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1.
J Phys Chem Lett ; 2020 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-32058721

RESUMO

The dielectric strength of cellulose-liquid composites is always about several times higher than that of the cellulose paper and insulating liquids. However, this experimental phenomenon has not yet been demonstrated theoretically. Herein, the spectra characterization, molecular simulation, and wavefunction analysis method provide a new insight that the role of nanoscale interfacial adsorption of cellulose-liquid is exclusive for composites affecting the charge separation which is responsible for the difference in dielectric strength, producing the deep-level traps to seriously hinder electromigration under electric field. Meanwhile, the π conjugation and σ-π hyperconjugation effects enhance the electrical stability of aromatic hydrocarbon insulating liquids. In conclusion, interfacial trap theory can be used to explain the correlation of dielectric strength between cellulose-liquid composites and cellulose paper or dielectric liquids. It can be expected that materials with high dielectric strength can be manufactured according to the fundamental study of interfacial trap theory.

3.
Nat Commun ; 10(1): 1813, 2019 04 18.
Artigo em Inglês | MEDLINE | ID: mdl-31000718

RESUMO

The asparagine (N)-linked Man9GlcNAc2 is required for glycoprotein folding and secretion. Understanding how its structure contributes to these functions has been stymied by our inability to produce this glycan as a homogenous structure of sufficient quantities for study. Here, we report the high yield chemoenzymatic synthesis of Man9GlcNAc2 and its biosynthetic intermediates by reconstituting the eukaryotic lipid-linked oligosaccharide (LLO) pathway. Endoplasmic reticulum mannosyltransferases (MTases) are expressed in E. coli and used for mannosylation of the dolichol mimic, phytanyl pyrophosphate GlcNAc2. These recombinant MTases recognize unique substrates and when combined, synthesize end products that precisely mimic those in vivo, demonstrating that ordered assembly of LLO is due to the strict enzyme substrate specificity. Indeed, non-physiological glycans are produced only when the luminal MTases are challenged with cytosolic substrates. Reconstitution of the LLO pathway to synthesize Man9GlcNAc2 in vitro provides an important tool for functional studies of the N-linked glycoprotein biosynthesis pathway.


Assuntos
Asparagina/metabolismo , Lipopolissacarídeos/biossíntese , Mananas/metabolismo , Manosiltransferases/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Asparagina/química , Retículo Endoplasmático/metabolismo , Glicoproteínas/metabolismo , Glicosilação , Mananas/química , Manosiltransferases/genética , Manosiltransferases/isolamento & purificação , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/isolamento & purificação
4.
Phytomedicine ; 53: 18-27, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30668397

RESUMO

BACKGROUND: Lung cancer is a leading cause of cancer-related death worldwide. Cisplatin-based chemotherapy is the standard treatment for lung cancer, but chemoresistance and adverse effects especially cardiotoxicity limit its efficacy. PURPOSE: The efficacy of combination treatment of dendrobine, a plant alkaloid isolated from Dendrobium nobile, with cisplatin was examined as a possible anti-non-small cell lung cancer strategy. METHODS: The cytotoxicity of dendrobine and cisplatin against A549 lung cancer cells was analyzed by MTT and colony formation assays. Apoptosis was measured by annexin V/PI double staining. Apoptosis-related proteins were assessed by western blotting and qPCR analysis. In vivo efficacy was determined using A549 xenograft in nude mice. JNK and Bim inhibition were achieved by siRNA knockdown and/or chemical inhibition. Cardiotoxicity was assessed by serum creatine phosphokinase activity assay. RESULTS: Dendrobine induced apoptotic cell death through mitochondrial-mediated pathway. Combination treatment of dendrobine with cisplatin showed enhanced cytotoxicity through stimulation of JNK/p38 stress signaling pathways and, consequently, the induction of apoptosis involving pro-apoptotic proteins Bax and Bim. In addition, dendrobine attenuated the body weight reduction and cardiotoxicity induced by cisplatin in nude mice. CONCLUSION: The combination treatment showed enhanced anticancer activity toward non-small cell lung cancer cells without aggravating the cardiotoxic effects of cisplatin suggesting that the combination strategy deserves further investigation for human lung cancer treatment.


Assuntos
Alcaloides/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Neoplasias Pulmonares/tratamento farmacológico , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Células A549 , Alcaloides/administração & dosagem , Animais , Antineoplásicos Fitogênicos/administração & dosagem , Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose/metabolismo , Peso Corporal/efeitos dos fármacos , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Cisplatino/administração & dosagem , Cisplatino/farmacologia , Feminino , Humanos , Neoplasias Pulmonares/patologia , Camundongos Endogâmicos BALB C , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto
5.
Glycobiology ; 28(10): 741-753, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-29939232

RESUMO

In eukaryotes, the biosynthesis of a highly conserved dolichol-linked oligosaccharide (DLO) precursor Glc3Man9GlcNAc2-pyrophosphate-dolichol (PP-Dol) begins on the cytoplasmic face of the endoplasmic reticulum (ER) and ends within the lumen. Two functionally distinguished heteromeric glycosyltransferase (GTase) complexes are responsible for the cytosolic DLO assembly. Alg1, a ß-1, 4 mannosyltransferase (MTase) physically interacts with Alg2 and Alg11 proteins to form the multienzyme complex which catalyzes the addition of all five mannose to generate the Man5GlcNAc2-PP-Dol intermediate. Despite the fact that Alg1 plays a central role in the formation of the multi-MTase has been confirmed, the topological information of Alg1 including the molecular mechanism of membrane association are still poorly understood. Using a combination of bioinformatics and biological approaches, we have undertaken a structural and functional study on Alg1 protein, in which the enzymatic activities of Alg1 and its variants were monitored by a complementation assay using the GALpr-ALG1 yeast strain, and further confirmed by a liquid chromatography-mass spectrometry-based in vitro quantitative assay. Computational and experimental evidence confirmed Alg1 shares structure similarity with Alg13/14 complex, which has been defined as a membrane-associated GT-B GTase. Particularly, we provide clear evidence that the N-terminal transmembrane domain including the following positively charged amino acids and an N-terminal amphiphilic-like α helix domain exposed on the protein surface strictly coordinate the Alg1 orientation on the ER membrane. This work provides detailed membrane topology of Alg1 and further reveals its biological importance at the spatial aspect in coordination of cytosolic DLO biosynthesis.


Assuntos
Membrana Celular/metabolismo , Manosiltransferases/metabolismo , Oligossacarídeos/biossíntese , Saccharomyces cerevisiae/metabolismo , Membrana Celular/química , Manosiltransferases/química , Manosiltransferases/genética , Oligossacarídeos/química , Conformação Proteica , Saccharomyces cerevisiae/citologia
6.
J Agric Food Chem ; 66(27): 7054-7064, 2018 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-29920075

RESUMO

Worldwide, colorectal cancer (CRC) is a deleterious disease causing millions of death annually. 5-Fluorouracil (5-FU) is a first-line chemotherapy for CRC, but chemoresistance and gastrointestinal mucositis limit its efficacy. Polyphenol-rich foods are increasingly popular due to their potential beneficial roles in preventing and treating cancer. Ellagitannins are a group of phenolic compounds commonly found in pomegranate, strawberries, raspberries, etc. The objective of this study was to explore whether ellagitannins from pomegranate (PETs) could ameliorate 5-FU-induced intestinal mucositis and enhance the drug's efficacy against CRC. The results showed that PETs (100 mg/kg) counteracted 5-FU-induced intestinal mucositis in rats. The number of apoptotic cells per crypt was reduced from 1.50 ± 0.21 to 0.85 ± 0.18 ( P < 0.05). Moreover, PETs induced HT-29 CRC cell death through intrinsic apoptosis, as demonstrated by dissipation of mitochondrial membrane potential, increased Bax-to-Bcl-2 ratio, and cleavage of caspase 9 and caspase 3. PETs and 5-FU combination treatments exhibited synergistic cytotoxicity against HT-29 cells with a weighted combination index of 0.3494. PETs (80 µg/mL) and 5-FU (40 µg/mL) treatments for 48 h induced 14.03 ± 0.76% and 16.42 ± 1.15% of HT-29 cells to undergo apoptosis, while the combination treatment further increased apoptosis of cells to 34.00 ± 1.54% ( P < 0.05). Combination treatment of the cells also enhanced S phase cell cycle arrest as compared with PETs or 5-FU monotherapy ( P < 0.05). These results suggest that dietary ellagitannins from pomegranate could alleviate intestinal mucositis in rats induced by 5-FU while enhancing its toxicity against HT-29 cells through potentiation of apoptosis and cell cycle arrest.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Fluoruracila/efeitos adversos , Taninos Hidrolisáveis/farmacologia , Lythraceae/química , Mucosite/tratamento farmacológico , Animais , Antineoplásicos Fitogênicos/administração & dosagem , Antineoplásicos Fitogênicos/farmacologia , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Feminino , Fluoruracila/administração & dosagem , Células HT29 , Humanos , Taninos Hidrolisáveis/administração & dosagem , Taninos Hidrolisáveis/química , Metaloproteinases da Matriz/metabolismo , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mucosite/induzido quimicamente , Mucosite/metabolismo , Ratos , Espécies Reativas de Oxigênio/metabolismo
7.
FASEB J ; 32(5): 2492-2506, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29273674

RESUMO

Asparagine ( N)-linked glycosylation requires the ordered, stepwise synthesis of lipid-linked oligosaccharide (LLO) precursor Glc3Man9GlcNAc2-pyrophosphate-dolichol (Glc3Man9Gn2-PDol) on the endoplasmic reticulum. The fourth and fifth steps of LLO synthesis are catalyzed by Alg2, an unusual mannosyltransferase (MTase) with two different MTase activities; Alg2 adds both an α1,3- and α1,6-mannose onto ManGlcNAc2-PDol to form the trimannosyl core Man3GlcNAc2-PDol. The biochemical properties of Alg2 are controversial and remain undefined. In this study, a liquid chromatography/mass spectrometry-based quantitative assay was established and used to analyze the MTase activities of purified yeast Alg2. Alg2-dependent Man3GlcNAc2-PDol production relied on net-neutral lipids with a propensity to form bilayers. We further showed addition of the α1,3- and α1,6-mannose can occur independently in either order but at differing rates. The conserved C-terminal EX7E motif, N-terminal cytosolic tail, and 3 G-rich loop motifs in Alg2 play crucial roles for these activities, both in vitro and in vivo. These findings provide insight into the unique bifunctionality of Alg2 during LLO synthesis and lead to a new model in which alternative, independent routes exist for Alg2 catalysis of the trimannosyl core oligosaccharide.-Li, S.-T., Wang, N., Xu, X.-X., Fujita, M., Nakanishi, H., Kitajima, T., Dean, N., Gao, X.-D. Alternative routes for synthesis of N-linked glycans by Alg2 mannosyltransferase.


Assuntos
Polissacarídeos Fúngicos/química , Bicamadas Lipídicas/química , Manosiltransferases/química , Modelos Moleculares , Oligossacarídeos/química , Proteínas de Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/enzimologia , Motivos de Aminoácidos , Polissacarídeos Fúngicos/genética , Polissacarídeos Fúngicos/metabolismo , Glicosilação , Bicamadas Lipídicas/metabolismo , Manosiltransferases/genética , Manosiltransferases/metabolismo , Oligossacarídeos/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Relação Estrutura-Atividade
8.
Biochim Biophys Acta Gen Subj ; 1861(1 Pt A): 2934-2941, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27670784

RESUMO

BACKGROUND: Asparagine (N)-linked glycosylation begins with a stepwise synthesis of the dolichol-linked oligosaccharide (DLO) precursor, Glc3Man9GlcNAc2-PP-Dol, which is catalyzed by a series of endoplasmic reticulum membrane-associated glycosyltransferases. Yeast ALG1 (asparagine-linked glycosylation 1) encodes a ß-1, 4 mannosyltransferase that adds the first mannose onto GlcNAc2-PP-Dol to produce a core trisaccharide Man1GlcNAc2-PP-Dol. ALG1 is essential for yeast viability, and in humans mutations in the ALG1 cause congenital disorders of glycosylation known as ALG1-CDG. Alg1 is difficult to purify because of its low expression level and as a consequence, has not been well studied biochemically. Here we report a new method to purify recombinant Alg1 in high yield, and a mass spectral approach for accurately measuring its ß-1, 4 mannosyltransferase activity. METHODS: N-terminally truncated yeast His-tagged Alg1 protein was expressed in Escherichia coli and purified by HisTrap HP affinity chromatography. In combination with LC-MS technology, we established a novel assay to accurately measure Alg1 enzyme activity. In this assay, a chemically synthesized dolichol-linked oligosaccharide analogue, phytanyl-pyrophosphoryl-α-N, N'-diacetylchitobioside (PPGn2), was used as the acceptor for the ß-1, 4 mannosyl transfer reaction. RESULTS: Using purified Alg1, its biochemical characteristics were investigated, including the apparent Km and Vmax values for acceptor, optimal conditions of activity, and the specificity of its nucleotide sugar donor. Furthermore, the effect of ALG1-CDG mutations on enzyme activity was also measured. GENERAL SIGNIFICANCE: This work provides an efficient method for production of Alg1 and a new MS-based quantitative assay of its activity.


Assuntos
Manosiltransferases/metabolismo , Saccharomyces cerevisiae/enzimologia , Sequência de Aminoácidos , Western Blotting , Cromatografia Líquida , Dissacarídeos/química , Dissacarídeos/metabolismo , Eletroforese em Gel de Poliacrilamida , Glicosilação , Manosiltransferases/química , Espectrometria de Massas , Proteínas Mutantes/química , Proteínas Mutantes/isolamento & purificação , Proteínas Mutantes/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação
9.
J Ethnopharmacol ; 150(3): 1062-70, 2013 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-24432369

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Astragaloside IV (As IV) is one of the main effective components isolated from the traditional Chinese medical herb Astragalus membranaceus. The protective effect of Astragalus membranaceus on myocardial hypertrophy has been extensively proved. To test the hypothesis that Astragaloside IV can ameliorate the myocardial hypertrophy and inflammatory effect induced by ß-adrenergic hyperactivity, we carried out in vivo and in vitro experiments. MATERIAL AND METHODS: In in vivo study, the isoproterenol (Iso) (5 mg kg(-1) d(-1)) was used as a model of myocardial hypertrophy by intraperitoneal injection. SD rats were randomly assigned to following six groups: A: the control; B: Iso group; C: Iso plus As IV 20 mg kg(-1) d(-1); D: Iso plus As IV 40 mg kg(-1) d(-1); E: Iso plus As IV 80 mg kg(-1) d(-1); F: Iso plus Propranolol 40 mg kg(-1) d(-1). In in vitro study, cultured neonatal rat cardiomyocytes were pretreated with As IV (3, 10, 30 µ mol L(-1)), Propranolol (2 µ mol L(-1)) and BAY11-7082 (5 µ mol L(-1)) for 30 min, and then incubated with Iso (10 µ mol L(-1)) for 48 h. For the rats in each group, the heart mass index (HMI) and the left ventricular mass index (LVMI) were measured. To measure the transverse diameter of left ventricular myocardial cells (TDM), the hematoxylin-eosin (HE) staining method was applied. In addition, the volume and the total protein content of cardiomyocytes were measured, the mRNA expression of ANP and TLR4 were quantified by RT-PCR, the protein expression of TLR4, IκBα and p65 were quantified by Western blot, and the level of TNF-α and IL-6 were measured by ELISA. RESULTS: In vivo: Comparing the Iso group to the control, the HMI, LVMI, TDM were significantly increased; the protein expression of TLR4 and p65 were increased, while the IκBα were decreased; the expression of ANP, TLR4 mRNA, and TNF-α, IL-6 in serum were significantly increased. These changes could be partly prevented by As IV and Pro. In vitro: the over-expression of the cell size, total protein content could remarkably down-regulated by As IV and Pro, and the results of RT-PCR, Western blot and ELISA were similar to those of in vivo. CONCLUSIONS: The results of these studies indicate that Astragaloside IV has good protective effect on myocardial hypertrophy induced by isoproterenol. More specifically, the cardioprotection is related to inhibiting the TLR4/NF-кB signaling pathway and the attenuating inflammatory effect.


Assuntos
Anti-Inflamatórios/farmacologia , Cardiotônicos/farmacologia , Hipertrofia Ventricular Esquerda/metabolismo , NF-kappa B/antagonistas & inibidores , Saponinas/farmacologia , Receptor 4 Toll-Like/antagonistas & inibidores , Triterpenos/farmacologia , Animais , Anti-Inflamatórios/uso terapêutico , Cardiotônicos/uso terapêutico , Células Cultivadas , Hipertrofia Ventricular Esquerda/induzido quimicamente , Hipertrofia Ventricular Esquerda/tratamento farmacológico , Interleucina-6/metabolismo , Isoproterenol , Masculino , Miocárdio/metabolismo , Miocárdio/patologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , NF-kappa B/metabolismo , Ratos , Ratos Sprague-Dawley , Saponinas/uso terapêutico , Transdução de Sinais , Receptor 4 Toll-Like/genética , Receptor 4 Toll-Like/metabolismo , Triterpenos/uso terapêutico , Fator de Necrose Tumoral alfa/metabolismo
10.
J Chem Phys ; 137(15): 154702, 2012 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-23083179

RESUMO

The surface electrostatic potential of raw nanodiamonds is implied to be altered permanently during in the spontaneously occurred graphitization process by recent reports. With all-electron ab initio density functional theory methods, the intrinsic effect of graphitization on the electrostatic potential of nanodiamonds is investigated. It is exposed that while the graphitization process goes on, the dangling bonds on the (111) surface transfer into the inner side and subsequently the surface potential changes from negative to positive. Our results may be of great help in understanding the various electrostatic properties of nanodiamonds.

11.
Inorg Chem ; 51(21): 11223-5, 2012 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-23046342

RESUMO

Quantum-chemical calculations reveal that metallic carbide endohedral fullerene Y(2)C(2)@C(84) possesses a novel fullerene cage, C(1)(51383)-C(84), with one pair of pentagon adjacencies. One of the encapsulated yttrium atoms is located on the adjacent pentagons, while the other stays on a hexagonal ring in the fullerene cage. As one of numerous metallic carbide endohedral fullerenes, Y(2)C(2)@C(1)(51383)-C(84) is the first example that violates the well-known isolated pentagon rule (IPR). More interestingly, compared with the fact that Sc(2)C(2)@C(84) has a conventional IPR-satisfying cage, D(2d)(51591)-C(84), Y(2)C(2)@C(84) utilizes the novel fullerene cage C(1)(51383)-C(84) with one pair of pentagon adjacencies.

12.
Dalton Trans ; 41(17): 5294-300, 2012 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-22415172

RESUMO

By means of density functional theory and statistical mechanics, we investigate the geometric and electronic structures, thermodynamic stability and infrared (IR) vibrational frequencies of alkaline earth metal endohedral fullerenes, M@C(76) (M = Ca, Sr, and Ba). The results reveal that M@C(1)(17,459)-C(76) possesses the lowest energy followed by M@C(2v)(19,138)-C(76) with a very small energy difference. Both the structures have a pair of adjacent pentagons and are related by a single Stone-Wales transformation. Equilibrium statistical thermodynamic analyses based on Gibbs energy treatments suggest that M@C(1)(17,459)-C(76) has a prominent thermodynamic stability at higher temperatures, in contrast with M@C(2v)(19,138)-C(76) whose thermodynamic stability is affected by the encapsulated metal atom. The encapsulated metallic atoms as well as cage structures significantly influence the electronic properties of endohedral fullerenes such as electron affinities and ionization potentials. On the other hand, the singlet-triplet splitting energy ΔE(S-T) depends on the cage structures. In addition, IR spectra and chemical shifts of these compounds have been computed to assist further experimental characterization.

13.
Appl Microbiol Biotechnol ; 90(1): 369-76, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21181155

RESUMO

Changes of microbial characteristics in a full-scale submerged membrane bioreactor system (capacity, 60,000 m(3) day(-1)) treating sewage were monitored over the start-up period (96 days). Fluorescence in situ hybridization analysis showed that the percentages of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (nitrobacter-related population) in total bacteria counted with DAPI staining increased significantly from 1.9% and 0.9% to 4.5% and 2.8%, corresponding to an increase of the specific ammonium oxidizing rate (from 0.06 to 0.12 kg N kg(-1) mixed liquor suspended solids (MLSS) per day) and the specific nitrate forming rate (from 0.05 to 0.10 kg N kg(-1) MLSS day(-1)). Both the denaturing gradient gel electrophoresis of polymerase chain reaction and clone library results showed that the AOB was dominated by the genus Nitrosomonas, the diversity of which increased markedly with operational time. Most of the day 2 clones were closely related with the uncultured Nitrosomonas sp. clone Ninesprings-49S amoA gene (AY356450.1) originated from activated sludge, while the day 96 clone library showed a more diverse distribution characterized by the appearance of the oligotrophic nitrifiers like the Nitrosomonas oligotropha- and Nitrosomonas ureae-like bacteria, perhaps due to the interception by membrane and the low food-to-microorganisms ratio environment. The above results show that the membrane bioreactor system was characterized by the increased diversity and percentage of nitrifiers, which made it possible to achieve a stable and high efficient nitrification. Ammonia-oxidizing archaea with the changing population structures were also detected, but their roles for ammonia oxidation in the system need further studies.


Assuntos
Bactérias/isolamento & purificação , Bactérias/metabolismo , Reatores Biológicos/microbiologia , Nitritos/metabolismo , Esgotos/microbiologia , Amônia/metabolismo , Bactérias/classificação , Bactérias/genética , Dados de Sequência Molecular , Nitratos/metabolismo , Nitrificação , Nitrosomonas/classificação , Nitrosomonas/genética , Nitrosomonas/isolamento & purificação , Nitrosomonas/metabolismo , Oxirredução , Filogenia
14.
J Chem Phys ; 123(20): 204315, 2005 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-16351264

RESUMO

Various structural possibilities for Al(n)B(m) (n=1-7, m=1-2) neutral isomers were investigated using B3LYP6-311G(d) and CCSD(T)6-311G(d) methods. Our calculations predicted the existence of a number of previously unknown isomers. The B atom favors to locate over/inside of all clusters in this series. All structures of the Al(n)B (n=2-7) may be derived from capping/putting a B atom over/inside the Al(n) cluster. All Al(n)B(2) (n=1-5) may be understood as two substitutions of Al atoms by B atoms in the Al(n+2) molecule. The strong B-B bond is a dominant factor in the building-up principle of mixed Al(n)B(2) neutral clusters. The second difference in energy showed that the Al(n)B(m) clusters with even n+m are more stable than those with odd n+m. Our results and analyses revealed that the mixed Al-B clusters exhibit aromatic behaviors.

15.
Sichuan Da Xue Xue Bao Yi Xue Ban ; 35(4): 528-31, 2004 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-15291119

RESUMO

OBJECTIVE: To investigate the effects of the proprietary Chinese Medicine "anti-hepatic-fibrosis 268" on hepatic fibrosis and the related mechanisms. METHODS: The model of CCl4-induced hepatic damage was established in SD rats. 54 male rats were divided into four groups, namely high dose and low dose "anti-hepatic-fibrosis 268" groups, colchicine control group, and model control group. Using Masson stain and light microscope, the authors examined the rats' hepatic tissues and counted the hepatic fiber components, then examined and counted TGF-beta1, alpha-SMA, FN, Type I, III collagen by means of immunohistochemical technique. The groups were compared and the internal relationships of the data were analyzed. RESULTS: The levels of FN, LN, Type I and III collagen, TGF-beta1, and alpha-SMA of the CCl4 damaged rats increased (P<0.01). After 3 weeks of high dose "anti-hepatic-fibrosis 268" treatment, the levels of TGF-beta1, alpha-SMA, FN, LN, Type I and III collagen decreased (P<0.01) and the degree hepatic fibrosis took a favorable turn significantly (P<0.05) as compared with the model control. In the rats of the low dose group, the levels of TGF-beta1, alpha-SMA, FN, Type III collagen significantly decreased (P<0.05), the levels of LN, Type I collagen were not different from the model control; The hepatic fibrosis improved to a certain extent (P<0.05). CONCLUSION: The mechanism of reversing hepatic fibrosis by "anti-hepatic-fibrosis 268" in this experiment is that the medicine regulates TGF-beta1 and further affects alpha-SMA, thus resulting in the decline of FN, Type I, III collagen levels in liver extracellular matrix.


Assuntos
Actinas/metabolismo , Medicamentos de Ervas Chinesas/farmacologia , Cirrose Hepática Experimental/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Animais , Astrágalo (Planta) , Intoxicação por Tetracloreto de Carbono/complicações , Colágeno Tipo I/metabolismo , Colágeno Tipo III/metabolismo , Fibronectinas/metabolismo , Fígado/patologia , Cirrose Hepática Experimental/induzido quimicamente , Cirrose Hepática Experimental/patologia , Masculino , Ratos , Ratos Sprague-Dawley , Fator de Crescimento Transformador beta1
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