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Dive into the research topics where Konstantinos Ravanos is active.

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Featured researches published by Konstantinos Ravanos.


Reproductive Biomedicine Online | 2012

History of endometriosis may adversely affect the outcome in menopausal recipients of sibling oocytes.

Yannis Prapas; Maria Goudakou; Ioannis Matalliotakis; Alexandra Kalogeraki; Charikleia Matalliotaki; Yannis Panagiotidis; Konstantinos Ravanos; Nikos Prapas

Due to the known adverse effect of endometriosis on gamete quality, it has always been difficult to demonstrate a direct effect of endometriosis on implantation. In order to eliminate these confounding effects, this prospective comparative study studied a population of menopausal recipients with and without endometriosis sharing sibling oocytes coming from the same donor. The aim was to understand the impact of endometriosis on implantation, pregnancy and live birth rates in menopausal recipients. A total of 240 menopausal recipients of donated sibling oocytes, were divided in two groups. Group I consisted of 120 recipients diagnosed with endometriosis and group II consisted of 120 controls. The implantation and pregnancy rates were significantly lower in the endometriosis group compared with the control group (23.81% versus 31.48%, P=0.019; 45.00% versus 58.33%, P=0.039, respectively). In oocyte donation cycles, a recipients history of endometriosis might have a negative impact on implantation, pregnancy and live birth rates, even in menopausal women. Infertility in endometriosis may be due to poor oocyte quality or embryos with decreased ability to implant due to impaired fertilization. There are no conclusive data on the impact of endometriosis on implantation. The already-known adverse effect of endometriosis on gamete quality makes it more difficult to demonstrate a direct effect of endometriosis on implantation. In order to eliminate these confounding effects we studied a population of menopausal recipients with and without endometriosis sharing sibling oocytes coming from the same oocyte donor. The oocyte donation model was used in an attempt to understand whether the endometrium, the oocytes or both are affected by endometriosis. The aim of the present study was to understand the impact of endometriosis on implantation, pregnancy and live birth rates in menopausal recipients. A total of 240 menopausal recipients of donated sibling oocytes were divided into two groups. Group I consisted of 120 recipients diagnosed with endometriosis and group II consisted of 120 controls. The pregnancy and implantation rates were significantly lower in the endometriosis group compared to the control group (45.00% versus 58.33%, P=0.039) and (23.81% versus 31.48%, P=0.019) respectively. In oocyte donation cycles, a recipients history of endometriosis might have a negative impact on implantation, pregnancy and live birth rates, even in menopausal women.


Gynecological Endocrinology | 2015

Factors implicated in the initiation of human parturition in term and preterm labor: a review.

Konstantinos Ravanos; Themistoklis Dagklis; Stamatios Petousis; Chrysoula Margioula-Siarkou; Yannis Prapas; Nikolaos Prapas

Abstract After accommodating the pregnancy for an average of 40 weeks, the uterus expels the fetus, the placenta and the membranes through the birth canal in a process named parturition. The absolute sequence of events that trigger and sustain human parturition are not yet fully clarified. Evidence suggests that spontaneous preterm and term labor seem to share a common inflammatory pathway. However, there are several other factors being involved in the initiation of human parturition. Placental corticotropin releasing hormone production seems to serve as a placental clock that might be set to ring earlier or later determining the duration of pregnancy and timing of labor. Estrogens do not cause contractions but their properties seem to capacitate uterus to coordinate and enhance contractions. Cytokines, prostaglandins, nitric oxide and steroids seem also to induce ripening by mediating remodeling of the extracellular matrix and collagen. Infection and microbe invasion resulting in chorioamnionitis also represents a common cause of early preterm labour. This review provides an overview of all these factors considered to be implicated in the initiation of human parturition. Chinese abstract 在调节平均40周的妊娠后,子宫通过产道排出胎儿,胎盘和胎膜的过程称为分娩。触发和维持人类分娩的绝对事件序列仍未完全阐明。有证据表明,自发早产和足月产似乎都遵循一条同样的炎症通路。然而,仍有一些其他的因素与人类分娩的触发有关。胎盘促肾上腺激素释放激素的产生似乎充当胎盘时钟的作用,时钟响的时间可能会设定的早或晚,决定了孕期的时长和分娩的时间。雌激素并不造成宫缩,但是它的性质可使子宫协调而加强宫缩。细胞因子、前列腺素、一氧化氮和类固醇似乎通过重塑细胞外基质和胶原来同样促进成熟。感染和微生物入侵所导致的绒毛膜羊膜炎也是常见的早产原因之一。这篇综述提供了与人类分娩的相关因素的概述。


Journal of Maternal-fetal & Neonatal Medicine | 2016

Expression of progesterone receptors is significantly impaired in the endometrium of infertile women during the implantation window: a prospective observational study.

Stamatios Petousis; Yannis Prapas; Chrysoula Margioula-Siarkou; Stefanos Milias; Konstantinos Ravanos; Ioannis Kalogiannidis; Constantinos Haitoglou; Nikolaos Prapas; David Rousso

Abstract Objective: To compare the expression of progesterone receptors (A + B) and type-B progesterone receptors in the epithelial and stromal cells of fertile and infertile women. Methods: Women were divided into two groups, the group of fertile controls (group 1) and the group of infertile women (group 2) and were set on regular ultrasound imaging in order to detect ovulation. An endometrial biopsy was obtained on the seventh or eighth post-ovulatory day. Immunohistochemistry was performed to measure percentage of positive nuclei, intensity of staining and h-score for progesterone receptors (PgR) (A + B) as well as type-B progesterone receptors in epithelial and stromal cells. Secondary outcomes included endometrial tissue dating, the rate of tissues being out-of-phase and endometrial thickness. Results: Endometrial issue was obtained from 15 fertile and 30 infertile women. Expression of PgR (A + B) and PgR type-B was significantly lower in the epithelial cells of infertile women. PgR (A + B) h-score was 220.0 ± 18.5 for fertile versus 147.3 ± 18.0 for infertile women (p = 0.02). PgR type-B h-score in epithelial cells was 166.8 ± 30.7 for fertile versus 90.8 ± 20.6 for infertile (p = 0.04). No significant difference was observed in stromal cells. Conclusions: Expression levels of PgR (A + B) as well as type-B receptors are significantly lower in the epithelial cells of infertile women during implantation window.


American Journal of Reproductive Immunology | 2018

Unexplained infertility patients present the mostly impaired levels of progesterone receptors: Prospective observational study

Stamatios Petousis; Yannis Prapas; Chrysoula Margioula-Siarkou; Konstantinos Ravanos; Stefanos Milias; George Mavromatidis; Ioannis Kalogiannidis; Costas Haitoglou; Apostolos Athanasiadis; Nikolaos Prapas; David Rousso

Τo assess the endometrial expression of progesterone receptors in various subgroups of infertile women during implantation window.


Cytokine | 2017

LIF endometrial expression is impaired in women with unexplained infertility while LIF-R expression in all infertility sub-groups

Chrysoula Margioula-Siarkou; Yannis Prapas; Stamatios Petousis; Stefanos Milias; Konstantinos Ravanos; Themistoklis Dagklis; Ioannis Kalogiannidis; George Mavromatidis; Constantinos Haitoglou; Nikolaos Prapas; David Rousso

Abstract The main objective of our study was to study LIF and LIF‐R endometrial expression during the implantation window in the various sub‐groups of infertile women according to infertility cause. A prospective observational case‐control study was performed from March 2013 to February 2016. Infertile women consisted of the patients’ group (group 2) while fertile women were the control group (group 1). Infertile women were divided according to infertility cause in women with tubal factor (group 2a), poor ovarian reserve (group 2b), endometriosis (group 2c) and unexplained infertility (group 2d). Endometrial biopsy was performed on 7th–8th postovulatory menstrual day. Leukemia Inhibitory Factor (LIF) and LIF‐Receptor (LIF‐R) expression in epithelial and stromal cells were assessed with Immunohistochemistry (IHC). There were 20 infertile with poor ovarian reserve, 15 with tubal factor, 10 with endometriosis and 15 with unexplained infertility included in the analysis. LIF expression in patients with unexplained infertility was significantly compared with controls (P = 0.006). No significant difference was observed between patients with tubal factor, poor ovarian reserve and endometriosis compared with control group (P = 0.78, P = 0.44 and P = 0.56 respectively). Analysis of LIF‐R expression in sub‐categories of infertility indicated that expression was significantly decreased in all sub‐groups of infertility. Our study indicated impaired LIF expression levels only in women with unexplained infertility, while LIF‐R expression was impaired in all sub‐groups of infertile women. Further multicenter prospective studies should be performed in order to assess the exact etiopathogenetic role of these cytokines in the molecular background of infertility.


European Journal of Obstetrics & Gynecology and Reproductive Biology | 2018

Anatomic distribution of endometriosis: A reappraisal based on series of 1101 patients

A Audebert; Stamatios Petousis; Chrysoula Margioula-Siarkou; Konstantinos Ravanos; Nikos Prapas; Yannis Prapas

OBJECTIVE To reappraise the anatomic distribution of endometriosis lesions in cases with Superficial Implants (SI), Ovarian Endometrioma (OMA) and Deep Infiltrating Endometriosis (DIE). MATERIALS AND METHODS A prospective observational study was operated between January 1989 to June 2009. A total of 1333 consecutive patients with a laparoscopic diagnosis of endometriosis, were extracted from our database. Due to missing data or repeated operations, 232 patients were excluded from the study. Finally, 1101 patients who met the selected criteria were included in the present analysis.. Primary outcome of study was the anatomic location of endometriotic lesions. Secondary outcomes were laterality of lesions as well as location of adhesions. RESULTS Mean age of patients was 33.06 years (range 15-63 years) while the mean BMI was 21.5. The ovary was the most frequent site of endometriotic lesions (737 patients, 66.94%) followed by the utero-sacral ligaments (USL) (45.51%), the ovarian fossa (32.15%), the pouch of Douglas (29.52%) and the bladder (21.25%). Deep Infiltrating Endometriosis (DIE) was diagnosed in 159 patients (14.4%) with an increasing rate starting from the mid-nineties. The left side was predominant for all locations except fromr ovarian SI and fallopian tube, but for this latter location the number of cases was limited. 600 (54.4%) patients had adhesions wjth the adnexa being the most frequent site of location (47.4%). CONCLUSIONS Ovary was the main site of endometriotic lesions followed by the utero sacral ligaments. Left side was predominant for all locations except for ovarian SI and fallopian tube. The diagnosis of DIE has constantly being increased since mid-nineties. The large cohort of patients included in the study has strengthened previous reported data.


Molecular Medicine Reports | 2016

LIF and LIF‑R expression in the endometrium of fertile and infertile women: A prospective observational case‑control study

Chrysoula Margioula‑Siarkou; Yannis Prapas; Stamatios Petousis; Stefanos Milias; Konstantinos Ravanos; Ioannis Kalogiannidis; George Mavromatidis; Constantinos Haitoglou; Nikolaos Prapas; David Rousso


Obstetrical & Gynecological Survey | 2018

Declining Sperm Counts… or Rather Not? A Mini Review

Konstantinos Ravanos; Stamatios Petousis; Chrysoula Margioula-Siarkou; Achilleas Papatheodorou; Yannis Panagiotidis; Nikos Prapas; Yannis Prapas


Journal of Assisted Reproduction and Genetics | 2017

GnRH antagonist administered twice the day before hCG trigger combined with a step-down protocol may prevent OHSS in IVF/ICSI antagonist cycles at risk for OHSS without affecting the reproductive outcomes: a prospective randomized control trial

Yannis Prapas; Konstantinos Ravanos; Stamatios Petousis; Yannis Panagiotidis; Achilleas Papatheodorou; Chrysoula Margioula-Siarkou; Assunta Iuliano; Giuseppe Gullo; Nikos Prapas


European Journal of Obstetrics & Gynecology and Reproductive Biology | 2016

Endometrial expression of Leukemia Inhibitory Factor (LIF), LIF-receptor and HOXA-11 but not HOXA-10 is significantly impaired in women with unexplained infertility during implantation window

Chrysoula Margioula-Siarkou; Stamatios Petousis; Stefanos Milias; Konstantinos Ravanos; Ioannis Kalogiannidis; George Mavromatidis; Constantinos Haitoglou; Yannis Prapas; Nikolaos Prapas; David Rousso

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Yannis Prapas

Aristotle University of Thessaloniki

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Stamatios Petousis

Aristotle University of Thessaloniki

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Chrysoula Margioula-Siarkou

Aristotle University of Thessaloniki

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Nikolaos Prapas

Aristotle University of Thessaloniki

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David Rousso

Aristotle University of Thessaloniki

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Ioannis Kalogiannidis

Aristotle University of Thessaloniki

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Constantinos Haitoglou

Aristotle University of Thessaloniki

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George Mavromatidis

Aristotle University of Thessaloniki

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Nikos Prapas

Aristotle University of Thessaloniki

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Yannis Panagiotidis

Democritus University of Thrace

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