Expression of VE-cadherin in zebrafish embryos: a new tool to evaluate vascular development.

We have identified the zebrafish homologue of VE-cadherin and documented its expression in the developing vascular system. The zebrafish VE-cadherin gene is specifically expressed in the vascular endothelial cell lineage beginning with the differentiation and migration of angioblasts and persists throughout vasculogenesis, angiogenesis, and endocardium development. Staining zebrafish embryos by whole-mount in situ hybridization with the VE-cadherin probe provides a method to screen embryos for vascular defects. To illustrate this utility, we used VE-cadherin expression to demonstrate a conservation of vascular endothelial growth factor-A (VEGF-A) function. The morpholino antisense oligonucleotide knockdown of VEGF-A function in zebrafish embryos results in a loss of angiogenic blood vessels, as indicated by the lack of VE-cadherin expression in the intersegmental vasculature. This loss can be restored in embryos supplemented with either zebrafish or human VEGF-A, the latter indicating that genes crucial to angiogenesis have highly conserved functional activities in vertebrates.     

Spinal plasticity mediated by postsynaptic L-type Ca channels

In the spinal cord, motoneurons and specific subgroups of interneurons express L-type Ca²⁺ channels. As elsewhere, these dihydropyridine-sensitive channels mediate a slowly activating inward current in response to depolarisation and show little or no inactivation. The slow kinetics for activation and deactivation provide voltage-sensitive properties in a time range from hundreds of milliseconds to tens of seconds and lead to plateau potentials, bistability and wind-up in neurons in both sensory and motor networks. This slow dynamics is in part due to facilitation of L-type Ca²⁺ channels by depolarisation. The voltage sensitivity of L-type Ca²⁺ channels is also regulated by a range of metabotropic transmitter receptors. Up-regulation is mediated by receptors for glutamate, acetylcholine, noradrenaline and serotonin in motoneurons and by receptors for glutamate and substance P in plateau-generating dorsal horn interneurons. In both cell types, L-type Ca²⁺ channels are down-regulated by activation of GABA_B receptors. In this way, metabotropic regulation in cells expressing L-type Ca²⁺ channels provides mechanisms for flexible adjustment of excitability and of the contribution of plateau currents to the intrinsic properties. This type of regulation also steers the magnitude and compartmental distribution of Ca²⁺ influx during depolarisation, thus providing a signal for local synaptic plasticity.     

CXCR7 (RDC1) promotes breast and lung tumor growth in vivo and is expressed on tumor-associated vasculature

Chemokines and chemokine receptors have been posited to have important roles in several common malignancies, including breast and lung cancer. Here, we demonstrate that CXCR7 (RDC1, CCX-CKR2), recently deorphanized as a chemokine receptor that binds chemokines CXCL11 and CXCL12, can regulate these two common malignancies. Using a combination of overexpression and RNA interference, we establish that CXCR7 promotes growth of tumors formed from breast and lung cancer cells and enhances experimental lung metastases in immunodeficient as well as immunocompetent mouse models of cancer. These effects did not depend on expression of the related receptor CXCR4. Furthermore, immunohistochemistry of primary human tumor tissue demonstrates extensive CXCR7 expression in human breast and lung cancers, where it is highly expressed on a majority of tumor-associated blood vessels and malignant cells but not expressed on normal vasculature. In addition, a critical role for CXCR7 in vascular formation and angiogenesis during development is demonstrated by using morpholino-mediated knockdown of CXCR7 in zebrafish. Taken together, these data suggest that CXCR7 has key functions in promoting tumor development and progression.     

Combination of a Beta Adrenoceptor Modulator and a Norepinephrine-Serotonin Uptake Inhibitor for the Treatment of Obesity

{"type":"entrez-nucleotide","attrs":{"text":"LY377604","term_id":"1257744234","term_text":"LY377604"}}LY377604), a human β₃-adrenergic receptor agonist and β₁- and β₂-adrenergic receptor antagonist with no sympathomimetic activity at the β₁- and β₂-adrenergic receptors, is reported. Some in vivo data in both rats and humans is presented.     

An M-like outward current regulates the excitability of spinal motoneurones in the adult turtle

The excitatory action of muscarine on spinal motoneurones was investigated with intracellular recordings in a slice preparation from adult turtles. In these cells muscarine is known to facilitate a persistent inward current mediated by L-type Ca²⁺ channels. When this effect was blocked by nifedipine, muscarine still increased the excitability. In voltage clamp, a slowly activating outward current, generated during depolarizing voltage commands and deactivating as a tail current on return to the holding voltage, was reduced by muscarine. This outward current was activated when the voltage was stepped to potentials positive to −60 mV, was voltage sensitive and had a deactivation time constant of ≈80 ms. These findings are compatible with an M-current. This possibility was also supported by the finding that the current was reduced by XE-991 - a selective blocker of the KCNQ potassium channels underlying M-currents in other cell types. Our findings suggest that an M-like current, mediated by a KCNQ channel, contributes to the intrinsic response properties of motoneurones in the adult spinal cord by increasing adaptation of repetitive firing and decreasing the slope of the frequency-current relation.     

5-HT1A receptors increase excitability of spinal motoneurons by inhibiting a TASK-1-like K+ current in the adult turtle

The modulatory effects of serotonin mediated by 5-HT_1A receptors in adult spinal motoneurons were investigated by intracellular recordings in a slice preparation from the turtle. In current-clamp mode, activation of 5-HT_1A receptors by 8-OH-DPAT led to depolarization and an increase in input resistance in most motoneurons but caused hyperpolarization and a decrease in input resistance in the remaining smaller fraction of cells. When slices were preincubated in medium containing the 5-HT_1A receptor antagonist WAY-100635, 8-OH-DPAT had no effect. In voltage-clamp mode, with 1 m m CsCl in the bathing medium, 8-OH-DPAT consistently inhibited a leak current that was sensitive to extracellular acidification and anandamide, a TASK-1 channel blocker. In medium with a low pH, as in the presence of anandamide, 8-OH-DPAT had no effect. Our results show that activation of 5-HT_1A receptors contributes to the excitatory effect of serotonin on spinal motoneurons by inhibition of a TASK-1 potassium channel leading to depolarization and increased input resistance.     

The zebrafish as a novel system for functional genomics and therapeutic development applications

Unconventional antisense technology has entered the mainstream for both therapeutic and functional genomics applications in a variety of biological settings. Further development of this approach has been hampered by the high cost and limited information obtained with standard bioassays and animal models. The embryo of the zebrafish Danio rerio offers both biologists and technologists a new strategy that rapidly garners efficacy, toxicity and specificity data in an in vivo setting. This system has been used to optimize current antisense targeting methods, and it provides an ideal initial assay system for the development of new chemistries or other new gene targeting approaches.     

Femtosecond Laser-Ablated Copper Surface as a Substrate for a MoS2-Based Hydrogen Evolution Reaction Electrocatalyst

One of the methods to improve the performance of a heterogeneous electrocatalyst is the dispersion of a catalytic material on a suitable substrate. In this study, femtosecond laser ablation was used to prepare very rough but also ordered copper surfaces consisting of vertical, parallel ridges. Then, a molybdenum sulfide coating was electrochemically deposited onto these surfaces. It was observed by profilometry that the average roughness of the surface after coating with MoS₂ had decreased, but the developed surface area still remained significantly larger than the projected surface area. The electrodes were then used as an electrocatalyst for the hydrogen evolution reaction in acidic media. These were highly efficient, reaching 10 mA cm⁻² of HER current at a −181 mV overpotential and a Tafel slope of ~39 mV dec⁻¹. Additionally, scanning electrochemical microscopy was used to observe whether hydrogen evolution would preferentially occur in certain spots, for example, on the peaks, but the obtained results suggest that the entire surface is active. Finally, the electrochemical impedance spectroscopy data showed the difference in the double-layer capacitance between the ablated and non-ablated surfaces (up to five times larger) as well as the parameters that describe the improved catalytic activity of fs-Cu/MoS₂ electrodes.     

Inhibition of motoneurons during the cutaneous silent period in the spinal cord of the turtle

The transient suppression of motor activity in the spinal cord after a cutaneous stimulus is termed the cutaneous silent period (CSP). It is not known if CSP is due to suppression of the premotor network or direct inhibition of motoneurons. This issue was examined by intracellular recordings from motoneurons in the isolated carapace-spinal cord preparation from adult turtles during rhythmic scratch-like reflex. Electrical stimulation of cutaneous nerves induced CSP-like suppression of motor nerve firing during rhythmic network activity. The stimulus that generated the CSP-like suppression of motor activity evokes a polysynaptic compound synaptic potential in motoneurons and suppressed their firing. This compound synaptic potential was hyperpolarizing near threshold for action potentials and was associated with a substantial increase in conductance during the CSP in the motor pool. These results show that direct postsynaptic inhibition of motoneurons contributes to the CSP.