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1.
Langmuir ; 35(40): 12898-12907, 2019 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-31513424

RESUMO

The vacancy-enhanced contact friction of graphene is mainly attributed to the vacancy-enhanced out-of-plane deformation flexibility of the graphene and the climbing of the tip out of the vacancy trap (which actually acts as a step edge). However, this mechanism does not apply for explaining the enhanced friction caused by small-sized vacancies that are unable to accommodate the tip, such as single vacancy and double vacancies, which also commonly exist in the graphene. In the present study, by performing a set of classic molecular dynamics simulations, we demonstrated that the double-vacancy defect in graphene substantially enhanced the contact friction when the tip slides over it and the pinning effect of the reconstructed lattice of the double-vacancy defect with atoms at the bottom of the tip dominated such an influence. The underlying mechanism of such an atomic pinning effect and the influence of the normal load, sliding direction, and the sliding velocity were unveiled by analyzing the obtained friction evolution and the atomic configuration and interaction between the tip and the graphene. We believe that the findings presented in this study complete the state-of-art understanding of the nanoscale friction behaviors of vacancy-defected graphene, which is essential for the implementation of their potential control.

2.
ACS Appl Mater Interfaces ; 11(34): 31386-31392, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31380618

RESUMO

Graphene has exhibited massive potential as a macroscale solid lubricant, but its durability is limited due to the weak adhesion between graphene sheets and the substrate. Here, inspired by mussel adhesive protein (MAP), effective reinforcement of the graphene-substrate interaction to attain remarkable enhancement on the durability of the graphene film is presented. The mussel-inspired graphene (mGr) film exhibits a coefficient of friction stabilizing at 0.16 up to 490000 sliding cycles in the friction testing against the silicon nitride ball; in the identical sliding condition, comparatively, the graphene (Gr) film without MAP only lasts 4300 sliding cycles. The analysis of Raman and ATR-FTIR demonstrates that, on the one hand, the MAP film firmly adsorbs onto the substrate via forming metal-catechol coordination bonds with metal atoms; on the other hand, it establishes strong interactions with graphene sheets by hydrogen bonding as well as the π-π overlap. As an interlayer, MAP retains graphene sheets within the contact interface in the form of a compact tribo-layer, which results in an over 2 orders of magnitude enhancement of durability for the mGr film. This strategy of improving the graphene-substrate adhesion via MAP offers an avenue for the development of effective and reliable graphene-based solid lubricants for engineering applications.

3.
Biomed Res Int ; 2019: 7267062, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31008111

RESUMO

Purpose: To date, it remains unknown whether the addition of platelet-rich fibrin (PRF) to bone grafts actually improves the effectiveness of maxillary sinus augmentation. This study aimed to perform a meta-analysis to evaluate the efficacy of PRF in sinus lift. Materials and Methods: PubMed, Embase, and the Cochrane Library were searched. Randomized controlled studies were identified. The risk of bias was evaluated using the Cochrane Collaboration tool. Results: Five RCTs were included in our meta-analysis. Clinical, radiographic, and histomorphometric outcomes were considered. No implant failure or graft failure was detected in all included studies within the follow-up period. The percentage of contact length between newly formed bone substitute and bone in the PRF group was lower but lacked statistical significance (3.90%, 95% CI, -2.91% to 10.71%). The percentages of new bone formation (-1.59%, 95% CI, -5.36% to 2.18%) and soft-tissue area (-3.73%, 95% CI, -10.11% to 2.66%) were higher in the PRF group but were not significantly different. The percentage of residual bone graft was not significant in either group (4.57%, 95% CI, 0% to 9.14%). Conclusions: Within the limitations of this review, it was concluded that there were no statistical differences in survival rate, new bone formation, contact between newly formed bone and bone substitute, percentage of residual bone graft (BSV/TV), and soft-tissue area between the non-PRF and PRF groups. Current evidence supporting the necessity of adding PRF to bone graft in sinus augmentation is limited.


Assuntos
Transplante Ósseo/métodos , Implantação Dentária Endo-Óssea/métodos , Fibrina Rica em Plaquetas , Levantamento do Assoalho do Seio Maxilar , Regeneração Óssea/efeitos dos fármacos , Substitutos Ósseos/farmacologia , Humanos , Seio Maxilar/efeitos dos fármacos , Seio Maxilar/patologia , Ensaios Clínicos Controlados Aleatórios como Assunto
4.
Invest Ophthalmol Vis Sci ; 60(1): 113-122, 2019 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-30629726

RESUMO

Purpose: To develop a culture regime for the in vitro human lens capsular bag model that better reflects clinical events following cataract surgery and to use this refined model to evaluate the putative impact of IOLs on PCO formation. Methods: Capsulorhexis and lens extraction were performed on human donor eyes to generate capsular bags attached to the ciliary body by the zonules. Preparations were secured by pinning the ciliary body to a silicone ring and maintaining in 6 mL serum-free EMEM for 28 days or in a graded culture system (days 1-3, 5% human serum and 10 ng/mL TGFß2; days 4-7, 2% human serum and 1 ng/mL TGFß2; days 8-14, 1% human serum and 0.1 ng/mL TGFß2; days 15-28, serum-free EMEM), which better mimics clinical changes. Preparations were monitored with phase-contrast and modified-dark-field microscopy. Cell coverage and light scatter were quantified using image analysis software. The transdifferentiation marker, α-SMA and matrix component, fibronectin were assessed by immunocytochemistry. To assess IOLs in the model, Alcon Acrysof or Hoya Vivinex IOLs were implanted in match-paired capsular bags. Results: Match-paired experiments showed that graded culture enhanced growth, facilitated matrix contraction, increased transdifferentiation, and promoted matrix deposition relative to serum-free culture. The graded culture protocol was applied to match-paired bags implanted with a Hoya Vivinex or an Alcon Acrysof IOL. The Vivinex demonstrated a lag in growth across the posterior capsule. However, by day 28, coverage was similar, but light-scatter was greater with Acrysof implanted. Cell growth on the Acrysof IOL anterior surface was significantly greater than Vivinex. Conclusions: The graded culture human capsular bag model serves as an excellent system to evaluate and develop intraocular lenses. The Hoya Vivinex IOL showed an overall better level of performance against postsurgical wound healing and PCO than the Alcon Acrysof using this model.


Assuntos
Opacificação da Cápsula/etiologia , Cápsula do Cristalino/fisiologia , Implante de Lente Intraocular/efeitos adversos , Lentes Intraoculares , Modelos Biológicos , Cápsula Posterior do Cristalino/patologia , Actinas/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Opacificação da Cápsula/patologia , Movimento Celular/fisiologia , Proliferação de Células/fisiologia , Transdiferenciação Celular/fisiologia , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Feminino , Fibronectinas/metabolismo , Técnica Indireta de Fluorescência para Anticorpo , Humanos , Luz , Masculino , Pessoa de Meia-Idade , Miofibroblastos/metabolismo , Miofibroblastos/patologia , Técnicas de Cultura de Órgãos , Espalhamento de Radiação , Doadores de Tecidos
5.
Comput Methods Biomech Biomed Engin ; 19(3): 240-247, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25693635

RESUMO

Few studies are performed to evaluate the influence of connection type on the stress distribution of distal extension mandibular removable partial dentures (RPDs) supported by both implants and natural teeth. In this study, five three-dimensional finite element models were prepared to simulate mandibular bilateral partially edentulous arches. Four were RPDs supported by both implants and natural teeth, and the other one was RPDs supported only by natural teeth. The maximum equivalent (EQV) stress values of bone around implants, the abutments, and the mucosa displacements of the related supporting structures were measured. It was found that a non-rigid telescopic coping was more favorable to protect the implant than a rigid telescopic coping. Compared with other connection types, the easy resilient attachment (ERA) system seemed to be effective to associate implant without complications. However, the results obtained in the present study should be cautiously interpreted in the clinic.


Assuntos
Prótese Dentária Fixada por Implante , Prótese Parcial Removível , Mandíbula , Estresse Mecânico , Dente , Adulto , Osso e Ossos , Dente Suporte , Análise de Elementos Finitos , Humanos , Masculino , Modelos Biológicos , Periodonto
6.
J Oral Maxillofac Surg ; 72(3): 449-55, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24215659

RESUMO

PURPOSE: This study was designed to evaluate clinical photographs published in the Journal of Oral and Maxillofacial Surgery (JOMS) and understand the current status of oral and maxillofacial surgery. MATERIALS AND METHODS: A total of 1,317 photographs from the JOMS Volume 69 were assessed. These photographs were scored from 1 to 10 for the following parameters: sharpness; depth of field; exposure; composition; color or grayscale; background; position; distortion; label consistency; and white balance. Then, the distributions of scores were analyzed. Each score was compared with the average score. The effects of different subjects; emergency or nonemergency situations; and intraoperative, preoperative, or postoperative conditions on the quality of photographs were analyzed by conducting a nonparametric Kruskal-Wallis test. RESULTS: The total score of each photograph showed a left-skewed distribution, varying from 3 to 10, with an average score of 6.82. Four parameters, including sharpness, depth of field, exposure, and white balance, scored less than the average score. Photographs with an intraoral subject yielded the lowest score, with a significant difference (P < .05). The score of photographs taken during a nonemergency situation was significantly higher than that during an emergency situation (6.84 vs 6.03; P < .001). Photographs of an intraoperative condition yielded a score significantly lower than those of pre- and postoperative conditions (6.53 vs 7.11 and 6.75, respectively; P < .001). Approximately 45.5% of photographs (148 of 325) displayed uncovered eyes and 57.1% of specimens (40 of 70) did not appear with a plotting scale. CONCLUSIONS: Sharpness, depth of field, exposure, and white balance should be considered to a greater extent than the other parameters when oral and maxillofacial photographs are taken, particularly for intraoral conditions, emergency situations, and intraoperative conditions. Enhanced parameters and protection of a patient's identity may significantly improve the average level of photographic quality.


Assuntos
Publicações Periódicas como Assunto , Fotografia Dentária/normas , Cirurgia Bucal , Humanos , Variações Dependentes do Observador , Estatísticas não Paramétricas
7.
Food Chem ; 138(2-3): 1008-14, 2013 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-23411207

RESUMO

Corchorus olitorius L. is grown in Taiwan during summer. Tender leaves are crushed and washed by running water before eating. Five fractions including crude phenolic extracts (using 80 per cent aqueous acetone) of whole plant, leaf, stem, washed leaf (WL) and dried water washing material (WW) were used in this study. Linoleic acid autoxidation inhibitions on all fractions were higher than that on α-tocopherol. Except for WL and WW, other fractions also showed DPPH radical scavenging efficiency. The effect of all fractions on the regulation of inflammatory responses in lipopolysaccharide (LPS)-stimulated J774A.1 macrophage cells was investigated. All fractions diminished LPS-induced protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2). Nitric oxide (NO) and prostaglandin E2 (PGE(2)), downstream products, were also suppressed in dose-dependent manners, except for WL and WW. Oxidative modification and loss of leaf phenolics after kneading and washing greatly affected DPPH radical scavenging and inflammatory responses.


Assuntos
Anti-Inflamatórios/farmacologia , Corchorus/química , Fenóis/farmacologia , Extratos Vegetais/farmacologia , Animais , Anti-Inflamatórios/química , Anti-Inflamatórios/isolamento & purificação , Antioxidantes/química , Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Camundongos , Fenóis/química , Fenóis/isolamento & purificação , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Folhas de Planta/química
8.
Biomaterials ; 31(13): 3479-91, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20138663

RESUMO

Current strategies to limit macrophage adhesion, fusion and fibrous capsule formation in the foreign body response have focused on modulating material surface properties. We hypothesize that topography close to biological scale, in the micron and nanometric range, provides a passive approach without bioactive agents to modulate macrophage behavior. In our study, topography-induced changes in macrophage behavior was examined using parallel gratings (250 nm-2 mum line width) imprinted on poly(epsilon-caprolactone) (PCL), poly(lactic acid) (PLA) and poly(dimethyl siloxane) (PDMS). RAW 264.7 cell adhesion and elongation occurred maximally on 500 nm gratings compared to planar controls over 48 h. TNF-alpha and VEGF secretion levels by RAW 264.7 cells showed greatest sensitivity to topographical effects, with reduced levels observed on larger grating sizes at 48 h. In vivo studies at 21 days showed reduced macrophage adhesion density and degree of high cell fusion on 2 mum gratings compared to planar controls. It was concluded that topography affects macrophage behavior in the foreign body response on all polymer surfaces examined. Topography-induced changes, independent of surface chemistry, did not reveal distinctive patterns but do affect cell morphology and cytokine secretion in vitro, and cell adhesion in vivo particularly on larger size topography compared to planar controls.


Assuntos
Reação a Corpo Estranho/imunologia , Macrófagos/imunologia , Modelos Biológicos , Polímeros , Animais , Linhagem Celular , Camundongos , Microscopia Eletrônica de Varredura , Propriedades de Superfície , Fator de Necrose Tumoral alfa/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo
9.
J Control Release ; 139(1): 48-55, 2009 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-19539680

RESUMO

Although viral gene transfer is efficient in achieving transgene expression for tissue engineering, drawbacks of virus dissemination, toxicity and transient gene expression due to immune response have hindered its widespread application. Many tissue engineering studies thus opt to genetically engineer cells in vitro prior to their introduction in vivo. However, it would be attractive to obviate the need for in vitro manipulation by transducing the infiltrating progenitor cells in situ. This study introduces the fabrication of a virus-encapsulated electrospun fibrous scaffold to achieve sustained and localized transduction. Adenovirus encoding the gene for green fluorescent protein was efficiently encapsulated into the core of poly(epsilon-caprolactone) fibers through co-axial electrospinning and was subsequently released via a porogen-mediated process. HEK 293 cells seeded on the scaffolds expressed high level of transgene expression over a month, while cells inoculated by scaffold supernatant showed only transient expression for a week. RAW 264.7 cells cultured on the virus-encapsulated fibers produced a lower level of IL-1 beta, TNF-alpha and IFN-alpha, suggesting that the activation of macrophage cells by the viral vector was reduced when encapsulated in the core-shell PCL fibers. In demonstrating sustained and localized cell transduction, this study presents an attractive alternative mode of applying viral gene transfer for regenerative medicine.


Assuntos
Técnicas de Transferência de Genes/instrumentação , Nanotubos , Adenoviridae/genética , Citomegalovirus/genética , Preparações de Ação Retardada , Ensaio de Imunoadsorção Enzimática , Expressão Gênica , Humanos , Cinética , Macrófagos/metabolismo , Macrófagos/virologia , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Poliésteres , Regiões Promotoras Genéticas/genética , Transgenes/genética , Replicação Viral
10.
Phytother Res ; 23(6): 785-90, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19145638

RESUMO

Leukopenia and immunity impairment usually occur during cancer therapy. Citronellol, an oil soluble compound derived from the geranium, has anticancer and antiinflammatory properties, as well as promoting wound healing. Ganoderma lucidum, Codonopsis pilosula and Angelicae sinensis are traditional Chinese herbs, all of which have proven immunomodulatory functions in laboratory-based research. This randomized, double-blind, placebo-controlled study examined whether the Chinese medicinal herb complex (CCMH; a mixture of citronellol and extracts of G. lucidum, C. pilosula and A. sinensis) improves the immune cell counts of cancer patients receiving chemotherapy and/or radiotherapy. A total of 105 cancer patients receiving chemotherapy or radiotherapy were enrolled. The quantities of immune cells in the blood of the subjects were determined before and after 6 weeks of cancer treatment, with either CCMH or a placebo. CCMH significantly reduced the depletion of leukocytes (14.2% compared with 28.2%) and neutrophils (11.0% compared with 29.1%). Analysis of the lymphocyte phenotype revealed that the patients receiving the placebo had reduced CD4 lymphocytes and natural killer (NK) cells than the CCMH-treated patients. Treatment with CCMH for patients receiving chemotherapy and/or radiotherapy may improve their immune function, improving their ability to fight off the cancer, as well as any secondary infections that could compromise their treatment and their health.


Assuntos
Medicamentos de Ervas Chinesas/uso terapêutico , Imunidade Celular/efeitos dos fármacos , Monoterpenos/uso terapêutico , Neoplasias/tratamento farmacológico , Fitoterapia , Linfócitos T CD4-Positivos/efeitos dos fármacos , Método Duplo-Cego , Feminino , Geranium/química , Humanos , Células Matadoras Naturais/efeitos dos fármacos , Contagem de Leucócitos , Masculino , Neoplasias/imunologia , Neoplasias/radioterapia
11.
Biophys J ; 94(12): 4948-56, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18326642

RESUMO

Accurate measurements of nuclear deformation, i.e., structural changes of the nucleus in response to environmental stimuli, are important for signal transduction studies. Traditionally, these measurements require labeling and imaging, and then nuclear measurement using image analysis. This approach is time-consuming, invasive, and unavoidably perturbs cellular systems. Light scattering, an emerging biophotonics technique for probing physical characteristics of living systems, offers a promising alternative. Angle-resolved low-coherence interferometry (a/LCI), a novel light scattering technique, was developed to quantify nuclear morphology for early cancer detection. In this study, a/LCI is used for the first time to noninvasively measure small changes in nuclear morphology in response to environmental stimuli. With this new application, we broaden the potential uses of a/LCI by demonstrating high-throughput measurements and by probing aspherical nuclei. To demonstrate the versatility of this approach, two distinct models relevant to current investigations in cell and tissue engineering research are used. Structural changes in cell nuclei due to subtle environmental stimuli, including substrate topography and osmotic pressure, are profiled rapidly without disrupting the cells or introducing artifacts associated with traditional measurements. Accuracy > or = 3% is obtained for the range of nuclear geometries examined here, with the greatest deviations occurring for the more complex geometries. Given the high-throughput nature of the measurements, this deviation may be acceptable for many biological applications that seek to establish connections between morphology and function.


Assuntos
Algoritmos , Núcleo Celular/ultraestrutura , Interpretação de Imagem Assistida por Computador/métodos , Interferometria/métodos , Refratometria/métodos , Tomografia de Coerência Óptica/métodos , Tamanho Celular , Coloração e Rotulagem
12.
Food Chem ; 108(2): 533-41, 2008 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-26059131

RESUMO

Galactose/glycine model systems of sugar concentration 0.035, 0.069, 0.139, and 0.278M were incubated at 60, 75, and 90°C separately for studying the reaction kinetics of color development, pH change, and system anti-oxidative activity change in Maillard reaction. The results indicated that system color development followed first-ordered kinetics on galactose concentration; system pH went linearly down with a logarithm-ordered kinetics on galactose concentration; and anti-oxidative activity reduced linearly with a first-ordered kinetics on galactose concentration. The values of Q10 and activation energy ranged from 1.98 to 2.00 and from 68.8 to 69.5kJ/mol, respectively, for these three properties.

13.
J Agric Food Chem ; 55(16): 6475-81, 2007 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-17629300

RESUMO

This study was performed to understand the characteristics and biological activities of phenolics in tomatoes and to examine the effect of tomato on the regulation of blood lipids. Tomatoes of both big and small sizes were used fresh, after blanching, or after blanching and heating. Moreover, a human clinical trial was conducted to examine plasma antioxidation, status of blood lipids, and phenolic responses after ingestion of fresh tomato, tomato juice, and a lycopene drink. The contents of tomato phenolics were increased by 34% for small tomato and by 23% for big tomato after treatment by blanching and heating at 100 degrees C for 30 min. Tomato phenolics showed fair antioxidant activity (57-71%) and also synergistically promoted the antioxidation (81-100%) of tomato carotenoids. In the human clinical study, total antioxidant capacity and phenolic contents in plasma were increased after administration of fresh tomato and tomato juice, but no significant difference was found for lycopene drink consumption. Triglyceride levels and low-density lipoprotein cholesterol were decreased after administration of fresh tomato and tomato juice, and high-density lipoprotein cholesterol was increased.


Assuntos
Antioxidantes/administração & dosagem , Dieta , Lipídeos/sangue , Lycopersicon esculentum/química , Fenóis/administração & dosagem , Adolescente , Bebidas , Carotenoides/administração & dosagem , LDL-Colesterol/sangue , Feminino , Flavonoides/sangue , Manipulação de Alimentos , Humanos , Licopeno , Masculino , Pessoa de Meia-Idade , Fenóis/sangue , Polifenóis , Substâncias Reativas com Ácido Tiobarbitúrico/análise , Triglicerídeos/sangue
14.
Am J Hypertens ; 20(1): 1-5, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17198904

RESUMO

BACKGROUND: About one in four adults suffer from prehypertension. People with prehypertension are at risk of developing hypertension, being a biomarker for cardiovascular disease risk. The use of milk-derived protein hydrolysates containing peptides with angiotensin-converting enzyme (ACE) inhibiting properties may reduce blood pressure (BP) and thus the risk of developing hypertension. METHODS: We investigated the BP-lowering effect of a casein-derived protein hydrolysate (C12 Peptide) during a 4-week intervention period in prehypertensive subjects. After a 2-week run-in period, 48 Taiwanese volunteers were randomly assigned to either placebo or C12 Peptide tablets for 4 weeks, followed by a 2-week off-treatment period. After the run-in period, BP was measured weekly. RESULTS: Baseline values for systolic BP (mean +/- SEM) in the placebo and C12 Peptide groups were 137.1 +/- 3.1 and 137.9 +/- 2.4 mm Hg, respectively; those for diastolic BP were 85.2 +/- 2.1 and 86.9 +/- 2.0 mm Hg, respectively. Four weeks repeated daily intake of 3.8 g C12 Peptide reduced significantly systolic and diastolic BP by 10.7 +/- 1.6 mm Hg and 6.9 +/- 1.2 mm Hg, respectively, compared to baseline. Furthermore, plasma angiotensin II and aldosterone levels were reduced significantly (P < .05). The placebo group showed a BP reduction of 3.6 +/- 2.4 and 2.7 +/- 1.6 mm Hg in systolic and diastolic BP, respectively (P = not significant). No evidence of side effects was observed. CONCLUSIONS: This study shows that C12 Peptide reduces BP in prehypertensive people.


Assuntos
Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Pressão Sanguínea/efeitos dos fármacos , Hipertensão/prevenção & controle , Aldosterona/sangue , Angiotensina II/sangue , Inibidores da Enzima Conversora de Angiotensina/efeitos adversos , Animais , Caseínas/efeitos adversos , Caseínas/uso terapêutico , Bovinos , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
15.
J Agric Food Chem ; 54(26): 9948-54, 2006 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-17177526

RESUMO

The effects of domestic processing on steroidal saponins and furostanol and spirostanol glycosides in Taiwanese yam cultivar (Dioscorea pseudojaponica Yamamoto) were studied. The baking or frying of yam slices was conducted at 150, 180, and 200 degrees C for 3, 5, and 10 min. Yam slices were steamed or microwave cooked at 2450 MHz with an output power of 850 W for 3, 5, and 10 min. The various saponins were quantified by HPLC with an evaporative light scattering detector (ELSD). Results showed that the contents of saponins were decreased along with increasing cooking temperature and time except for the steaming treatment. None of the steamed yam slices significantly change their initial compositions or quantities of furostanol and spirostanol glycosides. Fried yam slices had the highest loss of saponins, especially at 200 degrees C for 10 min (93 and 97% reductions for total furostanol and spirostanol glycosides, respectively). After baking for 10 min at 200 degrees C, the total furostanol and spirostanol glycosides were reduced by 67 and 74%, respectively. There were 12, 44, and 84% decreases for total furostanol glycosides and 10, 35, and 75% reductions for total spirostanol glycosides in yam slices after microwave cooking for 3, 5, and 10 min, respectively. Diosgenin, the aglycone of these saponins, could be found in yams after microwave cooking and baking, but not in steamed and fried yams.


Assuntos
Dioscorea/química , Manipulação de Alimentos/métodos , Fitosteróis/análise , Tubérculos/química , Saponinas/análise , Glicosídeos/análise , Temperatura Alta , Espirostanos/análise , Taiwan , Fatores de Tempo
16.
Biotechnol Bioeng ; 85(6): 589-600, 2004 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-14966800

RESUMO

A balance between proliferation and cell death is critical for achieving desirable high cell densities in mammalian cell culture. In this study, we evaluate a recently discovered anti-apoptotic gene, aven, and examine its effectiveness alone and in combination with a member of the Bcl-2 family, bcl-xL. The commercially popular cell line, Chinese hamster ovary (CHO), was genetically modified to constitutively express aven, bcl-xL, and the two genes in combination. Cells were exposed to several model insults that simulate severe bioreactor environments, including serum deprivation, spent medium, and Sindbis virus infection, as well as staurosporine, a known chemical inducer of apoptosis. CHO cells exhibited DNA fragmentation, a hallmark of apoptosis, after exposure to these model insults. After exposure to serum deprivation, 4- and 5-day spent medium, and staurosporine, cells expressing Aven provided limited protection against cell death when compared with the protection afforded by cells expressing Bcl-xL alone. However, the highest survival levels for all insults were achieved when Aven was expressed in combination with Bcl-xL. In fact, Aven appeared to act synergistically to enhance the protective function of Bcl-xL for several insults, because the protective function of the two genes expressed together in one cell line often exceeded the additive protective levels of each anti-apoptosis gene expressed alone. Surprisingly, Aven expression provided a mildly pro-apoptotic response in CHO isolates infected with Sindbis virus. However, CHO cells expressing both Bcl-xL and Aven showed protection against Sindbis virus infection due to the inhibitory properties of the bcl-xL anti-apoptosis gene. This study shows that combinatorial anti-apoptosis cell engineering strategies may be the most effective mechanisms for providing extended protection against cell death in mammalian cell culture.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Apoptose , Reatores Biológicos , Células CHO/patologia , Células CHO/virologia , Proteínas de Transporte/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Estaurosporina/farmacologia , Infecções por Alphavirus/metabolismo , Animais , Proteínas Reguladoras de Apoptose , Proteínas de Transporte/genética , Técnicas de Cultura de Células/métodos , Sobrevivência Celular , Cricetinae , Cricetulus , Meios de Cultura Livres de Soro , Citoproteção , Mamíferos , Proteínas de Membrana/genética , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Recombinantes/metabolismo , Vírus Sindbis , Proteína bcl-X
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