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Effects of Cell Seeding Methods on Chondrogenic Differentiation of Rat Mesenchymal Stem Cells in Polyhydroxybutyrate/Chitosan Scaffolds

Abstract

The aim of our study was to examine the effects of passive and active cell seeding techniques on in vitro chondrogenic differentiation of mesenchymal stem cells (MSC) isolated from rat bone marrow and seeded on porous biopolymer scaffolds based on polyhydroxybutyrate/chitosan (PCH) blends. This paper is focused on the distribution of the cells on and in the scaffolds, since it influences the uniformity of the created extracellular matrix (ECM), as well as the homogenity of the distribution of chondrogenic markers in vitro which ultimately affects the quality of the newly created tissue after in vivo implantation. The three types of cell-scaffold constructs were examined by: fluorescence microscopy, SEM, histology and quantitative analysis of the glycosaminoglycans after chondrogenic cultivation. The results demonstrated that the active cells seeded via the centrifugation of the cell suspension onto the scaffold guaranteed an even distribution of cells on the bulk of the scaffold and the uniform secretion of the ECM products by the differentiated cells.

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Extracellular matrix in tumours as a source of additional neoplastic lesions - a review

Abstract

The review describes the role of cells of extracellular matrix (ECM) as a source of neoplastic outgrowths additional to the original tumour. The cells undergo a spontaneous transformation or stimulation by the original tumour through intercellular signals, e.g. through Shh protein (sonic hedgehog). Additionally, cells of an inflammatory infiltrate, which frequently accompany malignant tumours and particularly carcinomas, may regulate tumour cell behaviour. This is either by restricting tumour proliferation or, inversely, by induction and stimulation of the proliferation of another tumour cell type, e.g. mesenchymal cells. The latter type of tumour may involve formation of histologically differentiated stromal tumours (GIST), which probably originate from interstitial cells of Cajal in the alimentary tract. Occasionally, e.g. in gastric carcinoma, proliferation involves lymphoid follicles and lymphocytes of GALT (gut-associated lymphoid tissue), which gives rise to lymphoma. The process is preceded by the earlier stage of intestinal metaplasia, or is induced by gastritis alone. This is an example of primary involvement of inflammatory infiltrate cells in neoplastic progression. Despite the numerous histogenetic classifications of tumours (zygotoma benignum et zygotoma malignum, or mesenchymomata maligna et mesenchymomata benigna), currently in oncological diagnosis the view prevails that the direction of tumour differentiation and its degree of histologic malignancy (grading) are more important factors than the histogenesis of the tumour.

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The Upshot of Money Supply and Inflation in Nigeria

Abstract

This study empirically investigates the upshot of money supply on inflation in Nigeria using annual time series data spanning from 1970 to 2016. Co-integration and Autoregressive Dynamic Error Correction Model (ADLECM) approach was utilized. The results showed that money supply does not considerably influence inflation both in the long and short run possibly because the country is in recession. The ECM has the correct sign of negative and it is significant meaning that about 21% of the errors are corrected yearly. The Granger causality outcome demonstrates that, there is no causality between money supply and inflation in Nigeria within the study period and vice-versa. The implication of this is often that there are different economic conditions which are key determinant of inflation in Nigeria. The study recommends that the government should diversify the economy, minimize importation by encouraging local production of products and services. The CBN should guarantee an exchange rate policy that is essentially determined by the state of the economy and not by speculators being a net importation economy. Also, the CBN should look inwards into the current interest rate and see how it can be regulated in such a way that will encourage private and foreign investors to be able to invest in the country. This in turn, successively increases income, infrastructure development and economic growth at large.

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Nanofibers and their biomedical use

, Nanofiber alignment and direction of mechanical strain affect the ECM production of human ACL fibroblast, Biomaterials 26 (2005) 1261-1270; DOI: 10.1016/j.biomaterials. 2004.04.037. 35. M. Cegnar, S. Baumgartner and J. Kristl, Vla_na oskrba rane s sodobnimi oblogami, Med. Razgl. 46 (2007) 235-247. 36. P. Zahedi, I. Rezaeian, S. O. Ranaei-Siadat, S. H. Jafari and P. Supaphol, A review on wound dressings with an emphasis on electrospunnanofibrous polymeric bandages, Polym. Adv. Technol. 21 (2010) 77-95; DOI: 10.1002/pat.1625

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The Effect of Electrochemical Machining on the Fatigue Strength of Heat Resistance Alloys

References Landolt, D. (2009). The role of surface films in ECM. Proceedings of the International Symposium on ElectroChemical Machining Technology INSECT 2009, Dresden. Sedykin, F.N. (1976). Electrochemical machining of machine Components , (in Russian). Moscow: Mashinostrojenije. Rumyantsev, E. & Davydov, A. (1989). Electrochemical machining of Metals. Moscow: MIR Publisher. Shmanilov, V.A., Filimoshin, V.G., Karimov, A. Ch., Petrov, B.I., & Pronichev

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The Debt Overhang Hypothesis: Evidence from Pakistan

Abstract

This study investigates the debt overhang hypothesis for Pakistan in the period 1960-2007. The study examines empirically the dynamic behaviour of GDP, debt services, the employed labour force and investment using the time series concepts of unit roots, cointegration, error correlation and causality. Our findings suggest that debt-servicing has a negative impact on the productivity of both labour and capital, and that in turn has adversely affected economic growth. By severely constraining the ability of the country to service debt, this lends support to the debt-overhang hypothesis in Pakistan. The long run relation between debt services and economic growth implies that future increases in output will drain away in form of high debt service payments to lender country as external debt acts like a tax on output. More specifically, foreign creditors will benefit more from the rise in productivity than will domestic producers and labour. This suggests that domestic labour and capital are the ultimate losers from this heavy debt burden.

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Quasi-Homogenous Model of Electrochemical Machining of Turbine Engine Parts

, Scientific Library of Institute of Aviation, No. 56, Warsaw 2019. [5] Kozak, J., Surface Shaping by Electrochemical Machining , Transaction of Warsaw University of Technology, Warsaw 1976. [6] Kozak, J., Computer Simulation System for Electrochemical Shaping , Journal of Materials Processing Technology, Vol. 109, No. 3, pp. 354-359, 2001. [7] Kozak, J., Lubkowski, K., The Basic Investigation of Characteristic in the Pulse ECM , Proceed. 20 th M.T.D.R. Int. Conf., pp. 625-630, Birmingham 1979. [8] Kozak, J., Rajurkar, K. P., Wei, B., Modelling

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Electrochemical reduction of azo dyes mimicking their biotransformation to more toxic products

aim of this study was to investigate the reduction products of selected azo dyes using the technique of electrochemistry with mass spectrometry (EC–MS). Afterwards, a comparison was made with data available in literature and software for predicting metabolic pathways. Particular attention was paid to the harmful aromatic amine reduction EC products. Based on these results an analytical method using liquid chromatography combined with tandem mass spectrometry (LC–MS/MS) was developed as a tool for the confirmation of the identified products obtained by

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The Impact of Exchange Rate Volatility on Turkish Exports: 1993-2009

The Impact of Exchange Rate Volatility on Turkish Exports: 1993-2009

This paper attempts to investigate the long-run and short-run relationships between Turkish exports, exchange rate volatility, foreign income, and relative prices by employing quarterly data for the period 1993Q3-2009Q4. Towards this purpose, multivariate cointegration and error correction model (ECM) techniques are used in this study. The long-run estimation results suggest that foreign income and real exchange rate volatility exert positive and statistically significant impacts on Turkish exports, while relative prices affect Turkish exports negatively and significantly. In addition, the results of the ECM model indicate that relative prices have a negative and significant effect, foreign income has an insignificant effect, and nominal exchange rate volatility has a positive and significant effect on Turkish exports.

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Paxillus involutus Forms an Ectomycorrhizal Symbiosis and Enhances Survival of PtCOMT-modified Betula pendula in vitro

Abstract

The ability of the PtCOMT (caffeate/5-hydroxyferulate O-methyltransferase from Populus tremuloides L.) - modified Betula pendula Roth. lines to form symbiosis with an ectomycorrhizal (ECM) fungus Paxillus involutus Batsch Fr. was studied in vitro. Lignin precursor gene PtCOMT was introduced into two B. pendula clones under the control of the cauliflower mosaic virus 35S promoter or the promoter of the sunflower polyubiquitin gene UbB1. Of the four transgenic lines, one 35SPtCOMT line (23) had a decreased syringyl/guaiacyl (S/G) ratio of root lignin, and two UbB1-PtCOMT lines (110 and 130) retarded root growth compared to the control clone. Both control clones and all transgenic lines were able to form ECMs with P. involutus, but the transgenic lines differed from the controls in the characteristics of the ECMs. The number of lateral roots covered with fungal hyphae and/or development of a Hartig net (HN) were reduced in line 23 with a decreased S/G ratio, and in lines 110 and 130 with slower root formation and changed root morphology, respectively. However, line 23 benefited more from the inoculation in lateral root formation than the control, and in lines 110 and 130 the percentage of viable plants increased most due to inoculation. The results show that B. pendula plants genetically transformed with the lignin gene PtCOMT could form mycorrhizal symbiosis regardless of changes in either the root S/G ratio or development. The benefits of the symbiosis were variable even in the closed in vitro system, and dependent on the clone or transgenic line and the ECM fungal symbiont.

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