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Radioiodinated Cholesterol as A Radiotracer in Biochemical Studies
Published in William C. Eckelman, Lelio G. Colombetti, Receptor-Binding Radiotracers, 2019
Raymond E. Counsell, Nancy Korn
LCAT is known to catalyze the transfer of the acyl group from the C-2 position of phosphatidyl choline to cholesterol — both of which are components of lipoproteins. The transferase prefers unsaturated fatty acids such as linoleate in humans and arachidonate in rats.9 Fewer studies have evaluated the sterol preference, but sterols other than cholesterol are capable of serving as acyl acceptors. Employing LCAT from human plasma, Piran and Nishida26 studied various sterols and concluded the following: The 3β-hydroxyl group was required since epicholesterol and epicholestanol were not substratesA trans rather than cis A/B ring configuration was required, since cholestanol and not coprostanol was readily esterifiedThe nature of the side-chain at C-17 was relatively unimportant, since androstan-3β-ol, which lacks a side-chain, was esterified as easily as cholesterol
Introduction to Human Cytochrome P450 Superfamily
Published in Shufeng Zhou, Cytochrome P450 2D6, 2018
Mutations in the CYP27A1 gene are known to be associated with cerebrotendinous xanthomatosis (CTX) (Bjorkhem 2013; Moghadasian 2004; Sundaram et al. 2008). CTX is a rare autosomal recessive lipid storage disorder in which cholestanol and cholesterol are accumulated in many tissues. CTX usually leads to tendon xanthoma, premature cataracts, juvenile atherosclerosis, and a progressive neurological syndrome involving mental retardation, cerebellar ataxia, pyramidal tract signs, myopathy, and peripheral neuropathy (Bjorkhem 2013; Moghadasian 2004; Sundaram et al. 2008). CYP27A1 is also a susceptibility gene for sporadic amyotrophic lateral sclerosis, which is a neurodegenerative disease characterized by progressive muscle weakness caused by loss of central and peripheral motor neurons (Diekstra et al. 2012).
Dementia Associated with Medical Conditions
Published in Marc E. Agronin, Alzheimer's Disease and Other Dementias, 2014
Three other rare demyelinating disorders that have been associated with cognitive impairment include adrenoleukodystrophy, an X-linked demyelinating disorder of the cerebral white matter that is caused by a deficiency of a peroxidase enzyme (Moser et al., 2004); metachromatic leukodystrophy, an inherited autosomal recessive demyelinating disorder that is related to a deficiency of arylsulfatase A (Shapiro, Lockman, Knopman, & Krivit, 1994); and cerebrotendinous xanthomatosis, an autosomal recessive disorder that causes increased levels of cholestanol because of the impaired hepatic synthesis of bile salts (Guyant-Maréchal, Verrips, & Girard, 2005).
Early diagnosis for cerebrotendinous xanthomatosis with juvenile cataract and family history
Published in Ophthalmic Genetics, 2023
Nurşen Öncel Acır, Burcu Taskiran Kandeger
The CYP27A1 mutation encoding the enzyme involved in bile acid synthesis results in the shifting of cholesterol to the cholestanol pathway (3). Clinical problems are caused by an increase in cholestanol and bile alcohols in the blood, urine, and feces, which then cross the blood-brain barrier and accumulate in various organs (15). Although cholestanol levels increase significantly in this disease, plasma cholesterol levels remain normal. Despite deposits in multiple organs, early-onset juvenile cataracts, and symptoms such as recurrent diarrhea episodes, the presence of cerebrotendinous xanthomatosis frequently remains misdiagnosed for years. However, with an early diagnosis of the disease, the production and plasma levels of cholestanol and bile alcohols decrease following the initiation of oral chenodeoxycholic acid (6,16). Moreover, the neurological complications of the disease can be prevented or even reversed (16). At this point, the early detection of the condition and the timing of the administration of chenodeoxycholic acid are critical. For this reason, juvenile cataract, which is one of the first symptoms, the morphology of the cataract, and the patient’s family history are of vital importance.
Genetic diseases mimicking multiple sclerosis
Published in Postgraduate Medicine, 2021
Chueh Lin Hsu, Piotr Iwanowski, Chueh Hsuan Hsu, Wojciech Kozubski
Symmetrical white matter hyperintensities around the dentate nuclei of the cerebellum are characteristic of CTX brain MRI [189,200]. Both white and gray matter volume are reduced, and can be best visualized under diffusion tensor imaging (DTI) and voxel- based morphometry. Thanks to the high sensitivity to water diffusion, DTI is helpful in sensing changes in the white matter tract [201]. Additional cord hyperintensities can be found in the T2 sequence of patients with spinal xanthomatosis [199]. MRI of the ankles show wedged thickening and hypointense mass on T1 and T2 sequences spanning the entire Achilles tendon [169,170,202,203]. Abnormally high levels of plasma cholestanol and urine bile alcohol, normal to low plasma cholesterol concentration with increased levels of both cholestanol and apolipoprotein B are specific biochemical findings of CTX patients [203].