The Ischemic Stroke Genetics Study (ISGS) Protocol

Background  

The molecular basis for the genetic risk of ischemic stroke is likely to be multigenic and influenced by environmental factors. Several small case-control studies have suggested associations between ischemic stroke and polymorphisms of genes that code for coagulation cascade proteins and platelet receptors. Our aim is to investigate potential associations between hemostatic gene polymorphisms and ischemic stroke, with particular emphasis on detailed characterization of the phenotype.     

A comparison of the illness beliefs of people with angina and their peers: a questionnaire study

Background

Systolic compression of a coronary artery by overlying myocardial tissue is termed myocardial bridging. Myocardial bridging usually has a benign prognosis, but some cases resulting in myocardial ischemia, infarction and sudden cardiac death have been reported. We are reporting a case of myocardial bridging which was complicated with acute myocardial infarction associated with inappropriate blood donation.

Case presentation

A 33 year-old-man was admitted to our emergency with acute anteroseptal myocardial infarction after a blood donation. The electrocardiography showed sinus rhythm and was consistent with an acute anteroseptal myocardial infarction. We decided to perform primary percutanous intervention (PCI). Myocardial bridging was observed in the mid segment of the left anterior descending coronary artery on coronary angiogram. PCI was canceled and medical follow up was decided. Blood transfusion was made because he had a deep anemia. A normal hemaglobin level and clinical reperfusion was achieved after ten hours by blood transfusion. At the one year follow up visit, our patient was healthy and had no cardiac complaints.

Conclusions

Myocardial bridging may cause acute myocardial infarction in various clinical conditions. Although the condition in this case caused profound anemia related acute myocardial infarction, its treatment and management was unusual.     

Brassinolide may control aquaporin activities in Arabidopsis thaliana

 It is usually assumed that aquaporins present in the cellular membranes could be an important route in the control of water flux in plants, but evidence for this hypothesis is scarce. In this paper, we report measurements of the osmotic permeability (P _os ) of protoplasts isolated from hypocotyls of wild-type and mutant Arabidopsis thaliana (L.) Heynh. Mutants were affected in their growth and exhibited different sensitivities to the phytohormone, brassinolide. For the two mutants studied (cpd: constitutive photomorphogenesis and dwarfism; bri1: brassinosteroid insensitive), hypocotyl length was correlated to P _os for the protoplasts. Under experimental conditions where hypocotyl growth had ceased, restoration of root, hypocotyl and petiole growth by brassinolide was correlated with an increase in P _os of the hypocotyl protoplasts. We consider that the increase in P _os of the hypocotyl cells was needed because these cells were part of the transcellular water pathway of the plant. This is the first time, to our knowledge, that brassinolide has been shown to be involved in the modification of the water-transport properties of cell membranes. Our results also emphasize the importance of aquaporins and the transcellular pathway in water transport under normal growth conditions. Received: 15 January 2000 / Accepted: 18 May 2000     

Voltage Noise in Acer pseudoplatanus Cells : Basic Cellular Noise and Gramicidin a Induced Noise

The present contribution is devoted to studying the electrical noise of Acer pseudoplatanus cells in culture suspensions. Spontaneous voltage noise of the cells was recorded by means of a microelectrode inserted in the vacuole. The small signal impedance of the cell was measured so that it was possible to study the intensity spectra of the noise. We recorded intensity spectra with cells incubated in 10⁻³ molar gramicidin A. Difference spectra showed characteristics of a channel noise. By using the calculated conductance of gramicidin A in an artificial membrane, and by simplifying assumptions for the ionic transports through plasmalemma and tonoplast, we were able to estimate the electrochemical potential difference for K⁺ ions across the plasmalemma (3.2 ± 1 millivolt).     

Microelectrode Measurements on Red Beet Vacuole : Biological Effect of Na OR NO(3) Ions, Diffusing from the Microelectrode

Glass microelectrodes filled with 3 molar KCl are widely used to measure intracellular potentials and it is usual to try to minimize their electrolyte loss. In these experiments we have used the ionic leak of our microelectrodes, filled with various salt solutions, to introduce a given ion into the red beet vacuole. This allowed us to show that NO₃⁻ ions reduce the magnitude of the current spectral density while they do not change the resistance of the tonoplast. This is true when NO₃⁻ is either added to the external medium or used as the microelectrode filling solution. This can be interpreted by a NO₃⁻ effect on the vacuolar side of the tonoplast, resulting in an inhibition of the ion transporting ATPase. Replacing K⁺ by Na⁺ ions in the medium has no effect on tonoplast resistance (R_s). On the contrary, when ions leaking from the microelectrode are H⁺, Li⁺ or K⁺, R_s is close to 4 kilohm square centimeter, whereas R_s is of the order of 30KΩ square centimeter when Na⁺ are the leaking ions. We also found a possible correlation between the presence of a Lorentzian in the current spectral density (cut-off frequency = 2 hertz) and a Cl⁻ efflux from the vacuole. This could be explained by the existence of Cl⁻ channels on the tonoplast.     

A strategy for finding regions of similarity in complete genome sequences

MOTIVATION: Complete genomic sequences will become available in the future. New methods to deal with very large sequences (sizes beyond 100 kb) efficiently are required. One of the main aims of such work is to increase our understanding of genome organization and evolution. This requires studies of the locations of regions of similarity. RESULTS: We present here a new tool, ASSIRC ('Accelerated Search for SImilarity Regions in Chromosomes'), for finding regions of similarity in genomic sequences. The method involves three steps: (i) identification of short exact chains of fixed size, called 'seeds', common to both sequences, using hashing functions; (ii) extension of these seeds into putative regions of similarity by a 'random walk' procedure; (iii) final selection of regions of similarity by assessing alignments of the putative sequences. We used simulations to estimate the proportion of regions of similarity not detected for particular region sizes, base identity proportions and seed sizes. This approach can be tailored to the user's specifications. We looked for regions of similarity between two yeast chromosomes (V and IX). The efficiency of the approach was compared to those of conventional programs BLAST and FASTA, by assessing CPU time required and the regions of similarity found for the same data set. AVAILABILITY: Source programs are freely available at the following address: ftp://ftp.biologie.ens. fr/pub/molbio/assirc.tar.gz CONTACT: vincens@biologie.ens.fr, hazout@urbb.jussieu.fr