Early life nutrition and the opportunity to influence long-term health: an Australasian perspective.

There are now significant data to support the hypothesis that early life nutrition in the fetus, infant and young child can have profound effects on long-term health. This review considers some of this evidence with specific reference to the current burden of disease in Australia and New Zealand. As the findings of further research become available, recommendations on optimizing early life nutrition should be formulated and made widely available as part of the preventative health policy agenda in both Australia and New Zealand.

Palliative Surgery for Pseudomyxoma Peritonei.

INTRODUCTION: Pseudomyxoma peritonei is a rare disease causing peritoneal carcinomatosis. In patients with extensive carcinomatosis, curative treatment is unachievable. Palliative debulking therapy is the only treatment in relieving symptoms. We report our results from palliative debulking surgery at a national pseudomyxoma peritonei center in Denmark. METHODS: From January 2007 to October 2012, we performed 27 palliative operations for pseudomyxoma peritonei with debulking at our institution. All patients were evaluated and found eligible for palliative treatment only. Patients were prospectively registered, while perioperative data were collected retrospectively from patient records. RESULTS: The majority of patients (n = 25) received an omentectomy (93%) as the primary procedure. In total, 17 (63%) received additional surgery. Median operative time was 88 min (range: 33-160 min). Median stay at the recovery ward was 6 h (2-288 h). Median hospital stay was 8 days (4-105 days). In all, 23 (85%) patients had no in-hospital complications, whereas 4 patients experienced complications (15%). Two of the complications were mild (Clavien-Dindo grade II), and two experienced severe complications (grade III and IV). Thirty-day mortality was 0%. Median survival was 3.0 years (0.2-6.2 years). CONCLUSION: Palliative debulking is a safe procedure with an acceptable morbidity and mortality offering immediate disease control.

Primary Aldosteronism: New Answers, New Questions.

There have been 2, and possibly 3, major questions for primary aldosteronism (PA) answered at least in principle over the past 5 years. The first is that of somatic mutations underlying the majority of aldosterone producing adenomas. The second is the extension of our knowledge of the genetics of familial hypertension, and the third the role of renal intercalated cells in sodium homeostasis. New questions for the next 5 years include a single accepted confirmatory/exclusion test; standardisation of assays and cut-offs; alternatives to universal adrenal venous sampling; reclassification of 'low renin hypertension'; recognition of the extent of 'occult' PA; inclusion of low-dose mineralocorticoid receptor antagonist in first-line therapy for hypertension; and finally, possible resolution of the aldosterone/inappropriate sodium status enigma at the heart of the cardiovascular damage in PA.

The giraffe kidney tolerates high arterial blood pressure by high renal interstitial pressure and low glomerular filtration rate.

BACKGROUND: The tallest animal on earth, the giraffe (Giraffa camelopardalis) is endowed with a mean arterial blood pressure (MAP) twice that of other mammals. The kidneys reside at heart level and show no sign of hypertension-related damage. We hypothesized that a species-specific evolutionary adaption in the giraffe kidney allows normal for size renal haemodynamics and glomerular filtration rate (GFR) despite a MAP double that of other mammals. METHODS: Fourteen anaesthetized giraffes were instrumented with vascular and bladder catheters to measure glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). Renal interstitial hydrostatic pressure (RIHP) was assessed by inserting a needle into the medullary parenchyma. Doppler ultrasound measurements provided renal artery resistive index (RI). Hormone concentrations as well as biomechanical, structural and histological characteristics of vascular and renal tissues were determined. RESULTS: GFR averaged 342 ± 99 mL min(-1) and ERPF 1252 ± 305 mL min(-1) . RIHP varied between 45 and 140 mmHg. Renal pelvic pressure was 39 ± 2 mmHg and renal venous pressure 32 ± 4 mmHg. A valve-like structure at the junction of the renal and vena cava generated a pressure drop of 12 ± 2 mmHg. RI was 0.27. The renal capsule was durable with a calculated burst pressure of 600 mmHg. Plasma renin and AngII were 2.6 ± 0.5 mIU L(-1) and 9.1 ± 1.5 pg mL(-1) respectively. CONCLUSION: In giraffes, GFR, ERPF and RI appear much lower than expected based on body mass. A strong renal capsule supports a RIHP, which is >10-fold that of other mammals effectively reducing the net filtration pressure and protecting against the high MAP.

Primary aldosteronism: are we missing the wood for the trees?

The prevalence of primary aldosteronism (PA) is around 10% of hypertensives, with markedly increased risk of cardiovascular damage compared with age-, sex- and BP-matched essential hypertension (EH). Currently, if hypertension is present in 20% of the population, PA will account for 2%; of these PA patients only 1% are ever screened, let alone diagnosed and treated, and the remaining 99% suboptimally treated, if at all. Mineralocorticoid receptor (MR) antagonists are effective in lowering BP, uniquely vasoprotective and safe when titrated to effect in EH. In resistant hypertension (BP elevated despite 3 or more conventional agents, including a diuretic), which constitutes 20-30% of EH, addition of a low dose MR antagonist reproducibly produces BP lowering of 20-30 mm Hg. Two thirds of PA is unilateral, and normally treated by MR antagonists; in unilateral PA surgery is recommended, but there are also studies reporting MR antagonist therapy to be noninferior over the longer term. There thus seems to be a very strong case for including a low dose MR antagonist in first-line therapy for new hypertension, given its utility and safety across EH, its particular efficacy in resistant hypertension, and its specific benefits for the 99% of subjects with occult PA. We do not have the resources to diagnose PA, but we do have the wherewithal to treat it.

Influence of venous reservoir level on microbubbles in cardiopulmonary bypass.

Patients undergoing open-heart surgery may, post-operatively, suffer from neurological disorders due to microbubbles created during extracorporeal circulation. Venous air is not completely removed in open hard-shell venous reservoirs. We, therefore, investigated the relationship between venous reservoir blood level and the amount of microbubbles in different commercially available reservoirs for comparison and determination of safe level. An in vitro flow loop with a heart-lung machine was used to compare three different reservoirs (Maquet, Sorin and Medtronic) at different levels. Microbubbles were measured after the reservoir and after the arterial filter with a GAMPT BCC200 detector. Microbubble count and volume were significantly higher with decreasing reservoir level (p = 0.014), but not as much as earlier studies have shown. Reducing the level from 1000 ml to 250 ml resulted in a 12.4% increase in bubble volume after the reservoir and 40.2% after the arterial filter. There was an almost linear trend towards more bubble volume with decreasing reservoir level (R2 = 0.98-0.83). There was a significant difference in microbubbles between the 3 tested reservoirs, up to 32.6%, p < 0.001 measured after the reservoir. Bubble volume from the Sorin reservoir was markedly lower after the arterial filter than from the Medtronic and Maquet reservoirs (up to 60 times p < 0.001). A lower reservoir level results in a moderate rise in microbubbles passing the reservoir. The minimum levels recommended by the manufacturers are safe. There was a significant difference in bubbles between the different reservoirs, especially after the arterial filter.

Distinguishing the antihypertensive and electrolyte effects of eplerenone.

In two clinical trials on the antihypertensive effects of the mineralocorticoid receptor antagonist eplerenone 397 essential hypertensives were dose titrated (50, 100, and 200 mg/d) over successive 4-wk periods until they reached target blood pressure levels. Of the total, 44% reached target on 50 mg/d, 17% on 100 mg/d, and 19% on 200 mg/d, with 20% failing to do so despite stepwise dose increases. At each dose level, those who reached target (responders) were compared with those who did not (nonresponders), with three major findings. First, at each dose level, the blood pressure fall in responders (systolic, 16-20 mm Hg; diastolic, approximately 15 mm Hg) was markedly more than mean values in nonresponders (systolic, 2-5 mm Hg; diastolic, 1-3 mm Hg). Second, sensitivity to eplerenone varied widely across the population studied in terms of blood pressure reduction. Third, there was no difference in plasma [K+] levels between responders and nonresponders at any dose level. We interpret these data as evidence for the major antihypertensive effect of eplerenone being via mechanisms other than those involving epithelial electrolyte and fluid transport. The modest (< or =0.2 mEq/liter at 200 mg/d) mean elevation in plasma [K+] suggests that titration to effect rather than forced titration may minimize the risk of hyperkalemia, even where relatively high (100-200 mg/d) doses of the specific mineralocorticoid receptor antagonist eplerenone may ultimately be required.

Cardiac steroidogenesis in the normal and failing heart.

The present study explores the possibility of local de novo aldosterone production in normal and failing hearts (human and mouse) and the regulation of such putative cardiac steroidogenesis. Total RNA was isolated from human tissue from failing hearts taken at the time of cardiac transplantation, from normal hearts obtained at autopsy, and from normal and pressure-overloaded mouse hearts. Vascular smooth muscle cells from human artery and vein were also analyzed. RNA was reverse transcribed and probed with specific primers for side-chain cleavage enzyme (CYP11A), 3beta-hydroxysteroid dehydrogenase, aldosterone synthase (CYP11B2), 11beta-hydroxylase (CYP11B1), steroidogenic factor-1, and steroid acute regulatory protein. CYP11A, 3beta-hydroxysteroid dehydrogenase-2, and steroid acute regulatory protein were expressed at modest levels in all tissues examined in both mouse and human. In failing human heart, CYP11B1 and CYP11B2 were detected in some samples, in contrast with normal hearts, which expressed neither; in the mouse heart steroidogenic factor-1 was detected, but neither CYP11B1 nor CYP11B2 was found. Steroidogenic factor-1 was detected in no human heart sample tested after 40 cycles of PCR. Although the expression of some steroidogenic genes can be detected in the heart, the likelihood of physiologically relevant levels of aldosterone production by the normal heart is very low. The exact cellular location of steroid synthesis in the failing human heart remains to be established.

Experimental cardiac fibrosis: differential time course of responses to mineralocorticoid-salt administration.

The rapid (1-4 h) responses of epithelial target tissues to mineralocorticoids contrast with the days/weeks apparently required for responses in the cardiovascular system. The present study explores the time course and pattern of early events leading to cardiac fibrosis in the mineralocorticoid-salt rat model. Uninephrectomized rats were given deoxycorticosterone (20 mg, sc, weekly) plus 0.9% NaCl/0.3% KCl to drink and were killed at 2, 4, 8, 16, and 32 d. Type III collagen increased progressively from d 2, and blood pressure from d 4, with 4 and 8 d rats showing marked perivascular inflammatory cell infiltration. Apoptosis was also noted in perivascular areas at 4 and 8 d and in scar areas at 8, 16, and 32 d. Elevation of mineralocorticoid hormone levels inappropriate for salt status thus provokes a series of changes in cardiac vessels and myocytes leading to increased collagen deposition. When mineralocorticoid levels are elevated acutely by bolus injection, changes are discernible after 2 d, in contrast with previous infusion studies in which 3-4 wk were required for measurable changes.

Eplerenone suppresses constrictive remodeling and collagen accumulation after angioplasty in porcine coronary arteries.

BACKGROUND: Coronary artery angioplasty triggers healing that causes constrictive remodeling. Because collagen accumulation correlates with constrictive remodeling and aldosterone has been implicated in collagen accumulation, we examined how aldosterone and the mineralocorticoid receptor antagonists spironolactone and eplerenone affect remodeling and collagen in porcine coronary and iliac arteries after angioplasty. METHODS AND RESULTS: Twenty-four pigs were allocated into 4 treatment groups: oral eplerenone (100 mg/d), oral spironolactone (200 mg/d), subcutaneous aldosterone (400 microgram/d), or no treatment. Twenty-eight days after angioplasty of the coronary arteries, eplerenone increased total vessel area by 30% (P<0.05) and luminal area by nearly 60% (P<0.05) compared with the no-treatment group, without affecting neointima size. These effects were accompanied by a 65% reduction in neointimal and medial collagen density (both P<0.05). Spironolactone was less effective, and aldosterone tended to exert opposite effects on coronary artery structure after angioplasty. These effects were not observed in angioplastied iliac arteries. CONCLUSIONS: Eplerenone attenuates constrictive remodeling after coronary artery angioplasty by mechanisms involving reduction in collagen accumulation, which thus appears to be an important contributor to constrictive remodeling of angioplastied coronary arteries.

The serum- and glucocorticoid-induced kinase is a physiological mediator of aldosterone action.

Aldosterone plays a major role in regulating sodium and potassium flux in epithelial tissues such as kidney and colon. Recent evidence suggests that serum- and glucocorticoid-regulated kinase (SGK) is induced by aldosterone and acts as a key mediator of aldosterone action in epithelial tissues. Induction of SGK messenger RNA (mRNA) has previously been shown within 30 min of addition of supraphysiological doses of aldosterone to Xenopus A6 cells and within 4 h in rat kidney in vivo. In this study we determined the time course of SGK induction, at doses of aldosterone in the physiological range, in rat kidney and colon, using Northern and Western blot analyses and in situ hybridization and determined concurrent changes in urinary sodium and potassium excretion by Kagawa bioassay. On Northern blot analysis, SGK mRNA levels were significantly elevated in both kidney and colon 60 min after the injection of aldosterone. SGK protein in late distal colon was significantly elevated 2 and 4 h after aldosterone treatment. In situ hybridization showed SGK mRNA to be induced in renal collecting ducts and distal tubular elements in both cortex and medulla by doses of aldosterone of 0.1 microg/100 g BW or more within 30 min of steroid treatment. Significant changes in urinary composition were similarly seen with an aldosterone dose of 0.1 microg/100 g BW from 90 min after aldosterone injection. The early onset of SGK induction in kidney and colon and the correlation with urinary changes in terms of both time course and dose response suggest that SGK plays an important role in mediating the effects of aldosterone on sodium homeostasis in vivo.

GRKO mice express an aberrant dexamethasone-binding glucocorticoid receptor, but are profoundly glucocorticoid resistant.

The introduction of a targeted insertion mutation into exon 2 of the gene coding for the glucocorticoid receptor (GR) enabled production of glucocorticoid receptor knock-out (GRKO) mice. GRKO mice on a C57BL/6/129sv mixed genetic background show a variable phenotype, with 90% of -/- mice dying at birth with respiratory insufficiency but 10% of mutant mice surviving to maturity. To investigate the possibility of residual GR expression in surviving GRKO mice we have measured binding of the synthetic glucocorticoid dexamethasone in tissue extracts from adrenalectomized mice. High affinity binding of dexamethasone in protein extracts of liver, kidney, lung and brain from adult GRKO mice is found at levels 30-60% those in wild-type mice, with heterozygotes (+/-) having intermediate levels. PCR and ribonuclease protection analysis showed comparable levels of GR mRNA on the 3' side of the gene-targeted insertional mutation in exon 2 of the GR gene, with almost no GR mRNA detected from exons 1 and 2 on the 5' side of the gene-targeted insertional mutation. Western blot analysis using a C-terminal specific GR antibody detects a 39 kDa GR fragment in extracts from adult GRKO mice. Despite the evidence for expression of a ligand-binding domain fragment of the glucocorticoid receptor these mice are profoundly glucocorticoid resistant, with elevated levels of plasma ACTH and corticosterone. Thymocytes from adult and fetal GRKO mice are resistant to dexamethasone-induced apoptosis and cultured fetal hepatocytes from GRKO mice are completely refractory to glucocorticoid induction of the gluconeogenic enzyme glucose-6-phosphatase. Thus although the surviving adult homozygous GRKO mice express a dexamethasone-binding GR fragment, their classic target tissues remain profoundly glucocorticoid insensitive.

Non-genomic actions of aldosterone: role in hypertension.

There is universal acceptance of the existence of rapid, non-genomic effects of aldosterone, although their physiological relevance and potential importance in hypertension are not yet clear. What has emerged over the year under review is that at least some of such rapid non-genomic effects of aldosterone may be mediated by the activation of the classical intracellular mineralocorticoid receptor, rather than a putative membrane receptor. The post-receptor mechanisms of rapid aldosterone action appear variously to involve protein kinase C, calcium, cyclic adenosine 3', 5'-monophosphate and inositol 1, 4, 5-triphosphate, with downstream effects on a variety of ion pumps and channels.

Dynamin II regulates hormone secretion in neuroendocrine cells.

The dynamin family of GTP-binding proteins has been implicated as playing an important role in endocytosis. In Drosophila shibire, mutations of the single dynamin gene cause blockade of endocytosis and neurotransmitter release, manifest as temperature-sensitive neuromuscular paralysis. Mammals express three dynamin genes: the neural specific dynamin I, ubiquitous dynamin II, and predominantly testicular dynamin III. Mutations of dynamin I result in a blockade of synaptic vesicle recycling and receptor-mediated endocytosis. Here, we show that dynamin II plays a key role in controlling constitutive and regulated hormone secretion from mouse pituitary corticotrope (AtT20) cells. Dynamin II is preferentially localized to the Golgi apparatus where it interacts with G-protein betagamma subunit and regulates secretory vesicle release. The presence of dynamin II at the Golgi apparatus and its interaction with the betagamma subunit are mediated by the pleckstrin homology domain of the GTPase. Overexpression of the pleckstrin homology domain, or a dynamin II mutant lacking the C-terminal SH3-binding domain, induces translocation of endogenous dynamin II from the Golgi apparatus to the plasma membrane and transformation of dynamin II from activity in the secretory pathway to receptor-mediated endocytosis. Thus, dynamin II regulates secretory vesicle formation from the Golgi apparatus and hormone release from mammalian neuroendocrine cells.

Mineralocorticoids and cardiac fibrosis: the decade in review.

1. Over the past decade, aldosterone has been shown to have direct extra-epithelial actions and substantial (patho)physiological roles in the cardiovascular system in the context of inappropriate salt status. In experimental studies on uninephrectomized rats given 0.9% NaCl solution to drink, these include blood pressure elevation via activation of circumventricular mineralocorticoid receptors in the central nervous system and production of pressure-independent cardiac hypertrophy and fibrosis by a direct effect on the heart. 2. In the Randomized Aldactone Evaluation Study (RALES) trial, patients with severe congestive heart failure (CHF) were continued on their current therapy (angiotensin-converting enzyme inhibitor, diuretic etc.) and given either placebo or spironolactone at an average dose of 26 mg/day. Mineralocorticoid receptor inhibition was accompanied by a 30% improvement in mortality and 35% less hospitalization, striking confirmation of a pathophysiological role for aldosterone in CHF. 3. Although the current basic and clinical studies are conflicting, there is evidence both for aldosterone synthesis by the failing human heart and for substantial cardiac metabolism of aldosterone. The extent to which this potential paracrine source for aldosterone may be involved in cardiac hypertrophy and cardiac fibrosis remains to be established. 4. Belatedly, aldosterone-induced proteins (e.g. serum and glucocorticoid-regulated kinase (SGK)) have been identified in epithelial mineralocorticoid target tissue. Studies are currently in progress on the cellular and molecular mechanisms involved in the coronary vasculitis provoked early in the mineralocorticoid/salt model, which, in turn, appears to trigger the subsequent perivascular and interstitial fibrotic response.