Our case-control study of the relation between estrogen use and endometrial cancer involved 451 cases and 888 controls. The overall risk of endometrial carcinoma was sixfold for estrogen users as compared with nonusers; long-term users (greater than five years) had a 15-fold risk. Excess risk was present for both diethylstilberstrol and conjugated estrogens. The risk associated with cyclic use was as great as that for continuous use. Increased risk was associated with estrogen use for all histologic grades of the tumor. The risk of advanced-stage carcinoma was fourfold for estrogen users, but rhe confidence interval was wide, and this question requires further study. Finally, this investigation contradicts the speculation that the association between this cancer and estrogen use can be explained by swifter diagnosis for estrogen users, misclassification of estrogen-related hyperplasia or treatment of early symptoms of the tumor with estrogen.

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The Latin American Society of Nephrology and Arterial Hypertension's Dialysis and Transplant Registry was chartered in 1991. It collects information on ESRD and its treatment in 20 countries of the region. The prevalence of patients on renal replacement therapy (RRT) increased from 129 pmp in 1992 to 447 pmp in 2004; in 2004, 56% of the patients were on hemodialysis, 23% on peritoneal dialysis, and 21% had a functioning kidney graft. The highest rates of prevalence were reported in Puerto Rico (1027 pmp), Chile (686 pmp), and Uruguay (683 pmp). Hemodialysis was widely used, except in El Salvador, Mexico, Guatemala, Nicaragua, and the Dominican Republic, where peritoneal dialysis predominated. Incidence rate increased from 27.8 pmp to 147 pmp in the same period of observation; the lowest rate was reported in Guatemala (11.4 pmp) and the highest in Puerto Rico (337.4 pmp). Diabetes mellitus was the leading cause of renal failure in incident patients; the highest rates were reported in Puerto Rico (62.2%) and Mexico (60%). Forty-four percent of the incident population were older than 65 years. Access to renal replacement therapy was universal in Argentina, Brazil, Chile, Cuba, Puerto Rico, Uruguay, and Venezuela, while was restricted in other countries. Main causes of death in dialysis were cardiovascular (44%) and infectious disease (26%). The rate of renal transplantation increased from 3.7 pmp in 1987 to 14.5 in 2004; fifty-three percent of the organs came from cadavers. Overall, donation rate was 5.9 pmp. In conclusion, the prevalence and incidence rates have increased over the years, and diabetes mellitus has emerged as the leading cause of kidney disease in the region. Although the rate of kidney transplantation has increased, the number remains insufficient to match the growing demand. The implementation of renal health programs in the region is urgently needed.

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The purpose of our study was to evaluate the performance and clinical usefulness of an automated injector system (AIS) that administers an automated injection for ictal SPECT after calculating the volume of tracer to be injected over time. Methods: To test the AIS, repeated injections were performed at different times after tracer preparation. The clinical study consisted of 56 patients with drug-resistant, complex partial seizures. Tracer for ictal SPECT was injected using automated injection in 27 patients and manual injection (MI) in the remaining 29. Injection time (T I ) was measured in seconds from seizure onset to the end of volume injection. The SISCOM (Subtraction Ictal Spect Co-registered to MRI) procedure was used to locate the epileptogenic seizure focus with SPECT. The definition of seizure focus was made by consensus of the epilepsy unit using conventional diagnostic methods. Results: During the experimental phase, there were no system failures, and the error in injected doses when using automated injection was lower than with MI. During the clinical phase, T I using manual injection was 41 s with a range of 14-103 s, compared with an AIS average of 33 s with a range of 19-63 s (P , 0.05). Ictal SPECT and SISCOM successfully localized the seizure focus in 21 of the 27 patients (78%) by AIS and in 19 of the 29 patients (65%) by MI (P 5 0.14). Furthermore, nursing staff found the AIS method more convenient than the MI method. Conclusion: An AIS can improve the quality of work of the nursing staff in the neurology ward and allow a finer adjustment of the injection dose. Early results using an AIS would indicate a reduction in injection time and improved SPECT accuracy.

Partially crystalline Si3N4, with nanosized crystals and a specific surface area greater than 200 m2/g, is obtained by pyrolysis of a commercially available vinylic polysilane in a stream of anhydrous NH3 to 1000°C. This polymer does not contain N initially. Crystallization to high-purity wSi3N4 proceeds with additional heating above 1400°C under Nz. The changes in crystallinity, powder morphology, infrared spectra, and elemental compositions, for samples annealed from 1000" to 1600°C under N,, are consistent with an amorpbous-to-crystalline transformation. Although macroscopic consolidation and local densification occur at 1400"C, volatilization and accompanying weight loss limit bulk densification. The effect of temperature on specific surface area is examined and related to the sintering process. These results are applicable to pyrolysis, decomposition, and crystallization studies of ceramics synthesized by polymeric precursor routes. [Key words: silicon nitride, precursor, polymer, pyrolysis, surface area.]

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