JoVE Visualize What is visualize?
Stop Reading. Start Watching.
Advanced Search
Stop Reading. Start Watching.
Regular Search
Find video protocols related to scientific articles indexed in Pubmed.
[The levels of angiopoietin-2 in patients with acute respiratory distress syndrome and its value on prognosis].
Zhonghua Wei Zhong Bing Ji Jiu Yi Xue
PUBLISHED: 11-18-2014
Show Abstract
Hide Abstract
To approach the correlation between angiopoietin-2 (Ang-2) levels and degree of lung injury and prognosis and its clinical significance in patients with acute respiratory distress syndrome (ARDS).
Related JoVE Video
Evidence for Stabilizing Selection on Codon Usage in Chromosomal Rearrangements of Drosophila pseudoobscura.
G3 (Bethesda)
PUBLISHED: 10-19-2014
Show Abstract
Hide Abstract
There has been a renewed interest in investigating the role of stabilizing selection acting on genome-wide traits such as codon usage bias. Codon bias, when synonymous codons are utilized at unequal frequencies, occurs in a wide variety of taxa. Standard evolutionary models explain the maintenance of codon bias through a balance of genetic drift, mutation and weak purifying selection. The efficacy of selection is expected to be reduced in regions of suppressed recombination. Contrary to observations in Drosophila melanogaster, some recent studies have failed to detect a relationship between the recombination rate, intensity of selection acting at synonymous sites and the magnitude of codon bias as predicted under these standard models. Here, we examined codon bias in 2,798 protein coding loci on the third chromosome of Drosophila pseudoobscura using whole genome sequences of 47 individuals, representing five common third chromosome gene arrangements. Fine-scale recombination maps were constructed using over 1 million segregating sites. As expected, recombination was demonstrated to be significantly suppressed between chromosome arrangements, allowing for a direct examination of the relationship between recombination, selection, and codon bias. As with other Drosophila species, we observe a strong mutational bias away from the most frequently used codons. We find the rate of synonymous and nonsynonymous polymorphism is variable between different amino acids. However, we do not observe a reduction in codon bias or the strength of selection in regions of suppressed recombination as expected. Instead, we find that the interaction between weak stabilizing selection and mutational bias likely plays a role in shaping the composition of synonymous codons across the third chromosome in D. pseudoobscura.
Related JoVE Video
[The effect of superior oblique recession on the status of ocular torsion].
Zhonghua Yan Ke Za Zhi
PUBLISHED: 10-15-2014
Show Abstract
Hide Abstract
To investigate the effect of superior oblique recession on the status of ocular torsion.
Related JoVE Video
Localization of Oxygen Interstitials in CeSrGa3O7+? Melilite.
Inorg Chem
PUBLISHED: 10-10-2014
Show Abstract
Hide Abstract
The solubility of Ce in the La1-xCexSrGa3O7+? and La1.54-xCexSr0.46Ga3O7.27+? melilites was investigated, along with the thermal redox stability in air of these melilites and the conductivity variation associated with oxidization of Ce(3+) into Ce(4+). Under CO reducing atmosphere, the La in LaSrGa3O7 may be completely substituted by Ce to form the La1-xCexSrGa3O7+? solid solution, which is stable in air to ?600 °C when x ? 0.6. On the other side, the La1.54-xCexSr0.46Ga3O7.27+? compositions displayed much lower Ce solubility (x ? 0.1), irrespective of the synthesis atmosphere. In the as-made La1-xCexSrGa3O7+?, the conductivity increased with the cerium content, due to the enhanced electronic conduction arising from the 4f electrons in Ce(3+) cations. At 600 °C, CeSrGa3O7+? showed a conductivity of ?10(-4) S/cm in air, nearly 4 orders of magnitude higher than that of LaSrGa3O7. The oxidation of Ce(3+) into Ce(4+) in CeSrGa3O7+? slightly reduced the conductivity, and the oxygen excess did not result in apparent increase of oxide ion conduction in CeSrGa3O7+?. The Ce doping in air also reduced the interstitial oxide ion conductivity of La1.54Sr0.46Ga3O7.27. Neutron powder diffraction study on CeSrGa3O7.39 composition revealed that the extra oxygen is incorporated in the four-linked GaO4 polyhedral environment, leading to distorted GaO5 trigonal bipyramid. The stabilization and low mobility of interstitial oxygen atoms in CeSrGa3O7+?, in contrast with those in La1+xSr1-xGa3O7+0.5x, may be correlated with the cationic size contraction from the oxidation of Ce(3+) to Ce(4+). These results provide a new comprehensive understanding of the accommodation and conduction mechanism of the oxygen interstitials in the melilite structure.
Related JoVE Video
Topotactic growth, selective adsorption, and adsorption-driven photocatalysis of protonated layered titanate nanosheets.
ACS Appl Mater Interfaces
PUBLISHED: 10-01-2014
Show Abstract
Hide Abstract
Layered titanates with selective adsorption ability and adsorption-driven photocatalytic property can be quite attractive due to their potential applications in water purification. In this work, lepidocrocite-like layered protonated titanate (H2Ti2O5·H2O, denoted as HTO) nanosheets were successfully synthesized by an ion-exchange process. It turns out that this layered structure displays an abundant and selective adsorption toward the fluoroquinolone pharmaceutical compared with some large dye molecules due to a size selectivity of the interlayer spacing of HTO and the molecular horizontal size, as well as their electrostatic interaction. The uptake ability of HTO could be readily controlled through adjusting the pH values of adsorbate solution, and the maximum uptake capacity was achieved at the pH value of about 5.5 for ciprofloxacin (CIP) and 6.5 for moxifloxacin (MOX). The adsorption amount of smaller nalidixic acid (NAL) showed an increasing tendency as the pH value decreased. Moreover, the two-dimensional layered crystal structure also permits such HTO nanosheets to have a large percentage of (010) faces exposed, which is considerably provided by the interlayer surfaces of these nanosheets. The (010) surface has a similar Ti and O atomic arrangement as to the highly reactive anatase TiO2(001) one. Due to these specific characteristics, these HTO nanosheets show excellent photocatalytic activity in degrading CIP under UV light irradiation as well as possess a superior adsorption ability to remove CIP from aqueous solution selectively and efficiently. The photocatalytic reaction is believed to be mainly conducted on the active anatase (001)-like interlayer (010) surfaces of the layered structures since the as-prepared HTO performs an adsorption-driven molecular recognitive photocatalytic reaction.
Related JoVE Video
Cu?O template synthesis of high-performance PtCu alloy yolk-shell cube catalysts for direct methanol fuel cells.
Chem. Commun. (Camb.)
PUBLISHED: 09-04-2014
Show Abstract
Hide Abstract
Novel PtCu alloy yolk-shell cubes were fabricated via the disproportionation and displacement reactions in Cu2O yolk-shell cubes, and they exhibit significantly improved catalytic activity and durability for methanol electrooxidation.
Related JoVE Video
Design, synthesis and pharmacological evaluation of 6,7-disubstituted-4-phenoxyquinoline derivatives as potential antitumor agents.
Bioorg. Chem.
PUBLISHED: 08-12-2014
Show Abstract
Hide Abstract
Two series of 6,7-disubstituted-4-phenoxyquinoline derivatives bearing 2,4-imidazolinedione/pyrazolone scaffold were designed, synthesized and evaluated for their c-Met kinase inhibition and cytotoxicity against HT-29, H460, A549, MKN-45, and U87MG cancer cell lines in vitro. The pharmacological data indicated that most of the tested compounds showed moderate to significant cytotoxicity and high selectivity against HT-29, H460 and A549 cancer cell lines as compared with foretinib. The SAR analyses indicated that compounds with halogen groups, especially trifluoromethyl groups at 2-position on the phenyl ring (moiety B) were more effective. In this study, a promising compound 17 (c-Met IC50=2.20nM, a multi-target tyrosine kinase inhibitor) showed the most potent antitumor activities with IC50 values of 0.14?M, 0.18?M, 0.09?M, 0.03?M, and 1.06?M against HT-29, H460, A549, MKN-45, and U87MG cell lines, respectively.
Related JoVE Video
Comparative validation of the D. melanogaster modENCODE transcriptome annotation.
Genome Res.
PUBLISHED: 07-03-2014
Show Abstract
Hide Abstract
Accurate gene model annotation of reference genomes is critical for making them useful. The modENCODE project has improved the D. melanogaster genome annotation by using deep and diverse high-throughput data. Since transcriptional activity that has been evolutionarily conserved is likely to have an advantageous function, we have performed large-scale interspecific comparisons to increase confidence in predicted annotations. To support comparative genomics, we filled in divergence gaps in the Drosophila phylogeny by generating draft genomes for eight new species. For comparative transcriptome analysis, we generated mRNA expression profiles on 81 samples from multiple tissues and developmental stages of 15 Drosophila species, and we performed cap analysis of gene expression in D. melanogaster and D. pseudoobscura. We also describe conservation of four distinct core promoter structures composed of combinations of elements at three positions. Overall, each type of genomic feature shows a characteristic divergence rate relative to neutral models, highlighting the value of multispecies alignment in annotating a target genome that should prove useful in the annotation of other high priority genomes, especially human and other mammalian genomes that are rich in noncoding sequences. We report that the vast majority of elements in the annotation are evolutionarily conserved, indicating that the annotation will be an important springboard for functional genetic testing by the Drosophila community.
Related JoVE Video
Studies of terbium bridge: saturation phenomenon, significance of sensitizer and mechanisms of energy transfer, and luminescence quenching.
ACS Appl Mater Interfaces
PUBLISHED: 06-20-2014
Show Abstract
Hide Abstract
Terbium chain in the form of S ? (Tb(3+))n ? A (S = Ce(3+) or Eu(2+), A = Eu(3+)), as a promising energy transfer (ET) approach, has been proposed to enhance Eu(3+) emission for solid-state lighting. However, the viewpoint of ET from S to A via the terbium chain (Tb(3+)-Tb(3+)-Tb(3+)-...) is very doubtful. Here, hosts of Ba3Ln(PO4)3, LnPO4, LnBO3, and Na2Ln2B2O7 doped with Ce(3+) ? (Tb(3+))n ? Eu(3+) or (Tb(3+))n ? Eu(3+) are synthesized to prove the universality of S ? (Tb(3+))n ? A in inorganic hosts and to study the unsolved issues. Saturation distance of Tb(3+)-Eu(3+), estimated with the empirical data of different hosts, is proposed to be a criterion for determining whether a spectral chromaticity coordinate keeps constant. A branch model is put forward to replace the chain model to explain the role of (Tb(3+))n in ET from Ce(3+) to Eu(3+) and the necessity of high content of Tb(3+); the term "terbium bridge" is used to replace "terbium chain", and the value of n is determined to be two or three. The intensity quenching of Eu(3+) emission is attributed to the surface defects ascribed to the smaller particles and larger specific surface area rather than the concentration quenching of Tb(3+). Based on the saturation distance and the mechanism of luminescence quenching, the necessary concentration of Tb(3+) for (Tb(3+))n can be estimated as long as the cell parameters are already known and the luminescent efficiency of Eu(3+) can be further improved by optimizing the synthesis method to decrease the quantity of surface defects.
Related JoVE Video
Solid-State (29)Si NMR and neutron-diffraction studies of Sr(0.7)K(0.3)SiO(2.85) oxide ion conductors.
Inorg Chem
PUBLISHED: 06-06-2014
Show Abstract
Hide Abstract
K/Na-doped SrSiO3-based oxide ion conductors were recently reported as promising candidates for low-temperature solid-oxide fuel cells. Sr0.7K0.3SiO2.85, close to the solid-solution limit of Sr1-xKxSiO3-0.5x, was characterized by solid-state (29)Si NMR spectroscopy and neutron powder diffraction (NPD). Differing with the average structure containing the vacancies stabilized within the isolated Si3O9 tetrahedral rings derived from the NPD study, the (29)Si NMR data provides new insight into the local defect structure in Sr0.7K0.3SiO2.85. The Q(1)-linked tetrahedral Si signal in the (29)Si NMR data suggests that the Si3O9 tetrahedral rings in the K-doped SrSiO3 materials were broken, forming Si3O8 chains. The Si3O8 chains can be stabilized by either bonding with the oxygen atoms of the absorbed lattice water molecules, leading to the Q(1)-linked tetrahedral Si, or sharing oxygen atoms with neighboring Si3O9 units, which is consistent with the Q(3)-linked tetrahedral Si signal detected in the (29)Si NMR spectra.
Related JoVE Video
In vitro molecular evolution yields an NEIBM with a potential novel IgG binding property.
Sci Rep
PUBLISHED: 02-28-2014
Show Abstract
Hide Abstract
Staphylococcus aureus protein A (SpA) and protein G of groups C and G streptococci (SpG) are two well-defined bacterial immunoglobulin (Ig)-binding proteins (IBPs) with high affinity for specific sites on IgG from mammalian hosts. Both SpA and SpG contain several highly-homologous IgG-binding domains, each of which possesses similar binding characteristic of the whole corresponding proteins. Whether specific combinations of these domains could generate a molecule with novel IgG-binding properties remained unknown. We constructed a combinatorial phage library displaying randomly-rearranged A, B, C, D and E domains of SpA as well as the B2 (G2) and B3 (G3) domains of SpG. In vitro molecular evolution directed by human, rabbit, bovine, or goat polyclonal IgGs and four subclasses of mouse monoclonal IgGs generated one common combination, D-C-G3. A series of assays demonstrated that D-C-G3 exhibited a potential novel IgG binding property that was obviously different from those of both parent proteins. This study provides an example of successful protein engineering through in vitro molecular evolution and useful approaches for structure and function studies of IBPs.
Related JoVE Video
Highly thermally stable single-component white-emitting silicate glass for organic-resin-free white-light-emitting diodes.
ACS Appl Mater Interfaces
PUBLISHED: 02-05-2014
Show Abstract
Hide Abstract
Thermal management is still a great challenge for high-power phosphor-converted white-light-emitting diodes (pc-WLEDs) intended for future general lighting. In this paper, a series of single-component white-emitting silicate SiO2-Li2O-SrO-Al2O3-K2O-P2O5: Ce(3+), Tb(3+), Mn(2+) (SLSAKP: Ce(3+), Tb(3+), Mn(2+)) glasses that simultaneously play key roles as a luminescent convertor and an encapsulating material for WLEDs were prepared via the conventional melt-quenching method, and systematically studied using their absorption spectra, transmittance spectra, photoluminescence excitation and emission spectra in the temperature range 296-498 K, decay curves, and quantum efficiency. The glasses show strong and broad absorption in 250-380 nm region and exhibit intense white emission, produced by in situ mixing of blue-violet, green, and orange-red light from Ce(3+), Tb(3+), and Mn(2+) ions, respectively, in a single glass component. The quantum efficiency of SLSAKP: 0.3%Ce(3+), 2.0%Tb(3+), 2.0%Mn(2+) glass is determined to be 19%. More importantly, this glass shows good thermal stability, exhibiting at 373 and 423 K about 84.56 and 71.02%, respectively, of the observed room temperature (298 K) emission intensity. The chromaticity shift of SLSAKP: 0.3%Ce(3+), 2.0%Tb(3+), 2.0%Mn(2+) is 2.94 × 10(-2) at 498 K, only 57% of the commercial triple-color white-emitting phosphor mixture. Additionally, this glass shows no transmittance loss at the 370 nm emission of a UV-Chip-On-Board (UV-COB) after thermal aging for 240 h, compared with the 82% transmittance loss of epoxy resin. The thermal conductivity of the glass is about 1.07 W/mK, much larger than the 0.17 W/mK of epoxy resin. An organic-resin-free WLEDs device based on SLSAKP: 0.3%Ce(3+), 2.0%Tb(3+), 2.0%Mn(2+) glass and UV-COB is successfully demonstrated. All of our results demonstrate that the presented Ce(3+)/Tb(3+)/Mn(2+) tridoped lithium-strontium-silicate glass may serve as a promising candidate for high-power WLEDs.
Related JoVE Video
Real-time automatic hospital-wide surveillance of nosocomial infections and outbreaks in a large Chinese tertiary hospital.
BMC Med Inform Decis Mak
PUBLISHED: 01-27-2014
Show Abstract
Hide Abstract
We aimed to develop a real-time nosocomial infection surveillance system (RT-NISS) to monitor all nosocomial infections (NIs) and outbreaks in a Chinese comprehensive hospital to better prevent and control NIs.
Related JoVE Video
Embryonic Stem Cells Promoting Macrophage Survival and Function are Crucial for Teratoma Development.
Front Immunol
PUBLISHED: 01-01-2014
Show Abstract
Hide Abstract
Stem cell therapies have had tremendous potential application for many diseases in recent years. However, the tumorigenic properties of stem cells restrict their potential clinical application; therefore, strategies for reducing the tumorigenic potential of stem cells must be established prior to transplantation. We have demonstrated that syngeneic transplantation of embryonic stem cells (ESCs) provokes an inflammatory response that involves the rapid recruitment of bone marrow-derived macrophages (BMDMs). ESCs are able to prevent mature macrophages from macrophage colony-stimulating factor (M-CSF) withdrawal-induced apoptosis, and thus prolong macrophage lifespan significantly by blocking various apoptotic pathways in an M-CSF-independent manner. ESCs express and secrete IL-34, which may be responsible for ESC-promoted macrophage survival. This anti-apoptotic effect of ESCs involves activation of extracellular signal-regulated kinase (ERK)1/2 and PI3K/Akt pathways and thus, inhibition of ERK1/2 and PI3K/AKT activation decreases ESC-induced macrophage survival. Functionally, ESC-treated macrophages also showed a higher level of phagocytic activity. ESCs further serve to polarize BMDMs into M2-like macrophages that exhibit most tumor-associated macrophage phenotypic and functional features. ESC-educated macrophages produce high levels of arginase-1, Tie-2, and TNF-?, which participate in angiogenesis and contribute to teratoma progression. Our study suggests that induction of M2-like macrophage activation is an important mechanism for teratoma development. Strategies targeting macrophages to inhibit teratoma development would increase the safety of ESC-based therapies, inasmuch as the depletion of macrophages completely inhibits ESC-induced angiogenesis and teratoma development.
Related JoVE Video
Report of recombinant norovirus GII.g/GII.12 in Beijing, China.
PLoS ONE
PUBLISHED: 01-01-2014
Show Abstract
Hide Abstract
Norovirus (NoV) has been recognized as the most important cause of nonbacterial acute gastroenteritis affecting all age group people in the world. Genetic recombination is a common occurance in RNA viruses and many recombinant NoV strains have been described since it was first reported in 1997. However, the knowledge of recombinant NoV in China is extremely limited.
Related JoVE Video
Cloning, Expression, and Characterization of l-Asparaginase from a Newly Isolated Bacillus subtilis B11-06.
J. Agric. Food Chem.
PUBLISHED: 09-18-2013
Show Abstract
Hide Abstract
This study focused on the cloning, overexpression, and characterization of the gene encoding l-asparaginase (ansZ) from a nonpathogenic strain of Bacillus subtilis B11-06. The recombinant enzyme showed high thermostability and low affinity to l-glutamine. The ansZ gene, encoding a putative l-asparaginase II, was amplified by PCR and expressed in B. subtilis 168 using the shuttle vector pMA5. The activity of the recombinant enzyme was 9.98 U/mL, which was significantly higher than that of B. subtilis B11-06. The recombinant enzyme was purified by a two-step procedure including ammonium sulfate fractionation and hydrophobic interaction chromatography. The optimum pH and temperature of the recombinant enzyme were 7.5 and 40 °C, respectively. The enzyme was quite stable at a pH range of 6.0-9.0 and exhibited about 14.7 and 9.0% retention of activity following 2 h incubation at 50 or 60 °C, respectively. The Km for l-asparagine was 0.43 mM, and the Vmax was 77.51 ?M/min. Results of this study also revealed the potential industrial application of this enzyme in reducing acrylamide formation during the potato frying process.
Related JoVE Video
Effects of advanced treatment systems on the removal of antibiotic resistance genes in wastewater treatment plants from hangzhou, china.
Environ. Sci. Technol.
PUBLISHED: 07-11-2013
Show Abstract
Hide Abstract
This study aimed at quantifying the concentration and removal of antibiotic resistance genes (ARGs) in three municipal wastewater treatment plants (WWTPs) employing different advanced treatment systems [biological aerated filter, constructed wetland, and ultraviolet (UV) disinfection]. The concentrations of tetM, tetO, tetQ, tetW, sulI, sulII, intI1, and 16S rDNA genes were examined in wastewater and biosolid samples. In municipal WWTPs, ARG reductions of 1-3 orders of magnitude were observed, and no difference was found among the three municipal WWTPs with different treatment processes (p > 0.05). In advanced treatment systems, 1-3 orders of magnitude of reductions in ARGs were observed in constructed wetlands, 0.6-1.2 orders of magnitude of reductions in ARGs were observed in the biological aerated filter, but no apparent decrease by UV disinfection was observed. A significant difference was found between constructed wetlands and biological filter (p < 0.05) and between constructed wetlands and UV disinfection (p < 0.05). In the constructed wetlands, significant correlations were observed in the removal of ARGs and 16S rDNA genes (R(2) = 0.391-0.866; p < 0.05). Constructed wetlands not only have the comparable ARG removal values with WWTP (p > 0.05) but also have the advantage in ARG relative abundance removal, and it should be given priority to be an advanced treatment system for further ARG attenuation from WWTP.
Related JoVE Video
Graphene quantum dots embedded in a hexagonal BN sheet: identical influences of zigzag/armchair edges.
Phys Chem Chem Phys
PUBLISHED: 06-08-2013
Show Abstract
Hide Abstract
Various graphene quantum dots (GQDs) embedded in a hexagonal BN sheet were studied theoretically using the tight binding model. The effective mass was analyzed as a function of the distance between neighboring GQDs. It was found that the effective mass increases exponentially as the distance increases, indicating that the confined states of GQDs are well conserved in these hybrid systems. Further studies revealed that a ubiquitous gap of 0.3-3 eV exists, the size of which is mainly governed by the GQDs dimensions whereas it is insensitive to edge structures. These results show that GQDs in BN are promising candidates for optoelectronics.
Related JoVE Video
Comparative investigation of the performances of hematite nanoplates and nanograins in lithium-ion batteries.
Phys Chem Chem Phys
PUBLISHED: 05-16-2013
Show Abstract
Hide Abstract
In this work, we selectively prepared two samples with quite different nanocrystal shapes, i.e. nanoplates and nanograins but with almost identical surface areas to make a clear comparison of nanocrystal shapes on electrochemical performance. The electrochemical results indicate that the thinner hexagonal ?-Fe2O3 nanoplates considerably enclosed by two larger (0001) basal surfaces exhibit higher capacity and stability than thicker ?-Fe2O3 nanograins enclosed by a variety of crystal facets. During the conversion reaction, an orientated growth of porous nanostructure with orientated nanowalls as a stable framework is observed for the nanoplate, readily supplying a pathway for long and easy lithiation-delithiation cycling. The improved electrochemical performance of ?-Fe2O3 nanoplates is surely related to the nanostructure with significantly stacked (0001) lattice planes along [0001] direction for orientated growth of ?-Fe2O3 nanodomains along one [111] direction.
Related JoVE Video
Involvement of ?7 nAChR Signaling Cascade in Epigallocatechin Gallate Suppression of ?-Amyloid-Induced Apoptotic Cortical Neuronal Insults.
Mol. Neurobiol.
PUBLISHED: 05-04-2013
Show Abstract
Hide Abstract
Excessive generation and accumulation of the ?-amyloid (A?) peptide in selectively vulnerable brain regions is a key pathogenic event in the Alzheimers disease (AD), while epigallocatechin gallate (EGCG) is a very promising chemical to suppress a variety of A?-induced neurodegenerative disorders. However, the precise molecular mechanism of EGCG responsible for protection against neurotoxicity still remains elusive. To validate and further investigate the possible mechanism involved, we explored whether EGCG neuroprotection against neurotoxicity of A? is mediated through the ?7 nicotinic acetylcholine receptor (?7 nAChR) signaling cascade. It was shown in rat primary cortical neurons that short-term treatment with EGCG significantly attenuated the neurotoxicity of A?1-42, as demonstrated by increased cell viability, reduced number of apoptotic cells, decreased reactive oxygen species (ROS) generation, and downregulated caspase-3 levels after treatment with 25-?M A?1-42. In addition, EGCG markedly strengthened activation of ?7nAChR as well as its downstream pathway signaling molecules phosphatidylinositol 3-kinase (PI3K) and Akt, subsequently leading to suppression of Bcl-2 downregulation in A?-treated neurons. Conversely, administration of ?7nAChR antagonist methyllycaconitine (MLA; 20 ?M) to neuronal cultures significantly attenuated the neuroprotection of EGCG against A?-induced neurototoxicity, thus presenting new evidence that the ?7nAChR activity together with PI3K/Akt transduction signaling may contribute to the molecular mechanism underlying the neuroprotective effects of EGCG against A?-induced cell death.
Related JoVE Video
An omp gene enhances cell tolerance of Cu(II) in Sinorhizobium meliloti CCNWSX0020.
World J. Microbiol. Biotechnol.
PUBLISHED: 03-18-2013
Show Abstract
Hide Abstract
The main aim of this work was to study molecular characterization of a DNA fragment conferring resistance to Cu(II) in Sinorhizobium meliloti CCNWSX0020. The strain CCNWSX0020, resistant to 1.4 mmol l(-1) Cu(II) in tryptone-yeast extract medium was isolated from Medicago lupulina growing in mine tailings of Fengxian County, China. The availability of the complete genome sequence of S. meliloti CCNWSX0020 provides an opportunity for investigating genes that play significant roles in Cu(II) resistance. A copper resistance gene, with a length of 1,445 bp, encoding 481 amino acids, designated omp, was identified by cDNA-amplified fragment length polymorphism from S. meliloti CCNWSX0020. The expression of omp gene strongly increased in the presence of Cu(II). The omp-defective mutants display sensitivities to Cu(II) compared with their wild types. The Cu(II)-sensitive phenotype of the mutant was complemented by a 1.5-kb DNA fragment containing omp gene. BLAST analysis revealed that this gene encoded a hypothetical outer membrane protein with 75 % similarity to outer membrane efflux protein in Rhizobium leguminosarum bv. viciae 3841. These studies suggested that the omp product was involved in the Cu(II) tolerance of S. meliloti CCNWSX0020.
Related JoVE Video
UV-Vis-NIR luminescence properties and energy transfer mechanism of LiSrPO4:Eu2+, Pr3+ suitable for solar spectral convertor.
Opt Express
PUBLISHED: 03-14-2013
Show Abstract
Hide Abstract
An efficient near-infrared (NIR) phosphor LiSrPO(4):Eu(2+), Pr(3+) is synthesized by solid-state reaction and systematically investigated using x-ray diffraction, diffuse reflection spectrum, photoluminescence spectra at room temperature and 3 K, and the decay curves. The UV-Vis-NIR energy transfer mechanism is proposed based on these results. The results demonstrate Eu(2+) can be an efficient sensitizer for harvesting UV photon and greatly enhancing the NIR emission of Pr(3+) between 960 and 1060 nm through efficient energy feeding by allowed 4f-5d absorption of Eu(2+) with high oscillator strength. Eu(2+)/Pr(3+) may be an efficient donor-acceptor pair as solar spectral converter for Si solar cells.
Related JoVE Video
Inverse relationship between carrier mobility and bandgap in graphene.
J Chem Phys
PUBLISHED: 03-08-2013
Show Abstract
Hide Abstract
A frequently stated advantage of gapless graphene is its high carrier mobility. However, when a nonzero bandgap is opened, the mobility drops dramatically. The hardness to achieve high mobility and large on?off ratio simultaneously limits the development of graphene electronics. To explore the underlying mechanism, we investigated the intrinsic mobility of armchair graphene nanoribbons (AGNRs) under phonon scattering by combining first-principles calculations and a tight-binding analysis. A linear dependence of the effective mass on bandgap was demonstrated to be responsible for the inverse mobility-gap relationship. The deformation-potential constant was found to be determined by the strain dependence of the Fermi energy and the bandgap, resulting in two mobility branches, and is essential for the high mobility of AGNRs. In addition, we showed that the transport polarity of AGNRs can be switched by applying a uniaxial strain.
Related JoVE Video
VEGF-C ShRNA inhibits pancreatic cancer growth and lymphangiogenesis in an orthotopic fluorescent nude mouse model.
Anticancer Res.
PUBLISHED: 02-09-2013
Show Abstract
Hide Abstract
The aim of this study was to assess the inhibitory efficacy of short hairpin RNA (ShRNA) targeting vascular endothelial growth factor C (VEGF-C) in an orthotopic pancreatic cancer mouse model. BxPC-3 human pancreatic cancer cells expressing green fluorescent protein (GFP) were orthotopically implanted onto the pancreas of nude mice. All mice were randomly divided into four groups when the average tumor size had reached 100 mm(3) and were treated with either vehicle or gemcitabine at 150 mg/kg; or intravenous VEGF-C ShRNA at 150 mg/kg; or intratumoral VEGF-C ShRNA at 150 ?g/kg. In vivo fluorescence imaging was performed to monitor tumor growth and metastasis during the study. Real-time quantitative polymerase chain reaction (RT-qPCR) and an enzyme-linked immunosorbent assay (ELISA) were performed to determine the mRNA and protein level of VEGF-C in tumor tissues. Lymphatic vessel marker D2-40, blood vessel marker CD31 and proliferation marker Ki67 expression of the tumor tissues were analyzed by immunohistochemistry staining. Intravenous and intratumoral VEGF-C ShRNA treatment significantly inhibited tumor growth, downregulated the expression of VEGF-C mRNA, reduced tumor microlymphatic vessel density (MLVD), and inhibited cancer cell proliferation. Gemcitabine, as the standard treatment for pancreatic cancer, demonstrated a stronger inhibitory effect on tumor growth, with less inhibition of MLVD and more inhibition of microvessel density (MVD) and proliferation than VEGF-C ShRNA. These results indicate that different mechanisms are associated with the efficacy of gemcitabine and VEGF-C ShRNA.
Related JoVE Video
Photo-induced free radical modification of graphene.
Small
PUBLISHED: 02-04-2013
Show Abstract
Hide Abstract
Graphene has stimulated enormous interest due to its intriguing structure and fascinating properties. The extremely high carrier mobility, mechanical flexibility, and optical transparency as well as the versatility for band structure engineering make graphene a promising candidate for next-generation carbon-based electronic devices. Graphene chemistry, the covalent functionalization of graphene as a 2D giant molecule, offers a promising direction to controllably tailor its properties through the introduction of various chemical decorations. One of the great challenges for graphene functionalization originates from its strong chemical stability, thus highly reactive chemical species are needed as the reactants. In recent years, novel photochemical approaches have been developed to achieve efficient graphene modification and bandgap modulation, following a general concept of "Photochemical Bandgap Engineering of Graphene". In this article, such kinds of photochemical graphene engineering are demonstrated, together with a brief discussion on the future directions, challenges, and opportunities in this fascinating research area.
Related JoVE Video
The inhibition of resveratrol to human skin squamous cell carcinoma A431 xenografts in nude mice.
Fitoterapia
PUBLISHED: 02-02-2013
Show Abstract
Hide Abstract
Squamous cell carcinoma (SCC) is one of the commonest dermatological malignancies. Resveratrol (Res) is one type of polyphenolic compound which was first identified from the roots of Veratrum grandinorum in 1940. The previous studies found that Res can promote apoptosis of a variety of tumor cell, especially SCC cells. However it is rare to study the inhibition mechanism of Res in the animal model. In this study, through the establishment of human cutaneous SCC A431 xenografts in nude mice, we observed Res inhibition effect and investigated the inhibition mechanism by checking the expression of apoptosis-related factors, p53, ERK and survivin. The results showed that the xenograft volume and weight of Res groups were less than those of the control groups (P<0.05), but the net body mass of nude mice of Res groups was not significantly different from the control groups (P>0.05). The apoptotic index of Res groups were significantly higher than the control groups (P<0.05). The protein and mRNA expression of p53 and ERK were statistically positively correlated (P<0.05) and significantly increased in Res high- and medium-dose groups compared with the control groups (P<0.05). Moreover, the protein and mRNA expression of SVV were negatively correlated with p53 (P<0.05) and lower than the control groups (P<0.05). The results demonstrate Res inhibitory effect and indicate that the inhibition mechanism of Res is to upgrade the protein and mRNA expression of p53 and to downgrade the protein and mRNA expression of SVV, thus inducing the apoptosis of tumor cells.
Related JoVE Video
Occurrence and removal of antibiotic resistance genes in municipal wastewater and rural domestic sewage treatment systems in eastern China.
Environ Int
PUBLISHED: 01-23-2013
Show Abstract
Hide Abstract
Antibiotic resistance genes (ARGs) are emerging environmental contaminants and pose a threat to public health. In this study, four tetracycline resistance genes (tetM, tetO, tetQ and tetW) and two sulfonamide resistance genes (sulI and sulII) were evaluated in 4 municipal wastewater and 8 rural domestic sewage treatment systems with different wastewater handling abilities and treatment processes using quantitative polymerase chain reaction (qPCR). In the influents, the relative abundance of different ARGs showed significant variations among the sampling sites. In addition, significant correlations (tetQ: R(2)=0.712, P<0.05; tetO: R(2)=0.394, P<0.05) between the gene copy numbers and wastewater-receiving capacity were observed. Statistical analysis revealed a positive correlation (R(2)=0.756, P<0.05) between the gene copy numbers of sulI and intI1, whereas the gene numbers of tetM and sulI were strongly correlated with 16S rDNA. Significant reductions (1-3 orders of magnitude) in ARGs were observed in municipal wastewater treatment systems, but a smaller reduction was found in the rural domestic sewage treatment systems. These results provide insights into the occurrence and removal of ARGs in wastewater treatment systems in both rural and urban areas in eastern China.
Related JoVE Video
Janus graphene from asymmetric two-dimensional chemistry.
Nat Commun
PUBLISHED: 01-09-2013
Show Abstract
Hide Abstract
Janus materials have distinct surfaces on their opposite faces. Graphene, a two-dimensional giant molecule, provides an excellent candidate to fabricate the thinnest Janus discs and study the asymmetric chemistry of atomic-thick nanomembranes using covalent chemical functionalisation. Here we present the first experimental realisation of nonsymmetrically modified single-layer graphene--Janus graphene--which is fabricated by a two-step surface covalent functionalisation assisted by a poly(methyl methacrylate)-mediated transfer approach. Four types of Janus graphene are produced by co-grafting of halogen and aryl/oxygen-functional groups on each side. Chemical decorations on one side are found to be capable of affecting both chemical reactivity and physical wettability of the opposite side, indicative of communication between the two grafted groups. This novel asymmetric structure provides a platform for theoretical and experimental studies of two-dimensional chemistry and graphene devices with multiple functions.
Related JoVE Video
Free radical reactions in two dimensions: a case study on photochlorination of graphene.
Small
PUBLISHED: 01-07-2013
Show Abstract
Hide Abstract
Graphene, a two-dimensional giant-molecule of sp(2) -bonded carbon atoms, provides a perfect platform for studying free radical reaction chemistry in two-dimensions, which holds promise to control the chemical functionality of graphene. Free-radical photochlorination of graphene is used as an example to investigate the thickness, stacking order, and single- and double-side dependent reactivity in graphene. Anomalously low reactivity is observed in the photochlorination of AB-stacked bilayer graphene in comparison with that of few-layer graphene. Double-sided chlorination of graphene shows higher reactivity and chlorine coverage than single-sided reaction. It is also experimentally and theoretically demonstrated that chlorine free radicals at low coverage prefer to form a stable charge-transfer complex with graphene, which highly enhances graphenes conductivity and simultaneously generates a pseudo-bandgap through noninvasive doping. Moreover, the initial accumulation of chlorine radicals is considered as the rate-determining step of photochlorination of graphene.
Related JoVE Video
Identification of the forkhead transcriptional factor 2 (FOXL2) gene mutations in four Chinese families with blepharophimosis syndrome.
Mol. Vis.
PUBLISHED: 01-01-2013
Show Abstract
Hide Abstract
To determine the genetic origin of disease in four Chinese families with blepharophimosis syndrome.
Related JoVE Video
Bioaccumulation and trophic transfer of mercury in a food web from a large, shallow, hypereutrophic lake (Lake Taihu) in China.
Environ Sci Pollut Res Int
PUBLISHED: 11-04-2011
Show Abstract
Hide Abstract
Due to the fast development of industry and the overuse of agrichemicals in past decades, Lake Taihu, an important source of aquatic products for Eastern China, has simultaneously suffered mercury (Hg) contamination and eutrophication. The objectives of this study are to understand Hg transfer in the food web in this eutrophic, shallow lake and to evaluate the exposure risk of Hg through fish consumption.
Related JoVE Video
Differentiation of Schisandra chinensis and Schisandra sphenanthera using metabolite profiles based on UPLC-MS and GC-MS.
Nat. Prod. Res.
PUBLISHED: 08-23-2011
Show Abstract
Hide Abstract
Historically, Schisandra chinensis and S. sphenanthera have been widely used in traditional Chinese medicine. Although both species are in the genus Schisandra, they have dissimilar therapeutic effects that may be attributed to compositional differences in secondary metabolites. We developed a method to compare these metabolites obtained from the above plant species using ultra-performance liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry coupled with multivariate statistical analyses. The critical markers we used to discriminate between both plant species resulted in the identification and quantification of six lignans and seven essential oils. We believe that our approach provided a sensitive, reliable and robust method to conveniently classify medicinal plants that can be used to explore subtle variations among different species or plants from different geographical locations.
Related JoVE Video
Prognostic value of matrix metalloproteinase-1/ proteinase-activated receptor-1 signaling axis in hepatocellular carcinoma.
Pathol. Oncol. Res.
PUBLISHED: 06-11-2011
Show Abstract
Hide Abstract
Matrix metalloproteinase-1 (MMP-1) is proposed to be involved in both tumor cell invasion and metastasis. MMP-1 proteolytically activates protease activated receptor-1 (PAR-1), which also plays an important role in tumor development and progression. However, it is currently unknown whether MMP-1 activation of PAR-1 has relevance to the progression of hepatocellular carcinoma (HCC). To address this problem, we investigate the clinicopathological and prognostic value of MMP-1/PAR-1 signaling axis in HCC. Immunohistochemistry assay was used to determine the expression of MMP-1 and PAR-1 proteins in normal and HCC tissues. The correlations of MMP-1 and PAR-1 expression with clinicopathological parameters were assessed by Chi-squared test. Patient survival and their differences were determined by Kaplan-Meier method and log-rank test. Cox regression was adopted for multivariate analysis of prognostic factors. MMP-1 and PAR-1 immunoreactivities were negative or low in normal liver tissues, but high in HCC tissues. PAR-1 expression was significantly correlated with that of MMP-1 (r?=?0.896, p?
Related JoVE Video
Role of bile salt in regulating Mcl-1 phosphorylation and chemoresistance in hepatocellular carcinoma cells.
Mol. Cancer
PUBLISHED: 04-20-2011
Show Abstract
Hide Abstract
Glycochenodeoxycholate (GCDA) is one of the major human bile salts. Bile salts stimulate cell survival and proliferation through the mitogen-activated protein kinase, but the downstream signaling mechanism(s) remains enigmatic. Mcl-1 is an antiapoptotic molecule of the Bcl2 family that is extensively overexpressed in tumor tissues of patients with hepatocellular carcinoma (HCC).
Related JoVE Video
Oral immunization with attenuated Salmonella carrying a co-expression plasmid encoding the core and E2 proteins of hepatitis C virus capable of inducing cellular immune responses and neutralizing antibodies in mice.
Vaccine
PUBLISHED: 01-11-2011
Show Abstract
Hide Abstract
Hepatitis C virus (HCV) core protein has long been considered an attractive candidate for inclusion in a protective vaccine. However, this protein may hamper the development of systemic immune responses because of its immune suppressive properties. We previously reported that immune responses to HCV core protein could be efficiently induced by attenuated Salmonella carrying the HCV core protein, but not the HCV core DNA vaccine. To optimize the combination of the core protein and envelope protein 2 (E2) into a vaccine formulation to induce cellular immune responses and neutralizing antibodies, we constructed a plasmid containing two expression cassettes. One expression cassette was included to regulate the expression of HCV core protein by an inducible in vivo-activated Salmonella promoter, the other was included to regulate the expression of HCV E2 protein by the cytomegalovirus enhancer/promoter. Oral immunization of BALB/c mice with the attenuated Salmonella strain SL7207 carrying this plasmid efficiently induced HCV core and E2-specific cellular immune responses and antibodies. IgG purified from immunized mice could neutralize the infectivity of HCV pseudoparticles (HCVpp) of both the autologous Con 1 isolate and the heterologous H77 isolate, and cell culture produced HCV (HCVcc) of Con1-JFH1 chimera. These results indicated that this vaccine strategy can effectively deliver core and E2 protein to the immune system and provide a promising approach for the development of prophylactic and therapeutic vaccines against HCV infection.
Related JoVE Video
Mechanistically probing lipid-siRNA nanoparticle-associated toxicities identifies Jak inhibitors effective in mitigating multifaceted toxic responses.
Mol. Ther.
PUBLISHED: 12-21-2010
Show Abstract
Hide Abstract
A major hurdle for harnessing small interfering RNA (siRNA) for therapeutic application is an effective and safe delivery of siRNA to target tissues and cells via systemic administration. While lipid nanoparticles (LNPs) composed of a cationic lipid, poly-(ethylene glycol) lipid and cholesterol, are effective in delivering siRNA to hepatocytes via systemic administration, they may induce multi-faceted toxicities in a dose-dependent manner, independently of target silencing. To understand the underlying mechanism of toxicities, pharmacological probes including anti-inflammation drugs and specific inhibitors blocking different pathways of innate immunity were evaluated for their abilities to mitigate LNP-siRNA-induced toxicities in rodents. Three categories of rescue effects were observed: (i) pretreatment with a Janus kinase (Jak) inhibitor or dexamethasone abrogated LNP-siRNA-mediated lethality and toxicities including cytokine induction, organ impairments, thrombocytopenia and coagulopathy without affecting siRNA-mediated gene silencing; (ii) inhibitors of PI3K, mammalian target of rapamycin (mTOR), p38 and I?B kinase (IKK)1/2 exhibited a partial alleviative effect; (iii) FK506 and etoricoxib displayed no protection. Furthermore, knockout of Jak3, tumor necrosis factor receptors (Tnfr)p55/p75, interleukin 6 (IL-6) or interferon (IFN)-? alone was insufficient to alleviate LNP-siRNA-associated toxicities in mice. These indicate that activation of innate immune response is a primary trigger of systemic toxicities and that multiple innate immune pathways and cytokines can mediate toxic responses. Jak inhibitors are effective in mitigating LNP-siRNA-induced toxicities.
Related JoVE Video
Nanoflower arrays of rutile TiO2.
Chem. Commun. (Camb.)
PUBLISHED: 11-16-2010
Show Abstract
Hide Abstract
Stacks of multilayered rutile TiO(2) nanoflowers can grow on a titanium film through a simple acid vapour oxidation (AVO) method. The growth of this interesting hierarchical architecture is due to the formation of rutile {101} twinned structures and a subtle mismatching between the lattice spacings of the substrate and product.
Related JoVE Video
Formation mechanism of CaTiO3 hollow crystals with different microstructures.
J. Am. Chem. Soc.
PUBLISHED: 09-17-2010
Show Abstract
Hide Abstract
The crystal growth of CaTiO(3) hollow crystals with different microstructures has been investigated. In a water-free poly(ethylene glycol) 200 (PEG-200) solution, CaTiO(3) nanocubes formed first. The nanocubes underwent an oriented self-assembly into spherical particles, enhanced by the surface-adsorbed polymer molecules. Since the growth of nanocubes and their aggregation took place simultaneously, the nanocubes in the outer shells were larger than those in the cores. Disappearance of the small nanocubes in the cores of the spheres during an Ostwald ripening process led to spherical hollow crystals. Addition of a small amount of water (1.25 vol %) in the polymer solution enhanced surface recrystallization of the aggregated spheres, forming a cubic morphology. The orthorhombic distortion of the perovskite CaTiO(3) structure did not have a significant effect on the nanocube aggregation, resulting in a domain structure in the shells. Single-crystalline hollow cubes were produced with a slightly higher water content, e.g., 5 vol %. This process of (1) aggregation of nanocubes and (2) surface crystallization followed by (3) surface-to-core extension of recrystallization gives a good example of the reversed crystal growth route in ceramic materials. The proposed formation mechanism of the hollow CaTiO(3) crystals would enable us to control the microstructures of these materials and to explain the formation of many other hollow crystals.
Related JoVE Video
Continuous shape- and spectroscopy-tuning of hematite nanocrystals.
Inorg Chem
PUBLISHED: 08-20-2010
Show Abstract
Hide Abstract
Uniform hexagonal hematite (?-Fe(2)O(3)) nanoplates have been synthesized by a facile alcohol-thermal reaction, and a new nanostructure of ?-Fe(2)O(3) has been proposed. Each nanoplate is enclosed by (0001) basal planes and {1012} side surfaces. The phase, size, shape, and growth orientation of these nanocrystals were characterized by powder X-ray diffraction and electron microscopy. The thickness and diameter of these nanocrystals could be finely tuned by the selective use of alcohol solvent with increasing carbon atom number in the linear alkyl chain. A variety of nanocrystals with systemically changeable shapes from nanoplates to nanograins have been obtained. Specific adsorption of alcohol molecules on polar (0001) facets is proposed to be the main issue to modify the growth behavior of hematite nanocrystals. The presence of distilled water and the addition of sodium acetate have also been investigated. Either of them has a great influence on the growth of hematite nanocrystals, and shape-controlled growth can be rationally achieved. In addition, the post-aging of as-grown hematite nanocrystals in alcohol and distilled water has also been described. Both vibration spectroscopy (i.e., FTIR and Raman) and electronic spectra (diffused reflectance spectra) of these nanocrystals with a continuing shape change show a highly shape-dependent nature.
Related JoVE Video
Noninvasive imaging of lipid nanoparticle-mediated systemic delivery of small-interfering RNA to the liver.
Mol. Ther.
PUBLISHED: 07-13-2010
Show Abstract
Hide Abstract
Mouse models with liver-specific expression of firefly luciferase were developed that enable a noninvasive and longitudinal assessment of small-interfering RNA (siRNA)-mediated gene silencing in hepatocytes of live animals via bioluminescence imaging. Using these models, a set of lipid nanoparticles (LNPs) with different compositions of cationic lipids, polyethylene glycol (PEG), and cholesterol, were tested for their abilities in delivering a luciferase siRNA to the liver via systemic administration. A dose-dependent luciferase knockdown by LNP/siRNA assemblies was measured by in vivo bioluminescence imaging, which correlated well with the results from parallel ex vivo analyses of luciferase mRNA and protein levels in the liver. RNA interference (RNAi)-mediated target silencing was further confirmed by the detection of RNAi-specific target mRNA cleavage. A single dose of LNP02L at 3 mg/kg (siRNA) caused 90% reduction of luciferase expression and the target repression lasted for at least 10 days. With identical components, LNPs containing 2% PEG are more potent than those with 5.4% PEG. Our results demonstrate that these liver-luciferase mouse models provide a powerful tool for a high-throughput evaluation of hepatic delivery platforms by noninvasive imaging and that the molar ratio of PEG lipid can affect the efficacy of LNPs in silencing liver targets via systemic administration.
Related JoVE Video
Structural shifts of gut microbiota as surrogate endpoints for monitoring host health changes induced by carcinogen exposure.
FEMS Microbiol. Ecol.
PUBLISHED: 07-07-2010
Show Abstract
Hide Abstract
This study monitored structural shifts of gut microbiota of rats developing precancerous mucosal lesions induced by carcinogen 1,2-dimethyl hydrazine (DMH) treatment using PCR-denaturing gradient gel electrophoresis (DGGE) and 454 pyrosequencing on the 16S rRNA gene V3 region. Partial least square discriminant analysis of DGGE fingerprints showed that the gut microbiota structure of treated animals was similar to that of the controls 1 and 3 weeks after DMH treatments, but significantly different 7 weeks after DMH treatments, when a large number of aberrant crypt foci (ACF) developed in their colons. Martens uncertainty test, followed by anova test (P<0.05) identified Ruminococcus-like and Allobaculum-like bacteria as key variables for discrimination of DMH-treated rats from controls. Real-time PCR confirmed the significant increase of the Ruminococcus obeum and the Allobaculum-like bacteria in DMH-treated rats. UniFrac analysis based on V3 pyrosequencing further validated that the gut microbiota structures of treated and control animals were similar at an early stage, but segregated after ACF formation. Thirteen operational taxonomic units including Ruminococcus-like and Allobaculum-like bacteria were identified as key variables for the discrimination of DMH-treated rats from controls. Dynamic analysis of gut microbiota may become a noninvasive strategy for monitoring host health changes induced by carcinogen exposure.
Related JoVE Video
Complex ZnO nanotree arrays with tunable top, stem and branch structures.
Nanoscale
PUBLISHED: 05-25-2010
Show Abstract
Hide Abstract
Hierarchical tree-, mushroom- and cockscomb-like ZnO arrays with increasing branching order and complexities have been grown in situ on cheap zinc plates by a simple hydrothermal oxidation approach. Their morphology, crystal structure and orientation relationship are characterized by powder X-ray diffraction, scanning electron microscopy (SEM) and cross-sectional high-resolution transmission electron microscopy (HRTEM). The wurtzite ZnO arrays, growing mainly in the [0001] direction, show a special orientation relationship between the stem and the branch as well as a novel stem-branch boundary which might be attributed to the least mismatch between [symbol: see text] and (0002) lattice planes. The co-solvent ethylenediamine (en) was used to control the morphology and complexing of these complex ZnO nanostructures. Correspondingly, the physical properties of ZnO nanostructure assembly arrays were tuned and a stronger UV emission was observed with negligible emissions in the visible range, indicating the highly crystalline features of the complex ZnO micro-/nanostructured materials.
Related JoVE Video
Synthesis and in vitro/in vivo anti-cancer evaluation of curcumin-loaded chitosan/poly(butyl cyanoacrylate) nanoparticles.
Int J Pharm
PUBLISHED: 05-10-2010
Show Abstract
Hide Abstract
We have synthesized novel cationic poly(butyl) cyanoacrylate (PBCA) nanoparticles coated with chitosan, formulation of curcumin nanoparticles. The size and zeta potential of prepared curcumin nanoparticles were about 200 nm and +29.11 mV, respectively with 90.04% encapsulation efficiency. The transmission electron microscopy (TEM) study revealed the spherical nature of the prepared nanoparticles along with confirmation of particle size. Curcumin nanoparticles demonstrate comparable in vitro therapeutic efficacy to free curcumin against a panel of human hepatocellular cancer cell lines, as assessed by cell viability (3-[4,5-dimethylthiazol-2-yl]2,5-diphenyltetrazolium bromide assay [MTT assay]) and proapoptotic effects (annexin V/propidium iodide staining). In vivo, curcumin nanoparticles suppressed hepatocellular carcinoma growth in murine xenograft models and inhibited tumor angiogenesis. The curcumin nanoparticles mechanism of action on hepatocellular carcinoma cells is a mirror that of free curcumin.
Related JoVE Video
Clinicopathologic and prognostic significance of CD24 in gallbladder carcinoma.
Pathol. Oncol. Res.
PUBLISHED: 03-23-2010
Show Abstract
Hide Abstract
CD24, a small cell surface protein, has emerged as a novel oncogene and prognostic factor for poor outcomes in many human cancers. However, the association of CD24 expression pattern in gallbladder carcinoma with patients survival has not been reported. To shed light on this problem, we performed an analysis on the relationship between CD24 expression and prognostic parameters in gallbladder carcinoma. CD24 expression was examined immunohistochemically on paraffin-embedded tissue specimens from 207 patients who underwent surgical treatment for gallbladder carcinoma in the period between January 2004 and May 2009. CD24 positive expression was found in 78.7% (163/207) of the tumor samples. It tended to be associated positively with tumor histological grades and pT stages. Kaplan-Meier curves showed that CD24 positive expression was significantly related to decreased overall survival (p < 0.01). Multivariate analysis, including CD24 expression, pT stage, tumor grade, and resection margin involvement, showed that CD24 positive expression was an independent prognostic marker in gallbladder carcinoma (p = 0.02; relative risk = 1.6). Our data demonstrate for the first time that CD24 is an important marker of malignancy and poor prognosis in gallbladder carcinoma. Its detection combined with cancerous staging may increase the ability of investigators to predict the prognosis of patients with gallbladder carcinoma. Furthermore, the CD24 antigen represents an attractive target for specific therapies with monoclonal antibodies in patients with CD24-overexpressing gallbladder carcinoma, so the detection of CD24 may help clinicians select patients likely to benefit from novel molecular therapies.
Related JoVE Video
ADAM-17 over-expression in gallbladder carcinoma correlates with poor prognosis of patients.
Med. Oncol.
PUBLISHED: 02-17-2010
Show Abstract
Hide Abstract
The ADAMs is a multi-functional gene family of membrane proteins possessing a disintegrin and metalloprotease domain. They have potential implications for the metastasis of human tumor cells via cell adhesion and protease activities. However, no studies have yet comprehensively examined the expression of ADAMs in gallbladder carcinoma. The aim of this study was to test the hypothesis that ADAM-17 (otherwise known as tumor necrosis factor-? converting enzyme) is involved in the progression of gallbladder carcinoma. Two hundreds samples of gallbladder carcinoma and sixty non-cancerous gallbladder samples were used to measure the expression of total ADAM-17 by enzyme-linked immunosorbent assay, and the precursor and active forms by western blotting analysis. Expression of ADAM-17 was significantly increased in tumors with high histological grade and pT stage compared with low histological grade and pT stage tumors and was not associated with patients gender, age, histological type, and resection margin involvement. Patients with high expression of ADAM-17 had a significantly shorter overall survival compared with those with low expression. Significantly, the prognostic impact of ADAM-17 was independent of conventional prognostic factors for gallbladder carcinoma. The current study demonstrated that the over-expression of ADAM-17 in patients with gallbladder carcinoma was linked closely with histological grade, pT stage and prognosis, and thus provides further impetus for exploiting ADAM-17 as new target for the treatment of gallbladder carcinoma.
Related JoVE Video
Overexpression of EphA2, MMP-9, and MVD-CD34 in hepatocellular carcinoma: Implications for tumor progression and prognosis.
Hepatol. Res.
PUBLISHED: 09-25-2009
Show Abstract
Hide Abstract
Aim: To investigate the expression of erythropoietin-producing hepatocellular (Eph)A2 receptor, matrix metalloproteinase (MMP)-9, and angiogenesis in hepatocellular carcinoma (HCC), in order to reveal their expression correlations with tumor invasion, metastasis, and prognosis. Methods: From January 2000 to June 2003, 129 specimens of resected tumors from the patients with HCC were obtained. Corresponding pericarcinomatous liver tissues were also obtained and selected as a control group. Expressions of EphA2, MMP-9, and CD34 were detected with immunohistochemical staining. Microvascular density (MVD) was calculated with counting of CD34-positive vascular endothelial cells. Results: The expressions of EphA2, MMP-9, and MVD in the HCC tissues were significantly higher than those in the pericarcinomatous liver tissues (P < 0.01). Statistical analysis showed there were significant correlations between the expressions of EphA2, MMP-9 and MVD in some classicclinicopathological parameters (i.e. tumor nodule, vein invasion, tumor, node, metastasis stages, extrahepatic metastasis; P < 0.05). The correlation between EphA2 and MMP-9 expression was positive (r = 0.625, P = 0.011). Tumor MVD was closely associated with EphA2 (r = 0.281, P = 0.01) and MMP-9 (r = 0.319, P < 0.01) expressions. In particular, EphA2, MMP-9, and MVD expressions levels were found to be independent prognostic factors after HCC resection. Conclusions: Overexpressions of EphA2 and MMP-9 relate to tumor progression, metastasis, and prognosis in HCC. The present study suggests that EphA2 is associated with key mediators of angiogenesis and invasion.
Related JoVE Video
Cross-medal arrays of Ta-doped rutile titania.
J. Am. Chem. Soc.
PUBLISHED: 08-27-2009
Show Abstract
Hide Abstract
A rutile microstructure with a novel cross-medal morphology was prepared via a hydrothermal method by using a Tantalum foil as both the doping source and the substrate. This rutile cross-medal prefers to grow along an unprecedented preferential orientation of <110> directions from the substrate, which is very different from the traditional c-axis. The new material exhibits highly enhanced field emission (FE) properties.
Related JoVE Video
Development of a new poly(ethylene glycol)-graft-poly(D,L-lactic acid) as potential drug carriers.
J Biomed Mater Res A
PUBLISHED: 05-12-2009
Show Abstract
Hide Abstract
A new poly(ethylene glycol) (PEG)-modified poly(D,L-lactic acid) (PLA) was synthesized by grafting maleic anhydride onto PLA and subsequently amidating with O,O-bis-(2-aminopropyl) polypropylene glycol-block-polyethylene oxide-block-polypropylene glycol (H2N-PEG-NH2, Mw: 600). Its structure was confirmed by FTIR, DSC, 1H NMR, GPC, and ninhydrin test. The polymer is more hydrophilic compared with PLA according to contact angle tests, and is degradable as determined from its pH and mass changes during degradation. The polymer shows a 62.7% decrease in BSA absorption compared with PLA when dried in air, and a 82.76% decrease when dried under 65% humidity, as measured by fluorospectrophotometry. The polymer promotes adhesion and proliferation of osteoblasts, determined by MTT assay. With this new polymer, spherical nanoscale aggregates encapsulated with or without hydrophilic dye are formed spontaneously in water, visualized by inverted microscope and AFM. The particle size is concentration dependent as confirmed by dynamic light scattering, and its critical micelle concentration was 1.124 microg/mL as determined by a fluorescence method. The good hydrophilicity, degradability, cellular compatibility, protein-resistance, self-aggregation, and reactivity of the polymer may lead to its potential applications in drug delivery.
Related JoVE Video
Hierarchically nanostructured rutile arrays: acid vapor oxidation growth and tunable morphologies.
ACS Nano
PUBLISHED: 04-30-2009
Show Abstract
Hide Abstract
A general acid vapor oxidation (AVO) strategy has been developed to grow highly oriented hierarchically structured rutile TiO(2) nanoarrays with tunable morphologies from titanium thin films. This is a simple one-pot synthesis approach involving the reaction of a titanium surface with the vapor generated from a hydrochloric acid solution in a Teflon lined autoclave. To the best of our knowledge, this is the first successful attempt to grow ordered tree-like titania nanoarrays. A possible formation mechanism for the interesting architectures has been proposed based on series of time-dependent experiments. By adjusting the initial HCl concentration, films of different rutile structures including nanotrees, dendritic nanobundles, and nanorods can be selectively obtained. Subsequently, the surface morphologies and wettability can be readily tuned.
Related JoVE Video
Metabonomics approach to understanding acute and chronic stress in rat models.
J. Proteome Res.
PUBLISHED: 03-19-2009
Show Abstract
Hide Abstract
The effects of acute and chronic stress on the production of systemic metabolites were investigated in male Sprague-Dawley (SD) rats. Metabolites excreted in urine were analyzed using GC/MS in conjunction with multivariate and univariate statistical techniques. SD rats were subjected to two kinds of acute stress and chronic unpredictable mild stress, respectively. Metabolic analysis demonstrated that urinary expression of a number of metabolites including glutamate, glutamine, homovanillate, proline, succinate, citrate, and tyrosine altered in the acute stress model in the same way as in the chronic model, while pimelate and hippurate changed in the opposite trend. The results suggested that the stress induced metabolic perturbations were reversible and nonspecific. Metabolic response to chronic combined stress revealed biochemical clues to depression-like symptoms validated by behavior and physiologic results. This study provides a noninvasive and dynamic analytical strategy for the characterization of endogenous metabolic perturbations induced by external stress.
Related JoVE Video
Cationic polybutyl cyanoacrylate nanoparticles for DNA delivery.
J. Biomed. Biotechnol.
PUBLISHED: 03-11-2009
Show Abstract
Hide Abstract
To enhance the intracellular delivery potential of plasmid DNA using nonviral vectors, we used polybutyl cyanoacrylate (PBCA) and chitosan to prepare PBCA nanoparticles (NPs) by emulsion polymerization and prepared NP/DNA complexes through the complex coacervation of nanoparticles with the DNA. The object of our work is to evaluate the characterization and transfection efficiency of PBCA-NPs. The NPs have a zeta potential of 25.53 mV at pH 7.4 and size about 200 nm. Electrophoretic analysis suggested that the NPs with positive charges could protect the DNA from nuclease degradation and cell viability assay showed that the NPs exhibit a low cytotoxicity to human hepatocellular carcinoma (HepG2) cells. Qualitative and quantitative analysis of transfection in HepG2 cells by the nanoparticles carrying plasmid DNA encoding for enhanced green fluorescent protein (EGFP-N1) was done by digital fluorescence imaging microscopy system and fluorescence-activated cell sorting (FACS). Qualitative results showed highly efficient expression of GFP that remained stable for up to 96 hours. Quantitative results from FACS showed that PBCA-NPs were significantly more effective in transfecting HepG2 cells after 72 hours postincubation. The results of this study suggested that PBCA-NPs have favorable properties for nonviral delivery.
Related JoVE Video
Traditional Chinese medicine: balancing the gut ecosystem.
Phytother Res
PUBLISHED: 03-03-2009
Show Abstract
Hide Abstract
Gut microflora has become a topic of interest in life sciences in the context of global systems biology, in which human biological system is viewed as superorganisms involving an internal ecosystem of diverse microbiome. We conceive that multi-pathway modulations of the human gut microbial system exerted by traditional Chinese medicines (TCMs) to restore the balance of the gut ecology may account for a large portion of their effectiveness in host during treatment. Such a concept is evidenced by series of studies which have revealed an interactive relationship between gut microflora and TCM, involving the two important aspects: gut microflora-dependent drug metabolism in TCM and gut microflora-targeted modulation of physiological conditions, both of which highlight the significance of gut microflora involvement in the future TCM investigation.
Related JoVE Video
A rapid ultra-performance liquid chromatography-electrospray Ionisation mass spectrometric method for the analysis of saponins in the adventitious roots of Panax notoginseng.
Phytochem Anal
PUBLISHED: 02-21-2009
Show Abstract
Hide Abstract
Saponins are bioactive compounds employed in the prevention and treatment of cardiovascular and cerebrovascular diseases. The adventitious roots of Panax notoginseng may offer an alternative source of saponins. Identification and determination of saponins in the crude extract is challenging owing to their similar structures and the lack of standards.
Related JoVE Video
Polyhydroxyalkanoate production from fermented volatile fatty acids: effect of pH and feeding regimes.
Bioresour. Technol.
Show Abstract
Hide Abstract
The combined fermentation of sludge from the secondary sedimentation tank of municipal wastewater treatment plants and food waste enables not only waste reduction, but also the acquisition of volatile fatty acids (VFAs) for the biosynthesis of polyhydroxyalkanoates (PHAs). To better understand variables influencing the production of VFAs and PHAs, this study considered anaerobic fermentation of VFAs under different pH conditions. The production of VFA was the highest at an initial pH of 9.0, reaching 25,934 ± 1,485 mg COD/L and a VFAs/S COD ratio of 0.61 ± 0.04. When the fermentation liquid was used as a carbon source for PHA biosynthesis, continuous pulsed feeding resulted in the highest PHA synthesis rate of 64.5 ± 1.8%, while the culture receiving a one-time feeding had the lowest rate of only 51.5 ± 2.0%.
Related JoVE Video
Anti-HBV efficacy of combined siRNAs targeting viral gene and heat shock cognate 70.
Virol. J.
Show Abstract
Hide Abstract
Hepatitis B virus (HBV) infection is a major health concern with more than two billion individuals currently infected worldwide. Because of the limited effectiveness of existing vaccines and drugs, development of novel antiviral strategies is urgently needed. Heat stress cognate 70 (Hsc70) is an ATP-binding protein of the heat stress protein 70 family. Hsc70 has been found to be required for HBV DNA replication. Here we report, for the first time, that combined siRNAs targeting viral gene and siHsc70 are highly effective in suppressing ongoing HBV expression and replication.
Related JoVE Video
Metabonomics approach to assessing the modulatory effects of St Johns wort, ginsenosides, and clomipramine in experimental depression.
J. Proteome Res.
Show Abstract
Hide Abstract
The protective effects of St Johns Wort extract (SJ), ginsenosides (GS), and clomipramine (CPM) on chronic unpredictable mild stress (CUMS)-induced depression in rats were investigated by using a combination of behavioral assessments and metabonomics. Metabonomic analyses were performed using gas chromatography/mass spectrometry in conjunction with multivariate and univariate statistical analyses. During and at the end point of the chronic stress experiment, food consumption, body weight, adrenal gland, thymus and spleen indices, behavior scores, sucrose consumption, and stress hormone levels were measured. Changes in these parameters reflected characteristic phenotypes of depression in rats. Metabonomic analysis of serum, urine, and brain tissue revealed that CPM and SJ mainly attenuated the alteration of monoamine neurotransmitter metabolites, while GS affected both excitatory/inhibitory amino acids and monoamine neurotransmitter metabolites. GS also attenuated the stress-induced alterations in cerebrum and peripheral metabolites to a greater extent than CPM and SJ. These results provide important mechanistic insights into the protective effects of GS against CUMS-induced depression and metabolic dysfunction.
Related JoVE Video
[Investigation of differences in subjective demand for orthodontic treatment of middle school students in zones with different economic levels].
Hua Xi Kou Qiang Yi Xue Za Zhi
Show Abstract
Hide Abstract
To investigate the acquaintance to orthodontics and possible factors that obstruct orthodontic treatment in middle school students in zones with different economic levels in Jiangjin, Chongqing.
Related JoVE Video
Transcriptomic and metabonomic profiling reveal synergistic effects of quercetin and resveratrol supplementation in high fat diet fed mice.
J. Proteome Res.
Show Abstract
Hide Abstract
Dietary quercetin and resveratrol have been frequently used in treating various diseases, but the underlying mechanisms are not entirely clear. Here, we report combined transcriptomic and metabonomic profiling that showed that the combined supplementation with quercetin and resveratrol produced synergistic effects on a high-fat diet-induced metabolic phenotype in mice. Histological and phenotypic improvements in serum and hepatic total cholesterol, insulin, fasting blood glucose, and HbA1c were also observed in mice receiving combined quercetin and resveratrol supplementation. This combined quercetin and resveratrol supplementation resulted in significant restoration of gene sets in functional pathways of glucose/lipid metabolism, liver function, cardiovascular system, and inflammation/immunity, which were altered by high fat diet feeding. The integration of transcriptomic and metabonomic data indicated quercetin and resveratrol supplementation enhanced processes of glycolysis and fatty acid oxidation, as well as suppressed gluconeogenesis. These alterations discovered at both the transcriptional and metabolic levels highlight the significance of combined "omics" platforms for elucidating mechanistic pathways altered by dietary polyphenols, such as quercetin and resveratrol, in a synergistic manner.
Related JoVE Video
Sectional anatomy aid for improvement of decompression surgery approach to vertical segment of facial nerve.
J Craniofac Surg
Show Abstract
Hide Abstract
The aim of this study was to find a surgical approach to a vertical segment of the facial nerve (VFN) with a relatively wide visual field and small lesion by studying the location and structure of VFN with cross-sectional anatomy. High-resolution spiral computed tomographic multiplane reformation was used to reform images that were parallel to the Frankfort horizontal plane. To locate the VFN, we measured the distances as follows: from the VFN to the paries posterior bony external acoustic meatus on 5 typical multiplane reformation images, to the promontorium tympani and the root of the tympanic ring on 2 typical images. The mean distances from the VFN to the paries posterior bony external acoustic meatus are as follows: 4.47 mm on images showing the top of the external acoustic meatus, 4.20 mm on images with the best view of the window niche, 3.35 mm on images that show the widest external acoustic meatus, 4.22 mm on images with the inferior margin of the sulcus tympanicus, and 5.49 mm on images that show the bottom of the external acoustic meatus. The VFN is approximately 4.20 mm lateral to the promontorium tympani on images with the best view of the window niche and 4.12 mm lateral to the root of the tympanic ring on images with the inferior margin of the sulcus tympanicus. The other results indicate that the area and depth of the surgical wound from the improved approach would be much smaller than that from the typical approach. The surgical approach to the horizontal segment of the facial nerve through the external acoustic meatus and the tympanic cavity could be improved by grinding off the external acoustic meatus to show the VFN. The VFN can be found by taking the promontorium tympani and tympanic ring as references. This improvement is of high potential to expand the visual field to the facial nerve, remarkably without significant injury to the patients compared with the typical approach through the mastoid process.
Related JoVE Video
Urinary metabolite variation is associated with pathological progression of the post-hepatitis B cirrhosis patients.
J. Proteome Res.
Show Abstract
Hide Abstract
Cirrhosis is a common and terminal outcome of many chronic liver conditions. A urinary metabonomic study using gas chromatography-mass spectrometry (GC-MS) and ultra performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOFMS) was carried out to elucidate the pathophysiological basis of posthepatitis B cirrhosis in 63 posthepatitis B cirrhosis patients and 31 health controls. Urinary metabolic profile and corresponding differential metabolites associated with Child-Pugh (CP) grading of liver function were characterized, in addition to the blood routine, liver, and renal function tests. Multivariate statistical tools including principal component analysis (PCA) and orthogonal partial least-squares-discriminant analysis (OPLS-DA) were employed in the metabolite analysis along with a univariate statistical method, Wilcoxon-Mann-Whitney test. The alterations of differential metabolites contributing to the intergroup variation between healthy controls and cirrhotic patients, and among cirrhosis of CP grade A, B and C were also investigated. Six metabolites, ?-hydroxyhippurate, tyrosine-betaxanthin, 3-hydroxyisovalerate, canavaninosuccinate, estrone, and glycoursodeoxycholate, were significantly altered among cirrhotic patients with CP A, B, and C, reflecting abnormal metabolism of amino acid, bile acids, hormones, and intestinal microbial metabolism. The results show that dynamic alteration of urinary metabolome, characterized by the changes of a panel of the differential metabolite markers, is indicative of an exacerbated liver function, highlighting their diagnostic and prognostic potential for the liver cirrhosis development.
Related JoVE Video
In vitro and in vivo antitumoral action of metformin on hepatocellular carcinoma.
Hepatol. Res.
Show Abstract
Hide Abstract
Aims:? Metformin is a biguanide that has been widely used to treat type 2 diabetes. Several studies have shown that metformin is also effective in treating cancer, including hepatocellular carcinoma (HCC). The objective of this study was to evaluate the antitumor effects of metformin in HCC, and to investigate the potential molecular target(s) of metformin-mediated antitumor activity. Methods:? The antiproliferative effects of metformin were assessed in human HCC cell lines and normal human liver cells at various concentrations. Orthotopic xenograft tumors were established in athymic nude mice, and tumor growth was monitored after metformin treatment. Western blot analysis and cell cycle regulation were performed to determine the involvement of various mediators of apoptosis. Results:? Metformin specifically inhibited the growth of HCC cells without affecting the growth of normal liver cells both in vitro and in vivo. Metformin caused cell cycle arrest in HCC cells, which resulted in caspase-3 activation. Livin levels decreased in a dose-dependent manner upon metformin treatment. Metformin activated 5-adenosine monophosphate-activated protein kinase, inhibited the mammalian target of rapamycin pathway and downregulated Livin protein expression. Conclusion:? Our findings indicate that metformin is effective at initiating apoptosis and inhibiting key survival signaling pathways in HCC cells. These data provide a foundation for further studies to evaluate metformin in the clinic either as a single agent or in combination with other first-line agents as a treatment option for HCC.
Related JoVE Video
Metabonomic Variations Associated with AOM-Induced Precancerous Colorectal Lesions and Resveratrol Treatment.
J. Proteome Res.
Show Abstract
Hide Abstract
Resveratrol (Res), 3,5,4-trihydroxy-trans-stilbene, is an antioxidant found in the skin of red grapes and in several other plants. This phenolic compound has been recently reported to possess cancer chemopreventive activity that inhibits the process of carcinogenesis. However, the mechanisms underlying its anticancer effects remain largely unresolved. In this study, we investigated the chemoprotective effects of dietary Res in an azoxymethane (AOM) induced precancerous colorectal lesion model in male Wistar rats. The metabolic alterations in urine, sera, and colonic tissues of experimental rats perturbed by AOM intervention as well as the Res treatment were measured by a gas chromatography time-of-flight mass spectrometry (GC-TOFMS) analysis. Significant alterations of metabolites were observed in AOM group in urine, sera, and colonic tissues, which were attenuated by Res treatment and concurrent with the histopathological improvement with significantly decreased aberrant crypt foci (ACF) incidence. Representative metabolites include depleted glucose, ?-hydroxybutyrate (ketone body), hypoxanthine, and elevated branched chain amino acids (isoleucine and valine) and tryptophan in colonic tissue, as well as elevated serum aminooxyacetate and urinary 4-hydroxyphenylacetate and xanthurenate. These metabolic changes suggest that the preventive effect of Res is associated with attenuation of impaired glucose and lipid metabolism and elevated protein breakdown in colonic tissues from AOM-exposed rats. It also appears that Res induced significant metabolic alterations independent of the AOM-induced metabolic changes. The significantly altered metabolites identified in Res-AOM group relative to AOM group include arachidonate, linoleate, glutamate, docosahexaenoate, palmitelaidate, 2-aminobutyrate, pyroglutamate, and threonate, all of which are involved in inflammation and oxidation processes. This suggests that Res exerts the chemopreventive effects on ACF formation by anti-inflammatory and antioxidant mechanisms in addition to amelioration of AOM-induced mitochondrial disruption.
Related JoVE Video
MIF produced by bone marrow-derived macrophages contributes to teratoma progression after embryonic stem cell transplantation.
Cancer Res.
Show Abstract
Hide Abstract
Although stem cell therapy holds promise as a potential treatment in a number of diseases, the tumorigenicity of embryonic stem cells (ESC) and induced pluripotent stem cells remains a major obstacle. In vitro predifferentiation of ESCs can help prevent the risk of teratoma formation, yet proliferating neural progenitors can generate tumors, especially in the presence of immunosuppressive therapy. In this study, we investigated the effects of the microenvironment on stem cell growth and teratoma development using undifferentiated ESCs. Syngeneic ESC transplantation triggered an inflammatory response that involved the recruitment of bone marrow (BM)-derived macrophages. These macrophages differentiated into an M2 or angiogenic phenotype that expressed multiple angiogenic growth factors and proteinases, such as macrophage migration inhibitory factor (MIF), VEGF, and matrix metalloproteinase 9, creating a microenvironment that supported the initiation of teratoma development. Genetic deletion of MIF from the host but not from ESCs specifically reduced angiogenesis and teratoma growth, and MIF inhibition effectively reduced teratoma development after ESC transplantation. Together, our findings show that syngeneic ESC transplantation provokes an inflammatory response that involves the rapid recruitment and activation of BM-derived macrophages, which may be a crucial driving force in the initiation and progression of teratomas.
Related JoVE Video
The cross-transmission of 2009 pandemic influenza A (H1N1) infections among healthcare workers and inpatients in a chinese tertiary hospital.
Infect Control Hosp Epidemiol
Show Abstract
Hide Abstract
We reported 2009 H1N1 influenza infections among healthcare workers (HCWs) and inpatients and the prevention measures instituted in a large Chinese hospital. In total, 171 HCWs and 89 inpatients tested positive for H1N1. Sixteen HCWs had known hospital exposure, among whom only 7 had working-contact exposure. There was no influenza outbreak.
Related JoVE Video
Comparison of mercury speciation and distribution in the water column and sediments between the algal type zone and the macrophytic type zone in a hypereutrophic lake (Dianchi Lake) in Southwestern China.
Sci. Total Environ.
Show Abstract
Hide Abstract
During a heavy algal bloom in 2009, we collected lake water, surface sediment, sediment cores and porewater samples from Dianchi Lake to investigate the effect of eutrophication and different aquatic habitats (algal and macrophytic) on mercury (Hg) distribution and speciation in hypereutrophic lake. The total Hg (THg) concentration in the sediment and lake water was substantially elevated compared to uncontaminated lakes and reservoirs. The spatial distribution of THg pointed to waste water discharged from Kunming City as the dominant source of Hg in Dianchi Lake. Despite the high concentration of THg, the concentration of methyl mercury (MeHg) was relatively low compared to other deep water lakes and reservoirs, and the ratio of MeHg/THg was generally lower than 1% in lake water and sediments, implying the low potential of Hg methylation. No significant relationship was found between the total organic carbon (TOC) and MeHg in either surface sediment or sediment cores. This result is different from previous conclusions that an increase of organic material load in sediment can enhance the potential of Hg methylation in sediments. A significant relationship between the total S and MeHg in the two cores indicated that sulfur played an important role in Hg methylation. However, because of similar concentrations of MeHg and distinct differences in the S concentration in the two cores, the total S should not be a limiting factor for Hg methylation in sediment. The most important limiting factors controlling Hg methylation were high pH and Eh induced by heavy algal blooms and shallow water depth in Dianchi Lake because Hg methylation will be inhibited and the demethylation of MeHg may be accelerated under alkaline and oxic conditions.
Related JoVE Video

What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.