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1.
Oncogene ; 34(25): 3273-82, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25132272

RESUMO

Hepatocarcinogenesis results from the accumulation of genetic and epigenetic changes in liver cells. A common mechanism through which these alterations induce liver cancer is by deregulating signaling pathways. A number of signaling pathways, including the PI3K/PTEN/AKT and transforming growth factor ß (TGF-ß) pathways have been implicated in normal liver development as well as in cancer formation. In this study, we assessed the effect of the TGF-ß signaling pathway on liver tumors induced by phosphatase and tensin homolog (Pten) loss. Inactivation of only the TGF-ß receptor type II, Tgfbr2, in the mouse liver (Tgfbr2(LKO)) had no overt phenotype, while inactivation of Pten alone (Pten(LKO)), resulted in the formation of both hepatocellular carcinomas and cholangiocarcinomas (CC). Interestingly, deletion of both Pten and Tgfbr2 (Pten(LKO);Tgfbr2(LKO)) in the mouse liver resulted in a dramatic shift in tumor type to predominantly CC. Assessment of the PI3K/PTEN/AKT pathway revealed increased phosphorylation of AKT and glycogen synthase kinase 3 beta (GSK-3ß) in both the Pten(LKO) and Pten(LKO);Tgfbr2(LKO) mice, suggesting that this pathway is constitutively active regardless of the status of the TGF-ß signaling pathway. However, phosphorylation of p70 S6 kinase was observed in the liver of all three phenotypes (Tgfbr2(LKO), Pten(LKO), Pten(LKO);Tgfbr2(LKO)) indicating that the loss of Tgfbr2 and/or Pten leads to an increase in this signaling pathway. Analysis of markers of liver progenitor/stem cells revealed that the loss of TGF-ß signaling resulted in increased expression of c-Kit and CD133. Furthermore, in addition to increased c-Kit and CD133, Scf and EpCam expression were also increased in the double knock-out mice. These results suggest that the alteration in tumor types between the Pten(LKO) mice and Pten(LKO);Tgfbr2(LKO) mice is secondary to the altered regulation of stem-cell features induced by the loss of TGF-ß signaling.


Assuntos
Carcinogênese , Neoplasias Hepáticas/patologia , PTEN Fosfo-Hidrolase/deficiência , Transdução de Sinais , Fator de Crescimento Transformador beta/metabolismo , Animais , Ductos Biliares/patologia , Biomarcadores Tumorais/metabolismo , Ativação Enzimática , Células Epiteliais/patologia , Feminino , Técnicas de Inativação de Genes , Hepatócitos/patologia , Neoplasias Hepáticas/genética , Masculino , Camundongos , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , PTEN Fosfo-Hidrolase/genética , PTEN Fosfo-Hidrolase/metabolismo , Receptores de Fatores de Crescimento Transformadores beta/deficiência , Receptores de Fatores de Crescimento Transformadores beta/genética
2.
Nat Mater ; 13(8): 817-21, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24880732

RESUMO

Liquid-crystalline polymers are materials of considerable scientific interest and technological value. An important subset of these materials exhibit rubber-like elasticity, combining the optical properties of liquid crystals with the mechanical properties of rubber. Moreover, they exhibit behaviour not seen in either type of material independently, and many of their properties depend crucially on the particular mesophase employed. Such stretchable liquid-crystalline polymers have previously been demonstrated in the nematic, chiral-nematic, and smectic mesophases. Here, we report the fabrication of a stretchable gel of blue phase I, which forms a self-assembled, three-dimensional photonic crystal that remains electro-optically switchable under a moderate applied voltage, and whose optical properties can be manipulated by an applied strain. We also find that, unlike its undistorted counterpart, a mechanically deformed blue phase exhibits a Pockels electro-optic effect, which sets out new theoretical challenges and possibilities for low-voltage electro-optic devices.


Assuntos
Géis/química , Cristais Líquidos/química , Elasticidade , Eletroquímica/métodos , Óptica e Fotônica , Fótons , Física/métodos , Polímeros/química , Temperatura
3.
Oncogene ; 33(12): 1538-47, 2014 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-23604118

RESUMO

The accumulation of genetic and epigenetic alterations mediates colorectal cancer (CRC) formation by deregulating key signaling pathways in cancer cells. In CRC, one of the most commonly inactivated signaling pathways is the transforming growth factor-beta (TGF-ß) signaling pathway, which is often inactivated by mutations of TGF-ß type II receptor (TGFBR2). Another commonly deregulated pathway in CRC is the phosphoinositide-3-kinase (PI3K)-AKT pathway. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is an important negative regulator of PI3K-AKT signaling and is silenced in ∼30% of CRC. The combination of TGFBR2 inactivation and loss of PTEN is particularly common in microsatellite-unstable CRCs. Consequently, we determined in vivo if deregulation of these two pathways cooperates to affect CRC formation by analyzing tumors arising in mice that lack Tgfbr2 and/or Pten specifically in the intestinal epithelium. We found that lack of Tgfbr2 (Tgfbr2(IEKO)) alone is not sufficient for intestinal tumor formation and lack of Pten (Pten(IEKO)) alone had a weak effect on intestinal tumor induction. However, the combination of Tgfbr2 inactivation with Pten loss (Pten(IEKO);Tgfbr2(IEKO)) led to malignant tumors in both the small intestine and colon in 86% of the mice and to metastases in 8% of the tumor-bearing mice. Moreover, these tumors arose via a ß-catenin-independent mechanism. Inactivation of TGF-ß signaling and loss of Pten in the tumors led to increased cell proliferation, decreased apoptosis and decreased expression of cyclin-dependent kinase inhibitors. Thus, inactivation of TGF-ß signaling and loss of PTEN cooperate to drive intestinal cancer formation and progression by suppressing cell cycle inhibitors.


Assuntos
Neoplasias do Colo/patologia , PTEN Fosfo-Hidrolase/deficiência , Transdução de Sinais , Fator de Crescimento Transformador beta/metabolismo , Animais , Carcinogênese/efeitos dos fármacos , Carcinogênese/genética , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/genética , Linhagem Celular Tumoral , Neoplasias do Colo/genética , Neoplasias do Colo/metabolismo , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Quinases Ciclina-Dependentes/antagonistas & inibidores , Progressão da Doença , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/genética , Técnicas de Inativação de Genes , Humanos , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/patologia , Camundongos , Mutação , PTEN Fosfo-Hidrolase/genética , Inibidores de Proteínas Quinases/farmacologia , Proteínas Serina-Treonina Quinases/deficiência , Proteínas Serina-Treonina Quinases/genética , Receptor do Fator de Crescimento Transformador beta Tipo II , Receptores de Fatores de Crescimento Transformadores beta/deficiência , Receptores de Fatores de Crescimento Transformadores beta/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética
4.
Artigo em Inglês | MEDLINE | ID: mdl-23848702

RESUMO

In this article, we investigate the spontaneous emission properties of radiating molecules embedded in a chiral nematic liquid crystal, under the assumption that the electronic transition frequency is close to the photonic edge mode of the structure, i.e., at resonance. We take into account the transition broadening and the decay of electromagnetic field modes supported by the so-called "mirrorless"cavity. We employ the Jaynes-Cummings Hamiltonian to describe the electron interaction with the electromagnetic field, focusing on the mode with the diffracting polarization in the chiral nematic layer. As known in these structures, the density of photon states, calculated via the Wigner method, has distinct peaks on either side of the photonic band gap, which manifests itself as a considerable modification of the emission spectrum. We demonstrate that, near resonance, there are notable differences between the behavior of the density of states and the spontaneous emission profile of these structures. In addition, we examine in some detail the case of the logarithmic peak exhibited in the density of states in two-dimensional photonic structures and obtain analytic relations for the Lamb shift and the broadening of the atomic transition in the emission spectrum. The dynamical behavior of the atom-field system is described by a system of two first-order differential equations, solved using the Green's-function method and the Fourier transform. The emission spectra are then calculated and compared with experimental data.

5.
Phys Rev E Stat Nonlin Soft Matter Phys ; 86(1 Pt 1): 011705, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23005435

RESUMO

We calculate the density of photon states (DOS) of the normal modes in dye-doped chiral nematic liquid crystal (LC) cells in the presence of various loss mechanisms. Losses and gain are incorporated into the transmission characteristics through the introduction of a small imaginary part in the dielectric constant perpendicular and along the director, for which we assume no frequency dispersion. Theoretical results are presented on the DOS in the region of the photonic band gap for a range of values of the loss coefficient and different values of the optical anisotropy. The obtained values of the DOS at the photonic band gap edges predict a reversal of the dominant modes in the structure. Our results are found to be in good agreement with the experimentally obtained excitation thresholds in chiral nematic LC lasers. The behavior of the DOS is also discussed for amplifying LC cells providing additional insight to the lasing mechanism of these structures.


Assuntos
Corantes/química , Cristais Líquidos/química , Modelos Químicos , Modelos Moleculares , Simulação por Computador , Densitometria , Transferência de Energia , Fótons
6.
Meat Sci ; 92(4): 837-40, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22863079

RESUMO

This study aimed to measure the amount of microbial contamination caused by inspecting the lymph nodes of adult sheep carcasses for caseous lymphadenitis (CLA). Surface swabs from carcasses pre-inspection (N=296) and post-inspection (N=296) were obtained for enumeration of indicator organisms at three commercial abattoirs. At the scapular site, inspection doubled the probability of detecting E. coli (Pr before=0.35, Pr after=0.67) and increased the expected count of E. coli from 2 cfu/cm² to 13 cfu/cm². Inspection at the rump site increased the probability of detecting E. coli by 1.1 times (Pr before=0.84, Pr after=0.93) and increased the expected count from 32 cfu/cm² to 45 cfu/cm². Effects were also observed for Enterobacteriaceae and total viable count. The findings show that routine inspection of adult sheep carcasses for CLA has a detrimental impact on carcass microbiological traits.


Assuntos
Infecções por Corynebacterium/veterinária , Contaminação de Alimentos , Inspeção de Alimentos , Linfonodos/patologia , Linfadenite/veterinária , Carne/microbiologia , Doenças dos Ovinos/patologia , Matadouros , Animais , Nádegas , Contagem de Colônia Microbiana , Infecções por Corynebacterium/diagnóstico , Infecções por Corynebacterium/patologia , Enterobacteriaceae/crescimento & desenvolvimento , Enterobacteriaceae/isolamento & purificação , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/isolamento & purificação , Contaminação de Alimentos/prevenção & controle , Linfadenite/diagnóstico , Linfadenite/patologia , Programas de Rastreamento/efeitos adversos , Programas de Rastreamento/veterinária , New South Wales , Palpação/efeitos adversos , Probabilidade , Escápula , Ovinos , Doenças dos Ovinos/diagnóstico , Propriedades de Superfície
7.
Nat Mater ; 11(7): 599-603, 2012 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-22581313

RESUMO

A promising approach to the fabrication of materials with nanoscale features is the transfer of liquid-crystalline structure to polymers. However, this has not been achieved in systems with full three-dimensional periodicity. Here we demonstrate the fabrication of self-assembled three-dimensional nanostructures by polymer templating blue phase I, a chiral liquid crystal with cubic symmetry. Blue phase I was photopolymerized and the remaining liquid crystal removed to create a porous free-standing cast, which retains the chiral three-dimensional structure of the blue phase, yet contains no chiral additive molecules. The cast may in turn be used as a hard template for the fabrication of new materials. By refilling the cast with an achiral nematic liquid crystal, we created templated blue phases that have unprecedented thermal stability in the range -125 to 125 °C, and that act as both mirrorless lasers and switchable electro-optic devices. Blue-phase templated materials will facilitate advances in device architectures for photonics applications in particular.

8.
Bioresour Technol ; 102(2): 1503-8, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20801645

RESUMO

This study demonstrates use of recombinant yeast to simultaneously saccharify and ferment grass juice (GJ) to bioethanol. A modified Bacillus subtilis levanase gene (sacC) in which the native bacterial signal sequence was replaced with a yeast α-factor domain, was synthesised with yeast codon preferences and transformed into Saccharomyces cerevisiae (strain AH22) using the expression vector pMA91. AH22:psacC transformants secreted sacCp as an active, hyper-glycosylated (>180 kDa) protein allowing them to utilise inulin (ß[2-1] linked fructose) and levan (ß[2-6] linkages) as growth substrates. The control (AH22:pMA91) strain, transformed with empty plasmid DNA was not able to utilise inulin or levan. When cultured on untreated GJ levels of growth and bioethanol production were significantly higher in experiments with AH22:psacC than with AH22:pMA91. Bioethanol yields from AH22:psacC grown on GJ (32.7[±4] mg mL(-1)) compared closely to those recently achieved (Martel et al., 2010) using enzymatically pre-hydrolysed GJ (36.8[±4] mg mL(-1)).


Assuntos
Bacillus subtilis/enzimologia , Biocombustíveis/análise , Etanol/síntese química , Fermentação , Glicosídeo Hidrolases/metabolismo , Poaceae/metabolismo , Saccharomyces cerevisiae/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/química , Biotecnologia , Metabolismo dos Carboidratos , Dados de Sequência Molecular , Recombinação Genética/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento , Transformação Genética
9.
Phys Rev Lett ; 104(15): 157801, 2010 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-20482018

RESUMO

We show theoretically that flexoelectricity stabilizes blue phases in chiral liquid crystals. Induced internal polarization reduces the elastic energy cost of splay and bend deformations surrounding singular lines in the director field. The energy of regions of double twist is unchanged. This in turn reduces the free energy of the blue phase with respect to that of the chiral nematic phase, leading to stability over a wider temperature range. The theory explains the discovery of large temperature range blue phases in highly flexoelectric "bimesogenic" and "bent-core" materials, and predicts how this range may be increased further.

10.
Neurotoxicol Teratol ; 32(2): 142-51, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-19737611

RESUMO

Methylphenidate (MPH) is an amphetamine derivative widely prescribed for the treatment of attention deficit-hyperactivity disorder. Recent concern over its genotoxic potential in children [11] spurred a study on the effects of chronic MPH treatment in a nonhuman primate population and the studies reported here were conducted in conjunction with that study in the same animals. Here, the focus was on the ability of juvenile rhesus monkeys to learn how to perform a battery of operant behavioral tasks while being treated chronically with MPH. Performance of the National Center for Toxicological Research (NCTR) Operant Test Battery (OTB) was used to quantify the learning of tasks thought to model specific aspects of cognitive function including learning, motivation, color and position discrimination, and short-term memory. The OTB tasks designed to assess these specific behaviors included Incremental Repeated Acquisition (IRA), Progressive Ratio (PR), Conditioned Position Responding (CPR), and Delayed Matching-to-Sample (DMTS), respectively. Juvenile males (n=10/group) pressed levers and press-plates for banana-flavored food pellets. Subjects were treated orally, twice a day, five days per week (M-F) for 66 weeks with escalating doses (0.15 mg/kg initially, increased to 2.5 mg/kg for the low dose group and to 12.5 mg/kg for the high dose group) and tested in OTB tasks 30 to 60 min after the morning dose. The findings indicate that MPH at doses up to 2.5 mg/kg twice per day were well tolerated (performance was no different than controls) but at doses of 12.5 mg/kg twice per day there was a significant decrement in OTB performance, characterized by decreases in both percent task completed and response rates for all tasks. These effects of MPH seem primarily due to decreases in motivation to perform for food, which is not surprising given the well known appetite suppressing effects of amphetamine-like stimulants. Thus, the current data do not strongly suggest cognitive impairments following chronic MPH administration.


Assuntos
Encéfalo/efeitos dos fármacos , Encéfalo/fisiopatologia , Estimulantes do Sistema Nervoso Central/toxicidade , Transtornos Cognitivos/induzido quimicamente , Transtornos Cognitivos/fisiopatologia , Metilfenidato/toxicidade , Fatores Etários , Envelhecimento/fisiologia , Animais , Apetite/efeitos dos fármacos , Depressores do Apetite/farmacologia , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Encéfalo/crescimento & desenvolvimento , Condicionamento Operante/efeitos dos fármacos , Condicionamento Operante/fisiologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Esquema de Medicação , Macaca mulatta , Masculino , Motivação/efeitos dos fármacos , Motivação/fisiologia , Testes Neuropsicológicos , Tempo
11.
Phys Rev E Stat Nonlin Soft Matter Phys ; 80(3 Pt 1): 031709, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19905133

RESUMO

The flexoelectro-optic effect describes the rotation of the optic axis of a short-pitch chiral nematic liquid crystal under the application of an electric field. We investigate the effect in the uniform standing helix, or "Grandjean" configuration. An in-plane electric field is applied. The director profile is determined numerically using a static one-dimensional continuum model with strong surface anchoring. The Berreman method is used to solve for plane-wave solutions to Maxwell's equations, and predict the optical properties of the resulting structure in general cases. By using a chiral nematic with short pitch between crossed polarizers an optical switch may be generated. With no applied field the configuration is nontransmissive at normal incidence, but becomes transmissive with an applied field. For this case, numerical results using the Berreman method are supplemented with an analytic theory and found to be in good agreement. The transmitted intensity as a function of tilt, the contrast ratio, and the tilt required for full intensity modulation are presented. The angular dependence of the transmission is calculated and the isocontrast curves are plotted. For typical material and cell parameters a switching speed of 0.017 ms and contrast ratio of 1500:1 at normal incidence are predicted, at a switch-on tilt of 41.5 degrees. Experimental verification of the analytic and numerical models is provided.

12.
Mutat Res ; 653(1-2): 76-81, 2008 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-18499509

RESUMO

The rhesus monkey (Macaca mulatta) has long been an important model in biomedical and behavioral research. The biomedical importance of M. mulatta is due to its 93% genetic similarity with humans and its complex social behavior. The recent sequencing of the M. mulatta genome has enhanced its role in biological research. However, the use of the macaque as an experimental model in cytogenetic assays has been problematic due to difficulties in obtaining large numbers of well-spread cells in metaphase without the use of extremely toxic mitogens such as staphylococcal enterotoxin A (SEA). Here we describe a technique for culturing and producing sufficient numbers of cells in metaphase using the common mitogens phytohemagglutinin (PHA), concanavalin A (ConA), and T-cell growth factor (TCGF) which act synergistically to induce M. mulatta T-lymphocyte division. Using this method we have obtained a mitotic index in 48 h cultures of 12.0+/-2.2 metaphase cells/100 cells (n=5 animals). Fluorescence in situ hybridization with whole chromosome painting of M. mulatta cells was performed with human whole-chromosome probes that labeled the following chromosomes for human (M. mulatta): 1(1), 2q(12), 2p(13), 4(5) pairs in red, and 3(2), 5(6) and 6(4) pairs in green. In humans this probe combination simultaneously paints 3 chromosome pairs in red and 3 in green, whereas in M. mulatta 4 chromosome pairs are labeled in red and 3 pairs are labeled in green. Using this method we show a baseline frequency of 0.026 translocations per 100 whole-genome cell equivalents in peripheral blood lymphocytes obtained from unexposed adolescent non-human primates. This method will add to the usefulness of M. mulatta as an animal model in biomedical research.


Assuntos
Técnicas de Cultura de Células , Coloração Cromossômica , Cromossomos de Mamíferos , Linfócitos/citologia , Modelos Biológicos , Animais , Células Cultivadas , Coloração Cromossômica/métodos , Genoma , Macaca mulatta , Metáfase/efeitos dos fármacos , Mitógenos/farmacologia , Translocação Genética/efeitos dos fármacos
13.
Phys Rev E Stat Nonlin Soft Matter Phys ; 75(4 Pt 1): 041701, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17500907

RESUMO

In this paper, we report on the flexoelastic and viscoelastic ratios for a number of bimesogens compounds with the same generic structure. Values are obtained indirectly by measuring the flexoelectro-optic response in the chiral nematic phase. By varying the molecular structure we alter the bend angle, transverse dipole moment, and length of the molecule. First, to examine the influence of the bend angle we use a homologous series whereby the only alteration in the molecular structure is the number of methylene units in the aliphatic spacer, n . Results show that the flexoelastic ratio, e/K , and the effective flexoelectric coefficient, e , both exhibit an odd-even effect with values for n=odd being greater than that for n=even . This is understood in terms of an increase in the bend angle of the molecule and an increase in the transverse dipole moment. Second, in order to investigate the impact of the dipole moment, we have altered the mesogenic units so as to vary the longitudinal dipole moment and used different linkages in the aliphatic spacer in an attempt to alter the transverse dipole moment. Qualitatively, the results demonstrate that the odd-spaced bimesogen with larger transverse dipole moments exhibit larger flexoelastic ratios.

14.
Phys Rev E Stat Nonlin Soft Matter Phys ; 76(5 Pt 1): 051703, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18233669

RESUMO

In this study we have fabricated eight different liquid-crystal lasers using the same gain medium but different homologues from the bimesogenic series alpha-(2',4-difluorobiphenyl-4'-yloxy)-omega-(4-cyanobiphenyl-4'-yloxy)alkanes, whereby the number of methylene units in the spacer chain varied from n=5 to n=12. To quantify the performance of these lasers, the threshold energy and the slope efficiency were extracted from the input-output characteristics of each laser. A clear odd-even effect was observed when both the excitation threshold and the slope efficiency were plotted as a function of the number of methylene units in the spacer chain. In all cases, the bimesogen lasers for which n is even exhibit lower threshold energies and higher slope efficiencies than those for which n is odd. These results are then interpreted in terms of the macroscopic physical properties of the liquid-crystalline compounds. In accordance with a previous study [S. M. Morris, A. D. Ford, M. N. Pivnenko, O. Hadeler, and H. J. Coles, Phys. Rev. E. 74, 061709 (2006)], a combination of a large birefringence and high order parameters are found, in the most part, to correlate with low-threshold energy and high slope efficiency. This indicates that the threshold and slope efficiency are dominated by the host macroscopic properties as opposed to intermolecular interactions between the dye and the liquid crystal. However, certain differences in the slope efficiency could not be explained by the birefringence and order parameter values alone. Instead, we find that the slope efficiency is further increased by increasing the elastic constants of the liquid-crystal host so as to decrease the scattering losses incurred by local distortions in the director field under high-energy optical excitation.

15.
Phys Rev E Stat Nonlin Soft Matter Phys ; 74(6 Pt 1): 061709, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17280086

RESUMO

In order to understand how the performance of a liquid-crystal laser depends on the physical properties of the low molar mass nematic host, we have studied the energy threshold and slope efficiency of ten optically pumped liquid-crystal lasers based on different hosts. Specifically, this leads to a variation in the birefringence, the orientational order parameter, and the order parameter of the transition dipole moment of the dye. It is found that low threshold energies and high slope efficiencies correlate with high order parameters and large birefringences. To a first approximation this can be understood by considering analytical expressions for the threshold and slope efficiency, which are derived from the space-independent rate equations for a two-level system, in terms of the macroscopic liquid crystal properties.

16.
Am J Physiol Renal Physiol ; 289(3): F569-76, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15870384

RESUMO

Disabled-2 (Dab2) is a cytoplasmic adaptor protein that binds to the cytoplasmic tail of the multiligand endocytic receptor megalin, abundantly expressed in renal proximal tubules. Deletion of Dab2 induces a urinary increase in specific plasma proteins such as vitamin D binding protein and retinol binding protein (Morris SM, Tallquist MD, Rock CO, and Cooper JA. EMBO J 21: 1555-1564, 2002). However, the subcellular localization of Dab2 in the renal proximal tubule and its function have not been fully elucidated yet. Here, we report the characterization of Dab2 in the renal proximal tubule. Immunohistocytochemistry revealed colocalization with megalin in coated pits and vesicles but not in dense apical tubules and the brush border. Kidney-specific megalin knockout almost abolished Dab2 staining, indicating that Dab2 subcellular localization requires megalin in the proximal tubule. Reciprocally, knockout of Dab2 led to a redistribution of megalin from endosomes to microvilli. In addition, there was an overall decrease in levels of megalin protein observed by immunoblotting but no decrease in clathrin or alpha-adaptin protein levels or in megalin mRNA. In rat yolk sac epithelial BN16 cells, Dab2 was present apically and colocalized with megalin. Introduction of anti-Dab2 antibody into BN16 cells decreased the internalization of 125I-labeled receptor-associated protein, substantiating the role of Dab2 in megalin-mediated endocytosis. The present study shows that Dab2 is localized in the apical endocytic apparatus of the renal proximal tubule and that this localization requires megalin. Furthermore, the study suggests that the urinary loss of megalin ligands observed in Dab2 knockout mice is caused by suboptimal trafficking of megalin, leading to decreased megalin levels.


Assuntos
Proteínas Adaptadoras de Transporte Vesicular/genética , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Túbulos Renais Proximais/fisiologia , Proteína-2 Relacionada a Receptor de Lipoproteína de Baixa Densidade/genética , Proteína-2 Relacionada a Receptor de Lipoproteína de Baixa Densidade/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Animais , Proteínas Reguladoras de Apoptose , Linhagem Celular Tumoral , Endocitose/fisiologia , Tumor do Seio Endodérmico , Imuno-Histoquímica , Túbulos Renais Proximais/ultraestrutura , Ligantes , Camundongos , Camundongos Knockout , Microscopia Imunoeletrônica , Ratos
17.
Mutat Res ; 549(1-2): 43-64, 2004 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-15120962

RESUMO

Microarray analysis is a powerful tool to identify the biological effects of drugs or chemicals on cellular gene expression. In this study, we compare the relationships between traditional measures of genetic toxicology and mutagen-induced alterations in gene expression profiles. TK6 cells were incubated with 0.01, 0.1, or 1.0 microM +/-anti-benzo(a)pyrene-trans-7,8-dihydrodiol-9,10-epoxide (BPDE) for 4 h and then cultured for an additional 20 h. Aliquots of the exposed cells were removed at 4 and 24 h in order to quantify DNA adduct levels by 32P post-labeling and measure cell viability by cloning efficiency and flow cytometry. Gene expression profiles were developed by extracting total RNA from the control and exposed cells at 4 and 24 h, labeling with Cy3 or Cy5 and hybridizing to a human 350 gene array. Mutant frequencies in the Thymidine Kinase and Hypoxanthine Phosphoribosyl Transferase genes were also determined. The 10alpha-(deoxyguanosin-N(2)-yl)-7alpha,8beta,9beta-trihydroxy-7,8,9,10-tetrahydrobenzo(a)pyrene (dG-N(2)-BPDE) adduct increased as a function of dose and was the only adduct identified. A dose-related decrease in cell viability was evident at 24 h, but not at 4 h. Cell death occurred by apoptosis. At 4 h, analysis of the gene expression profiles revealed that Glutathione Peroxidase and Gadd45 were consistently upregulated (greater than 1.5-fold and significantly (P < 0.001) greater than the control in two experiments) in response to 1.0 microM BPDE exposure. Fifteen genes were consistently down-regulated (less than 0.67-fold and significantly (P < 0.001) lower than the control in two experiments) at 4 h in cultures exposed to 1.0 microM BPDE. Genes with altered expression at 4 h included genes important in the progression of the cell-cycle and those that inhibit apoptosis. At 24 h post-exposure, 16 genes, involved in cell-cycle control, detoxification, and apoptosis were consistently upregulated; 10 genes were repressed in cultures exposed to the high dose of BPDE. Real-time quantitative PCR confirmed the differential expression of selected genes. These data suggest that changes in gene expression will help to identify effects of drugs and chemicals on molecular pathways in cells, and will provide useful information about the molecular responses associated with DNA damage. Of the endpoints evaluated, DNA adduct formation was the most sensitive indicator of DNA damage. DNA adduct formation was clearly evident at low doses, but the number of genes with significantly altered expression (P < 0.001) was minimal. Alterations in gene expression were more robust at doses associated with cellular toxicity and induction of mutations.


Assuntos
7,8-Di-Hidro-7,8-Di-Hidroxibenzo(a)pireno 9,10-óxido/toxicidade , Perfilação da Expressão Gênica , Mutagênicos/toxicidade , Sequência de Bases , Células Clonais , Adutos de DNA , Primers do DNA , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase
18.
Soc Sci Med ; 58(12): 2431-44, 2004 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15081195

RESUMO

The place of death of cancer patients has become an important theme in UK cancer and palliative care policy. This paper examines the place of death preferences of 41 terminally ill cancer patients and 18 of their informal carers, living in the Morecambe Bay area of north-west England. We interviewed cancer patients referred to the research team by 13 specialist palliative care professionals; patients had an estimated 3 months of life remaining. The study design involved an in-depth qualitative interview with each patient soon after referral to the study, followed by an interview some 4 weeks later and subsequent tracking interviews by telephone at 2-4 week intervals until death occurred. Interviews were also conducted with main coresident carers soon after patient referral to the study and again in the post-bereavement period. Thirteen factors were identified as shaping the place of death preference of patients and carers. These are organised into four thematic domains: the informal care resource, management of the body, experience of services, and existential perspectives. In documenting these factors, this paper adds significantly to current knowledge on the factors that shape place of death preference, a field of enquiry acknowledged to be underdeveloped (J. Palliative Med. 3 (2000) 287). More importantly, it uncovers some of the reasons that underpin these preferences. Our research revealed a much stronger preference for deaths in a hospice than had been anticipated, leading us to take a qualified stance on the current policy drive in favour of home deaths by those charged with delivering UK cancer and palliative care services.


Assuntos
Cuidados Paliativos na Terminalidade da Vida/normas , Neoplasias/mortalidade , Neoplasias/terapia , Satisfação do Paciente , Adulto , Idoso , Idoso de 80 Anos ou mais , Atitude Frente a Morte , Cuidadores/psicologia , Estudos de Coortes , Feminino , Cuidados Paliativos na Terminalidade da Vida/tendências , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Doente Terminal , Reino Unido
19.
Prev Med ; 38(3): 251-7, 2004 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-14766106

RESUMO

BACKGROUND: This study aims to determine whether healthcare providers' (HCPs') communication dealing with sun-protection (i.e., counseling) is associated with clients' skin-cancer-related prevention practices, detection self-efficacy, and knowledge. METHODS: Secondary analysis of two surveys of 1,469 randomly sampled farmers and soccer participants from southeast and coastal Georgia. RESULTS: Farmers and soccer participants who report ever having been counseled by a HCP about how to protect their skin from the sun report being more likely to wear sunscreen (P < 0.05), get clinical exams of their skin (P < 0.001), be certain that they can recognize unhealthy changes in their skin (P < 0.001), be certain that they know how to perform a skin exam (P < 0.001), and be knowledgeable about skin cancer prevention (P < 0.05 and P < 0.001, respectively); soccer participants are additionally more likely to wear protective headgear (P < 0.05) and perform monthly self-exams of their skin (P < 0.001). All analyses incorporated three control variables: participants' prior history of skin cancer, age, and non-HCP-derived skin-cancer awareness. CONCLUSIONS: Findings suggest that HCPs' counseling can positively shape skin-cancer-related prevention practices, detection self-efficacy, and knowledge. Additional research is needed on HCPs' actual communication about skin cancer and sun protection and its influence on client outcomes.


Assuntos
Agricultura , Conhecimentos, Atitudes e Prática em Saúde , Promoção da Saúde/métodos , Exposição Ocupacional/efeitos adversos , Neoplasias Cutâneas/prevenção & controle , Protetores Solares/administração & dosagem , Feminino , Georgia , Humanos , Masculino , Roupa de Proteção/estatística & dados numéricos , Análise de Regressão , Fatores de Risco , Neoplasias Cutâneas/etiologia , Futebol , Protetores Solares/uso terapêutico , Inquéritos e Questionários
20.
Eur J Oncol Nurs ; 7(1): 5-13; discussion 14-6, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12849570

RESUMO

The importance of psychosocial factors in the cancer journey for both patients and their carers has been recognised in UK health policy. The aim of this paper is to consider--(1) which needs are regarded as important by patients and their carers; (2) which are the unmet needs of patients and their carers. The study focuses on the responses of 233 paired cancer patients and their carers derived from a cross-sectional questionnaire survey in three health authorities in North West England. The majority of patient-carer pairs expressed the importance of having good relationships with health-care professionals and receiving good-quality information. These can be identified as "universal" needs. A minority of patient-carer pairs expressed the importance of other kinds of needs. These items were mainly to do with managing daily life, emotions, and social identity and can be identified as "situational" or "personal" needs. Where there were discrepancies between patients and carers, patients were likely to identify more needs as important. In contrast, carers have more unmet needs, reflecting their comparative neglect. Broadly, "universal" needs are being met, but "situational" and "personal" needs, particularly among carers, are relatively unmet and require greater attention on the part of nurses and primary care professionals.


Assuntos
Cuidadores/psicologia , Assistência Domiciliar/psicologia , Assistência Domiciliar/normas , Avaliação das Necessidades , Neoplasias/enfermagem , Qualidade de Vida , Adulto , Idoso , Estudos Transversais , Relações Familiares , Feminino , Humanos , Relações Interpessoais , Assistência de Longa Duração , Masculino , Pessoa de Meia-Idade , Psicologia , Medição de Risco , Apoio Social , Inquéritos e Questionários , Reino Unido
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