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W Baumgartner

Publications and source records attributed to W Baumgartner.

At least 37 records · Page 2Linked to original sources
PubMed2004

Does the weather influence the occurrence of abomasal displacement in dairy cows?

Aim of the study was to investigate the correlation between the occurrence of abomasal displacement and the weather situations. Data were collected for the years 2000 and 2001 in the area around Lisbon at 26 farms keeping about 6500 Holstein-Friesian milk cows; the analysis of 372 cases of abomasal displacement were included in the study. The weather situation was assessed on daily basis: atmospheric pressure, relative humidity, precipitation, daily insolation, maximum air temperature, minimum air temperature and average wind velocity. These original parameters were modified for the statistical analyses according to atmospheric pressure, water vapour pressure, relative humidity, temperature, temperature range, precipitation, insolation and wind speed. The change of the weather situation was described by the mean absolute deviation (deviation of the meteorological parameters from the running mean over a period of 5 and 10 days) and by a method which was based on the principal component analysis of the entire data set. A weak influence of water vapour pressure, relative humidity, temperature, temperature range, precipitation, and insolation on the occurrence of abomasal displacements was found by linear correlation- and regression analysis. A higher probability for abomasal displacement was verified for low water vapour pressure, high relative humidity, low air temperature, low temperature range, high precipitation and low insolation. No statistically significant relations were found between occurrence of abomasal displacement and either wind velocity or atmospheric pressure. A time series analysis exhibited a higher prevalence for abomasal displacement for periods with a change from sunny, warm and dry days to cool, overcast and humid days. From the present work it can be concluded that the meteorological situation has an influence on the occurrence of abomasal displacement. Therefore, the weather situation should be included among the predisposing causes of the occurrence of abomasal displacements.

Abomasum↗
PubMed2003

Requirement of Rac activity for maintenance of capillary endothelial barrier properties.

Our previous experiments indicated that GTPases, other than RhoA, are important for the maintenance of endothelial barrier integrity in both intact microvessels of rats and mice and cultured mouse myocardial endothelial (MyEnd) cell monolayers. In the present study, we inhibited the endothelial GTPase Rac by Clostridium sordellii lethal toxin (LT) and investigated the relation between the degree of inhibition of Rac by glucosylation and increased endothelial barrier permeability. In rat venular microvessels, LT (200 ng/ml) increased hydraulic conductivity from a control value of 2.5 +/- 0.6 to 100.8 +/- 18.7 x 10-7 cm x s(-1) x cm H2O(-1) after 80 min. In cultured MyEnd cells exposed to LT (200 ng/ml), up to 60% of cellular Rac was glucosylated after 90 min, resulting in depolymerization of F-actin and interruptions of junctional distribution of vascular endothelial cadherin (VE-cadherin) and beta-catenin as well as the formation of intercellular gaps. To understand the mechanism by which inhibition of Rac caused disassembly of adherens junctions, we used laser tweezers to quantify VE-cadherin-mediated adhesion. LT and cytochalasin D, an actin depolymerizing agent, both reduced adhesion of VE-cadherin-coated microbeads to the endothelial cell surface, whereas the inhibitor of Rho kinase Y-27632 did not. Stabilization of actin filaments by jasplakinolide completely blocked the effect of cytochalasin D but not of LT on bead adhesion. We conclude that Rac regulates endothelial barrier properties in vivo and in vitro by 1) modulation of actin filament polymerization and 2) acting directly on the tether between VE-cadherin and the cytoskeleton.

Actins↗
PubMed2003

Clinical and ultrasonographic findings in the mammary gland of sheep.

AIM: To compare clinical and ultrasonographic findings and assess the value of ultrasonography for evaluating the structure and condition of the teat and teat canal of sheep. METHODS: The mammary glands of 30 lactating ewes were examined clinically and using ultrasonography. The distance from the teat tip to the ground was measured and diagnostic images of the body of the gland, gland cistern and teat cistern were obtained using an 8.5 MHz frequency ultrasonic transducer. A California mastitis test (CMT) and bacteriological culture were performed on milk samples collected from each half of each udder. RESULTS: Udder parenchyma and teats were palpably normal in 27/30 (90%) ewes. Milk clots or abnormalities were evident in 4/30 (13%) udders, lesions in the glandular parenchyma and/or teats were evident by palpation in 3/30 (10%), and pathogenic bacteria were cultured from 2/30 (7%). In both of the latter cases, mastitis was diagnosed based on clotted and discoloured appearance of milk and highly positive CMT reactions. Ultrasonographic examination in these udders revealed non-homogenous regions in the glandular tissue and alternating areas of hyperechogenic and hypoechogenic tissue. Overall, highly positive CMT reactions were evident in milk from 14/30 (47%) left halves and 9/30 (30%) right halves (p=0.02). No relationship between teat-to-ground distances and CMT results was evident (p>0.05). Teat canal lengths ranged from 5.7-10.3 mm (mean=8.6; SD=1.3 mm) and the widths from 1.8-3.1 mm (mean=2.3; SD=0.4 mm). Milk sampled from ewes that had long (> or = 9 mm) or wide (> or = 2 mm) teat canals was highly positive to the CMT in 75% and 83% of cases, respectively. CONCLUSIONS: Ultrasonographic measurements of the length and width of the teat canal appeared to correlate with CMT results. The use of ultrasonography in evaluating the health of the udder of small ruminants holds promise for the future.

Journal Article↗
PubMed2002

PrP genotyping of Austrian sheep breeds.

Scrapie, an ovine and caprine transmissible spongiforme encephalopathy, is widely spread among sheep populations in many European countries. As it is known that susceptibility to scrapie is determined genetically, breeding programmes aiming at providing scrapie-resistant flocks have been established. Selection is based on the prion protein (PrP) genotype, which is used to classify animals into risk groups of susceptibility (R1-R5) according to the amino acids encoded by codons at positions 136, 154 and 171, respectively. At position 136 (136V-->136A) alanine and at position 154 (154H-->154R) as well as 171 (171Q-->171R) arginine are the favoured amino acids. Whereas PrP genotyping data are available for many of the European sheep breeds, comparable data for local Austrian sheep breeds are missing. The most known among these are Tyrolean mountain sheep, forest sheep. Tyrolean stone sheep and Carynthian sheep. The genotypes of 112 sheep from these four local breeds were determined. In terms of PrP genetics, Austrian breeds belong to the group of non-valine-breeds, with the exception of the Carynthian sheep, that exhibited a frequency of 136V of 4.2%. The most frequent allele was ARQ with 64.6-71.2% (depending on the breed), followed by ARR (14.8-25.8%). In contrast to the above-mentioned findings, scrapie has never been diagnosed in any of the Austrian sheep breeds. Native Austrian sheep breeds exhibit a very robust constitution, a pronounced adaptation to harsh climates and good reproduction parameters as well as a marked mother instinct. Therefore, these breeds are often used in crossbreeding programmes. Beside the above-mentioned characteristics, our results indicate that the investigated breeds may be effectively used in crossing-out breeding programmes for eliminating valine at position 136 of PrP.

Animal Husbandry↗
PubMed2002

A retrospective study of oesophageal endoscopy in cattle - oesophagoscopy for diagnosis of mucosal disease.

Oesophageal endoscopy in cattle has been rarely reported in the literature. It has, however, been used for many years as an aid to the diagnosis and treatment of illnesses of the upper gastrointestinal tract in small animals and horses. We have assessed the potential value of oesophagoscopy on 120 bovine patients presented at the 2nd Medical Clinic for Ruminants and Swine at the University of Veterinary Medicine, Vienna, over a period of three years. In the course of the study, cattle exhibiting symptoms such as salivation, regurgitation or swelling in the neck region were referred for endoscopic examination. The main indication was to confirm or exclude bovine virus diarrhoea virus infection in calves, in which typical erosions were visible endoscopically on the mucosa of the oesophagus in infected animals. In addition, endoscopy proved to be useful for the diagnosis of diverticula, ruptures and inflammation of the oesophagus. Oesophagoscopy can be considered to be a valuable supplementary aid to clinical examination and, in many cases, can facilitate diagnosis.

Animals↗
PubMed2002

Evaluation of flow injection analysis for determination of urea in sheep's and cow's milk.

Difficulties in measuring the urea content in sheep's milk often occur with spectral photometry due to the high protein and fat concentrations of the milk. In this study an enzymatic flow procedure (QuickChem 8000 Ion Analyser, Lachat Instruments, Milwaukee, USA) to determine the urea content in ovine and bovine milk was evaluated. Urea content is determined by the Berthelot reaction after splitting it enzymatically with urease. The free ammonia diffuses through a teflon membrane into a stream of reagent solutions. Detection takes place by means of a reaction between the ammonium ions with hypochlorite and salicylate producing a green colour, which is measured spectrometrically in a flow meter at 660 nm. By using a diffusion cell chemical deproteinisation of milk is not necessary and capacity is high. The assessed procedure exhibited high accuracy and precision and reached a sample capacity of 55 samples an hour. Storage of the milk samples for several days as well as chemical preservation with bronopol had no effect on the measurement procedure. Due to the complexity of the apparatus and the costs associated therewith, the device proves less suitable for routine diagnostics but rather serves as a reference method for the measurement of urea concentration in milk.

Animals↗
PubMed2001

High-gradient millimeter-wave accelerator on a planar dielectric substrate.

We report the first high-gradient studies of a millimeter-wave accelerator, employing for the first time a planar dielectric accelerator, powered by means of a 0.5-A, 300-MeV, 11.424-GHz drive electron beam, synchronous at the 8th harmonic, 91.392 GHz. Embedded in a ring-resonator circuit within the electron beam line vacuum, this structure was operated at 20 MeV/m, with a circulating power of 200 kW, for 2 x 10(5) pulses, with no sign of breakdown, dielectric charging, or other deleterious high-gradient phenomena. We also present the first measurement of the quadrupolar content of an accelerating mode.

Journal Article↗
PubMed2001

Ultrasonography of the teat canal in cows and sheep.

When the isolated teat of a cow was examined with an 8.5 MHz linear array transducer in a vertical plane, the teat canal appeared as a thin, white line, bordered on each side by parallel, thick, grey-black bands. In a horizontal plane a comparable image was obtained. In a sheep, images of comparable quality were obtained with a 12 MHz transducer. Histological studies of the tissues whose removal led to the disappearance of this characteristic ultrasonographic appearance showed that it was associated with the stratified keratinised squamous epithelium with distinct papillae. The content of keratin in the stratum corneum was apparently responsible for the bright zone; the stratum lucidum was not visible, and the surrounding dark, less echoic area was associated with the stratum granulosum. Doppler echography in live animals confirmed this designation. The outer layers of the teat wall were more echogenic.

Animals↗
PubMed2001

Total and organic mercury in the Black Sea harbour porpoise Phocoena phocoena relicta.

This paper reports on mercury (Hg) concentrations in different tissues (liver, muscle, kidney, blubber and brain) of harbour porpoises Phocoena phocoena found dead in the Black Sea between 1997 and 1999, mainly bycaught in fishing nets (n = 79). Total Hg and organic Hg (MeHg) were determined. The main factor affecting Hg accumulation was, as expected, age, with MeHg concentration increasing with age. Accumulation of high concentrations of inorganic Hg in the liver was probably due to a slow demethylation process implying the formation of tiemannite (HgSe). In older adults, liver concentrations reached 35 microg g(-1) dry weight ('ppm') total Hg and 3 microg g(-1) dw MeHg. A geographical comparison with existing data from other regions showed a generally low Hg contamination of Black Sea porpoises, one order of magnitude lower than, e.g. in the North Sea.

Adipose Tissue↗
PubMed2001

[Comparison of iodinated and barium-containing contrast media of different viscosity in the detection of pharyngeal perforation].

PURPOSE: In contrast to esophageal perforations, the more radiopaque barium-suspensions are not as important as iodinated aqueous contrast agents for the detection of pharyngeal perforations. This study was performed to find out whether the highly different viscosities (of iodinated and barium-containing contrast agents with comparable radiopacities) are a reason for this. METHODS: Viscosity, subjective difference in contrast, and CT-density of an iodinated aqueous (Telebrix) and a 50 wt/vol% barium-containing contrast agent (Micropaque) were determined. Moreover, to exclude postoperative perforation, 104 patients were prospectively examined by pharyngography using both contrast media. Pharyngographies of patients with perforation were later compared by two independent readers. All patients with perforation were followed up clinically to exclude complications due to barium administration. RESULTS: In-vitro comparison showed comparable radiopacity but the 50 wt/vol% barium-suspension was much more viscous than the iodinated contrast agent. During pharyngography, totally, 14 perforations were clearly delineated with the iodinated aqueous contrast agent. However, two of them were not detected with the barium-suspension. All the other perforations presented equally. CONCLUSIONS: Given a sufficient radiopacity, a low viscosity appears to be essential for a contrast agent to detect especially pharyngeal perforations. Thus, we recommend the sole use of an iodinated contrast agent (at suspicion of aspiration as isoosmolar variant) for this purpose.

Adult↗
PubMed2001

Perimodiolar electrodes in cochlear implant surgery.

Perimodiolar-positioned cochlear implant electrodes have been developed in order to bring the electrode contacts as close as possible to the spiral ganglion cells, which are the target of electrostimulation. This results in lower electrical thresholds, higher dynamic ranges and less channel interaction when compared with normal implant electrodes which are usually located peripherally within the scala tympani. In this study we evaluated 4 different types of perimodiolar electrode: the Clarion Preformed electrode, the Clarion Preformed electrode with positioner, the Nucleus Contour electrode and the Med-El Perimodiolar Combi 40 electrode. These devices require different approaches to achieve a perimodiolar electrode position. The electrodes were inserted in fresh human temporal bones. After processing these bones with the electrodes in situ by employing a sawing, grinding and polishing technique, the inner ear structures as well as the electrode positions could be evaluated in detail. All electrode types studied had a more or less perimodiolar position; however, each type produced a certain amount of trauma to cochlear structures which is discussed in relation to mechanical properties. Further human temporal bone studies with improved perimodiolar cochlear implant electrodes are necessary in order to find an optimized type of electrode.

Cochlea↗
PubMed2001

In vitro efficacy of chemotherapeutics as determined by 50% inhibitory concentrations in cell cultures of mammary gland tumors obtained from dogs.

OBJECTIVE: To determine the 50% inhibitory concentration (IC-50) of carboplatin, cisplatin, and doxorubicin in cell cultures of mammary gland tumors obtained from dogs and to assess whether in vitro efficacy was within the range of clinically relevant concentrations, SAMPLE POPULATION: 30 mammary gland tumors excised from dogs. PROCEDURE: Cell cultures were established from the 30 tumors. Cultures then were treated with carboplatin, cisplatin, or doxorubicin. Growth inhibition of cultures was assessed via DNA measurement 24, 48, and 72 hours after treatment. The IC-50 values were calculated by use of linear interpolation. RESULTS: Cultures varied in their pattern of susceptibility. Doxorubicin induced significantly lower IC-50 values than the platinum derivatives. Cisplatin and carboplatin had comparable effects. The IC-50 values for carboplatin and doxorubicin were in the range of clinically relevant concentrations, but only part of the cisplatin cultures had IC-50 values within clinically relevant concentrations. We did not detect differences in the in vitro susceptibility among subtypes of tumors (ie, adenocarcinoma, solid carcinoma, malignant mixed tumor). CONCLUSION AND CLINICAL RELEVANCE: The IC-50 values determined in this study allowed assessment of in vitro drug efficacy of chemotherapeutics in cultures of mammary gland tumors obtained from dogs. Variations in susceptibility were evident and emphasize the importance of assessing susceptibility and resistance patterns for each tumor. Prospective studies to assess direct correlations between in vitro and in vivo efficacy must be performed to determine the clinical predictive value of this in vitro chemosensitivity assay for treatment of dogs with mammary gland tumors.

Adenocarcinoma↗
PubMed2001

Radical cavities and cochlear implantation.

Profoundly deaf patients with chronic suppurative otitis media have been contraindicated for cochlear implantation in the past. Complications such as infection of the radical cavity, fat necrosis, skin flap problems, change in electrode position and cholesteatoma have occurred in subjects with radical cavities. The aim is to create a dry, self-cleansing, infection-free cavity. This is essential in patients about to receive a cochlear implant, as infection may be introduced into the cochlea at the implantation site and destroy any remaining neural elements. The aim of this paper was to show that it is possible to obliterate the radical cavity and perform cochlear implantation using a one-step surgical technique. Eight patients suffering from long-term bilateral chronic middle ear diseases with chronic sepsis leading to severe hearing impairment underwent cochlear implant surgery. No major complications were observed in these subjects.

Adult↗
PubMed2000

Mycobacterium avium subsp. paratuberculosis infection in cattle in Austria, diagnosis with culture, PCR and ELISA.

Serum samples from healthy, infected (n=11) and diseased (n=2) cattle as well as positive (n=17) and negative (n=41) reference sera were tested for antibodies to Mycobacterium avium subsp. paratuberculosis with two ELISA-methods (A-ELISA, Allied Monitors, Fayette, USA; H-ELISA, Institute of Microbiology and Animal Diseases, Veterinary University Hannover). Fecal samples of these animals were examined by PCR and culture. Also field serum samples found to be positive (n=664) or inconclusive (n=1589) by A-ELISA during a survey done on 11028 cattle of 2757 farms at different districts in Austria were retested with H-ELISA (Gasteiner et al., 1999). In both ELISA-methods total agreement between antibody detection and shedding of M. avium subsp. paratuberculosis (PCR, culture) in cases of diseased animals during the testing period was found. In subclinically infected animals H-ELISA showed a better correlation with the results of PCR and fecal culture. Reference serum samples of culturally negative cattle were negative in 98% by H-ELISA and in 82% by A-ELISA, and those of positive animals were positive in 59% by H-ELISA and in 82% by A-ELISA. The 664 A-ELISA positive field serum samples were positive in 20.5%, inconclusive in 32.5% and negative in 47% by H-ELISA. A-ELISA inconclusive sera gave positive reactions by H-ELISA in 5.2%, negative in 74.8% and inconclusive results in 20%. The highest prevalence of antibodies (7.9% by A- and 2.2% by H-ELISA) against M. avium subsp. paratuberculosis were found in cattle at the age of six and seven years. Seropositive animals were found at all tested ages. The A-ELISA gave two to three times more positive reactors than the H-ELISA. Also both tests showed the highest prevalence of reagents among Holstein Friesian (6.2% by A-ELISA, 2.5% by H-ELISA) followed by other cattle breeds. Seropositive cattle were observed in all districts of Austria in 3. 3-7.1% and in 0.5-1.8% of herds according to A- and H-ELISA, respectively.

Animals↗
PubMed2000

Cadherin interaction probed by atomic force microscopy.

Single molecule atomic force microscopy was used to characterize structure, binding strength (unbinding force), and binding kinetics of a classical cadherin, vascular endothelial (VE)-cadherin, secreted by transfected Chinese hamster ovary cells as cis-dimerized full-length external domain fused to Fc-portion of human IgG. In physiological buffer, the external domain of VE-cadherin dimers is a approximately 20-nm-long rod-shaped molecule that collapses and dissociates into monomers (V-shaped structures) in the absence of Ca(2+). Trans-interaction of dimers is a low-affinity reaction (K(D) = 10(-3)-10(-5) M, k(off) = 1.8 s(-1), k(on) = 10(3)-10(5) M(-1) x s(-1)) with relatively low unbinding force (35-55 pN at retrace velocities of 200-4,000 nm x s(-1)). Higher order unbinding forces, that increase with interaction time, indicate association of cadherins into complexes with cumulative binding strength. These observations favor a model by which the inherently weak unit binding strength and affinity of cadherin trans-interaction requires clustering and cytoskeletal immobilization for amplification. Binding is regulated by low-affinity Ca(2+) binding sites (K(D) = 1.15 mM) with high cooperativity (Hill coefficient of 5.04). Local changes of free extracellular Ca(2+) in the narrow intercellular space may be of physiological importance to facilitate rapid remodeling of intercellular adhesion and communication.

Animals↗
PubMed2000

Steady-state gel electrophoresis of long polymer molecules: a theoretical study.

The velocity of long polymer molecules in a gel and the liquid flow profile in the vicinity of a molecule's surface were studied theoretically by combining the Navier-Stokes equation with the Poisson-Boltzmann equation. The electrophoretic mobility has been calculated in dependence of the ionic strength of the electrolyte solution, its viscosity, the gels' volume friction coefficient, the surface charge and the radius of the polymer molecule. The results are presented in a nondimensional form and depend on two dimensionless parameters only. The first parameter is the radius of the polymer molecule in units of the Debye length. The second is a parameter comprising the electrolyte's viscosity and the gel density. Thus, by similarity theory, the results apply to any given experimental arrangement.

Biophysics↗
PubMed2000

Data analysis of interaction forces measured with the atomic force microscope

The force-distance cycle mode of the atomic force microscope (AFM) allows for detection of interaction forces between the AFM-tip and a substrate (probe). This can either be a direct tip-sample interaction or an interaction between molecules coupled to the tip and probe, respectively. The interaction forces are typically in the range of a few pN to some hundred pN. In this article we describe algorithms for the analysis of force-distance cycles, to quantify interaction forces between tip and probe. Both, the direct tip-probe interaction as well as the interaction between specifically bound molecules are analyzed. The molecules bound to tip and probe have to be either long and flexible or have to be bound via a flexible cross linker. The algorithms are exemplified on direct tip-probe interactions and on unbinding events of cadherins which are bound via PEG-spacers to the AFM-tip and to the probe.

Journal Article↗