Death and conception. (49/646)

The complex moral, ethical and legal concerns that have arisen as a result of posthumous assisted reproduction (PAR) are examined in this report. Difficult questions such as what constitutes informed consent, and whether it is ethical to retrieve spermatozoa from patients who are in a coma, are considered. Legal issues, such as whether gametes can be considered as property and the need to clarify the legal definition of paternity in cases of children born in such circumstances, are also discussed, while other points regarding the advisability of PAR, respecting the wishes of the deceased donor and the need to protect the interests of the unborn child, are outlined. The motives of the gestating women, viewing their desire for PAR perhaps as part of the grieving process, and the effects on the children concerned are examined; it is concluded that there appears to be no adverse effect, but this finding might be premature. The report also asserts the need for responsible accounting on the part of fertility clinics, and calls for fairness, transparency and patience to help the bereaved reach an unbiased yet informed decision. This may be achieved by offering ample time for informed and support counselling. Finally, consideration should be expressed for the welfare of unborn child, in a balanced, pragmatic and sensible manner.  (+info)

Increased epithelial cell proliferation in very premature baboons with chronic lung disease. (50/646)

Coordinated proliferation of lung cells is required for normal lung growth and differentiation. Chronic injury to developing lung may disrupt normal patterns of cell proliferation. To examine patterns of cell proliferation in injured developing lungs, we investigated premature baboons delivered at 125 days gestation (approximately 67% of term) and treated with oxygen and ventilation for 6, 14, or 21 days (PRN). Each PRN treatment group contained 3 or 4 animals. During normal in utero lung development, the proportion of proliferating lung cells declined as measured by the cell-cycle marker Ki67. In the PRN group, the proportion of proliferating lung cells was 2.5-8.5-fold greater than in corresponding gestational controls. By 14 days of treatment, the proportion of cells that expressed pro-surfactant protein B (proSP-B) was ~2.5-fold greater than in gestational controls. In the PRN group, 41% of proliferating cells expressed proSP-B compared with 5.8% in the gestational controls. By 21 days of treatment, proliferation of proSP-B-expressing epithelial cells declined substantially, but the proportion of proliferating non-proSP-B-expressing cells increased approximately sevenfold. These data show that the development of chronic lung disease is associated with major alterations in normal patterns of lung-cell proliferation.  (+info)

Birth and death of protein domains: a simple model of evolution explains power law behavior. (51/646)

BACKGROUND: Power distributions appear in numerous biological, physical and other contexts, which appear to be fundamentally different. In biology, power laws have been claimed to describe the distributions of the connections of enzymes and metabolites in metabolic networks, the number of interactions partners of a given protein, the number of members in paralogous families, and other quantities. In network analysis, power laws imply evolution of the network with preferential attachment, i.e. a greater likelihood of nodes being added to pre-existing hubs. Exploration of different types of evolutionary models in an attempt to determine which of them lead to power law distributions has the potential of revealing non-trivial aspects of genome evolution. RESULTS: A simple model of evolution of the domain composition of proteomes was developed, with the following elementary processes: i) domain birth (duplication with divergence), ii) death (inactivation and/or deletion), and iii) innovation (emergence from non-coding or non-globular sequences or acquisition via horizontal gene transfer). This formalism can be described as a birth, death and innovation model (BDIM). The formulas for equilibrium frequencies of domain families of different size and the total number of families at equilibrium are derived for a general BDIM. All asymptotics of equilibrium frequencies of domain families possible for the given type of models are found and their appearance depending on model parameters is investigated. It is proved that the power law asymptotics appears if, and only if, the model is balanced, i.e. domain duplication and deletion rates are asymptotically equal up to the second order. It is further proved that any power asymptotic with the degree not equal to -1 can appear only if the hypothesis of independence of the duplication/deletion rates on the size of a domain family is rejected. Specific cases of BDIMs, namely simple, linear, polynomial and rational models, are considered in details and the distributions of the equilibrium frequencies of domain families of different size are determined for each case. We apply the BDIM formalism to the analysis of the domain family size distributions in prokaryotic and eukaryotic proteomes and show an excellent fit between these empirical data and a particular form of the model, the second-order balanced linear BDIM. Calculation of the parameters of these models suggests surprisingly high innovation rates, comparable to the total domain birth (duplication) and elimination rates, particularly for prokaryotic genomes. CONCLUSIONS: We show that a straightforward model of genome evolution, which does not explicitly include selection, is sufficient to explain the observed distributions of domain family sizes, in which power laws appear as asymptotic. However, for the model to be compatible with the data, there has to be a precise balance between domain birth, death and innovation rates, and this is likely to be maintained by selection. The developed approach is oriented at a mathematical description of evolution of domain composition of proteomes, but a simple reformulation could be applied to models of other evolving networks with preferential attachment.  (+info)

Ethics of practicing medical procedures on newly dead and nearly dead patients. (52/646)

OBJECTIVE: To examine the ethical issues raised by physicians performing, for skill development, medically nonindicated invasive medical procedures on newly dead and dying patients. DESIGN: Literature review; issue analysis employing current normative ethical obligations, and evaluation against moral rules and utilitarian assessments manifest in other common perimortem practices. RESULTS: Practicing medical procedures for training purposes is not uncommon among physicians in training. However, empiric information is limited or absent evaluating the effects of this practice on physician competence and ethics, assessing public attitudes toward practicing medical procedures and requirements for consent, and discerning the effects of a consent requirement on physicians' clinical competence. Despite these informational gaps, there is an obligation to secure consent for training activities on newly and nearly dead patients based on contemporary norms for informed consent and family respect. Paradigms of consent-dependent societal benefits elsewhere in health care support our determination that the benefits from physicians practicing procedures does not justify setting aside the informed consent requirement. CONCLUSION: Current ethical norms do not support the practice of using newly and nearly dead patients for training in invasive medical procedures absent prior consent by the patient or contemporaneous surrogate consent. Performing an appropriately consented training procedure is ethically acceptable when done under competent supervision and with appropriate professional decorum. The ethics of training on the newly and nearly dead remains an insufficiently examined area of medical training.  (+info)

ICU Cornestone: a lecture that changed my practice. (53/646)

In 1982, the author attended a lecture by Professor Joseph Civetta dealing with the concept that, at times, the goal of care should be comfort rather than cure, and that inappropriate care prolonged dying and suffering. Efforts to improve end-of-life care subsequent to this had effects on care at a local level and at a state level. Intensive care providers should be leaders in the provision of appropriate and compassionate care at the end of life.  (+info)

Explaining the Pleistocene megafaunal extinctions: models, chronologies, and assumptions. (54/646)

Understanding of the Pleistocene megafaunal extinctions has been advanced recently by the application of simulation models and new developments in geochronological dating. Together these have been used to posit a rapid demise of megafauna due to over-hunting by invading humans. However, we demonstrate that the results of these extinction models are highly sensitive to implicit assumptions concerning the degree of prey naivety to human hunters. In addition, we show that in Greater Australia, where the extinctions occurred well before the end of the last Ice Age (unlike the North American situation), estimates of the duration of coexistence between humans and megafauna remain imprecise. Contrary to recent claims, the existing data do not prove the "blitzkrieg" model of overkill.  (+info)

Acute myelofibrosis in children with Down's syndrome. (55/646)

Two boys with Down's syndrome, recognized at birth, developed acute myelogibrosis at the ages of 19 and 21 months. The disorder presented with anaemia and splenomegaly, and clinically resembled acute leukaemia, but bone marrow histology showed a bizarre pattern with generalized fibrosis, markedly increased reticulin, large reticulum cells, and giant cells resembling megakaryocytes. The children survived 6 and 11 months from diagnosis. A third case is quoted (Hillman and Forrester, 1968) which was also studied at this hospital; the features of all 3 cases are similar. There appears to be an increased incidence of acute myelofibrosis in children with Down's syndrome, which may be a further example of the instability of the haemopoietic system in the disease. In children with Down's syndrome and unusual leukaemia-like illness, histological examination of the bone marrow may be diagnostic.  (+info)

Trends in the place of death of cancer patients, 1992-1997. (56/646)

BACKGROUND: Although many patients with cancer would prefer to die at home, most die in hospital. We carried out a study to describe the yearly trends in the place of death between 1992 and 1997 and to determine predictors of out-of-hospital death for adults with cancer in Nova Scotia. METHODS: In this population-based study, we linked administrative health data from 2 databases - the Nova Scotia Cancer Centre Oncology Patient Information System and the Queen Elizabeth II Health Sciences Centre Palliative Care Program - for all adults in Nova Scotia who died of cancer from 1992 to 1997. We also used grouped neighbourhood income information from the 1996 Canadian census. Death out of hospital was defined as death in any location other than an acute care hospital facility. We used logistic regression analysis to identify the odds of dying out of hospital over time and to identify factors predictive of out-of-hospital death. RESULTS: A total of 14 037 adults died of cancer during the study period. The data for 101 people were excluded because of missing information regarding place of death. Of the remaining 13 936 people, 10 266 (73.7%) died in hospital and 3670 (26.3%) died out of hospital. Over the study period the proportion of people who died out of hospital rose by 52%, from 19.8% (433/2182) in 1992 to 30.2% (713/2359) in 1997. Predictors associated with out-of-hospital death included year of death (for 1997 v. 1992, adjusted odds ratio [OR] 1.8, 95% confidence interval [CI] 1.5-2.0), female sex (adjusted OR 1.2, 95% CI 1.1-1.3), age (for > or = 85 v. 18-44 years, adjusted OR 2.2, 95% CI 1.7-2.8), length of survival (for 61-120 v. < or =60 days, adjusted OR 2.2, 95% CI 1.8-2.6; for 121-180 v. < or =60 days, adjusted OR 2.5, 95% CI 2.2-2.8), having received palliative radiation (adjusted OR 0.8, 95% CI 0.7-0.9) and region of death (Cape Breton v. Halifax, adjusted OR 0.5, 95% CI 0.5-0.6). Among Halifax residents, registration in the Palliative Care Program was also a significant predictor of out-of-hospital death (adjusted OR 1.4, 95% CI 1.2-1.7). Tumour group, neighbourhood income and residence (urban v. rural) were not predictive of out-of-hospital death in multivariate analysis. INTERPRETATION: Over time, more patients with cancer, especially women, elderly people and people with longer survival after diagnosis, died outside of hospital in Nova Scotia.  (+info)