Effect of psychotropic drug treatment on sterol metabolism

Cholesterol metabolism is vital for brain function. Previous work in cultured cells has shown that a number of psychotropic drugs inhibit the activity of 7-dehydrocholesterol reductase (DHCR7), an enzyme that catalyzes the final steps in cholesterol biosynthesis. This leads to the accumulation of 7-dehydrocholesterol (7DHC), a molecule that gives rise to oxysterols, vitamin D, and atypical neurosteroids. We examined levels of cholesterol and the cholesterol precursors desmosterol, lanosterol, 7DHC and its isomer 8-dehydrocholesterol (8DHC), in blood samples of 123 psychiatric patients on various antipsychotic and antidepressant drugs, and 85 healthy controls, to see if the observations in cell lines hold true for patients as well. Three drugs, aripiprazole, haloperidol and trazodone increased circulating 7DHC and 8DHC levels, while five other drugs, clozapine, escitalopram/citalopram, lamotrigine, olanzapine, and risperidone, did not. Studies in rat brain verified that haloperidol dose-dependently increased 7DHC and 8DHC levels, while clozapine had no effect. We conclude that further studies should investigate the role of 7DHC and 8DHC metabolites, such as oxysterols, vitamin D, and atypical neurosteroids, in the deleterious and therapeutic effects of psychotropic drugs. Finally, we recommend that drugs that increase 7DHC levels should not be prescribed during pregnancy, as children born with DHCR7 deficiency have multiple congenital malformations.

Sterols and oxysterols in plasma from Smith-Lemli-Opitz syndrome patients

Smith-Lemli-Opitz syndrome (SLOS) is a severe autosomal recessive disorder resulting from defects in the cholesterol synthesising enzyme 7-dehydrocholesterol reductase (Δ⁷-sterol reductase, DHCR7, EC 1.3.1.21) leading to a build-up of the cholesterol precursor 7-dehydrocholesterol (7-DHC) in tissues and blood plasma. Although the underling enzyme deficiency associated with SLOS is clear there are likely to be multiple mechanisms responsible for SLOS pathology. In an effort to learn more of the aetiology of SLOS we have analysed plasma from SLOS patients to search for metabolites derived from 7-DHC which may be responsible for some of the pathology. We have identified a novel hydroxy-8-dehydrocholesterol, which is either 24- or 25-hydroxy-8-dehydrocholesterol and also the known metabolites 26-hydroxy-8-dehydrocholesterol, 4-hydroxy-7-dehydrocholesterol, 3β,5α-dihydroxycholest-7-en-6-one and 7α,8α-epoxycholesterol. None of these metabolites are detected in control plasma at quantifiable levels (0.5ng/mL).

Increases in plasma plant sterols stabilize within four weeks of plant sterol intake and are independent of cholesterol metabolism

BACKGROUND AND AIMS

Plant sterols (PS) lower plasma LDL-cholesterol through partial inhibition of intestinal cholesterol absorption. Although PS themselves are poorly absorbed, increased intakes of PS result in elevated plasma concentrations. In this paper, we report time curves of changes in plasma PS during 12 weeks of PS intake. Furthermore, the impact of cholesterol synthesis and absorption on changes in plasma PS is explored.

METHODS AND RESULTS

The study was a double-blind, randomized, placebo-controlled, parallel-group study with the main aim to investigate the effects of PS on vascular function (clinicaltrials.gov: NCT01803178). Hypercholesterolemic but otherwise healthy men and women (n = 240) consumed low-fat spreads without or with added PS (3 g/d) for 12 weeks after a 4-week run-in period. Blood sampling was performed at week 0, 4, 8 and 12. Basal cholesterol-standardized concentrations of lathosterol and sitosterol + campesterol were used as markers of cholesterol synthesis and absorption, respectively. In the PS group, plasma sitosterol and campesterol concentrations increased within the first 4 weeks of intervention by 69% (95%CI: 58; 82) starting at 7.2 μmol/L and by 28% (95%CI: 19; 39) starting at 11.4 μmol/L, respectively, and remained stable during the following 8 weeks. Placebo-corrected increases in plasma PS were not significantly different between high and low cholesterol synthesizers (P-values >0.05). Between high and low cholesterol absorbers, no significant differences were observed, except for the cholesterol-standardized sum of four major plasma PS (sitosterol, campesterol, brassicasterol and stigmasterol) showing larger increases in low absorbers (78.3% (95%CI: 51.7; 109.5)) compared to high absorbers (40.8% (95%CI: 19.9; 65.5)).

CONCLUSIONS

Increases in plasma PS stabilize within 4 weeks of PS intake and do not seem impacted by basal cholesterol synthesis or absorption efficiency. This study was registered at clinicaltrials.gov (NCT01803178).

Elevated cholesterol precursors other than cholestanol can also be a hallmark for CTX

Cerebrotendinous xanthomatosis (CTX) is an inborn error of bile acid synthesis in which hepatic conversion of cholesterol to cholic and chenodeoxycholic acids is impaired. Patients have abnormal bile alcohols in urine, normal to increased plasma cholesterol concentrations and increased concentrations of plasma cholestanol. Little is known about cholesterol precursors in CTX, however. We studied cholesterol and phytosterol profiles in two siblings with CTX during follow-up. While cholesterol concentrations were low in both patients, plasma cholestanol was 6-fold higher compared to control values. In addition, both siblings had a more than 100-fold increase in 7-dehydrocholesterol (7DHC) and 8-dehydrocholesterol (8DHC). Lathosterol, lanosterol and sitosterol were increased in both patients while concentrations of desmosterol and campesterol were normal. In addition, plasma lathosterol/cholesterol ratios were significantly elevated. After treatment with chenodeoxycholate, both patients showed a marked decrease in cholestanol, 7DHC, 8DHC, lathosterol, lanosterol and sitosterol. In addition, the lathosterol/cholesterol ratio normalized, indicating that overall cholesterol synthesis was sufficiently suppressed. This study shows that elevated cholesterol precursors, other than cholestanol, can be a hallmark for CTX.

Rapid quantification of free and esterified phytosterols in human serum using APPI-LC-MS/MS

A novel analytical platform based on liquid chromatography and tandem mass spectrometry using atmospheric pressure photoionization was applied for the simultaneous quantification of free and esterified beta-sitosterol, campesterol, brassicasterol, and stigmasterol. The total time for sample pretreatment and analysis could be reduced from approximately 3 h [gas chromatography-mass spectrometry (GC-MS)] to 15 min. The detection limits of the different phytosterols ranged between 0.25 and 0.68 microg/l. Linear ranges were between 1 and 1,000 microg/l. The within-run and between-run variabilities ranged between 1.4% and 9.9%. The analytical sensitivity was at least 150-fold higher compared with GC-MS. Our new method allows a rapid and simultaneous determination of free and esterified phytosterols in serum.

Smith-Lemli-Opitz syndrome with a classical phenotype, oesophageal achalasia and borderline plasma sterol concentrations

The diagnostic biochemical hallmarks of Smith-Lemli-Opitz syndrome (SLOS) are elevated concentrations of the cholesterol precursors 7- and 8-dehydrocholesterol (7- and 8-DHC). We describe a patient with classical SLOS phenotype and oesophageal achalasia, which has not been reported in SLOS patients before. Plasma 7-DHC and 8-DHC were only marginally elevated. The diagnosis was confirmed by sterol analysis in cultured skin fibroblasts and mutation analysis.

Effects of dietary cholesterol on plasma lipoproteins in Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz syndrome is a condition of impaired cholesterol synthesis that is caused by mutations in DHCR7 encoding 7-dehydrocholesterol-Delta7 reductase. Birth defects and mental retardation are characteristic. Deficient plasma and tissue cholesterol and excess cholesterol precursors 7 and 8 dehydrocholesterol (7DHC and 8DHC) contribute to the pathogenesis. Cholesterol is transported to tissues via lipoproteins. We measured the effect of dietary cholesterol (egg yolk) on plasma lipoproteins to evaluate this potential treatment. We used the enzymatic method to measure total sterols in lipoproteins (n=12) and plasma (n=16). In addition, we analyzed individual plasma sterols by a gas chromatographic method. Samples were evaluated after 3 wk of a cholesterol-free diet and after 6-19 mo of dietary cholesterol. We also analyzed the distribution of sterols in lipoproteins and the apolipoprotein E genotype. Dietary cholesterol significantly increased the total sterols in plasma (2.22 +/- 0.13 to 3.10 +/- 0.22; mean +/- SEM; p < 0.002), in LDL (0.98 +/- 0.13 to 1.52 +/- 0.17 mM), and in HDL (0.72 +/- 0.04 to 0.92 +/- 0.07). Plasma cholesterol increased (1.78 +/- 0.16 to 2.67 +/- 0.25 mM; p < 0.007) and plasma 7DHC decreased in 10 children, but the mean decrease was not significant. The distribution of individual sterols in each lipoprotein fraction was similar to the distribution in plasma. The baseline cholesterol and the response to dietary cholesterol was the same in children with 3/3 and 3/4 apolipoprotein E genotypes. Dietary cholesterol increased total sterols in plasma, LDL, and HDL in children with Smith-Lemli-Opitz syndrome. These favorable increases in the lipoproteins are potentially therapeutic for this condition.

Serum Lipid Analysis Confirms the Diagnosis of X-Linked Dominant Chondrodysplasia Punctata - Conradi-Hünermann-Happle Syndrome

We present the morphological and biochemical findings in a twelve month old girl with chondrodysplasia punctata X2 - Conradi-Hünermann-Happle syndrome. This disease is characterized by limb length discrepancies, growth retardation, ichthyosis, cataracts, and punctate calcification. The diagnosis could finally be confirmed by increased concentrations of cholesterol precursors as recently found in the plasma and tissues of affected patients.

Identification of three patients with a very mild form of Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive malformation syndrome characterized by mental retardation, congenital anomalies, and growth deficiency. The syndrome is caused by a block in cholesterol biosynthesis at the level of 7-dehydrocholesterol reductase (7-DHCR), which results in elevated levels of the cholesterol precursor 7-dehydrocholesterol (7-DHC) and its isomer 8-dehydrocholesterol (8-DHC). We report on three patients from two families with a very mild clinical presentation of SLOS. Their plasma cholesterol values were normal and their plasma levels of 7- and 8- DHC were only slightly elevated. In cultured skin fibroblasts, a significant residual 7-DHCR activity was found. All three patients were compound heterozygotes for a novel mutation affecting translation initiation (M1L). Two of them had the common IVS8-1G>C null mutation and the third patient an E448K mutation in the 7-DHCR gene. Our findings emphasize the importance of using a sensitive method for measuring precursors of cholesterol in combination with mutation analysis to analyze patients with only minimal clinical SLOS-like signs.

X-linked dominant chondrodysplasia punctata (CDPX2) caused by single gene mosaicism in a male

X-linked dominant chondrodysplasia punctata (CDPX2; Happle syndrome) is recognized almost exclusively in females, who display mosaic and asymmetric features, presumed to arise secondary to random X-inactivation. CDPX2 results from mutation of an X-linked gene coding for sterol-delta(8)-delta(7) isomerase (emopamil binding protein). We describe a boy with clinical features of CDPX2 (including those presumed to arise usually secondary to functional mosaicism in females). Biochemical and molecular studies demonstrate that he is mosaic for a sterol-delta(8)-delta(7) isomerase gene mutation. He is the first reported example of single gene mosaicism giving rise to CDPX2 in a male.

Simvastatin treatment in the SLO syndrome: a safe approach?

Soon after the discovery of reduced cholesterol synthesis in the Smith-Lemli-Opitz syndrome (SLOS), several trials with dietary supplementation were initiated with the aim of increasing cholesterol and reducing the de novo synthesis and accumulation of 7- and 8-dehydrocholesterol (DHC). Dietary cholesterol raises cholesterol levels in the circulation with only marginal effects on levels of DHC. Photosensitivity and polyneuropathy have been reported to be improved by the treatment, but other effects have been difficult to evaluate. In order to see whether inhibition of hydroxymethylglutaryl CoA reductase is of benefit, two of our patients have been treated with simvastatin in addition to the long-term treatment with cholesterol and bile acids. Absolute as well as relative levels of DHC were reduced. In one patient, creatine kinase increased moderately after 2 months of treatment. In the other patient, the treatment had to be interrupted because of hepatotoxic side effects with a marked increase in alanine aminotransferase and aggravation of the hypocholesterolemia and photosensitivity. We conclude that even if the levels of accumulated intermediates can be reduced, treatment with a statin may be harmful in some patients with SLOS.

Effects of sample storage on 7- and 8-dehydrocholesterol levels analysed on whole blood spots by gas chromatography-mass spectrometry-selected ion monitoring

Smith-Lemli-Opitz syndrome (SLOS) patients have increased 7- and 8-dehydrocholesterol (DHC) concentrations. Using gas chromatography-mass spectrometry with selected ion monitoring we investigated whether storage time (24 h, 7 and 30 days, and 22 months at room temperature or at 4 degrees C) affected DHC concentrations in whole blood spots (WBSs) from SLOS patients and normal controls. Our results suggest that WBS sterol analysis can be used for SLOS screening and possibly related inborn errors of sterol metabolism with a 100% sensitivity and specificity on specimens stored for up to 30 days, either at room temperature or 4 degrees C. After 22 months of storage at both temperature SLOS samples can be indistinguishable from control samples. Therefore, great caution should be used to exclude SLOS by sterol analysis of WBSs stored for a long time.

Oxysterols in the circulation of patients with the Smith-Lemli-Opitz syndrome: abnormal levels of 24S- and 27-hydroxycholesterol

Infants with the cholesterol synthesis defect Smith- Lemli-Opitz syndrome (SLO) have reduced activity of the enzyme 7-dehydrocholesterol-7-reductase and accumulate 7-dehydrocholesterol, with the highest concentration in the brain. As a result of the generally reduced content of cholesterol, plasma levels of oxysterols would be expected to be reduced. 24S-hydroxycholesterol is almost exclusively formed in the brain, whereas 27-hydroxycholesterol is mainly formed from extrahepatic and extracerebral cholesterol. In accordance with the expectations, sterol-correlated plasma levels of 24S-hydroxycholesterol were reduced in infants with SLO (by about 50%). In contrast, the sterol-correlated levels of 27-hydroxycholesterol in the circulation were markedly increased. No side-chain oxidized metabolites of 7-dehydrocholesterol were detected in the circulation. Recombinant human CYP27 had markedly lower 27-hydroxylase activity toward 7-dehydrocholesterol than towards cholesterol. HEK293 cells expressing 24S-hydroxylase active toward cholesterol had no significant activity towards 7-dehydrocholesterol. The plasma levels of 3 beta,7 alpha-dihydroxy-5-cholestenoic in the patients acid were reduced, suggesting a generally reduced metabolism of 27-oxygenated steroids. It is concluded that the accumulation of 7-dehydrocholesterol in the brains of patients with SLO reduces formation of 24S-hydroxycholesterol. The condition is associated with markedly increased circulating levels of 27-hydroxycholesterol, most probably due to reduced metabolism of this oxysterol. We discuss the possibility that the circulating levels of 24S-hydroxycholesterol may be used as a marker for the severity of the disease.--Björkhem, I., L. Starck, U. Andersson, D. Lütjohann, S. von Bahr, I. Pikuleva, A. Babiker, and U. Diczfaulsy. Oxysterols in the circulation of patients with the Smith-Lemli-Opitz syndrome: abnormal levels of 24S- and 27-hydroxycholesterol. J. Lipid Res. 2001. 42: 366--371.

Simvastatin. A new therapeutic approach for Smith-Lemli-Opitz syndrome

The Smith-Lemli-Opitz syndrome (SLOS) is caused by deficient Delta(7)-dehydrocholesterol reductase, which catalyzes the final step of the cholesterol biosynthetic pathway, resulting in low cholesterol and high concentrations of its direct precursors 7-dehydrocholesterol (7DHC) and 8DHC. We hypothesized that i) 7DHC and 8DHC accumulation contributes to the poor outcome of SLOS patients and ii) blood exchange transfusions with hydroxymethylglutaryl (HMG)-CoA reductase inhibition would improve the precursor-to-cholesterol ratio and may improve the clinical outcome of SLO patients. First, an in vitro study was performed to study sterol exchange between plasma and erythrocyte membranes. Second, several exchange transfusions were carried out in vivo in two SLOS patients. Third, simvastatin was given for 23 and 14 months to two patients. The in vitro results illustrated rapid sterol exchange between plasma and erythrocyte membranes. The effect of exchange transfusion was impressive and prompt but the effect on plasma sterol levels lasted only for 3 days. In contrast, simvastatin treatment for several months demonstrated a lasting improvement of the precursor-to-cholesterol ratio in plasma, erythrocyte membranes, and cerebrospinal fluid (CSF). Plasma precursor concentrations decreased to 28 and 33% of the initial level, respectively, whereas the cholesterol concentration normalized by a more than twofold increase. During the follow-up period all morphometric parameters improved. The therapy was well tolerated and no unwanted clinical side effects occurred. This is the first study in which the blood cholesterol level in SLOS patients is normalized with a simultaneous significant decrease in precursor levels. There was a lasting biochemical improvement with encouraging clinical improvement. Statin therapy is a promising novel approach in SLOS that deserves further studies in larger series of patients.

Diagnosis of Smith-Lemli-Opitz syndrome from stored filter paper blood specimens

BACKGROUND

Smith-Lemli-Opitz (SLO) syndrome is a recessively inheritable metabolic disease with deficiency of cholesterol and accumulation of dehydrocholesterols, caused by a defect in the last step of cholesterol biosynthesis. Biochemical methods for identification of affected individuals, even prenatally, have been developed. Reliable genetic counselling is now possible.

AIM

To find a method of proving or disproving whether a child in whom SLO syndrome had been suspected but not confirmed during lifetime had in fact died of the SLO syndrome.

METHODS

Lipid extracts of stored filter paper blood specimens collected at the national neonatal metabolic screening were used. The ratio of dehydrocholesterols to cholesterol was measured by combined gas chromatography-mass spectrometry.

RESULTS

The ratio of 8-dehydrocholesterol to cholesterol in stored filter paper specimens clearly distinguished affected infants from normal infants. SLO syndrome was thus proven in two children who had died more than seven years earlier.

CONCLUSION

It is possible to diagnose SLO syndrome from dried paper specimens, even when the samples were collected more than a decade ago. Genetic counselling is available for families of affected children who died before the discovery of the defect in cholesterol synthesis.

Pitfalls in measuring plasma cholesterol in the Smith-Lemli-Opitz syndrome

Correct quantitative results for plasma cholesterol, 7-dehydrocholesterol (7-DHC), and 8-dehydrocholesterol (8-DHC) are invaluable for making the correct diagnosis in patients with the Smith-Lemli-Opitz syndrome (SLO) and for biochemical monitoring of these patients during therapy. The enzymatic method for cholesterol measurement based on cholesterol oxidase gives falsely high values for plasma cholesterol in samples from patients with SLO. Both 7-DHC and 8-DHC contribute substantially to the test result, given that they are accepted substrates of cholesterol oxidase. All cholesterol methods making use of this enzyme are expected to give unreliable results with plasma samples from SLO patients. Cholesterol values found with these methods may be low-normal in individual cases with SLO. Therefore, other techniques for measuring cholesterol, 7-DHC, and 8-DHC, e.g., gas chromatography, should be used for diagnosing these patients and for follow-up during therapy. However, a normal value for plasma cholesterol, as obtained by gas chromatography, does not exclude SLO. The diagnosis should always be confirmed or excluded by testing for the presence of high concentrations of 7-DHC and 8-DHC in plasma. We found that one patient with a severe form of the disease had a plasma cholesterol concentration of 20 micromol/L-to our knowledge, the lowest value ever recorded in a human being.

Changes in serum sterols of rats treated with 7-dehydrocholesterol-delta 7-reductase inhibitors: comparison to levels in humans with Smith-Lemli-Opitz syndrome

The impaired conversion of 7-dehydrocholesterol to cholesterol, as a result of a permanent inhibition of the activity of 7-dehydrocholesterol-delta 7-reductase, has been reported in the Smith-Lemli-Opitz (SLO) syndrome (1, 2). For the purpose of experimental teratology, an animal disease model consisting of the offspring of pregnant rats treated with AY 9944 or BM 15766, inhibitors of 7-dehydrocholesterol-delta 7-reductase, was established. The present study compares the profiles of sterols in rat serum, obtained after transient treatment with inhibitors, with profiles of sterols obtained from patients with the permanent enzyme defect. AY 9944 (single dose of 50, 75, or 100 mg/kg) or BM 15766 (60, 75, or 90 mg/kg per day for 11 days) induces hypocholesterolemia and accumulation of 7-dehydrocholesterol and aberrant sterols in rat serum. The aberrant sterols in the treated rats are similar to those detected in human SLO patients by gas chromatography coupled to mass spectrometry (1, 3, 4) and were identified as 7- and 8-dehydrocholesterol, two trienols (I and II), and 19-nor-5,7,9(10)-cholestatrien-3 beta-ol. The time- and dose-dependences of the biochemical alterations are compared to the teratogenic abnormalities induced by inhibitors. The dietary cholesterol supplementation that suppresses embryo malformations induced by AY 9944 prevents severe hypocholesterolemia and decreases the aberrant sterol levels. As a function of time after intoxication, the 8-dehydrocholesterol to 7-dehydrocholesterol ratio increases, suggested that 8-dehydrocholesterol is derived from the gradual conversion of the accumulated 7-dehydrocholesterol. The ratio of 8-dehydrocholesterol to 7-dehydrocholesterol is higher in human SLO than in the animal disease model. This may be explained by a permanent block in 7-dehydrocholesterol-delta 7-reductase in SLO compared to a transient inhibition of this enzyme in the animal model.

Identification of cholesta-3,5-dien-7-one by gas chromatography-mass spectrometry in the erythrocyte membrane of alcoholic patients

Lipids and oxidized lipids were analyzed by gas chromatography-mass spectrometry in the erythrocyte membranes of alcoholic and control subjects. Cholesta-3,5-dien-7-one and cholesta-trienes were detected in alcoholic samples examined, but not in significant amounts in controls. Levels of polyunsaturated fatty acids (arachidonic acid, 20:4; docosahexaenoic acid, 22:6; and docosatetraenoic acid, 22:4) in alcoholic samples declined significantly, whereas cholesta-3,5-dien-7-one levels increased. A high level of total bilirubin was observed in most patients. A possible mechanism of the accumulation of cholesta-3,5-dien-7-one in the erythrocyte membrane of alcoholics is discussed.

Identification of 19-nor-5,7,9(10)-cholestatrien-3 beta-ol in patients with Smith-Lemli-Opitz syndrome

We have identified the third unknown sterol in the plasma and tissues of Smith-Lemli-Opitz homozygotes as 19-nor-5,7,9(10)-cholestatrien-3 beta-ol. The structure was established from capillary gas-liquid chromatography retention index and characteristic fragmentation pattern by mass spectrometry that were identical to a synthetic reference standard. Evidence is presented that 19-nor-5,7,9(10)-cholestatrien-3 beta-ol is not an artifact formed during the chemical isolation of the relatively unstable 7-dehydrocholesterol. It is possible that 19-nor-5,7,9(10)-cholestatrien-3 beta-ol may contribute to the clinical abnormalities in patients with Smith-Lemli-Opitz syndrome.

Evaluation of bile acid malabsorption by plasma cholesterol precursor sterols in familial hypercholesterolaemia patients with and without ileal exclusion

To evaluate the value of plasma cholesterol precursor sterols in the detection of bile acid malabsorption we measured these sterols in 14 familial hypercholesterolaemia patients, seven with and seven without an ileal exclusion. In the operated subjects bile acid malabsorption had induced a 4.8-fold increase in cholesterol synthesis, accompanied by a 1.9-5.1-fold increase in the plasma content of the eight cholesterol precursor sterols studied. There was no overlap between the two groups in any of these sterols, when total and free sterols were considered, and only three of the esterified sterols overlapped. The tri- and dimethyl sterols were mostly unesterified, monomethyl sterols modestly esterified and the demethylated sterols, especially desmosterol, were mainly esterified. The plasma lathosterol content segregated most clearly the patients with bile acid malabsorption from the controls. The lowest lathosterol value of the operated patients was 2.5-fold higher than the highest value of the control patients. Because lathosterol is the most abundant of the plasma cholesterol precursor sterols and is relatively easy to quantitate, it is suggested that plasma lathosterol measurement can be used in the detection of bile acid malabsorption.

Measurement of blood levels of 7-dehydrocholesterol in man by high-performance liquid chromatography

A high-performance liquid chromatography procedure was established to measure 7-dehydrocholesterol (7DHC) in the blood. Interference studies were performed using 20 similar compounds likely to give analytical errors. 7DHC was extracted with a methanol chloroform mixture. Extraction recoveries were reproducible and acceptable, with low methodological variations from batch-to-batch. Results show that 7DHC is not detectable in the blood, contrary to the previous reports. Possible explanations for its absence in the blood are: (1) it is confined to the skin and is not present in the blood in this form; (2) because the molecule is labile, it is destroyed by the methods applied; (3) previous reports on 7DHC levels were based on non-specific methods.

C26 sterol in a human urine

A new C26 sterol, 22-trans-27-norcholesta-5,22-dien-3 beta-ol, was found in the urine of a 6-year-old girl, with a clinical diagnosis of congenital adrenal hyperplasia of the salt losing type, accompanied by symptoms of mixed sex anatomy and skin pigmentation. The structure of the sterol was determined by comparison with the synthetic compound. The sterol was also detected in ther serum. This appears to be the first case in which a C26 sterol has occurred in mammalia.

(2-Piperidine)- and (2-pyrrolidine)ethanones and -ethanols as inhibitors of blood platelet aggregation

(E)-4-[4-(Methylthio)phenyl]-1-(2-piperidinyl)-3-buten-2-one hydrochloride (44, RMI 14 133A) was found to inhibit ADP-induced aggregation of blood platelets. It was selected from a large series of (2-piperidinyl)- and (2-pyrrolidinyl)ethanones synthesized by a modified Schopf reaction from enolate magnesium salts of beta-keto acids and 2,3,4,5-tetrahydropyridine trimer or 3,4-dihydro-2H-pyrrole trimer, respectively. Evaluation of the compounds was carried out in vitro on human blood platelets. Structure-activity relationships are discussed. 44 also inhibited platelet aggregation ex vivo in guinea pigs. Subacute toxicity evaluation in dogs and guinea pigs showed it to have an unfavorable therapeutic ratio. 1-[4'-Chloro(1,1'-biphenyl)-4-yl-a1-2-(2-piperdinyl)ethanone hydrochloride (18, RMI 12436A) was found to lower serum cholesterol levles in rats with concurrent accumulation of (3beta)-cholesta-5,7-dien-3-ol, suggesting inhibition of 7-dehydrocholesterol delta7-reductase.

Contributions of other sterols to the estimation of cholesterol

The responses of 5alpha-cholestan-3beta-ol, 5alpha-cholest-7-ene-3beta-ol and cholesta-5,7-dien-3beta-ol, normally found in human serum, were examined by: (1) the Liebermann-Burchard reaction, (2) the Zak (ferric chloride) reaction, (3) an enzymatic cholesterol method monitored by estimating the amount of hydrogen peroxide produced, (4) an enzymatic cholesterol method monitored by observing the change in absorbance at 240 nm, and (5) gas chromatography. The results show that none of these methods is specific for cholesterol; contributions from the sterols examined range from zero to more than 150% relative to cholesterol. For the first four methods contributions depend on the conditions under which each test is performed.