Arachidonic Acid as a Possible Negative Feedback Inhibitor of Nicotinic Acetylcholine Receptors on Neurons

Neuronal acetylcholine receptors, being highly permeable to calcium, are likely to regulate calcium-dependent events in neurons. Arachidonic acid is a membrane-permeant second messenger that can be released from membrane phospholipids by phospholipases in a calcium-dependent manner. We show here that activation of neuronal acetylcholine receptors triggers release of 3H-arachidonic acid in a calcium-dependent manner from neurons preloaded with the fatty acid. Moreover, low concentrations of arachidonic acid reversibly inhibit the receptors and act most efficiently on receptors likely to have the highest permeability to calcium, namely receptors containing α7 subunits. Low concentrations of arachidonic acid also reversibly inhibit α7- containing receptors expressed in Xenopus oocytes following injection of α7 cRNA. The oocyte results indicate following injection of α7 cRNA. The oocyte results indicate that the inhibition is a feature of the receptors rather than a consequence of neuron-specific machinery. The inhibition is not mediated by specific metabolites of arachidonic acid because the effects can be mimicked by other fatty acids; their effectiveness correlates with their content of double bonds. In contrast to arachidonic effects on calcium currents, inhibition of neuronal nicotinic receptors by the fatty acid cannot be prevented by blocking production of free radicals or by inhibiting protein kinase C. An alternative mechanism is that arachidonic acid binds directly to the receptors or perturbs the local environment in such a manner as to constrain receptor function

Multichannel coupling with supersymmetric quantum mechanics and exactly-solvable model for Feshbach resonance

A new type of supersymmetric transformations of the coupled-channel radial Schroedinger equation is introduced, which do not conserve the vanishing behavior of solutions at the origin. Contrary to usual transformations, these ``non-conservative'' transformations allow, in the presence of thresholds, the construction of potentials with coupled scattering matrices from uncoupled potentials. As an example, an exactly-solvable potential matrix is obtained which provides a very simple model of Feshbach-resonance phenomenon.Comment: 10 pages, 2 figure

The potential link between corporate innovations and corporate competitiveness:Evidence from IT firms in the UK

Purpose: The purpose of this paper is to provide a thorough empirical investigation of the potential link between corporate innovations and corporate competitiveness in the context of the UK IT industry. Design/methodology/approach: This research uses a panel of 216 UK IT firms for the period from 2000 to 2016. The sample data for this study were extracted from the Worldscope, extracted from the Datastream database from Thomson Reuters. For the analysis of the data, the generalised method of moments model is applied. Findings: The results of this study provide empirical evidence that there exists a strong, positive link between corporate innovations and corporate competitiveness. Such evidence further reinforces the common view in the current literature of strategic management that because of the nature of their business, firms in the IT industry need to enhance their innovative capacities on a continual basis because of their critical role on these firms’ success and survival. Also, it is found that when the proxies for corporate innovations are lagged by two periods, their impact on corporate competitiveness becomes relatively more significant. However, when they are further lagged, i.e. by three periods, such an impact turns out to be relatively less pronounced. Research limitations/implications: The data gathered for this paper was restricted to IT-oriented firms in the UK. Using a secondary database (Datastream), the paper considered the period of 2000-2016. Originality/value: The research makes a significant contribution to the current debate on the relationship between information technology, innovation and performance, referred to in the literature as the productivity paradox, by studying the problem in the IT industry. It supports organisations from the sector in their efforts to deal with the dynamic nature of technological innovations and of the context where they operate. Methodologically, the way the study has measured the concepts of innovation and performance and the lessons learned from their analysis has also brought value to the research

Supersymmetry in quantum mechanics: An extended view

The concept of supersymmetry in a quantum mechanical system is extended, permitting the recognition of many more supersymmetric systems, including very familiar ones such as the free particle. Its spectrum is shown to be supersymmetric, with space-time symmetries used for the explicit construction. No fermionic or Grassmann variables need to be invoked. Our construction extends supersymmetry to continuous spectra. Most notably, while the free particle in one dimension has generally been regarded as having a doubly degenerate continuum throughout, the construction clarifies taht there is a single zero energy state at the base of the spectrum.Comment: 4 pages, 4 figure

Toward a Spin- and Parity-Independent Nucleon-Nucleon Potential

A supersymmetric inversion method is applied to the singlet $^1S_0$ and $^1P_1$ neutron-proton elastic phase shifts. The resulting central potential has a one-pion-exchange (OPE) long-range behavior and a parity-independent short-range part; it fits inverted data well. Adding a regularized OPE tensor term also allows the reproduction of the triplet $^3P_0$, $^3P_1$ and $^3S_1$ phase shifts as well as of the deuteron binding energy. The potential is thus also spin-independent (except for the OPE part) and contains no spin-orbit term. These important simplifications of the neutron-proton interaction are shown to be possible only if the potential possesses Pauli forbidden bound states, as proposed in the Moscow nucleon-nucleon model.Comment: 9 pages, RevTeX, 5 ps figure

Single Dose Pharmacokinetics of Efavirenzin Healthy Indian Subjects

Background & Objective: Access to antiretroviral therapy in India is improving. Efavirenz (EFV) is a commonly used non-nucleoside reverse transcriptase inhibitor used to treat HIV infection. No information is available on the pharmacokinetics of EFV in Indian subjects. The aim of this study was to obtain information on single dose pharmacokinetics of efavirenz (EFV) in healthy Indian subjects. Methods: Sixteen adult healthy volunteers (8 males and 8 females) were administered a single oral tablet of 600 mg EFV after an overnight fast. Blood samples were collected at 1, 2, 3, 4, 5, 6, 10, 24 and 48 hours post dosing. Plasma EFV concentrations were estimated by HPLC, and certain pharmacokinetic variables were calculated. Results: Plasma EFV concentrations were higher in females than males at all the time points, the differences being significant at 1 (p<0.001) and 2 (p=0.05) hours. Females had significantly higher peak concentration (Cmax) of EFV than males (p=0.05) (3.11 & 1.90 μg/ml). The inter-individual variability in Cmax and AUC0-48 were 42 and 45% respectively. Conclusions: This study provides basic information on the pharmacokinetics of EFV in Indian subjects. Females had higher peak levels of EFV than males. Inter-subject variability was high. Further studies are necessary to describe the pharmacokinetic profile of EFV under steady state conditions in Indian patients on antiretroviral treatment

The influence of the cluster environment on the large-scale radio continuum emission of 8 Virgo cluster spirals

The influence of the environment on the polarized and total power radio continuum emission of cluster spiral galaxies is investigated. We present deep scaled array VLA 20 and 6 cm observations including polarization of 8 Virgo spiral galaxies. These data are combined with existing optical, HI, and Halpha data. Ram pressure compression leads to sharp edges of the total power distribution at one side of the galactic disk. These edges coincide with HI edges. In edge-on galaxies the extraplanar radio emission can extend further than the HI emission. In the same galaxies asymmetric gradients in the degree of polarization give additional information on the ram pressure wind direction. The local total power emission is not sensitive to the effects of ram pressure. The radio continuum spectrum might flatten in the compressed region only for very strong ram pressure. This implies that neither the local star formation rate nor the turbulent small-scale magnetic field are significantly affected by ram pressure. Ram pressure compression occurs mainly on large scales (>=1 kpc) and is primarily detectable in polarized radio continuum emission.Comment: 16 pages, 10 figures, accepted for publication in A&

Shape-invariant quantum Hamiltonian with position-dependent effective mass through second order supersymmetry

Second order supersymmetric approach is taken to the system describing motion of a quantum particle in a potential endowed with position-dependent effective mass. It is shown that the intertwining relations between second order partner Hamiltonians may be exploited to obtain a simple shape-invariant condition. Indeed a novel relation between potential and mass functions is derived, which leads to a class of exactly solvable model. As an illustration of our procedure, two examples are given for which one obtains whole spectra algebraically. Both shape-invariant potentials exhibit harmonic-oscillator-like or singular-oscillator-like spectra depending on the values of the shape-invariant parameter.Comment: 16 pages, 5 figs; Present e-mail of AG: [email protected]