Evaluating an Evidence-Based Practice Curriculum for Nurses Entering Clinical Practice in the Veterans Health Administration

Introduction

The Veterans Health Administration (VHA) registered nurse (RN) Transition to Practice (TTP) program is a 1-year comprehensive, standardized curriculum taught for entry-level nurses to assist them in transitioning to VA-trained, competent, professional RNs. The TTP program includes revised modules on Evidence-Based Practice (EBP) clinical decision making. The revised curriculum emphasizes EBP as a problem-solving approach to clinical decision making rather than a project-based approach to implement practice changes. The goal of this quality improvement project was to evaluate the content, delivery, and outcomes of a revised Evidence-Based Practice Curriculum (EBPC) for use in the VHA RN TTP program.

Methods

Focus groups were conducted with TTP coordinators, who teach the program and facility EBP content experts from 32 VHA Medical Centers. All attended a three-day face-to-face training at a central location. Qualitative data were managed and analyzed with a rapid assessment process.

Discussion

Leaders within and outside of organizations are commonly believed to affect the success of implementing and sustaining any program or initiative through their influence on organizational climate, leadership processes, and leadership alignment across multiple levels of leadership. Our findings were in line with other research showing that leaders should prioritize EBP and fuel it with resources to create sustainable change.

Conclusions

In conclusion, the EBPC was reviewed very favorably by all who planned to use it in their facilities in teaching the content to practicing registered nurses. Future evaluation will focus on the degree to which faculty use the program, how they use the modules, and what feedback nurses provide after exposure to EBPC.

Using Clinical Narratives in Program and Curriculum Evaluation

Background

Using personal experience stories as teaching tools, clinical narratives are an effective means for sharing the art of nursing practice and provide insight into nurses' critical thinking and clinical proficiency. Using clinical narratives to assess curriculum effectiveness provides important insights into changed practice and learning beyond the classroom.

Aim

This article provides an example of using clinical narratives in the evaluation of the Department of Veterans Health Affairs Office of Nursing Services (ONS) Evidence Based Practice Curriculum (EBPC).

Methods

As part of a larger mixed-method evaluation of the EBPC, clinical narrative methods were employed to describe one incident where participants (n=3) applied at least two of three evidence based practice components (best available evidence; clinical expertise; patient preference).

Results

Examination of clinical narratives demonstrated successful application of key components of evidence based practice and an integration into individual nursing practice beyond data obtained from other evaluation methods.

Conclusions

Incorporating rich clinical narratives into a rigorous mixed-method program evaluation protocol provides insights beyond information uptake, satisfaction, efficacy, or competency assessment scores.

High risk HPV infection prevalence and associated cofactors: a population-based study in female ISSSTE beneficiaries attending the HPV screening and early detection of cervical cancer program

BACKGROUND

Cervical cancer is the second cause leading of malignancy-related death among Mexican women. The present study determined the population-based prevalence of high risk Human Papillomavirus (HR-HPV) infection and associated cofactors in female beneficiaries of the Institute of Security and Social Services for State Workers (ISSSTE) attending the Program for HPV Screening and Early Detection of Cervical Cancer and registered in the Women's Cancer Detection System (SIDECAM).

METHODS

In a cross-sectional study, cervical samples from 115,651 female users of the program for HPV screening and early detection of cervical cancer recruited in 23 ISSSTE care centers were analyzed for HR-HPV. Logistic regression analyses, adjusting for potential confounders, were performed to determine the association of HR-HPV infection with sexual health and behavior variables and with positivity to cervical premalignant lesions by cytology.

RESULTS

The overall prevalence of HR-HPV infection among female ISSSTE beneficiaries in the 2013-2015 period was 13%. A bivariate analysis of relevant variables for HR-HPV infection showed a statistically significant association for age, number of sexual partners, use of hormonal contraceptives and smoking. A statistical association was found between infection by HR-HPV with the use of hormonal contraceptives, number of sexual partners and smoking and association of HPV 16 and other non-16/18 HR-HPV infection with number of lifetime sexual partners and tobacco use adjusted for age, history of hormonal contraception, number of sexual partners and tobacco use with the exception of exposition variable itself. Similarly, an association was found between HR-HPV infection, regardless of the virus genotype, with positivity to cervical premalignant lesions adjusted for age, number of lifetime sexual partners, history of hormonal contraception and tobacco use.

CONCLUSIONS

HR-HPV prevalence in female ISSSTE Women's Cancer Program users is similar to the population-based prevalence previously reported in Mexican women without cervical alterations. The ISSSTE robust screening and early detection program, based on cytology studies and HPV co-testing, allows us to know the prevalence of HR-HPV infection among female users of the service.

Surrogate-Based Artifact Removal From Single-Channel EEG

OBJECTIVE

the recent emergence and success of electroencephalography (EEG) in low-cost portable devices, has opened the door to a new generation of applications processing a small number of EEG channels for health monitoring and brain-computer interfacing. These recordings are, however, contaminated by many sources of noise degrading the signals of interest, thus compromising the interpretation of the underlying brain state. In this paper, we propose a new data-driven algorithm to effectively remove ocular and muscular artifacts from single-channel EEG: the surrogate-based artifact removal (SuBAR).

METHODS

by means of the time-frequency analysis of surrogate data, our approach is able to identify and filter automatically ocular and muscular artifacts embedded in single-channel EEG.

RESULTS

in a comparative study using artificially contaminated EEG signals, the efficacy of the algorithm in terms of noise removal and signal distortion was superior to other traditionally-employed single-channel EEG denoizing techniques: wavelet thresholding and the canonical correlation analysis combined with an advanced version of the empirical mode decomposition. Even in the presence of mild and severe artifacts, our artifact removal method provides a relative error 4 to 5 times lower than traditional techniques.

SIGNIFICANCE

in view of these results, the SuBAR method is a promising solution for mobile environments, such as ambulatory healthcare systems, sleep stage scoring, or anesthesia monitoring, where very few EEG channels or even a single channel is available.

Detection of time reversibility in time series by ordinal patterns analysis

Time irreversibility is a common signature of nonlinear processes and a fundamental property of non-equilibrium systems driven by non-conservative forces. A time series is said to be reversible if its statistical properties are invariant regardless of the direction of time. Here, we propose the Time Reversibility from Ordinal Patterns method (TiROP) to assess time-reversibility from an observed finite time series. TiROP captures the information of scalar observations in time forward as well as its time-reversed counterpart by means of ordinal patterns. The method compares both underlying information contents by quantifying its (dis)-similarity via the Jensen-Shannon divergence. The statistic is contrasted with a population of divergences coming from a set of surrogates to unveil the temporal nature and its involved time scales. We tested TiROP in different synthetic and real, linear, and non-linear time series, juxtaposed with results from the classical Ramsey's time reversibility test. Our results depict a novel, fast-computation, and fully data-driven methodology to assess time-reversibility with no further assumptions over data. This approach adds new insights into the current non-linear analysis techniques and also could shed light on determining new physiological biomarkers of high reliability and computational efficiency.

CARE-rCortex: A Matlab toolbox for the analysis of CArdio-REspiratory-related activity in the Cortex

BACKGROUND

Although cardio-respiratory (CR) system is generally controlled by the autonomic nervous system, interactions between the cortex and these primary functions are receiving an increasing interest in neurosciences.

NEW METHOD

In general, the timing of such internally paced events (e.g. heartbeats or respiratory cycles) may display a large variability. For the analysis of such CR event-related EEG potentials, a baseline must be correctly associated to each cycle of detected events. The open-source toolbox CARE-rCortex provides an easy-to-use interface to detect CR events, define baselines, and analyse in time-frequency (TF) domain the CR-based EEG potentials.

RESULTS

CARE-rCortex provides some practical tools to detect and validate these CR events. Users can define baselines time-locked to a phase of respiratory or heart cycle. A statistical test has also been integrated to highlight significant points of the TF maps with respect to the baseline. We illustrate the use of CARE-rCortex with the analysis of two real cardio-respiratory datasets.

COMPARISON WITH EXISTING METHODS

Compared to other open-source toolboxes, CARE-rCortex allows users to automatically detect CR events, to define and check baselines for each detected event. Different baseline normalizations can be used in the TF analysis of EEG epochs.

CONCLUSIONS

The analysis of CR-related EEG activities could provide valuable information about cognitive or pathological brain states. CARE-rCortex runs in Matlab as a plug-in of the EEGLAB software, and it is publicly available at https://github.com/FannyGrosselin/CARE-rCortex.

Role of inter-hemispheric connections in functional brain networks

Today the human brain can be modeled as a graph where nodes represent different regions and links stand for statistical interactions between their activities as recorded by different neuroimaging techniques. Empirical studies have lead to the hypothesis that brain functions rely on the coordination of a scattered mosaic of functionally specialized brain regions (modules or sub-networks), forming a web-like structure of coordinated assemblies (a network of networks. NoN). The study of brain dynamics would therefore benefit from an inspection of how functional sub-networks interact between them. In this paper, we model the brain as an interconnected system composed of two specific sub-networks, the left (L) and right (R) hemispheres, which compete with each other for centrality, a topological measure of importance in a networked system. Specifically, we considered functional scalp EEG networks (SEN) derived from high-density electroencephalographic (EEG) recordings and investigated how node centrality is shaped by interhemispheric connections. Our results show that the distribution of centrality strongly depends on the number of functional connections between hemispheres and the way these connections are distributed. Additionally, we investigated the consequences of node failure on hemispherical centrality, and showed how the abundance of inter-hemispheric links favors the functional balance of centrality distribution between the hemispheres.

WITHDRAWN: A single center experience in resectable pancreatic ductal adenocarcinoma : the limitations of the surgery-first approach. Critical review of the literature and proposals for practice update

The article has been withdrawn at the request of the authors and editor because of incorrect authorship, which is considered a form of unethical publication. The Publisher apologizes for any inconvenience this may cause.

A single center experience in resectable pancreatic ductal adenocarcinoma : the limitations of the surgery-first approach. Critical review of the literature and proposals for practice update

BACKGROUND AND STUDY AIMS

The current standard of care for resectable pancreatic ductal adenocarcinoma (PDAC) is surgery-first followed by adjuvant chemotherapy. We review our single center experience in a PDAC cohort managed by the surgery-first strategy. We then compare our data to those of Belgian and international literature.

PATIENTS METHODS

We reviewed a series of 83 consecutive resectable patients with PDAC, treated by the surgery-first approach in a Belgian Academic Hospital between 2007 and 2013. The outcomes were assessed with univariate and multivariate Cox regression analysis. Kaplan-Meier curves were drawn according to patient groups.

RESULTS

For the entire population, the median survival (MS) was 18.4 months; the 1-year relapse-free survival was 56%, and the 5-year overall survival (OS) was 13%. The size of the primary tumor larger than 3 cm (OS, HR = 1.76, p = 0.033) and vascular resection (DFS, HR = 2.1, p = 0.024) were the single independent prognostic factors in the multivariate analysis of this cohort. Only 69% of the patients received adjuvant chemotherapy, and more than 75% of them demonstrated no chance of survival beyond 3 years because they harbored poor prognostic factors, recognized only postoperatively.

CONCLUSIONS

Our results and those published in the literature brought to light the limited perspectives of the surgery-first strategy in a population of apparently resectable pancreatic cancers. In comparison, data from reported neo-adjuvant series deserve our interest to bring this strategy upfront in selected patients in the context of close observational monitoring and randomized trials. The actual standard of care for resectable PDAC is surgery-first followed by adjuvant chemotherapy. The performance of this strategy relies on the dedicated imaging that does not accurately recognize the limits of the tumor and the high prevalence of adverse prognostic factors. Moreover, pancreatectomy remains associated with high postoperative complication rates and the poor completion of adjuvant therapy. This translates into poor long-term survival figures. In our series the MS was 18.4 months and 5-year OS was 13%. The disease-free survival (DFS) was 15.6 months, 1 and 3-year DFS were 56 and 26%, respectively. The variables that significantly correlated with OS in univariate analysis are tumor size and lymph node involvement. Regarding DFS, vascular resection was the only significant factor. In the multivariate analysis, the only significant factor related to OS remained the tumor size >3 cm in greatest diameter. Vascular resection remained significant for DFS. 31% of the patients did not receive any chemotherapy at all before the 6-month period following resection. The rates of complete resections compared favorably with those of a surgery-first strategy with no excess of operative mortality, complications and early relapse rates. The advantages of a chemotherapy-first approach, eventually combined with chemo-radiotherapy, are to offer higher combined therapy completion rates and improve the level of free resection margins, lymph node involvement and patient selection. The advent of safe, more potent chemotherapy combinations has the potential to further improve survival when administered upfront.

Loss of brain inter-frequency hubs in Alzheimer's disease

Alzheimer's disease (AD) causes alterations of brain network structure and function. The latter consists of connectivity changes between oscillatory processes at different frequency channels. We proposed a multi-layer network approach to analyze multiple-frequency brain networks inferred from magnetoencephalographic recordings during resting-states in AD subjects and age-matched controls. Main results showed that brain networks tend to facilitate information propagation across different frequencies, as measured by the multi-participation coefficient (MPC). However, regional connectivity in AD subjects was abnormally distributed across frequency bands as compared to controls, causing significant decreases of MPC. This effect was mainly localized in association areas and in the cingulate cortex, which acted, in the healthy group, as a true inter-frequency hub. MPC values significantly correlated with memory impairment of AD subjects, as measured by the total recall score. Most predictive regions belonged to components of the default-mode network that are typically affected by atrophy, metabolism disruption and amyloid-β deposition. We evaluated the diagnostic power of the MPC and we showed that it led to increased classification accuracy (78.39%) and sensitivity (91.11%). These findings shed new light on the brain functional alterations underlying AD and provide analytical tools for identifying multi-frequency neural mechanisms of brain diseases.

Sex-based differential regulation of bacterial-induced bone resorption

BACKGROUND AND OBJECTIVE

Periodontal disease pathogenesis is comprised of the complex inflammatory immune response to oral bacterial dysbiosis. Like other inflammatory diseases, there is sexual dimorphism evident in periodontal diseases. During periodontitis, inflammatory chemokines direct neutrophils to migrate to the site of infection to neutralize the pathogen. Interestingly, these same chemokines are also involved in regulating pathogen-induced osteoclast formation. Previous reports show differences in bone turnover and lymphocyte recruitment between sexes. We hypothesize that chemokine expression is differentially regulated by sex and thus results in differential osteoclast formation.

MATERIAL AND METHODS

Male and female mice were utilized to isolate neutrophils based on expression of Ly6G-specific, as well as defined osteoclast progenitors. Cells were stimulated with lipopolysaccharide (LPS; 100 ng/mL) then analyzed for neutrophil infiltration and gene expression. Defined osteoclast progenitors were primed: macrophage-colony stimulating factor (25 ng/mL), receptor activator of NF-κB ligand (50 ng/mL), then stimulated with LPS. Osteoclasts were enumerated via TRAP stain and mRNA isolated for gene expression analysis via quantitative polymerase chain reaction.

RESULTS

In response to LPS, male neutrophils in vitro respond with increased chemokine expression and significantly more osteoclast formed in response to LPS compared to females.

CONCLUSIONS

Findings support observations in humans regarding a sexual dimorphism in oral bacterial infections of alveolar bone loss. Males have a strong inflammatory response to bacterial infection, resulting in increased inflammatory microenvironment, reduced pathogenic bacteria clearance and increased osteoclast-driven bone loss in response to differential expression of key chemokines.

Characterization of X-linked hypohidrotic ectodermal dysplasia (XL-HED) hair and sweat gland phenotypes using phototrichogram analysis and live confocal imaging

Hypohidrotic ectodermal dysplasia (HED) is the most common type of ectodermal dysplasia (ED), which encompasses a large group of syndromes that share several phenotypic features such as missing or malformed ectodermal structures, including skin, hair, sweat glands, and teeth. X-linked hypohidrotic ectodermal dysplasia (XL-HED) is associated with mutations in ectodysplasin (EDA1). Hypohidrosis due to hypoplastic sweat glands and thin, sparse hair are phenotypic features that significantly affect the daily lives of XL-HED individuals and therefore require systematic analysis. We sought to determine the quality of life of individuals with XL-HED and to quantify sweat duct and hair phenotypes using confocal imaging, pilocarpine iontophoresis, and phototrichogram analysis. Using these highly sensitive and non-invasive techniques, we demonstrated that 11/12 XL-HED individuals presented with a complete absence of sweat ducts and that none produced sweat. We determined that the thin hair phenotype observed in XL-HED was due to multiple factors, such as fewer terminal hairs with decreased thickness and slower growth rate, as well as fewer follicular units and fewer hairs per unit. The precise characterization of XL-HED phenotypes using sensitive and non-invasive techniques presented in our study will improve upon larger genotype-phenotype studies and the assessment of future therapies in XL-HED.

Modeling ventilation time in forage tower silos

The fermentation process in forage tower silos produces a significant amount of gases, which can easily reach dangerous concentrations and constitute a hazard for silo operators. To maintain a non-toxic environment, silo ventilation is applied. Literature reviews show that the fermentation gases reach high concentrations in the headspace of a silo and flow down the silo from the chute door to the feed room. In this article, a detailed parametric analysis of forced ventilation scenarios built via numerical simulation was performed. The methodology is based on the solution of the Navier-Stokes equations, coupled with transport equations for the gas concentrations. Validation was achieved by comparing the numerical results with experimental data obtained from a scale model silo using the tracer gas testing method for O2 and CO2 concentrations. Good agreement was found between the experimental and numerical results. The set of numerical simulations made it possible to establish a simple analytical model to predict the minimum time required to ventilate a silo to make it safe to enter. This ventilation time takes into account the headspace above the forage, the airflow rate, and the initial concentrations of O2 and CO2. The final analytical model was validated with available results from the literature.

Dynamics of excitable neural networks with heterogeneous connectivity

A central issue of neuroscience is to understand how neural units integrates internal and external signals to create coherent states. Recently, it has been shown that the sensitivity and dynamic range of neural assemblies are optimal at a critical coupling among its elements. Complex architectures of connections seem to play a constructive role on the reliable coordination of neural units. Here we show that, the synchronizability and sensitivity of excitable neural networks can be tuned by diversity in the connections strengths. We illustrate our findings for weighted networks with regular, random and complex topologies. Additional comparisons of real brain networks support previous studies suggesting that heterogeneity in the connectivity may play a constructive role on information processing. These findings provide insights into the relationship between structure and function of neural circuits.

Functional modularity of background activities in normal and epileptic brain networks

We analyze the connectivity structure of weighted brain networks extracted from spontaneous magnetoencephalographic signals of healthy subjects and epileptic patients (suffering from absence seizures) recorded at rest. We find that, for the activities in the 5-14 Hz range, healthy brains exhibit a sparse connectivity, whereas the brain networks of patients display a rich connectivity with a clear modular structure. Our results suggest that modularity plays a key role in the functional organization of brain areas during normal and pathological neural activities at rest.

Complex modular structure of large-scale brain networks

Modular structure is ubiquitous among real-world networks from related proteins to social groups. Here we analyze the modular organization of brain networks at a large scale (voxel level) extracted from functional magnetic resonance imaging signals. By using a random-walk-based method, we unveil the modularity of brain webs and show modules with a spatial distribution that matches anatomical structures with functional significance. The functional role of each node in the network is studied by analyzing its patterns of inter- and intramodular connections. Results suggest that the modular architecture constitutes the structural basis for the coexistence of functional integration of distant and specialized brain areas during normal brain activities at rest.

Dynamic small-world behavior in functional brain networks unveiled by an event-related networks approach

There is growing interest in studying the role of connectivity patterns in brain functions. In recent years, functional brain networks were found to exhibit small-world properties during different brain states. In previous studies, time-independent networks were recovered from long time periods of brain activity. In this paper, we propose an approach, the event-related networks, that allows one to characterize the dynamical evolution of functional brain networks in time-frequency space. We illustrate this approach by characterizing connectivity patterns in magnetoencephalographic signals recorded during a visual stimulus paradigm. When compared with equivalent random and regular networks, the results reveal that functional connectivity varies with time and frequency during the processing of the stimulus, while maintaining a small-world structure. This approach may provide insights into the connectivity of other complex and spatially extended nonstationary systems.

Degree mixing and the enhancement of synchronization in complex weighted networks

Real networks often consist of local units interacting with each other by means of heterogeneous connections. In many cases, furthermore, such networks feature degree mixing properties, i.e., the tendency of nodes with high degree (with low degree) to connect with connectivity peers (with highly connected nodes). Such degree-degree correlations may have an important influence in the spreading of information or infectious agents on a network. We explore the role played by these correlations for the synchronization of networks of coupled dynamical systems. Using a stochastic optimization technique, we find that the value of degree mixing providing optimal conditions for synchronization depends on the weighted coupling scheme. We also show that a minimization of the assortative coefficient may induce a strong destabilization of the synchronous state. We illustrate our findings for weighted networks with scale free and random topologies.

Synchronization in dynamical networks: evolution along commutative graphs

Starting from an initial wiring of connections, we show that the synchronizability of a network can be significantly improved by evolving the graph along a time dependent connectivity matrix. We consider the case of connectivity matrices that commute at all times, and compare several approaches to engineer the corresponding commutative graphs. In particular, we show that synchronization in a dynamical network can be achieved even in the case in which each individual commutative graphs does not give rise to synchronized behavior.

Towards a proper estimation of phase synchronization from time series

In experimental synchronization studies a continuous phase variable is commonly estimated from a scalar time series by means of its representation on the complex plane. The aim is to obtain a pair of functions [A(t), phi(t)] defining its instantaneous amplitude and phase, respectively. However, any arbitrary pair of functions cannot be considered as the amplitude and the phase of the real observable. Here, we point out some criteria that the pair [A(t), phi(t)] must observe to unambiguously define the instantaneous amplitude and phase of the observed signal. In this work, we illustrate how the complex representation may fail if the signal possesses a multi-component or a broadband spectra. We also point out a practical procedure to test whether a signal, not displaying a single oscillation at a unique frequency, has a narrow-band behavior. Implications for the study of phase interdependencies are illustrated and discussed. Phase dynamics estimated from electric brain activities recorded from an epileptic patient are also discussed.

Synchronizing weighted complex networks

Real networks often consist of local units, which interact with each other via asymmetric and heterogeneous connections. In this work, we explore the constructive role played by such a directed and weighted wiring for the synchronization of networks of coupled dynamical systems. The stability condition for the synchronous state is obtained from the spectrum of the respective coupling matrices. In particular, we consider a coupling scheme in which the relative importance of a link depends on the number of shortest paths through it. We illustrate our findings for networks with different topologies: scale free, small world, and random wirings.

Neuropsychological function in nondemented carriers of presenilin-1 mutations

BACKGROUND

Prospective and case-control studies have demonstrated that memory loss and executive dysfunction occur early in Alzheimer disease (AD).

OBJECTIVE

To investigate these observations by the study of persons at risk for autosomal dominant forms of AD.

METHODS

Neuropsychological and genetic tests were performed on 51 nondemented at-risk members of 10 Mexican families with two distinct presenilin-1 (PS1) mutations. Test scores were compared between PS1 mutation carriers (MCs; n = 30) and noncarriers (NCs; n = 21) by analyses of variance, co-varying for family and specific mutation. Regression analyses were performed, taking into account age relative to the median age at dementia diagnosis in the family (adjusted age), gender, Beck Depression Inventory (BDI) scores, education, and number of APOE epsilon4 alleles. Subjects were divided into age tertiles and scores compared within these groups. Composite scores for Verbal Memory, Executive Function/Working Memory, Language, and Visuospatial Function were created, and these scores compared between MCs and NCs.

RESULTS

MCs performed worse than NCs on the Mini-Mental State Examination, Trails Making Tests A and B, Delayed Recall of a 10-Word List, and Wechsler Adult Intelligence Scale WAIS Block Design. In multiple linear regression analyses, BDI score, gender, and number of APOE epsilon4 alleles did not consistently affect test scores. The differences seen between MCs and NCs were due to differences in the oldest tertile. MCs had lower Visuospatial and Executive Function/Working Memory but not Verbal Memory or Language composite scores.

CONCLUSIONS

This study is consistent with findings in sporadic Alzheimer disease of early problems with memory, visuospatial function, and particularly with executive function in PS1 mutation carriers. Depression, gender, and presence of an APOE epsilon4 allele did not demonstrate large influences on neuropsychological performance.

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) inhibition of coronary vasculogenesis is mediated, in part, by reduced responsiveness to endogenous angiogenic stimuli, including vascular endothelial growth factor A (VEGF-A)

BACKGROUND

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exposure prior to chick embryo incubation (GD 0) induces dilated cardiomyopathy, and reduces myocardial hypoxia, vascular endothelial growth factor A (VEGF-A) expression, and coronary vascularization. We investigated whether reduced coronary vascularization 1) occurs in the absence of changes in cardiac morphology and 2) is associated with altered secretion of VEGF-A and/or an antivasculogenic factor.

METHODS

Chicken eggs were treated with control (corn oil) or TCDD (0.075-0.3 pmol of TCDD/gm) on GD 5. In vivo cardiac morphology and artery number were determined on GD 10, while in vitro vascular outgrowth and VEGF-A secretion were determined from cardiac explants on GD 6. Effects of recombinant VEGF-A (rcVEGF-A), soluble flt-1 (sFlt-1) receptor plus rcVEGF-A, and control conditioned media were assessed in TCDD explants, while effects of TCDD-conditioned media was assessed in control explants.

RESULTS

TCDD reduced coronary artery number in vivo by 53 +/- 8% and induced a dose-related reduction in tube outgrowth in vitro, but had no effect on cardiac morphology. All TCDD doses reduced explant VEGF-A secretion equally (43 +/- 3%), compared to control. sFlt-1 blocked outgrowth in control cultures and blocked rcVEGF-A-mediated rescue of outgrowth in TCDD explants. Control conditioned media partially rescued outgrowth from TCDD explants, while conditioned media from TCDD explants had no effect on controls.

CONCLUSIONS

TCDD inhibition of coronary vascularization can occur in the absence of changes in cardiac morphology and is associated with reduced VEGF-A secretion but not an antivasculogenic factor. Since control media only partly rescues TCDD's inhibitory effect, we suggest that TCDD-exposed endothelial cells are less responsive to vasculogenic stimuli.

Synchronization is enhanced in weighted complex networks

The propensity for synchronization of complex networks with directed and weighted links is considered. We show that a weighting procedure based upon the global structure of network pathways enhances complete synchronization of identical dynamical units in scale-free networks. Furthermore, we numerically show that very similar conditions hold also for phase synchronization of nonidentical chaotic oscillators.

Synchronization in complex networks with age ordering

The propensity for synchronization is studied in a complex network of asymmetrically coupled units, where the asymmetry in a given link is determined by the relative age of the involved nodes. In growing scale-free networks, synchronization is enhanced when couplings from older to younger nodes are dominant. We describe the requirements for such an effect in a more general context and compare with the situations in nongrowing random networks with and without a degree ordering.

A theoretical approach to some analytical properties of heterogeneous enzymatic assays

Heterogeneous enzymatic assays (HEA), where an enzyme in solution acts upon an immobilized substrate, are been increasingly used. Given their high throughput and versatility they hold great potential for developing massive enzyme inhibitor screening. However, current HEA lack, in general, rigorous quantitative use. This is in part due to technical problems as a multiplicity of suboptimal substrate populations achieved with traditional immobilization techniques but, more importantly, is due to a poor understanding of the particular kinetic behavior of these systems. This paper addresses the kinetic features of HEA that arise from the very low amount of solid-phase substrate and the resulting inalterability of the free enzyme concentration during the assay, which classify HEA as enzyme quasi-saturable systems (EQSS). We assessed the optimal enzyme concentration working range and time of reaction. We also considered certain attributes of HEA for evaluating isosteric inhibitors. These studies were done on the basis of a simplified model for the kinetics of EQSS and a formal splitting of the functional factor of the analytical sensitivity of an enzymatic assay into [E(o)]/K(m)-dependent and temporal components.

Roles of mitogen activated protein kinases and EGF receptor in arsenite-stimulated matrix metalloproteinase-9 production

The dermatotoxicity of arsenic is well established and epidemiological studies identify an increased incidence of keratinocytic tumors (basal cell and squamous cell carcinoma) associated with arsenic exposure. Little is known about the underlying mechanisms of arsenic-mediated skin carcinogenesis, but activation of mitogen-activated protein (MAP) kinases and subsequent regulation of downstream target genes may contribute to tumor promotion and progression. In this study, we investigated activation of the extracellular signal regulated kinase (ERK) and the stress-associated kinase p38 by arsenite in HaCat cells, a spontaneously immortalized human keratinocyte cell line. Arsenite concentrations > or =100 microM stimulate rapid activation of p38 and ERK MAP kinases. However, upon extended exposure (24 h), persistent stimulation of p38 and ERK MAP kinases was detected at low micromolar concentrations of arsenite. Although ERK and p38 were activated with similar time and concentration dependence, the mechanism of activation differed for these two MAP kinases. ERK activation by arsenite was fully dependent on the catalytic activity of the epidermal growth factor (EGF) receptor and partially dependent on Src-family kinase activity. In contrast, p38 activation was independent of EGF receptor or Src-family kinase activity. Arsenite-stimulated MAP kinase signal transduction resulted in increased production of matrix metalloproteinase (MMP)-9, an AP-1 regulated gene product. MMP-9 induction by arsenite was prevented when EGF receptor or MAP kinase signaling was inhibited. These studies indicate that EGF receptor activation is a component of arsenite-mediated signal transduction and gene expression in keratinocytes and that low micromolar concentrations of arsenite stimulate key signaling pathways upon extended exposure. Stimulation of MAP kinase cascades by arsenic and subsequent regulation of genes including c-fos, c-jun, and the matrix degrading proteases may play an important role in arsenic-induced skin carcinogenesis.

Female preclinical presenilin-1 mutation carriers unaware of their genetic status have higher levels of depression than their non-mutation carrying kin

OBJECTIVES

To study depressive symptoms in preclinical presenilin-1 (PS1) related Alzheimer's disease.

METHODS

Participants were 33 Mexican women at risk for inheriting PS1 mutations who were not demented. They were interviewed, underwent cognitive testing, and completed the Beck depression inventory (BDI). PS1 mutation status was determined. Mean BDI scores were compared between PS1 mutation carriers and non-carriers. The percentage of subjects who reported seeing a psychiatric professional, and the percentage complaining of memory loss were compared between groups. Regression analysis was used to determine whether mutation status predicted BDI scores after adjusting for age, education, mini-mental state examination, and subjective memory function.

RESULTS

PS1 mutation carriers (n = 17) scored significantly higher than non-carriers (n = 16) on the BDI (mean score, 14.4 v 6.5, p = 0.017); 24% of mutation carriers and 12.5% of non-carriers admitted having sought help from a psychiatric professional (NS). Mutation status remained a significant predictor of BDI scores after adjusting for potential covariates. Though not demented, mutation carriers tended to score lower than non-carriers on several neuropsychological tests.

CONCLUSIONS

Depressive symptoms can occur early in the course of PS1 related Alzheimer's disease, at least in women. This supports the hypothesis that depression may occur as a direct result of the neuropathology underlying Alzheimer's disease.

[Epidemic dermatits by Paederus irritans in Piura, Perú at 1999, related to El Niño phenomenon]

The phenomen El Niño that affected Peru at 1998, made possible the growth of copious vegetation in traditionally dry places. On this way, Paederus irritans, dipterous of the order Coleoptera that produces dermatitis when croushed on the skin, found substract that allowed the natural growth of its population. The coming of occasional rains on the months of February to April 1999, attacked the habitat of this insect, that looked for urban areas, exposing seriously the general population of Piura on north Perú to the contact. During February and May 1,451 cases of dermatitis caused by Paederus irritans, called latigazo because of its linear and eritematous characteristic lesions on the skin, were notified at Piura. The more affected body areas were head (56.6%) and neck (30.9%), but there were also cases of conjunctivitis and genital injuries, because of hands contamination.

Intrahepatic hepatitis C virus replication is increased in patients with regular alcohol consumption

AIMS

To assess clinical significance of liver hepatitis C virus RNA levels and their relationship with epidemiological, biochemical and histological factors.

METHODS

A total of 50 patients (mean age 35.5+/-7 years) with biopsy-proven chronic hepatitis C infection were recruited. Risk factors were drug abuse (n=21), transfusion (n=16), other parental routes (n=8; surgery=3, tattooing=5), and idiopathic (n=5). Duration of infection was 16+/-9 years. All patients showed abnormal alanine aminotransferase levels and positive serum hepatitis C virus RNA. Hepatitis C virus genotype was assessed by Inno-Lipa. Liver biopsy was performed for histology and for hepatitis C virus RNA quantification by Amplicor-HCV-Monitor Daily alcohol consumption was recorded on two occasions by anamnesis. Inflammation grade was mild (n=31) or severe (n=19). Fibrosis was early stage (n=42) or advanced (n=8).

RESULTS

Mean hepatitis C virus RNA levels were 9.4x10(5)+/-1.5x10(6) copies/microg of total RNA in liver tissue, and 9.1x10(5)+/-1.3x10(6) copies/ml in serum. Viral load in liver was positively correlated with that in serum (r=0.51, p<0.001) and there was a significant relationship between daily alcohol consumption and intrahepatic hepatitis C virus burden (r=0.53; p<0.001). Patients infected with genotype 3a showed lower intrahepatic hepatitis C virus load than patients infected with genotype 1b; albeit without reaching statistical significance (0.49x10(6)+/-0.89x10(6) vs 1.44x10(6)+/-1.9x10(6) copies/microg of total RNA; p=NS). No relationships were observed between liver viral burden and age, risk factor status, duration of infection, ferritin and alanine aminotransferase levels or with grading and staging.

CONCLUSIONS

Hepatitis C virus load in serum is a mirror of intrahepatic hepatitis C virus levels. Chronic alcohol consumption enhances intrahepatic hepatitis C virus concentration.

Frequency of twinning in two Costa Rican ethnic groups: an update

Variation in the frequency of twinning among human populations has been presumed to reflect genetic differences. It has been commonly reported that populations of African ancestry have the highest, those of Asian ancestry the lowest, and those of European and Middle-Eastern ancestry intermediate frequencies of twinning. Populations from the Americas have been reported to have intermediate twinning frequencies, presumably reflecting their admixture. In this context, Madrigal (1994. Am J Hum Biol 6:215-218) reported virtually identical (and high) twinning frequencies in two Costa Rican ethnic groups, one of African, the other of Euro-Amerindian ancestry. These frequencies were interpreted in light of frequent inter-ethnic unions, and it was predicted that the two groups would not differ substantially in gene frequencies of several blood enzyme systems. This paper reports the gene frequencies of both groups for such systems. The samples differ significantly for systems that have clearly different frequencies in African and European populations. Given that the groups are actually different in gene frequencies and not homogenous as predicted earlier, the conclusion that twinning frequencies are similar as a result of a similar genetic make up can be questioned. The results challenge the assumption that if populations have similar twinning frequencies it is because they are genetically similar and argue for a stronger environmental component for twinning frequencies.

Ethnicity, gene flow, and population subdivision in Limón, Costa Rica

In this paper we examine the effects of ethnicity on the gene flow between two groups living in Limón, Costa Rica. Our main interest is to determine if ethnicity has acted as a barrier to the exchange of genes, and if the groups have remained distinct genetically. We report the admixture estimates, F(st) values, and inbreeding coefficients of the two samples. The data consist of blood samples and surnames obtained from 375 individuals. The subjects' two surnames were analyzed to determine the ethnicity of their parents (individuals carry their father's and mother's first surnames). We used the formula of Crow and Mange ([1965] Eugen Q 12:199-203) to compute F(t), F(n), and F(r) with the surnames. Admixture estimates were computed for both groups using the computer program ADMIX.PAS kindly provided by Jeffrey Long. The estimates for the Hispanic-Limonense group are M1 = 0.5866 European, M2 = 0.3383 Amerindian, and M3 = 0.0751 African ancestry. For the Afro-Limonense group, the admixture estimates indicate M1 = 0.1047 European, M2 = 0.1357 Amerindian, and M3 = 0.7595 African ancestry. The F(st) values are F(st) = 0.00558 for the Hispanic group and F(st) = 0.05137 for the Afro-Limonense group. These F(st) values indicate that the Afro-Limonense group has experienced more genetic drift than has the other group, possibly as a result of its long history of isolation in Costa Rica. Indeed, when plotted along a scaled eigenvector R matrix of Caribbean gene frequencies, the two Limonense groups did not cluster with each other. Thus we conclude that the two ethnic groups have remained distinct breeding populations.

High-performance liquid chromatography of monoamines on phenyl-bound sorbents using organic free mobile phases

Tryptophan and its metabolites, 5-hydroxytryptophan, 5-hydroxytryptamine, 5-hydroxyindolacetic acid, as well as dopamine, homovanilic acid and 2,3-dihydroxyphenylacetic acid, were separated on phenyl bound silica gel using isocratic elution with phosphate buffer. The method was successfully transferred to several other phenyl HPLC columns from different manufacturers simply by adjusting the pH of the buffer. The method has been validated by the determination of the level of monoamines in rat hypothalamus.

Characterization and distribution of somatostatin binding sites in goldfish brain

Somatostatin (SRIF) binding sites were characterized in goldfish brain. Binding of (125)I-[Tyr(11)]-SRIF-14 to a brain membrane preparation was found to be saturable, reversible, and time-, temperature-, and pH-dependent. Binding was also displaceable by different forms of SRIF. Under optimal conditions (22 degrees C, pH 7.2), the equilibrium binding of (125)I-[Tyr(11)]-SRIF-14 to goldfish brain membranes was achieved after 60 min incubation. Analysis of saturable equilibrium binding revealed a one-site model fit with K(a) of 1.3 nM. SRIF-14, mammalian SRIF-28, and salmon SRIF-25 displaced (125)I-[Tyr(11)]-SRIF-14 binding with similar affinity, whereas other neuropeptides, e.g., substance P, were unable to displace (125)I-[Tyr(11)]-SRIF-14. Autoradiography studies demonstrated that (125)I-[Tyr(11)]-SRIF-14 binding sites are found throughout the goldfish brain. A high density of (125)I-[Tyr(11)]-SRIF-14 binding sites was found in the forebrain, including the nucleus preopticus, nucleus preopticus periventricularis, nucleus anterioris periventricularis, nucleus lateralis tuberis, nucleus dorsomedialis thalami, nucleus dorsolateralis thalami, nucleus ventromedialis thalami, and nucleus diffusus lobi inferioris. In midbrain, (125)I-[Tyr(11)]-SRIF-14 binding sites were found in the optic tectum. The facial and vagal lobes and the mesencephalic-cerebellar tract were found to have a high density of binding sites. This study provides the first characterization and distribution of specific binding sites for SRIF in a fish brain.

APH-1, a POU homeobox gene expressed in the salt gland of the crustacean Artemia franciscana

We characterized the first POU-homeoprotein in a crustacean (designated APH-1 for Artemia POU-Homeoprotein, EMBL Y15070). The amino acid sequence of the APH-1 POU-domain is identical, except for two residues, to that of the two class III POU proteins Cf1-a (Drosophila) and POU-M1 (Bombyx mori). Southern blot analysis suggests that crustaceans have only one class III POU gene. RT-PCR and whole-mount in situ hybridization show that APH-1 mRNA is present in larvae specifically in the salt gland, an organ which is involved in osmoregulation, and disappears in the adult.