FEASIBILITY FOR DETECTING LIVER METASTASES IN DOGS USING GADOBENATE DIMEGLUMINE‐ENHANCED MAGNETIC RESONANCE IMAGING

Early detection of liver metastases may improve the prognosis for successful treatment in dogs with primary tumors. Hepatobiliary‐specific contrast agents have been shown to allow an increase in magnetic resonance imaging (MRI) detection of liver metastases in humans. The purpose of this prospective study was to test the feasibility for using one of these agents, gadobenate dimeglumine, to detect liver metastases in dogs. Ten consecutive dogs known to have a primary tumor were recruited for inclusion in the study. All dogs were scanned using the same protocol that included a T2‐weighted respiratory‐triggered sequence, T1 VIBE, diffusion‐weighted imaging, and 3D‐FLASH before and after dynamic injection of gadobenate dimeglumine contrast medium. Delayed imaging was performed less than 30 min after injection and up to 60 min in two cases. Histological analysis of liver lesions identified in delayed phases was performed for each case and confirmed metastatic origin. In all cases, lesion number detected in hepatobiliary contrast‐enhanced sequences was statistically higher than in other sequences. Optimal lesion detection occurred with a 3D‐FLASH sequence acquired in the transverse plane and less than 30 min after injection. Findings indicated that gabobenate dimeglumine enhanced MRI is a feasible technique for detecting liver metastases in dogs.     

IMAGING DIAGNOSIS—PARAGANGLIOMA OF THE CAUDA EQUINA: MR FINDINGS

The magnetic resonance imaging features of a cauda equina paraganglioma in a 5‐year‐old dog are described. Imaging revealed a well‐defined, strongly contrast‐enhancing mass invading the adjacent vertebral body and infiltrating the intervertebral foramen bilaterally. Flow void, compatible with increased drainage veins around the mass, and macroscopically visible neovessels in contrast‐enhanced magnetic resonance angiography, as reported in numerous human studies, were not visible in this single case. The tumor recurred despite aggressive surgery and radiotherapy. This neoplasm should be considered in the differential diagnosis of cauda equina abnormalities in dogs.     

Structure and function of microbial communities in the rhizosphere of Scots pine after tree-felling

We evaluated changes occurring in the rhizosphere microbial communities of Scots pine (Pinus sylvestris L.) due to tree-felling and decrease of the photosynthetic C flow into the soil under field conditions over one growing season. Samples were taken from tree rhizospheres, freshly felled stump rhizospheres and bulk soil. We used culture dependent (CFU counts, community level physiological profiles, CLPPs) and independent methods (fluorogenic MUF-substrates, PLFA pattern and PCR-DGGE) to monitor the microbial communities in soil samples. The numbers of cultivable bacteria and amounts of phosphatase activity in the rhizosphere of trees were significantly higher compared with those in the bulk soil. The organic C consuming community measured by CLPP was stimulated directly after the tree-felling in stump rhizospheres; utilization of the disintegration components of cellulose, hemicellulose and chitin increased. Furthermore, bacterial and fungal biomass as well as chitin decomposers (CFU) increased in the stump rhizosphere. After 11 weeks of tree-felling the stump rhizosphere soluble PO₄-P and NH₄-N as well as amounts of total C and N began to resemble the concentrations measured in the bulk soil. However, the stump rhizosphere community structure detected by PLFA and PCR-DGGE still resembled that of the tree rhizosphere.     

Assessing the Impact of Effluents from a Modern Wastewater Treatment Plant on Breakdown of Coarse Particulate Organic Matter and Benthic Macroinvertebrates in a Lowland River

Wastewater treatment plants (WWTP) with insufficient technologies for wastewater purification often cause a distinct nutrient pollution in the receiving streams. The increased concentrations of dissolved nutrients can severely disturb the ecological integrity of streams, which has been recently shown for basic ecosystem processes like mineralization of coarse particulate organic matter (CPOM). The present study investigated the impact of a modern WWTP (Zentralkläranlage Jena) on breakdown rates of CPOM exposed in net bags (1 mm mesh size) to the effluent of a large municipal WWTP and an upstream control site in the Saale River (Thuringia, Germany) from April to October 2005. Control and effluent site differed significantly in water chemistry with increased concentrations of dissolved organic carbon (DOC), ammonium, sulfate, and chloride at the effluent site, while the control site displayed higher concentrations of nitrate. However, breakdown rates of toothpickers and small twigs were not significantly different between the sites, whereas breakdown rate of leaf litter was significantly higher at the effluent site (k?=?0.0124 day^?1) than at the control site (k?=?0.0095 day^?1). Benthic invertebrate assemblages inhabiting the sandy stream bed at both sites were dominated by Chironomidae and Oligochaeta, typical inhabitants of fine sediments. Although the Shannon diversity of the benthic invertebrates was slightly higher at the effluent site (0.85) than at the control site (0.63), no significant difference could be detected. Bacterial numbers in water samples and surface biofilms on glass slides also displayed no significant differences between the two sites. This study showed that the effluents of a WWTP with modern technologies for wastewater purification did not directly affect breakdown rates of CPOM, bacteria numbers in epibenthic biofilms and the water column, and the community composition of sediment inhabiting aquatic macroinvertebrates in an effluent-receiving river with already increased concentrations of dissolved nutrients.     

Effect of xanthan on flavor release from thickened viscous food model systems

The influence of xanthan concentration (0, 0.02, 0.1, 0.4, and 0.8% w/w) and bulk viscosity on the release of 20 aroma compounds of different chemical classes (5 aldehydes, 4 esters, 5 ketones, 3 alcohols, and 3 terpenes) was evaluated in xanthan-thickened food model systems having different viscosities. Interactions between flavor compounds and xanthan were assessed by measuring air-liquid partition coefficients, K, of aroma compounds in pure water and in the xanthan solutions by static headspace gas chromatography. Mass transfer of aroma compounds was estimated by dynamic headspace gas chromatography. Notably, limonene and some of the esters and aldehydes exhibited decreased K values in the presence of xanthan, indicating that the release of these volatile aroma compounds was reduced due to interaction with the xanthan matrix. The degree of interaction depended on the physicochemical characteristics of the aroma compounds. A similar tendency was observed at nonequilibrium with the decreases in release rates being most pronounced for limonene, followed by the esters and aldehydes, with no effect for ketones and an apparent "salting out" effect for alcohols. The reduction in flavor release by xanthan was thus dependent on the physicochemical properties of the aroma compounds and was apparently a result of the aroma-xanthan interactions and not influenced by the viscosity of the system itself.     

Host-parasite coevolutionary conflict between Arabidopsis and downy mildew

Plants are constantly exposed to attack by an array of diverse pathogens but lack a somatically adaptive immune system. In spite of this, natural plant populations do not often suffer destructive disease epidemics. Elucidating how allelic diversity within plant genes that function to detect pathogens (resistance genes) counteracts changing structures of pathogen genes required for host invasion (pathogenicity effectors) is critical to our understanding of the dynamics of natural plant populations. The RPP13 resistance gene is the most polymorphic gene analyzed to date in the model plant Arabidopsis thaliana. Here we report the cloning of the avirulence gene, ATR13, that triggers RPP13-mediated resistance, and we show that it too exhibits extreme levels of amino acid polymorphism. Evidence of diversifying selection visible in both components suggests that the host and pathogen may be locked in a coevolutionary conflict at these loci, where attempts to evade host resistance by the pathogen are matched by the development of new detection capabilities by the host.     

Negligible effect of ions on the hydrogen-bond structure in liquid water

The effects of ions on bulk properties of liquid water, such as viscosity, have suggested that ions alter water's hydrogen-bonding network. We measured the orientational correlation time of water molecules in Mg(ClO4)2, NaClO4, and Na2SO4 solutions by means of femtosecond pump-probe spectroscopy. The addition of ions had no influence on the rotational dynamics of water molecules outside the first solvation shells of the ions. This result shows that the presence of ions does not lead to an enhancement or a breakdown of the hydrogen-bond network in liquid water.     

Public health. Building microbial forensics as a response to bioterrorism

Combating bioterrorism is a challenge to all of us. To be proactive, the U.S. Government has formalized the discipline of "microbial forensics" to deter and attribute perpetrators of such acts. This Policy Forum describes the foundations of the microbial forensics program: the creation of a national bioforensics laboratory, a partnership laboratory network, and a peer-consensus scientific working group and the promulgation of quality assurance guidelines.