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Experimental Neurology Nov 1985An abnormality in myoplasmic Ca2+ regulation has frequently been proposed in 20,25-diazacholesterol (20,25-D) myotonia. We report here the results of several studies of...
An abnormality in myoplasmic Ca2+ regulation has frequently been proposed in 20,25-diazacholesterol (20,25-D) myotonia. We report here the results of several studies of transmembrane Ca2+ movement in this animal model. (i) Physiologic Ca2+ release by intact sarcoplasmic reticulum (SR) was examined in chemically skinned single muscle fibers preloaded in EGTA-buffered Ca2+ solutions (pCa2+7.0 to 6.4). Isometric tension development and Ca2+ release thresholds in response to Cl- or caffeine showed no differences between control and 20,25-D fibers at any pCa2+. (ii) The kinetics of energy-dependent Ca2+ accumulation in purified SR vesicles were followed spectrophotometrically using Ca2+-sensitive dyes. The apparent rate for ATP-dependent Ca2+ uptake and Ca2+ sequestering capacity were unchanged in SR from 20,25-D animals vs. controls. (iii) Surface membrane Ca2+ATPase activity was measured in red blood cell ghosts and sarcolemma. Enzyme Vmax was decreased by 25 to 50% in both membranes in the 20,25-D-treated animals with a compensatory increase in the number of Ca2+ATPase molecules. In general, the SR handling of Ca2+ appears normal in 20,25-D myotonia, although the activity of Ca2+ATPase in membranes with high sterol content may be altered in response to changes in the lipid environment in this model.
Topics: Adenosine Triphosphate; Animals; Azacosterol; Caffeine; Calcium; Calcium-Transporting ATPases; Cell Membrane; Chlorides; Cholesterol; Egtazic Acid; Erythrocyte Membrane; Kinetics; Male; Myotonia; Rats; Rats, Inbred Strains; Sarcolemma; Sarcoplasmic Reticulum
PubMed: 2932344
DOI: 10.1016/0014-4886(85)90019-6 -
Molecular and Cellular Biochemistry Oct 1977The composition of skeletal muscle microsomes is reviewed. Evidence for the involvement of cholesterol in the transport of calcium by vesicles derived from the...
The composition of skeletal muscle microsomes is reviewed. Evidence for the involvement of cholesterol in the transport of calcium by vesicles derived from the sarcoplasmic reticulum is considered. Results obtained by non aqueous extractions of skeletal muscle microsomes, and by use of the cholesterol analogue 20, 25 diazacholesterol indicate that cholesterol is not involved in calcium transport by vesicles of sarcoplasmic reticulum origin. Use of density perturbation procedures indicating that cholesterol is present in muscle membranes other than those of the sarcoplasmic reticulum involved in calcium transport is discussed. The distribution of membranal cholesterol in muscle is compared to that in other tissues.
Topics: Adenosine Triphosphatases; Animals; Azacosterol; Biological Transport, Active; Calcium; Cholesterol; Membranes; Microsomes; Muscles; Sarcoplasmic Reticulum; Tissue Distribution
PubMed: 144866
DOI: 10.1007/BF01730831 -
Lipids Oct 1977Extended treatment of developing or adult rats with a variety of hypocholesterolemic drugs has shown that both the central nervous system (CNS) and peripheral nervous...
Extended treatment of developing or adult rats with a variety of hypocholesterolemic drugs has shown that both the central nervous system (CNS) and peripheral nervous system (PNS) sterol content could be affected in both age groups by this type of treatment. Treatment of developing animals was begun at 5 days of age and continued for 45 days. Adult rats, 300 g at onset, were treated for 35 days. The influence of these drugs on PNS sterol composition has not been previously examined. Diazacholesterol administration caused an accumulation of desmosterol in the CNS and 7-dehydrodesmosterol and desmosterol in the PNS. Zuclomiphene induced a build-up of desmosterol in either tissue. Both of these drugs had a more pronounced effect on developing CNS and PNS than on adult CNS and PNS. Addition of AY-9944 or Triparanol to the zuclomiphene treatment of the developing animals reduced desmosterol accumulation but brought about a build-up of 7-dehydrocholesterol and 7-dehydrodesmosterol.
Topics: Animals; Anticholesteremic Agents; Azacosterol; Central Nervous System; Clomiphene; Desmosterol; Female; Isomerism; Male; Peripheral Nerves; Rats; Sterols; Triparanol; trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride
PubMed: 72342
DOI: 10.1007/BF02533274 -
Annals of Neurology Sep 1981The electrophysiological characteristics of the myotonic syndrome produced in mammalian skeletal muscle by administration of 20,25-diazacholesterol (20,25-D) were...
The electrophysiological characteristics of the myotonic syndrome produced in mammalian skeletal muscle by administration of 20,25-diazacholesterol (20,25-D) were studied in detail. In vivo electromyographic recordings confirmed widespread repetitive electrical activity, but delayed relaxation was evanescent and required isotonic rather than isometric conditions, with long recovery periods between stimuli, for clear demonstration. Subsequent administration of a potent inhibitor of membrane chloride conductance (GCl) induced profound delays in relaxation different from that after chronic 20,25-D alone. Intracellular passive cable analysis revealed only a small decrease in membrane GCl and none in potassium conductance. Potassium current-voltage relationships did not differ in control and treated animals. Intracellular microelectrode recordings consistently showed multiple driven action potentials during long depolarizations but no spontaneous myotonic discharges after cessation of the stimulus. Variations in temperature, buffer, and external ionic concentrations also failed to produce spontaneous activity. Anode break excitation under mild depolarizing conditions, however, did elicit repetitive membrane electrical activity. The myotonia induced by 20,25-D is not due to low membrane GCl. The relationship between delayed mechanical relaxation and membrane repetitive electrical activity remains to be clearly established in this myotonic syndrome.
Topics: Action Potentials; Animals; Azacosterol; Electric Conductivity; Electromyography; Electrophysiology; In Vitro Techniques; Male; Membrane Potentials; Muscle Contraction; Muscles; Myotonia; Rats; Rats, Inbred Strains
PubMed: 7294732
DOI: 10.1002/ana.410100310 -
Journal of Neurology Mar 1979In both fast and slow muscles of rats treated with 20--25 diazacholesterol there were qualitative alterations, such as changes of fiber outlines, numerous moth-eaten...
In both fast and slow muscles of rats treated with 20--25 diazacholesterol there were qualitative alterations, such as changes of fiber outlines, numerous moth-eaten fibers and rare ring fibers. In addition there were generally larger groups of Type I and intermediate fibers than in normal controls ("type-grouping" tendency) in the preparations for oxidative enzymes in the extensor digitorum longus (EDL) of myotonic animals. Quantitative evaluations of EDL and soleus of myotonic rats revealed moderate hypothrophy of Type I and Type II fibers with an increase in the numbers of Type I and of Type III fibers in the EDL and a significant decrease of the nondominant fibers in the soleus muscle. The data are discussed in the light of a neurally mediated and/or direct action of the drug on the muscle fiber.
Topics: Animals; Azacosterol; Female; Mitochondria, Muscle; Muscles; Myotonia; Peripheral Nervous System Diseases; Rats; Staining and Labeling
PubMed: 87497
DOI: 10.1007/BF00313954 -
Experimental Neurology Apr 1978
Topics: Animals; Azacosterol; Cholesterol; Desmosterol; Female; Muscle, Smooth; Myotonic Dystrophy; Rats; Receptors, Cholinergic; Receptors, Muscarinic
PubMed: 639920
DOI: 10.1016/0014-4886(78)90157-7 -
Laboratory Investigation; a Journal of... May 1983Several drugs that interfere with sterol metabolism have been associated with hyperkeratosis in man. We found that 20,25-diazacholesterol (30 to 60 mg/kg/day),...
Several drugs that interfere with sterol metabolism have been associated with hyperkeratosis in man. We found that 20,25-diazacholesterol (30 to 60 mg/kg/day), administered to hairless mice that were otherwise given normal laboratory chow and water ad libitum, consistently produced ichthyosis after 6 to 9 weeks, an effect that was reversible with removal of drug or with coadministration of a high cholesterol diet. Scaling was most pronounced over the tail, but some stratum corneum retention was noted over the entire skin surface. As measured in frozen sections, stratum corneum thickness was three to 10 times thicker in treated animals than in either controls or revertants. Oil red O-stained frozen sections and freeze fracture replicas revealed decreased stratum corneum membrane lipids in the diazacholesterol-treated animals, but this finding was not specific, since a similar deficit was found in control and revertant tail stratum corneum but not in the stratum corneum from other sites. Stratum corneum lipid extracts revealed reduced total free sterols, reduced cholesterol, accumulation of several normally absent sterol precursors, and increased glycosphingolipids on thin-layer chromatography and high pressure liquid chromatography. In summary, we describe a syndrome of drug-induced ichthyosis in hairless mice that parallels the drug-induced syndrome in man. This syndrome is reversible and accompanied by distinctive abnormalities in cutaneous sterol metabolism. The diazacholesterol model may further our understanding of the pathogenesis of human keratinizing disorders and may provide a valuable analogue for testing new forms of therapy, such as retinoids, for scaling dermatoses.
Topics: Animals; Azacosterol; Cholesterol; Disease Models, Animal; Freeze Fracturing; Glycosphingolipids; Ichthyosis; Lipids; Male; Mice; Mice, Hairless; Skin; Tail
PubMed: 6843087
DOI: No ID Found -
Archives Internationales de... Mar 1965
Topics: Acetates; Acetoacetates; Adipose Tissue; Adrenal Glands; Anticholesteremic Agents; Azacosterol; Bile; Carbon Isotopes; Cholesterol; Chromatography; Fatty Acids; Humans; Hydroxybutyrates; Injections, Intraperitoneal; Lipid Metabolism; Liver; Male; Mevalonic Acid; Pharmacology; Phospholipids; Radiometry; Rats; Research; Sterols; Testis; Triparanol
PubMed: 14346416
DOI: No ID Found -
Cancer Research Jul 1981The effect of 20-methylcholanthrene and phorbol esters on sterol metabolism of mouse skin was studied. When 4 beta-phorbol esters were administered to mice that were...
The effect of 20-methylcholanthrene and phorbol esters on sterol metabolism of mouse skin was studied. When 4 beta-phorbol esters were administered to mice that were previously painted once with 20-methylcholanthrene, a depression of some sterols in skin occurred, of which that of lathosterol was most marked. This effect was not observed when the order of application was reversed. Using a metabolic inhibitor, diazacholesterol, it was shown that sterols which reduce in mouse skin by administration of carcinogen and promoters were similar to those which reduce by administration of carcinogen only and are the members of one of the two cholesterol-biosynthetic pathways, i.e., a pathway which proceeds through intermediates with a saturated side chain. The intensity of the lathosterol-depressing effect of phorbol esters depends on the order of application of 20-methylcholanthrene and promoters, the amount of promoters, molecular species of alcoholic moiety of esters, and configuration at C-4 of phorbol moiety. Of the phorbol esters tested, 4 beta-phorbol-12-myristate-13-acetate revealed the highest activity, which was followed by 4 beta-phorbol-12,13-didecanoate, 4 beta-phorbol-12,13-dibutyrate, 4 beta-phorbol-12,13-dibenzoate, 4 beta-phorbol-12,13-diacetate, 4 alpha-phorbol-12,13-didecanoate, and 4 alpha-phorbol. 4 alpha-Phorbol was practically inactive. When beta-naphthoflavone was substituted for 20-methylcholanthrene, little effect was observed except in TPA, which revealed a rather marked lathosterol-depressing activity. Phorbol esters themselves did show some activity of lathosterol depression without prior application of 20-methylcholanthrene, but the effects were much weaker. When anthralin was applied to mouse skin after the painting of 20-methylcholanthrene, a low but definite lathosterol-depressing effect was observed.
Topics: Administration, Topical; Animals; Anthralin; Azacosterol; Benzoflavones; Cholesterol; Chromatography, Gas; Chromatography, Thin Layer; Male; Methylcholanthrene; Mice; Mice, Inbred ICR; Phorbol Esters; Phorbols; Skin; Sterols; beta-Naphthoflavone
PubMed: 7248953
DOI: No ID Found -
Journal of Chromatography. B,... Oct 2017Wildlife contraceptives are an emerging tool for minimizing human-wildlife conflicts. One promising avian contraceptive compound, 20,25-diazacholesterol (DAC), reduces...
Wildlife contraceptives are an emerging tool for minimizing human-wildlife conflicts. One promising avian contraceptive compound, 20,25-diazacholesterol (DAC), reduces fertility by inhibiting cholesterol synthesis. A reliable analytical method for DAC was required in support of its registration for use as a reproductive control agent in pest bird species. A liquid chromatographic method employing tandem mass spectrometry (LC-MS/MS) was developed for the analysis of tissue extracts following solid phase extraction clean-up. Tissues analyzed were whole body samples from crows, monk parakeets, and quails and liver samples from crows and quails. Excellent sensitivity and selectivity was afforded by tandem mass spectrometry. The method accuracy of DAC from various tissue samples fortified at parts-per-million (ppm) and parts-per-billion (ppb) concentrations was high (>90%) with excellent precision (<10% relative standard deviation). Lower limits of detection were excellent in all tissues types, ranging from 1 to 11ppb in whole body matrices and 9.9-34ppb in liver matrices.
Topics: Animals; Azacosterol; Birds; Chromatography, High Pressure Liquid; Contraceptive Agents; Limit of Detection; Linear Models; Liver; Pest Control; Reproducibility of Results; Solid Phase Extraction; Tandem Mass Spectrometry; Tissue Distribution
PubMed: 28985619
DOI: 10.1016/j.jchromb.2017.09.028