Effect of furosemide on urine specific gravity and osmolality in thoroughbred racehorses

Postrace urine samples from thoroughbred horses were examined to compare osmolality and specific gravity between horses treated with furosemide and those not treated. Samples were assigned to groups in relation to reported medication (furosemide) status, race finish position, and distance of race. Urine osmolality was significantly (P <.05) lower in samples from horses treated with furosemide when compared with untreated horses. Specific gravity determinations are less precise at measuring urine osmolality at lower levels (1.01 g/ml or less). The measurement of osmolality is a superior method for determining the urine solute concentration and facilitating the regulation of furosemide.     

Association of high-speed exercise with racing injury in thoroughbreds

OBJECTIVE: To determine the association between high-speed exercise and risk of injury while racing among Thoroughbreds in Kentucky. DESIGN: Matched case-control study. ANIMALS: 206 Thoroughbreds that sustained a musculoskeletal injury while racing and 412 Thoroughbreds that were not injured during the same races. PROCEDURE: Data regarding official timed workouts and races and the Beyer's numbers for the 3 races before the race during which injury occurred were extracted from past performance charts and compared between injured horses and control horses. RESULTS: For injured horses, cumulative distance of high-speed exercise during the 1- and 2-month periods prior to the race in which injury occurred was significantly less than that of control horses; for either period, a difference of 10 furlongs was associated with approximately 2-fold greater risk of injury. Beyer's numbers were significantly higher for injured horses than for control horses. These effects remained significant after adjusting for age and results of prerace physical inspection. CONCLUSIONS AND CLINICAL RELEVANCE: In Kentucky, injured horses had significantly less cumulative high-speed exercise than did control horses during the 1- and 2-month periods prior to the race in which injury occurred. These results differ from those observed in California. The association of injury with cumulative high-speed exercise appears to vary among regions in the United States.     

Lidocaine in the horse: its pharmacological effects and their relationship to analytical findings

Lidocaine is a local anaesthetic agent that is widely used in equine medicine. It is also an Association of Racing Commissioners International (ARCI) Class 2 foreign substance that may cause regulators to impose substantial penalties if residues are identified in post race urine samples. Therefore, an analytical/pharmacological database was developed for this drug. Using our abaxial sesamoid local anaesthetic model, the highest no-effect dose (HNED) for the local anaesthetic effect of lidocaine was determined to be 4 mg. Using enzyme-linked immunosorbent assay (ELISA) screening, administration of the HNED of lidocaine to eight horses yielded peak serum and urine concentrations of apparent lidocaine of 0.84 ng/mL at 30 min and 72.8 ng/mL at 60 min after injection, respectively. These concentrations of apparent lidocaine are readily detectable by routine ELISA screening tests (LIDOCAINE ELISA, Neogen, Lexington, KY). ELISA screening does not specifically identify lidocaine or its metabolites, which include 3-hydroxylidocaine, dimethylaniline, 4-hydroxydimethylaniline, monoethylglycinexylidine, 3-hydroxymonoethylglycinexylidine, and glycinexylidine. As 3-hydroxylidocaine is the major metabolite recovered from equine urine, it was synthesized, purified and characterized, and a quantitative mass spectrometric method was developed for 3-hydroxylidocaine as recovered from horse urine. Following subcutaneous (s.c.) injection of the HNED of lidocaine, the concentration of 3-hydroxylidocaine recovered from urine reached a peak of about 315 ng/mL at 1 h after administration. The mean pH of the 1 h post dosing urine samples was 7.7, and there was no apparent effect of pH on the amount of 3-hydroxylidocaine recovered. Within the context of these experiments, the data suggests that recovery of less than 315 ng/mL of 3-hydroxylidocaine from a post race urine sample is unlikely to be associated with a recent local anaesthetic effect of lidocaine. Therefore these data may be of assistance to industry professionals in evaluating the significance of small concentrations of lidocaine or its metabolites in postrace urine samples. It should be noted that the quantitative data are based on analytical methods developed specifically for this study, and that methods used by other laboratories may yield different recoveries of urine 3-hydroxylidocaine.     

An ab initio molecular dynamics study of the aqueous liquid-vapor interface

We present an ab initio molecular dynamics simulation of the aqueous liquid-vapor interface. Having successfully stabilized a region of bulk water in the center of a water slab, we were able to reproduce and further quantify the experimentally observed abundance of surface "acceptor-only"(19%) and "single-donor"(66%) moieties as well as substantial surface relaxation approaching the liquid-vapor interface. Examination of the orientational dynamics points to a faster relaxation in the interfacial region. Furthermore, the average value of the dipole decreases and the average value of the highest occupied molecular orbital for each water molecule increases approaching the liquid-vapor interface. Our results support the idea that the surface contains, on average, far more reactive states than the bulk.     

Use of droperidol and fentanyl for analgesia and sedation in primates

A combination of droperidol and fentanyl produces qualitatively similar pharmacologic effects in dogs and primates. Unlike the dog, however, primates did not appear to respond to auditory stimuli. As a result of the analgesic and sedative or tranquil state produced in primates, the animals were easily handled and tolerant of painful stimuli. The principal desirable features of the combination were high analgesic and sedative potency and a rapid onset of action following intramuscular administration. High doses produced respiratory depression. However, this effect was easily reversed by administering nalorphine hydrochloride.     

Fatigue and creep in chipboard

Summary Matched samples of chipboard were loaded in four-point bending under either a 7 hours loaded/17 hours unloaded cycle, a 17 hours loaded/7 hours unloaded cycle, or constant load in order to asses the effect of cyclic loading on creep deformation. Tests were carried out at three humidity levels (30, 45 and 90% RH) and at three stress levels (30, 45, and 60% of the short term strength). The creep rate of samples under constant load was greater than under cyclic load, with the 7 hours loaded/17 hours unloaded samples giving the lowest creep rate. Analysis of the data on an accumulated time-under-load basis showed that the law of superposition did not apply to the 7 hours loaded/17 hours unloaded samples at the 30% and 45% stress levels, with these samples giving lower deflection than for the other loading conditions. The 17 hours loaded/7 hours unloaded samples also did not appear to obey the law of superposition, although the difference between them and the constantly loaded samples was slight. Considerable scatter in data accumulated at the 60% stress level did not allow any differences in the superposition analysis of cyclic and constant loaded samples to become apparent. Increasing the stress level applied to samples produced an almost linear increase in relative creep for all loading regimes. The 7 hours loaded/17 hours unloaded samples gave consistently lower relative creep values at all levels of stressing, but particularly at the 30 and 45% stress levels. Increasing the relative humidity from 30% to 65% RH had an almost negligible effect on relative creep of all samples, but increasing the humidity to 90% RH caused a marked increase in relative creep.     

The modelling of time-dependant deformation in wood using chemical kinetics

Summary The development of rheological models to predict creep has led to the derivation of quite complex equations that can predict creep reasonably accurately. However, these models are conceptual and are not based on a fundamental understanding of the actual deformation processes occurring within the material. The concept of modelling creep using a chemical kinetic approach is one that attempts to understand creep in wood at a molecular level and, from this, to develop models that more accurately predict creep deflections.This paper presents two models developed from chemical kinetic theory, that describe the time-dependant deformation of wood. The validity of applying these models to experimental data has been assessed by stress relaxation tests on thin samples of Sequoia sempervirens. Two stages of experimentation were carried out. In stage 1, both models were applied to the results of stress relaxation tests on 6 samples. Similar values of activation energy and activation volume were calculated by both models and a single energy barrier was found to dominate the deformation process.In stage 2, the effect of varying the initial applied stress on activation energy and activation volume was assessed by carrying out stress relaxation tests at stress levels of 25%, 30% and 35% of the short-term strength. Values of activation energy and activation were found to increase as the applied stress level decreased.Both models describe the time-dependent behaviour of wood well, however their ability to predict long-term creep deflections may be limited. Future work will develop these models further in order to improve long-term creep prediction and then apply them to the results of both creep and stress relaxation tests at a variety of stress levels and moisture contents in order to test their validity.     

Effects of cyclophosphamide myelosuppression in adult dogs with latent canine herpesvirus-1 infection

Latent canine herpesvirus-1 (CHV-1) infection is common in domestic dogs, but triggers for viral reactivation and recrudescent CHV-1 disease are poorly understood. Cyclophosphamide is a potent immunosuppressive and myelosuppressive agent used for the therapy of a variety of neoplastic and immune-mediated canine disorders. Cyclophosphamide (200mg/m(2)) was administered to mature dogs latently infected with CHV-1 to determine its potential to induce recurrent CHV-1 disease and viral shedding. Non-infected dogs and dogs recovered from experimental primary ocular CHV-1 infection with experimentally confirmed latent CHV-1 infection were divided into groups and administered cyclophosphamide or placebo. Dogs were monitored for myelosuppression and viral reactivation for 28days using clinical and virological outcome measures. Clinical ophthalmic and in vivo ocular confocal microscopic examinations were performed at intervals. Samples were collected for CHV-1 polymerase chain reaction (PCR), CHV-1 virus neutralizing (VN) antibody, and hemogram assays. Myelosuppression (i.e., decreased total leukocyte, segmented neutrophil, and erythrocyte counts) was detected on study day 7 in dogs administered cyclophosphamide, but not dogs administered placebo. There were no abnormalities suggestive of recurrent CHV-1 ocular disease during clinical ophthalmic or in vivo confocal microscopic examination in any dogs during the study. Ocular CHV-1 shedding was not detected by PCR and CHV-1 VN titers remained stable in all dogs. Following study conclusion, the presence of reactivatable latency was reconfirmed in the infected dogs by administering systemic prednisolone. Myelosuppression elicited by a single dose of cyclophosphamide does not result in detectable recurrent ocular CHV-1 infection in adult dogs with experimentally induced latent CHV-1 infection.     

Esterase-inhibiting photo-oxidation products from the organophosphorus insecticide pyrimithate

Pyrimithate (2-dimethylamino-6-methylpyrimidin-4-yl diethyl phosphorothio-nate) decomposes when exposed to u.v. light in the presence of air to a complex mixture of products, some of which inhibit esterases directly or indirectly. Separation of the mixture by thin-layer and liquid chromatography gave five pure components in sufficient quantity for spectroscopic identification. A sixth was tentatively identified. The structures ( II-VII ) show that oxidative attack occurs at the dimethylamino group and at the sulphur atom.