A qualitative risk assessment approach for Swiss dairy products: opportunities and limitations.

Switzerland implemented a risk-based monitoring of Swiss dairy products in 2002 based on a risk assessment (RA) that considered the probability of exceeding a microbiological limit value set by law. A new RA was launched in 2007 to review and further develop the previous assessment, and to make recommendations for future risk-based monitoring according to current risks. The resulting qualitative RA was designed to ascertain the risk to human health from the consumption of Swiss dairy products. The products and microbial hazards to be considered in the RA were determined based on a risk profile. The hazards included Campylobacter spp., Listeria monocytogenes, Salmonella spp., Shiga toxin-producing Escherichia coli, coagulase-positive staphylococci and Staphylococcus aureus enterotoxin. The release assessment considered the prevalence of the hazards in bulk milk samples, the influence of the process parameters on the microorganisms, and the influence of the type of dairy. The exposure assessment was linked to the production volume. An overall probability was estimated combining the probabilities of release and exposure for each combination of hazard, dairy product and type of dairy. This overall probability represents the likelihood of a product from a certain type of dairy exceeding the microbiological limit value and being passed on to the consumer. The consequences could not be fully assessed due to lack of detailed information on the number of disease cases caused by the consumption of dairy products. The results were expressed as a ranking of overall probabilities. Finally, recommendations for the design of the risk-based monitoring programme and for filling the identified data gaps were given. The aims of this work were (i) to present the qualitative RA approach for Swiss dairy products, which could be adapted to other settings and (ii) to discuss the opportunities and limitations of the qualitative method.

[Diagnosis of anterior knee instability. Comparison between the Lachman test, the KT-1,000 arthrometer and the ultrasound Lachman test]. / Diagnostik der vorderen Knieinstabilität. Vergleich zwischen dem Lachman-Test, KT-1000-Arthrometer und sonographischem Lachman-Test.

We reviewed 45 patients on average 14.7 years after surgery for rupture of the anterior cruciate ligament. The aim of the study was to compare the reliability of the Lachman test to evaluation of knee laxity with the KT 1000 arthrometer and the ultrasound-assisted Lachman test. Forty-five knees were examined with the Lachman test: 12 knees showed no sign of instability; 20 had a + positive Lachman test with a hard end point; 6 with a + positive test had no end point and were rated as unstable; a +2 Lachman test was found in 7 knees. With the KT 1000 Arthrometer 44 knees were examined: 30 knees were graded as stable according to the criteria of Daniel; 14 knees were unstable. We used the ultrasound-guided Lachman test in 44 knees. Taking only the side-to-side difference into account, 37 knees were stable and 7 unstable. According to Gruber, a single translation greater than 4 mm is also a sign of instability. Therefore, 12 knees were unstable, although 6 of these knees were rated as stable, taking the side-to-side difference into account. Comparing the two instrument measurements, all knees with ultrasound-rated instability on the basis of side-to-side measurements were also rated as unstable with the KT 1000 arthrometer. Only half of the knees rated as unstable because of a single translation greater than 4 mm with the ultrasound technique were rated as unstable with the KT 1000 arthrometer. Our results show that the accuracy of the Lachman test is as good as the instrument evaluation if the end point is taken into consideration. A positive Lachman test indicating anterior knee laxity is one where the soft end point is as described by Torg et al. Both instrument measurements are accurate in indicating anterior knee laxity, but only if they are used by an experienced examiner. Using the side-to-side measurements, the sensitivity of the KT 1000 arthrometer is higher. If only single translations greater than 4 mm without a significant side-to-side difference with the ultrasound technique are interpreted as anterior knee instability, then some knees will be rated as unstable, although both the clinical and KT 1000 arthrometer examinations prove them to be stable. We believe that only a side-to-side difference with the instrument techniques should be interpreted as knee laxity. Borderline positive measurements should only be used together with the clinical findings. Both instrument measurements can help to improve the quality of the clinical examination if the examiners are inexperienced. If instrument measurements are required, we believe that the ultrasound technique is easy and cheap to perform. Nevertheless, we believe that instrument measurements of anterior knee laxity are not necessary if a thorough clinical examination is performed, taking the end point of the Lachman test into consideration.

Synthesis of EF-Tu and distribution of its mRNA between stroma and thylakoids during the cell cycle of Chlamydomonas reinhardii.

In Chlamydomonas reinhardii the elongation factor EF-Tu is encoded in the chloroplast DNA. We identified EF-Tu in the electrophoretic product pattern of chloroplast-made proteins and showed that this protein is only synthesized in the first half of the light period in synchronized cells. The newly synthesized EF-Tu contributed little to the almost invariable content of EF-Tu in chloroplasts during the light period of the cell cycle. However, increasing cell volume and the lack of EF-Tu synthesis in the second half of the light period led to a decrease in the concentration of EF-Tu in chloroplasts. At different times in the vegetative cell cycle, the RNA was extracted from whole chloroplasts and from free and thylakoid-bound chloroplast polysomes. The content of mRNA of EF-Tu in chloroplasts and the distribution between stroma and thylakoids were determined. During the light period, the content of the mRNA for EF-Tu varied in parallel to the rate of EF-Tu synthesis. However, in the dark, some mRNA was present even in the absence of EF-Tu synthesis. Most of the mRNA was bound to thylakoids during the whole cell cycle. This suggests that synthesis of EF-Tu is associated with thylakoid membranes.

Synthesis of two proteins in chloroplasts and mRNA distribution between thylakoids and stroma during the cell cycle of Chlamydomonas reinhardii.

Chloroplasts contain thylakoid-bound and free ribosomes and polysomes. Whether binding of polysomes plays an immediate role in the regulation of chloroplast protein synthesis is not yet clear. In the present work, variations of protein synthesis and of mRNA content were measured not in greening, but in fully differentiated chloroplasts during the cell cycle of synchronized cultures of Chlamydomonas reinhardii. At different times of the vegetative cell cycle, the RNA was extracted from free and thylakoid-bound chloroplast polysomes and the partition of mRNAs between stroma and thylakoids was measured for two proteins, i.e. the 32-kDa herbicide-binding membrane protein and the soluble large subunit of the ribulose-1,5-bisphosphate carboxylase. At the same time the rates of synthesis of these two proteins were also determined. At 2 h after the onset of light, the content of both mRNAs in chloroplasts had doubled and 75-90% of each of these mRNAs were found to be bound to the thylakoids. The rate of protein synthesis, however, increased 10-fold, but reached its maximum only after about 6 h in the light. The differences in the time courses, in the stimulation of the rate of protein synthesis, and in the mRNA-binding to thylakoids point to a translational regulation of protein synthesis. Furthermore, since a very high proportion of polysomes were bound to thylakoids, containing mRNA for both a membrane and a soluble protein, this light-induced binding of polysomes to thylakoids seems to be an essential, but not the only, prerequisite for protein synthesis in chloroplasts.