Diagnosis of cerebrotendinous xanthomatosis (CTX) and effect of chenodeoxycholic acid therapy by analysis of urine using capillary gas chromatography

Pathophysiology and Treatment of Lipid Abnormalities in Cerebrotendinous Xanthomatosis: An Integrative Review

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive disorder caused by pathogenic variants in CYP27A1, leading to a deficiency in sterol 27-hydroxylase. This defect results in the accumulation of cholestanol and bile alcohols in various tissues, including the brain, tendons and peripheral nerves. We conducted this review to evaluate lipid profile abnormalities in patients with CTX. A search was conducted in PubMed, Embase and the Virtual Health Library in January 2023 to evaluate studies reporting the lipid profiles of CTX patients, including the levels of cholestanol, cholesterol and other lipids. Elevated levels of cholestanol were consistently observed. Most patients presented normal or low serum cholesterol levels. A decrease in chenodeoxycholic acid (CDCA) leads to increased synthesis of cholesterol metabolites, such as bile alcohols 23S-pentol and 25-tetrol 3-glucuronide, which may serve as surrogate follow-up markers in patients with CTX. Lipid abnormalities in CTX have clinical implications. Cholestanol deposition in tissues contributes to clinical manifestations, including neurological symptoms and tendon xanthomas. Dyslipidemia and abnormal cholesterol metabolism may also contribute to the increased risk of atherosclerosis and cardiovascular complications observed in some CTX patients.

The effectiveness of correcting abnormal metabolic profiles

Inborn errors of metabolism cause disease because of accumulation of a metabolite before the blocked step or deficiency of an essential metabolite downstream of the block. Treatments can be directed at reducing the levels of a toxic metabolite or correcting a metabolite deficiency. Many disorders have been treated successfully first in a single patient because we can measure the metabolites and adjust treatment to get them as close as possible to the normal range. Examples are drawn from Komrower's description of treatment of homocystinuria and the author's trials of treatment in bile acid synthesis disorders (3β-hydroxy-Δ⁵ -C₂₇ -steroid dehydrogenase deficiency and Δ⁴ -3-oxosteroid 5β-reductase deficiency), neurotransmitter amine disorders (aromatic L-amino acid decarboxylase [AADC] and tyrosine hydroxylase deficiencies), and vitamin B6 disorders (pyridox(am)ine phosphate oxidase deficiency and pyridoxine-dependent epilepsy [ALDH7A1 deficiency]). Sometimes follow-up shows there are milder and more severe forms of the disease and even variable clinical manifestations but by measuring the metabolites we can adjust the treatment to get the metabolites into the normal range. Biochemical measurements are not subject to placebo effects and will also show if the disorder is improving spontaneously. The hypothesis that can then be tested for clinical outcome is whether getting metabolite(s) into a target range leads to an improvement in an outcome parameter such as abnormal liver function tests, hypokinesia, epilepsy control etc. The metabolite-guided approach to treatment is an example of personalized medicine and is a better way of determining efficacy for disorders of variable severity than a randomized controlled clinical trial.

Cerebrotendinous xanthomatosis presenting with bilateral achilles tendon xanthomata: a case report

Xanthomas are described as deposits in the skin and subcutaneous tissues. Mostly known as pseudotumors, xanthomas consist of connective tissue containing mainly cholesterol, triglycerides, and numerous foamy macrophages. Bilateral Achilles tendon xanthomata is pathognomonic for cerebrotendinous xanthomatosis in the case of normal cholesterol levels but increased cholestanol levels in serum. In this article, we present findings regarding bilateral xanthomas of Achilles tendons in a patient with cerebrotendinous xanthomatosis.

Peroxisomes and bile acid biosynthesis

Peroxisomes play an important role in the biosynthesis of bile acids because a peroxisomal beta-oxidation step is required for the formation of the mature C24-bile acids from C27-bile acid intermediates. In addition, de novo synthesized bile acids are conjugated within the peroxisome. In this review, we describe the current state of knowledge about all aspects of peroxisomal function in bile acid biosynthesis in health and disease. The peroxisomal enzymes involved in the synthesis of bile acids have been identified, and the metabolic and pathologic consequences of a deficiency of one of these enzymes are discussed, including the potential role of nuclear receptors therein.

Defects in bile acid biosynthesis--diagnosis and treatment

Bile acid synthetic defects represent a specific category of metabolic liver disease. This article highlights the history and summarizes our analytical approach to the diagnosis and treatment of genetic defects in bile acid synthesis. By the application of mass spectrometry as a screening tool, it is possible to perform rapid diagnosis of potential inborn errors in bile acid synthesis from urinary bile acid analysis. Molecular techniques then afford the identification of specific mutations in genes encoding the enzymes responsible for bile acid synthesis. Using this approach, 6 of the 7 known genetic defects that are causes of progressive cholestatic liver disease, syndromes of fat-soluble vitamin malabsorption, or neurological disease, have been characterized. Bile-acid therapy using oral cholic acid has proven effective in most of these bile acid synthetic defects making early diagnosis crucial to optimum clinical prognosis.

Hydrophilic 7 beta-hydroxy bile acids, lovastatin, and cholestyramine are ineffective in the treatment of cerebrotendinous xanthomatosis

We compared the effect of treatments with hydrophilic bile acids (ursodeoxycholic and ursocholic acids), cholestyramine, and lovastatin versus chenodeoxycholic acid in 4 patients with cerebrotendinous xanthomatosis (CTX). Bile acids and bile alcohols in plasma, bile, and urine before and after treatment were quantitated by gas-liquid chromatography. Untreated, all patients showed abnormal biliary bile acid composition: cholic acid (72.7%) and chenodeoxycholic acid (6.2%), and polyhydroxylated C(27)-bile alcohols (10.0%), and elevated plasma cholestanol levels. Treatment with hydrophobic chenodeoxycholic acid inhibited abnormal bile acid synthesis (virtual disappearance of C(27)-bile alcohols from plasma, bile, and urine and marked reduction of plasma cholestanol levels). Hydrophilic ursodeoxycholic and ursocholic acids did not inhibit abnormal bile acid synthesis, while cholestyramine increased abnormal bile acid synthesis (continued increased formation of polyhydroxylated C(27)-bile alcohols and further elevation of plasma cholestanol levels). Lovastatin did not affect abnormal bile acid synthesis or reduce plasma cholestanol levels. The results demonstrate that impaired side-chain oxidation in bile acid synthesis due to mutations of Cyp27 results in increased formation of polyhydroxylated C(27)-bile alcohols and cholestanol in CTX. Hydrophobic chenodeoxycholic acid, but not cholestyramine, lovastatin, or hydrophilic 7beta-hydroxy acids, inhibited the abnormal synthetic pathway. The role of chenodeoxycholic acid in downregulating abnormal bile acid synthesis in CTX is emphasized.

Differential effects of streptozotocin-induced diabetes on expression of hepatic ABC-transporters in rats

BACKGROUND & AIMS

Diabetes mellitus is associated with changes in bile formation. The aim of our study was to investigate the molecular basis for these changes in rats with experimentally induced diabetes.

METHODS

Expression of bile canalicular transporters was studied by reverse-transcription polymerase chain reaction, immunoblotting, and immunohistochemistry in control, streptozotocin-diabetic, and insulin-treated diabetic rats. Bile formation was studied under basal conditions and during stepwise increasing intravenous infusion of taurocholate to determine bile salt secretory rate maximum (SRm).

RESULTS

In diabetic rats, hepatic gene and protein expression of the multidrug resistance P-glycoprotein type 2 (Mdr2) were increased by 105% and 530%, respectively, associated with increased biliary phospholipid output (+520%) and phospholipid/bile salt ratio (+77%). Protein levels of the canalicular bile salt export pump (Bsep) were unchanged in diabetic rats, but basal biliary bile salt output and the SRm of taurocholate were increased by 260% and 130%, respectively, compared with controls. Alterations in transporter expression and bile formation were partly reversed by insulin administration. The bile salt SRm was strongly correlated with biliary phospholipid concentration (P < 0.001, R = 0.82).

CONCLUSIONS

Induction of Mdr2 expression and biliary phospholipid secretion, rather than Bsep expression, appears to be responsible for the enhanced capacity of biliary bile salt secretion in experimentally induced diabetes.

Cerebrotendinous xanthomatosis: the spectrum of imaging findings and the correlation with neuropathologic findings

PURPOSE

To describe imaging findings and their neuropathologic correlate in patients with cerebrotendinous xanthomatosis (CTX).

MATERIALS AND METHODS

Computed tomographic (CT) and magnetic resonance (MR) images in 24 patients with symptoms (mean age at time of imaging, 37 years; mean disease duration, 18 years) were reviewed for site and frequency of brain, spinal cord, and Achilles tendon involvement. Two patients died, and imaging findings were compared with postmortem neuropathologic findings.

RESULTS

Apart from nonspecific supratentorial atrophy and deep white matter changes, more typical hyperintense lesions were seen on T2-weighted images in the dentate nucleus (in 79% of patients), globus pallidus, substantia nigra, and inferior olive and extended into adjacent white matter as disease progressed. In these locations, lipid crystal clefts and perivascular macrophages, neuronal loss, demyelination, fibrosis, and reactive astrocytosis were found at microscopic examination. Hypointensity was sometimes found on T2-weighted images in the dentate nucleus and was related to deposition of hemosiderin and calcifications. CT depicted fewer lesions; all had low attenuation, except for the calcifications. Spinal cord MR imaging revealed increased signal intensity in the lateral and dorsal columns on T2-weighted images. Achilles tendon xanthomas displayed intermediate signal intensity on T1- and T2-weighted images.

CONCLUSION

The typical pattern of MR imaging findings reflects the classic histopathologic findings and should prompt the diagnosis of CTX.

Cerebrotendinous xanthomatosis. Controversies about nerve and muscle: observations in ten patients

Neuromuscular characteristics were documented in ten patients with biochemically and genetically confirmed cerebrotendinous xanthomatosis. An array of genotypes was found in these patients. Only one patient complained of muscle weakness, while clinical signs of peripheral neuropathy were present in six patients. Electromyogram showed predominantly axonal neuropathy in seven patients. Neurogenic changes were seen in muscle biopsies of nine patients. Sural nerve biopsies of three patients showed features of axonal neuropathy. In addition, in one patient, extensive onion bulb formation was seen, which is indicative of a primarily demyelinating process. Five patients had normal mitochondrial respiratory chain enzyme activity. It is concluded that myopathy is not a feature of cerebrotendinous xanthomatosis and that the most prominent neuromuscular abnormality is sensorimotor axonal polyneuropathy.

Clinical and molecular genetic characteristics of patients with cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX) is a lipid storage disease caused by a deficiency of the mitochondrial enzyme 27-sterol hydroxylase (CYP 27), due to mutations in its gene. In this study we report on mutations in 58 patients with CTX out of 32 unrelated families. Eight of these were novel mutations, two of which were found together with two already known pathogenic mutations. Twelve mutations found in this patient group have been described in the literature. In the patients from 31 families, mutations were found in both alleles. In the literature, 28 mutations in 67 patients with CTX out of 44 families have been described. Pooling our patient group and the patients from the literature together, 37 different mutations in 125 patients out of 74 families were obtained. Identical mutations have been found in families from different ethnic backgrounds. In 41% of all the patients, CYP 27 gene mutations are found in the region of exons 6-8. This region encodes for adrenodoxin and haem binding sites of the protein. Of these 125 patients, a genotype-phenotype analysis was done for 79 homozygous patients harbouring 23 different mutations, out of 45 families. The patients with compound heterozygous mutations were left out of the genotype-phenotype analysis. The genotype-phenotype analysis did not reveal any correlation.

Aberrant oxidation of the cholesterol side chain in bile acid synthesis of sterol carrier protein-2/sterol carrier protein-x knockout mice

Peroxisomal beta-oxidation plays an important role in the metabolism of a wide range of substrates, including various fatty acids and the steroid side chain in bile acid synthesis. Two distinct thiolases have been implicated to function in peroxisomal beta-oxidation: the long known 41-kDa beta-ketothiolase identified by Hashimoto and co-workers (Hijikata, M., Ishii, N., Kagamiyama, H., Osumi, T., and Hashimoto, T. (1987) J. Biol. Chem. 262, 8151-8158) and the recently discovered 60-kDa SCPx thiolase, that consists of an N-terminal domain with beta-ketothiolase activity and a C-terminal moiety of sterol carrier protein-2 (SCP2, a lipid carrier or transfer protein). Recently, gene targeting of the SCP2/SCPx gene has shown in mice that the SCPx beta-ketothiolase is involved in peroxisomal beta-oxidation of 2-methyl-branched chain fatty acids like pristanic acid. In our present work we have investigated bile acid synthesis in the SCP2/SCPx knockout mice. Specific inhibition of beta-oxidation at the thiolytic cleavage step in bile acid synthesis is supported by our finding of pronounced accumulation in bile and serum from the knockout mice of 3alpha,7alpha, 12alpha-trihydroxy-27-nor-5beta-cholestane-24-one (which is a known bile alcohol derivative of the cholic acid synthetic intermediate 3alpha,7alpha,12alpha-trihydroxy-24-keto-cholestano yl-coenzyme A). Moreover, these mice have elevated concentrations of bile acids with shortened side chains (i.e. 23-norcholic acid and 23-norchenodeoxycholic acid), which may be produced via alpha- rather than beta-oxidation. Our results demonstrate that the SCPx thiolase is critical for beta-oxidation of the steroid side chain in conversion of cholesterol into bile acids.

Gas chromatography of bile acids

Bile acids, the end products of cholesterol metabolism in the liver, are of vital importance in the tissue distribution of cholesterol. Abnormalities in cholesterol biosynthesis or metabolism are often reflected in the proportions, concentrations and conjugation of bile acids in various tissues and determination of bile acids in these tissues is important in the diagnosis of hepatobiliary diseases. Several methods for quantitative determination of bile acids in biological fluids are known and have been reviewed. In this review, we have discussed the gas-chromatographic method for determination of bile acids with special reference to bile acid quantitation in plasma, bile, urine and stool.

Effect of simvastatin in addition to chenodeoxycholic acid in patients with cerebrotendinous xanthomatosis

The effects of combination therapy with chenodeoxycholic acid (CDCA) and simvastatin on serum cholestanol, low-density lipoprotein (LDL) cholesterol, and lathosterol levels were investigated in seven adult patients with cerebrotendinous xanthomatosis (CTX) who were on long-term treatment with CDCA. The patients were treated with a combination of CDCA 750 mg daily and an increasing dose of simvastatin from 10 mg to 40 mg daily for a period of 6 months. We found a significant effect of this combination therapy compared with CDCA alone in terms of decreasing the serum cholestanol and LDL cholesterol levels, particularly with a daily dose of 40 mg simvastatin. The mean cholestanol level decreased from 9.27 micromol/L (baseline) to 6.69 micromol/L (40 mg simvastatin), while the mean LDL cholesterol level decreased from 5.08 mmol/L (baseline) to 3.04 mmol/L (40 mg simvastatin). No side effects were reported, and there were no effects on the clinical condition, cerebral magnetic resonance imaging (MRI), visual evoked potentials, and electroencephalographic features. We conclude that a combination of 750 mg CDCA and 40 mg simvastatin daily is effective to further reduce serum cholestanol, LDL cholesterol, and lathosterol in adult CTX patients treated with long-term CDCA. Whether this combination treatment will be effective for the long-term prevention of neurological deterioration and atherosclerosis remains to be established.

Chronic diarrhoea as a dominating symptom in two children with cerebrotendinous xanthomatosis

The objective of this study was to describe diarrhoea as a dominating symptom of cerebrotendinous xanthomatosis (CTX), a lipid storage disease, and investigate its cause. Two children with chronic diarrhoea as the dominating symptom of CTX are presented. Before and after therapy with orally administered chenodeoxycholic acid (15 mg kg-1 24 h, in three divided doses) bile alcohol excretion in urine, serum cholestanol level, serum bile acid patterns and faecal bile acids were measured. All routine gastro-intestinal investigations before therapy were normal. Diarrhoea ceased immediately after starting treatment with chenodeoxycholic acid. Abnormal bile alcohol excretion in urine decreased rapidly during the first days and elevated serum cholestanol level normalized in 2 years. We postulate the presence of bile alcohols in the lumen of the gut as most likely cause for diarrhoea in CTX, since the rapid decrease of bile alcohol excretion is associated with prompt cessation of diarrhoea after starting treatment with chenodeoxycholic acid.

Ocular and systemic manifestations of cerebrotendinous xanthomatosis

PURPOSE

Cerebrotendinous xanthomatosis is a storage disease that usually leads to severe mental and neurologic deterioration before the diagnosis and start of treatment are established. We identified major ocular and systemic characteristics that may enable a diagnosis to be made earlier.

METHODS

Ten patients (group 1) of the University Hospital Nijmegen, with a diagnosis of cerebrotendinous xanthomatosis, were re-examined for detailed ocular and major clinical manifestations. Meanwhile, we looked for similar but undiagnosed cases in patients (group 2) who visited the Institute of Ophthalmology during a 12-month period.

RESULTS

A diagnosis of cerebrotendinous xanthomatosis had been made in the patients of group 1 at an average age of 40 years (range, 33 to 48 years). Subsequently, six new cases (group 2) were diagnosed in patients 7 to 37 years old (average age, 18 years). Bilateral cataract was the major ocular manifestation in all 16 patients. Small irregular corticonuclear opacities, anterior polar cataracts, and dense posterior subcapsular cataracts were diagnosed at various ages (mean, 18 years; range, 4 to 40 years). Four patients showed clinical signs of optic neuropathy, whereas retinal function was normal in all patients. Other major clinical signs included a history of chronic diarrhea (since childhood), mental deterioration (mean age, 23 years), neurologic deterioration (mean age, 31 years), and tendon xanthomas (mean age, 37 years).

CONCLUSIONS

Appropriate biochemical investigations for cerebrotendinous xanthomatosis should be performed in patients with unexplained juvenile or early-onset adult cataracts, especially if these cataracts are associated with chronic diarrhea since infancy, mental retardation or deterioration, neurologic dysfunction, or xanthomas.

Bile alcohol glucuronides: regioselective O-glucuronidation of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol and 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol

A facile and regiocontrolled procedure for the preparation of 5-beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol-3-O-beta-D-glucuronide and its corresponding C-26 analogue is described. The method involves direct coupling of bile alcohols, namely, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol and 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol to methyl (tetra-O-acetyl-beta-D-glucopyranuronate) in the presence of a Lewis acid, tin(IV) chloride, in dichloromethane. The resulting anomeric pairs of 1,2-trans- and 1,2-cis-glucuronides of tetrols were resolved by analytical and preparative thin-layer chromatography, and their identities were established by high-resolution 1H NMR spectroscopy and by chemical-ionization and fast-atom-bombardment mass spectrometry. The method described has a practical advantage over the traditional two-step synthesis involving bromides as it is more efficient and uses inexpensive and less toxic materials. It is suggested that these compounds will be useful for studying permeability of the blood-brain barrier in cerebrotendinous xanthomatosis (CTX).

Osteoporosis and increased bone fractures in cerebrotendinous xanthomatosis

Significant osteoporosis determined by skeleton radiography and bone densitometry was found in 15 patients with cerebrotendinous xanthomatosis (CTX) whose mean age was 31 +/- 11 years. In three CTX patients, bone biopsies confirmed osteoporosis. Nine patients also sustained bone fractures following minimal trauma. Serum 25-hydroxyvitamin D ([25-OHD] 14.6 +/- 6.6 ng/mL v [normal] 30.4 +/- 8.0 ng/mL; P < .001) and 24,25-dihydroxyvitamin D ([24,25(OH)2D] 1.2 +/- 0.4 ng/mL v [normal] 2.7 +/- 0.8 ng/mL; P < .001) levels were low. Serum concentrations of 1,25(OH)2D, calcium, inorganic phosphorus, alkaline phosphatase, parathyroid hormone, and calcitonin were normal. Patients showed classic manifestations of CTX, including dementia, pyramidal and cerebellar insufficiency, peripheral neuropathy, cataracts, and tendon xanthomas associated with elevated serum cholestanol concentrations. These results demonstrate that extensive osteoporosis and increased risk of bone fractures are components of this inherited disease.

Cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX) is a familial sterol storage disease based on an inborn error of metabolism involving bile acid synthesis. Predominant clinical features are a chronic progressive neurological syndrome, mental deterioration, bilateral cataract and xanthomas. The presence of xanthomas usually leads to the diagnosis, and the reverse is probably also true: without xanthomas the diagnosis will often not be made. CTX may therefore be less rare than commonly thought, and the incidence of xanthomas in CTX may be overestimated. Four cases without xanthomas among the presenting symptoms are described, and the relevance of xanthomas in CTX is discussed.

Identification of (23S)-5 alpha-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol in urine of patients with cerebrotendinous xanthomatosis

This paper describes the identification of a new bile alcohol possessing the 5 alpha-cholestane structure that was found in the urine of patients with cerebrotendinous xanthomatosis. The urine samples were extracted with reversed-phase resin, treated with beta-glucuronidase, and separated on silica gel and reversed-phase column chromatography. The new bile alcohol isolated was the second component of the urinary bile alcohols and was identified as (23S)-5 alpha-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol by means of gas-liquid chromatography/mass spectrometry and nuclear magnetic resonance spectroscopic studies.

Inborn errors of bile acid metabolism

Cholesterol is converted to cholic acid and chenodeoxycholic acid by a series of reactions involving modifications to the steroid nucleus and oxidation of the side chain. These reactions can be affected by a number of inborn errors of metabolism. When this happens unusual bile acids or bile alcohols are synthesized; these can be identified using gas chromatography-mass spectrometry and fast atom bombardment mass spectrometry techniques. Two defects affecting the modifications to the steroid nucleus have been described; both present with cholestatic liver disease of neonatal onset. The better characterized of the two--3 beta-hydroxy-delta 5-C27-steroid dehydrogenase deficiency--leads to excretion of 3 beta-7 alpha-dihydroxy-5-cholenoic acid and 3 beta,7 alpha,12 alpha-trihydroxy-5-cholenoic acid in the urine. The liver disease improves dramatically on treatment with chenodeoxycholic acid. Deficient activity of 3-oxo-delta 4-steroid 5 beta-reductase is thought to be the cause of familial liver disease in some infants who excrete 7 alpha-hydroxy-3-oxo-4-cholenoic acid and 7 alpha,12 alpha-dihydroxy-3-oxo-4-cholenoic acid in the urine. However, diagnosis of this disorder is problematical; a similar pattern of metabolite excretion can occur as a result of liver damage caused by viruses or inborn errors of pathways unrelated to bile acid synthesis. Defective side chain oxidation in patients with cerebrotendinous xanthomatosis (CTX) leads to synthesis of bile alcohols such as 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol and 5 beta-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol. Patients with CTX do not have cholestatic liver disease. Their major problems (neurological disease, atherosclerosis and xanthomata) are caused by accumulation of cholestanol and cholesterol in the tissues. Bile acid precursors are probably diverted into synthesis of cholestanol. Chenodeoxycholic acid suppresses the production of abnormal metabolites from cholesterol (by inhibition of cholesterol 7 alpha-hydroxylase) and leads to improvement in the neurological disease. Defective side chain oxidation also occurs in peroxisomal disorders but this time it leads to accumulation of C27 bile acids such as 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid (trihydroxycoprostanic acid, THCA). This compound is readily detected in the bile and plasma of patients with defects of peroxisome biogenesis. In patients with defects of a single peroxisomal beta-oxidation enzyme (the 3-hydroxyacyl-CoA component of the bifunctional protein or the thiolase), the major C27 bile acid in bile may be 3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestanoic acid (varanic acid).(ABSTRACT TRUNCATED AT 400 WORDS)

Reduction of urinary bile alcohol excretion and serum cholestanol in patients with cerebrotendinous xanthomatosis after oral administration of deoxycholic acid

Deoxycholic acid and chenodeoxycholic acid were administered alternately to four patients with cerebrotendinous xanthomatosis. During this oral therapy serum cholestanol and urinary bile alcohols were determined. Both showed a marked decrease after the start of the two different therapies. It can be concluded that not only chenodeoxycholic acid but also deoxycholic acid is able to suppress endogenous human bile acid synthesis, which is in accordance with other experiments describing the effect of feeding of various bile acids on endogenous bile acid synthesis.

Treatment of chronic liver disease caused by 3 beta-hydroxy-delta 5-C27-steroid dehydrogenase deficiency with chenodeoxycholic acid

Deficiency of 3 beta-hydroxy-delta 5-C27-steroid dehydrogenase, the second enzyme in the sequence that catalyses the synthesis of bile acids from cholesterol, leads to chronic liver disease in childhood as well as to malabsorption of fat and fat soluble vitamins. A 4 year old boy with this condition has been successfully treated by oral administration of a bile acid--chenodeoxycholic acid. He had been jaundiced since birth, grew poorly because of rickets, and had severe pruritus. Plasma transaminase activities were persistently raised. Chenodeoxycholic acid 125 mg twice daily for two months, and then 125 mg daily, cured his jaundice and pruritus, returned his transaminase activities to normal, and eliminated the need for calcitriol for prevention of rickets. On this treatment he has so far remained well for two years. A diagnosis of 3 beta-hydroxy-delta 5-C27-steroid dehydrogenase deficiency should be considered in any child with unexplained chronic hepatitis or cirrhosis, especially if the liver disease is accompanied by a clinically obvious malabsorption of fat soluble vitamins. A simple colorimetric test of the urine confirms the diagnosis and effective treatment can be started.

Cerebrotendinous xanthomatosis: clinical, electrophysiological and nerve biopsy findings, and response to treatment with chenodeoxycholic acid

A 30-year-old patient with cerebrotendinous xanthomatosis was studied over a 6-year period. The clinical manifestations were cataracts, intellectual deterioration, ataxia, palatal and pharyngeal myoclonus, corticospinal tract damage and an electrophysiologically demonstrated sensorimotor peripheral neuropathy. Peripheral motor and sensory nerve conduction velocity was slowed. Sural nerve biopsy revealed reduced densities of both myelinated and unmyelinated axons and teased fibres showed evidence of axonal regeneration and some remyelination. The loss of myelinated nerve fibres particularly affected those of larger diameter, thus contributing to the slowing of nerve conduction. Chenodeoxycholic acid treatment for two separate periods of 10 and 6 months each increased nerve conduction velocity. This electrophysiological improvement was not matched by detectable clinical neurological improvement.

Cerebrotendinous xanthomatosis

A case report on a 23-year-old female patient with cerebrotendinous xanthomatosis (CTX) is presented. From 8 years of age, the patient clinically showed multiple xanthoma masses on both knees, both heels, and the nasal bridge, juvenile cataracts, multiple abnormal neurologic dysfunctions, and dementia. The level of cholestanol in urine, serum, and xanthoma mass tissues was increased, as determined by capillary gas chromatography.

Use of positive ion fast atom bombardment mass spectrometry for rapid identification of a bile alcohol glucuronide isolated from cerebrotendinous xanthomatosis patients

The identification of a major biliary and plasma bile alcohol glucuronide, 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 25-tetrol-3-0-beta-D-glucuronide, present in cerebrotendinous xanthomatosis (CTX) patients, was investigated by positive ion fast atom bombardment mass spectrometry (FAB-MS). The spectrum was characterized by abundant ions formed by attachment of a proton, [M + H]+, or of alkali ions, [M + Na]+ and [M + 39K]+, to the glucuronide salt. These ions allowed an unambiguous deduction of the molecular weight of the sample. It is suggested that FAB-MS could be used in the rapid diagnosis of CTX.

Determination of cholic acid and chenodeoxycholic acid pool sizes and fractional turnover rates by means of stable isotope dilution technique, making use of deuterated cholic acid and chenodeoxycholic acid

A procedure is described for the simultaneous determination of cholic acid and chenodeoxycholic acid pool sizes and fractional turnover rates. After oral administration of known amounts of 11,12-dideuterated chenodeoxycholic acid and 2,2,4,4-tetradeuterated cholic acid, the ratios of chenodeoxycholic acid-D2/chenodeoxycholic acid and cholic acid-D4/cholic acid are measured in consecutive serum samples, after which fractional turnover rates and pool sizes of chenodeoxycholic acid and cholic acid are determined arithmetically. In 7 healthy volunteers pool sizes for chenodeoxycholic acid and cholic acid were 22.9 +/- 7.8 and 24.1 +/- 11.7 mumol/kg, respectively. The corresponding values for the fractional turnover rates were 0.23 +/- 0.10 and 0.29 +/- 0.12/day. After oral administration of the labelled bile acids in capsule, the obtained pool sizes were significantly higher than after administration in a bicarbonate solution. Bile acid kinetics were also performed in a patient suffering from a cholesterol synthesis deficiency and in a patient very likely suffering from a bile acid synthesis deficiency. Furthermore, the kinetics of the intestinal absorption and hepatic clearance of unconjugated bile acids have been investigated in 2 healthy subjects.

Identification of bile alcohols in serum from healthy humans

Bile alcohol glucuronides present in human serum were isolated by ion exchange chromatography on piperidino-hydroxypropyl Sephadex LH-20. Following hydrolysis with beta-glucuronidase, the bile alcohols were analyzed by a combination of gas-liquid chromatography and mass spectrometry. Bile alcohols identified were 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol, 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25,26-hexol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,26-pentol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25,26-pentol, and 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25,26-hexol. The bile alcohol composition in serum was similar to that in urine but not to that in bile. The concentration of total bile alcohols in serum was 59.5 +/- 24.6 micrograms/L.

Separate transport systems for biliary secretion of sulfated and unsulfated bile acids in the rat

Biliary secretion of 3 alpha-sulfated bile acids has been studied in Wistar rats with an autosomal recessive defect in the hepatic transport of bilirubin. Liver function, established by measurement of various enzymes in plasma, by enzyme histochemical methods, and by electron microscopy, appeared to be normal in these rats. Serum levels of unconjugated, monoglucuronidated, and diglucuronidated bilirubin were 0.62, 1.62, and 6.16 mumol/liter, respectively, compared with 0.17, 0.08, and 0.02 mumol/liter in control rats. Biliary bilirubin secretion was strongly reduced in the mutant animals: 0.21 +/- 0.03 vs. 0.39 +/- 0.03 nmol/min per 100 g body wt in control rats. Despite normal biliary bile acid output, bile flow was markedly impaired in the mutant animals, due to a 53% reduction of the bile acid-independent fraction of bile flow. The transport maximum for biliary secretion of dibromosulphthalein (DBSP) was also drastically reduced (-53%). Biliary secretion of intravenously administered trace amounts of the 3 alpha-sulfate esters of 14C-labeled taurocholic acid (-14%), taurochenodeoxycholic acid (-39%), taurolithocholic acid (-73%), and glycolithocholic acid (-91%) was impaired in the jaundiced rats compared with controls, in contrast to the biliary secretion of the unsulfated parent compounds. Hepatic uptake of sulfated glycolithocholic acid was not affected in the jaundiced animals. Preadministration of DBSP (15 mumol/100 g body wt) to normal Wistar rats significantly impaired the biliary secretion of sulfated glycolithocholic acid, but did not affect taurocholic acid secretion. We conclude that separate transport systems in the rat liver exist for biliary secretion of sulfated and unsulfated bile acids; the sulfates probably share secretory pathways with the organic anions bilirubin and DBSP. The described genetic defect in hepatic transport function is associated with a reduced capacity to secrete sulfated bile acids into bile; this becomes more pronounced with a decreasing number of hydroxyl groups on the sulfated bile acid's molecule.

Cerebrotendinous xanthomatosis: a review of biochemical findings of the patient population in The Netherlands

This study gives a review of the results obtained from biochemical investigations of 20 patients in The Netherlands suffering from cerebrotendinous xanthomatosis, an inborn error of metabolism in bile acid synthesis. Diagnosis can best be established by determining the excretion of urinary bile alcohols, in particular 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha,23,25-pentol, in urine by means of capillary gas chromatography. Measurement of serum cholestanol levels or serum cholestanol/cholesterol ratios, commonly used for establishing cerebrotendinous xanthomatosis, are not reliable. The effectiveness of the different therapies, i.e. administration of bile acids, can be evaluated by monitoring the urinary excretion of bile alcohols. From such investigations it was concluded that cholic acid especially, but also chenodeoxycholic acid are the therapies of choice for the treatment of cerebrotendinous xanthomatosis. All patients, until now diagnosed in The Netherlands were not discovered before the third or fourth decade of life because the characteristic signs only then become manifest clearly. Unfortunately, because sterol storage is almost irreversible, therapy only results in minor improvements of the patient's condition. Therefore early detection of the presence of cerebrotendinous xanthomatosis is desirable so that treatment can start before extensive storage of sterols is a fact. We developed some laboratory assays with the purpose of early detection. One consists of the detection of cerebrotendinous xanthomatosis carriers by subjecting them to oral cholestyramine administration and monitoring the urinary excretion of the bile alcohol 5 beta-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol before and after treatment. Secondly, a relatively simple screening test for cerebrotendinous xanthomatosis was developed based on an enzymatic assay of 7 alpha-hydroxylated steroids in urine. After suitable modification this assay in principle allows the screening of large populations for the existence of cerebrotendinous xanthomatosis and thus to detect the disease at an earlier stage of life.

Increased concentrations of cholestanol and apolipoprotein B in the cerebrospinal fluid of patients with cerebrotendinous xanthomatosis. Effect of chenodeoxycholic acid

We investigated the effect of chenodeoxycholic acid on cerebrospinal fluid sterol and protein composition in six patients with cerebrotendinous xanthomatosis, a progressive neurologic disease, and in 11 control subjects. In the cerebrospinal fluid from the controls, the mean (+/- SD) levels of cholesterol and cholestanol were 400 +/- 300 and 4 +/- 7 micrograms per deciliter, respectively. The levels were almost 1.5 and 20 times higher in cerebrospinal fluid from untreated patients with cerebrotendinous xanthomatosis. Cholestanol levels were also markedly elevated in the plasma of untreated patients, but their plasma cholesterol levels (215 +/- 61 mg per deciliter) were not different from control values. Treatment with chenodeoxycholic acid reduced cerebrospinal fluid cholesterol by 34 percent and cholestanol threefold. Plasma cholestanol levels also decreased sharply. Normal cerebrospinal fluid contained small quantities of albumin, apolipoproteins, and lecithin:cholesterol acyltransferase. In cerebrospinal fluid from untreated patients with cerebrotendinous xanthomatosis, immunoreactive apolipoprotein B or apolipoprotein B fragment was increased about 100-fold and albumin about 3.5-fold; apolipoprotein AI, apolipoprotein D, and lecithin:cholesterol acyltransferase were 1.5 to 3 times more concentrated. Apolipoprotein AIV and apolipoprotein E concentrations were comparable to those in controls, and apolipoprotein AII was considerably decreased. During treatment, the concentrations of albumin and apolipoproteins AI and B declined. These results suggest that increased cerebrospinal fluid sterols are derived from plasma lipoproteins by means of a defective blood-brain barrier in patients with cerebrotendinous xanthomatosis. Therapy with chenodeoxycholic acid reestablished selective permeability of the blood-brain barrier and normalized the concentrations of sterol and apolipoprotein in the cerebrospinal fluid.

Determination of some hydroxycholesterols in human serum samples

The simultaneous determination of some hydroxycholesterols in human serum samples is described. The procedure is based on hydrolysis and extraction of these compounds in serum samples, followed by removal of especially cholesterol (making use of reversed-phase high-performance liquid chromatography) and derivatization of the purified compounds to their trimethylsilyl ethers and subsequent gas chromatography using flame ionization detection. Serum levels of 7 alpha-hydroxycholesterol, 7 beta-hydroxycholesterol and 26-hydroxycholesterol were determined in several groups of patients: normals, untreated patients suffering from cerebrotendinous xanthomatosis, patients suffering from cerebrotendinous xanthomatosis and treated with either chenodeoxycholic acid or cholic acid in an effective dose, patients suffering from cerebro-hepato-renal syndrome, patients suffering from hypercholesterolemia and treated with cholestyramine for prolonged periods and one patient presumed to be suffering from an inborn error of metabolism in bile acid synthesis. It can be concluded that the 7 alpha-hydroxycholesterol concentration in serum is a good parameter for establishing disorders involving the metabolic conversion of 7 alpha-hydroxycholesterol towards bile acids. In addition, 26-hydroxycholesterol levels in patients suffering from cerebrotendinous xanthomatosis are beyond detectable limits, even during treatment with bile acids in an effective dose, whereas in all other conditions this compound is substantially present.

Abnormal urinary bile acids in a patient suffering from cerebrotendinous xanthomatosis during oral administration of ursodeoxycholic acid

The urinary bile acid profile, obtained by capillary gas chromatography, of a patient suffering from cerebrotendinous xanthomatosis and treated with ursodeoxycholic acid demonstrated, besides the occurrence of 23-norcholic acid and (23R)-hydroxycholic acid (as a consequence of this disease), six additional unknown bile acids and three known bile acids, viz. ursodeoxycholic acid, hyocholic acid and omega-muricholic acid. The structure of two of the unknown bile acids were elucidated and proven by organic syntheses. These were 23-norursodeoxycholic acid and 3 beta-ursodeoxycholic acid. The structures of three bile acids were tentatively elucidated as being 1 beta-hydroxyursodeoxycholic acid, 21-hydroxyursodeoxycholic acid and 22-hydroxyursodeoxycholic acid, and the possibility that the structure of the remaining bile acid is that of 5-hydroxyursodeoxycholic acid is discussed. Two of these bile acids (1 beta-hydroxyursodeoxycholic acid and 5-hydroxyursodeoxycholic acid) also occurred in urine of a healthy individual during oral ursodeoxycholic acid treatment, whereas 23-norcholic acid, 23-norursodeoxycholic acid, (23R)-hydroxycholic acid, 21-hydroxyursodeoxycholic acid and 22-hydroxyursodeoxycholic acid were only present in urine of the patient suffering from cerebrotendinous xanthomatosis. The metabolism of ursodeoxycholic acid, both in the normal state and in the cerebrotendinous xanthomatosis, is discussed.