Rapid DNA multi-analyte immunoassay on a magneto-resistance biosensor.

We present the rapid and sensitive detection of amplified DNA on a giant magneto-resistance sensor using superparamagnetic particles as a detection label. The one-step assay is performed on an integrated and miniaturized detection platform suitable for application into point-of-care devices. A double-tagged PCR amplification product of the LamB gene of the Escherichia coli bacterium was used to investigate binding kinetics of the assay. We applied magnetic actuation to concentrate the target-particle complexes at the sensor surface and to remove unbound particles from the sensor surface. We achieved biological dose-response curves detecting 4-250pM amplicon concentrations in a one-step format in total assay times of less than 3min. Using various tag-antibody combinations specific for one of the individual genes, multi-analyte detection is shown of several antibiotic resistance genes of the food pathogen Salmonella.

Mechanism of induction of asthmatic attacks initiated by the inhalation of particles generated by airbag system deployment.

OBJECTIVE: We have previously demonstrated that inhalation of the dust produced by dual frontal airbag deployment can result in significant bronchospasm in approximately 40% of mild to moderate asthmatics. This study was performed to determine the cause of the asthmatic response. DESIGN: Controlled laboratory study. MATERIALS AND METHODS: Asthmatics who were previously tested for their response to airbag effluents were exposed for twenty minutes to either 1) airbag effluents from airbag systems in which the airbag was insulated from the hot deployment module; 2) non-sulfur containing airbag effluents; 3) sodium chloride aerosol; or 4) sodium carbonate-bicarbonate aerosol (pH 10). Pre-exposure, post-exposure, and 2 hour post exposure pulmonary spirometry and mechanics were measured. Subject's filled out symptoms questionnaires before exposure, 2, 4, 8, 12, and 19 minutes into the exposure, immediately post-exposure, and 2 hours post-exposure. MEASUREMENTS AND MAIN RESULTS: Prevention of the pyrolysis of the passenger-side bag as it rested on the hot module after deployment did not diminish the asthmatic response. Removal of sulfur-containing oxidants from the airbag pyrotechnic chemistry, which may have led to sulfite production, similarly did not alleviate the asthmatic response to the airbag effluents. Lastly, when asthmatics were exposed to sodium chloride and sodium carbonate-bicarbonate aerosols at approximately the same concentration (approximately 220 mg/m3) as the airbag aerosol concentration that occurred in the in-car tests, they had responses similar to those produced by the airbag exposures. CONCLUSIONS: We conclude that the amount of soluble particulate contained in the aerosol discharged into the passenger compartment by dual frontal airbag deployment is largely the cause of the observed evoked asthmatic attacks. The alkaline pH of the airbag and carbonate aerosols may have added an additional degree of provocation.

Pharmacokinetics and cyclooxygenase inhibition of itazigrel in normal volunteers after single oral doses.

The pharmacokinetics and cyclooxygenase inhibition of itazigrel were studied in normal male volunteers. In a low-dose study, subjects received a single oral dose of 5-100 mg of itazigrel. Serum concentration and the production rate of thromboxane B2, an indicator of cyclooxygenase activity, were monitored for 48 h. In a high-dose study, single oral doses of 100-600 mg of itazigrel were administered. Serum concentrations were monitored for 72 h. Production rates of thromboxane B2 and leukotriene B4, an indicator of lipoxygenase activity, were monitored for the first 2 h after drug administration. Pharmacokinetics of itazigrel appeared to follow biexponential elimination with an alpha half-life between 1.2 and 2 h and a beta half-life between 23 and 28 h. The relationship between dose and area under the serum concentration curve was nonlinear, probably due to saturable systemic metabolism or saturable first-pass metabolism. Cyclooxygenase inhibition by itazigrel was related to the serum concentration by the Hill's equation with a mean IC50 value of 2.1 ng/mL. Itazigrel did not appear to affect the lipoxygenase activity in the study.

Hemostasis changes during cardiopulmonary bypass surgery.

A number of hemostasis parameters were studied in a total of 63 patients undergoing cardiopulmonary bypass (CPB) for open heart surgery. In 33 patients fibrinogen, Factors II, V, VIII:C, X, XI, antithrombin, plasminogen, alpha 2-antiplasmin, and platelet counts were assayed before surgery, during maximal hypothermia, at the end of the bypass procedure, before and after protamine sulfate infusion, in the intensive care unit, and 48 hours postoperatively. All factors assayed decreased markedly when the patients were placed on the bypass machine, the drop fairly well paralleling the decrease in hematocrit. During bypass the factors remained low, although a slight tendency toward an increase was noted. Only platelet counts remained low with a decreasing trend until the end of bypass. In the intensive care unit a second decrease in fibrinogen, Factors II and V and antithrombin was noted. This drop was unrelated to four patients who experienced a greater blood loss during this time than the others. Forty-eight hours postoperatively, a marked increase could be found in all clotting factors and near normal levels were measured. Platelet counts remained low, however. The decrease in factors rarely dropped into a range where one would expect a compromised hemostasis (less than 30%). Although antithrombin levels decreased below 60%, no difficulties with heparinization were encountered. Several factors were assayed manually and by automated analyzer (Multistat III), and excellent correlations were found between both procedures. Also a good correlation was found between the activated whole blood clotting times and quantitative heparin assays. In 30 additional patients platelet function was studied before surgery, after thoracotomy, after heparin administration, after initiation of bypass, at maximal hypothermia, before and after protamine sulfate infusion, and 24 hours postoperatively. Platelet counts once again decreased as patients were placed on the CPB machine and remained low throughout the procedure. Mean platelet volumes were unchanged until protamine was given. At that time, a significant drop in mean platelet volume was recorded. Twenty-four hours postoperatively the volumes were normal again. Platelet aggregation studies were performed on a whole blood aggregometer using two concentrations of ADP, collagen, and ristocetin as aggregation inducers. A significant decrease in aggregability was seen when the patients were connected to the CPB apparatus.(ABSTRACT TRUNCATED AT 400 WORDS)

Early events in the formation of a venous thrombus following local trauma and stasis.

A jugular vein was exposed in 20 cats divided into four groups of five cats each. In group 1 the vein was removed immediately after exposure. In group 2 the vein was removed after three 5-minute periods of stasis and reflow. Groups 3 and 4 had the jugular vein occluded for 24 and 72 hours, respectively. In all groups, veins were perfused under physiologic pressure by heparinized saline to remove blood and immersed in 2.5% glutaraldehyde for fixation. All vessels were prepared for scanning and transmission electron microscopy. Group 1 cats had a normal-appearing luminal surface. Group 2 cats had deposition of leukocytes with few erythrocytes or platelets. Groups 3 and 4 had deposition of leukocytes, platelets, and erythrocytes. Leukocytes were found in all areas and associated with all cell types. Platelets and erythrocytes were seldom found in the absence of leukocytes. Thrombi were found on normal-appearing and damaged endothelium. The majority of thrombi were found at side branches and valve pockets. Our results suggest that leukocytes play a primary role in the initiation of deep vein thrombosis. Platelets may have only a secondary role.

Quantitation of hemoglobin A1a+b and hemoglobin A1c by automated "high-performance" liquid chromatography.

The glycosylated hemoglobins A1a+b and A1c have been rapidly and precisely quantitated in 5-micro L samples of human blood hemolysate (approximately 240 micrograms of hemoglobin) by cation-exchange column chromatography. Total chromatographic is 22.0 min. Proportions of Hb A1c range from 3.85 to 6.71% in normal individuals and from 4.23 to 19.90% in diabetic subjects. Within-day variation was 1.58 and 1.10% for mean Hb A1c proportions of 4.92 and 10.32%, respectively. Hb A1c and Hb A1 are stable in hemolysates stored at 4 degrees C for as long as seven days, and indefinitely under liquid nitrogen.