Principles and Procedures for Assessment of Acute Toxicity Incorporating In Silico Methods

Acute toxicity in silico models are being used to support an increasing number of application areas including (1) product research and development, (2) product approval and registration as well as (3) the transport, storage and handling of chemicals. The adoption of such models is being hindered, in part, because of a lack of guidance describing how to perform and document an in silico analysis. To address this issue, a framework for an acute toxicity hazard assessment is proposed. This framework combines results from different sources including in silico methods and in vitro or in vivo experiments. In silico methods that can assist the prediction of in vivo outcomes (i.e., LD50) are analyzed concluding that predictions obtained using in silico approaches are now well-suited for reliably supporting assessment of LD50-based acute toxicity for the purpose of GHS classification. A general overview is provided of the endpoints from in vitro studies commonly evaluated for predicting acute toxicity (e.g., cytotoxicity/cytolethality as well as assays targeting specific mechanisms). The increased understanding of pathways and key triggering mechanisms underlying toxicity and the increased availability of in vitro data allow for a shift away from assessments solely based on endpoints such as LD50, to mechanism-based endpoints that can be accurately assessed in vitro or by using in silico prediction models. This paper also highlights the importance of an expert review of all available information using weight-of-evidence considerations and illustrates, using a series of diverse practical use cases, how in silico approaches support the assessment of acute toxicity.

Accuracy of Point-of-Care-Ultrasonography in Confirming Shoulder Reduction in Emergency Departments

Aims Accurate identification of the successful reduction of a dislocated shoulder could avoid additional episodes of procedural sedation and repeated performance of X-rays. The objective of this study was to assess the diagnostic accuracy of point-of-care-ultrasound (POCUS) in the confirmation of a successful joint reduction in patients with shoulder dislocation. Methods This was a single-centre, prospective observational study set in an urban academic ED in Ireland, with a convenience sample of adult patients with shoulder dislocation on X-ray. Ultrasound was performed on participants before and after joint reduction using a posterior approach technique. The operator's confidence levels were recorded after image acquisition. Results Thirty-three subjects were recruited. All dislocations were correctly identified on pre-reduction US, indicating a sensitivity of 100% (CI 89.42 - 100). Post-reduction US confirmed successful reduction in 30 subjects that were subsequently reported as such on X-Ray, giving it a specificity of 100% (CI 88.43 - 100). Failure to achieve reduction was correctly identified on US in three cases, resulting in post-reduction US Sensitivity of 100% (CI 29.24 - 100) and 100% accuracy (CI 89.42 - 100). Conclusion This study has shown that POCUS, with a posterior approach technique, has 100% sensitivity and specificity in confirming successful shoulder reduction in the ED.

Polyphenol-enriched berry extracts naturally modulate reactive proteins in model foods

Healthy foods like polyphenol-rich berries and high quality edible proteins are in demand in today's functional food marketplace, but it can be difficult to formulate convenient food products with physiologically-relevant amounts of these ingredients and still maintain product quality. In part, this is because proteins can interact with other food ingredients and precipitate destabilizing events, which can disrupt food structure and diminish shelf life. Proteins in foods can also interact with human receptors to provoke adverse consequences such as allergies. When proteins and polyphenols were pre-aggregated into stable colloidal particles prior to use as ingredients, highly palatable food formulations (with reduced astringency of polyphenols) could be prepared, and the overall structural properties of food formulations were significantly improved. All of the nutritive and phytoactive benefits of the proteins and concentrated polyphenols remained highly bioavailable, but the protein molecules in the particle matrix did not self-aggregate into networks or react with other food ingredients. Both the drainage half-life (a marker of structural stability) and the yield stress (resistance to flow) of model foams made with the protein-polyphenol particles were increased in a dose-dependent manner. Of high significance in this complexation process, the reactive allergenic epitopes of certain proteins were effectively blunted by binding with polyphenols, attenuating the allergenicity of the food proteins. Porcine macrophages produced TNF-α proinflammatory cytokine when provoked with whey protein, but, this response was blocked completely when the cells were stimulated with particles that complexed whey protein with cinnamon-derived polyphenols. Cytokine and chemokine production characteristic of allergic reactions were blocked by the polyphenols, allowing for the potential creation of hypoallergenic protein-berry polyphenol enriched foods.

Prone positioning reduces mortality from acute respiratory distress syndrome in the low tidal volume era: a meta-analysis

PURPOSE

Prone positioning for ARDS has been performed for decades without definitive evidence of clinical benefit. A recent multicenter trial demonstrated for the first time significantly reduced mortality with prone positioning. This meta-analysis was performed to integrate these findings with existing literature and test whether differences in tidal volume explain conflicting results among randomized trials.

METHODS

Studies were identified using MEDLINE, EMBASE, Cochrane Register of Controlled Trials, LILACS, and citation review. Included were randomized trials evaluating the effect on mortality of prone versus supine positioning during conventional ventilation for ARDS. The primary outcome was risk ratio of death at 60 days meta-analyzed using random effects models. Analysis stratified by high (>8 ml/kg predicted body weight) or low (≤ 8 ml/kg PBW) mean baseline tidal volume was planned a priori.

RESULTS

Seven trials were identified including 2,119 patients, of whom 1,088 received prone positioning. Overall, prone positioning was not significantly associated with the risk ratio of death (RR 0.83; 95% CI 0.68-1.02; p = 0.073; I (2) = 64%). When stratified by high or low tidal volume, prone positioning was associated with a significant decrease in RR of death only among studies with low baseline tidal volume (RR 0.66; 95% CI 0.50-0.86; p = 0.002; I (2) = 25%). Stratification by tidal volume explained over half the between-study heterogeneity observed in the unstratified analysis.

CONCLUSIONS

Prone positioning is associated with significantly reduced mortality from ARDS in the low tidal volume era. Substantial heterogeneity across studies can be explained by differences in tidal volume.

Spleen tyrosine kinase (Syk) regulates systemic lupus erythematosus (SLE) T cell signaling

Engagement of the CD3/T cell receptor complex in systemic lupus erythematosus (SLE) T cells involves Syk rather than the zeta-associated protein. Because Syk is being considered as a therapeutic target we asked whether Syk is central to the multiple aberrantly modulated molecules in SLE T cells. Using a gene expression array, we demonstrate that forced expression of Syk in normal T cells reproduces most of the aberrantly expressed molecules whereas silencing of Syk in SLE T cells normalizes the expression of most abnormally expressed molecules. Protein along with gene expression modulation for select molecules was confirmed. Specifically, levels of cytokine IL-21, cell surface receptor CD44, and intracellular molecules PP2A and OAS2 increased following Syk overexpression in normal T cells and decreased after Syk silencing in SLE T cells. Our results demonstrate that levels of Syk affect the expression of a number of enzymes, cytokines and receptors that play a key role in the development of disease pathogenesis in SLE and provide support for therapeutic targeting in SLE patients.

Variation in initial kidney replacement therapy for end-stage renal disease due to lupus nephritis in the United States

OBJECTIVE

Little is known about the patterns of use of initial kidney replacement therapies among patients with lupus nephritis (LN) end-stage renal disease (ESRD). We aimed to identify sociodemographic and clinical factors associated with variation in initial kidney replacement therapies among LN ESRD patients.

METHODS

Patients with incident LN ESRD (1995-2006) were identified in the US Renal Data System. Age, sex, race, ethnicity, medical insurance, employment status, residential region, clinical factors, and comorbidities were considered as potential predictors of ESRD treatment choice, i.e., peritoneal dialysis (PD), hemodialysis (HD), or preemptive kidney transplantation in age-adjusted and multivariable-adjusted logistic regression analyses.

RESULTS

Of the 11,317 individuals with incident LN ESRD, 82.0% initiated HD, 12.2% initiated PD, and 2.8% underwent preemptive kidney transplantation. Receiving initial PD was significantly associated with earlier calendar year, female sex, higher albumin and hemoglobin levels, and lower serum creatinine levels. African Americans (versus whites), Medicaid beneficiaries and those with no health insurance (versus private insurance), and those unemployed (versus employed) had significantly reduced PD initiation. Comorbidities including congestive heart failure, peripheral vascular disease, and the inability to ambulate were also associated with decreased PD. Many sociodemographic and clinical factors favoring PD were associated with preemptive kidney transplant (versus dialysis) as well.

CONCLUSION

Few patients with LN ESRD receive initial PD or preemptive kidney transplantation. Race, ethnicity, employment, and medical insurance type are strongly associated with initial kidney replacement therapy choice. Future studies need to investigate the appropriateness of sociodemographic and clinical variation and the comparative effectiveness of kidney replacement therapies for LN ESRD.

Differing early blood pressure and renin-angiotensin system responses to the first dose of angiotensin-converting enzyme inhibitors in congestive heart failure

We previously demonstrated differing blood pressure (BP) responses to the first dose of angiotensin-converting enzyme (ACE) inhibitors in congestive heart failure (CHF). We wished to confirm the disparate responses to the first dose of these agents, study the response to repeated dosing, and explore possible explanations (slow, tight binding, and steric hindrance) for the phenomenon. Forty-eight elderly patients (aged 51-85 years) with stable CHF were studied for 48 hours. Groups (n = 12) received one of the following: (a) perindopril 2 mg orally (p.o.) + placebo intravenously (i.v.) (day 1) and perindopril 2 mg p.o. (day 2); (b) enalapril 2.5 mg p.o. + placebo i.v. (day 1) and enalapril 2.5 mg p.o. (day 2); (c) placebo p.o. + perindopril at 0.167 mg i.v. (day 1) and perindopril 2 mg p.o. (day 2); or (d) placebo p.o. + placebo i.v. (day 1) and placebo p.o. (day 2). Supine BP was measured on day 1. On day 2, BP was recorded by ambulatory BP monitor. Blood samples were taken at baseline and at intervals during the 48-h study period for estimation of neurohumoral parameters. Inhibition of the renin-angiotensin system (RAS) was estimated by plasma ACE inhibition and also by the ratio of angiotensin II (Ang II)/Ang I + Ang II. On day I, enalapril 2.5 mg caused a greater decrease in BP than did placebo response between 6 and 9 h postdose. Perindopril 2 mg produced a profile of BP response similar to that of placebo. Ambulatory BP on day 2 was consistently lower with enalapril as compared with perindopril. Profiles of plasma ACE inhibition were similar with each active therapy. Enalapril therapy produced a greater increase in plasma renin activity (PRA) than did other treatments. There was no temporal dissociation between plasma ACE inhibition and profile of Ang peptides for any treatment. We have confirmed the disparate BP responses to perindopril and enalapril in CHF. We noted no evidence of slow, tight binding or steric hindrance to explain these differences.

Effect of medium-chain triglycerides on calbindin-D9k expression in the intestine

These studies determined the effect of the saturated fat source in infant formula on the expression of calbindin-D9k (CaBP-9k). Piglets were fed from birth to 8 d with milk or formula containing saturated fatty acids as medium-chain triglycerides (MCT), coconut oil, palm oil (Palm 1), or synthesized triglycerides with 16:0 directed to the sn-2 position (Palm 2). Levels of intestinal CaBP-9k mRNA were significantly (P < 0.01) higher in piglets fed formula with MCT than in piglets fed the other formula or milk; and higher in piglets fed the Palm-1 than in piglets fed Palm-2 formula. This is the first evidence that MCT alter piglet intestinal CaBP-9k mRNA.

Steady-state pharmacokinetics of imipenem in febrile neutropenic cancer patients

We ascertained the pharmacokinetics of imipenem in febrile granulocytopenic cancer patients. The values observed were both different from and significantly more variable than those observed in normal volunteers. Free drug concentrations exceeded the MIC for 90% of Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus strains for greater than 6 h. The MIC for 90% of Pseudomonas aeruginosa strains was exceeded for 4 h. Because imipenem induces a 2-h postantibiotic effect in P. aeruginosa, it is promising as single-agent empiric therapy in this setting.