Karolinska Institutet

About: Karolinska Institutet is a education organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Population & Cancer. The organization has 46212 authors who have published 121142 publications receiving 6008130 citations.

DNA damage-induced apoptosis.

Abstract: Unicellular organisms respond to the presence of DNA lesions by activating cell cycle checkpoint and repair mechanisms, while multicellular animals have acquired the further option of eliminating damaged cells by triggering apoptosis. Defects in DNA damage-induced apoptosis contribute to tumorigenesis and to the resistance of cancer cells to a variety of therapeutic agents. The intranuclear mechanisms that signal apoptosis after DNA damage overlap with those that initiate cell cycle arrest and DNA repair, and the early events in these pathways are highly conserved. In addition, multiple independent routes have recently been traced by which nuclear DNA damage can be signalled to the mitochondria, tipping the balance in favour of cell death rather than repair and survival. Here, we review current knowledge of nuclear DNA damage signalling, giving particular attention to interactions between these nuclear events and apoptotic processes in other intracellular compartments.

C-di-GMP: the dawning of a novel bacterial signalling system

Abstract: Bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) has come to the limelight as a result of the recent advances in microbial genomics and increased interest in multicellular microbial behaviour. Known for more than 15 years as an activator of cellulose synthase in Gluconacetobacter xylinus, c-di-GMP is emerging as a novel global second messenger in bacteria. The GGDEF and EAL domain proteins involved in c-di-GMP synthesis and degradation, respectively, are (almost) ubiquitous in bacterial genomes. These proteins affect cell differentiation and multicellular behaviour as well as interactions between the microorganisms and their eukaryotic hosts and other phenotypes. While the role of GGDEF and EAL domain proteins in bacterial physiology and behaviour has gained appreciation, and significant progress has been achieved in understanding the enzymology of c-di-GMP turnover, many questions regarding c-di-GMP-dependent signalling remain unanswered. Among these, the key questions are the identity of targets of c-di-GMP action and mechanisms of c-di-GMP-dependent regulation. This review discusses phylogenetic distribution of the c-di-GMP signalling pathway in bacteria, recent developments in biochemical and structural characterization of proteins involved in its metabolism, and biological processes affected by c-di-GMP. The accumulated data clearly indicate that a novel ubiquitous signalling system in bacteria has been discovered.

Central D2-Dopamine Receptor Occupancy in Schizophrenic Patients Treated With Antipsychotic Drugs

Abstract: • Using positron emission tomography and the carbon 11—labeled ligand raclopride, central D2-dopamine receptor occupancy in the putamen was determined in psychiatric patients treated with clinical doses of psychoactive drugs. Receptor occupancy in drug-treated patients was defined as the percent reduction of specific carbon 11—raclopride binding in relation to the expected binding in the absence of drug treatment. Clinical treatment of schizophrenic patients with 11 chemically distinct antipsychotic drugs (including both classic and atypical neuroleptics such as clozapine) resulted in a 65% to 85% occupancy of D2-dopamine receptors. In a depressed patient treated with the tricyclic antidepressant nortriptyline, no occupancy was found. The time course for receptor occupancy and drug levels was followed after withdrawal of sulpiride or haloperidol. D2-dopamine receptor occupancy remained above 65% for many hours despite a substantial reduction of serum drug concentrations. In a sulpiride-treated patient, the dosage was reduced in four steps over a nine-week period and a curvilinear relationship was demonstrated between central D2-dopamine receptor occupancy and serum drug concentrations. The results demonstrate that clinical doses of all the currently used classes of antipsychotic drugs cause a substantial blockade of central D2-dopamine receptors in humans. This effect appears to be selective for the antipsychotics, since it was not induced by the antidepressant nortriptyline.

A gene-environment interaction between smoking and shared epitope genes in HLA-DR provides a high risk of seropositive rheumatoid arthritis

Abstract: Objective The main genetic risk factor for rheumatoid arthritis (RA) is the shared epitope (SE) of HLA–DR, while smoking is an important environmental risk factor. We studied a potential gene–environment interaction between SE genes and smoking in the etiology of the 2 major subgroups of RA: rheumatoid factor (RF)–seropositive and RF-seronegative disease. Methods A population-based case–control study involving incident cases of RF-seropositive and RF-seronegative RA (858 cases and 1,048 controls) was performed in Sweden. Cases and controls were classified according to their cigarette smoking status and HLA–DRB1 genotypes. The relative risk of developing RA was calculated for different gene/smoking combinations and was compared with the relative risk in never smokers without SE genes. Results The relative risk of RF-seropositive RA was 2.8 (95% confidence interval [95% CI] 1.6–4.8) in never smokers with SE genes, 2.4 (95% CI 1.3–4.6) in current smokers without SE genes, and 7.5 (95% CI 4.2–13.1) in current smokers with SE genes. Smokers carrying double SE genes displayed a relative risk of RF-seropositive RA of 15.7 (95% CI 7.2–34.2). The interaction between smoking and SE genes was significant, as measured by the attributable proportion due to interaction, which was 0.4 (95% CI 0.2–0.7) for smoking and any SE, and 0.6 (95% CI 0.4–0.9) for smoking and a double SE. Neither smoking nor SE genes nor the combination of these factors increased the risk of developing RF-seronegative RA. Conclusion The disease risk of RF-seropositive RA associated with one of the classic genetic risk factors for immune-mediated diseases (the SE of HLA–DR) is strongly influenced by the presence of an environmental factor (smoking) in the population at risk.