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For years, the mechanisms and structural underpinnings of ion selectivity by ion channel proteins have been inferred by indirect experiments. The recently determined structure of a K(+) channel has put flesh on these bones, revealing the coordination chemistry responsible for the unusual combination of high selectivity and high transport rates in ion channels.
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As managed care becomes more and more dominant in U.S. health care, it is coming into conflict with medical education. There are historical reasons for this: medical education traditionally excluded physicians who chose to work in health plans, and for profit managed care has tended to avoid subsidizing medical education. In order to improve the climate, three changes are necessary: medical education must understand the tense history of discord between the two; distinctions must be made between responsible and irresponsible managed care plans; and medical educators should not assume they own the moral high ground. Arrogance, a gross oversupply of physicians and especially specialists, scandals and fraud, an often callous attitude toward the poor, and other sins can be laid at medical education's door. The worse threat for both sides is that the public and payers could simply abandon both, leading to underfunding for health professions education, a society that does not trust its health care system, and the loss of superb teaching organizations. To prevent this, managed care and medical education should work together to solve several difficult problems: how to shrink the medical education infrastructure; how to report honestly the uses to which medical education funds are put; and how to identify and end irresponsible behavior on the part of health plans and medical education entities alike. If the two sides can exercise leadership in these areas, they will be able to protect and enhance the singular place of honor that medical education holds in this society.
The overriding consideration in choosing between soft contact lenses (SCLs) and rigid gas-permeable (RGP) lenses is the severity of the changes each induces in the corneal epithelium, endothelium, and conjunctival structures. Lens-related epithelial changes are largely the consequence of relative oxygen deprivation and consequent corneal edema. Factors such as lower oxygen transmissibility, minimal tear exchange capacity, and large diameters may explain why SCL wearers show a higher rate of corneal infiltrates, sterile ulcers, and irregular staining patterns than users of RGP lenses. The greater association of hydrogels with infectious keratitis may reflect their tendency to accumulate proteinaceous deposits, harbor bacteria in the polymer matrix, and resist easy disinfection. SCL wear has been linked to endothelial polymegethism, a largely irreversible condition that may cause more rapid corneal swelling and slower deswelling after periods of hypoxic stress. Among the conjunctival problems more often seen in SCL wearers are superficial neovascularization, contact lens-related superior limbic keratoconjunctivitis, and giant papillary conjunctivitis. Mechanical irritation from large-diameter lenses, a tendency to build up mucoproteinaceous deposits, corneal draping, and hypersensitivity to preservatives in SCL care products may play a role in these problems.
The use of probiotics, once discussed primarily in the context of alternative medicine, is now entering mainstream medicine. However, only a few of the potential health benefits attributed to probiotics have been confirmed in well-designed, well-conducted, randomized, controlled trials. This is especially true in the pediatric population. We review here the available evidence on efficacy of probiotics in children in the prevention and treatment of gastrointestinal diseases. Although we restrict our analysis to the pediatric age, whenever potentially relevant information is available only from adult studies, they are examined as well. Probiotics have been most extensively studied in the treatment of diarrheal diseases, where their efficacy can be considered well established. Studies documenting effects in other childhood gastrointestinal illnesses are few, although some preliminary results are promising. Furthermore, only a limited number of probiotic strains have been tested, and, as the effects of different probiotic microorganisms are not equivalent, results cannot be generalized. Thus, at present, we have some positive certainties, lots of exciting promises and many unanswered questions.
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In an increasingly competitive medical market-place, one of the authors had observed that women applying for training posts often appear lacking in self-confidence and unclear in decisions concerning their career plans. A successful workshop was held for women training part time which provided a forum for individuals to identify and explore their career dilemmas and an opportunity to make some quantitative assessment of their attitudes. Questionnaires completed by the 22 attenders and a further 16 returned by post showed that the majority of this group had realistically thought out career plans, had resolved the dilemmas posed by combining career and family commitments and were clear that their eventual career goal was to become a Consultant in the National Health Service. A much smaller group of women who tended to be both older and occupying more junior grades emerged as being confused about how the career/children conflict could be resolved and unclear as to their career aims. The oft-stated assumption that 'most women prefer a job with less responsibility than a Consultant' was not supported but it is clear that if women are not to be nudged into career cul-de-sacs they need clear advice and information so that they can complete their training and compete successfully with their male colleagues for career posts.
The discussions of these past twenty years have significantly improved our knowledge about the foundation of bioethics and the meaning of the four bioethical principles with concern to at least three different points: that they are organised hierarchically, and therefore not "prima facie" of the same level; that they have exceptions, and consequently lack of absolute character; and that they are neither strictly deontological nor purely teleological. The only absolute principle of moral life can be the abstract and unconcrete respect of human beings. But when determining the material content of this respect, principles become contingent and relative. Therefore, moral reasoning must have necessarily no less than three moments, one absolute but merely formal, namely respect for all human beings, and the other two relative and material. The first material moment is comprised of the four bioethical principles, divided into two levels, one private, including the principles of autonomy and beneficence, and the other one public, including those of nonmaleficence and justice. The second material moment deals with specific cases, and requires analysis of their context, including their circumstances and consequences. Only when following these steps, and therefore balancing principlism and contextualism, can moral reasoning be correct and complete.