137 research outputs found
Long-term culture of cholangiocytes from liver fibro-granulomatous lesions
BACKGROUND: Extensive bile duct proliferation is a key feature of the tissue reaction to clinical and experimental forms of liver injury. Experimental infection of mice by Schistosoma mansoni is a well-studied model of liver fibrosis with bile duct hyperplasia. However, the regulatory mechanisms of bile duct changes are not well understood. In this study we report the reproducible isolation of long-term cultures of cholangiocytes from mice livers with schistosomal fibrosis. METHODS: We have isolated a cholangiocyte cell line from Schistosoma-induced liver granulomas using a combination of methods including selective adhesion and isopyknic centrifugation in Percoll. RESULTS: The cell line was characterized by morphological criteria in optical and transmission electron microscopy, ability to form well differentiated ductular structures in collagen gels and by a positive staining for cytokeratin 18 and cytokeratin 19. To our knowledge, this is the first murine cholangiocyte cell line isolated from schistosomal fibrosis reported in the literature. CONCLUSION: After 9 months and 16 passages this diploid cell line maintained differentiated characteristics and a high proliferative capacity. We believe the method described here may be a valuable tool to study bile duct changes during hepatic injury
Isolation and primary cultures of human intrahepatic bile ductular epithelium
A technique for the isolation of human intrahepatic bile ductular epithelium, and the establishment of primary cultures using a serum- and growth-factor-supplemented medium combined with a connective tissue substrata is described. Initial cell isolates and monolayer cultures display phenotypic characteristics of biliary epithelial cells (low molecular weight prekeratin positive; albumin, alphafetoprotein, and Factor VIII-related antigen negative). Ultrastructural features of the cultured cells show cell polarization with surface microvilli, numerous interepithelial junctional complexes and cytoplasmic intermediate prekeratin filaments. © 1988 Tissue Culture Association, Inc
The nature of ferromagnetism in the chiral helimagnet Cr1/3NbS2
The chiral helimagnet Cr1/3NbS2 hosts exotic spin textures, whose influence on the magneto-transport properties make this material an ideal candidate for future spintronic applications. To date, the interplay between macroscopic magnetic and transport degrees of freedom is believed to result from a reduction in carrier scattering following spin order. Here, we present electronic structure measurements across the helimagnetic transition temperature TC that challenges this view. We show that the Fermi surface is comprised of strongly hybridized Nb- and Cr-derived electronic states, and that spectral weight close to the Fermi level increases anomalously as the temperature is lowered below TC. These findings are rationalized on the basis of first principle density functional theory calculations, which reveal a large nearest-neighbor exchange energy, suggesting the interaction between local spin moments and hybridized Nb- and Cr-derived itinerant states to go beyond the perturbative interaction of Ruderman-Kittel-Kasuya-Yosida, suggesting instead a mechanism rooted in a Hund’s exchange interaction
The nature of ferromagnetism in the chiral helimagnet
The chiral helimagnet, , hosts exotic spin textures, whose
influence on the magneto-transport properties, make this material an ideal
candidate for future spintronic applications. To date, the interplay between
macroscopic magnetic and transport degrees of freedom is believed to result
from a reduction in carrier scattering following spin order. Here, we present
electronic structure measurements through the helimagnetic transition
temperature, that challenges this view by showing a Fermi surface
comprised of strongly hybridized Nb- and Cr- derived electronic states, and
spectral weight in proximity to the Fermi level to anomalously increases as
temperature is lowered below . These findings are rationalized on the
basis of first principle, density functional theory calculations, which reveal
a large nearest-neighbor exchange energy, suggesting the interaction between
local spin moments and hybridized Nb- and Cr- derived itinerant states to go
beyond the perturbative interaction of Ruderman-Kittel-Kasuya-Yosida,
suggesting instead a mechanism rooted in a Hund's exchange interaction
Ultrafast Suppression of the Ferroelectric Instability in KTaO
We use an x-ray free-electron laser to study the ultrafast lattice dynamics
following above band-gap photoexcitation of the incipient ferroelectric
potassium-tantalate, \kto. %
We use ultrafast near-UV (central wavelength 266\,nm and 50 fs pulse
duration) laser light to photoexcite charge carriers across the gap and probe
the ultrafast lattice dynamics by recording the x-ray diffuse intensity
throughout multiple Brillouin zones using pulses from the Linac Coherent Light
Source (LCLS) (central wavelength 1.3\,\AA\, and ~fs pulse duration). We
observe changes in the diffuse intensity that we conclude are associated with a
hardening of the soft transverse optical and transverse acoustic phonon
branches along to and to . Using ground- and
excited-state interatomic force constants from density functional theory (DFT)
and assuming the phonon populations can be described by a time-dependent
temperature, we fit the quasi-equilibrium thermal diffuse intensity to the
experimental time-dependent intensity. We obtain the instantaneous lattice
temperature and density of photoexcited charge carriers as a function of time
delay. The DFT calculations demonstrate that photoexcitation transfers charge
from oxygen derived -bonding orbitals to Ta derived antibonding
orbitals, further suppressing the ferroelectric instability and increasing the
stability of the cubic, paraelectric structure.Comment: 8 pages, 4 figure
Multi-Mode Front Lens for Momentum Microscopy: Part II Experiments
We have experimentally demonstrated different operating modes for the front
lenses of the momentum microscopes described in Part I. Measurements at
energies from vacuum UV at a high-harmonic generation (HHG)-based source to the
soft and hard X-ray range at a synchrotron facility validated the results of
theoretical ray-tracing calculations. The key element is a ring electrode
concentric with the extractor electrode, which can tailor the field in the gap.
First, the gap-lens-assisted extractor mode reduces the field strength at the
sample while mitigating image aberrations. This mode gave good results in all
spectral ranges. Secondly, by compensating the field at the sample surface with
a negative voltage at the ring electrode we can operate in zero-field mode,
which is beneficial for operando experiments. Finally, higher negative voltages
establish the repeller mode, which removes all slow electrons below a certain
kinetic energy to eliminate the primary contribution to the space-charge
interaction in pump-probe experiments. The switch from extractor to repeller
mode is associated with a reduction in the k-field-of-view (10-20 % at
hard-X-ray energies, increasing to ~50% at low energies). Real-space imaging
also benefits from the new lens modes as confirmed by ToF-XPEEM imaging with
650 nm resolution.Comment: 22 pages, 9 figures, 56 reference
Cytotoxic activity of Thai medicinal plants against human cholangiocarcinoma, laryngeal and hepatocarcinoma cells in vitro
<p>Abstract</p> <p>Background</p> <p>Cholangiocarcinoma is a serious public health in Thailand with increasing incidence and mortality rates. The present study aimed to investigate cytotoxic activities of crude ethanol extracts of a total of 28 plants and 5 recipes used in Thai folklore medicine against human cholangiocarcinoma (CL-6), human laryngeal (Hep-2), and human hepatocarcinoma (HepG2) cell lines in vitro.</p> <p>Methods</p> <p>Cytotoxic activity of the plant extracts against the cancerous cell lines compared with normal cell line (renal epithelial cell: HRE) were assessed using MTT assay. 5-fluorouracil was used as a positive control. The IC<sub>50 </sub>(concentration that inhibits cell growth by 50%) and the selectivity index (SI) were calculated.</p> <p>Results</p> <p>The extracts from seven plant species (<it>Atractylodes lancea</it>, <it>Kaempferia galangal</it>, <it>Zingiber officinal</it>, <it>Piper chaba</it>, <it>Mesua ferrea</it>, <it>Ligusticum sinense</it>, <it>Mimusops elengi</it>) and one folklore recipe (Pra-Sa-Prao-Yhai) exhibited promising activity against the cholangiocarcinoma CL-6 cell line with survival of less than 50% at the concentration of 50 μg/ml. Among these, the extracts from the five plants and one recipe (<it>Atractylodes lancea</it>, <it>Kaempferia galangal</it>, <it>Zingiber officinal</it>, <it>Piper chaba</it>, <it>Mesua ferrea</it>, and Pra-Sa-Prao-Yhai recipe) showed potent cytotoxic activity with mean IC<sub>50 </sub>values of 24.09, 37.36, 34.26, 40.74, 48.23 and 44.12 μg/ml, respectively. All possessed high activity against Hep-2 cell with mean IC<sub>50 </sub>ranging from 18.93 to 32.40 μg/ml. In contrast, activity against the hepatoma cell HepG2 varied markedly; mean IC<sub>50 </sub>ranged from 9.67 to 115.47 μg/ml. The only promising extract was from <it>Zingiber officinal </it>(IC<sub>50 </sub>= 9.67 μg/ml). The sensitivity of all the four cells to 5-FU also varied according to cell types, particularly with CL-6 cell (IC<sub>50 </sub>= 757 micromolar). The extract from <it>Atractylodes lancea </it>appears to be both the most potent and most selective against cholangiocarcinoma (IC<sub>50 </sub>= 24.09 μg/ml, SI = 8.6).</p> <p>Conclusions</p> <p>The ethanolic extracts from five plants and one folklore recipe showed potent cytotoxic activity against CL-6 cell. Sensitivity to other cancerous cell lines varied according to cell types and the hepatocarcinoma cell line. HepG2 appears to be the most resistant to the tested extracts.</p
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