Biochemical evaluation of mitochondrial respiratory chain enzymes in canine skeletal muscle

OBJECTIVE: To perform respiratory chain enzymatic activity assays on canine skeletal muscle biopsy specimens and establish reference range values of skeletal muscle enzyme activities for dogs. SAMPLE POPULATION: Biopsy specimens from the vastus lateralis muscle were obtained from 24 dogs (8 sexually intact males and 14 sexually intact females) ranging from 15 months to 6 years of age. PROCEDURE: Mean values of citrate synthase, cytochrome-c oxidase, succinate dehydrogenase, succinate dehydrogenase-cytochrome-c reductase, nicotinamide adenine dinucleotide (NADH) dehydrogenase, and NADH dehydrogenase-cytochrome-c reductase activities were established by use of 6 standard spectrophotometric assays for respiratory chain enzyme analysis. RESULTS: Compared with published data for skeletal muscle enzyme activities in humans, skeletal muscle enzyme activities in dogs were 2- to 4-fold higher. Additionally, citrate synthase activity, a marker for mitochondrial volume, was positively correlated with age in dogs, suggesting that mitochondrial volume increases with age, although no apparent change in respiratory chain enzymatic activity with an increase in age was found. CONCLUSIONS AND CLINICAL RELEVANCE: Reference range values for skeletal muscle enzyme activities of dogs are needed to accurately interpret results of respiratory chain enzymatic activity assays. During investigation of metabolic myopathies, if skeletal muscle biopsy specimens are evaluated for respiratory chain enzyme kinetics, they should be performed and evaluated in concert with skeletal muscle biopsy specimens from clinically normal animals of the same species.     

Pharmacokinetics of meloxicam in plasma and urine of horses

OBJECTIVE: To determine pharmacokinetic parameters for meloxicam, a nonsteroidal anti-inflammatory drug, in horses. ANIMALS: 8 healthy horses. PROCEDURE: In the first phase of the study, horses were administered meloxicam once in accordance with a 2 x 2 crossover design (IV or PO drug administration; horses fed or not fed). The second phase used a multiple-dose regimen (daily oral administration of meloxicam for 14 days), with meloxicam administered at the recommended dosage (0.6 mg/kg). Plasma and urine concentrations of meloxicam were measured by use of validated methods with a limit of quantification of 10 ng/mL for plasma and 20 ng/mL for urine. RESULTS: Plasma clearance was low (mean +/- SD; 34 +/- 0.5 mL/kg/h), steady-state volume of distribution was limited (0.12 +/- 0.018 L/kg), and terminal half-life was 8.54 +/- 3.02 hours. After oral administration, bioavailability was nearly total regardless of feeding status (98 +/- 12% in fed horses and 85 +/- 19% in nonfed horses). During once-daily administration for 14 days, we did not detect drug accumulation in the plasma. Meloxicam was eliminated via the urine with a urine-to-plasma concentration that ranged from 13 to 18. Concentrations were detected for a relatively short period (3 days) after administration of the final daily dose. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study support once-daily administration of meloxicam regardless of the feeding status of a horse and suggest a period of at least 3 days before urine concentrations of meloxicam reach concentrations that could be used in drug control programs.     

A plant miRNA contributes to antibacterial resistance by repressing auxin signaling

Plants and animals activate defenses after perceiving pathogen-associated molecular patterns (PAMPs) such as bacterial flagellin. In Arabidopsis, perception of flagellin increases resistance to the bacterium Pseudomonas syringae, although the molecular mechanisms involved remain elusive. Here, we show that a flagellin-derived peptide induces a plant microRNA (miRNA) that negatively regulates messenger RNAs for the F-box auxin receptors TIR1, AFB2, and AFB3. Repression of auxin signaling restricts P. syringae growth, implicating auxin in disease susceptibility and miRNA-mediated suppression of auxin signaling in resistance.     

A synthetic fraction of feline facial pheromones calms but does not reduce struggling in cats before venous catheterization

OBJECTIVE: To evaluate whether a synthetic analogue of feline facial pheromone (FFP) calms cats before, and reduces struggling during intravenous catheterization. DESIGN: Block-randomized, 'blinded' clinical trial. ANIMALS: Seventy-seven healthy cats presented for elective surgery. PROCEDURE: Cats given glycopyrrolate and oxymorphone were assigned to one of four treatments: acepromazine and exposure to FFP (aceFFP); acepromazine and exposure to a placebo (acePlac); exposure to FFP only (FFP) and exposure to placebo only (Plac). The behaviour of cats was recorded on videotape for evaluation by assessors unaware of treatment group. Cats' veins were then catheterized by veterinary students unaware of the study protocol. Based on each cat's response to catheterization, the student independently decided whether intramuscular ketamine was required. RESULTS: Cats in the aceFFP group appeared to be calmer than acePlac cats on the basis of head position and their location in the cage (suggesting benefit from FFP among cats receiving acepromazine) but appeared to be less sedated. Cats in the aceFFP group also appeared to be calmer than FFP cats on the basis of head position and location in the cage. Feline facial pheromone cats were also calmer than Plac cats when compared using body and leg position. Exposure to FFP did not significantly reduce struggling at catheterization, nevertheless, the students were able to catheterize the veins in all cats. CONCLUSION AND CLINICAL RELEVANCE: There were no detrimental behavioural effects associated with either FFP or acepromazine. The FFP had additional calming effects in cats given acepromazine and, to a lesser degree, helped to calm cats that were not given acepromazine. Feline facial pheromone helps to calm cats in unfamiliar surroundings.     

Comparison of cell populations derived from canine olfactory bulb and olfactory mucosal cultures

OBJECTIVE: To evaluate the numbers and proportions of olfactory ensheathing cells (OECs) in cell cultures derived from the olfactory bulb (OB) and olfactory mucosa of dogs. ANIMALS: 7 dogs. PROCEDURES: OB tissue and olfactory mucosa from the nasal cavity and frontal sinus were obtained from euthanatized dogs and prepared for cell culture. At 7, 14, and 21 days of culture in vitro, numbers and proportions of OECs, astrocytes, and fibroblasts were determined via immunocytochemistry. Antibody against the low-affinity nerve growth factor receptor p75 was used to identify OECs, antibody against glial fibrillary acidic protein was used to identify astrocytes, and antibody against fibronectin was used to identify fibroblasts. RESULTS: Cultured OECs derived from the olfactory mucosa of the nasal cavity and frontal sinus had similar characteristics. However, whereas OECs in the OB cell cultures constituted approximately 50% of the cells at 7 days and approximately 75% at 21 days the proportion of OECs in cultures derived from both mucosal types was much lower, with approximately 40% OECs at 7 days and approximately 25% at 21 days. Analysis of OEC numbers revealed that these changes were accompanied by corresponding decreases and increases in the population of cells with fibronectin receptors. CONCLUSIONS AND CLINICAL RELEVANCE: Although olfactory mucosal cell cultures yielded a sufficient number of OECs for spinal cord transplantation procedures in dogs, modification of culture conditions would be required to ensure that the derived cell population contained a sufficient proportion of OECs.     

A simplified PCR method for genotyping Mycoplasma mycoides subspecies mycoides small colony: the aetiologic agent of contagious bovine pleuropneumonia

Mycoplasma mycoides subspecies mycoides small colony is the aetiological agent of contagious bovine pleuropneumonia, a cattle disease endemic to areas of sub-Saharan Africa. Twenty isolates from various geographical locations and the type strain were analysed by multi-locus sequence analysis (MLSA). The data generated was then used to develop three PCR primer sets to differentiate these isolates. The PCRs differentiated the isolates into four groups; the type strain (T); isolates of European origin (Eu); isolates from Tanzania (Af1) with a final group consisting of isolates from Namibia and Botswana (Af2). These PCRs offers a rapid and efficient post-identification typing method without the need to sequence and analyse multiple genes.     

Comparison of bupivacaine femoral and sciatic nerve block versus bupivacaine and morphine epidural for stifle surgery in dogs

ObjectiveTo evaluate the efficacy of combined femoral and sciatic nerve blocks as an alternative to epidural anesthesia and analgesia in dogs undergoing stifle surgery under general anesthesia.Study designProspective, blinded, randomized, clinical comparison.AnimalsTwenty dogs weighing 37 ± 11 (mean ± SD) kg, aged 3 (1–8) [median (minimum–maximum)] years undergoing elective unilateral tibial-plateau leveling osteotomy.MethodsDogs were assigned randomly to receive either epidural anesthesia (bupivacaine 0.5%, 0.5 mg kg^?1 + morphine 0.1%, 0.1 mg kg^?1, in 0.2 mL kg^?1; EPID) or femoral and sciatic nerve blocks (Bupivacaine 0.5%, 0.1 mL kg^?1, was administered at each site; F + S) guided by electrolocation. All patients received a standard general anesthesia technique. Pain and sedation were scored (on scales of 0–10 and 0–3, respectively) pre-operatively, at extubation, and at 1, 4 and then every 4 hours thereafter up to 24 hours. Postoperatively, hydromorphone was administered to any patient with a pain score of >5 or whenever the blinded caregiver determined that more hydromorphone was necessary. Intraoperative heart rate (HR), mean arterial pressure (MAP), end tidal isoflurane (FE′ISO), body temperature, post-operative pain scores, time to first hydromorphone dose after surgery, time to first feeding, time to first drinking, time to first urination, time to first ambulation (walk on a lead) and cumulative dose of hydromorphone were recorded.ResultsIntra-operatively, FE′ISO and MAP were significantly lower in the EPID group (p = 0.05 and p = 0.04, respectively). Postoperatively, the cumulative hydromorphone consumption (p = 0.04) and the incidence of urinary retention (p = 0.03) were higher in the EPID group.Conclusion and clinical relevance F + S is a practical alternative to EPID that produces less urine retention and reduces opioid consumption in the 24 hours after surgery. EPID might be associated with a lower isoflurane requirement and lower systemic blood pressure.     

Observations of the potency and duration of vecuronium in isoflurane-anesthetized horses

ObjectiveTo evaluate the potency and duration of three subparalyzing doses of vecuronium (VEC) in isoflurane-anesthetized horses.Study designProspective experimental study.AnimalsThirteen healthy adult horses undergoing arthroscopic surgery.MethodsDuring isoflurane anesthesia, horses received one of three doses of vecuronium (25, 50, or 100 μg kg^?1). Neuromuscular transmission was monitored with acceleromyography (AMG) with train-of-four (TOF) stimulation of the radial nerve. Maximal depression of the first twitch (T1), and onset time were recorded for each dose. Recovery time to a TOF ratio >90% was also evaluated.ResultsVecuronium 25 μg kg^?1 produced no observable T1 depression in four horses. VEC 50 μg kg^?1 (n = 5) produced a maximal T1 depression of [median (min, max)] 41 (20, 71) % in four horses, and no neuromuscular block was seen in the fifth. VEC 100 μg kg^?1 was given to four horses and produced a T1 depression of 73 (64, 78) %. Of the four horses in which VEC 50 μg kg^?1 produced a measurable neuromuscular block, three recovered spontaneously 43 (40, 52) minutes after VEC administration; a fourth subject received edrophonium to reverse residual block at the end of the surgery. Spontaneous recovery after VEC 100 μg kg^?1 occurred by 112 minutes in one horse, and had to be facilitated by edrophonium in the remaining three horses, more than 2 hours after VEC had been given.Conclusions and clinical relevanceA dose of 100 μg kg^?1 VEC in isoflurane anesthetized horses failed to produce complete paralysis. The partial neuromuscular block lasted at least 2 hours after this dose had been administered. Edrophonium was required to reverse the neuromuscular block in three of four horses. It is likely that more than 100 μg kg^?1 VEC would be necessary for complete neuromuscular blockade in horses, and that this dose will last >2 hours.