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Int. J. Mol. Sci., Volume 12, Issue 5 (May 2011) – 43 articles , Pages 2769-3393

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238 KiB  
Article
How Does the Preparation of Rye Porridge Affect Molecular Weight Distribution of Extractable Dietary Fibers?
by Allah Rakha, Per Åman and Roger Andersson
Int. J. Mol. Sci. 2011, 12(5), 3381-3393; https://doi.org/10.3390/ijms12053381 - 24 May 2011
Cited by 16 | Viewed by 9008
Abstract
Extractable dietary fiber (DF) plays an important role in nutrition. This study on porridge making with whole grain rye investigated the effect of rest time of flour slurries at room temperature before cooking and amount of flour and salt in the recipe on [...] Read more.
Extractable dietary fiber (DF) plays an important role in nutrition. This study on porridge making with whole grain rye investigated the effect of rest time of flour slurries at room temperature before cooking and amount of flour and salt in the recipe on the content of DF components and molecular weight distribution of extractable fructan, mixed linkage (1→3)(1→4)-β-D-glucan (β-glucan) and arabinoxylan (AX) in the porridge. The content of total DF was increased (from about 20% to 23% of dry matter) during porridge making due to formation of insoluble resistant starch. A small but significant increase in the extractability of β-glucan (P = 0.016) and AX (P = 0.002) due to rest time was also noted. The molecular weight of extractable fructan and AX remained stable during porridge making. However, incubation of the rye flour slurries at increased temperature resulted in a significant decrease in extractable AX molecular weight. The molecular weight of extractable β-glucan decreased greatly during a rest time before cooking, most likely by the action of endogenous enzymes. The amount of salt and flour used in the recipe had small but significant effects on the molecular weight of β-glucan. These results show that whole grain rye porridge made without a rest time before cooking contains extractable DF components maintaining high molecular weights. High molecular weight is most likely of nutritional importance. Full article
(This article belongs to the Special Issue Dietary Fibre: Biochemistry and Nutritional Science)
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488 KiB  
Article
Expression of an Endo-β-1,4-glucanase Gene from Orpinomyces PC-2 in Pichia pastoris
by Xin Jin, Nan Meng and Li-ming Xia
Int. J. Mol. Sci. 2011, 12(5), 3366-3380; https://doi.org/10.3390/ijms12053366 - 24 May 2011
Cited by 18 | Viewed by 8936
Abstract
The endo-β-1,4-glucanase gene celE from the anaerobic fungus Orpinomyces PC-2 was placed under the control of an alcohol oxidase promoter (AOX1) in the plasmid pPIC9K, and integrated into the genome of a methylotrophic yeast P. pastoris GS115 by electroporation. The strain with highest [...] Read more.
The endo-β-1,4-glucanase gene celE from the anaerobic fungus Orpinomyces PC-2 was placed under the control of an alcohol oxidase promoter (AOX1) in the plasmid pPIC9K, and integrated into the genome of a methylotrophic yeast P. pastoris GS115 by electroporation. The strain with highest endo-β-1,4-glucanase activity was selected and designed as P. pastoris egE, and cultivated in shaking flasks. The culture supernatant was assayed by SDS-polyacrylamide gel electrophoresis and showed a single band at about 52 kDa. Furthermore, the recombinant P. pastoris egE was proved to possess the ability to utilize sodium carboxymethyl cellulose as a carbon source. The recombinant endoglucanase produced by P. pastoris showed maximum activity at pH 6.0 and temperature 45 °C, indicating it was a mesophilic neutral endo-β-1,4-glucanase, suitable for denim biofinishing/washing. Further research was carried out in suitable fermentation medium in shaking flasks. The most favorable methanol addition concentration was discussed and given as 1.0%. After methanol induction for 96 h, the endo-β-1,4-glucanase activity reached 72.5 IU mL−1. This is the first report on expression and characterization of endo-β-1,4-glucanase from Orpinomyces in P. pastoris. The endo-β-1,4-glucanase secreted by recombinant P. pastoris represents an attractive potential for both academic research and textile industry application. Full article
(This article belongs to the Section Biochemistry)
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426 KiB  
Article
Anticoagulant, Antioxidant and Antitumor Activities of Heterofucans from the Seaweed Dictyopteris delicatula
by Kaline Dantas Magalhaes, Leandro Silva Costa, Gabriel Pereira Fidelis, Ruth Medeiros Oliveira, Leonardo Thiago Duarte Barreto Nobre, Nednaldo Dantas-Santos, Rafael Barros Gomes Camara, Ivan Rui Lopes Albuquerque, Sara Lima Cordeiro, Diego Araujo Sabry, Mariana Santana Santos Pereira Costa, Luciana Guimaraes Alves and Hugo Alexandre Oliveira Rocha
Int. J. Mol. Sci. 2011, 12(5), 3352-3365; https://doi.org/10.3390/ijms12053352 - 23 May 2011
Cited by 91 | Viewed by 12276
Abstract
In the present study, six families of sulfated polysaccharides were obtained from seaweed Dictyopteris delicatula by proteolytic digestion, followed by acetone fractionation and molecular sieving on Sephadex G-100. Chemical analyses demonstrated that all polysaccharides contain heterofucans composed mainly of fucose, xylose, glucose, galactose, [...] Read more.
In the present study, six families of sulfated polysaccharides were obtained from seaweed Dictyopteris delicatula by proteolytic digestion, followed by acetone fractionation and molecular sieving on Sephadex G-100. Chemical analyses demonstrated that all polysaccharides contain heterofucans composed mainly of fucose, xylose, glucose, galactose, uronic acid, and sulfate. The fucans F0.5v and F0.7v at 1.0 mg/mL showed high ferric chelating activity (~45%), whereas fucans F1.3v (0.5 mg/mL) showed considerable reducing power, about 53.2% of the activity of vitamin C. The fucan F1.5v presented the most prominent anticoagulant activity. The best antiproliferative activity was found with fucans F1.3v and F0.7v. However, F1.3v activity was much higher than F0.7v inhibiting almost 100% of HeLa cell proliferation. These fucans have been selected for further studies on structural characterization as well as in vivo experiments, which are already in progress. Full article
(This article belongs to the Section Biochemistry)
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173 KiB  
Article
Lycopene Enhances Antioxidant Enzyme Activities and Immunity Function in N-Methyl-N′-nitro-N-nitrosoguanidine–Induced Gastric Cancer Rats
by Cong Luo and Xian-Guo Wu
Int. J. Mol. Sci. 2011, 12(5), 3340-3351; https://doi.org/10.3390/ijms12053340 - 23 May 2011
Cited by 56 | Viewed by 9031
Abstract
To investigate anticancer effect of lycopene, we examined the effects of lycopene on the oxidative injury and immunity activities of N-methyl-N′-nitro-N-nitrosoguanidine (MNNG)-induced gastric cancer rats. The animals were divided into five groups. Group I served as the normal [...] Read more.
To investigate anticancer effect of lycopene, we examined the effects of lycopene on the oxidative injury and immunity activities of N-methyl-N′-nitro-N-nitrosoguanidine (MNNG)-induced gastric cancer rats. The animals were divided into five groups. Group I served as the normal control and was given corn oil orally for 20 weeks. Group II were induced with MNNG 200 mg/kg body weight by oral gavage at days 0 and 14, and saturated NaCl (1 mL per rats) was given once every three days for four weeks until the end of the experimental period. Group III, IV and V were posttreated with lycopene (50, 100 and 150 mg/kg body weight, dissolved in corn oil) from the sixth week of MNNG (as in group II) induction up to the end of the experimental period. In the presence of MNNG, MDA and immunity levels were significantly increased, whereas enzymatic (SOD, CAT, and GPx) antioxidant activities were decreased in the treated rats compared with normal control rats. Administration of lycopene to gastric carcinoma-induced rats largely up-regulated the redox status and immunity activities to decrease the risk of cancer compared to group II. We conclude that up-regulation of antioxidants and immunity by lycopene treatment might be responsible for the anticancer effect in gastric carcinoma. Full article
(This article belongs to the Section Biochemistry)
577 KiB  
Article
Behavior of Phenols and Phenoxyacids on a Bisphenol-A Imprinted Polymer. Application for Selective Solid-Phase Extraction from Water and Urine Samples
by Eliseo Herrero-Hernández, Rita Carabias-Martínez and Encarnacion Rodríguez-Gonzalo
Int. J. Mol. Sci. 2011, 12(5), 3322-3339; https://doi.org/10.3390/ijms12053322 - 20 May 2011
Cited by 26 | Viewed by 10112
Abstract
A molecularly imprinted polymer (MIP), obtained by precipitation polymerisation with 4-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate as cross-linker, and bisphenol-A (BPA) as template, was prepared. The binding site configuration of the BPA-MIP was examined using Scatchard analysis. Moreover, the behaviour of [...] Read more.
A molecularly imprinted polymer (MIP), obtained by precipitation polymerisation with 4-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate as cross-linker, and bisphenol-A (BPA) as template, was prepared. The binding site configuration of the BPA-MIP was examined using Scatchard analysis. Moreover, the behaviour of the BPA-MIP for the extraction of several phenolic compounds (bisphenol-A, bisphenol-F, 4-nitrophenol, 3-methyl-4-nitrophenol) and phenoxyacid herbicides such as 2,4-D, 2,4,5-T and 2,4,5-TP has been studied in organic and aqueous media in the presence of other pesticides in common use. It was possible to carry out the selective preconcentration of the target analytes from the organic medium with recoveries of higher than 70%. In an aqueous medium, hydrophobic interactions were found to exert a remarkably non-specific contribution to the overall binding process. Several parameters affecting the extraction efficiency of the BPA-MIP were evaluated to achieve the selective preconcentration of phenols and phenoxyacids from aqueous samples. The possibility of using the BPA-MIP as a selective sorbent to preconcentrate these compounds from other samples such as urine and river water was also explored. Full article
(This article belongs to the Special Issue Molecular Imprinting Science and Technology)
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402 KiB  
Review
Nanomedicine: Application Areas and Development Prospects
by Houria Boulaiz, Pablo J. Alvarez, Alberto Ramirez, Juan A. Marchal, Jose Prados, Fernando Rodríguez-Serrano, Macarena Perán, Consolación Melguizo and Antonia Aranega
Int. J. Mol. Sci. 2011, 12(5), 3303-3321; https://doi.org/10.3390/ijms12053303 - 19 May 2011
Cited by 137 | Viewed by 19210
Abstract
Nanotechnology, along with related concepts such as nanomaterials, nanostructures and nanoparticles, has become a priority area for scientific research and technological development. Nanotechnology, i.e., the creation and utilization of materials and devices at nanometer scale, already has multiple applications in electronics and [...] Read more.
Nanotechnology, along with related concepts such as nanomaterials, nanostructures and nanoparticles, has become a priority area for scientific research and technological development. Nanotechnology, i.e., the creation and utilization of materials and devices at nanometer scale, already has multiple applications in electronics and other fields. However, the greatest expectations are for its application in biotechnology and health, with the direct impact these could have on the quality of health in future societies. The emerging discipline of nanomedicine brings nanotechnology and medicine together in order to develop novel therapies and improve existing treatments. In nanomedicine, atoms and molecules are manipulated to produce nanostructures of the same size as biomolecules for interaction with human cells. This procedure offers a range of new solutions for diagnoses and “smart” treatments by stimulating the body’s own repair mechanisms. It will enhance the early diagnosis and treatment of diseases such as cancer, diabetes, Alzheimer’s, Parkinson’s and cardiovascular diseases. Preventive medicine may then become a reality. Full article
(This article belongs to the Special Issue Bioactive Nanoparticles (special issue))
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307 KiB  
Article
In Vitro Antioxidant Activities of Sulfated Derivatives of Polysaccharides Extracted from Auricularia auricular
by Hua Zhang, Zhen-Yu Wang, Lin Yang, Xin Yang, Xue Wang and Zhi Zhang
Int. J. Mol. Sci. 2011, 12(5), 3288-3302; https://doi.org/10.3390/ijms12053288 - 18 May 2011
Cited by 71 | Viewed by 9936
Abstract
In this research, two types of sulfated polysaccharide derivatives were successfully synthesized. Their antioxidant activities were investigated by employing various established in vitro systems. In addition, the degree of sulfation was evaluated using ion-chromatography and IR spectra. The results verify that, when employing [...] Read more.
In this research, two types of sulfated polysaccharide derivatives were successfully synthesized. Their antioxidant activities were investigated by employing various established in vitro systems. In addition, the degree of sulfation was evaluated using ion-chromatography and IR spectra. The results verify that, when employing scavenging superoxide radical tests, both the sulfation of acid Auricularia auricular polysaccharides (SAAAP) and the sulfation of neutral Auricularia auricular polysaccharides (SNAAP) derivatives possessed considerable antioxidant activity and had a more powerful antioxidant competence than that of the native non-sulfated polysaccharides (AAAP and NAAP). On the other hand, AAAP and NAAP exhibited stronger activity on scavenging both the hydroxyl radical and lipid peroxidation. Available data obtained with in vitro measurements indicates that the sulfated groups of AAAP and NAAP played an important role on antioxidant activity. In sum, the research demonstrates that the antioxidant activity of sulfated polysaccharide derivatives in vitro has a potential significance for seeking new natural antioxidant protective agents. Full article
(This article belongs to the Section Biochemistry)
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1461 KiB  
Review
Microfluidic Mixing: A Review
by Chia-Yen Lee, Chin-Lung Chang, Yao-Nan Wang and Lung-Ming Fu
Int. J. Mol. Sci. 2011, 12(5), 3263-3287; https://doi.org/10.3390/ijms12053263 - 18 May 2011
Cited by 891 | Viewed by 42159
Abstract
The aim of microfluidic mixing is to achieve a thorough and rapid mixing of multiple samples in microscale devices. In such devices, sample mixing is essentially achieved by enhancing the diffusion effect between the different species flows. Broadly speaking, microfluidic mixing schemes can [...] Read more.
The aim of microfluidic mixing is to achieve a thorough and rapid mixing of multiple samples in microscale devices. In such devices, sample mixing is essentially achieved by enhancing the diffusion effect between the different species flows. Broadly speaking, microfluidic mixing schemes can be categorized as either “active”, where an external energy force is applied to perturb the sample species, or “passive”, where the contact area and contact time of the species samples are increased through specially-designed microchannel configurations. Many mixers have been proposed to facilitate this task over the past 10 years. Accordingly, this paper commences by providing a high level overview of the field of microfluidic mixing devices before describing some of the more significant proposals for active and passive mixers. Full article
(This article belongs to the Special Issue Microfluidics)
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343 KiB  
Article
Novel Natural Inhibitors of CYP1A2 Identified by in Silico and in Vitro Screening
by Ruixin Zhu, Liwei Hu, Haiyun Li, Juan Su, Zhiwei Cao and Weidong Zhang
Int. J. Mol. Sci. 2011, 12(5), 3250-3262; https://doi.org/10.3390/ijms12053250 - 18 May 2011
Cited by 31 | Viewed by 11205
Abstract
Inhibition of cytochrome P450 (CYP) is a major cause of herb–drug interactions. The CYP1A2 enzyme plays a major role in the metabolism of drugs in humans. Its broad substrate specificity, as well as its inhibition by a vast array of structurally diverse herbal [...] Read more.
Inhibition of cytochrome P450 (CYP) is a major cause of herb–drug interactions. The CYP1A2 enzyme plays a major role in the metabolism of drugs in humans. Its broad substrate specificity, as well as its inhibition by a vast array of structurally diverse herbal active ingredients, has indicated the possibility of metabolic herb–drug interactions. Therefore nowadays searching inhibitors for CYP1A2 from herbal medicines are drawing much more attention by biological, chemical and pharmological scientists. In our work, a pharmacophore model as well as the docking technology is proposed to screen inhibitors from herbal ingredients data. Firstly different pharmaphore models were constructed and then validated and modified by 202 herbal ingredients. Secondly the best pharmaphore model was chosen to virtually screen the herbal data (a curated database of 989 herbal compounds). Then the hits (147 herbal compounds) were continued to be filtered by a docking process, and were tested in vitro successively. Finally, five of eighteen candidate compounds (272, 284, 300, 616 and 817) were found to have inhibition of CYP1A2 activity. The model developed in our study is efficient for in silico screening of large herbal databases in the identification of CYP1A2 inhibitors. It will play an important role to prevent the risk of herb–drug interactions at an early stage of the drug development process. Full article
(This article belongs to the Section Biochemistry)
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592 KiB  
Communication
Mechanism of Sphingosine 1-Phosphate- and Lysophosphatidic Acid-Induced Up-Regulation of Adhesion Molecules and Eosinophil Chemoattractant in Nerve Cells
by Richard W. Costello, Michael Maloney, Mazin Atiyeh, Gerald Gleich and Marie-Therese Walsh
Int. J. Mol. Sci. 2011, 12(5), 3237-3249; https://doi.org/10.3390/ijms12053237 - 17 May 2011
Cited by 10 | Viewed by 6779
Abstract
The lysophospholipids sphingosine 1-phosphate (S1P) and lysophosphatidic acid (LPA) act via G-protein coupled receptors S1P1–5 and LPA1–3 respectively, and are implicated in allergy. Eosinophils accumulate at innervating cholinergic nerves in asthma and adhere to nerve cells via intercellular adhesion molecule-1 (ICAM-1). [...] Read more.
The lysophospholipids sphingosine 1-phosphate (S1P) and lysophosphatidic acid (LPA) act via G-protein coupled receptors S1P1–5 and LPA1–3 respectively, and are implicated in allergy. Eosinophils accumulate at innervating cholinergic nerves in asthma and adhere to nerve cells via intercellular adhesion molecule-1 (ICAM-1). IMR-32 neuroblastoma cells were used as an in vitro cholinergic nerve cell model. The Gi coupled receptors S1P1, S1P3, LPA1, LPA2 and LPA3 were expressed on IMR-32 cells. Both S1P and LPA induced ERK phosphorylation and ERK- and Gi-dependent up-regulation of ICAM-1 expression, with differing time courses. LPA also induced ERK- and Gi-dependent up-regulation of the eosinophil chemoattractant, CCL-26. The eosinophil granule protein eosinophil peroxidase (EPO) induced ERK-dependent up-regulation of transcription of S1P1, LPA1, LPA2 and LPA3, providing the situation whereby eosinophil granule proteins may enhance S1P- and/or LPA- induced eosinophil accumulation at nerve cells in allergic conditions. Full article
(This article belongs to the Section Biochemistry)
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204 KiB  
Review
Evolution of Plant-Made Pharmaceuticals
by David R. Thomas, Claire A. Penney, Amrita Majumder and Amanda M. Walmsley
Int. J. Mol. Sci. 2011, 12(5), 3220-3236; https://doi.org/10.3390/ijms12053220 - 17 May 2011
Cited by 44 | Viewed by 13470
Abstract
The science and policy of pharmaceuticals produced and/or delivered by plants has evolved over the past twenty-one years from a backyard remedy to regulated, purified products. After seemingly frozen at Phase I human clinical trials with six orally delivered plant-made vaccines not progressing [...] Read more.
The science and policy of pharmaceuticals produced and/or delivered by plants has evolved over the past twenty-one years from a backyard remedy to regulated, purified products. After seemingly frozen at Phase I human clinical trials with six orally delivered plant-made vaccines not progressing past this stage over seven years, plant-made pharmaceuticals have made a breakthrough with several purified plant-based products advancing to Phase II trials and beyond. Though fraught with the usual difficulties of pharmaceutical development, pharmaceuticals made by plants have achieved pertinent milestones albeit slowly compared to other pharmaceutical production systems and are now at the cusp of reaching the consumer. Though the current economic climate begs for cautious investment as opposed to trail blazing, it is perhaps a good time to look to the future of plant-made pharmaceutical technology to assist in planning for future developments in order not to slow this technology’s momentum. To encourage continued progress, we highlight the advances made so far by this technology, particularly the change in paradigms, comparing developmental timelines, and summarizing the current status and future possibilities of plant-made pharmaceuticals. Full article
(This article belongs to the Special Issue Plant-Derived Pharmaceuticals by Molecular Farming)
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160 KiB  
Review
Novel Strategies for Drug Discovery Based on Intrinsically Disordered Proteins (IDPs)
by Jihua Wang, Zanxia Cao, Liling Zhao and Shuqiang Li
Int. J. Mol. Sci. 2011, 12(5), 3205-3219; https://doi.org/10.3390/ijms12053205 - 17 May 2011
Cited by 43 | Viewed by 9291
Abstract
Intrinsically disordered proteins (IDPs) are proteins that usually do not adopt well-defined native structures when isolated in solution under physiological conditions. Numerous IDPs have close relationships with human diseases such as tumor, Parkinson disease, Alzheimer disease, diabetes, and so on. These disease-associated IDPs [...] Read more.
Intrinsically disordered proteins (IDPs) are proteins that usually do not adopt well-defined native structures when isolated in solution under physiological conditions. Numerous IDPs have close relationships with human diseases such as tumor, Parkinson disease, Alzheimer disease, diabetes, and so on. These disease-associated IDPs commonly play principal roles in the disease-associated protein-protein interaction networks. Most of them in the disease datasets have more interactants and hence the size of the disease-associated IDPs interaction network is simultaneously increased. For example, the tumor suppressor protein p53 is an intrinsically disordered protein and also a hub protein in the p53 interaction network; α-synuclein, an intrinsically disordered protein involved in Parkinson diseases, is also a hub of the protein network. The disease-associated IDPs may provide potential targets for drugs modulating protein-protein interaction networks. Therefore, novel strategies for drug discovery based on IDPs are in the ascendant. It is dependent on the features of IDPs to develop the novel strategies. It is found out that IDPs have unique structural features such as high flexibility and random coil-like conformations which enable them to participate in both the “one to many” and “many to one” interaction. Accordingly, in order to promote novel strategies for drug discovery, it is essential that more and more features of IDPs are revealed by experimental and computing methods. Full article
(This article belongs to the Section Biochemistry)
505 KiB  
Article
KRAS Mutation Detection in Paired Frozen and Formalin-Fixed Paraffin-Embedded (FFPE) Colorectal Cancer Tissues
by Jérome Solassol, Jeanne Ramos, Evelyne Crapez, Majda Saifi, Alain Mangé, Evelyne Vianès, Pierre-Jean Lamy, Valérie Costes and Thierry Maudelonde
Int. J. Mol. Sci. 2011, 12(5), 3191-3204; https://doi.org/10.3390/ijms12053191 - 17 May 2011
Cited by 51 | Viewed by 9317
Abstract
KRAS mutation has been unambiguously identified as a marker of resistance to cetuximab-based treatment in metastatic colorectal cancer (mCRC) patients. However, most studies of KRAS mutation analysis have been performed using homogenously archived CRC specimens, and studies that compare freshly frozen specimens and [...] Read more.
KRAS mutation has been unambiguously identified as a marker of resistance to cetuximab-based treatment in metastatic colorectal cancer (mCRC) patients. However, most studies of KRAS mutation analysis have been performed using homogenously archived CRC specimens, and studies that compare freshly frozen specimens and formalin-fixed paraffin-embedded (FFPE) specimens of CRC are lacking. The aim of the present study was to evaluate the impact of tissue preservation on the determination of KRAS mutational status. A series of 131 mCRC fresh-frozen tissues were first analyzed using both high-resolution melting (HRM) and direct sequencing. KRAS mutations were found in 47/131 (35.8%) using both approaches. Out of the 47 samples that were positive for KRAS mutations, 33 had available matched FFPE specimens. Using HRM, 2/33 (6%) demonstrated suboptimal template amplification, and 2/33 (6%) expressed an erroneous wild-type KRAS profile. Using direct sequencing, 6/33 (18.1%) displayed a wild-type KRAS status, and 3/33 (9.1%) showed discordant mutations. Finally, the detection of KRAS mutations was lower among the FFPE samples compared with the freshly frozen samples, demonstrating that tissue processing clearly impacts the accuracy of KRAS genotyping. Full article
(This article belongs to the Section Molecular Pathology, Diagnostics, and Therapeutics)
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391 KiB  
Article
Mesomorphic Properties of an Homologous Series of Thioalkyl-Terminated Azomesogens
by Uhood J. Al-Hamdani
Int. J. Mol. Sci. 2011, 12(5), 3182-3190; https://doi.org/10.3390/ijms12053182 - 16 May 2011
Cited by 19 | Viewed by 7441
Abstract
A new homologous series (ten compounds) of 2-hydroxy azo compounds SRn (where n:1–10) were synthesized. Their structures were elucidated using spectroscopic techniques such as IR (Infrared), 1H-NMR as well as elemental analysis. Mesomorphic properties and phase transitions were studied using [...] Read more.
A new homologous series (ten compounds) of 2-hydroxy azo compounds SRn (where n:1–10) were synthesized. Their structures were elucidated using spectroscopic techniques such as IR (Infrared), 1H-NMR as well as elemental analysis. Mesomorphic properties and phase transitions were studied using polarized hot stage optical microscopy and differential scanning calorimetry (DSC), and are discussed as a function of the number of carbon atoms in the thioalkyl chain. It has been found that all compounds in the series are pure nematogens. Full article
(This article belongs to the Section Materials Science)
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469 KiB  
Article
Enhancing Effect of Glycerol on the Tensile Properties of Bombyx mori Cocoon Sericin Films
by Haiping Zhang, Lianxia Deng, Mingying Yang, Sijia Min, Lei Yang and Liangjun Zhu
Int. J. Mol. Sci. 2011, 12(5), 3170-3181; https://doi.org/10.3390/ijms12053170 - 16 May 2011
Cited by 59 | Viewed by 8828
Abstract
An environmental physical method described herein was developed to improve the tensile properties of Bombyx mori cocoon sericin films, by using the plasticizer of glycerol, which has a nontoxic effect compared with other chemical crosslinkers. The changes in the tensile characteristics and the [...] Read more.
An environmental physical method described herein was developed to improve the tensile properties of Bombyx mori cocoon sericin films, by using the plasticizer of glycerol, which has a nontoxic effect compared with other chemical crosslinkers. The changes in the tensile characteristics and the structure of glycerolated (0–40 wt% of glycerol) sericin films were investigated. Sericin films, both in dry and wet states, showed enhanced tensile properties, which might be regulated by the addition of different concentrations of glycerol. The introduction of glycerol results in the higher amorphous structure in sericin films as evidenced by analysis of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra, thermogravimetry (TGA) and differential scanning calorimetry (DSC) curves. Scanning Electron Microscopy (SEM) observation revealed that glycerol was homogeneously blended with sericin molecules when its content was 10 wt%, while a small amount of redundant glycerol emerged on the surface of sericin films when its content was increased to 20 wt% or higher. Our results suggest that the introduction of glycerol is a novel nontoxic strategy which can improve the mechanical features of sericin-based materials and subsequently promote the feasibility of its application in tissue engineering. Full article
(This article belongs to the Section Materials Science)
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396 KiB  
Article
First Principles Study on the Electronic Properties of Zn64Sb64−xTex Solid Solution (x = 0, 2, 3, 4)
by Jian-Hua Zhao, Er-Jing Han, Tian-Mo Liu and Wen Zeng
Int. J. Mol. Sci. 2011, 12(5), 3162-3169; https://doi.org/10.3390/ijms12053162 - 13 May 2011
Cited by 7 | Viewed by 8009
Abstract
The electronic properties of Te doped-ZnSb systems are investigated by first-principles calculations. We focus on the Zn64Sb64−xTex systems (x = 0, 2, 3, 4), which respond to the 0, 1.56at%, 2.34at% and 3.12at% of Te doping [...] Read more.
The electronic properties of Te doped-ZnSb systems are investigated by first-principles calculations. We focus on the Zn64Sb64−xTex systems (x = 0, 2, 3, 4), which respond to the 0, 1.56at%, 2.34at% and 3.12at% of Te doping concentration. We confirm that the amount of Te doping will change the conductivity type of ZnSb. In the cases of x = 2 and 3, we find that the Te element in ZnSb introduces some bands originating from Te s and p orbits and a donor energy level in the bottom of the conduction band, which induce the n-type conductivity of ZnSb. From these findings for the electronic structure and the conductivity mechanism, we predict that Te doping amounts such as 1.56at% and 2.34at% can be considered as suitable candidates for use as donor dopant. Full article
(This article belongs to the Special Issue Atoms in Molecules and in Nanostructures)
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651 KiB  
Article
Chemometric Analysis of the Amino Acid Requirements of Antioxidant Food Protein Hydrolysates
by Chibuike C. Udenigwe and Rotimi E. Aluko
Int. J. Mol. Sci. 2011, 12(5), 3148-3161; https://doi.org/10.3390/ijms12053148 - 13 May 2011
Cited by 270 | Viewed by 12929
Abstract
The contributions of individual amino acid residues or groups of amino acids to antioxidant activities of some food protein hydrolysates were investigated using partial least squares (PLS) regression method. PLS models were computed with amino acid composition and 3-z scale descriptors in the [...] Read more.
The contributions of individual amino acid residues or groups of amino acids to antioxidant activities of some food protein hydrolysates were investigated using partial least squares (PLS) regression method. PLS models were computed with amino acid composition and 3-z scale descriptors in the X-matrix and antioxidant activities of the samples in the Y-matrix; models were validated by cross-validation and permutation tests. Based on coefficients of the resulting models, it was observed that sulfur-containing (SCAA), acidic and hydrophobic amino acids had strong positive effects on scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and H2O2 radicals in addition to ferric reducing antioxidant power. For superoxide radicals, only lysine and leucine showed strong positive contributions while SCAA had strong negative contributions to scavenging by the protein hydrolysates. In contrast, positively-charged amino acids strongly contributed negatively to ferric reducing antioxidant power and scavenging of DPPH and H2O2 radicals. Therefore, food protein hydrolysates containing appropriate amounts of amino acids with strong contribution properties could be potential candidates for use as potent antioxidant agents. We conclude that information presented in this work could support the development of low cost methods that will efficiently generate potent antioxidant peptide mixtures from food proteins without the need for costly peptide purification. Full article
(This article belongs to the Special Issue Recent Advances in QSAR/QSPR Theory)
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430 KiB  
Article
Impaired Mitochondrial Respiratory Functions and Oxidative Stress in Streptozotocin-Induced Diabetic Rats
by Haider Raza, Subbuswamy K. Prabu, Annie John and Narayan G. Avadhani
Int. J. Mol. Sci. 2011, 12(5), 3133-3147; https://doi.org/10.3390/ijms12053133 - 13 May 2011
Cited by 106 | Viewed by 11972
Abstract
We have previously shown a tissue-specific increase in oxidative stress in the early stages of streptozotocin (STZ)-induced diabetic rats. In this study, we investigated oxidative stress-related long-term complications and mitochondrial dysfunctions in the different tissues of STZ-induced diabetic rats (>15 mM blood glucose [...] Read more.
We have previously shown a tissue-specific increase in oxidative stress in the early stages of streptozotocin (STZ)-induced diabetic rats. In this study, we investigated oxidative stress-related long-term complications and mitochondrial dysfunctions in the different tissues of STZ-induced diabetic rats (>15 mM blood glucose for 8 weeks). These animals showed a persistent increase in reactive oxygen and nitrogen species (ROS and RNS, respectively) production. Oxidative protein carbonylation was also increased with the maximum effect observed in the pancreas of diabetic rats. The activities of mitochondrial respiratory enzymes ubiquinol: cytochrome c oxidoreductase (Complex III) and cytochrome c oxidase (Complex IV) were significantly decreased while that of NADH:ubiquinone oxidoreductase (Complex I) and succinate:ubiquinone oxidoreductase (Complex II) were moderately increased in diabetic rats, which was confirmed by the increased expression of the 70 kDa Complex II sub-unit. Mitochondrial matrix aconitase, a ROS sensitive enzyme, was markedly inhibited in the diabetic rat tissues. Increased expression of oxidative stress marker proteins Hsp-70 and HO-1 was also observed along with increased expression of nitric oxide synthase. These results suggest that mitochondrial respiratory complexes may play a critical role in ROS/RNS homeostasis and oxidative stress related changes in type 1 diabetes and may have implications in the etiology of diabetes and its complications. Full article
(This article belongs to the Special Issue Oxidative Stress and Mitochondria)
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219 KiB  
Review
Inflammation, Oxidative Stress, and Obesity
by Alba Fernández-Sánchez, Eduardo Madrigal-Santillán, Mirandeli Bautista, Jaime Esquivel-Soto, Ángel Morales-González, Cesar Esquivel-Chirino, Irene Durante-Montiel, Graciela Sánchez-Rivera, Carmen Valadez-Vega and José A. Morales-González
Int. J. Mol. Sci. 2011, 12(5), 3117-3132; https://doi.org/10.3390/ijms12053117 - 13 May 2011
Cited by 1115 | Viewed by 43922
Abstract
Obesity is a chronic disease of multifactorial origin and can be defined as an increase in the accumulation of body fat. Adipose tissue is not only a triglyceride storage organ, but studies have shown the role of white adipose tissue as a producer [...] Read more.
Obesity is a chronic disease of multifactorial origin and can be defined as an increase in the accumulation of body fat. Adipose tissue is not only a triglyceride storage organ, but studies have shown the role of white adipose tissue as a producer of certain bioactive substances called adipokines. Among adipokines, we find some inflammatory functions, such as Interleukin-6 (IL-6); other adipokines entail the functions of regulating food intake, therefore exerting a direct effect on weight control. This is the case of leptin, which acts on the limbic system by stimulating dopamine uptake, creating a feeling of fullness. However, these adipokines induce the production of reactive oxygen species (ROS), generating a process known as oxidative stress (OS). Because adipose tissue is the organ that secretes adipokines and these in turn generate ROS, adipose tissue is considered an independent factor for the generation of systemic OS. There are several mechanisms by which obesity produces OS. The first of these is the mitochondrial and peroxisomal oxidation of fatty acids, which can produce ROS in oxidation reactions, while another mechanism is over-consumption of oxygen, which generates free radicals in the mitochondrial respiratory chain that is found coupled with oxidative phosphorylation in mitochondria. Lipid-rich diets are also capable of generating ROS because they can alter oxygen metabolism. Upon the increase of adipose tissue, the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), was found to be significantly diminished. Finally, high ROS production and the decrease in antioxidant capacity leads to various abnormalities, among which we find endothelial dysfunction, which is characterized by a reduction in the bioavailability of vasodilators, particularly nitric oxide (NO), and an increase in endothelium-derived contractile factors, favoring atherosclerotic disease. Full article
(This article belongs to the Special Issue Antioxidants)
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893 KiB  
Article
Nitrogen Substituted Phenothiazine Derivatives: Modelling of Molecular Self-Assembling
by Attila Bende and Ioan Turcu
Int. J. Mol. Sci. 2011, 12(5), 3102-3116; https://doi.org/10.3390/ijms12053102 - 12 May 2011
Cited by 6 | Viewed by 8302
Abstract
The study aims to present a detailed theoretical investigation of noncovalent intermolecular interactions between different π–π stacking nitrogen substituted phenothiazine derivatives by applying second-order Møller-Plesset perturbation (MP2), density functional (DFT) and semiempirical theories. The conformational stability of these molecular systems is mainly given [...] Read more.
The study aims to present a detailed theoretical investigation of noncovalent intermolecular interactions between different π–π stacking nitrogen substituted phenothiazine derivatives by applying second-order Møller-Plesset perturbation (MP2), density functional (DFT) and semiempirical theories. The conformational stability of these molecular systems is mainly given by the dispersion-type electron correlation effects. The density functional tight-binding (DFTB) method applied for dimer structures are compared with the results obtained by the higher level theoretical methods. Additionally, the optimal configuration of the investigated supramolecular systems and their self-assembling properties are discussed. Full article
(This article belongs to the Special Issue Advances in Molecular Electronic Structure Calculations)
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175 KiB  
Article
Required Levels of Catalysis for Emergence of Autocatalytic Sets in Models of Chemical Reaction Systems
by Wim Hordijk, Stuart A. Kauffman and Mike Steel
Int. J. Mol. Sci. 2011, 12(5), 3085-3101; https://doi.org/10.3390/ijms12053085 - 12 May 2011
Cited by 79 | Viewed by 9863
Abstract
The formation of a self-sustaining autocatalytic chemical network is a necessary but not sufficient condition for the origin of life. The question of whether such a network could form “by chance” within a sufficiently complex suite of molecules and reactions is one that [...] Read more.
The formation of a self-sustaining autocatalytic chemical network is a necessary but not sufficient condition for the origin of life. The question of whether such a network could form “by chance” within a sufficiently complex suite of molecules and reactions is one that we have investigated for a simple chemical reaction model based on polymer ligation and cleavage. In this paper, we extend this work in several further directions. In particular, we investigate in more detail the levels of catalysis required for a self-sustaining autocatalytic network to form. We study the size of chemical networks within which we might expect to find such an autocatalytic subset, and we extend the theoretical and computational analyses to models in which catalysis requires template matching. Full article
(This article belongs to the Special Issue Origin of Life 2011)
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222 KiB  
Review
Antioxidant Properties of Aminoethylcysteine Ketimine Decarboxylated Dimer: A Review
by Alberto Macone, Mario Fontana, Marco Barba, Bruno Botta, Mirella Nardini, Francesca Ghirga, Andrea Calcaterra, Laura Pecci and Rosa Marina Matarese
Int. J. Mol. Sci. 2011, 12(5), 3072-3084; https://doi.org/10.3390/ijms12053072 - 12 May 2011
Cited by 11 | Viewed by 9096
Abstract
Aminoethylcysteine ketimine decarboxylated dimer is a natural sulfur-containing compound detected in human plasma and urine, in mammalian brain and in many common edible vegetables. Over the past decade many studies have been undertaken to identify its metabolic role. Attention has been focused on [...] Read more.
Aminoethylcysteine ketimine decarboxylated dimer is a natural sulfur-containing compound detected in human plasma and urine, in mammalian brain and in many common edible vegetables. Over the past decade many studies have been undertaken to identify its metabolic role. Attention has been focused on its antioxidant properties and on its reactivity against oxygen and nitrogen reactive species. These properties have been studied in different model systems starting from plasma lipoproteins to specific cellular lines. All these studies report that aminoethylcysteine ketimine decarboxylated dimer is able to interact both with reactive oxygen and nitrogen species (hydrogen peroxide, superoxide anion, hydroxyl radical, peroxynitrite and its derivatives). Its antioxidant activity is similar to that of Vitamin E while higher than other hydrophilic antioxidants, such as trolox and N-acetylcysteine. Full article
(This article belongs to the Special Issue Antioxidants)
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589 KiB  
Article
Genetic Diversity and Phylogeny of Antagonistic Bacteria against Phytophthora nicotianae Isolated from Tobacco Rhizosphere
by Fengli Jin, Yanqin Ding, Wei Ding, M.S. Reddy, W.G. Dilantha Fernando and Binghai Du
Int. J. Mol. Sci. 2011, 12(5), 3055-3071; https://doi.org/10.3390/ijms12053055 - 12 May 2011
Cited by 49 | Viewed by 12137
Abstract
The genetic diversity of antagonistic bacteria from the tobacco rhizosphere was examined by BOXAIR-PCR, 16S-RFLP, 16S rRNA sequence homology and phylogenetic analysis methods. These studies revealed that 4.01% of the 6652 tested had some inhibitory activity against Phytophthora nicotianae. BOXAIR-PCR analysis revealed [...] Read more.
The genetic diversity of antagonistic bacteria from the tobacco rhizosphere was examined by BOXAIR-PCR, 16S-RFLP, 16S rRNA sequence homology and phylogenetic analysis methods. These studies revealed that 4.01% of the 6652 tested had some inhibitory activity against Phytophthora nicotianae. BOXAIR-PCR analysis revealed 35 distinct amplimers aligning at a 91% similarity level, reflecting a high degree of genotypic diversity among the antagonistic bacteria. A total of 25 16S-RFLP patterns were identified representing over 33 species from 17 different genera. Our results also found a significant amount of bacterial diversity among the antagonistic bacteria compared to other published reports. For the first time; Delftia tsuruhatensis, Stenotrophomonas maltophilia, Advenella incenata, Bacillus altitudinis, Kocuria palustris, Bacillus licheniformis, Agrobacterium tumefaciens and Myroides odoratimimus are reported to display antagonistic activity towards Phytophthora nicotianae. Furthermore, the majority (75%) of the isolates assayed for antagonistic activity were Gram-positives compared to only 25% that were Gram-negative bacteria. Full article
(This article belongs to the Section Biochemistry)
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341 KiB  
Article
Immobilization of Glucose Oxidase in Alginate-Chitosan Microcapsules
by Xia Wang, Ke-Xue Zhu and Hui-Ming Zhou
Int. J. Mol. Sci. 2011, 12(5), 3042-3054; https://doi.org/10.3390/ijms12053042 - 11 May 2011
Cited by 64 | Viewed by 10693
Abstract
In order to improve its stability and catalytic rate in flour, the immobilization of glucose oxidase (GOX) was investigated in this work. The enzyme was encapsulated in calcium alginate-chitosan microspheres (CACM) using an emulsification-internal gelation-GOX adsorption‑chitosan coating method. The interaction between alginate and [...] Read more.
In order to improve its stability and catalytic rate in flour, the immobilization of glucose oxidase (GOX) was investigated in this work. The enzyme was encapsulated in calcium alginate-chitosan microspheres (CACM) using an emulsification-internal gelation-GOX adsorption‑chitosan coating method. The interaction between alginate and chitosan was confirmed by infrared spectroscopy (IR). The resultant CACM in wet state, whose morphology was investigated by scanning electron microscopy (SEM), was spherical with a mean diameter of about 26 μm. The GOX load, encapsulation efficiency and activity of the CACM-GOX were influenced by concentration of chitosan, encapsulation time and encapsulation pH. The highest total enzymatic activity and encapsulation efficiency was achieved when the pH of the adsorption medium was near the isoelectric point (pI) of GOX, approximately pH 4.0. In addition, the molecular weight of chitosan also evidently influenced the encapsulation efficiency. Storage stabilities of GOX samples were investigated continuously over two months and the retained activity of CACM-GOX was 70.4%, markedly higher than the 7.5% of free enzyme. The results reveal the great potential of CACM-GOX as a flour improver. Full article
(This article belongs to the Section Materials Science)
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218 KiB  
Communication
Effect of Combined High Pressure and Thermal Treatment on Myofibrillar Proteins Solubilization of Beef Muscle
by Hanjun Ma, Guanghong Zhou, David A. Ledward, Xiaoling Yu and Runshu Pan
Int. J. Mol. Sci. 2011, 12(5), 3034-3041; https://doi.org/10.3390/ijms12053034 - 11 May 2011
Cited by 16 | Viewed by 7549
Abstract
The effects of high pressure (to 600 MPa) at different temperatures (20 to 60 °C) for 20 min on protein solubilization and electrophoretic pattern in beef post-rigor longissimus dorsi muscle were studied. The results showed that protein solubilization increased with increasing temperature, especially [...] Read more.
The effects of high pressure (to 600 MPa) at different temperatures (20 to 60 °C) for 20 min on protein solubilization and electrophoretic pattern in beef post-rigor longissimus dorsi muscle were studied. The results showed that protein solubilization increased with increasing temperature, especially from 40 °C to 60 °C. A regular trend of protein solubilization was found when isolated myofibrils were subjected to high pressure at different temperatures, an increase was observed with increasing pressure up to about 400 MPa, solubility then decreasing to 600 MPa. Electrophoretic profiles showed that myosin light chains and actin thin filaments were sensitive to pressure, and were released from myofibrils subjected to 100 MPa and higher pressures at the different temperatures. Full article
(This article belongs to the Section Biochemistry)
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317 KiB  
Article
Investigations on Inhibitors of Hedgehog Signal Pathway: A Quantitative Structure-Activity Relationship Study
by Ruixin Zhu, Qi Liu, Jian Tang, Huiliang Li and Zhiwei Cao
Int. J. Mol. Sci. 2011, 12(5), 3018-3033; https://doi.org/10.3390/ijms12053018 - 11 May 2011
Cited by 6 | Viewed by 7993
Abstract
The hedgehog signal pathway is an essential agent in developmental patterning, wherein the local concentration of the Hedgehog morphogens directs cellular differentiation and expansion. Furthermore, the Hedgehog pathway has been implicated in tumor/stromal interaction and cancer stem cell. Nowadays searching novel inhibitors for [...] Read more.
The hedgehog signal pathway is an essential agent in developmental patterning, wherein the local concentration of the Hedgehog morphogens directs cellular differentiation and expansion. Furthermore, the Hedgehog pathway has been implicated in tumor/stromal interaction and cancer stem cell. Nowadays searching novel inhibitors for Hedgehog Signal Pathway is drawing much more attention by biological, chemical and pharmological scientists. In our study, a solid computational model is proposed which incorporates various statistical analysis methods to perform a Quantitative Structure-Activity Relationship (QSAR) study on the inhibitors of Hedgehog signaling. The whole QSAR data contain 93 cyclopamine derivatives as well as their activities against four different cell lines (NCI-H446, BxPC-3, SW1990 and NCI-H157). Our extensive testing indicated that the binary classification model is a better choice for building the QSAR model of inhibitors of Hedgehog signaling compared with other statistical methods and the corresponding in silico analysis provides three possible ways to improve the activity of inhibitors by demethylation, methylation and hydroxylation at specific positions of the compound scaffold respectively. From these, demethylation is the best choice for inhibitor structure modifications. Our investigation also revealed that NCI-H466 served as the best cell line for testing the activities of inhibitors of Hedgehog signal pathway among others. Full article
(This article belongs to the Section Physical Chemistry, Theoretical and Computational Chemistry)
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408 KiB  
Article
Optimization of Ultrasound-Assisted Extraction of Anthocyanins from Mulberry, Using Response Surface Methodology
by Tang-Bin Zou, Min Wang, Ren-You Gan and Wen-Hua Ling
Int. J. Mol. Sci. 2011, 12(5), 3006-3017; https://doi.org/10.3390/ijms12053006 - 10 May 2011
Cited by 134 | Viewed by 14659
Abstract
Mulberry is one of the most widely used traditional Chinese medicines. Anthocyanins are the main bioactive components of mulberry, and possess important biological activities, such as antimicrobial, anti-inflammatory and antioxidant activities. This study investigated the ultrasound-assisted extraction (UAE) of anthocyanins from mulberry by [...] Read more.
Mulberry is one of the most widely used traditional Chinese medicines. Anthocyanins are the main bioactive components of mulberry, and possess important biological activities, such as antimicrobial, anti-inflammatory and antioxidant activities. This study investigated the ultrasound-assisted extraction (UAE) of anthocyanins from mulberry by using response surface methodology (RSM). The extraction conditions associated with anthocyanin yield, including extraction solvent, liquid-to-solid rate, temperature and extraction time, are discussed. The optimal conditions obtained by RSM for UAE from mulberry include 63.8% methanol contains 1% (v/v) trifluoroacetic acid (TFA), 43.2 °C temperature, 23.8 (v/w) liquid-to-solid ratio, and 40 min time for the maximum yield (64.70 ± 0.45 mg/g). The results indicated that the UAE can be an effective method for the extraction of some active components from plant materials. Full article
(This article belongs to the Section Biochemistry)
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454 KiB  
Article
Knockdown of Akt Sensitizes Osteosarcoma Cells to Apoptosis Induced by Cisplatin Treatment
by Guoyou Zhang, Ming Li, Xiaodong Zhu, Yushu Bai and Changwei Yang
Int. J. Mol. Sci. 2011, 12(5), 2994-3005; https://doi.org/10.3390/ijms12052994 - 10 May 2011
Cited by 30 | Viewed by 7739
Abstract
Akt plays an important role in the inhibition of apoptosis induced by chemotherapy and other stimuli. We therefore investigated if knockdown of Akt2 promoted drug-induced apoptosis in cultured osteosarcoma cells in vitro. SAOS-2 cells were transfected with Akt2 siRNA. The sensitivity of [...] Read more.
Akt plays an important role in the inhibition of apoptosis induced by chemotherapy and other stimuli. We therefore investigated if knockdown of Akt2 promoted drug-induced apoptosis in cultured osteosarcoma cells in vitro. SAOS-2 cells were transfected with Akt2 siRNA. The sensitivity of the transformed cell line to the chemotherapeutic drug cisplatin was assessed. Reduced expression of Akt2 did not directly inhibit the growth rate of the transfected cells; however, it significantly increased their sensitivity to cisplatin. Knockdown of Akt2, together with cisplatin treatment, promoted the expression of p53 up-regulated modulator of apoptosis (PUMA). It is possible that the augmentation of cisplatin cytotoxicity may be mediated by PUMA activation. The results of this study suggest that knockdown of Akt2 expression may have therapeutic applications in enhancing the efficacy of chemotherapy in patients with osteosarcoma. Full article
(This article belongs to the Section Biochemistry)
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376 KiB  
Article
3D-QSAR Studies on a Series of Dihydroorotate Dehydrogenase Inhibitors: Analogues of the Active Metabolite of Leflunomide
by Shun-Lai Li, Mao-Yu He and Hong-Guang Du
Int. J. Mol. Sci. 2011, 12(5), 2982-2993; https://doi.org/10.3390/ijms12052982 - 10 May 2011
Cited by 10 | Viewed by 7159
Abstract
The active metabolite of the novel immunosuppressive agent leflunomide has been shown to inhibit the enzyme dihydroorotate dehydrogenase (DHODH). This enzyme catalyzes the fourth step in de novo pyrimidine biosynthesis. Self-organizing molecular field analysis (SOMFA), a simple three-dimensional quantitative structure-activity relationship (3D-QSAR) method [...] Read more.
The active metabolite of the novel immunosuppressive agent leflunomide has been shown to inhibit the enzyme dihydroorotate dehydrogenase (DHODH). This enzyme catalyzes the fourth step in de novo pyrimidine biosynthesis. Self-organizing molecular field analysis (SOMFA), a simple three-dimensional quantitative structure-activity relationship (3D-QSAR) method is used to study the correlation between the molecular properties and the biological activities of a series of analogues of the active metabolite. The statistical results, cross-validated rCV2 (0.664) and non cross-validated r2 (0.687), show a good predictive ability. The final SOMFA model provides a better understanding of DHODH inhibitor-enzyme interactions, and may be useful for further modification and improvement of inhibitors of this important enzyme. Full article
(This article belongs to the Section Physical Chemistry, Theoretical and Computational Chemistry)
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743 KiB  
Article
First-Principles Investigation of Ag-Doped Gold Nanoclusters
by Xiao-Dong Zhang, Mei-Li Guo, Di Wu, Pei-Xun Liu, Yuan-Ming Sun, Liang-An Zhang, Yi She, Qing-Fen Liu and Fei-Yue Fan
Int. J. Mol. Sci. 2011, 12(5), 2972-2981; https://doi.org/10.3390/ijms12052972 - 9 May 2011
Cited by 31 | Viewed by 11312
Abstract
Gold nanoclusters have the tunable optical absorption property, and are promising for cancer cell imaging, photothermal therapy and radiotherapy. First-principle is a very powerful tool for design of novel materials. In the present work, structural properties, band gap engineering and tunable optical properties [...] Read more.
Gold nanoclusters have the tunable optical absorption property, and are promising for cancer cell imaging, photothermal therapy and radiotherapy. First-principle is a very powerful tool for design of novel materials. In the present work, structural properties, band gap engineering and tunable optical properties of Ag-doped gold clusters have been calculated using density functional theory. The electronic structure of a stable Au20 cluster can be modulated by incorporating Ag, and the HOMO–LUMO gap of Au20−nAgn clusters is modulated due to the incorporation of Ag electronic states in the HOMO and LUMO. Furthermore, the results of the imaginary part of the dielectric function indicate that the optical transition of gold clusters is concentration-dependent and the optical transition between HOMO and LUMO shifts to the low energy range as the Ag atom increases. These calculated results are helpful for the design of gold cluster-based biomaterials, and will be of interest in the fields of radiation medicine, biophysics and nanoscience. Full article
(This article belongs to the Special Issue Advances in Molecular Electronic Structure Calculations)
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