Pharmacokinetics of phenobarbital in the cat following intravenous and oral administration.

Phenobarbital was administered to eight healthy cats as a single intravenous dose of 10 mg/kg. Serum phenobarbital concentrations were determined using an immunoassay technique. The intravenous data were fitted to one-, two- and three-compartment models. After statistical comparison of the three models, a two-compartment model was selected. Following intravenous administration, the drug was rapidly distributed (distribution half-life = 0.046 +/- 0.007 h) with a large apparent volume of distribution (931 +/- 44.8 mL/kg). Subsequent elimination of phenobarbital from the body was slow (elimination half-life = 58.8 +/- 4.21 h). Three weeks later, a single oral dose of phenobarbital (10 mg/kg) was administered to the same group of cats. A one-compartment model with an input component was used to describe the results. After oral administration, the initial rapid absorption phase (absorption half-life = 0.382 +/- 0.099 h) was followed by a plateau in the serum concentration (13.5 +/- 0.148 micrograms/mL) for approximately 10 h. The half-life of the terminal elimination phase (76.1 +/- 6.96 h) was not significantly different from the half-life determined for the intravenous route. Bioavailability of the oral drug was high (F = 1.20 +/- 0.120). Based on the pharmacokinetic parameters determined in this study, phenobarbital appears to be a suitable drug for use as an anticonvulsant in the cat.     

Prevalence and clonal diversity of Campylobacter jejuni from dairy farms and urban sources

AIM: To investigate the role of free-living animals such as spar- rows, rodents and flies as potential reservoirs of Campylobacter spp on a dairy farm, and to assess the genetic diversity among Campylobacter isolates from the farm and an urban source.

METHODS: A total of 290 samples (bovine, passerine and ro- dent faeces, and whole flies) were collected from a large com- mercial dairy farm in the Manawatu district in New Zealand, and from faeces from urban sparrows in a nearby city. Other samples collected from the dairy farm included five from silage, two from aprons worn by workers during milking, two from workers' boots and two from water in troughs in a paddock. Isolates of thermophilic Campylobacter spp were identified mor- phologically and phenotypically and further characterised mo- lecularly using pulsed-field gel electrophoresis (PFGE) and the restriction enzyme SmaI.

RESULTS: Campylobacter jejuni was the only Campylobacter species isolated from all samples. The highest prevalence was found in faeces from dairy cows (54%), followed by faeces from sparrows from the urban area (40%) and the farm (38%), and from rodents (11%) and whole flies (9%). Other samples from the farm environment such as silage, trough water, and work- ers' aprons and boots were also positive for C. jejuni. Of the 22 restriction patterns obtained, seven were common to more than one source.

CONCLUSIONS: Cattle, sparrows, rodents and flies are po- tential reservoirs of C. jejuni on dairy farms. Identical clones of C. jejuni carried by cattle, sparrows, flies and rodents prob- ably indicate a common source of infection. The high level of asymptomatic carriage of C. jejuni by healthy dairy cows could be sufficient to maintain infections within the dairy farm sur- roundings via environmental contamination.     

Effect of setting a maximum milking time,from peak lactation,on production,milking time and udder health

Abstract

AIM: To examine the effect of setting a maximum milking time, from peak lactation until drying-off, on production, duration of milking, and udder health of dairy cows.

METHODS: Forty cows were assigned in twin-pairs to be either milked until cups were removed at a milk flow-rate threshold of 0.35 kg/minute (Control), or until cups were removed at a milk flow-rate threshold of 0.35 kg/minute, or maximum time, whichever came first (MaxT). The maximum time was set by determining the milking time of the 70th percentile cow when ranked from fastest to slowest, irrespective of yield. The milking routine was typical of that practised on dairy farms in New Zealand, and involved no pre-milking preparation. The study began at peak lactation (68 (SD 7) days in milk; DIM) and continued for 26 weeks. Duration of milking and milk yield were measured for each milking. Composition of milk was determined from weekly herd tests, and milk quality from fortnightly somatic cell counts (SCC). Completeness of milking and teat condition were assessed during the study. The bacterial status of quarter milk samples was determined at the beginning and end of the study, and all treated cases of clinical mastitis recorded. ANOVA was used to examine the effect of treatment group on variables of interest.

RESULTS: Total milk, fat and protein yields during the study period did not differ between treatments. On average, 30.3% of the morning and 27.6% of the afternoon milkings of MaxT cows reached the maximum time at which cups were removed, and were therefore shortened. While the average milking time of the slowest-milking cow was longer for the Control compared with MaxT group in Weeks 1–18, the average milking time did not differ between treatments. There was no difference in overall SCC, and the incidence of clinical mastitis, or the percentage of infected quarters at drying-off, was similar for the MaxT and Control cows.

CONCLUSION: The results show that setting a maximum milking time can reduce the milking time of slower-milking cows in a herd without compromising overall herd production and udder health.

CLINICAL RELEVANCE: Although the numbers of cows in the study were small there was no evidence of a major increase in SCC, or subclinical or clinical mastitis when a maximum milking time was set for slower-milking cows.     

Effect of plant density and macronutrient nutrition on Delphinium shoot cultures

The effect of shoot density on the uptake of macronutrients from MS medium and growth rates of Delphinium shoot tissue cultures was determined. Multiplication rates and uptake of phosphate, nitrate and sugar per shoot increased with decreasing shoot density. Increasing the concentration of total nutrients significantly increased both fresh weight gain and multiplication rate at the high plant density (15 shoots 50 ml'1 medium) usually used for micropropagation. However, increasing the phosphate concentration (phosphate being the nutrient most rapidly depleted in the medium) resulted in higher fresh weight only, while the multiplication rates of shoots remained similar.     

Virulence of Flavobacterium psychrophilum isolates in rainbow trout Oncorhynchus mykiss (Walbaum)

Flavobacterium psychrophilum, the causative agent of bacterial cold‐water disease (BCWD) in freshwater‐reared salmonids, is also a common commensal organism of healthy fish. The virulence potential of F. psychrophilum isolates obtained from BCWD cases in Ontario between 1994 and 2009 was evaluated. In preliminary infection trials of rainbow trout juveniles, significant differences (0% to 63% mortality) in the virulence of the 22 isolates tested were noted following intraperitoneal injection with 10⁸ cfu/fish. A highly virulent strain, FPG 101, was selected for further study. When fish were injected intraperitoneally with a 10⁶, 10⁷ or 10⁸ cfu/fish of F. psychrophilum FPG 101, the 10⁸ cfu/fish dose produced significantly greater mortality (p < 0.05). The bacterial load in spleen samples collected from fish every 3 days after infection was determined using rpoC quantitative polymerase chain reaction amplification and by plate counting. Bacterial culture and rpoC qPCR were highly correlated (R² = 0.92); however, culture was more sensitive than the qPCR assay for the detection of F. psychrophilum in spleen tissue. Ninety‐seven per cent of the asymptomatic and the morbid fish had splenic bacterial loads of <2.8 log₁₀ gene/copies and >3.0 log₁₀ gene copies/reaction, respectively, following infection with 10⁸ cfu/fish.     

Rapid vacuolar sequestration: the horseweed glyphosate resistance mechanism

BACKGROUND: Glyphosate‐resistant (GR) weed species are now found with increasing frequency and threaten the critically important GR weed management system. RESULTS: The reported ³¹P NMR experiments on glyphosate‐sensitive (S) and glyphosate‐resistant (R) horseweed, Conyza canadensis (L.) Cronq., show significantly more accumulation of glyphosate within the R biotype vacuole. CONCLUSIONS: Selective sequestration of glyphosate into the vacuole confers the observed horseweed resistance to glyphosate. This observation represents the first clear evidence for the glyphosate resistance mechanism in C. canadensis. Copyright © 2010 Society of Chemical Industry     

High-Tc superconductors in the two-dimensional limit:

The free modulation of interlayer distance in a layered high-transition temperature (high-Tc) superconductor is of crucial importance not only for the study of the superconducting mechanism but also for the practical application of high-Tc superconducting materials. Two-dimensional (2D) superconductors were achieved by intercalating a long-chain organic compound into bismuth-based high-Tc cuprates. Although the intercalation of the organic chain increased the interlayer distance remarkably, to tens of angstroms, the superconducting transition temperature of the intercalate was nearly the same as that of the pristine material, suggesting the 2D nature of the high-Tc superconductivity.     

Evaluation of point-of-care tests for diagnosis of disseminated intravascular coagulation in dogs admitted to an intensive care unit.

OBJECTIVE: To evaluate the accuracy of point-of-care tests for the diagnosis of disseminated intravascular coagulation (DIC) in dogs and assess the correlation and agreement of results between point-of-care and laboratory tests in the evaluation of hemostatic function. DESIGN: Prospective case series. ANIMALS: 59 critically ill dogs (affected dogs) with clinical signs of diseases known to predispose to DIC and 52 clinically normal dogs. PROCEDURES: Accuracy of the point-of-care tests (activated clotting time [ACT], estimated platelet count and number of schizocytes from a blood smear, plasma total solids [TS] concentration, and the protamine sulfate test) was evaluated, using receiver operating characteristic curves and likelihood ratios. A strategy, using likelihood ratios to calculate a posttest probability of DIC, was tested with 65% used as a threshold for initiation of treatment. Results of laboratory tests (coagulogram and plasma antithrombin III activity) were used as the standard for comparison in each dog. RESULTS: ACT and estimated platelet count provided the best accuracy for detection of DIC. The plasma TS concentration, schizocyte number, and protamine sulfate test had poor accuracy. The strategy using post-test probability of DIC identified 12 of 16 affected dogs that had DIC. Estimated platelet count was correlated and had acceptable clinical agreement with automated platelet count (r = 0.70). The plasma TS (r = 0.28) concentration and serum albumin (r = 0.63) concentration were not accurate predictors of plasma antithrombin III activity. The ACT did not correlate with activated partial thromboplastin time (r = 0.28). CONCLUSIONS AND CLINICAL RELEVANCE: Strategic use of likelihood ratios from point-of-care tests can assist clinicians in making treatment decisions for dogs suspected to have DIC when immediate laboratory support is unavailable.