Transverse momentum fluctuations and percolation of strings

The behaviour of the transverse momentum fluctuations with the centrality of the collision shown by the Relativistic Heavy Ion Collider data is naturally explained by the clustering of color sources. In this framework, elementary color sources --strings-- overlap forming clusters, so the number of effective sources is modified. These clusters decay into particles with mean transverse momentum that depends on the number of elementary sources that conform each cluster, and the area occupied by the cluster. The transverse momentum fluctuations in this approach correspond to the fluctuations of the transverse momentum of these clusters, and they behave essentially as the number of effective sources.Comment: 16 pages, RevTex, 4 postscript figures. Enhanced version. New figure

New tools in percutaneous minimally invasive chronic subdural hematomas evacuation

Background: Incidence of chronic subdural hematomas (cSDH) is expected to progressive rise in the next decades. There is no univocal indication of the approach to be used. Furthermore, there is no data about the efficacy of twist drill craniostomy (TDC) in hematomas with membranes. Objective: To describe our modified technique for TDC in patients affected by cSDH with membranes and in treatment with antiplatelets. Methods: We analyzed a group of 37 patients, affected by cSDH with membrane (type D laminar membrane and type G trabecular membrane according to Nakaguchi classification), treated with mushroom TDC using a modified technique. Results: After surgery the average maximum thickness of the common postoperative liquoral subdural collection decreased from 18.8 to 6.21 mm. We documented one acute subdural hematoma (2.7%), asymptomatic and not treated, and one recurrence of cSDH (2.7%) after 2 months that needed re-intervention with single burr hole. Conclusions: We presented a modified twist drill technique, characterized by the introduction of an application of a new device that optimizes both surgical results, clinical outcome and surgical procedure time. The presence of membrane type D and G does not affect the efficacy of drainage, that is negatively related to the presence of clots or acute hematoma. This modified technique is safe, fast, effective and represents a valid first line treatment of an unstable and unpredictable pathology such as cSDH. We suggest performing such technique on a larger patients’ cohort to further validate its effectiveness

Peripheral facial palsy following ventriculoperitoneal shunt. The lesson we have learned

The most frequent complications after shunt surgery are infective and obstructive. Other types are less common, and eventually occur due to technical errors during brain ventricular puncture, opening the intraperitoneal cavity or the tunnelling of the catheter between the two points. Although rare, there are well-reported complications related to the poor positioning of the distal catheter, with perforation of organs and tissues. We report a very rare case of a male patient with normal pressure hydrocephalus submitted to ventriculoperitoneal shunt. During tunnelling of the shunt stylet, a peripheral facial palsy due to injury to the extra cranial segment of the facial nerve occurred. To the best of our knowledge this is the second case described in Literature. The patient and the surgeon should be aware of this very rare but possible complication in shunt surgery being careful to the course of the facial nerve in the mastoid region

Rapid malignant progression of an intraparenchymal choroid plexus papillomas

Background: Choroid plexus tumors (CPTs) are rare neoplasms accounting for only 0.3-0.6% of all brain tumors in adults and 2-5% in children. The World Health Organization (WHO) classification describes three histological grades: grade I is choroid plexus papilloma (CPP), grade II is atypical papilloma, and grade III is the malignant form of carcinoma. In adults, CPTs rarely have a supratentorial localization. Case Description: Here we report a very rare case of an intraparenchymal parietal CPP with a rapid histological transition from grade I to grade III WHO in a 67-year-old man, in <7 months. Conclusion: Because of the rarity of these oncotypes, descriptions of each new case are useful, mostly to consider this diagnostic entity in extraventricular brain tumors of adults, despite an unusual location

Epigenetic reprogramming of breast cancer cells with oocyte extracts

<p>Abstract</p> <p>Background</p> <p>Breast cancer is a disease characterised by both genetic and epigenetic alterations. Epigenetic silencing of tumour suppressor genes is an early event in breast carcinogenesis and reversion of gene silencing by epigenetic reprogramming can provide clues to the mechanisms responsible for tumour initiation and progression. In this study we apply the reprogramming capacity of oocytes to cancer cells in order to study breast oncogenesis.</p> <p>Results</p> <p>We show that breast cancer cells can be directly reprogrammed by amphibian oocyte extracts. The reprogramming effect, after six hours of treatment, in the absence of DNA replication, includes DNA demethylation and removal of repressive histone marks at the promoters of tumour suppressor genes; also, expression of the silenced genes is re-activated in response to treatment. This activity is specific to oocytes as it is not elicited by extracts from ovulated eggs, and is present at very limited levels in extracts from mouse embryonic stem cells. Epigenetic reprogramming in oocyte extracts results in reduction of cancer cell growth under anchorage independent conditions and a reduction in tumour growth in mouse xenografts.</p> <p>Conclusions</p> <p>This study presents a new method to investigate tumour reversion by epigenetic reprogramming. After testing extracts from different sources, we found that axolotl oocyte extracts possess superior reprogramming ability, which reverses epigenetic silencing of tumour suppressor genes and tumorigenicity of breast cancer cells in a mouse xenograft model. Therefore this system can be extremely valuable for dissecting the mechanisms involved in tumour suppressor gene silencing and identifying molecular activities capable of arresting tumour growth. These applications can ultimately shed light on the contribution of epigenetic alterations in breast cancer and advance the development of epigenetic therapies.</p

Principles of early human development and germ cell program from conserved model systems

Human primordial germ cells (hPGCs), the precursors of sperm and eggs, originate during week 2-3 of early postimplantation development(1). Using in vitro models of hPGC induction(2-4), recent studies suggest striking mechanistic differences in specification of human and mouse PGCs(5). This may partly be due to the divergence in their pluripotency networks, and early postimplantation development(6-8). Since early human embryos are inaccessible for direct studies, we considered alternatives, including porcine embryos that, as in humans, develop as bilaminar embryonic discs. Here we show that porcine PGCs (pPGCs) originate from the posterior pre-primitive streak competent epiblast by sequential upregulation of SOX17 and BLIMP1 in response to WNT and BMP signalling. Together with human and monkey in vitro models simulating peri-gastrulation development, we show conserved principles for epiblast development for competency for PGC fate, followed by initiation of the epigenetic program(9-11), regulated by a balanced SOX17–BLIMP1 gene dosage. Our combinatorial approach using human, porcine and monkey in vivo and in vitro models, provides synthetic insights on early human development

Principles of early human development and germ cell program from observed model systems

Human primordial germ cells (hPGCs), the precursors of sperm and eggs, originate during weeks 2–3 of early post-implantation development$^{1}$. Using $\textit{in vitro}$ models of hPGC induction$^{2, 3, 4}$, recent studies have suggested that there are marked mechanistic differences in the specification of human and mouse PGCs$^{5}$. This may be due in part to the divergence in their pluripotency networks and early post-implantation development$^{6, 7, 8}$. As early human embryos are not accessible for direct study, we considered alternatives including porcine embryos that, as in humans, develop as bilaminar embryonic discs. Here we show that porcine PGCs originate from the posterior pre-primitive-streak competent epiblast by sequential upregulation of SOX17 and BLIMP1 in response to WNT and BMP signalling. We use this model together with human and monkey $\textit{in vitro}$ models simulating peri-gastrulation development to show the conserved principles of epiblast development for competency for primordial germ cell fate. This process is followed by initiation of the epigenetic program$^{9, 10, 11}$ and regulated by a balanced $\textit{SOX17–BLIMP1}$ gene dosage. Our combinatorial approach using human, porcine and monkey $\textit{in vivo}$ and $\textit{in vitro}$ models provides synthetic insights into early human development.Wellcome Trust Medical Research Council BBSR

Reprogrammed Transcriptome in Rhesus-Bovine Interspecies Somatic Cell Nuclear Transfer Embryos

Global activation of the embryonic genome (EGA), one of the most critical steps in early mammalian embryo development, is recognized as the time when interspecies somatic cell nuclear transfer (iSCNT) embryos fail to thrive.In this study, we analyzed the EGA-related transcriptome of rhesus-bovine iSCNT 8- to 16-cell embryos and dissected the reprogramming process in terms of embryonic gene activation, somatic gene silencing, and maternal RNA degradation. Compared with fibroblast donor cells, two thousand and seven genes were activated in iSCNT embryos, one quarter of them reaching expression levels comparable to those found in in vitro fertilized (IVF) rhesus embryos. This suggested that EGA in iSCNT embryos had partially recapitulated rhesus embryonic development. Eight hundred and sixty somatic genes were not silenced properly and continued to be expressed in iSCNT embryos, which indicated incomplete nuclear reprogramming. We compared maternal RNA degradation in bovine oocytes between bovine-bovine SCNT and iSCNT embryos. While maternal RNA degradation occurred in both SCNT and iSCNT embryos, we saw more limited overall degradation of maternal RNA in iSCNT embryos than in SCNT embryos. Several important maternal RNAs, like GPF9, were not properly processed in SCNT embryos.Our data suggested that iSCNT embryos are capable of triggering EGA, while a portion of somatic cell-associated genes maintain their expression. Maternal RNA degradation seems to be impaired in iSCNT embryos. Further understanding of the biological roles of these genes, networks, and pathways revealed by iSCNT may expand our knowledge about cell reprogramming, pluripotency, and differentiation