Evaluation of a wireless ambulatory capsule (SmartPill®) to measure gastrointestinal tract pH, luminal pressure and temperature, and transit time in ponies

Reasons for performing study: This study investigated the use of a wireless ambulatory capsule (WAC; SmartPill^® pH.p GI Monitoring System) to determine WAC‐gastric emptying time (GET) in ponies. Objectives: To measure WAC‐GET and compare it to those findings with GET assessed by nuclear scintigraphy (S‐GET). Hypothesis: WAC‐GET will be slower than S‐GET, but will be significantly correlated. Methods: Seven healthy adult mixed‐breed pony mares were used in this study. Feed was withheld for 12 h prior to the WAC administration. After administration, a complete‐feed diet was fed to allow the WAC to pass into the stomach. Luminal pH, temperature and pressure were collected by a modified receiver secured to the pony. Once the pH reached a value of ≥8.0, it was determined that gastric emptying had occurred, and ponies were fed grass hay. After 5 days, data were downloaded and analysed using proprietary software. During the second period of the study, after at least 2 weeks, 4 of the ponies underwent a standard S‐GET test. Results: The WAC was successfully administered, and data were collected from all ponies. The mean percentage of data packets collected by the receiver was 84.9 ± 3.51% (range 66.8–95.1%). Mean WAC‐GET was 7.38 h (range 0.15–46.65 h). Mean gastric pH was 4.75 (range 2.07–6.99). Mean small intestinal transit time was 4.6 h. The mean pH for the small intestine was 8.0. The mean S‐GET time (in hours) when 10% of the radioactive feed is present in the stomach (T‐90%) was 2.3 h. The S‐GET did not correlate significantly with the WAC‐GET. Conclusions and potential relevance: The WAC was safely administered to ponies, and data were collected using a modified receiver. The WAC‐GET varied considerably between ponies, but was ≤3 h in 5 of the 6 ponies. The WAC used in this study provided a noninvasive technique that produced novel information about the pony gastrointestinal tract, but owing to the substantial variability in GET values and long transit time it may not be a reliable clinical tool at this time.     

Evaluation of hyaluronidase activity in equine and bovine sera and equine synovial fluid samples by use of enzyme zymography

OBJECTIVE: To investigate the activities of hyaluronidases in equine sera and synovial fluid samples and sera from fetal and adult bovids and evaluate the extent to which the degradation of hyaluronan is influenced by chondrocytes. SAMPLE POPULATION: Commercial and noncommercial samples of equine (n = 6) and bovine (6) sera and 16 synovial fluid samples from horses. PROCEDURE: Hyaluronidase activities in sera and synovial fluid samples were assessed via enzyme zymography (performed at pH 4, 5, 6, or 7). Chondrocytes were isolated from equine cartilage and cultured with or without hyaluronan (1 mg/mL); the degradation of hyaluronan was assessed via agarose gel electrophoresis. RRESULTS: Hyaluronidase activity was detected in equine sera and synovial fluid samples at pH 4, but not at pH 7, and in bovine sera at both pH values. In all samples at pH 4, a major band of activity (molecular weight, approx 60 kd) and some additional higher molecular weight bands were detected; high- and low-molecular-weight activities were detected in bovine sera at pH 7 Hyaluronan in tissue culture medium with or without fetal calf serum was degraded in the presence, but not the absence, of equine chondrocytes. CONCLUSIONS AND CLINICAL RELEVANCE: Hyaluronidase activity was detected in equine sera and synovial fluid at pH 4 and in bovine sera at pH 4 and 7. Primary chondrocytes in monolayer culture can degrade exogenous hyaluronan. Modulating native hyaluronidase activity may offer a new approach to improve the quantity and quality of hyaluronan in articular joints.     

Investigation of the effect of black walnut extract on in vitro ion transport and structure of equine colonic mucosa

OBJECTIVE: To examine the secretory response (in the presence and absence of prostaglandin inhibition) in vitro and structural alterations of colonic mucosa in horses after intragastric administration of black walnut extract (BWE). ANIMALS: 14 adult horses. PROCEDURE: Seven horses were administered BWE intragastrically and monitored for 11 hours. Tissue samples were obtained from the right ventral, left ventral, and right dorsal colons (RVC, LVC, and RDC, respectively) of the 7 BWE-treated and 7 control horses. Tissue samples were examined via light microscopy, and the extent of hemorrhage, edema, and granulocytic cellular infiltration (neutrophils and eosinophils) was graded. Colonic mucosal segments were incubated with or without flunixin meglumine (FLM) for 240 minutes; spontaneous electrical potential difference and short-circuit current (Isc) were recorded and used to calculate mucosal resistance. RESULTS: Colonic tissues from BWE-treated horses (with or without FLM exposure) had an overall greater Isc during the 240-minute incubation period, compared with tissues from control horses. The resistance pattern in RVC, LVC, and RDC samples (with or without FLM exposure) from BWE-treated horses was decreased overall, compared with control tissues (with or without FLM exposure). Histologically, colonic mucosal tissues from BWE-treated horses had more severe inflammation (involving primarily eosinophils), edema, and hemorrhage, compared with tissue from control horses. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, BWE administration appears to cause an inflammatory response in colonic mucosal epithelium that results in mucosal barrier compromise as indicated by decreased mucosal resistance with presumed concomitant electrogenic chloride secretory response, which is not associated with prostaglandin mediation.     

The influence of environment on development of the mucosal immune system

The mucosal immune system expresses active responses against pathogens and also tolerance against harmless food and commensal bacterial antigens. The mechanisms that determine which of these outcomes occur after recognition of antigens by T-cells are not clear. One possibility is that it is determined by the initial interaction between a dendritic and a na?ve T-cell in organised lymphoid tissue. However, such organised structures are, evolutionarily, quite recent and the original immune system must have made appropriate responses in more diffuse immunological architecture; a second possibility is that the critical interaction is between primed T-cells and their environment, in the lamina propria of the intestine. The mucosal immune system of neonates is poorly developed and inefficient at expressing appropriate immune responses. Development is influenced by a range of environmental factors including maternally derived antigen or antibody and commensal flora and pathogens. The intestine is a complex immunological structure in which the immune system and the macro- and microenvironment interact.     

Effects of topical nitroglycerine patches and ointment on digital venous plasma nitric oxide concentrations and digital blood flow in healthy conscious horses

OBJECTIVE: To measure and compare palmar digital venous plasma nitric oxide (NO) concentrations and digital arterial blood flow after application of topical nitroglycerine (NTG). STUDY DESIGN: Experimental study. ANIMALS: Healthy adult horses (n=8). METHODS: Digital blood flow was measured by an ultrasonic Doppler flow probe surgically implanted around the medial palmar digital artery. Blood was collected from a catheter placed in the medial palmar digital vein for quantification of NO. NTG patches, NTG ointment or control patches were placed over the palmar digital vessels at the level of the fetlock. Two horses had an intra-arterial infusion of an NTG solution into the medial palmar digital artery in a pilot study. RESULTS: Digital arterial blood flow did not change significantly with application of the NTG patches, NTG ointment, or control patches. There were no statistically significant or biologically important changes in digital venous NO concentrations across time or between treated and control horses. In the pilot study, digital arterial blood flow and palmar digital venous NO concentrations increased with intra-arterial infusion of NTG. CONCLUSIONS: In clinically healthy horses, digital arterial blood flow and digital venous plasma NO concentrations did not change significantly with application of the NTG patches/ointment. These treatments are unlikely to have an effect on the digital vasculature of laminitic horses, however, further investigation is warranted. CLINICAL RELEVANCE: Although NTG patches have been used as a method of decreasing vasomotor tone and improving digital blood flow in horses with laminitis, this study provides evidence in healthy conscious horses that this treatment is not effective in altering digital blood flow.     

Summary of the first round analyses of the Second International Swine CD Workshop

The reactivity of 176 monoclonal antibodies (mAb) submitted to the Second International Swine CD Workshop, together with 19 internal standards, was analyzed by flow cytometry on 16 different cell types as a means of establishing the proper cell subset for later detailed clustering analyses. The exact CD subset reactivity of the 19 internal standard mAb had been characterized in the First International Swine CD Workshop. The flow cytometric analyses resulted in 40 data sets which were then subjected to statistical clustering using the Leukocyte Typing Database IV (LTDB4) software. As result of this work, 22 clusters were defined. After review of these results, panels of mAb from the defined first round clusters were assigned to cell subsets. The respective mAb in those first round clusters were then distributed to subset group researchers for further examination during the second round of the workshop.     

Effects of vegetation type on soil resistance to erosion: Relationship between aggregate stability and shear strength

Soil water erosion and shallow landslides depend on aggregate stability and soil shear strength. We investigated the effect of vegetation on both soil aggregate stability and shear strength (through direct shear tests) in former croplands converted to vegetated erosion protection areas within the context of China's sloping land conversion programme. Four treatments were analysed in plots comprised of (i) 4 year old crop trees, Vernicia fordii, where understory vegetation was removed; (ii) V. fordii and the dominant understory species Artemisia codonocephala; (iii) only A. codonocephala and (iv) no vegetation. Soil samples were taken at depths of 0–5 cm and 45–50 cm. Root length density (RLD) in five diameter classes was measured, soil organic carbon (SOC), hot water extractable carbon (HWEC), texture and Fe and Al oxides were also measured. We found that mean weight diameter after slow wetting (MWD_SW) in the A-horizon, was significantly greater (0.94–1.01 mm) when A. codonocephala was present compared to plots without A. codonocephala (0.57–0.59 mm). SOC and RLD in the smallest diameter class (< 0.5 mm), were the variables which best explained variability in MWD_SW. A significant positive linear relationship existed between MWD_SW and soil cohesion but not with internal angle of friction. As herbaceous vegetation was more efficient than trees in improving aggregate stability, this result suggests that the mechanisms involved include modifications of the cohesive forces between soil particles adjacent to plant roots and located in the enriched in SOC rhizosphere, thus also affecting shear strength of the corresponding soil volume. Thus, vegetation stabilised soil under different hierarchical levels of aggregate organisation, i.e. intra- and inter-aggregate. Our results have implications for the efficacy of techniques used in land conversion programs dedicated to control of soil erosion and shallow landslides. We suggest that mixtures of different plant functional types would improve soil conservation on slopes, by reducing both surface water erosion and shallow substrate mass movement. Planting trees for cropping or logging, and removing understory vegetation is most likely detrimental to soil conservation.     

A numerical investigation into factors affecting the anchorage of roots in tension

The arrangement of a plant's roots in the soil determines the ability of the plant to resist uprooting. We have investigated the influence of root morphology on anchorage using simple patterns of root systems and numerical simulation. The form and mechanical properties of roots were derived from results found in the literature. Major parameters determining soil characteristics, root patterns and strength were varied so that their influence could be evaluated. The design of the experimental method we used generated an optimal number of configurations of different root systems, the tensile resistances of which were calculated by two‐dimensional finite element analysis. We could quantify the influence of specific parameters, e.g. branching angle, number of lateral roots and soil cohesion, as well as global parameters such as total contact area, basal diameter and volume of the whole root system. We found that the number of roots and the diameter of roots were major components affecting the resistance to uprooting. The combination of topology and biomass explained 70% of the variation of tensile resistance.