Balance Reactions Research Articles

Adaptation of balance reactions following forward perturbations in people with joint hypermobility syndrome

BackgroundJoint Hypermobility Syndrome (JHS) is a Heritable Disorder of Connective tissue characterised by joint laxity and chronic widespread arthralgia. People with JHS exhibit a range of other symptoms including balance problems. To explore balance further, the objective of this study is to compare responses to forward perturbations between three groups; people who are hypermobile with (JHS) and without symptoms and people with normal flexibility.MethodsTwenty-one participants with JHS, 23 participants with Generalised Joint Hypermobility (GJH) and 22 participants who have normal flexibility (NF) stood on a platform that performed 6 sequential, sudden forward perturbations (the platform moved to the anterior to the participant). Electromyographic outcomes (EMG) and kinematics for the lower limbs were recorded using a Vicon motion capture system. Within and between group comparisons were made using Kruskal Wallis tests.ResultsThere were no significant differences between groups in muscle onset latency. At the 1st perturbation the group with JHS had significantly longer time-to-peak amplitude than the NF group in tibialis anterior, vastus medialis, rectus femoris, vastus lateralis, and than the GJH group in the gluteus medius. The JHS group showed significantly higher cumulative joint angle (CA) than the NF group in the hip and knee at the 1st and 2nd and 6th perturbation, and in the ankle at the 2nd perturbation. Participants with JHS had significantly higher CA than the GJH group at the in the hip and knee in the 1st and 2nd perturbation. There were no significant differences in TTR.ConclusionsThe JHS group were able to normalise the timing of their muscular response in relation to control groups. They were less able to normalise joint CA, which may be indicative of impaired balance control and strength, resulting in reduced stability.

IDENTIFYING RELEVANT PATHWAYS AND BIOMARKERS IN CROHN’S DISEASE USING CONTEXTUALIZED METABOLIC NETWORK MODEL

Abstract Background Candidate markers for Crohn’s Disease (CD) may be identified via gene expression-based construction of metabolic networks (MN). These can computationally describe gene-protein-reaction associations for entire tissues and also predict the flux of reactions (rate of turnover of specific molecules via a metabolic pathway). Recon3D is the most comprehensive human MN to date. We used publicly available CD transcriptomic data along with Recon3D to identify metabolites as potential diagnostic and prognostic biomarkers. Methods Terminal ileal gene expression profiles (36,372 genes; 218 CD. 42 controls) from the RISK cohort (Risk Stratification and Identification of Immunogenetic and Microbial Markers of Rapid Disease Progression in Children with Crohn’s Disease) and their transcriptomic abundances were used. Recon3D was pruned to only include RISK dataset transcripts which determined metabolic reaction linkage with transcriptionally active genes. Flux balance analysis (FBA) was then run using RiPTiDe with context specific transcriptomic data to further constrain genes (Figure 1). RiPTiDe was independently run on transcriptomic data from both CD and controls. From the pruned and constricted MN obtained, reactions were extracted for further analysis. Results After applying the necessary constraints to modify Recon3D, 527 CD and 537 control reactions were obtained. Reaction comparison with a publicly available list of healthy small intestinal epithelial reactions (n=1282) showed an overlap of 80 CD and 84 control reactions. These were then further grouped based on their metabolic pathways. RiPTiDe identified context specific metabolic pathway activity without supervision and the percentage of forward, backward, and balanced reactions for each metabolic pathway (Figure 2). The metabolite concentrations in the small intestine was altered among CD patients. Notably, the citric acid cycle and malate-aspartate shuttle were affected, highlighting changes in mitochondrial metabolic pathways. This is illustrated by changes in the number of reactions at equilibrium between CD and control. Conclusions The results are relevant as cytosolic acetyl-CoA is needed for fatty acid synthesis and is obtained by removing citrate from the citric acid cycle. An intermediate removal from the cycle has significant cataplerotic effects. The malate-aspartate shuttle also allows electrons to move across the impermeable membrane in the mitochondria (fatty acid synthesis location). These findings are reported by previously published studies where gene expression for fatty acid synthesis is altered in CD patients along with mitochondrial metabolic pathway changes, resulting in altered cell homeostasis. In-depth analysis is currently underway with our work supporting the utility of potential metabolic biomarkers for CD diagnosis, management and improved care.

The Effects of Bicycle Simulator Training on Anticipatory and Compensatory Postural Control in Older Adults: Study Protocol for a Single-Blind Randomized Controlled Trial.

Background: Falls are the leading cause of fatal and non-fatal injuries among older adults. Perturbation-Based-Balance Training (PBBT) is a promising approach to reduce fall rates by improving reactive balance responses. PBBT programs are designed for older adults who are able to stand and walk on a motorized treadmill independently. However, frail older adults, whose fall rates are higher, may not have this ability and they cannot participate. Thus, there is a critical need for innovative perturbation exercise programs to improve reactive balance and reduce the fall risks among older adults in a wider range of functioning. Trunk and arms are highly involved in reactive balance reactions. We aim to investigate whether an alternative PBBT program that provides perturbations during hands-free bicycling in a sitting position, geared to improve trunk and arm reactive responses, can be transferred to reduce fall risks and improve balance function among pre-frail older adults.Methods: In a single-blinded randomized-controlled trial, 68 community-dwelling pre-frail older adults are randomly allocated into two intervention groups. The experimental group receives 24-PBBT sessions over 12-weeks that include self-induced internal and machine-induced external unannounced perturbations of balance during hands-free pedaling on a bicycle-simulator system, in combination with cognitive dual-tasks. The control group receives 24 pedaling sessions over 12-weeks by the same bicycle-simulator system under the same cognitive dual-tasks, but without balance perturbations. Participants' reactive and proactive balance functions and gait function are assessed before and after the 12-week intervention period (e.g., balance reactive responses and strategies, voluntary step execution test, postural stability in upright standing, Berg Balance Test, Six-meter walk test, as well as late life function and fear of falling questionnaires).Discussion: This research addresses two key issues in relation to balance re-training: (1) generalization of balance skills acquired through exposure to postural perturbations in a sitting position investigating the ability of pre-frail older adults to improve reactive and proactive balance responses in standing and walking, and (2) the individualization of perturbation training to older adults' neuromotor capacities in order to optimize training responses and their applicability to real-life challenges.Clinical Trial Registration: www.clinicaltrials.gov, NCT03636672 / BARZI0104; Registered: July 22, 2018; Enrolment of the first participant March: 1, 2019. See Supplementary File.

Influence of a light touch reference on cutaneous reflexes from the hand during standing.

Light touch of a stable reference reduces sway during standing. However, unexpected displacement of a light touch reference leads to short-latency reactions in ankle muscles consistent with a balance reaction, that are replaced by responses in arm muscles on subsequent trials. We anticipated that the excitability of sensorimotor pathways arising from finger cutaneous afferents would reflect these changes in behavior. We hypothesized that (1) interlimb cutaneous reflexes in muscles of the ipsilateral leg, derived from median nerve (MED) stimulation would be facilitated when touch was stable, but reduced when touch was unreliable, (2) intralimb MED reflexes in muscles of the homonymous arm would be facilitated when touch was unreliable and participants tracked the touch reference with arm movements, and (3) radial nerve (RAD) evoked reflexes would be unaffected, given that the RAD innervation territory is not involved in the light touch task. Cutaneous reflexes were evoked using a transcutaneous train of pulses (5 × 1.0ms square-wave pulses; 300Hz) and recorded using electromyography of muscles of the ipsilateral arm and leg. As hypothesized, interlimb MED reflexes recorded in soleus (SOL) were larger when touching the stable reference (mean ± SD % MVC; 4.78 ± 1.57) than when not touching a reference (1.00 ± 1.05) or when touching an unstable reference (1.07 ± 1.16). In addition, intralimb MED reflexes in anterior deltoid (AD) were larger when touching an unstable reference (4.50 ± 1.31), compared to touching a stable reference (1.34 ± 1.01) or not touching (1.50 ± 1.00). In contrast, interlimb RAD reflexes in SOL were larger when not touching (4.29 ± 4.34), compared with touching a stable (1.14 ± 1.84) or unstable reference (3.11 ± 4.15). These findings indicate that cutaneous reflexes from the hand are scaled with a rapid change in motor behavior when a touch reference becomes unstable, suggesting that spinal sensorimotor pathways are functionally reweighted based in part upon the reliability of tactile inputs.

The influence of water\u2013rock interactions on household well water in an area of high prevalence chronic kidney disease of unknown aetiology (CKDu)

Poor drinking water quality in household wells is hypothesised as being a potential contributor to the high prevalence of chronic kidney disease of uncertain aetiology (CKDu) among the farming communities of the Medawachchiya area, Anuradhapura, Sri Lanka. One of the natural processes that can affect water quality is the dissolution of minerals contained within an aquifer by water–rock interactions (WRIs). Here we present a comprehensive assessment of WRIs and their influence on the water chemistry in household wells and spring waters in the Medawachchiya area by combining measurements of environmental isotopes, such as strontium, lithium and stable carbon isotopes and inorganic chemistry parameters, and modelling geochemical mass balance reactions between rainfall and groundwater samples. Our results reveal the presence of strontium, dissolved from both silicate and carbonate minerals, with high isotopic (87Sr/86Sr) ratios of up to 0.7316. Geochemical mass balance modelling and prior 87Sr/86Sr studies on the Wanni Complex bedrock suggest these strontium values may be the result of biotite dissolution. We also identify lithium and uranium contributed from the dissolution of silicates, albeit at concentrations too low to constitute a known health risk. In contrast, the levels of magnesium and calcium in our samples are high and demonstrate that, despite the felsic bedrock, well water chemistry in the Medawachchiya area is dominated by carbonate dissolution.

Bistable equation with discontinuous density dependent diffusion with degenerations and singularities

In this article we introduce rather general notion of the stationary solution of the bistable equation which allows to treat discontinuous density dependent diffusion term with singularities and degenerations, as well as degenerate or non-Lipschitz balanced bistable reaction term. We prove the existence of new-type solutions which do not occur in case of the ``classical'' setting of the bistable equation. In the case of the power-type behavior of the diffusion and bistable reaction terms near the equilibria we provide detailed asymptotic analysis of the corresponding solutions and illustrate the lack of smoothness due to the discontinuous diffusion.

РЕГУЛЯТОРНЫЕ ОСОБЕННОСТИ АДАПТАЦИИ КАРДИОГЕМОДИНАМИКИ К НАГРУЗКАМ РАЗЛИЧНОЙ МОДАЛЬНОСТИ У БОКСЁРОВ

Ensuring a high level of fitness is directly related to the improvement of regulatory mechanisms in response to external stimuli. The leading role in the complex neurodynamics underlying the reactions of balance, orientation in space and coordination of movements in the dynamic conditions of boxing belongs to the vestibular analyzer and the complex system of unconditional vestibulosomatic and vestibulovegetative reflexes. Under the action of vestibular stimuli during training in boxers, the participation of vegetative components in the response of the body increases sharply and can lead to the appearance of a stress response. In qualified boxers with different levels of vestibular stability, significant differences in functional reserves were revealed, quantitatively expressed by the coefficient of vestibular and vegetative adaptability, which can be used to rank boxers according to the degree of their adaptive capabilities. Given the changes in the mechanisms of vegetative regulation in contingents with different levels of vestibular stability, the question arises of a quantitative assessment of the qualitative effects of the vestibular apparatus on the vegetative support of activity. Methods of measuring vegetative regulation reserves in order to analyze the effectiveness of the training process are insufficiently covered in literary sources. In this regard, the aim of our study was to identify the regulatory features of the adaptation of cardiohemodynamics to loads of different modality in boxers and the possibility of using the coefficient of vegetative-vestibular adaptivity (Cvva) in the quantitative assessment of regulatory reserves. It was revealed that the level of adaptation of boxers to physical and vestibular loads is directly related to the vegetative provision of cardiohemodynamics when performing loads of different modality and depends on the level of qualification or training experience, as well as the level of general physical performance. In boxers with different levels of vestibular stability, significant differences in functional reserves were revealed, quantitatively expressed by the coefficient of vestibular and vegetative adaptability. In qualified athletes at rest, the indices of heart rate and double work were significantly lower with an increase in the ability to perform physical load, and the values of VO2 max in experienced boxers exceeded the values of beginner boxers by 19.2 % (p<0.01). Reflecting the reduced reserves of adaptation to vestibular load, the coefficient of stability in the group of novice athletes was twice significantly higher than the data in the group of qualified boxers, and with a decrease in the level of vestibular stability in boxers, the coefficient of vegetative and vestibular adaptability also increased. Thus, both the energy and regulatory components form the adaptation of boxers to training loads, the integral indicator of which can be the mechanisms of regulation of cardiac activity.

Multiscale Cross-Domain Thermochemical Knowledge-Graph.

In this paper, we develop a set of software agents which improve a knowledge-graph containing thermodynamic data of chemical species by means of quantum chemical calculations and error-canceling balanced reactions. The knowledge-graph represents species-associated information by making use of the principles of linked data, as employed in the Semantic Web, where concepts correspond to vertices and relationships between the concepts correspond to edges of the graph. We implement this representation by means of ontologies, which formalize the definition of concepts and their relationships, as a critical step to achieve interoperability between heterogeneous data formats and software. The agents, which conduct quantum chemical calculations and derive the estimates of standard enthalpies of formation, update the knowledge-graph with newly obtained results, improving data values, and adding nodes and connections between them. A key distinguishing feature of our approach is that it extends an existing, general-purpose knowledge-graph, called J-Park Simulator (http://theworldavatar.com), and its ecosystem of autonomous agents, thus enabling seamless cross-domain applications in wider contexts. To this end, we demonstrate how quantum calculations can directly affect the atmospheric dispersion of pollutants in an industrial emission use-case.

A Novel Framework for Capacity Analysis of Diffusion-Based Molecular Communication Incorporating Chemical Reactions

In recent years, molecular communication (MC) is considered as a transformative paradigm in the communication theory and a promising solution to future nanoscale communication networks. In this article, a novel framework is introduced for diffusion-based MC and is shown how its capacity is impacted by the effects of chemical reactions which were neglected in the existing literature. Particularly, the chemical reactions corresponding to complex balanced chemical reaction networks are studied in this work. With an information-theoretic approach, the capacity is introduced where the effects of chemical reactions are taken into account. Then, the individual entropy derivations are addressed where the chemical reactions at the transmitter are considered with the chemical reaction network theory. Finally, the mutual information is derived based on these entropy derivations and the analytical capacity expressions are introduced accordingly. Numerical results exhibit the interactions between different parameters and show that the capacity actually decreases when the effects of chemical reactions are considered, implying that the capacity derived without chemical reactions was overestimated in previous studies. Consequently, the proposed framework analyzes the fundamental limits of diffusion-based MC and provides a more realistic capacity derivation comprising limitations imposed by chemical reactions, hence applicable to various more realistic MC scenarios.

Biochemical interaction of salt sensitivity: a key player for the development of essential hypertension.

Worldwide, more than 1 billion people have elevated blood pressure, with up to 45% of adults affected by the disease.In 2016 the global health study report on patients from 67 countries was released in Lancet, which identified hypertension as the world's leading cause for death and disability-adjusted years since 1990. This paper aims to analyze the pathophysiological connection between hemodynamic inflammatory reactions through sodium balance, salt sensitivity, and potential pathophysiological reactions. Besides, we explore how sodium consumption enhances the expression of transient receptor potential channel 3 (TrpC3) mRNA and facilitates the release of calcium inside immune cell groups, together with elevated blood pressure in essential hypertensive patients.

A Prospective Cohort Study of Muscular and Performance Fitness and Incident Glaucoma: The Niigata Wellness Study.

To examine the association between muscular and performance fitness (MPF) and the incidence of glaucoma. A total of 27,051 glaucoma-free participants aged 20-87years underwent physical fitness tests between April 2001 and March 2002. The MPF index was calculated using an age- and sex-specific summed z-score from grip strength, vertical jump, single-leg balance, forward bending, and whole-body reaction time. The participants were divided into quartiles according to the MPF index and each physical fitness test. Participants were followed up for the development of glaucoma, which was defined based on physician-diagnosed glaucoma at an annual health examination between April 2002 and March 2008. Hazard ratios for the incidence of glaucoma were estimated using Cox proportional hazards models. During follow-up, 303 participants developed glaucoma. Compared with the lowest MPF index group, hazard ratio (95% confidence interval) of developing glaucoma was 0.64 (0.46-0.89) for the highest MPF index group (P for trend = .001). Vertical jump and whole-body reaction time were associated with incident glaucoma (P for trend = .01 and <.001, respectively). There were no associations between the other physical fitness tests and the incidence of glaucoma. Higher MPF is associated with lower incidence of glaucoma.

On a Periodic Inner Layer in the Reaction–Diffusion Problem with a Modular Cubic Source

The article studies a singularly perturbed periodic problem for the parabolic reaction–diffusion equation in the case of a discontinuous source: a nonlinearity describing the reaction (interaction). The case of the existence of an inner transition layer under conditions of an unbalanced and a balanced reaction is considered. An asymptotic approximation is constructed, and the asymptotic Lyapunov stability of periodic solutions in each of the cases is investigated. To prove the existence of a solution and its asymptotic stability, the asymptotic method of differential inequalities is used. The theoretical result is illustrated by an example and numerical calculations.

Metastable patterns for a reaction-diffusion model with mean curvature-type diffusion

Reaction-diffusion equations are widely used to describe a variety of phenomena such as pattern formation and front propagation in biological, chemical and physical systems. In the one-dimensional model with a balanced bistable reaction function, it is well-known that there is persistence of metastable patterns for an exponentially long time, i.e. a time proportional to exp⁡(C/ε) where C,ε are strictly positive constants and ε2 is the diffusion coefficient. In this paper, we extend such results to the case when the linear diffusion flux is substituted by the mean curvature operator both in Euclidean and Lorentz–Minkowski spaces. More precisely, for both models, we prove existence of metastable states which maintain a transition layer structure for an exponentially long time and we show that the speed of the layers is exponentially small. Numerical simulations, which confirm the analytical results, are also provided.

A comprehensive study on the gelation process of silica gels from sodium silicate

The sol-gel route via sodium silicate precursor is known as a practical synthesis method to prepare silica gels in a cost effective way. In the current research, rheological properties of the synthesized silica gels were investigated at different pH values. The gelation time (tgel) was determined from the rheological measurements at different frequencies of 0.1, 0.3 and 0.5 Hz. The results were analyzed using rheological equations of state and the concept of the gelation point was discussed. The results revealed that tgel increases by increasing the pH value. Moreover, it was proved that the fractal value (df) is dependent on the pH value. The relaxation exponent (Δ) value was measured as 0 < Δ < 1/2, which shows that the gel system follows the non-stoichiometrically balanced reactions. Finally, it was shown that the gelation process is divided into three stages, namely, induction, gelation and over curing. The results revealed that by increasing the pH value, stage I is extended while stage II is diminished.

A Prospective Cohort Study of Muscular and Performance Fitness and Risk of Hearing Loss: The Niigata Wellness Study

BackgroundSeveral cross-sectional studies have linked higher physical fitness with better hearing sensitivity but have not established a causal relation; none have used a prospective design that is less susceptible to bias. We used a prospective cohort study to investigate the association between muscular and performance fitness and the incidence of hearing loss. MethodsA total of 21,907 participants without hearing loss received physical fitness assessments between April 2001 and March 2002. Muscular and performance fitness index, an age- and sex-specific summed z-score based on grip strength, vertical jump height, single-leg balance, forward bending, and whole-body reaction time was calculated. Participants were classified into quartiles according to the muscular and performance fitness index and each physical fitness test. They were followed up for the development of hearing loss, assessed by pure-tone audiometry at annual health examinations between April 2002 and March 2008. Hazard ratios and 95% confidence intervals for hearing loss incidence were estimated using Cox proportional hazards regression models. ResultsDuring follow-up, 2765 participants developed hearing loss. The hazard ratios (95% confidence intervals) for developing hearing loss across the muscular and performance fitness index quartiles (lowest to highest) were 1.00 (reference), 0.88 (0.79-0.97), 0.83 (0.75-0.93), and 0.79 (0.71-0.88) (Ptrend <.001). Among the various physical fitness components, a clear dose-response association with hearing loss incidence was observed for vertical jump height and single-leg balance (Ptrend <.001 for both). ConclusionHigher muscular and performance fitness is associated with a lower incidence of hearing loss.

Quantifying Segmental Contributions to Center-of-Mass Motion During Dynamic Continuous Support Surface Perturbations Using Simplified Estimation Models.

Investigating balance reactions following continuous, multidirectional, support surface perturbations is essential for improving our understanding of balance control in moving environments. Segmental motions are often incorporated into rapid balance reactions following external perturbations to balance, although the effects of these motions during complex, continuous perturbations have not been assessed. This study aimed to quantify the contributions of body segments (ie,trunk, head, upper extremity, and lower extremity) to the control of center-of-mass (COM) movement during continuous, multidirectional, support surface perturbations. Three-dimensional, whole-body kinematics were captured while 10 participants experienced 5minutes of perturbations. Anteroposterior, mediolateral, and vertical COM position and velocity were calculated using a full-body model and 7 models with reduced numbers of segments, which were compared with the full-body model. With removal of body segments, errors relative to the full-body model increased, while relationship strength decreased. The inclusion of body segments appeared to affect COM measures, particularly COM velocity. Findings suggest that the body segments may provide a means of improving the control of COM motion, primarily its velocity, during continuous, multidirectional perturbations, and constitute a step toward improving our understanding of how the limbs contribute to balance control in moving environments.

Assessment of dynamic balancing responses following perturbations during slow walking in relation to clinical outcome measures for high-functioning post-stroke subjects

BackgroundGenerating appropriate balancing reactions in response to unexpected loss of balance during walking is important to prevent falls. The purpose of this study was to assess dynamic balancing responses following pushes to the pelvis in groups of post-stroke and healthy subjects.MethodsForty-one post-stroke subjects and forty-three healthy subjects participated in the study. Dynamic balancing responses to perturbations triggered at heel strike of the left or right leg, directed in the forward, backward, inward and outward directions during slow treadmill walking were assessed. Responses of the healthy group provided reference values used to classify responses of the post-stroke group into two subgroups; one within the reference responses (“inside” subgroup) and the other that falls out (“outside” subgroup). A battery of selected clinical outcome measures (6-Minute Walk Test, 10-Meter Walk Test, Timed-Up-and-Go test, Four Square Step Test, Functional Gait Assessment, Functional Independence Measure and One-legged stance test) was additionally assessed in the post-stroke group.ResultsThe “inside” subgroup of post-stroke subjects was able to appropriately modulate centre-of-pressure and ground-reaction-force both under the impaired and non-impaired leg in response to perturbations. The “outside” subgroup of post-stroke subjects showed limited modulation of centre-of-pressure and ground-reaction-force under the impaired leg; instead stepping strategy was used in which the non-impaired leg was placed such as to make a longer step (forward perturbation), to make a shorter step (backward perturbation) or to make a cross-step (outward perturbation). Consequently, peak centre-of-mass displacements following perturbations were significantly higher in the “outside” subgroup compared to the “inside” subgroup. Responses in both subgroups following inward perturbations did not differ. Majority of clinical outcome measures moderately correlated with the peak centre-of-mass displacements for forward perturbations and exhibited weak correlations for other perturbation directions.ConclusionsSubstantial number of post-stroke subjects, that were considered to be independent walkers, have reduced capabilities to execute appropriate balancing responses following perturbations commencing on the hemiparetic leg and may thus benefit from perturbation-based training. Timed-Up-and-Go and Functional Independence Measure tests may provide an indication on the abilities of each subject to counteract unexpected loss of balance. However, a reliable assessment should be done through perturbation-based measures.

THE EFFECT OF 8 WEEKS FOLK DANCES TRAINING ON BALANCE REACTION TIME AND RHYTHM SESSION OF UNIVERSITY STUDENTS

The aim of this study was to investigate the effects of 8-week folk dance education on balance, reaction time and rhythm session of university students. A total of 40 students aged 19-23 years were included in the study. Participants were divided into two groups. 20 students of them were determined as control group. The other groups performed basic folk dance training was given to the students as ninety minutes three days a week. Age, height, weight, balance, visual and auditory reaction time and rhythm session were measured in groups one day before and one day after the study. Isokinetic balance test was performed for balance measurement. The normal distribution test of the data obtained from the study was carried out with Kolmogorov-Smirnov and Shapiro Wilk tests. The data showed normal distribution according to the groups (p> 0.05). Paired t test was used to compare the pre-test and post-test values of auditory reaction time, visual reaction time, api, body weight, osi and mli. McNemar test was used to analyze the pre-test and post-test of correlation between rhythm perception and performing skill scale. Statistical results were evaluated at 95% confidence interval and p <0.05 significance level. It could be concluded that eight weeks folk dance education can improve the balance, reaction time and rhythm session and have positive effects of university students. Article visualizations:

Probiotics: an Antibiotic Replacement Strategy for Healthy Broilers and Productive Rearing.

Pathogens develop resistance to antibiotics at a rate much faster than the discovery of new antimicrobial compounds. Reports of multidrug-resistant bacteria isolated from broilers, and the possibility that these strains may spread diseases amongst humans, prompted many European countries to ban the inclusion of antibiotics in feed. Probiotics added to broiler feed controlled a number of bacterial infections. A combination of Enterococcus faecium, Pediococcus acidilactici, Bacillus animalis, Lactobacillus salivarius and Lactobacillus reuteri decreased the colonisation of Campylobacter jejuni and Salmonella Enteritidis in the gastro-intestinal tract (GIT) of broilers, whereas Bacillus subtilis improved feed conversion, intestinal morphology, stimulated the immune system and inhibited the colonisation of Campylobacter jejuni, Escherichia coli and Salmonella Minnesota. Lactobacillus salivarius and Pediococcus parvulus improved weight gain, bone characteristics, intestinal morphology and immune response, and decreased the colonisation of S. Enteritidis. Lactobacillus crispatus, L. salivarius, Lactobacillus gallinarum, Lactobacillus johnsonii, Enterococcus faecalis and Bacillus amyloliquefaciens decreased the Salmonella count and led to an increase in lysozyme and T lymphocytes. Probiotics may also improve feed digestion through production of phytases, lipases, amylases and proteases or stimulate the GIT to secrete digestive enzymes. Some strains increase the nutritional value of feed by production of vitamins, exopolysaccharides and antioxidants. Bacteriocins, if produced, regulate pathogen numbers in the GIT and keep pro-inflammatory and anti-inflammatory reactions in balance.

Persistence of Delayed Complex Balanced Chemical Reaction Networks

In this article, we mainly focus on the persistence of delayed complex balanced systems. We first give the ω-limit set theorem for this kind of system which says that ω-limit set can be the single constant positive equilibrium or the set of constant equilibria on the boundaries. In addition, we derive several sufficient conditions to diagnose the persistence of delayed complex balanced chemical reaction network systems equipped with mass-action kinetics based on the situation of the boundary of stoichiometric compatibility class. Then, we can directly obtain that delayed complex balanced systems with two-dimensional stoichiometric subspace are persistent. Furthermore, we prove the abovementioned systems are globally asymptotically stable at the corresponding positive equilibrium if the trajectory starts from a positive initial function. We illustrate the analysis by two numerical examples.