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Search Results: 1 - 10 of 308 matches for " Kakulas Byron "
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A brief history of muscular dystrophy research: A personal perspective
Kakulas Byron
Neurology India , 2008,
Abstract: The field of myology has undergone remarkable changes. From the period of early clinical descriptions and clinical classifications, new knowledge of these disorders has come from the developments of histopathology, enzyme histochemistry and later, immunocytochemistry and electron microscopy. These techniques have enhanced the understanding of the pathophysiology of myopathies at the cellular level. The parallel evolution of molecular genetics has taken the science further not only by way of understanding and accuracy of diagnosis, but has opened up exciting possibilities of modulation of these chronic debilitating diseases. This review gives a personal perspective of the developments in the field of myology.
Matrix metalloproteinases and their inhibitors in human traumatic spinal cord injury
Armin Buss, Katrin Pech, Byron A Kakulas, Didier Martin, Jean Schoenen, Johannes Noth, Gary A Brook
BMC Neurology , 2007, DOI: 10.1186/1471-2377-7-17
Abstract: An immunohistochemical investigation in post mortem samples of control and lesioned human spinal cords was performed. All patients with traumatic SCI had been clinically diagnosed as having "complete" injuries and presented lesions of the maceration type.In the unlesioned human spinal cord, MMP and TIMP immunoreactivity was scarce. After traumatic SCI, a lesion-induced bi-phasic pattern of raised MMP-1 levels could be found with an early up-regulation in macrophages within the lesion epicentre and a later induction in peri-lesional activated astrocytes. There was an early and brief induction of MMP-2 at the lesion core in macrophages. MMP-9 and -12 expression peaked at 24 days after injury and both molecules were mostly expressed in macrophages at the lesion epicentre. Whereas MMP-9 levels rose progressively from 1 week to 3 weeks, there was an isolated peak of MMP-12 expression at 24 days. The post-traumatic distribution of the MMP inhibitors TIMP-1, -2 and -3 was limited. Only occasional TIMP immuno-positive macrophages could be detected at short survival times. The only clear induction was detected for TIMP-3 at survival times of 8 months and 1 year in peri-lesional activated astrocytes.The involvement of MMP-1, -2, -9 and -12 has been demonstrated in the post-traumatic events after human SCI. With an expression pattern corresponding largely to prior experimental studies, they were mainly expressed during the first weeks after injury and were most likely involved in the destructive inflammatory events of protein breakdown and phagocytosis carried out by infiltrating neutrophils and macrophages, as well as being involved in enhanced permeability of the blood spinal cord barrier. Similar to animal investigations, the strong induction of MMPs was not accompanied by an expression of their inhibitors, allowing these proteins to exert their effects in the lesioned spinal cord.After traumatic spinal cord injury (SCI), the initial damage to the parenchyma at the lesion s
NG2 and phosphacan are present in the astroglial scar after human traumatic spinal cord injury
Armin Buss, Katrin Pech, Byron A Kakulas, Didier Martin, Jean Schoenen, Johannes Noth, Gary A Brook
BMC Neurology , 2009, DOI: 10.1186/1471-2377-9-32
Abstract: An immunohistochemical investigation in post mortem samples of control and lesioned human spinal cords was performed. All patients with traumatic SCI had been clinically diagnosed as having "complete" injuries and presented lesions of the maceration type.In sections from control spinal cord, NG2 immunoreactivity was restricted to stellate-shaped cells corresponding to oligodendrocyte precursor cells. The distribution patterns of phosphacan, neurocan and versican in control human spinal cord parenchyma were similar, with a fine reticular pattern being observed in white matter (but also located in gray matter for phosphacan). Neurocan staining was also associated with blood vessel walls. Furthermore, phosphacan, neurocan and versican were present in the myelin sheaths of ventral and dorsal nerve roots axons. After human SCI, NG2 and phosphacan were both detected in the evolving astroglial scar. Neurocan and versican were detected exclusively in the lesion epicentre, being associated with infiltrating Schwann cells in the myelin sheaths of invading peripheral nerve fibres from lesioned dorsal roots.NG2 and phosphacan were both present in the evolving astroglial scar and, therefore, might play an important role in the blockade of successful CNS regeneration. Neurocan and versican, however, were located at the lesion epicentre, associated with Schwann cell myelin on regenerating peripheral nerve fibres, a distribution that was unlikely to contribute to failed CNS axon regeneration. The present data points to the importance of such correlative investigations for demonstrating the clinical relevance of experimental data.The loss of function following human traumatic spinal cord injury (SCI) is often permanent and results in a serious limitation to the patients' quality of life. Despite considerable progress in recent years, the underlying mechanisms responsible for the failure of axonal regeneration after SCI remain only partially understood.At the spinal cord lesion site,
?CUáL ES EL CRECIMIENTO DE LARGO PLAZO DE LA ECONOMíA CHILENA? UNA RESPUESTA FORMAL PARA UNA ANTIGUA PREGUNTA
Idrovo,Byron;
Cuadernos de Economía , 2010,
Abstract: the objective of the present study is to estimate the economy growth rate in the context of full use of the productive resources. time series univariete models, including a deterministic tendency (with mean breaks), and a space-state model that considers a stochastic tendency and a cyclic component, estimated by kalman′s filter were used. the cyclic component is calculated with and without regime chages (markov-switching models), according to friedman′s idea -plucking model. the results indicate that the chilean economy potential growth rate would be greater than 4% annually, accompanied by economic asymmetric cycles.
Advances Towards Personalised Medicine: What is the Cost of Knowing your Genome?
Kimberley Byron
Opticon1826 , 2011, DOI: 10.5334/opt.111110
Abstract: Since the completion of the Human Genome Project (HGP) in 2003, scientists have been working towards making whole genome sequencing a useful clinical diagnostic tool. The aim of many of the big biotechnology companies is to make this technique affordable and accessible so that it can be routinely used to diagnose rare genetic disorders and tailor medical treatment to an individual’s genetic code – a practice called personalised medicine.
Effect of Correlations Between Model Parameters and Nuisance Parameters When Model Parameters are Fit to Data
Byron Roe
Physics , 2013,
Abstract: The effect of correlations between model parameters and nuisance parameters is discussed, in the context of fitting model parameters to data. Modifications to the usual $\chi^2$ method are required. Fake data studies, as used at present, will not be optimum. Problems will occur for applications of the Maltoni-Schwetz \cite{ms} theorem. Neutrino oscillations are used as examples, but the problems discussed here are general ones, which are often not addressed.
Chi-square Fitting When Overall Normalization is a Fit Parameter
Byron Roe
Physics , 2015,
Abstract: The problem of fitting an event distribution when the total expected number of events is not fixed, keeps appearing in experimental studies. In a chi-square fit, if overall normalization is one of the parameters parameters to be fit, the fitted curve may be seriously low with respect to the data points, sometimes below all of them. This problem and the solution for it are well known within the statistics community, but, apparently, not well known among some of the physics community. The purpose of this note is didactic, to explain the cause of the problem and the easy and elegant solution. The solution is to use maximum likelihood instead of chi-square. The essential difference between the two approaches is that maximum likelihood uses the normalization of each term in the chi-square assuming it is a normal distribution, 1/sqrt(2 pi sigma-square). In addition, the normalization is applied to the theoretical expectation not to the data. In the present note we illustrate what goes wrong and how maximum likelihood fixes the problem in a very simple toy example which illustrates the problem clearly and is the appropriate physics model for event histograms. We then note how a simple modification to the chi-square method gives a result identical to the maximum likelihood method.
Fitting theory to data in the presence of background uncertainties
Byron Roe
Physics , 2014,
Abstract: When fitting theory to data in the presence of background uncertainties, the question of whether the spectral shape of the background happens to be similar to that of the theoretical model of physical interest has not generally been considered previously. These correlations in shape are considered in the present note and found to make important corrections to the calculations. The discussion is phrased in terms of $\chi^2$ fits, but the general considerations apply to any fits. Including these new correlations provides a more powerful test for confidence regions. Fake data studies, as used at present, may not be optimum.
Poincaré sections for the horocycle flow in covers of SL(2,R)/SL(2,Z) and applications to Farey fraction statistics
Byron Heersink
Mathematics , 2014,
Abstract: For a given finite index subgroup H of SL(2,Z), we use a process developed by Fisher and Schmidt to lift a Poincar\'e section of the horocycle flow on SL(2,R)/SL(2,Z) found by Athreya and Cheung to the finite cover SL(2,R)/H of SL(2,R)/SL(2,Z). We then use the properties of this section to prove the existence of the limiting gap distribution of various subsets of Farey fractions. Additionally, to each of these subsets of fractions, we extend solutions by Xiong and Zaharescu, and independently Boca, to a Diophantine approximation problem of Erd\H{o}s, Sz\"usz, and Tur\'an.
An effective estimate for the Lebesgue measure of preimages of iterates of the Farey map
Byron Heersink
Mathematics , 2015,
Abstract: Using techniques from infinite ergodic theory, Kessebohmer and Stratmann determined the asymptotic behavior of the Lebesgue measure of sets of the form $F^{-n}[\alpha,\beta]$, where $[\alpha,\beta]\subseteq(0,1]$ and $F$ is the Farey map. In this paper, we provide an effective version of this result, employing mostly basic properties of the transfer operator of the Farey map and an application of Freud's effective version of Karamata's Tauberian theorem.
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