Expression of the cell adhesion molecule E-cadherin by the human bone marrow stromal cells and its probable role in CD34(+) stem cell adhesion.

Bone marrow stroma is the physical basis of the haematopoietic microenvironment and regulates several key features of stem cell proliferation and differentiation. It plays a crucial role in maintaining haematopoietic homeostasis. Earlier studies have shown that this is achieved through interactions with the extracellular matrix and specific molecules called the cell adhesion molecules (CAMs). In this paper, we show that E-cadherin, a cell adhesion molecule which plays a crucial role in cell-cell aggregation during development, is also present in the bone marrow stroma. The expression of the CAM can also be demonstrated on a subset of CD34(+)stem cells. Stromal expression of E-cadherin is decreased when treated with lymphokine mixture, phytohaemagglutinin-treated-leukocyte-conditioned medium (PHA-LCM). This is the reverse of ICAM-I expression, which increases with PHA-LCM treatment. E-cadherin shows homotypic and homophilic interaction and its presence on a subset of CD34(+)cells leads to speculation on whether this CAM has a role in adherence of primitive stem cells to the marrow stroma.     

Gynaecological cancers and their cell lines

Cell lines are widely used for various research purposes including cancer and drug research. Recently, there have been studies that pointed to discrepancies in the literature and usage of cell lines. That is why we have prepared a comprehensive overview of the most common gynaecological cancer cell lines, their literature, a list of currently available cell lines, and new findings compared with the original studies. A literature review was conducted via MEDLINE, PubMed and ScienceDirect for reviews in the last 5 years to identify research and other studies related to gynaecological cancer cell lines. We present an overview of the current literature with reference to the original studies and pointed to certain inconsistencies in the literature. The adherence to culturing rulesets and the international guidelines helps in minimizing replication failure between institutions. Evidence from the latest research suggests that despite certain drawbacks, variations of cancer cell lines can also be useful in regard to a more diverse genomic landscape.     

84 PPC measurements of unfolding volumes of DNA stem-loop motifs

One focus of our research is to further our understanding of the physico-chemical properties of non-canonical nucleic acid structures. In this work, DNA hairpins are used to mimic a common motif present in RNA, i.e. a stem-loop motif with a bulge or internal loop in their stem. Specifically, we used a combination of temperature-dependent UV spectroscopy, differential scanning (DSC), and pressure perturbation (PPC) calorimetric techniques to determine complete thermodynamic profiles for the helix–coil transitions of two sets of hairpins with 5′–3′ sequences: d(GCGCT _n GTAACT₅GTTACGCGC) and d(GCGCT _n GTAACT₅GTTACT _n GCGC). “T _n ” is a variable loop of thymines, n?=?1, 3 or 5; and “T₅” is an end-loop of five thymines. Unfolding curves show monophasic transitions with TMs independent of strand concentration, confirming their intramolecular formation. DSC thermodynamic profiles indicate that the favorable folding of each hairpin results from the typical compensation of favorable enthalpy and unfavorable entropy contributions, while the DSC curves as a function of salt concentration yielded an uptake of cations and negative heat capacity effects. PPC melting curves yielded positive folding volumes ranging 12–31?cm³/mol, corresponding to releases of water molecules; in contrast, an uptake of water (ranging from 32 to 63?mol of H₂O/mol) is observed from osmotic stress experiments using ethylene glycol as the osmolyte. Overall, the increase in the size of the variable bulge or internal-loop yielded lower TMs and slightly more favorable enthalpies, corresponding to less favorable free energy contributions of ～0.7?kcal/mol per thymine residue. The volume measurements will be correlated with the unfolding entropies and discussed in terms of the type of water that is hydrating these stem-loop motifs structures.     

Synthesis, characterization and DNA binding of magnesium-ciprofloxacin (cfH) complex [Mg(cf)2] * 2.5H2O

Interactions of the tested systems (title compound [Mg(cf)(2)] * 2.5H(2)O (1), ciprofloxacin (cfH) and ciprofloxacin in the mixture with MgCl(2)), with single and double stranded calf thymus DNA, poly[d(AT)] * poly[d(AT)] and poly[d(GC)] * poly[d(GC)] were studied by UV-spectrophotometric (melting curves) and fluorescence emission measurements. Pronounced quenching of ciprofloxacin's fluorescence intensity has been observed for all the tested compounds after titration with various GC containing DNA molecules. It seems probable that quenching originates in the electron transfer from guanine to the photo-excited fluoroquinolone. The UV-spectrophotometric results obtained for 1 are substantially different from the other solutions and the biggest differences were observed for GC containing DNAs. Solution of 1 provokes a large thermal destabilization of poly[d(GC)] * poly[d(GC)]. This process is irreversible which suggests that the species present in solution of 1 alone inhibit re-annealing by associating irreversibly with the single strands. We have realized that aqueous solutions of 1 are colloidal and we propose that colloidal particles are involved in specific binding to GC containing sequences, most probably in the major groove of DNA.     

Ostreolysin enhances fruiting initiation in the oyster mushroom (Pleurotus ostreatus)

Fruiting initiation in mushrooms can be triggered by a variety of environmental and biochemical stimuli, including substances of natural or synthetic origin. In this work ostreolysin, a cytolytic protein specifically expressed during the formation of primordia and fruit bodies of Pleurotus ostreatus, was applied to nutrient media inoculated with mycelium of P. ostreatus, and its effects on mycelial growth and fructification of the mushroom studied. The addition of ostreolysin slightly inhibited the growth of mycelium, but strongly induced the formation of primordia, which appeared 10 d earlier than in control plates supplemented with bovine serum albumin or with the dissolving buffer alone. Moreover, ostreolysin stimulated the subsequent development of primordia into fruit bodies. However, direct involvement of this protein in the sporulation of the mushroom is unlikely, as it was also detected in large amounts in the non-sporulating strain of P. ostreatus.     

Nickel-quinolones interaction: Part 3 — Nickel(II) complexes of the antibacterial drug flumequine

Nickel(II) complexes with the first-generation quinolone antibacterial agent flumequine in the presence or absence of nitrogen donor heterocyclic ligands (4-benzylpyridine, pyridine, 2,2′-bipyridine or 1,10-phenanthroline) have been structurally characterized by physicochemical and spectroscopic techniques. The experimental data suggest that flumequine acts as deprotonated bidentate ligand coordinated to Ni(II) through the carboxylato and ketone oxygen atoms. The crystal structures of bis(4-benzylpyridine)bis(flumequinato)nickel(II) 2, (2,2′-bipyridine)bis(flumequinato)nickel(II) 4 and (1,10-phenanthroline)bis(flumequinato)nickel(II) 5 have been determined by X-ray crystallography and are the first crystal structures of flumequinato complexes reported. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) has shown that the complexes bind to CT DNA and bis(aqua)bis(flumequinato)nickel(II) exhibits the highest binding constant to CT DNA. Competitive study with ethidium bromide (EB) has shown that the complexes can displace the DNA-bound EB indicating that they bind to DNA in strong competition with EB. The cyclic voltammograms of the complexes recorded in DMSO solution and in 1/2 DMSO/buffer (containing 150 mM NaCl and 15 mM trisodium citrate at pH 7.0) solution have shown that in the presence of CT DNA they bind to CT DNA by the intercalative binding mode. The complexes exhibit good binding propensity to human or bovine serum albumin protein having relatively high binding constant values.     

Dual Processing Model for Medical Decision-Making: An Extension to Diagnostic Testing

Dual Processing Theories (DPT) assume that human cognition is governed by two distinct types of processes typically referred to as type 1 (intuitive) and type 2 (deliberative). Based on DPT we have derived a Dual Processing Model (DPM) to describe and explain therapeutic medical decision-making. The DPM model indicates that doctors decide to treat when treatment benefits outweigh its harms, which occurs when the probability of the disease is greater than the so called “threshold probability” at which treatment benefits are equal to treatment harms. Here we extend our work to include a wider class of decision problems that involve diagnostic testing. We illustrate applicability of the proposed model in a typical clinical scenario considering the management of a patient with prostate cancer. To that end, we calculate and compare two types of decision-thresholds: one that adheres to expected utility theory (EUT) and the second according to DPM. Our results showed that the decisions to administer a diagnostic test could be better explained using the DPM threshold. This is because such decisions depend on objective evidence of test/treatment benefits and harms as well as type 1 cognition of benefits and harms, which are not considered under EUT. Given that type 1 processes are unique to each decision-maker, this means that the DPM threshold will vary among different individuals. We also showed that when type 1 processes exclusively dominate decisions, ordering a diagnostic test does not affect a decision; the decision is based on the assessment of benefits and harms of treatment. These findings could explain variations in the treatment and diagnostic patterns documented in today’s clinical practice.     

Caffeine suppresses homologous recombination through interference with RAD51-mediated joint molecule formation

Caffeine is a widely used inhibitor of the protein kinases that play a central role in the DNA damage response. We used chemical inhibitors and genetically deficient mouse embryonic stem cell lines to study the role of DNA damage response in stable integration of the transfected DNA and found that caffeine rapidly, efficiently and reversibly inhibited homologous integration of the transfected DNA as measured by several homologous recombination-mediated gene-targeting assays. Biochemical and structural biology experiments revealed that caffeine interfered with a pivotal step in homologous recombination, homologous joint molecule formation, through increasing interactions of the RAD51 nucleoprotein filament with non-homologous DNA. Our results suggest that recombination pathways dependent on extensive homology search are caffeine-sensitive and stress the importance of considering direct checkpoint-independent mechanisms in the interpretation of the effects of caffeine on DNA repair.