Factors affecting dairy calf price in auction markets in Québec, Canada: 2008-2019.

Dairy calves not kept for replacement are sold at young age in Québec auction markets for white and grain-fed veal calf production. The province of Québec produces 80% of the Canadian veal meat, but little information is available on the factors associated with the calves' price per crude weight (Can$/kg; Can$1 = US$0.78 at time of writing). The characteristics of calves sold in Québec auction markets from 12 complete years (2008-2019) were retrospectively studied. The calves' weight, breed and sex, the year and season of sale, the auction site, as well as the estimated distance traveled between the farm of origin and the auction site were analyzed as potential covariates associated with calf price. Two multivariable logistic models associated with low sale value (below the 10th or the 25th percentile of the day price) and 2 models associated with good sale characteristics (above the 50th or the 75th percentile of the day price) were built. The median distance between the farm and the auction site was 52 km (interquartile range: 30-95 km). Only 5% of calves traveled distances greater than 220 km. The weight, breed, sex, and auction sites explained most of the variability in the different models. Distance traveled and multiple interactions were also significantly associated with the outcomes. Calves with body weight from 48 to <56 kg were sold in higher percentiles of the day than lighter or heavier calves. Beef-crossed calves had better sale prices than Holstein, whereas colored dairy calves had lower sale characteristics than both Holstein and beef-crossed calves. The effect of distance traveled was complex, varying depending on the model and interactions, and explained a small portion of the total deviance in every model. Calves traveling from distances ≥110 km had lower sale characteristics in summer and fall in the different studied models. This study gives relevant insights on calves' characteristics associated with good versus low sale prices in Québec auction markets.

Health parameters and their association with price in young calves sold at auction for veal operations in Québec, Canada.

The veal calf industry in Québec depends on young calves' availability at auction. Most of these calves come from dairy farms. The aim of this cross-sectional study was to determine the effect of clinical anomalies and other calf characteristics on their sale price. A total of 3,820 calves from 5 different auctions were included in this observational study. The calves were examined by a veterinarian on arrival at the auction and screened for umbilical anomalies, the presence of nasal or eye discharge, joint abnormality, diarrhea, appearance of neonatal characteristics (compatible with age less than 1 wk), and general health status mainly based on the presence of depression and dehydration. The final multivariable model included 5 different variables (calf weight, sex, breed, abnormal joints, and general health status) and the interaction between sex and general health status. The presence of abnormal joints and unhealthy characteristics was negatively associated with standardized price. Female calves and mixed breed beef calves were positively associated with standardized price. Finally, the calves' weight was associated with standardized price in a quadratic fashion. Ongoing or previous diarrhea had no effects on standardized price. This study will be helpful for both dairy and veal producers for improving the quality of calves sold to the Québec auction market.

Management of neonatal thrombocytopenia in a context of maternal antiplatelet alloimmunization: Expert opinion of the French-speaking working group.

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a potentially devastating disease, seen in 1/800-1000 neonates. FNAIT is the most common cause of early-onset isolated severe neonatal thrombocytopenia in maternity wards. The most feared complication of this disorder is intracranial hemorrhage, leading to death or neurological sequelae. There is no systematic screening of at-risk pregnancies and FNAIT is often discovered when fetal or neonatal bleeding is observed. A working group on fetomaternal platelet alloimmunization was created in 2017, under the auspices on the French Group of Thrombosis and Hemostasis (GFHT). The first objective of this group was to survey clinical practices for treatment of thrombocytopenic neonates in a context of suspected or confirmed FNAIT.

Dissociation of atrioventricular conduction and refractoriness following application of radiofrequency energy to the canine atrioventricular node: acute and chronic observations.

The electrophysiology of AV nodal modification induced by radiofrequency energy (n = 5) or a sham procedure (n = 5) was studied in ten dogs. The five dogs that received radiofrequency energy had an AH prolongation > 100% from baseline values and this prolongation persisted throughout the 2-month study. The AV nodal functional refractory period was prolonged only acutely. These data indicate a dissociation between the effects on AV nodal conduction and refractoriness that was induced by this procedure. The five sham treated controls showed no acute or chronic electrophysiological changes. In the dogs that received radiofrequency energy, there was fibrosis of the approaches to the AV node and the region of the AV node itself. It is concluded that chronic modification of AV nodal conduction without concomitant changes in refractoriness can be induced by radiofrequency energy delivered in the proximal portion of the AV node. It would be anticipated that this procedure would not decrease the ventricular response to atrial fibrillation or flutter, may be effective in preventing AV nodal reentrant tachycardia by interfering with conduction either in the AV node or perinodal region. Since the AV node itself suffers at least moderate pathological damage, there may be an appreciable incidence of the late development of complete heart block after this procedure.

Rabbit embryo-fetal fluid decreases the cell cycle activities of DU-145 cells.

Successful reproduction requires tight control of cell proliferation and differentiation. Rabbit blastocoelic fluid contains such regulatory factors. For instance, it inhibits tumour or transformed cell proliferation. In this study, DU-145 cells have been used to characterize further this inhibitory activity. Maximal inhibition of cell proliferation is observed at day 12 of embryo-fetal development and this is accompanied by a strong reduction of [3H]-thymidine incorporation. DNA specific staining and analysis by flow cytometry show that cells are not stopped at any specific stage of the cell cycle. Using bromodeoxyuridine incorporation in combination with propidium iodide labelling, it has been possible to estimate the percentage of labelled cells, the duration of the S phase of the cell cycle derived from their relative movement and also the proportion of cells participating to the cell cycle. In the presence of embryonic and fetal fluids collected on day 12 (EFF D-12) the duration of the S phase and the doubling time are considerably increased and the percentage of cells participating in the cell cycle is decreased. The results also show that treatment with EFF D-12 induces the release of the cells from the monolayer. Taken altogether, these results suggest that EFF D-12 increases the duration of the cell cycle. This reduction of the mitotic activities lead up to cell death with subsequent release of cells into the culture medium.

Assessment of effects of a radiofrequency energy field and thermistor location in an electrode catheter on the accuracy of temperature measurement.

Accurate measurement of temperature at the interface of the delivery electrode and the tissue during transcatheter delivery of radiofrequency energy (RFE) for ablation would provide better control of lesion production. Electromagnetic energy fields can affect the accuracy of temperature measurement with thermistors. An electrode probe was fabricated with a thermistor and an optical sensor in the center of the delivery electrode. Simultaneous temperature measurements during RFE delivery to cardiac tissue in the 37 degrees C bath showed good agreement between the sensors, indicating that the RFE field did not cause errors in thermistor temperature measurements with the electrode probe used. A second electrode probe was designed to determine optimal thermistor location. It was constructed using two thermistors with identical temperature-resistance curves. One thermistor protruded through a hole in the side of the delivery electrode and was thermally isolated from it. The other thermistor was bonded to the inner surface of the electrode with heat conductive epoxy. The electrode was placed in contact with cardiac tissue in a 37 degrees C bath of flowing saline with the protruding thermistor centered in the area to be heated. Temperatures measured at steady state during RFE delivery with the protruding thermistor were consistently higher than those of the inner wall thermistor, ranging from 1.8 degrees C difference at 46 degrees C to 8.3 degrees C difference at 75 degrees C interface temperature. The thermistor must be in contact with the tissue and thermally isolated from the delivery electrode for accurate determination of electrode/tissue interface temperature.

Synthesis and antiarrhythmic activity of cis-2,6-dimethyl-alpha,alpha-diaryl-1-piperidinebutanols.

A series of alpha,alpha-diaryl-1-piperidinebutanols was evaluated for antiarrhythmic activity in the coronary ligated dog model. Structure-activity relationship studies indicated that the 2,6-dimethylpiperidine group yielded compounds with the best antiarrhythmic profiles in this series. The length of the methylene chain separating the diarylcarbinol and the amino group was not crucial. Substitution of a hydrogen or a number of functional groups for the hydroxyl group had little effect on efficacy or duration but yielded compounds that produced severe tachycardias. Replacement of one of the aryl groups by hydrogen or a pyridinyl or cyclohexyl group had little effect on efficacy but decreased the duration of action. Compound 18 (pirmenol) was ultimately chosen for further studies and is now being investigated in man.

Synthesis and antiarrhythmic activity of alpha-[(diarylmethoxy)methyl]-1-piperidineethanols.

A series of alpha-[(diarylmethoxy)methyl]-1-piperidineethanols was evaluated for antiarrhythmic activity in the coronary artery ligated dog model. Structure-activity relationship studies indicated that the 2,6-dimethylpiperidine group afforded the best antiarrhythmic agents in this series and was essential for long duration of action. This investigation indicated that quaternary ammonium salts were not essential for a long duration of action. It was also shown that the antiarrhythmic activity could be separated from the tachycardia frequently caused by this type of agent.

The effect of electrode design on the efficiency of delivery of radiofrequency energy to cardiac tissue in vitro.

Four types of electrodes were studied with respect to efficiency of delivery of radiofrequency energy (RFE) and characteristics of the lesions produced in dog ventricular muscle in vitro. An imbeddable needle electrode was found to be the most efficient of the four types studied, with a lesion volume/energy-delivered ratio of 1.10 mm3/joule at an optimum power level of 2.8 watts and power density at the electrode surface of 0.45 watt/mm2. Lesion volume was linearly related to energy delivered at all power levels used below a power density of 0.64 watt/mm2, at and above which tissue impedance increased abruptly. The electrode catheter typically used for RFE ablations was the least efficient at 0.15 mm3/joule and a power density at the electrode surface of 0.50 watt/mm2 at 6.27 watts. masking 2/3 of the electrode surface with electrically insulating epoxy caused the RFE current to be directed into the tissue, resulting in a threefold increase in efficiency (0.46 mm3/joule) at less than half the power (2.79 watts). A flat, thermally insulated electrode with larger (10 mm2) contact area approached the efficiency of the imbedded electrode with a ratio of 0.69 mm3/joule at a low power density of 0.19 watt/mm2 and 1.85 watt power level. Characteristics of an "ideal" electrode for RFE lesion production in cardiac tissue are discussed.