OBJECTIVE

This study reports on sudden cardiac death (SCD) in sport in the literature and aims at achieving a generally acceptable preparticipation screening protocol (PPSP) endorsed by the consensus meeting of the International Olympic Committee (IOC).

BACKGROUND

The sudden death of athletes under 35 years engaged in competitive sports is a well-known occurrence; the incidence is higher in athletes (approximately 2/100,000 per year) than in non-athletes (2.5 : 1), and the cause is cardiovascular in over 90%.

METHODS

A systematic review of the literature identified causes of SCD, sex, age, underlying cardiac disease and the type of sport and PPSP in use. Methods necessary to detect pre-existing cardiac abnormalities are discussed to formulate a PPSP for the Medical Commission of the IOC.

RESULTS

SCD occurred in 1101 (1966-2004) reported cases in athletes under 35 years, 50% had congenital anatomical heart disease and cardiomyopathies and 10% had early-onset atherosclerotic heart disease. Forty percent occurred in athletes under 18 years, 33% under 16 years; the female/male ratio was 1/9. SCD was reported in almost all sports; most frequently involved were soccer (30%), basketball (25%) and running (15%). The PPSP were of varying quality and content. The IOC consensus meeting accepted the proposed Lausanne Recommendations based on this research and expert opinions (http://multimedia.olympic.org/pdf/en_report_886.pdf).

CONCLUSIONS

SCD occurs more frequently in young athletes, even those under the age of 18 years, than expected and is predominantly caused by pre-existing congenital cardiac abnormalities. Premature atherosclerotic disease forms another important cause in these young adults. A generally acceptable PPSP has been achieved by the IOC's acceptance of the Lausanne Recommendations.

DNA microarray analysis was used to analyze the transcriptional profile of HCT116 colorectal cancer cells that were treated with 5-fluorouracil (5-FU) or oxaliplatin and selected for resistance to these agents. Bioinformatic analyses identified sets of genes that were constitutively dysregulated in drug-resistant cells and transiently altered following acute exposure of parental cells to drug. We propose that these genes may represent molecular signatures of sensitivity to 5-FU and oxaliplatin. Using real-time reverse transcription-PCR (RT-PCR), the robustness of our microarray data was shown with a strong overall concordance of expression trends for>> or =82% (oxaliplatin) and>> or =85% (5-FU) of a representative subset of genes. Furthermore, strong correlations between the microarray and real-time RT-PCR measurements of average fold changes in gene expression were observed for both the 5-FU (R(2)>> or = 0.73) and oxaliplatin gene sets (R(2)>> or = 0.63). Functional analysis of three genes identified in the microarray study [prostate-derived factor (PDF), calretinin, and spermidine/spermine N(1)-acetyl transferase (SSAT)] revealed their importance as novel regulators of cytotoxic drug response. These data show the power of this novel microarray-based approach to identify genes which may be important markers of response to treatment and/or targets for therapeutic intervention.

Messenger-RNA-directed protein synthesis is accomplished by the ribosome. In eubacteria, this complex process is initiated by a specialized transfer RNA charged with formylmethionine (tRNA(fMet)). The amino-terminal formylated methionine of all bacterial nascent polypeptides blocks the reactive amino group to prevent unfavourable side-reactions and to enhance the efficiency of translation initiation. The first enzymatic factor that processes nascent chains is peptide deformylase (PDF); it removes this formyl group as polypeptides emerge from the ribosomal tunnel and before the newly synthesized proteins can adopt their native fold, which may bury the N terminus. Next, the N-terminal methionine is excised by methionine aminopeptidase. Bacterial PDFs are metalloproteases sharing a conserved N-terminal catalytic domain. All Gram-negative bacteria, including Escherichia coli, possess class-1 PDFs characterized by a carboxy-terminal alpha-helical extension. Studies focusing on PDF as a target for antibacterial drugs have not revealed the mechanism of its co-translational mode of action despite indications in early work that it co-purifies with ribosomes. Here we provide biochemical evidence that E. coli PDF interacts directly with the ribosome via its C-terminal extension. Crystallographic analysis of the complex between the ribosome-interacting helix of PDF and the ribosome at 3.7 A resolution reveals that the enzyme orients its active site towards the ribosomal tunnel exit for efficient co-translational processing of emerging nascent chains. Furthermore, we have found that the interaction of PDF with the ribosome enhances cell viability. These results provide the structural basis for understanding the coupling between protein synthesis and enzymatic processing of nascent chains, and offer insights into the interplay of PDF with the ribosome-associated chaperone trigger factor.

Molecular circadian clocks are interconnected via neural networks. In Drosophila, PIGMENT-DISPERSING FACTOR (PDF) acts as a master network regulator with dual functions in synchronizing molecular oscillations between disparate PDF(+) and PDF(-) circadian pacemaker neurons and controlling pacemaker neuron output. Yet the mechanisms by which PDF functions are not clear. We demonstrate that genetic inhibition of protein kinase A (PKA) in PDF(-) clock neurons can phenocopy PDF mutants while activated PKA can partially rescue PDF receptor mutants. PKA subunit transcripts are also under clock control in non-PDF DN1p neurons. To address the core clock target of PDF, we rescued per in PDF neurons of arrhythmic per⁰¹ mutants. PDF neuron rescue induced high amplitude rhythms in the clock component TIMELESS (TIM) in per-less DN1p neurons. Complete loss of PDF or PKA inhibition also results in reduced TIM levels in non-PDF neurons of per⁰¹ flies. To address how PDF impacts pacemaker neuron output, we focally applied PDF to DN1p neurons and found that it acutely depolarizes and increases firing rates of DN1p neurons. Surprisingly, these effects are reduced in the presence of an adenylate cyclase inhibitor, yet persist in the presence of PKA inhibition. We have provided evidence for a signaling mechanism (PKA) and a molecular target (TIM) by which PDF resets and synchronizes clocks and demonstrates an acute direct excitatory effect of PDF on target neurons to control neuronal output. The identification of TIM as a target of PDF signaling suggests it is a multimodal integrator of cell autonomous clock, environmental light, and neural network signaling. Moreover, these data reveal a bifurcation of PKA-dependent clock effects and PKA-independent output effects. Taken together, our results provide a molecular and cellular basis for the dual functions of PDF in clock resetting and pacemaker output.

BACKGROUND

In animals, neuropeptide signaling is an important component of circadian timekeeping. The neuropeptide pigment dispersing factor (PDF) is required for several aspects of circadian activity rhythms in Drosophila.

RESULTS

Here we investigate the anatomical basis for PDF's various circadian functions by targeted PDF RNA-interference in specific classes of Drosophila neuron. We demonstrate that PDF is required in the ventro-lateral neurons (vLNs) of the central brain and not in the abdominal ganglion for normal activity rhythms. Differential knockdown of PDF in the large or small vLNs indicates that PDF from the small vLNs is likely responsible for the maintenance of free-running activity rhythms and that PDF is not required in the large vLNs for normal behavior. PDF's role in setting the period of free-running activity rhythms and the proper timing of evening activity under light:dark cycles emanates from both subtypes of vLN, since PDF in either class of vLN was sufficient for these aspects of behavior.

CONCLUSIONS

These results reveal the neuroanatomical basis PDF's various circadian functions and refine our understanding of the clock neuron circuitry of Drosophila.

BACKGROUND

Raw data normalization is a critical step in microarray data analysis because it directly affects data interpretation. Most of the normalization methods currently used are included in the R/BioConductor packages but it is often difficult to identify the most appropriate method. Furthermore, the use of R commands for functions and graphics can introduce mistakes that are difficult to trace. We present here a script written in R that provides a flexible means of access to and monitoring of data normalization for two-color microarrays. This script combines the power of BioConductor and R analysis functions and reduces the amount of R programming required.

RESULTS

Goulphar was developed in and runs using the R language and environment. It combines and extends functions found in BioConductor packages (limma and marray) to correct for dye biases and spatial artifacts. Goulphar provides a wide range of optional and customizable filters for excluding incorrect signals during the pre-processing step. It displays informative output plots, enabling the user to monitor the normalization process, and helps adapt the normalization method appropriately to the data. All these analyses and graphical outputs are presented in a single PDF report.

CONCLUSIONS

Goulphar provides simple, rapid access to the power of the R/BioConductor statistical analysis packages, with precise control and visualization of the results obtained. Complete documentation, examples and online forms for setting script parameters are available from http://transcriptome.ens.fr/goulphar/.

: Evolutionary trace report_maker offers a new type of service for researchers investigating the function of novel proteins. It pools, from different sources, information about protein sequence, structure and elementary annotation, and to that background superimposes inference about the evolutionary behavior of individual residues, using real-valued evolutionary trace method. As its only input it takes a Protein Data Bank identifier or UniProt accession number, and returns a human-readable document in PDF format, supplemented by the original data needed to reproduce the results quoted in the report.

New inhibitors of peptide deformylase (PDF) which are very potent against the isolated enzyme and show a certain degree of antibacterial activity have recently been synthesized by our group. Several lines of experimental evidence indicate that these inhibitors indeed interfere with the target enzyme in the bacterial cell. (i) The inhibition of Escherichia coli growth could be counteracted by overexpression of PDF from different organisms, including E. coli, Streptococcus pneumoniae, and Haemophilus influenzae. Conversely, reduced expression of PDF in S. pneumoniae resulted in an increased susceptibility to the inhibitors. (ii) Proteome analysis on two-dimensional gels revealed a shift for many proteins towards lower pI in the presence of PDF inhibitors, as would be expected if the proteins still carry their N-formyl-Met terminus. (iii) PDF inhibitors show no antimicrobial activity against E. coli under conditions that make growth independent of formylation and deformylation. The antibacterial activity in E. coli was characterized as bacteriostatic. Furthermore, the development of resistance in E. coli was observed to occur with high frequency (10(-7)). Resistant mutants show a reduced growth rate, and DNA sequence analysis revealed mutations in their formyl transferase gene. Taking all these aspects into account, we conclude that PDF may not be an optimal target for broad-spectrum antibacterial agents.

OBJECTIVE

To measure the effect of free access to the scientific literature on article downloads and citations.

METHODS

Randomised controlled trial.

METHODS

11 journals published by the American Physiological Society.

METHODS

1619 research articles and reviews.

METHODS

Article readership (measured as downloads of full text, PDFs, and abstracts) and number of unique visitors (internet protocol addresses). Citations to articles were gathered from the Institute for Scientific Information after one year.

METHODS

Random assignment on online publication of articles published in 11 scientific journals to open access (treatment) or subscription access (control).

RESULTS

Articles assigned to open access were associated with 89% more full text downloads (95% confidence interval 76% to 103%), 42% more PDF downloads (32% to 52%), and 23% more unique visitors (16% to 30%), but 24% fewer abstract downloads (-29% to -19%) than subscription access articles in the first six months after publication. Open access articles were no more likely to be cited than subscription access articles in the first year after publication. Fifty nine per cent of open access articles (146 of 247) were cited nine to 12 months after publication compared with 63% (859 of 1372) of subscription access articles. Logistic and negative binomial regression analysis of article citation counts confirmed no citation advantage for open access articles.

CONCLUSIONS

Open access publishing may reach more readers than subscription access publishing. No evidence was found of a citation advantage for open access articles in the first year after publication. The citation advantage from open access reported widely in the literature may be an artefact of other causes.

BACKGROUND

Low response rates among surgeons can threaten the validity of surveys. Internet technologies may reduce the time, effort, and financial resources needed to conduct surveys.

OBJECTIVE

We investigated whether using Web-based technology could increase the response rates to an international survey.

METHODS

We solicited opinions from the 442 surgeon-members of the Orthopaedic Trauma Association regarding the treatment of femoral neck fractures. We developed a self-administered questionnaire after conducting a literature review, focus groups, and key informant interviews, for which we used sampling to redundancy techniques. We administered an Internet version of the questionnaire on a Web site, as well as a paper version, which looked similar to the Internet version and which had identical content. Only those in our sample could access the Web site. We alternately assigned the participants to receive the survey by mail (n=221) or an email invitation to participate on the Internet (n=221). Non-respondents in the mail arm received up to three additional copies of the survey, while non-respondents in the Internet arm received up to three additional requests, including a final mailed copy. All participants in the Internet arm had an opportunity to request an emailed Portable Document Format (PDF) version.

RESULTS

The Internet arm demonstrated a lower response rate (99/221, 45%) than the mail questionnaire arm (129/221, 58%) (absolute difference 13%, 95% confidence interval 4%-22%, P<0.01).

CONCLUSIONS

Our Internet-based survey to surgeons resulted in a significantly lower response rate than a traditional mailed survey. Researchers should not assume that the widespread availability and potential ease of Internet-based surveys will translate into higher response rates.

Observations from our own laboratories, as well as those of others, have demonstrated the critical role of histocompatibility gene products in governing the cell-cell interactions concerned with development and regulation of immune responses in several species (8-12). In mice, the relevant genes concerned have been shown to be located in the K end of the H-2 complex, i.e. in the K and/or I See PDF for Structure regions (13, 14). These discoveries have placed histocompatibility gene products on a more complex level of biologic function than was heretofore generally considered (15). Thus, the hypothesis was made from these observations that genes in the H-2 complex coded for products involved in the development of effective cell-cell interactions in the immune response (8, 9, 15). The recent identification of cell surface macromolecules on lymphocytes and macrophages, that may be distinct from immune response gene products but are likewise coded for by genes in the I region, has provided a group of suitable candidate molecules for such a role (2). In our initial studies on the biological and biochemical characteristics of AEF, we were impressed by the apparent preferential activity of the highly purified AEF preparations on B lymphocytes syngeneic to the activated T-cell population from which the AEF was obtained (1). Since a prediction of the aforementioned hypothesis is, of course, that the active molecules involved in regulatory immunocompetent cell interactions are gene products of the H-2 complex, and, accordingly, should be reactive with antisera directed against components of this complex, we were prompted to perform the appropriate analyses on our preparation of AEF. The experiments presented here demonstrate that the enhancing activity of AEF obtained from T cells of the H-2(d) haplotype can be specifically removed by immunoadsorbents prepared from antisera reactive with la molecules of the H-2(d) allele. Identical results were obtained in experiments with both direct and indirect absorption procedures. The possibility that the reaction of AEF with the B10.A anti-B10 (anti-Ia.8) antiserum resulted in release of some components that were in turn toxic to the cultured cells, has been made unlikely in these studies by the use of a direct adsorption method utilizing an immunoadsorbent prepared from thoroughly washed glutaraldehyde-linked antibodies. The results obtained with the (B6A)F(1) anti-B10.D2 antiserum deserve some comment. This antiserum contains antibodies directed predominantly against the H-2K region specificity, H-2.31, but may also be reactive with recently determined Ia(d) specificities (5). The capacity of this antiserum to directly absorb approximately 45% of the AEF activity at the lowest concentration of AEF employed (Fig. 1) could be interpreted to indicate the reactivity of AEF with anti-H-2K antibodies. However, the data presented here are also consistent with the interpretation that partial adsorption by the direct immunoadsorbent and lack of adsorption by the indirect method (in which only a high concentration of AEF was incubated with the alloantisera) reflect reactivity of AEF with anti-Ia(d) antibodies present in this antiserum. We conclude, therefore, that the biologically active enhancing moieties of AEF bear Ia determinants and therefore are most probably gene products of the I region of the H-2 gene complex. Recent data from other investigators have shown that an antigen-specific T-cell product could be specifically adsorbed by immunoadsorbents prepared from antisera directed against the K end of H-2 (16). Since the latter antisera may contain antibodies reactive with specificities of both K and I regions, it is possible that the use of selective anti-Ia sera may yield results consistent with those presented here. Taken collectively, these observations indicate that I-region gene products may be intimately involved in the mechanism of cell-cell interactions and responsible for the regulation of immune responses.

Long-term care services provided by paid, regulated providers are an important component of personal health care spending in the United States. This report presents the most current national descriptive results from the National Study of Long-Term Care Providers (NSLTCP), which is conducted by the Centers for Disease Control and Prevention's National Center for Health Statistics (NCHS). Data presented are drawn from multiple sources, primarily NCHS surveys of adult day services centers and residential care communities (covers 2014 data year); and administrative records obtained from the Centers for Medicare and Medicare Services (CMS) on home health agencies, hospices, and nursing homes (covers 2013 and 2014 data years). This report provides information on the supply, organizational characteristics, staffing, and services offered by paid, regulated providers of long-term care services; and the demographic, health, and functional composition of users of these services. Services users include residents of nursing homes and residential care communities, patients of home health agencies and hospices, and participants of adult day services centers. This report updates "Long-Term Care Services in the United States: 2013 Overview" (available from: http://www.cdc.gov/nchs/data/nsltcp/long_term_care_services_2013.pdf), which covered data years 2011 and 2012. In contrast, the title of this report and future reports will reflect the years of the data used rather than the publication year, in this case 2013 through 2014. A forthcoming companion product to this report, "Long-Term Care Providers and Services Users in the United States—State Estimates Supplement: National Study of Long-Term Care Providers, 2013–2014," contains tables and maps showing comparable state estimates for the national findings in this report, and will be available from: http://www.cdc.gov/nchs/ nsltcp/nsltcp_products.htm.

BACKGROUND

Circadian rhythms regulate physiology and behavior through transcriptional feedback loops of clock genes running within specific pacemaker cells. In Drosophila, molecular oscillations in the small ventral lateral neurons (sLNvs) command rhythmic behavior under free-running conditions releasing the neuropeptide PIGMENT DISPERSING FACTOR (PDF) in a circadian fashion. Electrical activity in the sLNvs is also required for behavioral rhythmicity. Yet, how temporal information is transduced into behavior remains unclear.

RESULTS

Here we developed a new tool for temporal control of gene expression to obtain adult-restricted electrical silencing of the PDF circuit, which led to reversible behavioral arrhythmicity. Remarkably, PERIOD (PER) oscillations during the silenced phase remained unaltered, indicating that arrhythmicity is a direct consequence of the silenced activity. Accordingly, circadian axonal remodeling and PDF accumulation were severely affected during the silenced phase.

CONCLUSIONS

Although electrical activity of the sLNvs is not a clock component, it coordinates circuit outputs leading to rhythmic behavior.

Morning and evening circadian oscillators control the bimodal activity of Drosophila in light-dark cycles. The lateral neurons evening oscillator (LN-EO) is important for promoting diurnal activity at dusk. We found that the LN-EO autonomously synchronized to light-dark cycles through either the cryptochrome (CRY) that it expressed or the visual system. In conditions in which CRY was not activated, flies depleted for pigment-dispersing factor (PDF) or its receptor lost the evening activity and displayed reversed PER oscillations in the LN-EO. Rescue experiments indicated that normal PER cycling and the presence of evening activity relied on PDF secretion from the large ventral lateral neurons and PDF receptor function in the LN-EO. The LN-EO thus integrates light inputs and PDF signaling to control Drosophila diurnal behavior, revealing a new clock-independent function for PDF.

We describe the relationship between the shape of the phase-resetting curve (PRC) and the degree of stochastic synchronization observed between a pair of uncoupled general oscillators receiving partially correlated Poisson inputs in addition to inputs from independent sources. We use perturbation methods to derive an expression relating the shape of the PRC to the probability density function (PDF) of the phase difference between the oscillators. We compute various measures of the degree of synchrony and cross correlation from the PDF's and use the same to compare and contrast differently shaped PRCs, with respect to their ability to undergo stochastic synchronization. Since the shape of the PRC depends on underlying dynamical details of the oscillator system, we utilize the results obtained from the analysis of general oscillator systems to study specific models of neuronal oscillators. It is shown that the degree of stochastic synchronization is controlled both by the firing rate of the neuron and the membership of the PRC (type I or type II). It is also shown that the circular variance for the integrate and fire neuron and the generalized order parameter for a hippocampal interneuron model have a nonlinear relationship to the input correlation.

The exponential development of Patient-Reported Outcomes (PRO) measures in clinical research has led to the creation of the Patient-Reported Outcome and Quality of Life Instruments Database (PROQOLID) to facilitate the selection process of PRO measures in clinical research. The project was initiated by Mapi Research Trust in Lyon, France. Initially called QOLID (Quality of Life Instruments Database), the project's purpose was to provide all those involved in health care evaluation with a comprehensive and unique source of information on PRO and HRQOL measures available through the Internet.PROQOLID currently describes more than 470 PRO instruments in a structured format. It is available in two levels, non-subscribers and subscribers, at http://www.proqolid.org. The first level is free of charge and contains 14 categories of basic useful information on the instruments (e.g. author, objective, original language, list of existing translations, etc.). The second level provides significantly more information about the instruments. It includes review copies of over 350 original instruments, 120 user manuals and 350 translations. Most are available in PDF format. This level is only accessible to annual subscribers. PROQOLID is updated in close collaboration with the instruments' authors on a regular basis. Fifty or more new instruments are added to the database annually.Today, all of the major pharmaceutical companies, prestigious institutions (such as the FDA, the NIH's National Cancer Institute, the U.S. Veterans Administration), dozens of universities, public institutions and researchers subscribe to PROQOLID on a yearly basis. More than 800 users per day routinely visit the database.

This paper proposes a 3D statistical model aiming at effectively capturing statistics of high-dimensional deformation fields and then uses this prior knowledge to constrain 3D image warping. The conventional statistical shape model methods, such as the active shape model (ASM), have been very successful in modeling shape variability. However, their accuracy and effectiveness typically drop dramatically in high-dimensionality problems involving relatively small training datasets, which is customary in 3D and 4D medical imaging applications. The proposed statistical model of deformation (SMD) uses wavelet-based decompositions coupled with PCA in each wavelet band, in order to more accurately estimate the pdf of high-dimensional deformation fields, when a relatively small number of training samples are available. SMD is further used as statistical prior to regularize the deformation field in an SMD-constrained deformable registration framework. As a result, more robust registration results are obtained relative to using generic smoothness constraints on deformation fields, such as Laplacian-based regularization. In experiments, we first illustrate the performance of SMD in representing the variability of deformation fields and then evaluate the performance of the SMD-constrained registration, via comparing a hierarchical volumetric image registration algorithm, HAMMER, with its SMD-constrained version, referred to as SMD+HAMMER. This SMD-constrained deformable registration framework can potentially incorporate various registration algorithms to improve robustness and stability via statistical shape constraints.

Sodium and potassium influxes and outfluxes have been studied in single isolated muscle fibers from the giant barnacle both by microinjection and by external loading. The sodium influxes and outfluxes were 49 and 39 pmoles /cm(2)-sec (temperature = 15-16 degrees C) respectively. The potassium influxes and outfluxes were 28 and 60 pmoles/cm(2)-sec (temperature = 13-16 degrees C) respectively. Replacement of external sodium by lithium reduced sodium outflux by 67% but had no effect on potassium outflux. Removal of external potassum reduced the sodium outflux by 51% but had no effect on potassium outflux. External strophanthidin (10-30 microM) reduced sodium outflux by 80-90% and increased potassium outflux by 40% in normal fibers. The time constant for sodium exchange increased linearly with internal sodium concentration, as did the fraction of sodium outflux insensitive to a maximally inhibitory concentration of external strophanthidin in the range of 10 tO 80 mM internal sodium. The strophanthidin-sensitive component of sodium outflux could be related to the internal sodium concentration by the following empirical formula: See PDF for Equation

Drosophila melanogaster flies concentrate behavioral activity around dawn and dusk. This organization of daily activity is controlled by central circadian clock neurons, including the lateral-ventral pacemaker neurons (LN(v)s) that secrete the neuropeptide PDF (pigment dispersing factor). Previous studies have demonstrated the requirement for PDF signaling to PDF receptor (PDFR)-expressing dorsal clock neurons in organizing circadian activity. Although LN(v)s also express functional PDFR, the role of these autoreceptors has remained enigmatic. Here, we show that (1) PDFR activation in LN(v)s shifts the balance of circadian activity from evening to morning, similar to behavioral responses to summer-like environmental conditions, and (2) this shift is mediated by stimulation of the Gα,s-cAMP pathway and a consequent change in PDF/neurotransmitter corelease from the LN(v)s. These results suggest another mechanism for environmental control of the allocation of circadian activity and provide new general insight into the role of neuropeptide autoreceptors in behavioral control circuits.

MicroRNAs (miRNAs) are synonymous with post-transcriptional repression of target genes. A number of studies, however, have reported miRNAs functioning outside this paradigm, and this SnapShot outlines these unconventional ways in which miRNAs can exert regulatory functions. To view this SnapShot, open or download the PDF.

Recent outbreaks of Clostridium difficile-associated diarrhoea (CDAD) with increased severity, high relapse rate and significant mortality have been related to the emergence of a new, hypervirulent C. difficile strain in North America, Japan and Europe. Definitions have been proposed by the European Centre of Disease Prevention and Control (ECDC) to identify severe cases of CDAD and to differentiate community-acquired cases from nosocomial CDAD (http://www.ecdc.europa.eu/documents/pdf/Cl_dif_v2.pdf). CDAD is mainly known as a healthcare-associated disease, but it is also increasingly recognised as a community-associated disease. The emerging strain is referred to as North American pulsed-field type 1 (NAP1) and PCR ribotype 027. Since 2005, individual countries have developed surveillance studies to monitor the spread of this strain. C. difficile type 027 has caused outbreaks in England and Wales, Ireland, the Netherlands, Belgium, Luxembourg, and France, and has also been detected in Austria, Scotland, Switzerland, Poland and Denmark. Preliminary data indicated that type 027 was already present in historical isolates collected in Sweden between 1997 and 2001.

Hybrid antibody [F(ab')(2)] with dual specificity for mouse gammaG and ferritin was prepared from the corresponding rabbit antisera, providing a precise reagent for locating mouse gammaG on cell surfaces. Viable cells were exposed successively to (a) mouse antibody to a cell surface antigen, (b) the rabbit hybrid antibody, and (c) ferritin, before preparation for electron microscopy. This method of See PDF for Structure. labeling is sensitive and specific and clearly lends itself to the introduction of visual markers other than ferritin. Other advantages are uniformity of labeling, ease of purification of the reagent, and circumvention of the many drawbacks arising from coupling ferritin to antibody chemically.

The promoter of the Streptococcus pneumoniae putative fuculose kinase gene (fcsK), the first gene of a novel fucose utilization operon, is induced by fucose and repressed by glucose or sucrose. When the streptococcal polypeptide deformylase (PDF) gene (def1, encoding PDF) was placed under the control of P(fcsK), fucose-dependent growth of the S. pneumoniae (P(fcsK)::def1) strain was observed, confirming the essential nature of PDF in this organism. The mode of antibacterial action of actinonin, a known PDF inhibitor, was also confirmed with this strain. The endogenous fuculose kinase promoter is a tightly regulated, titratable promoter which will be useful for target validation and for confirmation of the mode of action of novel antibacterial drugs in S. pneumoniae.

In this article, the authors isolate a gene encoding a neuropeptide in Drosophila melanogaster. The substance is called pigment-dispersing factor (PDF), based on one of the roles it plays in crustaceans (the arthropods in which this factor was initially discovered). The PDF-encoding Drosophila gene (pdf) is intronless and present in a single copy per haploid genome. The cytological location of pdf is 97B on the third chromosome. The putative 102-amino-acid precursor (prepro-PDF) consists of a signal peptide and a PDF-associated peptide, followed by the mature PDF. The PDF-associated peptide region of the precursor is highly diverged from those of the crustacean precursors, whereas the primary structure of the mature PDF is conserved in other members of the pigment-dispersing hormone family. A single pdf transcript (ca. 0.8 kb) is expressed predominantly in the head; the expression levels of pdf mRNA are consistently higher in males than in females. Putative pdf homologous transcripts are present in other Drosophila species, which exhibit similar sexual dimorphic expression patterns. Cyclic expression of pdf over the course of the day and night was assessed, but the mRNA exhibited at best very gentle cycling. The pdf expression in two behaviorally arrhythmic mutants were examined; the expression was intact in a period0 mutant but absent in the disconnected mutant.