The fluid dynamics of barnacle feeding

Sessile barnacles feed by sweeping their basket-like cirral fan through the water, intercepting suspended prey. A primary component of the diet of adult barnacles is copepods that are sensitive to fluid disturbances and capable of escaping. How do barnacles manage to capture copepods despite the fluid disturbances they generate? We examined this question by describing the feeding current architecture of 1 cm sized Balanus crenatus using particle image velocimetry, and by studying the trajectories of captured copepods and the escapes of evading copepods. We found that barnacles produce a feeding current that arrives both from behind and the sides of the barnacle. The flow from the sides represents quiescent corridors of low fluid deformation and uninterrupted by the beating cirral fan. Potential prey arriving from behind are likely to encounter the cirral fan and, hence, capture here is highly unlikely. Accordingly, most captured copepods arrived through the quiet corridors, while most copepods arriving from behind managed to escape. Thus, it is the unique feeding flow architecture that allows feeding on evasive prey. We used the Landau-Squire jet as a simple model of the feeding current. For the Reynolds number of our experiments, the model reproduces the main features of the feeding current, including the lateral feeding corridors. Furthermore, the model suggests that smaller barnacle specimens, operating at lower Reynolds numbers, will produce a fore-aft symmetric feeding current without the lateral corridors. This suggests an ontogenetic diet shift from non-evasive prey to inclusion of evasive prey as the barnacle grows.

Co-occurrence of Periodontitis and Diabetes-Related Complications

Periodontitis is a common finding among people with diabetes mellitus (DM) and has been cited as a DM complication. Whether and how periodontitis relates to other diabetes-related complications has yet to be explored. This study aims to examine the clustering of periodontitis with other diabetes-related complications and explore pathways linking diabetes-related complications with common risk factors. Using data from participants with DM across 3 cycles of the National Health and Nutrition Examination Survey (NHANES) (n = 2,429), we modeled direct and indirect pathways from risk factors to diabetes-related complications, a latent construct comprising periodontitis, cardiovascular diseases, proteinuria, and hypertension. Covariates included age, sex, socioeconomic status (SES), smoking, physical activity, healthy diet, alcohol consumption, hemoglobin A1c (HbA1c), dyslipidemia, and body mass index (BMI). Sensitivity analyses were performed considering participants with overweight/obesity and restricting the sample to individuals without DM. Periodontitis clustered with other diabetes complications, forming a latent construct dubbed diabetes-related complications. In NHANES III, higher HbA1c levels and BMI, older age, healthy diet, and regular physical activity were directly associated with the latent variable diabetes-related complications. In addition, a healthy diet and BMI had a total effect on diabetes-related complications. Although sex, smoking, dyslipidemia, and SES demonstrated no direct effect on diabetes-related complications in NHANES III, a direct effect was observed using NHANES 2011-2014 cycles. Sensitivity analysis considering participants with overweight/obesity and without DM showed consistent results. Periodontal tissue breakdown seems to co-occur with multiple diabetes-related complications and may therefore serve as a valuable screening tool for other well-known diabetes-related complications.

Data Collection and Analysis Methods for Smart Nudging to Promote Physical Activity: Protocol for a Mixed Methods Study

New digital technologies like activity trackers, nudge concepts, and approaches can inspire and improve personal health. There is increasing interest in employing such devices to monitor people's health and well-being. These devices can continually gather and examine health-related information from people and groups in their familiar surroundings. Context-aware nudges can assist people in self-managing and enhancing their health. In this protocol paper, we describe how we plan to investigate what motivates people to engage in physical activity (PA), what influences them to accept nudges, and how participant motivation for PA may be impacted by technology use.

Acoustic tethering of microorganisms

We show how to construct and apply a setup to acoustically tether and enable behavioral observations of individual microorganisms using simple laboratory equipment and a standard light microscope. We explore the capability of the setup with the freely swimming dinoflagellate Alexandrium minutum as study organism. We demonstrate that the setup allows us to tether cells in focus in the mid-plane of the sample chamber and make observations of individual organisms at high magnification without affecting their flagellar beat frequencies. We discuss the prospect of the method to explore appendage motion and swimming kinematics of other flagellates and ciliates.

Chronic thromboembolic pulmonary hypertension and mortality after venous thromboembolism: a nationwide population-based cohort study

Background

One of the ultimate long-term complications of venous thromboembolism (VTE) is chronic thromboembolic pulmonary hypertension (CTEPH). CTEPH is a condition defined as an increased mean pulmonary arterial pressure of at least 25 mmHg at rest and abnormal pulmonary artery resistance measured by right heart catheterization. To our knowledge, no study has compared mortality in VTE patients developing CTEPH to those who do not.

Purpose

We aimed to investigate the influence of CTEPH on long-term VTE mortality, by examining how receiving any pulmonary hypertension (PH) diagnosis following VTE influenced mortality.

Methods

We conducted a population-based cohort study of all adult Danish patients with an incident in or outpatient VTE diagnosis from 1995 through 2016. We excluded patients with a previous PH diagnosis. We defined CTEPH as receiving any PH diagnosis within two years following VTE. We categorized VTE by type (deep venous thrombosis [DVT] or pulmonary embolism [PE]) and provoking risk factors. We followed patients from two years after VTE until the first of death, emigration, or 31 December 2016. We calculated mortality rates and standardized mortality rate ratios (SMRs) of the association between PH and all-cause mortality and cause-specific mortality due to cancer and cardiovascular diseases. We also stratified the analyses by baseline presence of comorbidity (congestive heart failure, chronic pulmonary disease, and/or interstitial pulmonary disease).

Results

In 89,062 VTE patients alive two years after their VTE, 724 developed PH. The mortality rate per 1,000 person-years was 121 (95% confidence interval [CI]: 110–134) in patients with PH and 48 (95% CI: 47–48) in patients without PH. The SMR was 2.05 (95% CI: 1.77–2.37) for all VTE patients, 2.20 (95% CI: 1.53–3.16) for DVT patients, and 1.72 (95% CI: 1.47–2.01) for PE patients. The SMR was 1.79 (95% CI: 1.28–2.51) in VTE patients with a provoking VTE risk factor and 2.15 (95% CI: 1.83–2.53) in VTE patients without a provoking VTE risk factor. PH was associated with increased cause-specific mortality due to cardiovascular diseases (SMR=2.31, 95% CI: 1.75–3.06), but not cancer (SMR=0.94, 95% CI: 0.64–1.38). The SMR was 2.36 (95% CI: 2.06–2.71) in patients with comorbidity and 1.80 (95% CI: 1.45–2.24) in patients without comorbidity.

Conclusion

Development of PH, as a measure of CTEPH, within two years following incident VTE was associated with two-fold increased mortality in two-year VTE survivors. The increase in mortality was driven by cardiovascular causes.

Funding Acknowledgement

Type of funding sources: None.

Description of a clinical intervention among patients admitted to the medium secure forensic psychiatric services in Central Denmark Region

Introduction

Patients with schizophrenia suffer from increased mortality rates equivalent to 15-20 years shorter life expectancy. Up to 60% of this excess mortality can be explained by preventable, somatic conditions like cardiovascular, metabolic, and respiratory comorbidities. As forensic psychiatric (FP) patients often experience the triple stigmatization of mental illness, substance misuse and criminal conviction, the risk of suboptimal diagnosis and treatment may be high. Although benefits from the addition of general practitioner (GP) services to non-FP wards have been shown elsewhere, this cross-sectoral approach has never been attempted in a Danish FP ward.

Objectives

One purpose of this project is to evaluate the associations between self-reported quality of life and objective measures of somatic health.

Methods

A clinical intervention in which a GP consults patients in all medium secure wards in the Central Denmark Region (N=72). The consultation includes a physical examination, medication review, and evaluation of blood samples. Data is collected from: electronic patient files and questionnaires regarding quality of life (SF-12), lifestyle, and attitude towards GP services.

Results

The population will be described in regards to socio-demographic, clinical, and forensic characteristics. Associations will be made between quality of life (SF-12), metabolic syndrome, blood markers, and heart-SCORE risk. Risk profiles for endocrinologic and coronary illness will be examined.

Conclusions

Results may guide future health interventions and will be used as a basis for adjustments to the current project.

Disclosure

No significant relationships.

T1ρ imaging as a non-invasive assessment of collagen remodelling and organization in human skeletal muscle after ligamentous injury

Dysregulation and fibrosis of the extracellular matrix (ECM) in skeletal muscle is a consequence of injury. Current ECM assessment necessitates muscle biopsies to evaluate alterations to the muscle ECM, which is often not practical in humans. The goal of this study was to evaluate the potential of a magnetic resonance imaging sequence that quantifies T1ρ relaxation time to predict ECM collagen composition and organization. T1ρ imaging was performed and muscle biopsies obtained from the involved and non-involved vastus lateralis muscle on 27 subjects who had an anterior cruciate ligament (ACL) tear. T1ρ times were quantified via monoexponential decay curve fitted to a series of T1ρ-weighted images. Several ECM indices, including collagen content and organization, were obtained using immunohistochemistry and histochemistry in addition to hydroxyproline. Model selection with multiple linear regression was used to evaluate the relationships between T1ρ times and ECM composition. Additionally, the ACL-deficient and healthy limb were compared to determine sensitivity of T1ρ to detect early adaptations in the muscle ECM following injury. We show that T1ρ relaxation time was strongly associated with collagen unfolding (t = 4.093, P = 0.0007) in the ACL-deficient limb, and collagen 1 abundance in the healthy limb (t = 2.75, P = 0.014). In addition, we show that T1ρ relaxation time is significantly longer in the injured limb, coinciding with significant differences in several indices of collagen content and remodelling in the ACL-deficient limb. These results support the use of T1ρ to evaluate ECM composition in skeletal muscle in a non-invasive manner. KEY POINTS: Dysregulation and fibrotic transformation of the skeletal muscle extracellular matrix (ECM) is a common pathology associated with injury and ageing. Studies of the muscle ECM in humans have necessitated the use of biopsies, which are impractical in many settings. Non-invasive MRI T1ρ relaxation time was validated to predict ECM collagen composition and organization with aligned T1ρ imaging and biopsies of the vastus lateralis in the healthy limb and anterior cruciate ligament (ACL)-deficient limb of 27 subjects. T1ρ relaxation time was strongly associated with collagen abundance and unfolding in the ACL-deficient limb, and T1ρ relaxation time was strongly associated with total collagen abundance in the healthy limb. T1ρ relaxation time was significantly longer in the ACL-deficient limb, coinciding with significant increases in several indices of muscle collagen content and remodelling supporting the use of T1ρ to non-invasively evaluate ECM composition and pathology in skeletal muscle.

Neuroplasticity in Corticolimbic Brain Regions in Patients After Anterior Cruciate Ligament Reconstruction

CONTEXT

Fear has been cited as the primary barrier to return to sport (RTS) by athletes after anterior cruciate ligament reconstruction (ACLR). Understanding the neural factors that contribute to fear after ACLR may help us to identify interventions for this population.

OBJECTIVE

To characterize the underlying neural substrate of injury-related fear in patients after ACLR versus healthy matched control individuals during a picture imagination task (PIT) consisting of sport-specific images and images of activities of daily living (ADL).

DESIGN

Case-control study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 24 right-hand-dominant participants (12 with left-sided ACLR and 12 control individuals) were enrolled. Participants underwent full-brain functional magnetic resonance imaging.

MAIN OUTCOME MEASURE(S)

Functional data were acquired using blood oxygen level-dependent (BOLD) echoplanar imaging. Independent t tests were conducted to identify between-groups differences in BOLD signal changes during all images of the PIT. Paired t tests were computed to examine differences in BOLD signal change between sport-specific and ADL images in the ACLR group.

RESULTS

Increased activation in the inferior parietal lobule and the mediodorsal thalamus was observed during PIT in the ACLR group. An inability to suppress the default mode network in the ACLR group was noted. The ACLR group exhibited increased activation in the cerebellum and inferior occipital regions during the sport-specific images versus the ADL images, but no other regions of interest demonstrated differences.

CONCLUSION

After ACLR, patients may be more predisposed to fear, anxiety, and pain during sport-specific activities and ADLs. Psychosocial interventions may be warranted after ACLR to reduce injury-related fear and mitigate potentially maladaptive neuroplasticity.

Behavioral and Hemodynamic Changes Following Dichotic Training in Patients with Neurological Deficits of the Auditory Nervous System: A Case Series

BACKGROUND

 Dichotic listening occurs when one attends to different acoustical messages presented simultaneously to both ears. This is important for understanding speech in compromised listening situations, such as background noise. Deficits in dichotic listening can be remediated by participating in auditory training. We present two patients with binaural integration deficits who underwent dichotic interaural intensity difference (DIID) training.

PURPOSE

 The purpose of this investigation is to demonstrate improvement of dichotic listening deficits following DIID training in neurological patients seen clinically for hearing issues.

RESEARCH DESIGN

 This was a case series utilizing a pre- and posttreatment design.

STUDY SAMPLE

 This case series utilized two female participants who demonstrated binaural integration deficits during an auditory processing evaluation.

INTERVENTION

 The participants underwent a pretraining auditory processing evaluation and functional magnetic resonance imaging (fMRI). Participants then underwent 12, 30-minute DIID training sessions followed by posttreatment auditory processing evaluations and fMRI.

DATA COLLECTION AND ANALYSIS

 Data was collected at the pretreatment appointment and then immediately following the completion of the training.

RESULTS

 Each patient demonstrated varying degrees of improvement on the posttreatment assessment. Case 1 showed significant improvement on the Speech-in-Noise-Revised (SPIN-R) test. fMRI showed changes in activation patterns following training. Case 2 demonstrated improved scores on the Dichotic Digits Test and SPIN-R and increased activation of the calcarine sulcus following training.

CONCLUSION

 Dichotic training can be an efficacious treatment for binaural integration deficits and may show evidence of improving speech understanding in noise. This case series demonstrates a promising therapy to help patients improve auditory function by improving dichotic listening skills.

The effect of external flow on the feeding currents of sessile microorganisms

Microscopic sessile suspension feeders live attached to surfaces and, by consuming bacteria-sized prey and by being consumed, they form an important part of aquatic ecosystems. Their environmental impact is mediated by their feeding rate, which depends on a self-generated feeding current. The feeding rate has been hypothesized to be limited by recirculating eddies that cause the organisms to feed from water that is depleted of food particles. However, those results considered organisms in still water, while ambient flow is often present in their natural habitats. We show, using a point-force model, that even very slow ambient flow, with speed several orders of magnitude less than that of the self-generated feeding current, is sufficient to disrupt the eddies around perpendicular suspension feeders, providing a constant supply of food-rich water. However, the feeding rate decreases in external flow at a range of non-perpendicular orientations due to the formation of recirculation structures not seen in still water. We quantify the feeding flow and observe such recirculation experimentally for the suspension feeder Vorticella convallaria in external flows typical of streams and rivers.

23 Biopsied invitro-produced bovine blastocysts survive vitrification better than slow freezing

Trophectoderm (TE) biopsying for single nucleotide polymorphisms (SNPs) analysis is being implemented as a tool for the selection of elite bovine embryos. This biopsy method renders ample cells for analysis without compromising the inner cell mass (ICM), and the blastocyst recovers quickly after biopsy. To use the SNP data for embryo selection before the transfer, the blastocysts need to be cryopreserved either with vitrification or slow-freezing. In intact invitro-produced (IVP) blastocysts, vitrification has already proven optimal regarding embryo survival and pregnancy rates. This study aimed to investigate which cryopreservation approach is superior regarding blastocyst re-expansion rate as well as ICM, TE, and dead cell numbers after biopsying bovine IVP blastocysts. All IVP media and vitrification kits were from IVF Bioscience, and ethylene glycol with sucrose was from EggTech. Oocytes from slaughterhouse ovaries were used for blastocyst IVP. At Day 7, the blastocysts were pooled and randomised into 3 groups: (1) biopsy-control (BC), (2) biopsy-vitrification (BV), (3) biopsy-slow freeze (BSF). Subsequently, 5 to 10 TE cells were biopsied in BO-transfer medium using a 25-µm (inner diameter) biopsy pipette and flicking against the holding pipette. The BC group was incubated at 6% CO2 and 38.8°C for 5h. After scoring the re-expansion rate, the blastocysts were fixed with 4% paraformaldehyde/sucrose for further analyses. The BV and BSF groups were subjected to cryopreservation/thawing protocols according to the manufacturers’ instructions. Both groups, recovered under the same culture conditions as BC, were subsequently scored for re-expansion rate and finally fixed. For cell counting, the embryos were stained with Hoechst (DNA) and CDX2 (TE), combined with the TUNEL staining. ImageJ software (National Institutes for Health) was used for cell counting. P<0.05 was considered statistically significant and was determined using Fisher’s exact test for blastocyst re-expansion rate and Student’s t-test for cell numbers. The re-expansion rate in BV was 81% (61/75), which was significantly lower than in BC (95%; 225/236; P<0.005). In BSF, the re-expansion rate was 52% (28/54), which was significantly lower than in both BV and BC (both P<0.005). For cell counts, 18, 18, and 14 embryos, pooled from 3 to 4 independent IVP replicates, were analysed in BC, BV, and BSF, respectively. The average numbers of ICM cells in BV and BSF were 36±5 and 37±11, respectively, and neither was statistically different from BC (34±7; P>0.05). The average cell counts for TE cells in BV and BSF were 59±6 and 47±10, respectively, and neither was statistically different from BC (56±8; P>0.05). The average numbers of dead cells in BV and BSF were 8±3 and 9±2, respectively, and neither was statistically different from BC (10±4; P>0.05). In summary, the biopsied bovine IVP blastocysts recovered better after vitrification, and neither of cryopreservation methods had any effect on the numbers of ICM, TE, or dead cells. This project was supported by Innovation Fund Denmark and the Danish Milk Levy Foundation.

Early BCG Vaccination, Hospitalizations, and Hospital Deaths: Analysis of a Secondary Outcome in 3 Randomized Trials from Guinea-Bissau

Background

This study was performed to examine the effects of early BCG vaccination on the risk, cause, and severity of infant hospitalizations. The analysis included 3 trials randomizing low-weight neonates to early BCG vaccination (intervention) versus no BCG vaccination (usual practice in low-weight neonates, control), with hospitalizations as secondary outcome.

Methods

Hospitalization data were collected at the pediatric ward of the National Hospital. Effects of BCG vaccination on hospitalization risk were assessed in Cox models providing overall and major disease-group incidence rate ratios (IRRs). Severity was assessed by means of in-hospital case-fatality rates and compared by group as cohort study risk ratios (RRs).

Results

Among 6583 infants (3297 in BCG group, 3286 controls), there were 908 infant hospitalizations (450 BCG, 458 controls) and 135 in-hospital deaths (56 BCG, 79 controls). The neonatal (28 days), 6-week, and infant (1-year) BCG versus control hospitalization IRRs were 0.97 (95% confidence interval [CI], .72-1.31), 0.95 (.73-1.24), and 0.96 (.84-1.10). Corresponding BCG versus control case-fatality rate RRs were 0.58 (95% CI, .35-.94), 0.56 (.35-.90), and 0.72 (.53-.99). BCG vaccination tended to reduce neonatal and infant sepsis hospitalization rates (IRR, 0.75 [95% CI, .50-1.13] and 0.78 [.55-1.11], respectively), and it reduced the neonatal in-hospital sepsis mortality rate (RR, 0.46; 95% CI, .22-.98). There were no confirmed hospitalizations for tuberculosis.

Conclusions

BCG vaccination did not affect hospitalization rates but reduced in-hospital mortality rates significantly, primarily by preventing fatal cases of sepsis. The observed beneficial effects of BCG on the in-hospital mortality rate were entirely nonspecific.

Clinical Trials Registration

NCT00146302, NCT00168610, and NCT00625482.

Planktonic encounter rates with non-spherical encounter zones

We present general formulae for planktonic predator-prey encounter rates with encounter zones of convex shape and randomly moving point-like prey with ballistic motion. When the predator is not moving, we show that the encounter rate is independent of the shape of the encounter zone around it and proportional to the product of the surface area of the encounter zone and the prey speed. By contrast, the shape of the encounter zone plays a role when both the predator and the prey are moving. Slow predator motion results in only a weak increase of the encounter rate relative to the non-motile predator situation, but it may lead to a significant shift in where prey impact the surface of the encounter zone. By analysing disc-like and rod-like encounter zones with lengthwise and sideways motion, respectively, we show that fast predator motion may significantly influence the encounter rate, depending on the shape and the direction of motion of the encounter zone.

Dense Dwarfs versus Gelatinous Giants: The Trade-Offs and Physiological Limits Determining the Body Plan of Planktonic Filter Feeders

Most marine plankton have a high energy (carbon) density, but some are gelatinous with approximately 100 times more watery bodies. How do those distinctly different body plans emerge, and what are the trade-offs? We address this question by modeling the energy budget of planktonic filter feeders across life-forms, from micron-sized unicellular microbes such as choanoflagellates to centimeter-sized gelatinous tunicates such as salps. We find two equally successful strategies, one being small with high energy density (dense dwarf) and the other being large with low energy density (gelatinous giant). The constraint that forces large-but not small-filter feeders to be gelatinous is identified as a lower limit to the size-specific filter area, below which the energy costs lead to starvation. A further limit is found from the maximum size-specific motor force that restricts the access to optimum strategies. The quantified constraints are discussed in the context of other resource-acquisition strategies. We argue that interception feeding strategies can be accessed by large organisms only if they are gelatinous. On the other hand, organisms that use remote prey sensing do not need to be gelatinous, even if they are large.

Hydrodynamic functionality of the lorica in choanoflagellates

Choanoflagellates are unicellular eukaryotes that are ubiquitous in aquatic habitats. They have a single flagellum that creates a flow toward a collar filter composed of filter strands that extend from the cell. In one common group, the loricate choanoflagellates, the cell is suspended in an elaborate basket-like structure, the lorica, the function of which remains unknown. Here, we use Computational Fluid Dynamics to explore the possible hydrodynamic function of the lorica. We use the choanoflagellate Diaphaoneca grandis as a model organism. It has been hypothesized that the function of the lorica is to prevent refiltration (flow recirculation) and to increase the drag and, hence, increase the feeding rate and reduce the swimming speed. We find no support for these hypotheses. On the contrary, motile prey are encountered at a much lower rate by the loricate organism. The presence of the lorica does not affect the average swimming speed, but it suppresses the lateral motion and rotation of the cell. Without the lorica, the cell jiggles from side to side while swimming. The unsteady flow generated by the beating flagellum causes reversed flow through the collar filter that may wash away captured prey while it is being transported to the cell body for engulfment. The lorica substantially decreases such flow, hence it potentially increases the capture efficiency. This may be the main adaptive value of the lorica.

Methodology and effects of repeated intranasal delivery of DNSP-11 in awake Rhesus macaques

BACKGROUND

To determine if the intranasal delivery of neuroactive compounds is a viable, long-term treatment strategy for progressive, chronic neurodegenerative disorders, such as Parkinson's disease (PD), intranasal methodologies in preclinical models comparable to humans are needed.

NEW METHOD

We developed a methodology to evaluate the repeated intranasal delivery of neuroactive compounds on the non-human primate (NHP) brain, without the need for sedation. We evaluated the effects of the neuroactive peptide, DNSP-11 following repeated intranasal delivery and dose-escalation over the course of 10-weeks in Rhesus macaques. This approach allowed us to examine striatal target engagement, safety and tolerability, and brain distribution following a single ¹²⁵I-labeled DNSP-11 dose.

RESULTS

Our initial data support that repeated intranasal delivery and dose-escalation of DNSP-11 resulted in bilateral, striatal target engagement based on neurochemical changes in dopamine (DA) metabolites-without observable, adverse behavioral effects or weight loss in NHPs. Furthermore, a ¹²⁵I-labeled DNSP-11 study illustrates diffuse rostral to caudal distribution in the brain including the striatum-our target region of interest.

COMPARISON WITH EXISTING METHODS

The results of this study are compared to our experiments in normal and 6-OHDA lesioned rats, where DNSP-11 was repeatedly delivered intranasally using a micropipette with animals under light sedation.

CONCLUSIONS

The results from this proof-of-concept study support the utility of our repeated intranasal dosing methodology in awake Rhesus macaques, to evaluate the effects of neuroactive compounds on the NHP brain. Additionally, results indicate that DNSP-11 can be safely and effectively delivered intranasally in MPTP-treated NHPs, while engaging the DA system.

Short communication: Persistent socio-economic inequality in frequent headache among Danish adolescents from 1991 to 2014

BACKGROUND

The association between socio-economic status (SES) and headache among adolescents is an understudied issue, and no study has examined whether such an association changes over time. The aim was to examine trends in socio-economic inequality in frequent headache among 11- to 15-year-olds in Denmark from 1991 to 2014, using occupational social class (OSC) as indicator of SES.

METHODS

The study applies data from the Danish part of the international Health Behaviour in School-aged Children (HBSC) study. HBSC includes nationally representative samples of 11-, 13- and 15-year-olds. This study combines data from seven data survey years from 1991 to 2014, participation rate 88.6%, n = 31,102. We report absolute inequality as per cent difference in frequent headache between high and low OSC and relative inequality as odds ratio for frequent headache by OSC.

RESULTS

In the entire study population, 10.4% reported frequent headache. There was a significant increase in frequent headache from 8.0% in 1991 to 12.9% in 2014, test for trend, p < 0.0001. This increasing trend was significant in all OSCs. The prevalence of frequent headache was significantly higher in low than high OSC, OR = 1.50 (95% CI: 1.34-1.67). This socio-economic inequality in frequent headache was persistent from 1991 to 2014.

CONCLUSION

There was a significant and persistent socio-economic inequality, i.e. increasing prevalence of frequent headache with decreasing OSC. The association between socio-economic position and headache did not significantly change over time, i.e. the statistical interaction between OSC and survey year was insignificant.

SIGNIFICANCE

The prevalence of frequent headache among adolescents increases with decreasing SES. This socio-economic inequality has been persistent among adolescents in Denmark from 1991 to 2014. Clinicians should be aware of this social inequality.

Bacillus Calmette-Guérin vaccination at birth and in vitro cytokine responses to non-specific stimulation. A randomized clinical trial

Several studies have shown increased in vitro cytokine responses to non-related pathogens after Bacillus Calmette-Guérin (BCG) vaccination. A total of 158 infants (80 BCG administered within 7 days of birth; 78 controls) were bled 4 days post-randomization, and at age 3 and 13 months. Geometric mean concentrations of IL-1β, TNF-α, IL-6 (24 h stimulation) and IFN-γ, IL-10, IL-17, IL-22 (96 h stimulation) in response to in vitro stimulation with RPMI, LPS, PHA, Escherichia coli, Streptococcus pneumoniae, Candida albicans and BCG were compared among BCG vaccinated children and controls. BCG vaccination did not affect in vitro cytokine production, except IFN-γ and IL-22 response to BCG. Stratifying for 'age at randomization' we found a potentiating effect of BCG on cytokine production (TNF-α, IL-6, IL-10) in the 4 days post randomization stimulations, among children who were vaccinated at age 2-7 days versus age 0-1 days. BCG vaccination did not potentiate cytokine production to non-BCG antigens. At 4 days post randomization, BCG was associated with higher cytokine production in the later randomized children.

Swimming and feeding of mixotrophic biflagellates

Many unicellular flagellates are mixotrophic and access resources through both photosynthesis and prey capture. Their fitness depends on those processes as well as on swimming and predator avoidance. How does the flagellar arrangement and beat pattern of the flagellate affect swimming speed, predation risk due to flow-sensing predators, and prey capture? Here, we describe measured flows around two species of mixotrophic, biflagellated haptophytes with qualitatively different flagellar arrangements and beat patterns. We model the near cell flows using two symmetrically arranged point forces with variable position next to a no-slip sphere. Utilizing the observations and the model we find that puller force arrangements favour feeding, whereas equatorial force arrangements favour fast and quiet swimming. We determine the capture rates of both passive and motile prey, and we show that the flow facilitates transport of captured prey along the haptonema structure. We argue that prey capture alone cannot fulfil the energy needs of the observed species, and that the mixotrophic life strategy is essential for survival.

The effect of early measles vaccination at 4.5 months of age on growth at 9 and 24 months of age in a randomized trial in Guinea-Bissau

Background

Providing an early, additional measles vaccine (MV) at 4.5 months of age has been shown to reduce child mortality in low-income countries. We studied the effects on growth at 9 and 24 months of age.

Methods

A randomized controlled trial was conducted in Guinea-Bissau from 2003–2007 including 6,648 children. Children were randomized 1:1:1 to receive Edmonston-Zagreb measles vaccine at 4.5 and 9 months of age (group A), no vaccine at 4.5 months and Edmonston-Zagreb measles vaccine at 9 months (group B), or no vaccine at 4.5 months and Schwarz measles vaccine at 9 months (group C) Data on anthropometrics were obtained at enrolment at 4.5 months of age and again at 9 and 24 months of age. Analyses were stratified by sex, season of enrolment, and neonatal vitamin A supplementation (NVAS) status, as all these factors have been shown to modify the effect of early MV on mortality.

Results

Overall there was no effect of early MV on anthropometry at 9 months. At 24 months children who had received early MV had a significantly larger mid-upper-arm-circumference (MUAC/in cm) (Difference = 0.08; 95% CI (0.02;0.14)) compared with children in the control group; this effect was most pronounced among girls (0.12 (0.03;0.20)). The effect of early MV on MUAC remained significant in the dry season and in girls who received placebo rather than NVAS.

Conclusion

Early MV was associated with a larger MUAC particularly in girls. These results indicate that a two-dose measles vaccination schedule might not only reduce child mortality but also improve growth.

Trial registration

ClinicalTrials.gov NCT00168558. Registered September 9, 2005, retrospectively registered

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-016-0738-z) contains supplementary material, which is available to authorized users.

Cellular and Morphological Alterations in the Vastus Lateralis Muscle as the Result of ACL Injury and Reconstruction

BACKGROUND

Individuals who have had an anterior cruciate ligament (ACL) tear and reconstruction continue to experience substantial knee extensor strength loss despite months of physical therapy. Identification of the alterations in muscle morphology and cellular composition are needed to understand potential mechanisms of muscle strength loss, initially as the result of the injury and subsequently from surgery and rehabilitation.

METHODS

We performed diffusion tensor imaging-magnetic resonance imaging and analyzed muscle biopsies from the vastus lateralis of both the affected and unaffected limbs before surgery and again from the reconstructed limb following the completion of rehabilitation. Immunohistochemistry was done to determine fiber type and size, Pax-7-positive (satellite) cells, and extracellular matrix (via wheat germ agglutinin straining). Using the diffusion tensor imaging data, the fiber tract length, pennation angle, and muscle volume were determined, yielding the physiological cross-sectional area (PCSA). Paired t tests were used to compare the effects of the injury between injured and uninjured limbs and the effects of surgery and rehabilitation within the injured limb.

RESULTS

We found significant reductions before surgery in type-IIA muscle cross-sectional area (CSA; p = 0.03), extracellular matrix (p < 0.01), satellite cells per fiber (p < 0.01), pennation angle (p = 0.03), muscle volume (p = 0.02), and PCSA (p = 0.03) in the injured limb compared with the uninjured limb. Following surgery, these alterations in the injured limb persisted and the frequency of the IIA fiber type decreased significantly (p < 0.01) and that of the IIA/X hybrid fiber type increased significantly (p < 0.01).

CONCLUSIONS

Significant and prolonged differences in muscle quality and morphology occurred after ACL injury and persisted despite reconstruction and extensive physical therapy.

CLINICAL RELEVANCE

These results suggest the need to develop more effective early interventions following an ACL tear to prevent deleterious alterations within the quadriceps.

Alzheimer's Biomarkers are Correlated with Brain Connectivity in Older Adults Differentially during Resting and Task States

β-amyloid (Aβ) plaques and tau-related neurodegeneration are pathologic hallmarks of Alzheimer’s disease (AD). The utility of AD biomarkers, including those measured in cerebrospinal fluid (CSF), in predicting future AD risk and cognitive decline is still being refined. Here, we explored potential relationships between functional connectivity (FC) patterns within the default-mode network (DMN), age, CSF biomarkers (Aβ₄₂ and pTau₁₈₁), and cognitive status in older adults. Multiple measures of FC were explored, including a novel time series-based measure [total interdependence (TI)]. In our sample of 27 cognitively normal older adults, no significant associations were found between levels of Aβ₄₂ or pTau₁₈₁ and cognitive scores or regional brain volumes. However, we observed several novel relationships between these biomarkers and measures of FC in DMN during both resting-state and a short-term memory task. First, increased connectivity between bilateral anterior middle temporal gyri was associated with higher levels of CSF Aβ₄₂ and Aβ₄₂/pTau₁₈₁ ratio (reflecting lower AD risk) during both rest and task. Second, increased bilateral parietal connectivity during the short-term memory task, but not during rest, was associated with higher levels of CSF pTau₁₈₁ (reflecting higher AD risk). Third, increased connectivity between left middle temporal and left parietal cortices during the active task was associated with decreased global cognitive status but not CSF biomarkers. Lastly, we found that our new TI method was more sensitive to the CSF Aβ₄₂-connectivity relationship whereas the traditional cross-correlation method was more sensitive to levels of CSF pTau₁₈₁ and cognitive status. With further refinement, resting-state connectivity and task-driven connectivity measures hold promise as non-invasive neuroimaging markers of Aβ and pTau burden in cognitively normal older adults.

Double-slit experiment with single wave-driven particles and its relation to quantum mechanics

In a thought-provoking paper, Couder and Fort [Phys. Rev. Lett. 97, 154101 (2006)] describe a version of the famous double-slit experiment performed with droplets bouncing on a vertically vibrated fluid surface. In the experiment, an interference pattern in the single-particle statistics is found even though it is possible to determine unambiguously which slit the walking droplet passes. Here we argue, however, that the single-particle statistics in such an experiment will be fundamentally different from the single-particle statistics of quantum mechanics. Quantum mechanical interference takes place between different classical paths with precise amplitude and phase relations. In the double-slit experiment with walking droplets, these relations are lost since one of the paths is singled out by the droplet. To support our conclusions, we have carried out our own double-slit experiment, and our results, in particular the long and variable slit passage times of the droplets, cast strong doubt on the feasibility of the interference claimed by Couder and Fort. To understand theoretically the limitations of wave-driven particle systems as analogs to quantum mechanics, we introduce a Schrödinger equation with a source term originating from a localized particle that generates a wave while being simultaneously guided by it. We show that the ensuing particle-wave dynamics can capture some characteristics of quantum mechanics such as orbital quantization. However, the particle-wave dynamics can not reproduce quantum mechanics in general, and we show that the single-particle statistics for our model in a double-slit experiment with an additional splitter plate differs qualitatively from that of quantum mechanics.

Quiet swimming at low Reynolds number

The stresslet provides a simple model of the flow created by a small, freely swimming and neutrally buoyant aquatic organism and shows that the far field fluid disturbance created by such an organism in general decays as one over distance squared. Here we discuss a quieter swimming mode that eliminates the stresslet component of the flow and leads to a faster spatial decay of the fluid disturbance described by a force quadrupole that decays as one over distance cubed. Motivated by recent experimental results on fluid disturbances due to small aquatic organisms, we demonstrate that a three-Stokeslet model of a swimming organism which uses breast stroke type kinematics is an example of such a quiet swimmer. We show that the fluid disturbance in both the near field and the far field is significantly reduced by appropriately arranging the propulsion apparatus, and we find that the far field power laws are valid surprisingly close to the organism. Finally, we discuss point force models as a general framework for hypothesis generation and experimental exploration of fluid mediated predator-prey interactions in the planktonic world.

Invading slugs (Arion vulgaris) can be vectors for Listeria monocytogenes

AIMS

Listeriosis is a frequent silage-associated disease in ruminants. The slugs Arion vulgaris are invaders in gardens, vegetable crops and meadows for silage production. Field and laboratory studies were conducted to clarify whether slugs could host Listeria monocytogenes and thereby constitute a threat to animal feed safety.

METHODS AND RESULTS

Selective culture of L. monocytogenes from 79 pooled slug samples (710 slugs) resulted in 43% positive, 16% with mean L. monocytogenes values of 405 CFU g(-1) slug tissues. Of 62 individual slugs cultured, 11% also tested positive from surface/mucus. Multilocus sequence typing analysis of 36 isolates from different slug pools identified 20 sequence types belonging to L. monocytogenes lineages I and II. Slugs fed ≅4·0 × 10(5)  CFUL. monocytogenes, excreted viable L. monocytogenes in faeces for up to 22 days. Excretion of L. monocytogenes decreased with time, although there were indications of a short enrichment period during the first 24 h.

CONCLUSIONS

Arion vulgaris may act as a vector for L. monocytogenes.

SIGNIFICANCE AND IMPACT OF THE STUDY

Highly slug-contaminated grass silage may pose a potential threat to animal feed safety.

Hydrodynamics and energetics of jumping copepod nauplii and copepodids

Within its life cycle, a copepod goes through drastic changes in size, shape and swimming mode. In particular, there is a stark difference between the early (nauplius) and later (copepodid) stages. Copepods inhabit an intermediate Reynolds number regime (between ~1 and 100) where both viscosity and inertia are potentially important, and the Reynolds number changes by an order of magnitude during growth. Thus we expect the life stage related changes experienced by a copepod to result in hydrodynamic and energetic differences, ultimately affecting the fitness. To quantify these differences, we measured the swimming kinematics and fluid flow around jumping Acartia tonsa at different stages of its life cycle, using particle image velocimetry and particle tracking velocimetry. We found that the flow structures around nauplii and copepodids are topologically different, with one and two vortex rings, respectively. Our measurements suggest that copepodids cover a larger distance compared to their body size in each jump and are also hydrodynamically quieter, as the flow disturbance they create attenuates faster with distance. Also, copepodids are energetically more efficient than nauplii, presumably due to the change in hydrodynamic regime accompanied with a well-adapted body form and swimming stroke.

Self-reported recurrent pain and medicine use behaviours among 15-year olds: results from the international study

BACKGROUND

There is considerable variation in adolescent pain prevalence across epidemiological studies, with limited information on pain-related behaviours among adolescents, including medicine use. The aims of this study were (1) to examine the prevalence of recurrent pain among 15-year-old adolescents internationally; (2) to investigate the association between recurrent pain and medicine use behaviours among boys and girls; and (3) to evaluate the consistency of these associations across countries.

METHODS

The World Health Organization (WHO) collaborative international Health Behaviour in School-aged Children 2009/2010 study collects data about self-reported aches and medicine use from 36,762 15-year-old adolescents from 22 countries/regions in Europe and the United States. Multi-level multivariate logistic regression, stratified by gender, was used to analyse the association between recurrent pain and medicine use for headache, stomachache, nervousness and difficulties in getting to sleep.

RESULTS

More than 30% of adolescents reported recurrent headache, almost 30% recurrent backache and approximately 20% recurrent stomachache. Although pain prevalence and medicine use for aches were much higher for girls, the association between pain and medicine use was similarly strong for both genders. Adolescents with recurrent pain are more likely to use medicines also for non-corresponding pain, nervousness and difficulties in getting to sleep. The association between recurrent pain and medicine use was consistent across countries despite large-country differences in the prevalence of recurrent pain and medicine use.

CONCLUSIONS

Recurrent pain in adolescence is common cross-nationally. Adolescents with recurrent pain are more likely to use medicine in general. Recurrent pain and medicine use should be addressed in adolescent health policies.

Comparison of twice refocused spin echo versus stimulated echo diffusion tensor imaging for tracking muscle fibers

PURPOSE

To compare the precision of measuring the pennation angle and fiber length in the vastus lateralis (VL) using two distinctly different diffusion tensor imaging (DTI) sequences.

MATERIALS AND METHODS

We imaged the thigh of 10 normal subjects on a 3T magnetic resonance (MR) imager with twice refocused spin echo (TRSE) and stimulated echo (STEAM) DTI-MRI techniques. Both techniques took the same total acquisition time and employed the same diffusion weighting and gradient directions. Using the diffusion tensor images produced by each sequence, muscle fiber bundles were tracked from the aponeurosis by following the first eigenvector of the diffusion tensor. From these tracks we calculated the pennation angle and fiber length.

RESULTS

The STEAM acquisition resulted in significantly higher signal-to-noise ratio (SNR), lower apparent diffusion coefficient (ADC), higher fractional anisotropy (FA) values, and longer fibers than TRSE. Although no difference in the pennation angle between the two acquisitions was found, the TRSE sequence had a significantly greater within-subject dispersion in the pennation angle of tracked fibers, which may indicate a reduction in the coherence of fiber bundles.

CONCLUSION

DTI of muscle using a STEAM acquisition resulted in significant improvements in the SNR and FA, resulting in tracking a larger number of muscle fiber bundles over longer distances and with less within-subject dispersion.

Cortical glutamate levels decrease in a non-human primate model of dopamine deficiency

While Parkinson's disease is the result of dopaminergic dysfunction of the nigrostriatal system, the clinical manifestations of Parkinson's disease are brought about by alterations in multiple neural components, including cortical areas. We examined how 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration affected extracellular cortical glutamate levels by comparing glutamate levels in normal and MPTP-lesioned nonhuman primates (Macaca mulatta). Extracellular glutamate levels were measured using glutamate microelectrode biosensors. Unilateral MPTP-administration rendered the animals with hemiparkinsonian symptoms, including dopaminergic deficiencies in the substantia nigra and the premotor and motor cortices, and with statistically significant decreases in basal glutamate levels in the primary motor cortex on the side ipsilateral to the MPTP-lesion. These results suggest that the functional changes of the glutamatergic system, especially in the motor cortex, in models of Parkinson's disease could provide important insights into the mechanisms of this disease.