Oxidative stress in diabetic pregnancy: SOD, CAT and GSH-Px activity and lipid peroxidation products

Diabetic pregnancy is often complicated by a number of pathological conditions among which is increased oxidative stress. This study was conducted to investigate the parameters of oxidative stress in 90 patients divided into the three groups: pregnant women with Type 1 diabetes mellitus, healthy pregnant women and non-pregnant women. In pregnancy groups all parameters were followed in 1st, 2nd and 3rd trimester. Diabetic control was monitored by fasting blood glucose and glycosylated hemoglobin (HbA(1c)) and these values, as well as measured biochemical parameters (urea, creatinine, total cholesterol and uric acid), were appropriate throughout the study. The concentration of TBARS, as a measure of lipid peroxidation, and activity of antioxidant enzymes superoxide dismutase (Cu, Zn-SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) were investigated in hemolysate of erythrocytes. TBARS concentration increased significantly in pregnant women when compared with control group (non-pregnant women), as well as in pregnant diabetics compared with healthy pregnant women. The SOD activity was gradually increased in the group of normal pregnant women vs. non-pregnant group, but decreased significantly in the group of diabetic pregnant women. Catalase activity was significantly increased only in 3rd trimester diabetic pregnant women. Increased lipid peroxidation and reduced antioxidant status, despite good diabetic control, show that pregnant women are exposed to oxidative stress to a greater degree than controls.

The role of alterations in arachidonic acid metabolism and nitric oxide homeostasis in rat models of diabetes during early pregnancy

The diabetic pathology induces reproductive abnormalities that enhance spontaneous abortion, congenital anomalies and neonatal morbidity/mortality rates, abnormalities that begin with an altered female gamete. In this review we focus on the damage induced by maternal hyperglycemia during ovulation, early embryo development, implantation and embryo organogenesis in experimental rat models of diabetes. Hyperglycemia can induce cellular damage by enhancing the production of reactive oxygen species (ROS), by altering arachidonic acid metabolism (thus leading to altered production of prostaglandins such us PGE(2)and 15deoxydelta(12-14)PGJ(2), involved in signalling and developmental pathways), and by enhancing the generation of nitric oxide (a mediator of many cell functions including apoptotic cell death). In maternal diabetes all of these abnormalities are present from the oocyte stage, during embryonic implantation, and during embryo organogenesis. The involvement of these alterations in embryo loss and congenital malformations due to diabetes and the cross-talk among these metabolic pathways are discussed. As maternal hyperglycemia induces damage from the oocyte stage and throughout embryo development the data reviewed suggests the need of strict preconceptional metabolic control. The importance of the molecules involved in hyperglycemia-induced damage as future pharmacological targets for intervention is discussed.

Insulin therapy in pregnancy complicated by diabetes: are insulin analogs a new tool?

It has been demonstrated that good metabolic control maintained throughout pregnancy can reduce maternal and fetal complications in diabetes. To achieve good metabolic control, before conception and throughout pregnancy, insulin therapy needs to be optimized, and, in this context, the new insulins currently on the market may help. We therefore review here what is known about the potential benefits and risks related to the use of these new insulins in pregnancy. Clinical and experimental data on insulin lispro strongly suggest that lispro does not have adverse maternal or fetal effects during pregnancy in women with preexisting diabetes, and also that its use in these women results in improved glycemic control, fewer hypoglycemic episodes, and improved patient satisfaction. In women with gestational diabetes mellitus (GDM), the use of insulin lispro is efficient in reducing postprandial hyperglycemia and some neonatal features related to hyperglycemia, thus stressing its usefulness in this condition. As for insulin aspart, clinical data on GDM patients shows the same efficacy as insulin lispro in lowering postprandial hyperglycemia, indicating that insulin aspart may be used in GDM when this condition is characterized by postprandial hyperglycemia. The results of a multicentric study now in progress on the efficacy and safety of insulin aspart in type 1 pregnant diabetic patients will definitely be useful in establishing whether this insulin is safe in pregnancy. For the moment, the use of insulin glargine during pregnancy is not recommended owing to the lack of data on maternal and fetal effects.

Lipid metabolism in the embryos of diabetic rats during early organogenesis: modulatory effect of prostaglandin E2

The purpose of this work was to evaluate de novo lipid biosynthesis and the lipid profile, and to study the effect of prostaglandin E2 (PGE2; prostaglandin has previously been found to be involved in diabetes embryopathy) on lipid metabolism in embryos from control and streptozotocin-induced diabetic rats during organogenesis. Increased levels of triacylglycerols were found in embryos of diabetic rats compared with controls, whereas no differences were detected in the levels of cholesterol, cholesterylester, phosphatidylcholine and phosphatidylethanolamine. When the de novo synthesis of lipids in the embryo was studied using [14C]acetate as a tracer, a diminished rate of incorporation of [14C]acetate into the evaluated lipid classes was detected in the diabetic embryo compared with controls. Addition of PGE2 did not modify the incorporation of [14C]acetate into any of the lipid species of control embryos, but enhanced the incorporation of [14C]acetate into triacylglycerol, cholesterylesters, phosphatidylcholine and phosphatidylethanolamine of embryos from diabetic rats. The study's results show alterations in both synthesis and concentrations of lipids in the embryos of diabetic rats. Interestingly, the results demonstrate that the addition of PGE2, a prostaglandin that reverses the embryonic morphological abnormalities induced by diabetes, prevents disturbances in embryo lipid synthesis caused by diabetes.

Effect of hyperglycaemic load on maternal-foetal transport of L-leucine in perfused human placental lobule: in vitro study

The effect of hyperglycaemic loads on L-leucine transport in the maternal-foetal direction has been investigated in human placenta in vitro, using perfusion of isolated placental lobules. National Culture and Tissue Collection medium diluted with Earle's buffered salt solution was used as the perfusate. (14)C-labelled L-leucine along with tritiated water as reference were injected as a 100-microl bolus into the maternal circulation and serial perfusate samples were collected over a 5-min study period. In 6 successful perfusions, the differential transport rate of leucine for 10, 25, 50, 75 and 90% of efflux in the foetal vein averaged 1.26, 1.10, 1.19, 1.10 and 1.04 times respectively that of reference in the control euglycaemic phase. In the experimental hyperglycaemic phases of 27.8 and 55.6 mM/l, leucine transport for the corresponding efflux periods averaged 1.37, 1.33, 1.28, 1.22 and 1.26 times and 1.16, 0.97, 1.08, 1.08 and 1.08 times respectively that of the reference marker. Analysis of variance (ANOVA) test showed that the difference between the three groups was not statistically significant. In the control euglycaemic phase, leucine transport fraction (TF) averaged 40.90+/-3.51% of corresponding water TF while in experimental hyperglycaemic phases, TF of the amino acid averaged 37.80+/-4.82% and 35.61+/-3.21% of water TF respectively. The difference between the control and hyperglycaemic perfusion phases was not statistically significant. Further, no statistical difference could be shown between the two hyperglycaemic perfusion series themselves. Similarly, kinetic parameters such as absorption rate, elimination rate and absorption rate:elimination rate ratio were not significantly different in the hyperglycaemic perfusion phases compared to control phase. Our studies seem to indicate that leucine transport kinetics in in vitro conditions are not altered significantly in placentas exposed to hyperglycaemic loads.

Changes of oxidative stress parameters in diabetic pregnancy

BACKGROUND

The molecular aetiology of disturbed embryogenesis and other unfavourable outcomes in offspring of diabetic mothers is not fully understood. Experimental studies have suggested an involvement of radical oxygen species (ROS) in the teratological process.

THE AIM OF OUR STUDY

To investigate if maternal diabetes in humans is capable of inducing alterations in vascular oxidative stress parameters and whether such changes are associated with disturbances in foetal development.

METHODS

Seventy patients with pre-gestational diabetes (PGDM) were chosen for the study: 29 (41.4%) belonged to class B according to White, 15 (21.4%) to class C, 8 (11.4%) to class D, 3 (4.3%) to class F, 3 to class R and 12 (17.1%) to class F/R. In 20 (28.6%) patients from this group an unfavourable outcome was noted. All patients were subjected to intensive insulin therapy. Glycaemia was estimated by daily self-monitoring, and diurnal glucose profiles and glycated haemoglobin (HbA1c) concentrations were measured monthly. Oxidative stress was evaluated as changed superoxide dismutase, catalase and glutathione peroxidase activities as well as of malondialdehyde (MDA) and peroxides concentrations in maternal erythrocytes and blood serum.

RESULTS

Prior to conception, the mean glycaemia in the group that had a planned pregnancy was 6.6mmol/l and HBA1c was 9.35%. Throughout the course of pregnancy, these parameters were maintained at a level of 6.7 mmol/l and 7.85%, respectively. The activity of all antioxidative enzymes was lower before than during pregnancy, and so was the concentration of MDA. The MDA concentrations were higher in patients with elevated glycaemia and with an unfavourable outcome. The investigated ROS, the glycaemia level, as well as the concentration of HBA1c did not show any significant differences between pregnancies with and without vascular complications. Patients with a favourable perinatal outcome presented a higher activity of antioxidant enzymes, than those with unfavourable outcome, throughout the whole course of pregnancy. The appearance of unfavourable perinatal outcomes in relation to parameters of oxidative stress was assessed by logistic regression. Both SOD and GPX activities, as well as peroxides' concentration, showed significant correlations (p < 0.005) with foetal complications. However, after mean glucose levels in the studied group were included into these analyses, this relationship was only evident with SOD and GPX activity (p < 0.0016).

CONCLUSION

Oxidative stress is one of several important factors contributing to unfavourable outcome of human diabetic pregnancy.

[Glucooxidative stress and spontaneous abortion in pregnant women with diabetes mellitus type 1]

The pregnancies in women with Diabetes mellitus are in condition of increased glucooxidative stress, which could be toxic for the developing embryo. END-POINTS: To evaluate the levels of selenium and glutation peroxidase in pregnant women with Diabetes mellitus type 1 in the first trimester of pregnancy and to establish whether there is a correlation between the diabetic glycemic control and occurrence of spontaneous abortions.

STUDY DESIGN

Prospective study of 75 women for 1 year period. he pregnant women were divided in 3 groups as follows: 1st group--30 pregnant women with Diabetes mellitus type 1 with normal outcome; 2nd group--16 pregnant women with Diabetes mellitus type 1 with spontaneous abortion; 3rd group--29 healthy pregnant controls. The activity of GI-Px in red blood cells was measured in hemolysat of EDTA plasma in Germany. The levels of glucosylated haemoglobin were also evaluated.

RESULTS

1. In all pregnant women the levels of selenium were lower without significant difference between them 1st group--0.12 +/- 0.6 mmol/l, 2ndd group 0.13 +/- 0.1 mmol/l, 3rd group 0.13 +/- 0.7 mmol/l (P > 0.05). 2. There is an increase in the activity of GI-Px, which is statistically significant in the healthy pregnant women 47.8 +/- 13.3 U/g Hb and diabetic pregnant women with normal outcome 48. 6 +/- 8.4 U/g Hb. There is no statistically significant difference in the activity of GI-Px in diabetic pregnant women with spontaneous abortions and the healthy controls (P > 0. 05). 3. Negative correlation between the levels of selenium and the activity of GI-Px was proved in healthy pregnant women (r = - 0.4; P < 0.05). No correlation was found between the level of the selenium and the activity of GI-Px into the two groups of diabetic pregnant women. 4. There is a correlation in the levels of diabetic pregnant women with spontaneous abortions (r = -0.38; P < 0.001).

CONCLUSIONS

The increased activity of GI-Px in diabetic pregnant women with spontaneous abortions is a result of increased antioxidative defense of the cell. Probably the ineffective antioxidant defense, leading to a spontaneous abortion is due to the low levels of selenium and high level of pre-prandial glycaemia.

Effects of diabetes and insulin resistance in pregnant rats on ex vivo vascular reaction to magnesium

The purpose of this study was to investigate the effects of diabetes and insulin resistance during pregnancy on the ex vivo vascular reaction to magnesium. Female Sprague-Dawley rats were made diabetic by intravenous injection of alloxan, or insulin resistant by fructose feeding. The rats were allowed to mate and sacrificed on Day 19 of pregnancy. Aortic rings were isolated and mounted in organ baths for measurement of isometric tension. The rings were contracted with 10(-7) M phenylephrine and cumulative concentration-response curves for magnesium (1-12 mM) were determined in the presence and absence of 10(-4) M Nomega-nitro-L-arginine methyl ester (L-NAME) or 10(-5) M indomethacin. The relaxation response to magnesium was significantly decreased in pregnant rats compared with non-pregnant rats. Pregnant rats with diabetes or insulin resistance had greater impairment in the relaxation responses to magnesium compared with normal pregnant rats. The effects of diabetes and insulin resistance on magnesium-induced relaxation in pregnant rats were not altered in the presence of L-NAME and indomethacin. The results suggest that diabetes and insulin resistance aggravate the alteration in magnesium-induced vascular relaxation observed in pregnancy, and this may be due in part to impairment to mechanisms other than the nitric oxide-cyclic guanosine monophosphate and cyclooxygenase pathways.

Plasma ghrelin and resistin concentrations are suppressed in infants of insulin-dependent diabetic mothers

This study aimed to investigate 1) the effect of maternal diabetes mellitus on ghrelin, resistin, leptin, and insulin in term newborns; 2) the interrelationship of these metabolic hormones in the early postnatal period; and 3) the association of the hormones with anthropometric parameters at birth. A total of 120 term newborns were prospectively enrolled and categorized into three groups: 40 were infants of nondiabetic mothers (group N), 42 were infants born to mothers with gestational diabetes on low energy dietary treatment (group D), and 38 were infants born to mothers with preexisting or severe gestational diabetes who required exogenous insulin for stabilization of blood sugar during pregnancy (group I). Plasma ghrelin and resistin were significantly lower in group I than in either group N or group D infants (P < 0.048). Plasma ghrelin and subscapular skinfold thickness were significantly higher in female than in male infants [plasma ghrelin: median (interquartile range), 3.8 (3.0-4.8) vs. 3.0 (2.4-4.0) ng/ml in females and males, respectively; P = 0.003; subscapular skinfold thickness: 4.9 (4.2-5.6) vs. 4.6 (3.9-5.2) mm; P = 0.03]. In group N, plasma ghrelin was significantly, but negatively, associated with birth weight (r = -0.31; P = 0.05) and body length (r = -0.33; P = 0.04), whereas in group I, plasma ghrelin was negatively correlated with plasma resistin (r = -0.37; P = 0.02). Plasma ghrelin and resistin are suppressed in infants of insulin-dependent diabetic mothers, suggesting that the metabolic hormonal system is probably operational in fetal and early postnatal life. A low circulating ghrelin concentration may be advantageous to these infants, because a reduction in appetite may prevent excessive weight gain postnatally and counterbalances the in utero anabolic effect of hyperinsulinism in poorly controlled diabetic mothers. The suppressive effect of insulin on resistin may partially explain the excess accumulation of adipose tissue in infants of diabetic mothers by reducing the inhibitory effect of resistin on adipogenesis. Female infants have significantly higher plasma ghrelin levels than male infants, suggesting that sexual dimorphism exists in utero. This study has also shown an association between some of the metabolic hormones in specific groups of infants and thus suggests that these hormones could have interacted in utero to regulate growth and fat storage during this critical period.

Triglyceride hydrolase activities and expression of fatty acid binding proteins in the human placenta in pregnancies complicated by intrauterine growth restriction and diabetes

Triglyceride (TG) hydrolases in the placental microvillous plasma membrane (MVM) release fatty acids from circulating lipoproteins and represent the critical initial step in transplacental fatty acid transfer. We investigated the activity of two TG hydrolases in MVM isolated from placentas of appropriately grown for gestational age pregnancies and pregnancies complicated by intrauterine growth restriction (IUGR), insulin-dependent diabetes mellitus (IDDM) or gestational diabetes mellitus (GDM). In addition, we measured protein expression of lipoprotein lipase (LPL) in MVM and two fatty acid binding proteins (L- and C-FABP) in placental homogenates. The TG hydrolase activities were assessed by measuring hydrolysis of (3)H-trioleic acid incorporated into intralipid micelles after incubation with MVM. The placenta-specific TG hydrolase activity (optimum at pH 6) did not differ in the patient groups studied. MVM LPL activity (optimum at pH 8) was reduced by 47% in preterm IUGR (n = 8, P < 0.05), compared with gestational age-matched controls. The LPL activity in placentas of IDDM pregnancies was increased by 39% (n = 8, P < 0.05), compared with controls. No significant differences were observed in cases of GDM. We found no alteration in protein expression of LPL or C-FABP. The expression of L-FABP was increased by 112% (n = 8, P < 0.05) in IDDM and 64% (n = 8, P < 0.05) in GDM. These results indicate that alterations in MVM LPL activity and expression of L-FABP may contribute to the altered lipid deposition and metabolism in IUGR and diabetic pregnancies.

Nutrition and pregnancy: the link between dietary intake and diabetes

Pregnancy is a time when serial metabolic changes in the mother are carefully regulated to provide optimum substrate to both mother and fetus. Subtle perturbations in maternal metabolism can have implications not only for the index pregnancy, but also for future generations. The literature provides evidence that maternal nutrition plays a major role in the destiny of the offspring. Both maternal malnutrition and overnutrition are associated with subsequent diabetes in the offspring. Pregnancy represents a window of opportunity for health care providers to change dietary patterns toward habits that will be healthier for the individual now, as well as impacting on the future. The challenge for clinicians is to provide nutritional information based on scientific evidence that facilitates the normalization of fetal nutrition, and thus minimize the risk that the child will develop diabetes.

Species distribution and influence of glycemic control on fungal infections in pregnant women with diabetes

OBJECTIVES

(1) To find the distribution of species among fungal strains isolated from pregnant women with diabetes mellitus (DM), gestational diabetes (GDM) and healthy controls (CON); (2) to analyse the influence of glycemia on the prevalence of fungi in different body sites.

METHODS

Mycological examinations were performed in 251 pregnant women: 119 diabetic (47 DM, and 72 GDM) and 132 controls. Samples were collected from vagina, rectum and oral cavity of all women and cultured on Sabouraud media.

RESULTS

A total of 212 fungal strains were isolated, 12 fungal species were identified: 89.6% of the strains belonged to Candida gender, 10.4% to Saccharomyces, Geotrichum, Rhodotorula and Trichosporon genera. The prevalence of fungi, respectively, in vagina and rectum, was significantly higher in diabetics with poor glycemic control when stratified (<100 mg/dl, 100-120 mg/dl and >120 mg/dl) both the mean week glucose levels (MWGL) levels (p = 0.03, p = 0.03) and glycemia 90 min after breakfast (p = 0.04, 0.03). No difference was found in the prevalence of fungi and glycolised hemoglobin (HbA1).

CONCLUSIONS

MWGL showed an association between glycemia and prevalence of fungi. However, no relation was found between HbA1 and fungal infections in well controlled diabetic pregnancies.

Influence of peroxisome proliferator-activated receptor activation by its endogenous ligand 15-deoxy 12,14 prostaglandin J2 on nitric oxide production in term placental tissues from diabetic women

Diabetes induces alterations which condition placental remodelling. The levels of nitric oxide (NO) (a modulator of placental invasiveness, differentiation and proliferation) were higher in term placental explants from diabetic patients when compared to controls. Peroxisome proliferator-activated receptor gamma (PPARgamma) activation by its endogenous ligand 15-deoxy Delta(12,14)prostaglandin J(2) (15dPGJ(2)), is a differentiating factor of adipocytes and other cell types, such as trophoblasts. 15dPGJ(2) is also able to down-regulate NO production in different cell types. Our study evaluated the levels of 15dPGJ(2) and PPARgamma and the influence of PPARgamma activation by 15dPGJ(2) on the production of NO, in term placental tissues from control, pre-gestational and gestational diabetic patients. Our results showed that 15dPGJ(2) was present in human term placenta, and that its levels were diminished in gestational (P<0.05) and pre-gestational (P<0.002) diabetic women when compared to controls. Exogenous 15dPGJ(2) addition (2 x 10(-6) mol/l) down-regulated NO production in placenta from control (P<0.001) and pre-gestational diabetic (P<0.01) patients, but failed to do so in gestational diabetic women, whose placental PPARgamma expression was diminished in comparison to controls (P<0.001). As the exogenous activation of PPARgamma prevented NO overproduction in placenta from pre-gestational diabetic women, it may have the potential to improve fetal outcome in this pathology.

Iron deficiency alters auditory recognition memory in newborn infants of diabetic mothers

Infants of diabetic mothers (IDMs) are at risk for perinatal brain iron deficiency that may target the developing hippocampus. The objective of this study was to evaluate hippocampally based recognition memory and infant development in IDMs with suspected brain iron deficiency (BID; cord ferritin </=34 microg/L) compared with IDMs with sufficient brain iron stores (BIS; cord ferritin >34 microg/L) using event-related potentials (ERPs). ERPs assessed neonatal auditory cortical responses to sounds and auditory recognition memory in response to the mother's voice compared with a stranger's voice. Thirty-two newborn IDMs had cord serum ferritin concentrations and provided neonatal ERP data (n = 23) and/or blinded 1 y developmental assessments (n = 28). Auditory cortical responses to speech and nonspeech sounds were similar in the BID and BIS groups. In the maternal voice recognition paradigm, peak latencies were shorter in the BID group than in the BIS group. Infants in the BIS group displayed a significant negative slow wave for the strangers' voices compared with the mothers' voices, whereas the BID group did not. Higher cord ferritin concentrations were correlated with larger negative slow waves at the right temporal (T4) electrode site. At 1 y of age, motor development was slower in the BID group than in the BIS group. IDMs suspected to have BID demonstrated impaired neonatal auditory recognition memory and lower psychomotor developmental scores at 1 y of age than IDMs with BIS. These impairments map onto areas of the developing brain known to be vulnerable to iron deficiency.

The safety and efficacy of insulin analogs in pregnancy

Diabetes during pregnancy is accompanied by increasing needs for maternal insulin and ongoing biological changes that cause maternal insulin requirements to reach higher and lower extremes throughout the day than in non-pregnant patients. As maternal hyperglycemia increases the risk of fetal and maternal morbidity, it is essential for the mother to maintain normoglycemia during pregnancy. With the advent of insulin analogs that feature improved absorption and physiological profiles over human insulin, the achievement of normoglycemia throughout pregnancy has become more attainable. This review provides a discussion of the application of the insulin analogs to diabetes during pregnancy and compares the benefits of rapid-acting insulin analogs with long-acting insulin analogs during pregnancy. This review further proposes a treatment protocol for achieving and maintaining normoglycemia throughout pregnancy.

Transient otoacoustic emissions in infants of diabetic mothers

BACKGROUND

Nursing infants of diabetic mothers require special care.

AIM

To verify whether the metabolic alteration during pregnancy is able to alter the cochlear function and the efferent olivocochlear system.

METHOD

Transient otoacoustic emissions of 30 children of diabetic mothers were analyzed, comparing the results to a control group, according to the occurrence and amplitude of the responses.

RESULT

The children of diabetic mothers presented contractile activity of the outer hair cells with a lower response amplitude.

CONCLUSION

The results did not show a statistically significant difference. Further studies with larger samples are necessary.

Expression of angiopoietic factors in normal and type-I diabetes human placenta: a pilot study

OBJECTIVES

Morphological changes of blood vessel wall have been described in placenta from pregnancies complicated by diabetes mellitus type-I.

STUDY DESIGN

We measured mRNA expression of vascular endothelial growth factor (VEGF), angiopoietin 1 and 2 (Ang-1 and Ang-2), their receptors VEGFR-1, VEGFR-2, Tie-2, fibroblast growth factor 2 (FGF-2), and its receptor FGF-2R in placental tissue of diabetes type-I patients, in normal term placenta, and endometrium of non-pregnant women by real time reverse transcriptase PCR.

RESULTS

The expression of Ang-2 and VEGFR-1 mRNAs was significantly higher in placenta (P<or=0.01). The expression of VEGF and VEGFR-2 mRNAs was significantly lower in normal term or diabetes type-I placenta compared to human endometrium (P<or=0.01). We did not detect a significant difference in the expression of Ang-1, Ang-2, Tie-2, VEGF, VEGFR-1, VEGFR-2, FGF-2, and FGF-2R in normal and diabetes type-I placenta.

CONCLUSION

These data show differential expression of Ang-2, VEGFR-1, VEGF, and VEGFR-2 in placenta and endometrium. The expression of Ang-1, Ang-2, Tie-2, VEGF, VEGFR-1, VEGFR-2, FGF-2, and FGF-2R was not different in normal and type-I diabetes placenta.

Vascular endothelial cadherin and beta-catenin in human fetoplacental vessels of pregnancies complicated by Type 1 diabetes: associations with angiogenesis and perturbed barrier function

AIMS/HYPOTHESIS

Increased angiogenesis of fetoplacental vessels is a feature of pregnancies complicated by Type 1 diabetes mellitus, but the underlying molecular mechanisms are unknown. This investigation tests whether the diabetic maternal environment alters the phenotypic expression of placental vascular endothelial cadherin and beta-catenin, which have been implicated as key molecules in barrier formation and angiogenesis in the endothelium.

METHODS

Term placental microvessels from normal pregnancies (n=8) and from those complicated by Type 1 diabetes (n=8) were perfused with 76-Mr dextran tracers (1 mg/ml) and subjected to immunocytochemistry, immunoblotting and microscopy. Junctional integrity, localisation and phosphorylation were investigated along with total protein levels of vascular endothelial cadherin, beta-catenin and vascular endothelial growth factor. Stereological sampling and estimation tools were used to quantify aspects of angiogenesis and endothelial proliferation.

RESULTS

In the Type 1 diabetic placentae, junctional localisations of vascular endothelial cadherin and beta-catenin altered significantly, with more than 50% of microvessels showing complete loss of immunoreactivity and with no overall loss of total protein. Tracer leakage was associated with these vessels. There was a two- to three-fold increase in vessels showing junctional phospho-tyrosine immunoreactivity and hyperphosphorylated beta-catenin. Vascular endothelial growth factor levels were higher in these placentae. A four-fold increase in endothelial proliferation was observed, along with an increase in total length of capillaries without any change in luminal diameter.

CONCLUSIONS/INTERPRETATION

Molecular perturbations of vascular endothelial cadherin and beta-catenin occur in fetoplacental vessels of pregnancies complicated by Type 1 diabetes. Phosphorylation and loss of these molecules from the adherens junctional domains may be influenced in part by the elevated levels of vascular endothelial growth factor in the placenta. Perturbations of the junctional proteins may explain the observed breach in barrier integrity and may contribute to the mechanisms that drive proliferation and increases in capillary length.

Placental growth hormone during pregnancy in a growth hormone deficient woman with type 1 diabetes compared to a matching diabetic control group

In pregnancy, pituitary growth hormone (GH) is gradually replaced by placental growth hormone (hPGH). GH deficient pregnant women may take advantage of GH substitution during pregnancy, but this issue still remains unresolved. Also, in pregnancy diabetes may cause macrosomia. The combination of GH deficiency, GH substitution therapy and type 1 diabetes mellitus may influence pregnancy in unforeseen ways. We present a case of pregnancy in a GH deficient woman with type 1 diabetes who continued on GH replacement until week 21. In gestational week 37 a thin and mildly small-for gestational-age (length 55 cm, +3 SD, 99th centile and weight 2445 g., -1.4 SD, 10th centile) but otherwise healthy boy was born. The patient had levels of serum hPGH at the lower end of the range of values found in a matching group of diabetic women. Serum IGF-I levels were at the upper end of the range of values in the control group. A positive correlation between serum hPGH and IGF-I values was seen in the control group when using the area-under-the-curve (r=0.84; p<0.001). The patient's child had lower birth weight and ponderal index, but was otherwise healthy. Serum IGF-I, but not hPGH, correlated to the absolute birth weight (r=0.63; p=0.015) and the birth weight z-score (r=0.55; p=0.039) in the control group. Serum hPGH and IGF-I declined rapidly after delivery. In conclusion, hPGH correlated to IGF-I in type 1 diabetes mellitus (DM), and IGF-I values correlated to the birth weight. Both type 1 diabetes mellitus and GH deficiency (with GH substitution therapy) may influence fetal growth, and in combination, the net influence may be difficult to predict.

[Ultrastructural examination of the placenta in pregnancy complicated by diabetes mellitus]

BACKGROUND

Causes of fetal hypoxia in diabetic pregnancy are still unknown. Investigation of placental vascular network seems of great importance in this research area. Abnormalities in the structure of capillaries in the vasculo-epithelial membranes and role of perivascular space may be an essential factor in explanation for fetal hypoxia in diabetic pregnant women. The aim of the study was to evaluate the relationship between the vascular surface of the terminal villi to its total surface, evaluation of the endothelial structure, perivascular space and basal membrane of the trophoblast as well as analysis of the studied parameters in relation to the classes of diabetes and metabolic control.

MATERIAL AND METHODS

The study was performed on 32 placentas from women with PGDM and GDM. There were 8 pregnant women in class G1 and G2, 15 in class B, C, D, 9 in class R/F and 8 in control group. The mean diurnal glycemia in the analysed groups ranged between 90 + 22 mg/dl and 100 + 55 mg/dl (in control group 80 + 12 mg/dl). HbA1c concentrations were between 6.7 + 0.9% and 7.6 + 1.0% (in control group 6.0 + 0.5%). Placentas were examined using light microscopy and electron microscopy Opton-Zeiss EM-900.

RESULTS

Decrease in the vascular surface of terminal villi was found in PGDM with fetal hypotrophy. In this cases we observed separation of basal membranes in basal capillaries and distention and proliferation of endothelial cells, disarrangements of perivascular space,. In placentas of women with hyperglycemia and fetal macrosomia there was a significant thickening of basal membranes of the trophoblast, and structural abnormalities in perivascular space with proliferation of collagen in terminal villi. Intensity of these changes was related to the degree of hyperglycemia and affected fetal and neonatal wellbeing. Examination of the placentas in women with PGDM with normal sugar levels before and during pregnancy revealed no or very limited pathological changes on light and electron microscopy. No significant relationships were shown between vascular surface in terminal villi and selected biochemical parameters and neonatal condition in diabetic pregnant women with fetal eutrophy

CONCLUSIONS

Pathologic changes in the placentas of diabetic women (significant thickening of basal membranes of trophoblast separation of basal membranes in basal capillaries, distention and proliferation of endothelial cells, disarrangements of perivascular space and decrease of vascular surface of terminal villi are significant factors contributing to fetal anoxia in pregnancy complicated by diabetes mellitus.

Implication of lipids in macrosomia of diabetic pregnancy: can n-3 polyunsaturated fatty acids exert beneficial effects?

Macrosomia or fetal obesity is a frequent complication of pregnancy in diabetes mellitus. Several alterations observed in carbohydrate and lipid metabolism in macrosomic infants of diabetic mothers are thought to be a consequence of maternal hyperglycaemia leading to fetal hyperinsulinaemia. Macrosomic infants of diabetic mothers are prone to the development of glucose intolerance, obesity and diabetes during childhood and adulthood. Furthermore, increasing evidence is accumulating regarding the importance of n -3 polyunsaturated fatty acids (PUFAs) in the reduction of plasma lipids and hyperglycaemia. In this review article, we shed light on the abnormalities in lipid metabolism in macrosomia. We also raise the question of the possible beneficial effects of n -3 PUFAs in diabetic pregnancy and in the prevention and treatment of long-term metabolic abnormalities associated with macrosomia.

Enhanced expression of transforming growth factor-beta isoforms in the neural tube of embryos derived from diabetic mice exposed to cyclophosphamide

We analyzed the expression pattern of transforming growth factor-beta isoforms (TGF-beta1, TGF-beta2 and TGF-beta3) in the developing brain of embryos derived from the normal and diabetic mice exposed to cyclophosphamide (CP), a cytotoxic teratogen. The CP-treated diabetic embryos showed significantly more TGF-beta1 and TGF-beta2 immunoreactive cells in the regions of telencephalon and diencephalon in comparison to that of CP-treated non-diabetic embryos. Moreover, no cells expressing TGF-beta isoforms were detectable in the developing brain of normal and diabetic embryos. The mRNA expression levels of TGF-beta isoforms were found to be significantly increased in the developing brain of CP-treated diabetic embryos compared to that of CP-treated non-diabetic embryos as measured by quantitative real time reverse transcription-polymerase chain reaction. The enhanced expression levels of TGF-beta isoforms appear to be associated with the increased frequency of neural tube defects observed in the diabetic embryos exposed to CP.

Human placental growth hormone, insulin-like growth factor I and -II, and insulin requirements during pregnancy in type 1 diabetes

Human placental GH (hPGH) replaces pituitary GH during pregnancy. hPGH is correlated to serum IGF-I in normal pregnancies and in pregnancies complicated by fetoplacental disorders. In gestational diabetes and type 2 diabetes no correlation between hPGH and IGF-I has been found. The relationship between hPGH and IGF-I in type 1 diabetes mellitus has not been investigated thoroughly. Furthermore, hPGH may be involved in the development of insulin resistance during pregnancy. In this prospective, longitudinal study, 51 type 1 diabetic subjects were followed with repeated blood sampling during pregnancy (median, 14 blood samples/subject; range, 8-26). Maternal concentrations of serum hPGH, IGF-I, and IGF-II were measured and compared with insulin requirements and birth characteristics. hPGH was detected from as early as 6 wk gestation. In all subjects, a rise in serum hPGH was observed during pregnancy, and the rise between wk 16 and 25 was correlated to the rise between wk 26 and 35 (P < 0.001). From wk 26 onward, the increase in hPGH values was significantly correlated to the birth weight, expressed as a z-score (r(s) = 0.54; P < 0.001), as were the absolute hPGH values. Also, a positive influence of hPGH on placental weight was found. Serum IGF-I values decreased significantly from the first to the second trimester (P </= 0.021). Serum hPGH correlated to serum IGF-I from wk 24-35, and changes in IGF-I followed the increase in hPGH between wk 26 and 35 (r(s) = 0.53; P < 0.001), as did IGF-II (r(s) = 0.37; P = 0.008). Changes in IGF-I and IGF-II between wk 26 and 35 also correlated to the birth weight z-score (P </= 0.020), but only hPGH remained significant in multiple regression analysis. Similar results were found in the subgroup delivering at term. Interestingly, the increase in hPGH was not correlated to the increase in insulin requirements, nor was any consistent relationship revealed during each gestational period. In conclusion, our study suggests a role for hPGH in the regulation of both IGFs and fetal growth in type 1 diabetes. In contrast, the increase in insulin requirements during pregnancy in type 1 diabetic subjects could not be related to hPGH levels.

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.

Human placental growth hormone, insulin-like growth factor I and -II, and insulin requirements during pregnancy in type 1 diabetes

Human placental GH (hPGH) replaces pituitary GH during pregnancy. hPGH is correlated to serum IGF-I in normal pregnancies and in pregnancies complicated by fetoplacental disorders. In gestational diabetes and type 2 diabetes no correlation between hPGH and IGF-I has been found. The relationship between hPGH and IGF-I in type 1 diabetes mellitus has not been investigated thoroughly. Furthermore, hPGH may be involved in the development of insulin resistance during pregnancy. In this prospective, longitudinal study, 51 type 1 diabetic subjects were followed with repeated blood sampling during pregnancy (median, 14 blood samples/subject; range, 8-26). Maternal concentrations of serum hPGH, IGF-I, and IGF-II were measured and compared with insulin requirements and birth characteristics. hPGH was detected from as early as 6 wk gestation. In all subjects, a rise in serum hPGH was observed during pregnancy, and the rise between wk 16 and 25 was correlated to the rise between wk 26 and 35 (P < 0.001). From wk 26 onward, the increase in hPGH values was significantly correlated to the birth weight, expressed as a z-score (r(s) = 0.54; P < 0.001), as were the absolute hPGH values. Also, a positive influence of hPGH on placental weight was found. Serum IGF-I values decreased significantly from the first to the second trimester (P < or = 0.021). Serum hPGH correlated to serum IGF-I from wk 24- 35, and changes in IGF-I followed the increase in hPGH between wk 26-35 (r(s) = 0.53; P < 0.001), as did IGF-II (r(s) = 0.37; P = 0.008). Changes in IGF-I and IGF-II between wk 26-35 also correlated to the birth weight z-score (P < or = 0.020), but only hPGH remained significant in multiple regression analysis. Similar results were found in the subgroup delivering at term. Interestingly, the increase in hPGH was not correlated to the increase in insulin requirements, nor was any consistent relationship revealed during each gestational period. In conclusion, our study suggests a role for hPGH in the regulation of both IGFs and fetal growth in type 1 diabetes. In contrast, the increase in insulin requirements during pregnancy in type 1 diabetic subjects could not be related to hPGH levels.

[Pregnancy complications can impair placental transport systems. Aberrant fetal growth, for example in diabetes, is only now beginning to be understood]

The reduced fetal growth in intrauterine growth restriction (IUGR) has been attributed to decreased placental blood flow whereas maternal hyperglycemia is believed to represent the primary cause of accelerated fetal growth in pregnancies complicated by diabetes. However, recent research has demonstrated specific changes in placental transport function in association to these pregnancy complications that are likely to contribute to the altered fetal growth patterns. For example, in IUGR the activity of certain key amino acid transporters is reduced in the placental barrier and accelerated fetal growth in diabetes is associated with an increased activity of placental glucose and amino acid transporters. Therefore, placental insufficiency in IUGR is not just a question of reduced placental blood flow and up-regulation of placental nutrient transporters in diabetes may explain the high incidence of accelerated fetal growth despite rigorous maternal glycemic control.

Third trimester glycemic profiles and fetal growth

Diabetes is a common complication of pregnancy. Third trimester hyperglycemia has been associated in both gestational and pregestational diabetes with deviant fetal growth. Recent studies demonstrated that peak postprandial glucose levels in normal pregnancy are lower than previously thought. This finding could explain the lack of effectiveness reported by some investigators in achieving a rate of macrosomia similar to the general population. Among different possible blood glucose determinations, it appears that 1-hour postprandial as well as the overall mean blood glucose levels are the most closely correlated with fetal growth. It seems that a narrow window of glycemic levels is associated with optimal fetal growth because excessively tight glycemic control has been associated with increased incidence of small-for-gestational-age infants.

Bone in the pregnant mother and newborn at birth

BACKGROUND

Changes in maternal bone during pregnancy may affect fetal bone mineralization.

ISSUES

The biphasic changes in maternal bone histology (temporary loss of cancellous bone in early pregnancy restored by term gestation) are consistent with corresponding blood biochemistry changes; increased bone resorption markers in the first trimester, while bone formation markers increased in the last trimester. Postpartum bone mineral density (BMD) by DEXA is increased at cortical bone and decreased at trabecular bone sites compared with prepregnancy values. The mean reduction of spine BMD is 3.5% from prepregnancy to immediate postpartum. Neonatal bone mineral content (BMC) is different by season of birth, low weight relative to gestation, and having a diabetic mother. Lower total body BMC and high bone resorption marker in winter vs. summer-born newborns was related to low vitamin D, indicating alterations of fetal bone metabolism by maternal D deficiency. Lower BMC and decreased bone formation marker in infants born small for gestational age than those born appropriate for gestation may relate to reduced transplacental mineral transfer. Low BMC in infants of diabetic mother was correlated inversely with poor control of maternal diabetes during early pregnancy.

CONCLUSIONS

During pregnancy, maternal bone mineral metabolism are changed, and influences on fetal bone mineralization occur in utero.

Maternal-fetal transport of hypoglycaemic drugs

Due to legal, ethical and monetary problems, drug studies in pregnancy are rare. Numerous pharmacokinetic and pharmacodynamic changes occur in pregnancy that can affect the efficacy and safety of drugs, and these are difficult to predict without appropriate studies. Drugs potentially useful and safe in pregnancy have to either not cross the placenta and/or be harmless to the fetus at clinically relevant concentrations. The first characteristic can be predicted using in vitro models such as the placenta perfusion model. In the case of glibenclamide (glyburide), in vitro experiments showed minimal maternal-fetal transfer, leading to completion of a successful clinical trial of this drug in gestational diabetes. Insulin, the main drug used in diabetes during pregnancy, has also been shown not to cross the placenta in vitro, as has insulin lispro. Animal insulin may cross the placenta when complexed with anti-insulin antibodies. Other sulphonylurea drugs (tolbutamide and chlorpropamide) have been shown to cross the placenta both in vitro and in vivo and to produce toxicity in the fetus. This review summarises the pharmacokinetic data available for hypoglycaemic drugs during pregnancy, as well as the potential role for the in vitro placenta perfusion model in the preclinical evaluation of drugs with potential usefulness in pregnancy.

The effect of metabolic control on fetal nuchal translucency in women with insulin-dependent diabetes: a preliminary study

OBJECTIVE

Diabetes could potentially alter fetal nuchal translucency (NT) measurements mainly by increasing microvascular permeability. The aim of this study was to test this hypothesis.

METHODS

Sixty-five women with pre-pregnancy insulin-dependent diabetes mellitus undergoing NT screening were evaluated. The main outcome measure was the NT measurement, expressed as both absolute measurements and delta values (number of standard deviations by which the observed value differed from the normal mean for the same gestation). The relationships between NT and years of diabetes, insulin dose, glycosylated hemoglobin, and glycemic capillary profiles ('tight' glycemic control) were studied.

RESULTS

There was no significant correlation between NT and any of the studied parameters. There were no differences in NT according to the result of either glycosylated hemoglobin or 'tight' control.

CONCLUSIONS

Metabolic control does not affect the result of ultrasound-determined fetal NT measurement which, when available, seems to be the best option for screening for Down syndrome in women with diabetes mellitus.

Maternal diabetes mellitus is associated with altered deposition of fibrin-type fibrinoid at the villous surface in term placentae

Placentae from control and diabetic patients were used to test three null hypothesis: (1) there are no significant group differences in the volumes of villous syncytiotrophoblast compartments or intervillous fibrin-type fibrinoid, (2) perivillous fibrin-type fibrinoid is deposited randomly at the surface of trophoblast, and (3) amounts and deposition patterns of perivillous fibrin-type fibrinoid do not vary between groups. Term placentae were collected from non-diabetic subjects and five groups of diabetic women classified according to duration, severity and insulin dependence. Tissue specimens and sections were obtained by uniform random sampling. Volumes and surface areas of fibrin-type fibrinoid and trophoblast compartments (thin, syncytial knot, syncytial bridge and denuded regions) were estimated stereologically and compared using variance, chi-squared and contingency table analyses. As to null hypothesis (1), no group differences in volumes of trophoblast compartments were found but volumes of intervillous fibrin-type fibrinoid were greater in the non-insulin-dependent diabetic group. As to null hypothesis (2), regardless of group, fibrin-type fibrinoid was deposited preferentially at sites of denudation in every placenta examined. As to null hypothesis (3), villous surface areas occupied by perivillous fibrin-type fibrinoid were greater in type 1 (insulin-dependent) diabetics with complications (diabetic nephropathy or retinopathy). The surfaces of trophoblast occupied by fibrin-type fibrinoid were also notably larger in non-insulin-dependent diabetics and type 1 diabetics with complications. Except for the surface of denudation sites (which also increased in diabetes), there were no differences in the surfaces of trophoblast regions. These results confirm that the haemostatic steady state is perturbed in the diabetic placenta, that perivillous fibrin-type fibrinoid is deposited preferentially at sites of epithelial loss/damage, and that some diabetic groups are affected differentially.

Amniotic fluid insulin levels and fetal abdominal circumference at time of amniocentesis in pregnancies with diabetes

AIMS

Fetal hyperinsulinism is a strong predictor for excessive growth and fetopathy in pregnancies complicated by diabetes. We examined (i). the relationship between measurements of amniotic fluid insulin (AF insulin) and fetal abdominal circumference (AC) at the time of amniocentesis, and (ii). whether there is a threshold for fetal AC percentiles which can identify low vs. high-risk levels of AF insulin without performing an amniocentesis.

METHODS

In a retrospective study, AF insulin from 121 pregnant diabetic women (32 pregestational; 89 gestational) was measured during the 3rd trimester as part of a diabetes management protocol. AC measurements were transformed into a continuous variable of percentile growth for gestational age (Hadlock). Division of the cohort according to deciles or quartiles of AC percentiles was performed to identify a threshold AC with a significant increase in elevated AF insulin, previously defined as AF insulin >or= 7 microU/ml. A receiver operator characteristic (ROC) curve was created and the negative predictive value (NPV) of the determined threshold was calculated.

RESULTS

AF insulin levels were significantly correlated with the AC percentiles (r = 0.3, P = 0.0005) by linear regression. No AC threshold could reliably identify a moderate elevated AF insulin >or= 7 microU/ml (NPV 77.2%), but an AC threshold >or= 75th percentile could identify with fetal hyperinsulinism with an AF insulin >or= 16 microU/ml. All 10 cases of AF insulin >or= 16 microU/ml were identified with a NPV of 100% (74/74).

CONCLUSIONS

Our data indicate that an AC >or= 75th percentile determined by a 3rd trimester ultrasound examination may discriminate between pregnancies at low vs. high risk for AF insulin >or= 16 microU/ml. This AF insulin concentration corresponds to a level of hyperinsulinism reported to be associated with considerable neonatal and long term morbidity.

Suppression of Na+-H+ exchanger-1 in placentas of type 2 diabetic pregnant women: possible functional implication

Placental Na(+)/H(+) exchanger (NHE-1), which plays an important role in maintaining fetal and maternal Na+ and H+ homeostasis, is uniquely regulated. However, the role of this protein in type-2 diabetic placentas, and the molecular basis for its unique regulation in normal placenta remain poorly understood. To address these issues, a C-terminus regulatory domain of NHE-1 was cloned and sequenced from normal human placentas, and was used to prepare a GST-fusion protein for raising polyclonal antibodies. For this study, age-matched type 2 diabetic (n=8) and normal (n=8) pregnant women were recruited to investigate the effects of controlled hyperglycemia on the expression of placental NHE-1 at term delivery. The C-terminal sequence in the normal human placental isoform was identical to that reported for other tissues. The antibodies reacted selectively with a 110 kD protein. The level of NHE-1 protein was decreased significantly ( p<0.05) in diabetic placentas, whereas beta-actin, an internal control, remained unaltered. Yield of placental crude microsomes was significantly higher from diabetic placentas. Interestingly, the levels of NHE-1 mRNA and beta-actin mRNA did not change in diabetic pregnancies. Blood pressure values of the mothers in both groups were also normal. The placental mass and weight of babies were slightly increased, whereas the gestational age was lower in diabetic pregnancies. These results suggest that the unique regulation of placental NHE-1 is not due to differences in its C-terminus structure. Lack of a significant correlation between the suppression of NHE-1 and gestational age, placental mass or birth weight in the diabetic pregnancies suggests that suppression is independent of these parameters, and is regulated post-transcriptionally. This change in NHE-1 may contribute to an adequate provision of electrolytes and nutrients to the fetus.

Placental leptin receptor isoforms in normal and pathological pregnancies

Alternate mRNA splicing of human leptin receptor generates four membrane isoforms with different C-terminal sequences. They differ by the length of their intracellular domain which include specific motifs crucial for the specificity of leptin signalling. As a step towards functional studies, we have characterized leptin receptors in human placenta from normal pregnancies and pregnancies associated with diabetes and pre-eclampsia. Leptin and leptin receptors were visualized by immunohistochemistry of placentas obtained from first and third trimester pregnancies. Antibodies against N and C-terminal epitopes showed signals in the apical membrane of the syncytiotrophoblast in early and term placental villi as well as in JAr and BeWo derived trophoblast cells. In addition, a distinct isoform recognized by its extracellular juxtamembrane epitope was exclusively localized in cytotrophoblast cells and likely stains the soluble receptor. At contrast with the transmembrane receptors, the expression of this isoform is increased in placentas of pre-eclamptic and diabetic women which synthesize more leptin than placenta from uncomplicated pregnancy. These data demonstrate that short and long transmembrane leptin receptors are expressed in the trophoblast and indicate that leptin synthetized within the placenta can act locally through both receptor isoforms. Being also accessible to leptin from maternal origin, these transmembrane receptors may signal differently in pregnancy with normal and increased leptin production. The co-localization of leptin and the soluble receptor isoform suggests that this isoform serves for modulating maternal free leptin levels through modification of leptin binding capacities.

Localization of glycogen in the placenta and fetal and maternal livers of cadmium-exposed diabetic pregnant rats

This study was designed to investigate the effects of Cd exposure on the glycogen localization in the placenta and in fetal and maternal livers in streptozotocin (STZ)-induced-diabetic pregnant rats. Ninety-nine virgin female Wistar rats (200-220 g) were mated with 33 males for at least 12 h. From the onset of pregnancy, the rats were divided into four experimental groups (control, Cd treated, STZ treated, and Cd+STZ treated). The Cd-treated group was injected subcutaneously daily with CdCl2 dissolved in isotonic NaCl, starting at the onset of pregnancy throughout the experiment. Diabetes was induced on d 13 of pregnancy by a single intraperitoneal injection of STZ in the STZ-treated group. In addition to the daily injection of Cd, a single intraperitoneal injection of STZ was also given on d 13 of pregnancy in the Cd+STZ-treated group. The rats received the last injection 24 h before being sacrificed and 10 randomly selected rats in each group were sacrificed on d 15 and d 20 of pregnancy. Blood samples were taken for determination of the serum glucose and insulin levels. Fetal and maternal livers of sacrificed rats in all groups were harvested on d 15 and d 20 of pregnancy, whereas placentas were harvested only on d 20 of pregnancy for histochemical examination. Although both Cd and STZ caused hyperglycemia and decreased insulin secretion, Cd-alone treatment increased the glycogen content only in the placental labyrinth, whereas STZ-alone treatment increased the glycogen content only in the maternal part of the placenta. Increased glycogen localization was observed in both the placental labyrinth and the maternal part of placenta when Cd and STZ were given together. Fetal and maternal livers of control and other treatment groups were not different regarding the glycogen content on d 15 or d 20 of pregnancy. It was concluded that Cd exposure during pregnancy might produce a glycogen localization in the placenta of diabetic rats. However, the function and the mechanisms of increased glycogen contents in the placenta of Cd-exposed pregnant diabetic rats remain unclear and further studies are needed.

Oxidative stress and altered prostanoid production in the placenta of streptozotocin-induced diabetic rats

The oxidative stress in placental tissues during late pregnancy, as well as the relationship between reactive oxygen species (ROS) and the arachidonic acid (AA) pathway was evaluated in a neonatal streptozotocin (STZ)-induced diabetic rat model. Lipoperoxide levels are increased in diabetic tissues compared with control tissues (P<0.001) and they seem to increase throughout the development of gestation both in control (P<0.05) and STZ-induced diabetic (P<0.001) rats. Superoxide dismutase (SOD) activity is not modified on different days of pregnancy, but enzymatic activity is lower in diabetic tissues than in control tissues (P<0.01). Labour is preceded by an increase in placental 14C-prostaglandin conversion from 14C-AA in control and diabetic animals (P<0.05) and the thromboxane B2 (TXB2)/6-keto-prostaglandin F1alpha (PGF1alpha) ratio is higher in diabetic placental tissues than in controls. The addition of SOD and glutathione to the incubation medium does not modify prostanoid levels in control rats, but does decrease the AA conversion to PGF2alpha, PGE2 and TXB2 (P<0.05) in diabetic placenta. Superoxide radical generation (hypoxanthine/xanthine oxidase or hydrogen peroxide added to the incubation medium) produces a decrease in 6-keto-PGF1alpha (P<0.05) in control and diabetic tissues, whereas PGF2alpha, PGE2 and TXB2 levels, and PGF2alpha and TXB2 production are increased in control and diabetic animals respectively (P<0.05). Diabetic pregnant rats supplemented with a diet containing 400 mg day(-1) of alpha-tocopherol (vitamin E) have diminished placental PGF2alpha and TXB2 production and lipoperoxide levels. The results show a higher TXB2 and a decreased 6-keto-PGF1alpha placental production that may be linked to increased oxidative stress and to a reduced antioxidant capacity in STZ-induced diabetic rats. These imbalances, probably involved in abnormal placental structure and function, may potentially be corrected with dietary supplementation of alpha-tocopherol in diabetic pregnancies.

[Biochemical changes in pregnant diabetics]

In the course of pregnancy increasing insulin resistance develops due to deteriorated phosphorylation of the insulin receptor and its substrate (IRS-1). As a result of relations between secretion and the action of insulin the beta-cell reacts by insulin hypersecretion and thus the development of hyperinsulinaemia is influenced. Furthermore pregnancy is characterized by increasing differences between the anabolic and catabolic stage in the intermediary metabolism manifested in particular by a tendency towards ketosis and hypoglycaemia during fasting and also by hypoaminoacidaemia. In addition to these metabolic changes there are also other laboratory deviations, manifested e.g. by hyperfibrinogenaemia and an increased concentration of tPA inhibitor (PAI-1) without detectable endothelial dysfunction. The increasing albuminuria is not a manifestation of developing nephropathy but the sign of functional changes which after delivery disappear very quickly. The mentioned deviations are the consequence of altered hormonal regulations in the course of pregnancy, while after delivery the baseline state present before pregnancy is restored.

Modulation of nitric oxide concentration and lipid metabolism by 15-deoxy Delta12,14prostaglandin J2 in embryos from control and diabetic rats during early organogenesis

The concentration of 15-deoxy Delta(12,14)PGJ(2) (15dPGJ(2)) and its effects on nitric oxide generation and neutral lipid in embryos from control and neonatal streptozotocin-induced (n-stz) diabetic rats during organogenesis were investigated. 15dPGJ(2) is produced in embryos during organogenesis, and its production is lower in embryos of n-stz diabetic rats than in embryos from control rats. Nitrate and nitrite concentrations were higher in embryos from n-stz diabetic rats and were reduced in the presence of 15dPGJ(2) both in embryos from control and diabetic rats. Thus, decreased 15dPGJ(2) concentrations in embryos from n-stz diabetic rats may be related to the high nitric oxide concentrations found in those embryos. Exogenous 15dPGJ(2) decreased cholesterol and cholesteryl ester concentrations in embryos from control and n-stz diabetic rats, and reduced triacylglycerol concentrations in control embryos. Incorporation of [(14)C]acetate into lipids showed decreased de novo synthesis of cholesteryl ester and triacylglycerides in embryos from n-stz diabetic rats compared with controls. Exogenous 15dPGJ(2) reduced the incorporation of [(14)C]acetate into triacylglycerides, cholesterol and cholesteryl ester in embryos from both control and n-stz diabetic rats. 15dPGJ(2) is present in embryos during organogenesis, and reduces embryonic nitric oxide production and lipid synthesis. The lower 15dPGJ(2) concentration in embryos from n-stz diabetic rats may result in developmental alterations in this diabetic model.

Maternal glycemic control and umbilical artery Doppler velocimetry

OBJECTIVE

To determine whether information from umbilical artery Doppler flow velocity waveforms significantly improves the prediction of adverse perinatal outcome, independently of maternal glycemic control, in pregnancies complicated by diabetes.

STUDY DESIGN

The medical records of 277 pregnant women with diabetes were reviewed. Glycemic control was determined by glycosylated hemoglobin concentration and umbilical artery Doppler velocimetry by using systolic/diastolic ratios (S:D), both obtained during the third trimester. Pregnancies with adverse perinatal outcome were compared to those with good outcome. Logistic regression analysis was used to adjust for glycemic control, and to test whether an elevated umbilical artery Doppler S:D ratio was independently associated with pregnancy outcome.

RESULTS

Adverse pregnancy outcome occurred in 51.6% of these pregnancies (143/277). The mean third-trimester glycosylated hemoglobin (7.7 +/- 1.9% vs. 6.7 +/- 1.3%, p < 0.001) and the umbilical artery S:D ratio were significantly higher (2.6 +/- 0.6 vs. 2.4 +/- 0.3, p < 0.001) in the pregnancies with adverse outcome. Logistic regression analysis showed that umbilical artery S:D ratio was an independent predictor of adverse perinatal outcome after adjusting for the third-trimester glycosylated hemoglobin level. Forty per cent of patients with normal Doppler findings (S:D ratio of < 3.0) and normal glycemic control values (glycosylated hemoglobin level of < 7.5%) had an adverse pregnancy outcome. Sixty-three per cent of patients with an abnormal result for one of these tests had an adverse pregnancy outcome. Ninety-six per cent of patients with both abnormal Doppler findings and abnormal glycemic control had an adverse pregnancy outcome.

CONCLUSION

Umbilical artery Doppler velocimetry improves the predictive value for adverse perinatal outcome, independently of glycemic control, in pregnancies complicated by diabetes. The combination of an abnormal umbilical artery S:D ratio and abnormal glycosylated hemoglobin was strongly associated with adverse pregnancy outcome.

The use of lamellar body counts to predict fetal lung maturity in pregnancies complicated by diabetes mellitus

OBJECTIVE

The purpose of this study was (1) to correlate amniotic fluid lamellar body counts with the lecithin/sphingomyelin ratio and the presence of phosphatidylglycerol in pregnancies that were complicated by maternal diabetes mellitus and (2) to determine a lamellar body count value that maximizes sensitivity and specificity in the prediction of fetal lung maturity.

STUDY DESIGN

We reviewed our prospectively collected perinatal database from November 1992 through October 1999 to identify pregnancies that were complicated by diabetes mellitus for which fetal lung maturity studies had been performed within 72 hours of delivery. Lamellar body counts were correlated with lecithin-sphingomyelin ratio and phosphatidylglycerol values. The sensitivities and specificities of various lamellar body count cutoff values were calculated with the lecithin/sphingomyelin ratio and phosphatidylglycerol values as indicators of fetal lung maturity. Receiver operating curves were used to determine the lamellar body count that indicated fetal lung maturity. Our neonatal database was reviewed for this same time period to obtain all cases of respiratory distress syndrome. The maternal data were compared with the neonatal data to determine whether distress syndrome had developed in an infant who had undergone fetal lung maturity testing respiratory.

RESULTS

Lamellar body counts were correlated with lecithin/sphingomyelin ratio (r = 0.51, P <.001) and phosphatidylglycerol values (r = 0.57, P <.001) in 90 diabetic pregnant patients. A lamellar body count of 37,000/microL was found to have a sensitivity of 80% and a specificity of 100% in the prediction of fetal lung maturity by standardized methods of phospholipid analysis. There were no cases of neonatal respiratory distress syndrome in this study population.

CONCLUSION

The lamellar body count is a valid, rapid screening test for the determination of biochemical fetal lung maturity in pregnancies that are complicated by diabetes mellitus. A lamellar body count of > or =37,000/microL correlated with the lecithin/sphingomyelin ratio and phosphatidylglycerol values in the pregnancies of diabetic patients. Use of lamellar body counts in pregnancies that are complicated by diabetes mellitus could decrease the need for time-consuming and more costly phospholipid profiles. A full phospholipid profile is recommended for amniotic fluid specimens with lamellar body count values of <37,000/microL.

Postpartum maternal levels of hemoglobin A1c and cord C-peptide in macrosomic infants of non-diabetic mothers

OBJECTIVE

This study was designed to test the hypothesis that macrosomia in infants born to non-diabetic mothers is associated with an increased incidence of hyperinsulinemia and normal maternal glucose regulation in late pregnancy.

METHODS

Twenty mothers and their macrosomic infants were chosen as the study group, and 20 mothers with their appropriate-for-gestational-age infants were chosen as the control group.

RESULTS

No difference in postpartum mean hemoglobin A1c levels was observed between the mothers of macrosomic infants and those of control infants. Cord plasma C-peptide levels were significantly higher in macrosomic than in control infants.

CONCLUSIONS

This study revealed that macrosomic infants of non-diabetic mothers were significantly more likely to have hyperinsulinemia than were normal-sized infants, and this hyperinsulinemia was not caused by dysregulation in glucose metabolism.

Signs of platelet activation, but not lipid peroxidation, in fetal blood associated with functional and structural umbilicoplacental lesions in pregnancies complicated by impaired glucose metabolism

OBJECTIVES

To study the influence of platelet activation and lipid peroxidation in fetal blood on umbilical vascular prostanoid synthesis and placental morphology in diabetic pregnancy.

METHODS

The concentrations of thromboxane A2 (TxA2) and malondialdehyde (MDA) were determined in umbilical cord plasma in 21 women with diabetes mellitus/impaired glucose tolerance (DM/IGT) and ten healthy women. Segments from the umbilical artery and vein were incubated and prostacyclin (PGI2) and TxA2 metabolites were determined. Prostanoid synthesis was stimulated with calcium ionophore at a second incubation. Histological examination was carried out in samples from the umbilical cord, membranes and placental parenchyma. Non-parametric statistical analysis was used, with a two-tailed p < 0.05 considered statistically significant.

RESULTS

Cord plasma TxA2, but not MDA, was higher among DM/IGT women (p = 0.07). There were indications that cord plasma TxA2, but not MDA, was positively correlated with vascular prostanoid synthesis and synthesis capacity. In the umbilical vein, both the basal and stimulated PGI2 production and the stimulated TxA2 production were lower in the DM/IGT group. Ischemic placental lesions were associated with a high TxA, and a low MDA concentration in cord plasma.

CONCLUSIONS

Even in less severe forms of impaired glucose metabolism, disturbances in platelet activation significantly affect both biochemical and morphological vessel wall and tissue functions in the umbilicoplacental unit. This could indicate an abnormal programming of fetal cell functions and designate cases at increased risk of developing cellular and organ damage.

Optimal thresholds of the lecithin/sphingomyelin ratio and lamellar body count for the prediction of the presence of phosphatidyl glycerol in diabetic women

OBJECTIVE

To assess the optimal thresholds of the lecithin/sphingomyelin (L/S) ratio and lamellar body count for the prediction of the presence of phosphatidyl glycerol (PG) in diabetic pregnant women.

METHODS

We accessed a database of clear amniotic fluid specimens obtained by transabdominal amniocentesis in diabetic women with singleton non-malformed fetuses. PG results were classified as 'absent' or 'present'. Receiver operating characteristic (ROC) curve analysis was constructed of different L/S ratios and lamellar body counts to identify the optimal threshold for prediction of the presence of PG. Sensitivity was defined as the rate of L/S ratio and lamellar body count above specific thresholds among cases with present PG. The false-positive rate was that of L/S ratios or lamellar body counts above specific thresholds among cases with absent PG. Statistical analysis included one-way analysis of variance with post-hoc analysis, with p < 0.05 considered significant.

RESULTS

A total of 76 consecutive women were included in the analysis, 74% (n = 56) using insulin and the remainder treated by diet alone. L/S and PG results were both available in 72 women. PG was reported as 'present' in 70% (51/73) of specimens. As expected, there was a significant relationship between L/S ratios and presence of PG (area under the curve = 0.932, p < 0.001). An L/S ratio of > or = 3.0 represented the optimal trade-off between sensitivity (68%) and false-positive rate (6%) in the prediction of present PG. Similarly, there was a significant relationship between lamellar body count values and presence of PG (area under the curve = 0.976, p < 0.001). A lamellar body count of > or = 50 000 represented the optimal trade-off between sensitivity (92%) and false-positive rate (0%) in the prediction of present PG.

CONCLUSION

In diabetic pregnant patients, the presence of PG in the amniotic fluid more closely corresponded to an L/S ratio of > or = 3.0 or to a lamellar body count of > or = 50,000.

The utility and efficacy of the new insulins in the management of diabetes and pregnancy

The quest for tight glucose control has led to the development of insulin analogues (insulin lispro, insulin aspart, insulin glargine) designed to optimize glucose control while minimizing the impact of insulin therapy on daily life. Women with diabetes are increasingly likely to become pregnant on these new products and to benefit from their use while pregnant. Caution over the use of new medications in pregnancy has limited experience, but increasing evidence is emerging that use of insulin lispro is not associated with excess risk of fetal malformations, is associated with similar or better outcomes during pregnancy, and is preferred over regular insulin. Similar evidence for the other insulin analogues has yet to emerge, but is unlikely to be dissimilar.

Liver triacylglycerols and free fatty acids in streptozotocin-induced diabetic rats have atypical n-6 and n-3 pattern

In diabetes there is a decrease in membrane arachidonic (AA) and docosahexaenoic (DHA) acids and a concomitant increase in linoleic (LA) and alpha-linolenic (ALA) acids. This metabolic perturbation is thought to be due to impaired activity of Delta(6)- and Delta(5)-desaturases. Triacylglycerols are the major lipid pool in plasma and liver tissue and have a significant influence on fatty acid composition of membrane and circulating phospholipids. Data on the distribution of n-6 and n-3 polyunsaturated fatty acids of triacylglycerols in diabetes are sparse. We investigated whether streptozotocin-induced diabetes in Sprague-Dawley rats alters fatty acid composition of triacylglycerols and free fatty acids of liver tissue. The animals were fed a breeding diet prior to mating, during pregnancy and lactation. On days 1-2 of pregnancy, diabetes was induced in 10 of the 25 rats. Liver was obtained at post partum day 16 for analysis. Relative levels of LA (P=0.03), dihomo-gamma-linolenic acid (DHGLA) (P=0.02), AA (P=0.049), total n-6 (P=0.02), ALA (P=0.013), eicosapentaenoic acid (EPA) (P=0.004), docosapentaenoic acid (22:5n-3, DPA) (P=0.013), DHA (P=0.033), n-3 metabolites (P=0.015) and total n-3 (P=0.011) were significantly higher in the triacylglycerols of the diabetics compared with the controls. Similarly, liver free fatty acids of the diabetics had higher levels of LA (P=0.0001), DHGLA (P=0.001), AA (P=0.001), n-6 metabolites (P=0.002), total n-6 (P=0.0001), ALA (P=0.003), EPA (P=0.015), docosapentaenoic (22:5n-3, P=0.003), DHA (P=0.002), n-3 metabolites (P=0.005) and total n-3 (P=0.001). We conclude that impaired activity of desaturases and/or long chain acyl-CoA synthetase could not explain the higher levels of AA, DHA and n-6 and n-3 metabolites in the diabetics. This seems to be consistent with an alteration in the regulatory mechanism, which directs incorporation of polyunsaturated fatty acids either into triacylglycerols or phospholipids.

Alterations in the activity of placental amino acid transporters in pregnancies complicated by diabetes

Alterations in placental transport may contribute to accelerated fetal growth in pregnancies complicated by diabetes. We studied the activity of the syncytiotrophoblast amino acid transporter system A and the transport of the essential amino acids leucine, lysine, and taurine. Syncytiotrophoblast microvillous plasma membranes (MVMs) and basal plasma membranes (BMs) were isolated from placentas obtained from normal pregnancies and pregnancies complicated by gestational diabetes mellitus (GDM) and type 1 diabetes, with and without large-for-gestational-age (LGA) fetuses. Amino acid transport was assessed using radio-labeled substrates and rapid filtration techniques. System A activity in MVM was increased (65-80%, P < 0.05) in all groups with diabetes independent of fetal overgrowth. However, MVM system A activity was unaffected in placentas of normal pregnancies with LGA fetuses. MVM leucine transport was increased in the GDM/LGA group. In BMs, amino acid transport was unaffected by diabetes. In conclusion, diabetes in pregnancy is associated with an increased system A activity in MVM, and MVM leucine transport is increased in the GDM/LGA group. We suggest that these changes result in an increased uptake of neutral amino acids across MVM, which may be used in placental metabolism or be delivered to the fetus. The increased MVM leucine uptake in the GDM/LGA group may contribute to accelerated fetal growth in these patients.