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Microbial Community Stratification Linked to Utilization of Carbohydrates and Phosphorus Limitation in a Boreal Peatland at Marcell Experimental Forest, Minnesota, USA

Lin, Xueju; Tfaily, Malak M.; Steinweg, J. Megan; Chanton, Patrick; Esson, Kaitlin; Yang, Zamin K.; Chanton, Jeffrey P.; Cooper, William; Schadt, Christopher W.; Kostka, Joel E.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /06/2014 Português
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This study investigated the abundance, distribution, and composition of microbial communities at the watershed scale in a boreal peatland within the Marcell Experimental Forest (MEF), Minnesota, USA. Through a close coupling of next-generation sequencing, biogeochemistry, and advanced analytical chemistry, a biogeochemical hot spot was revealed in the mesotelm (30- to 50-cm depth) as a pronounced shift in microbial community composition in parallel with elevated peat decomposition. The relative abundance of Acidobacteria and the Syntrophobacteraceae, including known hydrocarbon-utilizing genera, was positively correlated with carbohydrate and organic acid content, showing a maximum in the mesotelm. The abundance of Archaea (primarily crenarchaeal groups 1.1c and 1.3) increased with depth, reaching up to 60% of total small-subunit (SSU) rRNA gene sequences in the deep peat below the 75-cm depth. Stable isotope geochemistry and potential rates of methane production paralleled vertical changes in methanogen community composition to indicate a predominance of acetoclastic methanogenesis mediated by the Methanosarcinales in the mesotelm, while hydrogen-utilizing methanogens predominated in the deeper catotelm. RNA-derived pyrosequence libraries corroborated DNA sequence data to indicate that the above-mentioned microbial groups are metabolically active in the mid-depth zone. Fungi showed a maximum in rRNA gene abundance above the 30-cm depth...

Microbial Metabolic Potential for Carbon Degradation and Nutrient (Nitrogen and Phosphorus) Acquisition in an Ombrotrophic Peatland

Lin, Xueju; Tfaily, Malak M.; Green, Stefan J.; Steinweg, J. Megan; Chanton, Patrick; Imvittaya, Aopeau; Chanton, Jeffrey P.; Cooper, William; Schadt, Christopher; Kostka, Joel E.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /06/2014 Português
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This study integrated metagenomic and nuclear magnetic resonance (NMR) spectroscopic approaches to investigate microbial metabolic potential for organic matter decomposition and nitrogen (N) and phosphorus (P) acquisition in soils of an ombrotrophic peatland in the Marcell Experimental Forest (MEF), Minnesota, USA. This analysis revealed vertical stratification in key enzymatic pathways and taxa containing these pathways. Metagenomic analyses revealed that genes encoding laccases and dioxygenases, involved in aromatic compound degradation, declined in relative abundance with depth, while the relative abundance of genes encoding metabolism of amino sugars and all four saccharide groups increased with depth in parallel with a 50% reduction in carbohydrate content. Most Cu-oxidases were closely related to genes from Proteobacteria and Acidobacteria, and type 4 laccase-like Cu-oxidase genes were >8 times more abundant than type 3 genes, suggesting an important and overlooked role for type 4 Cu-oxidase in phenolic compound degradation. Genes associated with sulfate reduction and methanogenesis were the most abundant anaerobic respiration genes in these systems, with low levels of detection observed for genes of denitrification and Fe(III) reduction. Fermentation genes increased in relative abundance with depth and were largely affiliated with Syntrophobacter. Methylocystaceae-like small-subunit (SSU) rRNA genes...

Metformin Exhibits Radiation Countermeasures Efficacy When Used Alone or in Combination with Sulfhydryl Containing Drugs

Miller, Richard C.; Murley, Jeffrey S.; Grdina, David J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Metformin, a biguanide drug used in the treatment of type II diabetes, was evaluated alone and in combination with amifostine, captopril, MESNA or N-acetyl-cysteine (NAC) for its ability to protect when administered 24 h after irradiation. Mouse embryo fibroblasts (MEF), human microvascular endothelial cells (HMEC) and SA-NH mouse sarcoma cells were exposed to 4 Gy in vitro. C3H mice were exposed to 7 Gy and evaluated utilizing an endogenous spleen colony assay system. Amifostine and WR1065, administered 30 min prior to irradiation, were used as positive controls. Treatment of MEF, HMEC and SA-NH cells with metformin elevated survival levels by 1.4-, 1.5- and 1.3-fold compared to 1.9-, 1.8- and 1.6-fold for these same cells treated with WR1065, respectively. Metformin (250 mg/kg) was effective in protecting splenic cells from a 7 Gy dose in vivo (protection factor = 1.8). Amifostine (400 mg/kg), administered 30 min prior to irradiation resulted in a 2.6-fold survival elevation, while metformin administered 24 h after irradiation in combination with NAC (400 mg/kg), MESNA (300 mg/kg) or captopril (200 mg/kg) enhanced survival by 2.6-, 2.8- and 2.4-fold, respectively. Each of these agents has been approved by the FDA for human use and each has a well characterized human safety profile. Metformin alone or in combination with selected sulfhydryl agents possesses radioprotective properties when administered 24 h after radiation exposure comparable to that observed for amifostine administered 30 min prior to irradiation making it a potentially useful agent for radiation countermeasures use.

p38 MAPK signaling regulates recruitment of Ash2L-containing methyltransferase complexes to specific genes during differentiation

Rampalli, Shravanti; Li, LiFang; Mak, Esther; Ge, Kai; Brand, Marjorie; Tapscott, Stephen J; Dilworth, F Jeffrey
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Cell-specific patterns of gene expression are established through the antagonistic functions of trithorax group (TrxG) and Polycomb group (PcG) proteins. Several muscle-specific genes have previously been shown to be epigenetically marked for repression by PcG proteins in muscle progenitor cells. Here we demonstrate that these developmentally regulated genes become epigenetically marked for gene expression (trimethylated on histone H3 Lys4, H3K4me3) during muscle differentiation through specific recruitment of Ash2L-containing methyltransferase complexes. Targeting of Ash2L to specific genes is mediated by the transcriptional regulator Mef 2d. Furthermore, this interaction is modulated during differentiation through activation of the p38 MAPK signaling pathway via phosphorylation of Mef 2d. Thus, we provide evidence that signaling pathways regulate the targeting of TrxG-mediated epigenetic modifications at specific promoters during cellular differentiation.

Analysis of FK506, timcodar (VX-853) and FKBP51 and FKBP52 chaperones in control of glucocorticoid receptor activity and phosphorylation

Hinds, Terry D; Stechschulte, Lance A; Elkhairi, Fadel; Sanchez, Edwin R
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
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The immunosuppressive ligand FK506 and the FK506-binding protein FKBP52 are stimulatory to glucocorticoid receptor (GR) activity. Here, we explore the underlying mechanism by comparing GR activity and phosphorylation status in response to FK506 and the novel nonimmunosuppressive ligand timcodar (VX-853) and in the presence and absence of FKBP52 and the closely related protein FKBP51. Using mouse embryonic fibroblast cells (MEFs) deficient knockout (KO) in FKBP51 or FKBP52, we show decreased GR activity at endogenous genes in 52KO cells, but increased activity in 51KO cells. In 52KO cells, elevated phosphorylation occurred at inhibitory serine 212 and decreased phosphorylation at the stimulatory S220 residue. In contrast, 51KO cells showed increased GR phosphorylation at the stimulatory residues S220 and S234. In wild-type (WT) MEF cells, timcodar, like FK506, potentiated dexamethasone-induced GR transcriptional activity at two endogenous genes. Using 52KO and 51KO MEF cells, FK506 potentiated GR activity in 51KO cells but could not do so in 52KO cells, suggesting FKBP52 as the major target of FK506 action. Like FK506, timcodar potentiated GR in 51KO cells, but it also increased GR activity in 52KO cells. Knock-down of FKBP51 in the 52KO cells showed that the latter effect of timcodar required FKBP51. Thus...

A new tumour suppression mechanism by p27Kip1: EGFR down-regulation mediated by JNK/c-Jun pathway inhibition

Fang, Yong; Wang, Yihong; Wang, Yulei; Meng, Yan; Zhu, Junlan; Jin, Honglei; Li, Jingxia; Zhang, Dongyun; Yu, Yonghui; Wu, Xue-Ru; Huang, Chuanshu
Fonte: Portland Press Ltd. Publicador: Portland Press Ltd.
Tipo: Artigo de Revista Científica
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p27Kip1 is a potent inhibitor of cyclin-dependent kinases that drive G1-to-S cell-cycle transition. Reduced p27Kip1 expression is prevalent in a wide range of human tumours; however, the exact mechanism(s) of p27Kip1-mediated tumour suppression remains obscure. In the present study, we identified a close inverse relationship between p27Kip1 and EGFR (epidermal growth factor receptor) expression: the parental T24 human bladder cancer cells had high p27Kip1 expression but low EGFR expression and, in striking contrast, the metastatic derivative of T24 (T24T) had low p27Kip1 expression but high EGFR expression. This relationship was also found in various human cancer tissues, and was not only just correlative but also causal; depletion of p27Kip1 in MEF (mouse embryonic fibroblast) cells resulted in markedly elevated EGFR expression, a result reproducible with an Egfr promoter-luciferase reporter in both T24 and MEF cells, suggesting transcriptional repression of EGFR by p27Kip1. Indeed, p27Kip1 was found to regulate EGFR expression via the JNK (c-Jun N-terminal kinase)/c-Jun transcription factor: p27Kip1 deficiency activated JNK/c-Jun, whereas inhibition of JNK/c-Jun by dominant-negative mutants dramatically repressed Egfr transcription. Furthermore...

Cytotoxic and apoptotic activities of Amorphophallus campanulatus (Roxb.) Bl. tuber extracts against human colon carcinoma cell line HCT-15

Ansil, P.N.; Wills, P.J.; Varun, R.; Latha, M.S.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Colorectal cancer is one of the leading causes of cancer death worldwide and is the third most common form of malignancy in both men and women. Several possible colon cancer chemopreventive agents are found in edible plants. Amorphophallus campanulatus (Roxb.) Blume (family: Araceae) is a tuber crop, largely cultivated throughout the plains of India for using its corm as food. This tuber has also been traditionally used for the treatment of abdominal tumors, liver diseases, piles etc. The aim of this study was to evaluate the dose-dependent cytotoxic and apoptosis inducing effects of the sub fractions of A. campanulatus tuber methanolic extract (ACME) viz. petroleum ether fraction (PEF), chloroform fraction (CHF), ethyl acetate fraction (EAF) and methanolic fraction (MEF) on the colon cancer cell line, HCT-15. Antiproliferative effects of the sub fractions of ACME were studied by MTT assay. Apoptotic activity was assessed by DAPI, Annexin V-FITC and JC-1 fluorescent staining. The chemotherapeutic drug, 5-flurouracil (5-FU) was used as positive drug control. The sub fractions of ACME significantly inhibited the proliferation of HCT-15 cells in a dose-dependent manner. In addition, the extracts were found to induce apoptosis and were confirmed by DAPI...

Targeting the integrated networks of aggresome formation, proteasome, and autophagy potentiates ER stress-mediated cell death in multiple myeloma cells

MORIYA, SHOTA; KOMATSU, SEIICHIRO; YAMASAKI, KAHO; KAWAI, YUSUKE; KOKUBA, HIROKO; HIROTA, AYAKO; CHE, XIAO-FANG; INAZU, MASATO; GOTOH, AKIHIKO; HIRAMOTO, MASAKI; MIYAZAWA, KEISUKE
Fonte: D.A. Spandidos Publicador: D.A. Spandidos
Tipo: Artigo de Revista Científica
Publicado em 24/11/2014 Português
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The inhibitory effects of macrolide antibiotics including clarithromycin (CAM) on autophagy flux have been reported. Although a macrolide antibiotic exhibits no cytotoxicity, its combination with bortezomib (BZ), a proteasome inhibitor, for the simultaneous blocking of the ubiquitin (Ub)-proteasome and autophagy-lysosome pathways leads to enhanced multiple myeloma (MM) cell apoptosis induction via stress overloading of the endoplasmic reticulum (ER). As misfolded protein cargo is recruited by histone deacetylase 6 (HDAC6) to dynein motors for aggresome transport, serving to sequester misfolded proteins, we further investigated the cellular effects of targeting proteolytic pathways and aggresome formation concomitantly in MM cells. Pronounced apoptosis was induced by the combination of vorinostat [suberoylanilide hydroxamic acid (SAHA); potently inhibits HDAC6] with CAM and BZ compared with each reagent or a 2-reagent combination. CAM/BZ treatment induced vimentin positive-aggresome formation along with the accumulation of autolysosomes in the perinuclear region, whereas they were inhibited in the presence of SAHA. The SAHA/CAM/BZ combination treatment maximally upregulated genes related to ER stress including C/EBP homologous protein (CHOP). Similarly to MM cell lines...

Pluripotent State Induction in Mouse Embryonic Fibroblast Using mRNAs of Reprogramming Factors

El-Sayed, Ahmed Kamel; Zhang, Zhentao; Zhang, Lei; Liu, Zhiyong; Abbott, Louise C.; Zhang, Yani; Li, Bichun
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 27/11/2014 Português
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Reprogramming of somatic cells has great potential to provide therapeutic treatments for a number of diseases as well as provide insight into mechanisms underlying early embryonic development. Improvement of induced Pluripotent Stem Cells (iPSCs) generation through mRNA-based methods is currently an area of intense research. This approach provides a number of advantages over previously used methods such as DNA integration and insertional mutagenesis. Using transfection of specifically synthesized mRNAs of various pluripotency factors, we generated iPSCs from mouse embryonic fibroblast (MEF) cells. The genetic, epigenetic and functional properties of the iPSCs were evaluated at different times during the reprogramming process. We successfully introduced synthesized mRNAs, which localized correctly inside the cells and exhibited efficient and stable translation into proteins. Our work demonstrated a robust up-regulation and a gradual promoter de-methylation of the pluripotency markers, including non-transfected factors such as Nanog, SSEA-1 (stage-specific embryonic antigen 1) and Rex-1 (ZFP-42, zinc finger protein 42). Using embryonic stem cells (ESCs) conditions to culture the iPS cells resulted in formation of ES-like colonies after approximately 12 days with only five daily repeated transfections. The colonies were positive for alkaline phosphatase and pluripotency-specific markers associated with ESCs. This study revealed the ability of pluripotency induction and generation of mouse mRNA induced pluripotent stem cells (mRNA iPSCs) using transfection of specifically synthesized mRNAs of various pluripotency factors into mouse embryonic fibroblast (MEF) cells. These generated iPSCs exhibited molecular and functional properties similar to ESCs...

Cytotoxic and apoptotic activities of Amorphophallus campanulatus tuber extracts against human hepatoma cell line

Ansil, P.N.; Wills, P.J.; Varun, R.; Latha, M.S.
Fonte: Medknow Publications & Media Pvt Ltd Publicador: Medknow Publications & Media Pvt Ltd
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
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Amorphophallus campanulatus (Roxb.) Blume belonging to the family of Araceae, is a perennial herb commonly known as elephant foot yam. Its tuber has been traditionally used for the treatment of liver diseases, abdominal tumors, piles. The aim of the present study was to evaluate the dose-dependent cytotoxic and apoptosis inducing effects of the sub fractions of Amorphophallus campanulatus tuber methanolic extract (ACME) namely petroleum ether fraction (PEF), chloroform fraction (CHF), ethyl acetate fraction (EAF) and methanolic fraction (MeF) on human liver cancer cell line, PLC/PRF/5. Antiproliferative effects of the sub fractions of ACME were studied by MTT assay. Apoptotic activity was assessed by 4′,6-diamidino-2-phenylindole (DAPI), annexin V- fluorescein isothiocyanate (FITC) and 5,5’,6,6’ tetrachloro-1,1’,3,3’-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) fluorescent staining. The chemotherapeutic drug, 5-flurouracil (5-FU) was used as positive drug control. The sub fractions of ACME were found to produce considerable cytotoxicity in human liver cancer cell line, PLC/PRF/5. In addition, the extracts were found to induce apoptosis and were substantiated by DAPI, annexin V-FITC and JC-1 fluorescent staining. A pronounced results of cytotoxic and apoptotic activities were observed in the cells treated with 5-FU and CHF...

Putative Porcine Embryonic Stem Cell Lines Derived from Aggregated Four-Celled Cloned Embryos Produced by Oocyte Bisection Cloning

Siriboon, Chawalit; Lin, Yu-Hsuan; Kere, Michel; Chen, Chun-Da; Chen, Lih-Ren; Chen, Chien-Hong; Tu, Ching-Fu; Lo, Neng-Wen; Ju, Jyh-Cherng
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 13/02/2015 Português
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We attempted to isolate ES cell lines using inner cell masses from high-quality cloned porcine blastocysts. After being seeded onto feeders, embryos had better (P < 0.05) attachment, outgrowth formation and primary colonization in both 2× and 3× aggregated cloned embryos (62.8, 42.6 and12.8% vs. 76.2, 55.2 and 26.2%, respectively) compared to the non-aggregated group (41.6, 23.4 and 3.9%). Effects of feeder types (STO vs. MEF) and serum sources (FBS vs. KSR) on extraction of cloned embryo-derived porcine ES cells were examined. More (17.1%) ntES cell lines over Passage 3 were generated in the MEF/KSR group. However, ntES cells cultured in KSR-supplemented medium had a low proliferation rate with defective morphology, and eventually underwent differentiation or apoptosis subsequently. Approximately 26.1, 22.7 and 35.7% of primary colonies were formed after plating embryos in DMEM, DMEM/F12 and α-MEM media, respectively. Survival rates of ntES cells cultured in α-MEM, DMEM and DMEM/F12 were 16.7, 4.3 and 6.8%, respectively (P > 0.05). We further examined the beneficial effect of TSA treatment of 3× aggregated cloned embryos on establishment of ntES cell lines. Primary colony numbers and survival rates of ntES cells beyond passage 3 were higher (P < 0.05) in those derived from TSA-treated 3× blastocysts (36.7 and 26.7%) than from the non-treated aggregated group (23.1 and 11.5%). These cells...

Alcohol modulates expression of DNA methyltranferases and methyl CpG-/CpG domain-binding proteins in murine embryonic fibroblasts

Mukhopadhyay, Partha; Rezzoug, Francine; Kaikaus, Jahanzeb; Greene, Robert M.; Pisano, M. Michele
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Fetal alcohol syndrome (FAS), presenting with a constellation of neuro-/psychological, craniofacial and cardiac abnormalities, occurs frequently in offspring of women who consume alcohol during pregnancy, with a prevalence of 1–3 per 1000 livebirths. The present study was designed to test the hypothesis that alcohol alters global DNA methylation, and modulates expression of the DNA methyltransferases (DNMTs) and various methyl CpG-binding proteins. Murine embryonic fibroblasts (MEFs), utilized as an in vitro embryonic model system, demonstrated ~5% reduction in global DNA methylation following exposure to 200 mM ethanol. In addition, ethanol induced degradation of DNA methyltransferases (DNMT-1, DNMT-3a, and DNMT-3b), as well as the methyl CpG-binding proteins (MeCP-2, MBD-2 and MBD-3), in MEF cells by the proteasomal pathway. Such degradation could be completely rescued by pretreatment of MEF cells with the proteasomal inhibitor, MG-132. These data support a potential epigenetic molecular mechanism underlying the pathogenesis of FAS during mammalian development.

miR-20a and miR-290, multi-faceted players with a role in tumourigenesis and senescence

Rizzo, Milena; Mariani, Laura; Pitto, Letizia; Rainaldi, Giuseppe; Simili, Marcella
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
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Expression of microRNAs changes markedly in tumours and evidence indicates that they are causatively related to tumourigenesis, behaving as tumour suppressor microRNAs or onco microRNAs; in some cases they can behave as both depending on the type of cancer. Some tumour suppressor microRNAs appear to be an integral part of the p53 and Retinoblastoma (RB) network, the main regulatory pathways controlling senescence, a major tumour suppressor mechanism. The INK4a/ARF locus which codifies for two proteins, p19ARF and p16INK4a, plays a central role in senescence by controlling both p53 and RB. Recent evidence shows that the proto-oncogene leukaemia/lymphoma related factor, a p19ARF specific repressor, is controlled by miRNAs and that miRNAs, in particular miR-20a and miR-290, are causatively involved in mouse embryo fibroblasts (MEF) senescence in culture. Intriguingly, both miR-20a, member of the oncogenic miR-17–92 cluster, and miR-290, belonging to the miR-290–295 cluster, are highly expressed in embryonic stem (ES) cells. The pro-senescence role of miR-20a and miR-290 in MEF is apparently in contrast with their proliferative role in tumour and ES cells. We propose that miRNAs may exert opposing functions depending on the miRNAs repertoire as well as target/s level/s present in different cellular contexts...

Role of isolated and clustered DNA damage and the post-irradiating repair process in the effects of heavy ion beam irradiation

Tokuyama, Yuka; Furusawa, Yoshiya; Ide, Hiroshi; Yasui, Akira; Terato, Hiroaki
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
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Clustered DNA damage is a specific type of DNA damage induced by ionizing radiation. Any type of ionizing radiation traverses the target DNA molecule as a beam, inducing damage along its track. Our previous study showed that clustered DNA damage yields decreased with increased linear energy transfer (LET), leading us to investigate the importance of clustered DNA damage in the biological effects of heavy ion beam radiation. In this study, we analyzed the yield of clustered base damage (comprising multiple base lesions) in cultured cells irradiated with various heavy ion beams, and investigated isolated base damage and the repair process in post-irradiation cultured cells. Chinese hamster ovary (CHO) cells were irradiated by carbon, silicon, argon and iron ion beams with LETs of 13, 55, 90 and 200 keV µm−1, respectively. Agarose gel electrophoresis of the cells with enzymatic treatments indicated that clustered base damage yields decreased as the LET increased. The aldehyde reactive probe procedure showed that isolated base damage yields in the irradiated cells followed the same pattern. To analyze the cellular base damage process, clustered DNA damage repair was investigated using DNA repair mutant cells. DNA double-strand breaks accumulated in CHO mutant cells lacking Xrcc1 after irradiation...

Ocular Fluid As a Replacement for Serum in Cell Cryopreservation Media

Varma, Vivek Phani; Devi, Lalitha; Venna, Naresh Kumar; Murthy, Ch Lakshmi N.; Idris, Mohammed M.; Goel, Sandeep
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 02/07/2015 Português
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Cryostorage is of immense interest in biomedical research, especially for stem cell-based therapies and fertility preservation. Several protocols have been developed for efficient cryopreservation of cells and tissues, and a combination of dimethyl sulfoxide (DMSO) and fetal bovine serum (FBS) is commonly used. However, there is a need for an alternative to FBS because of ethical reasons, high cost, and risk of contamination with blood-borne diseases. The objective of the present study was to examine the possibility of using buffalo (Bubalus bubalis) ocular fluid (BuOF) to replace FBS in cryomedia. Frozen–thawed cells, which were cryopreserved in a cryomedia with BuOF, were assessed for viability, early and late apoptosis, and proliferation. Three cell lines (CHO, HEK, and C18-4), mouse embryonic stem (mES) cells, and primary cells, such as mouse embryonic fibroblast (MEF) cells, human peripheral blood mononuclear cells (hPBMCs), and mouse bone marrow cells (mBMCs), were cryopreserved in cryomedia containing 10% DMSO (D10) with 20% FBS (D10S20) or D10 with 20% BuOF (D10O20). For all three cell lines and mES cells cryopreserved in either D10S20 or D10O20, thawed cells showed no difference in cell viability or cell recovery. Western blot analysis of frozen–thawed-cultured cells revealed that the expression of Annexin V and proliferating cell nuclear antigen (PCNA) proteins...

Comprehensive Dissection of PDGF-PDGFR Signaling Pathways in PDGFR Genetically Defined Cells

Wu, Erxi; Palmer, Nathan; Moseman, Annie P.; Galdzicki, Michal; Wang, Xuetao; Berger, Bonnie; Zhang, Hongbing; Tian, Ze; Kohane, Isaac Samuel
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
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Despite the growing understanding of PDGF signaling, studies of PDGF function have encountered two major obstacles: the functional redundancy of PDGFRα and PDGFRβ in vitro and their distinct roles in vivo. Here we used wild-type mouse embryonic fibroblasts (MEF), MEF null for either PDGFRα, β, or both to dissect PDGF-PDGFR signaling pathways. These four PDGFR genetically defined cells provided us a platform to study the relative contributions of the pathways triggered by the two PDGF receptors. They were treated with PDGF-BB and analyzed for differential gene expression, in vitro proliferation and differential response to pharmacological effects. No genes were differentially expressed in the double null cells, suggesting minimal receptor-independent signaling. Protean differentiation and proliferation pathways are commonly regulated by PDGFRα, PDGFRβ and PDGFRα/β while each receptor is also responsible for regulating unique signaling pathways. Furthermore, some signaling is solely modulated through heterodimeric PDGFRα/β.

Modificações na fisiologia e anatomia das folhas de espécies lenhosas jovens de cerrado sob irradiâncias contrastantes.

RONQUIM, C. C.
Fonte: In: CONGRESSO ABERTO AOS ESTUDANTES DE BIOLOGIA (CAEB), 9., 2009, Campinas, SP. Cadernos de resumos... Campinas, SP: Unicamp-IB, 2009. Publicador: In: CONGRESSO ABERTO AOS ESTUDANTES DE BIOLOGIA (CAEB), 9., 2009, Campinas, SP. Cadernos de resumos... Campinas, SP: Unicamp-IB, 2009.
Tipo: Resumo em anais de congresso (ALICE) Formato: p. 134.
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Na vegetação do cerrado, a adaptação a disponibilidade de luz é fundamental, pois há grande probabilidade dos indivíduos jovens, ainda pequenos, estarem sombreados. Mudas jovens de Anadenanthera falcata Benth. Speg. (Mimosoideae), Stryphnodendron adstringens Mart. Coville (Mimosoideae), Cybistax antisyphilitica. (Mart) Mart. (Bignoniaceae) e Copaifera tangsdorffii Desf. (Caesalpinioideae) e Eriotheca gracilipes (K. Schum) A Robins (Bombacaceae) foram cultivadas sob 60% de irradiância e posteriormente levadas e pleno sol. Após obtenção de curvas luz-fotossíntese e massa específica foliar (MEF) em ambas as condições, foram determinados valores de fotossíntese máxima, por área (Amaxa) e por massa (Amaxm) de folha, ponto de compensação à luz (PCL), radiação que satura a fotossíntese (RSF), respiração no escuro (Re) e eficiência quântica aparente (EQA). Os resultados indicaram que as espécies estudadas mostraram-se mais adaptadas à luz plena, contudo, todas apresentam plasticidade foliar, alterando a morfologia (MEF), assimilação de carbono; 2009

Estudo de campo de temperatura obtido numericamente para posterior determinação das tensões residuais numa junta soldada de aço ASTM AH36

Batista Guimarães, Pablo; Artur Sanguinetti Ferreira, Ricardo (Orientador)
Fonte: Universidade Federal de Pernambuco Publicador: Universidade Federal de Pernambuco
Tipo: Outros
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Neste trabalho foi desenvolvida uma metodologia numérico-experimental para determinar o campo de temperatura de uma junta soldada para posterior determinação das tensões residuais. Este modelo numérico se apóia no acoplamento de diferentes fenômenos físicos de natureza térmica, mecânica e metalúrgica presentes em uma operação de soldagem. As simulações numéricas foram realizadas através de um software baseado no método dos elementos finitos (MEF). Através do MEF consideraram-se aspectos que fazem a modelagem matemática do processo de soldagem complexa, tais como: as transformações de fase e as conseqüentes variações nas propriedades físicas e mecânicas dos materiais em função da temperatura, a transitoriedade e rapidez do processo de soldagem e os diferentes mecanismos de troca de calor com o meio (convecção e radiação), todos associados a uma elevada não-linearidade. A fonte de calor analítica utilizada para modelar o aporte térmico foi do tipo dupla elipsóide proposta por Goldak. Este modelo mostrou-se viável à aplicação na indústria devido seu controle através dos parâmetros de entrada do processo de soldagem, tais como: corrente e tensão elétrica e velocidade de soldagem. O material utilizado neste estudo foi composto por uma chapa de aço ASTM AH36...

Comparação de modelos computacionais para fluxo e transporte de poluentes em água subterrânea

da Costa Araújo, Clebenilson; Joaquim da Silva Pereira Cabral, Jaime (Orientador)
Fonte: Universidade Federal de Pernambuco Publicador: Universidade Federal de Pernambuco
Tipo: Outros
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155.00086%
Este trabalho apresenta um estudo da utilização de técnicas numéricas mais recentes e precisas associadas à modelagem do fluxo e transporte de poluentes em águas subterrâneas. A intenção principal é citar a técnica meshless e o modelo SUTRA como alternativas para a implementação dos problemas, bem como observar seus comportamentos em comparação aos métodos numéricos classicamente utilizados, tais como o Método dos Elementos Finitos (MEF) e o Método das Diferenças Finitas (MDF). Foram desenvolvidos alguns algoritmos em linguagem MatLab utilizando os chamados métodos sem malha de discretização, para o cálculo das cargas hidráulicas e do fluxo. Os métodos meshless utilizados são Métodos de Colocação utilizando Funções de Base Radial (FBR). No trabalho são apontados alguns exemplos de situações envolvendo o fluxo e o transporte de solutos em água subterrânea, os quais foram calculados utilizando-se a técnica proposta, meshless, e o modelo SUTRA, respectivamente. As soluções obtidas a partir da Função de Base Radial Multiquádrica (FBR-MQ) são mais precisas, quando comparadas aos resultados em MEF e MDF, e ainda, os resultados convergem rapidamente apenas com uma simples mudança do parâmetro de forma c. Observou-se ainda a redução dos tempos de processamento...

Uma metodologia para o estudo da flambagem de dutos aquecidos

Mendonça Belmont, Gustavo; Maria Bastos Afonso da Silva, Silvana (Orientador)
Fonte: Universidade Federal de Pernambuco Publicador: Universidade Federal de Pernambuco
Tipo: Outros
Português
Relevância na Pesquisa
155.00086%
O projeto e a manutenção de tubulações submetidas a altas pressões e variações de temperatura vem despertando especial interesse das empresas que lidam com este eficiente meio de transporte. Nos dutos submetidos a variações de temperaturas e altas pressões, surgem forças compressivas ao longo do seu eixo. Estas forças ocorrem devido às restrições impostas pelo solo à livre expansão axial do duto. Estes efeitos podem fazer com que as forças compressivas alcancem um valor crítico, induzindo à flambagem vertical ou lateral o que pode levar a ruptura da tubulação. No presente trabalho apresenta-se uma metodologia para o estudo da flambagem térmica de dutos com a finalidade de determinar a temperatura segura de operação, que é um parâmetro indispensável ao projeto deste tipo de estrutura. Tanto a flambagem lateral (snaking) como a flambagem vertical (upheaval buckling) são considerados. Procedimentos analíticos e numéricos são aqui investigados. A grande vantagem dos procedimentos analíticos implementados neste trabalho é que eles permitem uma avaliação rápida da influência de diversos parâmetros (rigidez do tubo, reação do solo, peso do duto, profundidade de enterramento, etc.), o que é muito útil em um projeto ou verificação. Contudo...