Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Mater Chem B ; 11(17): 3797-3807, 2023 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-37006120

RESUMO

Insufficient stability of micellar drug delivery systems is still the major limitation to their systematic application in chemotherapy. This work demonstrates novel π-electron stabilized polyelectrolyte block copolymer micelles based on dendritic polyglycerolsulfate-cystamine-block-poly(4-benzoyl-1,4-oxazepan-7-one)-pyrene (dPGS-SS-POxPPh-Py) presenting a very low critical micelle concentration (CMC) of 0.3 mg L-1 (18 nM), 55-fold lower than that of conventional amphiphilic block copolymer micelles. The drug loading capacities of up to 13 wt% allow the efficient encapsulation of the chemotherapeutic Docetaxel (DTX). The spherical morphology of the micelles was proven by cryogenic electron microscopy (cryo-EM). Gaussian Analysis revealed well-defined sizes of 57 nm and 80 nm in the unloaded/loaded state, respectively. Experiments by dynamic light scattering (DLS), ultraviolet-visible spectroscopy (UV-VIS), fluorescence spectroscopy, and cross-polarization solid-state 13C NMR studied the π-π interactions between the core-forming block segment of dPGS-SS-POxPPh-Py and DTX. The findings point to a substantial contribution of these noncovalent interactions to the system's high stability. By confocal laser scanning microscopy (CLSM), the cellular uptake of fluorescein-labelled FITC-dPGS-SS-POxPPh-Py micelles was monitored after one day displaying the successful cell insertion of the cargo-loaded systems. To ensure the drug release in cancerous cells, the disassembly of the micellar DTX-formulations was achieved by reductive and enzymatic degradation studied by light scattering and GPC experiments. Further, no size increase nor disassembly in the presence of human serum proteins after four days was detected. The precise in vitro drug release was also given by the high potency of inhibiting cancer cell growth, finding half-maximal inhibitory concentrations (IC50) efficiently reduced to 68 nM coming along with high viabilities of the empty polymer materials tested on tumor-derived HeLa, A549, and McF-7 cell lines after two days. This study highlights the substantial potential of micelles tailored through the combination of π-electron stabilization with dendritic polyglycerolsulfate for targeted drug delivery systems, enabling them to have a significant foothold in the clinical treatment of cancer.


Assuntos
Amidas , Micelas , Humanos , Docetaxel , Ésteres , Taxoides/química , Taxoides/farmacologia , Polímeros/química
2.
Trends Plant Sci ; 26(6): 600-606, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33893049

RESUMO

The European Commission's Farm to Fork (F2F) strategy, under the European Green Deal, acknowledges that innovative techniques, including biotechnology, may play a role in increasing sustainability. At the same time, organic farming will be promoted, and at least 25% of the EU's agricultural land shall be under organic farming by 2030. How can both biotechnology and organic farming be developed and promoted simultaneously to contribute to achieving the Sustainable Development Goals (SDGs)? We illustrate that achieving the SDGs benefits from the inclusion of recent innovations in biotechnology in organic farming. This requires a change in the law. Otherwise, the planned increase of organic production in the F2F strategy may result in less sustainable, not more sustainable, food systems.


Assuntos
Objetivos , Agricultura Orgânica , Biotecnologia , Europa (Continente) , Fazendas
3.
Foot Ankle Surg ; 22(1): 46-9, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26869500

RESUMO

BACKGROUND: Patient reported outcome measures (PROM's) after hallux valgus surgery are used to rate the effectiveness as perceived by the patient. The interpretability of these PROM's is highly dependent on participation rate. Data capture method may be an important factor contributing to the response rate. We investigated the effect on response rate of traditional paper mail, telephone and e-mail PROM's after hallux valgus surgery. METHODS: All consecutive patients operated between January and September 2013, were identified. Included patients were randomized by envelope in three groups: traditional pen and paper mail, e-mail and telephone. They were asked to fill in a FFI and EQ-5D. Two weeks later non-responders were sent a reminder. RESULTS: Of the 73 included patients, 25 were approached by mail, 24 by e-mail and 24 patients by telephone. The response rate on traditional mail was highest (88%), while response on e-mail was lowest (33%). Response rate on telephone was also high (79%). Response rate on traditional mail and telephone was significantly higher (p<0.001) than response on e-mail. CONCLUSIONS: Though electronic data collection has enormous potential, this study shows that e-mail yields unacceptable low response rates. It is too early to replace traditional pen-and-paper PROM's by electronic questionnaires.


Assuntos
Hallux Valgus/cirurgia , Avaliação de Resultados da Assistência ao Paciente , Inquéritos e Questionários , Adolescente , Adulto , Idoso , Correio Eletrônico , Feminino , Humanos , Entrevistas como Assunto , Masculino , Pessoa de Meia-Idade , Serviços Postais , Autorrelato , Adulto Jovem
7.
BMC Musculoskelet Disord ; 11: 188, 2010 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-20731873

RESUMO

BACKGROUND: Although pulsed electromagnetic field (PEMF) stimulation may be clinically beneficial during fracture healing and for a wide range of bone disorders, there is still debate on its working mechanism. Mesenchymal stem cells are likely mediators facilitating the observed clinical effects of PEMF. Here, we performed in vitro experiments to investigate the effect of PEMF stimulation on human bone marrow-derived stromal cell (BMSC) metabolism and, specifically, whether PEMF can stimulate their osteogenic differentiation. METHODS: BMSCs derived from four different donors were cultured in osteogenic medium, with the PEMF treated group being continuously exposed to a 15 Hz, 1 Gauss EM field, consisting of 5-millisecond bursts with 5-microsecond pulses. On culture day 1, 5, 9, and 14, cells were collected for biochemical analysis (DNA amount, alkaline phosphatase activity, calcium deposition), expression of various osteoblast-relevant genes and activation of extracellular signal-regulated kinase (ERK) signaling. Differences between treated and control groups were analyzed using the Wilcoxon signed rank test, and considered significant when p < 0.05. RESULTS: Biochemical analysis revealed significant, differentiation stage-dependent, PEMF-induced differences: PEMF increased mineralization at day 9 and 14, without altering alkaline phosphatase activity. Cell proliferation, as measured by DNA amounts, was not affected by PEMF until day 14. Here, DNA content stagnated in PEMF treated group, resulting in less DNA compared to control.Quantitative RT-PCR revealed that during early culture, up to day 9, PEMF treatment increased mRNA levels of bone morphogenetic protein 2, transforming growth factor-beta 1, osteoprotegerin, matrix metalloproteinase-1 and -3, osteocalcin, and bone sialoprotein. In contrast, receptor activator of NF-κB ligand expression was primarily stimulated on day 14. ERK1/2 phosphorylation was not affected by PEMF stimulation. CONCLUSIONS: PEMF exposure of differentiating human BMSCs enhanced mineralization and seemed to induce differentiation at the expense of proliferation. The osteogenic stimulus of PEMF was confirmed by the up-regulation of several osteogenic marker genes in the PEMF treated group, which preceded the deposition of mineral itself. These findings indicate that PEMF can directly stimulate osteoprogenitor cells towards osteogenic differentiation. This supports the theory that PEMF treatment may recruit these cells to facilitate an osteogenic response in vivo.


Assuntos
Células da Medula Óssea/citologia , Campos Eletromagnéticos , Osteoblastos/citologia , Células-Tronco/citologia , Células da Medula Óssea/metabolismo , Técnicas de Cultura de Células/métodos , Diferenciação Celular/fisiologia , Linhagem Celular Transformada , Proliferação de Células , Transformação Celular Viral , Células Cultivadas , Humanos , Osteoblastos/metabolismo , Células-Tronco/metabolismo , Células Estromais/citologia , Células Estromais/metabolismo
8.
J R Soc Interface ; 7(51): 1421-8, 2010 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-20375038

RESUMO

Severe large-scale disease and pest infestations in agricultural regions can cause significant economic damage. Understanding if and when disease control measures should be taken in the presence of risk and uncertainty is a key issue. We develop a framework to examine the economically optimal timing of treatment. The decision to treat should only be undertaken when the benefits exceed the costs by a certain amount and not if they are merely equal to or greater than the costs as standard net-present-value (NPV) analysis suggests. This criterion leads to a reduction in fungicide use. We investigate the effect of the model for disease progress on the value required for immediate treatment by comparing two standard models for disease increase (exponential and logistic growth). Analyses show that the threshold value of benefits required for immediate release of treatment varies significantly with the relative duration of the agricultural season, the intrinsic rate of increase of the disease and the level of uncertainty in disease progression. In comparing the performance of the delay strategy introduced here with the conventional NPV approach, we show how the degree of uncertainty affects the benefits of delaying control.


Assuntos
Agricultura/economia , Técnicas de Apoio para a Decisão , Doenças das Plantas/prevenção & controle , Incerteza , Agricultura/métodos , Fungicidas Industriais , Doenças das Plantas/microbiologia , Estações do Ano , Fatores de Tempo
9.
J Orthop Res ; 28(3): 390-6, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19780202

RESUMO

Wnt signaling is important for bone formation and osteoblastic differentiation. Recent findings indicate a stimulating role of Wnt signaling in bone mechanotransduction. However, negative effects of Wnt signaling on osteoblast differentiation and mineralization have been described as well. We conducted in vitro stretch experiments using human pre-osteoblasts to study short- and long-term effects of mechanical loading on Wnt/beta-catenin signaling. As the extracellular regulated kinase (ERK) pathway is known to be involved in mechanotransduction in osteoblasts, we also evaluated its role in Wnt/beta-catenin signaling. Stretch experiments up to 21 days (using stretch episodes of 15 min, alternated with 90 min rest) resulted in higher mineralization compared to static control cultures. We found that 15 min of stretch initially increased nuclear beta-catenin, but ultimately resulted in significant decrease at 12 and 40 h after stretch. Downregulation of Wnt-responsive element activity 16 h after stretch, using a luciferase construct, further supported these findings. The presence of the ERK inhibitor U0126 did not alter the stretch-induced decrease of beta-catenin levels. Our data indicate a biphasic effect of mechanical loading on beta-catenin in mineralizing human differentiating osteoblasts, which is independent of the ERK pathway. The osteogenic potential of our loading regime was confirmed by an increase in osteogenic differentiation markers such as alkaline phosphatase activity and calcium deposition after 3 weeks of culture. We conjecture that the biphasic aspect of Wnt/beta-catenin signaling with a strong decrease up to 40 h after the stretch induction, is important for the anabolic effects of mechanical stretch on bone.


Assuntos
Calcificação Fisiológica/fisiologia , Osteoblastos/metabolismo , Transdução de Sinais , Estresse Mecânico , Proteínas Wnt/metabolismo , beta Catenina/metabolismo , Butadienos/farmacologia , Diferenciação Celular , Linhagem Celular Transformada , Regulação para Baixo , Inibidores Enzimáticos/farmacologia , Genes Reporter , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Glicogênio Sintase Quinase 3 beta , Humanos , Cloreto de Lítio/farmacologia , Nitrilas/farmacologia , Osteoblastos/citologia , Plasmídeos , Elementos de Resposta/efeitos dos fármacos , Elementos de Resposta/genética , Transdução de Sinais/efeitos dos fármacos , Fatores de Tempo , Distribuição Tecidual/efeitos dos fármacos , Regulação para Cima , Proteínas Wnt/genética
10.
IEEE Trans Pattern Anal Mach Intell ; 31(10): 1790-803, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19696450

RESUMO

We present an object representation framework that encodes probabilistic spatial relations between 3D features and organizes these features in a hierarchy. Features at the bottom of the hierarchy are bound to local 3D descriptors. Higher level features recursively encode probabilistic spatial configurations of more elementary features. The hierarchy is implemented in a Markov network. Detection is carried out by a belief propagation algorithm, which infers the pose of high-level features from local evidence and reinforces local evidence from globally consistent knowledge, effectively producing a likelihood for the pose of the object in the detection scene. We also present a simple learning algorithm that autonomously builds hierarchies from local object descriptors. We explain how to use our framework to estimate the pose of a known object in an unknown scene. Experiments demonstrate the robustness of hierarchies to input noise, viewpoint changes, and occlusions.

12.
J Orthop Res ; 24(7): 1480-8, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16705736

RESUMO

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) produced by osteoblasts play an essential role in bone remodeling. Hence, these proteins could provide an interesting means by which mechanical loading leads to adaptation of bone. Here, we examined the effect of stretch on MMP-1, -2, -3, -8, -9, -13, and -14, as well as TIMP-1 and -2 gene expression in differentiating, mineralizing, and nonmineralizing human SV-40 immortalized preosteoblast cells. In the mineralizing osteoblast culture, but not in the nonmineralizing cultures, cyclic stretch for only 15 min resulted in an increase of MMP-1 (fourfold) and -3 (depending on differentiation stage up to 25-fold) transcript abundance. No clear effect was observed for other MMPs, TIMP-1 or -2. The increase of MMP-1 and -3 was confirmed on the protein level. Stretching experiments performed in the presence of a specific inhibitor of extracellular signal-regulated kinase (ERK) showed a strong suppression of the stretch-induced increase in MMP-1 and -3. In conclusion, we show that MMP-1 and MMP-3 are mechanosensitive genes in mineralizing the human osteoblast, and that the mechano-induction of these genes is mediated via the ERK pathway. Our findings implicate that these MMPs are important factors in the mechanoregulation of bone turnover. With the ability to generate MMPs at highly stretched sites, osteoblasts can potantially direct osteoclasts to specific bone surface areas prepared for resorption.


Assuntos
Calcificação Fisiológica/fisiologia , Diferenciação Celular/fisiologia , Metaloproteinases da Matriz/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/fisiologia , Osteoblastos/metabolismo , Butadienos , Linhagem Celular , Humanos , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Nitrilas , Osteoblastos/citologia , Fosforilação , Resistência à Tração , Inibidor Tecidual de Metaloproteinase-1/metabolismo , Inibidor Tecidual de Metaloproteinase-2/metabolismo
13.
J Biomech ; 39(9): 1702-7, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-15978598

RESUMO

The purpose of this study was to assess the effect of standardized anterior glenohumeral capsular lesions on axial humeral rotation in a full arc of glenohumeral elevation. Using a testing apparatus, the range of internal and external humeral rotation was assessed in an arc of glenohumeral elevation in the scapular plane with steps of 15 degrees in six isolated shoulder joint specimens. Cutting of the glenohumeral joint capsule 1 cm laterally from, and parallel to the glenoid rim was performed in seven steps of 1 cm till the anterior capsule was cut. Capsular lesions were made in three ways: from inferior, from superior and from the middle of the capsule. Anterior capsular lesions resulted in significant increase of external humeral rotation. This occurred particularly at 15-60 degrees glenohumeral elevation. Lesions of the inferior part of the capsule mainly increased external rotation at 30-60 degrees glenohumeral elevation, lesions of the superior part mainly in lower elevation angles and lesions of the middle more gradually in the range till 60 degrees of glenohumeral elevation. Cutting of the anterior glenohumeral capsule barely increased passive axial humeral rotation at elevation angles over 60 degrees. Above 60 degrees glenohumeral elevation, tightening of the inferior posterior glenohumeral joint capsule prevented both internal and, increasingly, external humeral rotation. From these observations it is concluded that increased external rotation correlates with progressive anterior capsular lesions, mainly below 60 degrees glenohumeral elevation. To assess anterior glenohumeral capsular lesions in patients, axial humeral rotation tests should probably not exceed 60 degrees glenohumeral elevation, i.e. 90 degrees thoracohumeral elevation.


Assuntos
Cápsula Articular , Rotação , Idoso , Fenômenos Biomecânicos , Humanos
14.
Arzneimittelforschung ; 35(6): 964-9, 1985.
Artigo em Inglês | MEDLINE | ID: mdl-2862877

RESUMO

The pharmacokinetic properties of adimolol (MEN 935), a new antihypertensive agents with predominantly beta-receptor blocking and additional alpha-adrenolytic activity were investigated in healthy volunteers. Study A subjects (n = 6) received single intravenous doses of 5 mg adimolol and single oral doses of 200 mg capsules, 200 mg tablets and 100 mg tablets on four occasions separated by at least two weeks. Study B subjects (n = 6) were given single intravenous doses of 5 mg and single oral doses of 100 mg of the 14C-labelled drug on two different occasions. Study C subjects (n = 6) were administered multiple oral doses of 100 mg adimolol daily for five days, and three weeks later 50 mg daily for five days. Adimolol plasma concentrations were assayed over seven days following each single dose using a specific and sensitive high-pressure liquid chromatographic method. The plasma concentration data obtained from the single i.v. dose studies were individually fitted to an open four-compartment model. To describe mathematically the single oral dose plasma level data, two compartments were added to the model to take care of the absorption. Irrespective of the route of administration, the doses and formulations given, all plasma concentration curves could be described with similar pharmacokinetic parameters. Plasma concentration curves predicted by the open four-compartment model were fully confirmed by the actual data obtained after chronic oral administration. The terminal half-life averaged 12 h following intravenous and 15 h after oral administration. The peak plasma concentration was reached on average 4 h following oral administration.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Antagonistas Adrenérgicos beta/metabolismo , Propanolaminas/metabolismo , Administração Oral , Antagonistas Adrenérgicos beta/administração & dosagem , Antagonistas Adrenérgicos beta/sangue , Adulto , Disponibilidade Biológica , Jejum , Humanos , Injeções Intravenosas , Cinética , Masculino , Pessoa de Meia-Idade , Modelos Biológicos , Propanolaminas/administração & dosagem , Propanolaminas/sangue , Equivalência Terapêutica
15.
Eur J Clin Pharmacol ; 21(3): 201-7, 1981.
Artigo em Inglês | MEDLINE | ID: mdl-7318879

RESUMO

The pharmacokinetics of alinidine was investigated in two groups of volunteers: Group I (N=5) received on two occasions single doses of 14C-labelled drug given orally (40 mg) or intravenously (10 mg); Group II (N=6) received single oral doses 10, 30, or 90 mg dissolved in 20 ml water. The samples from Group I were analysed by two different and independent methods (RIA and counting total radioactivity). The results obtained by the two methods were identical, since the compound was not metabolized. The plasma concentrations and renal excretion data obtained from both groups were individually fitted to an open three compartment model. Independent of the route of administration and of the doses given, similar pharmacokinetic parameters were calculated for each group and each trial. The half lives of the distribution and elimination phases were t1/2 alpha: 36-41s, t1/2 beta: 9.9-11.1 min and t 1/2 gamma: 2.7-3.8h. There was a linear relationship between the dose administered and the resulting areas under the plasma concentration curves (AUC). Following a lag period (tau =0.19-0.22h), the peak plasma concentration was reached 0.6-1.2h after oral administration. Oral alinidine was 100% bioavailable.


Assuntos
Fármacos Cardiovasculares/metabolismo , Clonidina/análogos & derivados , Administração Oral , Adulto , Clonidina/administração & dosagem , Clonidina/sangue , Clonidina/metabolismo , Clonidina/urina , Humanos , Cinética , Masculino , Modelos Biológicos , Radioimunoensaio
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...