Ksenija Geršak

Prof. Dr. Ksenija Geršak

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Research Focus & Metrics

Academic Career Length

23Years (2004-Present)

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

Representative Publications

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28 August 2018 in PLOS ONE
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FJFranc Jager
Franc Jager
SLSonja Libenšek
Sonja Libenšek
KGKsenija Geršak
Ksenija Geršak
Predicting preterm birth is uncertain, and numerous scientists are searching for non-invasive methods to improve its predictability. Current researches are based on the analysis of ElectroHysteroGram (EHG) records, which contain information about the electrophysiological properties of the uterine muscle and uterine contractions. Since pregnancy is a long process, we decided to also characterize, for the first time, non-contraction intervals (dummy intervals) of the uterine records, i.e., EHG signals accompanied by a simultaneously recorded external tocogram measuring mechanical uterine activity (TOCO signal). For this purpose, we developed a new set of uterine records, TPEHGT DS, containing preterm and term uterine records of pregnant women, and uterine records of non-pregnant women. We quantitatively characterized contraction intervals (contractions) and dummy intervals of the uterine records of the TPEHGT DS in terms of the normalized power spectra of the EHG and TOCO signals, and developed a new method for predicting preterm birth. The results on the characterization revealed that the peak amplitudes of the normalized power spectra of the EHG and TOCO signals of the contraction and dummy intervals in the frequency band 1.0-2.2 Hz, describing the electrical and mechanical activity of the uterus due to the maternal heart (maternal heart rate), are high only during term pregnancies, when the delivery is still far away; and they are low when the delivery is close. However, these peak amplitudes are also low during preterm pregnancies, when the delivery is still supposed to be far away (thus suggesting the danger of preterm birth); and they are also low or barely present for non-pregnant women. We propose the values of the peak amplitudes of the normalized power spectra due to the influence of the maternal heart, in an electro-mechanical sense, in the frequency band 1.0-2.2 Hz as a new biophysical marker for the preliminary, or early, assessment of the danger of preterm birth. The classification of preterm and term, contraction and dummy intervals of the TPEHGT DS, for the task of the automatic prediction of preterm birth, using sample entropy, the median frequency of the power spectra, and the peak amplitude of the normalized power spectra, revealed that the dummy intervals provide quite comparable and slightly higher classification performances than these features obtained from the contraction intervals. This result suggests a novel and simple clinical technique, not necessarily to seek contraction intervals but using the dummy intervals, for the early assessment of the danger of preterm birth. Using the publicly available TPEHG DB database to predict preterm birth in terms of classifying between preterm and term EHG records, the proposed method outperformed all currently existing methods. The achieved classification accuracy was 100% for early records, recorded around the 23rd week of pregnancy; and 96.33%, the area under the curve of 99.44%, for all records of the database. Since the proposed method is capable of using the dummy intervals with high classification accuracy, it is also suitable for clinical use very early during pregnancy, around the 23rd week of pregnancy, when contractions may or may not be present.

22 December 2006 in Human Reproduction
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PFPolonca Ferk
Polonca Ferk
NTNatasa Teran
Natasa Teran
KGKsenija Geršak
Ksenija Geršak
Hyperandrogenaemia is a common feature of polycystic ovary syndrome (PCOS). The sex hormone-binding globulin (SHBG) gene was proposed as being a PCOS candidate gene. A possible influence of the microsatellite polymorphism (TAAAA)n in the SHBG gene on serum SHBG levels in PCOS patients was investigated. One hundred and twenty-three PCOS patients and 110 age-matched controls were included in the study. Peripheral blood samples were obtained. Genotyping of the (TAAAA)n polymorphism in the SHBG gene was performed. Serum LH, FSH, SHBG and total testosterone concentrations were determined. SHBG alleles with 6–11 TAAAA repeats were found. None of the SHBG alleles or genotypes were present at a significantly more frequent rate in PCOS patients compared with controls. Serum SHBG levels were significantly lower (P < 0.001) in PCOS patients compared with controls and were found to be strongly influenced by the (TAAAA)nSHBG polymorphism, in both the PCOS (55.3%) and control (33.1%) groups of patients. The (TAAAA)nSHBG gene polymorphism might be an important predictor for serum SHBG levels and, consequently, for hyperandrogenaemic clinical presentation of PCOS.

1 December 2004 in Human Reproduction
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KGKsenija Geršak
Ksenija Geršak
SHSarah E. Harris
Sarah E. Harris
WSWendy J. Smale
Wendy J. Smale
ASAndrew Shelling
Andrew Shelling
In a Slovene patient with primary amenorrhoea without an association with blepharophimosis/ptosis/epicanthus inversus syndrome (BPES), a novel 30 bp deletion was identified in the FOXL2 gene. We report the clinical features of this woman who has spontaneously conceived and delivered two live healthy babies. The novel deletion was predicted to remove 10 out of 14 alanines (A221_A230del), from the polyalanine tract downstream of the winged helix/forkhead domain of the FOXL2 protein. The patient's parents and sister were shown not to carry this deletion. Despite seeing an anovulatory secretory pattern of FSH, follicles developed spontaneously. Persistent and consistent monitoring have practical implications for genetic and fertility counselling in the era when women with premature ovarian failure usually seek ovum donation. The role of FOXL2 in the development of infertility is still unclear, but several lines of evidence suggest that it plays a central role in follicle development.

2 September 2020 in Journal of Clinical Medicine
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MGMaša Vidmar Golja
Maša Vidmar Golja
ASAlenka Smid
Alenka Smid
NKNatasa Karas-Kuzelicki
Natasa Karas-Kuzelicki
JTJurij Trontelj
Jurij Trontelj
KGKsenija Geršak
Ksenija Geršak
IMIrena Mlinaric-Rascan
Irena Mlinaric-Rascan
Adequate levels of folates are essential for homeostasis of the organism, prevention of congenital malformations, and the salvage of predisposed disease states. They depend on genetic predisposition, and therefore, a pharmacogenetic approach to individualized supplementation or therapeutic intervention is necessary for an optimal outcome. The role of folates in vital cell processes was investigated by translational pharmacogenetics employing lymphoblastoid cell lines (LCLs). Depriving cells of folates led to reversible S-phase arrest. Since 5,10-methylenetetrahydrofolate reductase (MTHFR) is the key enzyme in the biosynthesis of an active folate form, we evaluated the relevance of polymorphisms in the MTHFR gene on intracellular levels of bioactive metabolite, the 5-methyltetrahydrofolate (5-Me-THF). LCLs (n = 35) were divided into low- and normal-MTHFR activity groups based on their genotype. They were cultured in the presence of folic acid (FA) or 5-Me-THF. Based on the cells’ metabolic activity and intracellular 5-Me-THF levels, we conclude supplementation of FA is sufficient to maintain adequate folate level in the normal MTHFR activity group, while low MTHFR activity cells require 5-Me-THF to overcome the metabolic defects caused by polymorphisms in their MTHFR genes. This finding was supported by the determination of intracellular levels of 5-Me-THF in cell lysates by LC-MS/MS. FA supplementation resulted in a 2.5-fold increase in 5-Me-THF in cells with normal MTHFR activity, but there was no increase after FA supplementation in low MTHFR activity cells. However, when LCLs were exposed to 5-Me-THF, a 10-fold increase in intracellular levels of this metabolite was determined. These findings indicate that patients undergoing folate supplementation to counteract anti-folate therapies, or patients with increased folate demand, would benefit from pharmacogenetics-based therapy choices.

1 July 2009 in Reproductive Toxicology
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KGKsenija Geršak
Ksenija Geršak
MCMarta Cvijic
Marta Cvijic
LCLilijana Kornhauser Cerar
Lilijana Kornhauser Cerar