Yilmaz Yildiz

Periostin is temporally expressed as an extracellular matrix component in skeletal muscle regeneration and differentiation

The transcriptional events and pathways responsible for the acquisition of the myogenic phenotype during regeneration and myogenesis have been studied extensively. The modulators that shape the extracellular matrix in health and disease, however, are less understood. Understanding the components and pathways of this remodeling will aid the restoration of the architecture and prevent deterioration under pathological conditions such as fibrosis. Periostin, a matricellular protein associated with remodeling of the extracellular matrix and connective tissue architecture, is emerging in pathological conditions associated with fibrosis in adult life. Periostin also complicates fibrosis in degenerative skeletal muscle conditions such as dystrophies. This study primarily addresses the spatial and temporal involvement of periostin along skeletal muscle regeneration. In the acute skeletal muscle injury model that shows recovery without fibrosis, we show that periostin is rapidly disrupted along with the extensive necrosis and periostin mRNA is transiently upregulated during the myotube maturation. This expression is stringently initiated from the newly regenerating fibers. However, this observation is contrasting to a model that displays extensive fibrosis where upregulation of periostin expression is stable and confined to the fibrotic compartments of endomysial and perimysial space. In vitro myoblast differentiation further supports the claim that upregulation of periostin expression is a function of extracellular matrix remodeling during myofiber differentiation and maturation. We further seek to identify the expression kinetics of various periostin isoforms during the differentiation of rat and mouse myoblasts. Results depict that a singular periostin isoform dominated the rat muscle, contrasting to multiple isoforms in C2C12 myoblast cells. This study shows that periostin, a mediator with deleterious impact on conditions exhibiting fibrosis, is also produced and secreted by myoblasts and regenerating myofibers during architectural remodeling in the course of development and regeneration.

Partial hydatidiform mole in a phenylketonuria patient treated with sapropterin dihydrochloride.

Abstract Strict control of hyperphenylalaninemia is necessary in pregnant women with phenylketonuria (PKU) in order to prevent phenylalanine embryopathy in the fetus, characterized by intrauterine growth restriction, dysmorphic facies, congenital heart disease, microcephaly and intellectual disability, collectively known as maternal PKU syndrome. Sapropterin dihydrochloride (SD), an alternative or adjunct to dietary therapy in patients with tetrahydrobiopterin (BH4)-responsive PKU, has recently been used in several cases to treat PKU during pregnancy with satisfactory results. Here, we report two pregnancies treated with SD and unrestricted diet in a patient with BH4-responsive mild PKU. The first pregnancy resulted in a partial hydatidiform mole and was terminated, whereas a healthy infant was born from the second pregnancy. Phenylalanine control was optimal in both pregnancies. To the best of our knowledge, this is the first report on the development of partial hydatidiform mole associated with SD treatment and the second report on molar pregnancy in PKU. While the relation between SD and molar pregnancy is unknown, further studies may be needed to investigate the possible effects of SD on fertilization.

Post-mortem detection of FLAD1 mutations in 2 Turkish siblings with hypotonia in early infancy

Inherited defects of vitamin B2 (riboflavin) metabolism may cause different phenotypes with common biochemical markers of multiple acyl-CoA dehydrogenase deficiency (MADD). Most recently, mutations in FLAD1, which encodes flavin adenine dinucleotide (FAD) synthase, has been implicated in MADD with combined respiratory chain deficiency in nine patients. Here, we describe two siblings with FAD synthase deficiency, who were diagnosed post-mortem upon suspicion of this newly-described disease. Hypotonia was evident at two months of age in both infants, followed by feeding difficulties, respiratory distress and death in six months despite partial response to riboflavin. The older sibling had documented lipid storage myopathy and biochemical markers of MADD. Our observations support the previous reports of unexpected riboflavin-responsiveness in frameshift mutations in the second exon of FLAD1 and suggest dysmorphic auricular helix and hypospadias as possible additional clinical features. More reports and studies are needed to better describe and treat FAD synthase deficiency.

Momentum or market? Determinants of large stock price changes in an emerging market

ABSTRACT The aim of this study is to investigate the determinants of large price changes in Turkey. We also provide additional evidence on determinants of large price changes in different macroeconomic environments, specifically on the pre-crisis and post-crisis periods. Using recurrent event analysis with stratified observations and frailty effects, our findings suggest that momentum has a significant impact on large price changes during both pre-crisis and post-crisis periods. However, the impact of market is more significant on the estimation of large price declines in the pre-crisis period and of large price increases in the post-crisis period. Additional findings suggest that liquidity and market-to-book ratio have positive, firm size has a negative impact on likelihood of large price changes regardless of the direction of the stock price change and macroeconomic environment. Findings of this study provide new insights into the understanding of large price changes in an emerging market.

Aracı Kurum Tavsiyelerinin Hisse Senedi Fiyatı Üzerindeki Etkisi: Türkiye Örneği

Calismanin amaci, hisse senetleri Borsa Istanbul’da islem goren sirketlere yonelik araci kurumlarin yaptigi tavsiyelerin hisse senedi fiyati uzerindeki etkisini incelemektir.Mevcut calismanin hedeflerinden biri de soz konusu etki uzerinden piyasanin yari guclu formda etkin olup olmadigini ortaya koymaktir. Olay calismasi yontemi kullanilarak yapilan analizde kisa vadede araci kurumlarin hisse alim satimi ile ilgili tavsiyeleri ile hisse senedi fiyatlari arasinda anlamli bir iliskinin oldugu, olay sonrasi kisa vadede hisse senetlerinden anormal getiri elde edilebilecegi tespit edilmistir. Duyuru sonrasi kisa vadede anormal getirilerin varligi ve hisse senedi fiyatlarinda duyurudan sonraki 15 gunluk sure zarfinda herhangi bir geri donus yasanmamasi piyasanin yari guclu formda etkin olmadigini gostermektedir.

Effect of brand value announcements on stock returns: empirical evidence from Turkey

AbstractThis study examines the effects of brand value announcements on stock returns of Turkish firms by using the event study methodology and long-term risk adjusted port-folio returns. We examined the stock-price impacts of 299 brand value announcements on the stock market performance of the firms within the years of 2010–2014 by using BrandFinance Turkey’s 100 ranking list as a data source. The findings indicate that the companies listed in the Turkey Top 100 Brands list earn positive abnormal returns 7 months after the announcement. Similarly, the companies which had greater brand values relative to the previous year, experienced significant positive abnormal returns in the 7-months period. Additional findings suggest that investors are able to beat the market in the long run regarding risk-adjusted returns by consistently investing in the Top Brands. Overall, the study demonstrates new evidence to the marketing-finance interface by focusing on the Turkish case as an important emerging market.