Transferrin allelic variants may cause false positives in the detection of cerebrospinal fluid fistulae.

Variations in either the polypeptide sequence or the carbohydrate moieties of transferrin may result in altered electrophoretic mobility of this molecule. We report a case of an allelic (polypeptide) variant of transferrin with mobility similar to that of the beta 2 (sialic acid-depleted) transferrin found in cerebrospinal fluid (CSF) and a few other body fluids. Allelic variation and other transferrin anomalies may be mistaken for the CSF isoform, resulting in false diagnoses of CSF fistulae.

Predicting death in patients hospitalized for community-acquired pneumonia.

OBJECTIVE: To validate a previously reported discriminant rule for predicting mortality in adult patients with primary community-acquired pneumonia and to determine which factors available at hospital admission predict a fatal outcome among such patients. DESIGN: Historical cohort study. SETTING: University hospital. PATIENTS: Adults admitted to the hospital for community-acquired pneumonia. MEASUREMENTS: Using stepwise logistic regression, we analyzed prognostic factors (data available at admission and recorded in the medical record) that showed a univariate association with mortality. The predictive values of three discriminant rules were measured to validate the results of a previous study. MAIN RESULTS: Of 245 patients, 20 (8.2%) died. Of 42 prognostic factors identified in previous studies, 8 were associated with mortality, but only a respiratory rate of 30/min or more, a diastolic blood pressure of 60 mm Hg or less, and a blood urea nitrogen of more than 7 mmol/L remained predictive in the multivariate analysis. A discriminant rule composed of these three variables was 70% sensitive and 84% specific in predicting mortality, yielding an overall accuracy of 82%. CONCLUSION: Tachypnea, diastolic hypotension, and an elevated blood urea nitrogen were independently associated with death from pneumonia in our study, confirming the value of a previously reported discriminant rule from the British Thoracic Society. This rule may be useful in triage decisions because it identifies high-risk patients who may benefit from special medical attention.

The interaction of antibody/DNA immune complexes with complement. Influence of antibody class and DNA conformation.

In 28 serum and plasma samples from patients with systemic lupus erythematosus, we examined the importance of antibody class with respect to complement-mediated binding to human red blood cells (RBC) of antibody/DNA immune complexes (IC) prepared with anti-DNA antibodies. We used both 3H-double-stranded DNA and 3H-single-stranded DNA (ssDNA). Generally, double-stranded DNA IC showed considerably higher binding than did ssDNA IC in the RBC binding assay. Further analysis indicated that although ssDNA IC fix complement, it is necessary that these IC contain IgM anti-DNA antibodies in order for them to bind to RBC. The results suggest that the mechanisms of clearance and pathogenic potential of these IC may depend upon both the DNA conformation and antibody class. In particular, complement-fixing IC which contain IgG anti-DNA antibodies and ssDNA may not be cleared via the erythrocyte clearance mechanism, and therefore, could be more likely to deposit in certain tissues and initiate inflammatory reactions.