Prediction of post-hemorrhagic ventricular dilatation trajectory using a growth mixture model in preterm infants.

BACKGROUND: Early intervention for post-hemorrhagic ventricular dilatation (PHVD), guided by ventricular size measurements from cranial ultrasound (cUS), is associated with improved neurodevelopmental outcomes in preterm infants but benefits must be balanced against intervention risks. METHODS: Anterior horn width (AHW) and ventricular index (VI) were measured from cUS for preterm infants (<29 weeks) with intraventricular hemorrhage admitted from 2010-2018. PHVD was defined as AHW > 6 mm or VI >97th percentile for postmenstrual age. Individual ventricular size trajectories were plotted, and a growth mixture model (GMM) used to identify latent trajectory classes and compare these to predetermined outcome of neurosurgical intervention. RESULTS: Measurements were obtained from 1543 cUS in 249 infants, of whom 39 had PHVD without and 17 PHVD with neurosurgical intervention based on signs of raised intracranial pressure. The GMM predicted trajectory identified: 93.3% of infants without PHVD, 88.2% and 30.8% of infants with PHVD with and without intervention using AHW; 100% of infants without PHVD, 52.9% and 59.0% of infants with PHVD with and without intervention using VI. CONCLUSIONS: The AHW GMM identified a significant proportion of infants with severe PHVD. Model refinement offers a promising approach for identifying differences in PHVD trajectory at an early stage to guide management. IMPACT: It is difficult to distinguish the trajectory of PHVD in the early stage of development, in particular PHVD that spontaneously arrests from slowly progressive PHVD which eventually requires intervention. We report the first modeling-based evaluation of PHVD trajectory for the prediction of short-term outcome of PHVD progression and neurosurgical intervention. With additional clinical validation and optimization to increase accuracy, predictive modeling has the potential to identify important differences in PHVD trajectory at an early stage in the clinical course, allowing for more individualized data-driven risk-benefit assessments to guide decisions on early intervention.

Self-care practices and depression, anxiety, and stress scores in veterinary students during a semester.

Objective: To measure associations between self-care activities and depression, anxiety, and stress of preclinical veterinary students during a semester. Procedure: Preclinical veterinary students at the University of Calgary Faculty of Veterinary Medicine were recruited voluntarily. Depression, anxiety, and stress scores (DASS-21) were measured, and a self-care questionnaire was administered at the beginning and end of the semester. Results: Depression, anxiety, and stress scores did not change during the fall semester (P = 1.000). At the beginning of the semester, students who spent 15 to 30 min (P = 0.042) or 30 to 60 min (P = 0.013) outside daily had lower anxiety scores compared to those who spent < 15 min outside daily; students who spent > 2 h daily on social media had higher stress scores than students who spent < 60 min (P = 0.024); and students who slept for 6 to 8 h daily had lower stress scores than students who slept < 6 h (P = 0.015). At the end of the semester, students who "often" felt that self-care techniques managed their stress had lower depression (P = 0.003) and anxiety (P = 0.011) scores than those who "rarely" did; students who spent 30 to 60 min outside daily had lower depression scores than those who spent < 15 min (P = 0.031); students who spent 15 to 30 min (P = 0.002) or 30 to 60 min (P = 0.009) outside daily had lower stress scores than those who spent < 15 min; and students who exercised 30 to 60 min daily had lower stress scores than those who exercised < 15 min (P = 0.047). Conclusion: Self-care activities that were associated with lower depression, anxiety, or stress scores at the beginning or end of the semester included spending at least 15 min daily outside or exercising; spending < 30 min on social media daily; and sleeping 6 to 8 h daily. These practices warrant further investigation. Clinical relevance: Encouraging certain self-care practices among preclinical veterinary students has the potential to enhance their mental health and should be considered part of a veterinary school curriculum.

Pratiques d'autosoins et scores de dépression, d'anxiété et de stress chez les étudiants vétérinaires au cours d'un semestre. Objectif: Mesurer les associations entre les activités d'autosoins et la dépression, l'anxiété et le stress des étudiants vétérinaires au cours d'un semestre. Procédure: Les étudiants vétérinaires de la faculté de médecine vétérinaire de l'University of Calgary ont été recrutés sur une base volontaire. Des scores de dépression, d'anxiété et de stress (DASS-21) ont été mesurés et un questionnaire d'autosoins a été administré au début et à la fin du semestre. Résultats: Les scores de dépression, d'anxiété et de stress n'ont pas changé au cours du semestre d'automne (P = 1,000). Au début du semestre, les étudiants qui passaient 15 à 30 min (P = 0,042) ou 30 à 60 min (P = 0,013) à l'extérieur par jour présentaient des scores d'anxiété inférieurs à ceux qui passaient < 15 min à l'extérieur par jour; les étudiants qui passaient > 2 h par jour sur les réseaux sociaux avaient des scores de stress plus élevés que les étudiants qui passaient < 60 min (P = 0,024); et les étudiants qui dormaient de 6 à 8 h par jour avaient des scores de stress inférieurs à ceux qui dormaient < 6 h (P = 0,015). À la fin du semestre, les étudiants qui estimaient « souvent ¼ que les techniques d'autosoins géraient leur stress avaient des scores de dépression (P = 0,003) et d'anxiété (P = 0,011) inférieurs à ceux qui l'étaient « rarement ¼; les étudiants qui passaient 30 à 60 min à l'extérieur quotidiennement avaient des scores de dépression inférieurs à ceux qui passaient moins de 15 min (P = 0,031); les étudiants qui passaient 15 à 30 min (P = 0,002) ou 30 à 60 min (P = 0,009) à l'extérieur quotidiennement avaient des scores de stress inférieurs à ceux qui passaient < 15 min; et les étudiants qui faisaient de l'exercice de 30 à 60 min par jour avaient des scores de stress inférieurs à ceux qui faisaient de l'exercice < 15 min (P = 0,047). Conclusion: Les activités d'autosoins associées à des scores de dépression, d'anxiété ou de stress plus faibles au début ou à la fin du semestre comprenaient le fait de passer au moins 15 minutes par jour à l'extérieur ou de faire de l'exercice; passer < 30 minutes sur les réseaux sociaux quotidiennement; et dormir 6 à 8 h par jour. Ces pratiques méritent une enquête plus approfondie. Pertinence clinique: Encourager certaines pratiques d'autosoins chez les étudiants vétérinaires a le potentiel d'améliorer leur santé mentale et devrait être considéré comme faisant partie du programme d'études d'une école vétérinaire.(Traduit par Dr Serge Messier).

Video Recording in Veterinary Medicine OSCEs: Feasibility and Inter-rater Agreement between Live Performance Examiners and Video Recording Reviewing Examiners.

The Objective Structured Clinical Examination (OSCE) is a valid, reliable assessment of veterinary students' clinical skills that requires significant examiner training and scoring time. This article seeks to investigate the utility of implementing video recording by scoring OSCEs in real-time using live examiners, and afterwards using video examiners from within and outside the learners' home institution. Using checklists, learners (n=33) were assessed by one live examiner and five video examiners on three OSCE stations: suturing, arthrocentesis, and thoracocentesis. When stations were considered collectively, there was no difference between pass/fail outcome between live and video examiners (χ2 = 0.37, p = .55). However, when considered individually, stations (χ2 = 16.64, p < .001) and interaction between station and type of examiner (χ2 = 7.13, p = .03) demonstrated a significant effect on pass/fail outcome. Specifically, learners being assessed on suturing with a video examiner had increased odds of passing the station as compared with their arthrocentesis or thoracocentesis stations. Internal consistency was fair to moderate (0.34-0.45). Inter-rater reliability measures varied but were mostly moderate to strong (0.56-0.82). Video examiners spent longer assessing learners than live raters (mean of 21 min/learner vs. 13 min/learner). Station-specific differences among video examiners may be due to intermittent visibility issues during video capture. Overall, video recording learner performances appears reliable and feasible, although there were time, cost, and technical issues that may limit its routine use.

Deslorelin and naltrexone stimulate follicular development in mares during autumn transition and early anestrus.

Horses are long-day breeders and commence ovarian follicular activity during the spring. Evidence suggests that there is an endogenous circannual rhythm in mares, and it is uncertain whether hormonal manipulation during or immediately following the fall transition induces follicular development. The current study was designed to test the hypothesis that both deslorelin and naltrexone induce follicular development in late fall transitioning or anestrous mares. Five of six mares treated with deslorelin, and 4 of 6 mares treated with naltrexone, developed a pre-ovulatory-sized follicle and were inseminated. Zero of three deslorelin-control mares and 1 of 3 naltrexone-control mares were inseminated. The number of mares bred in the deslorelin treatment group was significantly higher than in the corresponding control group (P < 0.05). Six of nine mares inseminated were pregnant 14 days after insemination. In conclusion, we were able to induce follicular development resulting in fertile ovulations during and shortly after the fall transition.

Stimulation du développement folliculaire par le deslorelin et le naltrexone chez des juments durant la transition automnale et le début de l'anoestrus. Les chevaux sont des reproducteurs saisonniers influencés par la lumière du jour et l'activité folliculaire ovarienne débute au printemps. Les évidences suggèrent que chez les juments il y a un rythme circannuel endogène, et il est incertain si une manipulation hormonale durant ou immédiatement après la transition automnale induit le développement folliculaire. La présente étude a été conçue afin de vérifier l'hypothèse que le deslorelin et le naltrexone induisent le développement folliculaire tard à l'automne lors de la période de transition ou chez des juments en anoestrus. Cinq des six juments traitées avec du deslorin et quatre des six juments traitées avec du naltrexone ont développé un follicule de taille pré-ovulatoire et ont été inséminées. Aucune des trois juments témoins pour le deslorin et une des trois juments témoins pour le naltrexone furent inséminées. Le nombre de juments saillies dans le groupe de traitement deslorin était significativement supérieur à celui du groupe témoin correspondant (P < 0,05). Six des neuf juments inséminées étaient gestantes 14 jours après l'insémination. En conclusion, nous avons été en mesure d'induire le développement folliculaire résultant en des ovulations fertiles durant et tôt après la transition automnale.(Traduit par Dr Serge Messier).

Workload of horses on a water treadmill: effect of speed and water height on oxygen consumption and cardiorespiratory parameters.

BACKGROUND: Despite the use of water treadmills (WT) in conditioning horses, the intensity of WT exercise has not been well documented. The workload on a WT is a function of water height and treadmill speed. Therefore, the purpose of this study was to determine the effects of these factors on workload during WT exercise. Fifteen client-owned Quarter Horses were used in a randomized, controlled study. Three belt speeds and three water heights (mid cannon, carpus and stifle), along with the control condition (dry treadmill, all three speeds), were tested. Measured outcomes were oxygen consumption (V̇O2), ventilation (respiratory frequency, tidal volume (VT)), heart rate (HR), and blood lactate. An ergospirometry system was used to measure V̇O2 and ventilation. Linear mixed effects models were used to examine the effects of presence or absence of water, water height and speed (as fixed effects) on measured outcomes. RESULTS: Water height and its interaction with speed had a significant effect on V̇O2, VT and HR, all peaking at the highest water level and speed (stifle at 1.39 m/s, median V̇O2 = 16.70 ml/(kg.min), VT = 6 L, HR = 69 bpm). Respiratory frequency peaked with water at the carpus at 1.39 m/s (median 49 breaths/min). For a given water height, the small increments in speed did not affect the measured outcomes. Post-exercise blood lactate concentration did not change. CONCLUSIONS: Varying water height and speed affects the workload associated with WT exercise. The conditions utilized in this study were associated with low intensity exercise. Water height had a greater impact on exercise intensity than speed.

Validation of noninvasive hemoglobin measurements using co-oximetry in anesthetized dogs.

New technology allows noninvasive measurement of total hemoglobin (Hb) in humans through use of multiple wavelength co-oximetry. This monitor is now available to the veterinary market but no studies have been performed to validate its use in animals. This study investigated the use of co-oximetry to measure Hb in anesthetized dogs by comparing "gold standard" Hb measurements from a laboratory (LabHb) with those measured by the co-oximeter (SpHb). Bland-Altman analysis showed that the monitor had a bias of -3.01 (SpHb values were lower than LabHb values) and that 64.5% of measured SpHb values were greater than 20 g/L different from their associated LabHb values. Based on the results of this study, use of co-oximetry to measure Hb in anesthetized dogs is not accurate enough to direct treatment. Further studies are warranted in other animal species and under other clinical conditions.

Validation des mesures non invasives de l'hémoglobine à l'aide de la co-oximétrie chez les chiens anesthésiés. La nouvelle technologie permet la mesure non invasive de l'hémoglobine totale (Hb) chez les humains à l'aide d'une co-oximétrie à longueurs d'onde multiples. Ce moniteur est maintenant disponible pour le marché vétérinaire, mais aucune étude n'a été réalisée pour valider son utilisation chez les animaux. Cette étude a évalué l'utilisation de la co-oximétrie pour mesurer Hb chez des chiens anesthésiés en comparant les mesures Hb d'un laboratoire (LabHb) considérées comme les mesures étalons aux mesures effectuées par le co-oximètre (SpHb). L'analyse Bland-Altman a montré que le moniteur avait un biais de −3,01 (les valeurs SpHb étaient inférieures aux valeurs LabHb) et que 64,5 % des valeurs SpHb mesurées présentaient une différence supérieure à 20 g/L par rapport aux valeurs LabHb correspondantes. En se fondant sur les résultats de cette étude, on constate que l'utilisation de co-oximétrie pour mesurer Hb chez les chiens anesthésiés n'est pas suffisamment exacte pour orienter le traitement. De nouvelles études sont justifiées chez d'autres espèces animales et dans d'autres conditions cliniques.(Traduit par Isabelle Vallières).

Assessment of insulin dose changes in pediatric patients with type 1 diabetes mellitus starting on continuous subcutaneous insulin infusion.

Objective: To assess change in total daily dose (TDD) of insulin following a switch from subcutaneous (SC) injections to continuous subcutaneous insulin infusion (CSII) in pediatric patients with type 1 diabetes (T1D). Secondary objectives were to determine the change in %basal insulin, insulin to carbohydrate (I:C) ratios, insulin sensitivity factor (ISF), and HbA1c/IDAA1c. Methods: A retrospective chart review of patients < 18 years of age who transitioned from SC to CSII at the Alberta Children's Hospital (Calgary, Alberta, Canada) between January 2019 and March 2022. Results: There was an increase of 0.04 units/kg/day in TDD from baseline vs 1-3 months later (p = 0.04, 95 % confidence interval (CI) [0.002, 0.072]). When stratified by age, a similar increase in TDD was observed in age 5-12 years only (p = 0.05, 95 % CI [0.0006, 0.8236]). There was a decrease in overall %basal insulin by 3 (44 % of TDD at baseline vs 41 % of TDD on CSII). (p = 0.02, 95 % CI [-5.5, -0.4]). No strengthening was seen in I:C ratios from baseline vs 1-3 months later. There was a significant strengthening of I:C ratios at all meals in the basal bolus group from 1-3 weeks to 1-3 months post-CSII; overall strengthening of ISF at both time points; and an overall HbA1c decrease -0.30 (p < 0.0001, CI [-0.45, -0.15]). Each extra year with diabetes was associated with a decrease in HbA1c by 0.07 % (p = 0.006). Conclusions: TDD of insulin was not found to be decreased post CSII initiation and patient characteristics should be considered when changing from SC to CSII. HbA1c was significantly improved post CSII.

Real-time pathologist-assisted field postmortem examinations of beef cattle.

Postmortem examination of deceased production animals with appropriate ancillary testing is fundamental to determining causes of morbidity and mortality. Reaching a definitive diagnosis is crucial to evidence-based herd management and treatment decisions that safeguard animal health and welfare, food safety, and human health. However, for a range of reasons, carcasses sometimes cannot be examined in a veterinary diagnostic laboratory. As a result, postmortem examinations of farmed animals, including cattle, are often performed on-farm by the referring veterinarian (rVet) with tissue samples submitted to a veterinary diagnostic laboratory for ancillary testing. For various reasons, field postmortems can be associated with lower diagnostic rates. We investigated real-time pathologist-assisted field postmortem examination (rtPAP) assistance to beef cattle rVets to gauge any improvement in attaining a final diagnosis. We found that rtPAPs improved the success of reaching a final diagnosis compared to unassisted field postmortem examinations. Both the participating bovine rVets and the pathologists saw benefits to the rtPAPs, with bovine rVets indicating that they would utilize this service in the future if available. Our proof-of-concept study demonstrated the positive role of rtPAPs in diagnosing beef cattle disease and speaks to the need for telepathology services supporting food animal rVets and producers.

Linearized forms of individual-level models for large-scale spatial infectious disease systems.

Individual-level models (ILMs) for infectious diseases, fitted in a Bayesian MCMC framework, are an intuitive and flexible class of models that can take into account population heterogeneity via various individual-level covariates. ILMs containing a geometric distance kernel to account for geographic heterogeneity provide a natural way to model the spatial spread of many diseases. However, in even only moderately large populations, the likelihood calculations required can be prohibitively time consuming. It is possible to speed up the computation via a technique which makes use a linearized distance kernel. Here we examine some methods of carrying out this linearization and compare the performances of these methods.

The effect of a high-selenium lentil diet on cardiovascular risk markers in an arsenic-exposed population.

Chronic arsenic exposure is associated with a number of systemic diseases, including cardiovascular disease. Selenium has been shown to promote arsenic excretion from the body. We investigated if a high-selenium lentil diet has an effect on blood pressure and plasma lipid levels in an arsenic-exposed population by conducting a 6-month randomized controlled dietary intervention trial with 405 participants.

Development of reference intervals for pupillometry in healthy dogs.

Background: Pupillometry, the measurement of pupil size and reactivity to a stimulus, has various uses in both human and veterinary medicine. These reflect autonomic tone, with the potential to assess nociception and emotion. Infrared pupillometry reduces inaccuracies that may occur when the pupillary light reflex is determined subjectively by the examiner. To our knowledge, there are no published studies outlining normal reference intervals for automated pupillometry in dogs. Objective: The objective of this study was to develop de novo automated pupillometry reference intervals from 126 healthy canine eyes. Methods: The pupillary light reflex (PLR) was measured with a handheld pupillometer (NeurOptics™ PLR-200™ Pupillometer). Parameters recorded included maximum pupil diameter (MAX), minimum pupil diameter (MIN), percent constriction (CON), latency (LAT), average constriction velocity (ACV), maximum constriction velocity (MCV), average dilation velocity (ADV) and time to 75% pupil diameter recovery (T75). One measurement was obtained for each eye. Results: The following reference intervals were developed: MAX (6.05-11.30 mm), MIN (3.76-9.44 mm), CON (-37.89 to -9.64 %), LAT (0.11-0.30 s), ACV (-6.39 to -2.63 mm/ s), MCV (-8.45 to -3.75 mm/s), ADV (-0.21-1.77 mm/s), and T75 (0.49-3.20 s). Clinical significance: The reference intervals developed in this study are an essential first step to facilitate future research exploring pupillometry as a pain assessment method in dogs.

Qiviut cortisol is associated with metrics of health and other intrinsic and extrinsic factors in wild muskoxen (Ovibos moschatus).

Glucocorticoid (GC) levels are increasingly and widely used as biomarkers of hypothalamic-pituitary-adrenal (HPA) axis activity to study the effects of environmental changes and other perturbations on wildlife individuals and populations. However, identifying the intrinsic and extrinsic factors that influence GC levels is a key step in endocrinology studies to ensure accurate interpretation of GC responses. In muskoxen, qiviut (fine woolly undercoat hair) cortisol concentration is an integrative biomarker of HPA axis activity over the course of the hair's growth. We gathered data from 219 wild muskoxen harvested in the Canadian Arctic between October 2015 and May 2019. We examined the relationship between qiviut cortisol and various intrinsic (sex, age, body condition and incisor breakage) and extrinsic biotic factors (lungworm and gastrointestinal parasite infections and exposure to bacteria), as well as broader non-specific landscape and temporal features (geographical location, season and year). A Bayesian approach, which allows for the joint estimation of missing values in the data and model parameters estimates, was applied for the statistical analyses. The main findings include the following: (i) higher qiviut cortisol levels in males than in females; (ii) inter-annual variations; (iii) higher qiviut cortisol levels in a declining population compared to a stable population; (iv) a negative association between qiviut cortisol and marrow fat percentage; (v) a relationship between qiviut cortisol and the infection intensity of the lungworm Umingmakstrongylus pallikuukensis, which varied depending on the geographical location; and (vi) no association between qiviut cortisol and other pathogen exposure/infection intensity metrics. This study confirmed and further identified important sources of variability in qiviut cortisol levels, while providing important insights on the relationship between GC levels and pathogen exposure/infection intensity. Results support the use of qiviut cortisol as a tool to monitor temporal changes in HPA axis activity at a population level and to inform management and conservation actions.

Optimal Suture Bite Size for Closure of Feline Linea Alba-A Cadaveric Study.

Objective: This study aimed to determine the most appropriate suture bite and stitch interval (SBSI) size for closing feline linea alba. Study design: Randomized ex vivo mechanical testing. Sample population: Ventral abdominal walls from 35 male feline cadavers were harvested and separated into 125 segments. Methods: Segments were incised along midline then sutured back together using 3-0 polydioxanone using one of the following SBSI: 3, 5, 7.5, or 10 mm whereby the distance represents the distance both between the suture bites, and from the bite to incision line. The location of segments as well as the weight of the cadaver were recorded. A single linear distraction mechanical breaking test was performed. Statistical analyses (logistic and linear regression) were performed to determine which factors were associated with visual and mechanical failure, as well as load at failure or maximum displacement. Results: SBSI was significantly associated with load at failure or maximum displacement (p < 0.001). In particular, 5 mm SBSI had the highest load at failure amongst all the bite sizes (LSmeans = 27.55N, 95% Confidence Interval (CI): 23.65-31.44); this was significantly higher than 7.5 mm (LSmeans = 19.15N, 95% CI: 15.26-23.05, p = 0.016) and 10 mm (LSmeans = 16.55N, 95%CI:12.39-20.70, p = 0.0012) but not significantly higher than 3 mm (LSmeans = 23.78N, 95% CI: 19.69-27.86, p = 0.2). Increased SBSI increased the odds of visual failure (p < 0.001) whereas increased weight of the cadaver reduced the odds of visual failure (OR = 0.52, 95%CI: 0.30-0.88, p = 0.016). Conclusion: The 5 mm SBSI had the highest load at failure and was not significantly different from the 3 mm SBSI when apposing feline linea alba using 3-0 polydioxanone. Clinical significance: Using 5 mm SBSI is the preferred bite size compared to 7.5 or 10 mm SBSI when apposing feline linea alba with 3-0 polydioxanone.

Intra- and inter-rater agreement for the detection of band neutrophils and toxic change in horses.

BACKGROUND: The detection of band neutrophils and toxic change via microscopic blood smear review is vitally important, as their presence indicates systemic inflammation. However, in-clinic evaluation of WBC morphology is often limited. OBJECTIVE: We aimed to determine the agreement between expert raters in the detection of bands and toxic change. METHODS: Three board-certified clinical pathologists each evaluated 109 blood smears from horses with acute disease, and 19 control smears from healthy horses. The pathologists determined if bands were present, and if so, the percentage of bands present. They also determined if toxic change was present, and if so, the grade of toxic change. Intra-rater agreement was evaluated using 12 duplicate blood smears. Agreement on the presence of bands between pathologists and an in-clinic hematology analyzer was evaluated. RESULTS: Intra-rater agreement was substantial to almost perfect. Agreement between pathologists for the detection of bands was moderate, but when pathologists agreed bands were present, there was excellent agreement on the percentage of bands and mature neutrophils. Agreement between pathologists for the detection of high-grade, clinically relevant toxic change was fair. When pathologists agreed high-grade toxic change was present, there was fair agreement on Döhle bodies and cytoplasmic basophilia and poor agreement on cytoplasmic vacuolation. Agreement between individual pathologists and the in-clinic hematology analyzer for the indication of bands was fair to moderate. CONCLUSIONS: Consistent identification of bands and toxic change is challenging, even for highly trained personnel. It is, thus,not surprising that in-clinic blood smear evaluation of WBC morphology by non-experts could be inadequate.

Assessment of two methods to determine the relative contributions of the aerobic and anaerobic energy systems in racehorses.

A prospective, randomized, controlled study was designed to determine relative aerobic and anaerobic (lactic and alactic) contributions at supramaximal exercise intensities using two different methods. Thoroughbred racehorses (n = 5) performed a maximal rate of oxygen consumption (V̇o2max) test and three supramaximal treadmill runs (105, 115, and 125% V̇o2max). Blood lactate concentration (BL) was measured at rest, every 15 s during runs, and 2, 5, 10, 20, 30, 40, 50, and 60 min postexercise. In method 1, oxygen demand was calculated for each supramaximal intensity based on the V̇o2max test, and relative aerobic and anaerobic contributions were calculated from measured V̇o2 and the accumulated oxygen deficit. In method 2, aerobic contribution was calculated using the trapezoidal method to determine V̇o2 during exercise. A monoexponential model was fitted to the postexercise V̇o2 curve. Alactic contribution was calculated using the coefficients of this model. Lactate anaerobic contribution was calculated by multiplying the peak to resting change in BL by 3. Linear mixed-effects models were used to examine the effects of exercise intensity and method (as fixed effects) on measured outcomes (P ≤ 0.05). Relative aerobic and anaerobic contributions were not different between methods (P = 0.20). Horses' mean contributions were 81.4, 77.6, and 72.5% (aerobic), and 18.5, 22.3, and 27.4% (anaerobic) at 105, 115, and 125% V̇o2max, respectively. Individual alactic anaerobic energy was not different between supramaximal exercise intensities (P = 0.43) and was negligible, contributing a mean of 0.11% of the total energy. Relative energy contributions can be calculated using measured V̇o2 and BL in situations where the exercise intensity is unknown. Understanding relative metabolic demands could help develop tailored training programs. NEW & NOTEWORTHY Relative energy contributions of horses can be calculated using measured V̇o2 and BL in situations where the exercise intensity is unknown. Horses' mean contributions were 81.4, 77.6, and 72.5% (aerobic), and 18.5, 22.3, and 27.4% (anaerobic) at 105, 115, and 125% of V̇o2max, respectively. Individual alactic capacity was unaltered between supramaximal exercise intensities and accounted for a mean contribution of 0.11% of energy use.

Blood concentration of bupivacaine and duration of sensory and motor block following ultrasound-guided femoral and sciatic nerve blocks in dogs.

Peripheral nerve blocks are becoming increasingly popular for perioperative use as anesthetics and analgesics in small animals. This prospective study was performed to investigate the duration of motor and sensory blockade following use of bupivacaine for ultrasound-guided femoral and sciatic nerve blocks in dogs and to measure the plasma concentrations of bupivacaine that result from these procedures. Six dogs were anesthetized twice using a randomized cross-over design. At the first anesthetic, dogs were assigned to receive either an ultrasound-guided femoral nerve block or sciatic nerve block with 0.15 mL kg-1 of bupivacaine 0.5%. Two months later, the other nerve block was performed during a second anesthetic. At 5, 10, 15, 20, 30 and 60 minutes after injection, arterial blood samples were collected for laboratory measurement of bupivacaine. After 60 minutes, dogs were recovered from anesthesia. Starting at two hours post-injection, video-recordings of the dogs were made every two hours for 24 hours. The videos were randomized and the degree of motor and sensory blockade was evaluated using a three-point scoring system (0 = no effect, 1 = mild effect, 2 = complete blockade) by two blinded assessors. The median (range) times to full recovery from motor blockade were 11 (6-14) hours (femoral) and 12 (4-18) hours (sciatic), and 15 (10-18) hours (femoral) and 10 (4-12) hours (sciatic) for sensory blockade. There were no differences in the median times to functional recovery for the two techniques. Plasma concentrations of bupivacaine were no different following the blocks and were less than 0.78 µg mL-1 at all times. These results suggest that these ultrasound-guided nerve blocks do not result in potentially toxic systemic levels of local anesthetic and that their duration of action is useful for providing anesthesia and analgesia for pelvic limb procedures.

Comparison of the risks of atherosclerotic events versus death from other causes associated with antiretroviral use.

BACKGROUND: Studies considering the risk of atherosclerotic disease (AtD) associated with the use of HAART have reported inconsistent results. METHODS: Data on antiretroviral therapy (ART) use, risk factors for cardiovascular disease (CVD), AtD and death from other causes in 18 603 HIV-infected patients from two established cohorts were evaluated. The relative hazards of AtD and death from other causes were calculated using a proportional hazards competing risks framework. The impact of protease inhibitor (PI)-containing, non-nucleoside reverse transcriptase inhibitor (NNRTI)-containing or PI + NNRTI-containing regimens on these outcomes were compared to nucleoside reverse transcriptase inhibitor (NRTI)-only regimens or stopping therapy, adjusting for known CVD risk factors. RESULTS: In 77 480 person-years of follow-up (median duration 3.49 years) there were 318 AtD events including 92 myocardial infarctions and 2044 deaths. Older age, hypertension, diabetes mellitus, having smoked and HIV disease stage were significantly associated with increased risk of AtD. PI- and NNRTI-containing regimens significantly reduced the joint risk of either AtD or death from other causes compared to NRTI-only or stopping therapy [hazard ratio (HR) for PI-containing ART, 0.76, 95% confidence interval (CI), 0.73-0.78, P< 0.001; NNRTI-containing ART, 0.69, 95% CI, 0.65-0.74; P< 0.001). PI-containing ART was associated with a borderline significant increased risk of myocardial infarction (cause-specific HR for PI-containing ART 1.19, 95% CI, 1.01-1.40, P = 0.04) but not with increased risk of AtD compared to NRTI-only regimens or stopping therapy (cause-specific HR for PI-containing ART, 1.03, 95% CI, 0.95-1.13, P = 0.44). CONCLUSIONS: Overall benefits of PI- and NNRTI-based ART in reducing mortality significantly outweigh any risks of AtD in the "short-term" follow-up of this study. Traditional cardiac risk factors play an important role in determining AtD risk status.

Parameterizing Spatial Models of Infectious Disease Transmission that Incorporate Infection Time Uncertainty Using Sampling-Based Likelihood Approximations.

A class of discrete-time models of infectious disease spread, referred to as individual-level models (ILMs), are typically fitted in a Bayesian Markov chain Monte Carlo (MCMC) framework. These models quantify probabilistic outcomes regarding the risk of infection of susceptible individuals due to various susceptibility and transmissibility factors, including their spatial distance from infectious individuals. The infectious pressure from infected individuals exerted on susceptible individuals is intrinsic to these ILMs. Unfortunately, quantifying this infectious pressure for data sets containing many individuals can be computationally burdensome, leading to a time-consuming likelihood calculation and, thus, computationally prohibitive MCMC-based analysis. This problem worsens when using data augmentation to allow for uncertainty in infection times. In this paper, we develop sampling methods that can be used to calculate a fast, approximate likelihood when fitting such disease models. A simple random sampling approach is initially considered followed by various spatially-stratified schemes. We test and compare the performance of our methods with both simulated data and data from the 2001 foot-and-mouth disease (FMD) epidemic in the U.K. Our results indicate that substantial computation savings can be obtained--albeit, of course, with some information loss--suggesting that such techniques may be of use in the analysis of very large epidemic data sets.

Relationship of oxidative stress in skeletal muscle with obesity and obesity-associated hyperinsulinemia in horses.

In horses, hyperinsulinemia and insulin resistance (insulin dysregulation) are associated with the development of laminitis. Although obesity is associated with insulin dysregulation, the mechanism of obesity-associated insulin dysregulation remains to be established. We hypothesized that oxidative stress in skeletal muscle is associated with obesity-associated hyperinsulinemia in horses. Thirty-five light breed horses with body condition scores (BCS) of 3/9 to 9/9 were studied, including 7 obese, normoinsulinemic (BCS ≥ 7, resting serum insulin < 30 µIU/mL) and 6 obese, hyperinsulinemic (resting serum insulin ≥ 30 µIU/mL) horses. Markers of oxidative stress (oxidative damage, mitochondrial function, and antioxidant capacity) were evaluated in skeletal muscle biopsies. A Spearman's rank correlation coefficient was used to determine relationships between markers of oxidative stress and BCS. Furthermore, to assess the role of oxidative stress in obesity-related hyperinsulinemia, markers of antioxidant capacity and oxidative damage were compared among lean, normoinsulinemic (L-NI); obese, normoinsulinemic (O-NI); and obese, hyperinsulinemic (O-HI) horses. Increasing BCS was associated with an increase in gene expression of a mitochondrial protein responsible for mitochondrial biogenesis (estrogen-related receptor alpha, ERRα) and with increased antioxidant enzyme total superoxide dismutase (TotSOD) activity. When groups (L-NI, O-NI, and O-HI) were compared, TotSOD activity was increased and protein carbonyls, a marker of oxidative damage, decreased in the O-HI compared to the L-NI horses. These findings suggest that a protective antioxidant response occurred in the muscle of obese animals and that obesity-associated oxidative damage in skeletal muscle is not central to the pathogenesis of equine hyperinsulinemia.

Chez les chevaux l'hyperinsulinémie et la résistance à l'insuline (dérèglement de l'insuline) sont associées avec le développement de fourbure. Bien que l'obésité soit associée avec le dérèglement de l'insuline, le mécanisme de l'obésité associée au dérèglement de l'insuline demeure à être établi. Nous émettons l'hypothèse que le stress oxydatif dans les muscles squelettiques est associé avec l'obésité associée à l'hyperinsulinémie chez les chevaux. Trente-cinq chevaux de races légères avec des pointages de conditions corporelles (PCC) de 3/9 à 9/9 ont été étudiés, incluant sept chevaux obèses, normo-insulinémique (PCC ≥ 7, insuline sérique au repos < 30 µIU/mL) et six chevaux obèses, hyperinsulinémique (insuline sérique au repos ≥ 30 µIU/mL). Les marqueurs de stress oxydatif (damage oxydatif, fonction mitochondriale, et capacité antioxydante) furent évalués dans des biopsies de muscles squelettiques. Un coefficient de corrélation de rang de Spearman a été utilisé pour déterminer la relation entre les marqueurs de stress oxydatif et le PCC. De plus, pour évaluer le rôle du stress oxydatif dans l'obésité reliée à l'hyperinsulinémie, les marqueurs de la capacité anti-oxydante et des dommages oxydatifs ont été comparés entre des chevaux minces, normo-insulinémiques (L-NI); des chevaux obèses, normo-insulinémique (O-NI); et des chevaux obèses, hyperinsulinémiques (O-HI). Une augmentation des PCCs était associée avec une augmentation de l'expression des gènes d'une protéine mitochondriale responsable de la biogénèse des mitochondries (récepteur alpha apparenté aux estrogènes, ERRα) et d'une augmentation de l'activité anti-oxydante totale de l'enzyme superoxyde dismutase (TotSOD). Lors de la comparaison des groupes (L-NI, O-NI, et O-HI), l'activité TotSOD était augmentée et les carbonyles protéiques, un marqueur des dommages oxydatifs, avaient diminué chez les chevaux O-HI comparativement aux chevaux L-NI. Ces données suggèrent qu'une réponse anti-oxydante protectrice s'est produite dans le muscle des chevaux obèses et que le dommage oxydatif associés à l'obésité dans les muscles squelettiques n'est pas central à la pathogénèse de l'hyperinsulinémie équine.(Traduit par Docteur Serge Messier).