Blur adaptation: clinical and refractive considerations

The human visual system is amenable to a number of adaptive processes; one such process, or collection of processes, is the adaptation to blur. Blur adaptation can be observed as an improvement in vision under degraded conditions, and these changes occur relatively rapidly following exposure to blur. The potential important future directions of this research area and the clinical implications of blur adaptation are discussed.     

Multiple small-bowel carcinoids presenting with gastrointestinal hemorrhage: a case report

Gastrointestinal hemorrhage from a small-bowel lesion can be a problem diagnostically and therapeutically. The authors present a case of multiple small-bowel carcinoids, which were the cause of multiple upper gastrointestinal hemorrhages over a 15-year period. Despite advances in endoscopy and diagnostic imaging, accurate localization and definitive diagnosis remain elusive in such cases. Optimal treatment depends on careful clinical evaluation and timely laparotomy.     

The 'Do not resuscitate' order. A profile of its changing use

The "do not resuscitate" (DNR) order has wide-ranging ethical, legal, and economic implications. We reviewed the course of 244 patients who died during two three-month periods, in 1982 and 1986. We found that 68% of patients who died had a DNR order written, including 94% with malignancy and half of patients with cardiovascular disease. Most orders (61%) were written within three days of death, with 64% written on medical-surgical floors and 34% in critical care units. Even among patients under the age of 60 years, 57% had a DNR order written by the time of death. Ninety-one percent of DNR orders were written by attending physicians, with accompanying explanatory note in 84%. Documentation showed only 14% of patients but 77% of families being consulted. In 1983 a new two-level DNR order system defined two levels of intensity: "all but cardiopulmonary resuscitation" and "comfort measures only." Equal numbers of patients received each order in the 1986 sample. No patient was transferred to the critical care units after a DNR order had been written. The prevalence of DNR orders written for patients dying of cardiovascular disease increased from 27% to 64% over the four years. We conclude, from study of deaths in this representative community hospital, that an explicit DNR order is now the rule rather than the exception, but decisions are made late and involve family far more than the patient.     

Interlaboratory validation of a CD71-based flow cytometric method (Microflow) for the scoring of micronucleated reticulocytes in mouse peripheral blood

An interlaboratory study was performed to validate an anti-CD71/flow cytometry-based technique for enumerating micronucleated reticulocytes (MN-RETs) in mouse peripheral blood. These experiments were designed to address International Workshop on Genotoxicity Test Procedures validation criteria by evaluating the degree of correspondence between MN-RET measurements generated by flow cytometry (FCM) with those obtained using traditional microscopy-based methods. In addition to these cross-methods data, flow cytometric MN-RET measurements for each blood sample were performed at two separate sites in order to evaluate the reproducibility of data between laboratories. In these studies, groups of male CD-1 mice were treated with vehicle (saline or vegetable oil), a negative control (saline or vegetable oil), or four dose levels of five known genotoxicants (clastogens: cyclophosphamide, benzo[a]pyrene, 5-fluorouracil, methotrexate; aneugen: vincristine sulfate). Exposure occurred on 3 consecutive days via intraperitoneal injection, and blood samples were obtained approximately 24 hr after the final treatment. MN-RET frequencies were determined for each sample based on the analysis of 2,000 (microscopy) and 20,000 (FCM) reticulocytes. Regardless of the method utilized, each genotoxic agent was observed to cause statistically significant increases in the frequency of MN-RETs, and each response occurred in a dose-dependent manner. Spearman's correlation coefficient (rs) for FCM versus microscopy-based MN-RET measurements (nine experiments, 252 paired measurements) was 0.740, indicating a high degree of correspondence between methods. The rs value for all flow cytometric MN-RET measurements performed at the two independent sites was 0.857 (n = 248), suggesting that the automated method is highly transferable between laboratories. Additionally, the flow cytometric system offered advantages relative to microscopy-based scoring, including a greater number of cells analyzed, much faster analysis times, and a greater degree of objectivity. Collectively, data presented in this report suggest that the overall performance of mouse peripheral blood micronucleus tests is enhanced by the use of the flow cytometric scoring procedure.