Somatomedins and insulin in diabetic pregnancies: effects on fetal macrosomia in the human and rhesus monkey

The concentrations of the somatomedins (SMs) insulin-like growth factors I and II (SM-C/IGF-I and IGF-II) were measured by RIA in six normal and seven insulin-dependent diabetic pregnant women and their infants at delivery. SM-C/IGF-I and IGF-II levels in the two groups of women were similar. Maternal IGF-II concentrations correlated with maternal hemoglobin AIc levels (r = 0.68) and infant birth weight ratios (actual birth weight/expected 50th percentile sex-corrected birth weight for gestation age; r = 0.54). SMC/IGF-I and IGF-II levels in umbilical plasma in infants of diabetic mothers did not differ from those in control infants, but were lower than the corresponding maternal values. In contrast, umbilical plasma levels of C-peptide immunoreactivity were significantly elevated in the infants of diabetic mothers (2.25 +/- 1.85 (+/-SD) vs. 0.34 +/- 0.15 pmol/ml; P less than 0.01). The infant birth weight ratio was logarithmically correlated with the umbilical plasma C-peptide immunoreactivity (r = 0.78). SM levels were also measured by radioreceptor assay in five normal and five hyperinsulinemic rhesus monkey fetuses. When chronic hyperinsulinemia was produced by continuous SC infusion of insulin in the fetal rhesus monkey, the fetal birth weight ratio was also found to be logarithmically correlated with the fetal plasma insulin concentration (r = 0.81). The fetal SM peptide content was elevated only in the fetuses with plasma insulin levels greater than 3000 microU/ml. The fetal weight gains in response to hyperinsulinemia in the human and rhesus are similar. Since fetal SM levels in the humans and monkeys were not significantly different in the two groups, our data suggest that insulin plays the predominant role in stimulating human and subhuman primate excess fetal weight gain of the infant of the diabetic mother during the latter part of gestation.     

Epigenetic changes encompassing the IGF2/H19 locus associated with relaxation of IGF2 imprinting and silencing of H19 in Wilms tumor.

In most tissues IGF2 is expressed from the paternal allele while H19 is expressed from the maternal allele. We have previously shown that in some Wilms tumors the maternal IGF2 imprint is relaxed such that the gene is expressed biallelically. We have now investigated this subset of tumors further and found that biallelic expression of IGF2 was associated with undetectable or very low levels of H19 expression. The relaxation of IGF2 imprinting in Wilms tumors also involved a concomitant reversal in the patterns of DNA methylation of the maternally inherited IGF2 and H19 alleles. Furthermore, the only specific methylation changes that occurred in tumors with relaxation of IGF2 imprinting were solely restricted to the maternal IGF2 and H19 alleles. These data suggest that there has been an acquisition of a paternal epigenotype in these tumors as the result of a pathologic disruption in the normal imprinting of the IGF2 and H19 genes.     

Enhanced sensitivity to IGF-II signaling links loss of imprinting of IGF2 to increased cell proliferation and tumor risk

Loss of imprinting (LOI) of the insulin-like growth factor-II gene (IGF2), leading to abnormal activation of the normally silent maternal allele, is a common human epigenetic population variant associated with a 5-fold increased frequency of colorectal neoplasia. Here, we show first that LOI leads specifically to increased expression of proliferation-related genes in mouse intestinal crypts. Surprisingly, LOI(+) mice also have enhanced sensitivity to IGF-II signaling, not simply increased IGF-II levels, because in vivo blockade with NVP-AEW541, a specific inhibitor of the IGF-II signaling receptor, showed reduction of proliferation-related gene expression to levels half that seen in LOI(−) mice. Signal transduction assays in microfluidic chips confirmed this enhanced sensitivity with marked augmentation of Akt/PKB signaling in LOI(+) cells at low doses of IGF-II, which was reduced in the presence of the inhibitor to levels below those found in LOI(−) cells, and was associated with increased expression of the IGF1 and insulin receptor genes. We exploited this increased IGF-II sensitivity to develop an in vivo chemopreventive strategy using the azoxymethane (AOM) mutagenesis model. LOI(+) mice treated with AOM showed a 60% increase in premalignant aberrant crypt foci (ACF) formation over LOI(−) mice. In vivo IGF-II blockade with NVP-AEW541 abrogated this effect, reducing ACF to a level 30% lower even than found in exposed LOI(−) mice. Thus, LOI increases cancer risk in a counterintuitive way, by increasing the sensitivity of the IGF-II signaling pathway itself, providing a previously undescribed epigenetic chemoprevention strategy in which cells with LOI are “IGF-II addicted” and undergo reduced tumorigenesis in the colon upon IGF-II pathway blockade.     

Glycosylated hemoglobin as predictor of adverse fetal outcome in type 1 diabetic pregnancies

The study aimed to determine whether a consistent dose-response association can be demonstrated, after adjustment for maternal age and White classification, between glycosylated hemoglobin (HbA_1c) values before conception and in the first trimester of pregnancy of insulin-dependent diabetic mothers and adverse fetal outcome (abortions and major malformations). This is a historical follow-up study based on medical records in a geographically defined catchment area. The study comprised 60 pregnancies with HbA_1c determinations before pregnancy and 161 with HbA_1c in the first trimester in women with type 1 diabetes admitted between 1980 and 1992. Relative risk calculations indicated a highly significant and consistent correlation between HbA_1c values above 6.6% and adverse fetal outcome after adjustment for differences in maternal age and White classification. Our data support a clinically significant and consistent relationship between adverse fetal outcome and HbA_1c in the first trimester of pregnancy of type 1 mothers, without any indication of a cut-off level below which further improvement in HbA_1c was of minor importance. Received: 25 October 1996 / Accepted in revised form: 18 April 1997     

Pregnancy and murine thyroiditis: thyroglobulin immunization leads to fetal loss in specific allogeneic pregnancies

Thyroid autoantibodies are risk factors in human pregnancy. To investigate the influence of autoimmune thyroiditis on pregnancy, we have studied the impact of murine experimental autoimmune thyroiditis (EAT) on pregnancy outcome by using thyroglobulin (Tg) immunized CBA/J (H2(k)) female mice. When Tg immunized mice were mated with BALB/c (H2(d)) males, only 57% (47/83) of pregnant mice maintained their conceptions compared with >85% of other strain combinations (P < 0.05). We also found that MHC class II antigens were expressed on placental cells from Tg immunized pregnant mice but not in control normal pregnancies. Furthermore, the frequency and severity of thyroiditis, assessed by histological analyses, was also increased in Tg immunized mice mated with the BALB/c strain compared with syngeneic pregnancies (P < 0.05). In these pregnant mice mated with BALB/c, interleukin-4 secretion by mitogen-stimulated spleen cells was significantly suppressed and interferon-gamma secretion by mixed lymphocyte reactions with BALB/c cells was significantly increased. These data demonstrated enhanced Th1 cell proliferation and fetal loss in CBA/J X BALB/c pregnancies. We concluded, therefore, that pregnancy loss was increased in experimental autoimmune thyroiditis in a manner that was dependent on paternal antigens. These observations have broad implications for understanding the immunology of pregnancy.     

Atenolol and fetal growth in pregnancies complicated by hypertension.

Atenolol use may be associated with growth retardation when given in pregnancy, although the relationship to trimester of initiation, duration of treatment, and its use as monotherapy is still uncertain. To compare the obstetric and fetal outcome between women receiving atenolol (as monotherapy) and other antihypertensive drug monotherapies, and also to investigate the effect of duration of treatment on fetal growth, we performed a retrospective cohort study of 312 pregnancies in 223 women attending an Antenatal Hypertension Clinic. Atenolol (as monotherapy) was given in 78 pregnancies (25.0%), other types of antihypertensive drugs as monotherapy were given in 53 pregnancies (17.0%), and multiple drug combinations were given in 90 pregnancies (28.8%). In 91 pregnancies (29.2%) no antihypertensive drugs were given. Atenolol was found to be associated with lower birth weight and ponderal index values, with a trend toward a higher prevalence of preterm (<37 weeks) delivery and small-for-gestational-age babies when compared to other antihypertensive drugs as monotherapy, or to no treatment. The adverse effect of atenolol was more pronounced in women receiving the drug earlier in their pregnancy, and continuing the drug for a longer duration. In conclusion, atenolol should be avoided in the early stages of pregnancy and given with caution at the later stages, as it is associated with fetal growth retardation, which is related to duration of treatment.     

Prevalence of antiphospholipid antibodies in patients with fetal loss.

The prevalence of antiphospholipid and antinuclear antibodies in 102 patients with at least three unexplained miscarriages before a gestational age of 12 weeks, or at least one intrauterine fetal death after 12 weeks, was investigated and compared with the prevalence in 102 normal pregnant controls. Six patients had a history of thrombosis and six had 'lupus-like' disease. Twenty one patients had anticardiolipin antibodies compared with 10 controls. Serum samples of nine patients and one control contained antinuclear antibodies. The lupus anticoagulant was present in the plasma of five patients with anticardiolipin antibodies. The influence of patient selection on the results was illustrated by the finding that antiphospholipid antibodies and antinuclear antibodies were mainly detected in patients with lupus-like disease or a history of thrombosis. When these patients were excluded there was no significant difference in the prevalence of anticardiolipin and antinuclear antibodies between patients and controls. Therefore, in the absence of lupus-like disease or a history of thrombosis, screening for antiphospholipid antibodies in patients with adverse pregnancy outcomes seems not to be indicated.     

High amniotic fluid erythropoietin levels are associated with an increased frequency of fetal and neonatal morbidity in Type 1 diabetic pregnancies

Aims/hypothesis In this study we investigated whether chronic fetal hypoxia, as indicated by amniotic fluid erythropoietin levels, is associated with perinatal morbidity in Type 1 diabetic pregnancies.Methods A total of 331 women with Type 1 diabetes had at least one childbirth between 1995 and 2000. The amniotic fluid erythropoietin concentration was measured in 156 diabetic singleton pregnancies at a median time of 1 day before Caesarean section without labour contractions and in 19 healthy control subjects at Caesarean section.Results The median amniotic fluid erythropoietin level was 14.0 mU/ml (range 2.0–1975.0) in diabetic pregnancies and 6.3 mU/ml (range 1.7–13.7) in controls (p<0.0001). Of the 156 diabetic patients, 21 (13.5%) had amniotic fluid erythropoietin levels higher than 63.0 mU/ml. Amniotic fluid erythropoietin levels correlated negatively with umbilical artery pH (r=–0.49, p<0.0001) and pO₂ (r=–0.62, p<0.0001) at birth and neonatal lowest blood glucose level (r=–0.47, p<0.0001). Positive correlations were found between amniotic fluid erythropoietin levels and umbilical artery pCO₂ (r=0.49, p<0.0001) and last maternal HbA₁c (r=0.43, p<0.0001). Furthermore, a U-shaped correlation was demonstrated between amniotic fluid erythropoietin levels and birthweight z score (z score below –0.6 SD units: r=–0.63, p=0.0007; z score above +1.0 SD units: r=0.32, p=0.0014). Neonatal hypoglycaemia, hypertrophic cardiomyopathy and admission to the neonatal intensive care unit occurred significantly more often in cases with high amniotic fluid erythropoietin levels (>63.0 mU/ml) than in those with normal levels. Multivariate logistic regression analysis revealed that amniotic fluid erythropoietin was the only variable independently related to low umbilical artery pH (<7.21; p<0.0001) and neonatal hypoglycaemia (p=0.002). Low umbilical artery pO₂ (<15.0 mm Hg) was explained by amniotic fluid erythropoietin (p<0.0001) and birthweight z score (p=0.004).Conclusions/interpretation Antenatal high amniotic fluid erythropoietin levels can identify Type 1 diabetic pregnancies at increased risk of severe perinatal complications.     

Bone loss in diabetic patients with chronic kidney disease.

OBJECTIVE: We investigated whether loss of bone is detectable during follow-up of diabetic patients with chronic kidney disease (CKD). RESEARCH DESIGN AND METHODS: In 40 initially non-dialysed diabetic patients with CKD (isotopic glomerular filtration rate < 60 ml/min/1.73 m(2) or albumin excretion rate > 30 mg/24 h), body composition (DEXA scan) and glomerular filtration rate (GFR determined from (51)Cr-EDTA clearance) were measured at a 2-year interval, and compared by paired t-tests. RESULTS: The 40 patients, mainly with Type 2 diabetes (n = 28), were men (n = 28), aged 65 +/- 11 years, with diabetes duration 18 +/- 11 years. GFR was initially 38.0 (range 8-89) ml/min/1.73 m(2). CKD progressed during follow-up: eight started haemodialysis and GFR declined in the 32 others (P < 0.05 vs. initial). T-scores for total body (initial -0.61 +/- 1.11, final -1.11 +/- 1.40; P < 0.001) and femoral neck (initial -1.88 +/- 0.15, final -2.07 +/- 0.15; P < 0.05) declined. Ten patients were osteopaenic at baseline (no osteoporosis), whereas most were osteopaenic (n = 21, P < 0.05) and five were osteoporotic at final assessment. The 16 patients who became osteopaenic or osteoporotic during follow-up did not differ from the others for the type of diabetes, age, GFR, albumin excretion rate, HbA(1c), GFR reduction and the requirement for dialysis during follow-up. They were all men (P < 0.01 by chi-squared test), with reduced initial total body T-score (-1.20 +/- 0.82, others -0.32 +/- 1.13; P < 0.05) and a lower body mass index (24.6 +/- 4.3; others 27.7 +/- 4.3; P < 0.05). CONCLUSION: Bone loss, especially in the femoral neck, is progressive in diabetic patients with CKD.     

Acute onset of dermatomyositis presenting in pregnancy with rhabdomyolysis and fetal loss.

We report a case of acute onset of dermatomyositis with rhabdomyolysis and myoglobinuria, which presented in the 14th week of pregnancy and resulted in spontaneous abortion of the fetus. The diagnostic work up for an underlying disease was negative and the histologic examination confirmed the diagnosis of dermatomyositis, which subsequently improved with corticosteroids.     

A silencer element identified in Drosophila is required for imprinting of H19 reporter transgenes in mice

The H19 gene is subject to genomic imprinting because it is methylated and repressed after paternal inheritance and is unmethylated and expressed after maternal inheritance. We recently identified a 1.1-kb control element in the upstream region of the H19 gene that functions as a cis-acting silencer element in Drosophila. Here we investigate the function of this element in mice. We demonstrate that both H19-lacZ and H19-PLAP reporter transgenes can undergo imprinting with repression and hypermethylation after paternal transmission at many integration sites. However, transgenes that were deleted for the 1.1-kb silencer element showed loss of paternal repression, but they did not show marked changes in the paternal methylation of the remaining upstream region. This study demonstrates that the 1.1-kb control element identified in Drosophila is required to silence paternally transmitted H19 minitransgenes in mice.