University of Ljubljana

About: University of Ljubljana is a education organization based out in Ljubljana, Slovenia. It is known for research contribution in the topics: Population & Liquid crystal. The organization has 17210 authors who have published 47013 publications receiving 1082684 citations. The organization is also known as: Univerza v Ljubljani.

Cell membrane electroporation- Part 1: The phenomenon

Abstract: Each biological cell, trillions of which build our bodies, is enveloped by its plasma membrane. Composed largely of a bilayer (double layer) of lipids just two molecules thick (about 5 nm), and behaving partly as a liquid and partly as a gel, the cell plasma membrane nonetheless separates and protects the cell from its surrounding environment very reliably and stably. Embedded within the lipid bilayer, also quite stably, are a number of different proteins, some of which act as channels and pumps, providing a pathway for transporting specific molecules across the membrane. Without these proteins, the membrane would be a largely impenetrable barrier. Electrically, the cell plasma membrane can be viewed as a thin insulating sheet surrounded on both sides by aqueous electrolyte solutions. When exposed to a sufficiently strong electric field, the membrane will undergo electrical breakdown, which renders it permeable to molecules that are otherwise unable to cross it. The process of rendering the membrane permeable is called membrane electroporation. Unlike solid insulators, in which an electrical breakdown generally causes permanent structural change, the membrane, with its lipids behaving as a two-dimensional liquid, can spontaneously return to its prebreakdown state. If the exposure is sufficiently short and the membrane recovery sufficiently rapid for the cell to remain viable, electroporation is termed reversible; otherwise, it is termed irreversible. Since its discovery [1]���[3], electroporation has steadily gained ground as a useful tool in various areas of medicine and biotechnology. Today, reversible electroporation is an established method for introducing chemotherapeutic drugs into tumor cells (electrochemotherapy) [4]. It also offers great promise as a technique for gene therapy without the risks caused by viral vectors (DNA electrotransfer) [5]. In clinical medicine, irreversible electroporation is being investigated as a method for tissue ablation (nonthermal electroablation) [6], whereas in biotechnology, it is useful for extraction of biomolecules [7] and for microbial deactivation, particularly in food preservation [8]. This article, the first in a series of three focusing on electroporation, describes the phenomenon at the molecular level of the lipid bilayer, and then proceeds to the cellular level, explaining how exposure of a cell as a whole to an external electric field results in an inducement of voltage on its plasma membrane, its electroporation, and transport thorough the electroporated membrane. The second article will review the most important and promising applications of electroporation, and the third article will focus on the hardware for electroporation (pulse generators and electrodes) and on the need for standards, safety, and certification.

Observation of the DsJ(2317) and DsJ(2457) in B Decays

Abstract: We report the first observation of the B-->(D) over barD(sJ)(2317) and B-->(D) over barD(sJ)(2457) decays based on 123.8x10(6) B (B) over bar events collected with the Belle detector at KEKB. We observe the D-sJ(2317) decay to D(s)pi(0) and the D-sJ(2457) decay to the D(s)(*)pi(0) and D(s)gamma final states. We also set 90% C.L. upper limits for the decays D-sJ(2317)-->D-s*gamma, D-sJ(2457)-->D-s*gamma, D-sJ(2457)-->D(s)pi(0), and D-sJ(2457)-->D(s)pi(+)pi(-).

The CHEMDNER corpus of chemicals and drugs and its annotation principles.

Abstract: The automatic extraction of chemical information from text requires the recognition of chemical entity mentions as one of its key steps. When developing supervised named entity recognition (NER) systems, the availability of a large, manually annotated text corpus is desirable. Furthermore, large corpora permit the robust evaluation and comparison of different approaches that detect chemicals in documents. We present the CHEMDNER corpus, a collection of 10,000 PubMed abstracts that contain a total of 84,355 chemical entity mentions labeled manually by expert chemistry literature curators, following annotation guidelines specifically defined for this task. The abstracts of the CHEMDNER corpus were selected to be representative for all major chemical disciplines. Each of the chemical entity mentions was manually labeled according to its structure-associated chemical entity mention (SACEM) class: abbreviation, family, formula, identifier, multiple, systematic and trivial. The difficulty and consistency of tagging chemicals in text was measured using an agreement study between annotators, obtaining a percentage agreement of 91. For a subset of the CHEMDNER corpus (the test set of 3,000 abstracts) we provide not only the Gold Standard manual annotations, but also mentions automatically detected by the 26 teams that participated in the BioCreative IV CHEMDNER chemical mention recognition task. In addition, we release the CHEMDNER silver standard corpus of automatically extracted mentions from 17,000 randomly selected PubMed abstracts. A version of the CHEMDNER corpus in the BioC format has been generated as well. We propose a standard for required minimum information about entity annotations for the construction of domain specific corpora on chemical and drug entities. The CHEMDNER corpus and annotation guidelines are available at: http://www.biocreative.org/resources/biocreative-iv/chemdner-corpus/