Beta-2-glycoprotein I antibodies in patients with thrombosis.

The laboratory diagnosis of antiphospholipid antibody syndrome currently requires two consecutive positive results in either lupus anticoagulant or anticardiolipin antibody assays. Antibodies against beta-2-glycoprotein I (abeta2-GPI) are suggested as a new marker for the syndrome. The inclusion of abeta2-GPI in the official diagnostic criteria has so far been precluded owing to lack of an international standard and also technical difficulties. Samples from 5367 consecutive patients sent to a national reference laboratory mainly because of various thrombotic events were studied. An IgG abeta2-GPI ELISA assay was performed in addition to lupus anticoagulant (dRVVT and PTT-LA) and IgG anticardiolipin antibody determinations to evaluate patient groups in which the new assay might be of value. From a total of 90 patients, 2.2% of the samples were abeta2-GPI positive; 51 patients had abeta2-GPI as the only positive antiphospholipid antibody marker; 20 patients had had a venous thrombosis and 14 an arterial thrombosis, 4 had pregnancy complications and 2 had thrombocytopenia. Relatively young patients with cerebrovascular ischaemic events seemed especially to present sole abeta2-GPI positivity. The abeta2-GPI positivity remained fairly constant in the 23 patients from whom follow-up samples were taken. It is concluded that the IgG abeta2-GPI assay seems to be a potentially important additional diagnostic tool for the antiphospholipid antibody syndrome.

A novel two-component regulatory system in Bacillus subtilis for the survival of severe secretion stress.

The Gram-positive eubacterium Bacillus subtilis is well known for its high capacity to secrete proteins into the environment. Even though high-level secretion of proteins is an efficient process, it imposes stress on the cell. The present studies were aimed at the identification of systems required to combat this so-called secretion stress. A two-component regulatory system, named CssR-CssS, was identified, which bears resemblance to the CpxR-CpxA system of Escherichia coli. The results show that the CssR/S system is required for the cell to survive the severe secretion stress caused by a combination of high-level production of the alpha-amylase AmyQ and reduced levels of the extracytoplasmic folding factor PrsA. As shown with a prsA3 mutation, the Css system is required to degrade misfolded exported proteins at the membrane-cell wall interface. This view is supported by the observation that transcription of the htrA gene, encoding a predicted membrane-bound protease of B. subtilis, is strictly controlled by CssS. Notably, CssS represents the first identified sensor for extracytoplasmic protein misfolding in a Gram-positive eubacterium. In conclusion, the results show that quality control systems for extracytoplasmic protein folding are not exclusively present in the periplasm of Gram-negative eubacteria, but also in the Gram-positive cell envelope.