An innovative lattice Boltzmann model for simulating Michaelis–Menten-based diffusion–advection kinetics and its application within a cartilage cell bioreactor

Lattice Boltzmann models (LBM) are rapidly showing their ability to simulate a lot of fluid dynamics problems that previously required very complex approaches. This study presents a LBM for simulating diffusion–advection transport of substrate in a 2-D laminar flow. The model considers the substrate influx into a set of active cells placed inside the flow field. A new innovative method was used to simulate the cells activity using the LBM by means of Michaelis–Menten kinetics. The model is validated with some numerical benchmark problems and proved highly accurate results. After validation the model was used to simulate the transport of oxygen substrates that diffuse in water to feed a set of active cartilage cells inside a new designed bioreactor.     

Herbal medicine as an auspicious therapeutic approach for the eradication of Helicobacter pylori infection: A concise review

Helicobacter pylori (H. pylori) causes gastric mucosa inflammation and gastric cancer mostly via several virulence factors. Induction of proinflammatory pathways plays a crucial role in chronic inflammation, gastric carcinoma, and H. pylori pathogenesis. Herbal medicines (HMs) are nontoxic, inexpensive, and mostly anti-inflammatory reminding meticulous emphasis on the elimination of H. pylori and gastric cancer. Several HM has exerted paramount anti-H. pylori traits. In addition, they exert anti-inflammatory effects through several cellular circuits such as inhibition of 5′-adenosine monophosphate-activated protein kinase, nuclear factor-κB, and activator protein-1 pathway activation leading to the inhibition of proinflammatory cytokines (interleukin 1α [IL-1α], IL-1β, IL-6, IL-8, IL-12, interferon γ, and tumor necrosis factor-α) expression. Furthermore, they inhibit nitrous oxide release and COX-2 and iNOS activity. The apoptosis induction in Th1 and Th17-polarized lymphocytes and M2-macrophagic polarization and STAT6 activation has also been exhibited. Thus, their exact consumable amount has not been revealed, and clinical trials are needed to achieve optimal concentration and their pharmacokinetics. In the aspect of bioavailability, solubility, absorption, and metabolism of herbal compounds, nanocarriers such as poly lactideco-glycolide-based loading and related formulations are helpful. Noticeably, combined therapies accompanied by probiotics can also be examined for better clearance of gastric mucosa. In addition, downregulation of inflammatory microRNAs (miRNAs) by HMs and upregulation of those anti-inflammatory miRNAs is proposed to protect the gastric mucosa. Thus there is anticipation that in near future HM-based formulations and proper delivery systems are possibly applicable against gastric cancer or other ailments because of H. pylori.     

Evolution of body condition‐dependent dispersal in metapopulations

Body condition‐dependent dispersal strategies are common in nature. Although it is obvious that environmental constraints may induce a positive relationship between body condition and dispersal, it is not clear whether positive body conditional dispersal strategies may evolve as a strategy in metapopulations. We have developed an individual‐based simulation model to investigate how body condition–dispersal reaction norms evolve in metapopulations that are characterized by different levels of environmental stochasticity and dispersal mortality. In the model, body condition is related to fecundity and determined either by environmental conditions during juvenile development (adult dispersal) or by those experienced by the mother (natal dispersal). Evolutionarily stable reaction norms strongly depend on metapopulation conditions: positive body condition dependency of dispersal evolved in metapopulation conditions with low levels of dispersal mortality and high levels of environmental stochasticity. Negative body condition‐dependent dispersal evolved in metapopulations with high dispersal mortality and low environmental stochasticity. The latter strategy is responsible for higher dispersal rates under kin competition when dispersal decisions are based on body condition reached at the adult life stage. The evolution of both positive and negative body condition‐dependent dispersal strategies is consequently likely in metapopulations and depends on the prevalent environmental conditions.     

Functional constraints on nest characteristics of pebble mounds of breeding male hornyhead chub Nocomis biguttatus

Breeding male hornyhead chub Nocomis biguttatus constructed nests in areas with relatively high but less than maximum flow rate and greater than average water depth. Nests comprised c. 3000 pebbles for a total mass of 11 kg. Males selected pebbles of smaller diameter but higher density than pebbles in the immediate vicinity. Thus, nests balanced the risk of mound erosion and energetic cost of nest construction with the benefits of protection from egg predators and a stable internal flow rate for oxygenation. These data help establish environmental management goals for the conservation of N. biguttatus and the lotic ecosystems dependent upon them.     

Phylogenetic patterns of diversification in a clade of Neotropical frogs (Anura: Aromobatidae: Mannophryne)

We used partial sequences of mitochondrial 16S and cytochrome oxidase I genes to perform a phylogenetic study of collared frogs (Anura: Aromobatidae: Mannophryne ), a genus endemic to Venezuela and the islands of Trinidad and Tobago. We analysed 1.2 kb from 13 of the 15 described species of Mannophryne . Maximum parsimony, maximum likelihood and Bayesian analyses support the monophyly of Mannophryne . Mannophryne consists of three deeply differentiated clades that split from each other in a relatively short period of time. The diversification of Mannophryne occurred well before the glacial-interglacial periods of the Quaternary. Our data support the taxonomic validity of M. olmonae , a species endemic to Tobago Island. Mannophryne olmonae is more closely related to the continental species Mannophryne riveroi than to the Trinidad island endemic Mannophryne trinitatis . As in most tropical clades of frogs, molecular evidence indicates that species richness in Mannophryne is largely underestimated and, consequently, current priorities for conservation are inadequate.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 185–199.     

Nanostructured lipid carriers as semisolid topical delivery formulations for diflucortolone valerate

Context: Topical treatment of skin disease needs to be strategic to ensure high drug concentration in the skin with minimum systemic absorption.

Objective: The aim of this study was to produce semisolid nanostructured lipid carrier (NLC) formulations, for topical delivery of the corticosteroid drug, diflucortolone valerate (DFV), with minimum systemic absorption.

Method: NLC formulations were developed using a high shear homogenization combined with sonication, using Precirol® ATO5 or Tristearin® as the solid lipid, Capryol? or isopropyl myristate as the liquid lipid and Poloxamer® 407 as surfactant. The present study addresses the influence of different formulations composition as solid lipid, liquid lipid types and concentrations on the physicochemical properties and drug release profile from NLCs.

Results and discussion: DFV-loaded NLC formulations possessed average particle size ranging from 160.40?nm to 743.7?nm with narrow polydispersity index. The encapsulation efficiency was improved by adding the lipid-based surfactants (Labrasol® and Labrafil® M1944CS) to reach 68%. The drug release from the investigated NLC formulations showed a prolonged release up to 12?h. The dermatopharmacokinetic study revealed an improvement in drug deposition in the skin with the optimized DFV-loaded NLC formulation, in contrast to a commercial formulation.

Conclusion: NLC provides a promising nanocarrier system that work as reservoir for targeting topical delivery of DFV.