B‐cell Acute Lymphoblastic Leukemia (B‐ALL) is the most common pediatric cancer, arising most often in children aged 2–5 years. This distinctive age distribution hints at an association between B‐ALL development and disrupted immune system function during a susceptible period during childhood, possibly triggered by early exposure to infection. While cure rates for childhood B‐ALL surpass 90% in high‐income nations, survivors suffer from diminished quality of life due to the side effects of treatment. Consequently, understanding the origins and evolution of B‐ALL, (...) and how to prevent this prevalent childhood cancer, is paramount to alleviate this substantial health burden. This article provides an overview of our current understanding of the etiology of childhood B‐ALL and explores how this knowledge can inform preventive strategies. (shrink)

B‐cell acute lymphoblastic leukaemia (B‐ALL) is a clonal malignant disease originated in a single cell and characterized by the accumulation of blast cells that are phenotypically reminiscent of normal stages of B‐cell differentiation. B‐ALL origin has been a subject of continuing discussion, given the fact that human disease is diagnosed at late stages and cannot be monitored during its natural evolution from its cell of origin, although most B‐ALLs probably start off with chromosomal changes in haematopoietic stem cells. (...) However, the cells responsible for maintaining the disease appear to differ between the different types of B‐ALLs and this remains an intriguing and exciting topic of research, since these cells have been posited to be responsible for resistance to conventional therapies, recurrence and dissemination. During the last years this problem has been addressed primarily by transplantation of purified subpopulations of human B‐ALL cells into immunodeficient mice. The results from these different reconstitution experiments and their interpretations are compared in this review in the context of normal B‐cell developmental plasticity. While the results from different research groups might appear mutually exclusive, we discuss how they could be reconciled with the biology of normal B‐cells and propose research avenues for addressing these issues in the future. (shrink)

The transcription factor Pax5 is essential for the initial commitment of hematopoietic progenitors to the B cell lineage. Recently, our understanding of the lineage commitment process has been extended with the finding that Pax5 is also continuously required throughout B cell development to reinforce commitment, as inactivation of Pax5 in mature B cells results in their de‐differentiation to a progenitor stage that is capable of multi‐lineage potential.1 The reliance of B cell identity on a single gene is not without (...) its problems as the loss of Pax5 results in B cell malignancies in mouse models and mutation in human PAX5 is the most‐common genetic lesion in acute lymphoblastic leukemia. BioEssays 30:203–207, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

B cell activation is accompanied by metabolic adaptations to meet the increased energetic demands of proliferation. The metabolic composition of the microenvironment is known to change during a germinal center response, in inflamed tissue and to vary significantly between different organs. To sustain cellular homeostasis B cells need to be able to dynamically adapt to changes in their environment. An inability to take up and process available nutrients can result in impaired B cell growth and a diminished humoral immune (...) response. Furthermore, the metabolic microenvironment can affect B cell signaling and provide a means to avoid aberrant proliferation or modulate B cell function. Thus, a better understanding of the intricate interplay between cell signaling and metabolism could provide novel insight into how B cell function is regulated and have implications for the development of vaccines or treatment of autoimmune disorders and B cell derived malignancies. Throughout their lifespan, B cells are exposed to different metabolic environments. Signaling pathways regulating cellular responses to metabolic stress not only help to maintain B cell viability and to facilitate cellular functions but may also play an important role in preventing excessive proliferation and malignant transformation. (shrink)

The apolipoprotein E gene plays an important role in the pathogenesis of Alzheimer's disease , and amyloid plaque comprised mostly of the amyloid-beta peptide ) is one of the major hallmarks of AD. However, the relationship between these two important molecules is poorly understood. We examined how A treatment affects APOE expression in cultured cells and tested the role of the transcription factor NF-B in APOE gene regulation. To delineate NF-B's role, we have characterized a 1098 nucleotide segment containing (...) the 5'-flanking region of the human APOE gene . Sequence analysis of this region suggests the presence of two potential NF-B elements. To demonstrate promoter activity, the region was cloned upstream of a promoterless luciferase gene. This segment was able to drive expression of luciferase in transient transfections of human fetal glial cells. Promoter activity was stimulated twofold by A treatment. Pretreatment with double-stranded DNA decoy oligonucleotides against NF-B reduced A stimulation. Deletion and mutagenetic analyses demonstrated that the distal NF-B element was functional and showed a strong DNA-protein complex band in gel shift analysis, similar to that from control NF-B consensus element. An anti-inflammatory and anti-NF-B drug, sodium salicylate, significantly blocked A-induced APOE promoter function. Our data provide evidence that upregulation of APOE by A in astroglial cells is mediated by an NF-B-element present in the 5'-flanking region of the APOE gene. (shrink)

Stem cell biology is driven by experiment. Its major achievements are striking experimental productions: "immortal" human cell lines from spare embryos (Thomson et al. 1998); embryo-like cells from "reprogrammed" adult skin cells (Takahashi and Yamanaka 2006); muscle, blood and nerve tissue generated from stem cells in culture (Lanza et al. 2009, and references therein). Well-confirmed theories are not so prominent, though stem cell biologists do propose and test hypotheses at a profligate rate. 1 This paper aims to (...) characterize the role of experiment in stem cell biology, so as to answer the following question: how do experiments contribute to our knowledge of stem cells and related phenomena? The .. (shrink)

It is common to account for our senses on the basis of our sensory organs. One way of glossing why Aristotle famously counted five senses—and why his count became common sense in the West and elsewhere—is because there are five rather obvious organs of sense. In more modern accounts, this organ criterion of the senses has transformed into a neurobiological criterion; that is to say, part of what it means to be a sense is to have an associated organ with (...) appropriate physiological properties. For example, part of the claim that humans have a sense of vision is that we have a non-vestigial organ (the eye) that has cells (photoreceptors) especially sensitive to the properties of electromagnetic radiation. However, the nature of this “organ criterion” is a point of some contention. Is it a sufficient criterion? Necessary? To be called “vision” need the organ mediating it give rise to “visual experiences”? This chapter will consider the neurobiological criterion as it was originally presented in Aristotle and later reconceptualized in 19th-century neurophysiologist Johannes Müller’s “Law of Specific Nerve Energies.” By understanding the role of neurobiology in these accounts, we will be able to explore the deficiencies of contemporary accounts that downplay neurobiology in differentiating the senses. We will consider one of these accounts in detail: Alva Noë’s recent arguments in favor of an enactive approach to perceptual psychology. (shrink)

A continuous spatial automaton is analogous to a cellular automaton, except that the cells form a continuum, as do the possible states of the cells. After an informal mathematical description of spatial automata, we describe in detail a continuous analog of Conway’s “Life,” and show how the automaton can be implemented using the basic operations of field computation.

Entrepreneurs generally lack the marketing capabilities necessary to bring their new product to market. To engage the resources required to do this, they must somehow place a value on the enterprise. However, all of the methods of valuation currently available are based on the use of historical or current revenues, and therefore are not applicable to an entrepreneurial enterprise with a first-time product. In Valuing an Entrepreneurial Enterprise, Audretsch and Link present a valuation method uniquely tailored to emerging technology-based ventures (...) that have no revenue history to lean on. Unlike many traditional methods, theirs does not take into account the track record of companies and products similar to that being valuated. Instead, it draws on economic theory to formulate a solution to the problem. The book develops conceptual ground, including trends in entrepreneurship, models of innovation, and the economics of standards and entrepreneurship policy. The authors review the traditional valuation methods and illustrate them numerically with case studies to show how the traditional approach produces an incorrect valuation. The core of the book presents the new methodology and demonstrates how it avoids the pitfalls of past approaches. The authors also show how public policy on technology and infrastructure changes valuations of start-up firms in areas such as stem-cell products and renewable fuels projects. Valuing an Entrepreneurial Enterprise will serve as a valuable resource for advanced students, economists, financial planners, and valuators interested in new valuation methods and the theory behind them, as well as those interested in entrepreneurship. (shrink)

A case study concerning a 27-year-old African American female with sickle cell anemia who requests specific medication is presented. Hospital team members should do their best to treat the patient and form their judgments based on her clinical data and medical and social history.

In lieu of an abstract, here is a brief excerpt of the content:Kennedy Institute of Ethics Journal 14.1 (2004) 97-114 [Access article in PDF] Stem Cell Research in the U.S. after the President's Speech of August 2001 Cynthia B. Cohen On 9 August 2001, in a nationally televised speech, President Bush addressed the contentious question of whether to provide federal funds for human embryonic stem cell research (White House 2001).1 This research involves taking the primordial cells found in embryos (...) and transforming them into certain specialized cells, such as those of the heart, nerves, and muscles, with the ultimate goal of transferring these cells into patients to repair damaged cells and tissues. In his remarks, the President authorized funding for research only on stem cells already harvested from remaining embryos at in vitro fertilization (IVF) centers as of 9 August 2001, the date of the speech. In a "Fact Sheet" about embryonic stem cell research, he added the ethical requirements that (1) the donors of embryos gave informed consent to the derivation of stem cells from their embryos, (2) the embryos were created solely for reproductive purposes, and (3) no financial inducements were given to the embryo donors. The President also prohibited federally funded research on embryonic stem cells derived from embryos after 9 August 2001, as well as the creation of embryos for research purposes and the cloning of human embryos for both reproductive and research purposes. He did not seek to ban the pursuit of embryonic stem cell research with private funds. "This allows us to explore the promise and potential of stem-cell research without crossing a fundamental moral line by providing taxpayer funding that would sanction or encourage further destruction of embryos," the President stated (White House 2001).The President's speech stirred intense controversy. Many applauded the new policy because it allowed some embryonic stem cell research to proceed, thereby raising hope that treatments might be developed for those suffering from such conditions as Parkinson's disease, Alzheimer's disease, and diabetes. Others supported it on grounds that it would discourage the future destruction of embryos in stem cell research. They maintained that although it was wrong to have derived stem cells from embryos, this wrong was no longer remediable and it therefore was justifiable to allow research using such embryos to proceed. Some, however, objected to the new policy because they held that it unduly limited the [End Page 97] number of embryonic stem cells available for federally funded research. Still others opposed it on grounds that it made the federal government complicit in what they took to be the wrongful destruction of human embryos that had taken place prior to 9 August 2001. The President established the President's Council on Bioethics by executive order in November 2001 and charged it, among other tasks, with monitoring stem cell research and recommending guidelines and regulations for biomedical innovations.Questions about the moral status of human embryos have so captured public attention since the President issued his remarks that other significant ethical and policy issues raised about stem cell research inside the Beltway have remained in the shadows. A number of individuals and organizations—legislators, scientists, patient groups, the President's Council on Bioethics, ethicists, religious task forces, and social commentators—have attempted to bring these other issues to legislative and public attention. They also have revisited the more publicly prominent question of what sorts of protections we owe to human embryos. In response, Congress has attempted to address several of these newly emerging issues at hearings and in legislation. I review these efforts, consider developing issues and arguments, and conclude by exploring possible future directions for federal and private sector stem cell policy. The Availability of Embryonic Stem Cell Lines to Federally Funded Researchers President Bush, in developing his stem cell research policy, accepted a distinction between the "derivation" and the "use" of embryos enunciated by the General Counsel of the Department of Health and Human Services toward the end of the Clinton administration. This distinction was adopted to avoid contravening the Dickey-Wicker Amendment (added... (shrink)

Variations in levels of apolipoprotein E have been tied to the risk and progression of Alzheimer's disease . Our group has previously compared and contrasted the promoters of the mouse and human ApoE gene promoter sequences and found notable similarities and significant differences that suggest the importance of the APOE promoter's role in the human disease. We examine here three specific single-nucleotide polymorphisms within the human APOE promoter region, specifically at -491 , -427 , and at -219 upstream from the (...) +1 transcription start site. The -219 and -491 polymorphic variations have significant association with instance of AD, and -491AA has significant risk even when stratified for the APOEepsilon4 allele. We also show significant effects on reporter gene expression in neuronal cell cultures, and, notably, these effects are modified by species origin of the cells. The -491 and -219 polymorphisms may have an interactive effect in addition to any independent activity. DNA-protein interactions differ between each polymorphic state. We propose SP1 and GATA as candidates for regulatory control of the -491 and -219 polymorphic sites. This work's significance lies in drawing connection among APOE promoter polymorphisms' associations with AD to functional promoter activity differences and specific changes in DNA-protein interactions in cell culture-based assays. Taken together, these results suggest that APOE expression levels are a risk factor for AD irrespective of APOEepsilon4 allele status. (shrink)

Le but principal de la conférence est de montrer comment l’hypothèse monadologique explique les rapports entre l’âme et le cerveau.Elle est divisée en trois parties, dont la première expose les faits de la localisation cérébrale des phénomènes psychiques, la deuxième la localisation de ceux-ci dans la conscience elle-même, et la troisième l’explication monadologique des rapports entre l’âme et le cerveau.Dans la première, l’auteur insiste d’abord sur la différence anatomique entre les centres de projection et les centres dassociation dans l’écorce cérébrale, (...) et il énumère ensuite, d’après Flechsig, les régions de celle-ci où se trouvent les centres sensoriels.Dans la deuxième partie, l’auteur montre que tous les contenus de la conscience sont localisés, directement ou indirectement, dans l’espace visuel.Dans la troisième partie, l’auteur démontre d’abord l’impossibilité de la localisation directe des phénomènes psychiques dans l’écorce cérébrale ; il énumère ensuite les difficultés anatomiques et physiologiques du siège simple de l’âme ; et il montre enfin que ces difficultés disparaissent dans l’hypothèse monado- logicrue. (shrink)

Alzheimer's disease is characterized by amyloid-beta peptide -loaded plaques in the brain. Abeta is a cleavage fragment of amyloid-beta protein precursor and over production of APP may lead to amyloidogenesis. The regulatory region of the APP gene contains consensus sites recognized by the transcription factor, specificity protein 1 , which has been shown to be required for the regulation of APP and Abeta. To understand the role of SP1 in APP biogenesis, herein we have characterized the relative distribution and localization (...) of SP1, APP, and Abeta in various brain regions of rodent and primate models using immunohistochemistry. We observed that overall distribution and cellular localization of SP1, APP, and Abeta are similar and neuronal in origin. Their distribution is abundant in various layers of neocortex, but restricted to the Purkinje cell layer of the cerebellum, and the pyramidal cell layer of hippocampus. These findings suggest that overproduction of Abeta in vivo may be associated with transcriptional pathways involving SP1 and the APP gene. (shrink)

: The transplantation of adult human neural stem cells into prenatal non-humans offers an avenue for studying human neural cell development without direct use of human embryos. However, such experiments raise significant ethical concerns about mixing human and nonhuman materials in ways that could result in the development of human-nonhuman chimeras. This paper examines four arguments against such research, the moral taboo, species integrity, "unnaturalness," and human dignity arguments, and finds the last plausible. It argues that the transfer of (...) human brain or retinal stem cells to nonhuman embryos would not result in the development of human-nonhuman chimeras that denigrate human dignity, provided such stem cells are dissociated. The article provides guidelines that set ethical boundaries for conducting such research that are consonant with the requirements of human dignity. (shrink)

In this article, physiological and pathological forms of excitability are studied in a two-dimensional electrical model of excitable cell endowed with a generic inward persistent conductance. Bifurcation analysis of the model is performed as a function of the maximal inward persistent conductance, the input current, or the voltage dependency of the activation function. Several discharge modes are exhibited, including: (1) a basic mode that corresponds to a resting potential and production of action potential; (2) bistability between resting potential and self-sustained (...) spiking; (3) a pacemaker mode of discharge; and (4) bistability between resting potential and plateau potential. These behaviours can be compared to experimentally described physiological and pathological forms of excitability that depend upon inward persistent conductances. In the results obtained, attractors allow for a qualitative description of physiological and pathological states. However, it is not possible to obtain an unambiguous identification of particular ''physiological attractors'' or ''pathological attractors''. In the perspective of the theory of dynamical systems, we suggest that pathological states can be modelled in two different ways, i.e. by bifurcation (as in the present model) or by perturbation. We also highlight some other theoretical concepts that may be relevant to a theoretical description of pathology. (shrink)

All species, extant and extinct, from the simplest unicellular prokaryotes to humans, have an existential consciousness. Without sentience, the first cells that emerged some 4 billion years ago would have been evolutionary dead-ends, unable to survive in the chaotic, dangerous environment in which life first appeared and evolved. In this book, Arthur Reber's theory, the Cellular Basis of Consciousness (CBC), is outlined and distinguished from those models that argue that minds could be instantiated on artificial entities and those that (...) maintain consciousness requires a nervous system. The CBC framework takes a novel approach to classic topics such as the origin-of-life, philosophy of mind, the role of genes, the impact of cognition, and how biological information is processed by all species. It also calls for a rethinking of a variety of issues including the moral implications of the sentient capacities of all species, how welfare concerns need to be expanded beyond where they currently are, and critically, how all life is intertwined in a coordinated cognitive ecology. The Sentient Cell explores this revolutionary model, which updates the standard neo-Darwinian framework within which current approaches operate and examines the underlying biomolecular features that are the likely candidates for the "invention" of consciousness and outline their role in cellular life. (shrink)

This article examines the assertion that human embryonic stem cells patents are immoral because they violate human dignity. After analyzing the concept of human dignity and its role in bioethics debates, this article argues that patents on human embryos or totipotent embryonic stem cells violate human dignity, but that patents on pluripotent or multipotent stem cells do not. Since patents on pluripotent or multipotent stem cells may still threaten human dignity by encouraging people to treat embryos (...) as property, patent agencies should carefully monitor and control these patents to ensure that patents are not inadvertently awarded on embryos or totipotent stem cells. (shrink)

A determined division wall positioning in each plant cell with respect to the last formed division wall leads to autoreproductive configurations which can simulate plant-like meristems as such with 2/5 phyllotactic patterns. L-map systems are used to generate the corresponding topological wall nets. But in these patterns cells are not six-sided as mostly found in layers. It is shown that wall staggering cannot be a determinate device of the cell itself, nor a randomized dissociation of the cross walls, but (...) results from a physical control with interaction between adjacent cells. It is independent of the cellular program responsible for the appearance of patterns like 2/5 phyllotaxis which is of a pentameric nature. (shrink)

ABSTRACT One of the most important as well as most awesome achievements of modern biotechnology is the possibility of cloning human embryonic stem cells, if not human beings themselves. The possible revolutionary role of such stem cells in curative, preventive and enhancement medicine has been voiced and chorused around the globe. However, the question of the moral status of embryonic stem cells has not been clearly and unequivocally answered. Taking inspiration from the African adage that ‘the hand (...) that reaches beneath the incubating hen is not guiltless’, I attempt answering this question, from the background of traditional African moral sensibility and sensitivity. I reach the following conclusions. Stem cells in themselves do not have human status and therefore lack moral worth/value. Embryos do have human status and a morally significant line cannot be drawn between human embryos and other human beings. What is morally at stake in stem cell research is therefore the question of the source of derivation or generation of the cells, not of the cells as such. (shrink)

The emergence of individuality during the evolutionary transition from single cells to multicellularity poses a range of problems. A key issue is how variation in lower‐level individuals generates a corporate (collective) entity with Darwinian characteristics. Of central importance to this process is the evolution of a means of collective reproduction, however, the evolution of a means of collective reproduction is not a trivial issue, requiring careful consideration of mechanistic details. Calling upon observations from experiments, we draw attention to proto‐life (...) cycles that emerge via unconventional routes and that transition, in single steps, individuality to higher levels. One such life cycle arises from conflicts among levels of selection and invokes cheats as a primitive germ line: it lays the foundation for collective reproduction, the basis of a self‐policing system, the selective environment for the emergence of development, and hints at a plausible origin for a soma/germ line distinction. (shrink)

Cell therapy means treating diseases with the body's own cells. One of the cell types most in demand for therapeutic purposes is the pancreatic β‐cell. This is because diabetes is one of the major healthcare problems in the world. Diabetes can be treated by islet transplantation but the major limitation is the shortage of organ donors. To overcome the shortfall in donors, alternative sources of pancreatic β‐cells must be found. Potential sources include embryonic or adult stem cells (...) or, from existing β‐cells. There is now a startling new addition to this list of therapies: the pancreatic α‐cell. Thorel and colleagues recently showed that under circumstances of extreme pancreatic β‐cell loss, α‐cells may serve to replenish the insulin‐producing compartment. This conversion of α‐cells to β‐cells represents an example of transdifferentiation. Understanding the molecular basis for transdifferentiation may help to enhance the generation of β‐cells for the treatment of diabetes. (shrink)

Epistemology of science is currently polarized. Descriptive accounts of the social aspects of science coexist uneasily with normative accounts of scientific knowledge. This tension leads students of science to privilege one of these important aspects over the other. I use an episode of recent immunology research to develop an integrative account of scientific inquiry that resolves the tension between sociality and epistemic success. The search for the hematopoietic stem cell by members of Irving Weissman’s laboratory at Stanford University Medical Center (...) exhibits both the goal-oriented character of contemporary immunology and the importance of social interactions in successful achievement of those goals. This episode includes three kinds of epistemic success: characterization of HSC, formation of new interdisciplinary interfaces, and reconciliation of apparently incompatible models. All three depend on coordinating the work of diverse participants via social interactions. Together, they reveal the crucial role of social interactions within and between research groups in producing epistemic success. These features of the search for the HSC generalize to immunology as a whole, and plausibly to other disciplines. This account thus resolves the polarizing tension in epistemology of science, and complements individualistic accounts of scientific knowledge and rationality. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Future Directions for Oversight of Stem Cell Research in the United StatesCynthia B. Cohen (bio) and Mary A. Majumder (bio)Human pluripotent stem cell research, meaning research into cells that can multiply indefinitely and differentiate into almost all the cells of the body, has become a minefield in which science, ethics, and politics have collided over the last decade in the United States. President Barack Obama entered this (...) highly charged territory when he indicated during his campaign that once in office he would issue an executive order expanding federally funded human embryonic stem cell (hESC) research and introduce rigorous oversight of it (Obama 2008a & b). Candidate Obama stated that he would require that the hESC lines involved were derived with donor consent from early embryos that otherwise would be discarded following in vitro fertilization (IVF) treatment. However, in contrast with the policy of President George W. Bush, he would do so without regard to the date of their derivation. He added that he would call upon the director of the National Institutes of Health (NIH) to develop guidelines for federally funded hESC and other pluripotent stem cell research that would draw from the guidelines developed in 2005 by the National Academies of Science (NAS) for privately funded research (National Research Council 2005).A similar policy was written into the 2008 version of the Stem Cell Research Enhancement Act, which reiterates the policy enunciated in earlier versions of this bill, passed twice by the Congress but vetoed by President Bush each time (House of Representatives, 110th Congress 2008).1 Depending on how one reads the 2008 version of the act, it could also apply in certain respects to hESC research that is not federally funded. We proceed on the assumption that the act applies at least to federally funded stem cell research. Therefore, it appears that the president or the Congress, or both, will approve of an expanded policy of federal funding of hESC research, as well as other forms of human pluripotent stem cell research. [End Page 79]This policy would make the guidelines developed by a committee appointed by NAS, a prestigious private body of American scientists and related experts, the primary basis for the development of new federal guidelines for oversight of hESC research in the United States. This would have certain advantages in that those familiar with the relevant scientific issues are likely to address them accurately and stem cell investigators are apt to accept restrictions on their research written by fellow scientists and ethics and policy experts whom they perceive as strong supporters of stem cell research. However, it also would have certain disadvantages. Chief among these is that the NAS committee appointed to write guidelines for this research, in its concern to see stem cell science move forward after a period in which many scientists and others maintained that it had been unduly restricted, might have overlooked or deferred consideration of some pressing ethical and policy issues. We maintain that this is the case—although we also maintain that the NAS guidelines provide a responsible foundation for developing NIH guidelines for stem cell research. Consequently, we propose that an NIH task force charged by the director of NIH with writing new guidelines for hESC and other stem cell research should revise and expand the NAS guidelines in ways that we propose below, as well as others that it considers necessary, and make it obligatory for those seeking federal funding of such research to follow these new guidelines.We highlight certain areas in which an ethical case can be made for strengthening the existing NAS guidelines and certain areas in which more fundamental ethical reflection—and building on that, additional guideline/policy development—seems warranted. Among the sections of the NAS guidelines that need clarification and reworking, we include those regarding consent to embryo donation, which provide one of their central focuses, and the development of human-nonhuman chimeras, which they address relatively briefly. In addition, we maintain that new guidelines need to be written to address the nascent ethical and policy issues raised by the possibility that human gametes will be induced from pluripotent stem cells in the next few years and that... (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Future Directions for Oversight of Stem Cell Research in the United States: An UpdateMary A. Majumder (bio) and Cynthia B. Cohen (bio)On 9 March 2009, President Barack Obama (2009a) signed an executive order revoking the statement issued by President George W. Bush during a televised speech in August 2001, in which the latter had sharply restricted the scope of federally funded human embryonic stem cell (hESC) research to cell (...) lines derived (without federal funding) prior to 9:00 P.M. EDT on 9 August 2001. Action by President Obama to remove the cut-off date had been expected. It came as a surprise, however, that he gave authority to determine the scope of eligible research to the Director of the National Institutes of Health (NIH), referencing only general concerns of responsibility, scientific worth, and legality.1 This contrasted not only with the approach of former President Bush, but also with that of former President Clinton, who had expressed personal opposition to the creation of embryos for research and had a distinction between hESCs derived from embryos created for research and those derived from spare embryos enshrined in NIH policy.President Obama’s remarks upon signing the executive order give some insight into the thinking behind his approach. Implicit in them are the views that earlystage human embryos outside the womb do not have full moral status and that the destruction of human embryos in the effort to care for and ease the suffering of human beings who do have full moral status does not devalue human life. The President also stressed that the decision to pursue hESC research reflected not only his opinion, but also a broad social consensus. He concluded with strong ethical commitments on two fronts:We will develop strict guidelines, which we will rigorously enforce, because we cannot ever tolerate misuse or abuse. And we will ensure that our government never opens the door to the use of cloning for human reproduction. It is dangerous, profoundly wrong, and has no place in our society, or any society.(Obama 2009b)The specific guarantee that President Obama gave against government support for the development of cloning techniques for human reproductive purposes made his silence on the use of cloning for research seem significant. Comments he had made in the course of the campaign (Obama 2008) suggested that he would affirm [End Page 195] the Clinton-era policy of limiting federal funding to hESCs derived from spare embryos. Did this silence mean that President Obama was opening the door to federal funding of research cloning when and if scientists might manage that feat?2009 NIH GuidelinesThe answer to this question and several others came on 17 April, when Raynard Kington, the acting director of NIH, released Draft NIH Guidelines for Human Stem Cell Research (NIH 2009), developed by an NIH Stem Cell Task Force, along with a request for public comment within 30 days of their publication in the Federal Register.2 The 2009 Draft Guidelines exclude from federal funding the derivation of hESCs, a restriction mandated by the reenactment of the Dickey-Wicker Amendment as part of the 2009 Omnibus Appropriations Act (Public Law 111-8, Division F, Title V, § 509). The 2009 Draft Guidelines also exclude the use of hESCs derived from embryos created for research purposes, and so represent a refusal to open the funding door as broadly as the NIH interpretation of the Dickey-Wicker Amendment might allow, at least for the time being.It appears that the drafters used as their starting point the 2000 NIH Guidelines for Research Using Human Pluripotent Stem Cells (NIH 2000) dating from the Clinton Administration, rather than more recent guidelines from the National Academy of Sciences (National Research Council 2005; 2007; 2008) and other private bodies. Both the format and content of the 2000 and 2009 NIH efforts are similar, making the departures in the latter stand out in high relief. We highlight departures related to informed consent to embryo donation, creation of human-nonhuman chimeras, and the role of an NIH task force, updating our original comment (Cohen and Majumder 2009).Informed Consent to Embryo DonationThe 2009 NIH Draft Guidelines require that certain statements... (shrink)

Insulin is synthesized in pancreatic B‐cells of islets of Langerhans. Understanding the mechanisms of action of B‐cytotoxins on pancreatic islets seems to be important for elucidating not only the causes of diabetes mellitus but also its prevention.

Recent findings in several organ systems show that cytoneme‐mediated signaling transports signaling proteins along cellular extensions and targets cell‐to‐cell exchanges to synaptic contacts. This mechanism of paracrine signaling may be a general one that is used by many (or all) cell types in many (or all) organs. We briefly review these findings in this perspective. We also describe the properties of several signaling systems that have previously been interpreted to support a passive diffusion mechanism of signaling protein dispersion, but can (...) now be understood in the context of the cytoneme mechanism.Also watch the Video Abstract. (shrink)

Persons with serious and disabling medical conditions have traveled abroad in search of stem cell treatments in recent years. However, weak or nonexistent oversight systems in some countries provide insufficient patient protections against unproven stem cell treatments, raising concerns about exposure to harm and exploitation. The present article, the first of two, describes and analyzes stem cell tourism in Russia and India and addresses several scientific/medical, ethical, and policy issues raised by the provision of unproven stem cell-based treatments within them. (...) The distinction between treatment based on proven clinical research and "innovative treatment" is addressed and the authors conclude that the innovations at issue constitute neither. Regulatory measures need to be developed or strengthened in accord with internationally accepted standards in such countries to protect those seeking stem cell treatments. (shrink)

Clinics and hospitals around the globe are offering stem cell treatments to persons with serious conditions for whom no effective therapies are available in their home countries. Many of these treatments, which are touted as cures for such conditions as Parkinson's and Alzheimer's Diseases, multiple sclerosis, and spinal cord injuries, have not gone through clinical trials that establish their safety and efficacy. Indeed, it is unclear whether some of them even utilize stem cells. State regulation of these therapies tends (...) to be weak or nonexistent in some of the countries in which they are offered. This puts those who believe they must travel abroad for stem cell treatments at risk of injury from procedures that .. (shrink)

If stem cell-based therapies are developed, we will likely confront a difficult problem of justice: for biological reasons alone, the new therapies might benefit only a limited range of patients. In fact, they might benefit primarily white Americans, thereby exacerbating long-standing differences in health and health care.

Plant reproduction is vital for species survival, and is also central to the production of food for human consumption. Seeds result from the successful fertilization of male and female gametes, but our understanding of the development, differentiation of gamete lineages and fertilization processes in higher plants is limited. Germ cells in animals diverge from somatic cells early in embryo development, whereas plants have distinct vegetative and reproductive phases in which gametes are formed from somatic cells after the (...) plant has made the transition to flowering and the formation of the reproductive organs. Recently, novel insights into the molecular mechanisms underlying male germ‐line initiation and male gamete development in plants have been obtained. Transcriptional repression of male germ‐line genes in non‐male germ‐line cells have been identified as a key mechanism for spatial and temporal control of male germ‐line development. This review focuses on molecular events controlling male germ‐line development especially, on the nature and regulation of gene expression programs operating in male gametes of flowering plants. BioEssays 29:1124–1132, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

Advances in medical technology and information have facilitated clinical practices that favourably affect the success rates of treatment for diseases. Regenerative medicine has been the focus of the recent medical agenda, to the extent of fundamentally changing treatment paradigms. Stem cell practices, their efficacy, and associated ethical concerns have been debated intensively in many countries. Stem cell research is carried out along with the treatment of patients. Thus, various groups affected by the practices inevitably participate in the discussions. In addition (...) to discussions based on avoiding any harm, providing benefits and respecting personal autonomy and justice, problems arise owing to the lack of legal regulations for stem cell research and practice. The dimensions of the problems vary in the developing countries, with widespread use of advanced medical technology but with lack of sources allocated for healthcare, dominance of paternalistic physician–patient relationships and failure to achieve a sufficient level of awareness of patients’ rights. This article discusses the current situation of stem cell practices within the context of regenerative medicine in Turkey and ethical concerns about some of the legal regulations, such as the Regulation for Umblical Cord Blood Banking and Guidelines for Non-embryonic Stem Cell Study for Non-clinical Purposes directing the research on this issue. (shrink)

Mapping the paths that stem and progenitor cells take en route to differentiate and elucidating the underlying molecular controls are key goals in developmental and stem cell biology. However, with population level analyses it is difficult − if not impossible − to define the transition states and lineage trajectory branch points within complex developmental lineages. Single‐cell RNA‐sequencing analysis can discriminate heterogeneity in a population of cells and even identify rare or transient intermediates. In this review, we propose that (...) using these data, one can infer the lineage trajectories of individual stem cells and identify putative branch points. Clonal lineage tracing of stem cells allows one to define the outcome of differentiation. Integrating these single cell‐based approaches provides a robust strategy for establishing and testing models of how an individual stem cell changes through time to differentiate and self‐renew. (shrink)

Here we elucidate a paradox: how a single chemoattractant‐receptor system in two individuals is used for communication despite the seeming inevitability of self‐excitation. In the filamentous fungus Neurospora crassa, genetically identical cells that produce the same chemoattractant fuse via the homing of individual cell protrusions toward each other. This is achieved via a recently described “ping‐pong” pulsatile communication. Using a generic activator‐inhibitor model of excitable behavior, we demonstrate that the pulse exchange can be fully understood in terms of two (...) excitable systems locked into a stable oscillatory pattern of mutual excitation. The most puzzling properties of this communication are the sudden onset of oscillations with final amplitude, and the absence of seemingly inevitable self‐excitation. We show that these properties result directly from both the excitability threshold and refractory period characteristic of excitable systems. Our model suggests possible molecular mechanisms for the ping‐pong communication. (shrink)

Human behavior is the joint product of (i) contingencies of survival responsible for natural selection, and (ii) contingencies of reinforcement responsible for the repertoires of individuals, including (iii) the special contingencies maintained by an evolved social environment. Selection by consequences is a causal mode found only in living things, or in machines made by living things. It was first recognized in natural selection: Reproduction, a first consequence, led to the evolution of cells, organs, and organisms reproducing themselves under increasingly (...) diverse conditions. The behavior functioned well, however, only under conditions similar to those under which it was selected.Reproduction under a wider range of consequences became possible with the evolution of processes through which organisms acquired behavior appropriate to novel environments. One of these, operant conditioning, is a second kind of selection by consequences: New responses could be strengthened by events which followed them. When the selecting consequences are the same, operant conditioning and natural selection work together redundantly. But because a species which quickly acquires behavior appropriate to an environment has less need for an innate repertoire, operant conditioning could replace as well as supplement the natural selection of behavior.Social behavior is within easy range of natural selection, because other members are one of the most stable features of the environment of a species. The human species presumably became more social when its vocal musculature came under operant control. Verbal behavior greatly increased the importance of a third kind of selection by consequences, the evolution of social environments or cultures. The effect on the group, and not the reinforcing consequences for individual members, is responsible for the evolution of culture. (shrink)

The specification of specific and often unique fates to individual cells as a function of their position within a developing organism is a fundamental process during the development of multicellular organisms. The development of the Drosophila embryonic central nervous system serves as an excellent model system in which to clarify the developmental mechanisms that link pattern formation to cell-type specification. The Drosophila embryonic central nervous system develops from a set of neural stem cells termed neuroblasts. Neuroblasts arise from (...) the ectoderm in an invariant pattern, and each neuroblast acquires a unique fate based on its position within this pattern. Two groups of genes recently have been demonstrated to govern the individual fate specification of neuroblasts. One group, the segment polarity genes, enables neuroblasts that develop in different anteroposterior positions to acquire different fates. The second group, referred to as the columnar genes, ensures that neuroblasts that develop in different dorsoventral domains assume different fates. When integrated, the activities of the segment polarity and columnar genes create a Cartesian coordinate system that bestows unique fates to individual neuroblasts as a function of their position of formation within the ectoderm. BioEssays 1999;21:922–931. © 1999 John Wiley & Sons, Inc. (shrink)

Ethics in scientific research has never been more important. Recent controversies over the integrity of data in federally funded science, the manipulation and distortion of privately sponsored research, cloning, stem cell research, and the patenting of DNA and cell lines, illustrate the need for a more thorough education in ethics for researchers at all levels. Now in its second edition, Responsible Conduct of Research provides an introduction to many of the social, ethical, and legal issues facing scientists today. The fully (...) updated volume includes three brand new chapters and additional cases for discussion, as well as analysis of the latest issues and problems in research ethics. Featuring chapters that treat such topics as ethical decision-making, research misconduct, and intellectual property, this new edition will be an indispensable resource for students and teachers, academics and industry professionals alike. (shrink)

This chapter argues that although there are certain limits on how religious bodies and their members should attempt to insert their beliefs into public policy matters, religiously based arguments should, as a matter of principle, be allowed to enter into public debate. This is the case even when many participants in these debates do not accept the premises on which the arguments of religious believers are constructed. The first part of the chapter considers the stances that various religious bodies and (...) commentators have taken publicly regarding embryonic stem cell research and the ways in which they have justified their views in the course of public discussion. It then examines why critics of religious bodies object to the introduction of religious views into public policy debates and offer several responses to these critics, using the responses of religious bodies and thinkers to embryonic stem cell research as examples. Finally, the chapter sets out an alternative view that offers a system for allowing religious bodies to present their views in the public sphere, provided that they follow certain practices that allow fair and open debate. (shrink)

It has long been known that the red blood cell contains a membrane skeleton that stabilizes the plasma membrane, determines its shape, and regulates the lateral distribution of the membrane glyco‐proteins to which it is attached. The way in which these functions are regulated in other cells has not been understood. It has now been shown that platelets also contain a membrane skeleton. In contrast to the membrane skeleton of the red blood cell, the platelet membrane skeleton has actin‐binding (...) protein, not spectrin, as a major component. The platelet membrane skeleton regulates the same cellular functions as the red blood cell membrane skeleton. Other cells may contain a membrane skeleton that is critical to their viability and normal functioning. (shrink)