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Dive into the research topics where Mert Bahtiyar is active.

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Featured researches published by Mert Bahtiyar.


Journal of Ultrasound in Medicine | 2007

Prevalence of Congenital Heart Defects in Monochorionic/Diamniotic Twin Gestations A Systematic Literature Review

Mert Bahtiyar; Antonette T. Dulay; Bevin Weeks; Alan H. Friedman; Joshua A. Copel

Congenital heart defects (CHDs) affect approximately 0.5% of all neonates. Recent literature points to a possible increase in the CHD prevalence among monochorionic/diamniotic (MC/DA) twin gestations. We hypothesized that MC/DA twin pregnancy is a risk factor for CHD.


American Journal of Obstetrics and Gynecology | 2011

Accreta complicating complete placenta previa is characterized by reduced systemic levels of vascular endothelial growth factor and by epithelial-to-mesenchymal transition of the invasive trophoblast

Mark Wehrum; Irina A. Buhimschi; Carolyn Salafia; Stephen Thung; Mert Bahtiyar; Erica F. Werner; Katherine Campbell; Christine Laky; Anna K. Sfakianaki; Guomao Zhao; Edmund F. Funai; Catalin S. Buhimschi

OBJECTIVE We sought to characterize serum angiogenic factor profile of women with complete placenta previa and determine if invasive trophoblast differentiation characteristic of accreta, increta, or percreta shares features of epithelial-to-mesenchymal transition. STUDY DESIGN We analyzed gestational age-matched serum samples from 90 pregnant women with either complete placenta previa (n = 45) or uncomplicated pregnancies (n = 45). Vascular endothelial growth factor (VEGF), placental growth factor, and soluble form of fms-like-tyrosine-kinase-1 were immunoassayed. VEGF and phosphotyrosine immunoreactivity was surveyed in histological specimens relative to expression of vimentin and cytokeratin-7. RESULTS Women with previa and invasive placentation (accreta, n = 5; increta, n = 6; percreta, n = 2) had lower systemic VEGF (invasive previa: median 0.8 [0.02-3.4] vs control 6.5 [2.7-10.5] pg/mL, P = .02). VEGF and phosphotyrosine immunostaining predominated in the invasive extravillous trophoblasts that coexpressed vimentin and cytokeratin-7, an epithelial-to-mesenchymal transition feature and tumorlike cell phenotype. CONCLUSION Lower systemic free VEGF and a switch of the interstitial extravillous trophoblasts to a metastable cell phenotype characterize placenta previa with excessive myometrial invasion.


Seminars in Perinatology | 2008

Cardiac Changes in the Intrauterine Growth-Restricted Fetus

Mert Bahtiyar; Joshua A. Copel

Intrauterine growth restriction (IUGR), which complicates approximately 3% to 10% of all pregnancies leads to preferential hemodynamic changes in affected fetuses. Advanced ultrasound modalities allow reliable and reproducible assessment of the intrauterine fetal cardiac function. Among other methods, combined cardiac output, individual ventricular ejection forces, E/A ratio, and Tei index can be utilized to quantify fetal heart function. While systolic ejection forces significantly increase with advancing gestational age in normal fetuses, there is a significant decline in the systolic function in IUGR fetuses. From the diastolic cardiac function point, IUGR fetuses have significantly lower left and right ventricular diastolic filling without significant changes in diastolic function. Overall, IUGR fetuses demonstrate progressive hemodynamic changes. It appears that there is an earlier and more pronounced right than left and diastolic than systolic fetal cardiac function deterioration in growth-restricted fetuses.


Obstetrics & Gynecology | 2008

Using proteomic analysis of the human amniotic fluid to identify histologic chorioamnionitis.

Irina A. Buhimschi; Eduardo Zambrano; Christian M. Pettker; Mert Bahtiyar; Michael J. Paidas; Victor A. Rosenberg; Stephen Thung; Carolyn Salafia; Catalin S. Buhimschi

OBJECTVE: To estimate the relationship between histologic chorioamnionitis and four amniotic fluid proteomic biomarkers characteristic of inflammation (defensins 2 and 1, calgranulins C and A). METHODS: One hundred fifty-eight women with singleton pregnancies had a clinically indicated amniocentesis to rule out inflammation and infection in the context of preterm labor or preterm premature rupture of membranes. A proteomic fingerprint (Mass Restricted score) was generated from amniotic fluid using surface-enhanced laser desorption ionization time-of-flight mass spectrometry. The Mass Restricted score ranges from 0 to 4 (none to all four biomarkers present) in direct relationship with severity of intra-amniotic inflammation. Presence or absence of biomarkers was analyzed in relationship to placental pathology. Criteria for severity of histologic chorioamnionitis were 3 stages and 4 grades of inflammation of the amnion, choriodecidua and chorionic plate. RESULTS: The prevalence of histologic chorioamnionitis was 64% (stage I 12%, stage II 16%, and stage III 37%). The Mass Restricted score significantly correlated with stages of histologic chorioamnionitis (r=0.539, P<.001), grades of choriodeciduitis (r=0.465, P<.001), and amnionitis (r=0.536, P<.001). African-American women were overrepresented in the group with severe inflammation (Mass Restricted score 3–4, P=.022). Of the four biomarkers of the Mass Restricted score, calgranulin C had the strongest relationship with presence of stage III chorioamnionitis, independent of race, amniocentesis-to-delivery interval, and gestational age. CONCLUSION: Proteomic analysis of amniotic fluid provides an opportunity for early recognition of histologic chorioamnionitis. This methodology may in the future identify candidates for antenatal therapeutic interventions. LEVEL OF EVIDENCE: II


American Journal of Obstetrics and Gynecology | 2007

Nucleated red blood cells are a direct response to mediators of inflammation in newborns with early-onset neonatal sepsis.

Antonette T. Dulay; Irina A. Buhimschi; Guomao Zhao; Guoyang Luo; Sonya S. Abdel-Razeq; Michael Cackovic; Victor A. Rosenberg; Christian M. Pettker; Stephen Thung; Mert Bahtiyar; Vineet Bhandari; Catalin S. Buhimschi

OBJECTIVE The objective of the study was to test the hypothesis that inflammation modulates fetal erythroblastosis and/or the release of nucleated red blood cells (NRBCs) independent of hypoxia or fetal stress. We sought to determine whether fetal inflammation is associated with an elevation in neonatal NRBC count in the setting of inflammation-associated preterm birth. STUDY DESIGN The relationships between peripheral NRBC count, histological chorioamnionitis, umbilical cord interleukin (IL)-6, erythropoietin (EPO), cortisol, and acid-base status were analyzed in 68 preterm singletons, born to mothers who had an amniocentesis to rule out infection. Proteomic profiling of amniotic fluid identified presence of intraamniotic inflammation according to established parameters. NRBC counts were assessed within 1 hour of birth. Early-onset neonatal sepsis (EONS) was established based on hematological and microbiological indices. IL-6, EPO, and cortisol levels were measured by immunoassays. Fetal acid-base status was determined within 10 minutes of delivery. Parametric or nonparametric statistics were used. RESULTS Fetuses with EONS (n = 19) were delivered at earlier gestational ages (mean +/- SD: 27.1 +/- 2.8 weeks, P = .001) and more often by mothers with intraamniotic inflammation (P = .022) and histological chorioamnionitis (P < .001). Neonates with EONS had higher absolute NRBC counts (P = .011). NRBC counts were directly correlated with cord blood IL-6 levels (P < .001) but not with EPO, cortisol or parameters of acid-base status levels regardless of EONS status. These relationships remained following correction for gestational age, diabetes, intrauterine growth restriction, and steroid exposure. CONCLUSION In the setting of inflammation-associated preterm birth and in the absence of hypoxia, elevations in NRBCs in the early neonatal period may be a direct response of exposure to inflammatory mediators in utero.


Journal of Immunology | 2011

IL-6 Trans-Signaling System in Intra-Amniotic Inflammation, Preterm Birth, and Preterm Premature Rupture of the Membranes

Sarah Y. Lee; Irina A. Buhimschi; Antonette T. Dulay; Unzila Ali; Guomao Zhao; Sonya S. Abdel-Razeq; Mert Bahtiyar; Stephen Thung; Edmund F. Funai; Catalin S. Buhimschi

Classic IL-6 signaling is conditioned by the transmembrane receptor (IL-6R) and homodimerization of gp130. During trans-signaling, IL-6 binds to soluble IL-6R (sIL-6R), enabling activation of cells expressing solely gp130. Soluble gp130 (sgp130) selectively inhibits IL-6 trans-signaling. To characterize amniotic fluid (AF) IL-6 trans-signaling molecules (IL-6, sIL-6R, sgp130) in normal gestations and pregnancies complicated by intra-amniotic inflammation (IAI), we studied 301 women during second trimester (n = 39), third trimester (n = 40), and preterm labor with intact (n = 131, 85 negative IAI and 46 positive IAI) or preterm premature rupture of membranes (PPROM; n = 91, 61 negative IAI and 30 positive IAI). ELISA, Western blotting, and real-time RT-PCR were used to investigate AF, placenta, and amniochorion for protein and mRNA expression of sIL-6R, sgp130, IL-6R, and gp130. Tissues were immunostained for IL-6R, gp130, CD15+ (polymorphonuclear), and CD3+ (T cell) inflammatory cells. The ability of sIL-6R and sgp130 to modulate basal and LPS-stimulated release of amniochorion matrix metalloprotease-9 was tested ex vivo. We showed that in physiologic gestations, AF sgp130 decreases toward term. AF IL-6 and sIL-6R were increased in IAI, whereas sgp130 was decreased in PPROM. Our results suggested that fetal membranes are the probable source of AF sIL-6R and sgp130. Immunohistochemistry and RT-PCR revealed increased IL-6R and decreased gp130 expression in amniochorion of women with IAI. Ex vivo, sIL-6R and LPS augmented amniochorion matrix metalloprotease-9 release, whereas sgp130 opposed this effect. We conclude that IL-6 trans-signaling molecules are physiologic constituents of the AF regulated by gestational age and inflammation. PPROM likely involves functional loss of sgp130.


American Journal of Perinatology | 2008

Stillbirth at Term in Women of Advanced Maternal Age in the United States: When Could the Antenatal Testing Be Initiated?

Mert Bahtiyar; Edmund F. Funai; Victor A. Rosenberg; Errol R. Norwitz; Heather S. Lipkind; Catalin S. Buhimschi; Joshua A. Copel

We sought to determine if advanced maternal age (AMA) is a risk factor for intrauterine fetal demise (IUFD). We used a U.S. Centers for Disease Control and Prevention database and analyzed outcomes in women 15 to 44 years of age with term singleton gestations. Cox proportional hazards models and Cochran-Mantel-Haenszel tests were used. Results were controlled for maternal race and smoking. After excluding congenital anomalies and medical complications, 6,239,399 singleton term deliveries were identified. When compared with women 25 to 29 years of age, the risk of IUFD increased with advancing age: 30 to 34 years, odds ratio [OR] = 1.24 (95% confidence interval [CI], 1.13 to 1.36); 35 to 39 years, OR = 1.45 (95% CI, 1.21 to 1.74), and 40 to 44 years, OR = 3.04 (95% CI, 1.58 to 5.86). The risk of IUFD for women 40 to 44 years of age at 39 weeks is comparable with that of 42 weeks in those 25 to 29 years of age. We concluded that AMA is an independent predictor of IUFD, and a strategy of antenatal testing in those > or = 40 years of age beginning at 38 weeks may be considered.


American Journal of Reproductive Immunology | 1997

Growth-Regulated α Expression in Human Preovulatory Follicles and Ovarian Cells

Engin Oral; Emre Seli; Mert Bahtiyar; Ervin E. Jones; Aydin Arici

PROBLEM: Around the time of ovulation the number of neutrophils increases in the theca of the leading follicle. We hypothesized that growth‐regulated a (GROα), a neutrophil chemoattractant/activating factor, may be a modulator of periovulatory neutrophil chemotaxis.


Ultrasound in Obstetrics & Gynecology | 2011

Assessment of the fetal thymus by two- and three-dimensional ultrasound during normal human gestation and in fetuses with congenital heart defects.

Ling Li; Mert Bahtiyar; C. S. Buhimschi; Lin Zou; Qichang Zhou; Joshua A. Copel

Our objectives were to compare the size and volume of the developing fetal thymus obtained by two‐dimensional ultrasound (2D‐US) and three‐dimensional ultrasound (3D‐US), develop normative data for thymus volume (TV), and investigate TV in fetuses with congenital heart disease (CHD) and normal twin gestations.


Obstetrics & Gynecology | 1996

Growth-regulated α expression in the peritoneal environment with endometriosis

Engin Oral; Emre Seli; Mert Bahtiyar; David L. Olive; Aydin Arici

Objective To investigate the presence and modulation of growth-regulated α, a member of the chemokine family with neutrophil chemotactic activity, in the peritoneal fluid of women with or without endometriosis. Methods Peritoneal fluid samples were obtained at laparoscopy from 63 women with endometriosis and 19 fertile women without endometriosis. Endometrial tissue was obtained from uteri after hysterectomy for reasons other than endometrial disease or from endometrial biopsies of reproductive-age women. Cellular RNA was extracted and northern blots were hybridized with an oligonucleotide probe complementary to a specific sequence of growth-regulated α messenger RNA. Growth-regulated α in peritoneal fluid and culture supernatant was quantified using enzyme-linked immunosorbent assay. Statistical analyses were performed using Kruskal-Wallis and Mann-Whitney tests. Results The median (range) concentration of growth-regulated α in peritoneal fluid samples from 19 normal fertile women was 27 pg/mL (0-108), from 24 women with moderate endometriosis 34 pg/mL (8–150), and from seven with severe endometriosis was 73 pg/mL (10–221) (P = .04, P = .01, respectively). In the moderate and severe endometriosis groups, the levels of growth-regulated α were significantly higher in the peritoneal fluid of women with untreated endometriosis (73 pg/mL [10–221]) than in women with medically treated endometriosis (25 pg/mL [8–47]). In mesothelial and endometrial stromal cells in culture, growth-regulated α messenger RNA and protein were detectable constitutively; however, both interleukin-1α and tumor necrosis factor-α induced higher levels of growth-regulated α messenger RNA and protein in a dose- and time-dependent manner. Conclusions Growth-regulated α levels are elevated in the peritoneal fluid of women with moderate and severe endometriosis. This chemotactic factor, which acts via the interleukin-8 receptor, may play a role in the pathogenesis of endometriosis.

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