Laser ablation-combustion-GC-IRMS--a new method for online analysis of intra-annual variation of delta13C in tree rings

We present a new, rapid method for high-resolution online determination of delta13C in tree rings, combining laser ablation (LA), combustion (C), gas chromatography (GC) and isotope ratio mass spectrometry (IRMS) (LA-C-GC-IRMS). Sample material was extracted every 6 min with a UV-laser from a tree core, leaving 40-microm-wide holes. Ablated wood dust was combusted to CO2 at 700 degrees C, separated from other gases on a GC column and injected into an isotope ratio mass spectrometer after removal of water vapor. The measurements were calibrated against an internal and an external standard. The tree core remained intact and could be used for subsequent dendrochronological and dendrochemical analyses. Cores from two Scots pine trees (Pinus sylvestris spp. sibirica Lebed.) from central Siberia were sampled. Inter- and intra-annual patterns of delta13C in whole-wood and lignin-extracted cores were indistinguishable apart from a constant offset, suggesting that lignin extraction is unnecessary for our method. Comparison with the conventional method (microtome slicing, elemental analysis and IRMS) indicated high accuracy of the LA-C-GC-IRMS measurements. Patterns of delta13C along three parallel ablation lines on the same core showed high congruence. A conservative estimate of the precision was +/- 0.24 per thousand. Isotopic patterns of the two Scots pine trees were broadly similar, indicating a signal related to the forest stand's climate history. The maximum variation in delta13C over 22 years was about 5 per thousand, ranging from -27 to -22.3 per thousand. The most obvious pattern was a sharp decline in delta13C during latewood formation and a rapid increase with spring early growth. We conclude that the LA-C-GC-IRMS method will be useful in elucidating short-term climate effects on the delta13C signal in tree rings.     

Case–control risk factor study of methicillin-resistant Staphylococcus pseudintermedius (MRSP) infection in dogs and cats in Germany

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) has emerged as a highly drug-resistant small animal veterinary pathogen. Although often isolated from outpatients in veterinary clinics, there is concern that MRSP follows a veterinary-hospital-associated epidemiology. This study's objective was to identify risk factors for MRSP infections in dogs and cats in Germany. Clinical isolates of MRSP cases (n = 150) and methicillin-susceptible S. pseudintermedius (MSSP) controls (n = 133) and their corresponding host signalment and medical data covering the six months prior to staphylococcal isolation were analysed by multivariable logistic regression. The identity of all MRSP isolates was confirmed through demonstration of S. intermedius-group specific nuc and mecA. In the final model, cats (compared to dogs, OR 18.5, 95% CI 1.8–188.0, P = 0.01), animals that had been hospitalised (OR 104.4, 95% CI 21.3–511.6, P < 0.001), or visited veterinary clinics more frequently (>10 visits OR 7.3, 95% CI 1.0–52.6, P = 0.049) and those that had received topical ear medication (OR 5.1, 95% CI 1.8–14.9, P = 0.003) or glucocorticoids (OR 22.5, 95% CI 7.0–72.6, P < 0.001) were at higher risk of MRSP infection, whereas S. pseudintermedius isolates from ears were more likely to belong to the MSSP-group (OR 0.09, 95% CI 0.03–0.34, P < 0.001). These results indicate an association of MRSP infection with veterinary clinic/hospital settings and possibly with chronic skin disease. There was an unexpected lack of association between MRSP and antimicrobial therapy; this requires further investigation but may indicate that MRSP is well adapted to canine skin with little need for selective pressure.     

Modification of Marine Natural Product Ningalin B and SAR Study Lead to Potent P-Glycoprotein Inhibitors

In this study, new marine ningalin B analogues containing a piperazine or a benzoloxy group at ring C have been synthesized and evaluated on their P-gp modulating activity in human breast cancer and leukemia cell lines. Their structure-activity relationship was preliminarily studied. Compounds 19 and 20 are potent P-gp inhibitors. These two synthetic analogues of permethyl ningalin B may be potentially used as effective modulators of P-gp-mediated drug resistance in cancer cells.     

APPEARANCE OF THE SACROILIAC JOINT IN VENTRODORSAL RADIOGRAPHS OF THE NORMAL CANINE PELVIS

Radiology of the canine sacroiliac (SI) joint was investigated by obtaining ventrodorsal radiographs of cadaveric pelves and bone specimens (n = 40) marked with solder wire or radiopaque paint to demonstrate the orientation of the sacroiliac joint in various radiographic views. In the following retrospective radiographic study (n = 94 survey sacroiliac joint radiographs), central projections of the sacrum were noted to ease identification of the dorsal, middle and ventral joint components, whereas angled projections of the sacrum had advantages when assessing the cranial joint components. Radiographic assessment was already successful in juvenile dogs older than 5 months. Failure in tracing the outlines of the joint space of the sacroiliac joints is not consistent with alteration of the SI joint. Rather, it was felt that alterations would have assisted in identifying the contours of the SI joints because of an increase in mineralization.     

Isolation and characterization of bone marrow-derived equine mesenchymal stem cells

OBJECTIVE: To isolate and characterize bone marrow-derived equine mesenchymal stem cells (MSCs) for possible future therapeutic applications in horses. SAMPLE POPULATION: Equine MSCs were isolated from bone marrow aspirates obtained from the sternum of 30 donor horses. PROCEDURES: Cells were cultured in medium (alpha-minimum essential medium) with a fetal calf serum content of 20%. Equine MSC features were analyzed to determine selfrenewing and differentiation capacity. For potential therapeutic applications, the migratory potential of equine MSCs was determined. An adenoviral vector was used to determine the transduction rate of equine MSCs. RESULTS: Equine MSCs can be culture-expanded. Equine MSCs undergo cryopreservation in liquid nitrogen without altering morphologic characteristics. Furthermore, equine MSCs maintain their ability to proliferate and differentiate after thawing. Immunocytochemically, the expression of the stem cell marker CD90 can be detected on equine MSCs. The multilineage differentiation potential of equine MSCs was revealed by their ability to undergo adipogenic, osteogenic, and chondrogenic differentiation. CONCLUSIONS AND CLINICAL RELEVANCE: Our data indicate that bone marrow-derived stromal cells of horses can be characterized as MSCs. Equine MSCs have a high transduction rate and migratory potential and adapt to scaffold material in culture. As an autologous cell population, equine MSCs can be regarded as a promising cell population for tissue engineering in lesions of the musculoskeletal system in horses.     

Anisotropy of wood vibrational properties: dependence on grain angle and review of literature data

The anisotropy of vibrational properties influences the acoustic behaviour of wooden pieces and their dependence on grain angle (GA). As most pieces of wood include some GA, either for technological reasons or due to grain deviations inside trunks, predicting its repercussions would be useful. This paper aims at evaluating the variability in the anisotropy of wood vibrational properties and analysing resulting trends as a function of orientation. GA dependence is described by a model based on transformation formulas applied to complex compliances, and literature data on anisotropic vibrational properties are reviewed. Ranges of variability, as well as representative sets of viscoelastic anisotropic parameters, are defined for mean hardwoods and softwoods and for contrasted wood types. GA-dependence calculations are in close agreement with published experimental results and allow comparing the sensitivity of different woods to GA. Calculated trends in damping coefficient (tanδ) and in specific modulus of elasticity (E′/ρ) allow reconstructing the general tanδ-E′/ρ statistical relationships previously reported. Trends for woods with different mechanical parameters merge into a single curve if anisotropic ratios (both elastic and of damping) are correlated between them, and with axial properties, as is indicated by the collected data. On the other hand, varying damping coefficient independently results in parallel curves, which coincide with observations on chemically modified woods, either “artificially”, or by natural extractives.     

Genetic engineering of terpenoid metabolism attracts bodyguards to Arabidopsis

Herbivore-damaged plants release complex mixtures of volatiles that attract natural enemies of the herbivore. To study the relevance of individual components of these mixtures for predator attraction, we manipulated herbivory-induced volatiles through genetic engineering. Metabolic engineering of terpenoids, which dominate the composition of many induced plant volatile bouquets, holds particular promise. By switching the subcellular localization of the introduced sesquiterpene synthase to the mitochondria, we obtained transgenic Arabidopsis thaliana plants emitting two new isoprenoids. These altered plants attracted carnivorous predatory mites (Phytoseiulus persimilis) that aid the plants' defense mechanisms.