ObjectiveWe investigated whether systemic lupus erythematosus (SLE) disease duration or serology associate with abnormal regional glucose metabolism as measured with [18F]2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) and deficits on neuropsychological testing.MethodsSubjects with SLE with stable disease activity, without brain damage or clinical symptoms of neuropsychiatric (NP) SLE, stratified by disease duration (short-term (ST)-SLE=disease ≤2 years, long-term (LT)-SLE=disease ≥10 years), underwent clinical assessments, neuropsychological testing, resting FDG-PET scan imaging and measurement of serum titres of antibody to N-methyl-d-aspartate receptor (DNRAb). FDG-PET scans were compared with age-matched and gender-matched healthy controls.ResultsSubjects with LT-SLE demonstrated hypometabolism in the prefrontal and premotor cortices that correlated with accrued SLE-related damage, but not with DNRAb titre or performance on NP testing. Independent of disease duration, subjects with SLE demonstrated hypermetabolism in the hippocampus and orbitofrontal cortex that correlated with impaired memory performance and mood alterations (depression, anxiety, fatigue). Serum DNRAb also correlated independently with impaired memory performance and increased anxiety. Together, serum DNRAb titre and regional hypermetabolism were more powerful predictors of performance than either alone.InterpretationThe presence of serum DNRAbs can account for some aspects of brain dysfunction in patients with SLE, and the addition of regional measurements of resting brain metabolism improves the assessment and precise attribution of central nervous system manifestations related to SLE.

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Clinical and environmental analyses frequently necessitate rapid, simple, and inexpensive point-of-care or field tests. These semiquantitative tests may be later followed up by confirmatory laboratory-based assays, but provide an initial scenario assessment important for resource mobilization and threat confinement. Lateral-flow assays (LFAs) and dip-stick assays, which are typically antibody-based and yield a visually detectable signal, provide an assay format suiting these applications extremely well. Signal generation is commonly obtained through the use of colloidal gold or latex beads, which yield a colored band either directly proportional or inversely proportional to the concentration of the analyte of interest. Here, dye-encapsulating liposomes as a highly visible alternative are discussed. The semiquantitative LFA biosensor described in this chapter relies on a sandwich immunoassay for the detection of myoglobin in whole blood. After an acute myocardial infarction (AMI) event, several cardiac markers are released into the blood, the most common of which are troponin, creatine kinase MB, C-reactive protein, and myoglobin. Due to its early release, myoglobin has value as an indicator of a recent heart attack amongst conditions which present with similar symptoms and its lack of elevation can effectively rule out a heart attack (Brogan et al., Ann Emerg Med 24:665-671, 1994). The assay described within relies on sandwich complex formation between a membrane immobilized capture monoclonal antibody against myoglobin, a detector biotinylated monoclonal antibody against a different epitope on myoglobin, and streptavidin-conjugated visible dye (sulforhodamine B)-encapsulating liposomes to allow for signal generation.

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