Probing phospholipid microbubbles by atomic force microscopy to quantify bubble mechanics and nanostructural shell properties

Microbubbles (MBs), which are used as ultrasonic contrast agents, have distinct acoustic signatures which enable them to significantly enhance visualisation of the vasculature. Research is progressing to develop MBs which act as drug/gene delivery vehicles for site-specific therapeutics. In order to manufacture effective theranostic vehicles, it is imperative to understand the mechanical and nanostructural properties of these agents; this will enrich the understanding of how the structural, biophysical and chemical properties of these bubbles impact their functionality. We produced microfluidic phospholipid-based MBs due to their favourable properties, such as biocompatibility and echogenicity, as well as the ability to modify the shell for targeting applications. We have drawn upon atomic force microscopy to conduct force spectroscopy and tapping-mode imaging investigations. We have, for the first time to our knowledge, been able to accurately quantify the thickness and lipid configuration of phospholipid-shelled MBs - showing a trilayer as opposed to the conventional monolayer structure. Furthermore, we have measured MB stiffness and employed different mechanical theories to quantify the Young’s modulus. We show that the Reissner theory is inappropriate for mechanical characterisation of phospholipid MBs, however, the Hertz model does offer biologically relevant comparisons. Analysis using the Alexander-de Gennes polymer brush theory has allowed us to provide new information regarding how the thickness of the polyethylene glycol brushes, end-grafted to our phospholipid microbubbles, changes with diameter

Quantitative EEG as a Prognostic Tool in Suspected Anti-N-Methyl-D-Aspartate Receptor Antibody Encephalitis

PURPOSE: Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a form of autoimmune encephalitis associated with EEG abnormalities. In view of the potentially severe outcomes, there is a need to develop prognostic tools to inform clinical management. The authors explored whether quantitative EEG was able to predict outcomes in patients with suspected anti-NMDAR encephalitis. METHODS: A retrospective, observational study was conducted of patients admitted to a tertiary clinical neuroscience center with suspected anti-NMDAR encephalitis. Peak power and peak frequency within delta (<4 Hz), theta (4-8 Hz), alpha (8 - 13 Hz), and beta (13-30 Hz) frequency bands were calculated for the first clinical EEG recording. Outcome was based on the modified Rankin Scale (mRS) score at 1 year after hospital discharge. Binomial logistic regression using backward elimination was performed with peak frequency and power, anti-NMDAR Encephalitis One-Year Functional Status score, age, and interval from symptom onset to EEG entered as predictors. RESULTS: Twenty patients were included (mean age 48.6 years, 70% female), of which 7 (35%) had a poor clinical outcome (mRS 2-6) at 1 year. There was no association between reported EEG abnormalities and outcome. The final logistic regression model was significant (χ2(1) = 6.35, P < 0.012) with peak frequency in the delta range (<4 Hz) the only retained predictor. The model explained 38% of the variance (Nagelkerke R2) and correctly classified 85% of cases. Higher peak frequency in the delta range was significantly associated (P = 0.04) with an increased likelihood of poor outcome. CONCLUSIONS: In this exploratory study, it was found that quantitative EEG on routinely collected EEG recordings in patients with suspected anti-NMDAR encephalitis was feasible. A higher peak frequency within the delta range was associated with poorer clinical outcome and may indicate anti-NMDAR-mediated synaptic dysfunction. Quantitative EEG may have clinical utility in predicting outcomes in patients with suspected NMDAR antibody encephalitis, thereby serving as a useful adjunct to qualitative EEG assessment; however, given the small sample size, replication in a larger scale is indicated

Reduction of circulating cholesterol and apolipoprotein levels during sepsis

Sepsis with multiple organ failure is frequently associated with a substantial decrease of cholesterol levels. This decrease of cholesterol is strongly associated with mortality suggesting a direct relation between inflammatory conditions and altered cholesterol homeostasis. The host response during sepsis is mediated by cytokines and growth factors, which are capable of influencing lipid metabolism. Conversely lipoproteins are also capable of modulating cytokine production during the inflammatory response. Therefore the decrease in circulating cholesterol levels seems to play a crucial role in the pathophysiology of sepsis. In this review the interaction between cytokines and lipid metabolism and its clinical consequences will be discussed

Functional polymorphisms in the P2X7 receptor gene are associated with stress fracture injury

Context: Military recruits and elite athletes are susceptible to stress fracture injuries. Genetic predisposition has been postulated to have a role in their development. The P2X7 receptor (P2X7R) gene, a key regulator of bone remodelling, is a genetic candidate that may contribute to stress fracture predisposition. Objective: To evaluate the putative contribution of P2X7R to stress fracture injury in two separate cohorts, military personnel and elite athletes. Methods: In 210 Israeli Defence Forces (IDF) military conscripts, stress fracture injury was diagnosed (n=43) based on symptoms and a positive bone scan. In a separate cohort of 518 elite athletes, self-reported medical imaging scan-certified stress fracture injuries were recorded (n=125). Non-stress fracture controls were identified from these cohorts who had a normal bone scan or no history or symptoms of stress fracture injury. Study participants were genotyped for functional SNPs within the P2X7R gene using proprietary fluorescence-based competitive allele-specific PCR assay. Pearson Chi-square (χ2) tests, corrected for multiple comparisons, were used to assess associations in genotype frequencies. Results: The variant allele of P2X7R SNP rs3751143 (Glu496Ala- loss of function) was associated with stress fracture injury, while the variant allele of rs1718119 (Ala348Thr- gain of function) was associated with a reduced occurrence of stress fracture injury in military conscripts (P<0.05). The association of the variant allele of rs3751143 with stress fractures was replicated in elite athletes (P<0.05), whereas the variant allele of rs1718119 was also associated with reduced multiple stress fracture cases in elite athletes (P<0.05). Conclusions: The association between independent P2X7R polymorphisms with stress fracture prevalence supports the role of a genetic predisposition in the development of stress fracture injury

Associations between cardiorespiratory fitness, physical activity and clustered cardiometabolic risk in children and adolescents: the HAPPY study

Clustering of cardiometabolic risk factors can occur during childhood and predisposes individuals to cardiometabolic disease. This study calculated clustered cardiometabolic risk in 100 children and adolescents aged 10-14 years (59 girls) and explored differences according to cardiorespiratory fitness (CRF) levels and time spent at different physical activity (PA) intensities. CRF was determined using a maximal cycle ergometer test, and PA was assessed using accelerometry. A cardiometabolic risk score was computed as the sum of the standardised scores for waist circumference, blood pressure, total cholesterol/high-density lipoprotein ratio, triglycerides and glucose. Differences in clustered cardiometabolic risk between fit and unfit participants, according to previously proposed health-related threshold values, and between tertiles for PA subcomponents were assessed using ANCOVA. Clustered risk was significantly lower (p < 0.001) in the fit group (mean 1.21 ± 3.42) compared to the unfit group (mean -0.74 ± 2.22), while no differences existed between tertiles for any subcomponent of PA. Conclusion These findings suggest that CRF may have an important cardioprotective role in children and adolescents and highlights the importance of promoting CRF in youth

Transition probabilities for general birth-death processes with applications in ecology, genetics, and evolution

A birth-death process is a continuous-time Markov chain that counts the number of particles in a system over time. In the general process with $n$ current particles, a new particle is born with instantaneous rate $\lambda_n$ and a particle dies with instantaneous rate $\mu_n$. Currently no robust and efficient method exists to evaluate the finite-time transition probabilities in a general birth-death process with arbitrary birth and death rates. In this paper, we first revisit the theory of continued fractions to obtain expressions for the Laplace transforms of these transition probabilities and make explicit an important derivation connecting transition probabilities and continued fractions. We then develop an efficient algorithm for computing these probabilities that analyzes the error associated with approximations in the method. We demonstrate that this error-controlled method agrees with known solutions and outperforms previous approaches to computing these probabilities. Finally, we apply our novel method to several important problems in ecology, evolution, and genetics

Characteristics associated with quality of life among people with drug-resistant epilepsy

Quality of Life (QoL) is the preferred outcome in non-pharmacological trials, but there is little UK population evidence of QoL in epilepsy. In advance of evaluating an epilepsy self-management course we aimed to describe, among UK participants, what clinical and psycho-social characteristics are associated with QoL. We recruited 404 adults attending specialist clinics, with at least two seizures in the prior year and measured their self-reported seizure frequency, co-morbidity, psychological distress, social characteristics, including self-mastery and stigma, and epilepsy-specific QoL (QOLIE-31-P). Mean age was 42 years, 54% were female, and 75% white. Median time since diagnosis was 18 years, and 69% experienced ≥10 seizures in the prior year. Nearly half (46%) reported additional medical or psychiatric conditions, 54% reported current anxiety and 28% reported current depression symptoms at borderline or case level, with 63% reporting felt stigma. While a maximum QOLIE-31-P score is 100, participants’ mean score was 66, with a wide range (25–99). In order of large to small magnitude: depression, low self-mastery, anxiety, felt stigma, a history of medical and psychiatric comorbidity, low self-reported medication adherence, and greater seizure frequency were associated with low QOLIE-31-P scores. Despite specialist care, UK people with epilepsy and persistent seizures experience low QoL. If QoL is the main outcome in epilepsy trials, developing and evaluating ways to reduce psychological and social disadvantage are likely to be of primary importance. Educational courses may not change QoL, but be one component supporting self-management for people with long-term conditions, like epilepsy

Building Thriving Workforces from the Top Down: A Call and Research Agenda for Organizations to Proactively Support Employee Well-Being

Organizational researchers studying well-being – as well as organizations themselves – often place much of the burden on employees to manage and preserve their own well-being. Missing from this discussion is how – from a human resources management (HRM) perspective – organizations and managers can directly and positively shape the well-being of their employees. The authors use this review to paint a picture of what organizations could be like if they valued people holistically and embraced the full experience of employees’ lives to promote well-being at work. In so doing, the authors tackle five challenges that managers may have to help their employees navigate, but to date have received more limited empirical and theoretical attention from an HRM perspective: (1) recovery at work; (2) women’s health; (3) concealable stigmas; (4) caregiving; and (5) coping with socio-environmental jolts. In each section, the authors highlight how past research has treated managerial or organizational support on these topics, and pave the way for where research needs to advance from an HRM perspective. The authors conclude with ideas for tackling these issues methodologically and analytically, highlighting ways to recruit and support more vulnerable samples that are encapsulated within these topics, as well as analytic approaches to study employee experiences more holistically. In sum, this review represents a call for organizations to now – more than ever – build thriving organizations