Anatomical structure modeling from medical images

Some clinical applications, such as surgical planning, require volumetric models of anatomical structures represented as a set of tetrahedra. A practical method of constructing anatomical models from medical images is presented. The method starts with a set of contours segmented from the medical images by a clinician and produces a model that has high fidelity with the contours. Unlike most modeling methods, the contours are not restricted to lie on parallel planes. The main steps are a 3D Delaunay tetrahedralization, culling of non-object tetrahedra, and refinement of the tetrahedral mesh. The result is a high-quality set of tetrahedra whose surface points are guaranteed to match the original contours. The key is to use the distance map and bit volume structures that were created along with the contours. The method is demonstrated on computed tomography, MRI and 3D ultrasound data. Models of 170,000 tetrahedra are constructed on a standard workstation in approximately 10s. A comparison with related methods is also provided.     

Protecting the integrity of Rorschach expert witnesses: A reply to Grove and Barden (1999) re: The admissibility of testimony under Daubert/Kumho analyses.

The Rorschach Comprehensive System has been considered by W. M. Grove and R. C. Barden (1999) as inadmissible for expert psychological testimony according to the guidelines from the Daubert (1993), Joiner (1997), and Kumho (1999) decisions. This article refutes W. M. Grove and R. C. Barden's conclusions, arguing that the Rorschach Comprehensive System is (a) testable, (b) valid and reliable, (c) extensively peer reviewed, (d) associated with a reasonable error rate, (e) standardized, (f) accepted by a relevant and substantial scientific community, and (g) appropriate for a wide range of forensic issues. In drawing their negative conclusions, W. A Grove and R. C. Barden overlooked or minimized a substantial body of empirical data supporting the reliability and validity of the Rorschach Comprehensive System and misinterpreted the language and intent of the Supreme Court decisions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bimodal Detection of Proteins by 129Xe NMR and Fluorescence Spectroscopy

A full understanding of biological phenomena involves sensitive and noninvasive detection. Herein, we report the optimization of a probe for intracellular proteins that combines the advantages of fluorescence and hyperpolarized ¹²⁹Xe NMR spectroscopy detection. The fluorescence detection part is composed of six residues containing a tetracysteine tag (−CCXXCC−) genetically incorporated into the protein of interest and of a small organic molecule, CrAsH. CrAsH becomes fluorescent if it binds to the tetracysteine tag. The part of the biosensor that enables detection by means of ¹²⁹Xe NMR spectroscopy, which is linked to the CrAsH moiety by a spacer, is based on a cryptophane core that is fully suited to reversibly host xenon. Three different peptides, containing the tetracysteine tag and four organic biosensors of different stereochemistry, are benchmarked to propose the best couple that is fully suited for the in vitro detection of proteins.     

The paradox of indiscriminate multiculturalism.

Comments on a paper by H. S. Kim, D. K. Sherman, and S. E. Taylor (see record 2008-12151-002) in regards to the consideration of culture, ethnicity, and national origin in the study of individual and group differences and social interactions. Erard claims that their attempt to infer from small, mostly college-student samples examined on a handful of variables in a few dozen studies is ambitious to a fault. The author claims that they have committed a complementary error in supposing that science can discern any distinctive traits or behaviors that accurately apply to a class of some 4 billion people of varying ethnicities and cultural backgrounds. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Liver Transplantation for Colorectal Liver Metastases: Current Management and Future Perspectives

Patients with nonresectable liver metastases from colorectal cancer have few therapeutic options and a dismal prognosis. Although liver transplantation for this indication has historically a poor reputation, recent advances in the field of chemotherapy and immunosuppression have paved the way to revisit the concept. New data have shown promising results that need to be validated in several ongoing clinical trials. Since liver grafts represent a scarce resource, several new tools are being explored to expand the donor pool for this indication. The purpose of this review is to present all current available data and perspectives about liver transplantation for nonresectable liver metastases from colorectal cancer.     

Triangulation mapping of oxidative bursts released by single fibroblasts by amperometry at microelectrodes

It has been previously established that a lesion created by a microcapillary in the membrane of a single aerobic cell (from skin or immune origin) was sufficient to induce a local membrane depolarization and the ensuing release of oxidative bursts. Their kinetic and quantitative features reveal the activity of cell constitutive enzymes, namely, NADPH oxidases and NO synthases, prone to produce rapidly reactive oxygen and reactive nitrogen species. Until now, the spatial resolution provided by microelectrodes has been exploited in this context to characterize the chemical composition of oxidative bursts at several cell types with high collection efficiency. In the present work, spatial features of the oxidative bursts from single human fibroblasts were investigated using a step-by-step geometrical mapping approach. The spatial locations of cell active zones and of the extent of the activated area, when a cell membrane was stressed by a microcapillary's tip of 1-microm radius, have been addressed. On cells of large dimensions such as fibroblasts, ROS and RNS emission originated from a disk surface of the membrane limited to approximately 15-microm radius around the approximately 1-microm hole created by the microcapillary. This experimental result was rationalized through a simple physicochemical model designed to portray the extent of the membrane activated area due to ion concentration variations resulting from the pinhole channel created across the cell membrane. This is consistent with the fact that the activation of constitutive enzymatic complexes (NOX and NOS) is hypothesized to be a consequence of local variations of ion concentrations such as K(+), Na(+) or possibly Ca(2+). Our results showed that the calculated area near the cell membrane where the ion concentration gradients are significant was equivalent to the area of species release measured experimentally.     

Lung metastasis detection and visualization on CT images: a knowledge‐based method

A solution to the problem of lung metastasis detection on computed tomography (CT) scans of the thorax is presented. A knowledge‐based top‐down approach for image interpretation is used. The method is inspired by the manner in which a radiologist and radiotherapist interpret CT images before radiotherapy is planned. A two‐dimensional followed by a three‐dimensional analysis is performed. The algorithm first detects the thorax contour, the lungs and the ribs, which further help the detection of metastases. Thus, two types of tumors are detected: nodules and metastases located at the lung extremities. A method to visualize the anatomical structures segmented is also presented. The system was tested on 20 patients (988 total images) from the Oncology Department of La Chaux‐de‐Fonds Hospital and the results show that the method is reliable as a computer‐aided diagnostic tool for clinical purpose in an oncology department. Copyright © 2002 John Wiley & Sons, Ltd.     

Phosphatidyl myo-inositol mannosides mimics built on an acyclic or heterocyclic core: synthesis and anti-inflammatory properties

Phosphatidyl myo-inositol mannosides (PIMs) are constituents of the mycobacterial cell wall and possess immunomodulatory activities. Certain PIM derivatives have immunoprotective activity and are of interest as anti-inflammatory agents. In order to identify simplified analogues of PIMs that retain this interesting activity, we have prepared a series of new analogues based either on an acyclic or on a heterocyclic scaffold that replaces the inositol moiety, and evaluated these compounds for their inhibition of LPS-induced release of NO and pro-inflammatory cytokines by macrophages. It was found that the inositol moiety can be favourably replaced by an aza-cyclitol (trihydroxy-piperidine) or an oxa-cyclitol (trihydroxy-tetrahydropyran) unit, and that the configuration of the OH-carrying carbons does not play a significant role. The biological activity is reduced if the nitrogen atom is free in the aza-cyclitol unit.     

RNA recognition by the joint action of two nucleolin RNA-binding domains: genetic analysis and structural modeling

The interaction of nucleolin with a short stem-loop structure (NRE) requires two contiguous RNA-binding domains (RBD 1+2). The structural basis for RNA recognition by these RBDs was studied using a genetic system in Escherichia coli. Within each of the two domains, we identified several mutations that severely impair interaction with the RNA target. Mutations that alter RNA-binding specificity were also isolated, suggesting the identity of specific contacts between RBD 1+2 amino acids and nucleotides within the NRE stem-loop. Our data indicate that both RBDs participate in a joint interaction with the NRE and that each domain uses a different surface to contact the RNA. The constraints provided by these genetic data and previous mutational studies have enabled us to propose a three-dimensional model of nucleolin RBD 1+2 bound to the NRE stem-loop.     

MtENOD16 and 20 are members of a family of phytocyanin-related early nodulins

We have identified two single-copy genes from the model legume. Medicago truncatula (MtENOD16 and 20) whose expression can be correlated with early stages of root nodulation and whose predicted coding sequences are partially homologous to both pea/vetch ENOD5 and soybean N315/ENOD55. Database searching and sequence alignment have defined the encoded early nodulins as a distinct sub-family of phytocyanin-related proteins, although the absence of key ligands implies that they are unlikely to bind copper. Molecular modelling based on known phytocyanin structure has been used to predict the 3-dimensional conformation of the principle globular domain of MtENOD16/20. Additional structural features common to both early nodulin and phytocyanin precursors include an N-terminal transit peptide, a highly variable (hydroxy)proline-rich sequence which probably undergoes extensive post-translational modification, and a hydrophobic C-terminal tail.