Changes in chromatin structure during processing of wax-embedded tissue sections

The use of immunofluorescence (IF) and fluorescence in situ hybridisation (FISH) underpins much of our understanding of how chromatin is organised in the nucleus. However, there has only recently been an appreciation that these types of study need to move away from cells grown in culture and towards an investigation of nuclear organisation in cells in situ in their normal tissue architecture. Such analyses, however, especially of archival clinical samples, often requires use of formalin-fixed paraffin wax-embedded tissue sections which need addition steps of processing prior to IF or FISH. Here we quantify the changes in nuclear and chromatin structure that may be caused by these additional processing steps. Treatments, especially the microwaving to reverse fixation, do significantly alter nuclear architecture and chromatin texture, and these must be considered when inferring the original organisation of the nucleus from data collected from wax-embedded tissue sections

Preservation of large-scale chromatin structure in FISH experiments

The nuclear organization of specific endogenous chromatin regions can be investigated only by fluorescence in situ hybridization (FISH). One of the two fixation procedures is typically applied: (1) buffered formaldehyde or (2) hypotonic shock with methanol acetic acid fixation followed by dropping of nuclei on glass slides and air drying. In this study, we compared the effects of these two procedures and some variations on nuclear morphology and on FISH signals. We analyzed mouse erythroleukemia and mouse embryonic stem cells because their clusters of subcentromeric heterochromatin provide an easy means to assess preservation of chromatin. Qualitative and quantitative analyses revealed that formaldehyde fixation provided good preservation of large-scale chromatin structures, while classical methanol acetic acid fixation after hypotonic treatment severely impaired nuclear shape and led to disruption of chromosome territories, heterochromatin structures, and large transgene arrays. Our data show that such preparations do not faithfully reflect in vivo nuclear architecture. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00412-006-0084-2 and is accessible for authorized users

QCD and strongly coupled gauge theories : challenges and perspectives

We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.Peer reviewe

Management of male osteoporosis: report of the UK Consensus Group.

Although osteoporosis is generally regarded as a disease of women, up to 30% of hip fractures and 20% of vertebral fractures occur in men. Risk factors for osteoporotic fractures in men include low body mass index, smoking, high alcohol consumption, corticosteroid therapy, physical inactivity, diseases that predispose to low bone mass, and conditions increasing the risk of falls. The key drugs and diseases that definitely produce a decrease in bone mineral density (BMD) and/or an increase in fracture rate in men are long-term corticosteroid use, hypogonadism, alcoholism and transplantation. Age-related bone loss may be a result of declining renal function, vitamin D deficiency, increased parathyroid hormone levels, low serum testosterone levels, low calcium intake and absorption. Osteoporosis can be diagnosed on the basis of radiological assessments of bone mass, or clinically when it becomes symptomatic. Various biochemical markers have been related to bone loss in healthy and osteoporotic men. Their use as diagnostic tools, however, needs further investigation. A practical approach would be to consider a bone density more than one SD below the age-matched mean value (Z < -1) as an indication for therapy. The treatment options for men with osteoporosis include agents to influence bone resorption or formation and specific therapy for any underlying pathological condition. Testosterone treatment increases BMD in hypogonadal men, and is most effective in those whose epiphyses have not closed completely. Bisphosphonates are the treatment of choice in idiopathic osteoporosis, with sodium fluoride and anabolic steroids to be used as alternatives