A physical phantom for amine chemical exchange saturation transfer (CEST) MRI.

OBJECTIVE: To develop a robust amine chemical exchange saturation transfer (CEST) physical phantom, validate the temporal stability, and create a supporting software for automatic image processing and quality assurance. MATERIALS AND METHODS: The phantom was designed as an assembled laser-cut acrylic rack and 18 vials of phantom solutions, prepared with different pHs, glycine concentrations, and gadolinium concentrations. We evaluated glycine concentrations using ultraviolet absorbance for 70 days and measured the pH, relaxation rates, and CEST contrast for 94 days after preparation. We used Spearman's correlation to determine if glycine degraded over time. Linear regression and Bland-Altman analysis were performed between baseline and follow-up measurements of pH and MRI properties. RESULTS: No degradation of glycine was observed (p > 0.05). The pH and MRI measurements stayed stable for 3 months and showed high consistency across time points (R2 = 1.00 for pH, R1, R2, and CEST contrast), which was further validated by the Bland-Altman plots. Examples of automatically generated reports are provided. DISCUSSION: We designed a physical phantom for amine CEST-MRI, which is easy to assemble and transfer, holds 18 different solutions, and has excellent short-term chemical and MRI stability. We believe this robust phantom will facilitate the development of novel sequences and cross-scanners validations.

Frailty is common and strongly associated with dyspnoea severity in fibrotic interstitial lung disease.

BACKGROUND AND OBJECTIVE: Frailty is the age-related accumulation of deficits that decrease the ability to respond to biological stress. Patients with fibrotic interstitial lung disease (ILD) may be frail due to consequences of ILD, age, co-morbidities and adverse effects of pharmacotherapies. The objective of this study was to examine the prevalence and predictors of frailty in fibrotic ILD. METHODS: Fibrotic ILD patients were recruited from a specialized clinic. Patients with ILD secondary to a systemic disease were excluded. Frailty was determined using the Frailty Index based on the presence or absence of multiple deficits, including co-morbidities, symptoms and functional limitations. The Frailty Index was based on the proportion of deficits present, with frailty defined as a score >0.21. Cronbach's alpha was used to estimate the internal consistency of the Frailty Index. Dyspnoea was measured using the University of California San Diego Shortness of Breath Questionnaire. Multivariate analysis was used to determine independent predictors of frailty. RESULTS: The definition of frailty was met in 50% of the 129 patients. Cronbach's alpha for the Frailty Index was 0.87. The Frailty Index was associated with forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1 ), diffusion capacity of the lung for carbon monoxide (DLCO ), ILD-gender, age and physiology (GAP) index, composite physiologic index and dyspnoea score. Dyspnoea severity was the strongest unadjusted predictor (r = 0.65, P < 0.001) and only independent predictor of the Frailty Index (0.034 increase in Frailty Index per 10-point increase in dyspnoea score; R2 = 0.37; P < 0.001). CONCLUSION: Frailty is highly prevalent and is strongly and independently associated with dyspnoea severity, demonstrating that dyspnoea is a more important determinant of frailty than pulmonary function.

Gastric emptying and myoelectrical activity testing in children with esophageal atresia: A pilot study.

Objectives: Abnormalities of gastric function in children with esophageal atresia (EA) could potentially contribute to gastrointestinal symptoms and reduced quality of life (QOL). Therefore, we aimed to determine the feasibility and clinical usefulness of gastric function testing in children with EA. Methods: The validated PedsQL Gastrointestinal Symptoms Questionnaire (PedsQL-GI) was completed to assess gastrointestinal symptoms and symptom-related QOL. Gastric emptying and gastric myoelectrical activity were studied using 13C-gastric emptying octanoic acid breath test (13C-GEBT) and surface electrogastrography (EGG). Correlations between 13C-GEBT and EGG parameters and PedsQL-GI scores were investigated. Results: Fifteen patients (four males) were included (median age: 6 [3.0-8.5] years). Mean PedsQL-GI scores as reported by the children were comparable to the healthy population. However, parents reported a diminished QOL. Gastric function tests (gastric emptying and/or surface EGG) showed abnormalities in 12 patients (80%). Patients with abnormal slow waves showed abnormal gastric emptying coefficient more often. There was no significant association between 13C-GEBT nor EGG results and PedsQL-GI scores. Conclusions: 13C-GEBT and EGG can be used to evaluate gastric function in patients with EA. Abnormal gastric function tests were present in 80% of our cohort. However, abnormal gastric function did not significantly correlate with reported gastrointestinal symptom-related QOL.

Sleep disruptions and nocturnal nursing interactions in the intensive care unit.

BACKGROUND: Sleep deprivation, common in intensive care unit (ICU) patients, may be associated with increased morbidity and/or mortality. We previously demonstrated that significant numbers of nocturnal nursing interactions (NNIs) occur during the routine care of surgical ICU patients. For this study, we assessed the quantity and type of NNIs in different ICU types: medical, surgical, cardiothoracic, pediatric, and neonatal. We hypothesized that the number and type of NNIs vary among different ICU types. MATERIAL AND METHODS: We performed a prospective observational cohort study at our academic medical center examining potential sleep disruption in ICU patients secondary to NNIs from the hours 2200-0600 nightly. From May through November 2011, bedside nursing staff in five different ICUs collected data on NNIs, including the frequency and nature of each event (patient care activity, nursing intervention, nursing assessment, or patient-initiated contact) as well as the length of time of each event and whether the bedside care provider thought that the event could have been safely omitted without negatively affecting patient care. Additional data collected included patient demographics, the need for mechanical ventilation, and sedative/narcotic use. RESULTS: Two hundred ICU patients were enrolled over 51 separate nocturnal time periods (3.9 patients/nocturnal time period). Of those 200 patients, 53 (26.5%) were mechanically ventilated; 12.5% underwent sedative infusion; and 23.0% underwent narcotic infusion. There were a total of 1831 NNIs; most (67%) were due to nursing assessment or patient care activity. The surgical ICU had the most frequent NNIs (11.8 ± 9.0), although they were the shortest (6.66 ± 6.06 min), as well as the highest proportion of NNIs that could have been safely omitted (20.9%). Nursing staff estimated that, of all NNIs in all ICU types, 13.9% could have been safely omitted. CONCLUSIONS: NNIs occur frequently and vary across different ICU types. Many NNIs are due to nursing assessment and patient care activities, much of which could be safely omitted or clustered. A protocol for nocturnal sleep promotion is warranted in order to standardize ICU NNIs and minimize nighttime sleep disruptions.

Importance of each residue within secretin for receptor binding and biological activity.

Secretin is a linear 27-residue peptide hormone that stimulates pancreatic and biliary ductular bicarbonate and water secretion by acting at its family B G protein-coupled receptor. While, like other family members, the carboxyl-terminal region of secretin is most important for high affinity binding and its amino-terminal region is most important for receptor selectivity and receptor activation, determinants for these activities are distributed throughout the entire length of this peptide. In this work, we have systematically investigated changing each residue within secretin to alanine and evaluating the impact on receptor binding and biological activity. The residues most critical for receptor binding were His1, Asp3, Gly4, Phe6, Thr7, Ser8, Leu10, Asp15, Leu19, and Leu23. The residues most critical for biological activity included His1, Gly4, Thr7, Ser8, Glu9, Leu10, Leu19, Leu22, and Leu23, with Asp3, Phe6, Ser11, Leu13, Asp15, Leu26, and Val27 also contributing. While the importance of residues in positions analogous to His1, Asp3, Phe6, Thr7, and Leu23 is conserved for several closely related members of this family, Leu19 is uniquely important for secretin. We, therefore, have further studied this residue by molecular modeling and molecular dynamics simulations. Indeed, the molecular dynamics simulations showed that mutation of Leu19 to alanine was destabilizing, with this effect greater than that observed for the analogous position in the other close family members. This could reflect reduced contact with the receptor or an increase in the solvent-accessible surface area of the hydrophobic residues in the carboxyl terminus of secretin as bound to its receptor.

Clinical Evaluation of the Torq Zero Delay Centrifuge System for Decentralized Blood Collection and Stabilization.

Blood sample collection and rapid separation-critical preanalytical steps in clinical chemistry-can be challenging in decentralized collection settings. To address this gap, the Torq™ zero delay centrifuge system includes a lightweight, hand-portable centrifuge (ZDrive™) and a disc-shaped blood collection device (ZDisc™) enabling immediate sample centrifugation at the point of collection. Here, we report results from clinical validation studies comparing performance of the Torq System with a conventional plasma separation tube (PST). Blood specimens from 134 subjects were collected and processed across three independent sites to compare ZDisc and PST performance in the assessment of 14 analytes (K, Na, Cl, Ca, BUN, creatinine, AST, ALT, ALP, total bilirubin, albumin, total protein, cholesterol, and triglycerides). A 31-subject precision study was performed to evaluate reproducibility of plasma test results from ZDiscs, and plasma quality was assessed by measuring hemolysis and blood cells from 10 subject specimens. The ZDisc successfully collected and processed samples from 134 subjects. ZDisc results agreed with reference PSTs for all 14 analytes with mean % biases well below clinically significant levels. Results were reproducible across different operators and ZDisc production lots, and plasma blood cell counts and hemolysis levels fell well below clinical acceptance thresholds. ZDiscs produce plasma samples equivalent to reference PSTs. Results support the suitability of the Torq System for remotely collecting and processing blood samples in decentralized settings.