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PubMed2006

Convergent and divergent validity of the Gordon Diagnostic System in adults.

The present study examined the convergent and divergent validity of the Gordon Diagnostic System (GDS) as a measure of attention in adults by examining correlations between GDS scores and scores on other attentional and non-attentional measures in 77 veterans (4 women and 73 men) referred for neuropsychological evaluation. Scores on the GDS were neither significantly correlated with scores on other attentional nor non-attentional measures. Participants were then divided into two groups, those who scored lower (<1S.D. below the published normative mean) and higher on the GDS for the Vigilance and Distractibility tasks separately. Participants with lower GDS scores on the Vigilance task performed more poorly on the Trailmaking Test, Part B than those with higher GDS scores. There were no other group differences on tests of attentional or non-attentional functions. These results do not provide strong support for the convergent and divergent validity of the GDS as a measure of attention in adults.

Adult↗

PubMed2004

Margin convergence of the posterior rotator cuff to the biceps tendon.

Massive rotator cuff tears can often be repaired arthroscopically with satisfactory results. Tear pattern recognition, knot security, and loop security are essential in the repair of large and massive rotator cuff tears. In the case of a massive U-shaped tear, with a contracted immobile supraspinatus and a deficient rotator interval, a type of margin convergence technique can be used. This technique allows for the partial closure of the rotator cuff defect along with the proximal advancement of the posterior cuff by securing the posterior leaf of the cuff tendon to the tendon of the long head of the biceps brachii. Because of the mechanical effect of strain reduction in margin convergence, this procedure decreases the strain at the margin of the posterior cuff, thereby protecting its repair to bone. Our goal with this procedure is not to obtain healing of the cuff to the biceps, but to optimize the conditions for healing of the rotator cuff to bone.

Arthroscopy↗

PubMed2004

Esophagocardiac convergence onto thoracic spinal neurons: comparison of cervical and thoracic esophagus.

The aim of this study was to characterize thoracic spinal neurons receiving convergent inputs from the esophagus, heart and somatic receptive fields. Extracellular potentials of single T3-T4 spinal neurons were recorded in pentobarbital anesthetized male rats. Thoracic and cervical esophageal distensions (TED, CED) were produced by water inflation of a latex balloon. A catheter was placed in the pericardial sac to administer bradykinin or a mixture of algogenic chemicals. 96/311 (31%) neurons responded to both TED and intrapericardial chemicals (IC) and 48/177 (27%) neurons responded to both CED and IC. Long-lasting excitatory responses were more frequently encountered (P<0.05) in esophagocardiac spinal neurons responding to TED (T-ECSNs, 62/91) than in neurons responding to CED (C-ECSNs, 23/47). Ninety-one percent of T-ECSNs and 98% of C-ECSNs had somatic fields on chest, axilla and upper back areas. Esophagocardiac convergence on thoracic spinal neurons provided a spinal mechanism that might mediate viscerovisceral nociception and reflexes.

Animals↗

PubMed2005

Chemical library synthesis using convergent approaches.

New strategies are continuously being developed in combinatorial and diversity-oriented synthesis. Convergent design in target-oriented synthesis is commonly employed for construction of complex molecules. In this mini-review, we describe examples of convergent library design and synthesis as well as potential areas for future development.

Combinatorial Chemistry Techniques↗

PubMed2006

Sterol-regulated ubiquitination and degradation of Insig-1 creates a convergent mechanism for feedback control of cholesterol synthesis and uptake.

This paper describes a convergent mechanism for the feedback control of cholesterol synthesis and uptake mediated by SREBPs, membrane bound transcription factors. Endoplasmic reticulum (ER) bound SREBPs form complexes with Scap, a polytopic ER protein. In sterol-overloaded cells, Scap/SREBP binds to Insig-1, which retains the complex in the ER. Upon sterol deprivation, the Scap/SREBP complex dissociates from Insig-1, which is then ubiquitinated on lysines 156 and 158 and degraded in proteasomes. Scap/SREBP moves to the Golgi, where SREBP is processed to liberate a nuclear fragment that activates genes for cholesterol synthesis and uptake and the gene for Insig-1. Ubiquitination is not necessary for release of Scap/SREBP from Insig-1, but it establishes a requirement for synthesis of new Insig-1 for feedback inhibition. When the new Insig-1 and cholesterol converge on Scap, Scap/SREBP binds to Insig-1, preventing ubiquitination. The Insig-1/Scap/SREBP complex accumulates in the ER, ready for liberation when the cell is again sterol deprived.

Animals↗

PubMed2004

Convergent and concurrent validity of the Contemplation Ladder and URICA scales.

This study examined the convergent and concurrent validity of the Contemplation Ladder and the University of Rhode Island Change Assessment (URICA). Intake data of participants recruited into two concurrent studies were analyzed. One group (n=77) had no plans to quit smoking within the next 6 months, while a second group (n=106) had definite plans to quit. The groups did not differ on any demographic variables except employment status. Contemplation Ladder scores for the entire sample (n=183) correlated positively with the URICA Contemplation and Action subscale scores but negatively with Precontemplation subscale scores. The Contemplation Ladder also correlated positively with the URICA Composite score. Additionally, participants seeking to quit within the next 6 months had significantly higher Contemplation Ladder and URICA Contemplation, Action, and Composite scores, but lower Precontemplation scores than participants not seeking to quit. Controlling for employment status did not change the pattern of results. Our findings provide support for the convergent and concurrent validity of these two measures and suggest that the single-item Contemplation Ladder may be a practical alternative to the URICA in certain situations.

Adult↗

PubMed2005

Converging patterns of colorectal cancer mortality in Europe.

Trends in mortality rates from colorectal cancer during the second half of the 20th century were analysed for 21 European countries and grouped in three broad European regions. For each gender, age-standardised (world standard population) mortality rates were computed by the direct method, and joinpoint analysis was used to identify significant changes in rates. A favourable pattern in colorectal cancer mortality for both genders was observed in most European countries from the 1990s onwards. Colorectal cancer mortality rates were still in the upward direction in some Eastern European countries, as well as in some Mediterranean countries. Mortality rates tended to converge at around 20/100000 in men and around 11/100000 in women. This converging pattern is even clearer when colorectal mortality rates are examined in three broad European regions. Similar mortality rates over recent calendar years have been reached by countries where mortality has been decreasing in recent decades and in those countries (mainly Eastern European and Mediterranean countries) which have experienced a recent levelling-off and decrease. If recent trends are maintained, colorectal cancer mortality is likely to decline further in Europe in the current decade.

Adult↗

PubMed2005

Converging patterns in hospital organization: beyond the professional bureaucracy.

This study builds a framework to investigate the current trends emerging in hospital organizational design and its main consequences on human resources management. The analysis derives from an extensive literature review, which shows over the last 30 years a significant lack of works on organization design for hospitals, and from a number of experiences in hospital settings, which provide useful insights on changes taking place in hospitals. We intend to contribute to the filling of the gap in literature created by the lack of interest scholars have shown on hospital organization. The framework we discuss depicts the major converging trends of reorganization that can be observed in hospital contexts of industrialized countries. What we found is that large multi-specialty hospitals--by large we mean hospitals over about 300 beds--located in different countries, though starting from different internal and external organizational and environmental features are mostly converging towards a common design scheme. We labelled that scheme the care-focused hospital and we analysed in-depth its features in the attempt to facilitate cross-national comparison, otherwise difficult due to the fact that organizational concepts are value loaded and tend to be culture-bound. Challenges and managerial implications of this more and more widely diffused organizational paradigm are debated in the last part of the study.

Cross-Cultural Comparison↗

PubMed2004

Convergence of forelimb and hindlimb Natural Pendular Period in baboons (Papio cynocephalus) and its implication for the evolution of primate quadrupedalism.

The patterns of muscle mass distribution along the lengths of limbs may have important effects on the mechanics and energetics of quadrupedalism. Specifically, Myers and Steudel (J. Morphol. 234 (1997) 183) have shown that fore- and hindlimb Natural Pendular Periods (NPPs) may affect quadrupedal kinematics and must converge to reduce locomotor energetic costs. This study quantifies patterns of limb mass distribution in a live sample of Papio cynocephalus using limb inertial properties (mass, center of mass, mass moment of inertia, and radius of gyration). These inertial properties are calculated using a geometric modeling technique similar to that of Crompton et al. (Am. J. phys. Anthrop. 99 (1996) 547). The inertial properties in Papio are compared to those of Canis from Myers and Steudel (J. Morphol. 234 (1997) 183). The Papio sample has convergent fore- and hindlimb NPPs. Additionally, these limb NPPs are relatively large compared to those of Canis due to the relatively distally distributed limb mass in the Papio sample (relatively large limb masses, relatively distal centers of mass and radii of gyration, and relatively large limb mass moments of inertia). This relatively distal limb mass appears related to the grasping abilities of their hands and feet. Causal links are explored between limb shape adaptations for grasping hands and feet and the kinematics of primate quadrupedalism. In particular, if primates in general follow Papio's limb mass distribution pattern, then relatively large limb NPPs may lead to the relatively low stride frequencies already documented for primates. The kinematics of primate quadrupedalism appears to have been strongly influenced by both selection for grasping hands and feet and selection for reduced locomotor energetic costs.

Animals↗

PubMed2006

Simulator performance, microsleep episodes, and subjective sleepiness: normative data using convergent methodologies to assess driver drowsiness.

OBJECTIVE: Our objective was to examine a novel standardized assessment methodology of detecting impaired driving performance due to drowsiness in a normative cohort. METHODS: Thirty-one healthy subjects with no significant sleep, medical, and psychiatric pathology were assessed in a driving simulation paradigm. Thirty-minute simulations were repeated at two-hourly intervals (i.e., at 1000, 1200, 1400, and 1600 h). Convergent data sources included drivers' subjective ratings of sleepiness and alertness, electroencephalogram-verified microsleep (MS) episodes, and a variety of real-time driving simulator performance measures such as speed, lane tracking, reaction time (RT), and off-road events (crashes). RESULTS: Significant diurnal fluctuations were noted on objective measures of RT, velocity, tracking, and MS events, indicating the highest risk of impairment in the afternoon. By contrast, subjective ratings of sleepiness and alertness did not demonstrate significant circadian variation. The mean incidence of MS episodes and crash risk correlated highly (r = .748). CONCLUSIONS: This prospective study demonstrates the relevance of multiple convergent measures for comprehensive assessment. The divergence of subjective and objective assays of impairment implies that healthy individuals may not have full insights into neurophysiologically mediated performance deficits. These results will serve as normative comparators to patients presenting with daytime somnolence and may allow a more accurate prediction of potential crash risk than noninteractive daytime polysomnogram tests such as the mean sleep latency test or the maintenance of wakefulness test.

Accidents, Traffic↗

PubMed2006

How to reach linguistic consensus: a proof of convergence for the naming game.

In this paper we introduce a mathematical model of naming games. Naming games have been widely used within research on the origins and evolution of language. Despite the many interesting empirical results these studies have produced, most of this research lacks a formal elucidating theory. In this paper we show how a population of agents can reach linguistic consensus, i.e. learn to use one common language to communicate with one another. Our approach differs from existing formal work in two important ways: one, we relax the too strong assumption that an agent samples infinitely often during each time interval. This assumption is usually made to guarantee convergence of an empirical learning process to a deterministic dynamical system. Two, we provide a proof that under these new realistic conditions, our model converges to a common language for the entire population of agents. Finally the model is experimentally validated.

Biological Evolution↗

PubMed2004

Convergence of nociceptive information from temporomandibular joint and tooth pulp afferents on C1 spinal neurons in the rat.

The aim of the present study was to test the hypothesis that there is a convergence of afferent inputs from the temporomandibular joint (TMJ) on C1 spinal neurons responding to electrical stimulation of the tooth pulp (TP). In 14 pentobarbital anesthetized rats, the extracellular single unit activity of 31 C1 spinal neurons and the amplitude in a digastric muscle electromyogram (n = 31) increased proportionally during 1.0-3.5 times the threshold for the jaw-opening reflex (JOR). Of 31 C1 spinal neurons responsive to TP afferents, 28 (approximately 90%) were also excited by electrical stimulation of the ipsilateral TMJ capsule. All neurons tested were divided into three categories of nociceptive specific, wide dynamic range and non-responsive as to their responsiveness to mechanical stimuli (pin prick and touch) of the somatic receptive field (skin of the face, neck, jaw and upper forearm) and TMJ capsule. Nineteen (68%) of 28 C1 spinal neurons received nociceptive information from C fibers of the TMJ capsule. These results suggest that there is a convergence of noxious information from the TMJ and TP afferents on the same C1 spinal neurons, which importantly contribute to pain perception from the TMJ region.

Animals↗

PubMed2004

A stochastic model of tumor response to fractionated radiation: limit theorems and rate of convergence.

The iterated birth and death Markov process is defined as an n-fold iteration of a birth and death Markov process describing kinetics of certain population combined with random killing of individuals in the population at moments tau 1,...,tau n with given survival probabilities s1,...,sn. A long-standing problem of computing the distribution of the number of clonogenic tumor cells surviving an arbitrary fractionated radiation schedule is solved within the framework of iterated birth and death Markov process. It is shown that, for any initial population size iota, the distribution of the size N of the population at moment t > or = tau n is generalized negative binomial, and an explicit computationally feasible formula for the latter is found. It is shown that if i --> infinity and sn --> 0 so that the product iota s1...sn tends to a finite positive limit, the distribution of random variable N converges to a probability distribution, which for t = tau n turns out to be Poisson. In the latter case, an estimate of the rate of convergence in the total variation metric similar to the classical Law of Rare Events is obtained.

Cell Survival↗

PubMed2006

Convergence results for contact branching processes.

The link between the multi-type contact birth process and the spatial deterministic S-->I epidemic is exploited to give convergence results for a multi-type Markovian contact branching process. Let U(t) be the position of furthest spread by time t in a specific direction. The asymptotic speed of translation of the distribution function of U(t) is derived and U(t)/t is shown to converge in probability to this speed.

Disease Outbreaks↗

PubMed2004

Versican V2 and the central inhibitory domain of Nogo-A inhibit neurite growth via p75NTR/NgR-independent pathways that converge at RhoA.

Myelin is a major obstacle for regenerating nerve fibers of the adult mammalian central nervous system (CNS). Several proteins including Nogo-A, myelin-associated glycoprotein (MAG), oligodendrocyte myelin glycoprotein (OMgp) and the chondroitin-sulfate proteoglycan (CSPG) Versican V2 have been identified as inhibitory components present in CNS myelin. MAG, OMgp as well as the Nogo specific domain Nogo-66 exert their inhibitory activity by binding to a neuronal receptor complex containing the Nogo-66 receptor NgR and the neurotrophin receptor p75(NTR). While this suggests a converging role of the p75(NTR)/NgR receptor complex for myelin-derived neurite growth inhibitors, we show here that NgR/p75(NTR) is not required for mediating the inhibitory activity of the two myelin components NiG, unlike Nogo-66 a distinct domain of Nogo-A, and Versican V2. Primary neurons derived from a complete null mutant of p75(NTR) are still sensitive to NiG and Versican V2. In line with this result, neurite growth of p75(NTR) deficient neurons is still significantly blocked on total bovine CNS myelin. Furthermore, modulation of RhoA and Rac1 in p75(NTR)-/- neurons persists with NiG and Versican V2. Finally, we demonstrate that neither NiG nor Versican V2 interact with the p75(NTR)/NgR receptor complex and provide evidence that the binding sites of NiG and Nogo-66 are physically distinct from each other on neural tissue. These results indicate not only the existence of neuronal receptors for myelin inhibitors independent from the p75(NTR)/NgR receptor complex but also establish Rho GTPases as a common point of signal convergence of diverse myelin-induced regeneration inhibitory pathways.

Animals↗

PubMed2026

Fructophilic lactic acid bacteria as a window into multi-scale convergent evolution.

Fructophilic lactic acid bacteria (FLAB) are a group of lactic acid bacteria with unique growth characteristics, that is, poor growth on glucose. Their growth is enhanced in the presence of fructose or external electron acceptors. These organisms inhabit fructose-rich environments such as flowers, fruits, and pollinating insects, particularly honey bees. Apilactobacillus spp. and Fructobacillus spp. are representatives of FLAB, although they belong to phylogenetically distant clades. These organisms commonly possess markedly small genomes with a low number of coding DNA sequences. Furthermore, their genomes are characterized by a markedly reduced number of genes involved in carbohydrate transport and metabolism. Genome reduction in FLAB reflects convergent adaptation to fructose-rich environments rather than general genome streamlining. The two distinct FLAB genera, Fructobacillus and Apilactobacillus, independently lost more than 100 genes in statistically similar orders. In contrast, genes involved in carbohydrate and amino acid metabolism exhibited reversed orders of loss between the two genera. Furthermore, FLAB genomes lack an intact bifunctional alcohol/aldehyde dehydrogenase gene (adhE), which causes their poor growth on glucose. A comparative genomic study suggested the evolutionary process underlying adhE gene decay during adaptation to the fructose-rich environments, including pollinating insects. In conclusion, FLAB represent a unique example of habitat-driven convergent reductive evolution that can be investigated across multiple biological scales - from individual genes to whole genomes - in the diverse LAB group with a wide range of habitats, and partially share the fructophilic evolution with eukaryotic yeasts found in fructose-rich habitats.

Fructose↗

PubMed2003

Dorsal closure and convergent extension: two polarised morphogenetic movements controlled by similar mechanisms?

Coordinated cell movements contribute to the shaping of developing organisms during morphogenesis. Understanding the molecular basis of these directed movements is a crucial part of understanding the mechanisms in action during development. We present here a cellular description of two morphogenetic processes: dorsal closure of the Drosophila embryo and convergent extension in two vertebrate models, Xenopus laevis and Danio rerio. Both processes are characterised by polarised cell movements and increasing evidence suggests that they involve a common group of planar cell polarity genes. We propose that the comparison of dorsal closure and convergent extension will shed light on underlying mechanisms that are shared between the two processes.

Animals↗

PubMed2004

Transcriptional interference between convergent promoters caused by elongation over the promoter.

Transcriptional interference with convergent transcription from face-to-face promoters is a potentially important form of gene regulation in all organisms. Using LacZ reporter studies, the mechanism of interference was determined for a pair of face-to-face prokaryotic promoters in which a strong promoter interferes 5.6-fold with a weak promoter, 62 bp away. The promoters were variously rearranged to test different models of interference. Terminating transcription from the strong promoter before it reached the weak promoter dramatically reduced interference, indicating a requirement for the passage of the converging RNAP over the weak promoter. Based on in vitro experiments showing a slow rate of escape for open complexes at the weak promoter and their sensitivity to head-on collisions with elongating RNAP, a "sitting duck" model of interference is proposed and supported with in vivo permanganate footprinting. The model is further supported by the analysis of a second set of prokaryotic face-to-face promoters.

Gene Expression Regulation, Bacterial↗