Optical Coherence Tomography Identifies Lower Labial Salivary Gland Surface Density in Cystic Fibrosis

The labial minor salivary glands (LSGs) are easily accessible mucus-secreting structures of the alimentary tract that may provide new information on the basis of gastrointestinal complications of cystic fibrosis (CF). It was shown that they are destructed in the course of cystic fibrosis. We employed wide-field, micrometer resolution in vivo optical coherence tomography to assess the surface density of LSGs in 18 patients with CF and 18 healthy subjects. The median LSGs’ surface densities in CF patients, and in the control group were 4.32 glands/cm² and 6.58 glands/cm², respectively (p = 0.006; Mann-Whitney U test). A lower LSG surface density is a previously unrecognized CF-related pathology of the alimentary tract.     

Thermostability gradient in the collagen triple helix reveals its multi-domain structure

A triple-helical conformation and stability at physiological temperature are critical for the mechanical and biological functions of the fibril-forming collagens. Here, we characterized the role of consecutive domains of collagen II in stabilizing the triple helix. Analysis of melting temperatures of genetically engineered collagen-like proteins consisting of tandem repeats of the D1, D2, D3 or D4 collagen II periods revealed the presence of a gradient of thermostability along the collagen molecule with thermolabile N-terminal domains and thermostable C-terminal domains. These results imply a multi-domain character of the collagen triple helix. Assays of thermostabilities of the Arg75Cys and Arg789Cys collagen II mutants suggest that, in contrast to the thermostable domains, the thermolabile domains are able to accommodate amino acid substitutions without altering the thermostability of the entire collagen molecule.     

Synthesis and biological properties of new chimeric galanin analogue GAL(1-13)-[Ala10,11]ET-1(6-21)-NH2.

Several chimeric peptides consisting of the N-terminal fragment of galanin (GAL) and C-terminal fragments of other bioactive peptides (e.g. substance P, bradykinin, neuropeptide Y, mastoparan) have been synthesized and reported as high-affinity galanin receptor antagonists. Recently we have synthesized a new chimeric peptide, GAL(1-13)-[Ala(10,11)]ET-1(6-21)-NH(2), consisting of the N-terminal fragment of GAL and the C-terminal fragment of endothelin-1 (ET-1) analogue. This chimera was previously shown to be a moderate-affinity ligand to hypothalamic galanin receptors with a K(D) value of 205 nM. However, its biological action has been unknown so far. In our studies we characterized the biological properties of this new chimeric analogue, investigating its action on rat isolated gastric smooth muscles and influence on insulin secretion from rat isolated islets of Langerhans. Data acquired in the course of our studies suggest that analogue GAL(1-13)-[Ala(10,11)]ET-1(6-21)-NH(2) does not seem to be a potent galanin receptor antagonist in the gastrointestinal tract.     

Comparison of the effect of three different topoisomerase II inhibitors combined with cisplatin in human glioblastoma cells sensitized with double strand break repair inhibitors

Molecular Biology Reports - Topoisomerase II (Topo2) inhibitors in combination with cisplatin represent a common treatment modality used for glioma patients. The main mechanism of their action...     

Foraging Ecology Predicts Learning Performance in Insectivorous Bats

Bats are unusual among mammals in showing great ecological diversity even among closely related species and are thus well suited for studies of adaptation to the ecological background. Here we investigate whether behavioral flexibility and simple- and complex-rule learning performance can be predicted by foraging ecology. We predict faster learning and higher flexibility in animals hunting in more complex, variable environments than in animals hunting in more simple, stable environments. To test this hypothesis, we studied three closely related insectivorous European bat species of the genus Myotis that belong to three different functional groups based on foraging habitats: M. capaccinii, an open water forager, M. myotis, a passive listening gleaner, and M. emarginatus, a clutter specialist. We predicted that M. capaccinii would show the least flexibility and slowest learning reflecting its relatively unstructured foraging habitat and the stereotypy of its natural foraging behavior, while the other two species would show greater flexibility and more rapid learning reflecting the complexity of their natural foraging tasks. We used a purposefully unnatural and thus species-fair crawling maze to test simple- and complex-rule learning, flexibility and re-learning performance. We found that M. capaccinii learned a simple rule as fast as the other species, but was slower in complex rule learning and was less flexible in response to changes in reward location. We found no differences in re-learning ability among species. Our results corroborate the hypothesis that animals’ cognitive skills reflect the demands of their ecological niche.     

Comparative study of DNA damage, cell cycle and apoptosis in human K562 and CCRF-CEM leukemia cells: role of BCR/ABL in therapeutic resistance

The Philadelphia translocation t(9;22) resulting in the bcr/abl fusion gene is the pathogenic principle of almost 95% of human chronic myelogenous leukemia (CML). Imatinib mesylate (STI571) is a specific inhibitor of the BCR/ABL fusion tyrosine kinase that exhibits potent antileukemic effects in CML. BCR/ABL-positive K562 and -negative CCRF-CEM human leukemia cells were investigated. MTT survival assay and clonogenic test of the cell proliferation ability were used to estimate resistance against idarubicin. DNA damage after cell treatment with the drug at the concentrations from 0.001 to 3 microM with or without STI571 pre-treatment were examined by the alkaline comet assay. We found that the level of DNA damages was lower in K562 cells after STI571 pre-treatment. It is suggested that BCR/ABL activity may promote genomic instability, moreover K562 cells were found to be resistant to the drug treatment. Further, we provided evidence of apoptosis inhibition in BCR/ABL-positive cells using caspase-3 activity colorimetric assay and DAPI nuclear staining for chromatin condensation. We suggest that these processes associated with cell cycle arrest in G2/M checkpoint detected in K562 BCR/ABL-positive compared to CCRF-CEM cells without BCR/ABL expression might promote clone selection resistance to drug treatment.     

Imatinib mesylate (STI571) abrogates the resistance to doxorubicin in human K562 chronic myeloid leukemia cells by inhibition of BCR/ABL kinase-mediated DNA repair

Imatinib mesylate (STI571), a specific inhibitor of BCR/ABL tyrosine kinase, exhibits potent antileukemic effects in the treatment of chronic myelogenous leukemia (CML). However, the precise mechanism by which inhibition of BCR/ABL activity results in pharmacological responses remains unknown. BCR/ABL-positive human K562 CML cells resistant to doxorubicin (K562DoxR) and their sensitive counterparts (K562DoxS) were used to determine the mechanism by which the STI571 inhibitor may overcome drug resistance. K562 wild type cells and CCRF-CEM lymphoblastic leukemia cells without BCR/ABL were used as controls. The STI571 specificity was examined by use of murine pro-B lymphoid Baf3 cells with or without BCR/ABL kinase expression. We examined kinetics of DNA repair after cell treatment with doxorubicin in the presence or absence of STI571 by the alkaline comet assay. The MTT assay was used to estimate resistance against doxorubicin and Western blot analysis with Crk-L antibody was performed to evaluate BCR/ABL kinase inhibition by STI571. We provide evidence that treatment of CML-derived BCR/ABL-expressing leukemia K562 cells with STI571 results in the inhibition of DNA repair and abrogation of the resistance of these cells to doxorubicin. We found that doxorubicin-resistant K562DoxR cells exhibited accelerated kinetics of DNA repair compared with doxorubicin-sensitive K562DoxS cells. Inhibition of BCR/ABL kinase in K562DoxR cells with 1 microM STI571 decreased the kinetics of DNA repair and abrogated drug resistance. The results suggest that STI571-mediated inhibition of BCR/ABL kinase activity can affect the effectiveness of the DNA-repair pathways, which in turn may enhance drug sensitivity of leukemia cells.     

Ozone fumigation results in accelerated growth and persistent changes in the antioxidant system of Brassica oleracea L. var. capitata f. alba

The growth response and antioxidant capacity of Brassica oleracea var. capitata f. alba plants treated with 70 ppb of ozone was examined. Four week old cabbage seedlings were fumigated with O₃ for 3 days before being transplanted into the growing field. The effect of O₃ treatment was determined directly after fumigation and over the course of field cultivation. Plants subjected to O₃ treatment had an increased diameter of rosettes and number of leaves after 3 and 7 weeks in agriculture, respectively. In addition, the vast majority of fumigated plants reached marketable quality faster than control plants, indicating a positive role of episodes of increased O₃ concentrations during vegetation on growth and yielding.