Charge exchange in relativistic heavy ion collisions

Elastic charge-exchange in relativistic heavy ion collisions is responsible for the non-disruptive change of the charge state of the nuclei. We show that it can be reliably calculated within the eikonal approximation for the reaction part. The formalism is applied to the charge-pickup cross sections of 158 GeV/nucleon Pb projectiles on several targets. The relative contributions of pion- and rho-exchange are determined, using a single-particle model for the internal structure of the nuclei. The calculated cross sections are non-negligible for heavy targets. It is shown that these cross sections can be useful to obtain information on the Gamow-Teller transition strengths of the nuclei.Comment: 12 pages, 4 postscript figure

Resonant plasma excitation by single-cycle THz pulses

In this paper, an alternative perspective for the generation of millimetric high-gradient resonant plasma waves is discussed. This method is based on the plasma-wave excitation by energetic single-cycle THz pulses whose temporal length is comparable to the plasma wavelength. The excitation regime discussed in this paper is the quasi-nonlinear regime that can be achieved when the normalized vector potential of the driving THz pulse is on the order of unity. To investigate this regime and determine the strength of the excited electric elds, a Particle-In-Cell (PIC) code has been used. It has been found that by exploiting THz pulses with characteristics currently available in laboratory, longitudinal electron plasma waves with electric gradients up to hundreds MV/m can be obtained. The mm-size nature of the resonant plasma wave can be of great utility for an acceleration scheme in which high-brightness electron bunches are injected into the wave to undergo a strong acceleration. The long-size nature of the acceleration bucket with respect to the short length of the electron bunches can be handled in a more robust manner in comparison with the case when micrometric waves are employed

New Ultra Small Iron-Oxide Nanoparticles with Titanium-Carbamate Coating: Preparation and Magnetic Properties

This work deals with the preparation and chemical characterization of new Ultra-Small Iron-Oxide Superparamagnetic Nanoparticles (USPIONs) functionalized with Titanium-carbamate. The synthesis was performed starting from oleate-coated and 2-pyrrolidone-coated USPIONs having a maghemite ( -Fe2O3) and magnetite (Fe3O4) crystalline core, respectively. Zero-field-cooled (ZFC) and field-cooled (FC) magnetic susceptibility curves as well as the magnetization behavior as a function of temperature are reported and discussed in view of the superparamagnetic properties and coating effect of these new magnetic nanoparticles. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3545

UV and genotoxic stress induce ATR relocalization in mouse spermatocytes

During meiosis, phosphorylation of H2AX is one of the earliest cellular responses to the generation of DNA double-strand breaks (DSBs) by the SPO11 topoisomerase. ATM is the kinase which mediates the formation of phosphorylated H2AX (H2AX) meiotic foci, while ATR is the kinase which signals chromosome asynapsis at the level of the XY bivalent. To investigate the possible role of ATR also in DNA damage signalling in meiotic cells, we studied the effect of UV radiation and chemotherapy drugs on H2AX phosphorylation and ATR relocalization in mouse pachytene spermatocytes. Here, we report that UV, a single strand break DNA-damaging agent, induces ATR relocalization from the XY sex body to nuclear foci and intense H2AX phosphorylation. Other DNA damage proteins such as MDC1, NBS1 and 53BP1 showed a similar relocalization following UVA microirradiation of spermatocytes. We found that DNA damage induced by UV increased the intensity and the number of H2AX foci also in Atm null spermatocytes. Inhibition of RNA synthesis was found to induce the formation of H2AX foci, but it did not influence the DNA damage response to UV irradiation. Finally, exposure of spermatocytes to double strand break DNA-damaging agents such as cisplatin, bleomycin or etoposide also induced ATR relocalization and intense H2AX phosphorylation and led to anomalies in synaptonemal assembly. Our results demonstrate that DNA damage induced by genotoxic stress can activate ATR and influence meiotic chromatin remodelling through H2AX phosphorylation, likely as part of a response which normally ensures germ cell genomic integrity

Fgf9 inhibition of meiotic differentiation in spermatogonia is mediated by Erk-dependent activation of Nodal-Smad2/3 signaling and is antagonized by Kit Ligand

Both fibroblast growth factor 9 (Fgf9) and Kit Ligand (Kl) signal through tyrosine kinase receptors, yet they exert opposite effects on meiotic differentiation in postnatal spermatogonia, Fgf9 acting as a meiosis-inhibiting substance and Kl acting as a promoter of the differentiation process. To understand the molecular mechanisms that might underlie this difference, we tried to dissect the intracellular signaling elicited by these two growth factors. We found that both Fgf9 and Kl stimulate Erk1/2 activation in Kit+ (differentiating) spermatogonia, even though with different time courses, whereas Kl, but not Fgf9, elicits activation of the Pi3k-Akt pathway. Sustained Erk1/2 activity promoted by Fgf9 is required for induction of the autocrine Cripto-Nodal-Smad2/3 signaling loop in these cells. Nodal signaling, in turn, is essential to mediate Fgf9 suppression of the meiotic program, including inhibition of Stra8 and Scp3 expression and induction of the meiotic gatekeeper Nanos2. On the contrary, sustained activation of the Pi3k-Akt pathway is required for the induction of Stra8 expression elicited by Kl and retinoic acid. Moreover, we found that Kl treatment impairs Nodal mRNA expression and Fgf9-mediated Nanos2 induction, reinforcing the antagonistic effect of these two growth factors on the meiotic fate of male germ cells

The Potential of Omega-3 Supplementation to Reduce Muscle-Inflammation after Muscle-Damaging Exercise

Muscle Damaging exercise (EIMD) induces inflammation and relates to strength loss, muscle-soreness and impaired recovery. Overall, this means a performance impairment which might be relevant for those who engages in competitions or strenuous physical activities. It remains unclear whether Omega-3 fatty acids (O-3) supplementation blunts the exercise-induced inflammation associated with EIMD and therefore prevents performance impairment. PURPOSE: Following a three-week supplementation with O-3, indirect markers of muscle damage were examined after a bout of EIMD to determine if supplementation had any beneficial effect in maintaining leg-strength levels. METHODS: Eight healthy, recreationally active caucasian males (28.13 ± 3.4 yr) were randomly allocated to a supplementation group (SUP, n = 4) to receive 2.85g/day O-3 supplementation or a control group (CON, n = 4) for three weeks. Following supplementation, participants performed a bout of EIMD, which consisted of performing 10 sets of 15 repetitions of leg extension at a self-assessed intensity of 7/10 on the Rate of Perceived Exertion scale. Creatine Kinase (CK) from venous blood samples, isometric right-leg strength, squat-jump test and perceived soreness were determined, as indirect markers of muscle-damage at Baseline, immediately after EIMD (POST) and 48 hours after EIMD to coincide with the delayed muscle inflammatory response. RESULTS: No statistically significant differences were found between Baseline and POST. There was a trend for smaller increase of CK levels (pre vs 48-h post EIMD) on the SUP group (38.8% increase) compared with the CON group (105.6% increase; P = 0.051). There was no significant effect (baseline vs. 48-h post EIMD) on muscle strength between SUP and CON group (P > 0.05), however, CON showed a larger decrease in strength compared to SUP (> 6.3% vs SUP). No differences in jump height were found between SUP and CON (P > 0.05). There was no significant difference in muscle soreness at 48-h post EIMD between SUP and CON group (P = 0.171). CONCLUSION: Three weeks of O-3 supplementation might decrease exercise-induced muscle inflammation after eccentric exercise. The lack of statistical significance may be adduced to the limitations of the study design and sample size. Supplementation with O-3 can be beneficial in athletes undergoing heavy exercise regimes and in sedentary individuals restarting physical activity, decreasing the exercise related muscle inflammation. The encouraging results from this pilot study have led to designing further work related to this topic

Difficult management of an extremely rare case of giant pigmented epithelioid melanocytoma

Pigmented epithelioid melanocytoma (PEM), a heavily pigmented and highly uncommon melanocytic lesion, is extremely rare. It comes under several forms and names. We report the case of a three-year-old boy born with an isolated right lumbopelvic and femoral giant PEM. The boy was unable to walk due to the size and the shape of the lesion. He underwent two stages of intra lesional resections, one in Benin and the second in Switzerland. The first surgery was followed by hypothetic hypovolemic and anaphylactic shocks, and the second surgery by a continuous lymphatic leakage from the wounds for months. The strategic management approach, the surgery and follow-up of this case of giant PEM presented a real challenge. (C) 2017 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND licens

Developmental expression of BMP4/ALK3/SMAD5 signaling pathway in the mouse testis: a potential role of BMP4 in spermatogonia differentiation

It is well established that the c-kit gene plays an essential role in the proliferation of differentiating spermatogonia in prepuberal mice. However, the mechanisms that regulate the onset of spermatogenesis, i.e. differentiation of spermatogonial stem cells and c-kit expression, are poorly understood. Here we identify a novel signal transduction system in mouse prepuberal testis regulating this developmental event, involving bone morphogenetic protein 4 (BMP4) and its transduction machinery. BMP4 is produced by Sertoli cells very early in the postnatal life and is successively down regulated in peri-puberal Sertoli cells. Its receptor Alk3 and the R-Smad Smad5 are specifically expressed both in proliferating primordial germ cells and in postnatal spermatogonia. BMP4 stimulation of cultured spermatogonia induces Smad4/5 nuclear translocation and the formation of a DNA-binding complex with the transcriptional coactivator p300/CBP. In vitro exposure of undifferentiated spermatogonia to BMP4 exerts both mitogenic and differentiative effects, inducing [3H]thymidine incorporation and Kit expression. As a result of the latter event, Kit-negative spermatogonia acquire sensitivity to Stem Cell Factor

Transcriptome analysis of differentiating spermatogonia stimulated with kit ligand

Kit ligand (KL) is a survival factor and a mitogenic stimulus for differentiating spermatogonia. However, it is not known whether KL also plays a role in the differentiative events that lead to meiotic entry of these cells. We performed a wide genome analysis of difference in gene expression induced by treatment with KL of spermatogonia from 7-day-old mice, using gene chips spanning the whole mouse genome. The analysis revealed that the pattern of RNA expression induced by KL is compatible with the qualitative changes of the cell cycle that occur during the subsequent cell divisions in type A and B spermatogonia, i.e. the progressive lengthening of the S phase and the shortening of the G2/M transition. Moreover, KL up-regulates in differentiating spermatogonia the expression of early meiotic genes (for instance: Lhx8, Nek1, Rnf141, Xrcc3, Tpo1, Tbca, Xrcc2, Mesp1, Phf7, Rtel1), whereas it down-regulates typical spermatogonial markers (for instance: Pole, Ptgs2, Zfpm2, Egr2, Egr3, Gsk3b, Hnrpa1, Fst, Ptch2). Since KL modifies the expression of several genes known to be up-regulated or down-regulated in spermatogonia during the transition from the mitotic to the meiotic cell cycle, these results are consistent with a role of the KL/kit interaction in the induction of their meiotic differentiation