Optimized surface plasmon resonance immunoassay for staphylococcal enterotoxin G detection using silica nanoparticles

Staphylococcal enterotoxins are one of the most important causative agents of food poisoning. These molecules function as both gastrointestinal toxins and superantigens (SAgs) which can simultaneously bind MHC-II and T cell receptor leading to a non-specific polyclonal T cell activation and massive proinflammatory cytokine release. Common symptoms include vomiting and diarrhea; however, in more severe cases, systemic dissemination may result in toxic shock syndrome and can be lethal in a few hours. Only small amounts of these heat-stable toxins are needed to cause the disease. Therefore, it is highly important to detect quickly low concentrations of SAgs in biological samples. In this work, we report a surface plasmon resonance (SPR)-based capture immunoassay for the detection of the SAg SEG. We analyzed the use of different amplification strategies. The SPR-based double-antibody sandwich approach could detect picomolar levels of SEG. The use of antibody-coated silica nanoparticles (AbSiNPs) as an alternative enhancing reagent also detected SEG in the picomolar range. Although AbSiNPs did not improve the limit of detection, for the same amount of SAg tested, AbSiNPs gave a higher response level than free antibodies. This work highlights the suitability of silica nanoparticles for signal amplification in SPR-based biosensors. Overall, SPR biosensors offer the capability for continuous real-time monitoring and high sensitivity that can be befitting for the detection of enterotoxins in food industries, laboratories and regulatory agencies.

Increased levels of factor VIII and fibrinogen in patients with venous thrombosis are not caused by acute phase reactions

Factor VIII activity (factor VIII:C) levels > or =150 IU/dl are associated with a 5- to 6-fold increased risk of venous thrombosis compared to levels <100 IU/dl, and fibrinogen levels > or =5.0 g/l increase the thrombosis risk 4-fold. These high levels are present in 25% resp. 3% of the patients with a first episode of venous thrombosis. These findings were based on measurements after the thrombotic event, so the factor VIII and fibrinogen levels in thrombosis patients may have been influenced by acute phase reactions or ongoing inflammatory responses. In the present study we measured plasma C-reactive protein (CRP) as a sensitive marker of an acute phase reaction in 474 thrombosis patients and 474 age- and sex-matched healthy controls, that were part of the Leiden Thrombophilia Study (LETS). Mean and median CRP levels were higher in thrombosis patients than in the controls, suggesting inflammation in some patients. CRP affected both factor VIII and fibrinogen levels, in patients and controls alike. After adjustment for the effect of CRP, high factor VIII:C levels still increased the thrombosis risk 6-fold and high fibrinogen levels 4-fold, which is for both very similar to the risk before correction for CRP levels. These results show that although systemic inflammation may be present in some of the patients, elevated levels of factor VIII:C and fibrinogen were in general not caused by acute phase reactions. This further supports a causal relationship between both high factor VIII:C and fibrinogen levels and venous thrombosis.

Minitracheostomy in elective surgery of the larynx: an alternative to formal tracheostomy

A patient scheduled for surgical removal of a giant polyp of the larynx, and in whom difficult orotracheal intubation was anticipated in the preoperative visit, was managed successfully with a minitracheostomy performed with a Mini-Trach II kit. The ventilation achieved was adequate throughout the procedure. Thus, conventional tracheostomy was avoided.

Square pegs in round holes: a study of residents in long-term institutions in London, Ont

A large random sample of people in the long-term institutions (homes for the aged, nursing homes and continuing care hospitals) of London, Ont. was studied to assess the suitability of these people, according to physical and mental status, for the institution in which each resided. The results indicated a relative need for beds in homes for the aged and nursing homes. A high proportion (29% to 54%) of people in the three types of institutions were unsuitably placed. Greater flexibility is needed in institutional arrangements, and institutions should be examined for their potential to provide support in maintaining the elderly at home. The findings of this study add some weight to the arguments of those calling for more and better home care programs for the disabled.