Pharmacokinetics and pharmacodynamics of enrofloxacin and a low dose of amikacin administered via regional intravenous limb perfusion in standing horses

OBJECTIVE: To evaluate the pharmacokinetic-pharmacodynamic parameters of enrofloxacin and a low dose of amikacin administered via regional IV limb perfusion (RILP) in standing horses. ANIMALS: 14 adult horses. PROCEDURES: Standing horses (7 horses/group) received either enrofloxacin (1.5 mg/kg) or amikacin (250 mg) via RILP (involving tourniquet application) in 1 forelimb. Samples of interstitial fluid (collected via implanted capillary ultrafiltration devices) from the bone marrow (BMIF) of the third metacarpal bone and overlying subcutaneous tissues (STIF), blood, and synovial fluid of the radiocarpal joint were collected prior to (time 0) and at intervals after tourniquet release for determination of drug concentrations. For pharmacokinetic-pharmacodynamic analyses, minimum inhibitory concentrations (MICs) of 16 microg/mL (amikacin) and 0.5 microg/mL (enrofloxacin) were applied. RESULTS: After RILP with enrofloxacin, 3 horses developed vasculitis. The highest synovial fluid concentrations of enrofloxacin and amikacin were detected at time 0; median values (range) were 13.22 microg/mL (0.254 to 167.9 microg/mL) and 26.2 microg/mL (5.78 to 50.0 microg/mL), respectively. Enrofloxacin concentrations exceeded MIC for approximately 24 hours in STIF and synovial fluid and for 36 hours in BMIF. After perfusion of amikacin, concentrations greater than the MIC were not detected in any samples. Effective therapeutic concentrations of enrofloxacin were attained in all samples. CONCLUSIONS AND CLINICAL RELEVANCE: In horses with orthopedic infections, RILP of enrofloxacin (1.5 mg/kg) should be considered as a treatment option. However, care must be taken during administration. A dose of amikacin > 250 mg is recommended to attain effective tissue concentrations via RILP in standing horses.     

Differences in body temperature, cell viability, and HSP-70 concentrations between Pelibuey and Suffolk sheep under heat stress

Pelibuey and Suffolk sheep were compared as to their capacity to regulate body temperature under environmental hyperthermia by measuring their differences in cellular response to heat stress (HS). In a first experiment, seven Pelibuey and seven Suffolk ewes were kept in a climatic chamber for 6 h daily during 10 days (temperatures within the 18 to 39.5 °C range). As chamber temperature rose, sheep rectal temperature increased in both groups, but to a lesser extent in Pelibuey (0.3 °C) than in Suffolk sheep (0.7 °C) (P?<?0.05). In a second experiment, cellular viability was assessed using cultured blood mononuclear cells from 15 Pelibuey and 15 Suffolk sheep. They were incubated at 37 °C for 24 h (control) or 43 °C for 6 h followed by 18 h at 37 °C (HS). In a third experiment, another blood mononuclear cells culture from eight Pelibuey and eight Suffolk sheep was kept at 37 °C for 15 h; these were subsequently cultured for 6 h at 37 °C (controls) or 43 °C (HS). Next, HSP-70 concentration was determined. HS reduced the percentage of viable cells to a greater extent in Suffolk [37 °C (73.7 %) vs. 43 °C (61.9 %); P?<?0.05] than in Pelibuey sheep [37 °C (74.9 %) vs. 43 °C (66.7 %); P?>?0.05]. HS significantly increased HSP-70 average concentrations for both breeds at 43 °C. A significant effect was observed for the breed by temperature interaction (P?<?0.05) caused by a greater difference between Pelibuey and Suffolk at 43 °C (2.85 vs. 0.53 ng/mL, respectively; P?<?0.05) than at 37 °C (0.05 vs. 0.03 ng/mL, respectively; P?>?0.05). In conclusion, Pelibuey sheep show more effective body temperature regulation under conditions of environmental hyperthermia. Also, cell viability after HS was higher in Pelibuey than in Suffolk, an effect that could be mediated by an HSP-70-related mechanism.     

Phenylalanine ammonia lyase activity in chilli CM-334 infected by Phytophthora capsici and Nacobbus aberrans

We tested the hypothesis that PAL activity in chilli plants CM-334 inoculated with Nacobbus aberrans (Na) alone or in combination with Phytophthora capsici (Pc), is lower than in those inoculated only with Pc. At 21 days after nematode inoculation, inoculated plants showed a significant (P < 0.01) reduction of 48% in PAL activity compared to those non-inoculated in two separate experiments. In two other tests, where plants were inoculated with the oomycete 21 days after inoculation with the nematode, PAL activity at 2, 4, 6, 8 and 24 h after inoculation with Pc was significantly higher (Tukey, P < 0.01) in plants inoculated only with Pc than in plants inoculated only with Na or both pathogens (Na+Pc).     

Multilobular tumor of bone in the mandible of a dog

An 8-year-old Siberian husky dog was presented for a mass involving the rostral mandible. Intraoral radiographs demonstrated diffusely irregular bone and displacement of all mandibular incisor teeth. The mass was diagnosed as a grade I multilobular tumor of bone based on incisional biopsy. A bilateral rostral mandibulectomy was performed with tumor negative margins. Oral examination at 14-months following surgery indicated normal healing with minimal side effects and no evidence of tumor recurrence.     

Imazapyr seed dressings for Striga control on acetolactate synthase target-site resistant maize

High herbicide levels can be localized on or near seed of acetolactate synthase (ALS) resistant maize (Zea mays). The magnesium salt of imazapyr was optimal for seed dressings (drenching, priming, and coating), for preventing field damage from parasitic Striga hermonthica (witchweed) in three seasons. Striga emerged on untreated maize from 6 to 12 weeks after planting. There was almost no Striga emergence for 3 months on imazapyr-dressed homozygous ALS-R 3245IR maize seeds. Occasional Striga that emerged and flowered formed no seed by harvest. Dust or polyvinylpyrrolidone adhesive coatings were safer in maize and as effective in Striga control as priming. Seed dressing coupled with pulling Striga escapes reduces infestation and can be used to deplete the Striga seed bank until genetic crop resistance becomes available.     

A Study of Combining Elastin in the Chitosan Electrospinning to Increase the Mechanical Strength and Bioactivity

While electrospun chitosan membranes modified to retain nanofibrous morphology have shown promise for use in guided bone regeneration applications in in vitro and in vivo studies, their mechanical tear strengths are lower than commercial collagen membranes. Elastin, a natural component of the extracellular matrix, is a protein with extensive elastic property. This work examined the incorporation of elastin into electrospun chitosan membranes to improve their mechanical tear strengths and to further mimic the native extracellular composition for guided bone regeneration (GBR) applications. In this work, hydrolyzed elastin (ES12, Elastin Products Company, USA) was added to a chitosan spinning solution from 0 to 4 wt% of chitosan. The chitosan–elastin (CE) membranes were examined for fiber morphology using SEM, hydrophobicity using water contact angle measurements, the mechanical tear strength under simulated surgical tacking, and compositions using Fourier-transform infrared spectroscopy (FTIR) and post-spinning protein extraction. In vitro experiments were conducted to evaluate the degradation in a lysozyme solution based on the mass loss and growth of fibroblastic cells. Chitosan membranes with elastin showed significantly thicker fiber diameters, lower water contact angles, up to 33% faster degradation rates, and up to seven times higher mechanical strengths than the chitosan membrane. The FTIR spectra showed stronger amide peaks at 1535 cm⁻¹ and 1655 cm⁻¹ in membranes with higher concentrated elastin, indicating the incorporation of elastin into electrospun fibers. The bicinchoninic acid (BCA) assay demonstrated an increase in protein concentration in proportion to the amount of elastin added to the CE membranes. In addition, all the CE membranes showed in vitro biocompatibility with the fibroblasts.