Browsing by Author "Schuler, Gerhard"
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Item Effect of progesterone receptor blockage in late pregnant cows on placental histomorphology and maternal prostaglandin F2 alpha metabolite (PGFM) levels(Wiley, 2010-02) Shenavai, Sima; Dilly, Marc; Pfarrer, Christiane; Kindahl, Hans; Hoffmann, B.; Schuler, Gerhard; Özalp, Rabia Gözde; İntaş, Kamil Seyrek; Çalışkan, Çağlar; Uludağ Üniversitesi/Veterinerlik Fakültesi/Klinik Bilimler Bölümü.; 0000-0003-4694-6937; AAE-3607-2019; AAH-7292-2019Item Investigations into the mechanisms controlling parturition in cattle(Bioscientifica, 2012-08) Shenavai, Sima; Preissing, Susanne; Hoffmann, Bernd; Dilly, Marc; Pfarrer, Christiane; Schuler, Gerhard; Özalp, Gözde R.; Çalışkan, Çağlar; Seyrek, Kamil İntaş; Uludağ Üniversitesi/Veteriner Fakültesi/Doğum ve Jinekoloji Anabilim Dalı.; 0000-0003-4694-6937; AAH-7292-2019; AAE-3607-2019; 23985710500; 23984353800; 6603409870A pronounced increase in fetal cortisol concentrations stimulating an increase in estrogen production at the expense of progesterone precursors in the placenta, luteolysis, and progesterone withdrawal is considered as a key event during the complex signal cascade leading to the initiation of parturition in cattle. However, there are many questions concerning the exact functional and/or temporal relationships between these individual processes which finally result in the expulsion of the calf and the timely release of the placenta. Thus, parturition was induced in 270-day pregnant cows using the progesterone receptor blocker aglepristone (group AG, n=3), the prostaglandin F-2 alpha analog cloprostenol (group PG, n=4), and the glucocorticoid dexamethasone (group GC, n=4) to characterize the effect on maternal steroid and prostaglandin levels and to identify immediate subsequent changes in placental morphology and gene expression as compared with untreated controls sampled on day 272 (group D272, n=3) and cows during normal parturition (group NT, n=4). All calves of the treatment groups were born on days 271-272, whereas gestational length in NT cows was 280.5 +/- 1.3 days. However, none of the treatments significantly induced the prepartal remodeling of placentomes characterized by a decline in trophoblast giant cells and reduction of the caruncular epithelium. Data on placental CYP17 and COX2 expression confirm that these key enzymes are upregulated by GC, whereas placental aromatase expression was not affected by any treatment. Maternal progesterone and prostaglandin profiles suggest differential effects of the treatments on luteal function and placental or uterine prostaglandin production. The results provide new information on the initiation of parturition in cattle but raise many new questions.Item Matrix metalloproteinase 2 (MMP-2) may be activated by binding of tissue inhibitor of matrix metalloproteinase 2 (TIMP-2) to MMP-14 in bovine placentomes(Wiley, 2009-02) Dilly, Marc; Shenavai, Sima; Hambruch, Nina; Schuler, Gerhard; Pfarrer, Christiane; Özalp, Gözde Rabia; İntaş, Kamil Seyrek; Uludağ Üniversitesi/Veterinerlik Fakültesi/Kadın Hastalıkları ve Doğum Anabilim Dalı.; 0000-0003-4694-6937; AAH-7292-2019; AAE-3607-2019Item Persistence of placental progesterone production in parturient cows is not a major factor in the etiology of retained fetal membrane(Wiley, 2009-02) Shenavai, Sima; Dilly, Marc; Pfarrer, Chistiane; Hoffmann, B.; Schuler, Gerhard; Özalp, Gözde Rabia; İntaş, Kamil Seyrek; Çalışkan, Çağlar; Uludağ Üniversitesi/Veterinerlik Fakültesi/Kadın Hastalıkları ve Doğum Anabilim Dalı.; 0000-0003-4694-6937; AAH-7292-2019; AAE-3607-2019Item Placental steroids in cattle: Hormones, placental growth factors or by-products of trophoblast giant cell differentiation?(Johann Ambrosius Barth Verlag Medizinverlage Heidelberg, 2008-07) Schuler, Gerhard; Greven, Helga; Kowalewski, Mariusz Pawel; Hoffmann, Bernd; Doering, Barbara; Özalp, Gözde Rabia; Uludağ Üniversites/Veteriner Fakültesi/Kadın Hastalıkları ve Doğum Anabilim Dalı.; 0000-0003-4694-6937; AAE-3607-2019; 8555276100The bovine placenta produces large amounts of steroids, mainly estrone (E1) and progesterone (P-4). Specific features of bovine placental steroidogenesis are I) the expression of all enzymes needed for the production of estrogens from cholesterol in the trophoblast 2) an only marginal and temporal contribution to peripheral maternal P4 levels restricted to a period between approx. days 150-240 of gestation 3) the predominance of sulfoconjugated over free El and 4) a complementary setting of steroidogenic enzymes in the two morphologically discriminable trophoblast cell types, the uninucleated trophoblast cells (UTC) and the trophoblast giant cells (TGC). In cattle so far no definite information is available on the specific biological roles of placental estrogens and P4. However, the detection of estrogen receptors and progesterone receptors in the placentomes Suggests a role primarily as local regulators of caruncular growth, differentiation and functions. Inconsistent with a function as a caruncular growth factor is the strong evidence that in cattle placental estrogens enter the maternal compartment almost completely as estrone Sulfate (EIS), which is not active at classical nuclear receptors. Oil the other hand, E IS may be converted locally to free active estrogens via the action of steroid sulfatase (StS), which has been detected in specific parts of the bovine carancular epithelium. Alternatively or in addition, StS expression in the caruncular epithelium may serve the utilization of sulfated neutral steroid precursors (e.g. pregrienolone sulfate or cholesterol sulfate) supplied with maternal blood, thus providing free substrates for further metabolization in the adjacent trophoblast. The down-regulation of P450scc and P450c17 and the Up-regulation of 3B-HSD and aromatase during the differentiation of TGC from UTC in parallel with the up-regulation of ERE and estrogen sulfotransferase in maturing TGC suggests a function of placental estrogens primarily as auto-or intracrine regulators during this process and assigns to conjugated placental estrogens a role as inactivated by-products of TGC differentiation intended for excretion. Collectively, despite some evidence from recent studies for putative roles of placental steroids in cattle their exact functions in the bovine species remain still undefined.Item Plasental steroidogeneziste kilit enzim: 3β-hidroksisteroid dehidrogenaz/∆5-4 izomeraz (3β-hsd)’ın ökaryon vektörde klonlanmış prob’larla belirlenmesi(Uludağ Üniversitesi, 2010-06-24) Schuler, Gerhard; Özalp, Gözde; Uludağ Üniversitesi/Veteriner Fakültesi.3β-hidroksisteroid dehidrogenaz/∆5-4 izomeraz (3β-HSD) plasental steroidogenesiz’de kilit enzim olarak kabul edilir. Steroid hormonların oluşumu için, pregnenolon ∆5 ve ∆4 sentez yollarında kullanılan 3βhidroksisteroid dehidrogenaz/∆5-4 izomeraz (3β-HSD)’a ihtiyaç duyar. Çalışmanın amacı, hedef genin, bir ökaryon vektor üzerinde klonlanmasıyla prob elde edilmesi ve in situ hibridizasyonda kullanılabilirliğinin gösterilmesidir. Bu amaçla total RNA izolasyonundan sonra RT-PCR yapıldı. DNA bantları agaroz jelden ayrılarak saflaştırıldı. 3βHSD-DNA’ların E.coli suşuna transformasyonu tamamlandıktan sonra 3βHSD insert içeren vektörden NcoI ve NotI restriksiyon enzimleriyle kesildi. DIG-işaretli cRNA’ların transkripsiyonu sonrasında in situ hibridizasyon yapıldı. Spesifik boyanmalar tek nukleuslu trofoblast hücrelerinde gözlenirken negatif kontrol grubunda boyanma gözlenmedi. Sonuç olarak bir ökaryon vector üzerinde, hedef gen klonlanarak steroidogenik enzimlerin belirlenmesinde kullanılmak üzere, in situ hibridizasyon tekniği için oldukça spesifik prob’lar elde edilmiştir.