Accuracy testing of a new stereotactic CT -guided brain biopsy device in the dog

The accuracy testing of a new CT -guided stereotactic device was undertaken via an experimental study. Ten dog cadaver heads were submitted to a CT examination and a brain target was determined (coordinates: x1, y1, z1). 0.3 ml of a radiopaque paste was injected in this chosen point. The head was analysed twice by CT and the centre of the injection (x2, y2, z2) was measured on slices. Tridimensional statistical analysis of the variance of the two points was carried out. The procedure always led to the injection of the radiopaque paste and created an intracerebral mass which gave a measurable image on CT examination. The distance between the original target and the centre of the injection was 2.9 +/- 1.08 mm. It is concluded that this new device allows the opportunity to perform stereotactic CT -guided brain biopsy for all unknown brain lesions exceeding 6 mm in diameter in the dog.     

Stereotactic CT-guided brain biopsy in the dog

This study evaluated the accuracy of a new stereotactic CT-guided brain biopsy (SCTGBB) device on 23 client-owned dogs which presented with a brain lesion. Biopsy of the lesion was achieved in 95 per cent of cases. The target tissue was not sampled in one dog. Complications were observed in six dogs. Two dogs with highly vascularised brainstem tumours died after SCTGBB. Minor complications (slight variation in the neurological status) were observed in a further four cases. A diagnosis was reached in 16 dogs after cytological examination and in 21 dogs after histological evaluation. SCTGBB is an accurate diagnostic method for the diagnosis of brain lesions.     

Effect of genetic resistance of the hen to Salmonella carrier-state on incidence of bacterial contamination: synergy with vaccination

Salmonella is one of the major sources of toxi-infections in humans. The association between egg consumption and Salmonella outbreaks is a serious economic and public health problem. To control the incidence of Salmonella in poultry flocks, many prophylactic means have been developed but none allows a total reduction of the risk. In a previous study, we derived mathematical models for Salmonella transmission and used them to appreciate the most important factors of variation of egg contamination rate and thus of risk of human contamination. Thanks to recent data of a selection experiment for increased or decreased rate of carrier-state (also called divergent selection), we showed that mixing, in an equal proportion, animals issued from a line selected for a lower (denoted Sal-) or higher propensity to carry Salmonella (denoted Sal+) results in a reduction by half of the maximal percentage of contaminated animals but does not accelerate the extinction of the disease. Vaccination and selection should be synergic, since a former contamination reduces the maximal prevalence by 45 and 71%, respectively, in Sal+ or Sal- flocks respectively. These results show the interest in the introduction, even at a rather moderate percentage, of animals selected for a reduced rate of Salmonella carrier-state within commercial flocks. This could be achieved by using one or more selected lines in commercial crosses. These results must be confirmed experimentally while the mathematical model could be extended with minor modifications to other animal species or pathogenic species.     

Effects of radiotherapy on pituitary corticotroph macrotumors in dogs: a retrospective study of 12 cases

The efficacy of low doses of radiotherapy for the treatment of pituitary corticotroph macrotumors in dogs is evaluated retrospectively. Twelve dogs with pituitary-dependent hyperadrenocorticism and a large pituitary tumor treated with 36 Gy of radiation were included. Radiation was delivered in 12 fractions of 3 Gy over a 4- to 6-week period. Effects of radiation therapy on tumor size were assessed by computed tomography scans; a decrease was observed in 11 dogs (decrease > 50% in 6 dogs). Three dogs were reirradiated due to major tumor regrowth or a lack of tumor decrease (mean total dose: 22 Gy given in 3-Gy fractions over 3 or 4 weeks). The mean and median survival times following the initiation of radiotherapy were 22.6 months (688 days) and 17.7 months (539 days), respectively. These data are consistent with previous findings, based on high-dose radiation, showing that radiotherapy is a useful option for treating pituitary corticotroph macrotumors in dogs. Furthermore, computed tomography follow-up of the treated dogs demonstrates objectively the efficacy of radiotherapy against corticotroph tumors in dogs.     

Determining the bioavailability of contaminants and assessing the quality of sediments

Background, Aims and Scope  Our study determined the role of light, aeration, grain size, amount of sediments and of water, density of animals and presence of additional food on the movement of Ilyanassa obsoleta. Spiked relative to reference sediments were also tested for avoidance or preference by the mud snails. Our goal was to develop exposure conditions to be used in future assessment studies of the environmental quality of sediments inhabited by mud snails. The behavioural response of the snails towards different concentrations of contaminated Halifax Harbour sediments placed in one half of a tank relative to reference sediments in the other half is examined in Part 2 and a chemical link investigated. Methods  Animals were exposed in 7 L aquaria at 12°C to their native sediments placed in one or two halves of a tank and the effect due to the presence of a light source, air bubbles, sediment grain size, added algae examined relative to the snails’ behaviour. Preference or avoidance of one half of a tank relative to the second half, the immersed or dry glass surface represented the various media to be chosen by snails. After choosing the optimum set up, exposures were performed in triplicate, under slightly differing initial placement of the snails to compare means and variability in the results. Three specific biogenic chemicals, cholesterol, coprostanol and a fatty acid methyl ester (FAME) were spiked at 0.002, 0.01, 0.05, 0.25 and 1.2 mg/g, dry weight of sediment. A hexane, dichloromethane and methanol extract of harbour sediment were also spiked in reference sediments. In all cases, the location of the snails was recorded over a period extending up to 96 hrs. Results  Twenty snails exposed during a 72 hrs period in commercial 7 L tanks containing 50 g of sediments (wet weight) in the bottom half of a tank filled half way with seawater represented the chosen conditions to test the avoidance/preference behaviour of snails for part of a tank. The presence of additional food on sediments attracted snails within 24 hrs of exposure. Discussion  A general lack of preference was indicated in exposures to three biologically derived compounds spiked in reference sediments, i.e. a C-18 FAME, cholesterol and coprostanol. The repelling properties of a harbour sediment extract pointed to a role for non polar chemicals. Conclusions  It is proposed that behaviour reflects a balance between the repelling effects of contaminants and the attractive value of food. The present study provides a robust green assessment tool that is easy to set up to assess the quality of sediments. Recommendations and Perspectives  The interpretation of field observations regarding the abundance of animals during environmental assessments must consider both nutritional and toxicological causes. Additional laboratory exposures are needed to determine which chemicals play a role in the field.     

Phosphorus,potassium and calcium concentration limits in bean plants grown under deficiency after a period of sufficiency

Bush bean plants (Phaseolus vulgaris L. cv Tacacarigua) were grown under deficient P, K or Ca nutrient solutions after seven days in sufficiency and relative growth rate, root weight ratio, specific leaf area, leaf area development and nutrient concentration profiles in the dry matter of succesive leaves, analyzed throughout ontogeny. Acute Deficiency Concentration Limits (ADCL) were defined for P (0.14%) and K (1.20%) as the concentration in the leaves able to sustain a state of marginal growth, and may indicate the physiological condition in which restoration of optimal supply may not be followed by a recovery of the plants. The continuation of growth, dry matter dilution and retranslocation within the plant are suggested as major determinants of ADCL.     

Motivations for Sharing Bushmeat with an Urban Diaspora in Indigenous Australia

The hunting and trade of bushmeat is a significant issue. The sharing of marine bushmeat between Australian Torres Strait Islanders and their mainland urban diaspora was documented from a diaspora perspective by collecting quantitative and qualitative data from communities in three mainland cities. Motivations for sharing dugong and turtle meat were almost exclusively cultural and mostly occurred when a diaspora member visited Torres Strait, when Torres Strait Islanders visited their mainland family, during Islander ceremonies, or when goods were exchanged as gifts. Each respondent consumed relatively little dugong and turtle meat (<1–2% of annual meat consumption, or < 1 kg per person per annum). Sharing bushmeat strengthened social capital and reinforced cultural identity. Harnessing the social capital generated from the sharing of bushmeat to engage the urban diaspora in dugong and turtle management activities in the Torres Strait could enhance the legitimacy and effectiveness of such initiatives.     

Root morphology and acid phosphatase activity in tomato plants during development of and recovery from phosphorus stress

Changes in root morphology and acid phosphatase activity (APA) were followed during the developent of P‐deficiency in tomato plants grown for 7, 14, and 21 days in 0.16 P well aereated nutrient solutions, followed by a period of sufficiency (recovery) in 1 mM P. Plants were harvested weekly for APA, dry weight, and P concentration in roots, stems and leaves, and every 2 weeks for root morphology determinations. APA was highly correlated to development and recovery from P stress. Mixmium values were attained during growth under deficiency and decreased to that of the control plants after a period of recovery in 1 mM P nutrient solutions. Total root weight and average root diameter decreased under P‐stress and root surface area per unit dry weight increased. Efficiency of P utilization (g dry weight/mg absorbed P) was much higher at the end of the stress period but approached that of the controls as P‐supply was restored to sufficiency levels. The implications of these results in developing rapid and reliable screening technigues to detect successful plant performance under P‐stress is discussed.     

Inheritance and Mechanisms of Resistance to Tebuconazole, a Sterol C14-Demethylation Inhibitor, inNectria haematococca

Genetic control and mechanisms of resistance to tebuconazole, a sterol C14-demethylation inhibitor, were investigated in the phytopathogenic fungusNectria haematococca. Resistant mutants have been selected from the laboratory, following UV irradiation. They have been characterized through genetic crosses and mutations in at least three genes were found to be responsible for resistance. The genesTeb1, Teb2, andTeb3were clearly identified, a fourth gene calledTeb4could be hypothesized. Mutations at lociTeb2andTeb3induced pleiotropic effects such as reduced sporulation and growth rate, mycelium pigmentation (Teb2), or altered ascospore viability (Teb3). The resistance levels determined by mutations in the different genes were relatively low (below 10). When associated in double mutants, the additive effect was recorded. Cross-resistance toward other sterol C14-demethylation inhibitors was observed in all the resistant strains, except in theTeb4-carrying strain; moreover, for some C14-demethylation inhibitors hypersensitivity was expressed. A constitutive energy-dependent efflux seemed implicated in the mechanism of resistance for theTeb1-carrying strain and probably also for theTeb2andTeb3-carrying strains. However, theTeb4-carrying strain exhibited a kinetic of fungicide uptake similar to that of the wild-type strain. The sterol profile of theTeb4-carrying strain was similar to that of all the other resistant mutants and wild-type strains. Thus the resistance mechanism induced by mutation at theTeb4locus has not been found yet.