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1.
J Voice ; 34(2): 280-288, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30563730

RESUMO

INTRODUCTION: the aim of this study was to evaluate the correlation among dysphonic and vocal tract discomfort symptoms in patients who underwent empiric therapeutic trial with proton pump inhibitor (PPI) for a suspected laryngopharyngeal reflux (LPR). MATERIALS AND METHODS: A total of 34 patients with suspected LPR were enrolled in this study. All of them were evaluated using the reflux finding score, the reflux symptom Index (RSI), the vocal tract discomfort scale (VTDS), and the voice symptom scale (VoiSS) before and after the PPI treatment. RESULTS: A significant difference was found between pretreatment and posttreatment reflux finding score, RSI, VTDS, and VoiSS scores. Significant correlations among RSI, VTDS, and VoiSS before the PPI treatment were found. CONCLUSION: PPI treatment determined a significant improvement of symptoms related to dysphonia and vocal tract discomfort in patients with suspected LPR, in addition, significant correlations among the RSI, VTDS, and VoiSS scores were demonstrated thus suggesting that LPR might influence the response of questionnaires not specifically developed in order to assess the complains in LPR patient.


Assuntos
Disfonia/fisiopatologia , Refluxo Laringofaríngeo/tratamento farmacológico , Omeprazol/uso terapêutico , Inibidores da Bomba de Prótons/uso terapêutico , Prega Vocal/fisiopatologia , Qualidade da Voz , Adulto , Idoso , Idoso de 80 Anos ou mais , Disfonia/diagnóstico , Disfonia/etiologia , Feminino , Humanos , Refluxo Laringofaríngeo/complicações , Refluxo Laringofaríngeo/diagnóstico , Masculino , Pessoa de Meia-Idade , Medidas de Resultados Relatados pelo Paciente , Estudos Prospectivos , Recuperação de Função Fisiológica , Fatores de Tempo , Resultado do Tratamento , Adulto Jovem
2.
Beijing Da Xue Xue Bao Yi Xue Ban ; 46(4): 629-34, 2014 Aug 18.
Artigo em Chinês | MEDLINE | ID: mdl-25131483

RESUMO

OBJECTIVE: To prepare doxorubicin-loaded polyvinylalcohol-acrylic acid (PVA-AA) microspheres and evaluate properties of this chemoembolic agent. METHODS: PVA-AA microspheres were synthesized by inverse suspension polymerization method and then verified by infrared spectroscopy. drug loading (DL) and entrapment efficiency (EE%) were measured after doxorubicinwas loaded on PVA-AA microspheres. Their morphology and elasticity were investigated by optical microscope, environmental scanning electron microscope and texture analyzer, respectively. T-cell apparatus was used to evaluate the in vitro release behavior of doxorubicin-loaded microspheres.The external carotid of the rabbit was chosen as an embolization site to evaluate the in vivo embolic property of the microspheres. RESULTS: PVA-AA microspheres, which were transparent spheres,turned into red spheres after doxorubicin loading. DL of the microspheres was (20.56 ± 0.69)g/L and (23.25 ± 0.27) g/L,and EE% was 82.22% ± 2.76% and 93.00% ± 1.06% within 20 min and 6 h, respectively. The in vitro release results showed a significantly delayed release of the drug for 10.32% ± 0.47% after 24 h. The Young's modulus was (178.30 ± 12.33) kPa and (213.29 ± 15.61) kPa for blank microspheres and doxorubicin-loaded microspheres, respectively. Both blank microspheres and doxorubicin-loaded microspheres exhibited good elasticity. In vivo embolization showed that 0.3 mL of microspheres could produce distal embolic efficiency. CONCLUSION: The doxorubicin-loaded microspheres are expected to be a promising new chemoembolic agent.


Assuntos
Doxorrubicina/química , Portadores de Fármacos/química , Microesferas , Acrilatos , Animais , Elasticidade , Embolização Terapêutica , Álcool de Polivinil , Coelhos
3.
PLoS One ; 8(5): e63844, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23691104

RESUMO

Cell-free extracts isolated from colony biofilms of Actinobacillus pleuropneumoniae serotype 5 were found to inhibit biofilm formation by Staphylococcus aureus, S. epidermidis and Aggregatibacter actinomycetemcomitans, but not by A. pleuropneumoniae serotype 5 itself, in a 96-well microtiter plate assay. Physical and chemical analyses indicated that the antibiofilm activity in the extract was due to high-molecular-weight polysaccharide. Extracts isolated from a mutant strain deficient in the production of serotype 5 capsular polysaccharide did not exhibit antibiofilm activity. A plasmid harboring the serotype 5 capsule genes restored the antibiofilm activity in the mutant extract. Purified serotype 5 capsular polysaccharide also exhibited antibiofilm activity against S. aureus. A. pleuropneumoniae wild-type extracts did not inhibit S. aureus growth, but did inhibit S. aureus intercellular adhesion and binding of S. aureus cells to stainless steel surfaces. Furthermore, polystyrene surfaces coated with A. pleuropneumoniae wild-type extracts, but not with capsule-mutant extracts, resisted S. aureus biofilm formation. Our findings suggest that the A. pleuropneumoniae serotype 5 capsule inhibits cell-to-cell and cell-to-surface interactions of other bacteria. A. pleuropneumoniae serotype 5 capsular polysaccharide is one of a growing number of bacterial polysaccharides that exhibit broad-spectrum, nonbiocidal antibiofilm activity. Future studies on these antibiofilm polysaccharides may uncover novel functions for bacterial polysaccharides in nature, and may lead to the development of new classes of antibiofilm agents for industrial and clinical applications.


Assuntos
Actinobacillus pleuropneumoniae/química , Cápsulas Bacterianas/química , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Polissacarídeos Bacterianos/farmacologia , Comunicação Celular/efeitos dos fármacos , Peso Molecular , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/isolamento & purificação , Staphylococcus aureus/citologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/fisiologia
4.
mBio ; 3(4): e00198-12, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22851659

RESUMO

UNLABELLED: Subminimal inhibitory concentrations of antibiotics have been shown to induce bacterial biofilm formation. Few studies have investigated antibiotic-induced biofilm formation in Staphylococcus aureus, an important human pathogen. Our goal was to measure S. aureus biofilm formation in the presence of low levels of ß-lactam antibiotics. Fifteen phylogenetically diverse methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains were employed. Methicillin, ampicillin, amoxicillin, and cloxacillin were added to cultures at concentrations ranging from 0× to 1× MIC. Biofilm formation was measured in 96-well microtiter plates using a crystal violet binding assay. Autoaggregation was measured using a visual test tube settling assay. Extracellular DNA was quantitated using agarose gel electrophoresis. All four antibiotics induced biofilm formation in some strains. The amount of biofilm induction was as high as 10-fold and was inversely proportional to the amount of biofilm produced by the strain in the absence of antibiotics. MRSA strains of lineages USA300, USA400, and USA500 exhibited the highest levels of methicillin-induced biofilm induction. Biofilm formation induced by low-level methicillin was inhibited by DNase. Low-level methicillin also induced DNase-sensitive autoaggregation and extracellular DNA release. The biofilm induction phenotype was absent in a strain deficient in autolysin (atl). Our findings demonstrate that subminimal inhibitory concentrations of ß-lactam antibiotics significantly induce autolysin-dependent extracellular DNA release and biofilm formation in some strains of S. aureus. IMPORTANCE: The widespread use of antibiotics as growth promoters in agriculture may expose bacteria to low levels of the drugs. The aim of this study was to investigate the effects of low levels of antibiotics on bacterial autoaggregation and biofilm formation, two processes that have been shown to foster genetic exchange and antibiotic resistance. We found that low levels of ß-lactam antibiotics, a class commonly used in both clinical and agricultural settings, caused significant autoaggregation and biofilm formation by the important human pathogen Staphylococcus aureus. Both processes were dependent on cell lysis and release of DNA into the environment. The effect was most pronounced among multidrug-resistant strains known as methicillin-resistant S. aureus (MRSA). These results may shed light on the recalcitrance of some bacterial infections to antibiotic treatment in clinical settings and the evolution of antibiotic-resistant bacteria in agricultural settings.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , DNA Bacteriano/metabolismo , Espaço Extracelular/metabolismo , Staphylococcus aureus/fisiologia , beta-Lactamas/farmacologia , DNA Bacteriano/genética , Espaço Extracelular/efeitos dos fármacos , Espaço Extracelular/genética , Humanos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/fisiologia , Testes de Sensibilidade Microbiana , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética
5.
Int J Pharm ; 436(1-2): 527-35, 2012 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-22820132

RESUMO

A new embolic agent, poly(acrylic acid) microspheres (PMs), was synthesized and the cytocompatibility was proved by mouse L929 fibroblast cells. An analgesic drug, lidocaine, was loaded on the PMs to relief pain caused by embolization. PMs and lidocaine loaded microspheres (LMs) were characterized by investigating infrared spectrum, morphology, particle size, and equilibrium water contents (EWC). A series of tests were employed to evaluate the elasticity of PMs, LMs and Embosphere™, including once compression, twice compression, and stress relaxation test. The pressures of PMs and LMs passing through a catheter were measured on line by our new designed device. Drug release was studied with T-cell apparatus. The properties of PMs and LMs were proved to be suitable for embolization. Both PMs and LMs in this study might be potential embolic agents in the future.


Assuntos
Resinas Acrílicas/química , Anestésicos Locais/química , Portadores de Fármacos/química , Lidocaína/química , Resinas Acrílicas/administração & dosagem , Anestésicos Locais/administração & dosagem , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Força Compressiva , Portadores de Fármacos/administração & dosagem , Elasticidade , Lidocaína/administração & dosagem , Camundongos , Microesferas , Embolização da Artéria Uterina
6.
J Antibiot (Tokyo) ; 65(2): 73-7, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22167157

RESUMO

Extracellular DNA is an adhesive component of staphylococcal biofilms. The aim of this study was to evaluate the antibiofilm activity of recombinant human DNase I (rhDNase) against Staphylococcus aureus and Staphylococcus epidermidis. Using a 96-well microtiter plate crystal-violet binding assay, we found that biofilm formation by S. aureus was efficiently inhibited by rhDNase at 1-4 µg l⁻¹, and preformed S. aureus biofilms were efficiently detached in 2 min by rhDNase at 1 mg l⁻¹. Pretreatment of S. aureus biofilms for 10 min with 10 mg l⁻¹ rhDNase increased their sensitivity to biocide killing by 4-5 log units. rhDNase at 10 mg l⁻¹ significantly inhibited biofilm formation by S. epidermidis in medium supplemented with sub-MICs of antibiotics. We also found that rhDNase significantly increased the survival of S. aureus-infected Caenorhabditis elegans nematodes treated with tobramycin compared with nematodes treated with tobramycin alone. We concluded that rhDNase exhibits potent antibiofilm and antimicrobial-sensitizing activities against S. aureus and S. epidermidis at clinically achievable concentrations. rhDNase, either alone or in combination with antimicrobial agents, may have applications in treating or preventing staphylococcal biofilm-related infections.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Desoxirribonuclease I/farmacologia , Recombinação Genética , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus epidermidis/efeitos dos fármacos , Animais , Biofilmes/crescimento & desenvolvimento , Caenorhabditis elegans/efeitos dos fármacos , Caenorhabditis elegans/microbiologia , Desoxirribonuclease I/genética , Proteínas de Escherichia coli/metabolismo , Proteínas de Escherichia coli/farmacologia , Humanos , Testes de Sensibilidade Microbiana , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus epidermidis/crescimento & desenvolvimento , Tobramicina/farmacologia
7.
Microb Pathog ; 46(4): 207-13, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19490830

RESUMO

Respiratory infections caused by nontypeable Haemophilus influenzae (NTHi) are a major medical problem. Evidence suggests that the ability to form biofilms on mucosal surfaces may play a role in NTHi pathogenesis. However, the factors that contribute to NTHi biofilm cohesion remain largely unknown. In this study we investigated the biofilm growth and detachment phenotypes of eight NTHi clinical strains in vitro. We found that the majority of strains produced biofilms within 6h when cultured statically in tubes. Biofilm formation was inhibited when culture medium was supplemented with proteinase K or DNase I. Both enzymes also caused significant detachment of pre-formed NTHi biofilms. These findings indicate that both proteinaceous adhesins and extracellular DNA contribute to NTHi biofilm cohesion. Treatment of NTHi biofilms cultured in centrifugal filter devices with DNase I, but not with proteinase K, caused a significant decrease in fluid convection through the biofilms. These results suggest that extracellular DNA is the major volumetric component of the NTHi biofilm matrix. Mechanical or enzymatic disruption of NTHi biofilms cultured in microtiter plates significantly increased their sensitivity to killing by SDS, cetylpyridinium chloride, chlorhexidine gluconate, povidone iodine and sodium hypochlorite. These findings indicate that biocide resistance in NTHi biofilms is mediated to a large part by the cohesive and protective properties of the biofilm matrix. Understanding the mechanisms of biofilm cohesion and biocide resistance in NTHi biofilms may lead to new methods for treating NTHi-associated infections.


Assuntos
Aderência Bacteriana , Biofilmes/efeitos dos fármacos , Desinfetantes/farmacologia , Haemophilus influenzae/efeitos dos fármacos , Haemophilus influenzae/fisiologia , Adesinas Bacterianas/metabolismo , Biofilmes/crescimento & desenvolvimento , Cetilpiridínio/farmacologia , Clorexidina/análogos & derivados , Clorexidina/farmacologia , Contagem de Colônia Microbiana , DNA Bacteriano/metabolismo , Humanos , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Povidona-Iodo/farmacologia , Dodecilsulfato de Sódio/farmacologia , Hipoclorito de Sódio/farmacologia
8.
Dig Liver Dis ; 40(12): 936-43, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18468499

RESUMO

BACKGROUND: Current guidelines recommend beta-blockers for primary prevention of variceal haemorrhage in cirrhotic patients, and band ligation for patients with contraindications or intolerance to beta-blockers. However, it has been suggested that these patients may respond poorly to band ligation. AIM: We evaluated the usefulness of a strategy in which band ligation was used to treat patients with contraindications or intolerance and patients not responding to beta-blockers identified by hepatic vein pressure gradient measurement. Haemodynamic responders and patients refusing hepatic vein pressure gradient measurement were given long-term beta-blockers. METHODS: One hundred and thirty-five consecutive patients with high-risk oesophageal varices and no prior bleeding were enrolled. Twenty-five patients with contraindications (group A), 26 with intolerance to beta-blockers (group B) and 25 showing a poor haemodynamic response (Group C) underwent band ligation. Twenty-two haemodynamic responders (Group D) and 37 refusing hepatic vein pressure gradient measurement (Group E) were treated with beta-blockers. RESULTS: Median follow-up was 32 months. 12/135 patients (8.9%) bled: 3/25 (12%) in group A, 1/26 (3.8%) in group B, 0/25 (0%) in group C, 0/22 (0%) in group D and 8/37 (22.2%) in group E. Mortality was 8/135 (5.9%). CONCLUSIONS: Patients with contraindications, intolerance or not responding to beta-blockers treated with band ligation achieve protection from variceal bleeding comparable to that of good responders to beta-blockers.


Assuntos
Endoscopia , Varizes Esofágicas e Gástricas/cirurgia , Hemorragia Gastrointestinal/prevenção & controle , Cirrose Hepática/complicações , Antagonistas Adrenérgicos beta/efeitos adversos , Contraindicações , Varizes Esofágicas e Gástricas/tratamento farmacológico , Varizes Esofágicas e Gástricas/etiologia , Feminino , Seguimentos , Humanos , Ligadura , Masculino , Pessoa de Meia-Idade
9.
Artigo em Inglês | MEDLINE | ID: mdl-18346684

RESUMO

Variceal bleeding is one of the most severe complications of portal hypertension related to liver cirrhosis. Primary prophylaxis is considered mandatory in patients with cirrhosis and high-risk oesophageal varices, and once varices have bled, every effort should be made to arrest the haemorrhage and prevent further bleeding episodes. In acute variceal bleeding, vasoactive drugs that lower portal pressure should be started even before endoscopy, and should be maintained for up to 5 days. The choice of vasoactive drug should be made according to local resources. Terlipressin, somatostatin and octreotide can be used; vasopressin plus transdermal nitroglycerin may be used if no other drug is available. In variceal bleeding, antibiotic therapy is also mandatory. In primary and secondary prophylaxis, beta-blockers are the mainstay of therapy. In secondary prophylaxis (but not in primary prophylaxis) these drugs can be combined with organic nitrates.


Assuntos
Varizes Esofágicas e Gástricas/tratamento farmacológico , Vasoconstritores/uso terapêutico , Doença Aguda , Antagonistas Adrenérgicos beta/uso terapêutico , Antibioticoprofilaxia , Quimioterapia Combinada , Varizes Esofágicas e Gástricas/etiologia , Varizes Esofágicas e Gástricas/prevenção & controle , Humanos , Hipertensão Portal/complicações , Cirrose Hepática/complicações , Lipressina/análogos & derivados , Lipressina/uso terapêutico , Octreotida/uso terapêutico , Somatostatina/uso terapêutico , Terlipressina , Vasopressinas/uso terapêutico
10.
Dig Liver Dis ; 40(11): 874-81, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18329968

RESUMO

BACKGROUND AND AIM: Variceal bleeding carries a high-mortality rate in patients with liver cirrhosis. Since coagulation and fibrinolysis are abnormal in these patients we evaluated whether or not abnormalities of these haemostasis systems were independently related to mortality. METHODS: Global coagulation, coagulation activation and fibrinolysis measurements were performed in 43 cirrhotics bleeding from esophageal varices at baseline and during follow-up and in 43 non-bleeding cirrhotic patients at baseline only. RESULTS: Baseline measurements of coagulation activation and fibrinolysis were more impaired in bleeders. In bleeders, prothrombin time, tissue type plasminogen activator antigen and D-dimer plasma levels were persistently more abnormal in patients who died. High-D-dimer, infection, Child-Pugh C class and MELD score >or=17 were the significant predictors of death at univariate analysis. Two different multivariate analyses to assess the independent prognostic value of these variables, one including the Child-Pugh class, the other including MELD, were performed. Independent predictors of death were high-D-dimer and infection, but not Child-Pugh class, in the former; MELD and infection, but not D-dimer, in the latter. CONCLUSIONS: Beside infection, high-D-dimer is a stronger predictor of death as compared to Child-Pugh C class, but not to a MELD score >or=17.


Assuntos
Varizes Esofágicas e Gástricas/sangue , Produtos de Degradação da Fibrina e do Fibrinogênio/análise , Hemorragia Gastrointestinal/mortalidade , Cirrose Hepática/sangue , Adulto , Idoso , Idoso de 80 Anos ou mais , Análise de Variância , Biomarcadores/sangue , Estudos de Casos e Controles , Causas de Morte , Ensaio de Imunoadsorção Enzimática , Varizes Esofágicas e Gástricas/diagnóstico , Varizes Esofágicas e Gástricas/mortalidade , Feminino , Seguimentos , Hemorragia Gastrointestinal/sangue , Hemorragia Gastrointestinal/etiologia , Humanos , Modelos Lineares , Cirrose Hepática/diagnóstico , Cirrose Hepática/mortalidade , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Probabilidade , Valores de Referência , Estudos Retrospectivos , Sensibilidade e Especificidade , Análise de Sobrevida
11.
Dig Liver Dis ; 40(5): 312-7, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18294933

RESUMO

Currently, oesophago-gastroduodenoscopy is the standard method to diagnose the presence of oesophago-gastric varices and to estimate the risk of bleeding. It is recommended that all patients undergo endoscopic screening for varices at the time when cirrhosis is diagnosed. After screening endoscopy, patients with medium or large varices should be treated to prevent bleeding, while all other patients should undergo periodic surveillance endoscopy. However, at a given point in time a variable proportion of patients will not have varices, since the prevalence of varices is variable. Thus, screening all cirrhotic patients with endoscopy to detect the presence of varices implies a number of unnecessary endoscopies. In recent years a wealth of new methods have been proposed as alternatives to conventional oesophago-gastroduodenoscopy for the non-invasive or minimally invasive diagnosis of oesophageal varices. Three of these methods (the platelet count/spleen diameter ratio, Fibrotest and Fibroscan) are truly non-invasive. Of these, the former is promising and needs a proper validation, Fibrotest appears to be insufficiently precise, while Fibroscan needs further evaluation. Multidetector CT oesophagography and capsule endoscopy are not entirely "non-invasive", since the first requires air insufflation into the oesophagus via an orally passed tube, and the latter requires swallowing the capsule. Multidetector CT oesophagography is promising, but needs further evaluation; capsule endoscopy is safe and reliable and might be proposed as an alternative to oesophago-gastroduodenoscopy in patients unable or unwilling to undergo oesophago-gastroduodenoscopy.


Assuntos
Endoscopia por Cápsula/métodos , Endoscopia Gastrointestinal/métodos , Hipertensão Portal/diagnóstico , Hipertensão Portal/fisiopatologia , Tomografia Computadorizada por Raios X/métodos , Diagnóstico Diferencial , Técnicas de Imagem por Elasticidade/métodos , Varizes Esofágicas e Gástricas/diagnóstico , Varizes Esofágicas e Gástricas/etiologia , Varizes Esofágicas e Gástricas/fisiopatologia , Humanos , Hipertensão Portal/complicações , Índice de Gravidade de Doença
12.
Appl Environ Microbiol ; 74(2): 470-6, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18039822

RESUMO

Staphylococcus aureus and Staphylococcus epidermidis are major human pathogens of increasing importance due to the dissemination of antibiotic-resistant strains. Evidence suggests that the ability to form matrix-encased biofilms contributes to the pathogenesis of S. aureus and S. epidermidis. In this study, we investigated the functions of two staphylococcal biofilm matrix polymers: poly-N-acetylglucosamine surface polysaccharide (PNAG) and extracellular DNA (ecDNA). We measured the ability of a PNAG-degrading enzyme (dispersin B) and DNase I to inhibit biofilm formation, detach preformed biofilms, and sensitize biofilms to killing by the cationic detergent cetylpyridinium chloride (CPC) in a 96-well microtiter plate assay. When added to growth medium, both dispersin B and DNase I inhibited biofilm formation by both S. aureus and S. epidermidis. Dispersin B detached preformed S. epidermidis biofilms but not S. aureus biofilms, whereas DNase I detached S. aureus biofilms but not S. epidermidis biofilms. Similarly, dispersin B sensitized S. epidermidis biofilms to CPC killing, whereas DNase I sensitized S. aureus biofilms to CPC killing. We concluded that PNAG and ecDNA play fundamentally different structural roles in S. aureus and S. epidermidis biofilms.


Assuntos
Acetilglucosamina/metabolismo , Biofilmes/crescimento & desenvolvimento , DNA Bacteriano/metabolismo , Staphylococcus aureus/metabolismo , Staphylococcus epidermidis/metabolismo , Acetilglucosamina/fisiologia , Proteínas de Bactérias/metabolismo , Biofilmes/efeitos dos fármacos , Cetilpiridínio/farmacologia , Desoxirribonuclease I/metabolismo , Modelos Biológicos , Polissacarídeos Bacterianos/metabolismo , Polissacarídeos Bacterianos/fisiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética , Staphylococcus epidermidis/efeitos dos fármacos , Staphylococcus epidermidis/genética
13.
Microb Pathog ; 44(1): 52-60, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17851029

RESUMO

Clinical isolates of the periodontopathogen Aggregatibacter actinomycetemcomitans form matrix-encased biofilms on abiotic surfaces in vitro. A major component of the A. actinomycetemcomitans biofilm matrix is poly-beta-1,6-N-acetyl-d-glucosamine (PGA), a hexosamine-containing polysaccharide that mediates intercellular adhesion. In this report, we describe studies on the purification, structure, genetics and function of A. actinomycetemcomitans PGA. We found that PGA was very tightly attached to A. actinomycetemcomitans biofilm cells and could be efficiently separated from the cells only by phenol extraction. A. actinomycetemcomitans PGA copurified with LPS on a gel filtration column. (1)H NMR spectra of purified A. actinomycetemcomitans PGA were consistent with a structure containing a linear chain of N-acetyl-d-glucosamine residues in beta(1,6) linkage. Genetic analyses indicated that all four genes of the pgaABCD locus were required for PGA production in A. actinomycetemcomitans. PGA mutant strains still formed biofilms in vitro. Unlike wild-type biofilms, however, PGA mutant biofilms were sensitive to detachment by DNase I and proteinase K. Treatment of A. actinomycetemcomitans biofilms with the PGA-hydrolyzing enzyme dispersin B made them 3 log units more sensitive to killing by the cationic detergent cetylpyridinium chloride. Our findings suggest that PGA, extracellular DNA and proteinaceous adhesins all contribute to the structural integrity of the A. actinomycetemcomitans biofilm matrix.


Assuntos
Acetilglucosamina/genética , Acetilglucosamina/fisiologia , Biofilmes/crescimento & desenvolvimento , Pasteurellaceae/crescimento & desenvolvimento , Pasteurellaceae/genética , Acetilglucosamina/química , Aderência Bacteriana/efeitos dos fármacos , Aderência Bacteriana/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/fisiologia , Biofilmes/efeitos dos fármacos , Cetilpiridínio/farmacologia , Vermelho Congo/análise , Vermelho Congo/metabolismo , Primers do DNA/química , Detergentes/farmacologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Ordem dos Genes , Teste de Complementação Genética , Glicosídeo Hidrolases/farmacologia , Humanos , Espectroscopia de Ressonância Magnética , Mutação/fisiologia , Pasteurellaceae/efeitos dos fármacos , Reação em Cadeia da Polimerase , Trítio/análise
14.
FEBS J ; 274(22): 5987-99, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17949435

RESUMO

Dispersin B (DspB), a family 20 beta-hexosaminidase from the oral pathogen Aggregatibacter actinomycetemcomitans, cleaves beta(1,6)-linked N-acetylglucosamine polymer. In order to understand the substrate specificity of DspB, we have undertaken to characterize several conserved and nonconserved residues in the vicinity of the active site. The active sites of DspB and other family 20 hexosaminidases possess three highly conserved acidic residues, several aromatic residues and an arginine at subsite -1. These residues were mutated using site-directed mutagenesis and characterized for their enzyme activity. Our results show that a highly conserved acid pair in beta-hexosaminidases D183 and E184, and E332 play a critical role in the hydrolysis of the substrates. pH activity profile analysis showed a shift to a higher pH (6.8) in the optimal activity for the E184Q mutant, suggesting that this residue might act as the acid/base catalyst. The reduction in k(cat) observed for Y187A and Y278A mutants suggests that the Y187 residue (unique to DspB) located on a loop might play a role in substrate specificity and be a part of subsite +1, whereas the hydrogen-bond interaction between Y278A and the N-acetyl group might help to stabilize the transition state. Mutation of W237 and W330 residues abolished hydrolytic activity completely suggesting that alteration at these positions might collapse the binding pocket for the N-acetyl group. Mutation of the conserved R27 residue (to R27A or R27K) also caused significant reduction in k(cat) suggesting that R27 might be involved in stabilization of the transition state. From these results, we conclude that in DspB, and possibly in other structurally similar family 20 hydrolases, some residues at the active site assist in orienting the N-acetyl group to participate in the substrate-assisted mechanism, whereas other residues such as R27 and E332 assist in holding the terminal N-acetylglucosamine during the hydrolysis.


Assuntos
Aggregatibacter actinomycetemcomitans/enzimologia , Proteínas de Bactérias/metabolismo , Biofilmes , Glicosídeo Hidrolases/metabolismo , beta-N-Acetil-Hexosaminidases/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Sequência de Bases , Sítios de Ligação , Primers do DNA , Glicosídeo Hidrolases/química , Glicosídeo Hidrolases/genética , Concentração de Íons de Hidrogênio , Hidrólise , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Homologia de Sequência de Aminoácidos , Especificidade por Substrato , beta-N-Acetil-Hexosaminidases/química , beta-N-Acetil-Hexosaminidases/genética
15.
Microb Pathog ; 43(1): 1-9, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17412552

RESUMO

Most field isolates of the swine pathogen Actinobacillus pleuropneumoniae form tenacious biofilms on abiotic surfaces in vitro. We purified matrix polysaccharides from biofilms produced by A. pleuropneumoniae field isolates IA1 and IA5 (serotypes 1 and 5, respectively), and determined their chemical structures by using NMR spectroscopy. Both strains produced matrix polysaccharides consisting of linear chains of N-acetyl-D-glucosamine (GlcNAc) residues in beta(1,6) linkage (poly-beta-1,6-GlcNAc or PGA). A small percentage of the GlcNAc residues in each polysaccharide were N-deacetylated. These structures were nearly identical to those of biofilm matrix polysaccharides produced by Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis. PCR analyses indicated that a gene encoding the PGA-specific glycoside transferase enzyme PgaC was present on the chromosome of 15 out of 15 A. pleuropneumoniae reference strains (serotypes 1-12) and 76 out of 77 A. pleuropneumoniae field isolates (serotypes 1, 5 and 7). A pgaC mutant of strain IA5 failed to form biofilms in vitro, as did wild-type strains IA1 and IA5 when grown in broth supplemented with the PGA-hydrolyzing enzyme dispersin B. Treatment of IA5 biofilms with dispersin B rendered them more sensitive to killing by ampicillin. Our findings suggest that PGA functions as a major biofilm adhesin in A. pleuropneumoniae. Biofilm formation may have relevance to the colonization and pathogenesis of A. pleuropneumoniae in pigs.


Assuntos
Actinobacillus pleuropneumoniae/fisiologia , Adesinas Bacterianas/química , Biofilmes/crescimento & desenvolvimento , Resistência a Medicamentos , Galactanos/metabolismo , Polissacarídeos Bacterianos/química , Actinobacillus pleuropneumoniae/efeitos dos fármacos , Adesinas Bacterianas/efeitos dos fármacos , Adesinas Bacterianas/isolamento & purificação , Adesinas Bacterianas/fisiologia , Ampicilina/farmacologia , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Cromossomos Bacterianos , Galactanos/química , Deleção de Genes , Glicosiltransferases/genética , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Polissacarídeos Bacterianos/isolamento & purificação , Polissacarídeos Bacterianos/fisiologia
16.
Waste Manag ; 25(2): 215-20, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15737721

RESUMO

The presence of LiCoO(2) and LiCo(x)Ni((1-x))O(2) in the cathodic material of Li-ion and Li-polymer batteries has stimulated the recovery of Co and Ni by hydrometallurgical processes. In particular, the two metals were separated by SX method and then recovered by electrochemical (galvanostatic and potentiostatic) processes. The metallic Ni has been electrowon at 250 A/m(2), pH 3-3.2 and 50 degrees C, with 87% current efficiency and 2.96 kWh/kg specific energy consumption. Potentiostatic electrolysis produces a very poor Ni powder in about 1 h with current efficiency changing from 70% to 45% depending on Ni concentration in the electrolyte. Current efficiency of 96% and specific energy consumption of 2.8 kWh/kg were obtained for Co at 250 A/m(2), pH 4-4.2 and 50 degrees C, by using a solution containing manganese and (NH(4))(2)SO(4). The Co powder, produced in potentiostatic conditions (-0.9 V vs. SCE, pH 4, room temperature) appears particularly suitable for Co recycling as cobaltite in new batteries.


Assuntos
Conservação de Recursos Energéticos , Níquel/isolamento & purificação , Cobalto/isolamento & purificação , Eletroquímica , Fontes Geradoras de Energia , Lítio
17.
Aliment Pharmacol Ther ; 20 Suppl 3: 8-15; discussion 16-7, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15335392

RESUMO

Gastro-oesophageal variceal bleeding is the last step in a chain of events that starts with an increased portal pressure, and is followed by the formation and progressive dilatation of gastro-oesophageal varices. When the tension of the thin wall of the varices exceeds its elastic limit, the varices rupture and bleed. Wall tension is directly proportional to variceal pressure (which is a function of portal pressure) and variceal radius, and inversely related to the thickness of the variceal wall. The above facts explain why a high portal pressure (usually determined by the hepatic venous pressure gradient, or HVPG) and the presence at endoscopy of large varices with red wheals, red spots or diffuse redness on the varices (signalling a reduced wall thickness) correlate with the risk of bleeding.


Assuntos
Varizes Esofágicas e Gástricas/etiologia , Hemorragia Gastrointestinal/etiologia , Hipertensão Portal/complicações , Pressão na Veia Porta/fisiologia , Infecções Bacterianas/complicações , Transtornos da Coagulação Sanguínea/complicações , Transfusão de Sangue/métodos , Varizes Esofágicas e Gástricas/fisiopatologia , Hemorragia Gastrointestinal/fisiopatologia , Hemorragia Gastrointestinal/terapia , Humanos , Hipertensão Portal/fisiopatologia , Falência Hepática/complicações , Fatores de Risco
18.
Dig Liver Dis ; 36(12): 787-98, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15646423

RESUMO

Prevention of the first variceal haemorrhage should start when the patients have developed medium-sized to large varices. Non-selective beta-blockers and band ligation are equally effective in preventing the first bleeding episode. Rubber band ligation is the first choice for patients with contraindications or intolerance to beta-blockers. Treatment of acute bleeding should aim at controlling bleeding and preventing early rebleeding and complications, especially infections. Combined endoscopic (band ligation or sclerotherapy) and pharmacological treatment with vasoactive drugs can control bleeding in up to 90% of patients. Antibiotic prophylaxis is an integral part of the treatment of acute variceal haemorrhage, and must be started as soon as possible. Emergency transjugular intrahepatic portosystemic stent shunt (TIPS) is the standard rescue therapy for patients failing combined endoscopic and pharmacological treatment. All patients who survive a variceal bleed should be treated with beta-blockers or band ligation to prevent rebleeding. All patients in whom bleeding cannot be controlled or who continue to rebleed can be treated with salvage TIPS or, in selected cases, with surgical shunts. Liver transplantation should be considered for patients with severe liver insufficiency in which first-line treatments fail.


Assuntos
Hipertensão Portal/diagnóstico , Hipertensão Portal/terapia , Endoscopia Gastrointestinal , Hemorragia Gastrointestinal/etiologia , Hemorragia Gastrointestinal/prevenção & controle , Veias Hepáticas/fisiopatologia , Humanos , Hipertensão Portal/complicações , Ligadura , Cirrose Hepática/complicações , Seleção de Pacientes , Retratamento , Escleroterapia , Falha de Tratamento
19.
Acta Gastroenterol Belg ; 67(4): 334-43; discussion 344-5, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15727078

RESUMO

Prevention of the first variceal haemorrhage should start when the patients have developed medium sized to large varices. Non-selective beta-blockers are the first-line treatment; band ligation is roughly equivalent to beta-blockers and is the first choice for patients with contraindications or intolerance to beta-blockers. Treatment of acute bleeding should aim at controlling bleeding and preventing early rebleeding and complications, especially infections. Combined endoscopic and pharmacological treatment with vasoactive drugs can control bleeding in up to 90% of patients. All patients who survive a variceal bleed should be treated with beta-blockers or band ligation to prevent rebleeding. All patients in whom bleeding cannot be controlled or who continue to rebleed can be treated with salvage TIPS or, in selected cases, with surgical shunts. Liver transplantation should be considered for patients with severe liver insufficiency in which first-line treatments fail.


Assuntos
Hipertensão Portal/terapia , Doença Aguda , Antagonistas Adrenérgicos beta/uso terapêutico , Varizes Esofágicas e Gástricas/prevenção & controle , Hemorragia Gastrointestinal/prevenção & controle , Hemorragia Gastrointestinal/cirurgia , Humanos , Hipertensão Portal/tratamento farmacológico , Hipertensão Portal/prevenção & controle , Ligadura , Derivação Portossistêmica Transjugular Intra-Hepática , Prevenção Secundária , Vasodilatadores/uso terapêutico
20.
Recenti Prog Med ; 92(12): 735-40, 2001 Dec.
Artigo em Italiano | MEDLINE | ID: mdl-11822093

RESUMO

Portal hypertensive gastropathy (PHG) is characterized by changes in the endoscopic appearance of the gastric mucosa, specific for portal hypertension. The identification of the elementary lesions of PHG allowed the development of a reproducible classification, defining mild and severe pictures, and the execution of a natural history study. This study showed a 80% overall prevalence of PHG in patient with cirrhosis of the liver and a correlation between duration of the disease and development of PHG. PHG has often been shown to be a fluctuating condition, thus suggesting that its pathophysiology is not only related to portal hypertension, but also to other, yet unknown, factors. Bleeding from PHG did not occur in patients with a recent diagnosis of liver cirrhosis. Acute and chronic bleeding occurred in 2.5% and 12% of patients, respectively. The death rate from acute PHG bleeding was lower (12.5%) than the death rate of variceal bleeding (39.1%). Vasoactive drugs can be used in the treatment of acute PHG bleeding. For chronic bleeding, non selective 13-blockers and, if needed, iron, are the treatment of choice. TIPS or surgical portosystemic shunt may be considered for acute or chronic PHG bleeding, if medical treatment fails. Clinical controlled trials are needed to evaluate the efficacy of these or other treatments.


Assuntos
Hipertensão Portal/complicações , Cirrose Hepática/complicações , Gastropatias/etiologia , Doença Aguda , Varizes Esofágicas e Gástricas/complicações , Varizes Esofágicas e Gástricas/etiologia , Varizes Esofágicas e Gástricas/terapia , Feminino , Mucosa Gástrica/patologia , Hemorragia Gastrointestinal/etiologia , Hemorragia Gastrointestinal/terapia , Humanos , Hipertensão Portal/terapia , Masculino , Pessoa de Meia-Idade , Derivação Portossistêmica Transjugular Intra-Hepática , Escleroterapia , Gastropatias/patologia
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