Development and internal validation of clinical prediction models for outcomes of complicated intra-abdominal infection.

BACKGROUND: Complicated intra-abdominal infections (cIAIs) are associated with significant morbidity and mortality. The aim of this study was to describe the clinical characteristics of patients with cIAI in a multicentre study and to develop clinical prediction models (CPMs) to help identify patients at risk of mortality or relapse. METHODS: A multicentre observational study was conducted from August 2016 to February 2017 in the UK. Adult patients diagnosed with cIAI were included. Multivariable logistic regression was performed to develop CPMs for mortality and cIAI relapse. The c-statistic was used to test model discrimination. Model calibration was tested using calibration slopes and calibration in the large (CITL). The CPMs were then presented as point scoring systems and validated further. RESULTS: Overall, 417 patients from 31 surgical centres were included in the analysis. At 90 days after diagnosis, 17.3 per cent had a cIAI relapse and the mortality rate was 11.3 per cent. Predictors in the mortality model were age, cIAI aetiology, presence of a perforated viscus and source control procedure. Predictors of cIAI relapse included the presence of collections, outcome of initial management, and duration of antibiotic treatment. The c-statistic adjusted for model optimism was 0.79 (95 per cent c.i. 0.75 to 0.87) and 0.74 (0.73 to 0.85) for mortality and cIAI relapse CPMs. Adjusted calibration slopes were 0.88 (95 per cent c.i. 0.76 to 0.90) for the mortality model and 0.91 (0.88 to 0.94) for the relapse model; CITL was -0.19 (95 per cent c.i. -0.39 to -0.12) and - 0.01 (- 0.17 to -0.03) respectively. CONCLUSION: Relapse of infection and death after complicated intra-abdominal infections are common. Clinical prediction models were developed to identify patients at increased risk of relapse or death after treatment, these now require external validation.

Cross-sectional study of the prevalence, causes and management of hospital-onset diarrhoea.

BACKGROUND: The National Health Service in England advises hospitals collect data on hospital-onset diarrhoea (HOD). Contemporaneous data on HOD are lacking. AIM: To investigate prevalence, aetiology and management of HOD on medical, surgical and elderly-care wards. METHODS: A cross-sectional study in a volunteer sample of UK hospitals, which collected data on one winter and one summer day in 2016. Patients admitted ≥72 h were screened for HOD (definition: ≥2 episodes of Bristol Stool Type 5-7 the day before the study, with diarrhoea onset >48 h after admission). Data on HOD aetiology and management were collected prospectively. FINDINGS: Data were collected on 141 wards in 32 hospitals (16 acute, 16 teaching). Point-prevalence of HOD was 4.5% (230/5142 patients; 95% confidence interval (CI) 3.9-5.0%). Teaching hospital HOD prevalence (5.9%, 95% CI 5.1-6.9%) was twice that of acute hospitals (2.8%, 95% CI 2.1-3.5%; odds ratio 2.2, 95% CI 1.7-3.0). At least one potential cause was identified in 222/230 patients (97%): 107 (47%) had a relevant underlying condition, 125 (54%) were taking antimicrobials, and 195 (85%) other medication known to cause diarrhoea. Nine of 75 tested patients were Clostridium difficile toxin positive (4%). Eighty (35%) patients had a documented medical assessment of diarrhoea. Documentation of HOD in medical notes correlated with testing for C. difficile (78% of those tested vs 38% not tested, P<0.001). One-hundred and forty-four (63%) patients were not isolated following diarrhoea onset. CONCLUSION: HOD is a prevalent symptom affecting thousands of patients across the UK health system each day. Most patients had multiple potential causes of HOD, mainly iatrogenic, but only a third had medical assessment. Most were not tested for C. difficile and were not isolated.

The effect of renal denervation on kidney oxygenation as determined by BOLD MRI in patients with hypertension.

OBJECTIVES: Renal denervation (RDN) is a promising therapy for resistant hypertension. RDN is assumed to decrease sympathetic activity. Consequently, RDN can potentially increase renal oxygenation. Blood oxygen level-dependent MRI (BOLD-MRI) provides a non-invasive tool to determine renal oxygenation in humans. The aim of the current study was to investigate the effect of RDN on renal oxygenation as determined by BOLD-MRI. METHODS: Patients with resistant hypertension or the inability to follow a stable drug regimen due to unacceptable side effects were included. BOLD-MRI was performed before and 12 months after RDN. Twenty-seven patients were imaged on 3 T and 19 on 1.5 T clinical MRI systems. RESULTS: Fifty-four patients were included, 46 patients (23 men, mean age 57 years) completed the study. Mean 24-h BP changed from 163(±20)/98(±14) mmHg to 154(±22)/92(±13) mmHg (p = 0.001 and p < 0.001). eGFR did not change after RDN [77(±18) vs. 79(±20) mL/min/1.73 m(2); p = 0.13]. RDN did not affect renal oxygenation [1.5 T: cortical R2*: 12.5(±0.9) vs. 12.5(±0.9), p = 0.94; medullary R2*: 19.6(±1.7) vs. 19.3(1.4), p = 0.40; 3 T: cortical R2*: 18.1(±0.8) vs. 17.8(±1.2), p = 0.47; medullary R2*: 27.4(±1.9) vs. 26.7(±1.8), p = 0.19]. CONCLUSION: The current study shows that RDN does not lead to changes in renal oxygenation 1 year after RDN as determined by BOLD-MRI. KEY POINTS: • Renal denervation significantly decreased ambulatory blood pressure. • Renal denervation did not change renal oxygenation as determined by BOLD-MRI. • Absence of a change in renal oxygenation might be explained by autoregulation.

The effect of percutaneous renal denervation on muscle sympathetic nerve activity in hypertensive patients.

OBJECTIVE: The rationale of percutaneous renal denervation (RDN) is based on extensive studies suggesting that renal nerves contribute to hypertension and that they comprise a sensible treatment target. Muscle sympathetic nerve activity (MSNA) is considered to be one of the few reliable methods to quantify central sympathetic activity. The aim of this current study is to determine the effect of RDN on MSNA in a standardized fashion. METHODS: MSNA was determined in 13 patients before and 6months after RDN. Anti-hypertensive medication was stopped before MSNA. If cessation of medication was considered unsafe, a patient was instructed to use the exact same medication on both occasions. RESULTS: Ten sets of MSNA recordings were of good quality for analysis. Mean age was 57 ± 3 years and mean eGFR was 85 ± 18 mL/min/1.73 m(2). MSNA was determined twice during a medication free interval in 5 patients; 1 patient used the exact same medication twice, and 4 patients used different drugs. Mean BP changed from 206 ± 7 over 116 ± 4 mmHg, to 186 ± 6 over 106 ± 3 mmHg, 6 months after RDN (p=0.06 for systolic BP, p=0.04 for diastolic BP). Mean resting heart rate did not change (p=0.44). MSNA did not change after RDN: 37 ± 4 bursts/min and 43 ± 4 bursts/min (p=0.11) at baseline and after RDN, respectively. In the 6 patients with standardized medication use during the MSNA sessions, results were comparable. CONCLUSIONS: Treatment with RDN did not result in a change in MSNA. Changes in BP did not correlate with changes in MSNA.

Down-regulation of hepatic and intestinal Abcg5 and Abcg8 expression associated with altered sterol fluxes in rats with streptozotocin-induced diabetes.

AIM/HYPOTHESIS: Type I diabetes is associated with altered hepatic bile formation and increased intestinal cholesterol absorption. The aim of this study was to evaluate whether altered expression of the ATP-Binding Cassette half-transporters Abcg5 and Abcg8, recently implicated in control of both hepatobiliary cholesterol secretion and intestinal cholesterol absorption, contributes to changed cholesterol metabolism in experimental diabetes. METHODS: mRNA and protein expression of Abcg5 and Abcg8 were determined in the liver and intestine of rats with streptozotozin-induced diabetes and related to relevant metabolic parameters in plasma, liver and bile. RESULTS: Hepatic mRNA expression of both Abcg5 (-76%) and Abcg8 (-71%) was reduced in diabetic rats when compared to control rats. In spite of increased HDL cholesterol, considered a major source of biliary cholesterol, secretion of the sterol into bile relative to that of bile salts was reduced by 65% in diabetic animals. Intestinal mRNA expression of Abcg5 (-47%) and Abcg8 (-43%) as well as Abcg5 protein contents were also reduced in insulin-deficient animals. This was accompanied by a three- to four-fold increase in plasma beta-sitosterol and campesterol concentrations and by a doubling of the calculated apparent cholesterol absorption. These effects partially normalized upon insulin supplementation. CONCLUSION/INTERPRETATION: Our data indicate that effects of insulin-deficiency on bile composition and cholesterol absorption in rats are, at least partly, attributable to changes in hepatic and intestinal Abcg5 and Abcg8 expression.

Low external pH induces HOG1-dependent changes in the organization of the Saccharomyces cerevisiae cell wall.

Low environmental pH strongly affected the organization of the Saccharomyces cerevisiae cell wall, resulting in rapidly induced resistance to beta1,3-glucanase. At a molecular level, we found that a considerable amount of Cwp1p became anchored through a novel type of linkage for glycosylphosphatidylinositol (GPI)-dependent cell wall proteins, namely an alkali-labile linkage to beta1,3-glucan. This novel type of modification for Cwp1p did not require the presence of a GPI-derived structure connecting the protein with beta1,6-glucan. In addition, we found high levels of Cwp1p, which was double-anchored through both the novel alkali-sensitive bond to beta1,3-glucan and the alkali-resistant GPI-derived linkage to beta1,6-glucan. Further cell wall analyses demonstrated that Pir2p/Hsp150 and possibly other Pir cell wall proteins, which were already known to be linked to the beta1,3-glucan framework by an alkali-sensitive linkage, were also more efficiently retained in the cell wall at pH 3.5 than at pH 5.5. Consequently, the alkali-sensitive type of linkage of cell wall proteins to beta1,3-glucan was induced by low pH. The low pH-induced alterations in yeast cell wall architecture were demonstrated to be dependent on a functional HOG1 gene, but not on the Slt2p-mediated MAP kinase pathway. Consistent with this observation, DNA microarray studies revealed transcriptional induction of many known high-osmolarity glycerol (HOG) pathway-dependent genes, including four cell wall-related genes, namely CWP1, HOR7, SPI1 and YGP1.

Localization of synthesis of beta1,6-glucan in Saccharomyces cerevisiae.

Beta1,6-Glucan is a key component of the yeast cell wall, interconnecting cell wall proteins, beta1,3-glucan, and chitin. It has been postulated that the synthesis of beta1,6-glucan begins in the endoplasmic reticulum with the formation of protein-bound primer structures and that these primer structures are extended in the Golgi complex by two putative glucosyltransferases that are functionally redundant, Kre6 and Skn1. This is followed by maturation steps at the cell surface and by coupling to other cell wall macromolecules. We have reinvestigated the role of Kre6 and Skn1 in the biogenesis of beta1,6-glucan. Using hydrophobic cluster analysis, we found that Kre6 and Skn1 show significant similarities to family 16 glycoside hydrolases but not to nucleotide diphospho-sugar glycosyltransferases, indicating that they are glucosyl hydrolases or transglucosylases instead of genuine glucosyltransferases. Next, using immunogold labeling, we tried to visualize intracellular beta1,6-glucan in cryofixed sec1-1 cells which had accumulated secretory vesicles at the restrictive temperature. No intracellular labeling was observed, but the cell surface was heavily labeled. Consistent with this, we could detect substantial amounts of beta1,6-glucan in isolated plasma membrane-derived microsomes but not in post-Golgi secretory vesicles. Taken together, our data indicate that the synthesis of beta1, 6-glucan takes place largely at the cell surface. An alternative function for Kre6 and Skn1 is discussed.

Retention of Saccharomyces cerevisiae cell wall proteins through a phosphodiester-linked beta-1,3-/beta-1,6-glucan heteropolymer.

Yeast cell wall proteins, including Cwp1p and alpha-agglutinin, could be released by treating the cell wall with either beta-1,3-or beta-1,6-glucanases, indicating that both polymers are involved in anchoring cell wall proteins. It was shown immunologically that both beta-1,3- and beta-1,6-glucan were linked to yeast cell wall proteins, including Cwp1p and alpha-agglutinin. It was further shown that beta-1,3-glucan was linked to the wall protein through a beta-1,6-glucan moiety. The beta-1,6-glucan moiety could be removed from Cwp1p and other cell wall proteins by cleaving phosphodiester bridges either enzymatically using phosphodiesterases or chemically using ice-cold aqueous hydrofluoric acid. These observations are consistent with the notion that cell wall proteins in Saccharomyces cerevisiae are linked to a beta-1,3-/beta-1,6-glucan heteropolymer through a phosphodiester linkage and that this polymer is responsible for anchoring cell wall proteins. It is proposed that this polymer is identical to the alkali-soluble beta-1,3-/beta-1,6-glucan heteropolymer characterized by Fleet and Manners (1976, 1977).