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1.
J Biomech ; 152: 111588, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-37094384

RESUMO

While cyclic adenosine monophosphate (cAMP) is typically considered an intracellular signal, it has been shown to spread between adjacent cells through connexin-based gap junction channels, promoting gap junctional intercellular communication (GJIC). Gap junction-mediated signaling is critical for the coordinated function of many tissues, and have been linked with cardiovascular disease, neurogenerative disease, and cancers. In particular, it plays a complex role in tumor suppression or promotion. This work introduces a two-dimensional finite element model that can describe intercellular cAMP signaling in the presence of gap junctions on membrane interfaces. The model was utilized to simulate cAMP transfer through one and two gap junction channels on the interface of a cluster of two pulmonary microvascular endothelial cells. The simulation results were found to generally agree with what has been observed in the literature in terms of GJIC. The research outcomes suggest that the proposed model can be employed to evaluate the permeability properties of a gap junction channel if its cAMP volumetric flow rate can be experimentally measured.


Assuntos
Células Endoteliais , Junções Comunicantes , Análise de Elementos Finitos , AMP Cíclico , Conexinas , Comunicação Celular
2.
Artigo em Inglês | MEDLINE | ID: mdl-35756693

RESUMO

Cyclic AMP (cAMP) is a second messenger that regulates a wide variety of cellular functions. There is increasing evidence suggesting that signaling specificity is due in part to cAMP compartmentalization. In the last 15 years, development of cAMP-specific Förster resonance energy transfer (FRET) probes have allowed us to visualize spatial distributions of intracellular cAMP signals. The use of FRET-based sensors is not without its limitations, as FRET probes display low signal to noise ratio (SNR). Hyperspectral imaging and analysis approaches have, in part, allowed us to overcome these limitations by improving the SNR of FRET measurements. Here we demonstrate that the combination of hyperspectral imaging approaches, linear unmixing, and adaptive thresholding allow us to visualize regions of elevated cAMP (regions of interest - ROIs) in an unbiased manner. We transfected cDNA encoding the H188 FRET-based cAMP probe into pulmonary microvascular endothelial cells. Application of isoproterenol and prostaglandin E1 (PGE1) triggered complex cAMP responses. Spatial and temporal aspects of cAMP responses were quantified using an adaptive thresholding approach and compared between agonist treatment groups. Our data indicate that both the origination sites and spatial/temporal distributions of cAMP signals are agonist dependent in PMVECs. We are currently analyzing the data in order to better quantify the distribution of cAMP signals triggered by different agonists.

3.
Forces Mech ; 42021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35072121

RESUMO

This paper presents a three-dimensional finite element model for cyclic adenosine monophosphate (cAMP) signaling. Governing equations for the synthesis, diffusion, and degradation of cAMP were numerically implemented using the finite element method. Simulated results were displayed as time course plots of cAMP concentrations at selected nodes within the discretized geometry. The validity of the finite element model was assessed by comparing simulated results against analytical or other numerical solutions of cAMP concentration distribution for a spherical cellular volume. An endothelial cell was also simulated using its discretized geometry obtained from microscopic cellular cross-sectional images. Simulated solutions using the spherical cellular volume produced near identical cAMP concentration plots to the analytical solutions and were in good agreements with numerical results obtained from VCell, an existing software package for modeling cell biological systems. The validated 3-D finite element model was then employed to simulate the cAMP signaling pathway within a pulmonary microvascular endothelial cell geometry.

4.
Cell Signal ; 75: 109769, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32898611

RESUMO

FÓ§rster resonance energy transfer (FRET) has been described for more than a century. FRET has become a mainstay for the study of protein localization in living cells and tissues. It has also become widely used in the fields that comprise cellular signaling. FRET-based probes have been developed to monitor second messenger signals, the phosphorylation state of peptides and proteins, and subsequent cellular responses. Here, we discuss the milestones that led to FRET becoming a widely used tool for the study of biological systems: the theoretical description of FRET, the insight to use FRET as a molecular ruler, and the isolation and genetic modification of green fluorescent protein (GFP). Each of these milestones were critical to the development of a myriad of FRET-based probes and reporters in common use today. FRET-probes offer a unique opportunity to interrogate second messenger signals and subsequent protein phosphorylation - and perhaps the most effective approach for study of cAMP/PKA pathways. As such, FRET probes are widely used in the study of intracellular signaling pathways. Yet, somehow, the potential of FRET-based probes to provide windows through which we can visualize complex cellular signaling systems has not been fully reached. Hence we conclude by discussing the technical challenges to be overcome if FRET-based probes are to live up to their potential for the study of complex signaling networks.


Assuntos
Transferência Ressonante de Energia de Fluorescência/métodos , AMP Cíclico , Citoplasma/metabolismo , Proteínas Luminescentes/química , Proteínas Luminescentes/metabolismo , Fosforilação , Transdução de Sinais
5.
SN Appl Sci ; 1(12)2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33615142

RESUMO

In this work, we present a two-dimensional finite element analysis (FEA) model that describes fundamental intracellular signals of cyclic adenosine monophosphate (cAMP) in a general fashion. The model was subsequently solved numerically and the results were displayed in forms of time-course plots of cAMP concentration at a cellular location or color-filled contour maps of cAMP signal distribution within the cell at specific time points. Basic intracellular cAMP signaling was described in this model so it can be numerically validated by verifying its numerical results against available analytical solutions and against results obtained from other numerical techniques reported in the literature. This is the first important step before the model can be expanded in future work. Model simulations demonstrate that under certain conditions, sustained cAMP concentrations can be formed within endothelial cells (ECs), similar to those observed in rat pulmonary microvascular ECs. Spatial and temporal cAMP dynamic simulations indicated that the proposed FEA model is an effective tool for the study of the kinetics and spatial spread of second messenger signaling and can be expanded to simulate second messenger signals in the pulmonary vasculature.

6.
Am J Physiol Lung Cell Mol Physiol ; 309(10): L1199-207, 2015 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-26386118

RESUMO

Here, we tested the hypothesis that a promiscuous bacterial cyclase synthesizes purine and pyrimidine cyclic nucleotides in the pulmonary endothelium. To test this hypothesis, pulmonary endothelial cells were infected with a strain of the Gram-negative bacterium Pseudomonas aeruginosa that introduces only exoenzyme Y (PA103 ΔexoUexoT::Tc pUCPexoY; ExoY(+)) via a type III secretion system. Purine and pyrimidine cyclic nucleotides were simultaneously detected using mass spectrometry. Pulmonary artery (PAECs) and pulmonary microvascular (PMVECs) endothelial cells both possess basal levels of four different cyclic nucleotides in the following rank order: cAMP > cUMP ≈ cGMP ≈ cCMP. Endothelial gap formation was induced in a time-dependent manner following ExoY(+) intoxication. In PAECs, intercellular gaps formed within 2 h and progressively increased in size up to 6 h, when the experiment was terminated. cGMP concentrations increased within 1 h postinfection, whereas cAMP and cUMP concentrations increased within 3 h, and cCMP concentrations increased within 4 h postinfection. In PMVECs, intercellular gaps did not form until 4 h postinfection. Only cGMP and cUMP concentrations increased at 3 and 6 h postinfection, respectively. PAECs generated higher cyclic nucleotide levels than PMVECs, and the cyclic nucleotide levels increased earlier in response to ExoY(+) intoxication. Heterogeneity of the cyclic nucleotide signature in response to P. aeruginosa infection exists between PAECs and PMVECs, suggesting the intracellular milieu in PAECs is more conducive to cNMP generation.


Assuntos
Células Endoteliais/metabolismo , Nucleotídeos Cíclicos/fisiologia , Pseudomonas aeruginosa/enzimologia , Permeabilidade Capilar , Células Cultivadas , Células Endoteliais/microbiologia , Interações Hospedeiro-Patógeno , Microvasos/citologia , Artéria Pulmonar/citologia
7.
Mol Psychiatry ; 20(4): 459-71, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25070536

RESUMO

Human mutations in PQBP1, a molecule involved in transcription and splicing, result in a reduced but architecturally normal brain. Examination of a conditional Pqbp1-knockout (cKO) mouse with microcephaly failed to reveal either abnormal centrosomes or mitotic spindles, increased neurogenesis from the neural stem progenitor cell (NSPC) pool or increased cell death in vivo. Instead, we observed an increase in the length of the cell cycle, particularly for the M phase in NSPCs. Corresponding to the developmental expression of Pqbp1, the stem cell pool in vivo was decreased at E10 and remained at a low level during neurogenesis (E15) in Pqbp1-cKO mice. The expression profiles of NSPCs derived from the cKO mouse revealed significant changes in gene groups that control the M phase, including anaphase-promoting complex genes, via aberrant transcription and RNA splicing. Exogenous Apc4, a hub protein in the network of affected genes, recovered the cell cycle, proliferation, and cell phenotypes of NSPCs caused by Pqbp1-cKO. These data reveal a mechanism of brain size control based on the simple reduction of the NSPC pool by cell cycle time elongation. Finally, we demonstrated that in utero gene therapy for Pqbp1-cKO mice by intraperitoneal injection of the PQBP1-AAV vector at E10 successfully rescued microcephaly with preserved cortical structures and improved behavioral abnormalities in Pqbp1-cKO mice, opening a new strategy for treating this intractable developmental disorder.


Assuntos
Terapia Genética , Microcefalia/genética , Microcefalia/terapia , Células-Tronco Neurais/fisiologia , Proteínas Nucleares/deficiência , Adenoviridae/genética , Animais , Subunidade Apc4 do Ciclossomo-Complexo Promotor de Anáfase/metabolismo , Apoptose/genética , Encéfalo/patologia , Proteínas de Transporte/genética , Moléculas de Adesão Celular/metabolismo , Ciclo Celular , Proliferação de Células , Proteínas de Ligação a DNA , Modelos Animais de Doenças , Embrião de Mamíferos , Feminino , Humanos , Masculino , Camundongos , Camundongos Knockout , Microcefalia/patologia , Nestina/genética , Nestina/metabolismo , Neurogênese , Proteínas Nucleares/genética , Sinapsinas/genética , Sinapsinas/metabolismo
8.
Vet Pathol ; 52(4): 621-30, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25161207

RESUMO

Canine cutaneous mast cell tumors (MCT) are common, frequently malignant neoplasms that are currently graded histologically for provision of prognostic information. Continuing evidence of subsets of MCT within certain grades (with differing survival times) indicate the need for biomarkers that will facilitate better patient stratification and also provide further information on the biological processes involved in progression. We decided to investigate the expression of p62/sequestosome-1 (p62/SQSTM1), a stress-inducible "hub protein" found in all cell types that shuttles rapidly between the nucleus and cytoplasm and is known to play important roles in protein handling and tumorigenesis. The identity of canine p62/SQSTM1 was confirmed in silico and by validation of a commercial antibody using both Western blotting and functional (pharmaceutical-based) analyses in cell culture. Using immunohistochemistry, 3 patterns of p62 expression were identified based on the predominant intracellular localization, that is, nuclear, mixed (nuclear and cytoplasmic), and cytoplasmic. There was a highly significant association with the 2-tier (Kiupel) grade (P < .0001), with all p62-nuclear immunoreactivity being associated with low grade and most p62-cytoplasmic immunoreactivity (93%) with high grade. Most but not all mixed nuclear-cytoplasmic labeling occurred in low-grade MCT; in other (human) tumor types, this pattern has been interpreted as borderline malignant. These data indicate that there is a shift in protein-handling stress from the nucleus to the cytoplasm in association with increasing malignancy in MCT. Studies to identify the processes and drug-able targets involved in this progression are ongoing.


Assuntos
Biomarcadores Tumorais/metabolismo , Doenças do Cão/patologia , Mastócitos/patologia , Proteína Sequestossoma-1/metabolismo , Neoplasias Cutâneas/veterinária , Sequência de Aminoácidos , Animais , Carcinogênese , Citoplasma/metabolismo , Doenças do Cão/metabolismo , Cães , Imuno-Histoquímica/veterinária , Mastócitos/metabolismo , Prognóstico , Alinhamento de Sequência , Proteína Sequestossoma-1/química , Proteína Sequestossoma-1/imunologia , Neoplasias Cutâneas/metabolismo , Neoplasias Cutâneas/patologia
10.
J Comp Pathol ; 147(2-3): 227-47, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22789861

RESUMO

The equine superficial digital flexor tendon (SDFT) is a frequently injured structure that is functionally and clinically equivalent to the human Achilles tendon (AT). Both act as critical energy-storage systems during high-speed locomotion and can accumulate exercise- and age-related microdamage that predisposes to rupture during normal activity. Significant advances in understanding of the biology and pathology of exercise-induced tendon injury have occurred through comparative studies of equine digital tendons with varying functions and injury susceptibilities. Due to the limitations of in-vivo work, determination of the mechanisms by which tendon cells contribute to and/or actively participate in the pathogenesis of microdamage requires detailed cell culture modelling. The phenotypes induced must ultimately be mapped back to the tendon tissue environment. The biology of tendon cells and their matrix, and the pathological changes occurring in the context of early injury in both horses and people are reviewed, with a particular focus on the use of various tendon cell and tissue culture systems to model these events.


Assuntos
Tendão do Calcâneo/lesões , Traumatismos em Atletas/patologia , Doenças dos Cavalos , Ruptura/veterinária , Traumatismos dos Tendões/veterinária , Animais , Modelos Animais de Doenças , Cavalos , Humanos , Coxeadura Animal , Projetos de Pesquisa , Ruptura/patologia , Traumatismos dos Tendões/patologia
11.
Horm Metab Res ; 44(5): 390-9, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22314389

RESUMO

Metastatic pheochromocytomas and paragangliomas are rare and challenging tumors. The tumor burden, combined with excessive catecholamine production, predispose to a broad spectrum of complications that range from spinal cord compression to any organ damage, all of which may lead to decreased quality of life and overall survival. Current therapies include surgery, systemic chemotherapy and radiopharmaceutical agents. Surgery is often a preferred therapy because it may cure or allow a long-term remission in patients with locoregional or isolated resectable distant metastases. Additionally, surgery can palliate symptoms related to tumor burden or catecholamine excess. However, in patients for whom surgery is not an option, systemic chemotherapy and radiopharmaceutical agents are preferred options. Systemic chemotherapy and radiopharmaceutical agents such as 131I-Metaiodobenzylguanidine (131I-MIBG) may cause partial responses or stabilization of disease with better blood pressure control and symptomatic and performance status improvement. However, as these therapies are only palliative, patients' quality of life and personal preferences should always be considered. The recognition of molecular pathways involved in the pheochromocytoma and paraganglioma tumorigenesis has driven the development of new therapeutic options. Agents such as tyrosine kinase, MAPK, PI3K, or hypoxia inducible factor inhibitors, alone or in combination, may represent novel therapeutic strategies that could be evaluated in prospective clinical trials. Transcriptional profiling and the development of personalized cancer medicine will help to pave the way for more specific therapeutic approaches and combinations.


Assuntos
Neoplasias das Glândulas Suprarrenais/terapia , Feocromocitoma/terapia , Neoplasias das Glândulas Suprarrenais/genética , Neoplasias das Glândulas Suprarrenais/radioterapia , Neoplasias das Glândulas Suprarrenais/cirurgia , Animais , Humanos , Terapia de Alvo Molecular , Metástase Neoplásica , Paraganglioma/genética , Paraganglioma/radioterapia , Paraganglioma/cirurgia , Paraganglioma/terapia , Feocromocitoma/genética , Feocromocitoma/radioterapia , Feocromocitoma/cirurgia
12.
J Clin Endocrinol Metab ; 95(5): 2023-37, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20215394

RESUMO

CONTEXT: Pheochromocytomas and paragangliomas (PHEO/PGL) are neuroendocrine tumors that arise from sympathetic and parasympathetic paraganglia. Diagnosed rarely during childhood, PHEO/PGL are nonetheless important clinical entities, particularly given our evolving understanding of their pathophysiology. EVIDENCE ACQUISITION: We identified articles through the U.S. National Library of Medicine by using the search terms pheochromocytoma and paraganglioma. Results were narrowed to manuscripts that included children and studies related to the genetics of PHEO/PGL. Web-based resources for genetic disorders were also used. For all articles, we performed subsequent reference searches and verification of source data. EVIDENCE SYNTHESIS: Up to 20% of PHEO/PGL are diagnosed in children. Most are functional tumors, and clinical presentation includes symptoms related to catecholamine hypersecretion and/or tumor mass effect. Increasingly, PHEO/PGL are identified during presymptomatic screening in children with genetic syndromes associated with PHEO/PGL (multiple endocrine neoplasia type 2, von Hippel-Lindau disease, and the paraganglioma syndromes). Plasma and/or urine metanephrines are the best diagnostic test for a functional tumor, and the management of pediatric patients is similar to adults. Genetic counseling should be undertaken in all cases. Although most pediatric PHEO/PGL are benign, these tumors can occasionally metastasize, a condition for which no curative treatment exists. CONCLUSIONS: Although PHEO/PGL are rarely diagnosed during childhood, the pediatric provider should be able to recognize and screen for such tumors, particularly in the context of a known genetic predisposition. Optimal care of these children includes a multidisciplinary team approach at centers experienced in the evaluation and treatment of these uncommon yet fascinating endocrine neoplasms.


Assuntos
Paraganglioma/etiologia , Feocromocitoma/etiologia , Criança , Dopamina/metabolismo , Aconselhamento Genético , Humanos , Mutação de Sentido Incorreto , Paraganglioma/diagnóstico por imagem , Paraganglioma/tratamento farmacológico , Paraganglioma/genética , Paraganglioma/terapia , Feocromocitoma/diagnóstico , Feocromocitoma/diagnóstico por imagem , Feocromocitoma/genética , Feocromocitoma/terapia , Radiografia , Proteína Supressora de Tumor Von Hippel-Lindau/genética
13.
Genome Biol ; 10(2): R21, 2009 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-19216790

RESUMO

BACKGROUND: The identification of genetic changes that confer drug resistance or other phenotypic changes in pathogens can help optimize treatment strategies, support the development of new therapeutic agents, and provide information about the likely function of genes. Elucidating mechanisms of phenotypic drug resistance can also assist in identifying the mode of action of uncharacterized but potent antimalarial compounds identified in high-throughput chemical screening campaigns against Plasmodium falciparum. RESULTS: Here we show that tiling microarrays can detect de novo a large proportion of the genetic changes that differentiate one genome from another. We show that we detect most single nucleotide polymorphisms or small insertion deletion events and all known copy number variations that distinguish three laboratory isolates using readily accessible methods. We used the approach to discover mutations that occur during the selection process after transfection. We also elucidated a mechanism by which parasites acquire resistance to the antimalarial fosmidomycin, which targets the parasite isoprenoid synthesis pathway. Our microarray-based approach allowed us to attribute in vitro derived fosmidomycin resistance to a copy number variation event in the pfdxr gene, which enables the parasite to overcome fosmidomycin-mediated inhibition of isoprenoid biosynthesis. CONCLUSIONS: We show that newly emerged single nucleotide polymorphisms can readily be detected and that malaria parasites can rapidly acquire gene amplifications in response to in vitro drug pressure. The ability to define comprehensively genetic variability in P. falciparum with a single overnight hybridization creates new opportunities to study parasite evolution and improve the treatment and control of malaria.


Assuntos
Resistência a Medicamentos/genética , Mutação , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Plasmodium falciparum/efeitos dos fármacos , Fosfomicina/análogos & derivados , Fosfomicina/farmacologia , Amplificação de Genes , Plasmodium falciparum/genética , Polimorfismo de Nucleotídeo Único
14.
Cell Res ; 18(6): 622-40, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18504460

RESUMO

The PML gene is involved in the t(15;17) translocation of acute promyelocytic leukaemia (APL), which generates the oncogenic fusion protein PML (promyelocytic leukaemia protein)-retinoic acid receptor alpha. The PML protein localises to a subnuclear structure called the PML nuclear domain (PML-ND), of which PML is the essential structural component. In APL, PML-NDs are disrupted, thus implicating these structures in the pathogenesis of this leukaemia. Unexpectedly, recent studies indicate that PML and the PML-ND play a tumour suppressive role in several different types of human neoplasms in addition to APL. Because of PML's extreme versatility and involvement in multiple cellular pathways, understanding the mechanisms underlying its function, and therefore role in tumour suppression, has been a challenging task. In this review, we attempt to critically appraise the more recent advances in this field and propose new avenues of investigation.


Assuntos
Neoplasias/metabolismo , Neoplasias/patologia , Proteínas Supressoras de Tumor/metabolismo , Animais , Núcleo Celular/metabolismo , Humanos , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Estrutura Terciária de Proteína , Proteínas Supressoras de Tumor/química
15.
Mol Immunol ; 45(5): 1477-84, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17928057

RESUMO

The promyelocytic leukaemia (PML) nuclear domain (PML-ND) is a nuclear sentinel for stress. Each PML-ND cradles a delicate scaffold of nucleoproteins, many of which can trigger the apoptotic death cascade if disrupted. Given their place in integrating stress and death, PML-NDs are obvious targets for excision from injury pathways by viruses and cancers. Viruses express proteins dedicated to silencing the PML-ND network and their failure can presage the suppression of viral replication. To understand how PML-NDs protect the cell from stress we must discover those damage pathways with which they connect. Such data will reveal the panoply of signal pathways lost in PML null cells and the extent to which infection and cancer can desensitise the cell to therapeutic intervention. A convenient and sensitive method with which to detect PML-ND stress induction is its biophysical reorganisation, as well defined dose responsive modifications of PML protein accompany damage recognition. The experiments that we present in this manuscript arose from an observation that lipid mediated transfection of plasmid DNA triggered a dramatic modification of PML-NDs that was identical to that seen following their recognition of DNA damage. In later experiments, we identified lipoprotein and IL-6 as potential mediators of this response. Collectively these data are the first to link an endotoxin component and IL-6 to the PML-ND compartment and, given the role of PML in cell fate, suggest increasing complexity at the interface of immunity and carcinogenesis.


Assuntos
Leucemia Promielocítica Aguda/patologia , Proteínas Nucleares , Estresse Fisiológico , Reação de Fase Aguda , Dano ao DNA , Endotoxinas , Humanos , Imunidade , Interleucina-6 , Leucemia Promielocítica Aguda/etiologia , Transdução de Sinais , Viroses
16.
Endoscopy ; 39(4): 319-24, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17357951

RESUMO

BACKGROUND AND STUDY AIMS: The current treatment model for the management of malignant biliary obstruction is to place a plastic stent for unstaged pancreatic cancer. In patients with unresectable disease but a life expectancy of more than 6 months, self-expandable metal stents (SEMS) are favored because of their more prolonged patency. We analyzed the efficacy and cost-effectiveness of covered SEMS (CSEMS) in patients with pancreatic cancer and distal biliary obstruction without regard to surgical resectability. PATIENTS AND METHODS: Between March 2001 and March 2005, 101 consecutive patients with obstructive jaundice secondary to pancreatic cancer underwent placement of a CSEMS. Patients with resectable tumor were offered pancreaticoduodenectomy. A model was developed to compare the costs of CSEMS and polyethylene and DoubleLayer stents. RESULTS: A total of 21 patients underwent staging laparoscopy, of whom 16 had a resection (76%). The 85 patients who did not have a resection had a mean survival of 5.9 months (range 1-25 months) and a mean CSEMS patency duration of 5.5 months (range 1-16 months). Life-table analysis demonstrated CSEMS patency rates of 97% at 3 months, 85% at 6 months, and 68% at 12 months. In a cost model that accounted for polyethylene and DoubleLayer stent malfunction and surgical resections, initial CSEMS placement (3177 euros per patient) was a less costly intervention than either DoubleLayer stent placement (3224 euros per patient) or polyethylene stent placement with revision (3570 euros per patient). CONCLUSIONS: Covered SEMS are an effective treatment for distal biliary obstructions caused by pancreatic carcinoma. Their prolonged patency and removability makes them an attractive option for biliary decompression, regardless of resectability. The strategy of initial covered SEMS placement might be the most cost-effective strategy in these patients.


Assuntos
Árvores de Decisões , Neoplasias Pancreáticas/terapia , Stents , Adulto , Idoso , Idoso de 80 Anos ou mais , Colestase/etiologia , Feminino , Humanos , Tábuas de Vida , Masculino , Pessoa de Meia-Idade , Neoplasias Pancreáticas/complicações , Neoplasias Pancreáticas/economia , Neoplasias Pancreáticas/cirurgia , Pancreaticoduodenectomia , Estudos Prospectivos , Desenho de Prótese , Stents/economia , Estados Unidos
17.
J Pathol ; 211(4): 471-80, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17206596

RESUMO

Promyelocytic leukaemia nuclear domains (PML-NDs) comprise a shell of PML protein and many labile cargo proteins. The nature of their cargo, their juxtaposition to foci of damaged DNA following ionizing radiation (IR), and the altered DNA damage responses in PML null cells all implicate PML-NDs in the DNA damage response. In this work, the propensity of PML-NDs to increase in number and decrease in size following IR has been studied. Serial quantitative studies of endogenous PML-NDs prove that the PML-ND response to IR is not the result of the asymmetry in cell cycle distribution that can follow IR, but reflects more directly the process of DNA damage. The response is swift, sensitive (evident after 1 Gy), and potentially reversible in untransformed fibroblasts. In these cells and in HCT116 colon cancer cells, failure to restore PML-ND number within 24 h correlates with later loss of growth potential--in fibroblasts, through prolonged cell cycle arrest and in HCT116 cells, through apoptosis. Failure to express an intact ATM/CHK2 DNA damage signalling pathway in either cell type leads to a delay in the PML-ND response to IR. Conversely, cell cycle progression following IR in cells that detect damaged DNA accelerates PML-ND reorganization. Collectively, these data show that the increase in PML-ND number seen after irradiation is, in part, triggered by the receipt of the DNA damage stimulus. The senescent cell state is also associated with chronic DNA damage and Hayflick-limited fibroblasts were found to express nuclei with elevated numbers of PML-NDs before IR that remained unresponsive to IR. Though the underlying reasons for damage-induced PML alteration remain obscure, it is noteworthy that significant numbers of PML-NDs juxtapose with ionizing radiation-induced foci after IR. The co-regulation of these structures may necessitate the stereotyped increases in PML-ND number following damage.


Assuntos
Núcleo Celular/genética , Dano ao DNA/genética , Leucemia Promielocítica Aguda/genética , Apoptose/genética , Ciclo Celular/genética , Linhagem Celular , Linhagem Celular Tumoral , Senescência Celular/genética , Quinase do Ponto de Checagem 2 , Dano ao DNA/efeitos da radiação , Fibroblastos/fisiologia , Genes Supressores de Tumor , Humanos , Imuno-Histoquímica/métodos , Proteínas de Neoplasias/genética , Proteínas Nucleares/genética , Proteínas Serina-Treonina Quinases/genética , Radiação Ionizante , Transdução de Sinais/genética
18.
Brain Res Bull ; 56(3-4): 273-80, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11719261

RESUMO

Polyglutamine(Q) tract binding protein-1 (PQBP-1) was isolated on the basis of its interaction with polyglutamine tracts and localizes predominantly to the nucleus where it suppresses transcriptional activation by a neuron-specific transcription factor, Brn-2. Its C-terminal domain is highly conserved and binds to a component of the spliceosome. PQBP-1 possesses unique repetitive sequences that may fold as polar zippers. Interestingly, PQBP-1 also forms nuclear inclusion bodies, which are similar to those nucleated by the protein products of polyglutamine disease genes. Furthermore, because PQBP-1 is highly conserved in simple animal metazoans and plants (Caenorhabditis elegans and Arabidopsis), it may perform a basic function in cells. By the same token, disruption of the basic function could be critical to the disease process. Collectively, PQBP-1 might be a candidate molecule involved in the pathology of polyglutamine diseases. In this review, we discuss the structure and function of the PQBP-1 protein, the relevance of its aggregation and possible roles in normal and disease processes.


Assuntos
Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Corpos de Inclusão/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Peptídeos/genética , Peptídeos/metabolismo , Animais , Morte Celular/fisiologia , Núcleo Celular/metabolismo , Proteínas de Ligação a DNA , Humanos , Dados de Sequência Molecular , Homologia de Sequência de Aminoácidos , Repetições de Trinucleotídeos
19.
Proc Natl Acad Sci U S A ; 98(23): 13049-54, 2001 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-11606735

RESUMO

cAMP, the classical second messenger, regulates many diverse cellular functions. The primary effector of cAMP signals, protein kinase A, differentially phosphorylates hundreds of cellular targets. Little is known, however, about the spatial and temporal nature of cAMP signals and their information content. Thus, it is largely unclear how cAMP, in response to different stimuli, orchestrates such a wide variety of cellular responses. Previously, we presented evidence that cAMP is produced in subcellular compartments near the plasma membrane, and that diffusion of cAMP from these compartments to the bulk cytosol is hindered. Here we report that a uniform extracellular stimulus initiates distinct cAMP signals within different cellular compartments. By using cyclic nucleotide-gated ion channels engineered as cAMP biosensors, we found that prostaglandin E(1) stimulation of human embryonic kidney cells caused a transient increase in cAMP concentration near the membrane. Interestingly, in the same time frame, the total cellular cAMP rose to a steady level. The decline in cAMP levels near the membrane was prevented by pretreatment with phosphodiesterase inhibitors. These data demonstrate that spatially and temporally distinct cAMP signals can coexist within simple cells.


Assuntos
Compartimento Celular , AMP Cíclico/metabolismo , Transdução de Sinais , 1-Metil-3-Isobutilxantina/farmacologia , Alprostadil/farmacologia , Cálcio/metabolismo , Calibragem , Linhagem Celular , Humanos , Transporte de Íons , Rim/citologia , Rim/efeitos dos fármacos , Rim/metabolismo , Técnicas de Patch-Clamp
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