Irma Virant-Klun

Irma Virant-Klun


Research Focus & Metrics

Academic Career Length

32Years (1995-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 July 2014 in Human Reproduction
Verified
Journal Article
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MKM. S. Kupka
M. S. Kupka
AFA. P. Ferraretti
A. P. Ferraretti
JMJ. de Mouzon
J. de Mouzon
JCJ. A. Castilla
J. A. Castilla
VGV. Goossens
V. Goossens
T(The European Ivf-Monitoring (Eim)
The European Ivf-Monitoring (Eim)
The 14th European IVF—monitoring (EIM) report presents the results of medically assisted reproduction treatments including assisted reproductive technology (ART) cycles and intrauterine insemination (IUI) cycles initiated in Europe during 2010: are there changes in the trends compared with previous years? Despite some fluctuations in the number of countries reporting, the overall number of ART cycles has continued to increase year by year, and while pregnancy rates in 2010 remained similar to those reported in 2009, the number of transfers with multiple embryos (three or more) further declined. Since 1997, ART data in Europe have been collected and reported in 13 manuscripts, published in Human Reproduction. Retrospective collection of European ART data by the EIM Consortium for ESHRE; data were collected from cycles started between 1st January and 31st December 2010 by the National Registries of individual European countries, or on a voluntary basis by personal information for European countries without a national registry. Out of 31 countries, 991 clinics reported 550 296 ART treatment cycles: IVF (125 994), ICSI (272 771), frozen embryo replacement (FER, 114 593), egg donation (ED, 25 187), in vitro maturation (493), preimplantation genetic diagnosis/preimplantation genetic screening (6399) and frozen oocyte replacements (4859). European data on IUI using husband/partner's semen (IUI-H) or donor semen (IUI-D) were reported from 22 and 19 countries, respectively. A total of 176 512 IUI-H (+8.4% compared with 2009) and 38 124 IUI-D (+30.4% compared with 2009) cycles were included. In 16 countries where all clinics reported to the national ART registry, a total of 267 120 ART cycles were performed in a population of 219 million inhabitants, corresponding to 1221 cycles per million inhabitants. For IVF, the clinical pregnancy rates per aspiration and per transfer increased to 29.2 and 33.2%, respectively, and for ICSI, the corresponding rates also increased to 28.8 and 32.0%, when compared with the rates of 2009. In FER cycles, the pregnancy rate per thawing was 20.3%; in ED cycles the pregnancy rate per fresh transfer was 47.4% and per thawed transfer 33.3%. The delivery rate after IUI-H was 8.9 and 13.8% after IUI-D. In IVF and ICSI cycles, one, two, three and four or more embryos were transferred in 25.7, 56.7, 16.1 and 1.5%, respectively. The proportions of singleton, twin and triplet deliveries after IVF and ICSI (combined) were 79.4, 19.6 and 1.0%, respectively, resulting in a total multiple delivery rate of 20.6% compared with 20.2% in 2009, 21.7% in 2008, 22.3% in 2007, 20.8% in 2006. In FER cycles, the multiple delivery rate was 12.8% (12.5% twins and 0.3% triplets). Twin and triplet delivery rates associated with IUI cycles were 9.6/0.5 and 8.5/0.2%, following treatment with husband and donor semen, respectively. The method of reporting is not standardized in Europe but varies among countries. Furthermore registries from a number of countries have been unable to provide some of the relevant data such as initiated cycles and deliveries. Therefore, results should be interpreted with caution. The 14th ESHRE report on ART and IUI treatments shows a continuing expansion of the number of ART treatment cycles in Europe, with more than half a million of cycles reported in 2010. The use of ICSI may have reached a plateau. When compared with 2009/2008, pregnancy and (multiple) delivery rates after IVF and ICSI remained relatively stable. The number of multiple embryo transfers (three or more embryos) has shown a decline. The study has no external funding; all costs are covered by ESHRE. There are no competing interests.

1 August 2016 in Molecular & Cellular Proteomics
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Journal Article
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IVIrma Virant-Klun
Irma Virant-Klun
SLStefan Leicht
Stefan Leicht
CHChristopher Hughes
Christopher Hughes
Jeroen KrijgsveldJeroen Krijgsveld
Jeroen Krijgsveld
Oocytes undergo a range of complex processes via oogenesis, maturation, fertilization, and early embryonic development, eventually giving rise to a fully functioning organism. To understand proteome composition and diversity during maturation of human oocytes, here we have addressed crucial aspects of oocyte collection and proteome analysis, resulting in the first proteome and secretome maps of human oocytes. Starting from 100 oocytes collected via a novel serum-free hanging drop culture system, we identified 2,154 proteins, whose function indicate that oocytes are largely resting cells with a proteome that is tailored for homeostasis, cellular attachment, and interaction with its environment via secretory factors. In addition, we have identified 158 oocyte-enriched proteins (such as ECAT1, PIWIL3, NLRP7)1 not observed in high-coverage proteomics studies of other human cell lines or tissues. Exploiting SP3, a novel technology for proteomic sample preparation using magnetic beads, we scaled down proteome analysis to single cells. Despite the low protein content of only ∼100 ng per cell, we consistently identified ∼450 proteins from individual oocytes. When comparing individual oocytes at the germinal vesicle (GV) and metaphase II (MII) stage, we found that the Tudor and KH domain-containing protein (TDRKH) is preferentially expressed in immature oocytes, while Wee2, PCNA, and DNMT1 were enriched in mature cells, collectively indicating that maintenance of genome integrity is crucial during oocyte maturation. This study demonstrates that an innovative proteomics workflow facilitates analysis of single human oocytes to investigate human oocyte biology and preimplantation development. The approach presented here paves the way for quantitative proteomics in other quantity-limited tissues and cell types. Data associated with this study are available via ProteomeXchange with identifier PXD004142.

1 October 2008 in Differentiation
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Journal Article
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IVIrma Virant-Klun
Irma Virant-Klun
NZNicolas Zech
Nicolas Zech
PRPrimož Rožman
Primož Rožman
AVAndrej Vogler
Andrej Vogler
BCBranko Cvjetičanin
Branko Cvjetičanin
HMHelena Meden-Vrtovec
Helena Meden-Vrtovec

21 November 2019 in Journal of Assisted Reproduction and Genetics
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JBJure Bedenk
Jure Bedenk
EVEda Vrtačnik-Bokal
Eda Vrtačnik-Bokal
IVIrma Virant-Klun
Irma Virant-Klun

1 January 2009 in Stem Cells and Development
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Journal Article
Closed access
IVIrma Virant-Klun
Irma Virant-Klun
PRPrimož Rožman
Primož Rožman
BCBranko Cvjeticanin
Branko Cvjeticanin
EVEda Vrtacnik-Bokal
Eda Vrtacnik-Bokal
SNSrdjan Novakovic
Srdjan Novakovic
HMHelena Meden-Vrtovec
Helena Meden-Vrtovec
Little is known about parthenogenesis in the human ovary. What is known is related to patients with teratoma in their medical history. Ovarian surface epithelium (OSE) was often proposed as a source of ovarian stem cells with an embryonic character in the past, and was also termed “germinal epithelium.” The aim of this study was to isolate putative stem cells from OSE scrapings, to set up an OSE cell culture, to follow the in vitro oogenesis and possible formation of parthenogenetic embryos in 21 postmenopausal women with no naturally present follicles and oocytes. Small round cells with a bubble-like structure and with a diameter from 2 to 4 μm were isolated from the material obtained by OSE scrapings in all women. They expressed early embryonic developmental markers such as stage-specific embryonic antigen-4 (SSEA-4) surface antigen and Oct-4, Nanog, Sox-2, and c-kit transcription factors. These cells were separated by density gradient centrifugation and grown in vitro, where they proliferated and formed embryoid body-like structures. Their markers of pluripotency such as telomerase activity were decreased during in vitro culture and they did not form teratoma after the injection into SCID mice. Some of them grew intensively and reached a diameter of approximately 20 μm after 5–7 days of culture. In the OSE cell culture, oocyte-like cells developed among them, which reached a diameter up to 95 μm, and expressed Oct-4, c-kit, VASA, and ZP2 transcription markers after 20 days of culture. Some of them expressed a zona pellucida-like structure and rarely germinal vesicle- and polar body-like structures. At the same time, parthenogenetic blastocyst-like structures developed, which expressed transcription markers Oct-4, Sox-2, and Nanog and were normal for chromosomes X, Y, 13, 16, 18, 21, and 22. In conclusion, the discovered cells expressed embryonic stem cell markers, gave rise to embryoid body-, oocyte-, and blastocyst-like structures, and might be involved in the human reproduction and formation of ovarian tumors.

1 July 2002 in Journal of Assisted Reproduction and Genetics
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Journal Article
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IVIrma Virant-Klun
Irma Virant-Klun
TTTomaz Tomazevic
Tomaz Tomazevic
HMHelena Meden-Vrtovec
Helena Meden-Vrtovec