Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 17 de 17
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Nanotechnology ; 27(49): 495101, 2016 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-27834307

RESUMO

Danshen (Salvia miltiorrhiza), a Chinese medicinal herb, consists of several functional components including tanshinones responsible for prevention of several chronic diseases. This study intends to prepare tanshinone extract and nanoemulsion from danshen and determine their inhibition effect on lung cancer cells A549. A highly stable tanshinone nanoemulsion composed of Capryol 90, Tween 80, ethanol and deionized water with the mean particle size of 14.2 nm was successfully prepared. Tanshinone nanoemulsion was found to be more effective in inhibiting A549 proliferation than tanshinone extract. Both nanoemulsion and extract could penetrate into cytoplasm through endocytosis, with the former being more susceptible than the latter. A dose-dependent response in up-regulation of p-JNK, p53 and p21 and down-regulation of CDK2, cyclin D1 and cyclin E1 expressions was observed with the cell cycle arrested at G0/G1 phase. The cellular microcompartment change of A549 was also investigated. The study demonstrated that tanshinone nanoemulsion may be used as a botanic drug for treatment of lung cancer.


Assuntos
Nanoestruturas , Células A549 , Abietanos , Ciclo Celular , Emulsões , Humanos , Neoplasias Pulmonares , Salvia miltiorrhiza
2.
Osteoarthritis Cartilage ; 23(8): 1307-15, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25891750

RESUMO

OBJECTIVE: In healthy joints, a zone of calcified cartilage (ZCC) provides the mechanical integration between articular cartilage and subchondral bone. Recapitulation of this architectural feature should serve to resist the constant shear force from the movement of the joint and prevent the delamination of tissue-engineered cartilage. Previous approaches to create the ZCC at the cartilage-substrate interface have relied on strategic use of exogenous scaffolds and adhesives, which are susceptible to failure by degradation and wear. In contrast, we report a successful scaffold-free engineering of ZCC to integrate tissue-engineered cartilage and a porous biodegradable bone substitute, using sheep bone marrow stromal cells (BMSCs) as the cell source for both cartilaginous zones. DESIGN: BMSCs were predifferentiated to chondrocytes, harvested and then grown on a porous calcium polyphosphate substrate in the presence of triiodothyronine (T3). T3 was withdrawn, and additional predifferentiated chondrocytes were placed on top of the construct and grown for 21 days. RESULTS: This protocol yielded two distinct zones: hyaline cartilage that accumulated proteoglycans and collagen type II, and calcified cartilage adjacent to the substrate that additionally accumulated mineral and collagen type X. Constructs with the calcified interface had comparable compressive strength to native sheep osteochondral tissue and higher interfacial shear strength compared to control without a calcified zone. CONCLUSION: This protocol improves on the existing scaffold-free approaches to cartilage tissue engineering by incorporating a calcified zone. Since this protocol employs no xenogeneic material, it will be appropriate for use in preclinical large-animal studies.


Assuntos
Células da Medula Óssea/citologia , Calcificação Fisiológica/fisiologia , Cartilagem Hialina/fisiologia , Células Estromais/citologia , Engenharia Tecidual/métodos , Animais , Técnicas de Cultura de Células/métodos , Diferenciação Celular , Colágeno Tipo II/fisiologia , Colágeno Tipo X/fisiologia , Proteoglicanas/fisiologia , Ovinos , Tri-Iodotironina/farmacologia
3.
Placenta ; 32(3): 269-76, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21300404

RESUMO

Term placenta is a great reservoir of mesenchymal stem cells (MSCs), however, the potential of the earlier placenta is largely unknown. In this report, we established 17 MSC lines from 19 first-trimester human placenta (fPMSC). fPMSC proliferated for 90-150 days in vitro and by enhanced cellular interaction, fPMSC differentiated into nestin-expressing neural progenitor cells (fPMSC-NP), accompanied by inductions of immature neuron-specific genes. Therapeutic effect of the fPMSC-NP was tested in the animal model of hypoxia-ischemia (HI) which was devastating to dopaminergic neurons and to locomotor activity. Improvement of motor activity was evident as early as 2 weeks after transplantation of the fPMSC-NP into bilateral striatum and became indistinguishable from that of the age-matched normal animals by 8 weeks but no spontaneous recovery was observed in the control-grafted animals. Immunohistochemical analyses revealed that the implanted fPMSC-NP matured into ectodermal cells including the tyrosine hydroxylase (TH)-expressing neurons in the recipient striatum. So, the improved motor behavior was likely due to the dopaminergic differentiation of the implanted fPMSC-NP in the dopaminergic-denervated host brain. Based on this result, we propose that progenitors may be more advantageous than the terminally differentiated cells for the purpose of cell replacement therapies since the progenitors are easily obtainable and are expected to be more pliable to the new environment.


Assuntos
Diferenciação Celular/fisiologia , Hipóxia-Isquemia Encefálica/fisiopatologia , Células-Tronco Mesenquimais/fisiologia , Células-Tronco Neurais/fisiologia , Placenta/fisiologia , Animais , Animais Recém-Nascidos , Feminino , Humanos , Proteínas de Filamentos Intermediários/genética , Proteínas de Filamentos Intermediários/fisiologia , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Mesenquimais/citologia , Atividade Motora/fisiologia , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/fisiologia , Nestina , Células-Tronco Neurais/citologia , Placenta/citologia , Gravidez , Primeiro Trimestre da Gravidez , RNA Mensageiro/química , RNA Mensageiro/genética , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase Via Transcriptase Reversa
4.
Phys Rev Lett ; 91(20): 205003, 2003 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-14683369

RESUMO

Anomalous momentum transport has been observed in Alcator C-Mod tokamak plasmas through analysis of the time evolution of core impurity toroidal rotation velocity profiles. Following the L-mode to EDA (enhanced D(alpha)) H-mode transition, the ensuing cocurrent toroidal rotation velocity, which is generated in the absence of any external momentum source, is observed to propagate in from the edge plasma to the core. The steady state toroidal rotation velocity profiles are relatively flat and the momentum transport can be simulated with a simple diffusion model. Velocity profiles during edge localized mode free (ELM-free) H-modes are centrally peaked, which suggests the addition of inward momentum convection. In all operating regimes the observed momentum diffusivities are much larger than the neoclassical values.

5.
Science ; 293(5531): 825-8, 2001 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-11452082

RESUMO

Microwave atomic clocks have been the de facto standards for precision time and frequency metrology over the past 50 years, finding widespread use in basic scientific studies, communications, and navigation. However, with its higher operating frequency, an atomic clock based on an optical transition can be much more stable. We demonstrate an all-optical atomic clock referenced to the 1.064-petahertz transition of a single trapped 199Hg+ ion. A clockwork based on a mode-locked femtosecond laser provides output pulses at a 1-gigahertz rate that are phase-coherently locked to the optical frequency. By comparison to a laser-cooled calcium optical standard, an upper limit for the fractional frequency instability of 7 x 10(-15) is measured in 1 second of averaging-a value substantially better than that of the world's best microwave atomic clocks.

6.
Phys Rev Lett ; 86(22): 4996-9, 2001 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-11384404

RESUMO

The frequency comb created by a femtosecond mode-locked laser and a microstructured fiber is used to phase coherently measure the frequencies of both the Hg+ and Ca optical standards with respect to the SI second. We find the transition frequencies to be f(Hg) = 1 064 721 609 899 143(10) Hz and f(Ca) = 455 986 240 494 158(26) Hz, respectively. In addition to the unprecedented precision demonstrated here, this work is the precursor to all-optical atomic clocks based on the Hg+ and Ca standards. Furthermore, when combined with previous measurements, we find no time variations of these atomic frequencies within the uncertainties of the absolute value of( partial differential f(Ca)/ partial differential t)/f(Ca) < or =8 x 10(-14) yr(-1) and the absolute value of(partial differential f(Hg)/ partial differential t)/f(Hg) < or =30 x 10(-14) yr(-1).

7.
Chem Commun (Camb) ; (17): 1612-3, 2001 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-12240407

RESUMO

Treatment of alpha-naphthyl acrylate with both aliphatic and aromatic aldehydes in the presence of DABCO (30 mol%) afforded the desired (alpha-methylene-beta-hydroxy)esters with reasonable chemical yields (51-88%) within 20 min.

8.
Opt Lett ; 26(2): 102-4, 2001 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-18033520

RESUMO

With a fiber-broadened, femtosecond-laser frequency comb, the 76-THz interval between two laser-cooled optical frequency standards was measured with a statistical uncertainty of 2x10(-13) in 5 s , to our knowledge the best short-term instability thus far reported for an optical frequency measurement. One standard is based on the calcium intercombination line at 657 nm, and the other, on the mercury ion electric-quadrupole transition at 282 nm. By linking this measurement to the known Ca frequency, we report a new frequency value for the Hg(+) clock transition with an improvement in accuracy of ~10(5) compared with its best previous measurement.

9.
J Res Natl Inst Stand Technol ; 106(1): 47-63, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-27500017

RESUMO

The development of atomic frequency standards at NIST is discussed and three of the key frequency-standard technologies of the current era are described. For each of these technologies, the most recent NIST implementation of the particular type of standard is described in greater detail. The best relative standard uncertainty achieved to date for a NIST frequency standard is 1.5×10(-15). The uncertainties of the most recent NIST standards are displayed relative to the uncertainties of atomic frequency standards of several other countries.

10.
Antimicrob Agents Chemother ; 44(9): 2465-70, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10952596

RESUMO

Pathogen virulence factors and inflammation are responsible for tissue injury associated with respiratory failure in bacterial pneumonia, as seen in the bovine lung infected with Pasteurella haemolytica. Tilmicosin is a macrolide antibiotic used for the treatment of bovine bacterial pneumonia. Recent evidence suggests that tilmicosin-induced neutrophil apoptosis may have anti-inflammatory effects. Using bovine leukocytes, we sought to define whether live P. haemolytica affected tilmicosin-induced neutrophil apoptosis, assessed the proapoptotic effects of tilmicosin in comparison with other drugs, and characterized its impact on phagocytic uptake of neutrophils by macrophages. Induction of apoptosis in the presence or absence of P. haemolytica was assessed by using an enzyme-linked immunosorbent assay for apoptotic nucleosomes. In addition, fluorescent annexin-V staining identified externalized phosphatidylserine in neutrophils treated with tilmicosin, penicillin, ceftiofur, oxytetracycline, or dexamethasone. Neutrophil membrane integrity was assessed by using propidium iodide and trypan blue exclusion. As phagocytic clearance of apoptotic neutrophils by macrophages contributes to the resolution of inflammation, phagocytosis of tilmicosin-treated neutrophils by esterase-positive cultured bovine macrophages was assessed with light microscopy and transmission electron microscopy. Unlike bovine neutrophils treated with penicillin, ceftiofur, oxytetracycline, or dexamethasone, neutrophils exposed to tilmicosin became apoptotic, regardless of the presence or absence of P. haemolytica. Tilmicosin-treated apoptotic neutrophils were phagocytosed at a significantly greater rate by bovine macrophages than were control neutrophils. In conclusion, tilmicosin-induced neutrophil apoptosis occurs regardless of the presence or absence of live P. haemolytica, exhibits at least some degree of drug specificity, and promotes phagocytic clearance of the dying inflammatory cells.


Assuntos
Antibacterianos/farmacologia , Apoptose , Macrolídeos , Macrófagos/efeitos dos fármacos , Mannheimia haemolytica/fisiologia , Neutrófilos/efeitos dos fármacos , Tilosina/farmacologia , Animais , Transporte Biológico , Bovinos , Diferenciação Celular/efeitos dos fármacos , Técnicas In Vitro , Leucócitos Mononucleares/citologia , Leucócitos Mononucleares/metabolismo , Macrófagos/citologia , Macrófagos/fisiologia , Neutrófilos/citologia , Neutrófilos/microbiologia , Fagocitose/efeitos dos fármacos , Fosfatidilserinas/metabolismo , Tilosina/análogos & derivados
11.
Gaoxiong Yi Xue Ke Xue Za Zhi ; 8(1): 12-20, 1992 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-1548735

RESUMO

A Technetium-99m DTPA computer-assisted renal scan and CCR studies were performed on 35 spinal cord injured patients who had been hospitalized in the rehabilitation ward of Kaohsiung Medical College Hospital for less than 6 months during the period of August 1988 to March 1990. For each patient, the glomerular filtration rate (GFR), the effective renal plasma flow (ERPF), and the filtration fraction (FF) were obtained by a renal scan. CCR was measured by conventional procedure and was corrected with body length, body weight and body surface. Least square fit linear regression analysis revealed the best correlation between GFR and CCR. Based on GFR values the renal function was classified into four grades from normal to severe damage and the change of renal function was analyzed using four corresponding factors. The results showed that the ratio of GFR impairment in early spinal injury is 48.6% (mostly mild impairment). There are not significant differences between levels of lesion, severity of injury or successfulness of bladder training by Fisher's exact test. Renal function deteriorated proportionally with age and most of those patients having the worst renal function belonged to an old age group. Thus age is also one of the major factors in renal function impairment. Single kidney function impairment was noted in two patients whose total GFR or CCR were in the normal range, which implied the characteristic of early detection of renal dysfunction by renal scan.


Assuntos
Taxa de Filtração Glomerular , Rim/diagnóstico por imagem , Traumatismos da Medula Espinal/fisiopatologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cintilografia , Pentetato de Tecnécio Tc 99m
12.
Opt Lett ; 17(24): 1812-4, 1992 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-19798325

RESUMO

We report on the design and fabrication of Ge(x)Si(1-x) Mach-Zehnder interferometers based on the thermo-optic effect. The modulators exhibit 8 dB of extinction with a pi-phase-shift power requirement, P(pi), of 245 mW. The 3-dB bandwidth of these thermo-optic devices is 88 kHz. Finally, we present calculations indicating the effect of various parameters on the modulation of the Mach-Zehnder interferometer.

14.
Int J Biomed Comput ; 19(1): 43-61, 1986 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-3733253

RESUMO

This paper describes the application of the expert system concept to sleep stage scoring and is aimed at managing the large variability found in such records. The primary computational burden, sleep parameter calculation, can be relieved by recognizing major classes of recordings or 'somnotypes' having internally consistent sleep parameters for each class but significant differences between classes. The initiation and evolution of somnotypes so as to maintain accuracy while introducing a variety of sleep recordings is treated. The technique is demonstrated on seven all-night recordings resulting in 89.6% accuracy for about 5000 pages of data.


Assuntos
Computadores , Fases do Sono , Eletroencefalografia , Eletromiografia , Eletroculografia , Humanos , Sono REM
15.
Rev Sci Instrum ; 50(12): 1651, 1979 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18699456

RESUMO

A method is described for making solder connections to a commercial Nb(3)Sn multifilamentary conductor.

16.
Rev Sci Instrum ; 50(10): 1312, 1979 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18699383

RESUMO

A method is described for making a solder joint between a multifilamentary superconductor and a braided copper wire conductor.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...