Influence of Alkaline Earth Metals on Structure Formation and Magnesium Alloy Properties

The main aim of this work is to improve the structure and properties of the magnesium alloy ML5 by modifying it with alkaline earth metals (ALM). The separate and joint influence of calcium and barium on the macrostructure and microstructure of the alloy of Mg-Al-Zn system was investigated. The qualitative and quantitative estimation of the structural components was carried out. Alkali earth metals were included in complex intermetallic phases and serve as additional crystallization centers. Modification of magnesium alloys with alkaline earth metals is established in an amount of 0.05 to 0.1 wt. % increased the bulk percentage of intermetallic phases by ~1.5 times, shifting them towards smaller size groups while simultaneously forming spherical intermetallic phases located in the grain centre and serving as additional crystallization centers. In this case, grain size reduction and significant refinement of the alloy structural components were provided. The dependency of the separate and joint influence of alkali earth metals on the castings complex of properties of the magnesium alloy has been established. Thus, a separate modification of the ML5 alloy provided the maximum level of its strength and ductility with the addition of 0.1% Ca or Ba. The modification of the complex (0.1% Ca + 0.1% Ba) of the magnesium alloy decreased the dimensions of its structural components 1.5 times and increased the strength of the alloy by 20%, the ductility by 2 times and the long-term heat resistance 1.5 times due to the formation of the intermetallic phases of the complex composition. Linear dependences were obtained that describe the influence of the characteristics of the structural components of the modified magnesium alloy on its mechanical properties. The developed technology for modifying cast magnesium alloys with alkaline earth elements provides an improvement in casting quality and allows the reliability and durability of responsible casting operation.     

Investigation of the genes for RET and its ligand complex,GDNF/GFRα-1, in small cell lung carcinoma

RET is a receptor tyrosine kinase expressed in neuroendocrine cells and in tumors of these cell types. RET activation may be mediated by a ligand complex comprising glial cell line-derived neurotrophic factor (GDNF) and GDNF family receptor alpha-1 (GFRα-1). Activating RET mutations are found in the inherited cancer syndrome multiple endocrine neoplasia type 2 and in a subset of the related sporadic tumors, medullary thyroid carcinoma and pheochromocytoma, both being derived from neuroendocrine tissues. In one small study, mutations were identified in another tumor with neuroendocrine features, small cell lung carcinoma (SCLC). To determine whether RET mutations contribute to the pathogenesis of SCLC, we examined a panel of 54 SCLC cell lines. No mutations were identified in RET exons 10, 11, and 13–16, regions previously implicated in SCLC or other neuroendocrine tumors. We further examined the expression pattern of RET and the genes encoding the components of its ligand complex GDNF and GFRα-1 , in 21 SCLC lines by using RT-PCR. Although we found no consistent pattern of expression for these three genes, RET was expressed in 57% of SCLC lines. Thus, although RET mutations appear unlikely to be an important step in the tumorigenesis of SCLC, the frequent expression of this gene suggests that RET may have a mitogenic role in a subset of SCLC cell lines. Genes Chromosomes Cancer 21:326–332, 1998. © 1998 Wiley-Liss, Inc.     

Downregulation of putative tumor suppressor gene TSC-22 in human brain tumors

BACKGROUND AND OBJECTIVES: Our objective was to identify differentially expressed genes involved in the pathogenesis of glioblastoma multiforme (GBM). METHODS: Screening of arrayed human fetal brain and human postnatal brain cDNA libraries was performed by differential hybridization with glioblastoma multiforme and human normal brain cDNAs. RESULTS: Repeated differential hybridization of more than 100 cDNA clones selected by primary screening and analysis of RNA from adult normal brain and glial tumors showed 16 nucleotide sequences differentially expressed between normal brain and brain tumors. Among others, decreased content in astrocytic tumors was determined for TSC-22 mRNA corresponding to cDNA in the ICRFp507J1041 clone from human fetal brain cDNA library. Northern blot hybridization of RNA from different human brain tumors showed very low amounts of TSC-22 mRNA in most investigated samples of GBM, anaplastic astrocytoma, and some other tumors. Complete lack of expression of TSC-22 occurred in one sample of anaplastic astrocytoma, as well as in meningioma, brain sarcoma, sarcomatous meningioma, and oligodendroglioma. The differential expression of TSC-22 gene was confirmed by semiquantitative RT-PCR in 15 samples of astrocytomas WHO grade II-IV and three samples of normal brain. CONCLUSIONS: Significantly decreased levels of TSC-22 mRNA in human brain and salivary gland tumors and antiproliferative role of TSC-22 strongly suggest a tumor suppressor role for TSC-22. J.     

Quality with quantity? Evaluating interprofessional faculty prebriefs and debriefs for simulation training using video

BackgroundHigh-fidelity simulation-based training is used increasingly for prelicensure student teams. Such sessions rely on faculty who are able to provide quality prebriefing and debriefing to foster learning among participants. We investigated how well faculty conducted prebriefing and debriefing as part of high-fidelity simulation-based training for interprofessional education.MethodsTwo trained observers independently rated 38 video-recorded sessions of combinations of 4 faculty conducting prebriefings and debriefings of prelicensure student teams after high-fidelity simulation-based training. Assessment was undertaken using the Objective Structured Assessment of Debriefing, an 8-item tool using a 5-point Likert scale (1 as minimum and 5 as maximum). Mean scores for each item were calculated. Inter-rater agreement was determined using Cohen’s kappa. A one-way between-subjects analysis of variance with post-hoc Tukey’s studentized range procedure was conducted to compare the effect of team facilitator grouping on the quality of team performance of each Objective Structured Assessment of Debriefing element during a prebriefing or a debriefing. Trend analyses of teams with 4 or more observations were performed using Kendall’s Tau coefficient test and linear regression analyses to identify whether teams showed improvement through time. Statistical significance was set at P < .05.ResultsA total of 7 combinations of faculty conducted between 1 to 14 prebriefings or debriefings. In general, faculty combinations performed better during debriefings compared with prebriefings, with only 1 team having 1 mean item score <3.50. Statistically significant differences between faculty combinations in mean item scores was more pronounced during the prebriefings (2 of 3 Objective Structured Assessment of Debriefing items rated) than during debriefings (1 of 8 Objective Structured Assessment of Debriefing items rated). Effect sizes were strong for all differences. Linear regression analysis revealed a statistically significant change through time for the 3 rated prebriefing items and for 7 of the 8 rated debriefing items.ConclusionInterprofessional faculty combinations in this study tended to have good quality prebriefings and debriefings. The quality of the prebriefings and debriefings can, however, be influenced by the composition of the facilitator teams, most prominently for prebriefings, and team performance does appear to change through time, especially during the debriefing. Future work will focus on whether the quality of prebriefings and debriefings influences learning by trainees.     

Frequencies of micronucleated lymphocytes and Epstein-Barr virus contamination in Altai region residents living near the Semipalatinsk atomic testing ground

We assessed the frequencies of micronucleated lymphocytes in 3,036 individuals living in 16 settlements in the western part of the Altai region. The majority of individuals with significantly high frequencies of micronucleated lymphocytes were detected in settlements adjacent to the Semipalatinsk atomic testing ground (SATG). The most considerable genome instability was found in individuals born in the period of intensive testing at the SATG (1949 to 1962). Moreover, we determined that the residents of the settlements adjacent to the SATGhave significantly high levels of antibodies to potentially oncogenic Epstein-Barr virus, in addition to high frequencies of micronucleated lymphocytes. The considerable Epstein-Barr virus contamination among the residents in the radiation-polluted zone around the SATG was supposed to be caused by immunodeficiency disorders in these individuals and was correlated with high frequencies of micronucleated cells. Environ. Mol. Mutagen. 31:11–17, 1998. © Wiley-Liss, Inc.     

Stimulus‐evoked potentials contribute to map the epileptogenic zone during stereo‐EEG presurgical monitoring

Presurgical monitoring with intracerebral electrodes in patients with drug‐resistant focal epilepsy represents a standard invasive procedure to localize the sites of seizures origin, defined as the epileptogenic zone (EZ). During presurgical evaluation, intracerebral single‐pulse electrical stimulation (SPES) is performed to define the boundaries of eloquent areas and to evoke seizure‐associated symptoms. Extensive intracranial exploration and stimulation generate a large dataset on brain connectivity that can be used to improve EZ detection and to understand the organization of the human epileptic brain. We developed a protocol to analyse field responses evoked by intracranial stimulation. Intracerebral recordings were performed with 105–162 recording sites positioned in fronto‐temporal regions in 12 patients with pharmacoresistant focal epilepsy. Recording sites were used for bipolar SPES at 1 Hz. Reproducible early and late phases (<60 ms and 60–500 ms from stimulus artefact, respectively) were identified on averaged evoked responses. Phase 1 and 2 responses recorded at all and each recording sites were plotted on a 3D brain reconstructions. Based on connectivity properties, electrode contacts were primarily identified as receivers, mainly activators or bidirectional. We used connectivity patterns to construct networks and applied cluster partitioning to study the proprieties between potentials evoked/stimulated in different regions. We demonstrate that bidirectional connectivity during phase 1 is a prevalent feature that characterize contacts included in the EZ. This study shows that the application of an analytical protocol on intracerebral stimulus‐evoked recordings provides useful information that may contribute to EZ detection and to the management of surgical‐remediable epilepsies. Hum Brain Mapp 35:4267–4281, 2014. © 2014 Wiley Periodicals, Inc .     

Role of cannabinoid receptors in the regulation of cardiac contractility during ischemia/reperfusion

We studied the effect of selective ligands of cannabinoid (CB) receptors on contractility of isolated Langendorff-perfused rat heart under conditions of 45-min total ischemia and 30-min reperfusion. Perfusion with a solution containing selective CB receptor agonist HU-210 for 10 min before ischemia increased the severity of reperfusion contractile dysfunction. This drug decreased left ventricular developed pressure and maximum rates of contraction and relaxation, but had no effect on heart rate and end-diastolic pressure. The negative inotropic effect of the drug was transitory and disappeared after 5-min reperfusion. Pretreatment with selective CB1 receptor antagonist SR141716A and selective CB2 receptor antagonist SR144528 had no effect on heart rate and myocardial contractility during reperfusion. Our results indicate that stimulation of CB receptors can increase the degree of reperfusion-induced cardiac contractile dysfunction. However, endogenous cannabinoids are not involved in the development of myocardial contractile dysfunction during ischemia/reperfusion of the isolated heart. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 142, No. 11, pp. 500–504, November, 2006