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1.
Ann Oncol ; 32(7): 881-895, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33894335

RESUMO

BACKGROUND: In the phase III KEYNOTE-189 study (NCT02578680), pembrolizumab plus pemetrexed and platinum-based chemotherapy (pemetrexed-platinum) significantly improved overall survival (OS) and progression-free survival (PFS) in patients with previously untreated metastatic nonsquamous non-small-cell lung cancer (NSCLC) versus placebo plus pemetrexed-platinum. We report updated efficacy outcomes from the protocol-specified final analysis, including outcomes in patients who crossed over to pembrolizumab from pemetrexed-platinum and in patients who completed 35 cycles (∼2 years) of pembrolizumab. PATIENTS AND METHODS: Eligible patients were randomized 2 : 1 to receive pembrolizumab 200 mg (n = 410) or placebo (n = 206) every 3 weeks (for up to 35 cycles, ∼2 years) plus four cycles of pemetrexed (500 mg/m2) and investigators' choice of cisplatin (75 mg/m2) or carboplatin (area under the curve 5 mg·min/ml) every 3 weeks, followed by pemetrexed until progression. Patients assigned to placebo plus pemetrexed-platinum could cross over to pembrolizumab upon progression if eligibility criteria were met. The primary endpoints were OS and PFS. RESULTS: After a median follow-up of 31.0 months, pembrolizumab plus pemetrexed-platinum continued to improve OS [hazard ratio (HR), 0.56; 95% confidence interval (CI), 0.46-0.69] and PFS (HR, 0.49; 95% CI, 0.41-0.59) over placebo plus pemetrexed-platinum regardless of programmed death-ligand 1 expression. Objective response rate (ORR) (48.3% versus 19.9%) and time to second/subsequent tumor progression on next-line treatment (PFS2; HR, 0.50; 95% CI, 0.41-0.61) were improved in patients who received pembrolizumab plus pemetrexed-platinum. Eighty-four patients (40.8%) from the placebo plus pemetrexed-platinum group crossed over to pembrolizumab on-study. Grade 3-5 adverse events occurred in 72.1% of patients receiving pembrolizumab plus pemetrexed-platinum and 66.8% of patients receiving placebo plus pemetrexed-platinum. Fifty-six patients completed 35 cycles (∼2 years) of pembrolizumab; ORR was 85.7% and 53 (94.6%) were alive at data cut-off. CONCLUSIONS: Pembrolizumab plus pemetrexed-platinum continued to show improved efficacy outcomes compared with placebo plus pemetrexed-platinum, with manageable toxicity. These findings support first-line pembrolizumab plus pemetrexed-platinum in patients with previously untreated metastatic nonsquamous NSCLC.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Anticorpos Monoclonais Humanizados , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Pemetrexede/uso terapêutico , Platina/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como Assunto
2.
Int J Stroke ; 16(4): 396-405, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-32640881

RESUMO

BACKGROUND AND AIMS: Poststroke shoulder pain is a common complication. We aimed to investigate the prevalence of poststroke shoulder pain, with attention to the neuropathic component, and the relationship between poststroke shoulder pain and upper limb improvement in motor function, strength, disability, and quality of life after upper limb rehabilitation. METHODS: This is a secondary analysis of a multicenter randomized controlled trial to compare upper limb conventional or robotic rehabilitation on 224 patients enrolled in eight rehabilitation centers. We assessed poststroke shoulder pain (using the Numerical Rating Scale and the Douleur Neuropathique 4), and upper limb motor function, strength, disability, and quality of life at baseline (T0), after 30 rehabilitation sessions (T1), and three months after the end of rehabilitation (T2). RESULTS: A moderate/severe poststroke shoulder pain was reported by 28.9% of patients, while 19.6% of them showed a neuropathic component. At T0, the intensity of pain was higher in women and in patients with neglect syndrome, positively correlated with the time since stroke and disability and negatively correlated with motor function, strength, and the physical aspects of the quality of life.Moderate/severe pain and neuropathic component significantly reduced after both treatments and this reduction was maintained at T2. Finally, the intensity of pain at baseline was negatively correlated with the improvement of upper limb motor function. CONCLUSIONS: Poststroke shoulder pain negatively impact on motor performance, strength, disability, and physical aspects of the quality of life as well as on upper limb motor recovery; however, it can be reduced after a robotic or a conventional rehabilitation. Therefore, we suggest considering poststroke shoulder pain when planning the rehabilitation intervention.


Assuntos
Procedimentos Cirúrgicos Robóticos , Reabilitação do Acidente Vascular Cerebral , Acidente Vascular Cerebral , Feminino , Humanos , Qualidade de Vida , Recuperação de Função Fisiológica , Dor de Ombro/epidemiologia , Dor de Ombro/etiologia , Acidente Vascular Cerebral/complicações , Resultado do Tratamento , Extremidade Superior
3.
Dalton Trans ; 49(10): 3333-3340, 2020 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-32101190

RESUMO

Integrating graphene as an inorganic nanostructure within a hydrogel matrix enables the creation of a unique hybrid composite combining the peculiar chemical and physical properties of graphene with the high porosity and stability of hydrogels as for example agarose gel. As a consequence, the resulting material forms a double-network system providing advantages deriving from both the components. In this study, we present the synthesis of novel magnetic porous agarose-based graphene oxide microbeads for the adsorption and separation of positively charged aromatic molecules. The hydrogel-based graphene oxide beads revealed an ultrafast adsorption kinetics for positively charged aromatic dyes. We tested this material for the purification of fluorescent-tagged biomolecules. In addition, reduced graphene oxide microbeads were decorated with palladium nanoparticles, showing a high catalytic activity towards the reduction of dyes by sodium borohydride. Our results show that magnetic agarose based graphene microbeads with enhanced physical-chemical properties can be used for several biochemical applications.

4.
Nanotechnology ; 30(25): 255601, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-30836334

RESUMO

We report the first synthesis of silicon nanocrystals embedded in a silicon nitride matrix through a direct pyrolysis of a preceramic polymer (perhydropolysilazane). Structural analysis carried out by XRD, XPS, Raman and TEM reveals the formation of silicon quantum dots and correlates the microstructures with the annealing temperature. The photoluminescence of the nanocomposites was investigated by both linear and nonlinear measurements. Furthermore we demonstrate an enhanced chemical resistance of the nitride matrix, compared to the typical oxide one, in both strongly acidic and basic environments. The proposed synthesis via polymer pyrolysis is a striking innovation potentially allowing a mass-scale production nitride embedded Si nanocrystals.

5.
Dalton Trans ; 47(41): 14573-14579, 2018 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-30259035

RESUMO

We report a method to synthesize a palladium-functionalized porous graphene xerogel structure. A graphene xerogel nanocomposite with a three-dimensional microstructure was obtained by chemical reduction of an aqueous dispersion of graphene oxide at mild temperature. After the graphene hydrogel has been placed in a K2PdCl4 solution, the spontaneous redox reaction between the reduced graphene and Pd2+ takes place, leading to the formation of nanohybrid materials consisting of a graphene porous matrix decorated with Pd nanoparticles. The final porosity of the material was tuned through drying the graphene hydrogel by solvent evaporation. The palladium functionalized porous graphene xerogels were successfully used for the catalytic reduction of Rhodamine 6G.

6.
Nanotechnology ; 29(31): 315101, 2018 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-29762138

RESUMO

The main limitation of drug-enhanced radiotherapy concerns the difficulty to evaluate the effectiveness of cancer targeting after drug administration hindering the standardization of therapies based on current radiosensitizing compounds. The challenge regards the development of systems able to combine imaging and radiotherapy enhancement in order to perform highly reliable cancer theragnosis. For these reasons, gold-magnetite hybrid nanoparticles (H-NPs) are proposed as innovative theranostic nanotools for imaging-guided radiosensitization in cancer treatment. In this work we propose a novel method for the synthesis of hydrophilic and superparamagnetic Tween20-stabilized gold-magnetite H-NPs. Morphology and chemical composition of nanoparticles were assessed by transmission electron microscopy, x-ray diffraction analysis and ion-coupled plasma optical emission spectroscopy. Colloidal stability and magnetic properties of nanoparticles were determined by dynamic light scattering and magnetometry. The potentialities of H-NPs for magnetic resonance imaging were studied using a human 4T-MRI scanner. Nanoparticles were proven to induce concentration-dependent contrast enhancement in T2*-weighted MR-images. The cytotoxicity, the cellular uptake and the radiosensitization activity of H-NPs were investigated in human osteosarcoma MG63 cell cultures and murine 3T3 fibroblasts, using specific bioassays and laser scanning confocal microscopy. H-NPs did not exhibit significant toxicity and were demonstrated to be internalized by cells. A significant x-ray enhancement at specific H-NPs exposure concentrations was evidenced on MG63 cell line.

7.
Biophys Chem ; 229: 151-164, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28739150

RESUMO

The biocompatibility of an implant depends upon the material it is composed of, in addition to the prosthetic device's morphology, mechanical and surface properties. Properties as porosity and pore size should allow, when required, cells penetration and proliferation. Stiffness and strength, that depend on the bulk characteristics of the material, should match the mechanical requirements of the prosthetic applications. Surface properties should allow integration in the surrounding tissues by activating proper communication pathways with the surrounding cells. Bulk and surface properties are not interconnected, and for instance a bone prosthesis could possess the necessary stiffness and strength for the application omitting out prerequisite surface properties essential for the osteointegration. In this case, surface treatment is mandatory and can be accomplished using various techniques such as applying coatings to the prosthesis, ion beams, chemical grafting or modification, low temperature plasma, or a combination of the aforementioned. Low temperature plasma-based techniques have gained increasing consensus for the surface modification of biomaterials for being effective and competitive compared to other ways to introduce surface functionalities. In this paper we review plasma processing techniques and describe potentialities and applications of plasma to tailor the interface of biomaterials.


Assuntos
Materiais Biocompatíveis/química , Gases em Plasma , Materiais Biocompatíveis/farmacologia , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Humanos , Microscopia de Força Atômica , Microscopia Confocal , Espectroscopia Fotoeletrônica , Porosidade , Propriedades de Superfície , Temperatura
8.
Pathologica ; 108(3): 148-150, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28195268

RESUMO

Vulvar tumors are not very common and account for about 4% of all cancers affecting the female genital organs. Frequently, malignant neoplasia of this site have squamous phenotype and the rare cases of metastasization are reported in the locoregional lymph nodes and in the surrounding organs. We report a case of metastasization of a vulvar squamous cell carcinoma in an unusual place such as the parietal pleura, in a relapsing patient that was submitted to a surgical vulvectomy the previous year.


Assuntos
Carcinoma de Células Escamosas/secundário , Derrame Pleural Maligno/patologia , Neoplasias Pleurais/secundário , Neoplasias Vulvares/patologia , Idoso , Biomarcadores Tumorais/análise , Biópsia , Carcinoma de Células Escamosas/química , Carcinoma de Células Escamosas/complicações , Diagnóstico Diferencial , Feminino , Humanos , Imuno-Histoquímica , Derrame Pleural Maligno/diagnóstico , Derrame Pleural Maligno/etiologia , Neoplasias Pleurais/química , Neoplasias Pleurais/complicações , Valor Preditivo dos Testes , Tomografia Computadorizada por Raios X
9.
Colloids Surf B Biointerfaces ; 113: 320-9, 2014 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-24121075

RESUMO

Plasma enhanced physical vapor depositions are extensively used to fabricate substrates for cell culture applications. One peculiarity of the plasma processes is the possibility to deposit thin films with reproducible chemical and physical properties. In the present work, a combinatorial plasma polymerization process was used to deposit thin carbon based films to promote cell adhesion, in the interest of testing cell proliferation as a function of the substrate chemical properties. Peculiarity of the combinatorial approach is the possibility to produce in just one deposition experiment, a set of surfaces of varying chemical moieties by changing the precursor composition. A full characterization of the chemical, physical and thermodynamic properties was performed for each set of the synthesized surfaces. X-ray photoelectron spectroscopy was used to measure the concentration of carboxyl, hydroxyl and amine functional groups on the substrate surfaces. A perfect linear trend between polar groups' density and precursors' concentration was found. Further analyses reveled that also contact angles and the correspondent surface energies of all deposited thin films are linearly dependent on the precursor concentration. To test the influence of the surface composition on the cell adhesion and proliferation, two cancer cell lines were utilized. The cell viability was assessed after 24 h and 48 h of cell culture. Experiments show that we are able to control the cell adhesion and proliferation by properly changing the thin film deposition conditions i.e. the concentration and the kind of chemical moiety on the substrate surface. The results also highlight that physical and chemical factors of biomaterial surface, including surface hydrophobicity and free energy, chemical composition, and topography, can altered cell attachment.


Assuntos
Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Adesão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Humanos , Polimerização , Propriedades de Superfície , Molhabilidade
10.
Int J Sports Med ; 35(3): 253-8, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23900896

RESUMO

Time-tested data indicate that ECG diagnosis of left ventricular hypertrophy in young athletes is challenging due to low sensitivity of the commonly used criteria. We sought to establish whether adult ECG criteria can be appropriate to make diagnosis of both common and uncommon patterns of left ventricular hypertrophy in young trained athletes. A total of 122 athletes, ages 16.2±3.8 years, training at least 5 h per week, were studied with Sokolow-Lyon voltage, Romhilt-Estes, Cornell voltage, Cornell Product, Perugia and Framingham scores. Garson Criteria were also investigated in athletes under 16. Participants were divided into 2 groups based on the presence (group-A, n=56) or absence (group-B, n=66) of at least one positive ECG score. Test performance was calculated with respect to accurate echocardiographic diagnosis of left ventricular hypertrophy. There were no inter-group differences regarding physical characteristics and training burden. 9 athletes from group-A (16%) and 2 from group-B (3%) were found to have left ventricular hypertrophy, likely to be pathological in 2 cases from group-A. Criteria gathering both QRS voltages and ST-T anomalies, like Perugia-score, best identified this subgroup and should be preferred to those based on QRS voltage analysis alone.


Assuntos
Eletrocardiografia , Ventrículos do Coração/anatomia & histologia , Hipertrofia Ventricular Esquerda/diagnóstico , Condicionamento Físico Humano , Esportes/fisiologia , Diagnóstico Diferencial , Feminino , Ventrículos do Coração/diagnóstico por imagem , Humanos , Hipertrofia Ventricular Esquerda/diagnóstico por imagem , Masculino , Sensibilidade e Especificidade , Ultrassonografia , Função Ventricular
11.
Langmuir ; 28(45): 15900-6, 2012 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-23083447

RESUMO

Branched gold nanoparticles were grown on oxidized multiwalled carbon nanotubes by one-step reduction of gold chloride in water. The carbon nanotube/gold hybrids were used for the delivery of the anticancer drug doxorubicin hydrochloride into A549 lung cancer cell line. Doxorubicin (Dox) can be adsorbed in high quantity on both inner and outer surfaces of oxidized carbon nanotubes by π-π stacking interactions between doxorubicin aromatic groups and carbon nanotube (CNT) backbone. Carbon nanotube/gold hybrids display a broad absorption band in the red and near-infrared regions allowing their use for imaging applications. In vitro cellular tests showed that the nanostructures can efficiently transport and deliver doxorubicin inside the cells.


Assuntos
Antineoplásicos/farmacocinética , Doxorrubicina/farmacocinética , Sistemas de Liberação de Medicamentos , Ouro/química , Neoplasias Pulmonares/tratamento farmacológico , Nanopartículas Metálicas/química , Nanotubos de Carbono/química , Humanos , Neoplasias Pulmonares/patologia , Tamanho da Partícula , Propriedades de Superfície , Células Tumorais Cultivadas
12.
Int J Pharm ; 438(1-2): 45-52, 2012 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-22959992

RESUMO

Gold nanoparticles functionalized with doxorubicin and stabilized with multilayers of degradable polyelectrolyte were allowed to age in aqueous medium in vitro in order to show the possibility of drug release in cellular environment. The chemico-physical characteristics of the nanoparticles are reported. The observed release of doxorubicin (DOX) was pH-dependent, and it increased in acidic environment. Cell uptake of nanoparticles and drug release were monitored by laser scanning confocal microscopy. Data showed that drug-bearing nanoparticles delivered DOX into the nuclei of A549 cells, leading to pronounced cytotoxic effects to this lung tumor cells. Our results suggest that gold nanoparticles conjugated with doxorubicin could be used as a pH-triggered drug releasing carrier for tumor drug delivery.


Assuntos
Antibióticos Antineoplásicos/química , Doxorrubicina/química , Portadores de Fármacos/química , Nanopartículas Metálicas/química , Adsorção , Antibióticos Antineoplásicos/administração & dosagem , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Preparações de Ação Retardada/administração & dosagem , Preparações de Ação Retardada/química , Doxorrubicina/administração & dosagem , Portadores de Fármacos/administração & dosagem , Ouro/química , Humanos , Nanopartículas Metálicas/administração & dosagem , Poliaminas/química , Polilisina/análogos & derivados , Polilisina/química
13.
J Sports Med Phys Fitness ; 49(4): 448-52, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20087305

RESUMO

Non-alcoholic steatosis (non-alcoholic fatty liver disease [NAFLD]), now considered a metabolic pathway to advanced liver disease, cirrhosis and hepatocellular carcinoma, can also be explained by physical inactivity and increased dietary fat intake. No established treatment exists for this potentially serious disorder. The authors present the case of a 29-year-old man with NALFD who followed a restricted diet and practiced aerobic exercise for 16 weeks. Outcome after a combination therapy of aerobic exercise and diet was good, suggesting that treatment with a restricted diet and physical exercise can improve blood biochemical values in patients with NAFLD. Moderate-intensity aerobic exercise may help to normalize liver enzyme values and the quality of life of patients with fatty liver diseases.


Assuntos
Exercício Físico , Fígado Gorduroso/fisiopatologia , Adulto , Alanina Transaminase/sangue , Alanina Transaminase/metabolismo , Aspartato Aminotransferases/sangue , Aspartato Aminotransferases/metabolismo , Dieta , Fígado Gorduroso/dietoterapia , Fígado Gorduroso/terapia , Humanos , Resistência à Insulina , Masculino , Atividade Motora , Estado Nutricional , Educação Física e Treinamento , Qualidade de Vida
14.
J Phys Chem A ; 112(34): 7856-61, 2008 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-18683914

RESUMO

We present an innovative approach to characterize small metal nanoclusters embedded in an amorphous carbon matrix. A simple mathematical relation linking binding energy shifts to the mean nanoparticle (NP) dimensions allows determination of the distribution of NP sizes by fitting the Au 4f X-ray photoemission spectrum. The NP size distributions obtained using our method are compared with those obtained from X-ray diffraction spectra.

15.
Phytomedicine ; 14(2-3): 109-14, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16860550

RESUMO

Maytenus senegalensis (Lam.) Excell (Celastraceae) root extracts were investigated for their topical anti-inflammatory properties by measuring the inhibition of the Croton oil-induced ear oedema in mice. The highest anti-inflammatory activity was detected in the chloroform extract, which reduced the oedematous response with a potency similar to that of the NSAID reference drug indomethacin (ID(50)=84 and 93 microg/cm(2), respectively). Fractionation of the chloroform and of the hexane extracts led to the isolation of maytenoic acid (1), which exhibited a dose-dependent antiphlogistic effect (ID(50)=0.11 micromol/cm(2)) twice that of indomethacin (ID(50)=0.26 micromol/cm(2)) and only three times lower than that of hydrocortisone (ID(50)=0.04 micromol/cm(2)).


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Edema/prevenção & controle , Maytenus , Fitoterapia , Extratos Vegetais/farmacologia , Triterpenos/farmacologia , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Anti-Inflamatórios não Esteroides/uso terapêutico , Óleo de Cróton , Relação Dose-Resposta a Droga , Edema/induzido quimicamente , Masculino , Camundongos , Camundongos Endogâmicos , Extratos Vegetais/administração & dosagem , Extratos Vegetais/uso terapêutico , Raízes de Plantas , Triterpenos/administração & dosagem , Triterpenos/uso terapêutico
17.
J Phys Chem A ; 110(51): 13857-63, 2006 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-17181344

RESUMO

The use of sophisticated methods for modeling complex systems is gaining ever more importance recently because they allow the design of material with properties tailored to specific applications. However, problems may arise from conflicts between different reaction pathways inherent in the wide variety of chemical elements used. This is reflected by the impossibility of exactly solving the Schroedinger equation or of exactly describing the exchange interaction in density functional theory when the system complexity increases. An alternative is offered by the application of semiempirical methods because they strongly reduce system complexity. Normally, this is accomplished by increasing the degree of the approximations to the detriment of the formalism generality. This work is aimed to improve the semiempirical electronegativity equalization method. This is accomplished by modifying the point charge Madelung potential with the introduction of covalent interaction to better describe the chemical bonds.

18.
Planta Med ; 71(1): 79-81, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15678379

RESUMO

A new diglucoside having a 5-methylchromone moiety was isolated from a commercial sample of Cape aloe, the dried exudate from Aloe ferox Miller, and named aloeresin I. Its structure was established as 1 on the basis of spectral and chemical evidence. Aloeresin I (1) (1 micromol/cm2) reduces in vivo the oedematous response (39 %) induced by Croton oil in the mouse ear with the same potency as aloesin, one of the most abundant Cape aloe constituents, and to a higher extent than aloeresin H (2). Indomethacin (0.3 micromol/cm2), the reference anti-inflammatory compound, provokes 61 % oedema inhibition.


Assuntos
Aloe , Anti-Inflamatórios não Esteroides/farmacologia , Cromonas/farmacologia , Dissacarídeos/farmacologia , Fitoterapia , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Anti-Inflamatórios não Esteroides/uso terapêutico , Cromonas/administração & dosagem , Cromonas/uso terapêutico , Óleo de Cróton , Dissacarídeos/administração & dosagem , Dissacarídeos/uso terapêutico , Edema/induzido quimicamente , Edema/diagnóstico , Masculino , Camundongos , Camundongos Endogâmicos , Extratos Vegetais/administração & dosagem , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico
19.
Fitoterapia ; 75(5): 520-2, 2004 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15261393

RESUMO

Two new compounds, 10-O-beta-D-glucopyranosyl aloenin (4) and 8-C-beta-D-glucopyranosyl-7-O-methyl-(R)-aloesol (6), were isolated from a commercial sample of Kenya aloe together with the known products aloenin (2), aloenin 2'-p-coumaroyl ester (3), aloenin aglycone (1), orcinol and acetylorcinol. All structures were determined or confirmed by spectral analyses.


Assuntos
Aloe/química , Fitoterapia , Humanos , Folhas de Planta
20.
Biomaterials ; 25(11): 2029-37, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-14741617

RESUMO

Development of biomaterial-related infections is attracting an increasing interest due to the significant percentage of implant failure in the hospital care. Recent literature puts in evidence the dependence of the infection risk on the different biomaterials used, because of the different interactions between material surface and micro-organisms. Despite this, the mechanisms underlying the adhesion of bacteria to the biomaterial surface are still unclear. Aim of this work is to study the initial events of the processes responsible for the bacterial adhesion on polymers in order to prevent the development of bacterial infections and the consequent failure and replacement of biomedical devices. Electrostatic and Lifshitz-van der Waals forces are usually considered responsible for the interactions at the biomaterial interface. A new term that involves Lewis acid-base interactions is here introduced to better describe the bacterial adhesion to the polymer surface. Two requirements are needed to test this hypothesis: the development of an ideal polymeric surface in terms of chemical and morphological properties and the choice of a specific bacterial strain to be utilized as "probe". Experiments were worked out using an Escherichia coli (Gram-) strain that represent one of the principal isolates from infected biomaterial implants and its adhesion was investigated on polymers having different acid/basic character. The findings indicate that the bacterial adhesion is influenced by the chemical properties of the polymeric surface. These results may be interpreted taking into account a mechanism in which the acid/base (Lewis) interaction plays an important role.


Assuntos
Aderência Bacteriana , Materiais Biocompatíveis/química , Escherichia coli/química , Escherichia coli/citologia , Polietileno/química , Polimetil Metacrilato/química , Cloreto de Polivinila/química , Escherichia coli/fisiologia , Concentração de Íons de Hidrogênio , Teste de Materiais/métodos , Polímeros/química , Propriedades de Superfície
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