Where is the vitamin D receptor?

The vitamin D receptor (VDR) is a member of the nuclear receptor superfamily and plays a central role in the biological actions of vitamin D. VDR regulates the expression of numerous genes involved in calcium/phosphate homeostasis, cellular proliferation and differentiation, and immune response, largely in a ligand-dependent manner. To understand the global function of the vitamin D system in physiopathological processes, great effort has been devoted to the detection of VDR in various tissues and cells, many of which have been identified as vitamin D targets. This review focuses on the tissue- and cell type-specific distribution of VDR throughout the body.     

What is river health?

1. Traditionally the assessment of river water quality has been based solely on the measurement of physical, chemical and some biological characteristics. While these measurements may be efficient for regulating effluent discharges and protecting humans, they are not very useful for large-scale management of catchments or for assessing whether river ecosystems are being protected. 2. Measurements of aquatic biota, to identify structural or functional integrity of ecosystems, have recently gained acceptance for river assessment. Empirical evidence from studies of river ecosystems under stress suggests that a small group of biological ecosystem-level indicators can assess river condition. However, physical and chemical features of the environment affect these indicators, the structure and function of which may be changed by human activities. 3. The term ‘river health’, applied to the assessment of river condition, is often seen as being analogous with human health, giving many a sense of understanding. Unfortunately, the meaning of ‘river health’ remains obscure. It is not clear what aspects of river health sets of ecosystem-level indicators actually identify, nor how physical, chemical and biological characteristics may be integrated into measures rather than just observations of cause and effect. 4. Increased examination of relationships between environmental variables that affect aquatic biota, such as habitat structure, flow regime, energy sources, water quality and biotic interactions and biological condition, are required in the study of river health.     

What is optimal about motor control?

This article poses a controversial question: is optimal control theory useful for understanding motor behavior or is it a misdirection? This question is becoming acute as people start to conflate internal models in motor control and perception (Poeppel et?al., 2008; Hickok et?al., 2011). However, the forward models in motor control are not the generative models used in perceptual inference. This Perspective tries to highlight the differences between internal models in motor control and perception and asks whether optimal control is the right way to think about things. The issues considered here may have broader implications for optimal decision theory and Bayesian approaches to learning and behavior in general.     

Vitamin D and autoimmunity: is vitamin D status an environmental factor affecting autoimmune disease prevalence?

The environment in which the encounter of antigen with the immune system occurs determines whether tolerance, infectious immunity, or autoimmunity results. Geographical areas with low supplies of vitamin D (for example Scandinavia) correlate with regions with high incidences of multiple sclerosis, arthritis, and diabetes. The active form of vitamin D has been shown to suppress the development of autoimmunity in experimental animal models. Furthermore, vitamin D deficiency increases the severity of at least experimental autoimmune encephalomyelitis (mouse multiple sclerosis). Targets for vitamin D in the immune system have been identified, and the mechanisms of vitamin D-mediated immunoregulation are beginning to be understood. This review discusses the possibility that vitamin D status is an environmental factor, which by shaping the immune system affects the prevalence rate for autoimmune diseases such as multiple sclerosis, arthritis, and juvenile diabetes.     

An evaluation of the vitamin D3 content in fish: Is the vitamin D content adequate to satisfy the dietary requirement for vitamin D?

It has been suggested that the major source of vitamin D should come from dietary sources and not sun exposure. However, the major fortified dietary source of vitamin D is milk which often does not contain at least 80% of what is stated on the label. Fish has been touted as an excellent source of vitamin D especially oily fish including salmon and mackerel. Little is known about the effect of various cooking conditions on the vitamin D content in fish. We initiated a study and evaluated the vitamin D content in several species of fish and also evaluated the effect of baking and frying on the vitamin D content. Surprisingly, farmed salmon had approximately 25% of the vitamin D content as wild salmon had. The vitamin D content in fish varied widely even within species. These data suggest that the tables that list the vitamin D content are out-of-date and need to be re-evaluated.     

Creatine supplementation in health and disease: What is the evidence for long-term efficacy?

Creatine supplementation is an established ergogenic aid in sports and is now claimed to have therapeutical applications in a variety of diseases. The available literature mainly covers the short-term (one to several weeks) effects of creatine supplementation on skeletal muscle function in health and disease, which is of little help to evaluate the long-term (two or more months) potential of creatine as a drug in chronic disorders, such as neurodegenerative diseases or muscular dystrophies. Recent findings in healthy humans indicate that the beneficial effect on muscle function and muscle total creatine content may disappear when creatine is continuously ingested for more than two or three months. The mechanism for this habituation to chronic creatine exposure is poorly understood. The primary purpose of the present review article is to critically evaluate the available evidence for long-term efficacy of creatine administration and to hypothesize about ways to optimize creatine administration regimens.     

What is the status of reaction-diffusion theory thirty-four years after Turing?

Physicochemical explanations of phenomena are divisible into three classes: structure, equilibrium and kinetics. For the phenomena of biological development, many physical scientists have the preconception that the explanations must turn out to be principally kinetic. In this class of theory, reaction-diffusion is by far the most extensively developed, and is worthy of attention both for its own sake and because many of its features well exemplify the nature of the broader field of kinetic theory. Reaction-diffusion should be thought of as a class, rather than a species, of theory. This review addresses three aspects: first, the general nature of the two-morphogen interaction as first proposed by Turing and incorporated in many later models; second, the specifics of these later models and their probable relative scope; third, the current state of attempts to identify the chemical nature of morphogens. It is concluded that reaction-diffusion in particular, and kinetic theory in general, are now slowly emerging from the almost total neglect by biologists which reaction-diffusion suffered for its first 20 years.     

What is mzXML good for?

mzXML (extensible markup language) is one of the pioneering data formats for mass spectrometry-based proteomics data collection. It is an open data format that has benefited and evolved as a result of the input of many groups, and it continues to evolve. Due to its dynamic history, its structure, purpose and applicability have all changed with time, meaning that groups that have looked at the standard at different points during its evolution have differing impressions of the usefulness of mzXML. In discussing mzXML, it is important to understand what mzXML is not. First, mzXML does not capture the raw data. Second, mzXML is not sufficient for regulatory submission. Third, mzXML is not optimized for computation and, finally, mzXML does not capture the experiment design. In general, it is the authors' opinion that XML is not a panacea for bioinformatics or a substitute for good data representation, and groups that want to use mzXML (or other XML-based representations) directly for data storage or computation will encounter performance and scalability problems. With these limitations in mind, the authors conclude that mzXML is, nonetheless, an indispensable data exchange format for proteomics.     

What is the future for cord blood stem cells?

Stem and progenitor cells are present in cord blood at a high frequency making these cells a major target population for experimental and clinical studies. Over the past decade there has been considerable developments in cord blood research and transplantation but despite the rapid progress many problems remain. The initial hope that cord blood would be an alternative source of haemopoietic cells for transplantation has been tempered by the fact that there are insufficient cells in most cord blood collections to engraft an adult of average weight. In attempts to increase the cell number, a plethora of techniques for ex-vivo expansion have been developed.These techniques have also proved useful for gene therapy. As cord blood cells possess unique properties this allows them to be utilised as suitable vehicles for gene therapy and long-term engraftment of transduced cells has been achieved. Current work examining the nature of the stem cells present in this haematological source indicates that cord blood contains not only haemopoietic stem cells but also primitive non-haemopoietic cells with high proliferative and developmental potential. As attention focuses on stem cell biology and the controversies surrounding the potential use of embryonic stem cells in treatment of disease, the properties of stem cells from other sources including cord blood are being re-appraised. The purpose of this article is to review some of the current areas of work and highlight biological problems associated with the use of cord blood cells. This revised version was published online in July 2006 with corrections to the Cover Date.     

What is the Best Elective Operation for Duodenal Ulcer?

During the past 40 years, after gastroenterostomy and pyloroplasty for duodenal ulcer had been replaced by partial gastrectomy in many centres, partial gastrectomy itself gave way to combinations of vagotomy with gastroenterostomy, pyloroplasty or antrectomy. Opinions differ concerning the procedure of choice and in this paper the author examines the causes of this diversity of opinion and assesses the reliability of conclusions that can be drawn about the elective treatment of duodenal ulcer today. Most reports of results from various operations have come from retrospective studies, and the causes of variability among such reports are analyzed to point out the great difficulty in making a valid judgment about the relative worth of the various operations used to treat duodenal ulcer. Results of some of the few prospective studies with randomized operations assessed blindly are then presented and note is taken of the surprising observation that greatly different operations appear to give remarkably similar results. From the data available the author develops a logical way of approaching the choice of operation for the various problems related to duodenal ulcer that require elective surgical treatment.