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Find video protocols related to scientific articles indexed in Pubmed.
Inhibition of connexin 36 hemichannels by glucose contributes to the stimulation of insulin secretion.
Am. J. Physiol. Endocrinol. Metab.
PUBLISHED: 04-15-2014
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The existence of functional connexin36 (Cx36) hemichannels in ?-cells was investigated in pancreatic islets of rat and wild-type (Cx36(+/+)), monoallelic (Cx36(+/-)), and biallelic (Cx36(-/-)) knockout mice. Hemichannel opening by KCl depolarization was studied by measuring ATP release and changes of intracellular ATP (ADP). Cx36(+/+) islets lost ATP after depolarization with 70 mM KCl at 5 mM glucose; ATP loss was prevented by 8 and 20 mM glucose or 50 ?M mefloquine (connexin inhibitor). ATP content was higher in Cx36(-/-) than Cx36(+/+) islets and was not decreased by KCl depolarization; Cx36(+/-) islets showed values between that of control and homozygous islets. Five minimolar extracellular ATP increased ATP content and ATP/ADP ratio and induced a biphasic insulin secretion in depolarized Cx36(+/+) and Cx36(+/-) but not Cx36(-/-) islets. Cx36 hemichannels expressed in oocytes opened upon depolarization of membrane potential, and their activation was inhibited by mefloquine and glucose (IC?? ?8 mM). It is postulated that glucose-induced inhibition of Cx36 hemichannels in islet ?-cells might avoid depolarization-induced ATP loss, allowing an optimum increase of the ATP/ADP ratio by sugar metabolism and a biphasic stimulation of insulin secretion. Gradual suppression of glucose-induced insulin release in Cx36(+/-) and Cx36(-/-) islets confirms that Cx36 gap junction channels are necessary for a full secretory stimulation and might account for the glucose intolerance observed in mice with defective Cx36 expression. Mefloquine targeting of Cx36 on both gap junctions and hemichannels also suppresses glucose-stimulated secretion. By contrast, glucose stimulation of insulin secretion requires Cx36 hemichannels' closure but keeping gap junction channels opened.
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Coordination Equilibria Between Seven- and Five-coordinate Iron(II) Complexes.
Inorg Chem
PUBLISHED: 10-10-2013
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Octahedral, tetrahedral, and square planar geometries are the most often encountered coordination geometries for transition metal complexes. In certain cases, coordination equilibria can exist between different geometries, such as between six- and four-coordinate geometries in nickel(II) complexes, which were discovered half a century ago. Here, we present the first examples of a seven-five coordination equilibrium. Extensive spectroscopic studies in solution have provided evidence for a dynamic equilibrium between two iron(II) complexes, one with a seven-coordinate pentagonal bipyramidal geometry and one with a five-coordinate trigonal bipyramidal geometry.
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Circulating levels of miR-133a predict the regression potential of left ventricular hypertrophy after valve replacement surgery in patients with aortic stenosis.
J Am Heart Assoc
PUBLISHED: 08-17-2013
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Myocardial microRNA-133a (miR-133a) is directly related to reverse remodeling after pressure overload release in aortic stenosis patients. Herein, we assessed the significance of plasma miR-133a as an accessible biomarker with prognostic value in predicting the reversibility potential of LV hypertrophy after aortic valve replacement (AVR) in these patients.
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Cooperation of taurine uptake and dopamine D1 receptor activation facilitates the induction of protein synthesis-dependent late LTP.
Neuropharmacology
PUBLISHED: 06-14-2013
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Co-activation of NMDA and dopamine receptors is required for the induction of the late phase of LTP (L-LTP) that is dependent on new protein synthesis. Other neuromodulatory substances may also contribute to this process. Here, we examined whether taurine is one of the neuromodulators contributing to L-LTP induction, since it is known that taurine uptake induces a long-lasting synaptic potentiation dependent on protein synthesis, and taurine uptake inhibition blocks L-LTP induced by tetanization. Experiments were conducted using rat hippocampal slices where field synaptic potentials were evoked and recorded in CA3-CA1 synapses. Taurine (1 mM) applied 10 min before a high frequency stimulation (HFS) train converted a transitory early-LTP (E-LTP) into an L-LTP dependent on protein synthesis. This taurine effect was blocked by a taurine uptake inhibitor. A facilitation of L-LTP induction was also obtained by pre-application of SKF38393, a D1/D5 dopamine receptor (D1R) agonist. In this case, LTP facilitation was not affected by the taurine uptake inhibitor. Nevertheless, when taurine and SKF38393 were simultaneously pre-applied at a concentration that individually did not modify E-LTP, they produced a synergistic mechanism that facilitated the induction of L-LTP with a sole HFS train. This facilitation of L-LTP was blocked by inhibiting either taurine uptake or D1R activation. Taurine and SKF38393 activated different signaling pathways to transform E-LTP into L-LTP. Taurine-induced L-LTP facilitation required MAPK activation, while D1R-agonist-induced facilitation depended mainly on PKA activation and partially on MAPK activation. On the other hand, the synergistic mechanisms induced by the cooperative action of taurine and SKF38393 were impaired by inhibitors against MAPK, PKA and PI3-K. This pharmacological profile resembles that displayed by L-LTP induced by three HFS trains at 10-min intervals. These results indicate that taurine uptake is necessary and cooperates with other neurotransmitter systems in the induction of L-LTP.
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Preclinical studies of the role of iron oxide magnetic nanoparticles for nonpalpable lesion localization in breast cancer.
J. Surg. Res.
PUBLISHED: 04-01-2013
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One-third of all breast cancers are present as clinically nonpalpable lesions. The current gold standard treatment is surgical excision by wire-guided localization. This technique has patient, technical, and scheduling drawbacks. Alternatives exist but depend on radioisotopes with their legislative and waste management issues. Magnetic nanoparticles (MNPs) have already been successfully used for sentinel lymph node biopsy in breast cancer. We therefore aimed to determine the feasibility of using iron oxide MNPs and a handheld magnetometer for the localization of nonpalpable breast cancers using a preclinical model.
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Synthesis of 9-amino(9-deoxy)epi cinchona alkaloids, general chiral organocatalysts for the stereoselective functionalization of carbonyl compounds.
Nat Protoc
PUBLISHED: 01-17-2013
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We describe two procedures for the synthesis of primary amines derived from 9-amino(9-deoxy)epi cinchona alkaloids, valuable catalysts used in the asymmetric functionalization of carbonyl compounds. The first approach allows the one-pot 5-g-scale syntheses of four cinchona-based analogs (1, 3, 5 and 7) from the alkaloids quinine (QN), quinidine (QD), dihydroquinine (DHQN) and dihydroquinidine (DHQD), respectively, performed by means of a Mitsunobu reaction to introduce an azide group, followed by reduction and hydrolysis. Demethylation of 1, 3, 5 and 7 with BBr(3) provided direct access to the bifunctional aminocatalysts 2, 4, 6 and 8. A second approach, more convenient for scale-up (tested to a 20-g scale), is also provided. In this second procedure, the azides, formed from the O-mesylated derivatives of QN and QD, are selectively reduced with LiAlH(4) to afford catalysts 1 and 3, whereas hydrogenation (Pd/C) provides 5 and 7. Demethylation of 1, 3, 5 and 7 using an alkylthiolate affords 2, 4, 6 and 8 in a process in which the less-expensive QN and QD are the only starting materials used.
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Continuous-flow enantioselective ?-aminoxylation of aldehydes catalyzed by a polystyrene-immobilized hydroxyproline.
Beilstein J Org Chem
PUBLISHED: 08-31-2011
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The application of polystyrene-immobilized proline-based catalysts in packed-bed reactors for the continuous-flow, direct, enantioselective ?-aminoxylation of aldehydes is described. The system allows the easy preparation of a series of ?-aminoxy alcohols (after a reductive workup) with excellent optical purity and with an effective catalyst loading of ca. 2.5% (four-fold reduction compared to the batch process) working at residence times of ca. 5 min.
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Bovine parthenogenotes produced by inhibition of first or second polar bodies emission.
Biocell
PUBLISHED: 06-15-2011
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Parthenogenetic embryos are an ethically acceptable alternative for the derivation of human embryonic stem cells. In this work, we propose a new strategy to produce bovine parthenogenetic embryos inhibiting the emission of the first polar body during in vitro maturation, and allowing the extrusion of the second polar body during oocyte activation. Cytochalasin B, an inhibitor of actin microfilaments, was employed during in vitro maturation to inhibit first polar body emission or during parthenogenetic activation to block second polar body emission. Only one polar body was inhibited in each strategy in order to keep the diploid chromosome set. In experiment 1, the effect of cytochalasin B on in vitro maturation of bovine oocytes was evaluated. Most oocytes (77%) were arrested at a meiotic stage characterized by the presence of a large internal metaphase plate and absence of polar body. In experiment 2, development of embryos exposed to cytochalasin B during in vitro maturation (CytoB-IVM) or during activation (CytoB-ACT) was compared. Developmental rates did not differ between diploidization strategies, even when three agents were employed to induce activation. Both groups, CytoB-IVM and CytoB-ACT, tended to maintain diploidy. CytoB-IVM parthenogenesis could help to obtain embryos with a higher degree of homology to the oocyte donor.
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Myocardial gene expression of microRNA-133a and myosin heavy and light chains, in conjunction with clinical parameters, predict regression of left ventricular hypertrophy after valve replacement in patients with aortic stenosis.
Heart
PUBLISHED: 05-17-2011
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Left ventricular (LV) reverse remodelling after valve replacement in aortic stenosis (AS) has been classically linked to the hydraulic performance of the replacement device, but myocardial status at the time of surgery has received little attention.
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Highly active organocatalysts for asymmetric anti-Mannich reactions.
Chemistry
PUBLISHED: 05-16-2011
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Lighten the load! A family of enantiopure 4-oxy-substituted 3-aminopyrrolidines arising from the enantioselective ring-opening of meso-3-pyrroline oxide have been developed as catalysts for the asymmetric, anti-selective Mannich reaction (see scheme; PMP=p-methoxyphenyl; PG=protecting group). Very high catalytic activity (down to 0.01 mol % loading) and stereoselectivity have been recorded.
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Reliability of squat and countermovement jump tests in children 6 to 8 years of age.
Pediatr Exerc Sci
PUBLISHED: 04-07-2011
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The aim of this study was to determine the reliability of the squat jump test (SJ) and countermovement jump test (CMJ), in fifty-six children (30 girls and 26 boys) with ages ranging from 6 to 8 years. Each subject performed two evaluation sessions (T1, T2) with seven days between tests. The results show that the CMJ test has a high intratrial reproducibility in T1 and T2 measured through intraclass correlation coefficient (ICC ? 0.95). The ICC for the SJ test had a high value (0.99) only in T1. The variability for both tests among children under 9 years of age is higher than those reported for adult subjects in other studies. The intersession reliability was questionable with a high methodical error (ME= 9.86-15.1%, for the SJ and CMJ, respectively) and a significant worsening of the results of CMJ in T2 (p < .05).
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(??m)Tc-bisphosphonate-iron oxide nanoparticle conjugates for dual-modality biomedical imaging.
Bioconjug. Chem.
PUBLISHED: 02-21-2011
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The combination of radionuclide-based imaging modalities such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) with magnetic resonance imaging (MRI) is likely to become the next generation of clinical scanners. Hence, there is a growing interest in the development of SPECT- and PET-MRI agents. To this end, we report a new class of dual-modality imaging agents based on the conjugation of radiolabeled bisphosphonates (BP) directly to the surface of superparamagnetic iron oxide (SPIO) nanoparticles. We demonstrate the high potential of BP-iron oxide conjugation using (??m)Tc-dipicolylamine(DPA)-alendronate, a BP-SPECT agent, and Endorem/Feridex, a liver MRI contrast agent based on SPIO. The labeling of SPIOs with (??m)Tc-DPA-alendronate can be performed in one step at room temperature if the SPIO is not coated with an organic polymer. Heating is needed if the nanoparticles are coated, as long as the coating is weakly bound as in the case of dextran in Endorem. The size of the radiolabeled Endorem (??m)Tc-DPA-ale-Endorem) was characterized by TEM (5 nm, Fe?O? core) and DLS (106 ± 60 nm, Fe?O? core + dextran). EDX, Dittmer-Lester, and radiolabeling studies demonstrate that the BP is bound to the nanoparticles and that it binds to the Fe?O? cores of Endorem, and not its dextran coating. The bimodal imaging capabilities and excellent stability of these nanoparticles were confirmed using MRI and nanoSPECT-CT imaging, showing that (??m)Tc and Endorem co-localize in the liver and spleen In Vivo, as expected for particles of the composition and size of (??m)Tc-DPA-ale-Endorem. To the best of our knowledge, this is the first example of radiolabeling SPIOs with BP conjugates and the first example of radiolabeling SPIO nanoparticles directly onto the surface of the iron oxide core, and not its coating. This work lays down the basis for a new generation of SPECT/PET-MR imaging agents in which the BP group could be used to attach functionality to provide targeting, stealth/stability, and radionuclides to Fe?O? nanoparticles using very simple methodology readily amenable to GMP.
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Novel methods to induce exogenous gene expression in SCNT, parthenogenic and IVF preimplantation bovine embryos.
Transgenic Res.
PUBLISHED: 02-18-2011
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The import of exogenous DNA (eDNA) from the cytoplasm to the nucleus represents a key intracellular obstacle for efficient gene delivery in mammalian cells. In this study, cumulus cells or oolemma vesicles previously incubated with eDNA, and naked eDNA were injected into the cytoplasm of MII oocytes to evaluate their efficiency for eDNA expressing bovine embryo production. Our study evaluated the potential of short time co-incubation (5 min) of eDNA with; (1) cumulus cells, to be used as donor cells for SCNT and (2) oolemma vesicles (vesicles) to produce parthenogenic transgene expressing embryos. In addition, we included a group consisting of the injection of eDNA alone (plasmid) followed by parthenogenic activation. Two different pCX-EGFP plasmid concentrations (50 and 500 ng/?l) were employed. The results showed that embryos produced by SCNT and by vesicle injection assisted by chemical activation were able to express the eDNA in higher rates than embryos injected with plasmid alone. The lower plasmid concentration allowed the highest development rates in all groups. Using confocal microscopy, we analyzed the interaction of FITC- labeled eDNA with cumulus cells and vesicles as well as oocytes injected with labeled plasmid alone. Our images demonstrated that eDNA interacted with cumulus cells and vesicles, resulting an increase in its expression efficiency. In contrast, oocytes injected with DNA alone did not show signs of transgene accumulation, and their eDNA expression rates were lower. In a further experiment, we evaluated if transgene-expressing embryos could be produced by means of vesicle injection followed by IVF. The lower plasmid concentration (50 ng/?l) injected after IVF, produced the best results. Preliminary FISH analysis indicated detectable integration events in 1/5 of SCNT blastocysts treated. Our studies demonstrate for the first time that short term transgene co-incubation with somatic cells can produce transgene-expressing mammalian SCNT embryos and also that parthenogenic, eDNA- expressing embryos can be obtained by injection of vesicles or eDNA alone. Moreover, eDNA-expressing embryos can be also obtained by cytoplasmic injection vesicles in IVF zygotes, simplifying the traditional IVF pronuclear injection technique.
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Effects of bone morphogenic protein 4 (BMP4) and its inhibitor, Noggin, on in vitro maturation and culture of bovine preimplantation embryos.
Reprod. Biol. Endocrinol.
PUBLISHED: 02-01-2011
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BMP4 is a member of the transforming growth factor beta (TGFbeta) superfamily and Noggin is a potent BMP inhibitor that exerts its function by binding to BMPs preventing interactions with its receptors. The aim of this work was to investigate the role of BMP4 and Noggin, on oocytes in vitro maturation (m experiments) and embryos in vitro development (c experiments) of bovine.
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Efficacy and safety of an intraoral electrostimulation device for xerostomia relief: a multicenter, randomized trial.
Arthritis Rheum.
PUBLISHED: 02-01-2011
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To evaluate the efficacy and safety of an intraoral electrostimulation device, consisting of stimulating electrodes, an electronic circuit, and a power source, in treating xerostomia. The device delivers electrostimulation through the oral mucosa to the lingual nerve in order to enhance the salivary reflex.
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Reduction of plasma membrane glutamate transport potentiates insulin but not glucagon secretion in pancreatic islet cells.
Mol. Cell. Endocrinol.
PUBLISHED: 01-06-2011
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Glutamate is generated during nutrient stimulation of pancreatic islets and has been proposed to act both as an intra- and extra-cellular messenger molecule. We demonstrate that glutamate is not co-secreted with the hormones from intact islets or purified ?- and ?-cells. Fractional glutamate release was 5-50 times higher than hormone secretion. Furthermore, various hormone secretagogues did not elicit glutamate efflux. Interestingly, epinephrine even decreased glutamate release while increasing glucagon secretion. Rather than being co-secreted with hormones, we show that glutamate is mainly released via plasma membrane excitatory amino acid transporters (EAAT) by uptake reversal. Transcripts for EAAT1, 2 and 3 were present in both rat ?- and ?-cells. Inhibition of EAATs by L-trans-pyrrolidine-2,4-dicarboxylate augmented intra-cellular glutamate and ?-ketoglutarate contents and potentiated glucose-stimulated insulin secretion from islets and purified ?-cells without affecting glucagon secretion from ?-cells. In conclusion, intra-cellular glutamate-derived metabolite pools are linked to glucose-stimulated insulin but not glucagon secretion.
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Predictors of long-term renal function after conversion to proliferation signal inhibitors in long-term heart transplant recipients.
J. Heart Lung Transplant.
PUBLISHED: 01-06-2011
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The purpose of this study was to evaluate the change in renal function and its determinants after replacement of calcineurin inhibitors with a proliferation signal inhibitor (sirolimus or everolimus) in long-term heart transplant recipients.
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Efficiency of sperm-mediated gene transfer in the ovine by laparoscopic insemination, in vitro fertilization and ICSI.
J. Reprod. Dev.
PUBLISHED: 11-10-2010
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Transgenesis constitutes an important tool for pharmacological protein production and livestock improvement. We evaluated the potential of laparoscopic insemination (LI), in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) to produce egfp-expressing ovine embryos, using spermatozoa previously exposed to pCX-EGFP plasmid in two different sperm/DNA incubation treatments: "Long Incubation" (2 h at 17 C) and "Short Incubation" (5 min at 5 C). For LI, Merino sheep were superovulated and inseminated with treated fresh semen from Merino rams. The embryos were recovered by flushing the uterine horns. For IVF and ICSI, slaughterhouse oocytes were fertilized with DNA-treated frozen/thawed sperm. All recovered embryos were exposed to blue light (488 nm) to determine green fluorescent morulae and blastocysts rates. High cleavage and morulae/blastocysts rates accompanied the LI and IVF procedures, but no egfp-expressing embryos resulted. In contrast, regardless of the sperm/plasmid incubation treatment, egfp-expressing morulae and blastocysts were always obtained by ICSI, and the highest transgenesis rate (91.6%) was achieved with Short Incubation. In addition, following the incubation of labeled plasmid DNA, after Long or Short exposure treatments, with fresh or frozen/thawed spermatozoa, only non-motile fresh spermatozoa could maintain an attached plasmid after washing procedures. No amplification product could be detected following PCR treatment of LI embryos whose zonae pellucidae (ZP) had been removed. In order to establish conditions for transgenic ICSI in the ovine, we compared three different activation treatments, and over 60% of the obtained blastocysts expressed the transgene. For ICSI embryos, FISH analysis found possible signals compatible with integration events. In conclusion, our results show that in the ovine, under the conditions studied, ICSI is the only method capable of producing exogenous gene-expressing embryos using spermatozoa as vectors.
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Iron(II) complexes with tetradentate bis(aminophenolate) ligands: synthesis and characterization, solution behavior, and reactivity with O(2).
Inorg Chem
PUBLISHED: 11-09-2010
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Tetradentate bis(aminophenolate) ligands H(2)salan(X) and H(2)bapen(X) (where X refers to the para-phenolate substituent = H, Me, F, Cl) react with [Fe{N(SiMe(3))(2)}(2)] to form iron(II) complexes, which in the presence of suitable donor ligands L (L = pyridine or THF) can be isolated as the complexes [Fe(salan(X))(L)(2)] and [Fe(bapen(X))(L)(2)]. In the absence of donor ligands, either mononuclear complexes, for example, [Fe(salan(tBu,tBu))], or dinuclear complexes of the type [Fe(salan(X))](2) are obtained. The dynamic coordination behavior in solution of the complexes [Fe(salan(F))(L)(2)] and [Fe(bapen(F))(L)(2)] has been investigated by VT (1)H and (19)F NMR spectroscopy, which has revealed equilibria between isomers with different ligand coordination topologies cis-?, cis-? and trans. Exposure of the iron(II) salan(X) complexes to O(2) results in the formation of oxo-bridged iron(III) complexes of the type [{Fe(salan(X))}(2)(?-O)] or [{Fe(salan(X))(L)}(2)(?-O)]. The lack of catalytic activity of the iron(II) salan and bapen complexes in the oxidation of cyclohexane with H(2)O(2) as the oxidant is attributed to the rapid formation of stable and catalytically inactive oxo-bridged iron(III) complexes.
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[Development and validation of a questionnaire about the main variables affecting the individual investors behavior in the Stock Exchange].
Psicothema
PUBLISHED: 11-04-2010
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Development and validation of a questionnaire about the main variables affecting the individual investors behavior in the Stock Exchange. There is a considerable lack of information about the methodology usually used in most of the studies about individual investors behavior. The studies reviewed do not show the method used in the selection of the items or the psychometric properties of the questionnaires. Because of the importance of investment in the Stock Exchange nowadays, it seems relevant to obtain a reliable instrument to understand individual investors behavior in the Stock Exchange. Therefore, the goal of the present work is to validate a questionnaire about the main variables involved in individual investors behavior in the Stock Exchange. Based on previous studies, we elaborated a questionnaire using the Delphi methodology with a group of experts. The internal consistency (Cronbach alpha=.934) and validity evidence of the questionnaire show that it may be an effective instrument and can be applied with some assurance.
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Activation with ionomycin followed by dehydroleucodine and cytochalasin B for the production of parthenogenetic and cloned bovine embryos.
Cell Reprogram
PUBLISHED: 08-12-2010
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In this work, Dehydroleucodine (DhL) was evaluated as a chemical activator of bovine oocytes and somatic cell nuclear transfer (SCNT) reconstituted embryos. Oocytes were activated with 5 microM Ionomycin (Io) and exposed for 3 h to 1 or 5 microM DhL alone (Io-Dhl1 or Io-DhL5) or combined with Cytochalasin B (Io-DhL1/CB; Io-DhL5/CB). Control groups were Io (Io), Io followed by 1.9 mM 6-Dimethylaminopurine (Io-6DMAP), and embryos produced by in vitro fertilization (IVF). Pronuclear formation and development to blastocysts of activated oocytes were evaluated. Embryos obtained by the DhL concentration that induced the highest blastocyst rates (1 microM) were karyotyped. An additional treatment based in Io-DhL1 plus lengthened (6-h) exposure to CB (Io-DhL1/long CB) was included to improve the proportion of diploid blastomeres. Finally, DhL combined with CB was employed to assist cloning by intracytoplasmic injection of whole cumulus cells. Results showed that DhL induces a pronuclear formation dynamic that was more similar to IVF-produced embryos than DMAP. Development to blastocyst stage was higher after activation with 1 microM DhL than with 5 microM DhL, either for groups combined or not with CB (19.15; 21.74 vs. 6.82; 0%, respectively) (p < 0.05). Io-DhL1 and Io-DhL1/CB treatments induced blastocyst-cleaved embryo ratios not statistically different from those of Io-DMAP (35.85%) and IVF (33.33%) groups (p > 0.05). Io-DhL1/long CB induced higher diploid blastomere rates than Io-Dhl1, Io-DhL1/CB and Io-DMAP (63.8 vs. 36.8; 40 and 31.6%, respectively) (p < 0.05). Moreover, all DhL treatments resulted in polyploidy rates that were lower than Io-DMAP (5.2, 12.0, 10.6, and 31.6%, respectively) (p < 0.05). Io-DhL1/CB and Io-DhL1/long CB induced cloned embryo blastocyst rates that were not significantly different from Io-DMAP (6.1, 9.4, and 18.3%, respectively) (p < 0.05). Our results indicate that Io-DhL1/long CB protocol could be useful for SCNT programs.
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Glucose promotion of GABA metabolism contributes to the stimulation of insulin secretion in ?-cells.
Biochem. J.
PUBLISHED: 08-11-2010
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We have demonstrated recently that branched-chain ?-keto acid stimulation of insulin secretion is dependent on islet GABA (?-aminobutyric acid) metabolism: GABA transamination to succinic semialdehyde is increased by 2-oxoglutarate, generated in ?-keto acid transamination to its corresponding ?-amino acid. The present work was aimed at investigating whether glucose also promotes islet GABA metabolism and whether the latter contributes to the stimulation of insulin secretion. Glucose (20 mM) decreased both the content and release of islet GABA. Gabaculine (1 mM), a GABA transaminase inhibitor, partially suppressed the secretory response of rat perifused islets to 20 mM glucose at different L-glutamine concentrations (0, 1 and 10 mM), as well as the glucose-induced decrease in islet GABA. The drug also reduced islet ATP content and the ATP/ADP ratio at 20 mM glucose. Exogenous succinic semialdehyde induced a dose-dependent increase in islet GABA content by reversal of GABA transamination and a biphasic insulin secretion in the absence of glucose. It depolarized isolated ?-cells and triggered action potential firing, accompanied by a reduction of membrane currents through ATP-sensitive K(+) channels. The gene expression and enzyme activity of GABA transaminase were severalfold higher than that of 2-oxoglutarate dehydrogenase in islet homogenates. We conclude that, at high glucose concentrations, there is an increased diversion of glucose metabolism from the citric acid cycle into the GABA shunt. Semialdehyde succinic acid is a cell-permeant GABA-shunt metabolite that increases ATP and the ATP/ADP ratio, depolarizes ?-cells and stimulates insulin secretion. In summary, an increased islet GABA metabolism may trigger insulin secretion.
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[The influence of preventive programs on laboral injuries].
Rev Med Inst Mex Seguro Soc
PUBLISHED: 07-02-2010
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To evaluate the impact of preventive programs at enterprises affiliated to the Instituto Mexicano del Seguro Social (IMSS) during 2004.
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Influence of accumulation of heaps of steel slag on the environment: determination of heavy metals content in the soils.
An. Acad. Bras. Cienc.
PUBLISHED: 06-22-2010
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The presence of high level of heavy metals involves a human healthy risk that could induce chronic diseases. This work reports on the metal contamination due to heaps of steel-slag accumulated during more than 40 years in allotments and industrial areas in the southern part of Madrid (Spain). Several slag and soil samples were collected in an area of 10 km(2) and characterized by different conventional (XRD and XRF) and no so common methods (ESEM, thermoluminescence and EDS-WDS). The analysis reveal the presence of: (i) important amounts of Fe (43%), Mg (26%), Cr (1.1%), Mn (4.6%), S (6.5%) in the form of Fe-rich slag phases (wustite, magnetite...), Si and Ca-rich phases (larnite, ghelenite...), Cr (chromite), Mn (bustamite) and graphite, (ii) traces of some other contaminants such as Cr (7700 ppm), Zn (3500 ppm), Ba (3000 ppm), Pb (700 ppm) or Cu (500 ppm) on pathway soil samples that come from the steel slag, and (iii) Co (13 ppm), Pb (78 ppm) and V (54 ppm) in farmland soil samples. Although the existing heavy metals content is not appropriate for the current use, the extremely high metal contamination of the surrounding areas is more worrying. The properties of the soil farmlands (pH circa 7, 13% of clay, mainly illite, and 1-4% of organic matter content) show suitable conditions for the retention of cationic metals, but further studies on the movilization of these elements have to be performed to determine the possibility of severe human health risks. This sort of study can provide useful information for the politicians regarding the appropriate use of the territory to prevent possible health hazard for the population.
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[Electrostimulation for the treatment of dry mouth].
Harefuah
PUBLISHED: 06-17-2010
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Xerostomia is a very common condition, which not only involves dry mouth feeling, but can also lead to psychosocial distress, impaired quality of life, and complications, such as dental caries and oral candidiasis. It is generally induced by hypofunction of salivary glands, which has a wide variety of etiologies, such as Sjögrens syndrome, radiotherapy to the head and neck and side effects of medications. Current therapies rely on saliva substitutes and pharmacological stimulation of the parasympathetic system. These treatment modalities are somewhat limited by their short-term efficacy, high cost and drug interactions or other adverse effects. Local transcutaneous or permucosal electrostimulation in areas close to the nerves participating in the salivary autonomic reflex has been found to increase salivary secretion in animal and clinical experiments and to relieve symptoms of dry mouth in patients with salivary gland hypofunction. This concept is reviewed to update the readers on the current status and potential of intraoral miniature electrostimulating devices. They offer promise as an optional safe and non-chemical treatment of xerostomia.
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188Re(CO)3-dipicolylamine-alendronate: a new bisphosphonate conjugate for the radiotherapy of bone metastases.
Bioconjug. Chem.
PUBLISHED: 04-15-2010
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The palliation of pain due to bone metastases using targeted compounds containing beta-emitters such as rhenium-188 ((188)Re) is an accepted and effective form of treatment. Here, we describe the efficient synthesis and preclinical evaluation of (188)Re(CO)(3)-dipicolylamine(DPA)-alendronate, a novel bifunctional bisphosphonate for the palliative treatment of bone metastases. (188)Re(CO)(3)-DPA-alendronate can be easily synthesized with high specific activities and yields (18.8 GBq/mg, radiochemical yield > or =96%) in two steps using kit-based methodology, and in contrast with the clinically approved bisphosphonate (186/188)Re-HEDP, it forms inert, single species that have been well-characterized. In vivo imaging and biodistribution studies demonstrate that (188)Re(CO)(3)-DPA-alendronate is superior to (188)Re-HEDP in targeting and accumulating in areas of high metabolic bone activity while having low soft-tissue uptake. In addition to these studies, a simple and convenient new method for purifying its precursor, fac-[(188)Re(CO)(3)(H(2)O)(3)](+), is described.
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Spectroscopic and metal-binding properties of DF3: an artificial protein able to accommodate different metal ions.
J. Biol. Inorg. Chem.
PUBLISHED: 02-14-2010
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The design, synthesis, and metal-binding properties of DF3, a new de novo designed di-iron protein model are described ("DF" represents due ferri, Italian for "two iron," "di-iron"). DF3 is the latest member of the DF family of synthetic proteins. They consist of helix-loop-helix hairpins, designed to dimerize and form an antiparallel four-helix bundle that encompasses a metal-binding site similar to those of non-heme carboxylate-bridged di-iron proteins. Unlike previous DF proteins, DF3 is highly soluble in water (up to 3 mM) and forms stable complexes with several metal ions (Zn, Co, and Mn), with the desired secondary structure and the expected stoichiometry of two ions per protein. UV-vis studies of Co(II) and Fe(III) complexes confirm a metal-binding environment similar to previous di-Co(II)- and di-Fe(III)-DF proteins, including the presence of a mu-oxo-di-Fe(III) unit. Interestingly, UV-vis, EPR, and resonance Raman studies suggest the interaction of a tyrosine adjacent to the di-Fe(III) center. The design of DF3 was aimed at increasing the accessibility of small molecules to the active site of the four-helix bundle. Indeed, binding of azide to the di-Fe(III) site demonstrates a more accessible metal site compared with previous DFs. In fact, fitting of the binding curve to the Hill equation allows us to quantify a 150% accessibility enhancement, with respect to DF2. All these results represent a significant step towards the development of a functional synthetic DF metalloprotein.
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The changing face of prosthetic valve endocarditis at a tertiary-care hospital: 1986-2005.
Rev Esp Cardiol
PUBLISHED: 01-22-2010
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To investigate changes in the clinical characteristics, etiology and prognosis of prosthetic valve endocarditis at a tertiary-care hospital.
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High rates of bovine blastocyst development after ICSI-mediated gene transfer assisted by chemical activation.
Theriogenology
PUBLISHED: 01-02-2010
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In order to establish conditions for intracytoplasmic sperm injection-mediated gene transfer (ICSI-MGT) in cattle, various aspects of fertilization and embryonic development were assessed after five activation treatments. Spermatozoa were co-incubated with pCX-EGFP (pCX-enhanced green fluorescent protein gene) plasmid and injected into metaphase II oocytes, which were then treated with ionomycin (Io), before further activation with the following agents: 6-dimethylaminopurine (Io-DMAP), additional Io plus DMAP (2Io-DMAP), Io alone (2Io), ethanol (Io-EtOH), or strontium chloride (Io-SrCl2). Fertilization rates at 16 h after ICSI, presence of a condensed spermatozoon head on Day 4 (Day 0 = ICSI), blastocyst and EGFP expression rates on Day 7, and Oct-4 pattern of Day 8 blastocysts were evaluated. Fertilization rates did not differ significantly among treatments. All (100%) of EGFP-positive embryos resulted from ICSI fertilization, whereas at least 60% of EGFP-negative embryos (>4 cells) had a condensed sperm head. Blastocyst rates after 2Io-DMAP were not significantly different from Io-DMAP or Io-EtOH, but they were higher than 2Io or Io-SrCl2 treatments (25.9, 18.7, 14.7, 9.4, and 10.9% respectively; P < 0.05). Transgene expression rates were higher for Io-DMAP, 2Io-DMAP and Io-SrCl2 than for 2Io and Io-EtOH (52.3, 53.0, 42.8, 28.2, and 29.4% respectively; P < 0.05). Over 80% of the blastocysts expressed egfp protein. In conclusion, ICSI-MGT was a powerful technique to produce bovine embryos that expressed the EGFP transgene. Moreover, the actual efficiency of ICSI-MGT could be readily evaluated by this method, which uses a marker expressed early in embryo development.
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A prospective randomized open study in liver transplant recipients: daclizumab, mycophenolate mofetil, and tacrolimus versus tacrolimus and steroids.
Liver Transpl.
PUBLISHED: 10-31-2009
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This open-label, randomized study compared the efficacy of a regimen of corticosteroids and tacrolimus (standard therapy group, n = 79) with a regimen of daclizumab induction therapy in combination with mycophenolate mofetil and tacrolimus (modified therapy group, n = 78) in primary liver transplant recipients. The primary endpoint was biopsy-proven acute rejection (BPAR) at 24 weeks. Secondary endpoints included time to rejection and patient and graft survival. The incidence of BPAR was significantly reduced in the modified therapy group compared to the standard therapy group (11.5% versus 26.6%, respectively, P = 0.017). The time to rejection was significantly shorter in the standard therapy group compared with the modified therapy group (P = 0.044). There was no significant difference between groups in patient or graft survival. Hepatitis C virus-positive patients exhibited no differences from hepatitis C virus-negative patients with respect to the incidence of BPAR. A steroid-sparing regimen of daclizumab, mycophenolate mofetil, and tacrolimus was effective and well tolerated in the prevention of BPAR in adult liver transplant recipients in comparison with a standard regimen of tacrolimus and steroids.
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Efficient site-specific radiolabeling of a modified C2A domain of synaptotagmin I with [99mTc(CO)3]+: a new radiopharmaceutical for imaging cell death.
Bioconjug. Chem.
PUBLISHED: 10-31-2009
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We describe the design and synthesis of a new Tc-99m labeled bioconjugate for cell-death imaging, based on C2A, the phosphatidylserine (PS)-binding domain of rat synaptotagmin I. Since several lysine residues in this protein are critical for PS binding, we engineered a new protein, C2AcH, to include the C-terminal sequence CKLAAALEHHHHHH, incorporating a free cysteine (for site-specific covalent modification) and a hexahistidine tag (for site-specific radiolabeling with [99mTc(CO)3(OH2)3]+). We also engineered a second derivative, C2Ac, in which the C-terminal sequence included only the C-terminal cysteine. These proteins were characterized by electrospray mass spectrometry, SDS/PAGE, and size exclusion chromatography and radiolabeled with [99mTc(CO)3(OH2)3]+. Conjugates of the proteins with the rhenium analogue [Re(CO)3(OH2)3]+ were also synthesized. Site-specific labeling was confirmed by performing a tryptic digest of rhenium tricarbonyl-labeled C2AcH, and only peptides containing the His-tag contained the [Re(CO)3]+. The labeled proteins were tested for binding to red blood cells (RBC) with exposed PS in a calcium dependent manner. Labeling 100 microg of C2AcH with [99mTc(CO)3(OH2)3]+ at 37 degrees C for 30 min gave a radiochemical yield of > 96%. However, C2AcH that had first been conjugated with fluorescein maleimide or iodoacetamide via the Cys residue gave only 50% and 83% radiochemical yield, respectively, after incubation for 30 min at 37 degrees C. Serum stability results indicated that >95% of radiolabeled C2AcH remained stable for at least 18 h at 37 degrees C. Site-specifically labeled C2AcH exhibited calcium-dependent binding to the PS on the RBC, whereas a nonspecifically modified derivative, C2AcH-B, in which lysines had been modified with benzyloxycarbonyloxy, did not. We conclude that (i) the combination of Cys and a His-tag greatly enhances the rate and efficiency of labeling with [99mTc(CO)3(OH2)3]+ compared to either the His-tag or the Cys alone, and this sequence deserves further evaluation as a radiolabeling tag; (ii) non-site-specific modification of C2A via lysine residues impairs target binding affinity; (iii) 99mTc-C2AcH has excellent radiolabeling, stability and PS binding characteristics and warrants in vivo evaluation as a cell-death imaging agent.
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Plasma levels of transforming growth factor-beta1 reflect left ventricular remodeling in aortic stenosis.
PLoS ONE
PUBLISHED: 10-06-2009
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TGF-beta1 is involved in cardiac remodeling through an auto/paracrine mechanism. The contribution of TGF-beta1 from plasmatic source to pressure overload myocardial remodeling has not been analyzed. We investigated, in patients with valvular aortic stenosis (AS), and in mice subjected to transverse aortic arch constriction (TAC), whether plasma TGF-beta1 relates with myocardial remodeling, reflected by LV transcriptional adaptations of genes linked to myocardial hypertrophy and fibrosis, and by heart morphology and function.
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Lyomesophases of C3-symmetrical bipyridine-based discs in alkanes: an X-ray diffraction study.
Langmuir
PUBLISHED: 09-26-2009
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The importance of the role of alkane solvents in the self-assembly process of pi-conjugated molecules is well recognized but hardly understood. Here we present our results on the X-ray diffraction studies that we conducted to gain insight into the supramolecular structure of mixtures of a bipyridine-based molecule (1) with alkanes. Independent of the alkane used (linear or branched), above x(w) > 0.06 (with x(w) being the weight fraction of 1) the mixtures show lyotropic liquid-crystalline behavior. The nature of the lyomesophase depends only on x(w) and not on the nature of the alkane (linear or branched). A columnar rectangular phase is present when x(w) > 0.66. Upon dilution of 1, a columnar hexagonal phase is assigned first (0.50 < x(w) < 0.65), and finally a columnar nematic phase is observed when x(w) < 0.50. Concentration-dependent SAXD measurements revealed that the dilution of 1 can be viewed as a swelling process. First, solvent molecules occupy space between the columns formed by 1, which are not disrupted. This process can quantitatively be described by a 2D swelling model. Only at lower concentrations does 3D swelling start as the columns start breaking into shorter fragments.
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Pulmonary venous obstruction after lung transplantation. Diagnostic advantages of transesophageal echocardiography.
Clin Transplant
PUBLISHED: 09-03-2009
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Pulmonary venous vascular complications after lung transplantation are rare and a major cause of morbidity and mortality unless diagnosed and treated early. The epidemiological, diagnostic, and management characteristics of 33 patients (two of them in our hospital) with post-transplant pulmonary vein obstruction published in the literature were reviewed. We consider of utmost importance to differentiate stenosis from thrombosis as the cause of the obstruction. The angiography, considered the gold standard for diagnosis, was replaced by transesophageal echocardiography (TEE) in 79% of the cases, but no echocardiographic diagnostic criteria were defined. A diameter of the pulmonary veins, with 2D/color TEE, <0.5 cm, peak systolic flow velocity (PSFV) >1 m/s, pulmonary vein-left atrial pressure gradient (PVLAG) >/=10-12 mmHg, non-permeable flow through the stenosis and the presence of thrombus at that level, must lead us to suspect this complication. Higher mortality rates were found in unilateral procedures and in women. We consider that TEE must be carried out as part of the intraoperative routine or within the first 24 h of the post-operative period.
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Gender differences of echocardiographic and gene expression patterns in human pressure overload left ventricular hypertrophy.
J. Mol. Cell. Cardiol.
PUBLISHED: 07-30-2009
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Gender influence on left ventricular (LV) remodeling associated to aortic valve stenosis (AS) has been long recognized, but underlying myocardial gene expression patterns have not been explored. We studied whether sex differences in echocardiographic LV anatomy and function in AS patients are associated with specific changes in myocardial mRNA expression of remodeling proteins. AS (n=39) and control (n=23)patients were assessed echocardiographically, and LV myocardial mRNA levels were quantified by PCR. AS patients exhibit increased wall thicknesses and LV mass index (LVMI), but only men show chamber dilation.Collagens and fibronectin mRNA levels increased correlatively to transforming growth factor-beta1 (TGF-beta1). In AS women, collagen I upregulation was proportionally higher than other extracellular matrix (ECM)components. No changes in matrix metalloproteinase-2 and tissue inhibitor of metalloproteinase-2 were detected. Gene expressions of sarcomeric proteins (beta-myosin heavy chain and myosin light chain-2) and TGF-beta1 were directly correlated with each other. Myosin light chain-2 mRNA levels increased proportionally to the transvalvular gradient, but women did so in a greater extent than men for a given gradient. In women, the hypertrophic growth response, reflected by LVMI, was proportional to the expression of genes encoding sarcomeric proteins and TGF-beta1. In men, chamber dilation and deterioration of LVEF was proportional to collagens, fibronectin, and TGF-beta1 gene expression levels. We evidenced gender biased gene expression patterns of the intracellular TGF-beta pathways involving the Smad branch, but not the TAK-1 branch, that could contribute to the remodeling differences observed in AS men and women. Based on these findings, a gender specific therapeutic approach of pressure overload LV hypertrophy could be justified.
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Nuclear imaging of molecular processes in cancer.
Target Oncol
PUBLISHED: 06-21-2009
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Molecular imaging using radionuclides has brought about the possibility to image a wide range of molecular processes using radiotracers injected into the body at very low concentrations that should not perturb the processes being studied. Examples include specific peptide receptor expression, angiogenesis, multi drug resistance, hypoxia, glucose metabolism, and many others. This article presents an overview, aimed at the non-specialist in imaging, of the radionuclide imaging technologies positron emission tomography and single photon radionuclide imaging, and some of the molecules labeled with gamma- and positron-emitting radioisotopes that have been, or are being, developed for research and clinical applications in cancer.
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Characterization and clinical evaluation of a novel IMRT quality assurance system.
J Appl Clin Med Phys
PUBLISHED: 05-22-2009
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Intensity-modulated radiation therapy (IMRT) is a complex procedure that involves the delivery of complex intensity patterns from various gantry angles. Due to the complexity of the treatment plans, the standard-of-care is to perform measurement based patient-specific quality assurance (QA). IMRT QA is traditionally done with film for relative dose in a plane and an ion chamber for absolute dose. This is a laborious and time-consuming process. In this work, we characterized, commissioned, and evaluated the QA capabilities of a novel commercial IMRT device Delta4, (Scandidos, Uppsala, Sweden). This device consists of diode matrices in 2 orthogonal planes inserted in a cylindrical acrylic phantom that is 22 cm in diameter. Although the system has detectors in only 2 planes, it provides a novel interpolation algorithm that is capable of estimating doses at points where no detectors are present. Each diode is sampled per beam pulse so that the dose distribution can be evaluated on segment-by-segment, beam-by-beam, or as a composite plan from a single set of measurements. The end user can calibrate the system to perform absolute dosimetry eliminating the need for additional ion chamber measurements. The patients IMRT plan is imported into the device over the hospital LAN and the results of measurements can be displayed as gamma profiles, distance-to-agreement maps, dose difference maps, or the measured dose distribution can be superimposed of the patients anatomy to display an as-delivered plan. We evaluated the systems reproducibility, stability, pulse-rate dependence, dose-rate dependence, angular dependence, linearity of dose response and energy response using carefully planned measurements. We also validated the systems interpolation algorithm by measuring a complex dose distribution from an IMRT treatment. Several simple and complex isodose distributions planned using a treatment planning system were delivered to the QA device; the planned and measured dose distributions were then compared and analyzed. In addition, the dose distributions measured by conventional IMRT QA, which uses an ion chamber and film, were compared. We found that this device is accurate and reproducible and that its interpolation algorithm is valid. In addition the supplied software and network interface allow a streamlined IMRT QA process.
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An artificial di-iron oxo-protein with phenol oxidase activity.
Nat. Chem. Biol.
PUBLISHED: 05-12-2009
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Here we report the de novo design and NMR structure of a four-helical bundle di-iron protein with phenol oxidase activity. The introduction of the cofactor-binding and phenol-binding sites required the incorporation of residues that were detrimental to the free energy of folding of the protein. Sufficient stability was, however, obtained by optimizing the sequence of a loop distant from the active site.
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Could the deep squat jump predict weightlifting performance?
J Strength Cond Res
PUBLISHED: 04-24-2009
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This research was carried out with the aim of describing the deep squat jump (DSJ) and comparing it with the squat (SJ) and countermovement (CMJ) jumps, to introduce it as a strength testing tool in the monitoring and control of training in strength and power sports. Forty-eight male subjects (21 weightlifters, 12 triathletes, and 15 physical education students) performed 3 trials of DSJ, SJ, and CMJ with a 1-minute rest among them. For the weightlifters, snatch and clean and jerk results during the Spanish Championship 2004 and the 35th EU Championships 2007 were collected to study the relationship among vertical jumps and weightlifters performance. A 1-way analysis of variance (ANOVA) showed significant differences between groups in the vertical jumps, with the highest jumps for the weightlifters and the lowest for the triathletes. An ANOVA for repeated measures (type of jump) showed better results for DSJ and CMJ than SJ in all groups. A linear regression analysis was performed to determine the association between weightlifting and vertical jump performances. Correlations among the weightlifting performance and the vertical jumps were also calculated and determined using Pearson r. Results have shown that both CMJ and DSJ are strongly correlated with weightlifting ability. Therefore, both measures can be useful for coaches as a strength testing tool in the monitoring and control of training in weightlifting.
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Clinical course and predictors of death in prosthetic valve endocarditis over a 20-year period.
J. Thorac. Cardiovasc. Surg.
PUBLISHED: 02-17-2009
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To compare early and late outcome of patients with prosthetic valve endocarditis treated medically versus surgically and to determine predictors of in-hospital death. We retrospectively reviewed patients clinical records, including laboratory findings, surgery, and pathologic files, in an acute-care, 1200-bed teaching hospital.
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Virtual histology intravascular ultrasound assessment of cardiac allograft vasculopathy from 1 to 20 years after heart transplantation.
J. Heart Lung Transplant.
PUBLISHED: 02-10-2009
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Cardiac allograft vasculopathy (CAV) is the main cause of graft loss and death in heart transplant (HTx) recipients surviving >1 year. There is a dual etiology for coronary disease in HTx: classic atherosclerosis and an immunologically mediated disease. Intravascular ultrasound (IVUS) is highly sensitive for CAV detection; however, gray-scale IVUS is of limited value for identification of specific plaque components. We sought to characterize graft coronary artery disease by means of IVUS-virtual histology (IVUS-VH) at different time-points of follow-up and to correlate plaque composition with clinical factors.
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Biotechnological advances in neuro-electro-stimulation for the treatment of hyposalivation and xerostomia.
Med Oral Patol Oral Cir Bucal
PUBLISHED: 01-31-2009
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Treatment of xerostomia is a common clinical challenge in the oral medicine practice. Although some treatments have been used to improve the symptoms of xerostomia, none is completely satisfactory for the patients who suffer of this alteration. In the last years non-pharmacological treatments based on electro-stimulation for the treatment of xerostomia have been developed. This review is aimed at presenting new developments for the treatment of xerostomia, applying neuro-electro-stimulation by miniaturized intra-oral electro-stimulators. These devices increase salivary secretion and improve symptoms of oral dryness. Their effect is obtained by means of stimulation of the lingual nerve, in whose proximity the electrodes of the apparatus are placed. The objective of this mechanism is both to directly stimulate the salivary glands controlled by that nerve and to enhance the salivary reflex. Clinical studies have been carried out that have demonstrated the wetting effect of the method described in this article.
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Branched-chain 2-oxoacid transamination increases GABA-shunt metabolism and insulin secretion in isolated islets.
Biochem. J.
PUBLISHED: 01-29-2009
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We have previously shown that oxo-4-methylpentanoate promotes islet GABA (gamma-aminobutyric acid) metabolism and stimulates insulin secretion. The main aim of this work was to explore the participation of the transamination of branched-chain 2-oxoacids in these processes with the aid of several inhibitors of this enzyme activity. No correlation was found between the transamination of branched-chain 2-oxoacids in islet homogenates and insulin secretion. However, in vivo transamination rates correlated better with the secretion capacity of the different branched-chain 2-oxoacids. Gabapentin, a specific inhibitor of the cytosolic isoenzyme, showed greater potential to decrease the in vitro transamination rates of oxo-3-methylbutyrate and oxo-3-methylpentanoate than those of oxo-4-methylpentanoate and oxohexanoate; this correlated with its capacity to decrease insulin secretion. 4-Methylvaleric acid very strongly inhibited the transamination of all the branched-chain 2-oxoacids and blocked their capacity to decrease islet GABA and to stimulate insulin secretion. KCl at 70 mM at stimulated islet GABA release, subsequently decreasing its tissue concentration. This non-metabolic decrease of GABA suppressed the second phase of insulin secretion triggered by oxo-4-methylpentanoate and oxohexanoate. Oxo-4-methylpentanoate and oxo-3-methylpentanoate suppressed dose-dependent 2-oxoglutarate dehydrogenase activity in islet homogenates. In conclusion, the transamination of branchedchain 2-oxoacids is more important to the stimulation of insulin secretion than their catabolism, and transamination decreases islet GABA concentrations by promoting GABA metabolism. Also, inhibition of 2-oxoglutarate dehydrogenase by branched-chain 2-oxoacids may increase metabolic flux in the GABA-shunt at the expense of reduced tricarboxylic acid cycle flux.
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Asymmetrically substituted benzene-1,3,5-tricarboxamides: self-assembly and odd-even effects in the solid state and in dilute solution.
Chemistry
PUBLISHED: 01-15-2009
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Molecular organization: Chiral benzene tricarboxamides with methyl substituents at defined positions self-assemble into supramolecular polymers of preferred helicity by three-fold alpha-helical-type hydrogen bonding. The odd-even effect is operative and all derivatives are liquid crystalline showing a Col(ho) phase (see figure).Asymmetric benzene-1,3,5-tricarboxamides (aBTAs) comprising two n-octyl and one chiral methyl-alkyl side chain were synthesised and characterised. The influence of the position and the configuration of the chiral methyl group (methyl at the alpha, beta or gamma position) in the aliphatic side chains on the liquid-crystalline properties and the aggregation behaviour of the aBTAs was systematically studied and compared to symmetrical benzene-1,3,5-tricarboxamides (sBTAs). Solid-state characterisation (polarised optical microscopy, IR spectroscopy, X-ray diffraction and differential scanning calorimetry) revealed that all aBTAs show threefold, alpha-helical-type intermolecular hydrogen bonding between neighbouring molecules and exhibit a columnar hexagonal organisation from room temperature to well above 200 degrees C. Moving the chiral methyl group closer to the amide group stabilises the liquid-crystalline state, as evidenced by a higher clearing temperature and corresponding enthalpy. The self-assembly of dilute solutions of the aBTAs in methylcyclohexane ( approximately 10(-5) mol L(-1)) was investigated with circular dichroism (CD) spectroscopy. The sign of the Cotton effect demonstrated a pronounced odd-even effect, whereas the value of the molar ellipticity, Deltaepsilon, in the aBTAs was independent of the position of the methyl group. Subsequent temperature-dependent CD measurements showed that the aggregation of all aBTAs can quantitatively be described by the nucleation-growth model and that the stability of the aggregates increases when the chiral methyl group is closer to the amide moiety. The results presented herein illustrate that even small changes in the molecular structure of substituted benzene-1,3,5-tri-carboxamides affect their solid-state properties and their self-assembly behaviour in dilute solutions.
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HIF2? acts as an mTORC1 activator through the amino acid carrier SLC7A5.
Mol. Cell
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The mammalian target of rapamycin (mTOR) pathway, which is essential for cell proliferation, is repressed in certain cell types in hypoxia. However, hypoxia-inducible factor 2? (HIF2?) can act as a proliferation-promoting factor in some biological settings. This paradoxical situation led us to study whether HIF2? has a specific effect on mTORC1 regulation. Here we show that activation of the HIF2? pathway increases mTORC1 activity by upregulating expression of the amino acid carrier SLC7A5. At the molecular level we also show that HIF2? binds to the Slc7a5 proximal promoter. Our findings identify a link between the oxygen-sensing HIF2? pathway and mTORC1 regulation, revealing the molecular basis of the tumor-promoting properties of HIF2? in von Hippel-Lindau-deficient cells. We also describe relevant physiological scenarios, including those that occur in liver and lung tissue, wherein HIF2? or low-oxygen tension drive mTORC1 activity and SLC7A5 expression.
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Dithiocarbamate complexes as radiopharmaceuticals for medical imaging.
Mini Rev Med Chem
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Over the past 30 years dithiocarbamate ligands have found application in radiopharmaceutical metal-ligand complexes to image a range of disease states. The vast majority of research and applications, and the widest range of complex structures, have involved radionuclides of technetium and rhenium. Considering the extent of coordination chemistry of dithiocarbamate ligands described elsewhere in this issue, the extent of radiopharmaceutical application with metallic radionuclides is surprisingly narrow. Here we summarise the types of radiopharmaceutical complexes studied and the uses, and potential uses, to which they have been put in nuclear medicine.
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Myocardial and circulating levels of microRNA-21 reflect left ventricular fibrosis in aortic stenosis patients.
Int. J. Cardiol.
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Various human cardiovascular pathophysiological conditions associate aberrant expression of microRNAs (miRNAs) and circulating miRNAs are emerging as promising biomarkers. In mice, myocardial miR-21 overexpression is related to cardiac fibrosis elicited by pressure overload. This study was designed to determine the role of myocardial and plasmatic miR-21 in the maladaptive remodeling of the extracellular matrix induced by pressure overload in aortic stenosis (AS) patients and the clinical value of miR-21 as a biomarker for pathological myocardial fibrosis.
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Delineation of glutamate pathways and secretory responses in pancreatic islets with ?-cell-specific abrogation of the glutamate dehydrogenase.
Mol. Biol. Cell
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In pancreatic ?-cells, glutamate dehydrogenase (GDH) modulates insulin secretion, although its function regarding specific secretagogues is unclear. This study investigated the role of GDH using a ?-cell-specific GDH knockout mouse model, called ?Glud1(-/-). The absence of GDH in islets isolated from ?Glud1(-/-) mice resulted in abrogation of insulin release evoked by glutamine combined with 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid or l-leucine. Reintroduction of GDH in ?Glud1(-/-) islets fully restored the secretory response. Regarding glucose stimulation, insulin secretion in islets isolated from ?Glud1(-/-) mice exhibited half of the response measured in control islets. The amplifying pathway, tested at stimulatory glucose concentrations in the presence of KCl and diazoxide, was markedly inhibited in ?Glud1(-/-) islets. On glucose stimulation, net synthesis of glutamate from ?-ketoglutarate was impaired in GDH-deficient islets. Accordingly, glucose-induced elevation of glutamate levels observed in control islets was absent in ?Glud1(-/-) islets. Parallel biochemical pathways, namely alanine and aspartate aminotransferases, could not compensate for the lack of GDH. However, the secretory response to glucose was fully restored by the provision of cellular glutamate when ?Glud1(-/-) islets were exposed to dimethyl glutamate. This shows that permissive levels of glutamate are required for the full development of glucose-stimulated insulin secretion and that GDH plays an indispensable role in this process.
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Intraoral electrostimulator for xerostomia relief: a long-term, multicenter, open-label, uncontrolled, clinical trial.
Oral Surg Oral Med Oral Pathol Oral Radiol
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A previous sham-controlled multinational study demonstrated the short-term efficacy and safety for xerostomia treatment of an intraoral device that delivers electrostimulation to the lingual nerve. The objective of this study was to test the hypothesis that those beneficial effects would be sustained over an 11-month period.
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Helical self-assembly and co-assembly of fluorinated, preorganized discotics.
Org. Biomol. Chem.
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The synthesis and self-assembly properties of a fluorinated C(3)-symmetrical 3,3-bis(acylamino)-2,2-bipyridine discotic (1) in the mesophase and in solution are described. First, 3,4,5-tris-(1H,1H,2H,2H,3H,3H-perfluoroundecyl-1-oxy)benzoyl chloride was coupled to mono-t-BOC protected 2,2-bipyridine-3,3-diamine to afford after deprotection the corresponding fluorinated aromatic amine on a multigram scale. Then, three-fold reaction of this amine with trimesyl chloride yielded the target C(3)-symmetrical fluorinated disc. The latter displayed columnar liquid crystallinity over a temperature range of more than 350 K in which helical rectangular and hexagonal columnar mesophases were detected by X-ray diffraction measurements. (1)H-NMR spectroscopy showed a preorganized structure due to strong intramolecular hydrogen bonding between the amide N-Hs and bipyridine nitrogen atoms, even in the presence of a large excess of hexafluoroisopropanol. This preorganized structure allows the formation of helical self-assemblies in fluorinated solvents, as was established using UV-Vis spectroscopy. The fluorinated disc and two chiral hydrocarbon analogues (a C(3)-symmetrical and a desymmetrized disc) were mixed in a 1:10 v:v mixture of methoxynonafluorobutane (MNFB) and 1,1,2-trichloro-1,2,2-trifluoroethane (Freon 113). Importantly, the C(3)-symmetrical hydrocarbon disc dissolves only in the presence of fluorinated disc in the latter solvent mixture, proving a mutual interaction. CD spectroscopy performed on these mixtures points to a preference for alternating self-assemblies of fluorinated and chiral hydrocarbon discotics.
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Local contextual processing of abstract and meaningful real-life images in professional athletes.
Exp Brain Res
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We investigated the effect of abstract versus real-life meaningful images from sports on local contextual processing in two groups of professional athletes. Local context was defined as the occurrence of a short predictive series of stimuli occurring before delivery of a target event. EEG was recorded in 10 professional basketball players and 9 professional athletes of individual sports during three sessions. In each session, a different set of visual stimuli were presented: triangles facing left, up, right, or down; four images of a basketball player throwing a ball; four images of a baseball player pitching a baseball. Stimuli consisted of 15 % targets and 85 % of equal numbers of three types of standards. Recording blocks consisted of targets preceded by randomized sequences of standards and by sequences including a predictive sequence signaling the occurrence of a subsequent target event. Subjects pressed a button in response to targets. In all three sessions, reaction times and peak P3b latencies were shorter for predicted targets compared with random targets, the last most informative stimulus of the predictive sequence induced a robust P3b, and N2 amplitude was larger for random targets compared with predicted targets. P3b and N2 peak amplitudes were larger in the professional basketball group in comparison with professional athletes of individual sports, across the three sessions. The findings of this study suggest that local contextual information is processed similarly for abstract and for meaningful images and that professional basketball players seem to allocate more attentional resources in the processing of these visual stimuli.
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Nephrectomy as a cause of chronic kidney disease in the treatment of urolithiasis: a case-control study.
World J Urol
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To analyze the clinical course of nephrectomized patients due to complications related to nephrolithiasis and ascertain the prevalence of chronic kidney disease (CKD) in this population.
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