Factors associated with variation in bulk-tank-milk Salmonella Dublin ELISA ODC% in dairy herds

Our objective was to determine factors that contribute to variation in bulk-tank-milk Salmonella Dublin enzyme-linked immunosorbent assays (ELISA) corrected optic-density measurements (ODC%) in dairy herds. We constructed hierarchical mixed models with repeated bulk-tank-milk ELISA ODC% in 31 Danish dairy herds. Four models included different combinations of explanatory factors, and we compared how well these models described the variation in the data. Herd was included as a random effect nested within Salmonella status and barn type.

Detection of Salmonella Dublin or Salmonella Typhimurium by bacteriological culture of individual faecal samples or of slurry samples was associated with higher bulk-tank-milk ELISA ODC%, as was apparent Salmonella prevalence, the mean ELISA ODC% or mean-yield-corrected ELISA ODC% in milk samples collected from all individual cows. However, combinations of risk factors that included number or prevalence of cows with a very high ELISA ODC% provided better models, indicating that the effect of the cow-level explanatory variables on the bulk-tank-milk ELISA ODC% was related to the activity of the infection in the herd. Barn type (loose housing or tie stalls) was not associated with the variation in bulk-tank-milk ELISA ODC% in these models, which might be useful in planning of surveillance programs and intervention strategies.     

Response to soy: T-cell-like reactivity in the intestine of Atlantic salmon, Salmo salar L

T-cell-mediated hypersensitivity could be central in soybean meal (SBM)-induced intestinal changes in salmon. However, tools for immunohistochemical detection of T cells have been lacking in teleosts, including Atlantic salmon. Application of a specific histochemical protocol allowed demonstration of T-cell-like reactivities in formalin-fixed, paraffin-embedded tissues using an antibody reacting to a conserved region of human CD3epsilon (Dako A0452). Characteristic staining was observed in cells of the thymus as well as distal intestine, skin, gills and spleen. These cells were negative for immunoglobulin M (IgM). Intestinal intraepithelial leucocytes were CD3epsilon positive. During the SBM-induced enteropathy, the mixed inflammatory infiltrate in the lamina propria of the distal intestine included many lymphocytes with a T-cell-like reactivity. Real-time polymerase chain reaction revealed significantly increased expression of a complex polypeptide (CD3pp), CD4 and CD8beta (P < 0.05) in the distal intestine of SBM-fed fish compared to fish meal-fed reference fish. Increased reactivity for extracellular IgM in the lamina propria and a positive material between the epithelial cells at the tips of the folds was observed, possibly due to leakage of IgM through an abrogated epithelial barrier. In conclusion, a T-cell-like response appears to be involved in this example of a food-sensitive enteropathy.     

Fatty acid composition of serum lipids in atopic and healthy dogs

Fatty acids are increasingly used in the treatment of canine atopic dermatitis and their beneficial effects are documented in several prospective, controlled studies. Results from recent studies have indicated that atopic dogs have disordered fat metabolism, due to decreased desaturase activity. To further clarify these possible abnormalities, we examined serum fatty acid patterns in dogs with atopic dermatitis and normal controls. Atopic dermatitis was diagnosed according to the diagnostic criteria proposed by Willemse, after elimination of other possible causes of pruritic dermatitis. Both the relative and the absolute amounts of fatty acids in sera were determined by gas chromatography. Differences in the serum fatty acid pattern indicating a reduction in desaturase activity were not detected in atopic dogs when compared with controls.     

Shock metamorphism in lunar samples

Indications of shock metamorphism produced by pressures up to the megabar region have been observed in the fine material and the breccias, but very rarely in the coarser fragments of crystalline rocks. These indications are deformation structures in plagioclase and pyroxene, diaplectic plagioclase glasses, and glasses formed by shock-induced melting of lunar rocks. Two sources of shock waves have been distinguished: primary impact of meteorites and secondary impact of crater ejecta. There are two major chemical types of shock-induced melts. The differences in chemistry may be related to impact sites in mare and highland areas.     

Detection of chlorine-labelled chitosan in Scots pine by energy-dispersive X-ray spectroscopy

The aim of this study was to use energy-dispersive X-ray spectroscopy (EDX) to localize chitosan in the cell wall of chitosan-impregnated Scots pine. It was of interest to investigate the concentration of chitosan in wood to gain further knowledge and understanding of the distribution of chitosan in the wooden matrix. After deacetylation, chitosan was re-acetylated with chloroacetic anhydride to achieve a covalent bonding of chloride to the chitosan polymer. Chloride-labelled chitosan was measured by EDX using a scanning electron microscope and described as chloride intensity. Analysis of free chloride anions was performed by dialysis and inductively coupled plasma atomic emission spectroscopy. There was a significant correlation between the molecular weight of chitosan and the intensity of covalent-bonded chloride to the chitosan polymer. High molecular weight chitosan showed a better interaction with the cell wall structure than low molecular chitosan.     

Tritrichomonas foetus isolates from cats and cattle show minor genetic differences in unrelated loci ITS-2 and EF-1α

The protozoan parasite Tritrichomonas foetus is well known as an important causative agent of infertility and abortion in cattle (bovine trichomonosis). This World Organisation for Animal Health (O.I.E.) notifiable disease is thought to be under control in many countries including Switzerland. In recent studies, however, T. foetus has also been identified as an intestinal parasite that causes chronic large-bowel diarrhoea in cats. Since the feline isolates were considered indistinguishable from bovine isolates, the possibility and risk of parasite transmission from cats to cattle and vice versa has been intensively discussed in current literature. Therefore, we investigated if cat and cattle isolates are genetically distinct from each other or in fact represent identical genotypes. For this purpose, two independent genetic loci were selected that turned out to be well-suited for a PCR sequencing-based genotyping of trichomonad isolates: (i) previously published internal transcribed spacer region 2 (ITS-2) and (ii) a semi-conserved sequence stretch of the elongation factor-1 alpha (EF-1α) gene used for the first time in the present study. Respective comparative analyses revealed that both loci were sufficiently variable to allow unambiguous genetic discrimination between different trichomonad species. Comparison of both genetic loci confirmed that T. suis and T. mobilensis are phylogenetically very close to T. foetus. Moreover, these two genetic markers were suited to define host-specific genotypes of T. foetus. Both loci showed single base differences between cat and cattle isolates but showed full sequence identity within strains from either cat or cattle isolates. Furthermore, an additional PCR with a forward primer designed to specifically amplify the bovine sequence of EF-1α was able to discriminate bovine isolates of T. foetus from feline isolates and also from other trichomonads. The implications these minor genetic differences may have on the biological properties of the distinct isolates remain to be investigated.     

Curiosities in periodic precipitation patterns

Observations have been made of several types of Liesegang patterns that are more complex than the usual concentric ring or parallel bands of precipitate. The structures observed show radial gaps, segmentation, irregular patterns within concentric rings, add the formation of spiral precipitation bands instead of sets of parallel Lisegang bands.