Evaluation of the agar-gel immunodiffusion test in the diagnosis of canine blastomycosis

The agar-gel immunodiffusion test was used to evaluated 35 dogs with histopathologically confirmed blastomycosis and 98 dogs without blastomycosis. The test had a sensitivity of 91% and a specificity of 96%. Thirteen of the dogs treated for blastomycosis were tested at 6 to 33 months after treatment with amphotericin B. Ten of 13 dogs became seronegative and 3, though clinically normal, remained seropositive at 19, 20, and 20 months, respectively, after amphotericin treatment.     

Polymorphonuclear proteolytic activity and milk composition change

Relationships between Quarter Milk Cell Count (QMCC) and Tank Milk Cell Count (TMCC) with milk biochemical and technological parameters in milk and dairy products were investigated. All parameters measured were affected by the increase of TMCC and QMCC between 0 and 600 000 cells/mL. The variable effect of lactation stage which is different for different authors, is discussed. The three mechanisms, measured during the inflammation of the udder, implicated in the modification of milk quality are described (a decrease in synthesis, a decrease in the milk barrier permeability and an increase in proteolytic activities). The direct effect of plasmin in caseinolysis is well known; the specific role of the increase of somatic cells (especially PMN) in the modification of milk quality is described. Several specific proteolytic activities of PMN are described and the impact of these activities on caseinolysis is evaluated. Two hypothetical mechanisms of caseinolysis by PMN are suggested and a synthetic scheme of the role of plasmin, bacteria and somatic cells in caseinolysis is discussed.     

Monitoring of atrazine treatment on soil bacterial,fungal and atrazine-degrading communities by quantitative competitive PCR

We report the development of quantitative competitive (QC) PCR assays for quantifying the 16S, 18S ribosomal and atzC genes in nucleic acids directly extracted from soil. QC-PCR assays were standardised, calibrated and evaluated with an experimental study aiming to evaluate the impact of atrazine application on soil microflora. Comparison of QC-PCR 16S and 18S results with those of soil microbial biomass showed that, following atrazine application, the microbial biomass was not affected and that the amount of 16S rDNA gene representing 'bacteria' increased transitorily, while the amount of 18S rDNA gene representing fungi decreased in soil. In addition, comparison of atzC QC-PCR results with those of atrazine mineralisation revealed that, in response to atrazine treatment, the amount of atzC gene increased transitorily in soil pre-treated with atrazine, suggesting that accelerated atrazine biodegradation in soil could be due to a transient increase in the size of the atrazine mineralising community.     

Detection of Salmonella organisms and assessment of a protocol for removal of contamination in horse stalls at a veterinary teaching hospital

OBJECTIVES: To assess methods of detecting environmental contamination with Salmonella organisms and evaluate a cleaning and disinfection protocol for horse stalls in a veterinary teaching hospital. DESIGN: Original study. SAMPLE POPULATION: 37 horses with diarrhea likely to be caused by Salmonella infection and their stall environments. PROCEDURES: Fecal samples were collected from horses daily during hospitalization; samples were obtained from stall sites after cleaning and application of disinfectants. Fecal and environmental samples were cultured for Salmonella spp and tested via polymerase chain reaction (PCR) assay to detect Salmonella DNA. RESULTS: 1 horse died and 2 were discharged prior to sample collection. Fecal samples from 9 of 34 horses yielded growth of Salmonella organisms on bacteriologic culture, and 23 yielded positive results via PCR assay on > or = 1 occasion. Among environmental samples from 21 stalls, salmonellae were detected at > or = 1 stall site on 6 of 78 occasions, and > or = 1 stall site yielded positive results via PCR assay on 69 of 77 occasions. Salmonella DNA was detected more frequently in samples of stall drains, cracks, and corners. Salmonella spp were cultured from samples of 3 stalls after both initial and second cleaning and disinfection cycles, but no organisms were detected in samples obtained after use of a peroxygen disinfectant. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that stalls in which horses with salmonellosis were housed should only be used to accommodate newly hospitalized horses after samples (collected after 2 cycles of cleaning and disinfection) from drains, cracks, and corners yield negative results on bacteriologic culture.     

Thoracoscopic treatment of bullous emphysema in 3 dogs

OBJECTIVE: To report thorascopic partial lobectomy for treatment of bullous emphysema in dogs. STUDY DESIGN: Prospective clinical study. ANIMALS: Three dogs with spontaneous pneumothorax. METHODS: Thoracoscopy without pulmonary exclusion was used to identify bulla. The thorascope was introduced into the thorax lateral to the xyphoid process, and instrument portals were made at different levels along the thoracic wall between the third and tenth intercostal spaces. The thorascope was passed through the mediastinum to view the opposite pleural cavity. After identification of bullae, the affected lung was excised using an endoscopic stapler, and the incision line was checked for air leakage. Thoracic drains were used for air aspiration for 2 days after surgery. RESULTS: Bullae were confirmed histologically as emphysematous lesions. Lung inflation did not interfere with identification of bullae or with surgery. All dogs had full recovery without recurrence for 18 to 29 months after surgery. CONCLUSIONS: Identification and ablation of bulla can be performed thoracoscopically without pulmonary exclusion in dogs. CLINICAL RELEVANCE: Thoracoscopy offers several advantages compared with thoracotomy for treatment and diagnosis of idiopathic pneumothorax, including ease of identification of bullae and reduced postoperative pain and morbidity.     

Quantitative PCR monitoring of the effect of azoxystrobin treatments on Mycosphaerella graminicola epidemics in the field

Quantitative PCR and visual monitoring of Mycosphaerella graminicola epidemics were performed to investigate the effect of curative and preventative applications of azoxystrobin in wheat field crops. A non-systemic protectant and a systemic curative fungicide, chlorothalonil and epoxiconazole, respectively, were used as references. PCR diagnosis detected leaf infection by M graminicola 3 weeks before symptom appearance, thereby allowing a clear distinction between curative and preventative treatments. When applied 1 week after the beginning of infection, azoxystrobin curative activity was intermediate between chlorothalonil (low effect) and epoxiconazole. When applied preventatively, none of the fungicides completely prevented leaf infection. There was some indication that azoxystrobin preventative treatments may delay fungal DNA increase more than epoxiconazole at the beginning of leaf infection. Both curative and preventative treatments increased the time lapse between the earliest PCR detection and the measurement of a 10% necrotic leaf area. Azoxystrobin only slightly decreased the speed of necrotic area increase compared with epoxiconazole. Hence, azoxystrobin activity toward M graminicola mainly resides in lengthening the time lapse between the earliest PCR detection and the measurement of a 10% necrotic leaf area. Information generated in this way is useful for optimal positioning of azoxystrobin treatments on M graminicola.     

Development and validation of a radioimmunoassay for thyrotropin in cattle.

In mammals, thyrotropin, or thyroid-stimulating hormone (TSH), assay is used for the diagnosis of primary hypothyroidism. Hypothyroidism is the most common type of thyroid disorder in cattle. The aim of this study was to develop and validate, under physiologic and pathologic conditions, a radioimmunoassay (RIA) for bovine TSH (bTSH). Double RIA was performed with purified bTSH and specific bovine antiserum. Laboratory validation included research of minimal detection limit, accuracy, and reproducibility. The physiologic validation included a thyrotropin-releasing hormone (TRH) challenge performed on euthyroid cows and a follow-up of bTSH concentration over a 24-hour period. Furthermore, bTSH concentration was assayed in a large population of healthy dairy and beef cows to define reference interval. The pathologic validation was made by assaying bTSH and thyroid hormones on healthy and goitrous newborn calves. The minimum detection limit (MDL) for bTSH assay was 1.3 microU/ml. The recovery was 101% to 106%. The intra- and interassay coefficients of variation (CVs) ranged from 5% to 11% and 11% to 15%, respectively. The RIA covered the whole range of physiologic bTSH values, as shown by bTSH values induced by TRH-challenge. A pulsatile secretion of bTSH was observed, accompanied by a diurnal variation with lower night values than day values. Reference intervals of bTSH ranged from 1.3 to 13.0 microU/ml for beef and dairy breeds. Finally, bTSH easily discriminated goitrous newborn calves from healthy ones, leading to the definition of a cutoff value of 35 microU/ml. The bTSH assay positively reacted to physiologic and pathologic conditions. The accuracy and precision of the RIA were satisfying.     

Evolution of Phytophthora infestans populations in the two most important potato production areas of France during 1992–96

Phytophthora infestans isolates, collected in the two most important potato production regions of France (Brittany during 1992–96 and northern France during 1994–96), were analysed for mating type, Gpi and Pep allozyme genotypes, mitochondrial DNA haplotypes, response to metalaxyl and virulence patterns in order to determine the structure of populations. 'New' populations, similar to those observed in northern Europe and characterized by the presence of both mating types, Gpi 90/100 Pep 83/100, Gpi 90/100 Pep 100/100, Gpi 100/100 Pep 100/100 and Gpi 100/100 Pep 83/100 allozyme genotypes, Ia and IIa mitochondrial haplotypes and common races 1.3.4.7, 1.4.10.11, 1.3.4.7.11 and 1.3.4.7.10.11 were present in both areas. A new allozyme genotype ( Gpi 90/90 Pep 83/100), never previously detected in Europe, was discovered in Brittany in 1992, but disappeared in later years. Despite the appearance of the A2 mating type in Brittany in 1996 and in northern France since 1995, both populations were highly homogeneous and probably consisted of a few related clones. No evidence for sexual recombination was obtained. Although Brittany, isolated from other potato production areas, and northern France, situated close to north European production areas where the A2 mating type was discovered some years ago, are two contrasted regions, no geographic substructuring was apparent between the two regions. However, variations in genotypic frequencies and in race composition were observed from one year to the next at a single site, as well as between several local sites during the same year. The role of possible evolutionary mechanisms implicated in these evolutions, especially founder effects, is discussed.     

Pulmonary Eosinophilia Associated with Increased Airway Responsiveness in Young Racing Horses

Horses are known to acquire small airway disease (SAD), an allergen-induced naturally occurring syndrome of reversible obstructive lung disease accompanied by airway hyperresponsiveness and increased inflammatory cell numbers on bronchoalveolar lavage (BAL). This disorder has received scant attention in young racehorses. The purpose of the present report was to examine the effect of BAL eosinophilia in young racehorses on clinical examination, BAL, hematology, airway responsiveness, and on pulmonary function at rest and after a standardized exercise challenge. Five (3 males, 2 females; age 2.6 ± 0.9 years) with a history of respiratory compromise and BAL eosinophil differential count <5% and 6 controls (4 males, 2 females; age 3.5 ± 1.0 years) training and performing to expectation with normal BAL cell differential (eosinophils < 1%) were studied. Respiratory system clinical examination was performed and expressed as a clinical score. Arterial blood gas measurements, CBC, and pulmonary function testing were performed at rest. Pulmonary mechanics measurements were repeated 1 hour and 20 hours after a standardized treadmill exercise challenge. Incremental histamine inhalation challenge was performed and the concentration of histamine effecting a 35% decrease in dynamic compliance (PC35C_Dyn) was determined. Significant differences were noted between and controls with regard to clinical score ( P = .01), blood eosinophils ( P = .04), BAL cell count ( P = .04), BAL macrophage differential ( P = .04), PC35C_Dyn ( P = .008), and tidal volume and respiratory rate at 20 hours following exercise challenge ( P = .05). We conclude that pulmonary eosinophilia and airway hyperresponsiveness are manifest in some young horses without overt airway obstruction at rest. We speculate that these may be early events in the natural progression of heaves.