be recommended as standard of care with the use of laryngeal mask airways.

Peripheral nerve blocks for lower limb surgery--a choice anaesthetic technique for patients with a recent myocardial infarction?

Peripheral nerve blocks are associated with minimal haemodynamic disturbance. It is perhaps ideal for high-risk surgical patients who cannot tolerate the adverse consequences of even the slightest attenuation of haemodynamic response. However, peripheral nerve blockade is often perceived to be time consuming and undependable as the sole anaesthetic. In this report, a 56-year-old man with severe sepsis and recent myocardial infarction presents for an urgent above knee amputation. We present the practical benefits of a combined sciatic-femoral nerve block on such a patient.

The genetics of psoriasis 2001: the odyssey continues

Accumulating evidence indicates that psoriasis is a multifactorial disorder caused by the concerted action of multiple disease genes in a single individual, triggered by environmental factors. Some of these genes control the severity of multiple diseases by regulating inflammation and immunity (severity genes), whereas others are unique to psoriasis. Various combinations of these genes can occur even within a single family, accounting in large measure for the many clinical manifestations of psoriasis. The disease-causing variants (alleles) of these genes probably arose early in the history of modern humans. As a result, psoriasis disease alleles are common in the general population, have a worldwide distribution, and often share the same ancestral chromosome with neutral alleles at adjacent loci. This phenomenon, called linkage disequilibrium, explains why psoriasis is strongly associated with HLA-Cw6 worldwide, although HLA-Cw6 is unlikely to be the disease allele. Many unaffected individuals carry 1 or more disease alleles, but lack other genetic and/or environmental factors necessary to produce disease. This explains why psoriasis develops in only about 10% of HLA-Cw6-positive individuals, and why genome-wide linkage scans for psoriasis and other multifactorial genetic disorders have not been uniformly successful. The Human Genome Project is rapidly generating a catalog of human DNA sequence variations. This resource has already allowed precise linkage disequilibrium mapping of the major histocompatibility complex psoriasis gene to just beyond HLA-C, toward HLA-A. This gene is likely to be identified soon. Further development and use of linkage disequilibrium resources will provide a powerful tool for the identification of the remaining psoriasis genes.

Identification of marker chromosomes in thirteen patients using FISH probing

Fourteen marker chromosomes were studied by FISH (fluorescence in-situ hybridization) in cytogenetic preparations from 13 patients. The derived markers were identified as one isodicentric bisatellited mar(22), one fragment sized r(X), one fragment sized r(Y), one i(18p), small autosomal ring markers in three different patients derived from chromosomes 2, 8, and 8, a marker comprised of 9p and part of 9qh, and 3 bisatellited apparently monocentric markers; one of each from chromosomes 13 or 21, 14 or 22, and 15. Two fragment sized small ring markers in one patient and a small ring marker in another were negative with all twenty-two different probes used. In addition, the small ring marker Y chromosome that was found in a boy with karyotype 46,X,-Y,+mar was negative with both pDXZ1 and pDYZ3. This anomaly of negative results with the battery of centromeric alphoid probes can be explained if one breakpoint for some small ring markers is very near to or within the centromere. Only some of the pericentromeric repetitive sequences in the normal chromosome would be represented in the chromosome specific alphoid probes, and presumably those corresponding to the currently available probes are truncated during the formation of the unidentified markers. In three of the small ring markers the FISH signal on the marker was much stronger than on the normal homologues in various proportions of cells, and this may indicate that some of the fragment sized small rings were multicentric. The literature was reviewed for Distamycin A/DAPI negative small ring markers that were present as extra chromosomes. There were only single published cases of most small rings but there were three r(8) cases, two r(1) cases, two r(12) cases, and two r(20) cases, uncomplicated by the presence of other chromosome abnormalities. Most cases with similar small rings were quite dissimilar phenotypically and syndrome identification was not possible, but in pooled data, 18/23 (about 80%) were developmentally and/or phenotypically abnormal. Some patients (5/23, about 20%) with small rings were dysmorphic without intellectual handicap. Of 28 such patients with small ring markers (Distamycin/Dapi negative) in pooled data there are 6 (about 20%) with multiple markers mostly derived from different chromosomes. This is a very high figure and would suggest that the ring formation events, although involving different chromosomes, must be related and must be an indicator of the mechanism of origin of this group of markers.

Candida albicans infected pseudocyst in a postpartum woman

We have presented the case of a postpartum woman with a pseudocyst infected with C albicans and have reviewed the relevant literature. The patient did well with surgical drainage of the pseudocyst and adjunctive therapy with amphotericin B. Candida species isolated from a pancreatic pseudocyst or abscess should be considered pathogens, and the patient should receive aggressive therapy.