Free radicals and birth defects

OXIDATIVE STRESS AND REPRODUCTIVE FUNCTION: Reactive oxygen species in the mammalian pre-implantation embryo

In brief

Reactive oxygen species are generated throughout the pre-implantation period and are necessary for normal embryo formation. However, at pathological levels, they result in reduced embryo viability which can be mediated through factors delivered by sperm and eggs at conception or from the external environment.

Abstract

Reactive oxygen species (ROS) occur naturally in pre-implantation embryos as a by-product of ATP generation through oxidative phosphorylation and enzymes such as NADPH oxidase and xanthine oxidase. Biological concentrations of ROS are required for crucial embryonic events such as pronuclear formation, first cleavage and cell proliferation. However, high concentrations of ROS are detrimental to embryo development, resulting in embryo arrest, increased DNA damage and modification of gene expression leading to aberrant fetal growth and health. In vivo embryos are protected against oxidative stress by oxygen scavengers present in follicular and oviductal fluids, while in vitro, embryos rely on their own antioxidant defence mechanisms to protect against oxidative damage, including superoxide dismutase, catalase, glutathione and glutamylcysteine synthestase. Pre-implantation embryonic ROS originate from eggs, sperm and embryos themselves or from the external environment (i.e. in vitro culture system, obesity and ageing). This review examines the biological and pathological roles of ROS in the pre-implantation embryo, maternal and paternal origins of embryonic ROS, and from a clinical perspective, we comment on the growing interest in combating increased oxidative damage in the pre-implantation embryo through the addition of antioxidants.

Pathogenesis of Congenital Malformations: Possible Role of Oxidative Stress

OBJECTIVE

Congenital anomalies are important causes of morbidity and mortality in children. Oxidative stress (OS) is involved in the physiopathology of pregnancy-related congenital malformations. This review summarizes the role of OS in the pathogenesis of congenital malformations; in particular, its purpose is to describe how OS influences the development of heart congenital malformations, oesophageal atresia, biliary atresia, diaphragmatic hernia, and autosomal dominant polycystic kidney disease.

STUDY DESIGN

Systematic review of previous studies about the role of OS in pregnancy and its possible effects in developing of congenital malformations. One electronic database (PubMed) was searched and reference lists were checked.

RESULTS

An imbalance between the production of reactive oxygen species (ROS) and antioxidant defense can occur early in pregnancy and continue in the postnatal life, producing OS. It may destroy the signaling pathways needed for a correct embryogenesis leading to birth defects. In fact, cell functions, especially during embryogenesis, needs specific signaling pathways to regulate the development. These pathways are sensitive to both endogenous and exogenous factors; therefore, they can produce structural alterations of the developing fetus.

CONCLUSION

Because OS plays a significant role in pathogenesis of congenital malformations, studies should be developed in order to better define their OS mechanisms and the beneficial effects of supplemental therapeutic strategies.

KEY POINTS

· Oxidative stress is involved in the pathogenesis of congenital malformations.. · Heart malformations, oesophageal atresia, biliary atresia, diaphragmatic hernia, and autosomal dominant polycystic kidney are analyzed.. · A knowledge of pathomechanism of OS-related congenital malformations could be useful to prevent them..

Oxidative stress induces meiotic defects of oocytes in a mouse psoriasis model

Psoriasis, an immune-mediated inflammatory disease, is associated with poor pregnancy outcomes. Emerging evidence indicates that these defects are likely attributed to compromised oocyte competence. Nevertheless, little is known about the underlying associated mechanisms between psoriasis and poor oocyte quality. In this study, we construct an imiquimod-induced chronic psoriasis-like mouse model to review the effects of psoriasis on oocyte quality. We discover that oocytes from psoriasis-like mice display spindle/chromosome disorganization, kinetochore-microtubule mis-attachment, and aneuploidy. Importantly, our results show that melatonin supplement in vitro and in vivo not only increases the rate of matured oocytes but also significantly attenuates oxidative stress and meiotic defects by restoring mitochondrial function in oocytes from psoriasis-like mice. Altogether, our data uncover the adverse effects of psoriasis symptoms on oocytes, and melatonin supplement ameliorates oxidative stress and meiotic defects of oocytes from psoriatic mice.

Diet and Maternal Obesity Are Associated with Increased Oxidative Stress in Newborns: A Cross-Sectional Study

Overweight and obesity have become a world-health public problem, mainly for developing countries. Both health conditions have a higher prevalence among women of childbearing age. Physiopathology, overweight and obesity are characterized by a chronic oxidative stress status, which has deleterious effects on mothers and children. Hence, we determine whether the qualities of diet during pregnancy and maternal pregestational body mass index (BMI) are associated with increased oxidative stress markers in mothers and newborns. Two hundred forty-two (242) mother-newborn pairs were classified according to their pregestational BMI. Information on food intake was collected using a food frequency questionnaire in the third trimester of pregnancy. Levels of Malondialdehyde (MDA) and Nitric Oxide (NO) were measured in plasma from mothers at the end of the third trimester of pregnancy and from cord blood at birth. MDA and NO levels in mother–newborn pairs with maternal pregestational overweight or obesity were higher than in mother–newborn pairs with pregestational normal weight. For women (and newborns) who had a higher intake of fruit and vegetables, the levels of NO and MDA were lower. Lastly, women with pregestational obesity had lower fruit and vegetable intake during pregnancy and higher levels of oxidative stress and in their newborns.

Hemoglobin: potential roles in the oocyte and early embryo†

Hemoglobin (Hb) is commonly known for its capacity to bind and transport oxygen and carbon dioxide in erythroid cells. However, it plays additional roles in cellular function and health due to its capacity to bind other gases including nitric oxide. Further, Hb acts as a potent antioxidant, quenching reactive oxygen species. Despite its potential roles in cellular function, the preponderance of Hb research remains focused on its role in oxygen regulation. There is increasing evidence that Hb expression is more ubiquitous than previously thought, with Hb and its variants found in a myriad of cell types ranging from macrophages to spermatozoa. The majority of nonerythroid cell types that express Hb are situated within hypoxic environments, suggesting Hb may play a role in hypoxia-inducible factor-regulated gene expression by controlling the level of oxygen available or as an adaptation to low oxygen providing a mechanism to store oxygen. Oocyte maturation and preimplantation embryo development occur within the low oxygen environments of the antral follicle and oviduct/uterus, respectively. Interestingly, Hb was recently found in human cumulus and granulosa cells and murine cumulus-oocyte complexes and preimplantation embryos. Here, we consolidate and analyze the research generated todate on Hb expression in nonerythroid cells with a particular focus on reproductive cell types. We outline future directions of this research to elucidate the role of Hb during oocyte maturation and preimplantation embryo development and finally, we explore the potential clinical applications and benefits of Hb supplementation during the in vitro culture of gametes and embryos.

Ameliorating Effects of Natural Antioxidant Compounds on Female Infertility: a Review

The prevalence of female infertility cases has been increasing at a frightening rate, affecting approximately 48 million women across the world. However, oxidative stress has been recognized as one of the main mediators of female infertility by causing various reproductive pathologies in females such as endometriosis, PCOS, preeclampsia, spontaneous abortion, and unexplained infertility. Nowadays, concerned women prefer dietary supplements with antioxidant properties over synthetic drugs as a natural way to lessen the oxidative stress and enhance their fertility. Therefore, the current review is an attempt to explore the efficacy of various natural antioxidant compounds including vitamins, carotenoids, and plant polyphenols and also of some medicinal plants in improving the fertility status of females. Our summarization of recent findings in the current article would pave the way toward the development of new possible antioxidant therapy to treat infertility in females. Natural antioxidant compounds found in fruits, vegetables, and other dietary sources, alone or in combination with other antioxidants, were found to be effective in ameliorating the oxidative stress-mediated infertility problems in both natural and assisted reproductive settings. Numerous medicinal plants showed promising results in averting the various reproductive disorders associated with female infertility, suggesting a plant-based herbal medicine to treat infertility. Although optimum levels of natural antioxidants have shown favorable results, however, their excessive intake may have adverse health impacts. Therefore, larger well-designed, dose-response studies in humans are further warranted to incorporate natural antioxidant compounds into the clinical management of female infertility.

Severity of prepregnancy diabetes on the fetal malformations and viability associated with early embryos in rats†

Preexisting/pregestational diabetes enhances the risk of birth defects. Several factors have been involved during the implantation process, such as cytokines (granulocyte-macrophage-colony-stimulating factor [GM-CSF]). The objective was to evaluate the effects of two levels of diabetes on the redox status of preimplantation embryos during the implantation process to comprehend how both are involved in embryo and fetal viability against maternal diabetes. Female Sprague-Dawley rats received streptozotocin at birth (mild diabetes [MD]) or at adulthood (severe diabetes [SD]) to obtain two experimental diabetes intensities. After confirming the diabetic status, the nondiabetic and diabetic groups were mated around day 110 of life. At gestational day (GD) 21, fetuses were assessed for viability and malformations and ovaries for embryo loss before implantation. Other pregnant nondiabetic and diabetic rats were sacrificed at GD2-4 for maternal and preimplantation embryo oxidative stress markers, maternal serum insulin, uterine fluid GM-CSF, and preimplantation embryo morphological analysis. MD and SD caused abnormal redox levels, lower GM-CSF and insulin levels during the preimplantation period, and embryonic loss before implantation. SD caused lower fetal viability and higher fetal malformation percentages at GD21. The SD dam-derived preimplantation embryos presented lower glutathione levels and higher thiobarbituric acid reactive substances concentration at GD3 and an increased frequency of abnormal preimplantation embryos at GD4. In conclusion, preexisting diabetes leads to complications in the implantation process. Furthermore, maternal oxidative stress and other metabolic changes alter the redox state and morphological structure of preimplantation embryos, contributing to damaged growth and development in late pregnancy.

Review on the role of glutathione on oxidative stress and infertility

Infertility is a global health problem and it is one of the most stressful conditions amongst married couples. Even though not lethal, it has been described as a radical life changing problem that carries with it significant psychological trauma. Infertility can be caused by various problems and sometimes it is not possible to establish a cause. Oxidative stress, which arises from an imbalance between reactive oxygen species (ROS) and protective antioxidants, influences the entire reproductive lifespan of men and women. ROS can modulate cellular functions, and oxidative stress can disturb the intracellular milieu, resulting in diseased cells or endanger cell survival. Under normal conditions, antioxidants act to oppose ROS production, scavenging existing free radicals and promoting the repair of ROS-induced damage to cell structures. At controlled levels, oxidative stress facilitates some physiological reproductive functions but at higher levels it is implicated in pathological processes in the reproductive tract that contribute to infertility and poor pregnancy outcomes. As high levels of reactive oxygen species and low antioxidant status have been implicated in conditions contributing to infertility, treatment based on strategies to boost the exhausted antioxidant defense of the reproductive microenvironment is intuitive. Glutathione is a natural body antioxidant, which helps preserve all other antioxidants. It is present in both the male and female gametes and its level varies widely. This study reviews the role oxidative stress plays in both male and female infertility, and the antioxidant action of glutathione on infertility.

Long-term consequences of obesity on female fertility and the health of the offspring

PURPOSE OF REVIEW

Obesity has reached near epidemic levels among reproductive age women with a myriad of consequences. Obesity adversely affects the maternal milieu by creating conditions that decrease fertility and increase the risk of gestational diabetes, hypertensive disease in pregnancy, fetal growth abnormalities and congenital anomalies. The effects of obesity are not limited to pregnancy. Indeed, beyond the immediate postpartum period, obese women maintain a higher prevalence of insulin resistance and cardiovascular disease. In this article, we will review the pathophysiology underlying the effects of obesity on fertility, pregnancy outcome and health status of offspring. The purpose of this review is to outline proposed models responsible for the short-term and long-term consequences of obesity on fertility and offspring development, and identify knowledge gaps where additional research is needed.

RECENT FINDINGS

Maternal over or under nutrition adversely affect maternal reproductive capacity and pregnancy success. Separate from effects on maternal reproductive function, maternal over or under nutrition may also 'program' fetal pathophysiology through inheritance mechanisms that suggest epigenetic modification of DNA, differential RNA translation and protein expression, or modification of the fetal hypothalamic-pituitary axis function through programmed adverse effects on the developing hypothalamic circuitry. The concept of maternal health modifying the risk of developing noncommunicable diseases in the offspring is based on Developmental Origins of Health and Disease hypothesis.

SUMMARY

Of importance, the long-term effects of obesity are not limited to maternal health, but also programs pathophysiology in their offspring. Children of obese gravida are at increased risk for the development of cardiometabolic disease in childhood and throughout adulthood. Future studies directly interrogating mechanisms underlying the risks associated with obesity will allow us to develop interventions and therapies to decrease short-term and long-term morbidities associated with maternal obesity.

Amniotic fluid oxidant-antioxidant status in foetal congenital nervous system anomalies

Objective

This study aimed to evaluate the oxidant–antioxidant status of amniotic fluid in pregnant women with foetal congenital malformations of the central nervous system.

Methods

We studied pregnant women with foetal congenital nervous system anomalies at 16–22 weeks’ gestation (n = 36). The control group (n = 30) consisted of pregnant women at the same gestational age who underwent amniocentesis, resulting in a normal karyotype. We analysed glutathione, catalase, and malondialdehyde levels in amniotic fluid. Enzyme activation was measured by spectrophotometry.

Results

The demographic features of the groups were similar in terms of age, parity, body mass index, and gestational weeks. We detected lower glutathione and catalase levels in the foetal congenital anomaly group than in the control group. We detected higher malondialdehyde levels in the foetal congenital anomaly group than in the control group.

Conclusion

In the organism, the rate of formation of free radicals and their rate of removal are balanced, and this is called oxidative balance. As long as oxidative stability is achieved, the organism is not affected by free radicals. This fact should be kept in mind to avoid any type of teratogenic agent that could lead to congenital disorders.

Reevaluation of Antioxidative Strategies for Birth Defect Prevention in Diabetic Pregnancies

Diabetes mellitus in early pregnancy is the most severe maternal disease that is counted for 10% of newborn infants with structural defects. With the rapid increases in the number of diabetic women in childbearing age, the birth defect rate is projected to elevate dramatically. Thus, prevention of embryonic malformations becomes an urgent task. Animal studies have revealed an involvement of oxidative stress in diabetic embryopathy and treatment with antioxidants can reduce embryonic abnormalities. However, the failure of clinical trials using free radical-scavenging antioxidants to alleviate oxidative stress-related diseases prompts researchers to reevaluate the strategy in birth defect prevention. Hyperglycemia also disturbs other intracellular homeostasis, generating aberrant conditions. Perturbed folding of newly synthesized proteins causes accumulation of unfolded and misfolded proteins in the lumen of the endoplasmic reticulum (ER). The ER under the stress activates signaling cascades, known as unfolded protein response, to suppress cell mitosis and/or trigger apoptosis. ER stress can be ameliorated by chemical chaperones, which promote protein folding. Hyperglycemia also stimulates the expression of nitric oxide (NO) synthase 2 (NOS2) to produce high levels of NO and reactive nitrogen species and augment protein nitrosylation and nitration, resulting in nitrosative stress. Inhibition of NOS2 using inhibitors has been demonstrated to reduce embryonic malformations in diabetic animals. Therefore, targeting ER and nitrosative stress conditions using specific agents to prevent birth defects in diabetic pregnancies warrant further investigations. Simultaneously targeting multiple stress conditions using combined agents is a potentially effective and feasible approach.

Amelioration of intracellular stress and reduction of neural tube defects in embryos of diabetic mice by phytochemical quercetin

Diabetes mellitus in early pregnancy causes birth defects, including neural tube defects (NTDs). Hyperglycemia increases production of nitric oxide (NO) through NO synthase 2 (Nos2) and reactive oxygen species (ROS), generating nitrosative and oxidative stress conditions in the embryo. The present study aimed to target nitrosative stress using a naturally occurring Nos2 inhibitor, quercetin, to prevent NTDs in the embryos of diabetic mice. Daily administration of quercetin to diabetic pregnant mice during the hyperglycemia-susceptible period of organogenesis significantly reduced NTDs and cell apoptosis in the embryos, compared with those of vehicle-treated diabetic pregnant mice. Using HPLC-coupled ESI-MS/MS, quercetin metabolites, including methylated and sulfonylated derivatives, were detected in the conceptuses. The methylated metabolite, 3-O-methylquercetin, was shown to reduce ROS level in embryonic stem cells cultured in high glucose. Quercetin treatment decreased the levels of Nos2 expression, protein nitrosylation, and protein nitration, alleviating nitrosative stress. Quercetin increased the expression of superoxide dismutase 1 and 2, and reduced the levels of oxidative stress markers. Expression of genes of redox regulating enzymes and DNA damage repair factors was upregulated. Our study demonstrates that quercetin ameliorates intracellular stresses, regulates gene expression, and reduces embryonic malformations in diabetic pregnancy.

Effects of catechins on litter size, reproductive performance and antioxidative status in gestating sows

This study was conducted to investigate the effects of catechins on reproductive performance, antioxidative capacity and immune function of gestating sows. A total of 60 cross-bred (Landrace × Large White) multiparious sows were blocked by body weight, parity and backfact and randomly allocated to 1 of 5 treatments: 0, 100, 200, 300, or 400 mg/kg catechins. Dietary treatments were imposed from mating to d 40 of gestation of sows. At farrowing, litter total born, born alive, dead, and normal-(healthy piglets, ≥0.85 kg) and low-birth weight piglets (<0.85 kg) were recorded. Within 3.00 ± 0.50 days after farrowing litter size was standardized to 8.00 ± 1.50 piglets within treatment. The piglets were weighed at birth (d 1) and weaning (d 28). Sows serum samples were obtained from blood samples collected on d 40 of gestation for analyses of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), hydrogen peroxide (H₂O₂), nitric oxide synthetase (NOS) and nitrogen monoxide (NO). Our results showed that supplementation of catechins at levels of 200 or 300 mg/kg led to improvements in litter born alive (P < 0.01) and piglet born healthy (P < 0.01) and a decrease in stillborn (P < 0.05) at farrowing when compared with the control. In comparison with the control, catechins at any supplemental levels all enhanced the serum SOD (P < 0.05) and CAT (P < 0.01) activities of sows at farrowing but no obvious differences in the serum GSH-Px and NOS activities were observed in this trial (P > 0.05). Sows received 200 mg catechin per kg diets showed a reduction (P < 0.05) of the serum MDA level at farrowing compared with all other treatments. Sows received all the levels of catechin showed a reduction (P < 0.05) of serum H₂O₂ level compared with sows received the control diet on both d 40 of gestation and farrowing. Our results demonstrated that the catechins may be a potential antioxidant to increase the reproductive performance and antioxidative capacity of sows when it was added into diets during the early gestation.

Free radicals and antioxidants status in neonates with congenital malformation

Background:

Several studies using animal models have shown that oxidative stress during pregnancy may play an important role in causing birth defects. Congenital anomalies affect an estimated 270,000 newborns who die during the first 28 days of life every year from different birth defects. Hence, at present many research works are going on to reduce the infant mortality from congenital anomaly.[1]

Objective:

The objective was to measure the oxidant and antioxidant level in the serum of newborn babies with the congenital anomaly and compare these levels with age and sex matched normal neonates. This is to identify any role of oxidative stress in the causation of congenital anomaly.

Materials and Methods:

This case-control study included 159 participants: 106 newborns with the congenital anomaly and 53 healthy newborns. The markers of oxidative stress like serum malondialdehyde (MDA) level, protein carbonyl (PC) level, and the activity of antioxidants such as Vitamin C, glutathione were measured in both cases (neonates with congenital anomaly) and controls (normal healthy neonates). These parameters were statistically compared.

Results:

MDA levels and PC levels were significantly higher (P < 0.0001), and Vitamin C and reduced glutathione levels were significantly lower (P < 0.0001), in newborns with congenital malformation than in healthy newborns. Conclusions: Increased lipid peroxidation and protein carbonylation might play an important role in the pathogenesis of congenital anomaly. Impairment of the free radical/antioxidant balance is leading to increased free radical damage in neonates with congenital malformation.

Impact of retinoic acid exposure on midfacial shape variation and manifestation of holoprosencephaly in Twsg1 mutant mice

Holoprosencephaly (HPE) is a developmental anomaly characterized by inadequate or absent midline division of the embryonic forebrain and midline facial defects. It is believed that interactions between genes and the environment play a role in the widely variable penetrance and expressivity of HPE, although direct investigation of such effects has been limited. The goal of this study was to examine whether mice carrying a mutation in a gene encoding the bone morphogenetic protein (BMP) antagonist twisted gastrulation (Twsg1), which is associated with a low penetrance of HPE, are sensitized to retinoic acid (RA) teratogenesis. Pregnant Twsg1(+/-) dams were treated by gavage with a low dose of all-trans RA (3.75 mg/kg of body weight). Embryos were analyzed between embryonic day (E)9.5 and E11.5 by microscopy and geometric morphometric analysis by micro-computed tomography. P19 embryonal carcinoma cells were used to examine potential mechanisms mediating the combined effects of increased BMP and retinoid signaling. Although only 7% of wild-type embryos exposed to RA showed overt HPE or neural tube defects (NTDs), 100% of Twsg1(-/-) mutants exposed to RA manifested severe HPE compared to 17% without RA. Remarkably, up to 30% of Twsg1(+/-) mutants also showed HPE (23%) or NTDs (7%). The majority of shape variation among Twsg1(+/-) mutants was associated with narrowing of the midface. In P19 cells, RA induced the expression of Bmp2, acted in concert with BMP2 to increase p53 expression, caspase activation and oxidative stress. This study provides direct evidence for modifying effects of the environment in a genetic mouse model carrying a predisposing mutation for HPE in the Twsg1 gene. Further study of the mechanisms underlying these gene-environment interactions in vivo will contribute to better understanding of the pathogenesis of birth defects and present an opportunity to explore potential preventive interventions.

Maternal lifestyle factors in pregnancy and congenital heart defects in offspring: review of the current evidence

The prognosis of children with congenital heart defects(CHDs) continues to improve with advancing surgical techniques; however, lack of information about modifiable risk factors for malformations in cardiovascular development impeded the prevention of CHDs. We investigated an association between maternal lifestyle factors and the risk of CHDs, because epidemiological studies have reported conflicting results regarding maternal lifestyle factors and the risk of CHDs recently. A review published on 2007 provided a summary of maternal exposures associated with an increased risk of CHDs. As part of noninherited risk factors, we conducted a brief overview of studies on the evidence linking common maternal lifestyle factors, specifically smoking, alcohol, illicit drugs, caffeine, body mass index and psychological factors to the development of CHDs in offspring. Women who smoke and have an excessive body mass index(BMI) during pregnancy are suspected to be associated with CHDs in offspring. Our findings could cause public health policy makers to pay more attention to women at risk and could be used in the development of population-based prevention strategies to reduce the incidence and burden of CHDs. However, more prospective studies are needed to investigate the association between maternal lifestyle factors and CHDs.

Maternal diet supplementation with methyl donors and increased parity affect the incidence of craniofacial defects in the offspring of twisted gastrulation mutant mice

Diets rich in methyl-donating compounds, including folate, can provide protection against neural tube defects, but their role in preventing craniofacial defects is less clear. Mice deficient in Twisted gastrulation (TWSG1), an extracellular modulator of bone morphogenetic protein signaling, manifest both midline facial defects and jaw defects, allowing study of the effects of methyl donors on various craniofacial defects in an experimentally tractable animal model. The goal of this study was to examine the effects of maternal dietary supplementation with methyl donors on the incidence and type of craniofacial defects among Twsg1(-/-) offspring. Nulliparous and primiparous female mice were fed an NIH31 standard diet (control) or a methyl donor supplemented (MDS) diet (folate, vitamin B-12, betaine, and choline). Observed defects in the pups were divided into those derived mostly from the first branchial arch (BA1) (micrognathia, agnathia, cleft palate) and midline facial defects in the holoprosencephaly spectrum (cyclopia, proboscis, and anterior truncation). In the first pregnancy, offspring of mice fed the MDS diet had lower incidence of BA1-derived defects (12.8% in MDS vs. 32.5% in control; P = 0.02) but similar incidence of midline facial defects (6.4% in MDS vs. 5.2% in control; P = 1.0). Increased maternal parity was independently associated with increased incidence of craniofacial defects after adjusting for diet (from 37.7 to 59.5% in control, P = 0.04 and from 19.1 to 45.3% in MDS, P = 0.045). In conclusion, methyl donor supplementation shows protective effects against jaw defects, but not midline facial defects, and increased parity can be a risk factor for some craniofacial defects.

Neural tube defects and maternal intake of micronutrients related to one-carbon metabolism or antioxidant activity

BACKGROUND

Maternal nutritional status has been evaluated to clarify its role in development of neural tube defects (NTDs). Maternal folate intake during pregnancy has been closely evaluated for its association with NTDs. The study objective was to examine associations between NTDs and other dietary periconceptional micronutrient intake, particularly nutrients involved in one-carbon metabolism or antioxidant activity.

METHODS

Using data from the National Birth Defects Prevention Study, 1997-2005, logistic regression models were used to estimate the relative risk of NTDs based on maternal micronutrient intake.

RESULTS

Results were stratified according to folic acid supplement use, race/ethnicity, and maternal body mass index. Analyses included 954 cases (300 with anencephaly, 654 with spina bifida) and 6268 controls. Higher intakes of folate, thiamin, betaine, iron, and vitamin A were associated with decreased risk of anencephaly among some ethnic and clinical groups. In some groups, higher intakes of thiamin, riboflavin, vitamin B(6) , vitamin C, vitamin E, niacin, and retinol were associated with decreased risk of spina bifida.

CONCLUSION

In addition to folic acid, other micronutrients, including thiamin, betaine, riboflavin, vitamin B(6) , vitamin C, vitamin E, niacin, iron, retinol, and vitamin A, may decrease the risk of NTD occurrence. Birth Defects Research (Part A) 2012. © 2012 Wiley Periodicals, Inc.

Modeling autism: a systems biology approach

Autism is the fastest growing developmental disorder in the world today. The prevalence of autism in the US has risen from 1 in 2500 in 1970 to 1 in 88 children today. People with autism present with repetitive movements and with social and communication impairments. These impairments can range from mild to profound. The estimated total lifetime societal cost of caring for one individual with autism is $3.2 million US dollars. With the rapid growth in this disorder and the great expense of caring for those with autism, it is imperative for both individuals and society that techniques be developed to model and understand autism. There is increasing evidence that those individuals diagnosed with autism present with highly diverse set of abnormalities affecting multiple systems of the body. To this date, little to no work has been done using a whole body systems biology approach to model the characteristics of this disorder. Identification and modelling of these systems might lead to new and improved treatment protocols, better diagnosis and treatment of the affected systems, which might lead to improved quality of life by themselves, and, in addition, might also help the core symptoms of autism due to the potential interconnections between the brain and nervous system with all these other systems being modeled. This paper first reviews research which shows that autism impacts many systems in the body, including the metabolic, mitochondrial, immunological, gastrointestinal and the neurological. These systems interact in complex and highly interdependent ways. Many of these disturbances have effects in most of the systems of the body. In particular, clinical evidence exists for increased oxidative stress, inflammation, and immune and mitochondrial dysfunction which can affect almost every cell in the body. Three promising research areas are discussed, hierarchical, subgroup analysis and modeling over time. This paper reviews some of the systems disturbed in autism and suggests several systems biology research areas. Autism poses a rich test bed for systems biology modeling techniques.

Reduction in embryonic malformations and alleviation of endoplasmic reticulum stress by nitric oxide synthase inhibition in diabetic embryopathy

Maternal diabetes-induced neural tube defects (NTDs) are associated with increased programmed cell death (apoptosis) in the neuroepithelium, which is related to intracellular nitrosative stress. To alleviate nitrosative stress, diabetic pregnant mice were fed via gavage an inhibitor of nitric oxide (NO) synthase (NOS) 2, L-N6-(1-iminoethyl)-lysine (L-NIL; 80 mg/kg), once a day from embryonic (E) day 7.5 to 9.5 during early stages of neurulation. The treatment significantly reduced NTD rate in the embryos, compared with that in vehicle (normal saline)-treated diabetic group. In addition to alleviation of nitrosative stress, endoplasmic reticulum (ER) stress was also ameliorated, assessed by quantification of associated factors. Apoptosis was reduced, indicated by caspase 8 activation. These results show that nitrosative stress is important in diabetes-induced NTDs via exacerbating ER stress, leading to increased apoptosis. Oral treatment with NOS-2 inhibitor alleviates nitrosative and ER stress, decreases apoptosis, and reduces NTDs in the embryos, providing information for further interventional studies to reduce diabetes-associated birth defects.

The essential role of protein kinase Cδ in diabetes-induced neural tube defects

BACKGROUND

Maternal diabetes causes neural tube defects (NTDs) in the embryos via activating protein kinase Cs (PKCs), which regulate programmed cell death (apoptosis). The aims of this study are to investigate the role of proapoptotic PKCδ in NTD formation and the underlying mechanisms.

METHODS

PKCδ heterozygous (pkcδ(+/-)) female mice were diabetic (DM) induced by intravenous injection of streptozotocin. Occurrence of NTDs was evaluated at embryonic day 11.5 and compared between wild type (WT) and PKCδ homozygous (pkcδ(-/-)) embryos. Changes in oxidative and endoplasmic reticulum (ER) stress-associated factors and stress-response c-Jun N-terminal kinases (JNKs) were assessed using Western blot assay.

RESULTS

Compared to DM/WT, the DM/PKCδ(-/-) embryos had significantly lower NTD rate and lower levels of oxidative and ER stress factors and JNK activation. These values were similar to those in the non-diabetic control group.

CONCLUSION

PKCδ plays a critical role in diabetes-induced NTDs, potentially through increasing oxidative and ER stress and JNK-associated stress-response pathways.

Linkage study of embryopathy-polygenic inheritance of diabetes-induced skeletal malformations in the rat

We developed an inbred rat model of diabetic embryopathy, in which the offspring displays skeletal malformations (agnathia or micrognathia) when the mother is diabetic, and no malformations when she is not diabetic. Our aim was to find genes controlling the embryonic maldevelopment in a diabetic environment. We contrasted the fetal outcome in inbred Sprague-Dawley L rats (20% skeletal malformations in diabetic pregnancy) with that of inbred Wistar Furth rats (denotedW, no skeletal malformations in diabetic pregnancy). We used offspring from the backcross F(1)×L to probe for the genetic basis for malformation of the mandible in diabetic pregnancy. A set of 186 fetuses (93 affected, 93 unaffected) was subjected to a whole genome scan with 160 micro satellites. Analysis of genotype distribution indicated 7 loci on chromosome 4, 10 (3 loci), 14, 18, and 19 in the teratogenic process (and 14 other loci on 12 chromosomes with less strong association to the malformations), several of which contained genes implicated in other experimental studies of diabetic embryopathy. These candidate genes will be scrutinized in further experimentation. We conclude that the genetic involvement in rodent diabetic embryopathy is polygenic and predisposing for congenital malformations.

Endoplasmic reticulum stress in maternal diabetes-induced cardiac malformations during critical cardiogenesis period

BACKGROUND

Cardiac abnormalities, including atrioventricular (AV) septal defects (AVSDs), are the most common birth defects in diabetic embryopathy. The AV septum is derived from the endocardial cushions, which undergo development and remodeling during septation. The impact of maternal diabetes on these processes needs to be identified. Maternal diabetes disturbs the function of the endoplasmic reticulum (ER). The role of ER stress in cardiac malformation remains to be delineated to gain information for developing therapy.

METHODS

Female mice were induced diabetic via intravenous injection of streptozotocin. Pregnant mice were made hyperglycemic at desired embryonic (E) days. AVSDs were examined histologically at E15.5. ER stress-associated factors were examined and quantified using immunohistochemical and immunoblot assays at E10.5. The role of ER stress in endocardial cell migration was investigated by treating endocardial cushion explants that were cultured in high glucose with an organic chaperone molecule, sodium 4-phenylbutyrate.

RESULTS

The rate of AVSDs in the embryos that were exposed to maternal hyperglycemia during the period of endocardial cushion development was significantly higher than that in those during endocardial cushion remodeling. ER stress was increased in the hearts. Amelioration of ER stress restored endocardial cell migration under hyperglycemic conditions.

CONCLUSIONS

The development, rather than remodeling, of the endocardial cushions is the cardiomorphogenic process that is susceptible to the insult of maternal hyperglycemia in the formation of AVSDs. Maternal diabetes increases ER stress in the developing heart. ER stress plays an essential role in mediating the effect of hyperglycemia on endocardial cell migration.

Periconceptional nutrient intakes and risks of neural tube defects in California

BACKGROUND

This study investigated the association of neural tube defects (NTDs) with maternal periconceptional intake of folic acid-containing supplements and dietary nutrients, including folate, among deliveries that occurred after folic acid fortification in selected California counties.

METHODS

The population-based case-control study included fetuses and live born infants with spina bifida (189) or anencephaly (141) and 625 nonmalformed, live born controls delivered from 1999 to 2003. Mothers reported supplement use during telephone interviews, which included a 107-item food frequency questionnaire. For dietary nutrients, intakes <25th, 25th to <75th (reference), and > or =75th percentile were compared, based on control distributions.

RESULTS

After adjustment for potential confounders, any versus no supplement intake resulted in ORs of 0.8 (95% CI, 0.5-1.3) for anencephaly and 0.8 (95% CI, 0.6-1.2) for spina bifida. After stratification by maternal intake of vitamin supplements, most factors in the glycemic pathway were not associated with either NTD, with the exception of low levels of fructose and glucose that were significantly associated with anencephaly. Some nutrients that contribute to one-carbon metabolism showed lowered risks (folate, riboflavin, vitamins B(6) and B(12)); others did not (choline, methionine, zinc). Antioxidant nutrients tended to be associated with lowered risks (vitamins C, E, A, beta-carotene, lutein).

CONCLUSIONS

Mothers' intake of vitamin supplements was modestly if at all associated with a lowered risk of NTDs. Dietary intake of several nutrients contributing to one-carbon metabolism and oxidative stress were associated with reduced NTD risk.

Cardiac malformations and alteration of TGFbeta signaling system in diabetic embryopathy

BACKGROUND

Cardiovascular defects are the most common anomalies in diabetic embryopathy. The mechanisms underlying the manifestation of the defects remain to be addressed.

METHODS

Female mice were administered streptozotocin to induce diabetes. Embryos from euglycemic (control) and hyperglycemic groups were examined for morphological and histological evaluation of malformations. Cell proliferation and programmed cell death (apoptosis) were assessed using mitotic markers (BrdU and Ki67) and TUNEL assay, respectively. Expression of eight four genes in the TGFbeta signaling system was analyzed using real-time RT-PCR.

RESULTS

Structural abnormalities were observed in the heart and neural tube in diabetic groups, with significantly higher malformation rates than in control groups. Moreover, malformation rates in the heart were higher than those in the neural tube. Cardiac abnormalities including dilated heart tube, smaller ventricles, conotruncal stenosis, and abnormal heart looping were seen during early morphogenesis prior to cardiac septation [embryonic day (E) 9.5-11.5]. Histological examinations showed hypoplastic myocardium and endocardial cushions. After cardiac septation (E15.5), ventricular septal defects were observed, which were manifested in the non-muscular portion of the septum. Significant decreases in cell proliferation with no differences in apoptosis were observed in the myocardium and endocardial cushions in diabetic compared to control groups. Factors in the TGFbeta signaling that regulate heart development were downregulated by maternal diabetes.

CONCLUSIONS

Maternal diabetes causes malformations in the heart of the embryo. The heart is more susceptible to maternal diabetic insults than the neural tube. Malformations in the heart prior to septation are associated with decreased cell proliferation, but not increased apoptosis. The TGFbeta signaling is involved in cardiac malformations in diabetic embryopathy.

Lipid-soluble vitamins A, D, and E in HIV-infected pregnant women in Tanzania

BACKGROUND/OBJECTIVES

There is limited published research examining lipid-soluble vitamins in human immunodeficiency virus (HIV)-infected pregnant women, particularly in resource-limited settings.

SUBJECTS/METHODS

This is an observational analysis of 1078 HIV-infected pregnant women enrolled in a trial of vitamin supplementation in Tanzania. Baseline data on sociodemographic and anthropometric characteristics, clinical signs and symptoms, and laboratory parameters were used to identify correlates of low plasma vitamin A (<0.7 micromol/l), vitamin D (<80 nmol/l) and vitamin E (<9.7 micromol/l) status. Binomial regression was used to estimate risk ratios and 95% confidence intervals.

RESULTS

Approximately 35, 39 and 51% of the women had low levels of vitamins A, D and E, respectively. Severe anemia (hemoglobin <85 g/l; P<0.01), plasma vitamin E (P=0.02), selenium (P=0.01) and vitamin D (P=0.02) concentrations were significant correlates of low vitamin A status in multivariate models. Erythrocyte Sedimentation Rate (ESR) was independently related to low vitamin A status in a nonlinear manner (P=0.01). The correlates of low vitamin D status were CD8 cell count (P=0.01), high ESR (ESR >81 mm/h; P<0.01), gestational age at enrollment (nonlinear; P=0.03) and plasma vitamins A (P=0.02) and E (P=0.01). For low vitamin E status, the correlates were money spent on food per household per day (P<0.01), plasma vitamin A concentration (nonlinear; P<0.01) and a gestational age <16 weeks at enrollment (P<0.01).

CONCLUSIONS

Low concentrations of lipid-soluble vitamins are widely prevalent among HIV-infected women in Tanzania and are correlated with other nutritional insufficiencies. Identifying HIV-infected persons at greater risk of poor nutritional status and infections may help inform design and implementation of appropriate interventions.

Upper control limit of reactive oxygen species in follicular fluid beyond which viable embryo formation is not favorable

Though the role of reactive oxygen species (ROS) in female infertility has been a subject of rigorous research worldwide, there is inadequate information on the cut-off value of ROS in the oocyte microenvironment beyond which ART outcome may be adversely affected. An upper ROS level in follicular fluid (FF) samples of women undergoing IVF beyond which good quality embryo formation is unlikely, is established. ROS, lipid peroxidation and total antioxidant capacity were estimated. The upper cut-off ROS level beyond which viable embryo formation is not favorable was found to be approximately 107 cps/400 microl FF. This level, determined in women with tubal factor infertility, was further validated in women with endometriosis and PCOS and correlated with fertilization and pregnancy rate and embryo quality. Summarizing, a threshold level in FF has been established for the first time beyond which ROS may be considered toxic for viable embryo formation and pregnancy outcome.

Serum levels of TNF-alpha and antioxidant enzymes and placental TNF-alpha expression in unexplained recurrent spontaneous miscarriage

It has been proposed that many factors have been implicated in the pathogenesis of unexplained recurrent spontaneous miscarriage (URSM). The objective of this study was to evaluate the levels of some antioxidants, tumor necrosis factor-alpha (TNF-alpha), luteinizing (LH) and follicle-stimulating hormone (FSH) in URSM. Serum levels of superoxide dismutase (SOD), catalase (CAT), LH, FSH as well as TNF-alpha in serum and the expression of TNF-alpha positive cells in placental tissues, were assayed in women suffering from unexplained first trimester miscarriage. Two groups were included, the first was represented by 16 women with URSM (number of abortions: 3-5) and the second one included 24 women with URSM (number of abortions > 5). The control groups included 20 women within their first trimester of pregnancy and 20 non pregnant healthy females within their follicular phase. The obtained results showed a highly significant decrease in serum levels of SOD and CAT, in the URSM groups compared to control groups (p < 0.05 for each comparison). Higher serum levels of TNF-alpha were detected in URSM groups compared to control groups (p < 0.05 for each comparison). A significant increase in serum levels of LH was encountered between URSM groups compared to control groups; on the other hand the mean levels of FSH expressed no significant changes among URSM groups as compared to first trimester pregnancies control group. A positive correlation was noticed between serum levels of TNF-alpha and the levels of LH (p < 0.05). We conclude that antioxidant enzymes (CAT, SOD), TNF-alpha, LH and FSH may play a major role in the pathogenesis of URSM. Much more work is required before the mechanisms, which lead to RSM, can be fully understood.

Nutrient pathways and neural tube defects: a semi-Bayesian hierarchical analysis

BACKGROUND

We used conventional and hierarchical logistic regression to examine the association of neural tube defects (NTDs) with intake of 26 nutrients that contribute to the mechanistic pathways of methylation, glycemic control, and oxidative stress, all of which have been implicated in NTD etiology. The hierarchical approach produces more plausible, more stable estimates than the conventional approach, while adjusting for potential confounding by other nutrients.

METHODS

Analyses included 386 cases and 408 nonmalformed controls with complete data on nutrients and potential confounders (race/ethnicity, education, obesity, and intake of vitamin supplements) from a population-based case-control study of deliveries in California from 1989 to 1991. Nutrients were specified as continuous, and their units were standardized to have a mean of zero and standard deviation (SD) of 1 for comparability of units across pathways. ORs reflect a 1-SD increase in the corresponding nutrient.

RESULTS

Among women who took vitamin supplements, semi-Bayesian hierarchical modeling results suggested no associations between nutrient intake and NTDs. Among women who did not take supplements, both conventional and hierarchical models (HM) suggested an inverse association between lutein intake and NTD risk (HM odds ratio [OR] = 0.6; 95% confidence interval = 0.5-0.9) and a positive association with sucrose (HM OR 1.4; 1.1-1.8) and glycemic index (HM OR 1.3; 1.0-1.6).

CONCLUSIONS

Our findings for lutein, glycemic index, and sucrose suggest that further study of NTDs and the glycemic control and oxidative stress pathways is warranted.

Congenital anomalies in diabetic pregnancy

Congenital malformations are more common in infants of diabetic women than in children of non-diabetic women. The etiology, pathogenesis and prevention of the diabetes-induced malformations have spurred considerable clinical and basic research efforts. The ultimate aim of these studies has been to obtain an understanding of the teratogenic process, which may enable precise preventive therapeutic measures in diabetic pregnancies. The results of the clinical and basic studies support the view of an early gestational induction of the malformations in diabetic pregnancy by a teratogenic process of multifactorial etiology. There may be possible targets for new therapeutic efforts revealed by the research work. Thus, future additions to the therapeutic efforts may include supplementation with antioxidants and/or folic acid, although more research is needed to delineate the dosages and compounds to be used. As the research into genetic predisposition for the teratogenic induction of malformations by maternal diabetes starts to reveal new genes and gene products involved in the etiology of the malformations, a set of new targets for intervention may arise.

Wnt signaling in caudal dysgenesis and diabetic embryopathy

BACKGROUND

Congenital defects are a major complication of diabetic pregnancy, and the leading cause of infant death in the first year of life. Caudal dysgenesis, occurring up to 200-fold more frequently in children born to diabetic mothers, is a hallmark of diabetic pregnancy. Given that there is also an at least threefold higher risk for heart defects and NTDs, it is important to identify the underlying molecular mechanisms for aberrant embryonic development.

METHODS

We have investigated gene expression in a transgenic mouse model of caudal dysgenesis, and in a pharmacological model using situ hybridization and quantitative real-time PCR.

RESULTS

We identified altered expression of several molecules that control developmental processes and embryonic growth.

CONCLUSIONS

The results from our models point towards major implication of altered Wnt signaling in the pathogenesis of developmental anomalies associated with embryonic exposure to maternal diabetes.

Placental oxidative stress alters expression of murine osteogenic genes and impairs fetal skeletal formation

Fetal and placental developments rely on an intricate balance of nutrients, growth factors, and signaling pathways at precise times in gestation. Disruptions to this balance may result in disease that manifests in adulthood, a situation termed "developmental origins of health and disease". Diet, exercise, and certain chemical exposures during pregnancy increase oxidative stress (OS), and may alter trajectory of fetal osteogenic regulation in a manner that increases risk of adult bone dysfunction. The present study used gestational methylnitrosourea (MNU), a known inducer of OS, in C57BL/6 mice with or without dietary antioxidant quercetin (Q) supplementation. Several key placental genes that influence placental development and fetal osteogenesis (Hgf, Kitl, IFNalpha4, Ifrd, and IL-1beta) were altered by MNU, and largely normalized by Q. MNU treatment also resulted in small fetuses with disproportionately shortened limbs and distal limb malformations, and caused placental endothelial and trophoblast damage. Q was again protective against these fetal and placental pathologies. An unanticipated finding with Q supplementation was increased interdigital webbing, perhaps due to dose-related effects on apoptosis required for digital sculpting, or pro-oxidant effects of Q that caused a maturational delay. These results suggest that elevated OS may alter normal placental osteogenic signaling and fetal skeletal formation.

TNFalpha in the pathogenesis of diabetes-induced embryopathies: functions and targets

Hyperglycemia-induced increase in the production of reactive oxygen species (ROS) is proposed to be an initial step in the pathogenesis of diabetes-induced spontaneous abortions and structural inborn anomalies. However, the subsequent steps in this process are incompletely understood. One of the key molecules involved is tumor necrosis factor-alpha (TNFalpha): its expression is regulated by ROS and it regulates ROS production in turn. This cytokine has been the focus of many studies addressing the mechanisms of different forms of diabetes-induced embryopathies, such as early pregnancy loss, inborn anomalies, fetal growth retardation as well as some pathologies appearing during adult life. In this review, we analyze the results of these studies and discuss how TNFalpha may regulate the response of pre- and post-implantation stage embryos to diabetes-induced detrimental stimuli. The data presented in this review suggest that TNFalpha may play a dual role in the pathogenesis of diabetes-induced embryopathies. It may act both as a mediator of diabetes-induced embryotoxic stimuli leading to the death of peri-implantation stage embryos and, possibly, as a suppressor of diabetes-induced apoptosis in post-implantation stage embryos. It also appears that TNFalpha fulfills these functions via interaction with leukemia inhibitory factor (LIF) and the transcription factor NF-kappaB. These molecules are presently considered as attractive targets for the treatment of diabetes-induced complications. Therefore, further studies addressing their role in the mechanisms underlying diabetes-induced embryopathies are needed to evaluate the safety of such therapies for diabetic women of childbearing age.

Differentially expressed genes in embryonic cardiac tissues of mice lacking Folr1 gene activity

BACKGROUND

Heart anomalies are the most frequently observed among all human congenital defects. As with the situation for neural tube defects (NTDs), it has been demonstrated that women who use multivitamins containing folic acid peri-conceptionally have a reduced risk for delivering offspring with conotruncal heart defects 123. Cellular folate transport is mediated by a receptor or binding protein and by an anionic transporter protein system. Defective function of the Folr1 (also known as Folbp1; homologue of human FRalpha) gene in mice results in inadequate transport, accumulation, or metabolism of folate during cardiovascular morphogenesis.

RESULTS

We have observed cardiovascular abnormalities including outflow tract and aortic arch arterial defects in genetically compromised Folr1 knockout mice. In order to investigate the molecular mechanisms underlying the failure to complete development of outflow tract and aortic arch arteries in the Folr1 knockout mouse model, we examined tissue-specific gene expression difference between Folr1 nullizygous embryos and morphologically normal heterozygous embryos during early cardiac development (14-somite stage), heart tube looping (28-somite stage), and outflow track septation (38-somite stage). Microarray analysis was performed as a primary screening, followed by investigation using quantitative real-time PCR assays. Gene ontology analysis highlighted the following ontology groups: cell migration, cell motility and localization of cells, structural constituent of cytoskeleton, cell-cell adhesion, oxidoreductase, protein folding and mRNA processing. This study provided preliminary data and suggested potential candidate genes for further description and investigation.

CONCLUSION

The results suggested that Folr1 gene ablation and abnormal folate homeostasis altered gene expression in developing heart and conotruncal tissues. These changes affected normal cytoskeleton structures, cell migration and motility as well as cellular redox status, which may contribute to cardiovascular abnormalities in mouse embryos lacking Folr1 gene activity.

Responses of mitochondrial biogenesis and function to maternal diabetes in rat embryo during the placentation period

Mitochondria are cellular organelles that have been reported to be altered in diabetes, being closely related to its associated complications. Moreover, mitochondrial biogenesis and function are essential for proper embryo development throughout the placentation period, occurring during organogenesis, when a great rate of congenital malformations have been associated with diabetic pregnancy. Thus, the aim of the current work was to investigate the effect of the diabetic environment on mitochondrial function and biogenesis during the placentation period. For this purpose, we studied the oxidative phosphorylation system (OXPHOS) enzymatic activities as well as the expression of genes involved in the coordinated regulation of both mitochondrial and nuclear genome (PGC-1alpha, NRF-1, NRF-2alpha, mtSSB, and TFAM) and mitochondrial function (COX-IV, COX-I, and beta-ATPase) in rat embryos from control and streptozotocin-induced diabetic mothers. Our results reflected that diabetic pregnancy retarded and altered embryo growth. The embryos from diabetic mothers showing normal morphology presented a reduced content of proteins regulated through the PGC-1alpha mitochondriogenic pathway on gestational day 12. This fact was accompanied by several responses that entailed the activation of OXPHOS activities on the same day and the recovery of the content of the studied proteins to control levels on day 13. As a result, the mitochondria of these embryos would reach a situation close to control on day 13 that could allow them to follow the normal mitochondriogenic schedule throughout a gestational period in which the mitochondrial differentiation process is critical. Nevertheless, malformed embryos from diabetic mothers seemed to show a lower adaptation capability, which could exacerbate their maldevelopment.

Maternal caffeine consumption and risk of cardiovascular malformations

BACKGROUND

The physiologic effects and common use of caffeine during pregnancy call for examination of maternal caffeine consumption and risk of birth defects. Epidemiologic studies have yielded mixed results, but such studies have grouped etiologically different defects and have not evaluated effect modification.

METHODS

The large sample size and precise case classification of the National Birth Defects Prevention Study allowed us to examine caffeine consumption and specific cardiovascular malformation (CVM) case groups. We studied consumption of caffeinated coffee, tea, soda, and chocolate to estimate total caffeine intake and separately examined exposure to each caffeinated beverage. Smoking, alcohol, vasoactive medications, folic acid supplement use, and infant gender were evaluated for effect modification. Maternal interview reports for 4,196 CVM case infants overall and 3,957 control infants were analyzed.

RESULTS

We did not identify any significant positive associations between maternal caffeine consumption and CVMs. For tetralogy of Fallot, nonsignificant elevations in risk were observed for moderate (but not high) caffeine intake overall and among nonsmokers (ORs of 1.3 to 1.5). Risk estimates for both smoking and consuming caffeine were less than the sum of the excess risks for each exposure. We observed an inverse trend between coffee intake and risk of atrial septal defect; however, this single significant pattern of association might have been a chance finding.

CONCLUSIONS

Our study found no evidence for an appreciable teratogenic effect of caffeine with regard to CVMs.

Antioxidant metabolism of Xenopus laevis embryos during the first days of development

Reactive oxygen species (ROS) are formed and degraded in all aerobic organisms, but their role during embryonic development has not yet been well established. In this paper, we report the activities of various enzymes involved in antioxidant metabolism during the first 7 days of embryonic development of Xenopus laevis embryos. During the first two days of development, embryo antioxidant metabolism is based on catalase and superoxide dismutase activities. Later, the glutathione system is activated, and the activity of all the enzymes involved increases. The results presented in this study, together with previously reported data, support the hypothesis that antioxidant defences may include enzymes that are genetically regulated, while the other systems that appear to be environmentally modulated become relevant later in development, probably to protect embryos from environmental and toxic factors.

Maternal Exposure to Caffeine and Risk of Congenital Anomalies

BACKGROUND

Caffeine is teratogenic in animal studies when administered at high concentrations. Previous review articles have concluded that maternal caffeine consumption does not influence the risk of congenital anomalies. These reviews were narrative rather than systematic. The objective of the current systematic review is to provide a critical appraisal of epidemiologic evidence.

METHODS

A search of the MEDLINE/PUBMED database (1966-October 2004) was conducted for all published epidemiologic studies with maternal intake of caffeine as an exposure and major malformations as an outcome. Study characteristics were abstracted, internal validity evaluated, and study findings summarized.

RESULTS

Twenty-five papers met the initial criteria for inclusion, of which 18 were subsequently excluded as a result of other limitations. Effect estimates for the remaining 7 studies were generally close to null. Specific subgroup analyses were summarized across studies (associations between coffee and cardiovascular malformations, coffee and oral clefts, and tea and cardiovascular malformations). Summary point estimates ranged from 1.0 to 1.2; the upper limits of all confidence intervals were less than 1.7.

CONCLUSIONS

There is no evidence to support a teratogenic effect of caffeine in humans. Current epidemiologic evidence is not adequate to assess the possibility of a small change in risk of congenital anomalies resulting from maternal caffeine consumption.

Experimental mechanisms of diabetic embryopathy and strategies for developing therapeutic interventions

A high frequency of birth defects is seen in infants born to diabetic mothers. The mechanisms by which maternal hyperglycemia, the major teratogenic factor, induces embryonic malformations remain to be addressed. It has been shown that increases in programmed cell death are one of the factors causing embryonic malformations. Hyperglycemia-induced apoptosis is associated with oxidative stress, lipid peroxidation, and decreased antioxidant defense capacity in the embryos. Recent studies have revealed that mitogen-activated protein kinases as intracellular signaling factors are involved in hyperglycemia-induced embryopathy. Based on the findings, interventions to prevent embryonic malformations have been explored. Strategies include supplementation of molecules that are deficient in the embryos under hyperglycemic conditions and antioxidants to alleviate the adverse effects of oxidative stress. The ultimate goal is to develop multi-nutrient dietary supplements to eliminate embryonic abnormalities induced by maternal diabetes.

Exposure to 5-Bromo-2′-deoxyuridine induces oxidative stress and activator protein-1 DNA binding activity in the embryo

BACKGROUND

During organogenesis the embryo is highly sensitive to oxidative stress. We hypothesize that oxidative stress and activation of a redox-sensitive transcription factor, activator protein-1 (AP-1), are early indicators of embryonic stress in response to a teratogenic insult. 5-Bromo-2'-deoxyuridine (BrdU) was chosen as a model teratogen to test this hypothesis; BrdU is a thymidine analog that is incorporated into replicating DNA.

METHODS

Timed pregnant CD1 mice were given vehicle or BrdU (400, 600, 800, or 1000 mg of BrdU/kg of body weight) on gestation day 9 (GD 9). Oxidative stress, assessed as the ratio of glutathione disulfide (GSSG) to reduced glutathione (GSH), and AP-1 DNA binding activity (c-Fos- and c-Jun-dependent DNA binding) were measured in the maternal livers and embryos 0.5, 3, and 6 hr after treatment. External and skeletal malformations were assessed on GD 18. N-acetylcysteine, a glutathione precursor, was coadministered with BrdU to further explore the relationship between teratogenicity and redox homeostasis.

RESULTS

BrdU exposure produced a dose-dependent increase in skeletal malformations, which included polydactyly, and delayed ossification of the sternebrae and vertebrae. Exposure to teratogenic doses of BrdU depleted GSH concentrations and increased oxidative stress, as assessed by the GSSG:GSH ratio, in both maternal livers and embryos. While c-Jun DNA binding activity in embryos was not affected, c-Fos DNA binding activity was elevated significantly 3 hr after BrdU exposure. Coadministration of N-acetylcysteine decreased the skeletal malformations and AP-1 DNA binding activity induced by BrdU.

CONCLUSIONS

BrdU exposure induced an embryonic stress response manifested as an increase in oxidative stress and AP-1 DNA binding activity; these data support the hypothesis that disturbances in redox homeostasis mediate the response of the conceptus to a teratogenic insult.

Role of oxidative stress in female reproduction

In a healthy body, ROS (reactive oxygen species) and antioxidants remain in balance. When the balance is disrupted towards an overabundance of ROS, oxidative stress (OS) occurs. OS influences the entire reproductive lifespan of a woman and even thereafter (i.e. menopause). OS results from an imbalance between prooxidants (free radical species) and the body's scavenging ability (antioxidants). ROS are a double-edged sword - they serve as key signal molecules in physiological processes but also have a role in pathological processes involving the female reproductive tract. ROS affect multiple physiological processes from oocyte maturation to fertilization, embryo development and pregnancy. It has been suggested that OS modulates the age-related decline in fertility. It plays a role during pregnancy and normal parturition and in initiation of preterm labor. Most ovarian cancers appear in the surface epithelium, and repetitive ovulation has been thought to be a causative factor. Ovulation-induced oxidative base damage and damage to DNA of the ovarian epithelium can be prevented by antioxidants. There is growing literature on the effects of OS in female reproduction with involvement in the pathophysiology of preeclampsia, hydatidiform mole, free radical-induced birth defects and other situations such as abortions. Numerous studies have shown that OS plays a role in the pathophysiology of infertility and assisted fertility. There is some evidence of its role in endometriosis, tubal and peritoneal factor infertility and unexplained infertility. This article reviews the role OS plays in normal cycling ovaries, follicular development and cyclical endometrial changes. It also discusses OS-related female infertility and how it influences the outcomes of assisted reproductive techniques. The review comprehensively explores the literature for evidence of the role of oxidative stress in conditions such as abortions, preeclampsia, hydatidiform mole, fetal embryopathies, preterm labour and preeclampsia and gestational diabetes. The review also addresses the growing literature on the role of nitric oxide species in female reproduction. The involvement of nitric oxide species in regulation of endometrial and ovarian function, etiopathogenesis of endometriosis, and maintenance of uterine quiescence, initiation of labour and ripening of cervix at parturition is discussed. Complex interplay between cytokines and oxidative stress in the etiology of female reproductive disorders is discussed. Oxidant status of the cell modulates angiogenesis, which is critical for follicular growth, corpus luteum formation endometrial differentiation and embryonic growth is also highlighted in the review. Strategies to overcome oxidative stress and enhance fertility, both natural and assisted are delineated. Early interventions being investigated for prevention of preeclampsia are enumerated. Trials investigating combination intervention strategy of vitamin E and vitamin C supplementation in preventing preeclampsia are highlighted. Antioxidants are powerful and there are few trials investigating antioxidant supplementation in female reproduction. However, before clinicians recommend antioxidants, randomized controlled trials with sufficient power are necessary to prove the efficacy of antioxidant supplementation in disorders of female reproduction. Serial measurement of oxidative stress biomarkers in longitudinal studies may help delineate the etiology of some of the diosorders in female reproduction such as preeclampsia.