Aims/hypothesis: Prenatal glucocorticoid exposure causes lifelong hyperglycaemia in rat offspring, associated with permanently increased hepatic phosphoenolpyruvate carboxykinase 2 (PCK2), the rate-controlling enzyme of gluconeogenesis. To elucidate the mechanisms underlying the 'programming' of PCK2, this study examined the effect of prenatal dexamethasone treatment on expression of transcription factors that regulate Pck2. Materials and Methods: Real-time RT-PCR and in situ hybridisation were used to measure and localise hepatic mRNA transcribed from the genes for PCK2, hepatocyte nuclear factor 4, alpha (HNF4A), transcription factor 1 (TCF1), CCAAT/enhancer binding protein, alpha (CEBPA), CEBPB, the glucocorticoid receptor (NR3C1) and peroxisome proliferative activated receptor, gamma, coactivator 1 alpha (PPARGC1A) in foetal and adult offspring of dams treated with dexamethasone or vehicle during the last week of gestation. Results: Prenatal dexamethasone exposure significantly elevated Hnf4a mRNA expression in foetal and adult liver. This resulted from increased expression of isoforms derived from the 'adult' (P1) Hnf4a promoter. In contrast, isoforms from the 'foetal' (P2) promoter were markedly suppressed by dexamethasone. Like Pck2, the increase in hepatic Hnf4a mRNA occurred exclusively in the periportal zone. Foetal Tcf1 expression was also increased by dexamethasone treatment, but this did not persist into adulthood. Prenatal dexamethasone did not affect the amounts of foetal and/or adult Cebpa, Cebpb, Nr3c1 or Ppargc1a mRNA. Conclusions/interpretation: Prenatal dexamethasone exposure caused a permanent increase in hepatic Hnf4a mRNA. This increase, which was associated with a premature switch from foetal to adult promoter predominance, was congruent with changes in Pck2 expression. These data suggest that HNF4A might mediate Pck2 overexpression and subsequent hyperglycaemia.

Background Metformin has been shown to reduce complications and mortality from Type 2 diabetes mellitus, and is increasingly used to treat this condition. This agent is, however, associated with a rare but serious risk of lactic acidosis.Case report We present cases of 1.0 patients with Type 2 diabetes mellitus who developed acute renal failure and severe lactic acidosis. Despite the severity of their illness, all patients but one survived.Conclusions The increasing prevalence of Type 2 diabetes and its treatment with metformin might result in more cases of lactic acidosis. However our case report demonstrates that early and aggressive treatment with haemofiltration can improve outcomes even in the presence of severe acidosis.

The effects of thyroid dysfunction are thought to be reversible on restoration of euthyroidism, but postmortem and epidemiologic data suggest that subclinical or treated thyroid disease is associated with increased vascular risk. In order to determine the extent of this risk, and to explore whether the nature and/or treatment of thyroid disease are critical in this relationship, we used medical record linkage to match patients with treated thyroid disease of various etiologies with routinely collected national inpatient and daycase hospital discharge records and death records, and assessed the number of hospitalizations from cardiovascular or cerebrovascular disease or death in patients with thyroid disease and control patients. Patients treated for Graves' disease had more hospitalizations from cardiovascular disease than controls (relative risk, 1.42; 95% confidence interval, 1.20 to 1.67; p < 0.001). Toxic multinodular goiter was also associated with significantly higher rates of cardiovascular disease (relative risk, 1.50; 95% confidence interval, 1.11 to 2.02; p = 0.008). Patients with Hashimoto's thyroiditis aged over 50 years had a threefold increase in cardiovascular admissions compared to controls (23.5% and 6.5%, respectively; 95% confidence interval for difference, 6.0% to 27.9%; p = 0.003). Thus, different forms of thyroid disease were associated with increased long-term vascular risk despite restoration of euthyroidism. The mechanisms that mediate this risk are unclear but may not involve thyroid hormone abnormality.

Numerous studies in humans and experimental models have shown that alterations in calcium homeostasis are associated with an increased risk of cardiovascular complication. In particular, changes in systemic calcium metabolism are thought to play an important role in the regulation of blood pressure. One hypothesis for this link implicates parathyroid hormone (PTH). Serum calcium level is tightly regulated by PTH in a classic negative-feedback system. A small decrease in serum calcium stimulates an abrupt increase in PTH secretion, which leads to calcium mobilization from bone, increased renal tubular calcium reabsorption and increased renal hydroxylation of 25-hydroxyvitamin D to the biologically more active 1,25-dihydroxyvitamin D (which enhances calcium absorption from the intestine). Factors that tend to reduce the serum calcium levels (i.e. vitamin D deficiency) induce secondary hyperparathyroidism. In primary hyperparathyroidism, there is an autonomous increase in PTH secretion resulting in hypercalcaemia. Several studies have reported a positive correlation between serum PTH levels and hypertension [1]. This relationship has been demonstrated in patients with primary hyperparathyroidism as well as in those with secondary hyperparathyroidism [1]. Moreover, some studies have shown that patients with essential hypertension have a higher serum concentration of PTH than normotensive individuals. These data have led to the speculation that PTH may be involved in the pathogenesis of hypertension. In this issue of the journal, Jorde et al. [2] provide further evidence for an association between serum PTH levels and hypertension. In a prospective study involving 1784 patients over a 7-year period, the authors observed that the serum PTH levels at baseline (or the change in PTH levels over the study period) were a positive predictor of a change in systolic blood pressure over the study period in men. This association was not significant in women. The reasons for this apparent sexual diamorphism in the relationship between PTH levels and change blood pressure are unclear, although, in a previous report on this population, the authors found that PTH was a predictor of systolic and diastolic blood pressure in females [3]. Such a discrepancy may relate to differences in statistical power between the two studies. The current study has several other limitations, and these are freely acknowledged by the authors. In particular, the baseline samples for PTH estimation had been stored for a number of years before analysis, and may have been subjected to degradation, thus influencing the results. Despite the compelling evidence linking PTH with hypertension, the important question that remains unanswered is whether this relationship is causal or not. Several studies have demonstrated that PTH has vasoactive properties. For example, an acute fall in circulating PTH induced by calcium infusion increases systolic blood pressure in normal individuals, but not in thyroparathyroidectomized subjects [4]. Conversely, acute administration of PTH has been shown to cause vasodilation and blood pressure reduction. In sharp contrast to the acute effects, chronic PTH infusion results in persistent hypercalcaemia and hypertension in normal subjects [5]. Furthermore, patients with primary hyperparathyroidism have enhanced responsiveness to pressor agents, such as angiotensin II or norepinephrine [6], suggesting that PTH may provide a ‘permissive’ effect on blood pressure control. PTH has also been shown to increase renin secretion [7]. Additionally, PTH may cause hypertension by its direct effects on arteries and myocytes to promote arterial stiffness and left ventricular hypertrophy, respectively [8]. These data suggest a mechanistic coupling of PTH to hypertension. However, this relationship has remained controversial mainly because, unlike in most causes of secondary hypertension, there is no evidence that correction of PTH (and hypercalcaemia) with parathyroidectomy in patients with primary hyperparathyroidism improves blood pressure [9,10]. Similarly, although normalization of PTH after parathyroidectomy for primary hyperparathyroidism decreases left ventricular hypertrophy, this does not lower blood pressure [8,11]. The nature of the association between essential hypertension and PTH has also been questioned. Several studies have noted disturbances of calcium metabolism in patients with essential hypertension. These include increased urinary calcium excretion, a tendency for a low serum ionized calcium level, a raised PTH level and an increase in 1,25-dihydroxyvitamin D levels [12]. Essential hypertension is also associated with renal stones and osteoporosis [12]. Whether the alterations in calcium metabolism are primary or merely secondary to the elevated blood pressure remains unclear. There is evidence that hypertension increases urinary calcium excretion, and that this primary renal calcium leak results in a transient fall in serum ionized calcium, subsequently causing a compensatory rise in PTH [13]. In support of this hypothesis, similar alterations in calcium homeostasis have been observed in animal models of hypertension, such as in spontaneously hypertensive rats (SHR) [14] and mineralocorticoid-salt (DOCA-salt)-hypertensive rats [15]. Under these conditions, elevated PTH levels would be the consequence of hypertension, rather than the mediator of hypertension. Indeed, treating hypertension with diuretics or β-blockers has been shown to reverse changes in calcium and PTH levels [16]. On the other hand, dietary calcium supplementation (which lowers PTH levels) has also been shown to lower blood pressure in patients with essential hypertension and in animal models of hypertension, including SHR and DOCA-salt hypertension. This would support the notion that derangements in calcium metabolism may, at least in part, play a role in the development of hypertension. Clearly, other components of the calcium metabolic pathway, notably serum concentrations of ionized calcium and 1,25-dihydroxyvitamin D levels, rather than PTH per se, may also be important in the relationship between calcium homeostasis and the regulation of blood pressure. Thus, if such a mechanistic link exists, it will be difficult to differentiate indirect markers from actual mediator(s) of this relationship. The presentation of primary hyperparathyroidism has changed from a classical multisystem disease, characterized by severe hypercalcemia with significant bone, renal and neurological manifestations, to a disorder with mild hypercalcaemia in largely asymptomatic patients. These have resulted in a revision of the management guidelines, such that most asymptomatic patients with primary hyperparathyroidism are usually followed without parathyroidectomy [17]. With the increasing evidence implicating PTH in the pathogenesis of hypertension and cardiovascular risk, further studies will be required to critically examine this relationship, as well as to evaluate the long-term cardiovascular outcome of parathyroidectomy in asymptomatic patients with primary hyperparathyroidism, which might necessitate a reappraisal of current management strategies.

Aim: To ascertain the predictive values of thyroid autoantibodies and thyrotropin (TSH) levels for subsequent thyroid dysfunction in patients with diabetes. Methods: Review of records of 467 patients who had attended diabetes clinics for a mean of 6.1 years. Baseline autoantibody and TSH results and thyroid status at annual review were determined. Results: Thyroid disorders were known in 29 patients (6.2%), and newly identified in 32 (6.9%), at presentation. Of 406 patients with normal baseline thyroid status, 24 (5.9%) developed thyroid dysfunction during 6.1 years of mean follow-up. Higher baseline TSH concentration was associated with subsequent hypothyroidism; a threshold of 1.53 mU/L, approximately defining the top quartile, provided 75% sensitivity and specificity. Both TSH greater than 1.53 mU/L and positive autoantibody status predicted thyroid dysfunction, but only TSH was significant in multivariable analysis (odds ratio, 7.74, p < 0.001). No overt thyroid dysfunction developed in 293 patients with baseline TSH levels less than 1.53 mU/l. Conclusions: Baseline TSH level may be a better predictor of thyroid dysfunction than thyroid autoantibodies in people with diabetes. Patients with TSH levels below the top quartile have a risk of thyroid dysfunction similar to the general population. It may be appropriate to stop annual thyroid screening in this group, although confirmation is required.

OBJECTIVE: Glucocorticoids may contribute to the association between retarded growth in utero and insulin resistance in adulthood. Administration of dexamethasone (dex) to pregnant rats results in low birth weight offspring, which develop glucose intolerance, hyperinsulinaemia and hypercorticosteronaemia. This may be explained by tIssue-specific differences in expression of glucocorticoid receptors (GR) in adult offspring: GR is increased in visceral fat and liver, and decreased in hippocampus and soleus muscle. However, cause and effect between altered GR expression, hypercorticosteronaemia, and hyperinsulinaemia remains to be established. DESIGN AND METHODS: Rats were treated with dex (100 microg/kg per day) or saline during the third week of pregnancy. In 5-8-Month-old male offspring, GR expression in insulin target tIssues was quantified by RNase protection assay in rats that were adrenalectomised (ADX group), sham operated (SHAM group), or adrenalectomised with supra-physiological corticosterone replacement (CORT group) (n=7-8 per group), and in rats treated orally with vehicle, metformin (43 mg/kg per day) or rosiglitazone (1 mg/kg per day), after 3 weeks. RESULTS: Manipulation of corticosterone concentration did not affect GR mRNA in skeletal muscle or adipose. In liver, sham-operated animals showed lower GR mRNA, but there was no difference between adrenalectomised and hypercorticosteronaemic animals (SHAM 0.11+/-0.01 ratio to beta-actin, vs ADX 0.22+/-0.02, CORT 0.23+/-0.02, (values expressed as means+/-s.e.m.), P<0.001). Rosiglitazone reduced GR mRNA by approximately 30% in liver of dex- and saline-treated offspring (P<0.05), but had no effect on GR in adipose and skeletal muscle. Metformin abolished the 38% up-regulation of liver GR mRNA induced by antenatal dex and also reduced GR mRNA preferentially in muscle of dex-treated animals (0.14+/-0.01 vs 0.10+/-0.01; P=0.03). CONCLUSIONS: We conclude that neither hypercorticosteronaemia nor hyperinsulinaemia are sufficient to cause the changes in GR expression in dex-programmed rats, implying that these changes may be primary in determining the programmed insulin resistant phenotype. Normalisation of GR expression by metformin may be important in the mode of action of this anti-diabetic agent and may be especially useful to reverse-programmed up-regulation of GR.

In a previous study, we showed that exposure of rats to dexamethasone (Dex) selectively in late pregnancy produces permanent induction of hepatic phosphoenolpyruvate carboxykinase (PEPCK) expression and hyperglycaemia in the adult offspring. The mechanisms by which glucocorticoids cause this programming are unclear but may involve direct actions on the fetus/neonate, or glucocorticoids may act indirectly by affecting maternal postnatal nursing behaviour. Using a cross-fostering paradigm, the present data demonstrate that switching the offspring at birth from Dex-treated dams to control dams does not prevent induction of PEPCK or hyperglycaemia. Similarly, offspring born to control dams but reared by Dex-treated dams from birth maintain normal glycaemic control. During the neonatal period, injection of saline per se was sufficient to cause exaggeration in adult offspring responses to an oral glucose load, with no additional effect from Dex. However, postnatal treatment with either saline or Dex did not alter hepatic PEPCK activity. Prenatal Dex permanently raised basal plasma corticosterone levels, but under stress conditions there were no differences in circulating corticosterone levels. Likewise, Dex-exposed rats had similar plasma catecholamine concentrations to control animals. These findings show that glucocorticoids programme hyperglycaemia through mechanisms that operate on the fetus or directly on the neonate, rather than via effects that alter maternal postnatal behaviour during the suckling period. The hyperglycaemic response does not appear to result from abnormal sympathoadrenal activity or hypothalamic-pituitary-adrenal response during stress.

In vitro, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD-1) catalyses the interconversion of active corticosterone and inert 11-dehydrocorticosterone. 11beta-HSD-1 is highly expressed in liver, where the reaction direction is 11beta-reduction, thus potentially increasing intrahepatic active glucocorticoid levels. Inhibition of 11beta-HSD-1 increases insulin sensitivity in humans in vivo suggesting that hepatic 11beta-HSD-1 plays a role in the maintenance or control of key glucocorticoid-regulated metabolic functions. We have selectively repressed hepatic 11beta-HSD-1 in rats by oestradiol administration for 42 days. This nearly completely repressed hepatic 11beta-HSD-1 mRNA expression and enzyme activity and reduced expression of hepatic glucocorticoid-inducible genes including phosphoenolpyruvate carboxykinase (PEPCK), the rate-limiting step in gluconeogenesis. Similar effects were seen after 3 weeks of oestradiol treatment. To examine whether this was due to any direct effect of oestradiol upon PEPCK, the experiment was repeated in adrenalectomised rats+/-glucocorticoid replacement. In adrenalectomised rats, oestradiol did not attenuate hepatic PEPCK, whilst glucocorticoid replacement restored this action. Oestradiol did not alter hepatic metabolism of corticosterone by pathways other than 11beta-HSD-1. These data suggest 11beta-HSD-1 plays an important role in maintaining expression of key glucocorticoid-regulated hepatic transcripts. Enzyme inhibition may provide a useful therapeutic target for manipulating glucose homeostasis.

There is increasing epidemiological evidence in humans which associates low birth weight with later cardiovascular and metabolic disorders including hypertension, insulin resistance, hyperlipidaemia and death from ischaemic heart disease. The molecular mechanisms underlying this link are unknown but fetal glucocorticoid exposure may play a role. In adult mammals, glucocorticoid hormones are involved in control of several physiological processes that maintain homeostasis including coordination of responses to stress. During development, glucocorticoids have important regulatory functions to prepare the organism for metabolic adaptations necessary for extrauterine life. Fetal glucocorticoid load is, in part, regulated by placental and fetal 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD2) which catalyses a rapid breakdown of maternal and fetal glucocorticoids into inert products. Supraphysiological doses of glucocorticoids retard fetal growth, and human intrauterine growth retardation is associated with elevated cortisol levels. Recent studies have shown that exposing rats to excessive glucocorticoids in utero reduces birth weight and causes permanent hypertension and hyperglycaemia in the adult offspring. These observations show that glucocorticoids could be the link between low birth weight and later disease. Understanding of the molecular details involved in prenatal glucocorticoid action may provide novel insights into the pathogenesis of common cardiovascular and metabolic disorders.

Low birth weight in humans is predictive of insulin resistance and diabetes in adult life. The molecular mechanisms underlying this link are unknown but fetal exposure to excess glucocorticoids has been implicated. The fetus is normally protected from the higher maternal levels of glucocorticoids by feto-placental 11beta-hydroxysteroid dehydrogenase type-2 (11beta-HSD2) which inactivates glucocorticoids. We have shown previously that inhibiting 11beta-HSD2 throughout pregnancy in rats reduces birth weight and causes hyperglycemia in the adult offspring. We now show that dexamethasone (a poor substrate for 11beta-HSD2) administered to pregnant rats selectively in the last week of pregnancy reduces birth weight by 10% (P < 0.05), and produces adult fasting hyperglycemia (treated 5.3+/-0.3; control 4.3+/-0.2 mmol/ liter, P = 0.04), reactive hyperglycemia (treated 8.7+/-0.4; control 7.5+/-0.2 mmol/liter, P = 0.03), and hyperinsulinemia (treated 6.1+/-0.4; control 3.8+/-0.5 ng/ml, P = 0.01) on oral glucose loading. In the adult offspring of rats exposed to dexamethasone in late pregnancy, hepatic expression of glucocorticoid receptor (GR) mRNA and phosphoenolpyruvate carboxykinase (PEPCK) mRNA (and activity) are increased by 25% (P = 0.01) and 60% (P < 0.01), respectively, while other liver enzymes (glucose-6-phosphatase, glucokinase, and 11beta-hydroxysteroid dehydrogenase type-1) are unaltered. In contrast dexamethasone, when given in the first or second week of gestation, has no effect on offspring insulin/glucose responses or hepatic PEPCK and GR expression. The increased hepatic GR expression may be crucial, since rats exposed to dexamethasone in utero showed potentiated glucose responses to exogenous corticosterone. These observations suggest that excessive glucocorticoid exposure late in pregnancy predisposes the offspring to glucose intolerance in adulthood. Programmed hepatic PEPCK overexpression, perhaps mediated by increased GR, may promote this process by increasing gluconeogenesis.