Deformation uniformity of additively manufactured materials on the example of austenitic stainless steel 321 and copper C11000

Structural studies and mechanical tests of additively manufactured samples from AISI 321 steel copper C110000 have been carried out. Mechanical tensile tests of 321 steel show slight differences in the ultimate tensile strength (up to 3-4%) and ductility (up to 10%) of test coupons tested along the material growth direction and along the layer deposition direction. The strength of C11000 copper samples is 9.4% higher in the layer deposition direction, but their ductility is 15.4% lower than that of samples deformed in the growth direction. The strain relief on the surface of the polished gage section of the steel test coupons demonstrates changes in the material structure with small elongated grains along the growth direction of the sample. The deformation relief of copper samples is mainly related to the deformation of large columnar grains stretched in the growth direction

Structure formation features of large block-shaped samples from the copper and aluminum alloy produced by the wire-feed electron-beam additive technology

In this work the study of the structure of samples made by the wire-feed electronbeam 3D printing from copper C11000 and aluminum alloy AA5056 was carried out. The presence of a dendritic structure typical of this method was revealed, as well as the presence of pores, cracks and other defects that occurred during printing. Mechanical properties of samples cut in the planar section are at a rather low level. The ultimate tensile strength of copper block samples varies between 165 and 187 MPa. The relative elongation of samples without pores is at 18%, but with the presence of pores it decreases sharply to 7%, while the strength is practically not decreased. The samples of alloy AA5056 demonstrate slightly higher mechanical properties: the strength is at the level of 190-192 MPa and the relative elongation is about 16-18%. In samples with defects such as large pores or discontinuities, the strength drops to almost zero

СЛУЧАЙ НЕТЯЖЕЛОГО ТЕЧЕНИЯ ВРОЖДЕННОГО НЕФРОТИЧЕСКОГО СИНДРОМА

Nephrotic syndrome is a severe renal disease that may result in the end-stage renal failure despite the extent of proteinuria. Prognosis and tactics of therapy of nephrotic syndrome depend both on the morphological diagnosis and on the cause of the disease. It ought to be considered that congenital nephrotic syndrome is resistant to immunosuppressive therapy. However, several foreign authors demonstrate cases of immunosuppressive therapy effectiveness (steroids and cyclosporine A) in a range of familial cases of nephroticsyndrome. Timely detection of children with genetically caused nephrotic syndrome allows to define the patient management tactics in each case on time. This clinical case represents non-severe course of congenital nephrotic syndrome caused by an NPHS2 gene mutation, which had not before been described neither in Russian nor in foreign literature. The authors deem introduction of the molecular genetic analysis to the routine clinical practice for all cases of congenital nephrotic syndrome and steroid-resistant nephrotic syndrome reasonable. Нефротический синдром — серьезное заболевание почек, исходом которого независимо от степени протеинурии может стать терминальная стадия почечной недостаточности. Прогноз и тактика терапии нефротического синдрома зависят как от морфологического диагноза, так и от причины возникновения данного заболевания. Следует учитывать тот факт, что врожденный нефротический синдром является резистентным к иммуносупрессивной терапии. Однако, ряд зарубежных авторов демонстрирует примеры эффективности применения иммуносупрессивных препаратов (стероиды и циклоспорин А) при некоторых семейных случаях нефротического синдрома. Своевременное выявление детей с генетически обусловленным нефротическим синдромом позволяет вовремя определиться с тактикой ведения пациента в каждом конкретном случае. Представленный в статье клинический пример описывает нетяжелое течение врожденного нефротического синдрома, причиной которого стала ранее не описанная в отечественной и зарубежной литературе мутация гена NPHS2. Авторы считают целесообразным введение молекулярно-генетического исследования в повседневную клиническую практику при всех случаях врожденного нефротического синдрома, а также при стероидрезистентном варианте нефротического синдрома.

Long-term exposure to hypoxia inhibits tumor progression of lung cancer in rats and mice

<p>Abstract</p> <p>Background</p> <p>Hypoxia has been identified as a major negative factor for tumor progression in clinical observations and in animal studies. However, the precise role of hypoxia in tumor progression has not been fully explained. In this study, we extensively investigated the effect of long-term exposure to hypoxia on tumor progression <it>in vivo.</it></p> <p>Methods</p> <p>Rats bearing transplanted tumors consisting of A549 human lung cancer cells (lung cancer tumor) were exposed to hypoxia for different durations and different levels of oxygen. The tumor growth and metastasis were evaluated. We also treated A549 lung cancer cells (A549 cells) with chronic hypoxia and then implanted the hypoxia-pretreated cancer cells into mice. The effect of exposure to hypoxia on metastasis of Lewis lung carcinoma in mice was also investigated.</p> <p>Results</p> <p>We found that long-term exposure to hypoxia a) significantly inhibited lung cancer tumor growth in xenograft and orthotopic models in rats, b) significantly reduced lymphatic metastasis of the lung cancer in rats and decreased lung metastasis of Lewis lung carcinoma in mice, c) reduced lung cancer cell proliferation and cell cycle progression <it>in vitro</it>, d) decreased growth of the tumors from hypoxia-pretreated A549 cells, e) decreased Na⁺-K⁺ATPase α1 expression in hypoxic lung cancer tumors, and f) increased expression of hypoxia inducible factors (HIF1α and HIF2α) but decreased microvessel density in the lung cancer tumors. In contrast to lung cancer, the growth of tumor from HCT116 human colon cancer cells (colon cancer tumor) was a) significantly enhanced in the same hypoxia conditions, accompanied by b) no significant change in expression of Na⁺-K⁺ATPase α1, c) increased HIF1α expression (no HIF2α was detected) and d) increased microvessel density in the tumor tissues.</p> <p>Conclusions</p> <p>This study demonstrated that long-term exposure to hypoxia repressed tumor progression of the lung cancer from A549 cells and that decreased expression of Na⁺-K⁺ATPase was involved in hypoxic inhibition of tumor progression. The results from this study provide new insights into the role of hypoxia in tumor progression and therapeutic strategies for cancer treatment.</p

Symbiotic Associations in the Phenotypically-Diverse Brown Alga Saccharina japonica

The brown alga Saccharina japonica (Areschoug) Lane, Mayes, Druehl et Saunders is a highly polymorphic representative of the family Laminariaceae, inhabiting the northwest Pacific region. We have obtained 16S rRNA sequence data in symbiont microorganisms of the typical form (TYP) of S. japonica and its common morphological varieties, known as “longipes” (LON) and “shallow-water” (SHA), which show contrasting bathymetric distribution and sharp morphological, life history traits, and ecological differences. Phylogenetic analysis of the 16S rRNA sequences shows that the microbial communities are significantly different in the three forms studied and consist of mosaic sets of common and form-specific bacterial lineages. The divergence in bacterial composition is substantial between the TYP and LON forms in spite of their high genetic similarity. The symbiont distribution in the S. japonica forms and in three other laminarialean species is not related to the depth or locality of the algae settlements. Combined with our previous results on symbiont associations in sea urchins and taking into account the highly specific character of bacteria-algae associations, we propose that the TYP and LON forms may represent incipient species passing through initial steps of reproductive isolation. We suggest that phenotype differences between genetically similar forms may be caused by host-symbiont interactions that may be a general feature of evolution in algae and other eukaryote organisms. Bacterial symbionts could serve as sensitive markers to distinguish genetically similar algae forms and also as possible growth-promoting inductors to increase algae productivity

2-Deoxy-D-Glucose Treatment of Endothelial Cells Induces Autophagy by Reactive Oxygen Species-Mediated Activation of the AMP-Activated Protein Kinase

Autophagy is a cellular self-digestion process activated in response to stresses such as energy deprivation and oxidative stress. However, the mechanisms by which energy deprivation and oxidative stress trigger autophagy remain undefined. Here, we report that activation of AMP-activated protein kinase (AMPK) by mitochondria-derived reactive oxygen species (ROS) is required for autophagy in cultured endothelial cells. AMPK activity, ROS levels, and the markers of autophagy were monitored in confluent bovine aortic endothelial cells (BAEC) treated with the glycolysis blocker 2-deoxy-D-glucose (2-DG). Treatment of BAEC with 2-DG (5 mM) for 24 hours or with low concentrations of H2O2 (100 µM) induced autophagy, including increased conversion of microtubule-associated protein light chain 3 (LC3)-I to LC3-II, accumulation of GFP-tagged LC3 positive intracellular vacuoles, and increased fusion of autophagosomes with lysosomes. 2-DG-treatment also induced AMPK phosphorylation, which was blocked by either co-administration of two potent anti-oxidants (Tempol and N-Acetyl-L-cysteine) or overexpression of superoxide dismutase 1 or catalase in BAEC. Further, 2-DG-induced autophagy in BAEC was blocked by overexpressing catalase or siRNA-mediated knockdown of AMPK. Finally, pretreatment of BAEC with 2-DG increased endothelial cell viability after exposure to hypoxic stress. Thus, AMPK is required for ROS-triggered autophagy in endothelial cells, which increases endothelial cell survival in response to cell stress

Molecular Determinants and Dynamics of Hepatitis C Virus Secretion

The current model of hepatitis C virus (HCV) production involves the assembly of virions on or near the surface of lipid droplets, envelopment at the ER in association with components of VLDL synthesis, and egress via the secretory pathway. However, the cellular requirements for and a mechanistic understanding of HCV secretion are incomplete at best. We combined an RNA interference (RNAi) analysis of host factors for infectious HCV secretion with the development of live cell imaging of HCV core trafficking to gain a detailed understanding of HCV egress. RNAi studies identified multiple components of the secretory pathway, including ER to Golgi trafficking, lipid and protein kinases that regulate budding from the trans-Golgi network (TGN), VAMP1 vesicles and adaptor proteins, and the recycling endosome. Our results support a model wherein HCV is infectious upon envelopment at the ER and exits the cell via the secretory pathway. We next constructed infectious HCV with a tetracysteine (TC) tag insertion in core (TC-core) to monitor the dynamics of HCV core trafficking in association with its cellular cofactors. In order to isolate core protein movements associated with infectious HCV secretion, only trafficking events that required the essential HCV assembly factor NS2 were quantified. TC-core traffics to the cell periphery along microtubules and this movement can be inhibited by nocodazole. Sub-populations of TC-core localize to the Golgi and co-traffic with components of the recycling endosome. Silencing of the recycling endosome component Rab11a results in the accumulation of HCV core at the Golgi. The majority of dynamic core traffics in association with apolipoprotein E (ApoE) and VAMP1 vesicles. This study identifies many new host cofactors of HCV egress, while presenting dynamic studies of HCV core trafficking in infected cells