Effects of high intensity non-ionizing terahertz radiation on human skin fibroblasts

For the first time, the data have been obtained on the effects of high-intensity terahertz (THz) radiation (with the intensity of 30 GW/cm², electric field strength of 3.5 MV/cm) on human skin fibroblasts. A quantitative estimation of the number of histone Н2АХ foci of phosphorylation was performed. The number of foci per cell was studied depending on the irradiation time, as well as on the THz pulse energy. The performed studies have shown that the appearance of the foci is not related to either the oxidative stress (the cells preserve their morphology, cytoskeleton structure, and the reactive oxygen species content does not exceed the control values), or the thermal effect of THz radiation. The prolonged irradiation of fibroblasts also did not result in a decrease of their proliferative index.     

Investigation of Antibacterial Properties of Corrosion-Resistant 316L Steel Alloyed with 0.2 wt.% and 0.5 wt.% Ag

The article is devoted to the study of melted ingots, plates rolled from them, and the resulting spherical powder made of corrosion-resistant 316L steel with the addition of 0.2 wt.% and 0.5 wt.% Ag. The study of antibacterial properties, microstructure, and distribution of silver concentrations, as well as qualitative analysis of silver content was carried out. The optimal mode of homogenization annealing of the ingot was 1050 °C for 9 h, which leads to the formation of an austenitic structure. It is shown that the addition of a small amount of silver does not affect the formation of the austenitic structure and silver is distributed evenly throughout the volume of the ingot. The austenitic structure also prevails in the plates after rolling. Silver is distributed evenly throughout the entire volume of the plate. It is noted that the addition of 0.2 wt.% Ag does not affect the strength, elongation, and microhardness of steel, and the addition of 0.5 wt.% Ag does not significantly reduce the strength of steel, however, all samples meet the mechanical characteristics according to the ASTM A240 standard. The qualitative chemical composition of samples made of corrosion-resistant steels was confirmed by X-ray fluorescence analysis methods. By the method of energy-dispersion analysis, the presence of a uniform distribution of silver over the entire volume of the powder particle was determined. The particles have a spherical shape with a minimum number of defects. The study of the antibacterial activity of plates and powder shows the presence of a clear antibacterial effect (bacteria of the genus Xanthomonas campestris, Erwinia carotovora, Pseudomonas marginalis, Clavibacter michiganensis) in samples No. 2 and No. 3 with the addition of 0.2 wt.% and 0.5 wt.% Ag.     

Structure,Properties, and Phase Transformations of Water Nanoconfined between Brucite-like Layers: The Role of Wall Surface Polarity

The interaction of water with confining surfaces is primarily governed by the wetting properties of the wall material—in particular, whether it is hydrophobic or hydrophilic. The hydrophobicity or hydrophilicity itself is determined primarily by the atomic structure and polarity of the surface groups. In the present work, we used molecular dynamics to study the structure and properties of nanoscale water layers confined between layered metal hydroxide surfaces with a brucite-like structure. The influence of the surface polarity of the confining material on the properties of nanoconfined water was studied in the pressure range of 0.1–10 GPa. This pressure range is relevant for many geodynamic phenomena, hydrocarbon recovery, contact spots of tribological systems, and heterogeneous materials under extreme mechanical loading. Two phase transitions were identified in water confined within 2 nm wide slit-shaped nanopores: (1) at p₁ = 3.3–3.4 GPa, the liquid transforms to a solid phase with a hexagonal close-packed (HCP) crystal structure, and (2) at p₂ = 6.7–7.1 GPa, a further transformation to face-centered cubic (FCC) crystals occurs. It was found that the behavior of the confined water radically changes when the partial charges (and, therefore, the surface polarity) are reduced. In this case, water transforms directly from the liquid phase to an FCC-like phase at 3.2–3.3 GPa. Numerical simulations enabled determination of the amount of hydrogen bonding and diffusivity of nanoconfined water, as well as the relationship between pressure and volumetric strain.     

A new hope: novel therapeutic approaches to treatment of chronic lymphocytic leukaemia with defects in TP53

Chronic lymphocytic leukaemia (CLL) is an indolent B‐cell malignancy with heterogeneous outcomes. Chromosomal abnormalities in CLL are predictive of the natural disease course; del(11q) and del(17p) are recognized as high risk genetic lesions. Del(17p) is associated with an impaired function of TP53, a key tumour suppressor, and is particularly problematic. Such patients respond poorly to chemo‐immunotherapy and have significantly shorter survival compared to patients with standard and low‐risk cytogenetics. While TP53 pathway defects are rare at initial diagnosis, their frequency increases in relapsed CLL. Until very recently, this group of patients represented an unmet clinical need with few therapeutic options. However, the advent of targeted therapies has expanded the drug armamentarium and introduced new hope for these highly refractory patients. Agents that target B‐cell receptor signalling, BH3‐mimetics and others induce apoptosis of the neoplastic B‐cells in a TP53‐independent manner. Their use in the clinic is associated with remarkable activity in patients with del(17p). In this review we discuss the frequency and clinical significance of del(17p) and genetic mutations leading to disrupted TP53, the putative role of other TP53 homologues, and the results of key clinical trials involving both conventional chemotherapy and novel agents.     

Monitoring Dynamic Recrystallisation in Bioresorbable Alloy Mg-1Zn-0.2Ca by Means of an In Situ Acoustic Emission Technique

The tensile behaviour of the biocompatible alloy Mg-1Zn-0.2Ca (in wt.%) in the fine-grained state, obtained by severe plastic deformation via multiaxial isothermal forging, has been investigated in a wide range of temperatures (20 ÷ 300) °C and strain rates (5 × 10⁻⁴ ÷ 2 × 10⁻²) s⁻¹ with the measurements of acoustic emission (AE). The dependences of mechanical properties, including the yield stress, ultimate strength, ductility, and the strain-hardening rate, on the test temperature and strain rate, were obtained and discussed. It is shown for the first time that an acoustic emission method is an effective tool for in situ monitoring of the dynamic recrystallisation (DRX) process. The specific behaviour of the acoustic emission spectral density reflected by its median frequency as a function of strain at various temperatures can serve as an indicator of the DRX process’s completeness.     

TCL1 targeting miR-3676 is codeleted with tumor protein p53 in chronic lymphocytic leukemia

B-cell chronic lymphocytic leukemia (CLL) is the most common human leukemia and dysregulation of the T-cell leukemia/lymphoma 1 (TCL1) oncogene is a contributing event in the pathogenesis of the aggressive form of this disease based on transgenic mouse studies. To determine a role of microRNAs on the pathogenesis of the aggressive form of CLL we studied regulation of TCL1 expression in CLL by microRNAs. We identified miR-3676 as a regulator of TCL1 expression. We demonstrated that miR-3676 targets three consecutive 28-bp repeats within 3′UTR of TCL1 and showed that miR-3676 is a powerful inhibitor of TCL1. We further showed that miR-3676 expression is significantly down-regulated in four groups of CLL carrying the 11q deletions, 13q deletions, 17p deletions, or a normal karyotype compared with normal CD19⁺ cord blood and peripheral blood B cells. In addition, the sequencing of 539 CLL samples revealed five germ-line mutations in six samples (1%) in miR-3676. Two of these mutations were loss-of-function mutations. Because miR-3676 is located at 17p13, only 500-kb centromeric of tumor protein p53 (Tp53), and is codeleted with Tp53, we propose that loss of miR-3676 causes high levels of TCL1 expression contributing to CLL progression.Chronic lymphocytic leukemia (CLL) is the most common adult leukemia (1). Unfavorable prognosis associates with the expression of unmutated immunoglobulin variable genes (IGVH) and high levels of 70 kD zeta-associated protein (ZAP-70). CLLs can be subgrouped into aggressive and indolent cases and chromosomal aberrations are present in more than 80% of patients (1–3). Cytogenetic abnormalities are also a prognostic parameter (3). The most common chromosomal abnormalities detectable by cytogenetics include deletion at 13q (50%), 11q (18%), trisomy 12 (15–18%), and 17p (8%) (2, 3). Prognostic categories have shown poor survival in patients harboring 17p deletion, 11q deletion, or trisomy 12, and better survival for patients with normal karyotype and 13q deletion as the sole abnormality (3).We have shown that loss of miR-15a/16-1 is the most common genetic alteration in CLL (70–80%) (4). This alteration is very common in indolent CLLs and in indolent CLLs that progress to the aggressive form (4, 5). Previously, we have observed loss of miR-181 and miR-29, which negatively regulate T-cell leukemia/lymphoma 1 (TCL1), during the progression of CLL (6, 7).Activation of the TCL1 gene is arguably one of most studied events in the pathogenesis of aggressive CLL (8). We and others have found that TCL1 overexpression occurs in a number of B-cell malignancies, including CLL (8–10). To validate that overexpression of TCL1 is oncogenic in B-cells, we have created a Eμ-TCL1 transgenic mouse model overexpressing TCL1 (11, 12). All of these transgenic mice developed the aggressive form of CLL at the average age of 12 mo with 100% penetrance (11, 12), indicating that deregulation of TCL1 is critically important in the pathogenesis of the aggressive form of CLL. Numerous publications of this CLL model have confirmed our findings (13–17). Previously we reported that Tcl1 overexpression contributes to CLL pathogenesis by coactivating Akt, and inhibiting AP-1 and de novo DNA methylation by inhibiting of the de novo DNA methyltransferases (18–21). The mechanisms responsible for overexpression of Tcl1 in CLL are not entirely clear. For this reason, we studied the regulation of TCL1 expression by microRNAs.     

Sec17 can trigger fusion of trans-SNARE paired membranes without Sec18

Sec17 [soluble N-ethylmaleimide–sensitive factor (NSF) attachment protein; α-SNAP] and Sec18 (NSF) perform ATP-dependent disassembly of cis-SNARE complexes, liberating SNAREs for subsequent assembly of trans-complexes for fusion. A mutant of Sec17, with limited ability to stimulate Sec18, still strongly enhanced fusion when ample Sec18 was supplied, suggesting that Sec17 has additional functions. We used fusion reactions where the four SNAREs were initially separate, thus requiring no disassembly by Sec18. With proteoliposomes bearing asymmetrically disposed SNAREs, tethering and trans-SNARE pairing allowed slow fusion. Addition of Sec17 did not affect the levels of trans-SNARE complex but triggered sudden fusion of trans-SNARE paired proteoliposomes. Sec18 did not substitute for Sec17 in triggering fusion, but ADP- or ATPγS-bound Sec18 enhanced this Sec17 function. The extent of the Sec17 effect varied with the lipid headgroup and fatty acyl composition of the proteoliposomes. Two mutants further distinguished the two Sec17 functions: Sec17^L291A,L292A did not stimulate Sec18 to disassemble cis-SNARE complex but triggered the fusion of trans-SNARE paired membranes. Sec17^F21S,M22S, with diminished apolar character to its hydrophobic loop, fully supported Sec18-mediated SNARE complex disassembly but had lost the capacity to stimulate the fusion of trans-SNARE paired membranes. To model the interactions of SNARE-bound Sec17 with membranes, we show that Sec17, but not Sec17^F21S,M22S, interacted synergistically with the soluble SNARE domains to enable their stable association with liposomes. We propose a model in which Sec17 binds to trans-SNARE complexes, oligomerizes, and inserts apolar loops into the apposed membranes, locally disturbing the lipid bilayer and thereby lowering the energy barrier for fusion.Intracellular vesicular traffic between organelles is the basis of cell growth, hormone secretion, and neurotransmission. At each step of exocytic and endocytic trafficking, membranes dock and fuse, mixing their lipids and luminal contents while keeping them separate from the cytosol. Families of proteins, conserved from yeast to humans, mediate docking and fusion. Fusion requires Rab family GTPases and “effector” proteins that bind to a Rab in its active, GTP-bound state (1). Among the effectors are large, organelle-specific tethering complexes. Fusion requires SNARE proteins and their chaperones. SNAREs (2) are proteins that can “snare” (bind to) each other, in cis (when anchored to the same membrane) or in trans (when anchored to apposed, tethered membranes). SNAREs have a conserved “SNARE domain” with a characteristic heptad repeat. SNAREs are categorized as R-SNAREs if they have a central arginyl residue, or Qa-, Qb-, or Qc-SNAREs with a central glutamyl residue (3). SNAREs form RQaQbQc quaternary cis- or trans-SNARE complexes, which bind SNARE chaperones, including the Sec1/Munc18 family of SNARE binding proteins, and Sec18/NSF (N-ethylmaleimide–sensitive factor), an AAA family ATPase that drives SNARE complex disassembly (4). Sec17/α-SNAP (soluble NSF attachment protein) is a cochaperone to Sec18 that enhances its rate of SNARE complex disassembly (5).We study fusion with yeast vacuoles. The homotypic fusion of vacuoles has been studied extensively through genetic identification of vacuole morphology (vam) mutants (6) and vacuole protein sorting (vps) mutants (7), through a colorimetric assay of the fusion of isolated vacuoles (8), and more recently through the fusion of proteoliposomes reconstituted with defined, purified proteins and lipids (9–11). Sec17, Sec18, and ATP catalyze the first stage of vacuole fusion, in which cis-SNARE complexes are disassembled (12). Tethering is then supported by the Rab Ypt7 and the large, multisubunit tethering complex termed HOPS (13). Vps33, one of the HOPS subunits, is the vacuolar SM (Sec1/mUNC-18 family) protein. HOPS has direct affinity for vacuolar SNAREs (14–16), and helps to catalyze SNARE complex assembly and the subsequent fusion (17).During in vitro fusion incubations, most Sec17 is released from vacuoles during cis-SNARE complex disassembly (12). However, a few percent of the vacuolar SNAREs form trans-SNARE complexes (18), and Sec17 is a major constituent of these complexes (19). Furthermore, although Sec17 and Sec18 can disassemble trans-SNARE complexes (19) and will block fusion events in which tethering is supplied by an unphysiological agent such as polyethylene glycol (13), Sec17 and Sec18 work synergistically with HOPS to promote fusion (9, 20). This synergy is even seen when the SNAREs are initially disposed with the R-SNARE on one set of proteoliposomes and the three Q-SNAREs on the others (9), a condition that per se does not require cis-SNARE complex disassembly by Sec18. Finally, added Sec17 restores fusion to vacuoles where fusion is blocked by a defined C-terminal truncation in the SNARE domain of the Qc-SNARE Vam7, in the apparent absence of ATP or Sec18 activity (21). These observations prompted us to reevaluate the roles of Sec17 and Sec18 in the fusion pathway.We now exploit proteoliposomes bearing purified vacuolar Rab and SNAREs to reinvestigate the roles of Sec17 and Sec18. Generous amounts of Sec18 alone can disassemble cis-SNARE complexes, allowing proteoliposomes bearing all four vacuolar SNAREs to fuse at a moderate rate. The rate of fusion can be stimulated by wild-type Sec17, as expected, but also by a Sec17 mutant that has greatly diminished capacity to stimulate Sec18. This suggested that Sec17 could act in ways other than through Sec18 stimulation. We therefore examined fusion incubations where the SNAREs are disposed on complementary proteoliposomes such that Sec18 is not required at all. We find that Sec17 can trigger rapid fusion of proteoliposomes that are already joined by trans-SNARE associations.