Copper-deficient rat embryos are characterized by brain and heart anomalies, low superoxide dismu... more Copper-deficient rat embryos are characterized by brain and heart anomalies, low superoxide dismutase activity, and high superoxide anion concentrations. One consequence of increased superoxide anions can be the formation of peroxynitrite, a strong biological oxidant. To investigate developmentally important features of copper deficiency, GD 8.5 mouse embryos from copper-adequate and copper-deficient dams were cultured in media that were adequate or deficient in copper. After 48 h, copper-deficient embryos exhibited brain and heart anomalies, and a high incidence of yolk sac vasculature abnormalities compared to controls. Immunohistochemistry of 4-hydroxynonenal and 8-hydroxy-2'-deoxyguanosine for lipid and DNA damage, respectively, was similar between groups. In contrast, 3-nitrotyrosine, taken as a measure of protein nitration, was markedly higher in the neuroepithelium of the anterior neural tube of copper-deficient embryos than in controls. Repletion of copper-deficient media with copper, or supplementation with copper-zinc superoxide dismutase, Tiron, or glutathione peroxidase did not ameliorate the abnormal development, but did decrease 3-nitrotyrosine in neuroepithelium of copper-deficient embryos. These data support the concept that while copper deficiency compromises oxidant defense and increases protein nitration, additional mechanisms, e.g., altered nitric oxide metabolism may contribute to copper-deficiency-induced teratogenesis.
Because glucose is an important metabolic fuel during perinatal development, the effect of restri... more Because glucose is an important metabolic fuel during perinatal development, the effect of restriction of maternal dietary glucose on the developmental profile of neonatal glucoregulatory pathways was investigated. Pregnant rats were fed isoenergetic diets (0, 12, 24 or 60% glucose) and offspring were killed at seven postpartum time periods: 0 -2, 4 - 6, 12-16 and 24 h, and 3,
Maternal nutrition can have a significant effect on developmental processes during pregnancy and ... more Maternal nutrition can have a significant effect on developmental processes during pregnancy and lactation. While certain flavonoids have been postulated to be beneficial for health, little is known about the effects of ingestion during pregnancy and lactation on the mother and progeny. We report on the effects of maternal consumption of high levels of certain flavonoids on reproductive and developmental outcomes in a mouse model. C57BL/6J female mice were fed a control diet (CT), the CT diet supplemented with 1% or 2% of a mix of epicatechin and catechin (EC1, EC2), or rutin (RU1, RU2) prior to, during pregnancy, and lactation. A subset of dams was killed on gestation day (GD) 18.5 to evaluate fetal outcomes and the remainder was allowed to deliver to evaluate offspring. Maternal food intake, body and tissue weight did not differ among groups. The number of resorptions, implantations, litter size, postnatal survival, body weight, and skeletal development were also similar. Alterations in maternal and offspring liver mineral concentrations were observed. The current results indicate that consumption of high amounts of epicatechin, catechin, and rutin during gestation and lactation is not associated with any marked developmental effects, although changes in liver mineral concentrations were noted.
Approximately 3% of infants born have at least one serious congenital malformation. In the U.S., ... more Approximately 3% of infants born have at least one serious congenital malformation. In the U.S., an average of 10 infants per thousand die before 1 y of life; about half of these deaths can be attributed to birth defects, low birth weight or prematurity. Although the causes of developmental abnormalities are clearly multifactorial in nature, we suggest that a common factor contributing to the occurrence of developmental abnormalities is suboptimal mineral nutrition during embryonic and fetal development. Using zinc and copper as examples, evidence is presented that nutritional deficiencies can rapidly affect the developing conceptus and result in gross structural abnormalities. Deficits of zinc or copper can result in rapid changes in cellular redox balance, tissue oxidative stress, inappropriate patterns of cell death, alterations in the migration of neural crest cells and changes in the expression of key patterning genes. In addition to well-recognized malformations, mineral defic...
The etiology of congenital heart disease is multifactorial, with genetics and nutritional deficie... more The etiology of congenital heart disease is multifactorial, with genetics and nutritional deficiencies recognized as causative agents. Maternal zinc (Zn) deficiency is associated with an increased risk for fetal heart malformations; however, the contributing mechanisms have yet to be identified. In this study, we fed pregnant rats a Zn-adequate diet (ZnA), a Zn-deficient (ZnD), or a restricted amount of Zn adequate diet (RF) beginning on gestation day (GD) 4.5, to examine whether increased cell death and changes in cardiac neural crest cells (NCC) play a role in Zn deficiency-induced heart defects. Fetuses were collected on GD 13.5, 15.5, and 18.5 and processed for GATA-4, FOG-2, connexin-43 (Cx43), HNK-1, smooth muscle alpha-actin (SMA) and cleaved caspase-3 protein expression. Fetuses from ZnA-fed dams showed normal heart development, whereas fetuses from dams fed with the ZnD diet exhibited a variety of heart anomalies, particularly in the region of the outflow tract. HNK-1 expre...
Numerous studies support the concept that a major cause of pregnancy complications can be subopti... more Numerous studies support the concept that a major cause of pregnancy complications can be suboptimal embryonic and fetal nutrition. Although the negative effects of diets low in energy on pregnancy outcome are well documented, less clear are the effects of diets that are low in one or more essential micronutrients. However, several observational and intervention studies suggest that diets low in essential vitamins and minerals can pose a significant reproductive risk in diverse human populations. Although maternal nutritional deficiencies typically occur as a result of low dietary intakes of essential nutrients, nutritional deficiencies at the level of the conceptus can arise through multiple mechanisms. Evidence from experimental animals supports the concept that in addition to primary deficiencies, secondary embryonic and fetal nutritional deficiencies can be caused by diverse factors including genetics, maternal disease, toxicant insults and physiological stressors that can trigg...
Numerous studies support the concept that a major cause of pregnancy complications can be subopti... more Numerous studies support the concept that a major cause of pregnancy complications can be suboptimal embryonic and fetal nutrition. Although the negative effects of diets low in energy on pregnancy outcome are well documented, less clear are the effects of diets that are low in one or more essential micronutrients. However, several observational and intervention studies suggest that diets low
Dietary glucose restriction during pregnancy can retard fetal brain development, lower term brain... more Dietary glucose restriction during pregnancy can retard fetal brain development, lower term brain glycogen levels and adversely affect the serotonergic neurotransmitter system in the fetus. To study if the postnatal profile of brain indoles continues to respond to these diet-induced changes, pregnant rats were fed graded levels (0, 12, 24, 60%) of glucose from impregnation to day 15 postpartum, and neonatal brain measurements were made. A steady decrease in tryptophan levels, a steady increase in 5-hydroxytryptamine (5-HT) levels and a U-shaped change in 5-hydroxyindoleacetic acid (5-HIAA) were observed during the first 15 postpartum days. Superimposed on these development profiles was a temporary surge in the concentrations of all three indoles 24 h after birth, which was dramatic for tryptophan and more modest for 5-HT and 5-HIAA. The level of carbohydrate in the maternal diet significantly influenced the magnitude of this increase in tryptophan, 5-HT and 5-HIAA at 24 h: the values were significantly higher in the carbohydrate-restricted (12 or 24%) rat pups when compared with control or carbohydrate-free (0% glucose) offspring. No effects of dietary treatment were apparent by day 6. However, the reemergence of a significant difference in brain 5-HT content at day 15 postpartum indicates that even when energy intake is adequate the level of carbohydrate in the maternal diet may continue to play a role in modulating serotonergic neurotransmitter levels later in development.
Copper-deficient rat embryos are characterized by brain and heart anomalies, low superoxide dismu... more Copper-deficient rat embryos are characterized by brain and heart anomalies, low superoxide dismutase activity, and high superoxide anion concentrations. One consequence of increased superoxide anions can be the formation of peroxynitrite, a strong biological oxidant. To investigate developmentally important features of copper deficiency, GD 8.5 mouse embryos from copper-adequate and copper-deficient dams were cultured in media that were adequate or deficient in copper. After 48 h, copper-deficient embryos exhibited brain and heart anomalies, and a high incidence of yolk sac vasculature abnormalities compared to controls. Immunohistochemistry of 4-hydroxynonenal and 8-hydroxy-2'-deoxyguanosine for lipid and DNA damage, respectively, was similar between groups. In contrast, 3-nitrotyrosine, taken as a measure of protein nitration, was markedly higher in the neuroepithelium of the anterior neural tube of copper-deficient embryos than in controls. Repletion of copper-deficient media with copper, or supplementation with copper-zinc superoxide dismutase, Tiron, or glutathione peroxidase did not ameliorate the abnormal development, but did decrease 3-nitrotyrosine in neuroepithelium of copper-deficient embryos. These data support the concept that while copper deficiency compromises oxidant defense and increases protein nitration, additional mechanisms, e.g., altered nitric oxide metabolism may contribute to copper-deficiency-induced teratogenesis.
Copper (Cu) deficiency-induced teratogenicity is characterized by major cardiac, brain and vascul... more Copper (Cu) deficiency-induced teratogenicity is characterized by major cardiac, brain and vascular anomalies, however, the underlying mechanisms are poorly understood. Cu deficiency decreases superoxide dismutase activity, and increases superoxide anions which can interact with nitric oxide (NO), reducing the NO pool size. Given the role of NO as a developmental signaling molecule, we tested the hypothesis that low NO levels, secondary to Cu deficiency, represent a developmental challenge. Gestation day 8.5 embryos from Cu adequate (Cu+) or Cu deficient (Cu−) dams were cultured for 48 h in Cu+ or Cu− medium, respectively. We report that NO levels were low in conditioned media from Cu−/Cu− embryos and yolk sacs, compared to Cu+/Cu+ controls under basal conditions, and with NO synthase (NOS) agonists. The low NO production was associated with low endothelial NOS phosphorylation at serine 1177 and cyclic guanosine-3′,5′-monophosphate (cGMP) concentrations in the Cu−/Cu− group. The altered NO levels in Cu deficient embryos are functionally significant, as the administration of the NO donor, DETA/NONOate, increased cGMP and ameliorated embryo and yolk sac abnormalities. These data support the concept that Cu deficiency limits NO availability and alters NO-dependent signaling which contributes to abnormal embryo and yolk sac development.
There is cumulative strong evidence that diets rich in flavanols can provide certain positive hea... more There is cumulative strong evidence that diets rich in flavanols can provide certain positive health benefits, particularly with respect to the cardiovascular system. Consequently, it has been suggested that increasing one's dietary intake of flavanols may be of benefit. Complicating this idea, there are reports that high intakes of certain flavonoids during pregnancy are associated with an increased risk for acute infant leukemia due to a poison effect of select polyphenolic compounds on DNA topoisomerase (topo) II activity that promotes aberrant chromosomal translocations. In the current study, we characterized the effects of select flavanols (epicatechin and catechin monomers), and select flavanol dimers and longer oligomers, on topo II activity, and on cellular toxicity in vitro. In contrast to the chemotherapeutic drug etoposide (VP16) and the flavonol quercetin, which strongly inhibited topo II activity and increased the formation of cleavage complexes demonstrating a poison effect, the flavanols epicatechin and catechin had little effect on topo II enzyme activity. Accordingly, several fold greater concentrations of the flavanols were required to achieve cellular toxicity similar to that of quercetin and VP16 in cultures of myeloid and lymphoid cells. Low cellular toxicity and limited topo II inhibition were also observed with a procyanidin-rich cocoa extract. Of all the flavanols tested, the dimers (B2, B5 and a mix of both) exerted the greatest inhibition of topo II and inhibited cellular proliferation rates at concentrations similar to quercetin. However, in contrast to quercetin, the dimers did not function as topo II poisons. Collectively, our in vitro data show that cocoa-derived flavanols have limited effects on topo II activity and cellular proliferation in cancer cell lines. We predict that these compounds are likely to have limited leukemogenic potential at physiological concentrations.
Birth Defects Research Part B: Developmental and Reproductive Toxicology, 2006
It has been shown that mechanical stimulation affects the physical properties of multiple types o... more It has been shown that mechanical stimulation affects the physical properties of multiple types of engineered tissues. However, the optimum regimen for applying cyclic radial stretch to engineered arteries is not well understood. To this end, the effect of mechanical stretch on the development of engineered blood vessels was analyzed in constructs grown from porcine vascular smooth muscle cells. Cyclic radial distension was applied during vessel culture at three rates: 0 beats per minute (bpm), 90 bpm, and 165 bpm. At the end of the 7-week culture period, harvested vessels were analyzed with respect to physical characteristics. Importantly, mechanical stretch at 165 bpm resulted in a significant increase in rupture strength in engineered constructs over nonstretched controls. Stress-strain data and maximal elastic moduli from vessels grown at the three stretch rates indicate enhanced physical properties with increasing pulse rate. In order to investigate the role of collagen cross-linking in the improved mechanical characteristics, collagen cross-link density was quantified by HPLC. Vessels grown with mechanical stretch had somewhat more collagen and higher burst pressures than nonpulsed control vessels. Pulsation did not increase collagen cross-link density. Thus, increased wall thickness and somewhat elevated collagen concentrations, but not collagen cross-link density, appeared to be responsible for increased burst strength.
Copper (Cu) is an essential nutrient whose requirement is increased during pregnancy and lactatio... more Copper (Cu) is an essential nutrient whose requirement is increased during pregnancy and lactation. These represent times of critical growth and development, and the fetus and neonate are particularly vulnerable to deficiencies of this nutrient. Genetic mutations that predispose the offspring to inadequate stores of Cu can be life threatening as is observed in children with Menkes disease. During the last decade, severe Cu deficiency, once thought to be a rare condition, has been reported in the literature at an increasing frequency. Secondary Cu deficiencies can be induced by a variety of ways such as excessive zinc or iron intake, certain drugs, and bariatric surgery. Premature and low birth weight infants can be born with low Cu stores. A number of mechanisms can contribute to the teratogenicity of Cu including decreased activity of select cuproenzymes, increased oxidative stress, decreased nitric oxide availability, altered iron metabolism, abnormal extracellular matrix protein crosslinking, decreased angiogenesis and altered cell signaling among others. The brain, heart, and vessels as well as tissues such as lung, skin and hair, and systems including the skeletal, immune, and blood systems, are negatively affected by suboptimal Cu during development. Additionally, persistent structural, biochemical, and functional adverse effects in the offspring are noted even when Cu supplementation is initiated after birth, supporting the concept that adequate Cu nutriture during pregnancy and lactation is critical for normal development. Although Cu-containing IUDs are an effective method for increasing intrauterine Cu concentrations and for reducing the risk of pregnancy, high amounts of dietary Cu are not thought to represent a direct developmental risk.
Using liposomes composed of either brain phosphatidylcholine (PC), or binary mixtures of PC and p... more Using liposomes composed of either brain phosphatidylcholine (PC), or binary mixtures of PC and phosphatidylserine (PS)
We have used a preimplantation embryo culture system to investigate the effects of boron (B) defi... more We have used a preimplantation embryo culture system to investigate the effects of boron (B) deficiency on early mouse development. To test the influence of low boron concentration in the medium, two-cell embryos collected from CD-1 mice fed a commercial stock high boron diet were cultured for 72 h in control boron (B+), or boron-free (B−) media. Preimplantation development was similar in the two groups over the 72-h period (Study 1). To investigate the influence of maternal boron status on early embryonic development, mice were fed a low boron (0.04 g B/g, LOW), or a suppplemented boron (2.05 g B/g, SUPP) purified diet, or a high boron (11.8 g B/g, STOCK) commercial stock diet. In Study 2A, two-cell embryos were collected after the females had been fed the diets for 10, 12, or 16 weeks. Embryos were cultured in B+ medium. In Study 2B, two-cell embryos were collected after the females had been fed the diets for 16 weeks, and the embryos were cultured in B− medium. In both studies, liver and tibia boron concentrations were lower in LOW fed mice than in mice fed the SUPP or STOCK diets. The in vitro development of two-cell embryos collected from mice fed either one of the boron purified diets was not severely impaired when they were cultured in B+ medium. However, two-cell embryos from the LOW diet had a lower frequency of blastocyst formation (83.5%, LOW vs. 90.1%, SUPP), and an increased frequency of degenerate embryos (13.0%, LOW vs. 8.0%, SUPP) after 72 h of culture compared to embryos from the SUPP diet. Exposure to dietary and medium boron deficiency significantly compromised the in vitro development of two-cell embryos compared to dietary boron deficiency alone. Low dietary boron combined with low boron in the medium resulted in the highest percentage of degenerate embryos (57.0%). Collectively, these data support the concept that boron deficiency impairs early embryonic development in rodents.
Copper-deficient rat embryos are characterized by brain and heart anomalies, low superoxide dismu... more Copper-deficient rat embryos are characterized by brain and heart anomalies, low superoxide dismutase activity, and high superoxide anion concentrations. One consequence of increased superoxide anions can be the formation of peroxynitrite, a strong biological oxidant. To investigate developmentally important features of copper deficiency, GD 8.5 mouse embryos from copper-adequate and copper-deficient dams were cultured in media that were adequate or deficient in copper. After 48 h, copper-deficient embryos exhibited brain and heart anomalies, and a high incidence of yolk sac vasculature abnormalities compared to controls. Immunohistochemistry of 4-hydroxynonenal and 8-hydroxy-2'-deoxyguanosine for lipid and DNA damage, respectively, was similar between groups. In contrast, 3-nitrotyrosine, taken as a measure of protein nitration, was markedly higher in the neuroepithelium of the anterior neural tube of copper-deficient embryos than in controls. Repletion of copper-deficient media with copper, or supplementation with copper-zinc superoxide dismutase, Tiron, or glutathione peroxidase did not ameliorate the abnormal development, but did decrease 3-nitrotyrosine in neuroepithelium of copper-deficient embryos. These data support the concept that while copper deficiency compromises oxidant defense and increases protein nitration, additional mechanisms, e.g., altered nitric oxide metabolism may contribute to copper-deficiency-induced teratogenesis.
Because glucose is an important metabolic fuel during perinatal development, the effect of restri... more Because glucose is an important metabolic fuel during perinatal development, the effect of restriction of maternal dietary glucose on the developmental profile of neonatal glucoregulatory pathways was investigated. Pregnant rats were fed isoenergetic diets (0, 12, 24 or 60% glucose) and offspring were killed at seven postpartum time periods: 0 -2, 4 - 6, 12-16 and 24 h, and 3,
Maternal nutrition can have a significant effect on developmental processes during pregnancy and ... more Maternal nutrition can have a significant effect on developmental processes during pregnancy and lactation. While certain flavonoids have been postulated to be beneficial for health, little is known about the effects of ingestion during pregnancy and lactation on the mother and progeny. We report on the effects of maternal consumption of high levels of certain flavonoids on reproductive and developmental outcomes in a mouse model. C57BL/6J female mice were fed a control diet (CT), the CT diet supplemented with 1% or 2% of a mix of epicatechin and catechin (EC1, EC2), or rutin (RU1, RU2) prior to, during pregnancy, and lactation. A subset of dams was killed on gestation day (GD) 18.5 to evaluate fetal outcomes and the remainder was allowed to deliver to evaluate offspring. Maternal food intake, body and tissue weight did not differ among groups. The number of resorptions, implantations, litter size, postnatal survival, body weight, and skeletal development were also similar. Alterations in maternal and offspring liver mineral concentrations were observed. The current results indicate that consumption of high amounts of epicatechin, catechin, and rutin during gestation and lactation is not associated with any marked developmental effects, although changes in liver mineral concentrations were noted.
Approximately 3% of infants born have at least one serious congenital malformation. In the U.S., ... more Approximately 3% of infants born have at least one serious congenital malformation. In the U.S., an average of 10 infants per thousand die before 1 y of life; about half of these deaths can be attributed to birth defects, low birth weight or prematurity. Although the causes of developmental abnormalities are clearly multifactorial in nature, we suggest that a common factor contributing to the occurrence of developmental abnormalities is suboptimal mineral nutrition during embryonic and fetal development. Using zinc and copper as examples, evidence is presented that nutritional deficiencies can rapidly affect the developing conceptus and result in gross structural abnormalities. Deficits of zinc or copper can result in rapid changes in cellular redox balance, tissue oxidative stress, inappropriate patterns of cell death, alterations in the migration of neural crest cells and changes in the expression of key patterning genes. In addition to well-recognized malformations, mineral defic...
The etiology of congenital heart disease is multifactorial, with genetics and nutritional deficie... more The etiology of congenital heart disease is multifactorial, with genetics and nutritional deficiencies recognized as causative agents. Maternal zinc (Zn) deficiency is associated with an increased risk for fetal heart malformations; however, the contributing mechanisms have yet to be identified. In this study, we fed pregnant rats a Zn-adequate diet (ZnA), a Zn-deficient (ZnD), or a restricted amount of Zn adequate diet (RF) beginning on gestation day (GD) 4.5, to examine whether increased cell death and changes in cardiac neural crest cells (NCC) play a role in Zn deficiency-induced heart defects. Fetuses were collected on GD 13.5, 15.5, and 18.5 and processed for GATA-4, FOG-2, connexin-43 (Cx43), HNK-1, smooth muscle alpha-actin (SMA) and cleaved caspase-3 protein expression. Fetuses from ZnA-fed dams showed normal heart development, whereas fetuses from dams fed with the ZnD diet exhibited a variety of heart anomalies, particularly in the region of the outflow tract. HNK-1 expre...
Numerous studies support the concept that a major cause of pregnancy complications can be subopti... more Numerous studies support the concept that a major cause of pregnancy complications can be suboptimal embryonic and fetal nutrition. Although the negative effects of diets low in energy on pregnancy outcome are well documented, less clear are the effects of diets that are low in one or more essential micronutrients. However, several observational and intervention studies suggest that diets low in essential vitamins and minerals can pose a significant reproductive risk in diverse human populations. Although maternal nutritional deficiencies typically occur as a result of low dietary intakes of essential nutrients, nutritional deficiencies at the level of the conceptus can arise through multiple mechanisms. Evidence from experimental animals supports the concept that in addition to primary deficiencies, secondary embryonic and fetal nutritional deficiencies can be caused by diverse factors including genetics, maternal disease, toxicant insults and physiological stressors that can trigg...
Numerous studies support the concept that a major cause of pregnancy complications can be subopti... more Numerous studies support the concept that a major cause of pregnancy complications can be suboptimal embryonic and fetal nutrition. Although the negative effects of diets low in energy on pregnancy outcome are well documented, less clear are the effects of diets that are low in one or more essential micronutrients. However, several observational and intervention studies suggest that diets low
Dietary glucose restriction during pregnancy can retard fetal brain development, lower term brain... more Dietary glucose restriction during pregnancy can retard fetal brain development, lower term brain glycogen levels and adversely affect the serotonergic neurotransmitter system in the fetus. To study if the postnatal profile of brain indoles continues to respond to these diet-induced changes, pregnant rats were fed graded levels (0, 12, 24, 60%) of glucose from impregnation to day 15 postpartum, and neonatal brain measurements were made. A steady decrease in tryptophan levels, a steady increase in 5-hydroxytryptamine (5-HT) levels and a U-shaped change in 5-hydroxyindoleacetic acid (5-HIAA) were observed during the first 15 postpartum days. Superimposed on these development profiles was a temporary surge in the concentrations of all three indoles 24 h after birth, which was dramatic for tryptophan and more modest for 5-HT and 5-HIAA. The level of carbohydrate in the maternal diet significantly influenced the magnitude of this increase in tryptophan, 5-HT and 5-HIAA at 24 h: the values were significantly higher in the carbohydrate-restricted (12 or 24%) rat pups when compared with control or carbohydrate-free (0% glucose) offspring. No effects of dietary treatment were apparent by day 6. However, the reemergence of a significant difference in brain 5-HT content at day 15 postpartum indicates that even when energy intake is adequate the level of carbohydrate in the maternal diet may continue to play a role in modulating serotonergic neurotransmitter levels later in development.
Copper-deficient rat embryos are characterized by brain and heart anomalies, low superoxide dismu... more Copper-deficient rat embryos are characterized by brain and heart anomalies, low superoxide dismutase activity, and high superoxide anion concentrations. One consequence of increased superoxide anions can be the formation of peroxynitrite, a strong biological oxidant. To investigate developmentally important features of copper deficiency, GD 8.5 mouse embryos from copper-adequate and copper-deficient dams were cultured in media that were adequate or deficient in copper. After 48 h, copper-deficient embryos exhibited brain and heart anomalies, and a high incidence of yolk sac vasculature abnormalities compared to controls. Immunohistochemistry of 4-hydroxynonenal and 8-hydroxy-2'-deoxyguanosine for lipid and DNA damage, respectively, was similar between groups. In contrast, 3-nitrotyrosine, taken as a measure of protein nitration, was markedly higher in the neuroepithelium of the anterior neural tube of copper-deficient embryos than in controls. Repletion of copper-deficient media with copper, or supplementation with copper-zinc superoxide dismutase, Tiron, or glutathione peroxidase did not ameliorate the abnormal development, but did decrease 3-nitrotyrosine in neuroepithelium of copper-deficient embryos. These data support the concept that while copper deficiency compromises oxidant defense and increases protein nitration, additional mechanisms, e.g., altered nitric oxide metabolism may contribute to copper-deficiency-induced teratogenesis.
Copper (Cu) deficiency-induced teratogenicity is characterized by major cardiac, brain and vascul... more Copper (Cu) deficiency-induced teratogenicity is characterized by major cardiac, brain and vascular anomalies, however, the underlying mechanisms are poorly understood. Cu deficiency decreases superoxide dismutase activity, and increases superoxide anions which can interact with nitric oxide (NO), reducing the NO pool size. Given the role of NO as a developmental signaling molecule, we tested the hypothesis that low NO levels, secondary to Cu deficiency, represent a developmental challenge. Gestation day 8.5 embryos from Cu adequate (Cu+) or Cu deficient (Cu−) dams were cultured for 48 h in Cu+ or Cu− medium, respectively. We report that NO levels were low in conditioned media from Cu−/Cu− embryos and yolk sacs, compared to Cu+/Cu+ controls under basal conditions, and with NO synthase (NOS) agonists. The low NO production was associated with low endothelial NOS phosphorylation at serine 1177 and cyclic guanosine-3′,5′-monophosphate (cGMP) concentrations in the Cu−/Cu− group. The altered NO levels in Cu deficient embryos are functionally significant, as the administration of the NO donor, DETA/NONOate, increased cGMP and ameliorated embryo and yolk sac abnormalities. These data support the concept that Cu deficiency limits NO availability and alters NO-dependent signaling which contributes to abnormal embryo and yolk sac development.
There is cumulative strong evidence that diets rich in flavanols can provide certain positive hea... more There is cumulative strong evidence that diets rich in flavanols can provide certain positive health benefits, particularly with respect to the cardiovascular system. Consequently, it has been suggested that increasing one's dietary intake of flavanols may be of benefit. Complicating this idea, there are reports that high intakes of certain flavonoids during pregnancy are associated with an increased risk for acute infant leukemia due to a poison effect of select polyphenolic compounds on DNA topoisomerase (topo) II activity that promotes aberrant chromosomal translocations. In the current study, we characterized the effects of select flavanols (epicatechin and catechin monomers), and select flavanol dimers and longer oligomers, on topo II activity, and on cellular toxicity in vitro. In contrast to the chemotherapeutic drug etoposide (VP16) and the flavonol quercetin, which strongly inhibited topo II activity and increased the formation of cleavage complexes demonstrating a poison effect, the flavanols epicatechin and catechin had little effect on topo II enzyme activity. Accordingly, several fold greater concentrations of the flavanols were required to achieve cellular toxicity similar to that of quercetin and VP16 in cultures of myeloid and lymphoid cells. Low cellular toxicity and limited topo II inhibition were also observed with a procyanidin-rich cocoa extract. Of all the flavanols tested, the dimers (B2, B5 and a mix of both) exerted the greatest inhibition of topo II and inhibited cellular proliferation rates at concentrations similar to quercetin. However, in contrast to quercetin, the dimers did not function as topo II poisons. Collectively, our in vitro data show that cocoa-derived flavanols have limited effects on topo II activity and cellular proliferation in cancer cell lines. We predict that these compounds are likely to have limited leukemogenic potential at physiological concentrations.
Birth Defects Research Part B: Developmental and Reproductive Toxicology, 2006
It has been shown that mechanical stimulation affects the physical properties of multiple types o... more It has been shown that mechanical stimulation affects the physical properties of multiple types of engineered tissues. However, the optimum regimen for applying cyclic radial stretch to engineered arteries is not well understood. To this end, the effect of mechanical stretch on the development of engineered blood vessels was analyzed in constructs grown from porcine vascular smooth muscle cells. Cyclic radial distension was applied during vessel culture at three rates: 0 beats per minute (bpm), 90 bpm, and 165 bpm. At the end of the 7-week culture period, harvested vessels were analyzed with respect to physical characteristics. Importantly, mechanical stretch at 165 bpm resulted in a significant increase in rupture strength in engineered constructs over nonstretched controls. Stress-strain data and maximal elastic moduli from vessels grown at the three stretch rates indicate enhanced physical properties with increasing pulse rate. In order to investigate the role of collagen cross-linking in the improved mechanical characteristics, collagen cross-link density was quantified by HPLC. Vessels grown with mechanical stretch had somewhat more collagen and higher burst pressures than nonpulsed control vessels. Pulsation did not increase collagen cross-link density. Thus, increased wall thickness and somewhat elevated collagen concentrations, but not collagen cross-link density, appeared to be responsible for increased burst strength.
Copper (Cu) is an essential nutrient whose requirement is increased during pregnancy and lactatio... more Copper (Cu) is an essential nutrient whose requirement is increased during pregnancy and lactation. These represent times of critical growth and development, and the fetus and neonate are particularly vulnerable to deficiencies of this nutrient. Genetic mutations that predispose the offspring to inadequate stores of Cu can be life threatening as is observed in children with Menkes disease. During the last decade, severe Cu deficiency, once thought to be a rare condition, has been reported in the literature at an increasing frequency. Secondary Cu deficiencies can be induced by a variety of ways such as excessive zinc or iron intake, certain drugs, and bariatric surgery. Premature and low birth weight infants can be born with low Cu stores. A number of mechanisms can contribute to the teratogenicity of Cu including decreased activity of select cuproenzymes, increased oxidative stress, decreased nitric oxide availability, altered iron metabolism, abnormal extracellular matrix protein crosslinking, decreased angiogenesis and altered cell signaling among others. The brain, heart, and vessels as well as tissues such as lung, skin and hair, and systems including the skeletal, immune, and blood systems, are negatively affected by suboptimal Cu during development. Additionally, persistent structural, biochemical, and functional adverse effects in the offspring are noted even when Cu supplementation is initiated after birth, supporting the concept that adequate Cu nutriture during pregnancy and lactation is critical for normal development. Although Cu-containing IUDs are an effective method for increasing intrauterine Cu concentrations and for reducing the risk of pregnancy, high amounts of dietary Cu are not thought to represent a direct developmental risk.
Using liposomes composed of either brain phosphatidylcholine (PC), or binary mixtures of PC and p... more Using liposomes composed of either brain phosphatidylcholine (PC), or binary mixtures of PC and phosphatidylserine (PS)
We have used a preimplantation embryo culture system to investigate the effects of boron (B) defi... more We have used a preimplantation embryo culture system to investigate the effects of boron (B) deficiency on early mouse development. To test the influence of low boron concentration in the medium, two-cell embryos collected from CD-1 mice fed a commercial stock high boron diet were cultured for 72 h in control boron (B+), or boron-free (B−) media. Preimplantation development was similar in the two groups over the 72-h period (Study 1). To investigate the influence of maternal boron status on early embryonic development, mice were fed a low boron (0.04 g B/g, LOW), or a suppplemented boron (2.05 g B/g, SUPP) purified diet, or a high boron (11.8 g B/g, STOCK) commercial stock diet. In Study 2A, two-cell embryos were collected after the females had been fed the diets for 10, 12, or 16 weeks. Embryos were cultured in B+ medium. In Study 2B, two-cell embryos were collected after the females had been fed the diets for 16 weeks, and the embryos were cultured in B− medium. In both studies, liver and tibia boron concentrations were lower in LOW fed mice than in mice fed the SUPP or STOCK diets. The in vitro development of two-cell embryos collected from mice fed either one of the boron purified diets was not severely impaired when they were cultured in B+ medium. However, two-cell embryos from the LOW diet had a lower frequency of blastocyst formation (83.5%, LOW vs. 90.1%, SUPP), and an increased frequency of degenerate embryos (13.0%, LOW vs. 8.0%, SUPP) after 72 h of culture compared to embryos from the SUPP diet. Exposure to dietary and medium boron deficiency significantly compromised the in vitro development of two-cell embryos compared to dietary boron deficiency alone. Low dietary boron combined with low boron in the medium resulted in the highest percentage of degenerate embryos (57.0%). Collectively, these data support the concept that boron deficiency impairs early embryonic development in rodents.
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