Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 55
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Colorectal Dis ; 17(10): 891-902, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25808234

RESUMO

AIM: Smoking is known to have a deleterious effect on Crohn's disease (CD). The present study addressed the specific impact of smoking on the outcome of surgery for CD. METHOD: A review of the National Surgical Quality Improvement Program (NSQIP) database (2005-2012) identified 7631 patients with CD who underwent surgical resection. Patients were stratified based on smoking status and were compared with univariate statistical tests. Generalized linear regression and multiple logistic regressions were used to model the impact of smoking on the surgical outcome [length of stay (LOS), mortality, postoperative complications and readmission]. To confirm the validity of the regression models and to evaluate the influence of smoking in comparable patient cohorts, a propensity score match was also performed. RESULTS: There were 2047 (26.8%) patients with CD identified as current smokers, and 5584 (74.2%) identified as non- or ex-smokers. Smokers were more likely to have a pulmonary comorbidity, preoperative weight loss and a higher American Society of Anesthesiologists classification. No differences in mortality were observed between smokers and non- or ex-smokers in univariate analysis. In multivariate analysis, smoking status was not significantly associated with LOS. Morbidity (OR 1.20, P = 0.003), particularly infectious (OR 1.30, P < 0.001) and pulmonary (OR 1.87, P < 0.001) complications, and readmission (OR 1.58, P = 0.004) were significantly associated with smoking status. These findings were validated on propensity-score matching analysis. CONCLUSION: In patients with CD, the detrimental effects of smoking on surgical outcomes are driven by infectious and pulmonary complications, and by an increased likelihood of readmission.


Assuntos
Colectomia/métodos , Doença de Crohn/cirurgia , Pneumopatias/epidemiologia , Complicações Pós-Operatórias/fisiopatologia , Melhoria de Qualidade/organização & administração , Fumar/efeitos adversos , Adulto , Distribuição por Idade , Idoso , Estudos de Casos e Controles , Colectomia/efeitos adversos , Doença de Crohn/diagnóstico , Doença de Crohn/epidemiologia , Bases de Dados Factuais , Feminino , Seguimentos , Humanos , Incidência , Modelos Logísticos , Pneumopatias/fisiopatologia , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Complicações Pós-Operatórias/epidemiologia , Avaliação de Programas e Projetos de Saúde , Pontuação de Propensão , Medição de Risco , Índice de Gravidade de Doença , Distribuição por Sexo , Fumar/epidemiologia , Resultado do Tratamento , Adulto Jovem
2.
Colorectal Dis ; 17(3): 250-6, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25307082

RESUMO

AIM: Compared with standard laparoscopic (SDL) approaches, less is known about the incidence of hernias after single-site laparoscopic (SSL) colorectal surgery. This study hypothesized that SSL colorectal surgery was associated with an increased risk of hernia development. METHOD: Institutional retrospective chart review (September 2008-June 2013) identified 276 evaluable patients who underwent laparoscopic colorectal procedures. The following data were collected: demographic data, risk factors for the development of a hernia, operative details and postoperative course including the development of a hernia. Patients were stratified by laparoscopic technique to compare the characteristics of those undergoing SDL and SSL. Patients were subsequently stratified by the presence or absence of a hernia to identify associated factors. RESULTS: One hundred and nineteen patients (43.1%) underwent SDL and 157 patients (56.9%) underwent SSL surgery. The development of an incisional hernia was observed in 7.6% (9/119) of SDL patients compared with 17.0% (18/106) of SSL patients (P = 0.03) over a median 18-month follow-up. Similar proportions of patients developed parastomal hernias in both groups [SDL 16.7% (10/60) vs SSL 15.9% (13/80)]. Hernias were diagnosed at a median of 8.1 (SDL) and 6.5 (SSL) months following the index operation and were less likely to be incarcerated in the SSL group [SDL 38.9% (7/18) vs SSL 6.5% (2/31), P = 0.01]. CONCLUSION: SSL colorectal surgery is associated with an increase in the incidence of incisional hernias but not parastomal hernias. Site of specimen extraction in SSL may contribute to the development of an incisional hernia.


Assuntos
Cirurgia Colorretal/efeitos adversos , Hérnia Ventral/epidemiologia , Laparoscopia/efeitos adversos , Laparoscopia/métodos , Adulto , Idoso , Cirurgia Colorretal/métodos , Feminino , Hérnia Ventral/etiologia , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Período Pós-Operatório , Estudos Retrospectivos , Fatores de Risco
3.
Colorectal Dis ; 16(5): 382-9, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24373345

RESUMO

AIM: Elective laparoscopic colectomy (LC) has been shown to provide short-term results comparable with open colectomy (OC), but there is potential selection bias whereby LC patients may be healthier and therefore more likely to have a superior outcome. The aim of this study was to compare the incidence of postoperative complications between matched laparoscopic and open colectomy cohorts, while controlling for differences in comorbidity. METHOD: A retrospective cohort study (2005-2010) using National Surgical Quality Improvement Program data was performed, identifying laparoscopic and open partial colectomy patients through common procedural terminology codes. Patient having rectal resection were excluded. The cohorts were matched 1:1 on a propensity score to control for observable selection bias due to patient characteristics, comparing overall complication rates, length of hospital stay (LOS), the incidence of superficial (S-SSI) surgical site infection, urinary tract infection (UTI) and deep-venous thrombosis (DVT). RESULTS: We analysed 37 249 patients. After propensity score matching the LC group had a significantly lower overall incidence of postoperative complications (29.1 vs 21.2%; P < 0.0001), S-SSI (9.0 vs 5.9%; P = 0.003) and DVT (1.2 vs 0.3%; P = 0.001). The LC group had a shorter LOS (8.7 vs 6.4 days; P < 0.0001), while mortality was comparable between the two groups (4.0 vs 4.1%; P = 0.578). CONCLUSION: LC is associated with a lower incidence of S-SSI and DVT than OC. Previously suggested advantages for laparoscopy, such as shorter length of stay and overall rate of complications, were observed even after controlling for differences in comorbidity.


Assuntos
Colectomia/efeitos adversos , Laparoscopia/efeitos adversos , Infecção da Ferida Cirúrgica/epidemiologia , Infecções Urinárias/epidemiologia , Trombose Venosa/epidemiologia , Idoso , Colectomia/métodos , Colectomia/estatística & dados numéricos , Feminino , Humanos , Incidência , Laparoscopia/estatística & dados numéricos , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Pontuação de Propensão , Estudos Retrospectivos , Viés de Seleção , Infecção da Ferida Cirúrgica/etiologia , Infecções Urinárias/etiologia , Trombose Venosa/etiologia
4.
Colorectal Dis ; 15(8): 974-81, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23336347

RESUMO

AIM: Previous reports describing Clostridium difficile colitis (CDC) developing after the closure of a loop ileostomy suggest it is severe. In this study the incidence of CDC following ileostomy closure and its effect on the postoperative outcome have been studied. METHOD: Patients undergoing closure of loop ileostomy from 2004 to 2008 were analysed using the Nationwide Inpatient Sample. Patients who developed postoperative CDC (n = 217) were matched 10:1 to a propensity-score-matched cohort of patients without CDC (n = 13 245). Linear and logistic regression were used to examine the effect of CDC on hospital cost (US dollars), length of stay and mortality rates. Population resampling was performed using nearest neighbour bootstrapping to confirm the validity of the results. RESULTS: The incidence of CDC following ileostomy closure was 16 per 1000 patients. The mean length of stay was 11.5 days longer among CDC patients (P < 0.0001), with a greater cost of hospitalization of US$21 240 (P < 0.0001). There was no difference in mortality between the cohorts. CONCLUSION: CDC following ileostomy closure is an uncommon, costly and morbid complication. Patients undergoing stoma closure are at high risk for an adverse outcome if they have CDC. Should it develop they should be aggressively treated.


Assuntos
Infecções por Clostridium/etiologia , Clostridium difficile , Colite/etiologia , Custos Hospitalares/estatística & dados numéricos , Ileostomia , Doenças Inflamatórias Intestinais/complicações , Complicações Pós-Operatórias/microbiologia , Adulto , Idoso , Infecções por Clostridium/economia , Infecções por Clostridium/mortalidade , Estudos de Coortes , Colite/economia , Colite/mortalidade , Custos e Análise de Custo , Feminino , Humanos , Incidência , Doenças Inflamatórias Intestinais/cirurgia , Tempo de Internação , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/economia , Complicações Pós-Operatórias/mortalidade , Pontuação de Propensão
5.
Colorectal Dis ; 15(7): 798-804, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23350898

RESUMO

AIM: It is unclear whether colectomy for fulminant Clostridium difficile colitis (FCDC) leads to a improvement in survival compared with continued medical therapy for this moribund population. METHOD: Selected studies from 1994-2010 were identified through a comprehensive search theme applied to MEDLINE (OvidSP and PubMed), EMBASE and by hand searching. Data regarding mortality rates between medically and surgically treated patients were extracted. Risk of bias was assessed using a Newcastle-Ottawa Scale score. A meta-analysis of the odds ratios for mortality between surgical and medical treatment for FCDC was conducted using the Mantel-Haenszel method and fixed-effects modelling. RESULTS: Five hundred and ten patients with FCDC were identified in six studies. The pooled adjusted odds ratio of mortality comparing surgery with medical therapy was 0.70 (0.49-0.99), suggesting that surgery provided a survival benefit. CONCLUSION: Emergent colectomy for patients with FCDC provides a survival advantage compared with continuing antibiotics. Though there is selection bias of patients having surgery, the results of this systematic review suggest that colectomy has a therapeutic role in treating severe forms of C. difficile colitis.


Assuntos
Clostridium difficile , Colectomia , Enterocolite Pseudomembranosa/cirurgia , Infecções por Clostridium/cirurgia , Colite/cirurgia , Enterocolite Pseudomembranosa/mortalidade , Humanos , Índice de Gravidade de Doença , Resultado do Tratamento
6.
Br J Dermatol ; 164(5): 996-1003, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21166661

RESUMO

BACKGROUND: Topically applied calcineurin inhibitors have been shown to be effective in the treatment of atopic dermatitis. When systemically administered, these agents cause immunosuppression via inhibition of calcineurin in lymphocytes. As topical agents, the mechanism of action is poorly defined. OBJECTIVES: To test the hypothesis that skin-infiltrating lymphocytes are directly targeted when calcineurin inhibitors are applied to the skin. METHODS: Ten patients with atopic dermatitis were treated with 1% pimecrolimus cream twice daily to target lesions. Skin biopsies were performed before and 48 h after beginning therapy. We assessed the cellular localization of NFAT1 and NFAT2 as a surrogate measure of intracellular calcineurin activity (e.g. increasing cytoplasmic localization with increasing calcineurin inhibition). RESULTS: All patients showed a clinical response, at both 48 h and 2 weeks. As previously described, NFAT2 localized to the follicular keratinocytes, and its activation was partially inhibited by topical pimecrolimus. NFAT1 was found to be expressed by follicular and interfollicular keratinocytes, and its mostly nuclear localization was not affected by topical pimecrolimus therapy. Both NFAT1 and NFAT2 were found in the infiltrating lymphocytes. However, using both manual counting as well as an automated method to assess nuclear intensity of NFAT staining, we found that the proportion of infiltrating leucocytes with nuclear ('activated') NFAT did not change following therapy with pimecrolimus. CONCLUSIONS: Our results suggest that topical pimecrolimus does not act primarily by inhibiting the calcineurin/NFAT axis in lymphocytes but may instead act by other mechanisms, possibly by decreasing NFAT2 activity in follicular keratinocytes.


Assuntos
Dermatite Atópica/tratamento farmacológico , Imunossupressores/farmacologia , Linfócitos/efeitos dos fármacos , Tacrolimo/análogos & derivados , Administração Tópica , Biópsia , Inibidores de Calcineurina , Dermatite Atópica/patologia , Imunofluorescência , Humanos , Imuno-Histoquímica , Imunossupressores/uso terapêutico , Linfócitos/metabolismo , Fatores de Transcrição NFATC/metabolismo , Tacrolimo/farmacologia , Tacrolimo/uso terapêutico
7.
J Biol Chem ; 276(15): 12301-9, 2001 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-11121423

RESUMO

Cadherins are single pass transmembrane proteins that mediate Ca(2+)-dependent homophilic cell-cell adhesion by linking the cytoskeletons of adjacent cells. In adherens junctions, the cytoplasmic domain of cadherins bind to beta-catenin, which in turn binds to the actin-associated protein alpha-catenin. The physical properties of the E-cadherin cytoplasmic domain and its interactions with beta-catenin have been investigated. Proteolytic sensitivity, tryptophan fluorescence, circular dichroism, and (1)H NMR measurements indicate that murine E-cadherin cytoplasmic domain is unstructured. Upon binding to beta-catenin, the domain becomes resistant to proteolysis, suggesting that it structures upon binding. Cadherin-beta-catenin complex stability is modestly dependent on ionic strength, indicating that, contrary to previous proposals, the interaction is not dominated by electrostatics. Comparison of 18 cadherin sequences indicates that their cytoplasmic domains are unlikely to be structured in isolation. This analysis also reveals the presence of PEST sequences, motifs associated with ubiquitin/proteosome degradation, that overlap the previously identified beta-catenin-binding site. It is proposed that binding of cadherins to beta-catenin prevents recognition of degradation signals that are exposed in the unstructured cadherin cytoplasmic domain, favoring a cell surface population of catenin-bound cadherins capable of participating in cell adhesion.


Assuntos
Caderinas/metabolismo , Citoplasma/metabolismo , Proteínas do Citoesqueleto/metabolismo , Transativadores , Sequência de Aminoácidos , Animais , Sequência de Bases , Caderinas/química , Adesão Celular , Dicroísmo Circular , Primers do DNA , Humanos , Dados de Sequência Molecular , Ressonância Magnética Nuclear Biomolecular , Proteínas Recombinantes/metabolismo , Homologia de Sequência de Aminoácidos , Espectrometria de Fluorescência , beta Catenina
8.
J Biol Chem ; 275(27): 20707-16, 2000 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-10747916

RESUMO

Cadherins mediate cell-cell adhesion, but little is known about how their expression is regulated. In Madin-Darby canine kidney (MDCK) cells, the cadherin-associated cytoplasmic proteins alpha- and beta-catenin form high molecular weight protein complexes with two glycoproteins (Stewart, D. B., and Nelson, W. J. (1997) J. Biol. Chem. 272, 29652-29662), one of which is E-cadherin and the other we show here is the type II cadherin, cadherin-6 (K-cadherin). In low density, motile MDCK cells, the steady-state level of cadherin-6 is low, but protein is synthesized. However, following cell-cell adhesion, cadherin-6 becomes stabilized and accumulates by >50-fold at cell-cell contacts while the E-cadherin level increases only 5-fold during the same period. To investigate a role of beta-catenin in regulation of cadherin expression in MDCK cells, we examined the effects of expressing signaling-active beta-catenin mutants (DeltaGSK, DeltaN90, and DeltaN131). In these cells, while levels of E-cadherin, alpha- and beta-catenin are similar to those in control cells, levels of cadherin-6 are significantly reduced due to rapid degradation of newly synthesized protein. Additionally, these cells appeared more motile and less cohesive, as expression of DeltaGSK-beta-catenin delayed the establishment of tight confluent cell monolayers compared with control cells. These results indicate that the level of cadherin-6, but not that of E-cadherin, is strictly regulated post-translationally in response to Wnt signaling, and that E-cadherin and cadherin-6 may contribute different properties to cell-cell adhesion and the epithelial phenotype.


Assuntos
Caderinas/metabolismo , Proteínas do Citoesqueleto/metabolismo , Transdução de Sinais , Transativadores , Sequência de Aminoácidos , Animais , Caderinas/genética , Adesão Celular , Linhagem Celular , Clonagem Molecular , Proteínas do Citoesqueleto/genética , Cães , Imunofluorescência , Regulação da Expressão Gênica , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Dados de Sequência Molecular , Mutação , Ligação Proteica , RNA Mensageiro/metabolismo , beta Catenina
9.
Proc Natl Acad Sci U S A ; 96(9): 4947-52, 1999 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-10220399

RESUMO

N-terminal mutations in beta-catenin that inhibit beta-catenin degradation are found in primary tumors and cancer cell lines, and increased beta-catenin/T cell factor (TCF)-activated transcription in these cells has been correlated with cancer formation. However, the role of mutant beta-catenin in cell transformation is poorly understood. Here, we compare the ability of different N-terminal mutations of beta-catenin (DeltaN131, DeltaN90, DeltaGSK) to induce TCF-activated transcription and anchorage-independent growth in Madin-Darby canine kidney epithelial cells. Expression of DeltaN90 or DeltaGSK beta-catenin increased TCF-activated transcription but did not induce significant anchorage-independent cell growth. In contrast, deletion of the alpha-catenin-binding site in DeltaN131 beta-catenin reduced TCF-activated transcription, compared with that induced by DeltaN90 or DeltaGSK beta-catenin, but significantly enhanced anchorage-independent cell growth.


Assuntos
Proteínas do Citoesqueleto/genética , Células Epiteliais/citologia , Transativadores , Fatores de Transcrição/genética , Ativação Transcricional , Animais , Sequência de Bases , Divisão Celular/genética , Transformação Celular Neoplásica , Cães , Humanos , Dados de Sequência Molecular , Mutação , Transdução de Sinais/genética , Células Tumorais Cultivadas , beta Catenina
10.
J Cell Biol ; 144(4): 687-99, 1999 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-10037790

RESUMO

The E-cadherin/catenin complex regulates Ca++-dependent cell-cell adhesion and is localized to the basal-lateral membrane of polarized epithelial cells. Little is known about mechanisms of complex assembly or intracellular trafficking, or how these processes might ultimately regulate adhesion functions of the complex at the cell surface. The cytoplasmic domain of E-cadherin contains two putative basal-lateral sorting motifs, which are homologous to sorting signals in the low density lipoprotein receptor, but an alanine scan across tyrosine residues in these motifs did not affect the fidelity of newly synthesized E-cadherin delivery to the basal-lateral membrane of MDCK cells. Nevertheless, sorting signals are located in the cytoplasmic domain since a chimeric protein (GP2CAD1), comprising the extracellular domain of GP2 (an apical membrane protein) and the transmembrane and cytoplasmic domains of E-cadherin, was efficiently and specifically delivered to the basal-lateral membrane. Systematic deletion and recombination of specific regions of the cytoplasmic domain of GP2CAD1 resulted in delivery of <10% of these newly synthesized proteins to both apical and basal-lateral membrane domains. Significantly, >90% of each mutant protein was retained in the ER. None of these mutants formed a strong interaction with beta-catenin, which normally occurs shortly after E-cadherin synthesis. In addition, a simple deletion mutation of E-cadherin that lacks beta-catenin binding is also localized intracellularly. Thus, beta-catenin binding to the whole cytoplasmic domain of E-cadherin correlates with efficient and targeted delivery of E-cadherin to the lateral plasma membrane. In this capacity, we suggest that beta-catenin acts as a chauffeur, to facilitate transport of E-cadherin out of the ER and the plasma membrane.


Assuntos
Caderinas/química , Caderinas/metabolismo , Proteínas do Citoesqueleto/química , Proteínas do Citoesqueleto/metabolismo , Retículo Endoplasmático/metabolismo , Transativadores , Sequência de Aminoácidos , Animais , Sequência de Bases , Sítios de Ligação , Caderinas/genética , Adesão Celular/fisiologia , Linhagem Celular , Membrana Celular/metabolismo , Polaridade Celular , Cloroquina/farmacologia , Citoplasma/metabolismo , Cães , Leupeptinas/farmacologia , Substâncias Macromoleculares , Dados de Sequência Molecular , Plasmídeos/genética , Ratos , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , beta Catenina
11.
Free Radic Biol Med ; 25(3): 329-39, 1998 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9680179

RESUMO

Although cardiac endogenous antioxidants have been reported to be oxidized and decreased by ischemia-reperfusion, little is known whether the changes in these antioxidants are correlated with each other in a systematic relationship. In this study, isolated rat hearts were subjected to various periods of ischemia-reperfusion using the Langendorff method, and the content and/or redox status of tissue antioxidants were analyzed. Significant losses in the tissue hydrophilic antioxidants, ascorbate, and glutathione were observed. These losses were dependent on the duration of the reperfusion period (between 0-40 min) but not of ischemia (20-60 min). Marked increases of dehydroascorbate and glutathione disulfide, the oxidized forms of ascorbate and glutathione, respectively, were found during reperfusion, but these changes were not observed during ischemia. These findings indicate that the tissue hydrophilic antioxidants are easily oxidized and may be the first line of antioxidant defenses during reperfusion. Lipophilic antioxidants, like ubiquinol 9 and vitamin E, were not decreased during ischemia-reperfusion using regular buffer; however, if oxidative stress was induced by addition of H2O2 to the buffer solution during reperfusion after 20 min of ischemia, decreases in both the hydrophilic and hydrophobic antioxidants were noticeable. With 100 microM H2O2, the tissue antioxidant decreases were ubiquinol 9 (39%), vitamin E (3%), glutathione (44%) and ascorbate (58%). Only with 500 microM H2O2 treatment were marked decreases in tissue vitamin E (65%) observed; this was associated with almost complete depletion of tissue ubiquinol 9 (95%). These results suggest that prior to the consumption of vitamin E, other antioxidants are depleted and that vitamin E may serve as the ultimate antioxidant, protecting the integrity of cellular membranes. Thus, in this work, cardiac antioxidants were demonstrated to change in a systematically organized relationship under ischemia-reperfusion. This graded utilization of antioxidants supports the redox based antioxidant network concept, found to be present in other biological systems.


Assuntos
Antioxidantes/metabolismo , Isquemia Miocárdica/metabolismo , Reperfusão Miocárdica , Animais , Ácido Ascórbico/metabolismo , Ácido Desidroascórbico/metabolismo , Glutationa/metabolismo , Dissulfeto de Glutationa/metabolismo , Peróxido de Hidrogênio/farmacologia , Técnicas In Vitro , Masculino , Ratos , Ratos Sprague-Dawley , Ubiquinona/análogos & derivados , Ubiquinona/metabolismo , Vitamina E/metabolismo
12.
J Biol Chem ; 272(47): 29652-62, 1997 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-9368032

RESUMO

Catenins are cytoplasmic proteins that were initially identified in a complex with cadherins, a superfamily of transmembrane glycoproteins important for cell adhesion in normal and disease states. We have used gel filtration to identify four complexes of catenins in extracts from normal and transformed epithelial cells. In normal Madin-Darby canine kidney epithelial cells, a significant fraction of alpha- and beta-catenin and plakoglobin co-elute with cadherin in a high molecular weight complex (complex I). A portion of alpha-catenin and the remainder of beta-catenin and plakoglobin co-elute in a high molecular weight complex that does not contain cadherin (complex II). The remainder of alpha-catenin elutes in a low molecular weight fraction (complex III). In extracts from two colon carcinoma cell lines, HCT116 and SW480, beta-catenin elutes in an additional low molecular weight pool (complex IV) not present in Madin-Darby canine kidney cell extracts. In two subclones derived from SW480 cells, SW-E8 and SW-R2, beta-catenin is distributed evenly between high and low molecular weight pools in SW-E8 cells, whereas it elutes primarily in the low molecular weight pool (complex IV) in SW-R2 cells. These changes in beta-catenin elution profiles correlate with an increase in transformed phenotype and decreased cell-cell adhesion in the SW-R2 cells.


Assuntos
Caderinas/fisiologia , Proteínas do Citoesqueleto/fisiologia , Transativadores , Animais , Transformação Celular Neoplásica , Cromatografia em Gel , Desmoplaquinas , Cães , Epitélio , Humanos , Peso Molecular , Células Tumorais Cultivadas , alfa Catenina , beta Catenina , gama Catenina
14.
Biochem Pharmacol ; 50(6): 839-43, 1995 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-7575646

RESUMO

The antioxidant properties of nitecapone, a catechol derivative and an inhibitor of catechol-O-methyltransferase, were reported recently. In the present study, the influence of nitecapone on isolated rat heart ischemia-reperfusion injury was investigated to elucidate its cardioprotective role. Nitecapone, administered in the perfusion buffer from the beginning of the pre-ischemic phase, significantly improved recovery of cardiac mechanical function, suppressed enzyme leakage in the coronary effluent, and minimized loss of ascorbate, compared with the control group. In rats fed a diet containing 4% ascorbate, myocardial ascorbate content in ascorbate-fed rats after ischemia-reperfusion was higher than that in control rats fed a normal diet without ischemia. However, supplemented rats did not show any beneficial effects on cardiac mechanical recovery or enzyme leakage, suggesting that maintenance of tissue ascorbate level is not the cause, but the result of the protective effects of nitecapone against cardiac ischemia-reperfusion injury. The iron-chelating effect of nitecapone was also tested. It was confirmed, using electron spin resonance, that 50 microM nitecapone chelates the same concentration of iron released from the heart into the coronary effluent. Hence, the iron-chelating ability of nitecapone may be responsible, at least in part, for its cardioprotective effects in ischemia-reperfusion injury.


Assuntos
Antioxidantes/farmacologia , Ácido Ascórbico/administração & dosagem , Inibidores de Catecol O-Metiltransferase , Catecóis/farmacologia , Inibidores Enzimáticos/farmacologia , Isquemia Miocárdica/tratamento farmacológico , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Pentanonas/farmacologia , Animais , Ácido Ascórbico/análise , Interações Medicamentosas , Depuradores de Radicais Livres/farmacologia , Quelantes de Ferro/farmacologia , Masculino , Ratos , Ratos Sprague-Dawley
15.
Proc Natl Acad Sci U S A ; 92(11): 5067-71, 1995 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-7761449

RESUMO

The cadherin-catenin complex is important for mediating homotypic, calcium-dependent cell-cell interactions in diverse tissue types. Although proteins of this complex have been identified, little is known about their interactions. Using a genetic assay in yeast and an in vitro protein-binding assay, we demonstrate that beta-catenin is the linker protein between E-cadherin and alpha-catenin and that E-cadherin does not bind directly to alpha-catenin. We show that a 25-amino acid sequence in the cytoplasmic domain of E-cadherin and the amino-terminal domain of alpha-catenin are independent binding sites for beta-catenin. In addition to beta-catenin and plakoglobin, another member of the armadillo family, p120 binds to E-cadherin. However, unlike beta-catenin, p120 does not bind alpha-catenin in vitro, although a complex of p120 and endogenous alpha-catenin could be immunoprecipitated from cell extracts. In vitro protein-binding assays using recombinant E-cadherin cytoplasmic domain and alpha-catenin revealed two catenin pools in cell lysates: an approximately 1000- to approximately 2000-kDa complex bound to E-cadherin and an approximately 220-kDa pool that did not contain E-cadherin. Only beta-catenin in the approximately 220-kDa pool bound exogenous E-cadherin. Delineation of these molecular linkages and the demonstration of separate pools of catenins in different cell lines provide a foundation for examining regulatory mechanisms involved in the assembly and function of the cadherin-catenin complex.


Assuntos
Caderinas/genética , Caderinas/metabolismo , Proteínas do Citoesqueleto/metabolismo , Transativadores , Adenocarcinoma , Sequência de Aminoácidos , Animais , Sequência de Bases , Sítios de Ligação , Caderinas/isolamento & purificação , Linhagem Celular , Clonagem Molecular , Neoplasias do Colo , Proteínas do Citoesqueleto/isolamento & purificação , Primers do DNA , Cães , Humanos , Metionina/metabolismo , Dados de Sequência Molecular , Reação em Cadeia da Polimerase/métodos , Ligação Proteica , Saccharomyces cerevisiae/metabolismo , Células Tumorais Cultivadas , alfa Catenina , beta Catenina
18.
J Bacteriol ; 169(6): 2889-92, 1987 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-3584076

RESUMO

Pseudomonas putida expresses plasmid-encoded enzymes and regulatory proteins for the dissimilation of naphthalene through salicylate and the alpha-keto acid pathway. A strain of P. putida (NAH:Tn5/G67) defective in salicylate hydroxylase (nahG) was assessed for its ability to oxidize 1,4-dichloronaphthalene. Washed cell suspensions were shown to accumulate 3,6-dichlorosalicylate, which, after further chemical treatment, yields the herbicide dicamba (3,6-dichloro-2-methoxybenzoate). However, the rate of dichlorosalicylate formation from dichloronaphthalene was less than 1% of the rate of salicylate formation from unsubstituted naphthalene.


Assuntos
Benzoatos/metabolismo , Dicamba/metabolismo , Naftalenos/metabolismo , Pseudomonas/metabolismo , Salicilatos/metabolismo , Cromatografia Líquida de Alta Pressão , Oxirredução , Pseudomonas/enzimologia , Análise Espectral
19.
J Bacteriol ; 169(6): 2762-8, 1987 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-3108241

RESUMO

An alkalophilic Bacillus sp., strain GX6638 (ATCC 53278), was isolated from soil and shown to produce a minimum of three alkaline proteases. The proteases were purified by ion-exchange chromatography and were distinguishable by their isoelectric point, molecular weight, and electrophoretic mobility. Two of the proteases, AS and HS, which exhibited the greatest alkaline and thermal stability, were characterized further. Protease HS had an apparent molecular weight of 36,000 and an isoelectric point of approximately 4.2, whereas protease AS had a molecular weight of 27,500 and an isoelectric point of 5.2. Both enzymes had optimal proteolytic activities over a broad pH range (pH 8 to 12) and exhibited temperature optima of 65 degrees C. Proteases HS and AS were further distinguished by their proteolytic activities, esterolytic activities, sensitivity to inhibitors, and their alkaline and thermal stability properties. Protease AS was extremely alkali stable, retaining 88% of initial activity at pH 12 over a 24-h incubation period at 25 degrees C; protease HS exhibited similar alkaline stability properties to pH 11. In addition, protease HS had exceptional thermal stability properties. At pH 9.5 (0.1 M CAPS buffer, 5 mM EDTA), the enzyme had a half-life of more than 200 min at 50 degrees C and 25 min at 60 degrees C. At pH above 9.5, protease HS readily lost enzymatic activity even in the presence of exogenously supplied Ca2+. In contrast, protease AS was more stable at pH above 9.5, and Ca2+ addition extended the half-life of the enzyme 10-fold at 60 degrees C. In contrast, protease AS was more stable at pH above 9.5, and Ca2+ addition extended the half-life of the enzyme 10-fold at 60 degrees C. The data presented here clearly indicate that these two alkaline proteases from Bacillus sp. strain GX6638 represent novel proteases that differ fundamentally from the proteases previously described for members of the genus Bacillus.


Assuntos
Bacillus/enzimologia , Endopeptidases/metabolismo , Bacillus/metabolismo , Endopeptidases/imunologia , Endopeptidases/isolamento & purificação , Fermentação , Temperatura Alta , Concentração de Íons de Hidrogênio , Imunodifusão , Peso Molecular , Inibidores de Proteases , Serina Endopeptidases
20.
J Biol Chem ; 262(9): 4280-3, 1987 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-3549729

RESUMO

Subtilisin GX, a serine protease from Bacillus species GX6644, has been crystallized by the vapor diffusion method using ammonium sulfate as the precipitant. The space group is P212121 with a = 38.4 A, b = 70.3 A, c = 73.5 A, and one molecule in the asymmetric unit. The crystals diffract to beyond 2.0-A resolution and are suitable for a high resolution three-dimensional structure determination. All x-ray data used in the preliminary crystallographic study were collected with an electronic area detector.


Assuntos
Bacillus/enzimologia , Subtilisinas , Sulfato de Amônio , Precipitação Química , Cristalização , Difusão , Difração de Raios X
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA