Can the modified Allen's test always detect sufficient collateral flow in the hand? A computational study

Blood flow in the largest arteries of the arm up to the digital arteries is numerically modelled using the one-dimensional equations of pressure and flow wave propagation in compliant vessels. The model can be applied to different anatomies of arterial networks and can simulate compression of arteries, these allowing us to simulate the modified Allen's test (MAT) and to assess its suitability for the detection of sufficient collateral flow in the hand if radial blood supply is interrupted. The test measures blood flow in the superficial palmar arch before and during compression of the radial artery. The absence of reversal flow in the palmar arch with the compression indicates insufficient collateral flow and is referred to as a positive MAT. This study shows that small calibres of the superficial palmar arch and insufficient compression of the radial artery can lead to false-positive results. Measurement of the drop in digital systolic pressures with compression of the radial artery has proved to be a more sensitive test to predict the presence of sufficient ulnar collateral flow in networks with small calibres of the superficial palmar arch. However, this study also shows that digital pressure measurements can fail in detecting enough collateral flow if the radial artery is insufficiently compressed.     

Can the modified Allen's test always detect sufficient collateral flow in the hand? A computational study

Blood flow in the largest arteries of the arm up to the digital arteries is numerically modelled using the one-dimensional equations of pressure and flow wave propagation in compliant vessels. The model can be applied to different anatomies of arterial networks and can simulate compression of arteries, these allowing us to simulate the modified Allen's test (MAT) and to assess its suitability for the detection of sufficient collateral flow in the hand if radial blood supply is interrupted. The test measures blood flow in the superficial palmar arch before and during compression of the radial artery. The absence of reversal flow in the palmar arch with the compression indicates insufficient collateral flow and is referred to as a positive MAT. This study shows that small calibres of the superficial palmar arch and insufficient compression of the radial artery can lead to false-positive results. Measurement of the drop in digital systolic pressures with compression of the radial artery has proved to be a more sensitive test to predict the presence of sufficient ulnar collateral flow in networks with small calibres of the superficial palmar arch. However, this study also shows that digital pressure measurements can fail in detecting enough collateral flow if the radial artery is insufficiently compressed.     

Can the false-discovery rate be misleading?

The decoy-database approach is currently the gold standard for assessing the confidence of identifications in shotgun proteomic experiments. Here, we demonstrate that what might appear to be a good result under the decoy-database approach for a given false-discovery rate could be, in fact, the product of overfitting. This problem has been overlooked until now and could lead to obtaining boosted identification numbers whose reliability does not correspond to the expected false-discovery rate. To overcome this, we are introducing a modified version of the method, termed a semi-labeled decoy approach, which enables the statistical determination of an overfitted result.     

Can the Endo Medium be Standardized?

An investigation of various formulae for the Endo medium has been made, using about 20 different samples of basic fuchsia. It has been found that some samples are unsatisfactory in the standard formula of the American Public Health Association and others unsatisfactory in the formula given in the Manual of Methods for Pure Culture Study of Bacteria (of the Society of American Bacteriologists). A slight modification of the A. P. H. A. standard formula, however, is enough to make it satisfactory for any sample of basic fuchsin with which it has so far been tried. This modification is the use of 1 ml. of a 1% basic fuchsin solution instead of 0.5 ml. of a 10% solution. This modification in the formula brings about a change of the ratio of sulfite to fuchsin in the finished medium of 12 1/2:1 instead of roughly 3:1; and it is shown that this ratio permits the use of a greater variety of different fuchsins than the one which is in the standard formula.     

The computational study of the γ-Fe2O3 nanoparticle as Carmustine drug delivery system: DFT approach

In the present study, it is attempted to scrutinize the properties of the maghemite nanoparticle as a Carmustine drug delivery system by means of the density functional theory calculations regarding their geometries, adsorption energies, vibrational frequencies, and topological features of the electron density. Based on the density functional theory results, it is found that the interaction between Carmustine drug molecule and maghemite nanoparticle is weak; so that, the adsorption of the Carmustine drug is typically physisorption. It is also found that the intermolecular hydrogen bonds between the drug and the nanoparticle play the significant role in the stability of the physisorption configurations. The nature of the intermolecular interactions has been explored by calculation of the electron densities and their Laplacian at the bond critical points using Atoms-in-Molecule theory. Moreover, natural bond orbital analysis indicates that the Carmustine molecule can be adsorbed on the nanoparticle surface with a charge transfer from the Carmustine drug to the nanoparticle.     

Can embryo metabolism be used for selecting bovine embryos before transfer?

The quality of in vitro-produced bovine embryos remains variable. The selection of these embryos based only on their morphology does not allow for acceptable gestational rates to be obtained. The use of metabolic markers to select viable embryos before transfer would be of valuable help, both economically and as a research tool. The ideal marker should meet several conditions: it should be able to be evaluated 1) in a totally non-invasive manner, 2) on individual embryos (which necessitates very sensitive techniques), 3) very rapidly (so that it is compatible with the immediate transfer of fresh embryos), and 4) in order to allow viable embryos to be separated from those that are not viable, whatever the production system used. In practice, such a marker does not exist, but certain methods of metabolic evaluation resemble it. The development of a metabolic marker is confronted by the metabolic characteristics of the embryo, notably the evolution of the metabolism during the development of the embryo and its adaptation to the changes in the environment.     

Can neuroscience be integrated into the DSM-V?

To date, the diagnosis of mental disorders has been based on clinical observation, specifically: the identification of symptoms that tend to cluster together, the timing of the symptoms' appearance, and their tendency to resolve, recur or become chronic. The Diagnostic and Statistical Manual of Mental Disorders and the International Classification of Disease, the manuals that specify these diagnoses and the criteria for making them, are currently undergoing revision. It is thus timely to ask whether neuroscience has progressed to the point that the next editions of these manuals can usefully incorporate information about brain structure and function.     

Can the theory of evolution be falsified?

In this paper we discuss the epistemological positions of evolution theories. A sharp distinction is made between the theory that species evolved from common ancestors along specified lines of descent (here called the theory of common descent), and the theories intended as causal explanations of evolution (e.g. Lamarck's and Darwin's theory). The theory of common descent permits a large number of predictions of new results that would be improbable without evolution. For instance, (a) phylogenetic trees have been validated now; (b) the observed order in fossils of new species discovered since Darwin's time could be predicted from the theory of common descent; (c) owing to the theory of common descent, the degrees of similarity and difference in newly discovered properties of more or less related species could be predicted. Such observations can be regarded as attempts to falsify the theory of common descent. We conclude that the theory of common descent is an easily-falsifiable & often-tested & still-not-falsified theory, which is the strongest predicate a theory in an empirical science can obtain. Theories intended as causal explanations of evolution can be falsified essentially, and Lamarck's theory has been falsified actually. Several elements of Darwin's theory have been modified or falsified: new versions of a theory of evolution by natural selection are now the leading scientific theories on evolution. We have argued that the theory of common descent and Darwinism are ordinary, falsifiable scientific theories.     

Can zebrafish be used as a model to study the neurodevelopmental causes of autism?

The zebrafish has proven to be an excellent model for analyzing issues of vertebrate development. In this review we ask whether the zebrafish is a viable model for analyzing the neurodevelopmental causes of autism. In developing an answer to this question three topics are considered. First, the general attributes of zebrafish as a model are discussed, including low cost maintenance, rapid life cycle and the multitude of techniques available. These techniques include large-scale genetic screens, targeted loss and gain of function methods, and embryological assays. Second, we consider the conservation of zebrafish and mammalian brain development, structure and function. Third, we discuss the impressive use of zebrafish as a model for human disease, and suggest several strategies by which zebrafish could be used to dissect the genetic basis for autism. We conclude that the zebrafish system could be used to make important contributions to understanding autistic disorders.     

Can intact liposomes be absorbed in the gut?

Inulin, EDTA, or maltose were given intragastrically to mice, either free or entrapped in mono-shell liposomes of egg phosphatidylcholine or the non-digestible diether and dialkyl analog of phosphatidylcholine. Results indicate that liposomes may protect a drug from premature digestion but cannot carry it through the intestinal wall.     

Can egg donor selection be improved? - a pilot study

Background

Accurate assessments of ovarian reserve (OR) in egg donor candidates are crucial for maximal donor selection. This study assesses whether recently reported new methods of OR assessment by age-specific (as-), rather than non-as (nas-) hormones, follicle stimulating hormone (FSH) and anti-Müllerian hormone (AMH), and triple nucleotide (CGG) repeats on the FMR1 (fragile X) gene have the potential of improving egg donor selection.

Methods

Seventy-three consecutive egg donor candidates (candidates), amongst those 21 who reached egg retrieval (donors), were prospectively investigated for as-FSH, as-AMH and number of CGG repeats. Abnormal findings were assessed in candidates and donors and oocyte yields in the latter were statistically associated with abnormal FSH and AMH (>/< 95% CI of as-levels) and with normal/abnormal numbers of CGG repeats (normal range 26-32).

Results

Amongst candidates mean as-AMH was 3.8 +/- 2.8 ng/mL (37.0% normal, 3.0 +/- 0.7 ng/mL; 26.6% low, 1.5 +/- 0.5 ng/mL; and 37.0% high, 5.8 +/- 2.2 ng/mL). AMH among donors was 4.2 +/- 1.7 ng/mL (33.3% normal, 14.3% low, and 52.4% high), yielding 17.8 +/- 7.2 oocytes, 42.9% in normal range (10-15), 9.5% in low (less than or equal to 9) and 47.6.% in high range (16-32). Candidates in 41.9% and donors in 38.1% demonstrated normal CGG counts; the remained were mostly heterozygous abnormal.

Discussion

Prospective assessment of even carefully prescreened candidates and donors still demonstrates shortcomings on both ends of the OR spectrum. Utilization of ovarian reserve testing methods, like as-hormones and CGG repeats on the FMR1 gene have potential of improving candidate selections.

     

Can the immune system be harnessed to repair the CNS?

Experimental and clinical data have demonstrated that activating the immune system in the CNS can be destructive. However, other studies have shown that enhancing an immune response can be therapeutic, and several clinical trials have been initiated with the aim of boosting immune responses in the CNS of individuals with spinal cord injury, multiple sclerosis and Alzheimer's disease. Here, we evaluate the controversies in the field and discuss the remaining scientific challenges that are associated with enhancing immune function in the CNS to treat neurological diseases.     

Can indicator species predict restoration outcomes early in the monitoring process? a case study with peatlands

Success in ecological restoration is rarely assessed rigorously due to insufficient planning for post-restoration monitoring programs, limited funding and, especially, lack of scientifically validated evaluation criteria and protocols. In this article, we propose the use of the Indicator Value Index technique (IndVal), which statistically determines the association of species to one or several particular site types, to obtain indicators of success at the early stages of the recovery process in restoration projects. Peat bogs extracted by the vacuum method, subsequently restored by a moss-transfer technique and regularly monitored for ~10 years were used as a model system to test this approach. We first identified 34 restored sectors of ~10 ha from 4 to 11 years old in twelve eastern-Canadian bogs. These sectors were then classified according to their degree of success in recovering a typical sphagnum moss carpet (restoration goal). Then, we retrospectively reviewed vegetation communities recorded at the third year after restoration to identify indicator species of different categories of restoration success, using the IndVal methodology. By identifying early indicator species, our method provides a tool that guides intervention soon after restoration if a site is not on a desired successional trajectory. Typical bog species, namely the bryophytes S. rubellum and Mylia anomala and the tree Picea mariana, were indicative of successful restoration; while bare peat, lichens and one species of ericaceous shrubs (Empetrum nigrum), which cope better under drier conditions, indicated sites where restoration failed. A surprising finding was that the moss Polytrichum strictum, which is known to facilitate the colonization of sphagnum in disturbed peatlands, is an early indicator of unsuccessful restoration. This finding made us question the nursing role of P. strictum at a cover threshold above ca. 30%, when P. strictum could be outcompeting sphagnum and become dominant. We conclude that the IndVal method is an effective tool to identify early indicators of restoration success when combined with a thoughtful examination of species frequency and cover within each site type.     

Can the meaning of multiple words be integrated unconsciously?

What are the limits of unconscious language processing? Can language circuits process simple grammatical constructions unconsciously and integrate the meaning of several unseen words? Using behavioural priming and electroencephalography (EEG), we studied a specific rule-based linguistic operation traditionally thought to require conscious cognitive control: the negation of valence. In a masked priming paradigm, two masked words were successively (Experiment 1) or simultaneously presented (Experiment 2), a modifier (‘not’/‘very’) and an adjective (e.g. ‘good’/‘bad’), followed by a visible target noun (e.g. ‘peace’/‘murder’). Subjects indicated whether the target noun had a positive or negative valence. The combination of these three words could either be contextually consistent (e.g. ‘very bad - murder’) or inconsistent (e.g. ‘not bad - murder’). EEG recordings revealed that grammatical negations could unfold partly unconsciously, as reflected in similar occipito-parietal N400 effects for conscious and unconscious three-word sequences forming inconsistent combinations. However, only conscious word sequences elicited P600 effects, later in time. Overall, these results suggest that multiple unconscious words can be rapidly integrated and that an unconscious negation can automatically ‘flip the sign’ of an unconscious adjective. These findings not only extend the limits of subliminal combinatorial language processes, but also highlight how consciousness modulates the grammatical integration of multiple words.     

Can herbivores sharing the same host plant be mutualists?

Resource partitioning is considered to be a prerequisite for coexisting species to evolve from competition to mutualism. This is uniquely different for two major pest insects of rice. These herbivores preferentially opt to coinfest the same host plants, and through plant-mediated mechanisms, cooperatively utilize these plants in a mutualistic manner.     

The aging process: where are the drug opportunities?

New data support a role for growth hormone secretagogue receptor agonists as rejuvenating agents. Two enzymes critical for the formation of beta-amyloid plaques in Alzheimer's disease have been identified. Estrogen receptor beta continues to emerge as a potential drug target. The orphan nuclear receptor Nurr1 appears to be a target for treatment of Parkinson's disease, and propargylamines are emerging as inhibitors of oxidative damage in neurons.     

Can functional regions of proteins be predicted from their coding sequences? The case study of G-protein coupled receptors

A filter based on a set of unsupervised neural networks trained with a winner-take-all strategy discloses signals along the coding sequences of G-protein coupled receptors. By comparing with the existing experimental data it appears that these signals correlate with putative functional domains of the proteins. After protein alignment within subfamilies, signals cluster in protein regions which, according to the presently available experimental results, are described as possible functional domains of the folded proteins. The mapping procedure reveals characteristic regions in the coding sequences common and/or characteristic of the receptor subtype. This is particularly noticeable for the third cytoplasmic loop, which is likely to be involved in the molecular coupling of all the subfamilies with G-proteins. The results indicate that our mapping can highlight intrinsic representative features of the coding sequences which, in the case of G-protein coupled receptors, are characteristic of protein functional regions and suggest a possible application of the filter for predicting functional determinants in proteins starting from the coding sequence.