Vegetative Endocarditis Associated with Escherichia coli in a Dromedary Camel

Veterinary Research Communications -     

Development of a method for determination of cyanide concentrations in serum and rumen fluid of cattle

OBJECTIVES: To develop a reliable method for measurement of cyanide concentrations in cattle, using gas chromatography-mass spectrometry (GC-MS), and establish reference ranges of cyanide concentrations in cattle. ANIMALS: 52 Fleckvieh cattle. PROCEDURE: Cattle were allocated to 3 groups; 12 were fed leguminous grass and hay, 36 were fed whole-maize and corn-cob silages, and 4 were fed other feedstuffs. Samples of blood, rumen fluid, and liver were collected at time of slaughter. Serum, rumen fluid, and liver homogenate were assayed for cyanide content, using a derivatization procedure. A technique for analysis by GC-MS that used selected ion monitoring was developed. RESULTS: Compared with a spectrophotometric method, detection of cyanide in serum and rumen fluid by use of GC-MS was selective and sensitive, with a limit of detection of 0.7 microM. Spectrophotometric analysis yielded false-negative and false-positive results. Thus, the GC-MS method was used for subsequent analysis. In all cattle except 1, cyanide concentration ranged from < 0.7 to 35 microM in serum and from < 0.7 to 28 microM in rumen fluid; cyanide concentration in that 1 animal was 206 microM. Cattle fed clover, grass, grass hay, and clover hay had 8.3- to 8.6-fold higher mean cyanide concentrations in rumen fluid and serum than cattle fed whole-maize and corn-cob silages. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study suggest a reference range that should be useful for aiding in the diagnosis of cyanide poisoning. Also, cattle can apparently accommodate a serum cyanide concentration of 206 microM without adverse effects.     

Age determination of coarse woody debris with radiocarbon analysis and dendrochronological cross-dating

To study the decay of coarse woody debris (CWD) in forest ecosystems, it is necessary to determine the time elapsed since tree death, which is difficult at advanced decay stages. Here, we compare two methods for age determination of CWD logs, dendrochronological cross-dating and radiocarbon analysis of the outermost tree ring. The methods were compared using samples from logs of European beech, Norway spruce and Sessile oak decomposing in situ at three different forest sites. For dendrochronological cross-dating, we prepared wood discs with diameters of 10–80 cm. For radiocarbon analysis, cellulose was isolated from shavings of the outermost tree rings. There was an overall good agreement between time of death determined by the two methods with median difference of 1 year. The uncertainty of age determination by the radiocarbon approach did not increase with decreasing carbon density, despite incomplete separation of chitin from the extracted cellulose. Fungal chitin has the potential to alter the radiocarbon signature of tree rings as the carbon for chitin synthesis originates from different sources. Significant correlations between year of tree death and carbon density of wood were found for beech and spruce, but not for oak due to relatively small decreases in carbon density within 50–60 years. Total residence times of CWD were calculated from these correlations and revealed 24 years for beech and 62 years for spruce. The uncertainty of total residence times results mainly from huge natural variability in carbon density of CWD rather than uncertainty in the age determination. The results suggest that both methods are suitable for age determination of CWD.     

Detection and characterization of potentially zoonotic viruses in faeces of pigs at slaughter in Germany

Pigs can harbour a variety of viruses in their gastrointestinal tract. Some of them are closely related to human viruses and are therefore suspected to have a zoonotic potential. Only little is known about the presence of those viruses in pigs at slaughter. However, by contamination of meat with zoonotic viruses during the slaughtering process, food-borne transmission to humans may be possible. Here we analyzed 120 faecal samples of pigs at slaughter from 3 different geographical regions of Germany for the presence of astrovirus (AstV), encephalomyocarditis virus (EMCV), hepatitis E virus (HEV), norovirus genogroup II (NoV GII) and group A rotavirus (GARV). Using real-time RT-PCR, the most frequently detected virus was AstV, which was present in 20.8% of the samples, followed by NoV GII with a detection rate of 14.2%. EMCV, HEV and GARV were found only occasionally with detection rates of 4.2%, 2.5% and 0.8%, respectively. Analyses of partial genome sequences of the viruses indicated that the detected AstV and NoV GII mainly represented typical pig virus strains, which have not been detected in humans so far. However, the GARV and HEV strains were more closely related to human strains. The results indicate that enteric viruses, some of them with zoonotic potential, are present in pig faeces at slaughter. Application of good hygiene practice is necessary to minimize the risk of introducing these viruses into the food and to prevent virus transmission to highly exposed persons such as slaughterers and veterinarians.     

A "Double-Diamond Superlattice" Built Up of Cd17S4(SCH2CH2OH)26 Clusters

A simple preparation of Cd(17)S(4)(SCH(2)CH(2)OH)(26) clusters in aqueous solution leads to the formation of colorless blocky crystals. X-ray structure determinations revealed a superlattice framework built up of covalently linked clusters. This superlattice is best described as two enlarged and interlaced diamond or zinc blende lattices. Because both the superlattice and the clusters display the same structural features, the crystal structure resembles the self-similarities known from fractal geometry. The optical spectrum of the cluster solution displays a sharp transition around 290 nanometers with a large absorption coefficient ( approximately 84,000 per molar per centimeter).     

The structure of a mycobacterial outer-membrane channel

Mycobacteria have low-permeability outer membranes that render them resistant to most antibiotics. Hydrophilic nutrients can enter by way of transmembrane-channel proteins called porins. An x-ray analysis of the main porin from Mycobacterium smegmatis, MspA, revealed a homooctameric goblet-like conformation with a single central channel. This is the first structure of a mycobacterial outer-membrane protein. No structure-related protein was found in the Protein Data Bank. MspA contains two consecutive beta barrels with nonpolar outer surfaces that form a ribbon around the porin, which is too narrow to fit the thickness of the mycobacterial outer membrane in contemporary models.     

340,000-year centennial-scale marine record of Southern Hemisphere climatic oscillation

In order to investigate rapid climatic changes at mid-southern latitudes, we have developed centennial-scale paleoceanographic records from the southwest Pacific that enable detailed comparison with Antarctic ice core records. These records suggest close coupling of mid-southern latitudes with Antarctic climate during deglacial and interglacial periods. Glacial sections display higher variability than is seen in Antarctic ice cores, which implies climatic decoupling between mid- and high southern latitudes due to enhanced circum-Antarctic circulation. Structural and temporal similarity with the Greenland ice core record is evident in glacial sections and suggests a degree of interhemispheric synchroneity not predicted from bipolar ice core correlations.     

Self-assembly of proteins into designed networks

A C4-symmetric tetrameric aldolase was used to produce a quadratic network consisting of the enzyme as a rigid four-way connector and stiff streptavidin rods as spacers. Each aldolase subunit was furnished with a His6 tag for oriented binding to a planar surface and two tethered biotins for binding streptavidin in an oriented manner. The networks were improved by starting with composite units and also by binding to nickel-nitrilotriacetic acid-lipid monolayers. The mesh was adjustable in 5-nanometer increments. The production of a net with switchable mesh was initiated with the use of a calcium ion-containing beta-helix spacer that denatured on calcium ion depletion.     

Efficient inhibition of the Alzheimer's disease beta-secretase by membrane targeting

beta-Secretase plays a critical role in beta-amyloid formation and thus provides a therapeutic target for Alzheimer's disease. Inhibitor design has usually focused on active-site binding, neglecting the subcellular localization of active enzyme. We have addressed this issue by synthesizing a membrane-anchored version of a beta-secretase transition-state inhibitor by linking it to a sterol moiety. Thus, we targeted the inhibitor to active beta-secretase found in endosomes and also reduced the dimensionality of the inhibitor, increasing its local membrane concentration. This inhibitor reduced enzyme activity much more efficiently than did the free inhibitor in cultured cells and in vivo. In addition to effectively targeting beta-secretase, this strategy could also be used in designing potent drugs against other membrane protein targets.