Cooperative effect of heparan sulfate and laminin mimetic peptide nanofibers on the promotion of neurite outgrowth

Cataloged from PDF version of article.Extracellular matrix contains an abundant variety of signals that are received by cell surface receptors contributing to cell fate, via regulation of cellular activities such as proliferation, migration and differentiation. Cues from extracellular matrix can be used for the development of materials to direct cells into their desired fate. Neural extracellular matrix (ECM) is rich in axonal growth inducer proteins, and by mimicking these permissive elements in the cellular environment, neural differentiation as well as neurite outgrowth can be induced. In this paper, we used a synthetic peptide nanofiber system that can mimic not only the activity of laminin, an axonal growth-promoting constituent of the neural ECM, but also the activity of heparan sulfate proteoglycans in order to induce neuritogenesis. Heparan sulfate mimetic groups that were utilized in our system have an affinity to growth factors and induce the neuroregenerative effect of laminin mimetic peptide nanofibers. The self-assembled peptide nanofibers with heparan sulfate mimetic and laminin-derived epitopes significantly promoted neurite outgrowth by PC-12 cells. In addition, these scaffolds were even effective in the presence of chondroitin sulfate proteoglycans (CSPGs), which are the major inhibitory components of the central nervous system. In the presence of these nanofibers, cells could overcome CSPG inhibitory effect and extend neurites on peptide nanofiber scaffolds. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

Growth Factor Binding on Heparin Mimetic Peptide Nanofibers

Cataloged from PDF version of article.Immobilization of growth factors in scaffolds is important for controlling their dose and bioactivity for regenerative medicine applications. Although numerous covalent and noncovalent immobilization strategies have been proposed, better growth factor loading and dose control inside the scaffold is necessary. Nature of the binding site on the growth factor interacting with scaffold is critical for preserving and achieving maximal growth factor functionality, which has been a relatively less emphasized issue in previous studies. We recently reported heparin mimetic peptide nanofibers, which mimic chemistry of heparan sulfates. Heparin mimetic nanofibers were shown to bind to vascular endothelial growth factor (VEGF) and direct endothelial cells to angiogenesis. Here, we further investigated interactions between heparin mimetic peptide nanofibers and growth factors. We tested bioactivity of the nanofiber bound growth factors in order to understand the potential use of these peptide nanofiber scaffolds as analogues of heparan sulfates. We observed that heparin mimetic peptide nanofibers demonstrate better binding profiles to VEGF, hepatocyte growth factor (HGF), and fibroblast growth factor-2 (FGF-2) than control peptide nanofibers. We also identified that the heparin-binding domain of VEGF is critical for its interaction with these nanofibers. However, the heparin-binding site is not indispensable for binding of all growth factors to nanofibers. We also showed that binding of growth factors to nanofibers does not cause any loss in bioactivity through in vitro cell culture assays with PC-12 cells. These results reveal that heparin mimetic peptide nanofibers can effectively mimic heparan sulfates in extracellular matrix and provide an optimal milieu for spatial presentation of important growth factors. These properties make peptide nanofiber scaffolds promising materials for regenerative medicine applications through efficient and precisely controlled growth factor delivery. © 2012 American Chemical Society

Effective Methods of using of the Water Resources of Mountain Rivers with high turbidity

The article focuses on the solution methods of the problems arising from the rational use of the water resources of mountain rivers with high turbidity.Technical and operational indicators of water reservoirs constructed on mountain rivers characterised by high turbidity have been analysed and measures preventing stagnation of water reservoirs have been investigated.Issues related to the construction of a water reservoir outside the river bed and the prevention of stagnation of this water reservoir were investigated. The option of building a water receiving reservoir providing partial regulation and limpidity of the flow in the river valley was proposed. Hydraulic washing installation was proposed to remove sediments from the water reservoir equipped with the water tank. The working principle of washing installation with hydro-technical and hydraulic parameters are listed

Characterization of ancient ceramic shreds: Insights into firing conditions and manufacturing technology

Four ancient ceramic shreds from the archaeological site Leletepe in the Fizuli region of the Republic of Azerbaijan and two local raw ceramic pastes were characterized by powder X-ray diffraction (PXRD) and thermal analysis (TG-DTG) techniques. XRD analysis of ceramic sherds reveals that all investigated samples contain similar minerals: quartz, feldspar, and clay. Three samples out of four contain calcite. Based on the traditional approach, it has been assumed that the firing process in these samples stopped before 700 °C. The mass loss ratios of samples of ancient ceramics also indicate that reversible dehydroxylation took place in all four samples, thus indicating the initial mild firing conditions. The summary of all the applied methods indicates that the ceramic samples were made using a similar manufacturing technology. According to XRD analysis, samples N1 and N4 contain diopside, and samples N2 and N3 contain maghemite, indicating the different origins of the ceramic shreds. Analysis of the raw ceramic mass also did not reveal the presence of these minerals, which may indicate a discrepancy between the origin of ancient ceramic sherds and modern ones

Heparin Mimetic Peptide Nanofibers Promote Angiogenesis

Cataloged from PDF version of article.New blood vessel formation (angiogenesis) is one of the most important processes required for functional tissue formation. Induction of angiogenesis is usually triggered by growth factors released by cells. Glycosaminoglycans (e.g., heparan sulphates) in the extracellular matrix aid in proper functioning of these growth factors. Therefore, exogeneous heparin or growth factors were required for promoting angiogenesis in previous regenerative medicine studies. Here we report for the first time induction of angiogenesis by a synthetic nanofibrous peptide scaffold without the addition of any exogenous growth factors or heparin. We designed and synthesized a self-assembling peptide amphiphile molecule that is functionalized with biologically active groups to mimic heparin. Like heparin, this molecule has the ability to interact with growth factors and effectively enhance their bioactivity. The nanofibers formed by these molecules were shown to form a 3D network mimicking the structural proteins in the extracellular matrix. Because of heparin mimicking capabilities of the peptide nanofibers, angiogenesis was induced without the addition of exogenous growth factors in vitro. Bioactive interactions between the nanofibers and the growth factors enabled robust vascularization in vivo as well. Heparin mimetic peptide nanofibers presented here provide new opportunities for angiogenesis and tissue regeneration by avoiding the use of heparin and exogenous growth factors. The synthetic peptide nanofiber scaffolds enriched with proper chemical functional groups shown in this study can be used to induce various desired physiological responses for tissue regeneration. © 2011 American Chemical Society

Traumatic upper cervical esophageal perforation in childhood with door handle

Cervical esophageal rupture due to trauma in childhood is an extremely rare entity associated with a high rate of morbidity and mortality if misdiagnosed. There is still no consensus on the assessment and elective management of children with trauma and esophageal rupture. Surgical primary repair is usually not feasible in patients with delayed diagnosis, especially if the period extends over 48 h. We report a case of an 8-year-old boy who suffered a posterior oropharyngeal and cervical esophageal perforation after accidental intraoral penetration of a door handle. Primary repair was avoided because of late presentation of the patient. In nearly 1½ months, the perforation resolved completely without surgical intervention to the primary site.Keywords: childhood, esophageal perforation, traum

Self-induced penetrating rectal perforation by foreign body: an unusual event in childhood

Traumatic rectal perforation is a very rare and dangerous emergency in childhood. We present a case of rectal perforation due to self-induced transanal impalement.Keywords: children, foreign body, rectal perforatio

Tenascin-C Mimetic Peptide Nanofibers Direct Stem Cell Differentiation to Osteogenic Lineage

Cataloged from PDF version of article.Extracellular matrix contains various signals for cell surface receptors that regulate cell fate through modulation of cellular activities such as proliferation and differentiation. Cues from extracellular matrix components can be used for development of new materials to control the stem cell fate. In this study, we achieved control of stem cell fate toward osteogenic commitment by using a single extracellular matrix element despite the contradictory effect of mechanical stiffness. For this purpose, we mimicked bone extracellular matrix by incorporating functional sequence of fibronectin type III domain from native tenascin-C on self-assembled peptide nanofibers. When rat mesenchymal stem cells (rMSCs) were cultured on these peptide nanofibers, alkaline phosphatase (ALP) activity and alizarin red staining indicated osteogenic differentiation even in the absence of osteogenic supplements. Moreover, expression levels of osteogenic marker genes were significantly enhanced revealed by quantitative real-time polymerase chain reaction (qRT-PCR), which showed the remarkable bioactive role of this nanofiber system on osteogenic differentiation. Overall, these results showed that tenascin-C mimetic peptides significantly enhanced the attachment, proliferation, and osteogenic differentiation of rMSCs even in the absence of any external bioactive factors and regardless of the suitable stiff mechanical properties normally required for osteogenic differentiation. Thus, these peptide nanofibers provide a promising new platform for bone regeneratio

Electrostatic effects on nanofiber formation of self-assembling peptide amphiphiles

Cataloged from PDF version of article.Self-assembling peptide amphiphile molecules have been of interest to various tissue engineering studies. These molecules self-assemble into nanofibers which organize into three-dimensional networks to form hydrocolloid systems mimicking the extracellular matrix. The formation of nanofibers is affected by the electrostatic interactions among the peptides. In this work, we studied the effect of charged groups on the peptides on nanofiber formation. The self-assembly process was studied by pH and zeta potential measurements, FT-IR, circular dichroism, rheology, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. The aggregation of the peptides was triggered upon neutralization of the charged residues by pH change or addition of electrolyte or biomacromolecules. Understanding the controlled formation of the hydrocolloid gels composed of peptide amphiphile nanofibers can lead us to develop in situ gel forming bioactive collagen mimetic nanofibers for various tissue engineering studies including bioactive surface coatings. (C) 2010 Elsevier Inc. All rights reserved

Study of the Anthropogenic Impact on the Change of Geoecological Conditions of the Khojahasan Lake, Azerbaijan

The  paper  considers  the  results  of  geoecological  and  geophysical  studies  conducted   in   the   Khojahasan Lake basin in the Western part of Baku. The main purpose of the work was to study the anthropogenic impact on geoecological conditions of the lake. To assess the development of exogenous geological processes in the coastal zone of the lake and their impact on the environment, geophysical studies were carried out by the vertical electric sounding (VES). From 1990 to 2014, the physical and chemical characteristics of water and sediments were studied in a representative section of the lake. Metal concentrations, including such toxic elements as Cu, Zn, Cd, Sr, Ba, Pb, Cr, and Ni, were determined in the trace element composition of bottom sediments. It was revealed that since the mid-XIX century and especially since the second half of the XX century the high rate of population growth and urbanization in the territory of the Absheron Peninsula (in the Republic of Azerbaijan the name Apsheron was changed to Absheron) led to intensive use of natural resources and increased anthropogenic load on the environment. Technogenesis actively violates the natural cycle of matter and energy in lakes (limnogenesis), along with other natu- ral media, as lake basins are located in lowlands and often accumulate industrial, municipal, agricultural, and other discharges. Pollutants accumulated in the lake basin affect hydrobiochemical conditions, transform quantitative and qualitative indicators of the aquatic environment and bottom sediments. Factors affecting the lake landscape are ge- netically different, unequal in the degree and nature of the impact, as well as induration