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This paper reviews current status of the unified approach known as integrated safety assessment (ISA), as well as the associated SCAIS (simulation codes system for ISA) computer platform. These constitute a proposal, which is the result of collaborative action among the Nuclear Safety Council (CSN), University of Madrid (UPM), and NFQ Solutions S.L, aiming to allow independent regulatory verification of industry quantitative risk assessments. The content elaborates on discussions of the classical treatment of time in conventional probabilistic safety assessment (PSA) sequences and states important conclusions that can be used to avoid systematic and unacceptable underestimation of the failure exceedance frequencies. The unified ISA method meets this challenge by coupling deterministic and probabilistic mutual influences. The feasibility of the approach is illustrated with some examples of its application to a real size plant.

Discussions of the ethics involved in allocating scarce resources often proceed without a grounding in factual experience. This study explored whether there was statistical evidence to support the use of set age limits in patient selection criteria for heart transplantation. Many transplant teams have selection criteria that include age limits, excluding patients more than 60 or 65 years of age from being considered as transplant candidates. The hypothesis was made that patients in the age bracket of 60-69 should have a comparable success rate with transplantation to that of younger recipients when selected by using the same medical and psychiatric criteria. Based on their clinical observations, the authors postulated that the elderly would report better quality of life postoperatively than younger control subjects.

The frequency of cocaine use among donors is currently unknown. Cocaine has cardiotoxic effects and could affect the outcome of heart transplantation. To examine the frequency of nonintravenous cocaine use in organ donors and the outcome of heart transplantation with such donors, we retrospectively analyzed the clinical, biopsy, and donor information on 112 consecutive patients who underwent transplantation between December 1988 and August 1993. Ten patients were excluded because of incomplete information regarding the donor's cocaine status. Of the remaining 102 patients, 16 (16%) had a positive donor history for nonintravenous cocaine use (cocaine group) and 86 patients (84%) had a negative history (noncocaine group). Survival, frequency of cellular rejection (grade > or = 1B), and humoral rejection were compared between the two groups. Survival rates at 30 days (100% versus 97% +/- 2%) and at 1 year (93 +/- 7% versus 89 +/- 3%) were similar (p = not significant, cocaine versus noncocaine group). Freedom from rejection was similar at 30 days (81% +/- 10% versus 79% +/- 4% cellular rejection-free, 33% +/- 14% versus 60% +/- 6% humoral-free) and 6 months (34% +/- 12% versus 55% +/- 5% cellular-free, 16% +/- 11% versus 36% +/- 6% humoral-free) (p = not significant). No significant difference was found in donor inotropic support before procurement, ischemic time, length of stay in intensive care unit, or total stay in the hospital. In conclusion, a high incidence of nonintravenous cocaine use exists among donors. The outcome of patients who receive transplanted hearts obtained from nonintravenous cocaine users is favorable, suggesting that the use of such hearts is safe.