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Featured researches published by Yilmaz Guzel.


Human Reproduction | 2015

The magnitude of gonadotoxicity of chemotherapy drugs on ovarian follicles and granulosa cells varies depending upon the category of the drugs and the type of granulosa cells

Aytac Yuksel; Gamze Bildik; Filiz Senbabaoglu; Nazli Akin; Macit Arvas; Fehmi Ünal; Yagmur Kilic; Isil Karanfil; Baldan Eryılmaz; Pelin Yilmaz; Can Ozkanbaş; C. Taskiran; Senai Aksoy; Yilmaz Guzel; Basak Balaban; Umit Ince; Akira Iwase; Bulent Urman; Ozgur Oktem

STUDY QUESTION Do different chemotherapy drugs exert the same magnitude of cytotoxicity on dormant primordial follicles and the growing follicle fraction in the ovary in vivo and on mitotic non-luteinized and non-mitotic luteinized granulosa cells in vitro? SUMMARY ANSWER Cyclophosphamide (alkylating agent) and cisplatin (alkylating like) impacted both primordial and pre-antral/antral follicles and both mitotic and non-mitotic granulosa cells, whereas the anti-metabolite cancer drug gemcitabine was detrimental only to pre-antral/antral follicles and mitotic non-luteinized granulosa cells. WHAT IS KNOWN ALREADY It is already known that anti-metabolite cancer drugs are less detrimental to the ovary than alkylating and alkylating like agents, such as cyclophosphamide and cisplatin. This assumption is largely based on the results of clinical reports showing lower rates of amenorrhea in women receiving anti-metabolite agent-based regimens compared with those treated with the protocols containing an alkylating drug or a platinum compound. But a quantitative comparison of gonadotoxicity with a histomorphometric proof of evidence has not been available for many chemotherapy drugs. Therefore, we combined in this study in vivo and in vitro models of human and rat origin that allows a comparative analysis of the impact of different chemotherapy agents on the ovary and granulosa cells using real-time quantitative cell indices, histomorphometry, steroidogenesis assays, and DNA damage and cell death/viability markers. We also aimed to investigate if there is a difference between mitotic and non-mitotic granulosa cells in terms of their sensitivity to the cytotoxic actions of chemotherapy drugs with different mechanisms of action. This issue has not been addressed previously. STUDY DESIGN, SIZE, DURATION This translational research study involved in vivo analyses of ovaries in rats and in vitro analyses of granulosa cells of human and rat origin. PARTICIPANTS/MATERIALS, SETTING, METHODS For the in vivo assays, 54 4- to 6-week old Sprague-Dawley young female rats were randomly allocated into four groups of 13 to receive a single IP injection of: saline (control), gemcitabine (200 mg/kg), cisplatin (50 mg/kg) or cyclophosphamide (200 mg/kg). The animals were euthanized 72 h later. Follicle counts and serum AMH levels were compared between the groups. In vitro cytotoxicity studies were performed using mitotic non-luteinized rat (SIGC) and human (COV434, HGrC1) granulosa cells, and non-mitotic luteinized human (HLGC) granulosa cells. The cells were plated at a density of 5000 cells/well using DMEM-F12 culture media supplemented with 10% FBS. Chemotherapy agents were used at their therapeutic blood concentrations. The growth of mitotic granulosa cells was monitored real-time using xCelligence system. Live/dead cell and apoptosis assays were also carried out using intravital Yo-Pro-1 staining and cleaved caspase-3 expression, respectively. Estradiol (E2), progesterone (P) and anti-Mullerian hormone (AMH) levels were assayed with ELISA. MAIN RESULTS AND THE ROLE OF CHANCE Cyclophosphamide and cisplatin caused massive atresia of both primordials and growing follicles in the rat ovary whereas gemcitabine impacted pre-antral/antral follicles only. Cyclophosphamide and cisplatin induced apoptosis of both mitotic non-luteinized and non-mitotic luteinized granulosa cells in vitro. By contrast, cytotoxicity of gemcitabine was confined to mitotic non-luteinized granulosa cells. LIMITATIONS, REASONS FOR CAUTION This study tested only three chemotherapeutic agents. The experimental methodology described here could be applied to other drugs for detailed analysis of their ovarian cytotoxicity. WIDER IMPLICATIONS OF THE FINDINGS These findings indicate that in vivo and in vitro cytotoxic actions of chemotherapy drugs on the ovarian follicles and granulosa cells vary depending upon the their mechanism of action and the nature of the granulosa cells.


Human Reproduction | 2015

GnRH agonist leuprolide acetate does not confer any protection against ovarian damage induced by chemotherapy and radiation in vitro

Gamze Bildik; Nazli Akin; Filiz Senbabaoglu; Gizem Nur Sahin; Sercin Karahuseyinoglu; Umit Ince; C. Taskiran; Ugur Selek; Kayhan Yakin; Yilmaz Guzel; Cem Ayhan; Ebru Alper; Mustafa Çetiner; Basak Balaban; Nil Molinas Mandel; Tarık Esen; Akira Iwase; Bulent Urman; Ozgur Oktem

STUDY QUESTION Is there any in vitro evidence for or against ovarian protection by co-administration of a GnRH agonist with chemotherapy in human? SUMMARY ANSWER The co-administration of GnRH agonist leuprolide acetate with cytotoxic chemotherapy agents does not preserve ovarian reserve in vitro. WHAT IS KNOWN ALREADY Randomized controlled trials of the co-administration of gonadotrophin-releasing hormone (GnRH) agonists with adjuvant chemotherapy to preserve ovarian function have shown contradictory results. This fact, together with the lack of a proven molecular mechanism of action for ovarian protection with GnRH agonist (GnRHa) places this approach as a fertility preservation strategy under scrutiny. We therefore aimed in this study to provide in vitro evidence for or against the role of GnRHa in the prevention of chemotherapy-induced damage in human ovary. STUDY DESIGN, SETTINGS, SIZE AND DURATION This translational research study of ex vivo and in vitro models of human ovary and granulosa cells was conducted in a university hospital between 2013 and 2015. PARTICIPANTS/MATERIALS, SETTING, METHODS Ovarian cortical pieces (n = 15, age 14-37) and mitotic non-luteinized (COV434 and HGrC1) and non-mitotic luteinized human granulosa cells (HLGC) expressing GnRH receptor were used for the experiments. The samples were treated with cyclophosphamide, cisplatin, paclitaxel, 5-FU, or TAC combination regimen (docetaxel, adriamycin and cyclophosphamide) with and without GnRHa leuprolide acetate for 24 h. DNA damage, apoptosis, follicle reserve, hormone markers of ovarian function and reserve (estradiol (E2), progesterone (P) and anti-mullerian hormone (AMH)) and the expression of anti-apoptotic genes (bcl-2, bcl-xL, bcl-2L2, Mcl-1, BIRC-2 and XIAP) were compared among control, chemotherapy and chemotherapy + GnRHa groups. MAIN RESULTS AND THE ROLE OF CHANCE The greatest magnitude of cytotoxicity was observed in the samples treated with cyclophosphamide, cisplatin and TAC regimen. Exposure to these drugs resulted in DNA damage, apoptosis and massive follicle loss along with a concurrent decline in the steroidogenic activity of the samples. GnRHa co-administered with chemotherapy agents stimulated its receptors and raised intracellular cAMP levels. But it neither activated anti-apoptotic pathways nor prevented follicle loss, DNA damage and apoptosis induced by these drugs. LIMITATIONS, REASONS FOR CAUTION Our findings do not conclusively rule out the possibility that GnRHa may offer protection, if any, through some other mechanisms in vivo. WIDER IMPLICATIONS OF THE FINDINGS GnRH agonist treatment with chemotherapy does not prevent or ameliorate ovarian damage and follicle loss in vitro. These data can be useful when consulting a young patient who may wish to receive GnRH treatment with chemotherapy to protect her ovaries from chemotherapy-induced damage.


Molecular Reproduction and Development | 2017

Understanding follicle growth in vitro: Are we getting closer to obtaining mature oocytes from in vitro‐grown follicles in human?

Yilmaz Guzel; Ozgur Oktem

Obtaining and fertilizing mature oocytes from immature follicles that were grown outside the body has conceptually attracted scientists for centuries, with initial attempts first documented in the 19th century. Significant progress has been made since then, due in part to a better understanding of folliculogenesis and improved techniques of in vitro follicle growth. Indeed, in vitro growth is now considered a reasonable approach to preserve or restore fertility when immature follicles and their oocytes need to be grown and matured outside the body. Certain patients would benefit from in vitro follicle growth, particularly those who carry a risk of cancer re‐seeding after grafting of frozen‐thawed ovarian tissue or who are at the risk of premature ovarian failure due to several intrinsic ovarian defects and genetic mutations that lead to accelerated follicle atresia and early exhaustion of the ovarian reserve. This review provides an update on the current status of in vitro growth of preantral human follicles, from initial efforts to the most recent achievements.


Reproductive Toxicology | 2016

Cytotoxicity and mitogenicity assays with real-time and label-free monitoring of human granulosa cells with an impedance-based signal processing technology intergrating micro-electronics and cell biology.

Ozgur Oktem; Gamze Bildik; Filiz Senbabaoglu; Nathan A. Lack; Nazli Akin; Feridun Yakar; Defne Urman; Yilmaz Guzel; Basak Balaban; Akira Iwase; Bulent Urman

A recently developed technology (xCelligence) integrating micro-electronics and cell biology allows real-time, uninterrupted and quantitative analysis of cell proliferation, viability and cytotoxicity by measuring the electrical impedance of the cell population in the wells without using any labeling agent. In this study we investigated if this system is a suitable model to analyze the effects of mitogenic (FSH) and cytotoxic (chemotherapy) agents with different toxicity profiles on human granulosa cells in comparison to conventional methods of assessing cell viability, DNA damage, apoptosis and steroidogenesis. The system generated the real-time growth curves of the cells, and determined their doubling times, mean cell indices and generated dose-response curves after exposure to cytotoxic and mitogenic stimuli. It accurately predicted the gonadotoxicity of the drugs and distinguished less toxic agents (5-FU and paclitaxel) from more toxic ones (cisplatin and cyclophosphamide). This platform can be a useful tool for specific end-point assays in reproductive toxicology.


European Journal of Obstetrics & Gynecology and Reproductive Biology | 2018

Sphingosine-1-phosphate protects human ovarian follicles from apoptosis in vitro

Yilmaz Guzel; Gamze Bildik; Ozgur Oktem

OBJECTIVE(S) We aimed to analyze if anti-apoptotic agent sphingosine-1-phosphate offers protection against in vitro follicle atresia during culture of human ovarian cortical samples. STUDY DESIGN A translational research study of ex-vivo and in-vitro models of human ovarian tissue. MATERIAL AND METHODS Ovarian cortical tissue fragments (1 × 0.5 cm) were obtained from young patients (n = 15 mean age ± SD: 29.4 ± 2.5) undergoing laparoscopic excision of benign ovarian cysts. The samples were cultured for 4 days in 24-well format culture plate using conventional culture techniques. S1P was added to culture media at 200 and 400 μM concentrations. At the end of culture period the samples were processed for both histomorphological assessment and detection of apoptosis with immunohistochemistry and western blot methods using apoptosis marker cleaved caspase-3. In vitro estradiol (E2) and AMH productions of the samples were measured with ELISA. Follicle counts were expressed as the mean number of follicles per mm2. RESULTS The mean numbers of primordial and secondary follicles were 3.2 ± 0.4 and 0.7 ± 0.2 respectively, in the fresh fixed uncultured samples. After four days of culture their numbers were significantly decreased to 0.8 ± 0.2 (p < 0.01) and 0.1 ± 0.05 (p < 0.05) respectively, in the control samples cultured without S1P compared to fresh fixed samples. S1P treatment decreased follicle atresia and significantly higher number of primordials (2.3 ± 0.3, p < 0.01) and secondary follicles (0.5 ± 0.1, p < 0.05) survived in the samples after 4 day culture period compared to those cultured without S1P. In line with this there was dose-dependent decrease in the protein expression of cleaved caspase-3 on western blot and in the number of apoptotic follicles stained positive for cleaved caspase-3 on immunohistochemistry in the samples incubated with S1P at 200 and 400 μM concentrations. Furthermore, those samples incubated with S1P produced significantly higher amounts of E2 (2339 ± 321 vs. 1156 ± 125 pg/mL respectively, p < 0.01) compared to control samples. CONCLUSIONS These results suggest that S1P promotes follicle survival in human ovarian cortical samples in vitro.


Cell Death and Disease | 2018

Endogenous c-Jun N-terminal kinase (JNK) activity marks the boundary between normal and malignant granulosa cells

Gamze Bildik; Nazli Akin; Filiz Senbabaoglu; Yashar Esmalian; Gizem Nur Sahin; Defne Urman; Sercin Karahuseyinoglu; Umit Ince; E. Palaoglu; C. Taskiran; Macit Arvas; Yilmaz Guzel; Kayhan Yakin; Ozgur Oktem

Granulosa cell tumor of the ovary (GCT) is a very rare tumor, accounting for only 2% of all ovarian tumors. It originates from sex cords in the ovary and can be divided into adult (95%) and juvenile (5%) types based on histologic findings. To date, no clear etiologic process has been identified other than a missense point mutation in the FOXL2 gene. Our previous works showed that c-Jun N-terminal kinase (JNK) pathway plays critical role in cell cycle progression and mitosis of normal and immortalized granulosa cells and follicle growth in rodent ovaries. These findings led us to investigate the role of JNK pathway in the granulosa cell tumor of the ovary. We used two different GCT cell lines (COV434 and KGN) and fresh GCT samples of adult and juvenile types obtained from the patients during surgery. We have discovered that endogenous kinase activity of JNK is markedly enhanced in the GCT samples and cell lines, whereas it was almost undetectable in mitotic non-malignant human granulosa cells. The inhibition of JNK pathway in GCT cell lines with two different pharmacologic inhibitors (SP600125 and AS601245) or siRNA resulted in a dose-dependent reduction in in vitro cell growth, increased apoptosis and diminished estradiol and AMH productions. JNK inhibition was also associated with a decrease in the number of cells positive for mitosis marker phospho-histone H3Ser 10 in the asynchronous cells; and diminished EdU uptake during S phase and cell cycle arrest at G2/M-phase transition in the synchronized cells. Ex vivo treatment of patient-derived GCT samples with JNK inhibitors for 24 h significantly decreased their in vitro growth and estradiol and AMH productions. Furthermore, in human GCT xenograft model, in vivo tumor growth was significantly reduced and plasma AMH levels were significantly decreased in SCID mice after administration of JNK inhibitors and siRNA. These findings suggest that targeting JNK pathway may provide therapeutic benefit in the treatment of granulosa cell tumors for which currently no curative therapy exists beyond surgery.


Molecular Reproduction and Development | 2018

Sphingosine-1-phosphate reduces atresia of primordial follicles occurring during slow-freezing and thawing of human ovarian cortical strips: GUZEL et al.

Yilmaz Guzel; Gamze Bildik; Ece Dilege; Ozgur Oktem

We aimed in this study to explore if sphingosine‐1‐phosphate (S1P) reduces apoptosis of primordial follicles during cryopreservation of human ovarian cortical samples. Ovarian cortical tissue fragments obtained from young patients who underwent laparoscopic excision of benign ovarian cysts were used for the experiments. The samples were slow‐frozen and thawed with and without S1P at 200 and 400 μM, cultured for 1 day, and then were fixed and processed for both histomorphological assessment and detection of apoptosis with immunohistochemistry using apoptosis marker cleaved caspase‐3. Follicle counts were expressed as the mean number of follicles per mm2. The mean number of primordial follicles and in vitro estradiol (E2) and anti‐mullerian hormone (AMH) production of the slow‐frozen and thawed samples were significantly reduced compared with fresh unfrozen samples. S1P treatment at 400 μM but not 200 μM concentration resulted in a significant increase in the number of surviving primordial follicles and in vitro E2 and AMH productions of the samples compared with their counterparts slow‐frozen without S1P. We found that that there was a significant decrease in the number of primordial follicles with their oocytes stained positive for cleaved caspase‐3 in the slow‐frozen samples S1P 400 μM in comparison with the samples slow‐frozen without S1P. These results suggest that S1P may ameliorate follicle atresia occurring in human ovarian cortical samples during cryopreservation.


PLOS ONE | 2017

Menstrual cycle characteristics of young females with occult primary ovarian insufficiency at initial diagnosis and one-year follow-up with serum amh level and antral follicle count

Yilmaz Guzel; Yılda Arzu Aba; Kayhan Yakin; Ozgur Oktem

Occult primary ovarian insufficiency (also known as incipient ovarian failure or diminished ovarian reserve) is defined as serum AMH level ≤1.1ng/mL in women under age 30. Limited data is available regarding the prevalence of occult POI, the preceding menstrual characteristics and its natural course in otherwise healthy young females. We aimed in this prospective observational study to determine the prevalence of occult POI in young females (< age 30) screened with serum AMH measurement; and analyze the patterns of change in their menstruation at initial assessment and one-year follow-up in relation to the changes in ovarian reserve quantitatively assessed with AMH and AFC. 963 young female college students under age 30 voluntarily participated in this study. 43 of them (4.4%) were diagnosed with occult POI as their AMH levels were ≤ 1.1ng/mL. Thirty-eight (83.4%) of them have regular cycles and denied any menstrual irregularity in the last 12 months. This rate was not statistically different from 7.3% of those with AMH>1.1ng/mL who reported at least one abnormal menstrual cycle in the last year (p = 0.36). Cycle length was significantly shorter in females with AMH ≤ 1.1ng/mL compared to those with AMH>1.1ng/mL (25.1±3.2 vs. 31.2±2.8 respectively, p<0.001). Karyotype, FMR-1 mutation analyses and auto-antibody screening returned normal in all. At one-year follow-up AMH, AFC and mean cycle length were further reduced compared to their values at initial assessment. Now, a greater proportion of the participants with occult POI were menstruating regularly at every 21 days compared to the initial evaluation one year ago (39.5% vs. 13.9% respectively, p = 0.013). Twenty-five underwent oocyte cryopreservation. These findings underscore the importance of screening young females with AMH for possible occult POI. It also emphasizes that young females with critically diminished ovarian reserve may continue to menstruate regularly without any characteristic menstrual abnormality other than shortening of cycle length.


Applied Nursing Research | 2017

Effect of music therapy on the anxiety levels and pregnancy rate of women undergoing in vitro fertilization-embryo transfer: A randomized controlled trial

Yılda Arzu Aba; Dilek Avci; Yilmaz Guzel; Semanur Kumral Ozcelik; Basak Gurtekin

PURPOSE The aim of this study was to determine the effect of music therapy on the anxiety levels and pregnancy rates of women who underwent in vitro fertilization-embryo transfer. METHODS This prospective randomized controlled trial was conducted with 186 infertile women who presented to the In Vitro Fertilization Unit at the American Hospital in Turkey between April 2015 and April 2016. The infertile women who met the inclusion criteria were assigned to the music therapy group or the standard therapy group through block randomization. The study data were collected using the Personal Information Form, and State-Trait Anxiety Inventory. Early treatment success was determined by serum beta human chorionic gonadotrophin levels seven or ten days after the luteal day zero. For the analysis, descriptive statistics, chi-square test, Fishers exact test, independent sample t-test were used. RESULTS After the embryo transfer, the mean state anxiety scores decreased in both groups, and the mean trait anxiety score decreased in the music therapy group; however, the difference was not statistically significant (p>0.05). Clinical pregnancy rates did not differ between the music (48.3%) and standard (46.4%) therapy groups. CONCLUSION After the two sessions of music therapy, state and trait anxiety levels decreased and pregnancy rates increased, but the difference was not significant. Therefore, larger sample sizes and more sessions are needed to evaluate whether music therapy has an effect on clinical outcomes.


Journal of The Turkish German Gynecological Association | 2018

Spontaneous and IVF pregnancies have comparable first trimester screening profiles for Down syndrome

Yilmaz Guzel; E Turkgeldi; Hande Yağmur; Zeki Salar; Basak Balaban; Bulent Urman; Ozgur Oktem

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Yılda Arzu Aba

Istanbul Aydın University

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