Generalizability of predictive models for Clostridioides difficile infection, severity and recurrence at an urban safety-net hospital.

INTRODUCTION: Predictive models for Clostridioides difficile infection can identify high-risk patients and aid clinicians in preventing infection. Issues of generalizability regarding current predictive models have been acknowledged but, to the authors' knowledge, have never been quantified. METHODS: C. difficile infection, severity and recurrence predictive models were created using multi-variate logistic regression through case-control sampling from an urban safety-net hospital. Models were validated using five-fold cross-validation, and inverse probability weights (IPW) based on two different catchment area definitions were used to improve external validity. Akaike Information Criterion (AIC), area under the receiver operating characteristic curve (AUROC), and sensitivity and specificity with bootstrapped confidence intervals (CI) were used to assess and compare model fit and performance. RESULTS: Changes in performance before and after weighting were small across all models, although differences were more apparent after weighting the recurrence model (AUROC values of 0.78, 0.76 and 0.71 for the unweighted and two weighted models, respectively). Overall, the infection model performed the best (AUROC 0.82, 95% CI 0.78-0.85), followed by the recurrence model (AUROC 0.78, 95% CI 0.69-0.86) and then the severity model (AUROC 0.70, 95% CI 0.63-0.78). CONCLUSIONS: The performance of the models after weighting did not change drastically, suggesting that the models predicting C. difficile infection, severity and recurrence may not be impacted by patient selection factors. However, other researchers may wish to consider addressing these catchment forces using IPW.

Labelling medical devices: still waiting for the defining moment.

Recent developments in labelling and use of symbols are reviewed in this article together with the issues still being debated. Different symbols for the same concept continue to be a concern as well as the definition of the symbol for "sterile" for terminally sterilized devices. The essential message is that there is still some way to go before the requirement are totally clear.

Effects of exercise training on responses of peripheral and visceral arteries in swine.

Blood flow to skeletal muscle during exercise is greater in the trained state. We hypothesized that intrinsic vasomotor reactivity of arteries to active muscle during training bouts would be altered to favor a relative vasodilation after training. To test this hypothesis, miniature swine were pen confined (Sed; n = 30) or treadmill trained for 5 days/wk over 16-20 wk (Trn; n = 32). Efficacy of training was indicated by myocardial hypertrophy (4.84 +/- 0.11 and 5.81 +/- 0.12 g/kg body wt for Sed and Trn, respectively, P < 0.0005), training bradycardia at several submaximal running speeds of a maximal exercise test, increased running time to exhaustion (26 +/- 1 and 35 +/- 1 min for Sed and Trn, respectively, P < 0.0005), and increased oxidative capacities of several locomotory skeletal muscles. Segments of femoral, brachial, mesenteric, renal, and hepatic arteries were isolated from Sed and Trn swine. Isometric contractile and relaxation properties of vascular rings cut from these segments were determined in vitro. Contractile responses to KCl and norepinephrine (NE) were determined, as were relaxation responses to sodium nitroprusside and adenosine, agents acting directly on vascular smooth muscle, and the endothelium-dependent agents bradykinin and the calcium ionophore A-23187. Responses to vasocontractile and vasorelaxation agents were not different between Sed and Trn swine for vessels serving active muscles (i.e., femoral, brachial). On the other hand, renal arterial rings from Trn swine exhibited lesser contractile responses than those from Sed swine across a range of NE concentrations (P < 0.05) and approximately 25% less maximal contractile response to NE (32.7 +/- 2.6 and 24.2 +/- 2.1 g for Sed and Trn, respectively, P < 0.01). Responses of other vessels serving viscera (i.e., mesenteric, hepatic) were unchanged with training. These data indicate that vasomotor reactivity of porcine conduit-type arteries generally does not change with exercise training. An exception is the lesser contractile response to NE in renal artery, which could permit better preservation of renal blood flow during acute exercise in trained animals.

Comparison of kappa 2-opioid receptors in guinea pig brain and guinea pig ileum membranes.

The presence of kappa-opioid receptor subtypes has been clearly established in guinea pig brain. Using [3H]bremazocine in the presence of reversible blockers of mu, delta and kappa 1 receptors, two additional binding sites can be determined in guinea pig brain membranes. The site with higher affinity for the opioid ligands represents kappa 2, while the other site has low affinity and is poorly characterized. The kappa 2 site has high affinity for ethylketocyclazocine and other benzomorphans, as well as for the dynorphin gene products tested. The dynorphin analogs have no appreciable affinity for the low affinity site, so this site should not be called a kappa receptor. With an appropriate membrane preparation, kappa 2 binding can also be demonstrated in the guinea pig ileum. Binding affinities for selected ligands at kappa 2 in guinea pig ileum membranes are very similar to affinities found in brain membranes.

Indolent presentation of pancreatic abscess. Experience with 100 cases.

One hundred cases of pancreatic abscess were identified at five hospitals affiliated with UCLA between 1973 and 1985. Patients were included if a pancreatic mass or phlegmon followed an episode of pancreatitis, if the clinical impression was pancreatic abscess, and if drainage cultures were positive. Less than three Ranson's signs were present on admission in 72% of patients. The admission temperature was less than 38.3 degrees C in 71% of patients, and 27% of patients never had a fever. Abdominal tenderness was absent in 40% of patients. The admission amylase concentrations and white blood cell counts were normal in 36% and 23% of patients, respectively. Extensive débridement, external drainage, and a low threshold for reoperation were the mainstays of surgical therapy. Twenty patients (20%) died, but Ranson's signs did not predict outcome. pancreatic abscess may have an insidious presentation. A high index of suspicion, early computed tomographic scanning, and diagnostic needle aspiration may be necessary to establish this diagnosis.