169 research outputs found

    Combining Historical Records and Geospatial Techniques to Analyze Land Use Modification in a Tallgrass Prairie Landscape

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    The land use practices that accompanied settlement across central North America changed the structure and function of the North American tallgrass prairie landscape. Tallgrass prairie vegetation has experienced the largest areal reduction compared to other North American vegetation types. Euro-American settlement over the past 150 years is reported in historical records providing the data to study land use modification in the tallgrass prairie. The decline or loss of tallgrass prairie habitat was also accompanied by habitat fragmentation, a change in the spatial configuration of the original landscape. Land use practices that lead to the loss and fragmentation of tallgrass prairie include conversion to monoculture row crop production, introduction of non-native forage crops, woody plant encroachment, overgrazing, and urban expansion.This dissertation research used qualitative and quantitative methods to understand how modification in land use from the pre-settlement period to 2008 has altered the tallgrass prairie. In the first chapter I conducted a review of historical agriculture reports to determine when and why the non-native grass tall fescue (Schedonorus phoenix) was introduced into Oklahoma tallgrass prairies. I found that the two primary reasons for introduction were for prevention of soil erosion and to increase forage production, therefore increasing farm profits. In chapter two I used historical spatial data obtained from the General Land Office to determine land use practices that initially altered the tallgrass prairie landscape following settlement. I used spatial data and historic records to reconstruct the tallgrass prairie landscape in northeastern Oklahoma at the time of the Public Land Survey. I determined that the main drivers for loss and fragmentation of the tallgrass prairie vegetation was initiated by opening Indian Territory to railroads and settlers, the invention and widespread use of barbed wire fencing, which allowed for enclosure of, and an increase in cultivated fields, and the allotment of native lands. The third chapter quantified the areal loss and fragmentation of the tallgrass prairie vegetation by comparing tallgrass prairie land cover from pre-settlement, to 1896, to 2008. Landscape metrics were calculated to measure the degree of fragmentation. I found that 85% of the original tallgrass prairie landscape had been lost through land use changes. The tallgrass prairie that remained on the landscape was remnant patches maintained as either rangeland or hay meadows. Hay meadows represent traditional landscapes maintained to produce native prairie hay. These traditional landscapes harbor high species diversity and require little input of labor, fuel or chemicals to maintain them, compared to non-native monoculture pastures. This dissertation project studied land use changes by applying concepts and methods from the fields of geographic information science, biogeography, historical ecology, landscape ecology and conservation biology. The knowledge gained from this dissertation research can be used for the conservation and/or restoration of landscapes fragmented from land use modification

    Differentiation-dependent Requirement of Tsix long non-coding RNA in Imprinted X-chromosome Inactivation

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    Imprinted X-inactivation is a paradigm of mammalian transgenerational epigenetic regulation resulting in silencing of genes on the paternally-inherited X-chromosome. The pre-programmed fate of the X-chromosomes is thought to be controlled in cis by the parent-of-origin-specific expression of two long non-coding RNAs, Tsix and Xist, in mice. Exclusive expression of Tsix from the maternal–X has implicated it as the instrument through which the maternal germline prevents inactivation of the maternal–X in the offspring. Here, we show that Tsix is dispensable for inhibiting Xist and X-inactivation in the early embryo and in cultured stem cells of extra-embryonic lineages. Tsix is instead required to prevent Xist expression as trophectodermal progenitor cells differentiate. Despite induction of wild-type Xist RNA and accumulation of histone H3-K27me3, many Tsix-mutant X-chromosomes fail to undergo ectopic X-inactivation. We propose a novel model of lncRNA function in imprinted X-inactivation that may also apply to other genomically imprinted loci

    PRC2 represses transcribed genes on the imprinted inactive X chromosome in mice

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    Abstract Background Polycomb repressive complex 2 (PRC2) catalyzes histone H3K27me3, which marks many transcriptionally silent genes throughout the mammalian genome. Although H3K27me3 is associated with silenced gene expression broadly, it remains unclear why some but not other PRC2 target genes require PRC2 and H3K27me3 for silencing. Results Here we define the transcriptional and chromatin features that predict which PRC2 target genes require PRC2/H3K27me3 for silencing by interrogating imprinted mouse X-chromosome inactivation. H3K27me3 is enriched at promoters of silenced genes across the inactive X chromosome. To abrogate PRC2 function, we delete the core PRC2 protein EED in F1 hybrid trophoblast stem cells (TSCs), which undergo imprinted inactivation of the paternally inherited X chromosome. Eed –/– TSCs lack H3K27me3 and Xist lncRNA enrichment on the inactive X chromosome. Despite the absence of H3K27me3 and Xist RNA, only a subset of the inactivated X-linked genes is derepressed in Eed –/– TSCs. Unexpectedly, in wild-type (WT) TSCs these genes are transcribed and are enriched for active chromatin hallmarks on the inactive-X, including RNA PolII, H3K27ac, and H3K36me3, but not the bivalent mark H3K4me2. By contrast, PRC2 targets that remain repressed in Eed –/– TSCs are depleted for active chromatin characteristics in WT TSCs. Conclusions A comparative analysis of transcriptional and chromatin features of inactive X-linked genes in WT and Eed –/– TSCs suggests that PRC2 acts as a brake to prevent induction of transcribed genes on the inactive X chromosome, a mode of PRC2 function that may apply broadly.https://deepblue.lib.umich.edu/bitstream/2027.42/136651/1/13059_2017_Article_1211.pd

    Molecular imaging in multiple myeloma — novel PET radiotracers improve patient management and guide therapy

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    Due to its proven value in imaging of multiple myeloma (MM), including staging, prognostication, and assessment of therapy response, 2-deoxy-2-[18F]fluoro-D-glucose (FDG) positron emission tomography (PET) is utilized extensively in the clinic. However, its accuracy is hampered by imperfect sensitivity (e.g., so-called FDG-negative MM) as well as specificity (e.g., inflammatory processes), with common pitfalls including fractures and degenerative changes. Novel approaches providing a read-out of increased protein or lipid membrane syntheses, such as [11C]methionine and [11C]choline or the C-X-C motif chemokine receptor 4-targeting radiotracer [68Ga]Pentixafor, have already been shown to be suitable adjuncts or alternatives to FDG. In the present focused review, those imaging agents along with their theranostic potential in the context of MM are highlighted

    In-vivo somatostatin-receptor expression in small cell lung cancer as a prognostic image biomarker and therapeutic target

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    Background: Given the dismal prognosis of small cell lung cancer (SCLC), novel therapeutic targets are urgently needed. We aimed to evaluate whether SSTR expression, as assessed by positron emission tomography (PET), can be applied as a prognostic image biomarker and determined subjects eligible for peptide receptor radionuclide therapy (PRRT). Methods: A total of 67 patients (26 females; age, 41–80 years) with advanced SCLC underwent SSTR-directed PET/computed tomography (somatostatin receptor imaging, SRI). SRI-avid tumor burden was quantified by maximum standardized uptake values (SUVmax) and tumor-to-liver ratios (T/L) of the most intense SCLC lesion. Scan findings were correlated with progression-free (PFS) and overall survival (OS). In addition, subjects eligible for SSTR-directed radioligand therapy were identified, and treatment outcome and toxicity profile were recorded. Results: On a patient basis, 36/67 (53.7%) subjects presented with mainly SSTR-positive SCLC lesions (>50% lesions positive); in 10/67 patients (14.9%), all lesions were positive. The median SUVmax was found to be 8.5, while the median T/L was 1.12. SRI-uptake was not associated with PFS or OS, respectively (SUVmax vs. PFS, ρ = 0.13 with p = 0.30 and vs. OS, ρ = 0.00 with p = 0.97; T/L vs. PFS, ρ = 0.07 with p = 0.58 and vs. OS, ρ = −0.05 with p = 0.70). PRRT was performed in 14 patients. One patient succumbed to treatment-independent infectious complications immediately after PRRT. In the remaining 13 subjects, disease control was achieved in 5/13 (38.5%) with a single patient achieving a partial response (stable disease in the remainder). In the sub-group of responding patients, PFS and OS were 357 days and 480 days, respectively. Conclusions: SSTR expression as detected by SRI is not predictive of outcome in patients with advanced SCLC. However, it might serve as a therapeutic target in selected patient

    Data Throughput of Wireless Network for Fire Alarms

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    Import 22/07/2015Tato bakalářská práce se zabývá ostravskou hasičskou sítí, propustností, rušením a návrhem na vylepšení sítě z hlediska datové propustnosti. Analýza datové propustnosti byla provedena pomoci vlastního programu napsaného v C#. Pomocí USB tuneru Rafael Micro R820T s čipsetem RTL2832U a počítačem s operačním systémem Ubuntu 14.04, na kterém byly nainstalován software Librtlsdr, GNU radio GQRX , Teamviewer a Kazam. Těmito programy byly sledovány vstupní kmitočty převaděčů, které neodhalily žádné rušení. Dále byly vypsány možné vlivy teoretického rušení. Následně byly vymyšleny dvě teoreticky zlepšené varianty systému. První se zabývá obousměrným přenosem, kdy koncové vysílače přijímají zprávu o potvrzení přijetí z převaděče a druhá přidáním dalšího převaděče, který by se při správném umístění, které by bylo na výškové budově domova sester. Hlavní výhodou tohoto řešení je větší pokrytí oblasti. Oba tyto návrhy mají lepší vlastnosti v oblasti datové propustnosti.The bachelor thesis deals with the fire-fighting net in Ostrava, it's permeability, disturbance and improvement proposal for this net from the point of view of data permeability. Analysis of data permeability was made by own programme wrote in C#. Disturbance was watched by USB tuner Rafael Micro R820T with chipset RTL2832U and with computer with operating system Ubuntu 14.04. On Ubuntu was install a software Librtlsdr, GNU radio GQRX, Teamviewer and Kazam. But the disturbance was not found. The list of the theroretical influences on disturbance was made. Two theoretical better options were invented. The first one deals with two-way transfer and the second one proposes additional convertor. These suggestions have better properties in the field of data permeability.440 - Katedra telekomunikační technikydobř

    Widespread West Nile virus activity, eastern United States, 2000.

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    In 1999, the U.S. West Nile (WN) virus epidemic was preceded by widespread reports of avian deaths. In 2000, ArboNET, a cooperative WN virus surveillance system, was implemented to monitor the sentinel epizootic that precedes human infection. This report summarizes 2000 surveillance data, documents widespread virus activity in 2000, and demonstrates the utility of monitoring virus activity in animals to identify human risk for infection

    Human papillomavirus type 18 infection in a female renal allograft recipient : a case report

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    Publisher Copyright: © 2016 The Author(s).Background: Human papillomavirus type 18 is the second most common cause of cervical cancer and is found in 7 to 20 % of cases of cervical cancer. The oncogenic potential of high-risk human papillomavirus is associated with expression of early proteins E6 and E7. Due to long-term immunosuppressive therapy, renal transplant recipients have a higher risk of developing persistent human papillomavirus infection. Case presentation: A 29-year-old white woman from Latvia with chronic focal segmental glomerulosclerosis received renal allograft transplantation and was prescribed immunosuppressive therapy with cyclosporine, prednisolone, and mycophenolate mofetil. Two weeks after renal transplantation, her cervical swab was positive for human papillomavirus consensus sequences. After 6 months, quantitative polymerase chain reaction showed a high viral load of 3,630,789 copies/105 cells of high-risk human papillomavirus type 18 and expression of E6 and E7 oncogenes in her cervical swab and urine sample. One year after renal transplantation, the viral load in her cervical swab increased significantly to 7,413,102 copies/105 cells. Messenger ribonucleic acid of human papillomavirus type 18 E6 and E7 oncogenes were also detected. Shortly after this, she had an unsuccessful pregnancy which resulted in a spontaneous abortion at 6/7 weeks. Two months after the abortion her viral load sharply decreased to 39 copies/105 cells. Oncogenes E6 and E7 messenger ribonucleic acid expression was not observed in this period. Conclusions: This case report represents data which show that immunosuppressive therapy may increase the risk of developing persistent high-risk human papillomavirus infection with expression of E6 and E7 oncogenes in renal transplant recipients. However, even during this therapy the immune status of a recipient can improve and contribute to human papillomavirus viral load reduction. Spontaneous abortion can be considered a possible contributory factor in human papillomavirus clearance.publishersversionPeer reviewe

    Molecular epidemiology of Powassan virus in North America

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    Powassan virus (POW) is a tick-borne flavivirus distributed in Canada, the northern USA and the Primorsky region of Russia. POW is the only tick-borne flavivirus endemic to the western hemisphere, where it is transmitted mainly between Ixodes cookei and groundhogs (Marmota monax). Deer tick virus (DTV), a genotype of POW that has been frequently isolated from deer ticks (Ixodes scapularis), appears to be maintained in an enzootic cycle between these ticks and white-footed mice (Peromyscus leucopus). DTV has been isolated from ticks in several regions of North America, including the upper Midwest and the eastern seaboard. The incidence of human disease due to POW is apparently increasing. Previous analysis of tick-borne flaviviruses endemic to North America have been limited to relatively short genome fragments. We therefore assessed the evolutionary dynamics of POW using newly generated complete and partial genome sequences. Maximum-likelihood and Bayesian phylogenetic inferences showed two well-supported, reciprocally monophyletic lineages corresponding to POW and DTV. Bayesian skyline plots based on year-of-sampling data indicated no significant population size change for either virus lineage. Statistical model-based selection analyses showed evidence of purifying selection in both lineages. Positive selection was detected in NS-5 sequences for both lineages and envelope sequences for POW. Our findings confirm that POW and DTV sequences are relatively stable over time, which suggests strong evolutionary constraint, and support field observations that suggest that tick-borne flavivirus populations are extremely stable in enzootic foci
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