Intracarotid hydroxyethyl methacrylate solution causing stroke in dogs

Hydroxyethyl methacrylate (HEMA) has been advocated as a polymerizing solution with which to prevent deflation of detachable balloons in interventional neuroradiology. It is pertinent to know if unpolymerized HEMA would have untoward effects if accidentally released into the carotid artery by balloon rupture or deflation. Seven mongrel dogs underwent transfemoral catheterization of the common carotid artery and subsequent injection of HEMA solution in volumes of 1 cc in five dogs, 2 cc in one, and 4 cc in one. Angiography performed at the time of injection revealed evidence of intravascular thrombosis as well as possible spasm. Three surviving animals were sacrificed at 48 hours; the brains were fixed and examined histopathologically. One brain was normal and one was autolyzed and could not be examined. Five of the seven animals had histopathologically documented cerebral infarctions of varying size. No foreign substance was seen within the blood vessels to suggest intravascular polymerization. The animals injected with 2 or 4 cc HEMA solution did not survive 48 hours. Literature review reveals little documentation of the toxicology of intravascular HEMA. With its increasing popularity as a compound for polymerization in detachable balloons introduced into the brain, further investigations are warranted to understand the physical properties of the compound and potential risks of its use.     

Scrotal ultrasonography as adjunct to testis biopsy in leukemia

Testicular involvement in acute lymphocytic leukemia is considered an indicator of extramedullary relapse following chemotherapy. Biopsy of the testes prior to the cessation of chemotherapy has yielded early diagnosis and treatment of relapse, with an improved prognosis. Scrotal ultrasonography successfully guided the biopsy of palpably normal testes in a boy with acute lymphocytic leukemia. This success suggests that ultrasound may be a useful adjunct in localizing occult testicular leukemia prior to biopsy.     

A clinically applicable method to preserve urine and bladder washing cells for flow cytometric monitoring of bladder cancer patients

We describe a method to fix exfoliated bladder cells that is suitable for followup of bladder cancer patients by deoxyribonucleic acid flow cytometry. After fixation with room temperature methanol plus acetic acid (20:1, volume:volume) urine and bladder washing samples from these patients can be stored at room temperature for 3 to 7 days and then assessed reliably for the presence of aneuploidy and the percentage of hyperdiploid cells. For those with active transitional cell carcinoma diagnostic accuracy comparing fresh to fixed specimens was improved from 58 to 92% with urine and from 50 to 100% with washing samples. For patients with a history of transitional cell carcinoma who currently are free of disease the false positive rate remains unchanged after fixation. The procedure described is suitable for use in the outpatient clinic and should permit shipping of samples without refrigeration to a central flow cytometry facility for analysis.     

Evaluation of hypothesis testing for comparing two populations using NONMEM analysis.

In a simulation study of inference on population pharmacokinetic parameters, two methods of performing tests of hypotheses comparing two populations using NONMEM were evaluated. These two methods are the test based upon 95% confidence intervals and the likelihood ratio test. Data were simulated according to a monoexponential model and, in that context, power curves for each test were generated for (i) the ratio of mean clearance and (ii) the ratio of the population standard deviations of clearance. To generate the power curves, a range of these parameters was employed; other pharmacokinetic parameters were selected to reflect the variability typically present in a Phase II clinical trial. For tests comparing the means, the confidence interval tests had approximately the same power as the likelihood ratio tests and were consistently more faithful to the nominal level of significance. For comparison of the standard deviations, and when the volume of information available was relatively small, however, the likelihood ratio test was more able to detect differences between the two groups. These results were then compared to results on parameter estimation in order to gain insight into the question of power. As an example, the nonnormality of estimates of the ratio of standard deviations plays an important role in explaining the low power for the confidence interval tests. We conclude that, except for the situation of modeling standard deviations with only sparse information, NONMEM produces tests of significance that are effective at detecting clinically significant differences between two populations.