Origin and evolution of the deep thermochemical structure beneath Eurasia

A unique structure in the Earth's lowermost mantle, the Perm Anomaly, was recently identified beneath Eurasia. It seismologically resembles the large low-shear velocity provinces (LLSVPs) under Africa and the Pacific, but is much smaller. This challenges the current understanding of the evolution of the plate–mantle system in which plumes rise from the edges of the two LLSVPs, spatially fixed in time. New models of mantle flow over the last 230 million years reproduce the present-day structure of the lower mantle, and show a Perm-like anomaly. The anomaly formed in isolation within a closed subduction network ∼22,000 km in circumference prior to 150 million years ago before migrating ∼1,500 km westward at an average rate of 1 cm year⁻¹, indicating a greater mobility of deep mantle structures than previously recognized. We hypothesize that the mobile Perm Anomaly could be linked to the Emeishan volcanics, in contrast to the previously proposed Siberian Traps.

The Perm anomaly is found in the lower mantle beneath Eurasia, but how this structure formed has remained unclear. Here, the authors show that the anomaly has been mobile since it formed in isolation within a closed subduction network and propose that the anomaly is linked to the Emeishan volcanics.

Implementation of videoconferencing to support a managed clinical network in Scotland: lessons learned during the first 18 months

Managed clinical networks (MCNs) are usually built on established groups of health professionals from both acute and primary care sectors. We have used videoconferencing to support the gynaecological oncology MCN in the west of Scotland. Videoconferencing was implemented simultaneously at five sites in 2001 and DICOM image-capture software was added in 2003. Videoconferencing and live PC links allowed the multidisciplinary teams to discuss individual cancer diagnoses without the extensive travelling previously required. Our experience of the implementation suggests that local ownership is crucial. In the present project, each of the stakeholders had an important role in the delivery of a successful system. High-quality project management is required during implementation and for some time thereafter to achieve sustainability.

When is the 'right' time to initiate an assessment of a health technology?

There is currently no generally accepted formula for the optimal timing of health technology assessments (HTAs). This paper presents some of the relevant issues and then reviews the existing literature on timing of HTAs. It finds that the literature that specifically addresses these issues is limited. There is a consensus that HTAs should be initiated at an early stage of the development of a new health technology, and repeated during the life cycle of the technology. However, the questions of reliably identifying new technologies at an early stage in their development and of deciding on a detectable critical point for starting evaluation are not resolved. It is proposed that a system of categorization and prioritization of health technologies should be developed to allow decisions to be made as to when a strongly precautionary approach is required and how the limited resources available for HTA could be optimally deployed.

When and how to assess fast-changing technologies: a comparative study of medical applications of four generic technologies

OBJECTIVES. To try to identify the optimal time at which to start assessing new and fast-evolving health technologies. To provide insight into factors influencing the timing of assessments and the choice of methods for assessing new and fast-changing technologies. HOW THE RESEARCH WAS CONDUCTED. A series of literature reviews were undertaken covering the general principles involved in the timing of health technology assessments (HTAs). Additionally, the reported assessments of laparoscopic cholecystectomy, chorionic villus sampling (CVS), teleradiology, teledermatology, genetic screening for predisposition to breast cancer, and gene therapy for cystic fibrosis were reviewed to try to identify the factors that influenced the timing of these assessments. Key individuals in each field were also interviewed. The selected technologies allowed comparison between those that were new and evolving and those that were relatively well-established. A bibliometric study of publication trends was also undertaken to see whether these trends would suggest points in the development of a technology that could be used as indicators that assessment should be started. RESEARCH FINDINGS. TIMING. The precise point at which assessment should start was not identified but the bibliometric study suggested that extending this approach might give useful results. For all health technologies, more regular reporting of outcomes and side-effects should be encouraged during the period after initial assessment and, where the technology is fast-changing, reassessment should take place from time to time. The precise intervals were not identified and the problem remains of deciding when a technology has changed enough to warrant reassessment. FACTORS INFLUENCING TIMING. Published reports of assessments did not generally specify the reasons for their timing, but a number of factors appear to have influenced the timing of those assessments, directly or indirectly. Product champions and opinion leaders pioneer the introduction of new technologies into clinical practice, and their reports may lead to the rapid diffusion of such technologies before they have been adequately evaluated, as was the case with laparoscopic cholecystectomy; this diffusion may limit the methods of evaluation that can then be used. It is therefore important to assess new health technologies before diffusion takes place. The extent to which regulatory control is imposed on the introduction of new health technologies can also influence the timing of assessments. Such controls might have helped to restrict the diffusion of laparoscopic cholecystectomy, making a large and widely generalisable randomised controlled trial (RCT) feasible. The source and availability of funding for studies may influence the nature and timing of trials. Many telemedicine evaluations were funded by commercial telecommunications organisations and were thus restricted in their timing (and biased towards the technological aspects of the applications) by the availability of funds. Media coverage undoubtedly has an influence although this influence is not always predictable; it may generate 'favourable' publicity about new health technologies, which can lead to immediate demands for the new technique, as was the case with laparosocpic cholecystectomy with its apparent benefits. Thus assessments should be made before media coverage exerts popular pressure on purchasers to adopt the technology and dissuades patients from participating in RCTs (because of fear they may be randomised to the standard treatment as occurred in a US trial of CVS). Innovators should also be cautious in the claims that they make to the media.(ABSTRACT TRUNCATED)

US family physicians' experiences with practice guidelines

BACKGROUND

Practice guidelines were developed to improve medical outcomes and cost-effectiveness. The experiences of family physicians, who may need to use multiple guidelines in their practices, are crucial for effective development and implementation of practice guidelines. We surveyed a national sample of US family physicians about factors that affect their adoption and use of practice guidelines.

METHODS

We mailed a structured survey to a national random sample of 400 family physician members of the American Academy of Family Physicians.

RESULTS

The response rate was 51%. Most respondents (69%) reported a positive attitude about practice guidelines, but only 44% reported using any guidelines. More younger physicians thought that guidelines could be useful tools. Most preferred guidelines that could be modified (87%) and that were no longer than two pages. Only 27% of respondents knew where to locate a guideline on a particular topic. Forty-three percent of respondents reported that it would be useful if guidelines were a component of an electronic medical record.

CONCLUSIONS

If guidelines are to be used by practicing family physicians, a generalist perspective needs to be considered in future guideline development and implementation. Younger physicians had more positive attitudes toward guidelines.

The effects of the ALSO course as an educational intervention for residents. Advanced Life Support in Obstetrics

BACKGROUND AND OBJECTIVES

Previous descriptions of the Advanced Life Support in Obstetrics (ALSO) course have indicated increases in physician comfort in managing obstetric emergencies and in their intentions to continue offering maternity care after taking the course. No previous studies have been done about the educational outcomes of the ALSO course on family practice residents. This study compared residents' pre- and post-ALSO course confidence to manage obstetrical emergencies and their intention to provide maternity care when they enter practice.

METHODS

A self-selected group of 55 family practice residents completed questionnaires before and after ALSO training. The questionnaire was designed to measure confidence, using Bandura's model of self efficacy, and future intention, using Ajzen's Theory of Planned Behavior.

RESULTS

Residents' confidence in their abilities to manage obstetrical emergencies increased significantly after the ALSO course. Residents' intent to provide maternity care when the residents enter practice did not change.

CONCLUSIONS

The ALSO course is a valuable teaching intervention that can improve family practice residents' perceived self-confidence in managing obstetric emergencies. The study had sufficient power to detect a moderate effect size of the ALSO course on resident intention to provide maternity care but did not do so.

A descriptive, cross-sectional study of formal mentoring for faculty

BACKGROUND AND OBJECTIVES

Professional academic skills (PAS) encompass the values, collegial relations, and career management skills essential for faculty success. Mentoring has been proposed as a way for junior faculty to acquire these skills. In this paper, we present a summary of literature on formal mentoring and report an evaluation of a formal mentoring program (FMP) on the PAS development of junior family medicine faculty.

METHODS

A descriptive, cross-sectional study was used to examine FMP impact on two groups of junior faculty with 18 months (n = 8) and 6 months (n = 10) of program exposure. We developed a Likert-type questionnaire to assess PAS development and used semistructured interviews to identify unintended outcomes of program participation. A qualitative, template analysis helped surface themes from the descriptive data.

RESULTS

The FMP had an overall positive impact on junior faculty PAS development, with greatest improvements in their understanding of academic values. Proteges with longer program experience had greater gains. Unintended benefits included improved preparation to mentor others and increased perceptions of a supportive academic environment.

CONCLUSIONS

Formal mentoring programs can improve the PAS of junior faculty and positively impact an organizational culture that supports faculty development.

Round atelectasis as a complication of Legionnella pneumonia

Round atelectasis is a rare lung pseudotumor that is most commonly associated with asbestos-related pleural disease but can result from a variety of chronic pleural diseases. We describe a patient who developed round atelectasis over a period of only several months following an acute pleuropulmonary illness caused by Legionnella pneumophila.

Innovation in health care: developments in NHS trusts

Essential parts of the R&D in virtually all UK biomedical innovations are executed within teaching hospitals, which are undergoing major organizational changes as part of the ongoing NHS reforms. Examines the impact of the changing structural and regulatory environment on the process of biomedical innovation management of two groups of technologically novel projects with the NHS. Finds that regulatory changes were tending to centralize and formalize innovation management, but that end users were playing an active role in directing the course of new treatment development. Problems of allocation of R&D resources within teaching hospitals were still unresolved, although some evidence from the London teaching hospitals suggested that hospital managers were able to deal with conflicting demands where they perceived that research excellence could be an asset rather than a cost.

Chromosome organisation in polyploid mouse trophoblast nuclei

At least one-third of mouse trophoblast cells undergo endoreduplication during the first half of gestation. It has been suggested that the endoreduplicated chromosomes may be polytenised. Here it is shown, using in situ hybridisation to the alpha-1 antitrypsin genes, which map at a unique site, that while there is a tendency for duplicated chromosomes to cluster, this does not involve the complete fusion of replicated chromatids found in fully polytene chromosomes, and in a substantial proportion of homologues the sites on the chromosome arms corresponding to these genes are widely separated. The centromeres do not fuse into a single chromocentre but the possibility is not ruled out that individual chromosomes may be polytenised in the centromeric region. Evidence is also presented showing that endoreduplication in trophoblast nuclei is not accompanied by the formation of new prekinetochore structures, in contrast to the situation in polyploid mouse liver and C127 cells.

Characterization of a polypeptide associated with coated vesicles and the cytoskeleton which is recognized by a CREST serum

Serum from an individual with the CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dismotility, sclerodactyly, telangiectasia) reacts not only with kinetochores, but also with a cytoplasmic, phosphorylatable polypeptide, which is shown by immunofluorescence in whole cells and immunoelectronmicroscopy in sections to be associated with actin stress fibres in cultured mammalian cells. The antigen shows some variation in molecular weight between species, estimated by immunoblotting to range from 68 to 76 kD between mouse, Chinese hamster, sheep and human cells. Much of the polypeptide copurifies with coated vesicles, of which approx. 5% bound antibody from the serum, as detected by immunogold electronmicroscopy.

Cellular heterogeneity in the expression of the delta-crystallin gene in non-lens tissue

RNA transcripts of the delta-crystallin genes, which code for the major chicken lens protein, have been detected at low levels in many non-lens tissues. Here it is demonstrated by in situ hybridisation that these transcripts are concentrated at a high level in small, infrequent clusters of cells in many non-lens tissues. While the nuclei of these cells are very heavily labelled, there is only light labelling of the cytoplasm. The unlabelled cells surrounding the labelled clusters are of similar morphology and staining properties as the labelled cells, and all have the characteristic morphology of cells of the embryonic tissue used. With the exception of neural retina, it is not yet known whether the labelled clusters are found in specific locations in the tissues, or whether they arise at random.

Chicken lens delta-crystallin gene expression and methylation in several non-lens tissues

RNA sequences coding for the most abundant chicken lens proteins, delta-crystallin, were detected at very low levels in day old post hatch chick lung, heart, kidney and liver, and in 6 day embryo headless bodies. The pattern of cytosine methylation within the CCGG sequences of the delta-crystallin genes was also examined and shown to vary in several non-lens tissues, from several stages of development. Embryonic neural retina, which expresses a higher level of delta-crystallin RNA than the above tissues, is no less methylated in the sites studied than the tissues which have no association with the eye, and is actually more heavily methylated than the kidney. Thus no obvious correlation was found between undermethylation and gene expression.

The pattern of expression of chick delta-crystallin genes in lens differentiation and in trans-differentiating cultured tissues

During development of the vertebrate lens, the lens epithelium undergoes a final stage of differentiation into lens fibre cells. Lens fibre cells can also be produced by trans-differentiation from certain extralenticular structures, all of which are of different developmental origin from lens, including embryonic neural retina and retinal pigmented epithelium. Delta-crystallin is the major lens protein in the chick and appears first in development; it is the major product in trans-differentiated retina of younger embryos. In both normal differentiation and trans-differentiation an increase of delta-crystallin coding RNA is detectable in the nucleus of cells prior to their terminal differentiation into lens fibres. The increase in transcription of delta-crystallin genes accompanying final differentiation of lens fibres, appears to take place slightly in advance of an increase in the capacity to process and transport this mRNA to the cytoplasm.

Cytoplasmic RNA sequences complementary to cloned chick delta-crystallin cDNA show size heterogeneity

Double-stranded complementary DNA (cDNA) sequences were prepared from day-old chick lens total polysomal RNA and inserted into the unique PstI restriction site of the plasmid pBR322. Colonies containing sequences complementary to abundant lens poly(A)-containing RNA sequences were identified by using lens 32P-labelled cDNA. Some of these clones have been characterized as containing delta-crystallin mRNA coding sequences by genomic DNA blot hybridization and RNA blot hybridizations. Hybridization of labelled DNA from such clones to RNA blots detected four size classes of delta-crystallin RNA sequences, although Southern blots indicated that there are probably only two delta-crystallin genes.

Nonprotein neurotoxins

Nonprotein neurotoxins are continuing to play a major role as molecular probes in studying nervous processes. They also have clinical importance as some of them, such as saxitoxin and its analogues, are the source of public health problems, or have potential use in therapy. This review covers clinical, biological, pharmacological, and chemical aspects of certain nonprotein neurotoxins, with emphasis on three well-known ones: tetrodotoxin, saxitoxin, and batrachotoxin. The distribution of the toxins is discussed as well as their symptomatology, treatment of affected patients, and effects of their structures on their physiological activity. With so many outstanding problems remaining in neuropharmacology, the study of nonprotein neurotoxins thrives as a fertile area of research.