Serum IgM antibody response to Clostridioides difficile polysaccharide PS-II vaccination in pony foals.

OBJECTIVES: Clostridioides difficile (formerly Clostridium difficile) is associated with colitis in foals and mature horses. C. difficile exposes specific phosphorylated polysaccharides (PSs), named PS-I, PS-II and PS-III. These cell-surface PSs are potential vaccine targets, especially the hexasaccharide phosphate PS-II, that has been found in all C. difficile ribotypes examined. Since we previously identified anti-PS-II circulating antibodies in horses, we postulated that vaccinating foals with PS-II may prevent colonization by C. difficile. In this study, we aim to evaluate the IgM antibody responses in foals to PS-II. METHODS: To evaluate the reactogenicity and immunogenicity of C. difficile PS-II in foals, three-to four-month-old foals were vaccinated intramuscularly three times at intervals of three weeks with 100 µg/dose (3 foals) or 500 µg/dose (3 foals) of purified PS-II antigen with aluminum hydroxide adjuvant, or with a placebo preparation (2 foals) containing adjuvant alone. RESULTS: No injection site swelling, pain or fever was observed after vaccination. Two of the three foals receiving 100 µg/dose, and three out of three foals receiving 500 µg/dose of PS-II responded with increases in serum IgM antibodies. No control foals that received the placebo had IgM responses to PS-II. There was a trend towards a higher response rate in foals receiving 500 µg PS-II one week after second vaccination when compared to control foals and towards higher concentrations of serum IgM antibodies in foals receiving 500 µg PS-II. CONCLUSIONS: No adverse reactions were observed following vaccination with PS-II in foals; Serum IgM immune responses were induced by vaccination. A polysaccharide-based vaccine for C. difficile in horses deserves further investigation.

A structural approach to 3D-printing arterial phantoms with physiologically comparable mechanical characteristics: Preliminary observations.

Pulse wave behavior is important in cardiovascular pathophysiology and arterial phantoms are valuable for studying arterial function. The ability of phantoms to replicate complex arterial elasticity and anatomy is limited by available materials and techniques. The feasibility of improving phantom performance using functional structure designs producible with practical 3D printing technologies was investigated. A novel corrugated wall approach to separate phantom function from material properties was investigated with a series of designs printed from polyester-polyurethane using a low-cost open-source fused filament fabrication 3D printer. Nonpulsatile pressure-diameter data was collected, and a mock circulatory system was used to observe phantom pulse wave behavior and obtain pulse wave velocities. The measured range of nonpulsatile Peterson elastic strain modulus was 5.6-19 to 12.4-33.0 kPa over pressures of 5-35 mmHg for the most to least compliant designs respectively. Pulse wave velocities of 1.5-5 m s-1 over mean pressures of 7-55 mmHg were observed, comparing favorably to reported in vivo pulmonary artery measurements of 1-4 m s-1 across mammals. Phantoms stiffened with increasing pressure in a manner consistent with arteries, and phantom wall elasticity appeared to vary between designs. Using a functional structure approach, practical low-cost 3D-printed production of simple arterial phantoms with mechanical properties that closely match the pulmonary artery is possible. Further functional structure design development to expand the pressure range and physiologic utility of dir"ectly 3D-printed phantoms appears warranted.

Hematuria in a 3-month-old filly with an internal umbilical abscess and internal iliac artery aneurysm.

A 3-month-old foal with a history of acute hematuria was evaluated. Hydronephrosis and hydroureter were visualized upon renal ultrasonography of the left kidney. Cystoscopy identified a blood clot occluding the left ureter. Computed tomography (CT) revealed a large retroperitoneal abscess at the level of the aortic bifurcation and a left internal iliac aneurysm. Due to the severity of the lesions and the poor prognosis, the filly was euthanized and the clinical findings were confirmed by post-mortem examination. This report emphasizes the value of obtaining a precise diagnosis via CT in order to avoid unviable treatment approaches when confronted with this unusual secondary complication of omphaloarteritis. Key clinical message: Umbilical complications are routinely diagnosed in equine neonatal medicine, and commonly lead to septicemia, physitis, and septic arthritis; severe internal umbilical abscessation, and subsequent vascular and urinary disorders are uncommon sequelae.

Hématurie chez une pouliche de 3 mois avec abcès ombilical interne et anévrisme de l'artère iliaque interne. Un poulain de 3 mois ayant des antécédents d'hématurie aiguë a été évalué. L'hydronéphrose et l'hydro-uretère ont été visualisés par échographie rénale du rein gauche. La cystoscopie a identifié un caillot sanguin obstruant l'uretère gauche. La tomodensitométrie (TDM) a révélé un gros abcès rétropéritonéal au niveau de la bifurcation aortique et un anévrisme iliaque interne gauche. En raison de la gravité des lésions et du mauvais pronostic, la pouliche a été euthanasiée et les résultats cliniques ont été confirmés par un examen post-mortem. Ce rapport souligne l'intérêt d'obtenir un diagnostic précis par TDM afin d'éviter des approches thérapeutiques non-viables face à cette complication secondaire inhabituelle de l'omphalo-artérite.Message clinique clé :Les complications ombilicales sont couramment diagnostiquées en néonatalogie équine et conduisent généralement à une septicémie, une épiphysite et une arthrite septique; un abcès ombilical interne sévère et des troubles vasculaires et urinaires subséquents sont des séquelles peu fréquentes.(Traduit par Dr Serge Messier).

Development of a technique for determination of pulmonary artery pulse wave velocity in horses.

Calcification of the tunica media of the axial pulmonary arteries (PA) has been reported in a large proportion of racehorses. In humans, medial calcification is a significant cause of arterial stiffening and is implicated in the pathogenesis of cardiac, cerebral, and renal microvascular diseases. Pulse wave velocity (PWV) provides a measure of arterial stiffness. This study aimed to develop a technique to determine PA-PWV in horses and, secondarily, to investigate a potential association between PA-PWV and arterial fibro-calcification. A dual-pressure sensor catheter (PSC) was placed in the main PA of 10 sedated horses. The pressure waves were used to determine PWV along the PA, using the statistical phase offset method. Histological analysis of the PA was performed to investigate the presence of fibro-calcified lesions. The mean (±SD) PWV was 2.3 ± 0.7 m/s in the proximal PA trunk and 1.1 ± 0.1 m/s further distal (15 cm) in a main PA branch. The mean (±SD) of mean arterial pressures in the proximal PA trunk was 30.1 ± 5.2 mmHg, and 22.0 ± 6.0 mmHg further distal (15 cm) within the main PA branch. The mean (±SD) pulse pressure in the proximal PA trunk was 15.0 ± 4.7 mmHg, and 13.5 ± 3.3 mmHg further distal (15 cm) within the main PA branch. Moderate to severe lesions of the tunica media of the PAs were observed in seven horses, but a correlation with PWV could not be established yet. Pulmonary artery PWV may be determined in standing horses. The technique described may allow further investigation of the effect of calcification of large PAs in the pathogenesis of equine pulmonary circulatory disorders.NEW & NOTEWORTHY Pulmonary artery pulse wave velocity was determined safely in standing sedated horses. The technique described may allow further investigation of the effect of calcification of large pulmonary arteries in the pathogenesis of pulmonary circulatory disorders in horses.

Responses of a looming-sensitive neuron to compound and paired object approaches.

The lobula giant movement detector (LGMD) and its target neuron, the descending contralateral movement detector (DCMD), constitute a motion-sensitive pathway in the locust visual system that responds preferentially to objects approaching on a collision course. LGMD receptive field properties, anisotropic distribution of local retinotopic inputs across the visual field, and localized habituation to repeated stimuli suggest that this pathway should be sensitive to approaches of individual objects within a complex visual scene. We presented locusts with compound looming objects while recording from the DCMD to test the effects of nonuniform edge expansion on looming responses. We also presented paired objects approaching from different regions of the visual field at nonoverlapping, closely timed and simultaneous approach intervals to study DCMD responses to multiple looming stimuli. We found that looming compound objects evoked characteristic responses in the DCMD and that the time of peak firing was consistent with predicted values based on a weighted ratio of the half size of each distinct object edge and the absolute approach velocity. We also found that the azimuthal position and interval of paired approaches affected DCMD firing properties and that DCMDs responded to individual objects approaching within 106 ms of each other. Moreover, comparisons between individual and paired approaches revealed that overlapping approaches are processed in a strongly sublinear manner. These findings are consistent with biophysical mechanisms that produce nonlinear integration of excitatory and feed-forward inhibitory inputs onto the LGMD that have been shown to underlie responses to looming stimuli.