Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 69
Filtrar
1.
Proc Natl Acad Sci U S A ; 117(16): 9101-9111, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32245810

RESUMO

In eukaryotic photosynthetic organisms, the conversion of solar into chemical energy occurs in thylakoid membranes in the chloroplast. How thylakoid membranes are formed and maintained is poorly understood. However, previous observations of vesicles adjacent to the stromal side of the inner envelope membrane of the chloroplast suggest a possible role of membrane transport via vesicle trafficking from the inner envelope to the thylakoids. Here we show that the model plant Arabidopsis thaliana has a chloroplast-localized Sec14-like protein (CPSFL1) that is necessary for photoautotrophic growth and vesicle formation at the inner envelope membrane of the chloroplast. The cpsfl1 mutants are seedling lethal, show a defect in thylakoid structure, and lack chloroplast vesicles. Sec14 domain proteins are found only in eukaryotes and have been well characterized in yeast, where they regulate vesicle budding at the trans-Golgi network. Like the yeast Sec14p, CPSFL1 binds phosphatidylinositol phosphates (PIPs) and phosphatidic acid (PA) and acts as a phosphatidylinositol transfer protein in vitro, and expression of Arabidopsis CPSFL1 can complement the yeast sec14 mutation. CPSFL1 can transfer PIP into PA-rich membrane bilayers in vitro, suggesting that CPSFL1 potentially facilitates vesicle formation by trafficking PA and/or PIP, known regulators of membrane trafficking between organellar subcompartments. These results underscore the role of vesicles in thylakoid biogenesis and/or maintenance. CPSFL1 appears to be an example of a eukaryotic cytosolic protein that has been coopted for a function in the chloroplast, an organelle derived from endosymbiosis of a cyanobacterium.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas de Transferência de Fosfolipídeos/metabolismo , Fotossíntese , Tilacoides/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Cloroplastos , Microscopia Eletrônica de Transmissão , Mutação , Ácidos Fosfatídicos/metabolismo , Fosfatos de Fosfatidilinositol/metabolismo , Proteínas de Transferência de Fosfolipídeos/genética , Plantas Geneticamente Modificadas , Domínios Proteicos , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Plântula , Homologia de Sequência de Aminoácidos , Tilacoides/ultraestrutura
2.
Anal Bioanal Chem ; 412(24): 6199-6209, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32488390

RESUMO

Loop-mediated amplification (LAMP) is an isothermal amplification technique favored in diagnostics and point-of-care work due to its high sensitivity and ability to run in isothermal conditions. In addition, a visual readout by lateral flow strips (LFS) can be used in conjunction with LAMP, making the assay accessible at the point-of-care. However, the amplicons resulting from a LAMP reaction varied in length and shape, making them undiscernible on a double-stranded DNA intercalating dye stained gel. Standard characterization techniques also do not identify which amplicons specifically bind to the LFS, which generate the visual readout. We aimed to standardize our characterization of LAMP products during assay development by using fluorescein amidite (FAM) and biotin-tagged loop forward and backward primers during assay development. A pvuII restriction enzyme digest is applied to the LAMP products. FAM-tagged bands are directly correlated with the LFS visual readout. We applied this assay development workflow for an HPV 16 assay using both plasmid DNA and clinical samples to demonstrate proof of concept for generalized assay development work.


Assuntos
Papillomavirus Humano 16/isolamento & purificação , Técnicas de Amplificação de Ácido Nucleico/métodos , Sistemas Automatizados de Assistência Junto ao Leito , Papillomavirus Humano 16/genética , Humanos , Estudo de Prova de Conceito , Sensibilidade e Especificidade
3.
Org Biomol Chem ; 17(23): 5666-5670, 2019 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-30973549

RESUMO

Selective and sensitive detection of desired targets is very critical in sensor design. Here, we report a genetically engineered M13 bacteriophage-based sensor system evaluated by quantum mechanics (QM) calculations. Phage display is a facile way to develop the desired peptide sequences, but the resulting sequences can be imperfect peptides for binding of target molecules. A TNT binding peptide (WHW) carrying phage was self-assembled to fabricate thin films and tested for the sensitive and selective surface plasmon resonance-based detection of TNT molecules at the 500 femtomole level. SPR studies performed with the WHW peptide and control peptides (WAW, WHA, AHW) were well-matched with those of the QM calculations. Our combined method between phage engineering and QM calculation will significantly enhance our ability to design selective and sensitive sensors.


Assuntos
Bacteriófago M13/genética , Engenharia Genética , Trinitrotolueno/química , Regulação Viral da Expressão Gênica , Conformação Proteica , Teoria Quântica , Trinitrotolueno/metabolismo , Proteínas Virais
4.
Anal Chem ; 88(16): 8026-35, 2016 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-27429301

RESUMO

Traditional methods for identifying pathogens in bacteremic patients are slow (24-48+ h). This can lead to physicians making treatment decisions based on an incomplete diagnosis and potentially increasing the patient's mortality risk. To decrease time to diagnosis, we have developed a novel technology that can recover viable bacteria directly from whole blood and identify them in less than 7 h. Our technology combines a sample preparation process with surface-enhanced Raman spectroscopy (SERS). The sample preparation process enriches viable microorganisms from 10 mL of whole blood into a 200 µL aliquot. After a short incubation period, SERS is used to identify the microorganisms. We further demonstrated that SERS can be used as a broad detection method, as it identified a model set of 17 clinical blood culture isolates and microbial reference strains with 100% identification agreement. By applying the integrated technology of sample preparation and SERS to spiked whole blood samples, we were able to correctly identify both Staphylococcus aureus and Escherichia coli 97% of the time with 97% specificity and 88% sensitivity.


Assuntos
Escherichia coli/isolamento & purificação , Staphylococcus aureus/isolamento & purificação , Humanos , Análise Espectral Raman/instrumentação , Propriedades de Superfície
5.
Neurochem Res ; 41(10): 2788-2796, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27364962

RESUMO

Protein aggregation is a prominent feature of many neurodegenerative disorders including Parkinson's disease (PD). Aggregation of alpha-synuclein (SNCA) may underlie the pathology of PD. They are the main components of Lewy bodies and dystrophic neurites that are the intraneuronal inclusions characteristic of the disease. We have demonstrated that the polyphenol (-)-epi-gallocatechine gallate (EGCG) inhibited SNCA aggregation, which made it a candidate for therapeutic intervention in PD. Three methods were used: SNCA fibril formation inhibition by EGCG in incubates; inhibition of the SNCA fluorophore A-Syn-HiLyte488 binding to plated SNCA in microwells; and inhibition of the A-Syn-HiLyte488 probe binding to aggregated SNCA in postmortem PD tissue. Recombinant human SNCA was incubated under conditions that result in fibril formation. The aggregation was blocked by 100 nM EGCG in a concentration-dependent manner, as shown by an absence of thioflavin T binding. In the microplate assay system, the ED50 of EGCG inhibition of A-Syn-HiLyte488 binding to coated SNCA was 250 nM. In the PD tissue based assay, SNCA aggregates were recognized by incubation with 7 nM of A-Syn-HiLyte488. This binding was blocked by EGCG in a concentration dependent manner. The SNCA amino acid sites, which potentially interacted with EGCG, were detected on peptide membranes. It was implicated that EGCG binds to SNCA by instable hydrophobic interactions. In this study, we suggested that EGCG could be a potent remodeling agent of SNCA aggregates and a potential disease modifying drug for the treatment of PD and other α-synucleinopathies.


Assuntos
Catequina/análogos & derivados , Doença de Parkinson/metabolismo , alfa-Sinucleína/metabolismo , Catequina/farmacologia , Células Cultivadas , Humanos , Corpos de Lewy/efeitos dos fármacos , Corpos de Lewy/metabolismo , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/patologia
6.
Nano Lett ; 15(11): 7697-703, 2015 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-26455834

RESUMO

We report a highly selective and sensitive biosensor for the detection of an environmentally toxic molecule, decabrominated diphenyl ether (DBDE), one of the most common congeners of the polybrominated frame retardants (polybrominated diphenyl ether (PBDE)), using newly discovered DBDE peptide receptors integrated with carbon nanotube field-effect transistors (CNT-FET). The specific DBDE peptide receptor was identified using a high-throughput screening process of phage library display. The resulting binding peptide carries an interesting consensus binding pocket with two Trp-His/Asn-Trp repeats, which binds to the DBDE in a multivalent manner. We integrated the novel DBDE binding peptide onto the CNT-FET using polydiacetylene coating materials linked through cysteine-maleimide click chemistry. The resulting biosensor could detect the desired DBDE selectively with a 1 fM detection limit. Our combined approaches of selective receptor discovery, material nanocoating through click chemistry, and integration onto a sensitive CNT-FET electronic sensor for desired target chemicals will pave the way toward the rapid development of portable and easy-to-use biosensors for desired chemicals to protect our health and environment.


Assuntos
Técnicas Biossensoriais , Nanotubos de Carbono/química , Peptídeos/química , Receptores de Peptídeos/isolamento & purificação , Técnicas de Visualização da Superfície Celular , Química Click , Éteres Difenil Halogenados/química , Ligação Proteica , Receptores de Peptídeos/química
7.
Health Qual Life Outcomes ; 13: 126, 2015 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-26264130

RESUMO

AIMS: To assess the effect of a structured education intervention, Patient Empowerment Programme (PEP) patient-reported health-related quality of life (HRQOL) among type 2 diabetes mellitus (T2DM) patients, and if positive effect is confirmed, to further explore any association between frequency of sessions attendance and HRQOL. METHODS: A total of 298 T2DM patients were recruited when they attended the first session of PEP, between March and September 2010, and were followed over a one-year period from baseline. HRQOL data were assessed using Short Form-12 Health Survey version 2 (SF-12) and Short Form-6 Dimension (SF-6D) at baseline and one-year follow-up. Individuals' anthropometric and biomedical data were extracted from an administrative database in Hong Kong. Unadjusted and adjusted analyses of linear regression models were performed to examine the impact of PEP session attendance on the change in the HRQOL scores, accounting for the socio-demographic and clinical characteristics at baseline. RESULTS: Of the 298 eligible patients, 257 (86.2%) participated in the baseline assessment and 179 (60.1%) patients completed the follow-up assessment, respectively. Overall, PEP resulted in a significant improvement in SF-12 bodily pain and role emotional subscales and SF-6D utility scores. These positive changes were not associated with the level of participation as shown in both unadjusted and adjusted analyses. CONCLUSIONS: The PEP made significant improvement in bodily pain, role emotional and overall aspects of HRQOL. Higher number of session attendance was not associated with improvement in HRQOL in primary care real-world setting. Key Messages ● Participants with type 2 diabetes mellitus who participated in structured diabetes education programme made significant improvement in bodily pain and role emotional subscales and SF-6D scores. ● There was no association between the number of sessions attended and any aspect of HRQOL.


Assuntos
Diabetes Mellitus Tipo 2/psicologia , Educação de Pacientes como Assunto/estatística & dados numéricos , Participação do Paciente/estatística & dados numéricos , Qualidade de Vida , Autorrelato , Idoso , Feminino , Inquéritos Epidemiológicos , Hong Kong , Humanos , Masculino , Pessoa de Meia-Idade , Fatores Socioeconômicos
8.
Int Ophthalmol ; 35(3): 303-10, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24728535

RESUMO

To investigate the etiology and prevalence of optic neuritis in a Chinese population. This was a single centre prospective cohort study. Consecutive patients with either a first or recurrent attack of optic neuritis from November 2010 to December 2011 were recruited from a district hospital in Hong Kong Special Administrative Region, China. All patients underwent serology testing for NMO (neuromyelitis optica) IgG; oligoclonal bands from lumbar puncture; computer tomography and contrast magnetic resonance imaging (MRI) of the brain and orbit as well as visual field; and optical coherence tomography testing. Patients were followed up for 1 year after the initial attack. 30 optic neuritis subjects were recruited. 73.3 % (22/30) remain as clinical isolated syndrome (CIS) after 1-year follow-up. 10 % (3/30) patients developed multiple sclerosis. 10 % (3/30) were diagnosed with NMO and 6.7 % (2/30) with NMO-spectrum disorder. The majority of acute unilateral optic neuritis in Chinese was CIS in origin although a fraction does progress to develop MS or NMO-related disorders. Clinicians should be aware of the associations and offer appropriate systemic workups.


Assuntos
Neurite Óptica/epidemiologia , Adulto , Progressão da Doença , Feminino , Seguimentos , Hong Kong/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/complicações , Neuromielite Óptica/complicações , Neurite Óptica/diagnóstico , Neurite Óptica/etiologia , Prevalência , Estudos Prospectivos , Tomografia de Coerência Óptica/métodos
9.
Neuroophthalmology ; 39(1): 22-25, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27928326

RESUMO

The objective of this study was to investigate the longitudinal changes in retinal nerve fibre layer (RNFL) thickness 1 year after an episode of unilateral acute optic neuritis. This prospective cohort study recruited consecutive patients with a first episode of isolated, unilateral acute optic neuritis from October 2010 to June 2013. RNFL thickness of the attack and normal fellow eyes was measured by optical coherence tomography on presentation and 3, 6, and 12 months post attack in both the treatment and non-treatment groups. The treatment group consisted of subjects that opted for systemic steroids to hasten recovery time. In 20 subjects, 11 received systemic steroids and 9 were treated conservatively. The baseline RNFL thickness was similar in the attack and fellow eyes (p ≥ 0.4). Progressive RNFL thinning was seen in the attack eye over the 12-month period, with significant differences for baseline versus 3 months; baseline versus 12 months; and 3 versus 12 months (all p < 0.0001). At 12 months, the attack eye had a thinner average RNFL than the fellow eye (100.9 ± 6.1 versus 107.3 ± 5.5 µm; p = 0.002). The 12-month RNFL was similar between the treatment and non-treatment groups (p ≥ 0.6). A single episode of optic neuritis triggered an accelerated, progressive RNFL thinning up to 6 months post attack. Initial treatment with systemic steroids did not seem to alter the degree of RNFL loss at 12 months.

10.
Opt Express ; 22(20): 24507-15, 2014 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-25322026

RESUMO

The dark-field image obtained in grating-based x-ray phase-contrast imaging can provide information about the objects' microstructures on a scale smaller than the pixel size even with low geometric magnification. In this publication we demonstrate that the dark-field image quality can be enhanced with an energy-resolving pixel detector. Energy-resolved x-ray dark-field images were acquired with a 16-energy-channel photon-counting pixel detector with a 1 mm thick CdTe sensor in a Talbot-Lau x-ray interferometer. A method for contrast-noise-ratio (CNR) enhancement is proposed and validated experimentally. In measurements, a CNR improvement by a factor of 1.14 was obtained. This is equivalent to a possible radiation dose reduction of 23%.

11.
Opt Express ; 21(22): 25677-84, 2013 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-24216793

RESUMO

We have carried out grating-based x-ray differential phase-contrast measurements with a hybrid pixel detector in 16 energy channels simultaneously. A method for combining the energy resolved phase-contrast images based on energy weighting is presented. An improvement in contrast-to-noise ratio by 58.2% with respect to an emulated integrating detector could be observed in the final image. The same image quality could thus be achieved with this detector and with energy weighting at 60.0% reduced dose compared to an integrating detector. The benefit of the method depends on the object, spectrum, interferometer design and the detector efficiency.


Assuntos
Fotometria/instrumentação , Interpretação de Imagem Radiográfica Assistida por Computador/instrumentação , Refratometria/instrumentação , Tomografia Computadorizada por Raios X/instrumentação , Transdutores , Desenho de Equipamento , Análise de Falha de Equipamento , Fótons
12.
Health Qual Life Outcomes ; 11: 142, 2013 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-23964785

RESUMO

BACKGROUND: This study aimed to determine the associations of various clinical factors with generic health-related quality of life (HRQOL) scores among Hong Kong Chinese patients with type 2 diabetes mellitus (T2DM) in the outpatient primary care setting using the short-form 12 (SF-12). METHODS: A cross-sectional survey of 488 Chinese adults with T2DM recruited from a primary care outpatient clinic was conducted from May to August 2008. Data on the standard Chinese (HK) SF-12 Health Survey and patients' socio-demographics were collected from face-to-face interviews. Glycaemic control, body mass index (BMI), chronic co-morbidities, diabetic complications and treatment modalities were determined for each patient through medical records. Associations of socio-demographic and clinical factors with physical component summary (PCS-12) and mental component summary scores (MCS-12) were evaluated using multiple linear regression. RESULTS: The socio-demographic correlates of PCS-12 and MCS-12 were age, gender and BMI. After adjustment for socio-demographic variables, the BMI was negatively associated with PCS-12 but positively associated with MCS-12. The presence of diabetic complications was associated with lower PCS-12 (regression coefficient:-3.0 points, p < 0.05) while being on insulin treatment was associated with lower MCS-12 (regression coefficient:-5.8 points, p < 0.05). In contrast, glycaemic control, duration of T2DM and treatment with oral hypoglycaemic drugs were not significantly associated with PCS-12 or MCS-12. CONCLUSIONS: Among T2DM subjects in the primary care setting, impairments in the physical aspect of HRQOL were evident in subjects who were obese or had diabetic complications whereas defects in the mental aspect of HRQOL were observed in patients with lower BMI or receiving insulin injections.


Assuntos
Índice de Massa Corporal , Diabetes Mellitus Tipo 2/psicologia , Nível de Saúde , Qualidade de Vida/psicologia , Fatores Etários , Idoso , Intervalos de Confiança , Estudos Transversais , Feminino , Inquéritos Epidemiológicos , Hong Kong , Humanos , Masculino , Pessoa de Meia-Idade , Pesquisa Qualitativa , Fatores Sexuais
13.
ScientificWorldJournal ; 2013: 694613, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24459442

RESUMO

PURPOSE: To investigate the retinal nerve fibre layer (RNFL) thickness after unilateral acute optic neuritis using optical coherence tomography (OCT). PATIENTS AND METHODS: This prospective cohort study recruited consecutive patients with a first episode of isolated, unilateral acute optic neuritis. RNFL thickness and visual acuity (VA) of the attack and normal fellow eye were measured at presentation and 3 months in both the treatment and nontreatment groups. RESULTS: 11 subjects received systemic steroids and 9 were treated conservatively. The baseline RNFL thickness was similar in the attack and fellow eye (P ≥ 0.4). At 3 months, the attack eye had a thinner temporal (P = 0.02) and average (P = 0.05) RNFL compared to the fellow eye. At 3 months, the attack eye had significant RNFL thinning in the 4 quadrants and average thickness (P ≤ 0.0002) compared to baseline. The RNFL thickness between the treatment and nontreatment groups was similar at baseline and 3 months (P ≥ 0.1). Treatment offered better VA at 3 months (0.1 ± 0.2 versus 0.3 ± 0.2 LogMAR, P = 0.04). CONCLUSION: Generalized RNFL thinning occurred at 3 months after a first episode of acute optic neuritis most significantly in the temporal quadrant and average thickness. Visual improvement with treatment was independent of RNFL thickness.


Assuntos
Anti-Inflamatórios/uso terapêutico , Fibras Nervosas/patologia , Neurite Óptica/tratamento farmacológico , Neurite Óptica/patologia , Células Ganglionares da Retina/patologia , Tomografia de Coerência Óptica/métodos , Adolescente , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fibras Nervosas/efeitos dos fármacos , Tamanho do Órgão/efeitos dos fármacos , Estudos Prospectivos , Reprodutibilidade dos Testes , Células Ganglionares da Retina/efeitos dos fármacos , Sensibilidade e Especificidade , Resultado do Tratamento , Adulto Jovem
14.
Mol Cancer ; 11: 14, 2012 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-22439738

RESUMO

BACKGROUND: We had previously demonstrated overexpression of fibroblast growth factor receptor-4 (FGFR4) in hepatocellular carcinoma (HCC). However, additional molecular mechanisms resulting in amplified FGFR4 signaling in HCC remain under-studied. Here, we studied the mechanistic role of its co-receptor klotho-beta (KLB) in driving elevated FGFR4 activity in HCC progression. RESULTS: Quantitative real-time PCR analysis identified frequent elevation of KLB gene expression in HCC tumors relative to matched non-tumor tissue, with a more than two-fold increase correlating with development of multiple tumors in patients. KLB-silencing in Huh7 cells decreased cell proliferation and suppressed FGFR4 downstream signaling. While transient repression of KLB-FGFR4 signaling decreased protein expression of alpha-fetoprotein (AFP), a HCC diagnostic marker, prolonged inhibition enriched for resistant HCC cells exhibiting increased liver stemness. CONCLUSIONS: Elevated KLB expression in HCC tissues provides further credence to the oncogenic role of increased FGFR4 signaling in HCC progression and represents a novel biomarker to identify additional patients amenable to anti-FGFR4 therapy. The restricted tissue expression profile of KLB, together with the anti-proliferative effect observed with KLB-silencing, also qualifies it as a specific and potent therapeutic target for HCC patients. The enrichment of a liver stem cell-like population in response to extended KLB-FGFR4 repression necessitates further investigation to target the development of drug resistance.


Assuntos
Carcinoma Hepatocelular/metabolismo , Glucuronidase/metabolismo , Neoplasias Hepáticas/metabolismo , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/metabolismo , Carcinoma Hepatocelular/genética , Linhagem Celular Tumoral , Proliferação de Células , Glucuronidase/genética , Células Hep G2 , Humanos , Immunoblotting , Proteínas Klotho , Neoplasias Hepáticas/genética , RNA Interferente Pequeno , Reação em Cadeia da Polimerase em Tempo Real , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/genética
15.
Hong Kong Med J ; 18(1): 63-5, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22302915

RESUMO

This is a case report of a young healthy adult who had acute cerebral infarcts after a short-term visit to high-altitude area. He developed acute onset of right-sided limb weakness and right hemianopia a few hours after arrival at an altitude of 3600 m by train. He was initially treated for high-altitude cerebral oedema but later computed tomography and magnetic resonance imaging confirmed ischaemic infarcts in the medial left occipital lobe and left thalamus. Subsequent investigations, including laboratory tests and imaging including an echocardiogram, revealed no culpable predisposing factors.


Assuntos
Altitude , Isquemia Encefálica/etiologia , Acidente Vascular Cerebral/etiologia , Isquemia Encefálica/diagnóstico , Humanos , Imageamento por Ressonância Magnética , Masculino , Acidente Vascular Cerebral/diagnóstico , Tibet , Tomografia Computadorizada por Raios X , Viagem , Adulto Jovem
16.
J Cell Biochem ; 110(2): 438-46, 2010 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-20225273

RESUMO

Giant cell tumor (GCT) of bone is an aggressive non-cancerous tumor, which consists of multi-nucleated osteoclast-like giant cells, stromal cells, and monocytes. It is believed that stromal cells are the neoplastic component of this tumor. Expression of the receptor activator of nuclear factor kappa B ligand (RANKL) in the stromal cells stimulates the monocytes to form giant multi-nucleated osteoclast-like cells, causing bone over-resorption at the tumor site. Previously, our group has reported the up-regulation of RANKL in GCT of bone stromal cells, but the mechanism is unknown. Using stromal cell culture of GCT obtained from patients, we demonstrated the up-regulation of the transcriptional activator CCAAT/enhancer binding protein beta (C/EBPbeta). RANKL promoter studies revealed that C/EBPbeta over-expression induced RANKL promoter activity in a dose-dependent manner and a CCAAT-box within the region nt -357/-1 contributed to the basal transcription activity, with a possible C/EBPbeta binding element in the region nt -460/-358 leading to further induction. Furthermore, we also showed that C/EBPbeta bound to the RANKL promoter in GCT stromal cells in vivo by chromatin immunoprecipitation. To conclude, our study has shown that C/EBPbeta is a RANKL promoter activator in stromal cells of GCT of bone and we have proposed a model in which C/EBPbeta plays an important role in the osteolytic characteristics and pathological causes of GCT of bone.


Assuntos
Neoplasias Ósseas/metabolismo , Proteína beta Intensificadora de Ligação a CCAAT/metabolismo , Regulação da Expressão Gênica , Tumor de Células Gigantes do Osso/metabolismo , Ligante RANK/genética , Regulação para Cima , Sequência de Bases , Neoplasias Ósseas/patologia , Imunoprecipitação da Cromatina , Primers do DNA , Tumor de Células Gigantes do Osso/patologia , Humanos , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Regiões Promotoras Genéticas , Células Estromais/metabolismo
17.
Can J Gastroenterol ; 24(1): 40-6, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20186355

RESUMO

OBJECTIVE: To describe the natural history of primary sclerosing cholangitis (PSC) and inflammatory bowel disease (IBD) after liver transplant, the predictors of PSC and IBD recurrence, and the interaction of these disease processes. METHODS: Data regarding patients who received liver transplants for PSC at the University of Alberta Hospital (Edmonton, Alberta) from 1989 to 2006 were retrospectively reviewed. Recurrent PSC (rPSC) was defined by the Mayo Clinic criteria. Cox proportional hazards modelling and Kaplan-Meier statistics were used. RESULTS: Fifty-nine patients were studied, with a median follow-up of 68 months. A total of 71.2% of patients were diagnosed with IBD pretransplant. Clinical IBD severity post-transplant compared with severity pretransplant was unchanged in 67%, worse in 26.5% and improved in 6.1% of patients. Twenty-five per cent of patients developed rPSC posttransplant. The occurrence of at least one episode of acute cellular rejection (hazard ratio 5.7; 95% CI 1.3 to 25.8) and cytomegalovirus mismatch (hazard ratio 4.2; 95% CI 1.1 to 15.4) were found to be significant predictors of rPSC. Although not statistically significant, there was no rPSC in patients without pre- or post-transplant IBD, and in only one patient with a colectomy. Actuarial patient survival rates at one, five and 10 years posttransplant were 97%, 86% and 79%, respectively. Although a significant proportion of patients experienced worsening IBD post-transplantation, the presence or severity of IBD did not influence rPSC or patient survival. CONCLUSION: Acute cellular rejection and cytomegalovirus mismatch were both identified as independent predictors of rPSC. The impact of steroids and the ideal immunosuppressive regimen for the control of both IBD and PSC post-transplant requires further examination in prospective studies.


Assuntos
Colangite Esclerosante/terapia , Doenças Inflamatórias Intestinais/complicações , Transplante de Fígado , Adulto , Alberta , Colangite Esclerosante/complicações , Colangite Esclerosante/mortalidade , Citomegalovirus/imunologia , Feminino , Seguimentos , Rejeição de Enxerto/imunologia , Hospitais Universitários , Humanos , Doenças Inflamatórias Intestinais/fisiopatologia , Estimativa de Kaplan-Meier , Transplante de Fígado/imunologia , Masculino , Pessoa de Meia-Idade , Modelos de Riscos Proporcionais , Recidiva , Estudos Retrospectivos , Índice de Gravidade de Doença , Taxa de Sobrevida
18.
Can J Gastroenterol ; 24(1): 52-7, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20186357

RESUMO

Cholangiocarcinoma is the second most common primary hepatic tumour after hepatocellular carcinoma. Primary sclerosing cholangitis is one of the most commonly recognized risk factors for cholangiocarcinoma; however, approximately 90% of patients have no identifiable risk factors. Extrahepatic type is its most common presentation. Cholangiocarcinoma is considered to be a devastating disease, with a poor survival rate and few therapeutic options. Although surgical resection has been considered the best treatment option for localized cholangiocarcinoma, local recurrences of this cancer are very common, and imply persistent micro-metastatic disease in lymph nodes or at surgical margins, even after extended surgical resection. Consequently, the five year survival rate after attempted curative resection is only 20% to 40%. Early studies of liver transplantation for cholangiocarcinoma did not show a survival benefit and, currently, this tumour is considered to be an absolute contraindication for liver transplantation in most transplant centres worldwide. Recently, neoadjuvant chemoradiation in combination with liver transplantation for highly selected patients with cholangiocarcinoma has shown impressive results, with five-year survival rates at approximately 76% to 82%--similar to other standard indications for liver transplantation, such as hepatocellular carcinoma or hepatitis C-induced cirrhosis. However, this success of liver transplantation applies to only a subset of patients and most of the data originated from a single centre. Wider application of this strategy, especially for patients with potentially resectable disease, will require validation by other centres.


Assuntos
Neoplasias dos Ductos Biliares/terapia , Ductos Biliares Intra-Hepáticos/patologia , Colangiocarcinoma/terapia , Neoplasias dos Ductos Biliares/diagnóstico , Neoplasias dos Ductos Biliares/etiologia , Colangiocarcinoma/diagnóstico , Colangiocarcinoma/etiologia , Terapia Combinada , Humanos , Transplante de Fígado/métodos , Terapia Neoadjuvante/métodos , Fatores de Risco , Taxa de Sobrevida
19.
Biochem Biophys Res Commun ; 387(1): 149-52, 2009 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-19576176

RESUMO

Mutations in the alpha synuclein gene (SNCA) are the most potent cause of autosomal dominant Parkinson disease (PD) while mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common cause. We hypothesized that a direct interaction may exist between their protein products. Here we show that full-length Lrrk2 or fragments containing its kinase domain have a significant capacity to phosphorylate recombinant alpha synuclein (Asyn) at serine 129. Such phosphorylated Asyn is the major component of pathological deposits in PD. We further show that the G2019S mutation in Lrrk2, which is the most common genetic determinant of PD, has a significantly greater capacity than wild-type Lrrk2 to phosphorylate Asyn. This suggests that the G2019S mutant protein may cause PD by generating pathological levels of phosphorylated Asyn. Controlling Lrrk2 Asyn phosphokinase activity may be an approach to disease modifying therapy for PD and other synucleinopathies.


Assuntos
Doença de Parkinson/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Serina/metabolismo , alfa-Sinucleína/metabolismo , Linhagem Celular , Humanos , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina , Mutação , Doença de Parkinson/genética , Fosforilação , Estrutura Terciária de Proteína , Serina/genética , alfa-Sinucleína/genética
20.
Am J Gastroenterol ; 104(7): 1700-6, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19471253

RESUMO

OBJECTIVES: Liver transplantation for alcoholic liver disease (ALD) can be complicated by abusive or "problem" drinking (PD) after transplant. There are limited data for evaluating the effect of pre-transplant abstinence on post-transplant PD. Few existing studies have included a substantial number of patients with co-existing causes of hepatic dysfunction, and the effect of PD on survival in recent European studies has been controversial. We hypothesized that a longer duration of pre-transplant abstinence would lead to less PD after transplantation. Accordingly, the objectives of this study are to analyze a North American cohort of patients with ALD with or without a secondary diagnosis of liver disease to estimate (i) the incidence of PD and its predictors, as well as (ii) the effect of PD on patient survival. METHODS: We conducted a retrospective review of all patients transplanted for ALD surviving for more than 3 months after transplant. PD was defined as either any drinking (AD) to the point of intoxication or drinking above the toxic threshold (>20 g/day in women and >40 g/day in men) on at least two separate occasions. We used Cox's proportional hazards regression to estimate risk ratios and Kaplan-Meier curves with log-rank analysis to compare survival. RESULTS: Of 213 eligible transplant patients, 42 were excluded. Of the 171 remaining patients, 78% were male; mean age was 52 years. Overall 53% of patients had co-existing causes of liver dysfunction. The mean follow-up was 64.8 months. The median pre-transplant abstinence was 19 months. In all patients, the risk of AD was 24% and PD 13%. Pre-transplant abstinence duration was the only independent predictor of PD after transplant. For every 1-month increment in pre-transplant abstinence, there was a 5% decrease in the adjusted relapse rate. There was no survival difference noted between problem drinkers and non-drinkers. CONCLUSIONS: The risk of PD decreased with increasing pre-transplant abstinence. Our data support pre-transplant abstinence as an important predictor of post-transplant recidivism; however, the optimal period of abstinence remains unclear. Patients with <18 months of abstinence may benefit from more intensive follow-up and rehabilitation after transplant.


Assuntos
Consumo de Bebidas Alcoólicas/efeitos adversos , Causas de Morte , Rejeição de Enxerto/mortalidade , Hepatopatias Alcoólicas/mortalidade , Hepatopatias Alcoólicas/cirurgia , Transplante de Fígado/mortalidade , Estudos de Coortes , Feminino , Seguimentos , Humanos , Estimativa de Kaplan-Meier , Hepatopatias Alcoólicas/diagnóstico , Testes de Função Hepática , Transplante de Fígado/métodos , Masculino , Pessoa de Meia-Idade , Cuidados Pós-Operatórios , Valor Preditivo dos Testes , Cuidados Pré-Operatórios/métodos , Probabilidade , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Fatores de Risco , Assunção de Riscos , Índice de Gravidade de Doença , Estatísticas não Paramétricas , Análise de Sobrevida , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA