The extract from hop cones in plasma protects against changes following exposure to peroxynitrite

Humulus lupulus (Cannabaceae) is well known throughout the world as a raw material in the brewing industry. The antioxidative action of hop cones is poorly understood, therefore the aim of our present study was to investigate in vitro changes in human plasma induced by peroxynitrite in the presence of the highly purified extract from hop cones (Humulus lupulus). The aim of our study was also to explain the effect of the extract from hop cones on coagulation activity of human plasma treated with peroxynitrite. The action of the extract from hop cones was compared with the properties of a well-characterized commercial monomeric polyphenol — resveratrol (3,4′,5-trihydroxystilbene). The tested plant extract, like resveratrol, significantly inhibited protein carbonylation and nitration in plasma treated with ONOO⁻(0.1 mM). The extract from hop cones, like resveratrol, also caused a distinct reduction of plasma lipid peroxidation induced by ONOO⁻. Moreover, the tested extract modulated the coagulation properties of plasma treated with peroxynitrite. It seems that antioxidative activities of the highly purified extract from hop cones may be responsible for its medicinal properties.     

Significant involvement of chromosome 13q deletions in progression of larynx cancer, detected by comparative genomic hybridization

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of tumours with various clinical characteristics. These tumours generally exhibit complex karyotypes. Few studies of genomic imbalances have been performed exclusively in subgroups of larynx cancer samples at different stages of the disease. In the present study, chromosomal gains and losses were investigated in 52 larynx tumours, by using comparative genomic hybridization (CGH). The mean number of observed alterations was 37.7 per tumour. The most common sites of losses were 1p, 13q, Xp, and the most common gains were located in 1p, 9q, 16q. The overall number of gains was negatively associated with cancer grading. G1 tumours were also characterized by a higher frequency of deletions in 13q32 and amplifications in 1q23, than tumours in other grades (p < 0.05). The frequency of losses of 13q22 also positively associated with tumour size. There was no association between the frequency of losses in 13q and the presence of lymph node metastases at the time of diagnosis. Another statistically significant association was observed for gains at 1q22-23 and tumour size (p < 0.01). No statistically significant difference in the frequency of most common imbalances was detected between primary tumours with lymph node metastases and those without metastases. In conclusion, we discovered a significant involvement of 13q deletions in the progression of larynx cancer. All the other significant changes observed in the present study were reported previously as being important for HNSCC progression. It seems that multiple genes are disrupted in the process of neoplastic transformation in the larynx, and the networks of events remain to be elucidated.     

Visualisation of microtubules and actin filaments in fixed BY-2 suspension cells using an optimised whole mount immunolabelling protocol

Excellent visualisation of microtubules and actin filaments was obtained in fixed tobacco BY-2 suspension cells after optimising a protocol for whole mount immunolabelling. The procedure is based on modification of fixation, cell wall digestion, dimethyl sulfoxide (DMSO) treatment, post fixation, and blocking. The most critical aspects of successful preservation and visualization of cytoskeletal elements appeared to be: a two-step fixation with paraformaldehyde and glutaraldehyde before enzymatic cell wall digestion and a post fixation with aldehydes thereafter. The method allows the improved visualization of the organisation of the microtubular and actin filament arrays during the successive stages of cell division and at interphase. Although we present the application of our protocols for cytoskeleton labelling, the excellent results show the potential of using this method for the analysis of various proteins and molecules in plant cells.Electronic Supplementary Material Supplementary material is available for this article at     

Expression and regulation of resistin in osteoblasts and osteoclasts indicate a role in bone metabolism

The adipose tissue is the site of expression and secretion of a range of biologically active proteins, called adipokines, for example, leptin, adiponectin, and resistin. Leptin has previously been shown to be expressed in osteoblasts and to promote bone mineralization, whereas adiponectin expression is enhanced during osteoblast differentiation. In the present study we explored the possible role of resistin in bone metabolism. We found that resistin is expressed in murine preosteoclasts and preosteoblasts (RAW 264.7, MC3T3-E1), in primary human bone marrow stem cells and in mature human osteoblasts. The expression of resistin mRNA in RAW 264.7 was increased during differentiation and seemed to be regulated through PKC- and PKA-dependent mechanisms. Recombinant resistin increased the number of differentiated osteoclasts and stimulated NFkappaB promoter activity, indicating a role in osteoclastogenesis. Resistin also enhanced the proliferation of MC3T3-E1 cells in a PKA and PKC-dependent manner, but only weakly interfered with genes known to be upregulated during differentiation of MC3T3-E1 into osteoblasts. All together, our results indicate that resistin may play a role in bone remodeling.     

Mutagenic activity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine

MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) is a neurotoxin, which can damage dopaminergic neurons. It causes symptoms resembling those observed in patients suffering from Parkinson's disease, and hence this toxin is widely used in studies on animal models of this disorder. Mutagenicity of MPTP was also reported by some authors, but results obtained by others suggested that this compound is not mutagenic. Interestingly, those contrasting results were based on the same assay (the Ames test). Therefore, we aimed to test MPTP mutagenicity by employing a recently developed Vibrio harveyi assay, which was demonstrated previously to be more sensitive than the Ames test, at least for some mutagens. We found that MPTP showed a significant mutagenic activity. Moreover, MPTP mutagenicity was attenuated by methylxanthines, compounds that are known to form complexes with aromatic mutagens.     

The corticosteroid hormone induced factor: a new modulator of KCNQ1 channels?

The corticosteroid hormone induced factor (CHIF) is a member of the one-transmembrane segment protein family named FXYD, which also counts phospholemman and the Na,K-pump gamma-subunit. Originally it was suggested that CHIF could induce the expression of the I(Ks) current when expressed in Xenopus laevis oocytes, but recently CHIF has attracted attention as a modulatory subunit of the Na,K-pump. In renal and intestinal epithelia, the expression of CHIF is dramatically up-regulated in response to aldosterone stimulation, and regulation of epithelial ion channels by CHIF is an attractive hypothesis. To study a potential regulatory effect of the CHIF subunit on KCNQ1 channels, co-expression experiments were performed in Xenopus laevis oocytes and mammalian CHO-K1 cells. Electrophysiological characterization was obtained by two-electrode voltage-clamp and patch-clamp, respectively. In both expression systems, we find that CHIF drastically modulates the KCNQ1 current; in the presence of CHIF, the KCNQ1 channels open at all membrane potentials. Thereby, CHIF is the first accessory subunit shown to be capable of modulating both the Na,K-pump and an ion channel. To find a possible physiological function of the constitutively open KCNQ1/CHIF complex, the precise localization of KCNQ1 and CHIF in distal colon and kidney from control and salt-depleted rats was determined by confocal microscopy. However, in these tissues, we did not detect an obvious overlap in expression between KCNQ1 and CHIF. In conclusion, the hormone-regulated subunit CHIF modulates the voltage sensitivity of the KCNQ channels, but so far evidence for an actual co-localization of CHIF and KCNQ1 channels in native tissue is lacking.