Evaluation of a Western Blot and ELISA for the detection of anti-Trichinella-IgG in pig sera.

Human trichinellosis is a foodborne disease caused by ingestion of infective Trichinella muscle larvae via pork or meat of other food animals which are susceptible to this zoonotic parasite. There are new approaches for a risk-oriented meat inspection for Trichinella in pigs which are accompanied by monitoring programmes on herd level to control freedom from this parasite. For this purpose, testing schemes utilizing serological tests with a high sensitivity and specificity are required. This study aimed at the evaluation of an ELISA and a Western Blot (WB) for the detection of anti-Trichinella-IgG in terms of sensitivity and specificity taking results of artificial digestion as gold standard. For this purpose, 144 field sera from pigs confirmed as Trichinella-free as well as 159 sera from pigs experimentally infected with T. spiralis (123), T. britovi (19) or T. pseudospiralis (17) were examined by ELISA (excretory-secretory antigen) and WB (crude worm extract). Sera from pigs experimentally infected with four other nematode species were included to investigate the cross-reactivity of the antigen used in the WB. For all Trichinella-positive pig sera, band pattern profiles were identified in the WB and results were analysed in relation to ELISA OD% values. Testing of pig sera revealed a sensitivity of 96.8% for the ELISA and 98.1% for the WB whereas the methods showed a specificity of 97.9 and 100%, respectively. WB analysis of Trichinella-positive pig sera revealed five specific band patterns of 43, 47, 61, 66, and 102 kDa of which the 43 kDa protein was identified as the predominant antigen. The frequency of the band pattern profile was irrespective of the dose and the period of infection as well as the Trichinella species investigated. In conclusion, monitoring in swine farms for Trichinella antibodies should be based on screening pig sera by means of ELISA followed by confirmatory testing through WB analysis.

[Contribution to the differentiation of cross-reacting antibodies in brucellosis serology--1. Reactions with various Yersinia serotypes and antibody avidity]. / Beiträge zur Differenzierung von kreuzreagierenden Antikörpern in der Brucellose-Serologie--1. Untersuchungen mit verschiedenen Yersinia Serotypen und zur Antikörper-Avidität.

Brucella and Yersinia enterocolitca O:9 (Y.e.O:9) have antigenic determinants in common causing cross-reactions which interfere strongly in Brucella serology. Hoffmann (1988) observed cross-reactivity between Y.e.O:9, Y.e.O:5, and Y.e.O:6 and used an ELISA for the differentiation between Brucella- and Yersinia antibodies since Y.e.O:5 and Y.e.O:6 produced only low-level cross-reactions with Brucella antigen. The observations of Hoffmann were confirmed and led to the construction of an ELISA with 4 antigens. Sera from natural outbreaks of brucellosis and from artificial infections with Brucella and Y.e.O:9 were properly identifiable by this system. Furthermore, the test material has been used to measure the antibody avidity by a specially designed ELISA. This test produced a further divergence between specific and non-specific reactions.

[Possibilities for standardization of ELISA for detection of Salmonella antibodies in sera and meat juices of pigs]. / Uberlegungen zur Standardisierung des ELISA zur Bestimmung der Salmonellaantikörper in Seren und Fleischsäften des Schweins.

Programmes for controlling salmonella infections in German piggeries are based on the meat-juice-ELISA conducted in various investigation centres by using different test-kits. A usual procedure for harmonization (standardisation) of results is the calculation of the percentage of antibody-concentration from field samples in relation to the extinctions of a set of control-sera with known antibody concentrations. Whether this system is still acceptable in case of using different test-kits seems to be questionable. In principle, difficulties arise by calculating field results from the regression curve of control-sera because the calculated percentages of antibodies do not represent the antibody concentration but, instead, the percentages of the extinctions measured, and secondly, because control-sera presently in use are directed against different salmonella serovars. In regard to the number of laboratories involved and because of a variety of test-kits used it seems to be more adequate to include only one anti-Salmonella Typhimurium standard-serum at a given antibody concentration which is to be tested repeatedly on every test-plate. Simultaneously, further controls should include another anti-Salmonella Typhimurium and one anti-Salmonella Choleraesuis serum which should provide results similar to the Danish system which is regarded as a standard. As well, a negative serum must be included in the test and a minimum difference in extinctions between this negative serum and the standard positive control-serum should be reached to prove the validity of results from the test plate.

[Necessity of double testing of meat juice samples from pigs using ELISA for the determination of Salmonella status in pig farms]. / Uber den Nutzen von Doppelbestimmungen bei Fleischsaftuntersuchungen mittels ELISA für die Beurteilung des Salmonellenstatus von Schweinebeständen.

According to the test protocol of the "meat juice ELISA" for detection of salmonella antibodies in pigs, all meat juice samples and serum controls are to be tested in duplicate. Results from routine investigations of repeatedly double tested meat juice and serum samples have been used to analyze the effect of double testing versus single testing with regard to the reliability of the final result. In case of an individual animal, testing of samples in duplicate increases the reliability of the results significantly, especially, if samples are retested at different occasions. In contrast, such a difference between mono and double testing of samples is not of importance when a group of animals is tested in order to determine the mean antibody rate in a herd. Here, results from double testing practically do not contribute to a higher reliability of the final result. This observation provides the possibility to reduce the costs for investigation programmes drastically.

[Comparison of the results from commercially available Brucella ELISA test kits for the investigation of bovine sera]. / Vergleich der Ergebnisse von kommerziellen Brucellose-ELISA Testkits zur Untersuchung von Rinderserum.

Bovine sera from a farm with bacteriologically confirmed brucellosis were taken for comparative serological studies using conventional methods (slow agglutination test--SAT, complement fixation test--CFT, Rose-Bengal-plate-agglutination-test--RBPT) and 5 different commercially available brucellosis ELISA testkits. These serum samples together with other infectious sera producing low level positive antibody titers in conventional tests did not react uniformly when tested by five different commercial ELISA testkits. The introduction of a standard control serum with a general cut-off resulted in a greater uniformity of ELISA results from 4 of 5 ELISA testkits and a closer approach to results of the CFT which is regarded as the confirmatory test for brucellosis. This control serum, on the other hand, was not suitable for the identification of the sensitivity of the various ELISA test kits. For this purpose, in SAT and CFT weakly positive reacting brucella sera from infected farms is needed.

Iceman in the cold light of day.

The discovery of a Neolithic corpse in an alpine glacier in 1991 attracted widespread attention. What has happened in the eighteen months since then reflects badly on European science.

Smoking behavior among student nurses: a survey.

The study describes the smoking habits of student nurses and determines the correlates of smoking initiation, continuation, and cessation. The sample included 1,163 students attending 10 nursing schools in Buffalo, NY. Data were gathered by means of a self-administered questionnaire. Approximately 30 percent of the students were current smokers, 25 percent were exsmokers, and 45 percent had never smoked. More than half of the smokers (57 percent) expressed the desire to quit, and 81 percent had tried to do so in the past. Major reasons for trying to quit were to protect future health, save money, self-discipline, and pressure from significant others. Most (90 percent) of the students who had tried to quit had attempted to do so on their own and all at once. Knowledge of the health consequences of smoking was not significantly related to smoking behavior. These data suggest the need for health educators to promote personal health practices among their students that are congruent with the goals of the nursing profession of health promotion and disease prevention.

Models for protocellular photophosphorylation.

Several photoreactions for transducing light energy have been analyzed for their relevance as models for protocellular photophosphorylation. Inorganic ions and compounds could have played a role in protocellular photophosphorylation. Organic catalysts may have been the next significant agents used by protocells for photophosphorylation. Membranous photophosphorylation probably became the most recent type of photoenergy transduction to be acquired by protocells; it is still used by modern cells although components of the other types of phosphorylation are found in present day cells. Recorded yields of energy-rich phosphates from the model reactions discussed are small. Arguments are advanced that such yields could have been sufficient to have fueled protocellular metabolism which was probably very slow compared to modern cellular metabolism. Future prospects for research in this area are discussed.