Publications by authors named "Cedric Shackleton"

Primary aldosteronism (PA) causes 5-10% of hypertension cases, but only a minority of patients are currently diagnosed and treated because of a complex, stepwise, and partly invasive workup. We tested the performance of urine steroid metabolomics, the computational analysis of 24-hour urine steroid metabolome data by machine learning, for the identification and subtyping of PA. Mass spectrometry-based multi-steroid profiling was used to quantify the excretion of 34 steroid metabolites in 24-hour urine samples from 158 adults with PA (88 with unilateral PA [UPA] due to aldosterone-producing adenomas [APAs]; 70 with bilateral PA [BPA]) and 65 sex- and age-matched healthy controls.

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Context: 17α-Hydroxylase/17,20-lyase deficiency (17OHD) caused by mutations in the CYP17A1 gene is a rare form of congenital adrenal hyperplasia typically characterised by cortisol deficiency, mineralocorticoid excess and sex steroid deficiency.

Objective: To examine the phenotypic spectrum of 17OHD by clinical and biochemical assessment and corresponding in silico and in vitro functional analysis.

Design: Case series.

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Bile acids are the end products of cholesterol metabolism secreted into bile. They are essential for the absorption of lipids and lipid soluble compounds from the intestine. Here we have identified a series of unusual Δ-unsaturated bile acids in plasma and urine of patients with Smith-Lemli-Opitz syndrome (SLOS), a defect in cholesterol biosynthesis resulting in elevated levels of 7-dehydrocholesterol (7-DHC), an immediate precursor of cholesterol.

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Background: Cross-sectional imaging regularly results in incidental discovery of adrenal tumours, requiring exclusion of adrenocortical carcinoma (ACC). However, differentiation is hampered by poor specificity of imaging characteristics. We aimed to validate a urine steroid metabolomics approach, using steroid profiling as the diagnostic basis for ACC.

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Androgen biosynthesis in the human fetus proceeds through the adrenal sex steroid precursor dehydroepiandrosterone, which is converted to testosterone in the gonads, followed by further activation to 5α-dihydrotestosterone in genital skin, thereby facilitating male external genital differentiation. Congenital adrenal hyperplasia due to P450 oxidoreductase deficiency results in disrupted dehydroepiandrosterone biosynthesis, explaining undervirilization in affected boys. However, many affected girls are born virilized, despite low circulating androgens.

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Advances in technology have allowed for the sensitive, specific, and simultaneous quantitative profiling of steroid precursors, bioactive steroids and inactive metabolites, facilitating comprehensive characterization of the serum and urine steroid metabolomes. The quantification of steroid panels is therefore gaining favor over quantification of single marker metabolites in the clinical and research laboratories. However, although the biochemical pathways for the biosynthesis and metabolism of steroid hormones are now well defined, a gulf still exists between this knowledge and its application to the measured steroid profiles.

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Steroid biosynthesis and metabolism are reflected by the serum steroid metabolome and, in even more detail, by the 24-hour urine steroid metabolome, which can provide unique insights into alterations of steroid flow and output indicative of underlying conditions. Mass spectrometry-based steroid metabolome profiling has allowed for the identification of unique multisteroid signatures associated with disorders of steroid biosynthesis and metabolism that can be used for personalized approaches to diagnosis, differential diagnosis, and prognostic prediction. Additionally, steroid metabolome analysis has been used successfully as a discovery tool, for the identification of novel steroidogenic disorders and pathways as well as revealing insights into the pathophysiology of adrenal disease.

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Objective And Context: Increasing adiposity, ageing and tissue-specific regeneration of cortisol through the activity of 11β-hydroxysteroid dehydrogenase type 1 have been associated with deterioration in glucose tolerance. We undertook a longitudinal, prospective clinical study to determine if alterations in local glucocorticoid metabolism track with changes in glucose tolerance.

Design, Patients, And Measurements: Sixty-five overweight/obese individuals (mean age 50.

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Gas chromatography/mass spectrometry (GC/MS) has been used for steroid analysis since the 1960s. The advent of protective derivatization, capillary columns, and inexpensive electron ionization bench-top single quadrupole soon made it the method of choice for studying disorders of steroid synthesis and metabolism. However, the lengthy sample workup prevented GC/MS from becoming routine for steroid hormone measurement, which was dominated by radioimmunoassay.

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The steroid disulfates ( bis-sulfates) are a significant but minor fraction of the urinary steroid metabolome that have not been widely studied because major components are not hydrolyzed by the commercial sulfatases commonly used in steroid metabolomics. In early studies, conjugate fractionation followed by hydrolysis using acidified solvent (solvolysis) was used for the indirect detection of this fraction by GC-MS. This paper describes the application of a specific LC-MS/MS method for the direct identification of disulfates in urine, and their use as markers for the prenatal diagnosis of disorders causing reduced estriol production: STSD (steroid sulfatase deficiency), SLOS (Smith-Lemli-Opitz syndrome) and PORD (P450 oxidoreductase deficiency).

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Background: Adrenal aldosterone excess is the most common cause of secondary hypertension and is associated with increased cardiovascular morbidity. However, adverse metabolic risk in primary aldosteronism extends beyond hypertension, with increased rates of insulin resistance, type 2 diabetes, and osteoporosis, which cannot be easily explained by aldosterone excess.

Methods: We performed mass spectrometry-based analysis of a 24-hour urine steroid metabolome in 174 newly diagnosed patients with primary aldosteronism (103 unilateral adenomas, 71 bilateral adrenal hyperplasias) in comparison to 162 healthy controls, 56 patients with endocrine inactive adrenal adenoma, 104 patients with mild subclinical, and 47 with clinically overt adrenal cortisol excess.

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The lower risk of some internal cancers at lower latitudes has been linked to greater sun exposure and consequent higher levels of ultraviolet radiation (UVR)-produced vitamin D (D). To separate the experimental effects of sunlight and of all forms of D, a mouse in which UVR does not produce D would be useful. To this end we have generated mice carrying a modified allele of sterol C5-desaturase (Sc5d), the gene encoding the enzyme that converts lathosterol to 7-dehydrocholesterol (7-DHC), such that Sc5d expression can be inactivated using the Cre/lox site-specific recombination system.

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Context: Steroid sulfatase (STS) cleaves the sulfate moiety off steroid sulfates, including dehydroepiandrosterone (DHEA) sulfate (DHEAS), the inactive sulfate ester of the adrenal androgen precursor DHEA. Deficient DHEA sulfation, the opposite enzymatic reaction to that catalyzed by STS, results in androgen excess by increased conversion of DHEA to active androgens. STS deficiency (STSD) due to deletions or inactivating mutations in the X-linked STS gene manifests with ichthyosis, but androgen synthesis and metabolism in STSD have not been studied in detail yet.

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Context: Polycystic ovary syndrome (PCOS) is a heritable, complex genetic disease. Animal models suggest that androgen exposure at critical developmental stages contributes to disease pathogenesis. We hypothesized that genetic variation resulting in increased androgen production produces the phenotypic features of PCOS by programming during critical developmental periods.

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Smith-Lemli-Opitz syndrome (SLOS) is a severe autosomal recessive disorder resulting from defects in the cholesterol synthesising enzyme 7-dehydrocholesterol reductase (Δ-sterol reductase, DHCR7, EC 1.3.1.

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Smith Lemli Opitz syndrome (SLOS) is an inherited malformation and mental retardation metabolic disorder with no cure. Mutations in the last enzyme of the cholesterol biosynthetic pathway, 7-dehydrocholesterol reductase (DHCR7), lead to cholesterol insufficiency and accumulation of its dehyrdocholesterol precursors, and contribute to its pathogenesis. The central nervous system (CNS) constitutes a major pathophysiological component of this disorder and remains unamenable to dietary cholesterol therapy due to the impenetrability of the blood brain barrier (BBB).

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Smith-Lemli-Opitz syndrome (SLOS) is an inborn error of cholesterol synthesis resulting from a defect in 7-dehydrocholesterol reductase (DHCR7), the enzyme that produces cholesterol from its immediate precursor 7-dehydrocholesterol. Current therapy employing dietary cholesterol is inadequate. As SLOS is caused by a defect in a single gene, restoring enzyme functionality through gene therapy may be a direct approach for treating this debilitating disorder.

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Objective: Dysregulation of enzymes that control local tissue steroid metabolism has been implicated in the pathogenesis of obesity and insulin resistance; however, longitudinal changes in glucocorticoid metabolism have not been investigated. This study was performed to evaluate the role of glucocorticoid metabolism in the development of insulin resistance and obesity and to identify biomarkers for future development of metabolic disease.

Design: This was a prospective longitudinal observation study conducted over 5 years.

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Context: Low birth weight is associated with adverse metabolic outcome in adulthood. Exposure to glucocorticoid (GC) excess in utero is associated with decreased birth weight, but the prospective longitudinal relationship between GC metabolism and growth has not been examined.

Objective: We have hypothesized that changes in GC metabolism leading to increased availability may impair growth.

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Apparent mineralocorticoid excess syndrome (AME) is an autosomal recessive genetic disorder caused by a deficiency in the enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD). We report a 36-year-old male who was hypertensive from birth and was diagnosed with AME at 8 years of age. There was continuous documentation of his hypertension and hypokalemic alkalosis throughout childhood, during which spironolactone and supplemental potassium were administered.

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Zebrafish are emerging as a model to study steroid hormone action and associated disease. However, steroidogenesis in zebrafish is not well characterized. Mammalian P450 side-chain cleavage enzyme (CYP11A1) catalyzes the first step of steroidogenesis, the conversion of cholesterol to pregnenolone.

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In this study the sterol and oxysterol profile of newborn brain from the Dhcr7(Δ3-5/T93M) mouse model of Smith-Lemli-Opitz syndrome (SLOS) has been investigated. This is a viable mouse model which is compound heterozygous containing one null allele and one T93M mutation on Dhcr7. We find the SLOS mouse has reduced levels of cholesterol and desmosterol and increased levels of 7- and 8-dehydrocholesterol and of 7- and 8-dehydrodesmosterol in brain compared to the wild type.

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Context: Mutations in the electron donor enzyme P450 oxidoreductase (POR) result in congenital adrenal hyperplasia with apparent combined 17α-hydroxylase/17,20 lyase and 21-hydroxylase deficiencies, also termed P450 oxidoreductase deficiency (PORD). Major clinical features present in PORD are disordered sex development in affected individuals of both sexes, glucocorticoid deficiency, and multiple skeletal malformations.

Objective: The objective of the study was to establish a noninvasive approach to prenatal diagnosis of PORD including assessment of malformation severity to facilitate optimized prenatal diagnosis and timely treatment.

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