Towards continuous monitoring of TNF-α at picomolar concentrations using biosensing by particle motion

The ability to continuously monitor cytokines is desirable for fundamental research studies and healthcare applications. Cytokine release is characterized by picomolar circulating concentrations, short half-lives, and rapid peak times. Here, we describe the characteristics and feasibility of a particle-based biosensing technique for continuous monitoring of TNF-α at picomolar concentrations. The technique is based on the optical tracking of particle motion and uses an antibody sandwich configuration. Experimental results show how the analyte concentration influences the particle diffusivity and characteristic response time of the sensor, and how the sensitivity range depends on the antibody functionalization density. Furthermore, the data clarifies how antibodies supplemented in solution can shorten the characteristic response time. Finally, we demonstrate association rate-based sensing as a first step towards continuous monitoring of picomolar TNF-α concentrations, over a period of 2 h with delay times under 15 min. The insights from this research will enable the development of continuous monitoring sensors using high-affinity binders, providing the sensitivity and speed needed in applications like cytokine monitoring.</p

Sandwich Immunosensor Based on Particle Motion:How Do Reactant Concentrations and Reaction Pathways Determine the Time-Dependent Response of the Sensor?

To control and optimize the speed of a molecular biosensor, it is crucial to quantify and understand the mechanisms that underlie the time-dependent response of the sensor. Here, we study how the kinetic properties of a particle-based sandwich immunosensor depend on underlying parameters, such as reactant concentrations and the size of the reaction chamber. The data of the measured sensor responses could be fitted with single-exponential curves, with characteristic response times that depend on the analyte concentration and the binder concentrations on the particle and substrate. By comparing characteristic response times at different incubation configurations, the data clarifies how two distinct reaction pathways play a role in the sandwich immunosensor, namely, analyte binding first to particles and thereafter to the substrate, and analyte binding first to the substrate and thereafter to a particle. For a concrete biosensor design, we found that the biosensor is dominated by the reaction pathway where analyte molecules bind first to the substrate and thereafter to a particle. Within this pathway, the binding of a particle to the substrate-bound analyte dominates the sensor response time. Thus, the probability of a particle interacting with the substrate was identified as the main direction to improve the speed of the biosensor while maintaining good sensitivity. We expect that the developed immunosensor and research methodology can be generally applied to understand the reaction mechanisms and optimize the kinetic properties of sandwich immunosensors with particle labels.</p

Plasma Ghrelin Levels Are Associated with Anorexia but Not Cachexia in Patients with NSCLC

Background and Aims: The ghrelin receptor is one of the new therapeutic targets in the cancer anorexia-cachexia syndrome. Previous studies revealed that plasma ghrelin levels were high in patients with anorexia nervosa and low in obese subjects. We studied to what extent ghrelin levels are related with anorexia and cachexia in patients with cancer. Materials and Methods: Fasted ghrelin levels were determined as well as anorexia and cachexia in patients with stage III/IV non-small cell lung cancer before chemotherapy. Total plasma ghrelin was measured by radioimmunoassay. Anorexia was measured with the FAACT-A/CS questionnaire (cut-off value ≤ 37). Cachexia was determined as > 5% weight loss (WL) in 6 months or > 2% WL in 6 months in combination with low BMI or low muscle mass. The Kruskal-Wallis test was performed to assess differences in plasma ghrelin levels between four groups: patients with (+) or without (-) anorexia (A) or cachexia (C). Multiple regression analyses were performed to assess differences in plasma ghrelin levels between patients C+ and C- and patients with A+ and A- (adjusted for age and sex). Results: Forty patients with stage III (33%) or stage IV (68%) were recruited, of which 50% was male. Mean age was 59.6 ± 10.3 years. Sixteen patients had no anorexia or cachexia (A-C-), seven patients had both anorexia and cachexia (A+C+), ten patients had anorexia without cachexia (A+C-) and seven patients had cachexia without anorexia (A-C+). The levels of total plasma ghrelin were significantly different between the four groups of patients with or without anorexia or cachexia (p = 0.032): the A+C- patients had significantly higher ghrelin levels [median (IQR): 1,754 (1,404-2,142) compared to the A-C+ patients 1,026 (952-1,357), p = 0.003]. A+ patients had significantly higher ghrelin levels compared A- patients (C+ and C- combined, β: 304, p = 0.020). Plasma ghrelin levels were not significantly different in C+ patients compared to C- patients (A+ and A- combined, β: -99, p = 0.450). Conclusions: Patients with anorexia had significantly higher ghrelin levels compared to patients without anorexia. We therefore hypothesize that patients with cancer anorexia might benefit from treatment with a ghrelin receptor agonist to prevent WL and deterioration in physical functioning

Higher Muscle Strength Is Associated with Prolonged Survival in Older Patients with Advanced Cancer

BACKGROUND: Identifying predictors of treatment toxicity and overall survival (OS) is important for selecting patients who will benefit from chemotherapy. In younger patients with cancer, muscle mass and radiodensity are associated with treatment toxicity and OS. In this study, we investigated whether muscle mass, radiodensity, and strength were associated with treatment toxicity and OS in patients with advanced cancer aged 60 years or older. MATERIALS AND METHODS: Before starting palliative chemotherapy, muscle mass and radiodensity were assessed using computed tomography scans and muscle strength was assessed using a hydraulic hand grip dynamometer. Treatment toxicity was defined as any toxicity resulting in dose reduction and/or discontinuation of treatment. Multiple logistic and Cox regression analyses were performed to study potential associations of muscle mass, radiodensity, and strength with treatment toxicity and OS, respectively. RESULTS: The participants were 103 patients, with a mean age of 70 years, with advanced colorectal, prostate, or breast cancer. Muscle parameters were not significantly associated with treatment toxicity. Higher muscle strength was associated with longer OS (hazard ratio 1.03; 95% confidence interval 1.00-1.05). Muscle mass and radiodensity were not significantly associated with OS. CONCLUSION: Higher muscle strength at the start of palliative chemotherapy is associated with significantly better OS in older patients with advanced cancer. None of the investigated muscle parameters were related to treatment toxicity. Future studies are needed to evaluate whether muscle strength can be used for treatment decisions in older patients with advanced cancer. IMPLICATIONS FOR PRACTICE: This study in older patients with advanced cancer showed that adequate muscle strength is associated with longer overall survival. The results of this study imply that muscle strength might be helpful in estimating survival and therefore in identifying older patients who will benefit from anticancer treatment

Colorectal cancer screening with faecal immunochemical testing, sigmoidoscopy or colonoscopy: a microsimulation modelling study

OBJECTIVE: To estimate benefits and harms of different colorectal cancer screening strategies, stratified by (baseline) 15-year colorectal cancer risk. DESIGN: Microsimulation modelling study using MIcrosimulation SCreening ANalysis-Colon (MISCAN-Colon). SETTING: A parallel guideline committee (BMJ Rapid Recommendations) defined the time frame and screening interventions, including

The second round of the Dutch colorectal cancer screening program: Impact of an increased fecal immunochemical test cut-off level on yield of screening

The Dutch colorectal cancer (CRC) screening program started in 2014, inviting the target population biennially to perform a fecal immunochemical test (FIT). We obtained prospectively collected data from the national screening information-system to present the results of the second round (2016) and evaluate the impact of increasing the FIT cut-off halfway through the first round from 15 to 47 μg Hb/g feces on outcomes in the second round. Second round screening was done with a 47 μg Hb/g feces FIT cut-off. Participants were classified based on first round participation status as either FIT (15,47) or FIT (47,47) participants, and previous nonparticipants. In total, 348,891 (75.9%) out of 459,740 invitees participated in the second round. Participation rates were 93.4% among previous participants and 21.0% among previous non-participants. FIT(47,47) participants had a significantly higher detection rate of AN (15.3 vs. 10.4 per 1,000 participants) compared to FIT(15,47) participants in the second round, while their cumulative detection rate of AN over two rounds was significantly lower (45.6 vs. 52.6 per 1,000 participants). Our results showed that participation in the Dutch CRC screening program was consistently high and that second round detection rates depended on the first round FIT cut-off. The cumulative detection over two rounds was higher among FIT(15,47) participants. These findings suggest that a substantial part of, but not all the missed findings in the first round due to the increased FIT cut-off were detected in the subsequent round

Incidence of Interval Colorectal Cancer After Negative Results From First-Round Fecal Immunochemical Screening Tests, by Cutoff Value and Participant Sex and Age

Background & Aims: We evaluated the incidence of interval cancers between the first and second rounds of colorectal cancer (CRC) screening with the FOB-Gold fecal immunochemical test (FIT), and the effects of different cutoff values and patient sex and age. Methods: We collected data from participants in a population-based

The Terneuzen Birth Cohort. Longer exclusive breastfeeding duration is associated with leaner body mass and a healthier diet in young adulthood

<p>Abstract</p> <p>Background</p> <p>Breastfeeding (BF) is protective against overweight and is associated with dietary behaviour. The aims of our study were to assess the relationship between exclusive BF duration and BMI, waist circumference (WC) and waist-hip ratio (WHR) at adulthood, and to study whether dietary behaviour could explain the relationship between BF duration and the proxies of fat mass.</p> <p>Methods</p> <p>In 2004-2005, 822 subjects from the Terneuzen Birth Cohort (n = 2,604), aged 18-28 years, filled in postal questionnaires including sociodemographic factors and aspects of dietary behaviour (dietary pattern, and consumption of fruit and vegetables, snacks, sweetened beverages and alcohol); 737 subjects also underwent anthropometric measurements of weight, height, and waist and hip circumference. The relationship between exclusive BF duration and dietary outcomes was investigated by logistic regression analysis. The relationships of BF duration with the anthropometric measures were investigated by linear regression analyses. All results were corrected for age, gender and possible confounders. Finally, regression analyses were performed to investigate if diet factors had a mediating effect on the relationship between BF duration and fat mass.</p> <p>Results</p> <p>A significant inverse dose-response relationship of BF duration was found for BMI (β-0.13, SE 0.06), WC (β-0.39, SE 0.18) and WHR (β-0.003, SE 0.001), after correction for age, gender and confounders. The odds ratio (OR) of exclusive BF duration in months for a breakfast frequency of at least 5 times a week was 1.16 (95%CI 1.06-1.27), and for snack consumption of less than twice a week was 1.15 (95%CI 1.06-1.25). Both ORs were corrected for age, gender and confounders. For other dietary outcomes, the results point in the same direction, i.e. a positive relationship with BF duration, but these were not statistically significant. A mediating effect of the diet factors on the association between BF and anthropometric outcomes was not shown.</p> <p>Conclusions</p> <p>Exclusive BF duration had a significant inverse dose-response relationship with BMI, WC and WHR at young adulthood. BF duration was positively related to a healthier diet at adulthood, but this did not explain the protective effect of BF against body fat. Our results underline the recommendation of the WHO to exclusively breastfeed for 6 months or longer.</p

Development and Validation of Three Regional Microsimulation Models for Predicting Colorectal Cancer Screening Benefits in Europe

Background. Validated microsimulation models have been shown to be useful tools in providing support for colorec- tal cancer (CRC) screening decisions. Aiming to assist European countries in reducing CRC mortality, we developed and validated three regional models for evaluating CRC screening in Europe. Methods. Microsimulation Screening Analysis–Colon (MISCAN-Colon) model versions for Italy, Slovenia, and Finland were quantified using data from different national institutions. These models were validated against the best available evidence for the effectiveness of screening from their region (when available): the Screening for COlon REctum (SCORE) trial and the Florentine fecal immunochemical test (FIT) screening study for Italy; the Norwegian Colorectal Cancer Prevention (NORCCAP) trial and the guaiac fecal occult blood test (gFOBT) Finnish population-based study for Finland. When published evidenc

MicroMotility: State of the art, recent accomplishments and perspectives on the mathematical modeling of bio-motility at microscopic scales

Mathematical modeling and quantitative study of biological motility (in particular, of motility at microscopic scales) is producing new biophysical insight and is offering opportunities for new discoveries at the level of both fundamental science and technology. These range from the explanation of how complex behavior at the level of a single organism emerges from body architecture, to the understanding of collective phenomena in groups of organisms and tissues, and of how these forms of swarm intelligence can be controlled and harnessed in engineering applications, to the elucidation of processes of fundamental biological relevance at the cellular and sub-cellular level. In this paper, some of the most exciting new developments in the fields of locomotion of unicellular organisms, of soft adhesive locomotion across scales, of the study of pore translocation properties of knotted DNA, of the development of synthetic active solid sheets, of the mechanics of the unjamming transition in dense cell collectives, of the mechanics of cell sheet folding in volvocalean algae, and of the self-propulsion of topological defects in active matter are discussed. For each of these topics, we provide a brief state of the art, an example of recent achievements, and some directions for future research