Evaluation of head-out constant volume body plethysmography for measurement of specific airway resistance in conscious, sedated sheep

OBJECTIVE: To evaluate the use of a modified whole body plethysmograph in awake sheep. ANIMALS: 10 healthy adult sheep. PROCEDURE: Concurrent measurements of specific airway resistance (sR(aw)) and pulmonary resistance (R(L)) were obtained using a novel noninvasive head-out constant-volume plethysmograph and esophageal balloon-pneumotachography, respectively. All data were collected before and after external resistive loading with 1 and 5.6 cm H2O/L/s. Functional residual capacity (FRC) was measured by helium dilution for computation of airway resistance (R(aw)) preloading (R(aw) = sR(aw)/FRC). RESULTS: The sR(aw) and R(L) were closely correlated in 10 adult sheep. Additionally, sR(aw), and R(L) accurately reflected the magnitude of added resistance. The mean FRC was 52 mL/kg and used to calculate R(aw). At baseline, the values for R(aw) were significantly correlated with sR(aw) and R(L). CONCLUSIONS AND CLINICAL RELEVANCE: Precise measurements of sR(aw) and R(aw) at baseline and sR(aw) after external resistive loading were obtained by use of this novel noninvasive plethysmographic technology. This method should have application to veterinary patients or animals used in research in which noninvasive rapid or serial measurements of sR(aw) in the conscious state are required.     

Antibacterial Activity of Long-Chain Polyunsaturated Fatty Acids against Propionibacterium acnes and Staphylococcus aureus

New compounds are needed to treat acne and superficial infections caused by Propionibacterium acnes and Staphylococcus aureus due to the reduced effectiveness of agents used at present. Long-chain polyunsaturated fatty acids (LC-PUFAs) are attracting attention as potential new topical treatments for Gram-positive infections due to their antimicrobial potency and anti-inflammatory properties. This present study aimed to investigate the antimicrobial effects of six LC-PUFAs against P. acnes and S. aureus to evaluate their potential to treat infections caused by these pathogens. Minimum inhibitory concentrations were determined against P. acnes and S. aureus, and the LC-PUFAs were found to inhibit bacterial growth at 32–1024 mg/L. Generally, P. acnes was more susceptible to the growth inhibitory actions of LC-PUFAs, but these compounds were bactericidal only for S. aureus. This is the first report of antibacterial activity attributed to 15-hydroxyeicosapentaenoic acid (15-OHEPA) and 15-hydroxyeicosatrienoic acid (HETrE), while the anti-P. acnes effects of the six LC-PUFAs used herein are novel observations. During exposure to the LC-PUFAs, S. aureus cells were killed within 15–30 min. Checkerboard assays demonstrated that the LC-PUFAs did not antagonise the antimicrobial potency of clinical agents used presently against P. acnes and S. aureus. However, importantly, synergistic interactions against S. aureus were detected for combinations of benzoyl peroxide with 15-OHEPA, dihomo-γ-linolenic acid (DGLA) and HETrE; and neomycin with 15-OHEPA, DGLA, eicosapentaenoic acid, γ-linolenic acid and HETrE. In conclusion, LC-PUFAs warrant further evaluation as possible new agents to treat skin infections caused by P. acnes and S. aureus, especially in synergistic combinations with antimicrobial agents already used clinically.     

Campylobacter

Species within the genus, Campylobacter, have emerged over the last three decades as significant clinical pathogens, particularly of human public health concern, where the majority of acute bacterial enteritis in the Western world is due to these organisms. Of particular concern are the species, C. jejuni and C. coli, which are responsible for most of these gastrointestinal-related infections. Although these organisms have already emerged as causative agents of zoonoses, several aspects of their epidemiology and pathophysiology are only beginning to emerge. Trends in increasing antibiotic resistance are beginning to emerge with oral antibiotics, which may be the drug of choice for when it is necessary to intervene chemotherapeutically. This review wishes to examine (i) emerging clinical aspects of the disease, such as Guillain Barre syndrome (GBS), (ii) the association between these organisms and poultry as a natural host, (iii) environmental aspects of Campylobacter epidemiology, (iv) the emergence of atypical campylobacters (v) emerging trends in antibiotic resistance, (vi) adoption of modern methods for the detection of campylobacters.     

Specific polymerase chain reaction for differential diagnosis of Dirofilaria immitis and Dipetalonema reconditum using primers derived from internal transcribed spacer region 2 (ITS2)

Both Dirofilaria immiti and Dipetalonema reconditum may be found in blood of infected dogs but it is not easy to distinguish D. immitis from D. reconditum in morphology. We cloned and sequenced the contiguous internal transcribed spacer (ITS) region, ITS1-5.8S-ITS2, of these two different parasites and published on GenBank as AF217800 for D. immiti and AF217801 for D. reconditum in this study. We designed two pairs of specific primers derived from ITS2 being used for polymerase chain reaction (PCR). The amplicons of ITS2 from D. immiti and D. reconditum are 302 and 348bp, respectively. Moreover, the limitation for amplifying ITS2 gene using this PCR demonstrated that 1 x 10(-2) microfilaria of each species of parasite smashed or even with mixed samples could be detected and the PCR products were predicted as the same as that described above. Thus, D. immiti and D. reconditum could be differentially diagnosed by this specific PCR. Seventeen clinical cases were evaluated and all of them were correctly identified. In this study, ITS1-5.8S-ITS2 of D. immiti or D. reconditum were the first time sequenced and analyzed. No significant similarity of ITS1 and ITS2 between D. immiti and D. reconditum could be observed.     

Bactericidal properties of pradofloxacin against veterinary pathogens

Pradofloxacin is a new veterinary 8-cyano-fluoroquinolone developed for use against bacterial infections in dogs and cats involving both aerobic and anaerobic bacteria. The minimal bactericidal concentrations have been determined against clinical isolates of Staphylococcus pseudintermedius, Staphylococcus aureus, Escherichia coli, Pasteurella multocida, Streptococcus canis, Proteus spp., Fusobacterium spp., Porphyromonas gingivalis and Prevotella species. A subset of these species was selected, and the in vitro rate of kill by pradofloxacin was determined. For 27 of the 30 tested aerobic strains the pradofloxacin MBC was within two doubling dilutions of the MIC. For the remaining strains, the MIC and MBC were within three to four doubling dilutions. Pradofloxacin also demonstrated bactericidal activity against all anaerobic strains, and the MBC was equal to the MIC for four of the strains, within 1 doubling dilution for three strains, within 2 dilutions for a further 3 strains and within 3 dilutions for the remaining five strains. As pradofloxacin concentration was increased, a faster rate of killing was observed; bactericidal effects were seen in all cases at concentrations ≤ 0.25 μg/mL. The bactericidal activity against the anaerobic strains was marked, of particular relevance was the complete absence of regrowth even at 48 h at concentrations as low as 0.125 μg/mL. In conclusion, pradofloxacin exhibits clear bactericidal activity in terms of MBC and kill kinetics against aerobic and anaerobic clinical isolates from dogs and cats at concentrations that are greatly exceeded within the systemic circulation after administration of the recommended therapeutic doses to the target animals. It is expected that such a rapid rate of kill will play a significant role in clinical efficacy. These data demonstrate the complete and rapid killing of anaerobic bacteria by a veterinary 8-cyano-fluoroquinolone.     

Hatch rate of channel catfish Ictalurus punctatus (Rafinesque 1818) eggs treated with 100 mg L−1 copper sulphate pentahydrate

Catfish hatcheries use copper sulphate pentahydrate (CuSO₄·5H₂O) as an economical control for saprolegniasis on eggs. This study determines hatch rate of channel catfish, Ictalurus punctatus (Rafinesque 1818), eggs in hatching troughs containing 23.8 °C flow‐through well water when treated with 100 mg L^?1 CuSO₄·5H₂O (10 times the proposed therapeutic dose). Eggs were treated daily until the embryos reached the eyed stage. Fry survival in the control and 100 mg L^?1 CuSO₄·5H₂O treatments was significantly different (15% and 71% respectively). This study demonstrates that there is a considerable margin of safety in using CuSO₄·5H₂O as a catfish egg treatment to control saprolegniasis.     

Evaluation of an ear cleanser for the treatment of infectious otitis externa in dogs

Thirty-one ears (16 dogs) with otitis externa originating from bacterial or yeast infections were enrolled in a study to evaluate the in vivo efficacy of an ear cleanser containing 2.5% lactic acid and 0.1% salicylic acid for the treatment of infectious otitis externa. The affected ears were treated with the ear cleanser twice daily for 2 weeks and evaluated after 1 and 2 weeks of treatment. The ear cleanser was effective in resolution of infection in 67.7% of the ears, and clinical signs of infectious otitis externa were significantly reduced within 2 weeks.     

Depleting neuronal PrP in prion infection prevents disease and reverses spongiosis

The mechanisms involved in prion neurotoxicity are unclear, and therapies preventing accumulation of PrPSc, the disease-associated form of prion protein (PrP), do not significantly prolong survival in mice with central nervous system prion infection. We found that depleting endogenous neuronal PrPc in mice with established neuroinvasive prion infection reversed early spongiform change and prevented neuronal loss and progression to clinical disease. This occurred despite the accumulation of extraneuronal PrPSc to levels seen in terminally ill wild-type animals. Thus, the propagation of nonneuronal PrPSc is not pathogenic, but arresting the continued conversion of PrPc to PrPSc within neurons during scrapie infection prevents prion neurotoxicity.     

Effects of phenology,water availability and seed source on loblolly pine biomass partitioning and transpiration

One-year-old loblolly pine (Pinus taeda L.) seedlings from four seed sources (Arkansas, Georgia, Texas and Virginia) grown in 1-m-deep sand-filled pits in two water regimes (well-watered and drought) were studied, to gain insight into the process of seedling establishment. Whole-plant transpiration was measured biweekly from July to December. Whole-plant harvests were conducted at 6-week intervals from April to December. Whole-plant transpiration and transpiration per unit leaf and root area were affected by treatment, seedlot and phenology. Seedlings of the Arkansas seedlot maintained significantly higher transpiration rates per unit leaf and root area during drought than seedlings of the Virginia, Georgia or Texas seedlots, but did not accumulate greater biomass. The high transpiration rates of the Arkansas seedlings were attributed to their deep root systems. Allometric relationships indicated that, relative to the whole plant, biomass allocation to needles of drought-treated seedlings was enhanced during the summer (allometric ratio 1.09), whereas allocation to roots was enhanced in the spring and fall (allometric ratios of 1.13 and 1.09, respectively). Relative to the whole plant, biomass allocation to needles of well-watered seedlings was enhanced throughout the experiment (allometric ratio of 1.16 declining to 1.05), whereas the allometric ratio of root to total biomass was 0.89 or less throughout. Allometric relationships also indicated variation in biomass partitioning to roots in three soil layers (0-30, 30-60 and 60-100 cm), which differed among harvests in each soil layer. Root growth in both well-watered and drought-treated seedlings was concentrated in the top soil layer in the spring, shifted to the middle and bottom soil layers in the summer, and then increased in the top soil layer in the fall. Compared with well-watered seedlings, drought-treated seedlings had higher rates of root growth in the bottom soil layer in the fall, a characteristic that would confer tolerance to future periods of limited soil water availability.