bluuebunny/crossref_metadata_2025 huggingface dataset:
In search of the big fish: Investigating the coexistence of the big‐fish‐little‐pond effect with the positive effects of upward comparisons
Authors: Seaton Marjorie , Marsh Herbert W. , Dumas Florence , Huguet Pascal , Monteil Jean‐Marc , Régner Isabelle , Blanton Hart , Buunk Abraham P. , Gibbons Frederick X. , Kuyper Hans , Suls Jerry , Wheeler Ladd
Published: April 2007

Blanton, Buunk, Gibbons, and Kuyper (1999) and Huguet, Dumas, Monteil, and Genestoux (2001) found that children nominated a social comparison target who slightly outperformed them in class with a beneficial effect on course grades – an assimilation effect, but with no effects on self‐evaluation. However, big‐fish‐little‐pond effect (BFLPE) research has shown that attending a high‐ability school has a negative effect on academic self‐concept – a contrast effect. To resolve this apparent conflict, the present investigation (1) tested the BFLPE in the Netherlands and France, using nationally representative samples (Study 1) and (2) further analysed (using more sophisticated analyses) the Dutch (Blanton et al.) study (Study 2) and the French (Huguet et al.) study including new French data (Study 3), to examine whether the BFLPE coexisted with, or was moderated by, the beneficial impact of upward comparisons. In support of the BFLPE, all studies found the negative effects of school‐ or class‐average ability on self‐evaluation, demonstrating that these assimilation and contrast effects can coexist.
Study of Gas/Condensate Reservoir Exploitation Using Neurosimulation
Authors: Ayala Luis F. , Ertekin Turgay , Adewumi Michael
Published: April 2007

Gas/condensate reservoirs have been the subject of intensive research throughout the years because they represent an important class of the world's hydrocarbon reserves. Their exploitation for maximum hydrocarbon recovery involves additional complexities that cast them as a different class of reservoirs, apart from dry-gas, wet-gas, and oil reservoirs. Gas/condensate reservoirs are good candidates for compositional-simulation studies because their depletion performance is highly influenced by changes in fluid composition. Often, highly sophisticated and computationally intensive compositional simulations are needed for the accurate modeling of their performance, phase behavior, and fluid-flow characteristics. The desired outcome of a simulation study for gas/condensate reservoirs is the identification and development of the best operational production schemes that maximize hydrocarbon recovery with a minimum loss of condensate at reservoir conditions. However, compositional simulations are demanding in terms of computational overhead, manpower, and software and hardware requirements. Artificial-neural-network (ANN) technology (soft-computing) has proved instrumental in establishing expert systems capable of learning the existing vaguely understood relationships between the input parameters and output responses of highly sophisticated hard-computing protocols such as compositional simulation of gas/condensate reservoirs. In this study, we conduct parametric studies that identify the most influential reservoir and fluid characteristics in the establishment of optimum production protocols for the exploitation of gas/condensate reservoirs. During the training phase of the ANN, an internal mapping is created that accurately estimates the corresponding output for a range of input parameters. In this paper, a powerful screening and optimization tool for the production of gas/condensate reservoirs is presented. This tool is capable of screening the eligibility of different gas/condensate reservoirs for exploitation as well as assisting in designing the optimized exploitation scheme for a particular reservoir under consideration for development.
The Effect of Wettability and Pore Geometry on Foamed-Gel-Blockage Performance
Authors: Romero-Zerón Laura , Kantzas Apostolos
Published: April 2007

Excessive gas and/or water production is a common problem encountered throughout the lifetime of oil-producing wells. High-producing gas/oil or water/oil ratios are normally responsible for both rapid productivity decline and increased operating costs caused by gas or water processing. The result is often a premature shut-in of wells because production has become uneconomical. Foamed gels have been used as selective barriers to counteract disproportionate gas/oil and/or water/oil ratios in oil production. However, research on the effects of critical parameters such as wettability of the porous medium and pore geometry on foamed-gel-blockage performance remains incomplete.

In this work, microscale experiments, which involve the magnified observation of flowing and trapped foamed gel in etched-glass micromodels, were performed. The purpose of this research is to provide new insights into the sensitivity of foamed-gel-blockage performance as a function of porous-media wettability (strongly water-wet or strongly oil-wet systems) and pore geometry.

The experimental results indicate that foamed gels presented higher blocking efficiency in strongly oil-wet systems than in strongly water-wet systems. Under these experimental conditions, foamed gels exhibited higher blocking efficiency at lower pore-body-/pore-throat-size aspect ratios. The plugging treatment exhibited stability after subsequent steps of gas and brine injection. Ultimately, these results indicate that the combination of foam and gel systems has technical advantages that make foamed gels superior mobility-control and plugging agents.
Understanding Neuroimaging
Authors: Kimberley Teresa Jacobson , Lewis Scott M
Published: April 2007

Neuroimaging is an emergent method of investigation for studying the human brain in healthy and impaired populations. An increasing number of these investigations involve topics important to rehabilitation. Thus, a basic understanding of the more commonly used neuroimaging techniques is important for understanding and interpreting this growing area of research. Included in this article is a description of the signal source, the advantages and limitations of each technique, considerations for study design, and how to interpret cortical imaging data. Particular emphasis is placed on functional magnetic resonance imaging because of its ubiquitous presence in rehabilitation research.
Answering the Call: The Influence of Neuroimaging and Electrophysiological Evidence on Rehabilitation
Authors: Boyd Lara A , Vidoni Eric D , Daly Janis J
Published: April 2007

Functional recovery after brain damage or disease is dependent on the neuroplastic capability of the cortex and the nonaffected brain. Following cortical injury in the motor and sensory regions, the adjacent spared neural tissues and related areas undergo modifications that are required in order to drive more normal motor control. Current rehabilitation models seek to stimulate functional recovery by capitalizing on the inherent potential of the brain for positive reorganization after neurological injury or disease. This article discusses how neuroimaging and electrophysiological data can inform clinical practice; representative data from the modalities of functional magnetic resonance imaging, diffusion tensor imaging, magnetoencephalography, electroencephalography, and positron emission tomography are cited. Data from a variety of central nervous system disease and damage models are presented to illustrate how rehabilitation practices are beginning to be shaped and informed by neuroimaging and electrophysiological data.
Use of Imaging to Assess Normal and Adaptive Muscle Function
Authors: Segal Richard L
Published: April 2007

Physical therapists must be able to determine the activity and passive properties of the musculoskeletal system in order to accurately plan and evaluate therapeutic measures. Discussed in this article are imaging methods that not only allow for the measurement of muscle activity but also allow for the measurement of cellular processes and passive mechanical properties noninvasively and in vivo. The techniques reviewed are T1- and T2-weighted magnetic resonance (MR) imaging, MR spectroscopy, cine–phase-contrast MR imaging, MR elastography, and ultrasonography. At present, many of these approaches are expensive and not readily available in physical therapy clinics but can be found at medical centers. However, there are ways of using these techniques to provide important knowledge about muscle function. This article proposes creative ways in which to use these techniques as evaluative tools.
Study of intragastric administration of doxycycline: pharmacokinetics including body fluid, endometrial and minimum inhibitory concentrations
Authors: Bryant J. E. , Brown M. P. , Gronwall R. R. , Merritt K. A.
Published: April 2007

The objectives of this study were to determine the pharmacokinetics and tissue concentrations of doxycycline after repeated intragastric administration, and to determine the minimum inhibitory concentrations (MIC) for equine pathogenic bacteria. Inexperiment 1, 2 mares received a single intragastric dose of doxycycline hyclate (3 mg/kg bwt). Mean peak serum concentration was 0.22 μg/ml 1 h postadministration. Inexperiment 2, 5 doses of doxycycline hyclate (10 mg/kg bwt), dissolved in water, were administered to each of 6 mares via nasogastric tube at 12 h intervals. The mean ± s.e. peak serum doxycycline concentration was 0.32 ± 0.16 μg/ml 1 h after the first dose and 0.42 ± 0.05 μg/ml 2 h after the fifth dose. The mean trough serum concentrations were ≥ 0.16 μg/ml. Highest mean synovial concentration was 0.46 ± 0.13 μg/ml and highest mean peritoneal concentration was 0.43 ± 0.07 μg/ml, both 2 h after the fifth dose. Highest urine concentration was mean ± s.e. 145 ± 25.4 μg/ml 2 h after the last dose. Highest endometrial concentration was mean ± s.e. 1.30 ± 0.36 μg/ml 3 h after the fifth dose. Doxycycline was not detected in any of the CSF samples. Mean ± s.e. Vdareawas 25.3 ± 5.0 l/kg and mean t1/2was 8.7 ± 1.6 h. Inexperiment 3, minimum inhibitory concentrations of doxycycline were determined for 168 equine bacterial culture specimens. The MIC90was ≤ 1.0 μg/ml forStreptococcus zooepidemicusand 0.25 μg/ml forStaphylococcus aureus.Based on drug concentrations achieved in the serum, synovial and peritoneal fluids and endometrial tissues and MIC values determined in the present study, doxycycline at a dose of 10 mg/kg bwtper osevery 12 h may be appropriate for the treatment of infections caused by susceptible (MIC ≤ 0.25 μg/ml) Gram‐ positive organisms in horses.
Influence of bacitracin on microbial functions in the gastrointestinal tract of horses
Authors: Collinder E. , Berge G. N. , Grønvold B. , Lindholm A. , Midtvedt T. , Norin E.
Published: April 2007

This study investigated the influence of zinc bacitracin on the intestinal flora of horses. The functionally active intestinal flora was examined in 6 horses during treatment with zinc bacitracin. Utilising gas chromatography, spectrophotometry, gel electrophoresis and paper chromatography, samples were analysed on biochemical markers reflecting the action of parts of the intestinal flora. The following 5 flora‐related functions were studied in faecal samples and intestinal samples from different sections of the hindgut: conversion of cholesterol to coprostanol and of bilirubin to urobilinogens, degradation of mucin and of β‐aspartylglycine and inactivation of tryptic activity. Conversion to coprostanol, conversion to urobilinogens and degradation of mucin were affected by treatment of zinc bacitracin and conversion to coprostanol was most sensitive. All functions were normalised in a short time, in contrast to man and rats. Differences in environmental exposures are probably the reason for a more rapid normalisation of the intestinal flora functions in horses.
The forelimb in walking horses: 2. Net joint moments and joint powers
Authors: Clayton H. M. , Hodson E. , Lanovaz J. L.
Published: April 2007

The objective was to measure the net joint moments and joint powers for the joints of the equine forelimb during the walk. Videographic and force data were combined with morphometric information using an inverse dynamics method. During stance phase the predominant joint moment was on the palmar aspect of all forelimb joints except the shoulder, where the peak moment was considerably higher than at any other joint. The entire forelimb showed net energy absorption in both stance and swing phases. The elbow was the only joint that showed net generation of energy, which was used to maintain the limb in extension in early stance as the horse's body vaults over the limb and to drive protraction and retraction of the limb during swing. The carpus aligned the limb into a supportive strut, but did not play an important role in energy absorption or generation. A small burst of positive work on the flexor aspect at the start of breakover indicated that the carpus played an active role in initiating breakover during walking. The fetlock functioned elastically to store and release strain energy during stance. The coffin joint acted as an energy damper during most of stance with a small burst of energy generation on the flexor aspect as the joint flexed during breakover. The magnitude of the peak joint power during swing decreased in a proximal to distal sequence. It is concluded that the elbow joint is the main site of energy generation. The shoulder and coffin joints act as energy dampers during stance. The distal joints had very low joint powers and appeared to be driven by inertial forces during the swing phase. This information will be applied to derscribe how horses compensate for different lamenesses in terms of redistributing the functions of energy generation and absorption between joints.
Effect of water restriction on equine behaviour and physiology
Authors: Houpt K. A. , Eggleston A. , Kunkle K. , Houpt T. R.
Published: April 2007

Six pregnant mares were used to determine what level of water restriction causes physiological and/or behavioural changes indicative of stress. Nonlegume hay was fedad libitum.During the first week of restriction, 5 l water/100 kg bwt was available, during the second week 4 l/100 kg bwt and, during the third week, 3 l/100 kg bwt.Ad libitumwater intake was 6.9 l/100 kg bwt; at 3 l/100 kg bwt water intake was 42% of this. Daily hay intake fell significantly with increasing water restriction from 12.9 ± 0.75 kg to 8.3 ± 0.54 kg; bodyweight fell significantly for a total loss of 48.5 ± 8.3 kg in 3 weeks.

Daily blood samples were analysed; osmolality rose significantly with increasing water restriction from 282 ± 0.7 mosmols/kg to 293.3 ± 0.8 mosmols/kg bwt, but plasma protein and PCV did not change significantly. Cortisol concentrations fell from 8.1 ng/ml to 6.4 ng/ml over the 3 week period. Aldosterone fell from 211.3 ± 74.2 pg/ml to 92.5 ± 27.5 pg/ml at the end of the first week. The behaviour of 4 of the 6 mares was recorded 24 h/day for the duration of the study. The only significant difference was in time spent eating, which decreased with increasing water restriction from 46 ± 3% to 30 ± 3%. It is concluded that water restriction to 4 l/100 kg bwt dehydrates pregnant mares and may diminish their welfare, but is not life‐ or pregnancy‐threatening.
The effects of frusemide on racing times of Standardbred pacers
Authors: Soma L. R. , Birks E. K. , Uboh C. E. , May L. , Teleis D. , Martini J.
Published: April 2007

Seven hundred and eighty‐eight Standardbred pacers competing in 8378 races at one racetrack were analysed to determine the effects of the administration of prerace frusemide on racing times (RT). Frusemide was administered i.v. 4 h before the race to pacers diagnosed with exercise‐induced pulmonary haemorrhage (EIPH). Of the pacers, starting in the 1997 racing season, 32.5% received prerace frusemide. This study demonstrated that administration of frusemide prior to racing significantly decreased RT. There was an overall significant decrease (P<0.00001) in RT of 0.67 s. The overall RT for horses, geldings, and females, were mean ± s.e 117.91 ± 0.06, 118.20 ± 0.03 and 118.86 ± 0.04, respectively. RT progressively decreased until age 6 and increased thereafter. Horses, geldings and females ran a mean of 0.46, 0.31 and 0.74 s faster, respectively, with prerace administration of frusemide. This decrease in RT following prerace administration was most pronounced in younger pacers. In this study, a greater percentage of older pacers received prerace frusemide; however, the effect of frusemide on RT was decreasing with age.

Prerace venous acid‐base screening was performed in 2729 of the pacers competing. Pennsylvania Harness Racing Commission Regulations disqualify Standardbreds from racing with a base excess of over 10 and 12 mmol/l for Standardbreds without and with prerace administration of frusemide. The prerace venous acid‐base levels were not significantly related to RT and, forthose Standardbreds also sampled following the race, there was no correlation between pre‐ and postrace acid‐base status.
A comparison of the haemodynamic effects of isoflurane and halothane anaesthesia in horses
Authors: Raisis A. L. , Young L. E. , Blissitt K. J. , Brearley J. C. , Meire H. B. , Taylor P. M. , Lekeux P.
Published: April 2007

The purpose of this study was to compare the haemodynamic effects of equipotent isoflurane and halothane anaesthesia. Six adult horses were investigated on two separate occasions at least 4 weeks apart. On both occasions anaesthesia was induced by ketamine 2.2 mg/kg bwt given 5 min after i.v. administration 100 μg/kg bwt romifidine. Anaesthesia was maintained either by halothane or isoflurane (end‐tidal concentrations 0.9–1.0% and 1.3–1.4%, respectively). Horses were ventilated by intermittent positive pressure to maintain PaCO2between 40–50 mmHg. Haemodynamic variables were measured using catheter‐mounted strain gauge transducers in the left and right ventricle, aorta, and right atrium. Cardiac output (CO), velocity time integral (VTI), maximal aortic blood flow velocity (Vmax) and acceleration (dv/dtmax), left ventricular pre‐ejection period (PEP) and ejection time (ET) were measured from aortic blood flow velocity waveforms obtained by transoesophageal Doppler echocardiography. Flow velocity waveforms were recorded from the femoral arteries and veins using low pulse repetition frequency Doppler ultrasound. Time‐averaged mean velocity (TAV), velocity of component a (TaVa), velocity of component b (TaVb) and early diastolic deceleration slope (EDDS) were measured. Pulsatility index (PI) and volumetric flow were calculated. Microvascular blood flow was measured in the left and right semimembranosus muscles by laser Doppler flowmetry.

Maximal rate of rise of LV pressure (LVdp/dtmax), CO, Vmax, dv/dtmax, ET, VTI were significantly higher at all time points during isoflurane anaesthesia compared to halothane anaesthesia. Pre‐ejection period and diastolic aortic blood pressure were significantly less throughout isoflurane anaesthesia compared to halothane. Isoflurane anaesthesia was associated with significantly lower systemic vascular resistance than halothane anaesthesia. Femoral arterial and venous blood flow were significantly higher and EDDS and PI were significantly lower during isoflurane anaesthesia compared to halothane anaesthesia. In addition during both halothane and isoflurane anaesthesia, femoral arterial flow was higher and EDDS and PI lower in the left (dependent) artery compared to the right (nondependent) artery.

This study supports previous work demonstrating improved left ventricular systolic function during isoflurane compared to halothane anaesthesia. This improvement was still evident after premedication with a potent‐long acting α2‐adrenoreceptor agonist, romifidine, and induction of anaesthesia with ketamine. There was also evidence of increased hindlimb blood flow during isoflurane anaesthesia. However, there were differences observed in flow between the left and right hindlimb during maintenance of anaesthesia with each agent, suggesting that there were differences in regional perfusion in anaesthetised horses caused by factors unrelated to agents administered.
Clenbuterol administration does not attenuate the exercise‐induced pulmonary arterial, capillary or venous hypertension in strenuously exercising Thoroughbred horses
Authors: MANOHAR M. , GOETZ T. E. , ROTHENBAUM P. , HUMPHREY S.
Published: April 2007

The present study was carried out to ascertain whether β2‐adrenergic receptor stimulation with clenbuterol would attenuate the pulmonary arterial, capillary and venous hypertension in horses performing high‐intensity exercise and, in turn, modify the occurrence of exercise‐induced pulmonary haemorrhage (EIPH). Experiments were carried out on 6 healthy, sound, exercise‐trained Thoroughbred horses. All horses were studied in the control (no medications) and the clenbuterol (0.8 μg/kg bwt, i.v.) treatments. The sequence of these treatments was randomised for every horse, and 7 days were allowed between them. Using catheter‐tip‐transducers whosein‐vivosignals were referenced at the point of the left shoulder, right heart/pulmonary vascular pressures were determined at rest, sub‐maximal exercise and during galloping at 14.2 m/s on a 3.5% uphill grade ‐ a workload that elicited maximal heart rate and induced EIPH in all horses. In the control experiments, incremental exercise resulted in progressive significant increments in right atrial as well as pulmonary arterial, capillary and venous (wedge) pressures and all horses experienced EIPH. Clenbuterol administration to standing horses caused tachycardia, but significant changes in mean right atrial or pulmonary vascular pressures were not observed. During exercise performed after clenbuterol administration, heart rate as well as right atrial and pulmonary arterial, capillary and wedge pressures also increased progressively with increasing work intensity. However, these values were not found to be statistically significantly different from corresponding data in the control study and the incidence of EIPH remained unaffected. Since clenbuterol administration also does not affect the transpulmonary pressure during exercise, it is unlikely that the transmural force exerted onto the blood‐gas barrier of exercising horses is altered following i.v. clenbuterol administration at the recommended dosage.
The influence of strenuous exercise on collagen characteristics of articular cartilage in Thoroughbreds age 2 years
Authors: BRAMA P. A. J. , TEKOPPELE J. M. , BANK R. A. , BARNEVELD A. , FIRTH E. C. , WEEREN P. R. van
Published: April 2007

In order to assess the influence of strenuous exercise on collagen characteristics of articularcartilage, the response of the collagen network was studied in seven 2‐year‐old Thoroughbreds subjected to strenuous exercise compared to 7 nontrained individuals. After 13 weeks, the animals were subjected to euthanasia, fetlock joints of the forelimbs were scored macroscopically after Indian Ink staining, and articular cartilage from different locations of the articular surface of the proximal first phalanx was sampled and analysed for water content, collagen content, hydroxylysine content and amount of hydroxylysylpyridinoline (HP) crosslinks. Gross lesions were significantly more severe in the exercised than in the nonexercised group. In the control animals, the characteristic site‐specific differences in collagen parameters were found as described earlier, but in the strenuously exercised animals this physiological biochemical heterogeneity had disappeared. In the exercised animals, an increase in water content and a sharp decrease in HP crosslinking was found that was correlated with the presence of wear lines. It is concluded that the strenuous exercise provoked significant alterations in the characteristics of the collagen network of the articular cartilage of the fetlock joint which were suggestive of microdamage and loosening of the collagen network. The collagen component of cartilage, in contrast to the proteoglycan component, is known to have a very limited capacity for repairand remodelling due to an extremely low turnover rate. Therefore, alterations within the articular collagen network might be expected to play an important role in the pathophysiology of degenerative joint disorders.
Evidence for surfactant contributing to the gastric mucosal barrier of the horse
Authors: ETHELL M. T. , HODGSON D. R. , HILLS B. A.
Published: April 2007

This study was undertaken to determine the hydrophobicity of the luminal surface of the equine stomach and to elucidate the ultrastructure of the lining imparting that property. Gastric and duodenal mucosal samples from 5 horses were collected immediately after euthanasia and subjected to surface contact angle measurement using a goniometer. Gastric mucosal samples from 4 horses and a foal were examined by electron microscopy following a fixation procedure known to preserve phospholipids and oligolamellar structures. Contact angles for the equine gastric glandular mucosal surface (mean ± s.e. 78.0 ± 11.0°) were greater than for the duodenum (33.4 ± 8.7°), (P = 0.003). The contact angles for gastric squamous tissue (50.4 ± 4.5°) tended to be greater than for duodenum (P = 0.15). Electron microscopy revealed the existence of surfactant as abundant osmiophilic phospholipid material within both squamous and glandular gastric mucosae. These results indicate the hydrophobic nature of the equine gastric mucosae. We propose that the water‐repellent nature of the stomach contributes to the ‘gastric mucosal barrier’ and is imparted by surface‐active phospholipid adsorbed to the surface. Phospholipids may also be utilised as a physical barrier to back‐diffusion of acid by lining intracellular canaliculi and oxyntic ducts where other defence mechanisms are absent.
Elimination of guttural pouch infection and inflammation in asymptomatic carriers ofStreptococcus equi
Authors: VERHEYEN K. , NEWTON J. R. , TALBOT N. C. , BRAUWERE M. N. de , CHANTER N.
Published: April 2007

Three protracted outbreaks of strangles were investigated using endoscopic examination and a total of 14 asymptomatic carriers ofStreptococcus equiwere identified of which 13 showed evidence of carriage in the guttural pouch. Treatment was initiated to eliminateS. equicolonisation since these animals posed an infectious risk to susceptible horses. Two further horses were referred to us with severe guttural pouch pathology and from whichS. equiwas cultured, and treatment of these cases is also described. Treatment in the first instance was directed towards removal of gross guttural pouch pathology as seen on endoscopic examination. This was done with a combination of irrigation of the pouch with moderate to large amounts of saline, suction of fluid material and endoscopic manipulation of chondroids. Subsequently, antibiotic treatment was used to eliminateS. equiinfection. All animals received systemic antibiotics, in some cases combined with topical antimicrobial treatment. Treatment was generally regarded as successful when the guttural pouches appeared normal andS. equiwas not detected in nasopharangeal swabs and pouch lavages on 3 consecutive occasions. Successful treatment of one carrier required surgical intervention due to occlusion of both guttural pouch pharyngeal openings. Fourteen of 15 carriers were successfully treated by endoscopic removal of inflammatory material and antibiotic treatment, without surgical intervention. Five carriers originally given potentiated sulphonamide (33%) required further therapy with penicillin or ceftiofur, administered both systemically and topically, beforeS. equiinfection and associated inflammation of the guttural pouches were eliminated.
Uroperitoneum in the hospitalised equine neonate: retrospective study of 31 cases, 1988–1997
Authors: KABLACK K. A. , EMBERTSON R. M. , BERNARD W. V. , BRAMLAGE L. R. , HANCE S. , REIMER J. M. , BARTON M. H.
Published: April 2007

Historical, physical and diagnostic data were reviewed retrospectively in 31 equine neonates with uroperitoneum. Genderpredilection was not observed, and classic electrolyte abnormalities were seen in less than 50% of the cases. Aetiologies for uroperitoneum have been well described, but this review found that septicaemia/severe illness played a crucial role in the outcome of uroperitoneum. Approximately half the individuals with uroperitoneum had positive sepsis scores. Foals receiving fluid therapy were more likely to be septic and to have normal electrolyte concentrations. Ultrasonographic findings, serum creatinine and serum:peritoneal creatinine ratios were not affected by previous fluid therapy and were invaluable aids in the diagnosis of uroperitoneum, even with multisystemic disease such as sepsis.
Control of strangles outbreaks by isolation of guttural pouch carriers identified using PCR and culture of Streptococcus equi
Authors: NEWTON J. R. , VERHEYEN K. , TALBOT N. C. , TIMONEY J. F. , WOOD J. L. N. , LAKHANI K. H. , CHANTER N.
Published: April 2007

Previous use of repeated nasopharyngeal swabbing and culture of Streptococcus equi showed that healthy carriers developed in more than 50% of ‘strangles’ outbreaks. The guttural pouches were the only detectable site of S. equi colonisation on endoscopic examination of horses during one of these outbreaks and S. equi was sometimes not detected by culture of nasopharyngeal swabs from carriers for up to 2 or 3 months before nasal shedding resumed sporadically. A more sensitive way of detecting S. equi on swabs from established guttural pouch carriers was therefore required. Conveniently selected ‘strangles’ outbreaks were investigated in detail using endoscopy, in order to develop and assess a suitable polymerase chain reaction (PCR) test. We report here 3 protracted ‘strangles’ outbreaks on different kinds of establishments in which between 29 and 52% of sampled horses were infected as detected by culture and/or PCR. Of the infected horses, between 9 and 44% were identified as carrying S. equi after clinical signs had disappeared and the predominant site of carriage was the guttural pouch. Prolonged carriage of S. equi, which lasted up to 8 months, did not cease spontaneously before treatment was initiated to eliminate the infections. The detection and isolation of the carriers, in conjunction with strict hygiene measures, apparently resulted in the control of the outbreaks and allowed the premises to return to normal activity. Comparing PCR and culture, many more swabs were found to be positive using PCR (56 vs. 30% of 61 swabs). Similar results were obtained for guttural pouch samples from 12 established carriers (PCR 76% and culture 59%). These results from repeated samples from relatively few animals need confirming using more long‐term carriers. PCR can also detect dead organisms and is, therefore, liable to yield false positive results. Despite this drawback, it is argued that PCR provides a potentially useful adjunct to culture of nasopharyngeal swabs in the detection of asymptomatic carriers of S. equi following outbreaks of ‘strangles’.
Endotoxin and dietary amines may increase plasma 5‐hydroxytryptamine in the horse
Authors: BAILEY S. R. , CUNNINGHAM F. M. , ELLIOTT J.
Published: April 2007

Uptake of 5‐hydroxytryptamine (5‐HT) into platelets is an important mechanism by which low plasma concentrations are maintained, and platelet activation may therefore result in significant release of this vasoconstrictor. The present study examined the kinetics of active uptake of radiolabelled [3H]5‐HT by washed equine plateletsin vitro, and investigated the effects on this process of 4 other naturally occurring monoamines which may be released from the caecum in conditions of carbohydrate overload. The release of [3H]5‐HT by platelets was also studied, since platelet accumulation and activation has been associated with acute laminitis. Release of [3H]5‐HT was measured in response to platelet activating factor (PAF), unlabelled 5‐HT and the indirect activation of platelets by endotoxin in the presence of blood leucocytes. Kmvalue for the uptake of 5‐HT by equine platelets was 2.4 ± 0.6 μmol/l and the Vmaxwas 8.3 ± 0.6 pmol [3H]5‐HT/107platelets/min. The rate of uptake of 5 μmol/l [3H]5‐HT was significantly decreased by the uptake inhibitors fluvoxamine and clomipramine. The 4 other monoamines examined all inhibited the uptake of [3H]5‐HT in a noncompetitive manner, decreasing Vmaxby between 17 and 82%. Incubation of platelets with LPS (0.1 mg/ml) in the absence of leucocytes did not result in significant release of [3H]5‐HT; however, in the presence of leucocytes 3.8 ± 1.7 pmol [3H]5‐HT/107platelets (mean ± s.e.) were released. This release was significantly inhibited by parthenolide and WEB2086, but not by aspirin. This suggests that PAF from activated leucocytes was responsible for the 5‐HT release. These data show that 5‐HT uptake by equine platelets is a saturable process operating most efficiently at substrate concentrations in the low micromolar range. The noncompetitive inhibition of 5‐HT uptake by other naturally occurring monoamines may result in increased plasma concentrations of 5‐HT, as would its release by endotoxin. Such a rise in plasma 5‐HT concentrations may contribute to selective vasoconstriction in the equine digital circulation.
Equine proliferative enteropathy: a cause of weight loss, colic, diarrhoea and hypoproteinaemia in foals on three breeding farms in Canada
Authors: Lavoie J. P. , Drolet R. , Parsons D. , Leguillette R. , Sauvageau R. , Shapiro J. , Houle L. , HallÉ G. , Gebhart C. J.
Published: April 2007

Proliferative enteropathy (PE) is a transmissible enteric disease caused byLawsonia intracellularis.An outbreak of equine PE was diagnosed in foals from 3 breeding farms. Most foals had been weaned prior to the appearance of clinical signs, which included depression, rapid and marked weight loss, subcutaneous oedema, diarrhoea and colic. Poor body condition with a rough haircoat and a potbellied appearance were common findings in affected foals. Respiratory tract infection, dermatitis and intestinal parasitism were also found in some foals. Haematological and plasma biochemical abnormalities included hypoproteinaemia, transient leucocytosis, anaemia and increased serum creatinine kinase concentration.

Postmortemdiagnosis of PE was confirmed on 4 foals based on the presence of characteristic intracellularbacteria within the apical cytoplasm of proliferating crypt epithelial cells of the intestinal mucosa, using silver stains, and by results of PCR analysis and immunohistochemistry.Antemortemdiagnosis of equine PE was based on the clinical signs, hypoproteinaemia and the exclusion of common enteric infections. Faecal PCR analysis was positive for the presence ofL. intracellularisin 6 of 18 foals tested while the serum of all 7 foals with PE serologically evaluated had antibodies againstL. intracellularis.

Most foals were treated with erythromycin estolate alone or combined with rifampin for a minimum of 21 days. Additional symptomatic treatments were administered when indicated. All but one foal treated with erythromycin survived the infection. This study indicates that equine PE should be included in the differential diagnosis of outbreaks of rapid weight loss, diarrhoea, colic and hypoproteinaemia in weanling foals.
Evidence supporting an increased presence of reactive oxygen species in the diseased equine joint
Authors: Dimock A. N. , Siciliano P. D. , McIlwraith C. W.
Published: April 2007

Reactive oxygen species (ROS) are capable of degrading many components of the joint in the presence of insufficient antioxidant defences, and as a result have been implicated in the pathogenesis of joint disease in horses. However, to our knowledge, evidence of ROS occurring in diseased joints of horses has not been reported. The objective of this experiment was to compare differences in synovial fluid protein carbonyl content (as a marker of oxidative modification of synovial fluid proteins by ROS) and the antioxidant status of synovial fluid between clinically normal and diseased equine joints. Synovial fluid was collected from the metacarpophalangeal, metatarsophalangeal, carpal and tarsal joints of 4 horses, age 2–5 years, as controls, and from diseased joints (metacarpophalangeal, metatarsophalangeal, carpal, tarsal and/or femoropatellar) of 61 horses, age 2–5 years.

Synovial fluid protein carbonyl content was higher (P<0.01) in diseased joints as compared to controls. Antioxidant status of synovial fluid from diseased joints was higher, but not significantly, than that of controls (P = 0.0595). These findings require further study to determine their contribution to the overall disease process.
Relationship between clinical signs and lung function in horses with recurrent airway obstruction (heaves) during a bronchodilator trial
Authors: Robinson N. E. , Olszewski M. A. , Boehler D. , Berney C. , Hakala J. , Matson C. , Derksen F. J.
Published: April 2007

During a trial to determine the dose response to the β2‐adrenergic agonist pirbuterol, we judged the severity of airway obstruction by use of a clinical scoring system and compared this to objective data obtained by quantitative measures of lung function. Six horses affected by recurrent airway obstruction were used in this trial. Four hundred and sixty‐eight measurements of lung function and clinical scores were obtained from 13 measurement periods when horses received each of 6 doses of pirbuterol. Scores of 1–4 were assigned to degree of nasal flaring and abdominal effort and summed for a total score. The veterinarian scoring the signs did not know the dose of pirbuterol received by the horse and was unaware of the lung function data. Nasal, abdominal and total scores were significantly related to changes in lung function and changes in breathing pattern. There were significant differences between total scores greater than 5 in indices that reflected changes in breathing strategy (peak inspiratory and expiratory flow), peripheral airway obstruction (dynamic elastance), and effort of breathing (maximal change in pleural pressure). Below a total score of 5, there were fewer significant differences in lung function even though measurements of pulmonary resistance and dynamic elastance indicated considerable airway obstruction. Failure of clinical score to reflect this low‐grade airway obstruction suggests that airway disease is underdiagnosed and its detection would be helped by the availability of a convenient lung function test.
Anaemia, diarrhoea and opportunistic infections in Fell ponies
Authors: Richards A. J. M. , Kelly D. F. , Knottenbelt D. C. , Cheeseman M. T. , Dixon J. B.
Published: April 2007

This report summarises clinical and pathological observations on Fell pony foals with a range of signs that included ill thrift, anaemia, respiratory infection, glossal hyperkeratosis and diarrhoea. Some of the foals had normochromic, normocytic anaemia and some had low levels of plasma proteins, including immunoglobulin G. Antibiotic and supportive treatment was ineffective and all affected foals died or were killed on humane grounds. Postmortem examination of 12 foals and tissues from 2 other foals revealed a range of lesions that included glossal hyperkeratosis, typhlocolitis, intestinal cryptosporidiosis, granulomatous enteritis, proliferative and necrotising bronchiolitis consistent with adenovirus infection; lesions similar to those in the respiratory tract were present in the salivary gland and pancreas of individual foals. Lymphoid tissue was judged to be smaller than expected. These observations suggest the possibility of opportunistic infections secondary to some form of undefined immunocompromised state.
Affinity of isoxsuprine for adrenoreceptors in equine digital artery and implications for vasodilatory action
Authors: Belloli C. , Carcano R. , Arioli F. , Beretta C.
Published: April 2007

We used isolated equine digital arteries to study the vasodilatory mechanism of isoxsuprine, and fowl caecum preparations to investigate the affinity of the drug for β‐adrenoceptors. Isoxsuprine is a potent vasodilator of arterial smooth muscle that has been precontracted by an α‐adrenoceptoragonist such as noradrenaline (log EC50= ‐6.33 [‐5.98; ‐6.68]). The present study indicates that its effect is due to α‐adrenoceptorblockade since: (1) aftera long lasting exposure to cumulative doses of isoxsuprine the vasoconstricting action of noradrenaline cannot be restored; (2) isoxsuprine does not promote relaxation on preparations precontracted by PGF2α; (3) isoxsuprine shifts the dose‐response curve of noradrenaline to the right; and (4) its affinity (pKB= 6.90 [6.60; 7.20]) in this experiment is comparable to that in noradrenaline‐precontracted preparations and is 14 times lower than that of the selective α1‐adrenergic antagonist prazosin [pKB= 8.04 (7.40; 8.68]).

The affinity of isoxsuprine for β‐adrenoceptors was 100 times lower than that of isoprenaline when tested on fowl caecum. This preparation has a large β‐adrenoceptor and negligible α‐adrenoceptor population concerned with the control of smooth muscle motility. Our data suggest that the α‐mediated effect of isoxsuprine on horse arterial smooth muscle is due to higher affinity of the drug for α‐ than β‐adrenoceptors ratherthan low concentration orfunctionality of β‐sites at this site. According to these data, pure β2‐agonists seem to be more profitable tools to determine vasodialtion of the arterial bed in horses legs.
Spontaneous production of nitric oxide (NO), prostaglandin (PGE2) and neutral metalloproteinases (NMPs) in media of explant cultures of equine synovial membrane and articular cartilage from normal and osteoarthritic joints
Authors: Von Rechenberg B. , Mcilwraith C. W. , Akens M. K. , Frisbie D. D. , Leutenegger C. , Auer J. A.
Published: April 2007

Nitric oxide (NO), prostaglandin E2(PGE2), and the activity of neutral metalloproteinases (NMPs) were measured in conditioned media of equine synovial membrane and articular cartilage explant cultures from horses with normal joints (n = 7) and from horses affected with moderate (n = 7) or severe osteoarthritis (n = 14) as judged by macroscopic appearance. Normal articular cartilage appeared glossy and bluish‐white, was of normal thickness and showed no evidence of discolouration, fibrillation or other cartilage discontinuity. Slight discolouration and fibrillation or minor clefts of the cartilage were considered as moderate OA, whereas erosions of articular cartilage down to the subchondral bone were considered as cases of severe OA.

Explant cultures of equine synovial membrane and articular cartilage released the local mediators, NO and PGE2, as well as detectable levels of NMP activity into culture media. Concentrations of NO were higherin articular cartilage explants compared to synovial membrane explants, whereas concentrations of PGE2were higher in synovial membrane explants. The NMPs with collagenolytic activities were similar in both explant cultures, whereas gelatinolytic activities were higherin synovial membrane explant cultures and caseinolytic activities were generally higher in articular cartilage explant cultures. Furthermore it was shown that concentrations or enzyme activities increased according to the severity of disease of the joints. Concentrations for NO, collagenolytic and gelatinolytic NMPs were relatively stable, whereas PGE2and caseinolytic NMP concentrations increased over time in culture.
Nitric oxide inhibits aggrecan degradation in explant cultures of equine articular cartilage
Authors: Bird J. L. E. , May S. , Bayliss M. T.
Published: April 2007

Arthroses are debilitating diseases of articular joints which result in erosion of the cartilage extracellular matrix. Nitric oxide (NO) is a major component of the inflammatory response, and has been implicated as a mediator of some of the effects of the proinflammatory cytokine, interleukin‐1 (IL‐1). In this study, we investigated the role of NO in the regulation of proteoglycan degradation in equine articular cartilage. NO fully mediated the suppressive effect of IL‐1 on proteoglycan synthesis. However, NO was also antagonistic to proteoglycan degradation, irrespective of whether degradation was initiated by 10 ng/ml IL‐1 or 1 μmol/l all‐trans retinoic acid (RA) which (unlike IL‐1) does not elevate NO production. This was confirmed using the NO donor 2,2′‐(hydroxynitrosohydrazono) bis‐ethanamine (DETA‐NONOate) and the iNOS inhibitorL‐N5‐iminoethyl ornithine (dihydrochloride) (L‐NIO). The G1 fragments of aggrecan were detected in the media and extracts of cartilage explant cultures treated with all‐trans RA, DETA‐NONOate and L‐NIO. The presence of exogenous NO in culture resulted in a decrease in the appearance of the ‘aggrecanase’ cleavage epitope. Therefore, changes in the appearance of the G1 fragment expressing the ‘aggrecanase’ cleavage epitope in the media emulated the glycosaminoglycan loss from the tissue. These results lend further support to the hypothesis that NO has an anticatabolic role in equine cartilage proteoglycan degradation, and suggest that this may be mediated by the regulation of ‘aggrecanase’ activity. Therefore, any pharmacological intervention using NO as a target must take into account both its catabolic and anticatabolic roles in joint tissue turnover.
Assessment of muscle oxygenation in the horse by near infrared spectroscopy
Authors: Pringle J. , Roberts C. , Tatianaart C. , Lekeux P.
Published: April 2007

This study examined the ability of nearinfrared spectroscopy (NIRS) to noninvasively determine changes to muscle oxygenation in the resting horse. Five horses had (NIRS) performed over extremity muscle while under general anaesthesia, first with 8 min limb ischaemia, then systemic hypoxaemia for 5 min. A second group of 6 awake horses had NIRS performed over extremity muscle while being administered hypoxic gas (F1O2 0.10) for 5 min, and after return to steady state, limb ischaemia was induced for an additional 5 min. In the anaesthetised horses' ischaemia induced marked and significant muscle deoxygenation of haemoglobin/myoglobin (P<0.01), with corresponding arterial saturation decreasing from 98.9 to 81.9%. Hypoxaemia induced small yet significant muscle deoxygenation (P<0.01) that was 3.2% of the ischaemia deoxygenation signal, with a corresponding decrease in arterial saturation from 98.6 to 90.4%. In the awake horses muscle deoxygenation was not detectable during hypoxia despite reduction of arterial saturation from 97.8 to 86.8%, whereas ischaemia induced rapid and significant deoxygenation of muscle (P<0.05), with corresponding reduction of venous saturation from 78.4 to 75.4%. In neither group of horses was there evidence of cytochrome aa3 reduction, despite complete ischaemia forup to 8 min. NIRS changes in the resting horse muscle clearly differed between ischaemia and hypoxaemia, and can readily show muscle deoxygenation in clinically relevant hypoxaemia in the horse under anaesthesia. Further, as the deoxygenation signal induced by ischaemia was clearly detectable above a background movement artefact, NIRS application to study of muscle oxygenation in the working horse should be explored.