Personal non-commercial use only

ABSTRACT. Objective. Infections and thromboses are known complications of systemic lupus erythematosus (SLE). We investigated if infectious episodes in patients with SLE were followed by an increased risk of thrombotic events. Methods. A cohort of 571 patients with prevalent or incident SLE was followed for a mean of 8.9 ± 7.6 years. All episodes of hospitalized infections or episodes of cutaneous herpes zoster as well as arterial and venous thrombotic events were identified by retrospective chart review and prospective updating of a clinical database. For time-dependent analyses adjusted for age, sex, and ever-presence of antiphospholipid antibodies, thrombotic events were classified as occurring during the time at risk of 1 year after an infection or during the remaining control observation time. Infections and thromboses occur at an increased rate in patients with systemic lupus erythematosus (SLE) and, together with active SLE, are the most frequent causes of death in patients with SLE 1,2,3 . In general, acute infections have been recognized to be associated with the development of arterial thromboses, including myocardial infarction (MI) and stroke 4 . Also, the risk of MI and stroke after an acute respiratory tract infection is greater than after less severe urinary tract infection 5 . Large retrospective studies consistently find a 2-fold to 3-fold increase in the risk for acute coronary syndromes within 1-2 weeks after a respiratory infection, and this risk remains significant at 3 months 4 . It has been hypothesized that infections, in addition to eliciting systemic inflammatory responses, can also have direct inflammatory effects on atherosclerotic plaques and coronary arteries 4 . Studies have also demonstrated that there is a transient (up to 1 year) increased risk of venous thromboses [deep venous thrombosis (DVT) and pulmonary embolism (PE)] after respiratory infection 6,7 and urinary tract infection 7 in the general population. Clayton, et al found a 2.6-fold increased risk of DVT in the month following a respiratory infection persisting up to a year, as well as a 2.5-fold increased risk of PE for the same period 6 . We investigated whether infectious episodes in patients with SLE were followed by an increased risk of arterial and venous thrombotic events. MATERIALS AND METHODS Patients and procedures. Our SLE cohort was started and the majority of data (on 513 patients) were retrospectively collected in 1995 as part of previous study 8 . Patients were followed at several hospital centers in Denmark, including university hospitals that have specialized functions in diagnosing and treating SLE, and locally identified by means of a national disease coding system. Data collection on consecutive patients with SLE seen at one of the university hospitals is continuing, and we included further incident cases, resulting in data on 571 adult patients with SLE fulfilling the modified American College of Rheumatology (ACR) 1982 9 or 1997 10 classification criteria. The electronic SLE database includes basic demographics, SLE symptoms and dates of symptom onset, immunologi

Personal non-commercial use only

ABSTRACT. Objective. Infections and thromboses are known complications of systemic lupus erythematosus (SLE). We investigated if infectious episodes in patients with SLE were followed by an increased risk of thrombotic events. Methods. A cohort of 571 patients with prevalent or incident SLE was followed for a mean of 8.9 ± 7.6 years. All episodes of hospitalized infections or episodes of cutaneous herpes zoster as well as arterial and venous thrombotic events were identified by retrospective chart review and prospective updating of a clinical database. For time-dependent analyses adjusted for age, sex, and ever-presence of antiphospholipid antibodies, thrombotic events were classified as occurring during the time at risk of 1 year after an infection or during the remaining control observation time. Infections and thromboses occur at an increased rate in patients with systemic lupus erythematosus (SLE) and, together with active SLE, are the most frequent causes of death in patients with SLE 1,2,3 . In general, acute infections have been recognized to be associated with the development of arterial thromboses, including myocardial infarction (MI) and stroke 4 . Also, the risk of MI and stroke after an acute respiratory tract infection is greater than after less severe urinary tract infection 5 . Large retrospective studies consistently find a 2-fold to 3-fold increase in the risk for acute coronary syndromes within 1-2 weeks after a respiratory infection, and this risk remains significant at 3 months 4 . It has been hypothesized that infections, in addition to eliciting systemic inflammatory responses, can also have direct inflammatory effects on atherosclerotic plaques and coronary arteries 4 . Studies have also demonstrated that there is a transient (up to 1 year) increased risk of venous thromboses [deep venous thrombosis (DVT) and pulmonary embolism (PE)] after respiratory infection 6,7 and urinary tract infection 7 in the general population. Clayton, et al found a 2.6-fold increased risk of DVT in the month following a respiratory infection persisting up to a year, as well as a 2.5-fold increased risk of PE for the same period 6 . We investigated whether infectious episodes in patients with SLE were followed by an increased risk of arterial and venous thrombotic events. MATERIALS AND METHODS Patients and procedures. Our SLE cohort was started and the majority of data (on 513 patients) were retrospectively collected in 1995 as part of previous study 8 . Patients were followed at several hospital centers in Denmark, including university hospitals that have specialized functions in diagnosing and treating SLE, and locally identified by means of a national disease coding system. Data collection on consecutive patients with SLE seen at one of the university hospitals is continuing, and we included further incident cases, resulting in data on 571 adult patients with SLE fulfilling the modified American College of Rheumatology (ACR) 1982 9 or 1997 10 classification criteria. The electronic SLE database includes basic demographics, SLE symptoms and dates of symptom onset, immunologi

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data