Cross-national aspects of cyberbullying victimization among 14-17-year-old adolescents across seven European countries.

Background: The increasing use of the Internet and social network sites (SNS) has created a new domain of socio-emotional development for adolescents. The aim of this cross-sectional study was to explore cybervictimization across seven European countries, in relation to socio-demographic, Internet use and psychosocial variables.

Methods: A cross-sectional school-based study was conducted in the participating countries: Germany, Greece, Iceland the Netherlands, Poland, Romania and Spain.

Involvement of the specific nucleolar protein SURF6 in regulation of proliferation and ribosome biogenesis in mouse NIH/3T3 fibroblasts.

The nucleolar proteins which link cell proliferation to ribosome biogenesis are regarded to be potentially oncogenic. Here, in order to examine the involvement of an evolutionary conserved nucleolar protein SURF6/Rrp14 in proliferation and ribosome biogenesis in mammalian cells, we established stably transfected mouse NIH/3T3 fibroblasts capable of conditional overexpression of the protein. Cell proliferation was monitored in real-time, and various cell cycle parameters were quantified based on flow cytometry, Br-dU-labeling and conventional microscopy data.

Lack of the transcription factor C/EBPδ impairs the intrinsic capacity of peripheral neurons for regeneration.

Adult neurons of the peripheral nervous system (PNS), in contrast to those of the central nervous system, have a remarkable capacity to repair themselves after injury, yet the mechanisms underlying this regenerative propensity of peripheral neurons are far from completely understood. Here we show that the transcription factor CCAAT enhancer binding protein delta (C/EBPδ) is necessary for the efficient axonal regeneration of dorsal root ganglia (DRG) neurons after sciatic nerve crush injury. Loss of C/EBPδ substantially impairs axonal growth in dissociated cultured DRG neurons.

Development of novel mouse hybridomas producing monoclonal antibodies specific to human and mouse nucleolar protein SURF-6.

SURF-6 is an evolutionarily conserved nucleolar protein that is important for cell viability; however, its function in mammals still remains uncertain. The aim of this study is to generate monoclonal antibodies to human SURF-6 protein suitable for fundamental and biomedical research. The full-size human SURF-6 was expressed as a recombinant GST-fusion protein and used as an antigen to generate monoclonal antibodies, S79 and S148, specific for SURF-6.

Bioluminescence imaging of the brain response to acute inflammation in living C/EBP reporter mice.

The transcription factor CCAAT enhancer binding protein (C/EBP) is a key regulator of inflammation and immune responses, and recent studies suggest it is involved in inflammatory processes in the nervous system. We generated a transgenic reporter mouse model, carrying the luciferase (luc) gene under the transcriptional control of C/EBP, for visualising C/EBP activity in vivo. Real-time bioluminescence imaging reflecting C/EBP activity was performed in an acute inflammation model, after systemic administration of lipopolysaccharides (LPS), in C/EBP-luc mice.

[The levels of key nucleolar proteins in the lymphoid cells of healthy individuals and patients with lymphoproliferative diseases].

Immunocytochemical staining with specific antibodies was used to study the expression of three nucleolar proteins (fibrillarin, B23/nucleofozmin, and SURF6), which were involved in pRNA maturation, in the lymphoid cells of healthy individuals and patients with lymphoproliferative diseases and to compare it with the expression of the known proliferation marker Ki-67 protein. The results indicated that fibrillarin was detectable at the comparable level in the lymphoid cells of the patients and in the peripheral blood lymphocytes of the healthy individuals. In one fourth of the patients, the proportion of cells containing B23/nucleofozmin was noticeably higher than that in the lymphocytes of donors; however, there was no great difference in patients with different types of the disease.

Development and characterization of Thy*IκBα-SI transgenic mice.

We developed and characterized a new transgenic model where NF-κB activity is inhibited only in mature neurons. Transgenic mouse strain Thy*IκBα-SI was created using trans-dominant super inhibitor NF-κB (IκBα-SI), which is a multimutant form of IκBα inhibitory protein cloned into specific neutral Thy-1.2 cassette.

Posttraumatic activity of signal pathways of nuclear factor κB in mature sensory neurons.

The aim of this study was to clear out whether injury to the peripheral nerve leads to activation of nuclear factor κB in mature spinal ganglia. Analysis of matrix RNA of nuclear factor κB-dependent genes (monocyte chemoattractant protein MCP-1 and inhibitor of nuclear factor κB IκBα) showed different levels of expression of these genes in the spinal ganglia in vivo after axotomy and in vitro after TNF-α stimulation. On the other hand, DNA-binding activity of nuclear factor κB increased in the spinal ganglia 6 h after axotomy and after 10-min incubation of sensory neuron culture with TNF-α.

[Transcriptional activity of nuclear factor kappa B (NFkappaB) in posttraumatic sensory neurons (histochemical study)].

Nuclear factor kappa B (NFkappaB) is a ubiquitous nuclear transcription factor that regulates the expression of a number of genes involved in cell survival, immune and inflammatory processes. It has been hypothesized that after nerve injury, the release of specific cytokines may provide a stimulus for activation of the transcription factor NF-kappaB in adult dorsal root ganglia (DRG) neurons exerting the protective effect on the sensory neurons. However, the complexity of this transcription factor has led to some misleading conclusions about NF-kappaB signalling in injured DRG neurons.

Prediction of novel isoforms of the mouse Mpv17l protein.

The Mpv17l protein has two isoforms, M-LPL and M-LPS, which both regulate the production of reactive oxygen species (ROS) and protect against mitochondrial oxidative stress and apoptosis. M-LPL is ubiquitously expressed, while M-LPS is expressed mostly in the kidney of aged animals. We identified a variety of transcripts of the Mpv17l gene that could encode novel isoforms by mapping expressed sequence tags on the mouse M-LP genomic locus.

Early expression of nucleolar SURF-6 protein in mouse spleen lymphocytes activated for proliferation in vitro.

Using specific antibodies we studied the content of nucleolar SURF-6 protein, which participates in rRNA processing, in mouser spleen lymphocytes activated for proliferation with concanavalin A and compared it with the content of nucleolar nucleophosmin/B23 protein and DNA replication factor PCNA, well-known markers of proliferating cells. Using immunocytochemistry and immunoblotting methods we demonstrate that the concentration of all these proteins increases simultaneously with increasing the proportion of proliferating cells. Unlike nucleophosmin/B23, SURF-6 protein was not revealed in quiescent lymphocyte nucleoli, while the increase of its level in activated lymphocytes preceded elevation of PCNA level.

Observations on the function of nuclear factor kappa B (NF-kappaB) in the survival of adult primary sensory neurons after nerve injury.

Peripheral nerve transections cause much more neuronal death in embryonic and neonatal dorsal root ganglia (DRG) than in adult DRG. Here we used transgenic approaches to examine the hypothesis that NF-kappaB is an important intrinsic factor of adult DRG neurons for their in vivo capacity to survive after nerve injury. We generated transgenic mice expressing the NF-kappaB super-inhibitor (IkappaBalpha-SI), a multi-mutant form of IkappaBalpha, specifically in adult neurons.

SOCS3 suppresses AP-1 transcriptional activity in neuroblastoma cells through inhibition of c-Jun N-terminal kinase.

Transduction and activation of an inducible form of STAT3 (signal transducer and activator of transcription) sufficed to increase VIP (vasoactive intestinal protein) mRNA concentrations in neuroblastoma cells. Overexpression of SOCS3 (suppressor of cytokine signaling) inhibited and mutant SOCS3 (with an inactivating point mutation in amino acid 25) enhanced the induction of VIP mRNA by CNTF (ciliary neurotrophic factor). Because mutant SOCS3 did not augment the increase in STAT transcriptional activity following CNTF stimulation, the enhancement by mutant SOCS3 of the actions of CNTF cannot be attributed to changes in STAT3 signaling.

Actions of neuropoietic cytokines and cyclic AMP in regenerative conditioning of rat primary sensory neurons.

A conditioning lesion to peripheral axons of primary sensory neurons accelerates regeneration of their central axons in vivo or neurite outgrowth if the neurons are grown in vitro. Previous evidence has implicated neuropoietic cytokines and also cyclic AMP in regenerative conditioning. In experiments reported here, delivery through a lentivirus vector of ciliary neurotrophic factor to the appropriate dorsal root ganglion in rats was sufficient to mimic the conditioning effect of peripheral nerve injury on the regeneration of dorsal spinal nerve root axons.

The nucleolar protein SURF-6 is essential for viability in mouse NIH/3T3 cells.

SURF-6 is a bona fide nucleolar protein comprising an evolutionary conserved family that extends from human to yeast. The expression of the mammalian SURF-6 has been recently found to be regulated during the cell cycle. In order to determine the importance of SURF-6 in mammalian cells, we applied the Tet-On system to regulate conditionally, in response to tetracycline, the expression of an antisense RNA (asRNA) that targets Surf-6 mRNA in mouse NIH/3T3 cells.

[Properties and functions of a new nucleolar protein, Surf-6, in 3T3 mouse cells].

The localization of the specific protein Surf-6 from nucleoli of eukaryotic cells in mitosis and its sensitivity to the treatment of cells with RNase A and DNase I in situ were studied. It was shown that, in interphase nucleoli of 3T3 mouse cells, Surf-6 is probably associated with RNA and practically is not associated with DNA. In mitosis, Surf-6 appears in forming nucleoli after the known RNA-binding proteins fibrillarin and B23/nucleofozmin, which are involved in the early and late stages of the assembly of ribosomal particles, respectively.

Hypothalamic growth hormone-releasing hormone (GHRH) deficiency: targeted ablation of GHRH neurons in mice using a viral ion channel transgene.

Animal and clinical models of GHRH excess suggest that GHRH provides an important trophic drive to pituitary somatotrophs. We have adopted a novel approach to silence or ablate GHRH neurons, using a modified H37A variant of the influenza virus M2 protein ((H37A)M2). In mammalian cells, (H37A)M2 forms a high conductance monovalent cation channel that can be blocked by the antiviral drug rimantadine.

Identification of an evolutionary conserved SURF-6 domain in a family of nucleolar proteins extending from human to yeast.

The mammalian SURF-6 protein is localized in the nucleolus, yet its function remains elusive in the recently characterized nucleolar proteome. We discovered by searching the Protein families database that a unique evolutionary conserved SURF-6 domain is present in the carboxy-terminal of a novel family of eukaryotic proteins extending from human to yeast. By using the enhanced green fluorescent protein as a fusion protein marker in mammalian cells, we show that proteins from distantly related taxonomic groups containing the SURF-6 domain are localized in the nucleolus.

Physiological studies of transgenic mice overexpressing growth hormone (GH) secretagogue receptor 1A in GH-releasing hormone neurons.

The type 1A GH secretagogue (GHS) receptor (GHSR) has been proposed to mediate the effects of ghrelin on GH release, food intake, and body composition. We have overexpressed GHSR in GH-producing GC cells and GHRH neurons in an attempt to enhance signaling via this pathway selectively, in the GH axis. Constitutive overexpression of human GHSR in rat GC cell lines resulted in increased basal phosphoinositol turnover and rendered them responsive to GHS ligands.

Growth hormone-releasing hormone (GHRH) neurons in GHRH-enhanced green fluorescent protein transgenic mice: a ventral hypothalamic network.

The hypothalamic GHRH neurons secrete pulses of GHRH to generate episodic GH secretion, but little is known about the mechanisms involved. We have made transgenic mice expressing enhanced green fluorescent protein (eGFP) specifically targeted to the secretory vesicles in GHRH neurons. GHRH cells transported eGFP from cell bodies in the arcuate nucleus to extensively arborized varicose fiber terminals in the median eminence.

Disruption of exon definition produces a dominant-negative growth hormone isoform that causes somatotroph death and IGHD II.

Isolated growth hormone deficiency type II (IGHD II) is characterized by short stature due to dominant-negative mutations of the human growth hormone gene (GH1). Most of the known mutations responsible for IGHD II cause aberrant splicing of GH1 transcripts. We have recently shown that mutations that cause exon 3 skipping and produce a dominant-negative 17.

Autosomal dominant growth hormone deficiency disrupts secretory vesicles in vitro and in vivo in transgenic mice.

Autosomal dominant GH deficiency type II (IGHDII) is often associated with mutations in the human GH gene (GH1) that give rise to products lacking exon-3 ((Deltaexon3)hGH). In the heterozygous state, these act as dominant negative mutations that prevent the release of human pituitary GH (hGH). To determine the mechanisms of these dominant negative effects, we used a combination of transgenic and morphological approaches in both in vitro and in vivo models.

Versatile regulation of cytosolic Ca2+ by vanilloid receptor I in rat dorsal root ganglion neurons.

Analysis of small dorsal root ganglion (DRG) neurons revealed novel functions for vanilloid receptor 1 (VR1) in the regulation of cytosolic Ca(2+). The VR1 agonist capsaicin induced Ca(2+) mobilization from intracellular stores in the absence of extracellular Ca(2+), and this release was inhibited by the VR1 antagonist capsazepine but was unaffected by the phospholipase C inhibitor xestospongins, indicating that Ca(2+) mobilization was dependent on capsaicin receptor binding and was not due to intracellular inositol-1,4,5-trisphosphate generation. Confocal microscopy revealed extensive expression of VR1 on endoplasmic reticulum, consistent with VR1 operating as a Ca(2+) release receptor.

A secreted fluorescent reporter targeted to pituitary growth hormone cells in transgenic mice.

In stable transfection experiments in the GH-producing GC cell line, a construct containing the entire signal peptide and the first 22 residues of human GH linked in frame with enhanced green fluorescent protein (eGFP), produced brightly fluorescent cells with a granular distribution of eGFP. This eGFP reporter was then inserted into a 40-kb cosmid transgene containing the locus control region for the hGH gene and used to generate transgenic mice. Anterior pituitaries from these GH-eGFP transgenic mice showed numerous clusters of strongly fluorescent cells, which were also immunopositive for GH, and which could be isolated and enriched by fluorescence-activated cell sorting.

Differentially expressed genes during in vitro differentiation of murine embryonic stem cells transduced with a human erythropoietin receptor cDNA.

Our previous study demonstrated that transduction of murine embryonic stem (ES) cells with a human erythropoietin (Epo) receptor (R) cDNA resulted in enhanced erythropoiesis in developing embryonic bodies (EBs). To address possible mechanisms of gene regulation, we compared gene expression between hEpoR cDNA-transduced ES (ES-hEpoR) cells and parental ES cells during in vitro differentiation induced by withdrawal of leukemia inhibitory factor (LIF) and cultured in the absence of Epo using differential display reverse transcriptase-polymerase chain reaction (DDRT-PCR). A total of 48 differentially expressed cDNA fragments were found; 12 were sequenced and five were confirmed by Northern blot analysis to be up- or down-regulated in ES-hEpoR cells during differentiation compared to parental ES cells.