Changes in concentration, localization and activity of catalase within the human placenta during early gestation
TL;DR: Results are in agreement with the proposal that the placenta exists in a physiologically low oxygen environment during the early part of gestation, and oxidative activity of the sort resulting in the generation of hydrogen peroxide would presumably be suppressed.
About: This article is published in Placenta.The article was published on 1998-01-01. It has received 78 citations till now. The article focuses on the topics: Catalase & Oxygen tension.
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TL;DR: The impact of OS on assisted reproductive techniques (ART) will be addressed, in addition to the possible benefits of antioxidant supplementation of ART culture media to increase the likelihood for ART success.
Abstract: Oxidative stress (OS), a state characterized by an imbalance between pro-oxidant molecules including reactive oxygen and nitrogen species, and antioxidant defenses, has been identified to play a key role in the pathogenesis of subfertility in both males and females. The adverse effects of OS on sperm quality and functions have been well documented. In females, on the other hand, the impact of OS on oocytes and reproductive functions remains unclear. This imbalance between pro-oxidants and antioxidants can lead to a number of reproductive diseases such as endometriosis, polycystic ovary syndrome (PCOS), and unexplained infertility. Pregnancy complications such as spontaneous abortion, recurrent pregnancy loss, and preeclampsia, can also develop in response to OS. Studies have shown that extremes of body weight and lifestyle factors such as cigarette smoking, alcohol use, and recreational drug use can promote excess free radical production, which could affect fertility. Exposures to environmental pollutants are of increasing concern, as they too have been found to trigger oxidative states, possibly contributing to female infertility. This article will review the currently available literature on the roles of reactive species and OS in both normal and abnormal reproductive physiological processes. Antioxidant supplementation may be effective in controlling the production of ROS and continues to be explored as a potential strategy to overcome reproductive disorders associated with infertility. However, investigations conducted to date have been through animal or in vitro studies, which have produced largely conflicting results. The impact of OS on assisted reproductive techniques (ART) will be addressed, in addition to the possible benefits of antioxidant supplementation of ART culture media to increase the likelihood for ART success. Future randomized controlled clinical trials on humans are necessary to elucidate the precise mechanisms through which OS affects female reproductive abilities, and will facilitate further explorations of the possible benefits of antioxidants to treat infertility.
1,071 citations
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TL;DR: In this article, the authors measured changes in the oxygen tension within the human placenta associated with onset of the maternal arterial circulation at the end of the first trimester of pregnancy, and the impact on placental tissues.
Abstract: The aim was to measure changes in the oxygen tension within the human placenta associated with onset of the maternal arterial circulation at the end of the first trimester of pregnancy, and the impact on placental tissues. Using a multiparameter probe we established that the oxygen tension rises steeply from 50 mmHg at 12 weeks. This rise coincides with morphological changes in the uterine arteries that allow free flow of maternal blood into the placenta, and is associated with increases in the mRNA concentrations and activities of the antioxidant enzymes catalase, glutathione peroxidase, and manganese and copper/zinc superoxide dismutase within placental tissues. Between 8 to 9 weeks there is a sharp peak of expression of the inducible form of heat shock protein 70, formation of nitrotyrosine residues, and derangement of the mitochondrial cristae within the syncytiotrophoblast. We conclude that a burst of oxidative stress occurs in the normal placenta as the maternal circulation is established. We speculate that this may serve a physiological role in stimulating normal placental differentiation, but may also be a factor in the pathogenesis of pre-eclampsia and early pregnancy failure if antioxidant defenses are depleted.
947 citations
11 Jul 2019
TL;DR: Gestational diabetes mellitus is the most common complication in pregnancy and has short-term and long-term effects in both mother and offspring, and dietary modification and increased physical activity are the primary treatments, but pharmacotherapy, usually insulin, is used when normoglycaemia is not achieved.
Abstract: Hyperglycaemia that develops during pregnancy and resolves after birth has been recognized for over 50 years, but uniform worldwide consensus is lacking about threshold hyperglycaemic levels that merit a diagnosis of ‘gestational diabetes mellitus’ (GDM) and thus treatment during pregnancy. GDM is currently the most common medical complication of pregnancy, and prevalence of undiagnosed hyperglycaemia and even overt diabetes in young women is increasing. Maternal overweight and obesity, later age at childbearing, previous history of GDM, family history of type 2 diabetes mellitus and ethnicity are major GDM risk factors. Diagnosis is usually performed using an oral glucose tolerance test (OGTT), although a non-fasting, glucose challenge test (GCT) is used in some parts of the world to screen women for those requiring a full OGTT. Dietary modification and increased physical activity are the primary treatments for GDM, but pharmacotherapy, usually insulin, is used when normoglycaemia is not achieved. Oral hypoglycaemic agents, principally metformin and glibenclamide (glyburide), are also used in some countries. Treatment improves immediate pregnancy outcomes, reducing excess fetal growth and adiposity and pregnancy-related hypertensive disorders. GDM increases the risk of long-term complications, including obesity, impaired glucose metabolism and cardiovascular disease, in both the mother and infant. Optimal management of mother and infant during long-term follow-up remains challenging, with very limited implementation of preventive strategies in most parts of the world. Gestational diabetes mellitus (GDM) is the most common complication in pregnancy and has short-term and long-term effects in both mother and offspring. This Primer discusses the definitions of GDM, diagnosis and management of the disease and areas requiring further research.
643 citations
TL;DR: Miscarriage, missed miscarriage, and early- and late-onset preeclampsia represent a spectrum of disorders secondary to deficient trophoblast invasion, and high levels of oxidative stress in the periphery may induce formation of the chorion laeve.
Abstract: Objective:To review the role of oxidative stress in two common placental-related disorders of pregnancy, miscarriage and preeclampsia.Methods:Review of published literature.Results:Miscarriage and ...
607 citations
TL;DR: The maternal circulation to the placenta must be extremely sluggish before the eighth week of pregnancy but will be gradually established over the next few weeks, and development of the human fetoplacental unit during most of the first trimester takes place in a low-oxygen environment.
423 citations
References
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TL;DR: A quantitative, spectrophotometric technique for following the breakdown of hydrogen peroxide has been developed for routine studies of catalase kinetics and appears to give lower values forCatalase activity than do titration techniques.
6,007 citations
TL;DR: The chapter discusses the metabolism of transition metals, such as iron and copper, and the chelation therapy that is an approach to site-specific antioxidant protection.
Abstract: Publisher Summary This chapter discusses the role of free radicals and catalytic metal ions in human disease. The importance of transition metal ions in mediating oxidant damage naturally leads to the question as to what forms of such ions might be available to catalyze radical reactions in vivo . The chapter discusses the metabolism of transition metals, such as iron and copper. It also discusses the chelation therapy that is an approach to site-specific antioxidant protection. The detection and measurement of lipid peroxidation is the evidence most frequently cited to support the involvement of free radical reactions in toxicology and in human disease. A wide range of techniques is available to measure the rate of this process, but none is applicable to all circumstances. The two most popular are the measurement of diene conjugation and the thiobarbituric acid (TBA) test, but they are both subject to pitfalls, especially when applied to human samples. The chapter also discusses the essential principles of the peroxidation process. When discussing lipid peroxidation, it is essential to use clear terminology for the sequence of events involved; an imprecise use of terms such as initiation has caused considerable confusion in the literature. In a completely peroxide-free lipid system, first chain initiation of a peroxidation sequence in a membrane or polyunsaturated fatty acid refers to the attack of any species that has sufficient reactivity to abstract a hydrogen atom from a methylene group.
5,033 citations
Book•
01 Jan 1974
TL;DR: A methodical gross examination should be undertaken in all births and the results incorporated in the patient’s record.
Abstract: A methodical gross examination should be undertaken in all births and the results incorporated in the patient’s record.
1,330 citations
Journal Article•
TL;DR: It is suggested that the increase of placental PO2 at the end of the first trimester is related to the establishment of continuous maternal blood flow in the intervillous space.
768 citations
747 citations