Impact of Chronotherapy on 6-Mercaptopurine Metabolites in Inflammatory Bowel Disease: A Pilot Crossover Trial

INTRODUCTION

Chronotherapy is the timing of medication according to biological rhythms of the host to optimize drug efficacy and minimize toxicity. Efficacy and myelosuppression of azathioprine/6-mercaptopurine (AZA/6-MP) are correlated with the metabolite 6-thioguanine, while the metabolite 6-methylmercaptopurine correlates with hepatotoxicity.

METHODS

This was a single-center, 10-week prospective crossover trial involving 26 participants with inactive inflammatory bowel disease (IBD) on a stable dose and time of AZA or 6-MP therapy. Participants were switched to the opposite delivery time (morning or evening) for 10 weeks, and metabolite measurements were at both time points.

RESULTS

In the morning vs evening dosing, 6-thioguanine levels were 225.7 ± 155.1 vs 175.0 ± 106.9 ( P < 0.01), and 6-methylmercaptopurine levels were 825.1 ± 1,023.3 vs 2,395.3 ± 2,880.3 ( P < 0.01), with 69% (18 out of 26) of participants had better metabolite profiles in the morning. Participants with optimal dosing in the morning had an earlier chronotype by corrected midpoint of sleep.

DISCUSSION

In the first study on a potential role of chronotherapy in IBD, we found (i) morning dosing of AZA or 6-MP resulted in more optimal metabolite profiles and (ii) host chronotype could help identify one-third of patients who would benefit from evening dosing. Circadian regulation of metabolic enzymes of AZA/6-MP activity in the liver is the likely cause of these differences. This pilot study confirms the need to incorporate chronotherapy in future multicenter clinical trials on IBD disease.

The cysteinyl leukotriene 3 receptor regulates expansion of IL-25-producing airway brush cells leading to type 2 inflammation

Respiratory epithelial cells (EpCs) orchestrate airway mucosal inflammation in response to diverse environmental stimuli, but how distinct EpC programs are regulated remains poorly understood. Here, we report that inhalation of aeroallergens leads to expansion of airway brush cells (BrCs), specialized chemosensory EpCs and the dominant epithelial source of interleukin-25 (IL-25). BrC expansion was attenuated in mice lacking either LTC₄ synthase, the biosynthetic enzyme required for cysteinyl leukotriene (CysLT) generation, or the EpC receptor for leukotriene E₄ (LTE₄), CysLT₃R. LTE₄ inhalation was sufficient to elicit CysLT₃R-dependent BrC expansion in the murine airway through an IL-25-dependent but STAT6-independent signaling pathway. Last, blockade of IL-25 attenuated both aeroallergen and LTE₄-elicited CysLT₃R-dependent type 2 lung inflammation. These results demonstrate that CysLT₃R senses the endogenously generated lipid ligand LTE₄ and regulates airway BrC number and function.

COX-1 mediates IL-33-induced extracellular signal-regulated kinase activation in mast cells: Implications for aspirin sensitivity

BACKGROUND

Classical FcεRI-induced mast cell (MC) activation causes synthesis of arachidonic acid (AA)-derived eicosanoids (leukotriene [LT] C₄, prostaglandin [PG] D₂, and thromboxane A₂), which mediate vascular leak, bronchoconstriction, and effector cell chemotaxis. Little is known about the significance and regulation of eicosanoid generation in response to nonclassical MC activation mechanisms.

OBJECTIVES

We sought to determine the regulation and significance of MC-derived eicosanoids synthesized in response to IL-33, a cytokine critical to innate type 2 immunity.

METHODS

We used an ex vivo model of mouse bone marrow-derived mast cells and an IL-33-dependent in vivo model of aspirin-exacerbated respiratory disease (AERD).

RESULTS

IL-33 potently liberates AA and elicits LTC₄, PGD₂, and thromboxane A₂ production by bone marrow-derived mast cells. Unexpectedly, the constitutive function of COX-1 is required for IL-33 to activate group IVa cytosolic phospholipase A₂ with consequent AA release for synthesis of all eicosanoids, including CysLTs. In contrast, COX-1 was dispensable for FcεRI-driven CysLT production. Inhibition of COX-1 prevented IL-33-induced phosphorylation of extracellular signal-related kinase, an upstream effector of cytosolic phospholipase A₂, which was restored by exogenous PGH₂, implying that the effects of COX-1 required its catalytic function. Administration of a COX-1-selective antagonist to mice completely prevented the generation of both PGD₂ and LTC₄ in a model of AERD in which MC activation is IL-33 driven.

CONCLUSIONS

MC-intrinsic COX-1 amplifies IL-33-induced activation in the setting of innate type 2 immunity and might help explain the phenomenon of therapeutic desensitization to aspirin by nonselective COX inhibitors in patients with AERD.

Endogenous prostaglandin E2 amplifies IL-33 production by macrophages through an E prostanoid (EP)2/EP4-cAMP-EPAC-dependent pathway

When activated through toll-like receptors (TLRs), macrophages generate IL-33, an IL-1 family member that induces innate immune responses through ST2 signaling. LPS, a TLR4 ligand, induces macrophages to generate prostaglandin E₂ (PGE₂) through inducible COX-2 and microsomal PGE₂ synthase 1 (mPGES-1) (1). We demonstrate that IL-33 production by bone marrow-derived murine macrophages (bmMFs) requires the generation of endogenous PGE₂ and the intrinsic expression of EP₂ receptors to amplify NF-κB-dependent, LPS-induced IL-33 expression via exchange protein activated by cAMP (EPAC). Compared with WT cells, bmMFs lacking either mPGES-1 or EP₂ receptors displayed reduced LPS-induced IL-33 levels. A selective EP₂ agonist and, to a lesser extent, EP₄ receptor agonist potentiated LPS-induced IL-33 generation from both mPGES-1-null and WT bmMFs, whereas EP₁ and EP₃ receptor agonists were inactive. The effects of PGE₂ depended on cAMP, were mimicked by an EPAC-selective agonist, and were attenuated by EPAC-selective antagonism and knockdown. LPS-induced p38 MAPK and NF-κB activations were necessary for both IL-33 production and PGE₂ generation, and exogenous PGE₂ partly reversed the suppression of IL-33 production caused by p38 MAPK and NF-κB inhibition. Mice lacking mPGES-1 showed lower IL-33 levels and attenuated lung inflammation in response to repetitive Alternaria inhalation challenges. Cumulatively, our data demonstrate that endogenous PGE₂, EP₂ receptors, and EPAC are prerequisites for maximal LPS-induced IL-33 expression and that exogenous PGE₂ can amplify IL-33 production via EP₂ and EP₄ receptors. The ubiquitous induction of mPGES-1-dependent PGE₂ may be crucial for innate immune system activation during various IL-33 driven pathologic disorders.

The Bacillus subtilis and Bacillus halodurans Aspartyl-tRNA Synthetases Retain Recognition of tRNA(Asn)

Synthesis of asparaginyl-tRNA (Asn-tRNA(Asn)) in bacteria can be formed either by directly ligating Asn to tRNA(Asn) using an asparaginyl-tRNA synthetase (AsnRS) or by synthesizing Asn on the tRNA. In the latter two-step indirect pathway, a non-discriminating aspartyl-tRNA synthetase (ND-AspRS) attaches Asp to tRNA(Asn) and the amidotransferase GatCAB transamidates the Asp to Asn on the tRNA. GatCAB can be similarly used for Gln-tRNA(Gln) formation. Most bacteria are predicted to use only one route for Asn-tRNA(Asn) formation. Given that Bacillus halodurans and Bacillus subtilis encode AsnRS for Asn-tRNA(Asn) formation and Asn synthetases to synthesize Asn and GatCAB for Gln-tRNA(Gln) synthesis, their AspRS enzymes were thought to be specific for tRNA(Asp). However, we demonstrate that the AspRSs are non-discriminating and can be used with GatCAB to synthesize Asn. The results explain why B. subtilis with its Asn synthetase genes knocked out is still an Asn prototroph. Our phylogenetic analysis suggests that this may be common among Firmicutes and 30% of all bacteria. In addition, the phylogeny revealed that discrimination toward tRNA(Asp) by AspRS has evolved independently multiple times. The retention of the indirect pathway in B. subtilis and B. halodurans likely reflects the ancient link between Asn biosynthesis and its use in translation that enabled Asn to be added to the genetic code.

The predatory bacterium Bdellovibrio bacteriovorus aspartyl-tRNA synthetase recognizes tRNAAsn as a substrate

The predatory bacterium Bdellovibrio bacteriovorus preys on other Gram-negative bacteria and was predicted to be an asparagine auxotroph. However, despite encoding asparaginyl-tRNA synthetase and glutaminyl-tRNA synthetase, B. bacteriovorus also contains the amidotransferase GatCAB. Deinococcus radiodurans, and Thermus thermophilus also encode both of these aminoacyl-tRNA synthetases with GatCAB. Both also code for a second aspartyl-tRNA synthetase and use the additional aspartyl-tRNA synthetase with GatCAB to synthesize asparagine on tRNA^Asn. Unlike those two bacteria, B. bacteriovorus encodes only one aspartyl-tRNA synthetase. Here we demonstrate the lone B. bacteriovorus aspartyl-tRNA synthetase catalyzes aspartyl-tRNA^Asn formation that GatCAB can then amidate to asparaginyl-tRNA^Asn. This non-discriminating aspartyl-tRNA synthetase with GatCAB thus provides B. bacteriovorus a second route for Asn-tRNA^Asn formation with the asparagine synthesized in a tRNA-dependent manner. Thus, in contrast to a previous prediction, B. bacteriovorus codes for a biosynthetic route for asparagine. Analysis of bacterial genomes suggests a significant number of other bacteria may also code for both routes for Asn-tRNA^Asn synthesis with only a limited number encoding a second aspartyl-tRNA synthetase.

Prolactin as a marker of successful catheterization during IPSS in patients with ACTH-dependent Cushing's syndrome

CONTEXT

Anomalous venous drainage can lead to false-negative inferior petrosal sinus sampling (IPSS) results. Baseline inferior petrosal sinus to peripheral (IPS/P) prolactin ratio higher than 1.8 ipsilateral to the highest ACTH ratio has been proposed to verify successful catheterization. Prolactin-normalized ACTH IPS/P ratios may differentiate Cushing's disease (CD) from ectopic ACTH syndrome (EAS).

OBJECTIVE

Our objective was to examine the utility of prolactin measurement during IPSS.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a retrospective analysis of prolactin levels in basal and CRH-stimulated IPSS samples in ACTH-dependent Cushing's syndrome (2007-2010).

RESULTS

Twenty-five of 29 patients had a pathologically proven diagnosis (17 CD and eight EAS). IPSS results were partitioned into true positive for CD (n = 16), true negative (n = 7), false negative (n = 1), and false positive (n = 1). Prolactin IPS/P ratio suggested successful IPSS in eight of 11 with abnormal venograms. Baseline prolactin IPS/P ratio was helpful in two patients with abnormal venograms and false-negative (catheterization unsuccessful) or true-negative (catheterization successful) IPSS results; the normalized ratio correctly diagnosed their disease. Normalized ACTH IPS/P ratio was at least 1.3 in all with CD, but prolactin IPS/P ratios were misleadingly low in two. One patient with cyclic EAS had a false-positive IPSS when eucortisolemic (baseline prolactin IPS/P = 1.7; normalized ratio = 5.6). All other EAS patients had normalized ratios no higher than 0.7.

CONCLUSION

Prolactin measurement and evaluation of the venogram can improve diagnostic accuracy when IPSS results suggest EAS but is not necessary with positive IPSS results. Confirmation of hypercortisolemia remains a prerequisite for IPSS. A normalized ratio of 0.7-1.3 was not diagnostic.

Salivary cortisol increases after bariatric surgery in women

Cortisol increases have been associated with psychological and physiological stress; however, cortisol dynamics after weight loss (bariatric) surgery have not been defined. Obese participants not using exogenous glucocorticoids were eligible to participate. Female participants (n=24) provided salivary cortisol samples at bedtime, upon awakening the following morning, and 30 min after awakening before, and at 6 or 12 months after bariatric surgery. The Medical Outcomes Study Short Form-12 version 2 questionnaire regarding health-related quality of life was also completed. Preoperatively, mean body mass index was 45.1±8.1 kg/m2. Mean late night (1.8±1.1 nmol/l), awakening (10.7±7.4 nmol/l), and after-awakening (11.5±7.9 nmol/l) salivary cortisol values were within normal ranges. The cortisol awakening response (mean 21.1±79.7%, median 13.7%) was at the low end of normal. Preoperatively, participants had lower mental and physical health-related quality of life scores than US adult norms (p<0.001). Salivary cortisol was not correlated with measures of health-related quality of life. Mean BMI decreased over time (p<0.001) and participants experienced improved physical and mental health-related quality of life (p≤0.011). Postoperative late night salivary cortisol was not different from preoperative values. Awakening and after-awakening cortisol levels were higher than preoperative values (15.3±7.7 nmol/l, p=0.013; 17.5±10.2 nmol/l, p=0.005; respectively), but the cortisol awakening response was not changed (mean 26.7±66.2%; median 7.8%). Morning salivary cortisol increased at long-term follow-up after bariatric surgery. Although self-evaluated mental and physical health improved after surgery, the cortisol awakening response is at the low end of normal, which may indicate continued physiological stress.

Epidermal growth factor and parathyroid hormone-related peptide mRNA in the mammary gland and their concentrations in milk: effects of postpartum hypoxia in lactating rats

The physiological adaptations of the neonatal rat to hypoxia from birth include changes in gastrointestinal function and intermediary metabolism. We hypothesized that the hypoxic lactating dam would exhibit alterations in mammary gland function leading to changes in the concentration of milk peptides that are important in neonatal gastrointestinal development. The present study assessed the effects of chronic hypoxia on peptides produced by the mammary glands and present in milk. Chronic hypoxia decreased the concentration of epidermal growth factor (EGF) in expressed milk and pup stomach contents and decreased maternal mammary gland EGF mRNA. The concentration of parathyroid hormone-related protein (PTHrp) was unchanged in milk and decreased in pup stomach contents; however, mammary PTHLH mRNA was increased by hypoxia. There was a significant increase in adiponectin concentrations in milk from hypoxic dams. Chronic hypoxia decreased maternal body weight, and pair feeding normoxic dams an amount of food equivalent to hypoxic dam food intake decreased body weight to an equivalent degree. Decreased food intake did not affect the expression of EGF, PTHLH, or LEP mRNA in mammary tissue. The results indicated that chronic hypoxia modulated mammary function independently of hypoxia-induced decreases in maternal food intake. Decreased EGF and increased adiponectin concentrations in milk from hypoxic dams likely affect the development of neonatal intestinal function.

Augmented hypothalamic corticotrophin-releasing hormone mRNA and corticosterone responses to stress in adult rats exposed to perinatal hypoxia

Stressful events before or just after parturition alter the subsequent phenotypical response to stress in a general process termed programming. Hypoxia during the period before and during parturition, and in the postnatal period, is one of the most common causes of perinatal distress, morbidity, and mortality. We have found that perinatal hypoxia (prenatal day 19 to postnatal day 14) augmented the corticosterone response to stress and increased basal corticotrophin-releasing hormone (CRH) mRNA levels in the parvocellular portion of the paraventricular nucleus (PVN) in 6-month-old rats. There was no effect on the levels of hypothalamic parvocellular PVN vasopressin mRNA, anterior pituitary pro-opiomelanocortin or CRH receptor-1 mRNA, or hippocampus glucocorticoid receptor mRNA. We conclude that hypoxia spanning the period just before and for several weeks after parturition programmes the hypothalamic-pituitary-adrenal axis to hyper-respond to acute stress in adulthood, probably as a result of drive from the parvocellular CRH neurones.

An oxidized derivative of linoleic acid stimulates dehydroepiandrosterone production by human adrenal cells

We previously reported that an oxidized derivative of linoleic acid stimulated steroidogenesis in rat adrenal cells. This derivative was also detected in human plasma, and was positively correlated with visceral adiposity and plasma DHEA-S. The present study sought to characterize the effects of this derivative, 12,13-epoxy-9-keto-(10- trans)-octadecenoic acid (EKODE), on steroid production by normal human adrenocortical cells obtained during clinically-indicated adrenalectomy. Cell suspensions were incubated in the presence of varying concentrations of EKODE and ACTH. EKODE (16 microM) significantly increased DHEA production by 28% under basal conditions and by 25% in the presence of a low concentration of ACTH (0.2 ng/ml). The effect on DHEA was absent at a higher ACTH concentration (2.0 ng/ml). EKODE decreased cortisol production by 16% (low ACTH) and 25% (high ACTH), but was without effect on cortisol under basal conditions. The results suggest that EKODE affects adrenal DHEA production in the human, possibly by modulating steroidogenic enzyme activity. We postulate that excess visceral fat delivers fatty acids to the liver, where oxidized derivatives are formed that modulate adrenal steroidogenesis. This may be an important phenomenon in the genesis of changes in adrenal function associated with syndromes of obesity, especially those that include androgen excess.

Oxidized products of linoleic acid stimulate adrenal steroidogenesis

Adrenal steroidogenesis is under complex control, and clinical observations suggest that not all regulators have been identified. We postulated that fatty acid oxidation products found in the diet or formed in the body could affect steroidogenesis. Linoleic acid is a prominent constituent of animal fat and is readily oxidized. We found that several products of linoleic acid oxidation affect production of aldosterone and corticosterone by isolated cells from rat adrenals. We characterized one linoleic acid derivative by gas chromatography/mass spectrometry. It is 12,13-epoxy-9-oxo-10(trans)-octadecenoic acid ("EKODE"). At concentrations between 1 and 30 microM, EKODE stimulated production of aldosterone by zona glomerulosa cells, but at concentrations above 50 microM, it was inhibitory. In zona fasciculata cells, EKODE stimulated corticosterone production at concentrations of 5 microM or greater, and there was no evidence of inhibition at high concentrations. Stimulation of steroidogenesis was observed after 15 min of incubation and continued for at least 2 hrs. The potential relevance of our findings to the hypertension of obesity is discussed.

Oxygen-dependence of ACTH-stimulated aldosterone and corticosterone synthesis in the rat adrenal cortex: developmental aspects

The control of ACTH-stimulated steroidogenesis under decreasing levels of O(2) is not fully understood. The purpose of this study was to examine the effects of decreased O(2) in vitro on rat adrenocortical steroid synthesis at different stages of development. Of interest was the evaluation of the effect of low O(2) on steroidogenesis during the stress hyporesponsive period of the neonate. Rats were killed at 7, 14, or 42 days of age, adrenals collected and capsules (zona glomerulosa, ZG) separated from subcapsules (zona fasciculata/reticularis, ZFR). Cells were dispersed and placed into glass vials each gassed with a different level of O(2) (21, 5, 2, 1, or 0% O(2)). The entire steroidogenic pathway was analyzed by measuring ACTH-stimulated cAMP, corticosterone and aldosterone production during a 2 h incubation. In addition, the early (P450 scc) and late (P450c11 beta and P450 aldo) pathway activities were examined in the presence of cyanoketone. The PO(2) for half-maximal activity (P(50)) for aldosterone synthesis in ZG cells from 7- and 42-day-old rats was approximately 28 mmHg and 7 mmHg respectively, indicating that cells from older rats were more resistant to inhibition by low O(2). The P(50) for cAMP production from the ZG was approximately 14 mmHg for both age groups. The P(50) for corticosterone synthesis was approximately 28 mmHg and <7 mmHg in ZFR cells from 7- and 42-day-old cells respectively. The only enzyme activities affected by low O(2) (<35 mmHg) were P450 aldo and P450 scc. Moderate decreases in O(2) (from approximately 150 mmHg) decreased aldosteronogenesis, possibly due to observed decreases in cAMP generation, but not due to decreases in steroidogenic enzyme activity (7-day-old). Severe decreases in O(2) presumably inhibited P450 aldo through a direct effect on enzyme activity (both ages). P450 scc activity (including cholesterol transport) also seems to be decreased by very low O(2) (7-day-old). These findings illustrate a novel developmental alteration in O(2)-regulated steroid production, and may have implications for neonatal health and disease.

Mandibular and palatal tori, bone mineral density, and salivary cortisol in community-dwelling elderly men and women

BACKGROUND

This investigation evaluated the relationship between the presence of tori and bone mineral density (BMD) and salivary cortisol levels.

METHODS

A total of 230 healthy, community-dwelling elderly men (n = 129) and women (n = 101) aged 60 and older participated in this study. Forty-three women were on hormone replacement therapy (HRT). This was a component of a 5-year longitudinal study measuring subjects' body composition, hormone levels, physical activity, and diet every 6 months. Subjects were examined for the presence of tori by visual inspection and digital palpation. BMD at six sites was measured by dual-energy X-ray absorptiometry. Salivary cortisol levels were measured by radioimmunoassay.

RESULTS

Twenty-three percent of all subjects had mandibular tori, 13% had palatal tori, and 12% had both mandibular and palatal tori. Mandibular tori were more common in men, and palatal tori were more common in women. The presence of mandibular tori was significantly correlated with BMD of the lumbar spine, femoral neck, trochanter, and Ward's triangle for all subjects, and with the femoral neck and trochanter of women not on HRT. Men with palatal tori had lower levels of salivary cortisol in the evening.

CONCLUSIONS

This study documented the high prevalence of mandibular and palatal tori in a group of 230 elderly, community-dwelling subjects. Women not on HRT and all subjects taken as a group with mandibular tori had higher BMD. The presence of tori at young adulthood may be a marker of higher BMD in the future and of a lower risk for developing osteoporosis.

Growth hormone therapy during neonatal hypoxia in rats: body composition, bone mineral density, and insulin-like growth factor-1 expression

Hypoxia from birth results in a decrease in body weight gain, body size, and bone mineral density (BMD). The purpose of the present study was to determine whether short-term administration of growth hormone (GH) (rat GH; 100 microg/d) could attenuate some of these effects of neonatal hypoxia. Rat pups (with their lactating dams) were exposed to hypoxia (vs normoxic control) from birth. Hypoxia was continued until 14 d of age, with rat GH (vs vehicle control) administered daily. Hypoxia significantly inhibited body weight gain; GH therapy did not reverse this effect. GH therapy did reverse the inhibitory effect of hypoxia on tail length but not on body length. Hypoxia decreased BMD analyzed by dual X-ray absorptiometry (DXA); this effect was not reversed by GH therapy. Both GH therapy and hypoxia decreased the percentage of body fat analyzed by DXA, the effects of which were additive when combined. There were minimal effects of hypoxia and GH therapy on plasma insulin-like growth factor-1 (IGF-1), IGF-binding protein-3, and hepatic IGF-1 mRNA expression. We conclude that some of the effects of hypoxia on body habitus are reversed by GH therapy, but that short-term GH therapy did not prevent a loss of BMD. GH therapy for more than 14 days may be necessary to appreciate fully its potential in the treatment of the sequelae of neonatal hypoxia.

Suppression of hypothalamic-pituitary-adrenal axis activity with inhaled flunisolide and fluticasone propionate in adult asthma patients

BACKGROUND

Suppression of the hypothalamic-pituitary-adrenal (HPA) axis, a potential systemic effect of inhaled corticosteroid therapy, can be quantified by monitoring serum, urinary, and salivary cortisol levels.

OBJECTIVES

1) Compare the effects on HPA axis of the inhaled corticosteroids flunisolide and fluticasone propionate versus placebo and oral prednisone. 2) Estimate dose-potency ratio for HPA-axis suppression.

METHODS

Multicenter, randomized, placebo-controlled, open-label, 21-day trial. Active regimens were flunisolide 500 and 1,000 microg, twice daily; fluticasone propionate 110, 220, 330, and 440 microg, twice daily; and prednisone, 7.5 mg daily. Enrolled patients were nonsmokers, 18 to 50 years of age, with persistent mild-to-moderate asthma and had not used oral, nasal, or inhaled corticosteroids for 6 months before study. Main outcome measures were area under serum cortisol concentration curve for 22 hours (AUC(0-22h)); 24-hour urinary cortisol level; and 8 AM salivary cortisol level.

RESULTS

One hundred fifty-three patients were randomly assigned to active treatment or placebo; 125 patients completed the study and were at least 80% compliant with their regimens. Both fluticasone propionate and flunisolide caused dose-dependent suppression of HPA axis, which was statistically greater for fluticasone propionate (P = 0.0003). Dose-potency ratio showed 4.4 times more serum-cortisol suppression/microgram increase in dose with fluticasone propionate than with flunisolide. Diurnal pattern of serum cortisol suppression was persistent with fluticasone propionate and "remitting" with flunisolide. Salivary and urinary cortisol data were qualitatively similar to serum cortisol results.

CONCLUSIONS

Fluticasone caused significantly more suppression of HPA axis than flunisolide. Flunisolide may provide a safe option for patients with asthma requiring long-term inhaled corticosteroid therapy.

Diagnosis and differential diagnosis of Cushing's syndrome

The clinical recognition of Cushing's syndrome and its biochemical confirmation is a challenging problem. The best diagnostic approach to patients with suspected Cushing's syndrome is still evolving. The traditional diagnostic approach of urine free cortisol and low-dose dexamethasone suppression testing may be inadequate when the degree of hypercortisolism is mild. Late-night salivary cortisol determinations may evolve as the simplest means of screening patients for suspected hypercortisolism. Repeated measurements of cortisol secretion (urine free cortisol or late-night salivary cortisol) over an extended period of time may be necessary to provide diagnostic certainty. The dexamethasone-CRH test is a reasonable approach in patients with equivocal data. The introduction of reliable, sensitive, and specific plasma ACTH measurements, the use of IPSS for ACTH with CRH stimulation, and the improved techniques of pituitary and adrenal imaging have made the differential diagnosis of Cushing's syndrome relatively straightforward (see Fig. 2). Clinicians who have never missed the diagnosis of Cushing's syndrome or have never been fooled by attempting to establish its cause should refer their patients with suspected hypercortisolism to someone who has.

Effect of neonatal hypoxia on leptin, insulin, growth hormone and body composition in the rat

The purpose of the present study was to evaluate the effect of exposure to hypoxia from birth to 7 days of age on leptin, insulin, growth hormone (GH), insulin-like growth factor-1 (IGF-1), glucose, corticosterone, body weight, and body composition in rats studied at 7 days of age and then after return to normoxia. Hypoxia for the first 7 days of life resulted in a significant decrease in plasma leptin, body weight, and an increase in corticosterone and insulin with no change in plasma glucose, GH or IGF-1. There was no significant effect of hypoxia on % lean body mass, but a small but significant increase in % body fat. Bone mineral density (BMD) was lower in 7-day-old hypoxic rats as compared to normoxic controls. All hormonal variables and BMD had normalized by 7 days after return to normoxia. However, body weight remained lower even 5 weeks after return to normoxia. We conclude that leptin is decreased during neonatal hypoxia despite no change in adiposity. Furthermore, insulin is increased probably to overcome the effects of increased counterregulatory hormones (such as corticosterone).

Comparison of adrenal vein sampling and computed tomography in the differentiation of primary aldosteronism

Determination of the etiology of primary aldosteronism remains a diagnostic challenge. The most common types of primary aldosteronism are bilateral adrenal hyperplasia (BAH), aldosterone-producing adenomas (APA), and primary adrenal hyperplasia. Computed tomography (CT) and adrenal vein sampling (AVS) are the primary modalities used to differentiate these subtypes. The purpose of this study was to compare AVS and CT imaging of the adrenal glands in patients with hyperaldosteronism in whom CT imaging was normal or in whom focal unilateral or bilateral adrenal abnormalities were detected. The diagnosis of primary aldosteronism was made in 62 patients based on an elevated plasma aldosterone to PRA ratio and an elevated urinary aldosterone excretion rate. Thirty-eight patients had CT imaging and successful bilateral adrenal vein sampling and were included in the final analysis. AVS was considered the gold standard in determining the specific subtype of primary aldosteronism. There were 15 patients with APA, 21 patients with BAH, and 2 patients with primary adrenal hyperplasia. Plasma aldosterone was significantly higher in patients with APA (46.3 +/- 8.5 ng/dL; 1284 +/- 235 pmol/L) than in those with BAH (29.3 +/- 2.4 ng/dL; 813 +/- 11 pmol/L; P < 0.05). Plasma potassium was significantly lower in patients with APA (3.1 +/- 0.1 mmol/L) than in patients with BAH (3.5 +/- 0.1 mmol/L; P < 0.02). There was considerable overlap in the other biochemical indices (e.g. PRA and urinary aldosterone) in patients with the different subtypes. In patients with APA proven by AVS, eight had concordant findings with CT imaging, four had discordant findings, and three had normal CT imaging. In patients with BAH proven by AVS, four had concordant findings with CT imaging, eight had discordant findings, and nine had normal CT imaging. Compared with AVS, CT imaging was either inaccurate or provided no additional information in 68% of the patients with primary aldosteronism. We conclude that adrenal CT imaging is not a reliable method to differentiate primary aldosteronism. Adrenal vein sampling is essential to establish the correct diagnosis of primary aldosteronism.

Effect of neonatal hypoxia on the development of hepatic lipase in the rat

Increases in plasma lipids occur during hypoxia in suckling but not in weaned rats and may result from altered hepatic enzyme activity. We exposed rats to 7 days of hypoxia from birth to 7 days of age (suckling) or from 28 to 35 days of age (weaned at day 21). Hypoxia led to an increase in hepatic lipid content in the suckling rat only. Hepatic lipase was decreased to approximately 45% of control in 7-day-old rats exposed to hypoxia but not in hypoxic 35-day-old rats. Hypoxic suckling rats also had a 50% reduction in lactate dehydrogenase activity, whereas transaminase activity and CYP1A and CYP3A protein content were not different between hypoxic and normoxic groups. Additional rats were studied 7 and 14 days after recovery from hypoxic exposure from birth to 7 days of age; hepatic lipase activity had recovered to 85% by 7 days and to 100% by 14 days in the rats previously exposed to hypoxia. Administration of dexamethasone to neonatal rats to simulate the hyperglucocorticoid state found in hypoxic 7-day-old rats led to a moderate decrease ( approximately 75% of control) in hepatic lipases. Developmentally, in the normoxic state, hepatic lipases increased rapidly after birth and reached levels more than twofold that of the newborn by 7 days of age. Hypoxia delays the maturation of hepatic lipases. We suggest that the decrease in hepatic lipase activity contributes to hyperlipemia in the hypoxic newborn rats.

Randomized trial of oral hydrocortisone and its effect on emergency physicians during night duty

STUDY OBJECTIVE

To analyze the effects of hydrocortisone (40 mg. p.o.) administered to emergency physicians on their first night shift following a series of day shifts.

DESIGN

Prospective, double-blinded internal crossover study on objective and subjective parameters. Each participant was studied for a minimum of 10 nights.

TYPE OF PARTICIPANTS

Four healthy male emergency physicians in their mid to late thirties.

INTERVENTIONS

After baseline endocrine assessment, the subjects ingested a capsule containing either 40 mg of hydrocortisone or placebo (lactose) at the start of a first nightshift (starting at 10 pm or 11 pm) after day duty. Subjects self-administered psychological testing one hour after taking an oral capsule by listening to a self-guided audio tape (between 11 and 12 p.m), and again between 4 and 5 am. Blood samples were obtained during the first 4 nights of each subject at 11 pm, 2, 5 and 8 am.

MEASUREMENTS AND MAIN RESULTS

Four emergency physicians entered 42 nights of data. No differences in testing were detected. Plasma cortisol levels were measured and demonstrated cortisol levels consistent with oral replacement therapy. Physicians could subjectively differentiate the difference between hydrocortisone treatment and placebo: of 21 hydrocortisone nights, 17 were identified as "a good night" in reference to fatigue. Of 21 nights without hydrocortisone, 15 were identified as "bad" nights, (p < .001).

CONCLUSION

Hydrocortisone, administered before a nightshift to day-accommodated workers, recreated the rise of plasma cortisol seen on awakening and was shown to be an effective means of decreasing subjective fatigue of a first nightshift.

The effect of fetal hypoxia on adrenocortical function in the 7-day-old rat

Fetal hypoxia in late gestation is a common cause of postnatal morbidity. The purpose of the present study was to evaluate adrenal function in vivo and in vitro in 7-d-old rat pups previously exposed to normoxia or hypoxia (12% O2) during the last 2-3 d of gestation. Seven-day-old rats exposed to fetal hypoxia had a small, but significant decrease in plasma aldosterone despite no decreases in plasma ACTH or renin activity. There was a small (approx 20%) but significant decrease in the aldosterone and corticosterone response to cAMP in vitro in dispersed cells from 7-d-old pups exposed to fetal hypoxia. The aldosterone, corticosterone, and cAMP response to ACTH, however, was not altered by prior fetal hypoxia. There was also no effect of fetal hypoxia on steroidogenic enzyme expression or zonal dimension in 7-d-old rats. We conclude that fetal hypoxia in late gestation results in a subtle decrease in cAMP-stimulated steroidogenesis. Fetal hypoxia appears to have minimal effects on subsequent adrenal function in the neonatal rat.

Neonatal hypoxic hyperlipidemia in the rat: effects on aldosterone and corticosterone synthesis in vitro

Neonatal hypoxia increases aldosterone production and plasma lipids. Because fatty acids can inhibit aldosterone synthesis, we hypothesized that increases in plasma lipids restrain aldosteronogenesis in the hypoxic neonate. We exposed rats to 7 days of hypoxia from birth to 7 days of age (suckling) or from 28 to 35 days of age (weaned at day 21). Plasma was analyzed for lipid content, and steroidogenesis was studied in dispersed whole adrenal glands untreated and treated to wash away lipids. Hypoxia increased plasma cholesterol, triglycerides, and nonesterified fatty acids in the suckling neonatal rat only. Washing away lipids increased aldosterone production in cells from 7-day-old rats exposed to hypoxia, but not in cells from normoxic 7-day-old rats or from normoxic or hypoxic 35-day-old rats. Addition of oleic or linolenic acid to washed cells inhibited both aldosterone and corticosterone production, although cells from hypoxic 7-day-old rats were less sensitive. We conclude that hypoxia induces hyperlipidemia in the suckling neonate and that elevated nonesterified fatty acids inhibit aldosteronogenesis.

Elevated salivary cortisol in the evening in healthy elderly men and women: correlation with bone mineral density

BACKGROUND

Aging is associated with a loss of bone mineral density (BMD) in men and women. Loss of BMD can also be caused by hypercortisolemia in men or women at any age. This study measured salivary cortisol at 2300 h and 0700 h as indices of cortisol secretory activity in 228 elderly, community-dwelling subjects. Salivary cortisol results were correlated with BMD. We hypothesized that salivary cortisol is elevated at 2300 h in elderly people, and that salivary cortisol will correlate negatively with BMD.

METHODS

Saliva was sampled at 2300 h (nadir in circadian rhythm) and 0700 h (peak in circadian rhythm) in 130 men (70.7 +/- 0.4 years old) and 98 women (70.0 +/- 0.4 years old); approximately half of the women were receiving hormone replacement therapy (HRT). BMD was measured by dual energy x-ray absorptiometry.

RESULTS

Salivary cortisol at 2300 h was significantly elevated in men (2.3 +/- 0.1 nmol/L) and women (2.1 +/- 0.1 nmol/L) as compared to 73 younger controls (1.2 +/- 0.1 nmol/L; 37 +/- 1 year old). Salivary cortisol at 0700 h was not different between older subjects and younger controls. There was a significant negative correlation of lumbar (L2-4) BMD and 2300 h salivary cortisol in older women (r = -0.20, p = .05; n = 98); this correlation was significant only in women not on HRT. There was a highly significant negative correlation of lumbar (L2-4) BMD and 0700 h salivary cortisol in older men (r = -0.31, p = .0003).

CONCLUSIONS

Salivary cortisol is a simple, nonstressful method for assessing activity of the hypothalamic-pituitary-adrenal (HPA) axis in the elderly population. A major finding was an elevation in the late night nadir in cortisol secretion. We also suggest that elevated cortisol secretion in elderly people may contribute to the age-related loss in bone mineral density and that this effect is prevented by HRT.

The effect of hypoxia on plasma leptin and insulin in newborn and juvenile rats

Hypoxia leads to a decrease in food intake and attenuated weight gain in rats. The purpose of this study was to measure plasma leptin and insulin in young rats exposed to hypoxia for 7 d as compared to a normoxic control group of the same age. One group was exposed from birth to 7 d of age; the other was exposed from 28 to 35 d of age (weaned at 21 d of age). As expected, body weight was significantly lower in rats of either age exposed to hypoxia for 7 d. Plasma leptin was significantly lower in hypoxic (2.0+/-0.2 ng/mL; n = 41) compared with normoxic (2.6+/-0.3 ng/mL; n = 30) 7-d-old rats. Plasma leptin was also significantly lower in hypoxic (1.1+/-0.1 ng/mL; n = 20) as compared to normoxic (1.5+/-0.1 ng/mL; n = 20) 35-d-old rats. Seven-day-old rats exposed to hypoxia demonstrated significant increases in plasma glucose and insulin whereas 35-d-old rats exhibited a decrease in both variables. We conclude that exposure to hypoxia for 7 d leads to a decrease in body weight and plasma leptin in infant and juvenile rats. The decrease in leptin may be an attempt to reverse hypoxia-induced anorexia.

The effect of hypoxia from birth on the regulation of aldosterone in the 7-day-old rat: plasma hormones, steroidogenesis in vitro, and steroidogenic enzyme messenger ribonucleic acid

Adaptation to hypoxia in the neonate requires an appropriate adrenocortical response. The purpose of this study was to examine the adaptation of the aldosterone pathway in rat pups exposed to hypoxia in vivo from birth to 7 days of age. Neonatal rats (with their lactating dams) were exposed to normoxia (21% O2) or hypoxia (12% O2) continuously for 7 days from birth. Trunk blood was collected, and entire adrenal glands were processed from 7-day-old rats to study the activity of the steroidogenic pathway in dispersed cells and isolated mitochondria, for measurement of expression of the steroidogenic enzyme messenger RNAs (mRNAs) by RT-competitive PCR and in situ hybridization histochemistry, for measurement of zona glomerulosa width by immunohistofluorescent staining for P450c11AS protein, and for measurement of mitochondrial number and distribution by transmission electron microscopy. Exposure to hypoxia for 7 days from birth resulted in a marked increase in plasma ACTH, corticosterone, and aldosterone with no change in PRA. Aldosteronogenesis and P450c11AS activity were both augmented in dispersed cells; this effect was lost in isolated mitochondria (from entire adrenal glands) using a permeable substrate for P450c11AS. There was no significant effect of hypoxia on expression of the steroidogenic enzyme mRNAs measured by RT-competitive PCR or in situ hybridization histochemistry. Finally, hypoxia had no effect on mitochondrial number or stereology as assessed by transmission electron microscopy or on zona glomerulosa width as assessed by staining for P450c11AS protein. We conclude that, as opposed to that in adults, hypoxia in the neonate results in an augmentation of aldosteronogenesis. This effect is not accounted for by a change in steroidogenic enzyme mRNA expression, zona glomerulosa width (i.e. hyperplasia), or mitochondrial number or distribution. This functional augmentation of aldosteronogenesis may be due to a change in mitochondrial permeability to steroid substrates and/or the effect of cytosolic factors that control mitochondrial steroidogenesis.

Newer diagnostic techniques and problems in Cushing's disease

The best diagnostic approach to patients with suspected Cushing's disease continues to evolve. The introduction of transsphenoidal pituitary surgery as the treatment of choice for Cushing's disease as well as the absence of any pituitary imaging abnormalities in many patients with Cushing's disease has made accurate diagnosis and differential diagnosis essential. In the authors' opinion, two or three late night (11 PM) salivary cortisol determinations and the measurement of 24-hour UFC are the best and simplest means to evaluate patients with suspected hypercortisolism. L-DST can no longer be recommended to exclude the diagnosis of Cushing's disease, particularly if the hypercortisolism is mild. The combination of L-DST and CRH stimulation is a new and apparently sensitive means to establish the presence or absence of pathologic hypercortisolism in equivocal cases. In the absence of an overt pituitary tumor on MR imaging, inferior petrosal sinus sampling with CRH stimulation should be performed to secure the diagnosis of Cushing's disease as well as identify the probable location of the corticotroph adenoma.

Late-night salivary cortisol as a screening test for Cushing's syndrome

The clinical features of Cushing's syndrome (such as obesity, hypertension, and diabetes) are commonly encountered in clinical practice. Patients with Cushing's syndrome have been identified by an abnormal low-dose dexamethasone suppression test, elevated urine free cortisol (UFC), an absence of diurnal rhythm of plasma cortisol, or an elevated late-night plasma cortisol. Because the concentration of cortisol in the saliva is in equilibrium with the free (active) cortisol in the plasma, measurement of salivary cortisol in the evening (nadir) and morning (peak) may be a simple and convenient screening test for Cushing's syndrome. The purpose of this study was to evaluate the usefulness of the measurement of late-night and morning salivary cortisol in the diagnosis of Cushing's syndrome. We studied 73 normal subjects and 78 patients referred for the diagnosis of Cushing's syndrome. Salivary cortisol was measured at 2300 h and 0700 h using a simple, commercially-available saliva collection device and a modification of a standard cortisol RIA. In addition, 24-h UFC was measured within 1 month of saliva sampling. Patients with proven Cushing's syndrome (N = 39) had significantly elevated 2300-h salivary cortisol (24.0 +/- 4.5 nmol/L), as compared with normal subjects (1.2 +/- 0.1 nmol/L) or with patients referred with the clinical features of hypercortisolism in whom the diagnosis was excluded or not firmly established (1.6 +/- 0.2 nmol/L; N = 39). Three of 39 patients with proven Cushing's had 2300-h salivary cortisol less than the calculated upper limit of the reference range (3.6 nmol/L), yielding a sensitivity of 92%; one of these 3 patients had intermittent hypercortisolism, and one had an abnormal diurnal rhythm (salivary cortisol 0700-h to 2300-h ratio <2). An elevated 2300-h salivary cortisol and/or an elevated UFC identified all 39 patients with proven Cushing's syndrome (100% sensitivity). Salivary cortisol measured at 0700 h demonstrated significant overlap between groups, even though it was significantly elevated in patients with proven Cushing's syndrome (23.0 +/- 4.2 nmol/L), as compared with normal subjects (14.5 +/- 0.8 nmol/L) or with patients in whom Cushing's was excluded or not firmly established (15.3 +/- 1.5 nmol/L). Late-night salivary cortisol measurement is a simple and reliable screening test for spontaneous Cushing's syndrome. In addition, late-night salivary cortisol measurements may simplify the evaluation of suspected intermittent hypercortisolism, and they may facilitate the screening of large high-risk populations (e.g. patients with diabetes mellitus).

Intraoperative adrenocorticotropin levels during transsphenoidal surgery for Cushing's disease do not predict cure

Recently, intraoperative rapid immunochemiluminometric assay (ICMA) ACTH measurements have been used to evaluate the completeness of resection of ectopic ACTH-secreting tumors. This study evaluates whether this method can be applied to patients undergoing transsphenoidal surgery (TSS) for Cushing's disease to predict complete pituitary tumor resection. Eighteen patients with Cushing's disease undergoing TSS had plasma ACTH concentrations measured by a standard ICMA every 10 min for 1 h immediately after pituitary tumor removal. Patients were evaluated postoperatively for cure by standard criteria. ACTH levels were evaluated for percentage decrease from baseline at each time point. Patients who were cured (n = 11) had statistically greater decreases in ACTH levels (mean decrease 54%) than patients who were not (n = 7; 26% mean decrease, P < 0.04). By Receiver-Operator Characteristic (ROC) analysis, a reduction of at least 40% best predicted which patients were cured and which were not cured. This level of reduction was observed in 82% of cured patients, and a reduction of less than 40% was observed in 71% of those not cured. The analysis misclassified 4 of the 18 patients, resulting in a diagnostic accuracy of 78%. Although the mean maximal decrease in ACTH concentrations after tumor removal was significantly different between cured and not cured patients with Cushing's disease, it was less dramatic than results in the previous ectopic ACTH study. This may relate to incomplete suppression and/or surgical manipulation of normal pituitary corticotrophs in patients with pituitary disease. In summary, in contrast to the ectopic ACTH syndrome, decline of plasma ACTH during TSS does not accurately predict complete tumor resection.

Effectiveness versus efficacy: the limited value in clinical practice of high dose dexamethasone suppression testing in the differential diagnosis of adrenocorticotropin-dependent Cushing's syndrome

High dose dexamethasone suppression testing has been widely employed in the differentiation between pituitary ACTH-dependent hypercortisolism [Cushing's disease (CD)] and the ectopic ACTH syndrome. We hypothesized that the high dose dexamethasone suppression test as it is performed in practice does not improve the ability to differentiate between these two types of ACTH-dependent Cushing's syndrome. Cases were drawn from 112 consecutive patients with ACTH-dependent Cushing's syndrome, who were then classified based upon results of inferior petrosal sinus sampling for ACTH levels. Analysis of test characteristics of high dose dexamethasone suppression testing was performed in the 73 patients for whom results are available. Statistical modeling was performed using the 68 cases with complete data on all assessed variables. Logistic regression models were used to predict the probability of pituitary-dependent Cushing's syndrome (CD) given the results of high dose dexamethasone suppression testing before and after adjustment for the contribution of a series of potential covariates. Of the 112 patients with ACTH-dependent Cushing's syndrome, 15.2% had the ectopic ACTH syndrome, and the remainder had pituitary-dependent Cushing's syndrome (CD). Patients with the ectopic ACTH syndrome were significantly older (mean, 51.9 vs. 40.2), were more likely to be male (58.8% vs. 27.4%), had shorter duration of clinical findings (mean, 11.6 vs. 39.9 months), were more likely to have hypokalemia (50% vs. 8.6%), had higher baseline 24-h urinary free cortisol [mean, 8317 vs. 1164 nmol/day (3015 vs. 422 microg)] and plasma ACTH levels [mean, 47 vs. 17 pmol/L (210 vs. 78 pg/mL)] and were less likely to suppress urinary free cortisol or plasma cortisol with high dose dexamethasone using the standard criterion of 50% or more suppression compared with patients with pituitary-dependent Cushing's syndrome. Based upon the standard criterion, the sensitivity and specificity of the high dose dexamethasone suppression test for the diagnosis of pituitary-dependent Cushing's syndrome were 81.0% and 66.7%, respectively. Although the mean percent suppression was significantly greater for patients with CD than for those with the ectopic ACTH syndrome (72.2% vs. 41.3%), the range of suppression was 0-99% for each diagnosis. The area under the receiver operating characteristic curve was 0.710 (95% confidence interval, 0.541-0.879). Logistic regression models were used to evaluate the probability of CD given the responsiveness to high dose dexamethasone suppression testing before and after adjustment for the potential contributions of other factors. A model including all of the variables (age, sex, duration, presence of hypokalemia, urinary free cortisol, and plasma ACTH) had a diagnostic accuracy of 92.7%. A model including all of these variables plus a binary variable indicating whether the patient met the criterion of suppression by 50% or more resulted in 95.6% accuracy, whereas substitution of this binary variable by percent suppression resulted in a model with 94.1% accuracy. There were no statistically significant differences among these models; their values for the c statistic, which is equivalent to the area under the curve in a receiver operating characteristic analysis, were all greater than 0.9. Logistic regression models indicate that the results of the dexamethasone suppression test add little to the differential diagnosis of ACTH-dependent Cushing's syndrome, especially after taking other clinical information into account. In our patient population, the sensitivity and specificity of the dexamethasone suppression test were less than those reported by others. However, because 20-33% of cases of ectopic ACTH syndrome are misdiagnosed with these logistic regression models, other techniques are necessary to achieve greater diagnostic accuracy.

Effect of exposure to hypoxia from birth on aldosterone in rabbits: role of unesterified fatty acids

Hypoxia and fluid and electrolyte disturbances are serious risks to normal postnatal development. Because a decrease in inspired O2 (hypoxic hypoxia) inhibits aldosterone synthesis in the adult and aldosterone controls water and electrolyte balance, we studied adrenocortical function in rabbits exposed to normobaric normoxia or hypoxic hypoxia (fraction of inspired O2 0.09) from birth. At 21 days of age, rabbits were anesthetized, the adrenals were rapidly removed, and the adrenal capsules containing mostly zona glomerulosa cells were separated. Cells were dispersed with collagenase and studied in vitro. Hypoxia in vivo resulted in a 73% decrease in basal aldosterone release and a 86% decrease in adenosine 3',5'-cyclic monophosphate-stimulated aldosterone release in vitro. We hypothesized that increased unesterified fatty acids could be partly responsible for inhibition of aldosterone synthesis. Total serum unesterified fatty acids in hypoxic kits were significantly increased (298 +/- 14 micromol/l) compared with normoxic kits (184 +/- 31 micromol/l). When cells from hypoxic rabbits were washed with fatty acid-free albumin and studied under conditions devoid of fatty acids, aldosterone production was partially restored. Corticosterone production was not affected by washing. Washing had no effect on aldosterone synthesis by cells from normoxic rats. Finally, exposing washed zona glomerulosa cells to oleic acid (10-50 microM) inhibited aldosteronogenesis. We conclude that exposure to hypoxia from birth attenuates aldosterone production in part due to an increase in levels of unesterified fatty acid levels.

Liddle's syndrome: prospective genetic screening and suppressed aldosterone secretion in an extended kindred

Liddle's syndrome is an autosomal dominant form of hypertension that resembles primary hyperaldosteronism, is characterized by the early onset of hypertension with hypokalemia and suppression of both PRA and aldosterone, and is caused by mutations in the carboxyl-terminus of the beta- or gamma-subunits of the renal epithelial sodium channel. We describe a kindred (K176) whose distinguishing clinical features were mild hypertension and decreased aldosterone secretion. The index case was a 16-yr-old girl with intermittent mild hypertension and hypokalemia and subnormal PRA, aldosterone, 18-hydroxy-corticosterone, and deoxycortisol levels, but normal cortisol/cortisone metabolite ratio and cortisol half-life. A frameshift mutation in the carboxyl-terminus of the beta-subunit of the epithelial sodium channel was identified in the index case, establishing the diagnosis of Liddle's syndrome. Sixteen at-risk relatives of the index case were tested. Seven new subjects were heterozygous for the mutation found in the index case, and two deceased obligate carriers were identified. All genetically affected adult subjects had a history of mild hypertension, and four had a history of hypokalemia. Basal and postcosyntropin plasma aldosterone and urinary aldosterone levels were significantly suppressed in those positive for the mutation. The family demonstrates variability in the severity of hypertension and hypokalemia in this disease, raising the possibility that this disease may be underdiagnosed among patients with essential hypertension.

Adrenergic, respiratory, and cardiovascular effects of core cooling in humans

The adrenergic, respiratory, and cardiovascular responses to isolated core cooling were assessed in awake human subjects. Mild core hypothermia was induced by intravenous infusion of 30 or 40 ml/kg of cold saline (4 degrees C) on 2 separate days. A warm intravenous infusion (30 ml/kg, 37 degrees C) was given on a third day as a control treatment. Mean norepinephrine concentration increased 400% and total body oxygen consumption increased 30% when core temperature decreased 0.7 degrees C. Mean norepinephrine concentration increased 700% and total body oxygen consumption increased 112% when core temperature decreased 1.3 degrees C. Core cooling was associated with peripheral vasoconstriction and increased mean arterial blood pressure, whereas heart rate was unchanged. Plasma epinephrine and cortisol concentrations were unchanged during core cooling. There were no changes in any measured parameter with the warm infusion. These findings suggest that mild hypothermia induced by isolated core cooling is associated with an adrenergic response characterized by peripheral sympathetic nervous system activation without a significant adrenocortical or adrenomedullary response. The respiratory and cardiovascular responses to core cooling are characterized by a shivering-induced increase in metabolic rate, norepinephrine-mediated peripheral vasoconstriction, and increased arterial blood pressure.

Corticosterone inhibition of osmotically stimulated vasopressin from hypothalamic-neurohypophysial explants

Glucocorticoids inhibit and glucocorticoid deficiency increases vasopressin (AVP) release in vivo. To determine whether the effect of glucocorticoids is hypothalamic and mediated via a glucocorticoid receptor, explants of the hypothalamic-neurohypophysial system were used to measure AVP release during agonist and antagonist exposure. Explants from adult rats, which contained AVP neurons of the supraoptic nucleus with axonal projections terminating in the neural lobe but excluded the paraventricular nucleus, were perifused with an osmotic stimulus (increase of 5 mosmol/h over 6 h) in the absence or presence of corticosterone (100 micrograms/dl) or with corticosterone (100 micrograms/dl) in the absence or presence of the glucocorticoid antagonist RU-486 (10 microM). AVP release was not increased during osmotic stimulation in the presence of corticosterone (Cort) and was 20-30% lower than osmotically stimulated release observed in the absence of Cort. RU-486 reversed the inhibitory effect of corticosterone on AVP release. No changes in AVP mRNA content were detected. These results suggest that Cort inhibits osmotically stimulated AVP release by a direct effect within the hypothalamus and/or neurohypophysis. This effect is mediated by the glucocorticoid receptor through either genomic or nongenomic mechanisms.

Hypoxia in vivo inhibits aldosterone synthesis and aldosterone synthase mRNA in rats

Hypoxia leads to a decrease in aldosterone that cannot be entirely explained by extrinsic controllers of adrenal function. We have shown that acute hypoxia attenuates aldosterone synthesis via a direct inhibition of the function of the aldosterone enzyme pathway. The mechanism of the sustained decrease in aldosterone during chronic hypoxia is unknown. The present study evaluated the hypothesis that chronic hypoxia leads to a decrease in the expression of the steroidogenic enzyme P-450c11AS unique to the aldosterone pathway. Rats were exposed to 3 days of normoxia, moderate hypoxia (12% O2), or severe hypoxia (10% O2). Adrenal glands were removed and prepared for biochemical analysis of steroidogenesis in vitro (dispersed capsular cells) and for measurement of steady-state enzyme mRNA levels by reverse-transcription competitive polymerase-chain reaction (RT-cPCR) and by in situ hybridization histochemistry (ISHH). Moderate hypoxia had no effect on steroidogenesis. Adrenal cells from rats exposed to severe hypoxia demonstrated a decreased conversion of corticosterone to aldosterone (late pathway catalyzed by P-450c11AS) without a change in the other mitochondrial cytochrome P-450 enzyme activities. Adrenal cells from rats exposed to hypoxia also demonstrated a three- to fourfold decrease in P-450c11AS mRNA without a change in the other mitochondrial cytochrome P-450 enzymes mRNAs, as determined by either RT-cPCR or ISHH. We conclude that relatively short-term chronic hypoxia in rats leads to a decrease in aldosteronogenesis by decreasing the expression of the gene for the late-pathway enzyme unique to the aldosterone pathway (P-450c11AS).

Aldosterone release from adrenal cells is inhibited by reduced oxygen levels in vitro during maturation in rabbits

Hypoxia in vivo leads to a decrease in aldosterone not completely explained by extrinsic controllers of adrenal function including adrenocorticotrophic hormone, renin-angiotensin II, and K+. The dissociation of renin and aldosterone during acute hypoxia in vivo may be explained by the finding that aldosterone synthesis in adrenal cells is reversibly and specifically inhibited by decreases in O2 levels within the physiological range. The present study investigated whether the direct effect of acute decreases in O2 levels on aldosteronogenic pathway is altered during maturation. Adrenal cells (whole adrenals) were prepared from fetal (27 days gestation), neonatal (1 day), and infant (10 days) New Zealand White rabbits, and capsular cells were prepared from young (21 days) and adult (3 months) rabbits. All cells were dispersed with collagenase. Basal and cAMP-stimulated aldosterone production were assessed under two different levels of O2 (pO2 = 20.0 kPa or pO2 = 8.7 kPa). Decreased O2 levels significantly inhibited cAMP-stimulated aldosterone production in cells obtained from rabbits of all ages by 60 +/- 5% cAMP-stimulated aldosterone production was significantly lower in cells obtained from neonates and premature animals under both normoxic and reduced O2 conditions as compared with animals > or = 10 days old. Corticosterone production by cells obtained from adults and 21-day-old rabbits was unaffected by reduced O2 conditions suggesting a specific effect on the aldosterone pathway. The data demonstrate that the O2 sensitivity of the aldosterone pathway is present throughout development.

Vasopressin responses to corticotropin-releasing factor and hypertonicity after truncal vagotomy in dogs

Infusion of corticotropin-releasing factor (CRF) augments the plasma vasopressin response to infusion of hypertonic saline in conscious dogs. Furthermore, afferent vagal nerve input from the abdomen is involved in the control of vasopressin release and may be altered by CRF. The purpose of the present study was to characterize the effect of CRF on the vasopressin response to hypertonic saline and to determine if it is mediated by afferent input carried from the abdominal vagus. Conscious male dogs (n = 5) underwent infusion of isotonic saline (vehicle), CRF (10 or 20 ng.kg-1.min-1), hypertonic saline (0.2 mmol.kg-1.min-1), or the combination of CRF and hypertonic saline. Hypertonic saline increased plasma sodium from 147 +/- 1 to 153 +/- 1 meq/1 and plasma vasopressin from 2.5 +/- 0.1 to 5.8 +/- 0.4 pg/ml. CRF infusion alone had no effect on plasma vasopressin. The addition of 10 or 20 ng.kg-1.min-1 CRF augmented the vasopressin response to hypertonic saline to 7.7 +/- 1.7 and 6.9 +/- 0.3 pg/ml, respectively. Truncal vagotomy did not attenuate the vasopressin response to hypertonic saline with or without CRF infusion. We conclude that CRF augments the vasopressin response to hypertonic saline and that this effect is not mediated via afferents from the abdominal vagus.

Catecholamine and cortisol responses to lower extremity revascularization: correlation with outcome variables. Perioperative Ischemia Randomized Anesthesia Trial Study Group

OBJECTIVE

To determine whether catecholamine and cortisol secretory responses to surgery contribute to postoperative complications.

DESIGN

Prospective, randomized, case series.

SETTING

A university hospital operating suite and surgical intensive care unit.

PATIENTS

Sixty patients undergoing lower extremity vascular surgery.

INTERVENTIONS

Patients were randomized to receive either epidural anesthesia/epidural opiate analgesia (regional anesthesia) or general anesthesia/intravenous patient-controlled analgesia (general anesthesia).

MEASUREMENTS AND MAIN RESULTS

Anesthesia was managed according to a prospectively designed protocol. Hemodynamic parameters and plasma catecholamine concentrations were determined at specific intraoperative and postoperative time points. Intraoperative and postoperative urine samples were collected and analyzed for free cortisol concentrations. Outcomes evaluated were cardiac (nonfatal myocardial infarction and cardiac death) and surgical (graft occlusion). Mean arterial pressure during emergence from anesthesia and in the early postoperative period correlated positively with plasma norepinephrine concentration (p < .01). In addition, plasma catecholamine concentrations were higher in patients with postoperative hypertension. Plasma norepinephrine concentrations at the time of emergence from anesthesia and postoperatively were also higher in patients requiring repeat surgery for graft revision, thrombectomy, or amputation (p < .05). Multivariate analysis indicated that the norepinephrine concentration at the time of emergence, but not type of anesthesia, correlated with reoperation for graft occlusion, suggesting that the previously reported beneficial effect of regional anesthesia may be due to modulation of the stress response. Myocardial infarction or cardiac death occurred in three patients. These patients had markedly increased catecholamine concentrations.

CONCLUSIONS

The catecholamine response to lower extremity vascular surgery contributes to the development of postoperative hypertension and may also be important in the development of thrombotic complications.

Factitious Cushing’s Syndrome: Discovery with Use of a Sensitive Immunoradiometric Assay for Corticotropin

Factitious Cushing's syndrome is an unusual problem that may be clinically and biochemically indistinguishable from endogenous hypercortisolism. Results of biochemical studies may be misleading because of cross-reactivity of synthetic corticosteroids or their metabolites with plasma or urine cortisol. Because of its lack of specificity, radioimmunoassay (RIA) for corticotropin (adrenocorticotropic hormone or ACTH) may not show completely suppressed results in patients with surreptitious use of glucocorticoids. A new sensitive and specific immunoradiometric assay (IRMA) for ACTH demonstrates reliably suppressed levels after administration of glucocorticoids. In this report, we describe a 37-year-old woman with typical clinical and biochemical features of ACTH-dependent hypercortisolism. Metabolic evaluation had shown urinary free cortisol excretion of 7,499 nmol/day and plasma ACTH-RIA levels of 13.2 and 33.0 pmol/L on two separate occasions. The use of IRMA for the measurement of ACTH during inferior petrosal sinus sampling revealed a very low peripheral ACTH concentration (=0.4 pmol/L) and a considerably blunted response to ovine corticotropin-releasing hormone, findings that suggested ACTH-independent Cushing's syndrome. Plasma samples obtained during inferior petrosal sinus sampling were assayed for prednisolone and showed a concentration of 360 nmol/L; thus, the presence of factitious Cushing's syndrome was confirmed. Some commercial ACTH-RIA measurements may be unreliable in distinguishing ACTH-dependent from ACTH-independent hypercortisolism. ACTH-IRMA levels are low in patients with ACTH-independent Cushing's syndrome and will be helpful in identifying factitious Cushing's syndrome.

Differentiation of the expression of aldosterone synthase and 11 beta-hydroxylase mRNA in the rat adrenal cortex by reverse transcriptase-polymerase chain reaction

The adrenocortical enzymes of the steroidogenic late pathway in the rat are aldosterone synthase (P450aldo), which catalyzes the production of aldosterone, and 11 beta-hydroxylase (P45011 beta), which catalyzes the production of corticosterone throughout the cortex. These two enzymes are highly homologous and are encoded by the genes CYP11B2 and CYP11B1, respectively. The purpose of the present study is to describe the development of two sets of primers and the reverse transcription-polymerase chain reaction (RT-PCR) conditions that are capable of discriminating between rat P450aldo and P45011 beta mRNAs. The P450aldo primer set did not amplify full length cDNA P45011 beta plasmid and the P45011 beta primer set did not amplify full length cDNA P450aldo plasmid indicating minimal crosstalk. The fidelity of the PCR primers and method was further established by sequencing the PCR products and demonstration of virtual identity with the published sequences of P450aldo and P45011 beta. RT-PCR of mRNA from adrenal capsules (zona glomerulosa) and subcapsules (zona reticularis/fasciculata) from rats demonstrated no effect of sodium diet on the expression of P45011 beta mRNA but an approximately 8-fold greater expresison in P450aldo mRNA on low vs high sodium intake. Similar results were found when single hemicapsules were subjected to RT-PCR, demonstrating the sensitivity of the method. We conclude that the two sets of PCR primers and the RT-PCR method described are capable of evaluating the expression of the highly homologous mRNAs for P450aldo and P45011 beta with great precision and sensitivity.

Case report: renal phosphate wasting, syndrome of inappropriate antidiuretic hormone, and ectopic corticotropin production in small cell carcinoma

Renal phosphate wasting related to a tumor (oncogenous osteomalacia) is a rare disorder usually associated with benign mesenchymal tumors. In this article, the authors describe a man with renal phosphate wasting and the syndrome of inappropriate antidiuretic hormone associated with small cell carcinoma. Chemotherapy markedly reduced tumor burden and was associated with normalization of renal phosphate handling and serum sodium. With recurrence, renal phosphate wasting and the syndrome of inappropriate antidiuretic hormone developed again, with the additional complication of hypercortisolism secondary to ectopic corticotropin production. The authors report the rare occurrence of renal phosphate wasting with small cell carcinoma (5 previously reported cases) and the unique co-existence of this paraneoplastic syndrome with the syndrome of inappropriate antidiuretic hormone and ectopic corticotropin production.

O2 dependence of pregnenolone and aldosterone synthesis in mitochondria from bovine zona glomerulosa cells

Hypoxia in vivo results in a decrease in aldosterone not accounted for by extra-adrenal controllers. We have demonstrated that aldosteronogenesis but not cortisol synthesis in the whole cell is O2 sensitive. In the intact glomerulosa cell, this sensitivity is located in the late pathway step catalyzed by conversion of corticosterone to aldosterone (P-450aldo), whereas the early pathway catalyzed by conversion of cholesterol to pregnenolone (P-450scc) is not inhibited until PO2 is very low. Because P-450aldo and P-450scc are mitochondrial enzymes that depend on the same NADPH-specific electron transport proteins, we hypothesized that O2 sensitivity would be independent of energy production and expressed in isolated mitochondria. We measured the conversion of exogenous 25(OH)-cholesterol to pregnenolone and of exogenous corticosterone to aldosterone in the presence of cyanoketone in mitochondria isolated from bovine zona glomerulosa cells and exposed to an experimental gas (1-100% O2) vs. a room air control. Pregnenolone production was not affected until PO2 was < 35 Torr and decreased to almost nil when PO2 was < 30 Torr. In contrast, aldosterone production increased under hyperoxia and decreased under moderate decreases in O2. The conversion of corticosterone to aldosterone was maintained at approximately 50% of control, even when PO2 was < 20 Torr. The sensitivity of the aldosterone pathway to changes in O2 within the physiological range appears to reside in the mitochondrial late pathway (i.e., P-450aldo) and is not significantly influenced by cytosolic regulators of steroidogenesis or by limitation of reducing equivalents.

Intraoperative measurement of adrenocorticotropin (ACTH) during removal of ACTH-secreting bronchial carcinoid tumors

The optimal treatment for ectopic ACTH syndrome is the complete removal of the tumor secreting ACTH. These tumors are often occult, with their location suggested but not proven with imaging techniques. The intraoperative measurement of ACTH by immunoradiometric assay in five patients with the occult ectopic ACTH syndrome during removal of suspicious intrapulmonary lesions is reported. A significant ACTH gradient was detected in the pulmonary veins of the affected lobes in two patients. ACTH had decreased significantly in all five patients by 10 and 15 min after tumor removal. All five patients had histologically proven ACTH-secreting bronchial carcinoid tumors, suppressed plasma ACTH by 24 h after tumor removal, and subsequent secondary adrenal insufficiency indicating successful surgical therapy (five of five true-positive). In one patient, previous surgery was not curative and did not result in a decrease in intraoperative measurement of ACTH (one of one true-negative). It was demonstrated that a rapid ACTH immunochemiluminescence assay with a 15-min incubation time has sufficient sensitivity and precision to detect decreases in ACTH described above. These results demonstrate that complete removal of ACTH-secreting bronchial carcinoid tumors can be detected intraoperatively by a decrease in arterial ACTH by 15 min. The modification of the ACTH immunochemiluminescence assay to 15 min incubation allows the documentation of a successful tumor removal in the operating room. It may also be used to locate the tumor intraoperatively by selective pulmonary vein sampling. This protocol may be applicable to the intraoperative measurement of ACTH during pituitary microadenomectomy for Cushing's disease.

Elevated follicular fluid angiotensin II and pregnancy outcome

OBJECTIVE

To assess whether a relationship exists between follicular fluid (FF) angiotensin II (AII) concentration and pregnancy outcome or earlier fecundity parameters and whether correlations exist among FF AII concentrations and P, E2, T, androstenedione (A), or various ratios of these.

DESIGN

Retrospective study in which hormone concentrations in FF samples were measured.

SETTING

In vitro fertilization clinic-Assisted Reproductive Technology Program, Rush Medical Center.

PATIENTS

Twenty-six female patients underwent ovarian stimulation for IVF.

INTERVENTION

Leuprolide acetate was combined with hMG and FSH for ovarian stimulation.

MAIN OUTCOME MEASURE

Follicular fluid aspirates were collected and oocytes were recovered 34 to 36 hours after hCG injection. The patients proceeded to undergo IVF and ET. Follicular fluid hormones were measured using standard RIA. Angiotensin II and steroid hormone concentrations in FF were compared for pregnant versus nonpregnant women using the Student's t-test and rank-sum test. Pearson multiple-correlation analysis was performed to calculate correlation coefficients among AII concentrations and steroid concentrations in FF aspirates.

RESULTS

Mean FF concentration of AII was significantly lower in samples from women showing clinical pregnancies (112.2 +/- 13.9 pg/mL [107.3 +/- 13.3 pmol/L]) compared with samples from women who did not achieve pregnancy (217.1 +/- 23.8 pg/mL [207.5 +/- 22.7 pmol/L]) (mean +/- SE). A negative correlation was observed between FF concentrations of AII and P. Correlations of AII with E2, T, A, or with ratios of these did not show significance.

CONCLUSION

These data suggest that high AII concentration at time of oocyte recovery may indicate poor pregnancy outcome in women undergoing ovarian stimulation for IVF. These data corroborate previous results in animal models showing that AII predisposes follicles to undergo atresia-like conditions.

The catecholamine, cortisol, and hemodynamic responses to mild perioperative hypothermia. A randomized clinical trial

BACKGROUND

Unintended hypothermia occurs frequently during surgery and may have adverse effects on the cardiovascular system. Although the mechanisms responsible for the cardiovascular manifestations of hypothermia are unclear, it is possible that they are sympathetically mediated. In this prospective study, relationships between body temperature, the neuroendocrine response, and hemodynamic changes in the perioperative period were examined.

METHODS

Seventy-four elderly patients, undergoing abdominal, thoracic, or lower extremity vascular surgical procedures, were randomly assigned to either "routine care" (n = 37) or "forced-air warming" (n = 37) groups. Throughout the intraoperative and early postoperative periods, the routine care group received standard thermal care, and the forced-air warming group received forced-air skin-surface warming. Core temperature, forearm minus fingertip skin-surface temperature gradient, and plasma concentrations of epinephrine, norepinephrine, and cortisol were measured throughout the perioperative period, and the two groups were compared. In addition, heart rate and arterial blood pressure were compared between groups.

RESULTS

The routine care and forced-air warming groups did not differ with regard to age, sex, type of surgical procedures, anesthetic techniques, or postoperative analgesia. Mean core temperature was lower in the routine care group on admission to the postanesthetic care unit (routine care, 35.3 +/- 0.1 degree C; forced-air warming, 36.7 +/- 0.1 degree C; P = 0.0001) and remained lower during the early postoperative period. Forearm minus fingertip skin-surface temperature gradient (an index of peripheral vasoconstriction) was greater in the routine care group in the early postoperative period. The mean norepinephrine concentration (pcg/ml) was greater in the routine care group immediately after surgery (480 +/- 70 vs. 330 +/- 30, P = 0.02) and at 60 min (530 +/- 50 vs. 340 +/- 30, P = 0.002) and 180 min (500 +/- 80 vs. 320 +/- 30, P = 0.004) postoperatively. Mean epinephrine concentrations were not significantly different between groups. Mean cortisol concentrations were increased in both groups during the early postoperative period (P < 0.01), but the differences between groups were not significant. Systolic, mean, and diastolic arterial blood pressures were significantly higher in the routine care group.

CONCLUSIONS

Compared with patients in the forced-air warming group, patients receiving routine thermal care had lower core temperatures, a greater degree of peripheral vasoconstriction, higher norepinephrine concentrations, and higher arterial blood pressures in the early postoperative period. These findings suggest a possible mechanism for hypothermia-related cardiovascular morbidity in the perioperative period.

Chronic physiological increases in cortisol inhibit the vasopressin response to hypertonicity in conscious dogs

Chronic increases in cortisol inhibit basal plasma arginine vasopressin (AVP). Acute pretreatment with cortisol inhibits the large increase in AVP during hypotension or hypoxia but does not inhibit the modest increase in AVP in response to hypertonic saline (HS). We evaluated the effect of a chronic increase in cortisol (physiological range) on the acute AVP response to HS. Five male dogs received a continuous infusion of either vehicle or cortisol (65 mg/day) for 7 days. The AVP response to HS (0.2 mmol.kg-1.min-1 for 30 min) was tested before infusion, on days 1, 4, and 7 of chronic infusion, and 2 days after the infusion was discontinued. Plasma cortisol increased significantly from 1.0 +/- 0.2 micrograms/dl to an average over the 7 days of infusion of 5.0 +/- 0.2 micrograms/dl, and basal plasma AVP was significantly decreased during cortisol infusion. The increase in plasma Na and osmolality during HS was unaffected by chronic infusion. HS resulted in an increase in AVP from 3.5 +/- 0.2 to 7.1 +/- 0.7 pg/ml before cortisol infusion. After 7 days of cortisol, the AVP response to HS (from 2.6 +/- 0.1 to 3.9 +/- 0.7 pg/ml) was significantly attenuated. Sustained, physiological increases in cortisol significantly inhibited osmotically stimulated AVP release. The decrease in AVP during hypercortisolism and the syndrome of inappropriate antidiuretic hormone in patients with adrenal insufficiency appear to be due to an inhibitory effect of cortisol on the osmotic sensitivity of the AVP control system.