Design and synthesis of a multivalent catch-and-release assay to measure circulating FXIa.

BACKGROUND: Decreased blood coagulation factor (F)XIa levels have been shown to protect from thrombosis without bleeding side effects, but less is known on effects of increased FXIa levels. Studies are hampered by lack of a reliable and robust method for FXIa quantification in blood. We aim to develop a new assay employing a unique multivalent catch-and-release system. The system selectively isolates and protects homodimeric FXIa from plasma and releases free FXIa allowing subsequent quantification. METHODS: A dynamic multivalent construct was synthesized by complexing four identical FXIa inhibitors from the snake Bungarus Fasxiatus to avidin through desthiobiotin-PEG-linkers, allowing dissociation of FXIa by excess biotin. PEG-linker lengths were optimised for FXIa inhibitory activity and analysed by Michaelis-Menten kinetics. Finally, the catch-and-release assay was validated in buffer and plasma model systems. RESULTS: Monovalent and multivalent inhibitor constructs were successfully obtained by total chemical synthesis. Multimerisation of Fasxiator resulted in a 30-fold increase in affinity for FXIa from 1.6 nM to 0.05 nM. With use of this system, FXIa could be quantified down to a concentration of 7 pM in buffer and 20 pM in plasma. CONCLUSION: In this proof-of-concept study, we have shown that the catch-and-release approach is a promising technique to quantify FXIa in plasma or buffer. By binding FXIa to the multivalent construct directly after blood drawing, FXIa is hypothesized to be inaccessible for serpin inhibition or auto inactivation. This results in a close reflection of actual circulating FXIa levels at the moment of blood drawing.

Lung lesions increase the risk of reduced meat quality of slaughter pigs.

Lung lesions of about 1000 pigs (nN) were scored in the slaughter line. Carcass weight, back fat thickness, loin muscle depth, pHi and PQMi were measured on 460 pigs. Twenty-four hours after slaughter pHu, PQMu, brightness, redness, yellowness and drip loss were measured on 59 carcasses. A score for lung lesions was assessed at batch level, based on observations of all pigs in that batch, i.e. about 130. Pigs systematically selected from batches scoring more than 25% lung lesions had a lower pH of LD muscle (P≤0.0003) and a six fold higher risk for P(ale)S(oft)E(xudative) traits (P≤0.050) compared to batches scoring less than 5%.

Automation in haemostasis.

Automatia, an ancient Greece goddess of luck who makes things happen by themselves and on her own will without human engagement, is present in our daily life in the medical laboratory. Automation has been introduced and perfected by clinical chemistry and since then expanded into other fields such as haematology, immunology, molecular biology and also coagulation testing. The initial small and relatively simple standalone instruments have been replaced by more complex systems that allow for multitasking. Integration of automated coagulation testing into total laboratory automation has become possible in the most recent years. Automation has many strengths and opportunities if weaknesses and threats are respected. On the positive side, standardization, reduction of errors, reduction of cost and increase of throughput are clearly beneficial. Dependence on manufacturers, high initiation cost and somewhat expensive maintenance are less favourable factors. The modern lab and especially the todays lab technicians and academic personnel in the laboratory do not add value for the doctor and his patients by spending lots of time behind the machines. In the future the lab needs to contribute at the bedside suggesting laboratory testing and providing support and interpretation of the obtained results. The human factor will continue to play an important role in testing in haemostasis yet under different circumstances.

Increased level of antibodies cross-reacting with Ves v 5 and CRISP-2 in MAR-positive patients.

BACKGROUND: Anti-sperm antibodies (ASA) have been described to be involved in immunological infertility. A possible antigen for ASA is the human cysteine-rich secretory protein 2 (CRISP-2), a sperm surface protein important in sperm-oocyte interaction. Furthermore, anti-CRISP-2 antibodies were shown to decrease fertility rates in vitro. Recently, we have reported cross-reacting antibodies recognizing CRISP-2 and antigen 5 from yellow jacket venom (Ves v 5) in human serum. METHODS: Here, we investigated anti-Ves v 5 and CRISP-2 antibodies in sera from two groups of donors: MAR+ and MAR- patients. RESULTS: A higher incidence of allergy against hymenoptera venom was found in MAR+ patients. Interestingly, affinity-purified ASA from MAR+ patients' sera reacted against both Ves v 5 and CRISP-2, leading to sperm immobilization. Immunofluorescence analysis showed that ASA bound to the sperm surface, including the head part where CRISP-2 is localized. CONCLUSION: Taken together, these results showed a higher incidence of antibodies cross-reacting with Ves v 5 and CRISP-2 in MAR+ patients. This leads to the hypothesis that MAR+ patients may have a higher risk to develop wasp allergy.