Quantization of Midisuperspace Models

We give a comprehensive review of the quantization of midisuperspace models. Though the main focus of the paper is on quantum aspects, we also provide an introduction to several classical points related to the definition of these models. We cover some important issues, in particular, the use of the principle of symmetric criticality as a very useful tool to obtain the required Hamiltonian formulations. Two main types of reductions are discussed: those involving metrics with two Killing vector fields and spherically symmetric models. We also review the more general models obtained by coupling matter fields to these systems. Throughout the paper we give separate discussions for standard quantizations using geometrodynamical variables and those relying on loop quantum gravity inspired methods.Comment: To appear in Living Review in Relativit

Ca2+ Extrusion by NCX Is Compromised in Olfactory Sensory Neurons of OMP−/− Mice

The role of olfactory marker protein (OMP), a hallmark of mature olfactory sensory neurons (OSNs), has been poorly understood since its discovery. The electrophysiological and behavioral phenotypes of OMP knockout mice indicated that OMP influences olfactory signal transduction. However, the mechanism by which this occurs remained unknown.We used intact olfactory epithelium obtained from WT and OMP(-/-) mice to monitor the Ca(2+) dynamics induced by the activation of cyclic nucleotide-gated channels, voltage-operated Ca(2+) channels, or Ca(2+) stores in single dendritic knobs of OSNs. Our data suggested that OMP could act to modulate the Ca(2+)-homeostasis in these neurons by influencing the activity of the plasma membrane Na(+)/Ca(2+)-exchanger (NCX). Immunohistochemistry verifies colocalization of NCX1 and OMP in the cilia and knobs of OSNs. To test the role of NCX activity, we compared the kinetics of Ca(2+) elevation by stimulating the reverse mode of NCX in both WT and OMP(-/-) mice. The resulting Ca(2+) responses indicate that OMP facilitates NCX activity and allows rapid Ca(2+) extrusion from OSN knobs. To address the mechanism by which OMP influences NCX activity in OSNs we studied protein-peptide interactions in real-time using surface plasmon resonance technology. We demonstrate the direct interaction of the XIP regulatory-peptide of NCX with calmodulin (CaM).Since CaM also binds to the Bex protein, an interacting protein partner of OMP, these observations strongly suggest that OMP can influence CaM efficacy and thus alters NCX activity by a series of protein-protein interactions

Synthetic biology to access and expand nature's chemical diversity

Bacterial genomes encode the biosynthetic potential to produce hundreds of thousands of complex molecules with diverse applications, from medicine to agriculture and materials. Accessing these natural products promises to reinvigorate drug discovery pipelines and provide novel routes to synthesize complex chemicals. The pathways leading to the production of these molecules often comprise dozens of genes spanning large areas of the genome and are controlled by complex regulatory networks with some of the most interesting molecules being produced by non-model organisms. In this Review, we discuss how advances in synthetic biology — including novel DNA construction technologies, the use of genetic parts for the precise control of expression and for synthetic regulatory circuits — and multiplexed genome engineering can be used to optimize the design and synthesis of pathways that produce natural products

The cholecystokinin receptor antagonist devazepide enhances morphine-induced analgesia but not morphine-induced respiratory depression in the squirrel monkey.

The effects of the cholecystokinin antagonist devazepide on analgesia and respiratory depression induced by morphine in squirrel monkeys were examined. Pain thresholds were determined using the tail withdrawal procedure, in which monkeys restrained in chairs kept their tails in cool (35 degrees C) water for at least 20 sec, but withdrew them from warm (55 degrees C) water in less than 4 sec. Morphine produced a dose-related increase in tail withdrawal latencies from warm water. Devazepide (injected i.p. or p.o.) had no effect on tail withdrawal latencies when given alone but enhanced the analgesic effects of morphine. The devazepide dose-response curve for morphine enhancement was bell-shaped with doses of 3, 10, 30 and 100 micrograms/kg injected i.p. increasing morphine analgesia whereas higher and lower dose did not. In a separate group of monkeys, morphine produced dose-dependent decreases in respiratory rate and oxygen tension and increases in carbon dioxide tension. In contrast to its effects on morphine analgesia, devazepide had no effect on the various indices of morphine-induced respiratory depression. These data suggest that devazepide may have therapeutic utility as an adjuvant to morphine analgesia allowing lower dose of the opiate to be used to relieve pain and reducing the risk of opiate-induced respiratory depression

Strain differences in angiotensin-converting enzyme and angiotensin II type I receptor expression. Possible implications for experimental chronic renal transplant failure

Background The Fisher to Lewis (F-L) model of renal transplantation (Rtx) is widely used. Rtx from F to L without immunosuppressive treatment results in 50% survival, whereas L to F results in survival rates similar to syngrafts. When treated with an angiotensin-converting enzyme (ACE) inhibitor or antihypertensive triple therapy, renal damage is markedly reduced in F-L allografts. Despite similar reductions in blood pressure, the ACE inhibitor (ACE-I) is more effective than antihypertensive triple therapy, suggesting that the inhibition of intrarenal ACE plays an additional role in the attenuation of renal damage. Methods In the present study, we investigated strain-related differences in intrarenal ACE activity between F and L rats and whether treatment with ACE-I in F-L allografted rats results in reduction of intrarenal ACE. Intrarenal ACE was measured by activity assays, immunohistochemistry and PCR. Results In control kidneys from healthy F rats (n=8), we found a four-fold higher ACE activity than in native L rats (n=8, p Conclusion In conclusion, intrarenal levels of ACE may play a role in the development of renal damage in experimental chronic renal transplant failure