Comparative examination and validation of ELISA test systems for Salmonella typhimurium diagnosis of slaughtering pigs

The most frequently isolated Salmonella serotype from pork in Germany is S. typhimurium, especially phagetype DT 104. The monitoring programs on Salmonella in swine are based on enzyme-linked immunoadsorbent assay (ELISA) detecting antibodies in serum or meat juice. These serological results are used to classify swine herds in three categories to assess the hygienic status of farm regarding Salmonella infection in pigs. The object of this study was the comparative evaluation of four indirect Salmonella ELISA tests approved in Germany to detect Salmonella typhimurium infection of swine. Three tests (A–C) are based on LPS-antigen and directed against specific IgG-antibodies. The fourth test (D) bases on a whole-cell-lysate antigen and discriminates between Salmonella specific IgA-, IgM- and IgG-antibodies. In a longitudinal study sixteen 6 weeks old weaning pigs were orally infected with S. typhimurium DT 104. During an observation period of 138d clinical and bacteriological parameters were monitored and serum samples obtained at regular intervals as well as meat juice samples taken at slaughter were examined by the respective ELISA systems. Study results reveal that all tested ELISA systems are able to detect S. typhimurium infection in pigs in both sample matrices, blood serum and meat juice whereas test D showed the highest sensitivity to detect Salmonella antibodies in pigs. The sensitivity to detect Salmonella antibodies varied between tests A and C according to the used cut-off (test specific cut-off vs. recommended surveillance cut-off) resulting in a change of seroprevalence and hence may influence the Salmonella status of the farm.     

Experimentelle Identifikation und rechnergestützter Regler-Entwurf bei technischen Prozessen

Experimental identification and computer-aided control design in technical processes . The transient behaviour of complex processes, such as frequently occur in process engineering, is often known only inadequately, since theoretical (physical) model formation is extremely difficult owing to insufficient knowledge of internal processes. If satisfactory quality of control is to be achieved, then a viable approach is experimental model construction (identification) on the basis of a mathematical process model. Modern computer-aided identification procedures and computer-aided control design procedures based thereon or self-adjusting controls give particularly good results. Furthermore, the design time required is greatly reduced, meaning that computer use can also contribute to considerable saving of costs.     

The control of shivering and non-shivering thermogenesis in the rat

1. The effect of intraperitoneal administration of propranolol (4, 8 and 12 mg/kg) on colonic temperature was studied in twelve rats during exposure to ambient temperatures of 30, 15 and 5 degrees C. 2. At 30 degrees C, propranolol had no effect on colonic temperature; at 15 and 5 degrees C, however, 4 mg propanolol/kg induced a fall in colonic temperature of about 0-8 degrees C, whereas 8 and 12 mg propanolol/kg induced a fall of about 1-5-2-0 degrees C. 3. Assuming that the temperature regulations system of the rat has a proportional controller and that the effect of propranolol was due to the blockade of non-shivering thermogenesis, the results are interpreted as showing that shivering is activated only when heat loss exceeds the capacity for non-shivering thermogenesis.     

Spark-induced fracture of optical fibres

Sparks can be used to induce the fracture of optical fibres under controlled conditions to prepare ends for low-loss joints. The material and geometry of the electrodes of the spark gap are found to have a pronounced effect on the efficiency of the technique.     

Zur Fleischartbestimmung aus Fettbestandteilen und Fettbegleitstoffen

Determination of the Nature of Meat from the Fat-Components and Substances Accompanying Fats Foodstuffs in a ready-to-serve state are more and more preferred by the consumer. In order to prevent adulteration as far as possible, investigations within the scope of general control must include the examination of the nature of meat as well. Taking the examples of beef, pork and meats of horse, cangaroo, hare, tiger and elefant, it is shown, that on the basis of polyunsaturated fatty acids (linoleic, linolenic, and arachidonic) along with cholesterol of the meat fat, a reasonably good assessment of the nature of the meat can be performed.     

Influence of anthraquinones on the formation of urinary calculi in experimental animals (author''s transl)

A method is presented for the quantitation of urinary and CSF protein. In the presence of 0.10 N NaOH the peptide bonds of the protein remove and bind copper from an ion exchange resin. The resulting copper-protein complex is separated from low molecular weight substances by gel filtration and the copper in the eluted complex is determined colorimetrically with diethyldithiocarbamic acid. The method requires only 100mul of sample, has biuret specificity and uses a single prepacked column. The limit of sensitivity is 2 mg of protein per deciliter.     

Induction of protective immunity by aerosol or oral application of candidate vaccines in a dose-controlled pig aerosol infection model

In order to outline basic concepts for the design of a bacterial aerosol infection model, the development of a pig model with Actinobacillus pleuropneumoniae is described. First, reproducibility of aerosol parameters should be maintained by optimizing generating and sampling conditions. Survival rates of the chosen strain must be predictable. Secondly, inhalation conditions for the recipients have to be standardized to enable the determination of deposition sites and the dose administered. Subsequently, dose-response relationship should be evaluated to find a suitable challenge dose. Furthermore, it seems necessary to establish methods to obtain local specimens for determination of the local immune responses. The present study demonstrates that after aerosol challenge pigs were completely protected after inhalation and partially protected after oral application of A. pleuropneumoniae vaccines and describes techniques to administer bacteria in a dose-dependent, viable way. Using the infection model several stages of the disease from acute pleuropneumonia to chronic infection can be induced for research purposes.     

Fast determination of N-phenylpropenoyl-l-amino acids (NPA) in cocoa samples from different origins by ultra-performance liquid chromatography and capillary electrophoresis

N-Phenylpropenoyl-l-amino acids (NPA) are among the key contributors to the astringent taste of cocoa. Two fast and easy to use methods (CE and UPLC?, both with PDA detection) for routine determination of the main NPA were developed. Crude extracts of defatted seeds were analysed by means of capillary electrophoresis leading to separation in less than 30min. Separation by means of UPLC? was much faster (<4min), however, a preceding SPE clean-up abolishes this benefit in time saving. Thus, the CE- and UPLC?-methods are comparable concerning time consumption and provide similar results. Analysis of 18 samples of raw and roasted beans from the global cocoa market originated from 12 countries and 4 continents showed a great variability of NPA content (0.7-3.6mg/g) and qualitative composition of different NPA. Anyway, all samples from cocoa beans showed a comparable NPA pattern. N-[3',4'-dihydroxy-(E)-cinnamoyl]-l-aspartic acid was the most abundant metabolite, followed by N-[4'-hydroxy-(E)-cinnamoyl]-l-aspartic acid and N-[3',4'-dihydroxy-(E)-cinnamoyl]-3-hydroxy-l-tyrosine (clovamide). The analysis of other plant organs (flowers, leaves, fruits) revealed an entirely different situation. NPA were detected in all parts of the fruit, with husk and pulp being clearly dominated by clovamide. In flowers and leaves no NPA were detected; 2-O-caffeoyltartaric acid was shown to be the major caffeic acid metabolite in leaves.