Inhibition of mitochondrial Na+-Ca2+ exchange restores agonist-induced ATP production and Ca2+ handling in human complex I deficiency

Human mitochondrial complex I (NADH:ubiquinone oxidoreductase) of the oxidative phosphorylation system is a multiprotein assembly comprising both nuclear and mitochondrially encoded subunits. Deficiency of this complex is associated with numerous clinical syndromes ranging from highly progressive, often early lethal encephalopathies, of which Leigh disease is the most frequent, to neurodegenerative disorders in adult life, including Leber's hereditary optic neuropathy and Parkinson disease. We show here that the cytosolic Ca2+ signal in response to hormonal stimulation with bradykinin was impaired in skin fibroblasts from children between the ages of 0 and 5 years with an isolated complex I deficiency caused by mutations in nuclear encoded structural subunits of the complex. Inhibition of mitochondrial Na+-Ca2+ exchange by the benzothiazepine CGP37157 completely restored the aberrant cytosolic Ca2+ signal. This effect of the inhibitor was paralleled by complete restoration of the bradykinin-induced increases in mitochondrial Ca2+ concentration and ensuing ATP production. Thus, impaired mitochondrial Ca2+ accumulation during agonist stimulation is a major consequence of human complex I deficiency, a finding that may provide the basis for the development of new therapeutic approaches to this disorder.     

Structure-function relationships of the RNA-dependent RNA polymerase from poliovirus (3Dpol). A surface of the primary oligomerization domain functions in capsid precursor processing and VPg uridylylation

The primary oligomerization domain of poliovirus polymerase, 3Dpol, is stabilized by the interaction of the back of the thumb subdomain of one molecule with the back of the palm subdomain of a second molecule, thus permitting the head-to-tail assembly of 3Dpol monomers into long fibers. The interaction of Arg-455 and Arg-456 of the thumb with Asp-339, Ser-341, and Asp-349 of the palm is key to the stability of this interface. We show that mutations predicted to completely disrupt this interface do not produce equivalent growth phenotypes. Virus encoding a polymerase with changes of both residues of the thumb to alanine is not viable; however, virus encoding a polymerase with changes of all three residues of the palm to alanine is viable. Biochemical analysis of 3Dpol derivatives containing the thumb or palm substitutions revealed that these derivatives are both incapable of forming long fibers, suggesting that polymerase fibers are not essential for virus viability. The RNA binding activity, polymerase activity, and thermal stability of these derivatives were equivalent to that of the wild-type enzyme. The two significant differences observed for the thumb mutant were a modest reduction in the ability of the altered 3CD proteinase to process the VP0/VP3 capsid precursor and a substantial reduction in the ability of the altered 3Dpol to catalyze oriI-templated uridylylation of VPg. The defect to uridylylation was a result of the inability of 3CD to stimulate this reaction. Because 3C alone can substitute for 3CD in this reaction, we conclude that the lethal replication phenotype associated with the thumb mutant is caused, in part, by the disruption of an interaction between the back of the thumb of 3Dpol and some undefined domain of 3C. We speculate that this interaction may also be critical for assembly of other complexes required for poliovirus genome replication.     

Plant RanGAPs are localized at the nuclear envelope in interphase and associated with microtubules in mitotic cells

In animals and yeast, the small GTP-binding protein Ran has multiple functions - it is involved in mediating (i) the directional passage of proteins and RNA through the nuclear pores in interphase cells; and (ii) the formation of spindle asters, the polymerization of microtubules, and the re-assembly of the nuclear envelope in mitotic cells. Nucleotide binding of Ran is modulated by a series of accessory proteins. For instance, the hydrolysis of RanGTP requires stimulation by the RanGTPase protein RanGAP. Here we report the complementation of the yeast RanGAP mutant rna1 with Medicago sativa and Arabidopsis thaliana cDNAs encoding RanGAP-like proteins. Confocal laser microscopy of Arabidopsis plants overexpressing chimeric constructs of GFP with AtRanGAP1 and 2 demonstrated that the fusion protein is localized to patchy areas at the nuclear envelope of interphase cells. In contrast, the cellular distribution of RanGAPs in synchronized tobacco cells undergoing mitosis is characteristically different. Double-immunofluorescence shows that RanGAPs are co-localized with spindle microtubules during anaphase, with the microtubular phragmoplast and the surface of the daughter nuclei during telophase. Co-assembly of RanGAPs with tubulin correlates with these in vivo observations. The detected localization pattern is consistent with the postulated function of plant RanGAPs in the regulation of nuclear transport during interphase, and suggests a role for these proteins in the organization of the microtubular mitotic structures.     

Monitoring the level of complement components during autologous blood stem cell transplantation in patients with malignant lymphomas

The aim of this study was to determine the complement functions, the serum levels of the complement components C3 and C4, and circulating immune complexes during autologous blood stem cell transplantation. Seventeen lymphoma patients receiving transplants between 1997 and 2001 were involved in this study. High-dose chemotherapy with or without total body irradiation was used for conditioning. The transplantation resulted in complete remission without complications in 14 patients. Early relapse developed in one case and two nonrelapsed patients suffered from serious toxic infection early posttransplant. Normal values of CH50, C3, C4, and immune complexes in sera of patients were detected on day –7, before the conditioning (day of transplantation was determined as day 0). After the conditioning, on day –2, the levels of the CH50, C3, and C4 decreased significantly (p<0.05) in all patients compared with the starting values. The CH50, C3, and C4 levels exceeded the starting values in the noninfected patients from day +7. In two patients suffering from toxic infection, significantly elevated complement levels were documented early posttransplant. In the relapsed patient a significant decrease of the complement parameters was documented posttransplant accompanied by a significant elevation in the immune complex level. The results show alteration in the complement parameters during transplantation, but in the complication-free cases this remained within the normal ranges. However, an unusual elevation seemed to be the sign of infection, and the significant decrease seemed to indicate a relapse.     

Estimating an oncogenetic tree when false negatives and positives are present

Human solid tumors are believed to be caused by a sequence of genetic abnormalities arising in the tumor cells. The understanding of these sequences is extremely important for improving cancer treatment. Models for the occurrence of the abnormalities include linear structure and a recently proposed tree-based structure. In this paper we extend the pure oncogenetic tree model by introducing false positive and false negative observations. We state conditions sufficient for the reconstruction of the generating tree. As an example we analyze a comparative genomic hybridization data set and show that addition of the error model significantly improves the ability of the model to describe the data.     

Expression of differentiated functions in dexamethasone-resistant hepatoma cells

Abstract. The expression of liver-specific functions of different dexamethasone-resistant variants derived from a well-differentiated dexamethasone-sensitive Reuber H35 rat hepatoma cell line (Faza 967) was examined during long-term cultivation. The dexamethasone-sensitive Faza 967 cells are characterized by the activity of tyrosine aminotransferase (TAT) and gluconeogenic enzymes, secretion of serum albumin, and the presence of liver isozymes of alcohol dehydrogenase (L-ADH), aldolase (aldolase-B), and five isoenzymes of lactate dehydrogenase (LDH). The hormone-resistant cells undergo a very dramatic change in expression of most liver-specific functions (dedifferentiation) during long-term culture, in contrast to the sensitive cells in which only certain functions (TAT activity, inducibility, and synthesis of serum albumin) exhibit considerable changes. The hormone-dependent growth sensitivity and the expression of other differentiated functions is not controlled in coordinated way in Faza 967 cells. The time course of the expression of liver-specific functions shows that the cells are resistant before they became 'dedifferentiated', i.e., loss of these liver-specific functions is not a prerequisite of the establishment of the hormone-resistant state.     

An Empirical Investigation of Dance Addiction

Although recreational dancing is associated with increased physical and psychological well-being, little is known about the harmful effects of excessive dancing. The aim of the present study was to explore the psychopathological factors associated with dance addiction. The sample comprised 447 salsa and ballroom dancers (68% female, mean age: 32.8 years) who danced recreationally at least once a week. The Exercise Addiction Inventory (Terry, Szabo, & Griffiths, 2004) was adapted for dance (Dance Addiction Inventory, DAI). Motivation, general mental health (BSI-GSI, and Mental Health Continuum), borderline personality disorder, eating disorder symptoms, and dance motives were also assessed. Five latent classes were explored based on addiction symptoms with 11% of participants belonging to the most problematic class. DAI was positively associated with psychiatric distress, borderline personality and eating disorder symptoms. Hierarchical linear regression model indicated that Intensity (ß=0.22), borderline (ß=0.08), eating disorder (ß=0.11) symptoms, as well as Escapism (ß=0.47) and Mood Enhancement (ß=0.15) (as motivational factors) together explained 42% of DAI scores. Dance addiction as assessed with the Dance Addiction Inventory is associated with indicators of mild psychopathology and therefore warrants further research.     

Synthesis and pharmacological characterization of a potent,orally active p38 kinase inhibitor

Inhibitors of the MAP kinase p38 provide a novel approach for the treatment of osteoporosis, inflammatory disorders, and cancer. We have identified N-(3-tert-butyl-1-methyl-5-pyrazolyl)-N'-(4-(4-pyridinylmethyl)phenyl)urea as a potent and selective p38 kinase inhibitor in biochemical and cellular assays. This compound is orally active in two acute models of cytokine release (TNF-induced IL-6 and LPS-induced TNF) and a chronic model of arthritis (20-day murine collagen-induced arthritis).     

An architecture for the autonomic curation of crowdsourced knowledge

Human knowledge curators are intrinsically better than their digital counterparts at providing relevant answers to queries. That is mainly due to the fact that an experienced biological brain will account for relevant community expertise as well as exploit the underlying connections between knowledge pieces when offering suggestions pertinent to a specific question, whereas most automated database managers will not. We address this problem by proposing an architecture for the autonomic curation of crowdsourced knowledge, that is underpinned by semantic technologies. The architecture is instantiated in the career data domain, thus yielding Aviator, a collaborative platform capable of producing complete, intuitive and relevant answers to career related queries, in a time effective manner. In addition to providing numeric and use case based evidence to support these research claims, this extended work also contains a detailed architectural analysis of Aviator to outline its suitability for automatically curating knowledge to a high standard of quality.