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  • Author: Michal Jeseta x
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Endocrine disruptive compounds and male reproduction

Abstract

Endocrine disruptors (EDs) are chemical substances that affect physiological processes in the organism via hormonal regulation. The EDs are present in the environment and objects of everyday use. They are often detected in food, particularly released from packaging of canned food, but also from plastic water bottles, and they are also found in cosmetics and fertilizers. They are commonly detected in children's toys, banknotes, receipts and many more objects. Permanent and long-term utilization of EDs has harmful effects on human reproductive health mainly by interference with sex hormone synthesis and mechanism of action. The endocrine disruptors show many negative effects on male reproductive system. Any change during synthesis or activity of sex hormones can cause abnormal reproduction, including developmental anomalies of the sexual system, disruption of testicular development or deterioration of sperm quality. Mainly the impact on the development of testicles in prenatal and early postnatal period can be crucial for reproductive health in males. This review provides an overview of the EDs and their possible impact on reproductive health in males with focus on sperm quality and development of testicles.

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Genes regulating programmed cell death are significantly upregulated in porcine immature oocytes

Abstract

Correct maturation of the oocyte is crucial for further fertilization and embryogenesis. It comprises of both nuclear and cytoplasmic maturation, during which the proteins, nutrients and mRNAs are assembled. Cumulus cells are connected with the oocyte via gap-junctions, which enable bi-directional transfer of molecules, forming cumulus-oocyte complex (COC). The expression pattern in CCs is thought to resemble the genes expressed in the oocyte. The CCs surrounding the gamete of high developmental competence have an increased expression of apoptotic markers. Therefore, our aim in this study was to determine whether any apoptosis-related genes are upregulated in porcine oocytes before or after IVM. We isolated COCs from 45 pubertal crossbred gilts, performed brilliant cresyl blue (BCB) staining and analyzed the gene expression pattern in oocytes before and after IVM with the use of microarray analysis. The results include 419 differentially expressed transcripts, 25 of which belong to „regulation of apoptosis” and „regulation of cell death” GO BP terms. This set of genes includes BCLAF1, EIF2AK3, KLF10, MIF, MAP3K1, NOTCH2, TXNIP and APP, all of which have been upregulated in immature porcine oocytes. Our results suggest that they play part in porcine oocyte maturation and could be used as potential markers of female gamete’s developmental competence. This knowledge could serve as a basis to improve ART in pigs.

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Current Topics in Assisted Reproduction in the Czech Republic

Abstract

Assisted reproduction is a very dynamic part of reproductive gynaecology with fast changes in therapeutic approaches resulting from intensive research supported by private or public companies. This progress brings also new questions regarding ethical, legal or therapeutic issues. At the 26th Czech-Slovak symposium of assisted reproduction in Brno, several interesting topics of assisted reproduction were presented. During two days, more than 350 specialists discussed current topics related to gynaecology, embryology, andrology, genetics and sexology. From this fruitful discussion we chose the following topics that we consider to be the most important: (1) “Soft” versus “standard” stimulation protocols for IVF (2) Use of exogenous and endogenous progestins in IVF stimulation protocols (3) Cryopreservation and transplantation of ovarian tissue - state of the art and situation in the Czech Republic (4) Selection of spermatozoa with fragmented DNA: practical recommendations (5) Artificial activation of oocytes (8) Access of single and lesbian women to assisted reproduction technologies and possibility of their reproduction in the Czech Republic. Panel conclusions were presented at the end of the conference, which had great attendance, invoked lively commentaries and produced some definitive consensus. Certain issues remained inconclusive and these matters will be the subject of further discussion in future. This is a summary of the most important theses from this field in the Czech Republic in 2017.

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Resveratrol and Its Analogues – Is It a New Strategy of Anticancer Therapy?

Summary

Resveratrol (RSV) is one of the polyphenols - metabolites common in plants,however it does not occur in animals. It occurs mainly in grape skin (Vitisvinifera), peanuts (Arachis hypogeal) and in the roots of (Polygonumcupidatum) a traditional Chinese curative plant.

RSV has a preventive property against the most serious diseases of modern world such as cancer, neurodegenerative diseases and cardiovascular diseases. Due to pleiotropy, RSV is currently the main object of many research teams′ interest, which is shown by the significant number of publications devoted to this subject.

Animal and human conducted studies have shown very low bioavailability of RSV (approx. 2%), which is the result of rapid biotransformation to sulphate and to a lesser extent, to the glucuronide conjugates as well. The studies on the improvement of RSV bioavailability, which have beencarried out for many years, have contributed to the synthesis of the analogues of more chemopreventive and more desirable pharmacokinetic properties. In order to enhance antiproliferative activity and RSV bioavailability, series of methyl analogues were synthesized and this will be described later in more detail. An example of such a derivative is DMU-212 (3,4,4’5-tetramethoxystilbene).

Open access
Endocrine disruptors: General characteristics, chemical nature and mechanisms of action. A review.

Abstract

Over recent decades, different types of industrially manufactured chemicals have become widespread environmental contaminants with potential to interfere with the synthesis, secretion, transport, binding or elimination of natural hormones in the body. These chemical substances were named endocrine disruptors (EDs). The main route of exposure to EDs is the ingestion of contaminated food and water. EDs are very dangerous, because they have long half-life, stay present in the environment for years and may concentrate at great distances from the site where were produced. The group of EDs is heterogeneous and contains industrial lubricants, solvents, plastics, plasticizers, pesticides, fungicides, drugs, but also natural chemicals. The mechanisms of EDs action are difficult to predict, many substances act by interfering with the estrogen receptors (ER), androgen receptor (AR), thyroid receptors (TRs) and aryl hydrocarbon receptor (AhR), but they can also influence hormone synthesis or can have effect on epigenetic mechanisms. Further research is necessary to improve knowledge about EDs and their metabolites, and to identify endocrine-disruptive potential of chemicals, those replacing current EDs before they are widely distributed.

Open access
Recent Findings of the Types of Programmed Cell Death

Summary

Cell death plays an important role in maintaining the homeostasis of multicellular organisms. It can occur in a controlled manner by apoptosis or autophagy. Cell death which occurs regardless of regulatory factors include necrosis, mitotic catastrophe or oncosis.

Apoptosis and necrosis are cellular process that leads to cell death. However their mechanisms are different, although factors triggering them can be similar. Necrosis and apoptosis have many different characteristics in terms of biochemistry and morphology.

There are two main pathways of apoptosis induction signal: receptor - dependent and mitochondrial. The outsider apoptotic pathway is induced by external factors stimulating membrane receptors having an intracellular domain called death domain.

Mitochondrial apoptotic pathway is activated by increased concentration of reactive oxygen species (ROS), DNA damage, disorders electrolyte transport and an increase in the concentration of the calcium ions in the cytoplasm. In response to stress-factors, mitochondrial channels are opened, so that is released into the cytoplasm cytochrome C. This work is aimed at an overall description of exchanged processes.

Open access
Magnetic-Activated Cell Sorting in Combination with Swim-Up Efficiency Improve Effectivity of Spermatozoa Separation

Abstract

Correct selection of spermatozoa before their using for an assisted reproductive techniques is one of the crucial step in therapy of human infertility. It was previously reported that male factor plays a major role in infertility. Basic semen analyses and standard methods for sperm selection in many cases does not eliminate sufficiently proportion of spermatozoa with genetics defects. Magnetic Activated Cell Sorting (MACS) is a selection method which reduce apoptotic sperm and improve sperm and embryo quality. The aim of our study was the comparison of swim-up method and MACS and their combination. We tested swim-up and MACS alone and treatment of spermatozoa in combination when was is first swim-up and second MACS and vice versa. In this study we evaluated sperm concentration, motility and their DNA integrity before and after separtion methods. On the basis of our results we recommend to use swim-up before MACS method. This approach brings better results in the sperm selection - lower proportion of spermatozoa with fragmented DNA and also it brings better gain of total spermatozoa usable for next IVF or ICSI methods.

Open access
Characteristic of factors influencing the proper course of folliculogenesis in mammals

Abstract

Folliculogenesis is the process of ovarian follicle formation,, taking presence during foetal period. During the follicular development, oogoniums undergo meiosis and oocytes are formed. In the ovaries of new born sows, primary and secondary follicles are present and, 90 days after birth, tertiary follicles appear. During development in the ovarian follicles growth of granulosa cells and differentiation of the thecal cells can be observed. A cavity filled with follicular fluid appears. Granulosa cells are divided into: mural cells and corona radiata, which together with the oocyte form the cumulus oophorus. Corona radiata cells, mural layers and oolemma contact each other by a network of gap junctions. Secreted from the pituitary gland, FSH and LH gonadotropin hormones act on receptors located in granular and follicular cells. In the postnatal life tertiary follicles and Graafian follicles are formed. When the follicle reaches a diameter of 1 mm, further growth depends on the secretion of gonadotropins. Mature ovarian follicles produce: progestins, androgens and oestrogens. The growth, differentiation and steroidogenic activity of ovarian follicles, in addition to FSH and LH, is also affected by prolactin, oxytocin, steroid and protein hormones, numerous proteins from the cytokine and interleukin family, metabolic hormones like insulin, glucocorticoids, leptin, thyroid hormones and growth hormones. Despite numerous studies, many processes related to folliculogenesis have not been discovered Learning the mechanisms regulating reproductive processes would allow to easily distinguish pathological processes and discover more and more genes and mechanisms of their expression in cells that build ovarian follicles.

Open access
Pathogenesis and pathophysiology of ovarian follicular cysts in mammals

Abstract

Ovarian cysts remain to be one of the most common and serious problems in reproduction of farm animals, as well as humans. Apart from causing the fall in reproductive potential of the ovaries, occupying the place in which folliculogenesis and oogenesis occur, they also cause hormone imbalances, by preventing corpus luteum formation, hence lowering the amount of steroid hormone production. While singular cysts rarely affect fertility, hormone fluctuations that are associated with their presence promotes their multiplication, which usually has more adverse effects. While the cysts are easily detectable in humans, possessing distinct echography while examined by ultrasound, multiple factors prevent widespread use of effective detection methods among large herds of farm animals. Because of lack of noticeable symptoms of early stages of such malignancies, they rarely get detected before the animal stops to exhibit symptoms of heat. That causes scientific research to be focused on not only methods of detection, but also the ways to negate the effects of ovarian cysts and bring the affected specimen back to reproductive potential. Despite that, high costs of diagnosis and treatment, cause them to be uncommon on commercial farms. As lack of fertility eliminates animals from breeding purposed herds, ovarian cysts persist as a cause of large losses of the animal husbandry business. Continuous research, focused on natural examples of ovarian cysts should be conducted, in order to improve methods of detection, prevention, treatment and recovery from the effects of ovarian cysts.

Open access
Protein oligomerization is the biochemical process highly up-regulated in porcine oocytes before in vitro maturation (IVM)

Abstract

A wide variety of mechanisms controlling oligomerization are observed. The dynamic nature of protein oligomerization is important for bioactivity control. The oocyte must undergo a series of changes to become a mature form before it can fully participate in the processes associated with its function as a female gamete. The growth of oocytes in the follicular environment is accompanied by surrounding somatic cumulus (CCs) and granulosa cells (GCs). It has been shown that oocytes tested before and after in vitro maturation (IVM) differ significantly in the transcriptomic and proteomic profiles. The aim of this study was to determine new proteomic markers for the oligomerization of porcine oocyte proteins that are associated with cell maturation competence. The Affymetrix microarray assay was performed to examine the gene expression profile associated with protein oligomerization in oocytes before and after IVM. In total, 12258 different transcriptomes were analyzed, of which 419 genes with lower expression in oocytes after IVM. We found 9 genes: GJA1, VCP, JUP, MIF, MAP3K1, INSR, ANGPTL4, EIF2AK3, DECR1, which were significantly down-regulated in oocytes after IVM (in vitro group) compared to oocytes analyzed before IVM (in vivo group). The higher expression of genes involved in the oligomerization of the protein before IVM indicates that they can be recognized as important markers of biological activation of proteins necessary for the further growth and development of pig embryos.

Open access