Short communication: Examination of milk filters by real-time PCR as a herd-level indicator of the presence of Mycobacterium avium subspecies paratuberculosis in dairy herds

The aim of this study was to assess the suitability of real-time quantitative PCR (qPCR) for the detection of Mycobacterium avium ssp. paratuberculosis (MAP) in milk filters as a herd level indicator of paratuberculosis infection. Seventy-nine samples from textile or metal milk filters from 15 herds with defined MAP prevalence (infection status = noninfected, 0-5%, 5-10%, or >10% of animals with clinically confirmed paratuberculosis) were analyzed. The MAP DNA was isolated by a modified commercially available protocol for feces, and detection and quantification of the pathogen was performed by the IS900 qPCR. Mycobacterium avium ssp. paratuberculosis DNA was detected in 63 (79.7%) samples. Determination of MAP infection established by fecal and tissue culture was correctly confirmed by the analysis of milk filters on 11 of 12 infected farms; MAP was not detected in filters from 3 farms where paratuberculosis was never diagnosed. Statistical analysis of the data supports the evidence that milk filters can be used as a template for the direct detection of MAP on the herd level. The probability of successful MAP detection in milk filters in a herd with MAP-infected cows is at least 94.3%. Absolute numbers of MAP detected on the milk filter can be used for a rough estimation of paratuberculosis prevalence >10% in the herd. Analysis of milk filters for the presence of MAP can be a useful tool for the detection of paratuberculosis on the herd level before any individual control strategies.     

Polyphenolic Composition and Antioxidant Activities of Grape Seed Extract

Grape seed extracts (GSEs,) obtained from Italian and Rhine Rieslings, were examined for polyphenolic composition and antioxidant activities using HPLC and ESR spectrometry. The seed extraction was carried out with ethyl acetate and ethanol. The contents of polyphenols, flavan-3-ols and antioxidant activities were found to be higher in ethyl acetate than in ethanolic extracts. IC₅₀ values were 0.1045 mg/mL and 0.0599 mg/mL for the stable DPPH radical in ethanolic and ethyl acetate extracts, respectively. The values for the short-lived OH radical were 0.1989 mg/mL and 0.0362 mg/mL, in the given order. The significant correlations between the antioxidant activities of GSEs and polyphenols were established (P < 0.05). Owing to their antioxidant activities, the cultivars could be used as a source to produce a GSE.     

Malting Barley Grain Non‐specific Lipid‐Transfer Protein (ns‐LTP): Importance for Grain Protection

A basic protein (pI < 9) was isolated to homogeneity from a domestic cultivar of malting barley grain (Hordeum vulgare). In its unreduced form it exists as a dimer of a 9 kDa protomer with four disulphide bridges. These characteristics together with protein sequence data revealed that the isolated protein belongs to the class of ns‐LTP. The antifungal potency of malting barley grain ns‐LTP was examined on Saccharomyces cerevisiae, Candida albicans and the plant pathogen Fusarium solani growth in vitro. It was found that ns‐LTP inhibits Saccharomyces and Fusarium growth; the concentration required for 50% inhibition after 24 h of incubation (IC₅₀) was 100 and 80 μg/mL, respectively. On the basis of these results, the importance of ns‐LTP for barley grain protection from fungal diseases has been discussed.     

Cardiac tissue engineering: effects of bioreactor flow environment on tissue constructs

The limited ability of cardiac muscle to regenerate after injury and the small number of organs available for transplantation motivate studies aimed at curative treatment options. Tissue engineering based on the integrated use of cells on biomaterial scaffolds in bioreactors may offer cardiac grafts suitable for surgical attachment to the myocardium or for basic research. In one of the current approaches, neonatal rat cardiomyocytes are combined with collagen sponges, gels or polyglycolic acid scaffolds (PGA). Cultivations performed in dishes, static or mixed flasks or rotating bioreactors yield constructs with a thin (100–200 µm) peripheral layer of tissue expressing markers of cardiac differentiation and able to propagate electrical signals. The non‐uniform cell distribution is a result of oxygen diffusional limitations within the constructs. Cultivations with perfusion of culture medium through the construct enhance the convective‐diffusive oxygen supply and yield 1–2 mm thick constructs with physiologically high and spatially uniform distribution of viable cells expressing cardiac markers. We review here a series of studies we conducted using cells seeded on three‐dimensional scaffolds and cultured in several different bioreactors, to demonstrate that the bioreactor flow environment can have substantial effects on structural and functional properties of cardiac constructs. Copyright © 2006 Society of Chemical Industry     

What guides a search for food that has disappeared? Experiments on cotton-top tamarins (Saguinus oedipus).

When food is launched down a vertically positioned S-shaped opaque tube, cotton-top tamarins (Saguinus oedipus) search for the food in the position directly beneath the release point, even though over several trials it never appears in this position (B. M. Hood et al., 1999). Experiment 1 showed that when the trajectory of the food shifts from the vertical to the horizontal plane, tamarins no longer show systematic perseverative errors and, in general, perform better on this invisible displacement task. Experiment 2 showed that tamarins with experience on the horizontal task show less of a bias when tested on the vertical task but nonetheless fail overall to solve this invisible displacement problem; their performance is substantially worse than it was on the horizontal task. Experiment 3 revealed that when the vertically positioned tube is replaced by an occluded ramp, tamarins consistently search in the compartment below the release point, even though most of the tamarins had experience in Experiments 1 and 2. Overall, results indicate that tamarins have a significant gravity bias when searching for food that has disappeared along the vertical plane but also have more general problems finding food that has moved out of sight. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Generalized Chebyshev Filters for the Design of IIR Filters and Filter Banks

This paper introduces the generalized IIR Chebyshev filters. The proposed filters are obtained by applying bilinear transformation to the corresponding analog filters. The novelty of the method is the introduction of a new rational Chebyshev function, which includes Chebyshev Type I and Chebyshev Type II IIR filters as special cases. The application of the proposed digital filters to design perfect reconstruction two-channel filter banks is described. The proposed filters can be applied in orthogonal discrete wavelet transform.     

A simplified model for the correlation of vapour-liquid equilibrium in the CO2-NH3-H2O system

A new simplified VLE model of the CO₂-NH₃-H₂O system under conditions of the distillation and absorption steps of the recycle urea process is developed. For the gaseous phase the virial state equation is adopted and the component activity coefficients are approximated by a simple linear expression. The resulting equations for the equilibrium constants of the physical and chemical equilibria are fitted to experimental values (in the literature) within the temperature range of 307 to 414 K and within the pressure range of 2 to 40 bar. Tests of the model on the experimental data are presented as well as the comparisons with other published simplified VLE models of the system.