The Solution Structure, Binding Properties, and Dynamics of the Bacterial Siderophore-binding Protein FepB

The periplasmic binding protein (PBP) FepB plays a key role in transporting the catecholate siderophore ferric enterobactin from the outer to the inner membrane in Gram-negative bacteria. The solution structures of the 34-kDa apo- and holo-FepB from Escherichia coli, solved by NMR, represent the first solution structures determined for the type III class of PBPs. Unlike type I and II PBPs, which undergo large "Venus flytrap" conformational changes upon ligand binding, both forms of FepB maintain similar overall folds; however, binding of the ligand is accompanied by significant loop movements. Reverse methyl cross-saturation experiments corroborated chemical shift perturbation results and uniquely defined the binding pocket for gallium enterobactin (GaEnt). NMR relaxation experiments indicated that a flexible loop (residues 225-250) adopted a more rigid and extended conformation upon ligand binding, which positioned residues for optimal interactions with the ligand and the cytoplasmic membrane ABC transporter (FepCD), respectively. In conclusion, this work highlights the pivotal role that structural dynamics plays in ligand binding and transporter interactions in type III PBPs

Perioperative Factors Associated With Postoperative Delirium in Patients Undergoing Noncardiac Surgery:An Individual Patient Data Meta-Analysis

IMPORTANCE: Postoperative delirium (POD) is a common and serious complication after surgery. Various predisposing factors are associated with POD, but their magnitude and importance using an individual patient data (IPD) meta-analysis have not been assessed.OBJECTIVE: To identify perioperative factors associated with POD and assess their relative prognostic value among adults undergoing noncardiac surgery.DATA SOURCES: MEDLINE, EMBASE, and CINAHL from inception to May 2020.STUDY SELECTION: Studies were included that (1) enrolled adult patients undergoing noncardiac surgery, (2) assessed perioperative risk factors for POD, and (3) measured the incidence of delirium (measured using a validated approach). Data were analyzed in 2020.DATA EXTRACTION AND SYNTHESIS: Individual patient data were pooled from 21 studies and 1-stage meta-analysis was performed using multilevel mixed-effects logistic regression after a multivariable imputation via chained equations model to impute missing data.MAIN OUTCOMES AND MEASURES: The end point of interest was POD diagnosed up to 10 days after a procedure. A wide range of perioperative risk factors was considered as potentially associated with POD.RESULTS: A total of 192 studies met the eligibility criteria, and IPD were acquired from 21 studies that enrolled 8382 patients. Almost 1 in 5 patients developed POD (18%), and an increased risk of POD was associated with American Society of Anesthesiologists (ASA) status 4 (odds ratio [OR], 2.43; 95% CI, 1.42-4.14), older age (OR for 65-85 years, 2.67; 95% CI, 2.16-3.29; OR for &gt;85 years, 6.24; 95% CI, 4.65-8.37), low body mass index (OR for body mass index &lt;18.5, 2.25; 95% CI, 1.64-3.09), history of delirium (OR, 3.9; 95% CI, 2.69-5.66), preoperative cognitive impairment (OR, 3.99; 95% CI, 2.94-5.43), and preoperative C-reactive protein levels (OR for 5-10 mg/dL, 2.35; 95% CI, 1.59-3.50; OR for &gt;10 mg/dL, 3.56; 95% CI, 2.46-5.17). Completing a college degree or higher was associated with a decreased likelihood of developing POD (OR 0.45; 95% CI, 0.28-0.72).CONCLUSIONS AND RELEVANCE: In this systematic review and meta-analysis of individual patient data, several important factors associated with POD were found that may help identify patients at high risk and may have utility in clinical practice to inform patients and caregivers about the expected risk of developing delirium after surgery. Future studies should explore strategies to reduce delirium after surgery.</p

Comprehensive and Cost-Effective NMR Spectroscopy of Methyl Groups in Large Proteins

An NMR approach is described which yields the methyl resonance assignments of alanine, threonine, valine, leucine, and isoleucine residues in proteins with high sensitivity and excellent resolution. The method relies on protein samples produced by bacterial expression using [(1)H, (13)C]-D-glucose and similar to 100% D(2)O, which is cost-effective and ensures the isotopic enrichment of all possible methyl groups. Magnetization transfer throughout the methyl-containing side chains is possible with this labeling scheme due to the high level of deuteration along the amino acid side chain, coupled with the selection of the favorable CHD(2) methyl isotopomer for detection. In an application to the 34 kDa periplasmic binding protein FepB 164 out of 195 methyl groups (85%) were assigned sequence-specifically and stereospecifically. This percentage increases to 91% when taking into account that not all backbone assignments are available for this system. The remaining unassigned methyl groups belong to six leucine residues, caused by low cross-peak intensities, and four alanine residues due to degeneracy of the (13)C(alpha)/(13)C(beta) frequencies. Our results demonstrate that NMR spectroscopic investigations of protein structure, dynamics, and interactions can be extended to include all methyl-containing amino acids also for larger proteins

Delirium severity: Systematic review and meta-analysis

Protocol: Delirium severity and patient health outcomes: A systematic review and meta-analysi

The CAM-ICU-7 and ICDSC as measures of delirium severity in critically ill adult patients.

BackgroundIn clinical practice, a dichotomous approach to delirium identification may no longer be relevant when existing delirium screening tools measure a range of scores. The objective of this study was to compare the Confusion Assessment Method for the Intensive Care Unit 7-item (CAM-ICU-7) and the Intensive Care Delirium Screening Checklist (ICDSC) as measures of the spectrum of delirium severity in critically ill adult patients.MethodsIn this cross-sectional study, 218 patients underwent 641 paired assessments by bedside nurses (ICDSC, as per usual care) and trained research assistants (CAM-ICU-7). Correlation between the CAM-ICU-7 and ICDSC scores was evaluated. Logistic regression was used to explore associations between CAM-ICU-7 or ICDSC score and length of ICU stay and mechanical ventilation (receipt, ≥96 hours).ResultsDelirium prevalence evaluated by the CAM-ICU-7 and ICDSC were 46.3% (95% CI:39.7-53.0) and 34.4% (95% CI:28.3-41.0). Prevalence of less than clinical threshold symptoms of delirium evaluated by the CAM-ICU-7 (score: 1-2) and ICDSC (score: 1-3) were 30.3% (95%CI:24.5-36.7) and 50.9% (95%CI:44.3-57.6). The CAM-ICU-7 and ICDSC had significant positive correlation (0.58, pConclusionsThe CAM-ICU-7 and ICDSC are measures of the spectrum of delirium severity that are closely correlated. Less than clinical threshold symptoms of delirium measure by the ICDSC is a better predictor of outcomes, when compared with the CAM-ICU-7

Psychometric evaluation of the family caregiver ICU delirium knowledge questionnaire

Abstract Background Delirium is a common condition in critically ill patients, affecting nearly half of all patients admitted to an intensive care unit (ICU). Family caregivers of critically ill patients can be partners in the early recognition, prevention and management of delirium provided they are aware of the signs/symptoms and appropriate non-pharmacological strategies that might be taken. Valid, reliable instruments that assess family caregiver knowledge are essential so that nurses can prepare family caregivers to be effective partners. The purpose of the current study was to (a) adapt an existing caregiver delirium knowledge questionnaire (CDKQ) for use by nurses to measure a family caregiver’s delirium knowledge in the ICU; and (b) examine the psychometric properties and structure of the adapted Caregiver ICU Delirium Knowledge Questionnaire (CIDKQ). Methods In this cross-sectional study, a multidisciplinary team developed the 21-item CIDKQ (possible score range: 0–21) and administered it to 158 family caregivers of critically ill patients. Descriptive statistics were examined for all variables. The CIDKQ was analyzed for face validity, content validity, reliability and internal consistency. Results The mean CIDKQ score was 14.1 (SD: 3.5, range = 2 to 21). Path analysis revealed that a family caregiver’s delirium knowledge in the actions and symptoms dimensions had a direct effect on knowledge of delirium risk factors. The CIDKQ was found to have face validity and reliability (Cronbach’s α = 0.79). Conclusions The findings indicated good validity and reliability of the CIDKQ as a measure of ICU delirium knowledge in family caregivers of critically ill patients

Effectiveness of an intensive care unit family education intervention on delirium knowledge: a pre-test post-test quasi-experimental study

PurposeTo create, validate, and refine an intensive care unit (ICU) delirium education intervention to prepare family members to partner with the ICU care team to detect delirium symptoms and prevent and manage delirium using nonpharmacological strategies.MethodsIn this pre-test post-test quasi-experimental study, consecutive eligible family members of critically ill patients admitted to an ICU completed an ICU Family Education Delirium intervention in two parts: 1) six-minute video on ICU delirium (risk factors, prevention/management, symptoms, communication with the ICU care team), and 2) two case vignettes to practice detecting delirium using family-administered delirium detection questionnaires (Family Confusion Assessment Method [FAM-CAM] and Sour Seven). Family members' delirium knowledge was measured before, immediately after, and two weeks following the intervention using the Caregiver ICU Delirium Knowledge Questionnaire (CIDKQ).ResultsOf 99 family members recruited over eight months, 81 (82%) completed the intervention and 63 (63/81, 78%) completed all follow-up questionnaires. Family members' delirium knowledge improved significantly following the intervention (pre-CIDKQ, 14; 95% confidence interval [CI], 13 to 15; post-CIDKQ, 17; 95% CI, 16 to 17; P &lt; 0.001) and was retained two weeks after the intervention (CIDKQ 16; 95% CI, 16 to 17; P &lt; 0.001). This included increased knowledge regarding delirium risk factors (e.g., medication, mechanical ventilation), prevention/management (e.g., orientation, day/night routine), and symptoms of delirium. More family members correctly detected delirium symptoms in case vignettes using the Sour Seven (92%) compared with the FAM-CAM (78%).ConclusionsA video-based ICU delirium education intervention is effective in educating family members about prevention, detection, and management of delirium

Associations between caregiver-detected delirium and symptoms of depression and anxiety in family caregivers of critically ill patients: a cross-sectional study

BackgroundWitnessing delirium can be distressing for family caregivers (i.e., relatives or friends) of critically ill patients. This study aimed to evaluate associations between caregiver-detected delirium in critically ill patients and depression and anxiety symptoms in their family caregivers.MethodsConsecutive adult patient-caregiver dyads were enrolled from a 28-bed medical-surgical intensive care unit. Patient delirium was screened for daily by family caregivers using the Sour Seven instrument. Family caregivers completed the Patient Health Questionnaire-9 (PHQ-9) and General Anxiety Disorder-7 (GAD-7) instruments daily to assess their own depression and anxiety symptoms. Response feature analysis was used to handle repeated measures. Descriptive statistics and regression analyses were completed.ResultsOne hundred forty-seven patient-caregiver dyads were enrolled. Clinically significant symptoms of depression and anxiety occurred in 27% and 35% of family caregivers, respectively. Caregiver-detected delirium occurred in 65% of patients, and was not associated with clinically significant caregiver depression (Odds Ratio [OR] 1.4, 95% Confidence Interval [95%CI] 0.6-3.1) or anxiety (OR 1.2, 95%CI 0.6-2.6) symptoms. When stratified by Sour Seven scores, scores 1-3 and 4-9 were associated with increased symptoms of anxiety (OR 3.1, 95%CI 1.3-7.0) and depression (OR 2.6, 95%CI 1.1-6.1) in family caregivers. Caregiver-detected delirium score was associated with severity of family caregiver anxiety symptoms (coefficient 0.2, 95%CI 0.1-0.4), but not depression symptoms (coefficient 0.2, 95%CI -0.0-0.3).ConclusionsCaregiver-detected patient delirium was associated with increased depression and anxiety symptoms in family caregivers of critically ill patients. Further randomized research is required to confirm these associations

Associations between caregiver-detected delirium and symptoms of depression and anxiety in family caregivers of critically ill patients: a cross-sectional study

Abstract Background Witnessing delirium can be distressing for family caregivers (i.e., relatives or friends) of critically ill patients. This study aimed to evaluate associations between caregiver-detected delirium in critically ill patients and depression and anxiety symptoms in their family caregivers. Methods Consecutive adult patient-caregiver dyads were enrolled from a 28-bed medical-surgical intensive care unit. Patient delirium was screened for daily by family caregivers using the Sour Seven instrument. Family caregivers completed the Patient Health Questionnaire-9 (PHQ-9) and General Anxiety Disorder-7 (GAD-7) instruments daily to assess their own depression and anxiety symptoms. Response feature analysis was used to handle repeated measures. Descriptive statistics and regression analyses were completed. Results One hundred forty-seven patient-caregiver dyads were enrolled. Clinically significant symptoms of depression and anxiety occurred in 27% and 35% of family caregivers, respectively. Caregiver-detected delirium occurred in 65% of patients, and was not associated with clinically significant caregiver depression (Odds Ratio [OR] 1.4, 95% Confidence Interval [95%CI] 0.6–3.1) or anxiety (OR 1.2, 95%CI 0.6–2.6) symptoms. When stratified by Sour Seven scores, scores 1–3 and 4–9 were associated with increased symptoms of anxiety (OR 3.1, 95%CI 1.3–7.0) and depression (OR 2.6, 95%CI 1.1–6.1) in family caregivers. Caregiver-detected delirium score was associated with severity of family caregiver anxiety symptoms (coefficient 0.2, 95%CI 0.1–0.4), but not depression symptoms (coefficient 0.2, 95%CI -0.0–0.3). Conclusions Caregiver-detected patient delirium was associated with increased depression and anxiety symptoms in family caregivers of critically ill patients. Further randomized research is required to confirm these associations