Blood cholesterol and hydrocortisone production in man: quantitative aspects of the utilization of circulating cholesterol by the adrenals at rest and under adrenocorticotropin stimulation

Bile acids regulate SF-1 to alter cholesterol balance in adrenocortical cells via S1PR2

Glucocorticoid synthesis typically occurs in adrenal cortex and is influenced by cholesterol balance, since cholesterol is the sole precursor of steroids. Bile acids as the signaling molecules, have been shown to promote steroidogenesis in steroidogenic cells. However, whether bile acids directly regulate cholesterol balance remains elusive. In this study, we prepared cholestatic mouse models and cultured human adrenocortical cells (H295R) treated with taurochenodeoxycholic acid (TCDCA) to determine transcription levels of cholesterol metabolism associated genes and cholesterol concentrations in adrenocortical cells. Results showed that common bile duct ligation (CBDL) and chenodeoxycholic acid (CDCA) feeding elevated the mRNA levels of Abca1, Cyp51, Hmgcr, Srb1, and Mc2r in adrenals of mice. Meanwhile, the concentrations of total cholesterol and cholesteryl ester in adrenals of CBDL and CDCA-fed mice were dramatically lowered. The total and phosphorylation levels of HSL in adrenal glands of CBDL mice were also enhanced. Similarly, TCDCA treatment in H295R cells decreased intracellular concentrations of total cholesterol and cholesteryl ester and increased transcription levels of SRB1, MC2R, and HSL as well. Inhibition of bile acids' receptor sphingosine 1-phosphate receptor 2 (S1PR2), extracellular signal-regulated kinase (ERK) phosphorylation, and steroidogenic factor 1 (SF-1) respectively successfully abolished effect of TCDCA on H295R cells. SF-1s was found to be phosphorylated at Thr75 in TCDCA-treated H295R cells. While a mild increase of intracellular cAMP concentration was detected upon TCDCA treatment, inhibition of PKA activity with Rp-Isomer in H295R cells failed to decrease the expression of SF-1 and its target genes. Our findings suggest that conjugated bile acids affect cholesterol balance through regulation of SF-1 in adrenocortical cells so as to provide an adequate cholesterol supply for glucocorticoid synthesis, which improves and enriches our understanding of the mechanism whereby bile acids regulate cholesterol balance to affect adrenal function.

MicroRNA regulation of adrenal glucocorticoid and androgen biosynthesis

Steroid hormones are derived from a common precursor molecule, cholesterol, and regulate a wide range of physiologic function including reproduction, salt balance, maintenance of secondary sexual characteristics, response to stress, neuronal function, and various metabolic processes. Among the steroids synthesized by the adrenal and gonadal tissues, adrenal mineralocorticoids, and glucocorticoids are essential for life. The process of steroidogenesis is regulated at multiple levels largely by transcriptional, posttranscriptional, translational, and posttranslational regulation of the steroidogenic enzymes (i.e., cytochrome P450s and hydroxysteroid dehydrogenases), cellular compartmentalization of the steroidogenic enzymes, and cholesterol processing and transport proteins. In recent years, small noncoding RNAs, termed microRNAs (miRNAs) have been recognized as major post-transcriptional regulators of gene expression with essential roles in numerous biological processes and disease pathologies. Although their role in the regulation of steroidogenesis is still emerging, several recent studies have contributed significantly to our understanding of the role miRNAs play in the regulation of the steroidogenic process. This chapter focuses on the recent developments in miRNA regulation of adrenal glucocorticoid and androgen production in humans and rodents.

DHCR24, a Key Enzyme of Cholesterol Synthesis, Serves as a Marker Gene of the Mouse Adrenal Gland Inner Cortex

Steroid hormones are synthesized through enzymatic reactions using cholesterol as the substrate. In steroidogenic cells, the required cholesterol for steroidogenesis can be obtained from blood circulation or synthesized de novo from acetate. One of the key enzymes that control cholesterol synthesis is 24-dehydrocholesterol reductase (encoded by DHCR24). In humans and rats, DHCR24 is highly expressed in the adrenal gland, especially in the zona fasciculata. We recently reported that DHCR24 was expressed in the mouse adrenal gland's inner cortex and also found that thyroid hormone treatment significantly upregulated the expression of Dhcr24 in the mouse adrenal gland. In the present study, we showed the cellular expression of DHCR24 in mouse adrenal glands in early postnatal stages. We found that the expression pattern of DHCR24 was similar to the X-zone marker gene 20αHSD in most developmental stages. This finding indicates that most steroidogenic adrenocortical cells in the mouse adrenal gland do not synthesize cholesterol locally. Unlike the 20αHSD-positive X-zone regresses during pregnancy, some DHCR24-positive cells remain present in parous females. Conditional knockout mice showed that the removal of Dhcr24 in steroidogenic cells did not affect the overall development of the adrenal gland or the secretion of corticosterone under acute stress. Whether DHCR24 plays a role in conditions where a continuous high amount of corticosterone production is needed requires further investigation.

Phenotype-genotype correlation in aldosterone-producing adenomas characterized by intracellular cholesterol metabolism

Aldosterone-producing adenoma (APA) is histologically composed of clear and compact tumor cells. KCNJ5- mutated APAs were reported to be associated with higher plasma aldosterone concentration and more abundant clear tumor cells containing lipid droplets than non-KCNJ5- mutated APAs. However, the association among cholesterol uptake and/or synthesis, cellular morphology and genotypes has remained unknown. Therefore, in order to explore these differences, 52 APA cases (KCNJ5 mt: n = 33, non-KCNJ5 mt: n = 19; ATP1A1: n = 3, ATP2B3: n = 3, CACNA1D: n = 5, CTNNB1: n = 1, tumors without any mutation above: n = 7), zona glomerulosa (ZG) tissue adjacent to APA and 10 non-pathological adrenal glands (NAs) were examined for quantitative histopathological analysis of tumor morphology and immunohistochemical analysis of cholesterol receptors (SR-B1, LDL-R), cholesterol metabolic enzymes (ACAT1, ACAT2, HSL, DHCR24, StAR), and the enzymes required for steroid synthesis (CYP11A1, CYP17A, 3βHSD, CYP11B1, CYP11B2). Gas chromatography-mass spectrometry (GC-MS) analysis was further performed to profile cholesterol precursors and metabolites in 21 APA cases (KCNJ5 mt: n = 16, non-KCNJ5 mt: n = 5) and 14 adrenal cortex of adjacent adrenal tissues. Results demonstrated that both SR-B1 and DHCR24 were significantly lower in the ZG than in fasciculata or reticularis of NAs but LDL-R was not significantly different among them in immunohistochemical analysis. SR-B1 and DHCR24 were both significantly higher in APAs than in ZG tissue adjacent to APA. In GC-MS analysis, most cholesterol precursors and metabolites, except for lanosterol, and their metabolic ratios (= concentration of cholesterol/ precursor) were higher in APAs than in the adjacent adrenal cortex tissue. LDL-R, ACAT1/2, HSL, DHCR24 were all significantly lower in clear than in compact tumor cells of APA. LDL-R was significantly lower and cholesterol/lanosterol ratio was significantly higher in KCNJ5- mutated than non-KCNJ5- mutated APAs. We demonstrated SR-B1 mediated selective uptake of cholesterol ester and de novo cholesterol synthesis were both enhanced in APAs. In addition, cholesterol uptake and metabolism were different between clear and compact tumor cells. KCNJ5- mutated APAs were predominantly composed of clear tumor cells containing abundant cholesteryl ester but less activated LDL-R mediated uptake and increased de novo synthesis. Those findings above indicated their more pronounced functional deviation from the normal ZG cells in terms of their steroidogenic and intracellular cholesterol metabolism.

Integration of Distinct Analysis Strategies Improves Tissue-Trait Association Identification

Integrating genome-wide association studies (GWAS) with transcriptomic data, human complex traits and diseases have been linked to relevant tissues and cell types using different methods. However, different results from these methods generated confusion while no gold standard is currently accepted, making it difficult to evaluate the discoveries. Here, applying three methods on the same data source, we estimated the sensitivity and specificity of these methods in the absence of a gold standard. We established a more specific tissue-trait association atlas by combining the information captured by different methods. Our triangulation strategy improves the performance of existing methods in establishing tissue-trait associations. The results provide better etiological and functional insights for the tissues underlying different human complex traits and diseases.

The Many Roles of Cholesterol in Sepsis: A Review

RATIONALE

The biological functions of cholesterol are diverse, ranging from cell membrane integrity and signalling, immunity, to the synthesis of steroid and sex hormones, Vitamin D, bile acids and oxysterols. Multiple studies have demonstrated hypocholesterolemia in sepsis, the degree of which is an excellent prognosticator of poor outcomes. However, the clinical significance of hypocholesterolemia has been largely unrecognized.

OBJECTIVES/METHODS

We undertook a detailed review of the biological roles of cholesterol, the impact of sepsis, its reliability as a prognosticator in sepsis, and the potential utility of cholesterol as a treatment.

MEASUREMENTS AND MAIN RESULTS

Sepsis affects cholesterol synthesis, transport and metabolism. This likely impacts upon its biological functions including immunity, hormone and vitamin production, and cell membrane receptor sensitivity. Early preclinical studies show promise for cholesterol as a pleiotropic therapeutic agent.

CONCLUSIONS

Hypocholesterolemia is a frequent condition in sepsis and an important early prognosticator. Low plasma levels are associated with wider changes in cholesterol metabolism and its functional roles, and these appear to play a significant role in sepsis pathophysiology. The therapeutic impact of cholesterol elevation warrants further investigation.

Sterol and lipid analyses identifies hypolipidemia and apolipoprotein disorders in autism associated with adaptive functioning deficits

An improved understanding of sterol and lipid abnormalities in individuals with autism spectrum disorder (ASD) could lead to personalized treatment approaches. Toward this end, in blood, we identified reduced synthesis of cholesterol in families with ≥2 children with ASD participating with the Autism Genetic Resource Exchange (AGRE), as well as reduced amounts of high-density lipoprotein cholesterol (HDL), apolipoprotein A1 (ApoA1) and apolipoprotein B (ApoB), with 19.9% of the subjects presenting with apolipoprotein patterns similar to hypolipidemic clinical syndromes and 30% with either or both ApoA1 and ApoB less than the fifth centile. Subjects with levels less than the fifth centile of HDL or ApoA1 or ApoA1 + ApoB had lower adaptive functioning than other individuals with ASD, and hypocholesterolemic subjects had apolipoprotein deficits significantly divergent from either typically developing individuals participating in National Institutes of Health or the National Health and Nutrition Examination Survey III.

Period prevalence and mortality rates associated with hypocholesterolaemia in dogs and cats: 1,375 cases

To determine the period prevalence of hypocholesterolaemia and the associated mortality rates in dogs and cats at a university teaching hospital. The secondary aim was to identify disease processes associated with hypocholesterolaemia.

MATERIALS AND METHODS

Medical records over a 5-year period were reviewed to determine the severity of hypocholesterolaemia and its associated mortality rate. Medical records of animals with moderate to severe hypocholesterolaemia (<2.59 mmol/L in dogs, <1.81 mmol/L in cats) were analysed further. Animals with hospital-acquired hypocholesterolaemia were identified.

RESULTS

Among 16,977 dogs and 3,788 cats that had at least one cholesterol measurement, the period prevalence of hypocholesterolaemia was 7.0% in dogs and 4.7% in cats. The mortality rate of hypocholesteraemic dogs and cats was 12% in both species which was significantly higher than that of animals with normal serum cholesterol. The degree of hypocholesterolaemia was significantly associated with mortality. Dogs, but not cats, with hospital-acquired hypocholesterolaemia had a higher mortality rate than those presenting with hypocholesterolaemia. Disease of hepatic, gastrointestinal and lymphoreticular systems were most commonly associated with hypocholesterolaemia, and infectious and neoplastic disease were the most commonly associated pathophysiologic processes in both species. Lymphoma was over-represented in dogs with neoplasia.

CLINICAL SIGNIFICANCE

Hypocholesterolaemia is not a frequent abnormality but was associated with mortality in this study and may be a negative prognostic indicator. It is not known if hypocholesterolaemia is simply a marker for disease severity, or if it is has active physiologic effects contributing to poor outcomes.

Cholesterol delivery to the adrenal glands estimated by adrenal venous sampling: An in vivo model to determine the contribution of circulating lipoproteins to steroidogenesis in humans

BACKGROUND

Cholesterol, required for adrenal steroid hormone synthesis, is at least in part derived from circulating lipoproteins. The contribution of high-density lipoproteins (HDL) and low-density lipoproteins (LDL) to adrenal steroidogenesis in humans is unclear.

OBJECTIVE

The aim of the study was to determine the extent to which HDL and LDL are taken up by the adrenal glands using samples obtained during adrenal venous sampling (AVS).

METHODS

AVS was successfully performed in 23 patients with primary aldosteronism. Samples were drawn from both adrenal veins and inferior vena cava (IVC). HDL cholesterol (HDL-C) and lipoprotein particle profiles were determined by nuclear magnetic resonance spectroscopy. Apolipoprotein (apo) A-I and apoB were assayed by immunoturbidimetry.

RESULTS

Plasma HDL-C and HDL and LDL particle concentrations (HDL-P and LDL-P) were not lower in samples obtained from the adrenal veins compared with the IVC (HDL-C, P = .59; HDL-P, P = .06; LDL-P, P = .93). ApoB was lower in adrenal venous plasma than in IVC (P = .026; P < .05 for right adrenal vein). In 13 patients with an aldosterone producing adenoma (APA), apoB was also lower (P = .045) and LDL-P tended to be lower (P = .065) in the APA adrenal vein compared with the IVC. ApoA-I was not lower in adrenal venous plasma compared with the IVC, neither in the whole group (P = .20) nor in the APA subgroup (P = .075).

CONCLUSION

These in vivo observations suggest that circulating LDL may contribute to adrenal steroidogenesis in humans as inferred from adrenal venous-IVC apoB concentration differences. AVS is a feasible method to investigate the relationships between lipoproteins and steroidogenesis.

High-density lipoproteins and adrenal steroidogenesis: A population-based study

BACKGROUND

Cholesterol trafficked within plasma lipoproteins, in particular high-density lipoproteins (HDL), may represent an important source of cholesterol that is required for adrenal steroidogenesis. Based on a urinary gas chromatography method, compromised adrenal function has been suggested in men but not in women with (genetically determined) low plasma HDL-cholesterol (HDL-C).

OBJECTIVE

The objective of the article was to examine the extent to which glucocorticoid production relates to HDL-C in a population-based cohort.

METHODS

A total of 240 subjects (120 men and 120 women, aged 20-79 years) without relevant comorbidities were recruited from the general population. Glucocorticoid metabolites were measured by gas chromatography with tandem mass spectrometric detection in 24-hour urine collections to estimate total glucocorticoid production (TGP). Fasting plasma (apo)lipoproteins were assayed by routine methods.

RESULTS

TGP was not decreased but tended to be increased in subjects with low HDL-C (NCEP-ATPIII criteria; P = .094). In univariate analysis, TPG was correlated inversely with HDL-C (r = -0.353, P < .001) and apoA-I (r = -0.263, P = .01). Multivariable linear regression analysis demonstrated that TGP was still inversely related to HDL-C (β = -0.145, P = .019) or alternatively to low HDL-C (β = -0.129, P = .013) taking age, sex, current smoking, and other metabolic syndrome components into account.

CONCLUSION

In this population-based study, urinary glucocorticoid metabolite excretion was inversely associated with HDL-C. We found no evidence for an attenuated adrenal function in men and women with low HDL-C.

Role of steroid sulfatase in steroid homeostasis and characterization of the sulfated steroid pathway: Evidence from steroid sulfatase deficiency

The impact of steroid sulfatase (STS) activity in the circulating levels of both sulfated and unconjugated steroids is only partially known. In addition, the sulfated steroid pathway, a parallel pathway to the one for unconjugated steroids, which uses the same enzymes, has never been characterized in detail before. Patients with steroid sulfatase deficiency (STSD) are unable to enzymatically convert sulfated steroids into their unconjugated forms, and are a good model to elucidate how STS affects steroid biosynthesis and to study the metabolism of sulfated steroids. We quantified unconjugated and sulfated steroids in STSD serum, and compared these results with data obtained from serum of healthy controls. Most sulfated steroids were increased in STSD. However, androstenediol-3-sulfate and epiandrosterone sulfate showed similar levels in both groups, and the concentrations of androsterone sulfate were notably lower. Hydroxylated forms of DHEAS and of pregnenolone sulfate were found to be increased in STSD, suggesting a mechanism to improve the excretion of sulfated steroids. STSD testosterone concentrations were normal, but cholesterol and DHEA were significantly decreased. Additionally, serum bile acids were three-fold higher in STSD. Correlations between concentrations of steroids in each group indicate that 17α-hydroxy-pregnenolone-3-sulfate in men is mainly biosynthesized from the precursor pregnenolone sulfate and androstenediol-3-sulfate from DHEAS. These findings confirm the coexistence of two steroidogenic pathways: one for unconjugated steroids and another one for sulfated steroids. Each pathway is responsible for the synthesis of specific steroids. The equal levels of testosterone, and the reduced level of unconjugated precursors in STSD, support that testosterone is primarily synthesized from sulfated steroids. In consequence, testosterone synthesis in STSD relies on an enzyme with sulfatase activity other than STS. This study reveals that STS is a key player of steroid biosynthesis regulating the availability of circulating cholesterol.

Cholesterol Biosynthesis and Trafficking in Cortisol-Producing Lesions of the Adrenal Cortex

CONTEXT

Cortisol-producing adenomas (CPAs), primary pigmented nodular adrenocortical disease (PPNAD), and primary macronodular adrenocortical hyperplasia (PMAH) cause ACTH-independent Cushing syndrome (CS). Investigation of their pathogenesis has demonstrated their integral link to the cAMP-dependent protein kinase signaling pathway.

OBJECTIVE

The aim of this study was to identify differences in cholesterol biosynthesis among different CS-causing adrenocortical tumors. Because of the concomitant associations of cAMP levels with cholesterol and with steroid biosynthesis, we hypothesized that benign cortisol-producing tumors would display aberration of these pathways.

DESIGN AND SETTING

Twenty-three patients with CPA, PPNAD, or PMAH who underwent adrenalectomy for CS were included in the study. Preoperative biochemical analyses were performed, and excised adrenal tissues were studied.

MAIN OUTCOME MEASURES

Serum, urinary hormone levels, serum lipid profiles, and anthropometric data were obtained preoperatively. Adrenal tissues were analyzed for total protein, cholesterol, and neutral sterol content by mass spectrometry and expression of HMGCR, LDLR, ABCA1, DHCR24, and STAR genes.

RESULTS

There were differences in cholesterol content and markers of cholesterol biosynthesis and metabolism that distinguished CPAs from PMAH and PPNAD; cholesterol, lathosterol, and lathosterol/cholesterol ratio were significantly higher in CPAs. ABCA1 mRNA was lower among CPAs compared to tissues from bilateral adrenocortical hyperplasia (PMAH and PPNAD), and mRNA expression of LDL-R, DCHR24, and HMGCR tended to be higher in CPA tumor tissues.

CONCLUSION

CPAs displayed characteristics of "cholesterol-starved" tissues when compared to PPNAD and PMAH and appeared to have increased intrinsic cholesterol production and uptake from the periphery, as well as decreased cholesterol efflux. This has implications for a potential new way of treating these tumors.

Genetic alterations affecting cholesterol metabolism and human fertility

Single nucleotide polymorphisms (SNPs) represent genetic variations among individuals in a population. In medicine, these small variations in the DNA sequence may significantly impact an individual's response to certain drugs or influence the risk of developing certain diseases. In the field of reproductive medicine, a significant amount of research has been devoted to identifying polymorphisms which may impact steroidogenesis and fertility. This review discusses current understanding of the effects of genetic variations in cholesterol metabolic pathways on human fertility that bridge novel linkages between cholesterol metabolism and reproductive health. For example, the role of the low-density lipoprotein receptor (LDLR) in cellular metabolism and human reproduction has been well studied, whereas there is now an emerging body of research on the role of the high-density lipoprotein (HDL) receptor scavenger receptor class B type I (SR-BI) in human lipid metabolism and female reproduction. Identifying and understanding how polymorphisms in the SCARB1 gene or other genes related to lipid metabolism impact human physiology is essential and will play a major role in the development of personalized medicine for improved diagnosis and treatment of infertility.

Adrenal Function in females with low plasma HDL-C due to mutations in ABCA1 and LCAT

INTRODUCTION

Adrenal steroidogenesis is essential for human survival and depends on the availability of the precursor cholesterol. Male subjects with low plasma levels of high density lipoprotein (HDL) cholesterol are characterized by decreased adrenal function. Whether this is also the case in female subjects with low plasma HDL-C levels is unresolved to date.

FINDINGS

15 female ATP binding cassette transporter AI (ABCAI) and 14 female lecithin-cholesterol acyltransferase (LCAT) were included in the study. HDL-C levels were 38% and 41% lower in ABCA1 and LCAT mutation carriers compared to controls, respectively. Urinary steroid excretion of 17-ketogenic steroids or 17-hydroxy corticosteroids did not differ between 15 female ABCA1 mutation carriers (p = 0.27 vs 0.30 respectively) and 30 matched normolipidemic controls or between 14 female LCAT mutation carriers and 28 matched normolipidemic controls (p = 0.10 and 0.14, respectively). Cosyntropin testing in an unselected subgroup of 8 ABCA1 mutation carriers and 3 LCAT mutation carriers did not reveal differences between carriers and controls.

CONCLUSION

Adrenal function in females with molecularly defined low HDL-C levels is not different from controls. The discrepancy with the finding of impaired steroidogenesis in males with molecularly defined low HDL-C levels underscores the importance of gender specific analyses in cholesterol-related research.

Assessment of adrenal function in liver diseases

BACKGROUND

In recent times, there are reports of adrenal dysfunction in whole spectrum of liver disease. Adrenal insufficiency (AI) has been shown to correlate with progression of liver disease. Hence this study was conducted to assess adrenal function in subjects with acute liver disease (ALD), chronic liver disease (CLD) and post liver transplantation (LT).

MATERIAL AND METHODS

This study included 25 healthy controls, 25 patients of ALD, 20 subjects of CLD with Child-Pugh stage A (CLD-1) and 30 with Child-Pugh stage B or C (CLD-2), and 10 subjects with LT. All subjects were assessed clinically, biochemically and for adrenal functions.

RESULTS

AI was present in 9 (34.6%) patients with ALD, 20 (40%) patients with CLD and 4 (40%) in subjects with LT. AI was more common in CLD-2 (18 patients - 60%) than CLD-1 (2 patients - 10%). All patients with chronic liver disease had significantly lower basal cortisol (8.8±4.8, P=0.01), stimulated cortisol (18.2±6.3, P <0.00001) and incremental cortisol (9.4±4.6, P <0.00001) as compared to controls. There was increase in percentage of subjects with adrenal dysfunction with progression of liver disease as assessed by Child-Pugh staging. AI was predicted by lower levels of serum protein, serum albumin, total cholesterol and HDL cholesterol and higher levels of serum bilirubin and INR. Adrenal functions showed recovery following liver transplantation.

CONCLUSIONS

AI forms important part of spectrum of acute and chronic liver disease. Deterioration of synthetic functions of liver disease predicts presence of AI, and these patients should be evaluated for adrenal dysfunction periodically.

High density lipoprotein as a source of cholesterol for adrenal steroidogenesis: a study in individuals with low plasma HDL-C

Few studies have addressed the delivery of lipoprotein-derived cholesterol to the adrenals for steroid production in humans. While there is evidence against a role for low-density lipoprotein (LDL), it is unresolved whether high density lipoprotein (HDL) contributes to adrenal steroidogenesis. To study this, steroid hormone profiles in urine were assessed in male subjects suffering from functional mutations in ATP binding cassette transporter A1 (ABCA1) (n = 24), lecithin:cholesterol acyltransferase (LCAT) (n = 40), as well as in 11 subjects with low HDL cholesterol (HDL-C) without ABCA1/LCAT mutations. HDL-C levels were 39% lower in the ABCA1, LCAT, and low HDL-C groups compared with controls (all P < 0.001). In all groups with low HDL-C levels, urinary excretion of 17-ketogenic steroids was reduced by 33%, 27%, and 32% compared with controls (all P < 0.04). In seven carriers of either type of mutation, adrenocorticotropic hormone (ACTH) stimulation did not reveal differences from normolipidemic controls. In conclusion, this study shows that basal but not stimulated corticosteroid metabolism is attenuated in subjects with low HDL-C, irrespective of its molecular origin. These findings lend support to a role for HDL as a cholesterol donor for basal adrenal steroidogenesis in humans.

Are apolipoprotein E alleles correlated with semen quality?

Apolipoproteins have a unique role in lipoprotein metabolism regulation, aiding lipid transport and acting as a cofactor of the enzymes involved in metabolism. There are three co-dominant alleles, APOE*2, APOE*3 and APOE*4, which encode three protein isoforms, apoE2, apoE3 and apoE4. APOE*3 is the most frequent in all populations thus far investigated, ranging from 50 to 90%. Some studies have tried to resolve a genetic 'dilemma' by evaluating the cause of the frequency and survival of the three alleles. Genetic drift, migration or natural selection could explain the current distribution of APOE gene frequencies worldwide. If APOE*4 is the ancestral allele, APOE*3 must have offered a considerable selective advantage, perhaps consisting of a positive effect during the reproductive period. Given this, there is a need to understand if APOE gene polymorphism might affect reproductive capacity. Few studies have been conducted in this area, and they generally correlate APOE polymorphism with reproductive efficiency in terms of number of children. The aim of our study was to look for correlations between APOE polymorphism in humans and semen quality, to establish if APOE genotypes have any demonstrable effect on spermatogenesis. In conclusion, our data show that APOE polymorphism is not associated with semen quality, as it is present to a similar extent in both normal and impaired or absent spermatogenesis. This demonstrates once again that the use of number of children as an index of fertility is not indicative of real male reproductive capacity.

High density lipoprotein in patients with liver failure; relation to sepsis, adrenal function and outcome of illness

BACKGROUND AND AIMS

High density lipoprotein (HDL) plays an important role in the transport of cholesterol to the adrenal gland for steroidogenesis and may have actions that modulate response to infection and critical illness. The clinical relevance of HDL level in patients with liver failure remains poorly characterised.

METHODS

In 164 critically-ill patients with acute (ALF) and acute on chronic liver failure (AOCLF) we evaluated the relationship between HDL levels measured on admission to intensive care unit (ICU) and survival, predisposition to sepsis and adrenocortical function assessed through the cortisol response to short synacthen testing (SST).

RESULTS

In acute liver failure and acute on chronic liver failure, high density lipoprotein levels were significantly lower in non-survivors (P < 0.01). Levels correlated closely with biochemical markers of liver function and the duration of liver failure. However, predictive accuracy was not superior to conventional markers and on multi-variate analysis did not show independent association with survival. Low HDL concentration was not associated with an increased incidence of sepsis either precipitating or complicating ICU admission. Evidence of adrenocortical insufficiency was present in more than half of patients undergoing SST and HDL level but not other lipid parameters correlated closely with cortisol increment after SST (r = 0.364, P < 0.0001).

CONCLUSIONS

High density lipoprotein levels are low in patients with liver failure and reflect its severity. Levels are lower in non-survivors but do not offer an advantage as early indicators of prognosis over conventional markers. No evidence of a major predisposing role for infection was found, but findings suggest a close link to adrenal function.

Assessment of adrenal function in cirrhotic patients: salivary cortisol should be preferred

BACKGROUND & AIMS

Adrenal insufficiency is a common disorder among cirrhotic patients. Adrenal function is usually assessed with serum total cortisol assays. Free cortisol (active fraction) represents only 10% of serum total cortisol, the remaining 90% being linked to cortisol-binding globulin (CBG) and albumin. In cirrhotic patients, the synthesis of these proteins is reduced, which could lead to an overestimation of the prevalence of adrenal insufficiency. Salivary cortisol assessment adequately reflects free cortisol plasma concentration. However, this method has never been validated in cirrhotic patients. The objectives of this report were to assess the following parameters by a prospective observational study: (1) correlation between salivary, serum total and free cortisol, (2) adrenal insufficiency prevalence using salivary and serum assays, (3) parameters associated with a discrepancy between both tests, and (4) adrenal insufficiency risk factors among cirrhotic patients.

METHODS

Salivary and serum total cortisol were assessed before and 1h following an injection of corticotropin (250 microg) in patients hospitalized for cirrhosis complications without shock. CBG was measured and free cortisol was assessed by the Coolens formula.

RESULTS

Eighty-eight patients were included in the study (Child-Pugh C: 68.2%). Free cortisol was more strongly correlated with salivary than with serum total cortisol (Spearman coefficient=0.91 vs. 0.76, respectively, p<0.001). Among included patients, 9.1% had adrenal insufficiency according to salivary cortisol and 33.0% had adrenal insufficiency according to serum total cortisol (p=0.001). Hypoalbuminemia was the only factor associated with a discrepancy between the results of both tests. Adrenal insufficiency risk factors were ascites and low HDL-cholesterol plasma concentration.

CONCLUSION

Using serum total cortisol assays overstate adrenal insufficiency prevalence among cirrhotic patients, mainly because of inaccurate concentrations related to hypoalbuminemia. Salivary cortisol assays should be preferably used in these patients.

A multi-center, open label, crossover designed prospective study evaluating the effects of lipid lowering treatment on steroid synthesis in patients with Type 2 diabetes (MODEST Study)

OBJECTIVE

It has been suggested that lipid-lowering treatment with the use of statins adversely affects the steroid hormones. However, the safety of lipid lowering treatment targeting very low levels of LDL with respect to the steroid hormones has not been established.

RESEARCH DESIGN AND METHODS

A prospective, randomized, multicenter trial was conducted involving 98 patients. The patients were randomized into 2 groups: group-I received 10 mg of atorvastatin plus 10 mg of ezetimibe and group-II 80 mg of atorvastatin for the first 3 months. After crossover, the first group received 80 mg of atorvastatin and the second group 10 mg of atorvastatin plus 10 mg of ezetimibe for the following 3 months. Cortisol, DHEAS, testosterone, and estradiol levels were measured at the enrollment and at the end of the 1st, 2nd, 3rd, and 6th months.

RESULTS

Along with a decrease in LDL level, the levels of DHEAS, testosterone, and estradiol decreased in both groups (p<0.001). While cortisol levels were maintained in the group given 10 mg of atorvastatin plus 10 mg of ezetimibe, it decreased significantly after the crossover to 80 mg of atorvastatin (p<0.001). The group initially given 80 mg of atorvastatin measured a lower level of cortisol for the first 3 months and it returned to normal levels after switching to 10 mg of atorvastatin plus 10 mg of ezetimibe.

CONCLUSION

Eighty milligrams of atorvastatin decreased all adrenal and gonadal steroids, whereas 10 mg of ezetimibe combined with 10 mg of atorvastatin had at least no impact on cortisol levels.

Critical illness-related corticosteroid insufficiency

The diagnosis of adrenal failure and the indications for corticosteroid therapy in critically ill patients are controversial. This controversy is fueled by the complexity of the issues and the paucity of data from high quality clinical trials. Nevertheless, while the use of high-dose corticosteroids in patients with severe sepsis and ARDS failed to improve outcome and was associated with increased complications, an extended course of stress-dose corticosteroids has been reported to increase the occurrence of ventilator-free days and survival in select groups of ICU patients. These patients typically have an exaggerated proinflammatory response. Until recently the exaggerated proinflammatory response that characterizes critically ill patients with systemic inflammation has focused on suppression of the hypothalamic-pituitary-adrenal axis and adrenal failure. However, experimental and clinical data suggest that glucocorticoid tissue resistance may also play an important role. This complex syndrome is referred to as critical illness-related corticosteroid insufficiency (CIRCI) and is defined as inadequate corticosteroid activity for the severity of the illness of a patient. The paper reviews cortisol physiology, CIRCI, and the role of corticosteroid therapy in critically ill patients.

Effect of very low LDL-cholesterol on cortisol synthesis

BACKGROUND

Cardiovascular disease is the most common cause of mortality around the world. The relationship between coronary artery disease and serum LDL-cholesterol levels has become obvious in recent years and statin treatment has been used more commonly. However, influence of intensive statin treatment on steroidal hormonal functions has remained unclear. In this paper, we evaluated the effect of very low LDL levels (<70 mg/dl) on serum cortisol concentrations, which is mainly synthesized from cholesterol.

SUBJECTS AND METHODS

Forty-one patients with serum LDL-cholesterol levels below 70 mg/dl were included in the study. The control group consisted of 38 healthy people. Adrenal axis was evaluated by means of cortisol response to 1 microg ACTH test.

RESULTS

The mean age of patients was 52.45+/-10.74 yr. Of 41 patients, 19 (46.9%) were female. There were statistically significant differences between the study and control group according to their serum cholesterol and LDL levels. Main serum LDL levels were 58+/-11.4 mg/dl and 131+/-25.8 mg/dl in the study and control group, respectively. There were no statistically significant differences in response to 1 microg ACTH stimulation test at basal, 30 min and 60 min among both study and control group. Atorvastatin treatment was generally well tolerated.

CONCLUSIONS

Our data reflect that having serum LDL-cholesterol levels below 70 mg/dl did not affect the adrenal axis function in terms of cortisol.

Prevalence and risk factors for delayed adrenal insufficiency after liver transplantation

Liver transplantation (LT) recipients are at risk for early and delayed adrenal insufficiency for multiple reasons. Although early adrenal insufficiency is known to occur in a high proportion of recipients maintained on steroid-free immunosuppressive regimens, the prevalence and risk factors associated with delayed functional adrenal gland atrophy (FAGA) are unknown because routine evaluation for this condition is not standard practice among LT centers. We investigated a group of 87 patients (64 males) transplanted for end-stage liver disease related to different etiologies. All underwent a standard corticotropin stimulation test (CST) when, after gradual steroid tapering, they had been maintained for at least 1 week on oral prednisone at a daily dose of 5 mg. FAGA, defined by a serum cortisol concentration that, 60 minutes after corticotropin administration, did not double the baseline level and remained <20 mug/dL, was diagnosed in 23/87 patients (26.4%). Stepwise logistic regression analysis selected as significant predictors of FAGA the cumulative dosage of corticosteroids administered (P < 0.01), the increase in the body mass index after LT (P < 0.01), a low serum cholesterol concentration (P = 0.005), and a high adrenocorticotropin hormone (ACTH) serum level (P < 0.05) at the time CST was performed. In conclusion, FAGA is a common condition among LT recipients who are maintained on prolonged corticosteroid immunosuppressive treatment. Factors associated with FAGA include the cumulative steroid dose, weight changes after LT, and ACTH and cholesterol levels at the time of steroid withdrawal.

Recommendations for the diagnosis and management of corticosteroid insufficiency in critically ill adult patients: consensus statements from an international task force by the American College of Critical Care Medicine

OBJECTIVE

To develop consensus statements for the diagnosis and management of corticosteroid insufficiency in critically ill adult patients.

PARTICIPANTS

A multidisciplinary, multispecialty task force of experts in critical care medicine was convened from the membership of the Society of Critical Care Medicine and the European Society of Intensive Care Medicine. In addition, international experts in endocrinology were invited to participate.

DESIGN/METHODS

The task force members reviewed published literature and provided expert opinion from which the consensus was derived. The consensus statements were developed using a modified Delphi methodology. The strength of each recommendation was quantified using the Modified GRADE system, which classifies recommendations as strong (grade 1) or weak (grade 2) and the quality of evidence as high (grade A), moderate (grade B), or low (grade C) based on factors that include the study design, the consistency of the results, and the directness of the evidence.

RESULTS

The task force coined the term critical illness-related corticosteroid insufficiency to describe the dysfunction of the hypothalamic-pituitary-adrenal axis that occurs during critical illness. Critical illness-related corticosteroid insufficiency is caused by adrenal insufficiency together with tissue corticosteroid resistance and is characterized by an exaggerated and protracted proinflammatory response. Critical illness-related corticosteroid insufficiency should be suspected in hypotensive patients who have responded poorly to fluids and vasopressor agents, particularly in the setting of sepsis. At this time, the diagnosis of tissue corticosteroid resistance remains problematic. Adrenal insufficiency in critically ill patients is best made by a delta total serum cortisol of < 9 microg/dL after adrenocorticotrophic hormone (250 microg) administration or a random total cortisol of < 10 microg/dL. The benefit of treatment with glucocorticoids at this time seems to be limited to patients with vasopressor-dependent septic shock and patients with early severe acute respiratory distress syndrome (PaO2/FiO2 of < 200 and within 14 days of onset). The adrenocorticotrophic hormone stimulation test should not be used to identify those patients with septic shock or acute respiratory distress syndrome who should receive glucocorticoids. Hydrocortisone in a dose of 200 mg/day in four divided doses or as a continuous infusion in a dose of 240 mg/day (10 mg/hr) for > or = 7 days is recommended for septic shock. Methylprednisolone in a dose of 1 mg x kg(-1) x day(-1) for > or = 14 days is recommended in patients with severe early acute respiratory distress syndrome. Glucocorticoids should be weaned and not stopped abruptly. Reinstitution of treatment should be considered with recurrence of signs of sepsis, hypotension, or worsening oxygenation. Dexamethasone is not recommended to treat critical illness-related corticosteroid insufficiency. The role of glucocorticoids in the management of patients with community-acquired pneumonia, liver failure, pancreatitis, those undergoing cardiac surgery, and other groups of critically ill patients requires further investigation.

CONCLUSION

Evidence-linked consensus statements with regard to the diagnosis and management of corticosteroid deficiency in critically ill patients have been developed by a multidisciplinary, multispecialty task force.

Mechanisms and clinical consequences of critical illness associated adrenal insufficiency

PURPOSE OF REVIEW

Adrenal insufficiency is being diagnosed with increasing frequency in critically ill patients. There exists, however, much controversy in the literature as to the nature of this entity, including its pathophysiology, epidemiology, diagnosis and treatment. The review summarizes our current understanding of the causes and consequences of adrenal insufficiency in critically ill patients.

RELEVANT FINDINGS

Activation of the hypothalamic-pituitary-adrenal axis with the production of cortisol is a fundamental component of the stress response and is essential for survival of the host. Dysfunction of the hypothalamic-pituitary-adrenal axis with decreased glucocorticoid activity is being increasingly recognized in critically ill patients, particularly those with sepsis. This condition is best referred to as 'critical illness-related corticosteroid insufficiency'. Critical illness-related corticosteroid insufficiency may occur due to dysfunction at any point in the hypothalamic-pituitary-adrenal axis including tissue glucocorticoid resistance. Critical illness-related corticosteroid insufficiency leads to an exaggerated proinflammatory response with increased tissue injury and organ dysfunction.

SUMMARY

Critical illness-related corticosteroid insufficiency is common in critically ill patients, particularly those with sepsis. Supplemental corticosteroids may restore the balance between the pro-and anti-inflammatory mediators in patients with severe sepsis, septic shock and acute respiratory distress syndrome, and thereby improve the outcome of patients with these conditions.

Is lipid lowering treatment aiming for very low LDL levels safe in terms of the synthesis of steroid hormones?

Today atherosclerotic diseases are among the most important causes of death in the world. Epidemiological, clinical, genetic, experimental and pathological studies have clearly shown the role of lipoproteins in atherosclerosis. LDL is the major atherogenic lipoprotein and has been defined as the primary target of lipid lowering treatment by NCEP. Although the level of LDL, the primary target in the treatment of dyslipidemia, has been set as below 100 mg/dl in coronary heart diseases (CHD) and CHD risk equivalents, this level has been pulled down to below 70 mg/dl for the group defined as very high risk group by the ATP (Adult Treatment Panel) guide that has been updated following the new clinical studies. As we already know, cholesterol is the precursor of glucocorticoids, mineralocorticoids and sex steroids, besides being a structural component of the cell membrane. Both adrenal and non-adrenal (ovarian+testicular) all steroid hormones are primarily synthesized using the LDL-cholesterol in the circulation. In addition to this, there is 'de novo' cholesterol synthesis in both the adrenals and gonads controlled by the HMG-CoA reductase enzyme. A third pathway, which under normal circumstances has little contribution as compared to the first two, is the use of circulatory HDL-cholesterol by the adrenal and gonadal tissues for the synthesis of steroids. Our knowledge on extremely lowered LDL levels is quite limited. However, since statins both decrease circulatory LDL and inhibit de novo cholesterol synthesis, they are likely to affect the synthesis of steroid hormones.

Attenuated corticosterone response to chronic ACTH stimulation in hepatic lipase-deficient mice: evidence for a role for hepatic lipase in adrenal physiology

Hepatic lipase (HL), a liver-expressed lipolytic enzyme, hydrolyzes triglycerides and phospholipids in lipoproteins and promotes cholesterol delivery through receptor-mediated whole particle and selective cholesterol uptake. HL activity also occurs in the adrenal glands, which utilize lipoprotein cholesterol to synthesize glucocorticoids in response to pituitary ACTH. It is likely that the role of adrenal HL is to facilitate delivery of exogenous cholesterol for glucocorticoid synthesis. On this basis, we hypothesized that HL deficiency would blunt the glucocorticoid response to ACTH. Furthermore, because exogenous cholesterol also is derived from the LDL receptor (LDLR) pathway, we hypothesized that LDLR deficiency would blunt the response to ACTH. To test these hypotheses, we compared the corticosterone response to eight daily ACTH injections in HL-deficient (hl-/-), LDLR-deficient (Ldlr-/-), and HL- and LDLR-doubly deficient (Ldlr-/- hl-/-) mice with that in wild-type (WT) mice. Plasma corticosterone levels were measured on days 2, 5, and 8. Differences in plasma corticosterone levels between genotypes were analyzed by Kruskal-Wallis one-way ANOVA on ranks and pairwise multiple comparisons by Dunn's test. Our results demonstrate a trend toward reductions in plasma corticosterone levels on day 2 and significant reductions on day 5 and day 8 in the knockout models. Thus, on day 5, plasma corticosterone levels were reduced by 57, 70, and 73% (all P < 0.05) and on day 8 by 76, 59, and 63% (all P < 0.05) in hl-/-, Ldlr-/-, and Ldlr-/- hl-/- mice, respectively. These results demonstrate that HL deficiency, like LDLR deficiency, blunts the adrenal response to chronic ACTH stimulation and suggest a novel role for HL in adrenal physiology.

Adrenal-exhaustion syndrome in patients with liver disease

OBJECTIVE

Adrenal failure is emerging as an important cause of excess morbidity and mortality in critically ill patients. We have recently reported the high incidence of adrenal failure in patients with liver disease, the so called "hepato-adrenal syndrome." It has been noted that patients who on initial testing may have "normal" adrenal function subsequently progress to overt adrenal failure, the adrenal-exhaustion syndrome. The goal of this study was to further characterize this syndrome.

DESIGN

Retrospective review of the "Hepatic Cortisol Research and Adrenal Pathophysiology Study" database.

SETTING

Liver transplant ICU of a tertiary care university hospital.

PATIENTS AND METHODS

Patients who on initial testing had "normal" adrenal function were followed, and adrenal function testing was repeated in those who failed to improve. The patients were grouped as follows: (1) patients who developed adrenal failure on follow-up testing; and (2) patients who had normal adrenal function during their ICU stay. The incidence and risk factors for the development of adrenal-exhaustion syndrome were determined.

MEASUREMENTS AND RESULTS

The study cohort consisted of 221 patients, of whom 120 (54%) were diagnosed with adrenal insufficiency on initial diagnostic testing and were excluded from further analysis. The remaining 101 patients comprised those who made up the group of interest. On follow-up, 16 (16%) of these developed adrenal failure a mean of 3 days after initial testing. The only factor that predicted the development of adrenal-exhaustion syndrome was a low HDL level (p<0.001).

CONCLUSION

This study demonstrates that adrenal failure is a dynamic process and that repeat adrenal function testing is indicated in patients who remain hemodynamically unstable or fail to improve with aggressive supportive treatment. Low HDL levels may be pathogenetically linked to the development of adrenal failure.

Dyslipidemia in the Critically Ill

Total and HDL cholesterol levels fall at the onset of acute illness and the cholesterol levels normalize as the patient recovers. Hypocholesterolemia may predispose the critically ill patient to sepsis and adrenal failure. Early enteral nutrition and tight glycemic control accelerate the recovery of the cholesterol levels.

The hepatoadrenal syndrome: a common yet unrecognized clinical condition

OBJECTIVE

Adrenal failure is common in critically ill patients, particularly those with sepsis. As liver failure and sepsis are both associated with increased circulating levels of endotoxin and proinflammatory mediators and reduced levels of apoprotein-1/high-density lipoprotein, we postulated that adrenal failure may be common in patients with liver disease.

DESIGN

Clinical study.

SETTING

Liver transplant intensive care unit.

PATIENTS

The study cohort included 340 patients with liver disease.

INTERVENTIONS

Based on preliminary observational data, all patients admitted to our 28-bed liver transplant intensive care unit (LTICU) undergo adrenal function testing. An honest broker system was used to extract clinical, hemodynamic, medication, and laboratory data on patients admitted to the LTICU from March 2002 to March 2004. A random (stress) cortisol level <20 microg/dL in a highly stressed patient (respiratory failure, hypotension) was used to diagnose adrenal insufficiency. In all other patients, a random cortisol level <15 microg/dL or a 30-min level <20 microg/dL post-low-dose (1 microg) cosyntropin was considered diagnostic of adrenal insufficiency. Patients were grouped as follows: a) chronic liver failure; b) fulminant hepatic failure; c) patients immediately status post-orthotopic liver transplantation receiving a steroid-free protocol of immunosuppression; and d) patients status post-remote liver transplant (>/=6 months). The decision to treat patients with stress doses of hydrocortisone was at the discretion of the treating intensivist and transplant surgeon.

MEASUREMENTS AND MAIN RESULTS

Two-hundred and forty-five (72%) patients met our criteria for adrenal insufficiency (the hepatoadrenal syndrome). Eight (33%) patients with fulminant hepatic failure, 97 (66%) patients with chronic liver disease, 31(61%) patients with a remote history of liver transplantation, and 109 (92%) patients who had undergone liver transplantation under steroid-free immunosuppression were diagnosed with adrenal insufficiency. The high-density lipoprotein level at the time of adrenal testing was the only variable predictive of adrenal insufficiency (p < .0001). In vasopressor-dependent patients with adrenal insufficiency, treatment with hydrocortisone was associated with a significant reduction (p = .02) in the dose of norepinephrine at 24 hrs, whereas the dose of norepinephrine was significantly higher (p = .04) in those patients with adrenal failure not treated with hydrocortisone. In vasopressor-dependent patients without adrenal insufficiency, treatment with hydrocortisone did not affect vasopressor dose at 24 hrs. One hundred and forty-one patients (26.4%) died during their hospitalization. The baseline serum cortisol was 18.8 +/- 16.2 microg/dL in the nonsurvivors compared with 13.0 +/- 11.8 microg/dL in the survivors (p < .001). Of those patients with adrenal failure who were treated with glucocorticoids, the mortality rate was 26% compared with 46% (p = .002) in those who were not treated. In those patients receiving vasopressor agents at the time of adrenal testing, the baseline cortisol was 10.0 +/- 4.8 microg/dL in those with adrenal insufficiency compared with 35.6 +/- 21.2 microg/dL in those with normal adrenal function. Vasopressor-dependent patients who did not have adrenal failure had a mortality rate of 75%.

CONCLUSIONS

Patients with liver failure and patients post-liver transplantation have an exceedingly high incidence of adrenal failure, which may be pathophysiologically related to low levels of high-density lipoprotein. Treatment of patients with adrenal failure may improve outcome. High baseline serum cortisol levels may be a maker of disease severity and portend a poor prognosis.

Adrenal corticosteroid biosynthesis, metabolism, and action

Adrenal corticosteroids are essential for life, and an appreciation of the mechanisms underpinning their synthesis, secretion, and mode of action in normal physiology is essential if the physician is to diagnose and treat patients who have Cushing's syndromes effectively. In each case, there have been clinically significant advances in the knowledge base over recent years, notably in the understanding of steroidogenesis, cortisol action, and metabolism. This article describes corticosteroid biosynthesis, metabolism, and action.

Science review: mechanisms of impaired adrenal function in sepsis and molecular actions of glucocorticoids

This review describes current knowledge on the mechanisms that underlie glucocorticoid insufficiency in sepsis and the molecular action of glucocorticoids. In patients with severe sepsis, numerous factors predispose to glucocorticoid insufficiency, including drugs, coagulation disorders and inflammatory mediators. These factors may compromise the hypothalamic–pituitary axis (i.e. secondary adrenal insufficiency) or the adrenal glands (i.e. primary adrenal failure), or may impair glucocorticoid access to target cells (i.e. peripheral tissue resistance). Irreversible anatomical damages to the hypothalamus, pituitary, or adrenal glands rarely occur. Conversely, transient functional impairment in hormone synthesis may be a common complication of severe sepsis. Glucocorticoids interact with a specific cytosolic glucocorticoid receptor, which undergoes conformational changes, sheds heat shock proteins and translocates to the nucleus. Glucocorticoids may also interact with membrane binding sites at the surface of the cells. The molecular action of glucocorticoids results in genomic and nongenomic effects. Direct and indirect transcriptional and post-transcriptional effects related to the cytosolic glucocorticoid receptor account for the genomic effects. Nongenomic effects are probably subsequent to cytosolic interaction between the glucocorticoid receptor and proteins, or to interaction between glucocorticoids and specific membrane binding sites.

Changes in cholesterol and its precursors during the first days after major trauma

BACKGROUND

The causes of hypocholesterolemia in the critically ill, including major trauma patients, have not yet been fully elucidated.

OBJECTIVE

We tested the hypothesis that hypocholesterolemia is caused by decreased production of cholesterol precursors.

DESIGN

Serum concentrations of squalene, lanosterol, and lathosterol were measured on admission, and then at 24 and 48 hours after injury using gas chromatography coupled with mass spectrometry. Serum concentrations of total low-density and high-density lipoprotein cholesterol were measured on admission and every day in the first week after injury.

RESULTS

83 consecutive patients with multiple trauma were examined. Significant drops in concentrations of lanosterol and lathosterol were found in the patients in comparison with the control group. The most profound drop was in lathosterol.

CONCLUSION

Decreased synthesis of cholesterol precursors is the major cause of hypocholesterolemia in patients with multiple trauma. Lathosterol concentration is proposed as a marker of cholesterol synthesis.

Adrenal incidentalomas showing unilateral concordant visualization by adrenocortical scintigraphy: comparison with adenomas in Cushing's syndrome

An adrenocortical adenoma causing Cushing's syndrome (Cushing's adenoma) produces a unilateral concordant visualization (UCV) imaging pattern in which the adenoma is only visualized on radioiodocholesterol adrenocortical scintigraphy. But because this imaging pattern is also noted in some patients with adrenal incidentalomas, we examined whether the UCV-incidentaloma was essentially identical with Cushing's adenoma and would develop Cushing's syndrome. The subjects were 9 patients with UCV-incidentalomas (mean size, 30 mm; range, 20-45 mm) and 6 patients with Cushing's adenomas (mean size, 28 mm; range, 25-35 mm). Endocrinological evaluations showed several abnormalities including blunted diurnal rhythm of plasma cortisol within the normal range, low plasma ACTH and/or high 24-hr urinary 17-OHCS levels in 8 of 9 patients with UCV-incidentalomas, but these abnormalities did not meet the diagnostic criteria of Cushing's syndrome. Adrenal uptake of the tracer in the patients with UCV-incidentalomas was not statistically different from that in the patients with Cushing's adenomas and had no relationship with hormonal values in either patient group. Tumor size on CT correlated with the levels of 24-hr urinary 17-OHCS (r = 0.75, p = 0.02) and plasma cortisol at 7:00 (r = 0.82, p = 0.007) in the patients with UCV-incidentalomas, but not in the patients with Cushing's adenomas. Although 3 UCV-incidentalomas increased slightly in size, none of 9 patients with UCV-incidentalomas has developed Cushing's syndrome for 4 to 52 months. These results suggest that the UCV-incidentaloma may be essentially different from the Cushing's adenoma and unlikely to develop Cushing's syndrome.

Effect of decreased plasma low-density lipoprotein levels on adrenal and testicular function in man

OBJECTIVE

The study assessed whether serum LDL cholesterol levels affect adrenal and Leydig cell function in man.

DESIGN AND METHODS

A 24-h continuous ACTH infusion was performed in 15 consecutive chronically ill patients. Serum cortisol and DHEA-s were measured at baseline and at 3, 6, 12, 20, and 24 h during the infusion. Fasting serum lipoprotein levels including LDL cholesterol, HDL cholesterol as well as FSH, LH, total and free testosterone concentrations were also measured on the baseline morning samples prior to the infusion.

RESULTS

The initial 3 and 6 h percent rise in cortisol values during 24 h ACTH infusion were significantly diminished in patients with LDL-C values < 1.55 mmol/L as compared with patients with higher LDL-C levels (127 +/- 17% (SE) vs. 199 +/- 31% (SE); p < 0.02 and 115 +/- 17% vs. 213 +/- 32%; p < 0.02. However, the 24-h areas of cortisol under the curve were comparable in the 2 groups. Basal and ACTH stimulated DHEA-s levels and percent increases tended to be lower in the low LDL-C group but the differences were not statistically significant. The mean total testosterone was lower in the low LDL-C group (5.30 +/- 1.78 vs. 15.60 +/- 1.95 nmol/L; p < 0.0005). Free testosterone levels were also lower in the low LDL-C group (0.03 +/- 0.009 nmol/L vs. 0.08 +/- 0.01 nmol/L; p < 0.001). Five of six patients with low LDL-cholesterol had low testosterone values, but variable LH levels.

CONCLUSIONS

Our results suggest that severe acquired LDL cholesterol insufficiency impairs slightly the initial glucocorticoid response to ACTH stimulation but not the overall cortisol production during sustained ACTH stimulation. It also may contribute to the reduction in testosterone seen in chronically ill patients.

Cortisol production rates measured by liquid chromatography/mass spectrometry

Cortisol production rates (FPRs) in physiologic and pathologic states in humans have been investigated over the past 30 years. However, there has been conflicting evidence concerning the validity of the currently accepted value of FPRs in humans (12 to 15 mg/m2/d) as determined by radiotracer methodology. The present study reviews previous methods proposed for the measurement of FPRs in humans and discusses the applications of the first method for the direct determination of 24-hour plasma FPRs during continuous administration of a stable isotope, using a thermospray high-pressure liquid chromatography-mass spectrometry technique. The technique is fast, sensitive, and, unlike gas chromatography-mass spectrometry methods, does not require derivatization, allowing on-line detection and quantification of plasma cortisol after a simple extraction procedure. The results of determination of plasma FPRs by stable tracer/mass spectrometry are directly in units of mass/time and, unlike radiotracer methods, are independent of any determination of volume of distribution or cortisol concentration. Our methodology offers distinct advantages over radiotracer techniques in simplicity and reliability since only single measurements of isotope ratios are required. The technique was validated in adrenalectomized patients. Circadian variations in daily FRPs were observed in normal volunteers, and, to date, results suggest a lower FRP in normal children and adults than previously believed.

Failure to visualize bilateral adrenal glands in a patient with primary aldosteronism

Failure to visualize either adrenal gland by adrenal imaging was experienced in a patient with biochemical evidence of primary aldosteronism. Visualization of the adrenal glands was not possible after the administration of ACTH-Z (1 mg/day) for 3 days. The administration of ACTH and dexamethasone elicited an increase in blood pressure. Although the reason for this failure to visualize the adrenal glands by scanning and for the rise in blood pressure brought on by ACTH and dexamethasone remain unclear, we think that the case herein reported is a rare type of primary aldosteronism.

Transport of circulating serum cholesterol by human renal cell carcinoma

Clear cell renal cancer contains a large quantity of cholesterol ester (300-mg./gm. protein). To determine whether abnormalities in cholesterol transport could account for this sterol accumulation, the uptake, release, and imaging capabilities of intravenously injected 131I-6-iodomethyl-29-norcholesterol, a cholesterol analogue, were studied preoperatively in five patients with clear cell renal cancer. At surgery, samples of the liver, tumor, adrenal, and non-tumor kidney were obtained for analysis. 131I-sterol uptake by the tumor, when normalized for cholesterol content, was less than for adrenal, liver or kidney. In contrast, release of preloaded 131I-sterol from the human tumors was consistently slower than for normal kidney. The reduced release of free cholesterol from renal cancer cells may, in part, be responsible for the accumulation of cholesterol in human renal cancer.

Suppression of adjuvant arthritis in rats by cholesterol

Dietary cholesterol suppressed adjuvant arthritis, a chronic inflammatory disease, in rats, but did not significantly affect carrageenin edema, an acute inflammation. When rats were fed a high-cholesterol diet beginning 10 days before injection of adjuvant, the development of the adjuvant-induced arthritis was greatly suppressed. Cholesterol feeding prevented hypertrophy of the adrenal gland in arthritic rats, but had little influence on the serum corticosterone level. A significant positive correlation was observed between the adrenal weight and the severity of the arthritis. These findings suggest that the effect of cholesterol feeding is not due to increased adrenal sterol synthesis. Dietary cholesterol also prevented hypertrophy of the spleen, but had no effect on atrophy of the thymus in adjuvant-treated rats. Cholesterol-fed rats showed a significant decrease in the serum lipid peroxide level and a significant increase in the serum copper level. Adjuvant treatment not only enhanced hypercholesterolemia produced by cholesterol feeding, but also the level of free cholesterol in serum. These results suggest that dietary cholesterol may exert some effect on the immune response through changes in spleen and liver functions.

Stimulation of progesterone synthesis, in corpus luteum cells isolated from 4-amino-3,4-d-pyrazolopyrimidine-treated rats, by cholesterol presented in non-lipoprotein form

We have previously shown that the administration of 4-amino-3,4-d-pyrazolopyrimidine (4-APP) to rats reduces progesterone synthesis by cells subsequently isolated from their corpora lutea, and that plasma high density lipoprotein (HDL) can restore this progesterone synthesis to normal. In this paper we demonstrate that a dispersion of phospholipid and cholesterol, but not other sterols, can enhance this 4-APP-disabled progesterone synthesis to the same level as can HDL, thus providing the first direct evidence that cholesterol is the component of HDL upon which rat corpus luteum depends for its ability to synthesize progesterone.