Rapid measurement and evaluation of the effect of drying conditions on harpagoside content in Harpagophytum procumbens (devil's claw) root

The effect of drying conditions on harpagoside (HS) retention, as well as the use of near-infrared spectroscopy (NIRS) for rapid quantification of the iridoids, HS, and 8-rho-coumaroyl harpagide (8rhoCHG) and moisture, in dried Harpagophytum procumbens (devil's claw) root was investigated. HS retention was significantly (P < 0.05) lower in sun-dried samples as compared to tunnel-dried (60 degrees C, 30% relative humidity) and freeze-dried samples. The best retention of HS was obtained at 50 degrees C when evaluating tunnel drying at dry bulb temperatures of 40, 50, and 60 degrees C and 30% relative humidity. NIRS can effectively predict moisture content with a standard error of prediction (SEP) and correlation coefficient (r) of 0.24% and 0.99, respectively. The HS and 8rhoCHG NIRS calibration models established for both iridoid glucosides can be used for screening purposes to get a semiquantitative classification of devil's claw roots (for HS: SEP = 0.236%, r = 0.64; for 8rhoCHG: SEP = 0.048%, r = 0.73).     

Effects of alpha2-adrenergic receptor agonists on urine production in horses deprived of food and water

OBJECTIVE: To quantitate the dose- and time-related effects of IV administration of xylazine and detomidine on urine characteristics in horses deprived of feed and water. ANIMALS: 6 horses. PROCEDURE: Feed and water were withheld for 24 hours followed by i.v. administration of saline (0.9% NaCI) solution, xylazine (0.5 or 1.0 mg/kg), or detomidine (0.03 mg/kg). Horses were treated 4 times, each time with a different protocol. Following treatment, urine and blood samples were obtained at 15, 30, 60, 120, and 180 minutes. Blood samples were analyzed for PCV and serum concentrations of total plasma solids, sodium, and potassium. Urine samples were analyzed for pH and concentrations of glucose, proteins, sodium, and potassium. RESULTS: Baseline (before treatment) urine flow was 0.30 +/- 0.03 mL/kg/h and did not significantly change after treatment with saline solution and low-dose xylazine but transiently increased by 1 hour after treatment with high-dose xylazine or detomidine. Total urine output at 2 hours following treatment was 312 +/- 101 mL versus 4,845 +/- 272 mL for saline solution and detomidine, respectively. Absolute values of urine concentrations of sodium and potassium also variably increased following xylazine and detomidine administration. CONCLUSIONS AND CLINICAL RELEVANCE: Xylazine and detomidine administration in horses deprived of feed and water causes transient increases in urine volume and loss of sodium and potassium. Increase in urine flow is directly related to dose and type of alpha2-adrenergic receptor agonist. Dehydration in horses may be exacerbated by concurrent administration of alpha2-adrenergic receptor agonists.     

Effects of ventilation and isoflurane end-tidal concentration on intracranial and cerebral perfusion pressures in horses

OBJECTIVE: To measure the effects of isoflurane end-tidal concentration and mode of ventilation (spontaneous vs controlled) on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in horses. ANIMAL: adult horses of various breeds. PROCEDURES: Anesthesia was induced and maintained with isoflurane in O2 in 6 healthy, unmedicated, adult horses. Using a subarachnoid strain gauge transducer, ICP was measured. Blood gas tensions and carotid artery pressures also were measured. Four isoflurane doses were studied, corresponding to the following multiples of the minimum alveolar concentration (MAC): 1.0 MAC, 1.2 MAC, 1.4 MAC, and 1.6 MAC. Data were collected during controlled ventilation and spontaneous ventilation at each dose. RESULTS: increasing isoflurane end-tidal concentration induced significant dose-dependent decreases in mean arterial pressure (MAP) and CPP but no change in ICR Hypercapnic spontaneous ventilation caused significant increases in MAP and ICR compared with normocapnic controlled ventilation; no change in CPP was observed. CONCLUSIONS AND CLINICAL RELEVANCE: Hypercapnia likely increases cerebral blood flow (CBF) by maintaining CPP in the face of presumed cerebral vasodilation in healthy anesthetized horses. The effect of isoflurane dose on CBF however, remains unresolved because it depends on the opposing influences of a decrease in CCP and cerebral vasodilation.     

Effects of duration of isoflurane anesthesia and mode of ventilation on intracranial and cerebral perfusion pressures in horses

OBJECTIVE: To test the hypothesis that isoflurane-anesthetized horses during controlled ventilation and spontaneous ventilation exhibit temporal changes in cerebral hemodynamics, as measured by intracranial pressure and cerebral perfusion pressure, that reflect temporal changes in systemic arterial pressure. ANIMALS: 6 healthy adult horses. PROCEDURE: Horses were anesthetized in left lateral recumbency with 1.57% isoflurane in O2 for 5 hours in 2 experiments by use of either controlled ventilation (with normocapnia) or spontaneous ventilation (with hypercapnia) in a randomized crossover design. Intracranial pressure was measured with a subarachnoid strain-gauge transducer. Carotid artery pressure, central venous pressure, airway pressures, blood gases, and minute ventilation also were measured. RESULTS: Intracranial pressure during controlled ventilation significantly increased during constant dose isoflurane anesthesia and thus contributed to decreasing cerebral perfusion pressure. Intracranial pressure was initially higher during spontaneous ventilation than during controlled ventilation, but this difference disappeared over time; no significant differences in cerebral perfusion pressures were observed between horses that had spontaneous or controlled ventilation. CONCLUSIONS AND CLINICAL RELEVANCE: Cerebral hemodynamics and their association with ventilation mode are altered over time in isoflurane-anesthetized horses and could contribute to decreased cerebral perfusion during prolonged anesthesia.     

Effects of iron modulation on growth and viability of Rhodococcus equi and expression of virulence-associated protein A

OBJECTIVE: To determine the importance of iron for in vitro growth of Rhodococcus equi, define potential iron sources in the environment and mechanisms by which R equi may obtain iron from the environment, and assess expression and immunogenicity of iron-regulated proteins. SAMPLE POPULATION: 10 virulent and 11 avirulent strains of R equi. PROCEDURE: In vitro growth rates and protein patterns of R equi propagated in media with normal, excess, or limited amounts of available iron were compared. Immunoblot analyses that used serum from foals naturally infected with R equi and monoclonal antibody against virulence-associated protein (Vap)A were conducted to determine immunogenicity and identity of expressed proteins. RESULTS: Excess iron did not alter growth of any R equi strains, whereas growth of all strains was significantly decreased in response to limited amounts of available iron. Virulent R equi were able to use iron from ferrated deferoxamine, bovine transferrin, and bovine lactoferrin. Only virulent R equi expressed an iron-regulated, immunogenic, surface-associated protein identified as VapA. CONCLUSIONS AND CLINICAL RELEVANCE: Iron is required for the growth and survival of R equi. Sources of iron for R equi, and mechanisms by which R equi acquire iron in vivo, may represent important virulence factors and novel targets for the development of therapeutic and immunoprophylactic strategies to control R equi infection in foals. Expression of VapA is substantially upregulated when there is a limited amount of available iron.     

Immunological relationship between Neospora caninum and Besnoitia besnoiti

Neospora caninum is a coccidian parasite identified as a major cause of abortion in cattle. A combined infection of N. caninum with another taxonomically related parasite of cattle, Besnoitia besnoiti can occur in geographical areas endemic for both species. Both infections are routinely diagnosed serologically, and incorrect diagnosis could occur if immunological cross-reactivity exists between the two parasites. To investigate the possible degree of cross-reactivity, we compared results obtained with two serological techniques, immunofluorescent antibody test (IFA), and Western blot analysis on known positive and negative sera. The test sera were derived from naturally infected cattle and from experimentally infected Mongolian gerbils. In IFA of bovine sera, no cross-reactvity was detected at the commonly used serum dilution cutoffs of 1:200 for N. caninum and 1:256 for B. besnoiti. However, at 1:64 dilution of both cattle and gerbil sera, anti-N. caninum sera reacted with B. besnoiti antigen in some individual samples. Anti-B. besnoiti serum did not react with N. caninum antigen at any dilution. This low level one directional cross-reactivity was confirmed by Western blot analysis. B. besnoiti antigen showed two immunoreactive bands when probed with anti-N. caninum serum, while no bands appeared when N. caninum antigen was probed with B. besnoiti antiserum. Immunization and challenge experiments in the highly susceptible Mongolian gerbil (Meriones unguiculatus) showed essentially no cross-protection between N. caninum and B. besnoiti.     

Electrical nerve stimulation as an aid to the placement of a brachial plexus block

Most local anaesthetic blocks are placed blindly, based on a sound knowledge of anatomy. Very often the relationship between the site of deposition of local anaesthetic and the nerve to be blocked is unknown. Large motor neurons may be stimulated with the aid of an electrical current. By observing for muscle twitches, through electrical stimulation of the nerve, a needle can be positioned extremely close to the nerve. The accuracy of local anaesthetic blocks can be improved by this technique. By using the lowest possible current a needle could be positioned with in 2-5 mm of a nerve. The correct duration of stimulation ensures that stimulation of sensory nerves does not occur The use of electrical nerve stimulation in veterinary medicine is a novel technique that requires further evaluation.     

Microbiological and histopathological findings in cases of fatal bovine respiratory disease of feedlot cattle in Western Canada

The aim of this study was to describe the microbiologic agents and pathologic processes in fatal bovine respiratory disease (BRD) of feedlot cattle and to investigate associations between agents and pathologic processes. Ninety feedlot calves diagnosed at necropsy with BRD and 9 control calves without BRD were examined, using immunohistochemical (IHC) staining and histopathologic studies. Mannheimia haemolytica (MH) (peracute, acute, and subacute cases) and Mycoplasma bovis (MB) (subacute, bronchiolar, and chronic cases) were the most common agents identified in fatal BRD cases. Significant associations (P < 0.10) were detected between microbiologic agents and between agents and pathologic processes. When IHC staining was used, 25/26 (96%) of animals that were positive for bovine viral diarrhea virus (BVDV) were also positive for MH; 12/15 (80 %) of animals that were positive for Histophilus somni (HS) were also positive for MB; and all of the animals that were positive for HS were negative for MH and BVDV. This quantitative pathological study demonstrates that several etiologic agents and pathologic processes are involved in fatal BRD of feedlot cattle.     

Endemic Visceral Leishmaniasis in a Dog from Texas

Visceral leishmaniasis was diagnosed by cytology and positive indirect immunofluorescent antibody titers to Leishmania donovani in a 7-month-old female Basenji dog from Texas. Clinical and laboratory findings included weight loss, hematochezia, hyperglobulinemia, hypoalbuminemia, anemia, and neutrophilic leukocytosis. Evidence of response to treatment with diminazene aceturate and ketoconazole included improvement in the abnormal clinical, hematologic, and biochemical findings, decreased serum globulin concentration and antibody titer to Leishmania donovani, and absence of organisms in examined tissues. Several foci of endemic leishmaniasis have been reported in the United States. Because of its zoonotic potential and the lack of approved treatments for dogs with leishmaniasis in the United States, the development of effective treatment strategies is needed.