253 research outputs found

    Thin sections techniques in fossil remains of mammals impregnated with asphalt

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    Paleohistological studies of vertebrates are based on the analysis and interpretation of bone microstructure of petrographic thin sections. These sections are mainly performed following standard techniques; however, the methodology can vary according to the particular characteristics of the sample (e.g. skeletal element, type of preservation) or the purpose of the work. As part of a paleohistological study on Equus occidentalis recovered from a Late Pleistocene asphalt seep ("tar pit"), Rancho La Brea (California, United States), in this contribution we describe the technique used to make thin sections of fossils impregnated with asphalt. The hydrocarbons act as a release agent, which causes the resins commonly used for glued or embedding not to adhere to the fossil remains. For chip preparation (=block) the sample were embedded in a large volume of low-viscosity epoxy resin, which generated a higher shrinkage and prevented the separation of the chip components (resin / fossil). The chip must be mounted on the glass slide using UV acrylic resin, which, unlike epoxy resins, does not require heat application, optimizes adhesion, and reduces the curing time, offering the possibility of cutting and polishing quickly after mounting. During polishing, it was necessary to reduce the cleaning time with ultrasound to avoid peeling and loss of portions of the sample. Based on the results obtained, we consider that this variant of the traditional methodology is optimal to work with fossils preserved in this particular context, as it allows making complete thin sections without altering the original osteohistological features.Fil: Garrone, Mariana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; ArgentinaFil: Ortiz, Herácleo O.. Universidad Nacional del Sur. Departamento de Geología; ArgentinaFil: Prado, José L.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano. Universidad Nacional del Centro de la Provincia de Buenos Aires. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano; Argentina2nd Palaeontological Virtual CongressEspañaPalaeontological Virtual Congres

    Probing gas adsorption in zeolites by variable-temperature IR spectroscopy: An overview of current research

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    The current state of the art in the application of variable-temperature IR (VTIR) spectroscopy to the study of (i) adsorption sites in zeolites, including dual cation sites; (ii) the structure of adsorption complexes and (iii) gas-solid interaction energy is reviewed. The main focus is placed on the potential use of zeolites for gas separation, purification and transport, but possible extension to the field of heterogeneous catalysis is also envisaged. A critical comparison with classical IR spectroscopy and adsorption calorimetry shows that the main merits of VTIR spectroscopy are (i) its ability to provide simultaneously the spectroscopic signature of the adsorption complex and the standard enthalpy change involved in the adsorption process; and (ii) the enhanced potential of VTIR to be site specific in favorable cases

    Expression and subcellular localization of the bromodomain-containing protein 7 is a prognostic biomarker in breast cancer

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    Bromodomain-containing protein 7 (BRD7) is a member of the bromodomain-containing protein family. Previous studies suggest that BRD7 is predominantly localized in the nucleus, wherein it functions as a transcriptional regulator. Several lines of evidence imply a tumour suppressor function for BRD7. However, the importance of BRD7 in the pathogenesis of breast cancer is not well understood. We have investigated the expression, CpG island methylation and subcellular localization of BRD7 in breast cancer cell lines and clinical cases and thereby assessed its prognostic significance by correlating with clinical-pathological features and time-dependent clinical outcomes. We show that nuclear exclusion of BRD7 occurs commonly in breast cancer and is strongly associated with cases expressing wild-type p53. Moreover, clinical outcomes are significantly less favourable in cases with nuclear exclusion or loss of expression than those in which there is nuclear expression of BRD7. Methylation of the CpG island of BRD7 increases in breast cancer relative to normal breast tissue, but there is not an obvious correlation between methylation and reduced expression or between methylation and clinical outcomes. Overall, our results suggest that nuclear exclusion, rather than transcriptional silencing, is a common mechanism by which the tumour suppressor function of wild-type p53 is inhibited in breast cancer, and show that BRD7 is a promising candidate biomarker in breast cancer

    Composite risk and benefit from adjuvant dose-dense chemotherapy in hormone receptor-positive breast cancer

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    The GIM2 phase III trial demonstrated the benefit of dose-dense chemotherapy in node-positive early breast cancer (eBC). To better define the dose-dense effect in the hormone receptor-positive subgroup, we evaluated its benefit through a composite measure of recurrence risk. We conducted an ancillary analysis of the GIM2 trial evaluating the absolute treatment effect through a composite measure of recurrence risk (CPRS) in patients with hormone receptor-positive HER2-negative eBC. CPRS was estimated through Cox proportional hazards models applied to the different clinicopathological features. The treatment effect was compared to the values of CPRS by using the Sub-population Treatment Effect Pattern Plot (STEPP) process. The Disease-Free Survival (DFS)-oriented STEPP analysis showed distinct patterns of relative treatment effect with respect to CPRS. Overall, 5-year DFS differed across CPRS quartiles ranging from 95.2 to 66.4%. Each CPRS quartile was characterized by a different patients\u2019 composition, especially for age, lymph node involvement, tumor size, estrogen and progesterone receptor expression, and Ki-67. A number needed to treat of 154 and 6 was associated with the lowest and the highest CPRS quartile, respectively. Dose-dense adjuvant chemotherapy showed a consistent benefit in node-positive eBC patients with hormone receptor-positive HER2-negative disease, but its effect varied according to CPRS

    Association of tumor-infiltrating lymphocytes with distant disease-free survival in the ShortHER randomized adjuvant trial for patients with early HER2+ breast cancer.

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    BACKGROUND: There is the need to identify new prognostic markers to refine risk stratification for HER2-positive early breast cancer patients. The aim of this study was to evaluate the association of tumor-infiltrating lymphocytes (TILs) with distant disease-free survival (DDFS) in patients with HER2-positive early breast cancer enrolled in the ShortHER adjuvant trial which compared 9 weeks versus 1-year trastuzumab in addition to chemotherapy, and to test the interaction between TILs and treatment arm. PATIENTS AND METHODS: Stromal TILs were assessed for 866 cases on centralized hematoxylin and eosin-stained tumor slides. The association of TILs as 10% increments with DDFS was assessed with Cox models. Kaplan-Meier curves were estimated for patients with TILs\u2009 6520% and TILs\u2009<20%. Median follow-up was 6.1\u2009years. RESULTS: Median TILs was 5% (Q1-Q3 1%-15%). Increased TILs were independently associated with better DDFS in multivariable model [hazard ratio (HR) 0.73, 95% confidence interval (CI) 0.59-0.89, P\u2009=\u20090.006, for each 10% TILs increment]. Five years DDFS rates were 91.1% for patients with TILs\u2009<20% and 95.7% for patients with TILs\u2009 6520% (P\u2009=\u20090.025). The association between 10% TILs increments and DDFS was significant for patients randomized to 9\u2009weeks of trastuzumab (HR 0.60, 95% CI 0.41-0.88) but not for patients treated with 1\u2009year of trastuzumab (HR 0.89, 95% CI 0.71-1.12; test for interaction P\u2009=\u20090.088). For patients with TILs\u2009<20%, the HR for the comparison between the short versus the long arm was 1.75 (95% CI 1.09-2.80, P=0.021); whereas, for patients with TILs\u2009 6520% the HR for the comparison of short versus long arm was 0.23 (95% CI 0.05-1.09, P\u2009=\u20090.064), resulting in a significant interaction (P\u2009=\u20090.015). CONCLUSIONS: TILs are an independent prognostic factor for HER2-positive early breast cancer patients treated with adjuvant chemotherapy and trastuzumab and may refine the ability to identify patients at low risk of relapse eligible for de-escalated adjuvant therapy
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