Carpal avascular necrosis: MR imaging

The authors evaluated the use of magnetic resonance (MR) imaging in diagnosis of avascular necrosis (AVN) of carpal bones by examining 21 patients with wrist pain and two healthy volunteers. MR images were compared with conventional radiographs in every case and with bone scintigrams in 18 cases. MR imaging was slightly less sensitive than bone scintigraphy in depicting AVN, but in patients who were imaged with long repetition time (TR)/long echo time (TE) sequences in addition to short TR/short TE sequences, MR imaging was found to be more specific. While the authors believe that bone scintigraphy remains the screening test of choice for patients with wrist pain and normal plain radiographs, MR imaging promises to add significant diagnostic information in cases in which bone scans are abnormal.     

A comparison of the Invos 3100 and the Critikon 2020 near-infrared spectrophotometers as monitors of cerebral oxygenation

Assessment of cerebral oxygenation using near-infrared spectroscopy in intensive care is increasing. We compared the ability of the Invos 3100 and the Critikon 2020 monitors to produce stable and consistent readings of regional cerebral oxygen saturation in resting volunteers. Failure to obtain any stable reading with the Critikon occurred in eight out of 18 subjects (44.4%) and with the Invos in three out of 15 subjects (20%). The Critikon showed a significantly higher failure rate in male subjects (p = 0.0011). Differences in recorded values of cerebral oxygen saturation (Critikon − Invos) ranged from −4.7% to 12.6% and were significantly related to the average saturation level (p < 0.0001). The within-monitor variability was significantly higher for the Invos (p = 0.0124). Neither monitor is able to give stable and consistent readings over time, particularly in male subjects. The unacceptably high failure rate of the recently introduced Critikon 2020 will limit or prevent its clinical use.     

Effects of Bispectral Index Monitoring on Recovery from Surgical Anesthesia in 1,580 Inpatients from an Academic Medical Center

Background: The purpose of this study was to determine whether monitoring Bispectral Index (BIS) would affect recovery parameters in patients undergoing inpatient surgery.

Methods: Anesthesia providers (n = 69) were randomly assigned to one of two groups, a BIS or non-BIS control group. A randomized crossover design was used, with reassignment at monthly intervals for 7 months. Duration of time in the postanesthesia care unit, time from the end of surgery to leaving the operating room, and incidence of delayed recovery (> 50 min in recovery) were compared in patients treated intraoperatively with or without BIS monitoring. Data were analyzed by analysis of variance, unpaired t test, or chi-square test as appropriate.

Results: One thousand five hundred eighty patients in an academic medical center were studied. The mean BIS in the monitored group was 47. No differences were found in recovery parameters between the BIS-monitored group and the control group when comparisons were made using all subjects or when data were analyzed within anesthetic subgroups stratified by anesthetic agent or duration of anesthesia. There were some small reductions in the intraoperative concentration of sevoflurane (but not isoflurane).     

CD1b presents self and Borrelia burgdorferi diacylglycerols to human T cells

Lyme disease is a common multisystem disease caused by infection with a tick‐transmitted spirochete, Borrelia burgdorferi and related Borrelia species. The monoglycosylated diacylglycerol known as B. burgdorferi glycolipid II (BbGL‐II) is a major target of antibodies in sera from infected individuals. Here, we show that CD1b presents BbGL‐II to human T cells and that the TCR mediates the recognition. However, we did not detect increased frequency of CD1b‐BbGL‐II binding T cells in the peripheral blood of Lyme disease patients compared to controls. Unexpectedly, mapping the T cell specificity for BbGL‐II‐like molecules using tetramers and activation assays revealed a concomitant response to CD1b‐expressing APCs in absence of BbGL‐II. Further, among all major classes of self‐lipid tested, BbGL‐II responsive TCRs show strong cross‐reactivity to diacylglycerol, a self‐lipid antigen with structural similarities to BbGL‐II. Extending prior work on MHC and CD1b, CD1c, and CD1d proteins, this study provides evidence for cross‐reactive CD1b‐restricted T cell responses to bacterial and self‐antigens, and identifies chemically defined targets for future discovery of self and foreign antigen cross‐reactive T cells.     

Routine quantitation of white cells as low as 0.001 per microL in platelet components

A method is described for routine quantitation of very low numbers of white cells (WBCs) in platelet components, using flow cytometry and dual nucleic acid stains. The WBC quantitation is based on the detection of nucleated cells labeled with propidium iodide and thiazole orange, with chicken red cells added as an internal counting standard. Platelet concentrates containing 0.001 to 1500 WBCs per microL (2 × 10(2)-3 × 10(8) WBCs/component) and 600 to 2800 × 10(3) platelets per microL were analyzed for the number of contaminating WBCs. The method was found to be linear throughout the 7 log10 range and to have sufficient reproducibility and sensitivity for routine analysis of WBC- reduced platelet concentrates.