Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Cytokines and programming the pre-implantation embryo.

As the pre-implantation embryo traverses the female reproductive tract, it experiences fluctuations in the composition of the surrounding maternal environment, including the availability of nutrients, growth factors and cytokines. In particular, the cytokine milieu surrounding the early embryo is pivotal in programming optimal embryo development. The pre-implantation embryo is sensitive to a range of perturbations such as maternal diet or in vitro culture. These and other insults influencing the maternal environment including infection, stress and environmental toxins may in part act via impact on oviduct and uterine cytokine synthesis. However the effect of maternal perturbation to inflammation or infection, on the embryo and the role of cytokines in mediating this is not fully elucidated. The studies described in this thesis employed an in vivo mouse model of maternal systemic inflammation with the proinflammatory bacterial lipopolysaccharide (LPS), where a pro-inflammatory cytokine response was elicited on days 2.5 and 3.5 post coitum (pc), prior to implantation. This model was studied in wildtype C57Bl/6 (Il10 ⁺ʹ⁺) mice and mice with a null mutation in the Il10 gene (Il10 ⁻ʹ⁻) were studied to investigate the effects of maternal deficiency in the anti-inflammatory cytokine IL-10 during LPS treatment. We demonstrated that the altered cytokine signals resulting from a low level pro inflammatory LPS challenge (0.5 μg/mouse) in the pre-implantation period elicit changes in the embryo developmental trajectory that in turn alter fetal growth and delay postnatal growth in the male progeny from LPS-treated mothers. As LPS did not directly impact development of the embryo at low and moderate doses, this result appears to reflect indirect effects of LPS mediated via the maternal tract. This is consistent with data from day 3.5 pc oviduct and uterus tissues which revealed increased mRNA expression of proinflammatory cytokines including Il6, Tnfa and Il12b following maternal LPS treatment. Peri-conceptional low dose LPS treatment in Il10 ⁺ʹ⁺ and Il10 ⁻ʹ⁻ mice revealed that the number of viable fetuses and fetal weight were both significantly reduced after LPS treatment, particularly in the Il10 ⁻ʹ⁻ mice. Embryo transfer was then utilised to investigate the mechanism by which LPS acts on the embryo, where day 3.5 pc embryos from donors treated with 0.5 μg LPS or PBS on days 2.5 and 3.5pc were transferred into day 2.5 pc pseudopregnant Swiss female recipients. The effect of maternal LPS treatment on fetal and placental development was seen to be maintained even after embryo transfer, suggesting that any effects of altered cytokine expression in embryos are exerted during cleavage stages before embryo recovery from donors. In addition, postnatal investigation of male and female progeny derived from control PBS and LPStreated Il10 ⁺ʹ⁺ and Il10 ⁻ʹ⁻ females from birth until 19 weeks of age showed that maternal LPS treatment constrains postnatal growth in male progeny regardless of maternal Il10 genotype, compared to male progeny from PBS-treated mothers. While the adult male progeny from LPS-treated Il10 ⁺ʹ⁺ and Il10 ⁻ʹ⁻ mothers did not display changes in fat mass compared to their PBS-treated control counterparts, the combination of maternal LPS treatment and maternal IL-10 deficiency resulted in greater fat mass accumulation in the adult male progeny from LPS-treated Il10 ⁻ʹ⁻ mothers compared to adult male progeny from LPS-treated Il10 ⁺ʹ⁺ mothers. In addition, we investigated the effects of maternal systemic inflammation during the pre-implantation period on the response to LPS challenge during adulthood. Male progeny from LPS-treated Il10 ⁻ʹ⁻ mothers had a dampened response in LIF cytokine following a 100μg/kg LPS challenge at 18 weeks of age. This study implies a role for cytokines as mediators of programming the embryo during the preimplantation period, with altered responses in the event of maternal systemic inflammation impacting on later fetal and postnatal development. The anti-inflammatory cytokine IL-10 acts to protect the embryo from the adverse programming effects of exposure to LPS during the pre-implantation period, with absence of IL-10 resulting in altered postnatal phenotype and particularly fat mass accumulation in the male progeny during adulthood. It appears likely that the absence of IL-10 in the maternal environment delays the clearance of adverse pro-inflammatory cytokines induced during an inflammatory challenge, resulting in prolonged exposure of the embryo to circulating pro-inflammatory cytokines in the maternal tract, supporting a cytokine-mediated mechanism. These studies provide additional evidence for a role of cytokines in embryo sensing of environmental conditions, and indicate that IL-10 is a key regulator of this communication pathway.Thesis (Ph.D.) -- University of Adelaide, School of Paediatrics and Reproductive Health, 201

Toll-like Receptor-4: A New Target for Preterm Labour Pharmacotherapies?

Inflammatory activation, a major driver of preterm birth and subsequent neonatal morbidity, is an attractive pharmacological target for new preterm birth therapeutics. Inflammation elicited by intraamniotic infection is causally associated with preterm birth, particularly in infants delivered ≤34 weeks' gestation. However, sterile triggers of PTB, including placental ischaemic injury, uterine distention, cervical disease, or imbalance in the immune response, also act through inflammatory mediators released in response to tissue damage. Toll-like Receptors (TLRs) are critical upstream gate-keepers controlling the inflammatory activation that precedes preterm delivery, as well as in normal term labour. In particular, TLR4 is implicated for its capacity to sense and integrate a range of disparate infectious and sterile pro-inflammatory triggers, and so acts as a point-ofconvergence through which a range of infectious and sterile agents can activate and accelerate the parturition cascade. Recent studies point to the TLR4 signalling complex as a tractable target for the inhibition of fetal, placental & intraamniotic inflammatory cytokine production. Moreover, studies on mice show that novel small molecule antagonists of TLR4 signalling are highly effective in preventing preterm birth induced by bacterial mimetic LPS, heat-killed E. coli or the TLR4-dependent pro-inflammatory lipid, Platelet Activating Factor (PAF). In this review, we discuss the role of TLR4 in regulating the timing of birth and the potential utility of TLR4 antagonists as novel therapeutics for preterm delivery

Toll-like receptor-4 antagonist (D)-naltrexone protects against carbamyl- platelet activating factor (cPAF)-induced preterm labor in mice

Spontaneous preterm labor is frequently caused by an inflammatory response in the gestational tissues elicited by either infectious or sterile agents. In sterile preterm labor, the key regulators of inflammation are not identified, but platelet-activating factor (PAF) is implicated as a potential rate-limiting effector agent. Since Toll-like receptor (TLR)-4 can amplify PAF signaling, we evaluated whether TLR4 contributes to inflammation and fetal loss in a mouse model of PAF-induced sterile preterm labor, and whether a small-molecule TLR4 inhibitor, (þ)-naltrexone, can mitigate adverse PAF-induced effects. The administration of carbamyl (c)-PAF caused preterm labor and fetal loss in wild-type mice but not in TLR4-deficient mice. Treatment with (þ)-naltrexone prevented preterm delivery and alleviated fetal demise in utero elicited after cPAF administered by i.p. or intrauterine routes. Pups born after cPAF and (þ)-naltrexone treatment exhibited comparable rates of postnatal survival and growth to carrier-treated controls. (þ)-Naltrexone suppressed the cPAF-induced expression of inflammatory cytokine genes Il1b, Il6, and Il10 in the decidua; Il6, Il12b, and Il10 in the myometrium; and Il1b and Il6 in the placenta. These data demonstrate that the TLR4 antagonist (þ)-naltrexone inhibits the inflammatory cascade induced by cPAF, preventing preterm birth and perinatal death. The inhibition of TLR4 signaling warrants further investigation as a candidate strategy for fetal protection and delay of preterm birth elicited by sterile stimuli