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Find video protocols related to scientific articles indexed in Pubmed.
Development of an in vitro model of acquired resistance to toceranib phosphate (Palladia®) in canine mast cell tumor.
BMC Vet. Res.
PUBLISHED: 01-13-2014
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Mast cell tumors (MCTs) are the most common skin tumors in dogs and exhibit variable biologic behavior. Mutations in the c-kit proto-oncogene are associated with the tumorigenesis of MCTs, resulting in growth factor-independent and constitutive phosphorylation of the KIT receptor tyrosine kinase (RTK). Toceranib (TOC) phosphate (Palladia®) is a KIT RTK inhibitor that has biological activity against MCTs. Despite these benefits, patients ultimately develop resistance to TOC. Therefore, there is a need to identify distinguishing clinical and molecular features of resistance in this population.
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Chemerin connects fat to arterial contraction.
Arterioscler. Thromb. Vasc. Biol.
PUBLISHED: 04-04-2013
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Obesity and hypertension are comorbid in epidemic proportion, yet their biological connection is largely a mystery. The peptide chemerin is a candidate for connecting fat deposits around the blood vessel (perivascular adipose tissue) to arterial contraction. We presently tested the hypothesis that chemerin is expressed in perivascular adipose tissue and is vasoactive, supporting the existence of a chemerin axis in the vasculature.
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Estradiol modulates neurotransmitter concentrations in the developing zebra finch song system.
Brain Res.
PUBLISHED: 03-14-2013
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The neural song system in zebra finches is highly sexually dimorphic; only males sing and the brain regions controlling song are far larger in males than females. Estradiol (E2) administered during development can partially masculinize both structure and function. However, additional mechanisms, including those through which E2 may act, remain unclear. Male and female zebra finches were treated with E2 or control vehicle from post-hatching days 3 through 25, at which time norepinephrine (NE), dopamine (DA) and serotonin (5-HT) were measured in individual nuclei of the song system. Main effects of sex were not detected. However, E2 increased NE in the robust nucleus of the arcopallium (RA). In HVC (proper name), the hormone decreased 5-HT across the two sexes and increased DA in females only. These effects suggest that, while baseline levels of these neurotransmitters may not contribute to sexually dimorphic development of the song system, they could play specific roles in functions common to both sexes and/or in modification of the song system by exogenous E2.
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Long-term inhibition of xanthine oxidase by febuxostat does not decrease blood pressure in deoxycorticosterone acetate (DOCA)-salt hypertensive rats.
PLoS ONE
PUBLISHED: 01-08-2013
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Xanthine oxidase and its products, uric acid and ROS, have been implicated in the pathogenesis of cardiovascular disease, such as hypertension. We have previously reported that allopurinol inhibition of XO does not alter the progression of deoxycorticosterone acetate (DOCA)-salt hypertension in rats. However other researchers have observed a reduction in blood pressure after allopurinol treatment in the same model. To resolve this controversy, in this study we used the newer and more effective XO inhibitor febuxostat, and hypothesized that a more complete XO blockade might impair hypertension development and its end-organ consequences. We used DOCA-salt hypertensive rats and administered vehicle (salt water) or febuxostat (orally, 5 mg/kg/day in salt water) in a short-term "reversal" experiment (2 weeks of treatment 3 weeks after DOCA-salt beginning) and a long-term "prevention" experiment (treatment throughout 4 weeks of DOCA-salt). We confirmed XO inhibition by febuxostat by measuring circulating and tissue levels of XO metabolites. We found an overall increase in hypoxanthine (XO substrate) and decrease in uric acid (XO product) levels following febuxostat treatment. However, despite a trend for reduced blood pressure in the last week of long-term febuxostat treatment, no statistically significant difference in hemodynamic parameters was observed in either study. Additionally, no change was observed in relative heart and kidney weight. Aortic media/lumen ratio was minimally improved by long-term febuxostat treatment. Additionally, febuxostat incubation in vitro did not modify contraction of aorta or vena cava to norepinephrine, angiotensin II or endothelin-1. We conclude that XO inhibition is insufficient to attenuate hypertension in the rat DOCA-salt model, although beneficial vascular effects are possible.
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Indoleamine 2,3-diooxygenase in periaortic fat: mechanisms of inhibition of contraction.
Am. J. Physiol. Heart Circ. Physiol.
PUBLISHED: 08-12-2011
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Indoleamine 2,3-dioxygenase (IDO) metabolizes L-tryptophan to L-kynurenine, promotes immunosuppression, and has been described as a consumer of superoxide. We discovered IDO expression in periaortic fat and tested the hypothesis that periarterial IDO functionally reduces agonist-induced contraction. Our model was the thoracic aorta, abdominal aorta, and superior mesenteric artery of the male Sprague-Dawley rat. Periaortic fat from the thoracic aorta stained intensely for IDO, the brown fat marker uncoupling protein-1, and oil red O as a general lipid marker. White fat around the mesenteric artery and abdominal aorta stained less for IDO; brown fat was less abundant. IDO activity (kynurenine-to-tryptophan ratio via HPLC) was detected in visceral and mesenteric artery fat (ratio: ?4) but was highest in perithoracic aortic fat (ratio: 10 ± 1.1). In isometric contractile experiments, periadventitial fat reduced ANG II-induced thoracic aortic (with fat: 34% of without fat) and mesenteric artery (with fat: 63% of without fat) maximal contraction. In contrast, periadventitial fat did not reduce agonist-induced contraction in the abdominal aorta. The IDO inhibitor 1-L-methyltryptophan (1-MT) reversed the fat-induced reduction of ANG II-induced contraction in the thoracic aorta but not in the mesenteric artery. The IDO metabolite kynurenine relaxed the thoracic aorta only at high (9 mM) concentrations, whereas the downstream metabolite quinolinic acid (1 mM) relaxed the contracted thoracic aorta (?80%). 1-MT did not correct the reduction in basal superoxide levels observed in the presence of perithoracic aortic fat. We conclude that IDO is an enzyme active primarily in brown fat surrounding the thoracic aorta and depresses aortic contractility.
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Comparison of the function of the serotonin transporter in the vasculature of male and female rats.
Clin. Exp. Pharmacol. Physiol.
PUBLISHED: 03-05-2011
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1. The serotonin transporter (SERT) handles serotonin (5-hydroxytryptamine (5-HT)) and is blocked by the antidepressant SERT inhibitors fluoxetine and fluvoxamine. Although the importance of SERT in the central nervous system is clear, SERT also functions in the peripheral vasculature. In the present study, we tested the hypothesis that the vasculature from female rats has increased SERT function compared with male rats because females are more responsive to SERT inhibitors. 2. In addition to in vitro experiments, in vivo experiments were used to evaluate how male and female rats handle chronically elevated levels of 5-HT. Wild-type (WT) and SERT-knockout (SERT-KO) rats were infused with 5-HT (25 ?g/kg per min) for 7 days by minipump. 3. Using HPLC analysis, we demonstrated that blood vessels (aorta, carotid artery, jugular vein and vena cava) from naïve, non-infused female rats took up 5-HT acutely in vitro in a SERT-dependent manner. In in vitro experiments, SERT affected the contractility of aortas from female rats, as evidenced by an eightfold increase in potency of 5-HT in fluvoxamine (1 ?mol/L)-incubated WT aortas compared with control. Fluvoxamine did not alter 5-HT-induced contraction in aortas from SERT-KO female rats. 4. Infusion of 5-HT resulted in an increase in tissue 5-HT that was reduced to a larger extent in blood vessels from female than male SERT-KO rats. Aortic contractions to 5-HT were abolished in aortas from male and female 5-HT-infused SERT-KO rats compared with WT rats. 5. Collectively, these data suggest that SERT function, when challenged with 5-HT, is modestly more important in the vasculature of the female compared with male rat.
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Cloning and tissue expression of the equine transferrin receptor.
Vet Clin Pathol
PUBLISHED: 11-11-2010
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Characterization of anemia in horses presents a challenge, as they do not release reticulocytes into peripheral blood. Transferrin receptor (TfR) expression is highest on erythroid cells in people and rats, and measurement of a soluble serum form (sTfR) is used to quantify erythropoiesis in these species. We hypothesized that equine TfR (eTfR) expression is similar in quantity and distribution to that in these other species and thus has potential for characterization of the regenerative response in anemic horses.
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Allopurinol does not decrease blood pressure or prevent the development of hypertension in the deoxycorticosterone acetate-salt rat model.
J. Cardiovasc. Pharmacol.
PUBLISHED: 10-01-2010
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Reactive oxygen species play an important role in the pathogenesis of hypertension, disease in which reactive oxygen species levels and markers of oxidative stress are increased. Xanthine oxidase (XO) is a reactive oxygen species-producing enzyme the activity of which may increase during hypertension. Studies on XO inhibition effects on blood pressure have yielded controversial results. We hypothesized that XO inhibition would decrease blood pressure or attenuate the development of deoxycorticosterone acetate (DOCA)-salt hypertension. We administered the XO inhibitor, allopurinol (50 mg/kg per day, orally) or its vehicle to rats during the established or development stages of DOCA-salt hypertension. We validated XO inhibition by high-performance liquid chromatography measurements of XO metabolites in urine, serum, and tissues demonstrating a decrease in products, increase in substrates, and detection of the active metabolite of allopurinol, oxypurinol. We monitored blood pressure continuously through radiotelemetry and performed gross evaluations of target organs of hypertension. Allopurinol treatment did not impact the course of DOCA-salt hypertension regardless of the timing of administration. Aside from a significant decrease in pulse pressure in allopurinol-treated rats, no positive differences were observed between the allopurinol and the vehicle-treated rats. We conclude that XO does not play an important role in the development or maintenance of hypertension in the rat DOCA-salt hypertension model.
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Differential expression of pancreatitis-associated protein and thrombospondins in arterial versus venous tissues.
J. Vasc. Res.
PUBLISHED: 06-30-2009
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Arteries and veins modulate cardiovascular homeostasis and contribute to hypertension pathogenesis. Functional differences between arteries and veins are based upon differences in gene expression. To better characterize these expression patterns, and to identify candidate genes that could be manipulated selectively in the venous system, we performed whole genome expression profiling of arteries and veins.
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Development of 11 polymorphic microsatellite markers in a macrophyte of conservation concern, Vallisneria americana Michaux (Hydrocharitaceae).
Mol Ecol Resour
PUBLISHED: 02-25-2009
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Vallisneria americana Michaux (wild celery) is currently a target of submersed aquatic vegetation restoration efforts in the Chesapeake Bay watershed. To aid these efforts, we have developed 11 polymorphic microsatellite markers to assess the distribution and degree of genetic diversity in both restored and naturally occurring populations in the Chesapeake Bay. In 59 individuals from two populations, we detected two to 10 total alleles per locus. Observed heterozygosity ranged from 0.125 to 0.929, and two loci exhibited significant deviations from Hardy-Weinberg equilibrium in at least one of the populations assayed.
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Interaction between GABA and norepinephrine in interleukin-1beta-induced suppression of the luteinizing hormone surge.
Brain Res.
PUBLISHED: 02-04-2009
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Interleukin-1beta (IL-1beta), a cytokine that is closely associated with inflammation and immune stress, is known to interfere with reproductive functions. Earlier studies have demonstrated that IL-1beta inhibits the luteinizing hormone (LH) surge during the afternoon of proestrus in female rats. We have shown that this effect is most probably mediated through a reduction in norepinephrine (NE) levels in the medial preoptic area (MPA) of the hypothalamus. However, the mechanism by which IL-1beta decreases NE levels in the MPA is unclear. We hypothesized that the inhibitory neurotransmitter, GABA could play a role in decreasing NE levels in the MPA. To test this, ovariectomized, steroid-primed rats were injected (i.p.) with either PBS-BSA (control) or 5 microg of IL-1beta, alone or in combination with i.c.v. administration of GABA-A and GABA-B receptor antagonists, Bicuculline and CGP 35348 (CGP) respectively. Animals were subjected to push-pull perfusion of the MPA and perfusates collected at 30 min intervals were analyzed for both NE and GABA levels using HPLC-EC. Simultaneously, serial plasma samples were obtained through jugular catheters and were analyzed for LH levels using RIA. Compared to control rats, NE levels decreased significantly in the MPA in IL-1beta-treated rats (p<0.05). Concurrently, there was a significant increase in GABA levels in the MPA (p<0.05). The GABA-A receptor antagonist, bicuculline, was able to reverse the effect of IL-1beta on NE and LH, while the GABA-B receptor antagonist, CGP 35348 was without any effect. This leads us to conclude that the IL-1beta-induced suppression of the LH surge is most probably mediated through an increase in GABA levels in the MPA which causes a reduction in NE levels. This is probably one of the mechanisms by which IL-1beta inhibits reproductive functions.
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Body distribution of infused serotonin in rats.
Clin. Exp. Pharmacol. Physiol.
PUBLISHED: 01-18-2009
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1. Our goal was to investigate the body distribution of serotonin (5-hydroxytryptamine; 5-HT) in rats infused with 5-HT (25 microg/kg per min) for 7 days and the contribution of the 5-HT transporter (SERT) for 5-HT uptake into the tissues. 2. Mini-osmotic pumps containing 5-HT or vehicle were implanted in rats knocked out for SERT (SERT-KO) or in wild-type (WT) rats. On the 8th day, tissues were harvested for measurements of 5-HT by high-performance liquid chromatography (HPLC). The 5-HT metabolite 5-hydroxyindole acetic acid (5-HIAA) was also measured by HPLC, because an increase in 5-HIAA in tissues from rats receiving 5-HT reflects 5-HT uptake followed by metabolism. 3. In WT rats infused with 5-HT, an increase in 5-HT or 5-HIAA was observed in the heart, pancreas, thyroid, adrenal gland, kidney, seminal vesicle, bladder, prostate, liver, oesophagus, stomach, femur, trachea, lung and spleen compared with vehicle-infused rats. An increase in 5-HT and 5-HIAA was not observed in aorta, vena cava and jejunum. In tissues from SERT-KO rats infused with 5-HT, the content of 5-HT or 5-HIAA was decreased in most of the tissues studied compared with 5-HT-infused WT rats. Although 5-HT uptake in the kidney, seminal vesicle, prostate, jejunum and trachea is SERT dependent, it is SERT independent in the pancreas. The remaining tissues display SERT-dependent and -independent mechanisms for 5-HT uptake. 4. Altogether, tissues from different systems, such as the cardiovascular, endocrine, genitourinary and gastrointestinal, accumulate 5-HT mainly via SERT and, thus, these systems are potential targets for drugs that interfere with 5-HT homeostasis.
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One-month serotonin infusion results in a prolonged fall in blood pressure in the deoxycorticosterone acetate (DOCA) salt hypertensive rat.
ACS Chem Neurosci
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A 7-day infusion of serotonin (5-hydroxytryptamine, 5-HT) causes a sustained fall in elevated blood pressure in the male deoxycorticosterone acetate (DOCA)-salt rat. As hypertension is a long-term disease, we presently test the hypothesis that a longer (30 day) 5-HT infusion could cause a sustained fall in blood pressure in the established hypertensive DOCA-salt rat. This time period (?4 weeks) was also sufficient to test whether 5-HT could attenuate the development of DOCA-salt hypertension. 5-HT (25 ?g/kg/min; sc) or vehicle (Veh) was delivered via osmotic pump to (1) established DOCA-salt rats for one month, (2) Sprague-Dawley rats prior to DOCA-salt administration for one month, and blood pressure and heart rate measured telemetrically. On the final day of 5-HT infusion, free platelet poor plasma 5-HT concentrations were significantly higher in 5-HT versus Veh-infused rats, and mean arterial pressure was significantly lower in 5-HT-infused (135 ± 4 mmHg vs Veh-infused 151 ± 7 mmHg) established DOCA-salt rats. By contrast, 5-HT-infusion did not prevent the development of DOCA-salt hypertension (144 ± 7 mmHg vs Veh = 156 ± 6 mmHg). Isometric contraction of aortic strips was measured, and neither the potency nor maximum contraction to the alpha adrenergic receptor agonist phenylephrine (PE) or 5-HT were modified by infusion of 5-HT (established or preventative infusion), and maximum aortic relaxation to acetylcholine (ACh) was modestly but not significantly enhanced (?15% improvement). This study demonstrates 5-HT is capable of lowering blood pressure in established DOCA-salt hypertensive rats over the course of one month in a mechanism that does not significantly modify or is dependent on modified vascular responsiveness. This finding opens the possibility that elevation of 5-HT levels could be useful in the treatment of hypertension.
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Limitations on orchid recruitment: not a simple picture.
Mol. Ecol.
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Mycorrhizal fungi have substantial potential to influence plant distribution, especially in specialized orchids and mycoheterotrophic plants. However, little is known about environmental factors that influence the distribution of mycorrhizal fungi. Previous studies using seed packets have been unable to distinguish whether germination patterns resulted from the distribution of appropriate edaphic conditions or the distribution of host fungi, as these cannot be separated using seed packets alone. We used a combination of organic amendments, seed packets and molecular assessment of soil fungi required by three terrestrial orchid species to separate direct and indirect effects of fungi and environmental conditions on both seed germination and subsequent protocorm development. We found that locations with abundant mycorrhizal fungi were most likely to support seed germination and greater growth for all three orchids. Organic amendments affected germination primarily by affecting the abundance of appropriate mycorrhizal fungi. However, fungi associated with the three orchid species were affected differently by the organic amendments and by forest successional stage. The results of this study help contextualize the importance of fungal distribution and abundance to the population dynamics of plants with specific mycorrhizal requirements. Such phenomena may also be important for plants with more general mycorrhizal associations.
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CD40 ligand is necessary and sufficient to support primary diffuse large B-cell lymphoma cells in culture: a tool for in vitro preclinical studies with primary B-cell malignancies.
Leuk. Lymphoma
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Established cell lines are utilized extensively to study tumor biology and preclinical therapeutic development. However, they may not accurately recapitulate the heterogeneity of their corresponding primary disease. B-cell tumor cells are especially difficult to maintain under conventional culture conditions, limiting access to samples that faithfully represent this disease for preclinical studies. Here, we used primary canine diffuse large B-cell lymphoma to establish a culture system that reliably supports the growth of these cells. CD40 ligand, either expressed by feeder cells or provided as a soluble two-trimeric form, was sufficient to support primary lymphoma cells in vitro. The tumor cells retained their original phenotype, clonality and known karyotypic abnormalities after extended expansion in culture. Finally, we illustrate the utility of the feeder cell-free culture system for comparable assessment of cytotoxicity using dog and human B-cell malignancies. We conclude that this system has broad applications for in vitro preclinical development for B-cell malignancies.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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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.