221 research outputs found

    25 years of satellite InSAR monitoring of ground instability and coastal geohazards in the archaeological site of Capo Colonna, Italy

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    For centuries the promontory of Capo Colonna in Calabria region, southern Italy, experienced land subsidence and coastline retreat to an extent that the archaeological ruins of the ancient Greek sanctuary are currently under threat of cliff failure, toppling and irreversible loss. Gas extraction in nearby wells is a further anthropogenic element to account for at the regional scale. Exploiting an unprecedented satellite Synthetic Aperture Radar (SAR) time series including ERS-1/2, ENVISAT, TerraSAR-X, COSMO-SkyMed and Sentinel-1A data stacks acquired between 1992 and 2016, this paper presents the first and most complete Interferometric SAR (InSAR) baseline assessment of land subsidence and coastal processes affecting Capo Colonna. We analyse the regional displacement trends, the correlation between vertical displacements with gas extraction volumes, the impact on stability of the archaeological heritage, and the coastal geohazard susceptibility. In the last 25 years, the land has subsided uninterruptedly, with highest annual line-of-sight deformation rates ranging between -15 and -20 mm/year in 2011-2014. The installation of 40 pairs of corner reflectors along the northern coastline and within the archaeological park resulted in an improved imaging capability and higher density of measurement points. This proved to be beneficial for the ground stability assessment of recent archaeological excavations, in an area where field surveying in November 2015 highlighted new events of cliff failure. The conceptual model developed suggests that combining InSAR results, geomorphological assessments and inventorying of wave-storms will contribute to unveil the complexity of coastal geohazards in Capo Colonna. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

    Expression of BNIP3 in invasive breast cancer: correlations with the hypoxic response and clinicopathological features

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    <p>Abstract</p> <p>Background</p> <p>Bcl-2/adenovirus E1B 19 kDa-interacting protein 3 (BNIP3) is a pro-apoptotic member of the Bcl-2 family induced under hypoxia. Low or absent expression has recently been described in human tumors, including gastrointestinal tumors, resulting in poor prognosis. Little is known about BNIP3 expression in invasive breast cancer. The aim of the present study was to investigate the expression of BNIP3 in invasive breast cancer at the mRNA and protein level in correlation with the hypoxic response and clinicopathological features.</p> <p>Methods</p> <p>In 40 cases of invasive breast cancer, BNIP3 mRNA <it>in situ </it>hybridization was performed on frozen sections with a digoxigenin labeled anti-BNIP3 probe. Paraffin embedded sections of the same specimens were used to determine protein expression of BNIP3, Hypoxia Inducible Factor 1 alpha (HIF-1α) and its downstream targets Glucose Transporter 1 (Glut-1) and Carbonic Anhydrase (CAIX) by immunohistochemistry.</p> <p>Results</p> <p>BNIP3 mRNA was expressed in 16/40 (40%) of the cases and correlated with BNIP3 protein expression (p = 0.0218). Neither BNIP3 protein nor mRNA expression correlated with expression of HIF-1α expression or its downstream targets. Tumors which showed loss of expression of BNIP3 had significantly more often lymph node metastases (82% vs 39%, p = 0.010) and showed a higher mitotic activity index (p = 0.027). BNIP3 protein expression was often nuclear in normal breast, but cytoplasmic in tumor cells.</p> <p>Conclusion</p> <p>BNIP3 expression is lost in a significant portion of invasive breast cancers, which is correlated with poor prognostic features such as positive lymph node status and high proliferation, but not with the hypoxic response.</p

    Potential use of APSIS-InSAR measures of the range of vertical surface motion to improve hazard assessment of peat landslides

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    Peat landslides represent a notable natural hazard that is difficult to assess across complex blanket bog terrain. To aid the assessment of peat landslide susceptibility, we propose a new metric, the range of vertical surface motion (RVSM), quantified from time series data of surface motion measured using interferometric synthetic aperture radar (InSAR). Our expectation is that areas that are more susceptible to landslide will display a high RVSM that is indicative of high amplitude swelling and shrinking of the peat in response to changes in the volume of water stored in the peat over time. To test our hypothesis we examined the spatial distribution of high RVSM values that preceded three peat landslides in Ireland in 2020 and over a large area of blanket bog. We observed that high RVSM was closely associated with the known failures and with inferred points of initial failure, and that the areas of high RVSM were detectable up to two years in advance of failure. In the blanket bog landscape, high RVSM was associated with areas where landscape hydrology would favour thick peat and subsequent potential instability. We conclude that RVSM mapping has potential for refining national-scale assessments of peat landslide susceptibility

    Is no news good news? Inconclusive genetic test results in BRCA1 and BRCA2 from patients and professionals' perspectives

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    <p>Abstract</p> <p>Background</p> <p>Women from families with a high risk of breast or ovarian cancer in which genetic testing for mutations in the <it>BRCA1/2 </it>genes is inconclusive are a vulnerable and understudied group. Furthermore, there are no studies of the professional specialists who treat them - geneticists, genetic counsellors/nurses, oncologists, gynaecologists and breast surgeons.</p> <p>Methods</p> <p>We conducted a small qualitative study that investigated women who had developed breast cancer under the age of 45 and who had an inconclusive <it>BRCA1/2 </it>genetic diagnostic test (where no mutations or unclassified variants were identified). We arranged three focus groups for affected women and their close female relatives - 13 women took part. We also interviewed 12 health professionals who were involved in the care of these women.</p> <p>Results</p> <p>The majority of the women had a good grasp of the meaning of their own or a family member's inconclusive result, but a few indicated some misunderstanding. Most of the women in this study underwent the test for the benefit of others in the family and none mentioned that they were having the test purely for themselves. A difficult issue for sisters of affected women was whether or not to undertake prophylactic breast surgery. The professionals were sensitive to the difficulties in explaining an inconclusive result. Some felt frustrated that technology had not as yet provided them with a better tool for prediction of risk.</p> <p>Conclusions</p> <p>Some of the women were left with the dilemma of what decision to make regarding medical management of their cancer risk. For the most part, the professionals believed that the women should be supported in whatever management decisions they considered best, provided these decisions were based on a complete and accurate understanding of the genetic test that had taken place in the family.</p

    Tropical peat surface oscillations are a function of peat condition at North Selangor peat swamp forest, Malaysia

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    Tropical peatland condition across southeast Asia is deteriorating as a result of conversion to agriculture and urban zones. Conversion begins by lowering the water table, which leads to peat decomposition, subsidence and increased risk of large-scale forest fires. Associated changes in mechanical peat properties impact the magnitude and timing of changes in peatland surface motion, making them a potential proxy for peatland condition. However, such a relationship is yet to be observed in a tropical peatland setting. This study aimed to establish whether patterns of tropical peatland surface motion were a function of peat condition at North Selangor Peat Swamp Forest in Selangor, Malaysia. Results showed that subsidence was greatest at fire-affected scrubland sites, whilst the lowest mean water table levels were found at smallholder oil palm sites. Peat condition and magnitude of tropical peat surface oscillation were significantly different between peat condition classes, whilst peat condition differed with depth. More degraded tropical peats with high bulk density throughout the peat profile due to high surface loading and low mean water table levels showed greater surface oscillation magnitudes. The dominant peat surface oscillation mechanisms present at all sites were compression and shrinkage from changes in water table level. Mean water table level and subsidence rate were related to surface oscillation magnitude. However further work towards measuring surface and within-water table range bulk densities and surface loading is required to better understand the controls on surface oscillation magnitudes

    Aberrant DNA methylation associated with silencing BNIP3 gene expression in haematopoietic tumours

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    Hypoxia is a key factor contributing to the progression of human neoplasias and to the development of resistance to chemotherapy. BNIP3 is a proapoptotic member of the Bcl-2 protein family involved in hypoxia-induced cell death. We evaluated the expression and methylation status of BNIP3 gene to better understand the role of epigenetic alteration of its expression in haematopoietic tumours. Methylation of the region around the BNIP3 transcription start site was detected in four acute lymphocytic leukaemia, one multiple myeloma and one Burkitt lymphoma cell lines, and was closely associated with silencing the gene. That expression of BNIP3 was restored by treatment with 5-aza2′-deoxycytidine (5-aza-dC), a methyltransferase inhibitor, which confirmed the gene to be epigenetically inactivated by methylation. Notably, re-expression of BNIP3 using 5-aza2-dC also restored hypoxia-mediated cell death in methylated cell lines. Acetylation of histone H3 in the 5′ region of the gene, which was assessed using chromatin immunoprecipitation assays, correlated directly with gene expression and inversely with DNA methylation. Among primary tumours, methylation of BNIP3 was detected in five of 34 (15%) acute lymphocytic leukaemias, six of 35 (17%) acute myelogenous leukaemias and three of 14 (21%) multiple myelomas. These results suggest that aberrant DNA methylation of the 5′ CpG island and histone deacetylation play key roles in silencing BNIP3 expression in haematopoietic tumours

    Effect of hypoxia-inducible factor-1α on transcription of survivin in non-small cell lung cancer

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    <p>Abstract</p> <p>Background</p> <p>Survivin is a structurally and functionally unique member of the inhibitor of apoptosis protein (IAP) family. It plays an important role, not only in regulating mitosis but also in inhibiting apoptosis. The current literature contains few reports on the transcriptional regulation of survivin expression in lung cancer.</p> <p>Methods</p> <p>In this study, we investigated the effect of hypoxia-inducible factor-1α (HIF-1α) on the transcriptional activity of the survivin promoter in non-small cell lung cancer (NSCLC). Immunohistochemical staining was used to detect the expression of survivin and HIF-1α in the lung tissue of 120 patients with non-small cell lung cancer (NSCLC) and 40 patients with benign pulmonary disease. We also performed experiments with the lung adenocarcinoma cell line A549 cells, which were cultured under hypoxic conditions. The expression of survivin and HIF-1α was detected by real-time RT-PCR and Western blotting. In the survivin promoter the putative binding-site for HIF-1α, is -19 bp~-16 bp upstream of TSS. We performed site-directed mutagenesis of this binding site, and used luciferase reporter plasmids to determine the relative activity of the survivin promoter in A549 cells. We also studied the effect of HIF-1α on the expression of survivin by dsRNA targeting of HIF-1α mRNA.</p> <p>Results</p> <p>HIF-1α (58.33%) and survivin (81.60%) were both over-expressed in NSCLC and their expressions correlated with one another. They were also expressed in A549 cells under normal and hypoxic conditions, with a significant increase under hypoxic conditions. Site directed mutagenesis of the putative binding site for HIF-1α in the survivin promoter significantly decreased the activity of the survivin promoter in A549 cells. Inhibition of HIF-1α by RNAi decreased the expression of survivin in A549 cell lines.</p> <p>Conclusion</p> <p>Our results indicate that the binding of HIF-1α to the survivin promoter increases transcription of the survivin gene. Thus, HIF-1α is an important transcriptional regulator of survivin expression</p

    Target gene selectivity of hypoxia-inducible factor-α in renal cancer cells is conveyed by post-DNA-binding mechanisms

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    Inactivation of the von Hippel–Lindau tumour suppressor in renal cell carcinoma (RCC) leads to failure of proteolytic regulation of the α subunits of hypoxia-inducible factor (HIF), constitutive upregulation of the HIF complex, and overexpression of HIF target genes. However, recent studies have indicated that in this setting, upregulation of the closely related HIF-α isoforms, HIF-1α and HIF-2α, have contrasting effects on tumour growth, and activate distinct sets of target genes. To pursue these findings, we sought to elucidate the mechanisms underlying target gene selectivity for HIF-1α and HIF-2α. Using chromatin immunoprecipitation to probe binding to hypoxia response elements in vivo, and expression of chimaeric molecules bearing reciprocal domain exchanges between HIF-1α and HIF-2α molecules, we show that selective activation of HIF-α target gene expression is not dependent on selective DNA-binding at the target locus, but depends on non-equivalent C-terminal portions of these molecules. Our data indicate that post-DNA binding mechanisms that are dissimilar for HIF-1α and HIF-2α determine target gene selectivity in RCC cells

    HIF-1α determines the metastatic potential of gastric cancer cells

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    Gastric adenocarcinoma is characterised by rapid emergence of systemic metastases, resulting in poor prognosis due to vanished curative treatment options. Better understanding of the molecular basis of gastric cancer spread is needed to design innovative treatments. The transcription factor HIF-1α (hypoxia-inducible factor 1α) is frequently overexpressed in human gastric cancer, and inhibition of HIF-1α has proven antitumour efficacy in rodent models, whereas the relevance of HIF-1α for the metastatic phenotype of gastric adenocarcinoma remains elusive. Therefore, we have conducted a comprehensive analysis of the role of HIF-1α for pivotal metastasis-associated processes of human gastric cancer. Immunhistochemistry for HIF-1α showed specific staining at the invading tumour edge in 90% of human gastric cancer samples, whereas normal gastric tissue was negative and only a minority of early gastric cancers (T1 tumours) showed specific staining. Hypoxia-inducible factor 1α-deficient cells showed a significant reduction of migratory, invasive and adhesive properties in vitro. Furthermore, the HIF-1α-inhibitor 2-methoxy-estradiol significantly reduced metastatic properties of gastric cancer cells. The accentuated expression at the invading edge together with the in vitro requirement of HIF-1α for migration, invasion and adherence argues for a pivotal role of HIF-1α in local invasion and, ultimately, systemic tumour spread. These results warrant the exploration of HIF-1α-inhibiting substances in clinical treatment studies of advanced gastric cancer
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