Management of chemical cyanosis by oxygen saturation readings.

Chemical cyanosis is an oxygen transport deficiency produced by exposure to aromatic nitro- or animo-compounds. Evaluation of its severity by methemoglobin determinations defines the problem incompletely and is time consuming. Twenty-nine patients were studied over a five-year period by both methemoglobin level using classical laboratory methods and oxygen saturation level, using a reflection oximeter. The two results were found to bear an inverse linear relationship. Oxygen saturation may be determined easily and rapidly by the reflection oximeter method, and may be used safely as a guide to treatment of chemical cyanosis. No changes would have been made in medical management of any of the patients if the decisions had been made on the basis of the oxygen saturation level of less than 90% rather than the methemoglobin percentage of 10% or more.     

Targeted loss of SHP1 in murine thymocytes dampens TCR signaling late in selection

SHP1 is a tyrosine phosphatase critical to proximal regulation of TCR signaling. Here, analysis of CD4‐Cre SHP1^fl/fl conditional knockout thymocytes using CD53, TCRβ, CD69, CD4, and CD8α expression demonstrates the importance of SHP1 in the survival of post selection (CD53⁺), single‐positive thymocytes. Using Ca²⁺ flux to assess the intensity of TCR signaling demonstrated that SHP1 dampens the signal strength of these same mature, postselection thymocytes. Consistent with its dampening effect, TCR signal strength was also probed functionally using peptides that can mediate selection of the OT‐I TCR, to reveal increased negative selection mediated by lower‐affinity ligand in the absence of SHP1. Our data show that SHP1 is required for the survival of mature thymocytes and the generation of the functional T‐cell repertoire, as its absence leads to a reduction in the numbers of CD4⁺ and CD8⁺ naïve T cells in the peripheral lymphoid compartments.     

Computerized tomography in the evaluation of allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is a destructive disease of the lung characteristically associated with central bronchiectasis. This study was designed to determine if high-resolution computerized tomography (CT) could be used to define bronchiectasis in patients with suspected disease. Sixteen patients with asthma were studied. All demonstrated immediate cutaneous reactivity to common aeroallergens including Aspergillus fumigatus. Eight patients had clinical and immunologic evidence of ABPA. Six to 12 high-resolution CT sections (1.5 mm) were obtained at 1- to 2-cm intervals from the aortic knob to the dome of the diaphragm. All radiographs were evaluated separately by two readers in a blinded fashion and graded as to the presence and type of bronchial dilatation and bronchial wall thickening. Bronchial dilatation was seen in 41% of lung lobes in the ABPA group compared to 15% in the non-ABPA asthmatic control group. Upper lobe involvement and bronchial wall thickening was common to both groups. The presence of bronchiectasis in the control group may indicate that asthma is a more destructive lung disease than is currently appreciated. High-resolution CT of the chest has been shown in previous studies to have a sensitivity and specificity approaching that of bronchography, and the current findings support its use in the detection of bronchiectasis in patients with asthma suspected of having ABPA.     

Patient classification systems, Part 2: The third generation.

In Part 1 (July/August 1999), the authors reviewed the evolution of patient classification systems over four generations of progress, discussed issues of system credibility, and presented a third-generation patient classification system (3PCS) to address the shortcomings of current systems. In this article, an actual implementation of a 3PCS is presented by the authors in collaboration with system users. The development, implementation, and evaluation of the 3PCS, as well as the overall advantages, are discussed. Finally, the authors share lessons learned and thoughts for the future.