2,109 research outputs found
Glucagon-like peptide-2 modulates neurally evoked mucosal chloride secretion in guinea pig small intestine in vitro
No full textGlucagon-like peptide-2 (GLP-2) is
an important neuroendocrine peptide in intestinal physiology. It influences
digestion, absorption, epithelial growth, motility, and blood
flow. We studied involvement of GLP-2 in intestinal mucosal secretory
behavior. Submucosal-mucosal preparations from guinea pig
ileum were mounted in Ussing chambers for measurement of shortcircuit
current (Isc) as a surrogate for chloride secretion. GLP-2 action
on neuronal release of acetylcholine was determined with ELISA.
Enteric neuronal expression of the GLP-2 receptor (GLP-2R) was
studied with immunohistochemical methods. Application of GLP-2
(0.1–100 nM) to the serosal or mucosal side of the preparations
evoked no change in baseline Isc and did not alter transepithelial ionic
conductance. Transmural electrical field stimulation (EFS) evoked
characteristic biphasic increases in Isc, with an initially rapid rising
phase followed by a sustained phase. Application of GLP-2 reduced
the EFS-evoked biphasic responses in a concentration-dependent
manner. The GLP-2R antagonist GLP-2-(3-33) significantly reversed
suppression of the EFS-evoked responses by GLP-2. Tetrodotoxin,
scopolamine, and hexamethonium, but not vasoactive intestinal peptide
type 1 receptor (VPAC1) antagonist abolished or reduced to near
zero the EFS-evoked responses. GLP-2 suppressed EFS-evoked acetylcholine
release as measured by ELISA. Pretreatment with GLP-2-
(3-33) offset this action of GLP-2. In the submucosal plexus, GLP-2R
immunoreactivity (-IR) was expressed in choline acetyltransferase-IR
neurons, somatostatin-IR neurons, neuropeptide Y-IR neurons, and
vasoactive intestinal peptide-IR neurons. We conclude that submucosal
neurons in the guinea pig ileum express GLP-2R. Activation of
GLP-2R decreases neuronally evoked epithelial chloride secretion by
suppressing acetylcholine release from secretomotor neurons
Ventricular dyssynchrony assessment with equilibrium radionuclide angiography phase analysis predicts outcome after cardiac resynchronization therapy
No full textConsideration of Interference Correlation Properties in a JD-CDMA Mobile Radio System with Coherent Receiver Antenna Diversity
No full textIn code division multiple access (CDMA) mobile radio systems, both intersymbol interference and multiple access interference arise which can be combatted by using Joint Detection (JD) techniques, to reduce the degradation in performance resulting from time variance, coherent receiver antenna diversity (CRAD) can be used. The application of JD techniques offers the possibility to exploit the knowledge of noise covariances at the receiver. If only intercell (cochannel) interference is considered, the noise covariances in the uplink receiver of a multiple receiver antenna CDMA mobile radio system depend mainly on the directions of arrival (DOAs) of the interfering signals and the receiver antenna placement. Therefore, if the interferer DOAs are known at the base station, these covariances could be estimated. In this thesis, a realistic model of the uplink of a JD CDMA mobile radio system with CRAD is described in which the above mentioned interference cancelling method is used. Simulation results according to this model are given and evaluated.Applied SciencesElectrical EngineeringTelecommunications and Traffic Control Systems Grou
Dairy farmers’ perceptions toward the implementation of on-farm Johne’s disease prevention and control strategies
No full textmplementation of specific management strategies on dairy farms is currently the most effective way to reduce the prevalence of Johne’s disease (JD), an infectious chronic enteritis of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). However, dairy farmers often fail to implement recommended strategies. The objective of this study was to assess perceptions of farmers participating in a JD prevention and control program toward recommended practices, and explore factors that influence whether or not a farmer adopts risk-reducing measures for MAP transmission. Semi-structured interviews were conducted with 25 dairy farmers enrolled in a voluntary JD control program in Alberta, Canada. Principles of classical grounded theory were used for participant selection, interviewing, and data analysis. Additionally, demographic data and MAP infection status were collected and analyzed using quantitative questionnaires and the JD control program database. Farmers’ perceptions were distinguished according to 2 main categories: first, their belief in the importance of JD, and second, their belief in recommended JD prevention and control strategies. Based on these categories, farmers were classified into 4 groups: proactivists, disillusionists, deniers, and unconcerned. The first 2 groups believed in the importance of JD, and proactivists and unconcerned believed in proposed JD prevention and control measures. Groups that regarded JD as important had better knowledge about best strategies to reduce MAP transmission and had more JD risk assessments conducted on their farm. Although not quantified, it also appeared that these groups had more JD prevention and control practices in place. However, often JD was not perceived as a problem in the herd and generally farmers did not regard JD control as a “hot topic” in communications with their herd veterinarian and other farmers. Recommendations regarding how to communicate with farmers and motivate various groups of farmers according to their specific perceptions were provided to optimize adoption of JD prevention and control measures and thereby increase success of voluntary JD control programs
POSTNATAL MATURATION OF SEROTONIN SIGNALING SYSTEM IN MOUSE DUODENUM
No full textBACKGROUND AND AIMS: A plethora of study in animal neurodevelopmental models demonstrate that in central nervous system (CNS) temporal differences occur in the maturation of different neurotransmitter systems (Goldman-Rakic & Brown, 1982, Ehrlich et al., 2013). Although significant advances have been made in understanding the modifications in CNS, only primarily descriptive studies about the changes taking place in enteric nervous system (ENS), main regulator of gastrointestinal (GI) functions, have been underway. As the other organ systems, digestive system is still developing and maturing after birth and thus it is possible to speculate that the changes in the chemical coding of ENS may occur with development. Studies about the postnatal maturation of enteric neurotransmitter systems could help to assess why drugs, able to modulate GI functions, may have diverse clinical effects at different ages. Serotonin (5-hydroxytryptamine or 5-HT), is an important enteric neurotransmitter in the GI tract (Gershon 2013). Neuronally-released 5-HT plays a crucial role in the regulation of several physiological functions, such as motility, secretion and visceral sensitivity (Gershon 2013; Baker 2005; Beattie & Smith 2008). Since serotoninergic system appears to undergo dramatic postnatal changes in CNS, in this study we aimed to assess if, in the enteric nervous system, 5-HT signalling may undergoes to postnatal maturation, using mouse duodenum as model. METHODS: Using a pharmacological approach, we examined,
in vitro
, the role of 5-HT signalling in the regulation of duodenal contractility in neonatal mice (2 days old) compared to the adults. RESULTS: 5-HT induced in both duodenal preparations a concentration-dependent muscular contraction, being its efficacy greater in duodenum from neonatal mice. Serotoninergic response was mediated by activation of muscular 5-HT receptors, antagonized by methysergide, nontarget 5-HT receptor antagonist, and of neural 5-HT
3
receptors, antagonized by ondasetron. In both preparations there was a major sensitivity of the postjunctional
vs
prejunctional receptors. In duodenum from neonatal mice pretreatment with atropine, muscarinic receptor antagonist, abolished neurally evoked serotoninergic contraction. Instead, in adult duodenum, in the presence of atropine, the response to 5-HT was converted in a muscular relaxation, abolished by L-NAME, a nitric oxide (NO) synthase inhibitor. L-NAME
per se
potentiated the 5-HT cholinergic contractile effects in adult preparations. Instead, L-NAME was ineffective in neonatal preparations. CONCLUSIONS: In mouse duodenum, 5-HT signaling undergoes to age-related changes. In both preparations, 5-HT induces contractile effects via activation of muscular receptors and neural 5-HT
3
receptors on cholinergic nerves to induce acetylcholine release. Contractile response to 5HT is detectable from birth, but there is a gradual decrease in efficacy with age and a concurrent recruitment of inhibitory nitrergic nerves. These changes may contribute to gut motility adaptation to cope with the dietary changes at weaning.
REFERENCES
Beattie DT, Smith JA. Serotonin pharmacology in the gastrointestinal tract: a review. Naunyn Schmiedebergs Arch Pharmacol. (2008) ;377:181-203. Ehrlich DE, Ryan SJ, Hazra R, Guo JD, Rainnie DG. Postnatal maturation of GABAergic transmission in the rat basolateral amygdale J Neurophysiol.; (2013) 110:926-41. Gershon MD. 5-Hydroxytryptamine (serotonin) in the gastrointestinal tract. Curr Opin Endocrinol Diabetes Obes. (2013) 20:14-21. Goldman-Rakic P, Brown R Postnatal development of monoamine content and synthesis in the cerebral cortex of rhesus monkeys. Dev Brain Res (1982) 4:339
–
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Knowledge gaps that hamper prevention and control of Mycobacterium avium subspecies paratuberculosis infection
No full textIn the last decades, many regional and country‐wide control programmes for Johne's disease (JD ) were developed due to associated economic losses, or because of a possible association with Crohn's disease. These control programmes were often not successful, partly because management protocols were not followed, including the introduction of infected replacement cattle, because tests to identify infected animals were unreliable, and uptake by farmers was not high enough because of a perceived low return on investment. In the absence of a cure or effective commercial vaccines, control of JD is currently primarily based on herd management strategies to avoid infection of cattle and restrict within‐farm and farm‐to‐farm transmission. Although JD control programmes have been implemented in most developed countries, lessons learned from JD prevention and control programmes are underreported. Also, JD control programmes are typically evaluated in a limited number of herds and the duration of the study is less than 5 year, making it difficult to adequately assess the efficacy of control programmes. In this manuscript, we identify the most important gaps in knowledge hampering JD prevention and control programmes, including vaccination and diagnostics. Secondly, we discuss directions that research should take to address those knowledge gaps
Evaluation of an alternative method of herd classification for infection with paratuberculosis in cattle herds in the United States
No full textObjective - To develop a better system for classification of herd infection status for paratuberculosis (Johne's disease JD]) in US cattle herds on the basis of the risk of potential transmission of Mycobacterium avium subsp paratubeculosis. Sample - Simulated data for herd size and within-herd prevalence; sensitivity and specificity for test methods obtained from consensus-based estimates. Procedures - Interrelationships among variables influencing interpretation and classification of herd infection status for JD were evaluated by use of simulated data for various herd sizes, true within-herd prevalences, and sampling and testing methods. The probability of finding ≥1 infected animal in herds was estimated for various testing methods and sample sizes by use of hypergeometric random sampling. Results - 2 main components were required for the new herd JD classification system: the probability of detection of infection determined on the basis of test results from a sample of animals and the maximum detected number of animals with positive test results. Tables were constructed of the estimated probability of detection of infection, and the maximum number of cattle with positive test results or fecal pools with positive culture results with 95% confidence for classification of herd JD infection status were plotted. Herd risk for JD was categorized on the basis of 95% confidence that the true within-herd prevalence was ≤15%, ≤10%, ≤5%, or ≤2%. Conclusions and Clinical Relevance - Analysis of the findings indicated that a scientifically rigorous and transparent herd classification system for JD in cattle is feasible.Source type: Electronic(1
Factors associated with participation of Alberta dairy farmers in a voluntary, management-based Johne’s disease control program
No full textThe Alberta Johne's Disease Initiative (AJDI) is a voluntary, management-based prevention and control program for Johne's disease (JD), a wasting disease in ruminants that causes substantial economic losses to the cattle industry. Despite extensive communication about the program's benefits and low cost to participating producers, approximately 35% of Alberta dairy farmers have not enrolled in the AJDI. Therefore, the objective was to identify differences between AJDI nonparticipants and participants that may influence enrollment. Standardized questionnaires were conducted in person on 163 farms not participating and 61 farms participating in the AJDI. Data collected included demographic characteristics, internal factors (e.g., attitudes and beliefs of the farmer toward JD and the AJDI), external factors (e.g., farmers' JD knowledge and on-farm goals and constraints), as well as farmers' use and influence of various information sources. Nonparticipants and participants differed in at least some aspects of all studied categories. Based on logistic regression, participating farms had larger herds, higher self-assessed knowledge of JD, better understanding of AJDI details before participation, and used their veterinarian more often to get information about new management practices and technologies when compared with nonparticipants. In contrast, nonparticipants indicated that time was a major on-farm constraint and that participation in the AJDI would take too much time. They also indicated that they preferred to wait and see how the program worked on other farms before they participated
Deadly meals: The influence of personal and job factors on burnout and risky riding behaviours of food delivery motorcyclists
No full textFood delivery riders are overrepresented in road crashes. Arguably, the increased risk experienced by food delivery riders is linked to the working conditions offered by the “gig economy”. Research is needed to fully understand the safety-related issues this vulnerable group of road users face daily and identify opportunities for counter measures. In this investigation, we proposed a new theoretical model to explain the risky behaviour of food delivery motorcyclists based on the well-established Job Demands-Resources (JD-R) model. Following the JD-R, we considered the impact of job demands (job aspects that require sustained effort) and job resources (job aspects that help achieve work-related goals, reduce job demands and stimulate personal development) on the risky riding behaviours of food delivery motorcyclists. The JD-R model was also extended with three constructs, including personal demands, personal resources, and perceived safety risk to explore the role of individuals' within-person aspects. The developed model was tested using data collected from 554 food delivery riders in the two biggest cities in Vietnam. The results showed that job burnout, job resources, and personal demands directly impact risky riding behaviours, in which job burnout was the most significant predictor. Constructs such as job demands, personal resources, and perceived safety risk were not significant predictors of risky riding behaviours. This research shows that organisation-level factors could be modified to prevent risky riding behaviour. The gig economy industry can do much more to improve the safety of delivery riders.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Safety and Security Scienc
Dairy producer satisfaction and knowledge transfer with the veterinary-administered risk assessment and management plan in a voluntary Johne's disease control program
No full textThe Atlantic Johne's Disease Initiative (AJDI) aims to control Mycobacterium avium ssp. paratuberculosis infection by using veterinary-administered risk assessments to identify high-risk management practices and prompt changes in management behavior. Objectives for this study were to measure producer satisfaction with the veterinary-administered risk assessment and management plan (RAMP) process in a voluntary Johne's disease (JD) control program, compare RAMP-specific satisfaction results based on herd JD status, and measure knowledge transfer from certified veterinarians to producers during the RAMP. A satisfaction questionnaire was adapted to the RAMP process in the AJDI to measure producer satisfaction. The questionnaire included 9 RAMP-specific producer satisfaction items, 1 global RAMP satisfaction item, and 16 questions to assess producer knowledge and knowledge translation about JD, bovine viral diarrhea (BVD), and bovine leukosis virus (BLV) during the RAMP (BVD and BLV used for comparison purposes). A total of 133 dairy producers in the AJDI (79.6% response rate) completed the questionnaire by telephone. The RAMP-specific satisfaction was high among the AJDI producers surveyed, and these results were not found to differ based on herd JD status. The lowest satisfaction scores and the highest number of “unable to assess” responses were for the item relating to cost. Factors that contributed to RAMP-specific producer satisfaction were not identified from the demographic and herd information available in this study. The knowledge scores indicated moderate knowledge about JD and fair knowledge about BVD and BLV. Evidence of knowledge translation from the RAMP was mixed in this study. Bovine viral diarrhea knowledge scores were not found to differ based on whether or not the certified veterinarian discussed BVD during the preceding RAMP, but BLV knowledge scores were higher among dairy producers that discussed BLV during the preceding RAMP. Strengths and gaps in producer knowledge about these 3 infectious diseases were identified. By using this producer questionnaire, interventions aimed at improving the content, delivery, and satisfaction of RAMP in JD control programs, such as the AJDI, can be developed.Dairy Farmers of Prince Edward Island, Nova Scotia, New Brunswick, and Newfoundland and LabradorAgriculture and Agri-Foo
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