Changes in plasma lipids and increased low-density lipoprotein susceptibility to oxidation in pregnancies complicated by gestational diabetes: consequences of obesity.

Dyslipidemia is associated with increased low-density lipoprotein (LDL) susceptibility to oxidation, a phenomenon associated with endothelial dysfunction, atherosclerosis, cell toxicity, and intrauterine growth retardation. The present study was designed to determine if women developing gestational diabetes mellitus (GDM) have both increased plasma lipids and LDL susceptibility to oxidation throughout pregnancy. We also wanted to study the effects of obesity upon these parameters. A nested case-control study was carried out in 45 women with uncomplicated pregnancies and 62 women diagnosed with GDM following the criteria of the American Diabetes Association. In all women, blood was drawn at 15, 24, and 32 weeks of gestation. Low-density lipoprotein oxidation was initiated by the addition of CuCl2, and formation of conjugated dienes was monitored. Glucose, cholesterol, triglycerides, vitamin E, estradiol, and progesterone were determined. In GDM, elevated levels of glucose, cholesterol, and triglycerides were observed when compared with the control group even in the first trimester, before the detection of diabetes. In the control group, the lag phase in the LDL oxidation was 85.3, 84.4, and 95.6 minutes at 15, 24, and 32 weeks of pregnancy, compared with 63.3, 63.4, and 74.5 minutes in the GDM group (P < .001 in the 3 periods). These differences remained when adjusted for the body mass index. In a multiple linear regression analysis, a negative correlation was observed between the lag phase and the body mass index (P < .001) and cholesterol (P < .001), whereas a positive one appeared with vitamin E (P < .05) and time of gestation (P < .001). In pregnancy, GDM increases LDL susceptibility to oxidation. Obesity and hypercholesterolemia further exacerbate this effect.

Development of atherosclerosis in the diabetic BALB/c mice. Prevention with Vitamin E administration.

The aim of the present study was to determine in the BALB/c mice, a model of development of atherosclerosis when both hyperglycemia and hypercholesterolemia are present, whether the atherogenic effects of these parameters could be decreased with the administration of Vitamin E. BALB/c mice were made diabetic and divided in three groups: one fed the standard rodent chow diet (D); the other two fed an atherogenic diet (D+A); one of them supplemented with Vitamin E (D+A+E). Two groups of non diabetic animals were also performed, one fed the standard diet (C) and the other the atherogenic diet (C+A). After 16 weeks of treatment all the control animals survived, in contrast, a mortality rate of 12, 70 and 37% was observed, respectively, in the D, D+A and D+A+E groups. Neither fatty deposits nor macrophages were observed in the arterial wall of the animals fed the standard diet (D and C animals). In contrast, this finding was observed in 25% of the C+A, 71% of the D+A and 33% of the D+A+E. In conclusion, diabetic mice fed an atherogenic diet showed in the aorta a higher number of fatty deposits and macrophages than the control animals. These effects were partially reversed with the administration of Vitamin E, supporting in this model the role of oxidative stress in the development of atherosclerosis.

Increased low-density lipoprotein susceptibility to oxidation in pregnancies and fetal growth restriction.

OBJECTIVE: Atherosis and placental infarction have been observed in pregnancies complicated by fetal growth restriction (FGR). Low-density lipoprotein (LDL) oxidation plays a central role in the pathogenesis of atherosclerosis; therefore, it could be involved in the placental alterations observed in FGR. The aims of the present study were to estimate LDL susceptibility to oxidation in pregnancies complicated by FGR and to evaluate their relationship with fetal growth and placental hormone secretion. METHODS: A cohort prospective study was carried out in 50 women with uncomplicated pregnancies and 55 women with FGR. Blood was drawn at 15, 24, and 32 weeks of gestation. Low-density lipoprotein oxidation was initiated by the addition of CuCl2 and formation of conjugated dienes was monitored. Cholesterol, triglycerides, vitamin E, estradiol, progesterone, and placental lactogen were determined. RESULTS: Women with FGR showed a lag phase (minutes from addition of CuCl2) similar to the control group in the first trimester of pregnancy (85.3 +/- 3.3 versus 81.3 +/- 5.6). But in the second and third trimester, they showed a lower lag phase than the control group: 69.6 +/- 3.6 versus 84.4 +/- 3.5 (P < .05) and 69.9 +/- 3.4 versus 95.6 +/- 3.4 (P < .001). During the third trimester, pregnancies complicated with FGR showed lower levels of estradiol, progesterone, and human placental lactogen than those in the control group. In the third trimester, a positive correlation was found between the lag phase and the birth weight (P = .001) and with the plasma levels of estradiol (P = .002). CONCLUSION: Fetal growth restriction is associated with an increased LDL susceptibility to oxidation, a process that could damage the placenta, leading to alterations in placental endocrine function and fetal weight. Pregnancies complicated by fetal growth restriction show an increased LDL susceptibility to oxidation, a process that may lead to placental dysfunction and growth delay.

Immature rat brain slices exposed to oxygen-glucose deprivation as an in vitro model of neonatal hypoxic-ischemic encephalopathy.

To analyze whether exposure to oxygen-glucose deprivation (OGD) of immature rat brain slices might reproduce the main pathophysiologic events leading to neuronal death in neonatal hypoxic-ischemic encephalopathy (NHIE), 500 microm-thick brain slices were obtained from 7-day-old Wistar rats, and incubated in oxygenated physiological solution. In OGD group, oxygen and glucose were removed from the medium for 10-30 min (n = 25); then, slices were re-incubated in normal medium. In control group the medium composition remained unchanged (CG, n = 30). Medium samples were obtained every 30 min for 3 h. To analyze neuronal damage, slices were stained with Nissl and CA1 area of hippocampus and cortex were observed under microscopy. In addition, neuronal death was quantified as LDH released to the medium determined by spectrophotometry. Additionally, medium glutamate (Glu) levels were determined by HPLC and those of TNFalpha by ELISA, whereas inducible nitric oxide synthase expression was determined by Western blot performed on slices homogenate. Optimal OGD time was established in 20 min. After OGD, a significant decrease in the number of neurones in hippocampus and cortex was observed. LDH release was maximal at 30 min, when it was five-fold greater than in CG. Furthermore, medium Glu concentrations were 200 times greater than CG levels at the end of OGD period. A linear relationship between Glu and LDH release was demonstrated. Finally, 3 h after OGD a significant induction of iNOS as well as an increase in TNFalpha release were observed. In conclusion, OGD appears as a feasible and reproducible in vitro model, leading to a neuronal damage, which is physiopathologically similar to that found in NHIE.

Implications of postvaccination hepatitis B surface antigenemia in the management of exposures to body fluids.

A neonate vaccinated against HBV was the source of an occupational exposure to blood. She was tested for hepatitis B surface antigen and found to be positive, leading to unnecessary treatment, retesting, and concern. Evaluation of the infectious status of HBV should rely on other means if vaccination has recently occurred.

Relationship between alpha-tocopherol content in the different lipoprotein fractions in term pregnant women and in umbilical cord blood.

AIMS: To determine the concentration of vitamin E in normal maternal and umbilical cord blood pairs, and to study the relationship between vitamin E content in maternal lipoprotein fractions and umbilical cord blood. METHODS: Fifty healthy pregnant women were recruited randomly at term and blood samples were drawn from the mothers at delivery and cord blood was obtained immediately postpartum. Vitamin E was determined by HPLC in plasma, in the different lipoprotein fractions and in the placenta. Plasma levels of triglycerides and cholesterol were also measured. RESULTS: The concentration of vitamin E in umbilical cord plasma was 250 microg/dl, lower than in maternal plasma (1,460 microg/dl) (p < 0.001). A positive correlation was found between the vitamin E concentration in maternal plasma, LDL and VLDL and in the umbilical cord plasma. In contrast, no correlation was found between maternal HDL concentration and umbilical cord blood. CONCLUSION: These results show that the concentration of vitamin E in umbilical cord blood is lower than in maternal plasma. LDL and VLDL seem to be the main source of vitamin E for the fetus.

Effect of different doses of vitamin E on the incidence of malformations in pregnant diabetic rats.

BACKGROUND/AIMS: Previously we have shown that administration of 150 mg of vitamin E (alpha-tocopherol) per day to rats having diabetes decreases the rate of embryo malformations and increases their maturation and size. The present study was addressed to determine the effects of different doses of vitamin E upon these parameters. METHODS: Female rats were made diabetic (D) with streptozotocin, and from day 0 of gestation they were treated daily with 25 (D+25), 50 (D+50), 100 (D+100), 150 (D+150), and 500 (D+500) mg of vitamin E administered orally and were compared with control (C) animals. RESULTS: On day 11.5 of gestation, crown-rump length, somite number, and protein and DNA levels were lower in D than in C embryos. Crown-rump length and somite number increased with 100 mg or higher doses of vitamin E, although the values observed in C embryos were not reached. The proportions of reabsorption and malformations were 24.7 and 50%, respectively, in D rats, and in the rats supplemented with vitamin E they decreased to 22.7 and 19% in D+25, 16.4 and 21.3% in D+50, 16.2 and 12% in D+100, 12.9 and 13.9% in D+150, and to 43.9 and 10.8% in D+500 rats, whereas the values were 6.8 and 4.9% in C animals. CONCLUSIONS: Administration of vitamin E to D rats decreases the rate of embryo malformations, dependent on the dose administered. However, high doses have a negative effect in the conceptus, as shown by the increased rate of reabsorptions in the D+500 group.

Dual effect of glucose on LDL oxidation: dependence on vitamin E.

The aim of the present study was to determine the direct effect of glucose on LDL oxidation, a key step in the development of atherosclerosis. Purified human LDL were incubated with glucose (500 mg/dl) and LDL oxidation was started by adding CuCl(2) to the media. Glucose delayed the vitamin E consumption, but accelerated the formation of conjugated dienes and increased both the formation of thiobarbituric acid reacting substances (TBARS) and LDL electrophoretic mobility. When LDL were incubated with increasing concentrations of glucose and submitted to oxidation, the formation of conjugated dienes, TBARS, and the electrophoretic mobility increased in a concentration-dependent manner. When LDL was enriched with vitamin E, it showed a delay in the formation of conjugated dienes, even in the presence of glucose. To determine whether glucose had any effect on LDL oxidation, once the process was started and vitamin E consumed, LDL were submitted to oxidation and, at different times thereafter, glucose was added into the media. Under these conditions glucose also accelerated the LDL oxidation. In summary, present results show that in LDL submitted to oxidation, glucose delays the early phases of the oxidation, slowing the vitamin E consumption, but it accelerates the rate of LDL oxidation once LDL vitamin E has been consumed; the effect being concentration-dependent.

Teratogenic actions of thermally-stressed culinary oils in rats.

Lipid oxidation products (LOPs), generated in culinary oils during episodes of thermal stressing can give rise to cellular damage. The aims of this study were to determine whether orally-administered, LOP-containing thermally-stressed safflower oil exerts teratogenic actions in rats, and whether this effect could be prevented by co-administration of alpha-tocopherol (alpha-TOH). Safflower oil was heated for a period of 20 min according to standard frying practices and stored at -20 degrees C under N2. Four experimental groups of pregnant Wistar rats were employed; two received 0.30 ml of pre-heated oil (HO), one of which was also supplemented with 150 mg of alpha-TOH (HOE), and two served as controls, one treated with the non-heated oil (O) and the other without any treatment (C). The oil was administered daily by gavage from day 1 of pregnancy to day 11.5, when the animals were killed and the embryos examined. LOPs and alpha-TOH were determined both in the heated and non-heated oils. The percentage of embryo malformations and reabsorptions were determined in the above four experimental groups. Heating the oil substantially increased its concentration of LOPs and decreased its alpha-TOH content. The percentage of embryo malformations in the HO group was 21.73%, compared with 5.6 and 7% in the O and C groups, respectively. Supplementation of the pre-heated oil with alpha-TOH was found to decrease the percentage of malformations to 7%. The results obtained from these investigations indicate that LOPs detectable at millimolar levels in the heated cooking oils administered (e.g. saturated and alpha,beta-unsaturated aldehydes, and/or their conjugated hydroperoxydiene precursors) exert potent teratogenic actions in experimental animals which are at least partially circumventable by co-administration of the chain-breaking antioxidant alpha-TOH. Plausible mechanisms for these processes and their health relevance to humans regarding diet and methods of frying/cooking are discussed.