An Ayurvedic Review on Therapeutic Potentials of Manahshila (Realgar): A Literature Review

Manahshila (Realgar) is used only in purified & detoxified condition for the therapeutic purposes as internal as well as external medicine. Manahshila have significant therapeutic values which have been mentioned in Brihatrayi and Bhaishajya Ratnavali. Most of the formulation of Manahshila is used for external application whereas fine powders of these processed minerals are used for both in external and internal application. Certain Dhuma Yoga also contain Manahshila are advised in respiratory tract diseases. Shuddha Manahshila has been described in various Rasa Yoga preparations, such as Shvasakuthara Rasa, Rajamriganka Rasa, Trailokyachintamani Rasa, Shilasindura, and Samirapannaga Rasa, Moreover, there are references for the use of Manahshila in Kustha, Swasa, Kasa Roga but this arsenical drug has not been used so far independently as a single drug

Receptor crosstalk improves concentration sensing of multiple ligands

Cells need to reliably sense external ligand concentrations to achieve various biological functions such as chemotaxis or signaling. The molecular recognition of ligands by surface receptors is degenerate in many systems leading to crosstalk between different receptors. Crosstalk is often thought of as a deviation from optimal specific recognition, as the binding of non-cognate ligands can interfere with the detection of the receptor's cognate ligand, possibly leading to a false triggering of a downstream signaling pathway. Here we quantify the optimal precision of sensing the concentrations of multiple ligands by a collection of promiscuous receptors. We demonstrate that crosstalk can improve precision in concentration sensing and discrimination tasks. To achieve superior precision, the additional information about ligand concentrations contained in short binding events of the non-cognate ligand should be exploited. We present a proofreading scheme to realize an approximate estimation of multiple ligand concentrations that reaches a precision close to the derived optimal bounds. Our results help rationalize the observed ubiquity of receptor crosstalk in molecular sensing

Interplay of strong and weak hydrogen bonding in molecular complexes of some 4,4'-disubstituted biphenyls with urea, thiourea and water

The crystal chemistry and engineering of a new family of host-guest complexes is described. 4,4'-Dicyanobiphenyl (DCBP) forms a 1:1 complex, 1 with urea wherein the DCBP host forms large hexagonal channels via C-H···N hydrogen bonds and the urea guest molecules are arranged in N-H···O ribbons which fit completely within the host channels. By analogy, 4,4'-bipyridine N,N'-dioxide (BPNO) was selected as a molecule that can form a corresponding C-H…O based channel. BPNO forms complexes with urea (2), thiourea (3) and water (4). Structures 2 and 3 provide some points of comparison with the structure of 1 but are not fully equivalent to it. In structure 4, the smaller guest water is able to fit neatly within the smaller hexagonal channel of BPNO and in this sense, the degree of structural predictability is satisfactory. To obtain another structure similar to that of 1, 4,4'-dinitrobiphenyl (DNBP) was identified as an alternative host compound. This choice was justified by the structure of its 1:1 complex, 5 with urea. In all cases, the guest molecules interact with each other via strong hydrogen bonds and form an essential template for the weak hydrogen bonded assembly of the host network structure but the latter is still of some significance. One finds consequently, in complexes 1-5, a constructive interplay of strong and weak hydrogen bonds

Molecular networks in the crystal structures of tetrakis(4-iodophenyl)methane and (4-iodophenyl)triphenylmethane

The crystal structure of tetrakis(4-iodophenyl)methane is analysed in terms of molecular networks wherein the tetraphenylmethane moieties and I4 synthons are considered as molecular and supramolecular nodes. This I4 cluster plays the same role in generating molecular networks as does the Br4 cluster in the isomorphous tetrakis(4-bromophenyl)methane derivative. (4-Iodophenyl)triphenylmethane crystallises in a lower symmetry space group but features an unusual I···Ph interaction. In this series of halo-substituted tetraphenylmethanes the molecules exhibit similar columnar packing in the solid state, accounting for their crystallisation in non-centrosymmetric space groups

Excitable Dynamics in the Presence of Time Delay

The spiking properties of a subcritical Hopf oscillator with a time delayed nonlinear feedback is investigated. Finite time delay is found to significantly affect both the statistics and the fine structure of the spiking behavior. These dynamical changes are explained in terms of the fundamental modifications occurring in the bifurcation scenario of the system. Our mathematical model can find useful applications in understanding the dynamical behaviour of various real life excitable systems where propagation delay effects are ubiquitous.Comment: 10 pages including 7 figure