다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Astrocytes are specialized glial cells that outnumber neurons by over fivefold. They contiguously tile the entire central nervous system (CNS) and exert many essential complex functions in the healthy CNS. Astrocytes respond to all forms of CNS insults through a process referred to as reactive astrogliosis, which has become a pathological hallmark of CNS structural lesions. Substantial progress has been made recently in determining functions and mechanisms of reactive astrogliosis and in identifying roles of astrocytes in CNS disorders and pathologies. A vast molecular arsenal at the disposal of reactive astrocytes is being defined. Transgenic mouse models are dissecting specific aspects of reactive astrocytosis and glial scar formation in vivo. Astrocyte involvement in specific clinicopathological entities is being defined. It is now clear that reactive astrogliosis is not a simple all-or-none phenomenon but is a finely gradated continuum of changes that occur in context-dependent manners regulated by specific signaling events. These changes range from reversible alterations in gene expression and cell hypertrophy with preservation of cellular domains and tissue structure, to long-lasting scar formation with rearrangement of tissue structure. Increasing evidence points towards the potential of reactive astrogliosis to play either primary or contributing roles in CNS disorders via loss of normal astrocyte functions or gain of abnormal effects. This article reviews (1) astrocyte functions in healthy CNS, (2) mechanisms and functions of reactive astrogliosis and glial scar formation, and (3) ways in which reactive astrocytes may cause or contribute to specific CNS disorders and lesions.

/pdf/astrocytes-biology-and-pathology-2hq13zf0bo.pdf

Astrocytes: biology and pathology

Structural information on nanometer-sized gold particles has been limited, due in part to the problem of preparing homogeneous material. Here we report the crystallization and x-ray structure determination of a p-mercaptobenzoic acid (p-MBA)-protected gold nanoparticle, which comprises 102 gold atoms and 44 p-MBAs. The central gold atoms are packed in a Marks decahedron, surrounded by additional layers of gold atoms in unanticipated geometries. The p-MBAs interact not only with the gold but also with one another, forming a rigid surface layer. The particles are chiral, with the two enantiomers alternating in the crystal lattice. The discrete nature of the particle may be explained by the closing of a 58-electron shell.

http://science.sciencemag.org/content/sci/318/5849/430.full.pdf

Structure of a thiol monolayer-protected gold nanoparticle at 1.1 A resolution

MUCKE aims to mine a large volume of images, to structure them conceptually and to use this conceptual structuring in order to improve large-scale image retrieval. The last decade witnessed important progress concerning low-level image representations. However, there are a number problems which need to be solved in order to unleash the full potential of image mining in applications. The central problem with low-level representations is the mismatch between them and the human interpretation of image content. This problem can be instantiated, for instance, by the incapability of existing descriptors to capture spatial relationships between the concepts represented or by their incapability to convey an explanation of why two images are similar in a content-based image retrieval framework. We start by assessing existing local descriptors for image classification and by proposing to use co-occurrence matrices to better capture spatial relationships in images. The main focus in MUCKE is on cleaning large scale Web image corpora and on proposing image representations which are closer to the human interpretation of images. Consequently, we introduce methods which tackle these two problems and compare results to state of the art methods. Note: some aspects of this deliverable are withheld at this time as they are pending review. Please contact the authors for a preview.

http://ieeexplore.ieee.org/iel2/4524/12820/00592460.pdf

Image Processing

measures. RESULTS. The five input factors that had the largest influence across all outcome measures were, in ranked order: stiffness of the sclera, radius of the eye, stiffness of the lamina cribrosa, IOP, and thickness of the scleral shell. The five least influential factors were, in reverse ranked order: retinal thickness, peripapillary rim height, cup depth, cup-to-disc ratio, and pial thickness. Factor ranks were similar for various outcome measure groups and factor ranges. CONCLUSIONS. The model predicts that ONH biomechanics are strongly dependent on scleral biomechanical properties. Acute deformations of ONH tissues, and the consequent high levels of neural tissue strain, were less strongly dependent on the action of IOP directly on the internal surface of the ONH than on the indirect effects of IOP on the sclera. This suggests that interindividual variations in scleral properties could be a risk factor for the development of glaucoma. Eye size and lamina cribrosa biomechanical properties also have a strong influence on ONH biomechanics. (Invest Ophthalmol Vis Sci. 2005;46: 4189‐4199) DOI:10.1167/iovs.05-0541

http://www.ocularbiomechanics.com/pdfs/Sigal2005_IOVS.pdf

Factors influencing optic nerve head biomechanics.

METHODS. Several models of the optic nerve head tissues (preand postlaminar neural tissue, lamina cribrosa, central retinal vessel, sclera, and pia mater) were constructed. Stresses, deformations, and strains were computed using finite element modeling for a range of normal and elevated intraocular pressures. Computed retinal surface deformations were compared with measured deformation patterns in enucleated human eyes. A sensitivity analysis was performed in which tissue properties and selected geometric features were varied. RESULTS. Acute IOP-induced deformation of the vitreoretinal interface was highly dependent on optic cup shape but showed a characteristic “W-shaped” profile that did not match the deformation of the anterior surface of the lamina cribrosa. The central retinal vasculature had surprisingly little effect on optic nerve head biomechanics. At an IOP of 50 mm Hg, strains (fractional elongation) in the lamina cribrosa averaged 4% to 5.5%, dependent on model geometry, with maximum strains up to 7.7%. Strains in the lamina cribrosa were more dependent on scleral stiffness, scleral thickness, and scleral canal diameter than on lamina cribrosa stiffness and optic cup shape. CONCLUSIONS. Computed levels of strain in the lamina cribrosa are biologically significant and capable of contributing to the development of glaucomatous optic neuropathy, even without considering the probable accentuating effect of the lamina cribrosa’s microarchitecture. Depending on optic cup shape, IOP-induced deformation of the vitreoretinal interface may not match lamina cribrosa deformation. This finding implies that scanning laser tomography has limited ability to estimate lamina cribrosa deformation when imaging the anterior topography of the optic nerve head. Biomechanical effects in the lamina cribrosa depend strongly on scleral properties. (Invest Ophthalmol Vis Sci. 2004;45:4378‐4387) DOI:10.1167/ iovs.04-0133

http://www.ocularbiomechanics.com/pdfs/Sigal2004_IOVS.pdf

Finite element modeling of optic nerve head biomechanics.

http://www.ocularbiomechanics.com/pdfs/Sigal2009_EXER_Review.pdf

Biomechanics of the optic nerve head.

Glaucoma is recognized as a progressive optic neuropathy, therefore accurate characterization of changes at the optic nerve head (ONH) as well as at the retinal nerve fiber layer (RNFL) is of central importance in the management of glaucoma. Although evaluation of the ONH and RNFL by stereoscopic ophthalmoscopy remains the mainstay of clinical assessment, a role for semiautomated imaging devices has been increasingly recognized. Although much emphasis has been placed on using such devices to assist the clinician in discriminating between a normal optic disc and an abnormal or glaucomatous disc at presentation, a perhaps more useful application lies in their ability to detect longitudinal change. To date, most longitudinal imaging studies have used confocal scanning laser tomography (CSLT), in particular, the Heidelberg Retina Tomograph (HRT, Heidelberg Engineering, Heidelberg, Germany), either by measuring changes in surface height (topographical change analysis [TCA]) or changes in the neuroretinal rim area.1–3 Progressive nerve fiber layer loss has also been reported in glaucoma subjects based on measurements by time domain optical coherence tomography (TDOCT),4,5 and more recently, longitudinal RNFL changes have been documented by scanning laser polarimetry (SLP).6 It should be noted, however, that the preponderance of longitudinal imaging studies using the CSLT, as opposed to other imaging modalities, reflects the length of time CSLT has been available compared with newer techniques. This remains a central problem; as development and improvement in imaging hardware and software tend to occur at a more rapid rate than the evaluation of their ability to detect longitudinal change.

One approach, which may help establish a new device's ability to detect longitudinal change, is the use of an experimental glaucoma (EG) model. In the case of the nonhuman primate model, the experimental neuropathy is largely clinically indistinguishable from that observed in human glaucoma, and the changes observed develop over the course of months rather than years or decades, as in humans. The ONH of the rhesus macaque has an anatomy similar to that of the human, in particular the presence of a connective tissue lamina cribrosa. In our laboratory, we have used these anatomic similarities to explore structural changes at the earliest stages of EG optic neuropathy using postmortem 3D histomorphometric ONH reconstructions.7,8 Our postmortem studies suggest that the structural ONH abnormalities occurring at the earliest stages of the experimental neuropathy include posterior displacement of the lamina cribrosa, thickening of the lamina cribrosa, a widening of the scleral canal opening, and a thickening of the prelaminar tissue.7–9 We believe that these changes may well represent the earliest signs of an ONH in distress from an IOP-related insult, which would make them an important target for detection by in vivo imaging. These anatomic targets, deep from the surface of the cup, are theoretically within the resolution of spectral domain optical coherence tomography (SDOCT). Indeed, one recent report of a cross-sectional examination of a cohort of glaucomatous and ocular hypertensive eyes suggested that the full width of the lamina cribrosa can be detected in human subjects by 3D SDOCT imaging and that thinning of the lamina cribrosa correlates with the decrease in visual field mean deviation.10

The purpose of this study was therefore to investigate whether longitudinal changes deep within the ONH, as well as RNFL and neuroretinal rim changes, are detectable by longitudinal SDOCT imaging in an experimental model of glaucomatous optic neuropathy. We also sought to determine whether deep ONH changes are detectable by SDOCT at the onset of change in ONH surface topography, as detected by CSLT.

/pdf/longitudinal-change-detected-by-spectral-domain-optical-39rcmm6gfs.pdf

Longitudinal change detected by spectral domain optical coherence tomography in the optic nerve head and peripapillary retina in experimental glaucoma.

http://www.ocularbiomechanics.com/pdfs/DownsRobertsSigal_EXER_HernandezTribute_CorrectedProof.pdf

Ian A. Sigal

Papers

Factors influencing optic nerve head biomechanics.

Finite element modeling of optic nerve head biomechanics.

Biomechanics of the optic nerve head.

Longitudinal change detected by spectral domain optical coherence tomography in the optic nerve head and peripapillary retina in experimental glaucoma.

Glaucomatous cupping of the lamina cribrosa: a review of the evidence for active progressive remodeling as a mechanism.