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.
Far-infrared surface emissivity and climate.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 11-03-2014
Show Abstract
Hide Abstract
Presently, there are no global measurement constraints on the surface emissivity at wavelengths longer than 15 ?m, even though this surface property in this far-IR region has a direct impact on the outgoing longwave radiation (OLR) and infrared cooling rates where the column precipitable water vapor (PWV) is less than 1 mm. Such dry conditions are common for high-altitude and high-latitude locations, with the potential for modeled climate to be impacted by uncertain surface characteristics. This paper explores the sensitivity of instantaneous OLR and cooling rates to changes in far-IR surface emissivity and how this unconstrained property impacts climate model projections. At high latitudes and altitudes, a 0.05 change in emissivity due to mineralogy and snow grain size can cause a 1.8-2.0 W m(-2) difference in the instantaneous clear-sky OLR. A variety of radiative transfer techniques have been used to model the far-IR spectral emissivities of surface types defined by the International Geosphere-Biosphere Program. Incorporating these far-IR surface emissivities into the Representative Concentration Pathway (RCP) 8.5 scenario of the Community Earth System Model leads to discernible changes in the spatial patterns of surface temperature, OLR, and frozen surface extent. The model results differ at high latitudes by as much as 2°K, 10 W m(-2), and 15%, respectively, after only 25 y of integration. Additionally, the calculated difference in far-IR emissivity between ocean and sea ice of between 0.1 and 0.2, suggests the potential for a far-IR positive feedback for polar climate change.
Related JoVE Video
Isolation and Characterization of Sesquiterpenes from Celastrus orbiculatus and Their Antifungal Activities against Phytopathogenic Fungi.
J. Agric. Food Chem.
PUBLISHED: 10-29-2014
Show Abstract
Hide Abstract
Celastrus orbiculatus is an insecticidal plant belonging to the Celastraceae family. In this survey on the secondary metabolites of plants for obtaining bioactive substances to serve agriculture, the chemical constituents of the fruits of C. orbiculatus were investigated. This phytochemical investigation resulted in the isolation of nine new and one known sesquiterpene. Their structures, especially the complicated stereochemical features, were elucidated on the basis of extensive NMR spectroscopic data analyses, time-dependent density functional theory CD calculations, and the CD exciton chirality method. Biological screenings disclosed that these sesquiterpenes showed antifungal activities against six phytopathogenic fungi. The results of our phytochemical investigation further disclosed the chemical components of C. orbiculatus, and biological screening implied that it may be potentially useful to protect crops against phytopathogenic fungi and the bioactive compounds may be regarded as candidate agents of antifungal agrochemicals for crop protection products.
Related JoVE Video
Room Temperature Hole-Burning of X-ray Induced Sm(2+) in Nanocrystalline Ba0.5Sr0.5FCl0.5Br0.5:Sm(3+) Prepared by Mechanochemistry.
J Phys Chem A
PUBLISHED: 09-24-2014
Show Abstract
Hide Abstract
Alloyed nanocrystalline Ba0.5Sr0.5FCl0.5Br0.5 doped with Sm(3+) ions was prepared by a facile ball milling method at room temperature. Spectral hole-burning properties of Sm(2+) ions from X-irradiated sample were investigated in the (7)F0-(5)D0 transition between 2.5 K and room temperature. The alloying allows a "chemical" broadening of the inhomogeneous width of the (7)F0-(5)D0 f-f transition to 40 cm(-1); spectral holes with a homogeneous width of 5 cm(-1) can be burnt, yielding a figure-of-merit of ?inh/?hom = 8. Mechanochemical preparation methods have a significant potential for the preparation of functional materials for applications in frequency domain optical data storage and as X-ray storage phosphors by allowing the preparation of tailored solid solutions.
Related JoVE Video
Anxiety- and depressive-like behaviors in olfactory deficient Cnga2 knockout mice.
Behav. Brain Res.
PUBLISHED: 09-01-2014
Show Abstract
Hide Abstract
There is a close neuroanatomical connection between odor and emotional processing. Olfactory dysfunction is found in various neurodegenerative and neuropsychiatric disorders. Here, mice take the cyclic nucleotide gated channel 2 mutant gene (Cnga2), which is critical for olfactory sensory neurons to generate odor induced action potentials were used. The Cnga2 mice were congenitally anosmic. Adult mice were tested in a series behavioral paradigm such as open field, light/dark box, forced swim test and Y-maze. Our study found that Cnga2 mice showed increased anxiety- and depressive-like behaviors than their wide type siblings. However, Cnga2 mice showed no difference from the wide types when tested in the two-trial recognition Y-maze. The results indicate that innate olfactory deficiency might modulate emotional behaviors in mice.
Related JoVE Video
Mycoplasma Hyorhinis Infection Promotes NF-?B-Dependent Migration of Gastric Cancer Cells.
Cancer Res.
PUBLISHED: 08-18-2014
Show Abstract
Hide Abstract
Chronic infection of Mycoplasma hyorhinis (M. hyorhinis) has been postulated to be associated with several types of cancer, but its effect on patients' survival and host factors mediating its infection remain unclear. Herein, we demonstrated that M. hyorhinis p37 protein expression in gastric cancer tissues predicts poor survival and associates with metastasis. M. hyorhinis infects mammalian cells and promotes gastric cancer cell invasiveness via its membrane protein p37. Synthesized peptide corresponding to the N-terminus of p37 prevents M. hyorhinis infection. Host Annexin A2 (ANXA2) interacts with the N-terminus of p37. In addition, EGFR forms a complex with p37 and ANXA2, and is required for M. hyorhinis-induced phosphorylation and membrane recruitment of ANXA2. M. hyorhinis infection is inhibited by siRNA-mediated knockdown of ANXA2 or EGFR, but is enhanced by expression of ectopic ANXA2 or EGFR. Downstream of ANXA2 and EGFR, the NF-?B pathway is activated and mediates M. hyorhinis-driven cell migration. In conclusion, our study unveils the effect of M. hyorhinis infection on gastric cancer survival and uncovers the mechanisms by which M. hyorhinis infects mammalian cells and promotes cancer cell migration. Cancer Res; 74(20); 5782-94. ©2014 AACR.
Related JoVE Video
Hypovolaemia was associated with clustering of major cardiovascular risk factors in general population.
BMC Cardiovasc Disord
PUBLISHED: 08-11-2014
Show Abstract
Hide Abstract
Previous studies indicated that the clustering of major cardiovascular disease (CVD) risk factors is common, and multiple unhealthy lifestyles are responsible for the clustering of CVD risk factors. However, little is known about the direct association between the volume load and the clustering of CVD risk factors in general population.
Related JoVE Video
Association of clustering of major cardiovascular risk factors with chronic kidney disease in the adult population.
Clin. Nephrol.
PUBLISHED: 07-15-2014
Show Abstract
Hide Abstract
The prevalence of chronic kidney disease (CKD) is high in China, as is the clustering of major cardiovascular (CVD) risk factors. We aimed to explore the association of clustering of CVD risk factors with CKD in the adult population.
Related JoVE Video
Applications of graphene in mass spectrometry.
J Nanosci Nanotechnol
PUBLISHED: 04-25-2014
Show Abstract
Hide Abstract
This paper reviews the up-to-date research about the applications of graphene and its related materials in the field of mass spectrometry (MS). Due to its large surface area, delocalized pi-electrons, thermal conductivity, stability and rich interaction chemistry, graphene has been widely used in MS-based analytical chemistry. Graphene-based materials were applied as very effective matrixes or surfaces for many kinds of organic molecules in laser desorption/ionization (LDI) MS analysis. Many advantages of this novel matrix have been proved, which included: low interference ions from matrix itself, good reproducibility, high salt tolerance and so on. The unique properties of graphene also make it a superior sorbent used in solid-phase extraction (SPE). Further development of online SPE methods based on graphene coupling directly with LDI-MS, GC-MS and LC-MS greatly simplifies the MS-based analytical procedure for complex samples and makes the corresponding high-throughput and automatic analysis performable. Their applications as a platform in proteolysis for the rapid identification of proteins have been also developed. In addition, graphene was found to be a unique precursor for the generation of large-sized carbon cluster anions in the gas phase. Finally, the possible challenges and future perspectives in their applications in MS are discussed too.
Related JoVE Video
A solitary wave-based sensor to monitor the setting of fresh concrete.
Sensors (Basel)
PUBLISHED: 04-04-2014
Show Abstract
Hide Abstract
We present a proof-of-principle study about the use of a sensor for the nondestructive monitoring of strength development in hydrating concrete. The nondestructive evaluation technique is based on the propagation of highly nonlinear solitary waves (HNSWs), which are non-dispersive mechanical waves that can form and travel in highly nonlinear systems, such as one-dimensional particle chains. A built-in transducer is adopted to excite and detect the HNSWs. The waves are partially reflected at the transducer/concrete interface and partially transmitted into the concrete. The time-of-flight and the amplitude of the waves reflected at the interface are measured and analyzed with respect to the hydration time, and correlated to the initial and final set times established by the penetration test (ASTM C 403). The results show that certain features of the HNSWs change as the concrete curing progresses indicating that it has the potential of being an efficient, cost-effective tool for monitoring strengths/stiffness development.
Related JoVE Video
Metabolic engineering of Escherichia coli to enhance shikimic acid production from sorbitol.
World J. Microbiol. Biotechnol.
PUBLISHED: 04-03-2014
Show Abstract
Hide Abstract
Shikimic acid (SA) is the key synthetic material of Oseltamivir, which is an effective drug for the prevention and treatment of influenza. In this study, to block the downstream metabolic pathway of SA, the shikimate kinase isoenzyme genes aroK and aroL were deleted by Red recombination. Moreover, the key enzyme genes aroG, aroB, tktA and aroE of SA pathway were co-expressed by constructing the recombinant vector pETDuet-GBAE. As a result, SA production of E. coli BW25113 (?aroL/aroK, DE3)/pETDuet-GBAE reached 1,077.6 mg/l when low amounts of sorbitol (5 g/l) were fed in shake flasks. The yield was 3.7 times that when glucose was used (P < 0.05). The results showed that sorbitol was an optimized carbon source for the high efficient accumulation of SA for the first time, which was applicable to use in the industry for high yields and low consumption.
Related JoVE Video
Discovery of 1-aryloxyethyl piperazine derivatives as Kv1.5 potassium channel inhibitors (part I).
Eur J Med Chem
PUBLISHED: 03-22-2014
Show Abstract
Hide Abstract
Kv1.5 potassium channel is an efficacious and safe therapeutic target for the treatment of atrial fibrillation (AF), the most common arrhythmia that threatens human. Herein, by modifying the hit compound 7k from an in-house database, 48 derivatives were synthesized for the assay of their Kv1.5 inhibitory effects by whole cell patch clamp technique. Six compounds which showed better potency than the positive compound dronedarone were selected for the next evaluation of their drug-like properties. Compound 8 exhibited balanced solubility and permeability. It also showed acceptable pharmacodynamics profile with very low acute toxicity. Taking all these data into account, compound 8 can serve as a promising lead for the development of novel therapeutic agent for the treatment of AF.
Related JoVE Video
The serum from dialysis patients with acute coronary syndrome up-regulates the expression of TLR2 and its downstream effectors in human renal glomerular endothelial cells.
Ren Fail
PUBLISHED: 02-13-2014
Show Abstract
Hide Abstract
This study was to investigate the expression of toll-like receptor 2 and its downstream effectors in endothelial cells in response to the serum from maintenance hemodialysis (MHD) patients with acute coronary syndrome (ACS).
Related JoVE Video
Reinvestigation of the structure of protonated lysine dimer.
J. Am. Soc. Mass Spectrom.
PUBLISHED: 01-14-2014
Show Abstract
Hide Abstract
To better understand inconsistencies between the predicted infrared (IR) spectra of previously suggested isomers of Lys2H(+) reported by Wu et al. (J. Am. Soc. Mass Spectrom. 22:1651-1659, 18) and the experimental IR photon dissociation (IRPD) spectrum obtained by Oh et al. (J. Am. Chem. Soc. 127:4076-4083, 4), the structure of Lys2H(+) was reinvestigated using IRPD spectroscopy in the extended region 2700-3700 cm(-1) and theoretical calculations. The new experimental IRPD spectrum is in good agreement with Oh's spectrum in the corresponding wavelength range. Based on calculations at the MP2/6-311++G(d,p)//B3LYP/6-311++G(d,p) and MP2/6-31?+?G(d,p)//MP2/6-31?+?G(d,p) levels, a new salt-bridged isomer, ZW1, was found to be the most stable isomer; it is more energetically favored than the previously suggested charge-solvated isomer LL-CS01 by 10 or 26 kJ mol(-1). Although the calculated IR spectrum of ZW1 is in good agreement with the experimental one in the range 2700-3700 cm(-1), it is in poor agreement with the previous IRPD spectrum in the range 1000-1900 cm(-1). This investigation shows that the intermolecular interactions inside the dimer are more complex than previously supposed. It is possible that both salt-bridged and charge-solvated isomers of Lys2H(+) are stable in the gas phase, and the isomers generated during ionization are sensitive to the experimental conditions.
Related JoVE Video
Chirality effects on proline-substituted serine octamers revealed by infrared photodissociation spectroscopy.
Phys Chem Chem Phys
PUBLISHED: 12-05-2013
Show Abstract
Hide Abstract
Chiral preferences exist in proline-substituted serine octamers. For ions of [l-Ser6 + Pro2]H(+), the stability preference is [l-Ser6 + l-Pro2]H(+) > [l-Ser6 + d-Pro2]H(+) > [l-Ser6 + l-Pro1 + d-Pro1]H(+). Infrared photodissociation (IRPD) experiments were performed for the observed proline-substituted octamer ions in the range from 2700 to 3750 cm(-1). Chiral differentiation was achieved using the IRPD method, and the progressive changes in IRPD spectra due to the substitution were also reflected.
Related JoVE Video
Line selection and parameter optimization for trace analysis of uranium in glass matrices by laser-induced breakdown spectroscopy (LIBS).
Appl Spectrosc
PUBLISHED: 10-29-2013
Show Abstract
Hide Abstract
Laser-induced breakdown spectroscopy (LIBS) has been evaluated for the determination of uranium in real-world samples such as uraninite. NIST Standard Reference Materials were used to evaluate the spectral interferences on detection of uranium. The study addresses the detection limit of LIBS for several uranium lines and their relationship to non-uranium lines, with emphasis on spectral interferences. The data are discussed in the context of optimizing the choice of emission lines for both qualitative and quantitative analyses from a complex spectrum of uranium in the presence of other elements. Temporally resolved spectral emission intensities, line width, and line shifts were characterized to demonstrate the parameter influence on these measurements. The measured uranium line width demonstrates that LIBS acquired with moderately high spectral resolution (e.g., by a 1.25 m spectrometer with a 2400 grooves/mm grating) can be utilized for isotope shift measurements in air at atmospheric pressure with single to tens of parts per million (ppm) level detection limits, as long as an appropriate transition is chosen for analysis.
Related JoVE Video
Pd-catalyzed Heck-type cascade reactions with N-tosyl hydrazones: an efficient way to alkenes via in situ generated alkylpalladium.
Org. Lett.
PUBLISHED: 09-09-2013
Show Abstract
Hide Abstract
A palladium-catalyzed Heck-type cascade reaction of aryl halides and N-tosyl hydrazones is reported. The neopentylpalladium species, generated from an intramolecular Heck-type insertion reaction of aryl halides, could efficiently react with carbenes to form highly functionalized alkenes. The synthesis of spiro compounds was also explored via a multiple Heck-type insertion reaction with N-tosyl hydrazone.
Related JoVE Video
Carbon nanodots as a matrix for the analysis of low-molecular-weight molecules in both positive- and negative-ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and quantification of glucose and uric acid in real samples.
Anal. Chem.
PUBLISHED: 07-05-2013
Show Abstract
Hide Abstract
Carbon nanodots were applied for the first time as a new matrix for the analysis of low-molecular-weight compounds by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in both positive- and negative-ion modes. A wide range of small molecules including amino acids, peptides, fatty acids, as well as ?-agonists and neutral oligosaccharides were analyzed by MALDI MS with carbon nanodots as the matrix, and the lowest 0.2 fmol limits-of-detection were obtained for octadecanoic acid. Clear sodium and potassium adducts and deprotonated signals were produced in positive- and negative-ion modes. Furthermore, the glucose and uric acid in real samples were quantitatively determined by the internal standard method with the linear range of 0.5-9 mM and 0.1-1.8 mM (R(2) > 0.999), respectively. This work gives new insight into the application of carbon nanodots and provides a general approach for rapid analysis of low-molecular-weight compounds.
Related JoVE Video
Prediction of sweetness by multilinear regression analysis and support vector machine.
J. Food Sci.
PUBLISHED: 05-29-2013
Show Abstract
Hide Abstract
The sweetness of a compound is of large interest for the food additive industry. In this work, 2 quantitative models were built to predict the logSw (the logarithm of sweetness) of 320 unique compounds with a molecular weight from 132 to 1287 and a sweetness from 22 to 22500000. The whole dataset was randomly split into a training set including 214 compounds and a test set including 106 compounds, represented by 12 selected molecular descriptors. Then, logSw was predicted using a multilinear regression (MLR) analysis and a support vector machine (SVM). For the test set, the correlation coefficients of 0.87 and 0.88 were obtained by MLR and SVM, respectively. The descriptors found in our quantitative structure-activity relationship models are prone to a structural interpretation and support the AH/B System model proposed by Shallenberger and Acree.
Related JoVE Video
Laser ablation in analytical chemistry.
Anal. Chem.
PUBLISHED: 05-21-2013
Show Abstract
Hide Abstract
In 2002, we wrote an Analytical Chemistry feature article describing the Physics of Laser Ablation in Microchemical Analysis. In line with the theme of the 2002 article, this manuscript discusses current issues in fundamental research, applications based on detecting photons at the ablation site (LIBS and LAMIS) and by collecting particles for excitation in a secondary source (ICP), and directions for the technology.
Related JoVE Video
Carcinogenicity prediction of noncongeneric chemicals by a support vector machine.
Chem. Res. Toxicol.
PUBLISHED: 04-11-2013
Show Abstract
Hide Abstract
The ability to identify carcinogenic compounds is of fundamental importance to the safe application of chemicals. In this study, we generated an array of in silico models allowing the classification of compounds into carcinogenic and noncarcinogenic agents based on a data set of 852 noncongeneric chemicals collected from the Carcinogenic Potency Database (CPDBAS). Twenty-four molecular descriptors were selected by Pearson correlation, F-score, and stepwise regression analysis. These descriptors cover a range of physicochemical properties, including electrophilicity, geometry, molecular weight, size, and solubility. The descriptor mutagenic showed the highest correlation coefficient with carcinogenicity. On the basis of these descriptors, a support vector machine-based (SVM) classification model was developed and fine-tuned by a 10-fold cross-validation approach. Both the SVM model (Model A1) and the best model from the 10-fold cross-validation (Model B3) runs gave good results on the test set with prediction accuracy over 80%, sensitivity over 76%, and specificity over 82%. In addition, extended connectivity fingerprints (ECFPs) and the Toxtree software were used to analyze the functional groups and substructures linked to carcinogenicity. It was found that the results of both methods are in good agreement.
Related JoVE Video
Carbon isotope separation and molecular formation in laser-induced plasmas by laser ablation molecular isotopic spectrometry.
Anal. Chem.
PUBLISHED: 02-15-2013
Show Abstract
Hide Abstract
Laser ablation molecular isotopic spectrometry (LAMIS) recently was reported for rapid isotopic analysis by measuring molecular emission from laser-induced plasmas at atmospheric pressure. This research utilized the LAMIS approach to study C2 molecular formation from laser ablation of carbon isotopic samples in a neon gas environment at 0.1 MPa. The isotopic shift for the Swan system of the C2 ?? = 1 band was chosen for carbon isotope analysis. Temporal and spatial resolved measurements of (12)C2, (12)C(13)C, and (13)C2 show that C2 forms from recombination reactions in the plasma. A theoretical simulation was used to determine the temperature from the molecular bands and to extract the isotopic ratio of (12)C/(13)C derived from (12)C2, (12)C(13)C, and (13)C2. Our data show that the ratio of (12)C/(13)C varies with time after the laser pulse and with distance above the sample. (12)C/(13)C deviates from the nominal ratio (2:1) at early times and closest to the sample surface. These measurements provide understanding of the chemical processes in the laser plasma and analytical improvement using LAMIS.
Related JoVE Video
A comparative study on three different transducers for the measurement of nonlinear solitary waves.
Sensors (Basel)
PUBLISHED: 01-11-2013
Show Abstract
Hide Abstract
In the last decade there has been an increasing interest in the use of highly- and weakly- nonlinear solitary waves in engineering and physics. Nonlinear solitary waves can form and travel in nonlinear systems such as one-dimensional chains of particles, where they are conventionally generated by the mechanical impact of a striker and are measured either by using thin transducers embedded in between two half-particles or by a force sensor placed at the chains base. These waves have a constant spatial wavelength and their speed, amplitude, and duration can be tuned by modifying the particles material or size, or the velocity of the striker. In this paper we propose two alternative sensing configurations for the measurements of solitary waves propagating in a chain of spherical particles. One configuration uses piezo rods placed in the chain while the other exploits the magnetostrictive property of ferromagnetic materials. The accuracy of these two sensing systems on the measurement of the solitary waves characteristics is assessed by comparing experimental data to the numerical prediction of a discrete particle model and to the experimental measurements obtained by means of a conventional transducer. The results show very good agreement and the advantages and limitations of the new sensors are discussed.
Related JoVE Video
Association between family members of dialysis patients and chronic kidney disease: a multicenter study in China.
BMC Nephrol
PUBLISHED: 01-07-2013
Show Abstract
Hide Abstract
Family members of patients with end stage renal disease were reported to have an increased prevalence of chronic kidney disease (CKD). However, studies differentiated genetic and non-genetic family members are limited. We sought to investigate the prevalence of CKD among fist-degree relatives and spouses of dialysis patients in China.
Related JoVE Video
Serine-phosphoric acid cluster ions studied by electrospray ionization and tandem mass spectrometry.
J Mass Spectrom
PUBLISHED: 06-02-2011
Show Abstract
Hide Abstract
More than 310 kinds of cluster ions of S(m) P(n) H(k) (k+) are observed in a single ESI mass spectrum of a mixed solution of serine and phosphoric acid. Some typical cluster ions are selected, activated by collision in a FT ICR cell, and the dissociation pathways were deduced in detail. For large singly protonated ions, the collisions cause the ejection of subunits of serine or phosphoric acid subsequently producing the ions of S(2) P(4) H(1) (1+) , which can be further dissociated by the loss of phosphoric acid molecules in turn and form the protonated serine dimer and monomer. However, for the doubly protonated ions, the dissociation pathways change from the loss of a protonated serine dimer for the ions of S(7) P(9) H(2) (2+) to the neutral loss of H(3) PO(4) for the ions of S(7) P(12) H(2) (2+) or the neutral loss of serine or H(3) PO(4) for the larger clusters, indicating the effect of cluster sizes on the process of dissociation. The structure of S(2) P(4) H(1) (1+) is suggested based on B3LYP/6-31G(d,p) calculations. The diversity and structural orderliness of the hetero-cluster ions are mainly attributed to the network of hydrogen bonds inside the cluster ions and the extraordinary amphotericity of the components.
Related JoVE Video
Laser-based excitation of nonlinear solitary waves in a chain of particles.
Phys Rev E Stat Nonlin Soft Matter Phys
PUBLISHED: 05-21-2011
Show Abstract
Hide Abstract
Highly nonlinear solitary waves (HNSWs) are stress waves that can form and travel in highly nonlinear systems. They are characterized by a constant spatial wavelength and by a tunable propagation speed, dependent on the wave amplitude. Conventionally, HNSWs are generated in one-dimensional chains of spherical particles by means of a mechanical impact. In this paper, we demonstrate that short-duration laser pulses can be used to generate HNSWs, and we characterize their propagating properties in terms of shape, speed, and duration. We compare the waves characteristics with theoretical predictions, finding excellent agreement. In addition a simplified formulation is given to estimate the dynamic contact force generated by laser pulses onto the chain.
Related JoVE Video
Large carbon cluster anions generated by laser ablation of graphene.
J. Am. Soc. Mass Spectrom.
PUBLISHED: 05-05-2011
Show Abstract
Hide Abstract
The formation of large even-numbered carbon cluster anions, C(n)?, with n up to 500 were observed in the mass spectra generated by laser ablation of graphene and graphene oxide, and the signal intensity of the latter is much weaker than that of the former. The cluster distributions generated from graphene can be readily altered by changing the laser energy and the accumulation period in the FT-ICR cell. By choosing suitable experimental conditions, weak signals of odd-numbered anions from C???? to C????, doubly charged anions from C??²? to C???²? and triply charged cluster anions from C??³? to C???³? can be observed. Tandem MS was applied to some selected cluster anions. Though no fragment anions larger than C??? can be observed by the process of collisional activation with N(2) gas for most cluster ions, several cluster anions can lose units of C(2), C(4), C(6) or C(8) in their collision process. The differences in their dissociation kinetics and structures require further calculations and experimental studies.
Related JoVE Video
Mitochondrial ceramide-rich macrodomains functionalize Bax upon irradiation.
PLoS ONE
PUBLISHED: 04-15-2011
Show Abstract
Hide Abstract
Evidence indicates that Bax functions as a "lipidic" pore to regulate mitochondrial outer membrane permeabilization (MOMP), the apoptosis commitment step, through unknown membrane elements. Here we show mitochondrial ceramide elevation facilitates MOMP-mediated cytochrome c release in HeLa cells by generating a previously-unrecognized mitochondrial ceramide-rich macrodomain (MCRM), which we visualize and isolate, into which Bax integrates.
Related JoVE Video
Actuators for the generation of highly nonlinear solitary waves.
Rev Sci Instrum
PUBLISHED: 04-05-2011
Show Abstract
Hide Abstract
In this paper we present the design of two actuators for the generation of highly nonlinear solitary waves (HNSWs), which are mechanical waves that can form and travel in highly nonlinear systems. These waves are characterized by a constant spatial wavelength and by a tunable propagation speed, dependent on the wave amplitude. To date, the simplest and widely adopted method to generate HNSWs is by impacting a striker onto a chain of beads of equal size and mass. This operation is conducted manually and it might be impracticable if repetition rates higher than 0.1 Hz are necessary. It is known that the HNSWs properties, such as amplitude, duration, and speed can be modified by changing the size or the material of the particles, the velocity of the striker, and/or the precompression on the chain. To address the limitations associated with the manual generation of HNSWs we designed, built, and tested two actuators. The first actuator consists of a chain of particles wrapped by an electromagnet that induces static precompression on the chain. This design allows for the generation of solitary waves with controlled properties. The second actuator consists of a chain surmounted by an electromagnet that lifts and releases a striker. This actuator permits the remote and noncontact generation of solitary waves. The performance of both actuators is evaluated by comparing the experimental HNSWs to theoretical predictions, based on the long wavelength approximation.
Related JoVE Video
N-glycan-defective breast cancer cells induce a phenotypic switch in polarization of bone marrow-derived macrophages.
Clin Invest Med
PUBLISHED: 04-01-2011
Show Abstract
Hide Abstract
To investigate the effect of N-glycan-defective mammary adenocarcinoma cells on the polarization of macrophages.
Related JoVE Video
Functional analysis of luxS in Streptococcus suis reveals a key role in biofilm formation and virulence.
Vet. Microbiol.
PUBLISHED: 01-06-2011
Show Abstract
Hide Abstract
Streptococcus suis (SS) is an important pathogen of pigs, responsible for diverse diseases in swine and human. LuxS has been reported to play critical roles in both regulating various behaviors and interspecies quorum sensing in a large spectrum of bacteria. In this study, the luxS deletion mutant of SS was constructed using homologous recombination and its biofilm formation, hemolytic activity, cell adherence, virulence and expression of virulence factors were evaluated. Compared to the parental strain, the biofilm formation and hemolytic activity were significantly decreased in the luxS mutant. The addition of synthetic autoinducer 2 could complement the deficiencies of biofilm production in the mutant strain. Furthermore, its adherence to the HEp-2 cell line was dramatically decreased by 51% compared to the parental strain. Expressions of the known virulence genes gdh, cps, mrp, gapdh, sly, fbps and ef in the mutant strain were decreased by 0.66, 0.61, 0.45, 0.48, 0.29, 0.57 and 0.38, respectively, as quantified by real-time PCR. In a zebrafish infection model, the 50% lethal dose of the mutant strain was increased up to 10-fold. The findings demonstrated that the luxS gene deletion resulted in a significant decrease of bacterial biofilm formation, cell adhesion, hemolytic activity and transcription levels of many virulence genes in SS, and these factors may be associated with the attenuation of virulence in zebrafish. These results suggest that luxS may be involved in the interruption of bacterial communication and biofilm formation that contribute to the virulence of the bacterium.
Related JoVE Video
Interleukin-15 receptor-directed immunotoxins atteunuate disease severity in rat adjuvant arthritis.
Mol. Immunol.
PUBLISHED: 01-19-2010
Show Abstract
Hide Abstract
We previously constructed two Pseudomonas exotoxin (PE)-based immunotoxins, IL15-PEDelta293 (IT1) and IL15M-PEDelta293 (IT2), for eliminating interleukin-15 receptor (IL-15R)-overexpressing cells. These two immunotoxins were generated by fusing either wild-type human IL-15 or an antagonist mutant IL-15 (IL-15M) to a modified form of PE. In this study the anti-arthritic effect of IT1 and IT2 was investigated using the rat model of adjuvant arthritis (AA). We found that both IT1 and IT2 could specifically target IL-15R-positive cells and induce apoptosis. After AA induction, treatment with either IT1 or IT2 resulted in profound improvement of the disease, with reductions in levels of synovial mononuclear leukocytes and certain inflammatory factors. Clinical and histological comparisons, together with the analyses of mRNA expression and the signal transducer and activator of transcription-3 (STAT-3) phosphorylation, revealed that the two immunotoxins decreased joint inflammation in AA rats to a similar extent. These data suggest that eliminating IL-15R-bearing cells via immunotoxins may be a promising approach for RA treatment. In addition, wild-type IL-15-based immunotoxins can be as effective as antagonist mutant IL-15-based immunotoxins in preventing joint inflammation associated with rheumatoid arthritis.
Related JoVE Video
Vascular endothelial growth factor 1498C/T, 936C/T polymorphisms associated with increased risk of colorectal adenoma: a Chinese case-control study.
Mol. Biol. Rep.
PUBLISHED: 01-17-2010
Show Abstract
Hide Abstract
Single nucleotide polymorphisms in vascular endothelial growth factor gene VEGF, 1498C/T and 936 C/T are associated with colorectal cancer. We sought to determine whether such genetic variability in VEGF contributes to susceptibility of colorectal adenoma (CRA), a presumably precancerous state of colorectal cancer. In this research, two aforementioned polymorphisms were investigated for CRA susceptibility in a Chinese case-control study. The epidemiological risk factors were collected through questionnaire. The plasma VEGF levels were measured via enzyme-linked immunosorbent assay (ELISA). The Taqman-Probe assay was used to determine genotypes in 224 CRA patients and 200 CRA-free controls. The clinicopathological data of each sample were collected for further correlation analysis. According to data analysis males, cigarette smokers, patients who carry metabolic syndrome or familial antecedent of adenomas were significantly associated with CRA risk. Plasma VEGF levels of CRA patients were higher than those of controls (P = 0.003). This difference is independent of genotypes. The carriers with 936CT and CT+TT had higher risk of CRA in comparison with controls (CT vs. CC, OR 2.00, 95% CI 1.23-3.25, P = 0.006; CT+TT vs. CC, OR 2.04, 95% CI 1.28-3.26, P = 0.003). 936-T allele was associated with increased risk of CRA (OR 1.91, 95% CI 1.25-2.91, P = 0.003). Both CRA and control show no difference in the genotype of 1498C/T and the allele frequency of C-/T-. CRA patients with haplotype 1498T+936T presented significantly higher risk than those with wild-type 1498T+936C. Moreover, patients carrying 936CT+TT and 936-T allele demonstrated a tendency for villous adenoma. CRA patients have elevated plasma VEGF levels. The VEGF 936C/T polymorphism and 1498T+936T haplotype were found to be associated with increased CRA susceptibility.
Related JoVE Video
Kinase suppressor of Ras transphosphorylates c-Raf-1.
Biochem. Biophys. Res. Commun.
PUBLISHED: 09-08-2009
Show Abstract
Hide Abstract
Whether kinase suppressor of Ras1 (KSR1) is an active kinase that phosphorylates c-Raf-1 or a scaffold that coordinates signaling along the Ras/ERK1 signaling module is actively debated. In this study, we generated a monoclonal antibody against a c-Raf-1 peptide containing phosphorylated Thr(269), the putative target for KSR1 kinase activity. We show that this antibody detects Thr(269)-phosphorylated c-Raf-1 in A431 cells upon epidermal growth factor (EGF) stimulation, preceding MEK1 activation. Furthermore, this antibody detects in vitro phosphorylation of FLAG-c-Raf-1 and kinase-dead FLAG-c-Raf-1(K375M) by immunopurified KSR1, but fails to detect phosphorylation of FLAG-c-Raf-1(K375M/T269V), engineered with a Thr(269) to valine substitution. To provide unequivocal evidence that KSR1 is a legitimate kinase, we purified KSR1 to homogeneity, confirmed by mass spectrometry, renatured it in-gel, and demonstrated that it phosphorylates BSA-conjugated c-Raf-1 peptide at Thr(269). These studies add to emerging data validating KSR1 as a kinase that phosphorylates c-Raf-1.
Related JoVE Video
Rapid MALDI mass spectrometric analysis with prestructured membrane filters and functionalized diamond nanocrystals.
Anal. Chim. Acta
PUBLISHED: 09-02-2009
Show Abstract
Hide Abstract
A solid-phase extraction method based on prestructured membrane filters and functionalized diamond nanocrystals is developed to facilitate analysis of biopolymers with MALDI mass spectrometry. The method integrates isolation, purification, and concentration in one step and is adaptable to high-throughput peptide fingerprint mapping of intact proteins and enzymatic digests. The feasibility of the method was demonstrated using diamond nanocrystals surface-derivatized with carboxylate groups and subsequently coated with poly-lysines. These nanocrystals, which are capable of extracting proteins from highly dilute solutions contaminated with salts and detergents, can be easily isolated by filtration through paraffin-coated PVDF membrane filters pre-patterned with channels for direct MALDI mass spectrometric analysis. This method is facile, easy to operate, and the analysis of each sample solution (with a volume up to 500 microL) can be completed in 10 min. With this method, it is possible to achieve high-throughput analysis of proteins by preparing an array of filtration spots on paraffin-coated PVDF membrane that matches the MALDI sample target of the commercial mass spectrometer.
Related JoVE Video
Optical far- and near-field femtosecond laser ablation of Si for nanoscale chemical analysis.
Anal Bioanal Chem
PUBLISHED: 05-31-2009
Show Abstract
Hide Abstract
Extending spatial resolution in laser-based chemical analysis to the nanoscale becomes increasingly important as nanoscience and nanotechnology develop. Implementation of femtosecond laser pulses arises as a basic strategy for increasing resolution since it is associated with spatially localized material damage. In this work we study femtosecond laser far- and near-field processing of silicon (Si) at two distinct wavelengths (400 and 800 nm), for nanoscale chemical analysis. By tightly focusing femtosecond laser beams in the far-field, we were able to produce sub-micrometer craters. In order to further reduce the crater size, similar experiments were performed in the near-field through sub-wavelength apertures, resulting in the formation of sub-30-nm craters. Laser-induced breakdown spectroscopy (LIBS) was used for chemical analysis with a goal to identify the minimum crater size from which spectral emission could be measured. Emission from sub-micrometer craters (full width at half maximum) was possible, which are among the smallest ever reported for femtosecond LIBS.
Related JoVE Video
A ceramide-binding C1 domain mediates kinase suppressor of ras membrane translocation.
Cell. Physiol. Biochem.
PUBLISHED: 05-23-2009
Show Abstract
Hide Abstract
Genetic and biochemical data support Kinase Suppressor of Ras 1 (KSR1) as a positive regulator of the Ras-Raf-MAPK pathway, functioning as a kinase and/or scaffold to regulate c-Raf-1 activation. Membrane translocation mediated by the KSR1 CA3 domain, which is homologous to the atypical PKC C1 lipid-binding domain, is a critical step of KSR1-mediated c-Raf-1 activation. In this study, we used an ELISA to characterize the KSR1 CA3 domain as a lipid-binding moiety. Purified GST-KSR1-CA3 protein effectively binds ceramide but not other lipids including 1,2-diacylglyceol, dihydroceramide, ganglioside GM1, sphingomyelin and phosphatidylcholine. Upon epidermal growth factor stimulation of COS-7 cells, KSR1 translocates into and is activated within glycosphingolipid-enriched plasma membrane platforms. Pharmacologic inhibition of ceramide generation attenuates KSR1 translocation and KSR1 kinase activation in COS-7 cells. Disruption of two cysteines, which are indispensable for maintaining ternary structure of all C1 domains and their lipid binding capability, mitigates ceramide-binding capacity of purified GST-KSR1-CA3 protein, and inhibits full length KSR1 membrane translocation and kinase activation. These studies provide evidence for a mechanism by which the second messenger ceramide can target proteins to subcellular compartments in the process of transmembrane signal transduction.
Related JoVE Video
Detection of deletion mutations in DNA using water-soluble cationic fluorescent thiophene copolymer.
Talanta
PUBLISHED: 03-05-2009
Show Abstract
Hide Abstract
In this contribution, we designed a fluorescent thiophene copolymer to detect insertion/deletion mutation in DNA by doping aldehyde group in the main chain. The fluorescence of the copolymer could be dramatically quenched on the addition of single-stranded DNA (ssDNA) via strong electrostatic interactions and electronic/energy transfer. Although the complementary ssDNA made the fluorescence recover, the hydrogen bonds and chemical coupling also played a significant role between the unpaired bases and aldehyde group, which could differentiate the subtle differences in such mutant DNA. The influence of buffer pH, concentration of NaCl, heating time and the temperature was systemically investigated and the proposed method was then successfully applied to detect real sample. With the respect to the linearity, limit of detection precision, specificity, this procedure could provide sensitive methodologies for the rapid detection and identification of nucleic acids.
Related JoVE Video
Progress in studies on the DEK protein and its involvement in cellular apoptosis.
Sci. China, C, Life Sci.
PUBLISHED: 02-28-2009
Show Abstract
Hide Abstract
DEK protein is an ubiquitous phosphorylated nuclear protein. Specific binding of DEK to DNA could change the topology of DNA and then affect the gene activity of the underlying DNA sequences. It is speculated that there might be some potential relationship between the stress reaction of cells and DEK proteins. The phosphorylation status of DEK protein is altered during death-receptor-mediated cell apoptosis. Both phosphorylation and poly(ADP-ribosyl)ation could promote the release of DEK from apoptotic nuclei to extracellular environment, and in this case DEK becomes a potential autoantigen of some autoimmune diseases. The available evidence powerfully suggests that DEK protein is closely relevant to apoptosis. The overexpression of DEK protein has dual function in cell apoptosis, in terms of inhibiting or triggering cell apoptosis.
Related JoVE Video
Evaluation of the Chronic Kidney Disease Epidemiology Collaboration equation for estimating glomerular filtration rate in the Chinese population.
Nephrol. Dial. Transplant.
Show Abstract
Hide Abstract
Previous studies have indicated that the performance of glomerular filtration rate (GFR) estimation equations vary according to the races of the target population. The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation has not been validated in the Chinese population including patients with chronic kidney disease (CKD) and healthy controls.
Related JoVE Video
Effects of urate-lowering therapy in hyperuricemia on slowing the progression of renal function: a meta-analysis.
J Ren Nutr
Show Abstract
Hide Abstract
Uric acid (UA) is generally regarded as an independent risk factor for poor prognosis of patients with kidney disease. However, urate-lowering therapy (ULT) in asymptomatic hyperuricemia is conservative. Whether the beneficial effect on renal function can be achieved by lowering UA remains uncertain. A compound search for randomized controlled trials was conducted in databases consisting of MEDLINE, EMBASE, the Cochrane Library, the Chinese Biomedical Literature Database, and Chinese Science and Technology periodical databases. Two investigators independently screened these studies, assessed the included trials, and extracted data. Eleven articles with a total number of 753 participants met the criteria and were included in our meta-analysis. The results showed that ULT was associated with a decrease in serum creatinine and an increase in eGFR. Our study further confirms that ULT may have beneficial effects on slowing the progression of renal function.
Related JoVE Video
Analysis and design of a speed and position system for maglev vehicles.
Sensors (Basel)
Show Abstract
Hide Abstract
This paper mainly researches one method of speed and location detection for maglev vehicles. As the maglev train doesnt have any physical contact with the rails, it has to use non-contact measuring methods. The technology based on the inductive loop-cable could fulfill the requirement by using an on-board antenna which could detect the alternating magnetic field produced by the loop-cable on rails. This paper introduces the structure of a speed and position system, and analyses the electromagnetic field produced by the loop-cable. The equivalent model of the loop-cable is given and the most suitable component of the magnetic flux density is selected. Then the paper also compares the alternating current (AC) resistance and the quality factor between two kinds of coils which the antenna is composed of. The effect of the rails to the signal receiving is also researched and then the structure of the coils is improved. Finally, considering the common-mode interference, 8-word coils are designed and analyzed.
Related JoVE Video
Mineral and bone disorder in Chinese dialysis patients: a multicenter study.
BMC Nephrol
Show Abstract
Hide Abstract
Mineral and bone disorder (MBD) in patients with chronic kidney disease is associated with increased morbidity and mortality. Studies regarding the status of MBD treatment in developing countries, especially in Chinese dialysis patients are extremely limited.
Related JoVE Video
Inhibition of the expression of TGF-?1 and CTGF in human mesangial cells by exendin-4, a glucagon-like peptide-1 receptor agonist.
Cell. Physiol. Biochem.
Show Abstract
Hide Abstract
Despite the presence of glucagon-like peptide-1 receptor (GLP-1R) in kidney tissues, its direct effect on diabetic nephropathy remains unclear. The transforming growth factor-?(1) (TGF-?(1)) and the connective tissue growth factor (CTGF) both induce extracellular matrix accumulation and persistent fibrosis in the glomerular mesangium of patients with diabetic nephropathy.
Related JoVE Video
Classification of Aurora kinase inhibitors by self-organizing map (SOM) and support vector machine (SVM).
Eur J Med Chem
Show Abstract
Hide Abstract
The Aurora kinase family (consisting of Aurora-A, -B and -C) is an important group of enzymes that controls several aspects of cell division in mammalian cells. In this study, 512 compounds of Aurora-A and -B inhibitors were collected. They were classified into three classes: dual Aurora-A and Aurora-B inhibitors, selective inhibitors of Aurora-A and selective inhibitors of Aurora-B by Self-Organizing Map (SOM) and Support Vector Machine (SVM). The prediction accuracies of the models (based on the training/test set splitting using SOM method) for the test set were 92.2% for SOM1 and 93.8% for SVM1, respectively. In addition, the extended connectivity fingerprints (ECFP_4) for all the molecules were calculated and structure-activity relationship of Aurora kinase inhibitors was summarized, which may be helpful to find the important structural features of inhibitors relating to the selectivity to Aurora kinases.
Related JoVE Video
Oral activated charcoal suppresses hyperphosphataemia in haemodialysis patients.
Nephrology (Carlton)
Show Abstract
Hide Abstract
Hyperphosphataemia is almost inevitable in end stage renal disease (ESRD) patients and is associated with increased morbidity and mortality. In this study we examined whether oral activated charcoal (oAC) reduces serum phosphate level in haemodialysis patients.
Related JoVE Video
Difference in formation of carbon cluster cations by laser ablation of graphene and graphene oxide.
J Mass Spectrom
Show Abstract
Hide Abstract
The distributions of positive carbon cluster ions produced by laser ablation of graphene (G) and graphene oxide (GO) are found to be quite different. Under a typical experimental condition, narrow distributions of even-numbered clusters from C60+ to C162+ were observed for G, and broad distributions including even-numbered clusters from C100+ to C400+ and odd-numbered clusters from C189+ to C395+ were observed for GO. The threshold of laser energy for G is lower than that of GO. Further results of collision-activated dissociation mass spectrometry indicate that the cluster ions generated from G are structurally similar but are different with those generated from GO or nanodiamonds. It is proposed that the experimentally observed difference can be attributed to the different mechanisms behind the process. A top-down mechanism including both direct transformation of G to fullerene and fragmentation of large-sized fullerenes is suggested for the generation of carbon cluster cations in the process of laser ablation of G. For GO, the experimental results are close to those of nanodiamonds and other materials reported previously and can be explained by the generally accepted bottom-up mechanism.
Related JoVE Video
Association between microalbuminuria and subclinical atherosclerosis evaluated by carotid artery intima-media in elderly patients with normal renal function.
BMC Nephrol
Show Abstract
Hide Abstract
Moderate to severe renal insufficiency and albuminuria have been shown to be independent risk factors for atherosclerosis. However, little is known about the direct association between subclinical atherosclerosis evaluated by carotid artery intima-media thickness (IMT) and microalbuminuria in elderly patients with normal renal function.
Related JoVE Video
Effects of alkali metal ion cationization on fragmentation pathways of triazole-epothilone.
J. Am. Soc. Mass Spectrom.
Show Abstract
Hide Abstract
The collisionally activated dissociation mass spectra of the protonated and alkali metal cationized ions of a triazole-epothilone analogue were studied in a Fourier transform ion cyclotron resonance mass spectrometer. The fragmentation pathway of the protonated ion was characterized by the loss of the unit of C(3)H(4)O(3). However, another fragmentation pathway with the loss of C(3)H(2)O(2) was identified for the complex ions with Na(+), K(+), Rb(+), and Cs(+). The branching ratio of the second pathway increases with the increment of the size of alkali metal ions. Theoretical calculations based on density functional theory (DFT) method show the difference in the binding position of the proton and the metal ions. With the increase of the radii of the metal ions, progressive changes in the macrocycle of the compound are induced, which cause the corresponding change in their fragmentation pathways. It has also been found that the interaction energy between the compound and the metal ion decreases with increase in the size of the latter. This is consistent with the experimental results, which show that cesiated complexes readily eject Cs(+) when subject to collisions.
Related JoVE Video
Anti-ceramide antibody prevents the radiation gastrointestinal syndrome in mice.
J. Clin. Invest.
Show Abstract
Hide Abstract
Radiation gastrointestinal (GI) syndrome is a major lethal toxicity that may occur after a radiation/nuclear incident. Currently, there are no prophylactic countermeasures against radiation GI syndrome lethality for first responders, military personnel, or remediation workers entering a contaminated area. The pathophysiology of this syndrome requires depletion of stem cell clonogens (SCCs) within the crypts of Lieberkühn, which are a subset of cells necessary for postinjury regeneration of gut epithelium. Recent evidence indicates that SCC depletion is not exclusively a result of DNA damage but is critically coupled to ceramide-induced endothelial cell apoptosis within the mucosal microvascular network. Here we show that ceramide generated on the surface of endothelium coalesces to form ceramide-rich platforms that transmit an apoptotic signal. Moreover, we report the generation of 2A2, an anti-ceramide monoclonal antibody that binds to ceramide to prevent platform formation on the surface of irradiated endothelial cells of the murine GI tract. Consequently, we found that 2A2 protected against endothelial apoptosis in the small intestinal lamina propria and facilitated recovery of crypt SCCs, preventing the death of mice from radiation GI syndrome after high radiation doses. As such, we suggest that 2A2 represents a prototype of a new class of anti-ceramide therapeutics and an effective countermeasure against radiation GI syndrome mortality.
Related JoVE Video
Classification of Aurora B Kinase Inhibitors Using Computational Models.
Comb. Chem. High Throughput Screen.
Show Abstract
Hide Abstract
Using Self-Organizing Map (SOM) and Support Vector Machine (SVM), four classification models were built to predict whether a compound is an active or weakly active inhibitor of Aurora B kinase. A dataset of 679 Aurora B kinase inhibitors was collected, and randomly split into a training set (278 active and 204 weakly active inhibitors) and a test set (109 active and 88 weakly active inhibitors). Based on 19 selected ADRIANA.Code descriptors and 135 MACCS fingerprints, all the four models showed a good prediction accuracy of over 87% on the test set. It benefited from the advantages of two different types of molecular descriptors in encoding structure information of compounds and characterizing the diversity of different inhibitors. Some molecular properties, such as hydrogen-bonding interactions and atom charge related descriptors were found to be important to the bioactivity of Aurora B kinase inhibitors.
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.