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Biomedical subjects

C H Shackleton

Publications and source records attributed to C H Shackleton.

At least 109 records · Page 6Linked to original sources
PubMed1987

18-Hydroxy-11-deoxycortisol: a new steroid isolated from incubations of the adrenal with 11-deoxycortisol.

Cortisol has been shown to be metabolized in the zona glomerulosa of the adrenal gland through the same pathway involving the cytochrome P-450, corticosterone methyl oxidase by which corticosterone is transformed to 18-hydroxycorticosterone and aldosterone. When cortisol is the precursor, 18-hydroxycortisol and 18-oxocortisol are formed. 18-Hydroxycortisol can also be made at a similar rate in the bovine zona fasciculata and reticularis as in the zona glomerulosa. We studied the possibility that the formation of 18-hydroxycortisol in the zona fasciculata and reticularis might be through a different pathway involving initial 18-hydroxylation of 11-deoxycortisol before 11 beta-hydroxylation. Rat adrenal capsules or cores were incubated with 10 micrograms of cortisol or 11-deoxycortisol and the formation of 18-hydroxycortisol was measured by radioimmunoassay. Both capsules and cores transformed 11-deoxycortisol to 18-hydroxycortisol, but cortisol was only transformed in the capsular portion. Sixty-two rat adrenals were incubated with 10 mg of 11-deoxycortisol and the putative steroid, 18-hydroxy-11-deoxycortisol, was purified by TLC and HPLC and subjected to gas chromatography mass spectrometry. The mass spectra indicated that the steroid isolated was indeed 18-hydroxy-11-deoxycortisol. The function of this steroid is still unknown.

17-Hydroxycorticosteroids↗
PubMed1987

Thermospray HPLC/MS: a new mass spectrometric technique for the profiling of steroids.

The analysis of various steroid classes by thermospray HPLC-MS using solvent systems containing 0.1 M ammonium acetate has been described. For simple unconjugated 3-oxo-4-ene steroids the positive ion spectra are dominated by a parent ion M + H+ and with increasing numbers of hydroxyl group intense ions formed by sequential losses of water (M + H- n18)+ become important. Steroids with dihydroxyacetone side-chains readily lose these side-chains and the resulting (M + H-60)+ fragment is the base peak in their spectra. The (M + H-60)+ ion is not important for most steroids with glycerol-type side-chains. Although competition between thermal degradation and vaporization was observed at lower concentrations, the effect was minimized after optimizing conditions and the protonated molecular ion was easily detected when as little as 1-10 pmol of material were injected on-column. Steroid glucuronides when analyzed in the negative ion mode give simple spectra with base peak and parent ion (M-H)-. Lack of fragmentation permits facile and sensitive measurement of individual glucoronides by selected-ion-monitoring. Extensive fragmentation is seen in the positive ion mode with sequential losses of H2O from the molecular ions (M + NH4)+ and from the aglycone fragment ion. For simple unconjugated steroids the sensitivity of HPLC-MS in selected-ion-monitoring mode can be excellent. When the protonated molecular ion of testosterone was monitored the signal/noise ratio for 30 pg testosterone was about 10.

Chromatography, High Pressure Liquid↗
PubMed1986

Profiling steroid hormones and urinary steroids.

This paper reviews techniques utilized in the profiling of steroids in body fluids and tissues. Methods for profiling plasma unconjugated steroids and urinary steroid metabolites are focused on. Concentrations or levels of excretion of a variety of steroids have been documented and reviewed. The importance of profiling techniques in the study of normal and pathophysiology of hormonal steroids is discussed.

Animals↗
PubMed1986

The syndrome of apparent mineralocorticoid excess: its association with 11 beta-dehydrogenase and 5 beta-reductase deficiency and some consequences for corticosteroid metabolism.

We describe the metabolism of cortisol (F) in three children, two of them siblings, with apparent mineralocorticoid excess (AME). As with prior patients with AME, oxidation of F to cortisone (E) was impaired, but reduction of E to F was not. We propose that this metabolic defect is caused by deficient 11-dehydrogenase associated with unimpaired 11-reductase. The following supporting observations were made: urinary C21 11-hydroxy metabolites exceeded C21 11-oxo metabolites: ratio of urinary cortols to cortolones, 6.6 +/- 2.8 (+/- SD; normal, 0.47); tetrahydrocortisol (THF) and alloTHF to tetrahydrocortisone, 14.6 +/- 5.6 (normal, approximately 1); normal subjects oxidized [11 alpha-3H]F with transfer of 3H to water; the patients did not; 11-hydroxy, but not 11-oxo, C19 steroids were excreted into the urine; and fibroblasts from patients had 5 times more 11-reductase activity than normal subjects, though fibroblasts from neither group had 11-dehydrogenase activity. Other defects of cortisol metabolism not directly associated with 11-dehydrogenase deficiency were found: impaired conversion of tetrahydro to hexahydro neutral steroids, indicating defective reductive metabolism of the side chain; depressed F production rate and increased half-life of circulating F, resulting in normal blood levels of F; increased excretion of unconjugated F metabolites; and decreased excretion of THF relative to alloTHF, consistent with a 5 beta-reductase defect. Excretion of acidic metabolites of F (cortoic acids) was within the normal range. However, little or no 20 beta-hydroxy acids were excreted, while the level of urinary 20 alpha-hydroxy acids was increased. The 11-hydroxy to 11-oxo ratio of acid metabolites was similar to values in normal subjects. The proportion of cortoic acids relative to neutral hexahydro metabolites was increased (0.37 to 1.27 in patients; 22 in normal subjects). We conclude that children with AME have multiple defects in the conversion of F to neutral metabolites, while metabolism to cortoic acids was less extensively affected. How the defects in cortisol metabolism and the symptoms of AME are related remains to be determined.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1985

Equol: a contributor to enigmatic immunoassay measurements of estrogen.

The efficacy of radioimmunoassay (RIA) for the measurement of estradiol-17 beta (E2) in murine plasma was investigated. When Sephadex LH-20 or celite column chromatography was used to separate E2 from estrone (E1) and other cross-reacting compounds, the results were erratic if small volumes of mouse plasma were resolved. Assay of a diethyl ether extract of plasma (500 microL) was the most practical method for estimating the concentration of estradiol-17 beta in mice. This method was used to determine the pattern of estrogen secretion during the estrous cycle, on the day of implantation and during pregnancy. No convincing change in estrogen secretion was observed in the diestrous/proestrous mouse. By comparison, estrogen levels were elevated during pregnancy. Taken together, these results implied that cross-reactive components in plasma masked low levels of endogenous estrogen. Further evaluation of mouse plasma and urine using a co-chromatography technique to examine estrogen elution from a reverse-phase HPLC system followed by GC/MS analysis indicated the presence of equol [7-hydroxy-3-(4-hydroxyphenyl)chroman], a phytoestrogen metabolite with a ring structure similar to estradiol-17 beta. Equol and possibly other cross-reactive components of plasma may account for the apparent lack of increased estrogen secretion during the mouse estrous cycle and on the day of implantation as determined by the radioimmunoassay of ether extracts of plasma.

Animals↗
PubMed1985

Congenital 11 beta-hydroxysteroid dehydrogenase deficiency associated with juvenile hypertension: corticosteroid metabolite profiles of four patients and their families.

Four children with 11 beta-hydroxysteroid dehydrogenase deficiency are described. All patients had severe hypertension, hypokalaemia, and low plasma aldosterone and renin activities. Two of the patients were siblings and two were unrelated. The most noticeable biochemical feature of these individuals was the extremely low excretion of cortisol metabolites containing an 11-carbonyl group compared to the excretion of the 11 beta-hydroxyl containing metabolites. Although this condition is readily diagnosed in affected individuals by urinary steroid analysis, carriers of the defect do not differ from normal in their urinary steroids. Both parents of the affected siblings had normal 11-oxo-steroid/11 beta-hydroxysteroid ratios under baseline conditions and the lesions could not be revealed by ACTH administration.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1984

Bacterial formation of aldosterone metabolites.

The experiments described in this paper demonstrate that most of the metabolic alterations of the aldosterone molecule, hitherto attributed to hepatic enzymes, equally well may be carried out by enzymes synthesized by anaerobic bacteria from the human gut. The steroid reductases synthesized by Clostridium paraputrificum, Clostridium J-1, and Clostridium innocuum convert aldosterone to the 3 alpha, 5 beta tetrahydroaldosterone (THA), 3 beta, 5 alpha-THA, and 3 alpha, 5 alpha-THA, respectively. All three enzymes metabolize 5 alpha.dihydroaldosterone to a single compound: 3 beta, 5 alpha-THA. Bifidobacterium adolescentis reduces aldosterone to 20 beta-dihydroaldosterone. In mixed cultures of B. adolescentis and clostridia, the individual enzymes operate independently of each other; however, about half of the aldosterone metabolites are in the free form and half in the acetal form. By appropriate selection of substrate and bacterial strains, therefore, it is possible to biosynthesize not only three of the THA isomers but also the hexahydroisomers in free form as well as in the acetal form.

Aldosterone↗
PubMed1984

Identification of a non-steroidal estrogen, equol, in the urine of pregnant macaques: correlation with steroidal estrogen excretion.

Macaque urinary estrogens at late pregnancy were separated by high performance liquid chromatography and quantified, both with radioimmunoassay and an in vitro uterine estrogen receptor assay. Five estrogens were measured. Four were steroids: estriol, estrone, 17 beta-estradiol, and 16 alpha-hydroxyestrone. The fifth was a flavonoid, equol, a metabolite of plant isoflavonoids, formononetin and genistein. By mass, estrone and equol were the predominant urinary estrogens, with equol reaching levels of microgram/mg creatinine in three of 8 pregnancies studied. Both quality and quantity of urinary estrogen excretion in the rhesus (Macaca mulatta) was compared to those in 4 other species (Macaca fascicularis, Macaca nemestrina, Macaca radiata and Macaca silenus). All 5 estrogens present in the rhesus were also present in the other 4. Variability in mass of each estrogen excreted appeared no greater between species than within the rhesus. In a longitudinal study, urinary equol levels were most highly correlated with those of estrone, the predominant excretory steroid of macaque pregnancy. We conclude endogenous steroidal estrogen is related to production of equol in macaques, however, equol is not dependent on the feto-placental unit as low levels of equol were also present in male macaque urine.

Animals↗
PubMed1984

11 beta-Hydroxysteroid dehydrogenase: fact or fancy?

Previous attempts to explain the diverse behavior of 11 beta-hydroxysteroid dehydrogenase (11-HSD) within and between species have not been successful. We now propose that 11-HSD activity is the resultant of the coordinated interaction of two enzyme types, 11-dehydrogenase and 11-reductase. We have demonstrated their separate existence by physico-chemical and kinetic methods. Based on these findings, two classes of disease in humans that have been recently described can now be characterized as being associated with a deficiency in either 11-dehydrogenase or 11-reductase.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1984

Diagnosis and natural history of 17-hydroxylase deficiency in a newborn male.

We documented 17-hydroxylase deficiency in a newborn male infant with micropenis, perineoscrotal hypospadias, and a bifid scrotum containing two histologically normal testes. Mild hypertension developed at 20 months of age. The diagnosis was made on the basis of elevated serum levels of progesterone (180-475 ng/dl), corticosterone (1.8-20.2 micrograms/dl), and desoxycorticosterone (56-330 ng/dl). There was an exaggerated response of these steroids to ACTH-(1-24) and suppression by dexamethasone. Mass spectrometric analysis of urinary steroids showed an abnormally high ratio of C21 to C19 3 beta-hydroxy-5-ene steroids due to reduced C19 steroid formation. We suggest that this infant has a form of 17-hydroxylase deficiency which is less severe than previously reported cases in view of his partial prenatal virilization, the minimal testosterone response to CG the absence of hypokalemia, and the presence of normal cortisol levels after prolonged ACTH stimulation. Family studies suggest reduced 17-hydroxylase activity in the father. A surprising coincident finding of no apparent clinical significance was in vitro evidence of 5 alpha-reductase deficiency in genital skin fibroblasts.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1984

Evidence supporting the renal synthesis of 19-nor-deoxycorticosterone.

The fraction of urine containing free steroids was analyzed in a specimen obtained from a patient with 17 alpha-hydroxylase deficiency and contained deoxycorticosterone (DOC) (approximately 0.9 micrograms/24 h), 19 nor-DOC (approximately 1.1 micrograms/24 h) and tetrahydro-DOC (approximately 15.2 micrograms/24 h). These steroids were identified by combined gas chromatography/mass spectrometry. If present, tetrahydro-19-nor-DOC was at a concentration below the limits of detection, but it was the major metabolite found in urine of a normal person after ingestion of the steroid. This strongly suggests that little 19-nor-DOC passes through the liver after synthesis and is therefore further evidence that the final stage of its synthesis occurs in the kidney in close proximity to the site of excretion.

Adrenal Hyperplasia, Congenital↗
PubMed1983

Characterization of the major steroids present in amniotic fluid obtained between the 15th and 17th weeks of gestation.

In pooled amniotic fluid obtained between the 15th and 17th weeks of gestation the concentration of free steroids and steroid glucuronides was found to be 40 micrograms/dl. The concentration of steroid monosulfates and disulfates was 19 micrograms/dl. About half of the characterized steroids are progesterone metabolites. The "fetal type" 3 beta-hydroxy-5-ene steroids were found exclusively in the sulfoconjugated form. Their concentration represents 20% of the total steroid content. The identification of two 15 beta-hydroxylated C21 steroids, 3 beta,15 beta,17 alpha-tridoxy-5-pregnen-20-one and 5-pregnene-3 beta,15 beta,17 alpha,20 alpha-tetrol isolated from mid-pregnancy amniotic fluid is reported here. Metabolites of cortisol and 17-deoxycorticosteroid metabolites had similar quantitative importance, 8.6 and 9.4%, respectively.

17-alpha-Hydroxypregnenolone↗
PubMed1983

Failure of steroid sulfatase to desulfate vitamin D3 sulfate.

Patients with recessive X-linked ichthyosis lack activity of the enzyme steroid sulfatase. One of the more striking clinical findings in these patients is the improvement in stratum corneum shedding in the summer. Since vitamin D is one steroid responsive to sunlight, we examined whether or not vitamin D3 sulfate is a substrate for steroid sulfatase. Enzyme preparations active against other sulfated steroids caused no desulfation of vitamin D3 sulfate.

Cholecalciferol↗
PubMed1983

17 alpha-hydroxylase deficiency: mineralocorticoid hormone profiles in an affected family.

The plasma concentrations of mineralocorticoid hormones, basal and after stimulation and suppression with ACTH, can identify the heterozygotes in a family with two siblings with 17 alpha-hydroxylase deficiency. Both parents and one sibling had elevated levels of plasma deoxycorticosterone, corticosterone, 18-hydroxydeoxycorticosterone, and 18-hydroxycorticosterone, but normal cortisol and aldosterone concentrations. Stimulation with ACTH effected additional increases in the elevated steroid and cortisol levels, but not in aldosterone, further increasing the discrepancy and the ratio between 18-hydroxycorticosterone and aldosterone. One sibling had normal steroid patterns and an 18-hydroxycorticosterone to aldosterone ratio. Suppression of ACTH restored the steroids to low normal levels. In addition, the ratio of the gas chromatographic analysis of the total major urinary metabolites of corticosterone to total metabolites of cortisol was greater, and the sum of urinary androsterone and etiocholanolone to total corticosterone and cortisol metabolites was less in the heterozygotes than in normal subjects. This identifies deficient 17-hydroxylation, which is required for the production of cortisol and C-19 steroids. These criteria appear unique for the 17 alpha-hydroxylase defect in the heterozygote.

18-Hydroxycorticosterone↗
PubMed1983

Difficulties in the diagnosis of congenital adrenal hyperplasia in early infancy: the 11 beta-hydroxylase defect.

Investigations of steroid metabolism in a newborn infant with steroid 11 beta-hydroxylase deficiency are described. Deficiency of this enzyme, like other forms of congenital adrenal hyperplasia (CAH) can be difficult to characterise in the neonatal period. In the first days of life the excretion of cortisol was low but most other hormonal parameters were normal and the major metabolite of 11-deoxycortisol (tetrahydro-S, THS) was not detectable in the urine. Using mass spectrometry, the presence of THS was confirmed in urine collected on the 12th day of life and from this time the excretion rates increased until approximately 300 micrograms were measured in urine on the 27th day of life. A new metabolite of 11-deoxycortisol was tentatively identified as 6 alpha-hydroxy-THS. This steroid is not a significant metabolite in 11 beta-hydroxylase deficiency at other periods of life.

Adrenal Cortex Hormones↗
PubMed1983

Inborn errors of steroid biosynthesis: detection by a new mass-spectrometric method.

A new mass-spectrometric technique relies on ionization during bombardment of the analyte (dissolved in a liquid matrix, usually glycerol) by an atom beam (e.g., Ar0, Xe0). This technique, termed "fast atom bombardment," is particularly useful in the characterization of polar charged molecules. A neutral beam is not essential, and a primary beam of cesium ions has been successfully used to produce spectra equivalent to those obtained by fast atom bombardment. In this communication I report data on the use of both ion and atom primary beams for producing secondary-ion mass spectra of conjugated steroids. In negative-ion spectra produced for steroid glucuronides and sulfates, the ion [M - H]- is invariably the major high-mass peak, and the lack of substantial fragmentation allows assay of relatively complex mixtures if the analytes differ in mass. I describe here the use of secondary-ion mass spectrometry for distinguishing, by urinary steroid analysis, patients with the four enzyme defects that can affect cortisol synthesis: defects in 17 alpha-hydroxylase, 3 beta-hydroxysteroid dehydrogenase/isomerase, 21-hydroxylase, and 11 beta-hydroxylase.

Glucuronates↗