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1.
J Nanosci Nanotechnol ; 16(6): 6185-92, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27427688

RESUMO

A novel amperometric sensor based on iron doped hydroxyapatite (Fe-HA) and multiwalled carbon nanotubes (CNT) composite immobilized on a glassy carbon electrode (GCE) has been fabricated. The hybrid composite made of Fe-HA nanoparticles and CNT promotes electron transfer kinetics between the analyte levodopa (L-dopa) and the modified GC electrode. Under optimum conditions, the fabricated sensor gave a linear response range of 1.0 x 10(-7)-1.1 x 10(-6) M with the detection limit as low as 62 nM. The Fe-HA/CNT modified electrode showed good selectivity towards the determination of L-dopa in the presence of ascorbic acid (AA), uric acid (UA) and other common interferents. The sensor displays a high sensitivity, good reproducibility and long-term stability and it was successfully applied for the detection of L-dopa in pharmaceutical and medicinal plant samples.


Assuntos
Durapatita/química , Eletroquímica/instrumentação , Ferro/química , Levodopa/análise , Nanotubos de Carbono/química , Ácido Úrico/química , Catálise , Eletrodos , Vidro/química , Levodopa/química , Limite de Detecção , Mucuna/química , Oxirredução
2.
Analyst ; 138(7): 2061-7, 2013 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-23397580

RESUMO

We report the fabrication and testing of a riboflavin (RF) biosensor based on the use of Cr doped SnO2 nanoparticles. The Cr-SnO2 nanoparticles with chromium concentration from 0 to 5 wt% were synthesised by a microwave irradiation method. Magnetic studies revealed that only 3 wt% Cr doped nano-SnO2 has ferromagnetic behaviour at room temperature. This Cr-SnO2 nanoparticles modified electrode responded to RF linearly over a concentration range of 0.2 × 10(-6) to 1.0 × 10(-4) M with a detection limit of 107 nM. The fabricated sensor showed an excellent anti-interference ability against electroactive species and metal ions and proved to be useful for the estimation of the RF content in pharmaceutical samples with satisfactory recovery.


Assuntos
Técnicas Biossensoriais/métodos , Cromo/química , Nanopartículas Metálicas , Preparações Farmacêuticas/química , Riboflavina/análise , Compostos de Estanho/química , Limite de Detecção
3.
J Colloid Interface Sci ; 633: 120-131, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36436346

RESUMO

The design and construction of state-of-the-art wearable thermoelectric materials are important for the development of self-powered wearable thermoelectric generators (WTEGs). Molybdenum disulfide (MoS2) has been reported as a noteworthy thermoelectric (TE) material because of its large intrinsic bandgap and high carrier mobility. In this work, Cu-doped two-dimensional layered MoS2 nanosheets were grown on carbon fabric (CF) via a hydrothermal method. The electrical conductivity, Seebeck coefficient, and power factor for the Cu-doped MoS2 were found to increase with increasing temperature. The maximum Seebeck coefficient was obtained for a MoS2 sample doped with 4 at% of Cu (CM4) was ∼10 µV/K at 303 K and ∼13 µV/K at 373 K. The enhancement in the Seebeck coefficient was attributed to an energy-filtering effect caused by the interfacial barrier between MoS2 and Cu. In addition, a thermoelectric device was designed with four pairs of TE materials, where CM4 (4 at%) was used as a p-type material and Cu wire was used as an n-type material. These p- and n-type materials were connected electrically in series and thermally in parallel to generate a voltage of 190.7 µV at a temperature gradient of 8 K.

4.
Chemosphere ; 288(Pt 1): 132236, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34649090

RESUMO

Hierarchical orderd macroporous TiO2 architecture (HOMTA) was prepared with aid of ethylenediamine (EDA) and investigated the impact of amine molecules on the properties of TiO2 architecture. The different variation of amine molecules (EDA) leads to tunning the morphology under hydrothermal approach which is confirmed by FESEM and TEM analysis. The XRD and Raman studies confirms the crystal structure of anatase and brookite phase of TiO2. The surface of the architecture strongly depended on the concentration of EDA which plays a vital role in surface area which is revealed by Brunauer Emmett-Teller (BET) analysis. The obtained HOMTA was employed as photocatalyst and active photoanode in the dye sensitized solar cells (DSSC). The DSSC device exhibits excellent efficiency (η) of 5.27% for the EDA capped TiO2 (S5) which had high surface area (167.11 m2/g) for better dye loading, whereas the lower concentration of EDA capped TiO2 (S1, S2, S3 and S4) resulted the efficiency of 2.14, 3.90, 3.25 and 4.37%, respectively. The efficiency of photocatlysis degradation of the prepared samples (S1, S2, S3, S4 and S5) was 94.8, 90.47, 91.41, 91.32 and 93.75% under light source. The excellent photocatalysis property was achieved by S5 within 6 min due to high surface area which inducing more active site.


Assuntos
Recuperação e Remediação Ambiental , Titânio , Corantes , Luz Solar
5.
Nat Med ; 7(1): 94-100, 2001 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11135622

RESUMO

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in various tumor cells in vitro, but its physiological role in tumor surveillance remains unknown. Here, we report that TRAIL is constitutively expressed on murine natural killer (NK) cells in the liver and plays a substantial role in suppressing tumor metastasis. Freshly isolated NK cells, but not natural killer T cells or ordinary T cells, from the liver expressed cell surface TRAIL, which was responsible for spontaneous cytotoxicity against TRAIL-sensitive tumor cells in vitro along with perforin and Fas ligand (FasL). Administration of neutralizing monoclonal antibody against TRAIL significantly increased experimental liver metastases of several TRAIL-sensitive tumor cell lines. Such an anti-metastatic effect of TRAIL was not observed in NK cell-depleted mice or interferon-gamma-deficient mice, the latter of which lacked TRAIL on liver NK cells. These findings provide the first evidence for the physiological function of TRAIL as a tumor suppressor.


Assuntos
Apoptose/fisiologia , Células Matadoras Naturais/imunologia , Fígado/imunologia , Glicoproteínas de Membrana/fisiologia , Metástase Neoplásica/imunologia , Fator de Necrose Tumoral alfa/fisiologia , Animais , Proteínas Reguladoras de Apoptose , Ligantes , Fígado/citologia , Neoplasias Hepáticas Experimentais/secundário , Masculino , Camundongos , Camundongos Endogâmicos , Ligante Indutor de Apoptose Relacionado a TNF
6.
J Colloid Interface Sci ; 584: 295-309, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33069028

RESUMO

The hybrid of organic conducting polymers and inorganic materials with ultralow thermal conductivity, which is a promising strategy for the realization of polymer based effective thermoelectric (TE) applications. In this work, ultrathin layered molybdenum disulphide (MoS2) nanosheets/PANI nanocomposites are prepared by hydrothermal route. The effect of varying PANI wt% in the nanocomposites and its interface effect on thermoelectric properties are well investigated. The successful incorporation of PANI between the MoS2 layers confirmed by high resolution transmission electron microscope (HRTEM). The significantly enhanced potential difference of MoS2/ PANI nanocomposites with increasing PANI content is well clarified by the increased Seebeck value. The variable range hopping property is identified and conductivity is raised up highly due to insertion of PANI in layered van der Waal's gap of MoS2. The effective interface facilitates charge for fast transport. The reduced thermal conductivity is observed of about 0.248 W*m-1*K-1 for 2.5 wt% addition of PANI. The key factor is that the stability of the sample is improved for MoS2/ PANI nanocomposites than pristine MoS2. Our work paved a new approach to improve TE performance by preparing TE MoS2 material through simple chemical route.

7.
Dis Esophagus ; 23(7): 565-71, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20353442

RESUMO

The objective of the study was to evaluate the efficacy of sivelestat, a selective neutrophil elastase inhibitor, on body fluid balance after transthoracic esophagectomy. Esophagectomy with elective lymphadenectomy may induce excessive release of neutrophil elastase, which then promotes vascular permeability and an excessive water shift from the intravascular space to the peripheral compartment. Body fluid imbalance after esophagectomy often leads to circular instability, a decrease of urine output, and a delay in the shift to a diuretic state. The study was designed as a case-control study with a historical control group. A retrospective analysis was performed to examine our hypothesis that sivelestat improves abnormal body fluid retention and prevents subsequent pulmonary complications. To reveal the direct influence of sivelestat on the postoperative course, we avoided using steroids or other diuretic agents. Eighty-eight patients who underwent thoracic esophagectomy with extended lymphadenectomy from 2000 to 2008 were divided into two groups: those treated from 2003 to 2008, who all received postoperative administration of sivelestat (n=60); and those treated from 2000 to 2002, who did not receive sivelestat and were used as the control group (n=28). Both groups received fluid management using the same protocol. The time to reach a diuretic state, time until extubation of the tracheal tube, and development of delayed respiratory dysfunction were compared between the groups using univariate and multivariate analysis. The time until a shift to a diuretic state was significantly shorter after treatment with sivelestat (p<0.0001) and with a shorter operation time (p<0.0001). The tracheal tube was extubated significantly earlier in the sivelestat group (p<0.0001) and the incidence of delayed respiratory dysfunction was also significantly lower (p=0.0028) in this group. Multivariate logistic regression analysis showed that a delay in a shift to a diuretic state was a strong independent risk factor for the time to tracheal extubation (odds ratio 2.539, p=0.0056) and occurrence of delayed respiratory dysfunction (odds ratio 1.989, p=0.0104). Sivelestat treatment was not independently associated with reduced pulmonary complications, but the diuretic state was strongly regulated by sivelestat treatment (odds ratio 0.044, p=0.0003). Thus, administration of sivelestat has a beneficial influence on recovery from body water imbalance through a more rapid return to a diuretic state after esophagectomy, which contributes to prevention of subsequent pulmonary complications.


Assuntos
Esofagectomia/efeitos adversos , Proteínas Secretadas Inibidoras de Proteinases/uso terapêutico , Desequilíbrio Hidroeletrolítico/tratamento farmacológico , Desequilíbrio Hidroeletrolítico/etiologia , Idoso , Esofagectomia/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Recuperação de Função Fisiológica , Estudos Retrospectivos
8.
Acta Crystallogr Sect E Struct Rep Online ; 66(Pt 2): o355, 2010 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-21579781

RESUMO

Mol-ecules of the title compound, C(11)H(15)NO(2), are essentially planar (r.m.s. deviation = 0.035 Å) and are linked into a chain along the a axis by weak C-H⋯O hydrogen bonds.

9.
Mater Sci Eng C Mater Biol Appl ; 108: 110457, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31924033

RESUMO

Titanium dioxide nanoparticles exhibit good anticancer and antibacterial activities. They are known to be environmentally friendly and stable, less toxic and excellent biocompatibility nature. In this paper we report the biological properties of pure TiO2 nanoparticles modified with Withania somnifera (Ashwagandha), Eclipta prostrata (Karisalankanni) and Glycyrrhiza glabra (Athimathuram) for biological applications. X-ray diffraction results revealed the anatase nature of the samples. From the TEM analyses, it is observed that there is an increase in the particle size of the bio modified samples. UV results show the red shift for the bio modified samples when compared with the pure samples. The samples are then subjected to MTT assay to determine the cell viability. KB oral cancer cells are used for the determination of anticancer nature of the pure and bio modified nanoparticles. It is observed that Withania somnifera - Eclipta prostrate modified TiO2 nanoparticles exhibit excellent anticancer activities among other bio modified and pure samples. The samples are then examined for their antibacterial activities against three Gram-negative bacterial strains namely, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and two Gram-positive bacterial strains namely, Staphylococcus aureus and Streptococcus mutans. Among the modified and pure samples, Withania somnifera - Eclipta prostrata showed good antibacterial nature against Gram-positive and Gram-negative bacteria.


Assuntos
Antibacterianos , Antineoplásicos , Bactérias/crescimento & desenvolvimento , Eclipta/química , Glycyrrhiza/química , Neoplasias Bucais , Nanopartículas/química , Titânio/química , Withania/química , Antibacterianos/síntese química , Antibacterianos/química , Antibacterianos/farmacocinética , Antibacterianos/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/farmacocinética , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Humanos , Neoplasias Bucais/tratamento farmacológico , Neoplasias Bucais/metabolismo , Neoplasias Bucais/patologia
10.
J Appl Microbiol ; 107(4): 1367-74, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19426274

RESUMO

AIMS: To investigate the clonality of Staphylococcus aureus isolates, it is important to identify their clonal complexes (CCs) with multilocus sequence typing (MLST). However, it is expensive to carry out MLST analyses for many isolates. The aim of this study, therefore, was to develop a cost-effective method to identify CCs by determining the conservation pattern of 'small genomic islets' (SGIs). SGIs are nonconserved regions between strains and have single or multiple open-reading frames (ORFs). METHODS AND RESULTS: The whole-genome sequences of nine strains were compared in order to select 16 SGIs. The conservation patterns of the 16 SGIs (islet patterns) were investigated in 136 S. aureus isolates, which were classified into 21 CCs. The islet patterns (IPs) exhibited a one-to-one correspondence with the CCs, except for isolates belonging to CC1, CC5 and CC8. The IPs typical of strains belonging to CC1, CC5 and CC8 differed between those of sequence type 1 (ST1) and ST188 (CC1), ST5 and ST6 (CC5) and ST8 and ST239 (CC8). SIGNIFICANCE AND IMPACT OF THE STUDY: The CCs of many isolates can be identified in an easy and inexpensive manner by detecting these 16 SGIs. Emergent clones, particularly methicillin-resistant ones, can be identified by examining numerous islets by IP analysis.


Assuntos
Técnicas de Tipagem Bacteriana , Ilhas Genômicas/genética , Staphylococcus aureus/genética , Primers do DNA/genética , DNA Bacteriano/genética , Humanos , Staphylococcus aureus Resistente à Meticilina , Análise de Sequência de DNA , Staphylococcus aureus/isolamento & purificação
12.
Oncogene ; 26(41): 6038-49, 2007 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-17384676

RESUMO

In the previous study, we demonstrated the involvement of dual specificity phosphatase 22 (DUSP22/LMW-DSP2) in regulating the leukemia inhibitory factor/interleukin-6/signal transducer and activator of transcription 3-mediated signaling pathway. In this study, we show beta-estradiol (E2)-induced DUSP22 mRNA expression in estrogen receptor alpha (ERalpha)-positive breast cancer cells, whereas E2-induced phosphorylation and activation of ERalpha was suppressed by overexpression of DUSP22 but not catalytically inactive mutants. Furthermore, small-interfering RNA-mediated reduction of DUSP22 expression enhanced ERalpha-mediated transcription and endogenous gene expression. In fact, DUSP22 associated with ERalpha in vivo and both endogenous proteins interacted in ERalpha-positive breast cancer T47D cells. These results strongly suggest that DUSP22 acts as a negative regulator of the ERalpha-mediated signaling pathway.


Assuntos
Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Receptor alfa de Estrogênio/fisiologia , Fosfoproteínas Fosfatases/genética , Fosfosserina/metabolismo , Proteínas Tirosina Fosfatases/genética , Ativação Transcricional/fisiologia , Fosfatases de Especificidade Dupla , Estradiol/farmacologia , Receptor alfa de Estrogênio/efeitos dos fármacos , Feminino , Células HeLa , Humanos , Fosfatases da Proteína Quinase Ativada por Mitógeno , Reação em Cadeia da Polimerase , RNA Mensageiro/genética , Transdução de Sinais , Células Tumorais Cultivadas
13.
Obes Sci Pract ; 4(1): 97-105, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29479469

RESUMO

Objective: Previous work has shown that high body mass index (BMI) is associated with low grey matter volume. However, evidence on the relationship between waist circumference (WC) and brain volume is relatively scarce. Moreover, the influence of mild obesity (as indexed by WC and BMI) on brain volume remains unclear. This study explored the relationships between WC and BMI and grey matter volume in a large sample of Japanese adults. Methods: The participants were 792 community-dwelling adults (523 men and 269 women). Brain magnetic resonance images were collected, and the correlation between WC or BMI and global grey matter volume were analysed. The relationships between WC or BMI and regional grey matter volume were also investigated using voxel-based morphometry. Results: Global grey matter volume was not correlated with WC or BMI. Voxel-based morphometry analysis revealed significant negative correlations between both WC and BMI and regional grey matter volume. The areas correlated with each index were more widespread in men than in women. In women, the total area of the regions significantly correlated with WC was slightly greater than that of the regions significantly correlated with BMI. Conclusions: Results show that both WC and BMI were inversely related to regional grey matter volume, even in Japanese adults with somewhat mild obesity. Especially in populations with less obesity, such as the female participants in current study, WC may be more sensitive than BMI as a marker of grey matter volume differences associated with obesity.

14.
RSC Adv ; 8(47): 26664-26675, 2018 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-35541077

RESUMO

Edge-rich active sites of ultrathin layered molybdenum disulphide (MoS2) nanosheets were synthesized by a hydrothermal method. The effect of pH on the formation of MoS2 nanosheets and their photocatalytic response have been investigated. Structural and elemental analysis confirm the presence of S-Mo-S in the composition. Morphological analysis confirms the presence of ultrathin layered nanosheets with a sheet thickness of 10-28 nm at pH 1. The interplanar spacing of MoS2 layers is in good agreement with the X-ray diffraction and high-resolution transmission electron microscopy results. A comparative study of the photocatalytic performance for the degradation of methylene blue (MB) and rhodamine B (RhB) by ultrathin layered MoS2 under visible light irradiation was performed. The photocatalytic activity of the edge-rich ultrathin layered nanosheets showed a fast response time of 36 min with the degradation rate of 95.3% of MB and 41.1% of RhB. The photocatalytic degradation of MB was superior to that of RhB because of the excellent adsorption of MB than that of RhB. Photogenerated superoxide radicals were the key active species for the decomposition of organic compounds present in water, as evidenced by scavenger studies.

15.
J Thromb Haemost ; 5(11): 2219-26, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17958740

RESUMO

BACKGROUND: In a previous study, we found that thrombin induced proliferation of TM-1 and T98G human glioma cells and that the mitogenic effect was abolished by hirudin. OBJECTIVES: We investigated thrombin's effects on the proliferation of A172 human glioblastoma cells and the induction of growth factors. Furthermore, we examined whether or not the expression of heparin cofactor II (HCII) in A172 cells using adenovirus vector could suppress thrombin's effects. METHODS: The effect of thrombin on cell proliferation was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. The amount of growth factors in the conditioned medium was measured by enzyme-linked immunosorbent assay. The level of platelet-derived growth factor (PDGF)-B mRNA was assessed by reverse transcriptase-polymerase chain reaction analysis. RESULTS: Thrombin-induced proliferation of A172 cells primarily depended on the enhanced secretion of PDGF-AB by thrombin. The action of thrombin depended on its proteolytic activity. However, thrombin-induced PDGF-AB secretion was not abolished by anti-protease-activated receptor (PAR) antibody. The PAR-1 agonist peptide had no effect on cell growth and PDGF-AB levels. Thrombin did not increase PDGF-B gene expression. Expression of HCII effectively suppressed thrombin-induced PDGF-AB release. CONCLUSIONS: These results indicate that thrombin may play an important role in the proliferation of A172 cells by inducing PDGF-AB secretion and that thrombin's action is mediated by its proteolytic activity. Inhibition of thrombin's proteolytic activity may be a new therapeutic method for gliomas.


Assuntos
Proliferação de Células/efeitos dos fármacos , Glioblastoma/patologia , Fator de Crescimento Derivado de Plaquetas/metabolismo , Trombina/farmacologia , Linhagem Celular Tumoral , Meios de Cultivo Condicionados/química , Glioblastoma/metabolismo , Cofator II da Heparina/administração & dosagem , Cofator II da Heparina/farmacologia , Humanos , Proteínas Proto-Oncogênicas c-sis/análise , Proteínas Proto-Oncogênicas c-sis/genética , RNA Mensageiro/análise
16.
Dalton Trans ; 45(6): 2637-46, 2016 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-26732466

RESUMO

The two-dimensional (2D) transition metal dichalcogenide nanosheet-carbon composite is an attractive material for energy storage because of its high Faradaic activity, unique nanoconstruction and electronic properties. In this work, a facile one step preparation of a molybdenum disulfide (MoS2) nanosheet-graphene (MoS2/G) composite with the in situ reduction of graphene oxide is reported. The structure, morphology and composition of the pure MoS2 and composites were comparatively analyzed by various characterization techniques. The electrochemical performance of the pure MoS2, graphene oxide and the MoS2/G composite electrode materials was evaluated by cyclic voltammogram, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The MoS2/G composite showed a higher specific capacitance (270 F g(-1) at a current density of 0.1 A g(-1)) compared to the pure MoS2 (162 F g(-1)) in a neutral aqueous electrolyte. Moreover, the energy density of the composite electrode is also higher (12.5 Wh kg(-1)) with a high power density (2500 W kg(-1)) compared to the pure MoS2. In addition, the MoS2/G composite electrode showed excellent cyclic stability even after 1000 cycles. The enhancement in specific capacitance, excellent cyclic stability and high energy density of the composite electrode are mainly due to the interconnected conductive network of the composite as well as the synergetic effect of the pure MoS2 and graphene. The experimental results demonstrated that the MoS2/G composite is a promising electrode material for high-performance supercapacitors.

17.
Biochim Biophys Acta ; 746(1-2): 14-7, 1983 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-6871230

RESUMO

Fat body glycogen phosphorylase in some overwintering insects is known to be activated by cold and, therefore, this enzyme acts as a key enzyme that regulates the production of glycerol or trehalose from glycogen during winter. In this paper we report the mechanism of phosphorylase activation by cold: the major phosphorylase kinase (EC 2.7.1.38) of fat body is bound to glycogen and functions at 0 degrees C, whereas phosphorylase phosphatase does not; thus this may cause a slow but continuous accumulation of the active form of phosphorylase in the cold.


Assuntos
Tecido Adiposo/enzimologia , Cálcio/metabolismo , Temperatura Baixa , Corpo Adiposo/enzimologia , Fosforilase Quinase/metabolismo , Animais , Cátions Bivalentes/farmacologia , Glicogênio/metabolismo , Mariposas
18.
Biochim Biophys Acta ; 929(1): 117-20, 1987 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-3036245

RESUMO

Taurine and the taurine analogue guanidinoethanesulfonic acid interact with octopamine receptors of cockroach hemocytes to decrease octopamine-stimulated cAMP production. Dopamine-, synephrine- and tyramine-stimulated cAMP production in the haemocytes are also inhibited by taurine.


Assuntos
Inibidores de Adenilil Ciclases , Células Sanguíneas/metabolismo , AMP Cíclico/biossíntese , Hemócitos/metabolismo , Octopamina/antagonistas & inibidores , Taurina/farmacologia , Animais , Baratas , Antagonistas de Dopamina , Hemócitos/efeitos dos fármacos , Sinefrina/antagonistas & inibidores , Taurina/análogos & derivados , Tiramina/antagonistas & inibidores
19.
Biochim Biophys Acta ; 1294(2): 177-82, 1996 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-8645736

RESUMO

Quinolidomicin A1, a 60-membered macrolide purified from an actinomycete Micromonospora sp. markedly induced 45Ca2+ release from the heavy fraction of skeletal muscle sarcoplasmic reticulum (HSR), but induced only slightly from the light fraction of sarcoplasmic reticulum (LSR), showing a lack of the ionophoretic activity even at a high concentration (300 microM). This was also confirmed by measuring the 45Ca2+ transport activity of quinolidomicin A1 across an organic solvent barrier. Quinolidomicin A1 (3-300 microM) increased 45Ca2+ release from HSR with an EC50 value of approx. 20 microM. The potency of quinolidomicin A1 was approx. 100-fold higher than that of caffeine. The bell-shaped profile of Ca2+ dependence for quinolidomicin A1 was different from that for caffeine. Blockers of Ca2+ release channels such as Mg2+ (10 mM), procaine (10 mM) and ruthenium red (10 microM) partially blocked quinolidomicin A1 (30 microM)-induced 45Ca2+ release from HSR. At 0 degrees C, quinolidomicin A1-induced 45Ca2+ release was ascertained not to be due to the inhibition of Ca2+ ATPase by the ATPase assay. Quinolidomicin A1 potentiated [3H]ryanodine binding to HSR with a decrease in KD but without a change in Bmax. These results suggest that quinolidomicin A1-induced Ca2+ release from HSR is consisted of two components, which are both sensitive and insensitive to blockers of Ca2+ release channels, and that the former component is associated with the ryanodine receptor.


Assuntos
Antibacterianos/farmacologia , Cálcio/metabolismo , Macrolídeos , Músculo Esquelético/metabolismo , Retículo Sarcoplasmático/metabolismo , Actinomycetales , Análise de Variância , Animais , Antibacterianos/química , Antibacterianos/isolamento & purificação , Antibióticos Antineoplásicos/farmacologia , Transporte Biológico/efeitos dos fármacos , Cafeína/farmacologia , Radioisótopos de Cálcio , Cinética , Estrutura Molecular , Coelhos , Rianodina/metabolismo , Retículo Sarcoplasmático/efeitos dos fármacos
20.
Biochim Biophys Acta ; 1355(3): 241-7, 1997 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-9060995

RESUMO

Calcium spirulan (Ca-SP), a novel sulfated polysaccharide isolated from the blue-green alga Spirulina platensis, has been found to have antiviral and heparin cofactor II-dependent antithrombin activities. We have obtained evidence that Ca-SP is a potent inducer of tissue-type plasminogen activator (t-PA) production. The addition of Ca-SP to a culture of IMR-90 human fetal lung fibroblasts increased t-PA concentrations in the conditioned medium, in a dose- and time-dependent manner, but in the cell lysate, t-PA concentrations were unchanged, suggesting that t-PA induced by Ca-SP is easily secreted into the conditioned medium. The amount of newly synthesized t-PA in IMR-90 cells, as measured by labeling with [35S]methionine and subsequent immunoprecipitation of t-PA from conditioned medium, was significantly increased by Ca-SP-stimulation. However, Ca-SP did not increase the t-PA mRNA levels. As previously reported, thrombin stimulated t-PA gene transcription in IMR-90 cells, and the simultaneous treatment with Ca-SP and thrombin caused further enhancement of t-PA production, in a synergistic manner. It would thus appear that Ca-SP increases t-PA production through post-transcriptional processes. IMR-90 cells also produce plasminogen activator inhibitor type-1 (PAI-1), but Ca-SP showed little effect on the PAI-1 production. H-SP, which was obtained by removing the calcium from Ca-SP, had no effect on the t-PA production. Na-SP, which was prepared by replacement of the calcium with sodium, stimulated the t-PA production similarly to Ca-SP. Thus, Ca-SP specifically induces t-PA production, and the molecular conformation of Ca-SP maintained by Ca or Na may be essential for the stimulation of t-PA synthesis.


Assuntos
Polissacarídeos/farmacologia , Ativador de Plasminogênio Tecidual/biossíntese , Northern Blotting , Linhagem Celular , Meios de Cultivo Condicionados , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Feto , Fibroblastos , Humanos , Pulmão , Inibidor 1 de Ativador de Plasminogênio/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Trombina/farmacologia , Ativador de Plasminogênio Tecidual/genética
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