Dynamic associations between glucose and ecological momentary cognition in Type 1 Diabetes.

Type 1 diabetes (T1D) is a chronic condition characterized by glucose fluctuations. Laboratory studies suggest that cognition is reduced when glucose is very low (hypoglycemia) and very high (hyperglycemia). Until recently, technological limitations prevented researchers from understanding how naturally-occurring glucose fluctuations impact cognitive fluctuations. This study leveraged advances in continuous glucose monitoring (CGM) and cognitive ecological momentary assessment (EMA) to characterize dynamic, within-person associations between glucose and cognition in naturalistic environments. Using CGM and EMA, we obtained intensive longitudinal measurements of glucose and cognition (processing speed, sustained attention) in 200 adults with T1D. First, we used hierarchical Bayesian modeling to estimate dynamic, within-person associations between glucose and cognition. Consistent with laboratory studies, we hypothesized that cognitive performance would be reduced at low and high glucose, reflecting cognitive vulnerability to glucose fluctuations. Second, we used data-driven lasso regression to identify clinical characteristics that predicted individual differences in cognitive vulnerability to glucose fluctuations. Large glucose fluctuations were associated with slower and less accurate processing speed, although slight glucose elevations (relative to person-level means) were associated with faster processing speed. Glucose fluctuations were not related to sustained attention. Seven clinical characteristics predicted individual differences in cognitive vulnerability to glucose fluctuations: age, time in hypoglycemia, lifetime severe hypoglycemic events, microvascular complications, glucose variability, fatigue, and neck circumference. Results establish the impact of glucose on processing speed in naturalistic environments, suggest that minimizing glucose fluctuations is important for optimizing processing speed, and identify several clinical characteristics that may exacerbate cognitive vulnerability to glucose fluctuations.

The effect of postoperative intravenous iron in anaemic, older cardiac surgery patients on disability-free survival (AGE ANEMIA study): study protocol for a multi-centre, double-blind, randomized, placebo-controlled trial.

BACKGROUND: Postoperative anaemia is common in older cardiac surgery patients and often caused by iron deficiency. Anaemia may negatively affect recovery after cardiac surgery. This study aims to determine the efficacy of treatment of postoperative iron deficiency anaemia (IDA) with intravenous iron (IVI) on disability 90 days after cardiac surgery in older patients. METHODS: This is a randomized placebo-controlled double-blind multi-centre trial. In total, 310 patients aged ≥ 70 years with moderate IDA on postoperative day 1 (haemoglobin 85-110 g/L and ferritin concentration < 100 µg/L or iron saturation < 20%) after uncomplicated elective cardiac surgery (aortic valve repair or coronary artery bypass graft surgery) will be included. Patients will be randomly allocated to receive either IVI (ferric derisomaltose) or placebo (sodium chloride 0.9%) on postoperative day 1 in a 1:1 ratio, stratified by centre and type of cardiac surgery. The primary outcome is disability measured by the 12-item World Health Organization Disability Assessment score 2.0 after 90 days. Secondary outcome measures are the number of postoperative red blood cell (RBC) transfusions, change in reticulocyte haemoglobin content (pg) from randomization to hospital discharge, Hb levels at discharge, hospital complications, dyspnoea (assessed with the Rose Dyspnoea Scale) and health-related quality of life (HRQL) (assessed with The Older Persons and Informal Caregivers-Short Form (TOPICS-SF) questionnaire) after 90 days and days alive and out of hospital after 90 days. Lastly, the functional outcomes (e.g. steep ramp or 6-min walk test) and Hb level after 90 days will be assessed as an exploratory endpoint. DISCUSSION: The results of this study will demonstrate whether early treatment of postoperative IDA with IVI improves disability at 90 days in older cardiac surgery patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT04913649. Registered on June 4, 2021.

[Predicting postoperative mortality]. / Postoperatieve sterfte voorspellen.

This article briefly discusses the reliability of predictive models for postoperative mortality. In current practice, prediction models for postoperative mortality often have limited clinical value, because the mortality risk is generally low. Moreover, in preoperative screening there is not so much a need for predictions about the average effectiveness of an intervention or treatment for an average patient, but rather for estimating the patient's individual risk. Postoperative functional decline and loss of quality of life are often underexposed in preoperative decision making.

[Elderly patients with an abdominal aortic aneurysm; preoperative frailty-screening and a multidisciplinary approach]. / Ouderen met een aneurysma van de abdominale aorta.

Aneurysm of the abdominal aorta is common and can be treated with endovascular repair, open surgical repair or conservative treatment. Risk-stratification and treatment decision-making can be complex in frail patients and depends largely on anatomy, life-expectancy and functional capacity. Currently, risk-stratification in the Netherlands is primarily based on comorbidities and age. Insight in a patient's resilience could provide important additional information. For this reason, St. Antonius hospital has implemented an Anaesthesia Geriatric Evaluation (AGE) to screen for frailty in high risk vascular surgery patients. Results of frailty-screening are discussed in a multi-disciplinary team (MDT) to assess perioperative risk and compose a personal treatment plan. This paper presents a case-series of three patients to illustrate the additional value of MDT care and frailty-screening in a high-risk vascular surgery population.

New insights into the cognitive effects of sleep deprivation by decomposition of a cognitive throughput task.

STUDY OBJECTIVES: A cognitive throughput task known as the Digit Symbol Substitution Test (DSST) (or Symbol Digit Modalities Test) has been used as an assay of general cognitive slowing during sleep deprivation. Here, the effects of total sleep deprivation (TSD) on specific cognitive processes involved in DSST performance, including visual search, spatial memory, paired-associate learning, and motor response, were investigated through targeted task manipulations. METHODS: A total of 12 DSST variants, designed to manipulate the use of specific cognitive processes, were implemented in two laboratory-based TSD studies with N = 59 and N = 26 subjects, respectively. In each study, the Psychomotor Vigilance Test (PVT) was administered alongside the DSST variants. RESULTS: TSD reduced cognitive throughput on all DSST variants, with response time distributions exhibiting rightward skewing. All DSST variants showed practice effects, which were however minimized by inclusion of a pause between trials. Importantly, TSD-induced impairment on the DSST variants was not uniform, with a principal component analysis revealing three factors. Diffusion model decomposition of cognitive processes revealed that inter-individual differences during TSD on a two-alternative forced choice DSST variant were different from those on the PVT. CONCLUSIONS: While reduced cognitive throughput has been interpreted to reflect general cognitive slowing, such TSD-induced impairment appears to reflect cognitive instability, like on the PVT, rather than general slowing. Further, comparisons between task variants revealed not one, but three distinct underlying processes impacted by sleep deprivation. Moreover, the practice effect on the task was found to be independent of the TSD effect and minimized by a task pacing manipulation.

Cognitive flexibility: A distinct element of performance impairment due to sleep deprivation.

In around-the-clock operations, reduced alertness due to circadian misalignment and sleep loss causes performance impairment, which can lead to catastrophic errors and accidents. There is mounting evidence that performance on different tasks is differentially affected, but the general principles underlying this differentiation are not well understood. One factor that may be particularly relevant is the degree to which tasks require executive control, that is, control over the initiation, monitoring, and termination of actions in order to achieve goals. A key aspect of this is cognitive flexibility, i.e., the deployment of cognitive control resources to adapt to changes in events. Loss of cognitive flexibility due to sleep deprivation has been attributed to "feedback blunting," meaning that feedback on behavioral outcomes has reduced salience - and that feedback is therefore less effective at driving behavior modification under changing circumstances. The cognitive mechanisms underlying feedback blunting are as yet unknown. Here we present data from an experiment that investigated the effects of sleep deprivation on performance after an unexpected reversal of stimulus-response mappings, requiring cognitive flexibility to maintain good performance. Nineteen healthy young adults completed a 4-day in-laboratory study. Subjects were randomized to either a total sleep deprivation condition (n = 11) or a control condition (n = 8). Athree-phase reversal learning decision task was administered at baseline, and again after 30.5 h of sleep deprivation, or matching well-rested control. The task was based on a go/no go task paradigm, in which stimuli were assigned to either a go (response) set or a no go (no response) set. Each phase of the task included four stimuli (two in the go set and two in the no go set). After each stimulus presentation, subjects could make a response within 750 ms or withhold their response. They were then shown feedback on the accuracy of their response. In phase 1 of the task, subjects were explicitly told which stimuli were assigned to the go and no go sets. In phases 2 and 3, new stimuli were used that were different from those used in phase 1. Subjects were not explicitly told the go/no go mappings and were instead required to use accuracy feedback to learn which stimuli were in the go and nogo sets. Phase 3 continued directly from phase 2 and retained the same stimuli as in phase 2, but there was an unannounced reversal of the stimulus-response mappings. Task results confirmed that sleep deprivation resulted in loss of cognitive flexibility through feedback blunting, and that this effect was not produced solely by (1) general performance impairment because of overwhelming sleep drive; (2) reduced working memory resources available to perform the task; (3) incomplete learning of stimulus-response mappings before the unannounced reversal; or (4) interference with stimulus identification through lapses in vigilant attention. Overall, the results suggest that sleep deprivation causes a fundamental problem with dynamic attentional control. This element of performance impairment due to sleep deprivation appears to be distinct from vigilant attention deficits, and represents a particularly significant challenge for fatigue risk management.

Semiphysiologically based pharmacokinetic model for midazolam and CYP3A mediated metabolite 1-OH-midazolam in morbidly obese and weight loss surgery patients.

This study aimed to describe the pharmacokinetics of midazolam and its cytochrome P450 3A (CYP3A) mediated metabolite 1-OH-midazolam in morbidly obese patients receiving oral and i.v. midazolam before (n = 20) and one year after weight loss surgery (n = 18), thereby providing insight into the influence of weight loss surgery on CYP3A activity in the gut wall and liver. In a semiphysiologically based pharmacokinetic (semi-PBPK) model in which different blood flow scenarios were evaluated, intrinsic hepatic clearance of midazolam (CLint,H) was 2 (95% CI 1.40-1.64) times higher compared to morbidly obese patients before surgery (P < 0.01). Midazolam gut wall clearance (CLint,G) was slightly lower in patients after surgery (P > 0.05), with low values for both groups. The results of the semi-PBPK model suggest that, in patients after weight loss surgery, CYP3A hepatic metabolizing capacity seems to recover compared to morbidly obese patients, whereas CYP3A mediated CLint,G was low for both populations and showed large interindividual variability.

Assessment of circadian function in fibroblasts of patients with bipolar disorder.

Previous studies have implicated the circadian system in the pathophysiology of bipolar disorder, but conclusive evidence for altered circadian clocks is lacking. Cultured fibroblasts harbor circadian clocks representative of those in the master clock resident in the suprachiasmatic nuclei, providing a new avenue to investigate the core clock machinery in patients with bipolar illness. We examined the rhythmic expression patterns of core clock genes (BMAL1, PER1, PER2, REV-ERBalpha, DEC2, DBP) in fibroblasts from 12 bipolar patients and 12 healthy controls. Although we did not detect differences in the circadian period between bipolar patients and controls, the amplitude of rhythmic expression for BMAL1, REV-ERBalpha and DBP, as well as the overall mRNA expression level for DEC2 and DBP was reduced in fibroblasts from bipolar patients. Bonferroni's correction for multiple comparisons still resulted in significantly reduced DBP expression level, and trends toward reduced overall expression level of DEC2 and circadian amplitude of BMAL1, in fibroblasts from bipolar patients. We next examined an expanded cohort of 18 bipolar patients and 35 healthy controls for mRNA expression levels of four kinases (CKIdelta, CKIepsilon, GSK3alpha and GSK3beta) and the protein and phosphorylation levels of two of them (GSK3alpha and GSK3beta). We did not detect differences in steady-state mRNA levels or protein levels of these kinases between bipolar patients and controls, but the level of GSK3beta phosphorylation was significantly reduced in bipolar patients within an Old Order Amish bipolar kindred. Our results suggest that the reduced amplitudes and overall expression levels of circadian genes, and the decreased phosphorylation level of GSK3beta may lead to dysregulation of downstream genes, which could explain some pathological features of bipolar disorder.

Pneumoproteins as a lung-specific biomarker of alveolar permeability in conventional on-pump coronary artery bypass graft surgery vs mini-extracorporeal circuit: a pilot study.

BACKGROUND: Despite improvements of the heart-lung machine (HLM), oxidative stress and subsequent damage to the alveolar capillary membrane still occur after conventional on-pump coronary artery bypass graft (CCABG) surgery. In an attempt to further improve the conventional HLM, a mini-extracorporeal circuit (MECC) was introduced. This new concept is based on minimal volume shifts. The extent of alveolar injury that is associated with this new technique is unknown. The lung-specific biomarkers Clara-cell 16 (CC16) and KL-6 are applied in this study to quantify alveolar dysfunction in both techniques. METHODS: In a prospective observational setting, the concentrations of CC16 and KL-6 were measured during and after 10 consecutive CCABG operations and 10 consecutive coronary artery bypass graft (CABG) operations using MECC (MCABGs). These pneumoproteins were measured after the induction of anesthesia, before clamping of the ascending aorta, after unclamping of the aorta, on arrival to the ICU, and on the following days until discharge. Quantification of the differences of KL-6 and CC16 leakage through the alveolar membranes between the two techniques was realized by calculation of the Student t test. Perioperative and postoperative shunt fractions and clinical observations were monitored simultaneously. The potential value of pneumoproteins as biomarkers for quantification of alveolar permeability during CABG surgery was tested. RESULTS: Significantly reduced concentrations of CC16 were found early after MCABG as compared to CCABG surgery (p = 0.033). KL-6 showed no consistent pattern during both treatment modalities. Early after CCABG surgery, shunt fractions tended to show reduced oxygen transport over the alveolar membrane as compared to MCABG surgery. CONCLUSION: CC16 appears to be a useful biomarker for alveolar permeability during CABG surgery. Injury of the alveolar capillary membrane appears significantly reduced during MCABG surgery. Consistently early postoperative alveolar shunt fractions showed an increased value in CCABG compared to MCABG surgery in the early postoperative phase. Further randomized studies need to confirm the value of CC16 as marker in monitoring alveolar capillary damage during coronary bypass grafting.

Sleep loss reduces diurnal rhythm amplitude of leptin in healthy men.

The aim of the current study was to investigate the effects of sleep loss on the diurnal rhythm of circulating leptin levels. An indwelling forearm catheter was used to sample blood at 90-min intervals for a total of 120 h, which included 88 h of sustained sleeplessness, in 10 healthy men. The diurnal amplitude of leptin was reduced during total sleep deprivation and returned toward normal during the period of recovery sleep. This finding provides evidence that sleep influences the nocturnal leptin profile, and may have implications for the understanding of the role of sleep in metabolic regulation and the aetiologies of obesity and the night eating syndrome.