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We present three cases of "crack" cocaine-associated stroke, together with a review of cocaine-associated cerebrovascular complications. Unlike previously reported cases tentatively associating ischemic stroke with cocaine, our patients had no other potential causes for their strokes. Although the exact mechanism of cocaine-related stroke remains uncertain, both disordered neurogenic control of the cerebral circulation as well as systemic factors (ie, acute hypertension) may play a role.

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There is no established method for accurately predicting how much blood loss has occurred during hemorrhage. In the present study, we examine whether a genetic algorithm neural network (GANN) can predict volume of hemorrhage in an experimental model in rats and we compare its accuracy to stepwise linear regression (SLR). Serial measurements of heart period; diastolic, systolic, and mean blood pressures; hemoglobin; pH; arterial PO2; arterial PCO2; bicarbonate; base deficit; and blood loss as percent of total estimated blood volume were made in 33 male Wistar rats during a stepwise hemorrhage. The GANN and SLR used a randomly assigned training set to predict actual volume of hemorrhage in a test set. Diastolic blood pressure, arterial PO2, and base deficit were selected by the GANN as the optimal predictors set. Root mean square error in prediction of estimated blood volume by GANN was significantly lower than by SLR (2.63%, SD 1.44, and 4.22%, SD 3.48, respectively; P < 0.001). A GANN can predict highly accurately and significantly better than SLR volume of hemorrhage without knowledge of prehemorrhage status, rate of blood loss, or trend in physiological variables.

The purpose of this retrospective study was to examine the relationship between tumor volume and age in resected non-small cell lung cancer (NSCLC). Differences exist in the behavior, growth rate, and metastatic potential of solid tumors in both aged humans and experimental animal models. Data from 669 cases of NSCLC resected between 1980 and 1992 were reviewed (445 males; 224 females; median age 67 years, range 16-86). Measurements of the resected tumor in-situ were made in three dimensions, and these were multiplied to give an estimate of the tumor volume. Multiple regression analysis was used to examine the relationship between the tumor volume, age, gender, histological cell type, and TNM nodal score. No direct relationship existed between patient age and tumor volume or nodal score. However, there was a significant relationship between patient gender and tumor volume, i.e., smaller volume tumors in female patients (p = .02). Considering all variables, two relational subgroups were identified: younger male patients with large adenocarcinomas and older female patients with small squamous cell carcinomas (p = .05). We conclude that the relationship between tumor volume and age is complex and dependent on patient gender and tumor cell type.