43 research outputs found
Effect of Phytopreparations Based on Bioreactor-Grown Cell Biomass of Dioscorea Deltoidea, Tribulus Terrestris and Panax Japonicus on Carbohydrate and Lipid Metabolism in Type 2 Diabetes Mellitus
In the present study, we explored the therapeutic potential of bioreactor-grown cell cultures of the medicinal plant species Dioscorea deltoidea, Tribulus terrestris and Panax japonicus to treat carbohydrate metabolism disorders (CMDs) in laboratory rats. In the adrenaline model of hyperglycemia, aqueous suspensions of cell biomass pre-administered at a dose of 100 mg dry biomass/kg significantly reduced glucose level in animal blood 1–2.5 h (D. deltoidea and T. terrestris) or 1 h (P. japonicus) after adrenaline hydrochloride administration. In a streptozotocin-induced model of type 2 diabetes mellitus, the cell biomass of D. deltoidea and T. terrestris acted towards normalization of carbohydrate and lipid metabolism, as evidenced by a significant reduction of daily diuresis (by 39– 57%), blood-glucose level (by 46–51%), blood content in urine (by 78–80%) and total cholesterol (25– 36%) compared to animals without treatment. Bioactive secondary metabolites identified in the cell cultures and potentially responsible for their actions were deltoside, 25(S)-protodioscin and protodioscin in D. deltoidea; furostanol-type steroidal glycosides and quinic acid derivatives in T. terrestris; and ginsenosides and malonyl-ginsenosides in P. japonicus. These results evidenced for high potential of bioreactor-grown cell suspensions of these species for prevention and treatment of CMD, which requires further investigation. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This.Funding: Bioreactor cultivation of plant cell suspensions and their biochemical analysis were financially supported by the Ministry of Science and Higher Education of Russian Federation through Megagrant project no. 075-15-2019-1882 and performed by using the equipment of the large-scale research facilities “Experimental biotechnological facility” and “All-Russian Collection of cell cultures of higher plants” of the IPPRAS (EBF IPPRAS and ARCCC HP IPPRAS). Hypoglycemic activity evaluation of the cell biomass was performed with the financial support of the Russian Science Foundation project no. 19-14-00387. The results of the hypoglycemic activity evaluation were obtained by using the equipment of the Center for Collective Use “Analytical Center of the Federal State Budgetary Educational Institution of Higher Education Saint Petersburg State Chemical Pharmaceutical University (SPCPU) of the Ministry of Health of Russia”, equipped with the financial support of the Ministry of Education and Science of Russia
A review of Monte Carlo simulations of polymers with PERM
In this review, we describe applications of the pruned-enriched Rosenbluth
method (PERM), a sequential Monte Carlo algorithm with resampling, to various
problems in polymer physics. PERM produces samples according to any given
prescribed weight distribution, by growing configurations step by step with
controlled bias, and correcting "bad" configurations by "population control".
The latter is implemented, in contrast to other population based algorithms
like e.g. genetic algorithms, by depth-first recursion which avoids storing all
members of the population at the same time in computer memory. The problems we
discuss all concern single polymers (with one exception), but under various
conditions: Homopolymers in good solvents and at the point, semi-stiff
polymers, polymers in confining geometries, stretched polymers undergoing a
forced globule-linear transition, star polymers, bottle brushes, lattice
animals as a model for randomly branched polymers, DNA melting, and finally --
as the only system at low temperatures, lattice heteropolymers as simple models
for protein folding. PERM is for some of these problems the method of choice,
but it can also fail. We discuss how to recognize when a result is reliable,
and we discuss also some types of bias that can be crucial in guiding the
growth into the right directions.Comment: 29 pages, 26 figures, to be published in J. Stat. Phys. (2011
Forced-induced desorption of a polymer chain adsorbed on an attractive surface - Theory and Computer Experiment
We consider the properties of a self-avoiding polymer chain, adsorbed on a
solid attractive substrate which is attached with one end to a pulling force.
The conformational properties of such chain and its phase behavior are treated
within a Grand Canonical Ensemble (GCE) approach. We derive theoretical
expressions for the mean size of loops, trains, and tails of an adsorbed chain
under pulling as well as values for the universal exponents which describe
their probability distribution functions. A central result of the theoretical
analysis is the derivation of an expression for the crossover exponent ,
characterizing polymer adsorption at criticality, , which
relates the precise value of to the exponent , describing
polymer loop statistics. We demonstrate that , depending on the possibility of a single loop to interact with
neighboring loops in the adsorbed polymer. The universal surface loop exponent
and the Flory exponent .
We present the adsorption-desorption phase diagram of a polymer chain under
pulling and demonstrate that the relevant phase transformation becomes first
order whereas in the absence of external force it is known to be a continuous
one. The nature of this transformation turns to be dichotomic, i.e.,
coexistence of different phase states is not possible. These novel theoretical
predictions are verified by means of extensive Monte Carlo simulations.Comment: 24 pages, 14 figure