RESUMO
Ancient schwannomas are benign tumours arising from the neural sheath of peripheral, cranial and autonomic nerves. They are commonly situated in the inner ear and spine with pelvic manifestations being rare. We present the case of a 30-year-old patient, who presented with an abdominal mass. MRI imaging suggested a broad ligament fibroid and open surgery was undertaken to remove it. Subsequent histology confirmed an ancient schwannoma. This case report details the rarity of such a condition and the need for a high index of suspicion as well as outlining management options and surveillance.
RESUMO
INTRODUCTION: Vaginal sacrospinous fixation and sacrospinous hysteropexy (SSF/SSHP) are highly effective procedures for apical compartment prolapse. The established technique is the posterior vaginal approach. The alternative anterior approach through an anterior vaginal incision, although occasionally mentioned in the literature, is less well established. However, this approach is a more appropriate route if posterior vaginal surgery is not indicated. The aim of this paper is to review surgical outcomes of anterior approach in our centre and to compare outcomes of SSF vs SSHP. METHODS: Retrospective case note review of 60 patients who underwent anterior SSF for prolapse between 2009-2017 was performed. Preoperative and postoperative symptoms and findings were recorded. Anterior SSF involved an anterior vaginal incision and paravaginal access to the ligament for dissection and fixation to either the cervix or vault. RESULTS: SSF was performed in 39 patients, out of which 8 underwent vaginal hysterectomy concomitantly. SSHP for uterine prolapse was performed in 21 patients. There were no cases of recurrent apical prolapse in the cohort at mean follow-up of 1 year. No intra-operative visceral injuries were observed. Recurrence of anterior wall prolapse and postoperative voiding dysfunction was observed in 8.3% and short-term buttock pain in 6.6% of patients. CONCLUSION: Anterior approach SSF and SSHP is a safe and effective technique for apical prolapse and is the recommended route when posterior vaginal surgery is not required.
RESUMO
AIM: To assess the clinical outcome of TOT tape for stress and mixed urinary incontinence in a single centre. METHODS: From March 2002 to October 2006, 82 patients completed the study, all were evaluated at 3 and 12 months by physical examination and validated questionnaires. Seventy nine patients had the procedure under epidural anaesthesia and all women received antibiotics starting before surgery. RESULTS: TOT was mostly performed as a day case surgery with short operative time of 22 minute (range 15-38 minute). A total of 62 (70.4%) patients were discharged from the hospital within a few hours (4.3 +/- 1.7 hours). CONCLUSION: The TOT tape can safely be performed as a day-case procedure, which has a continence cure rate of approximately 80%. This figure is comparable with the more established TVT, however the TOT tape has a significantly lower morbidity in our experience.
Assuntos
Slings Suburetrais , Incontinência Urinária por Estresse/cirurgia , Incontinência Urinária de Urgência/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Pessoa de Meia-Idade , Qualidade de Vida , Estudos Retrospectivos , Resultado do Tratamento , Procedimentos Cirúrgicos Urológicos/métodosRESUMO
This is a retrospective case series conducted in Worthing General Hospital to evaluate the clinical outcome of abdominal vault suspension (AVS) using rectus sheath strips to treat vaginal vault prolapse. Thirty-four patients had suspension of the vaginal vault using this procedure. Patients were followed up at 3-6 months and by questionnaire for up to 90 months. Incidence of intraoperative and postoperative complications, improvement of prolapsed symptoms and recurrence of vault prolapsed were the main outcome measures. There were no serious intraoperative complications. Ninety four percent of patients had subjective resolution of their prolapsed symptoms whereas 6% had further symptoms. Hospital stay ranged from 2 to 8 days. There were no cases of bowel problems in the postoperative period or in the long term. Hospital stay ranged from 2 to 8 days. AVS using rectus sheath strips appears to be a safer and easier alternative to other abdominal suspension procedures. The use of patients' own tissue eliminates the risk of mesh erosion.
Assuntos
Reto do Abdome/transplante , Prolapso Uterino/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Procedimentos Cirúrgicos em Ginecologia/métodos , Humanos , Tempo de Internação , Pessoa de Meia-Idade , Recidiva , Estudos Retrospectivos , Resultado do TratamentoRESUMO
In vivo inhibition of 2,3-oxidosqualene:lanosterol cyclase (OSC, E.C. 5.4.99.7)--the enzyme which catalyzes the cyclization of monooxidosqualene to lanosterol--does not result in elevated 3-hydroxy-3-methylglutaryl CoA reductase (HMGR) activity. This trait is attributed to increased levels of oxysterols, produced upon partial inhibition of OSC, that suppress HMGR and other sterol-responsive genes. The OSC inhibitor [4'-(6-allyl-ethyl-amino-hexyloxy)-2'-fluoro-phenyl]-(4-bromopheny l)-methanone (Ro 48-8071) was shown earlier to lower low-density lipoprotein (LDL) cholesterol in hamsters with no increase in hepatic HMGR, in contrast to simvastatin. To delineate the regulatory mechanism(s) by which Ro 48-8071 reduces cholesterol synthesis without raising HMGR levels, Syrian hamster C100 cells were incubated with either Ro 48-8071 or simvastatin, and their effects on cholesterol synthesis and LDL uptake, as well as on HMGR mRNA levels and rates of synthesis, were determined. Using RNase protection and radioimmunoprecipitation assays, we found that, in the absence of LDL in the culture medium, both HMGR mRNA levels and synthesis were reduced with concentrations of Ro 48-8071 inhibiting cholesterol synthesis by 50-75%, whereas LDL uptake was either reduced or unchanged. In contrast, simvastatin, at concentrations inhibiting cholesterol synthesis by the same 50-75%, increased both HMGR mRNA levels and synthesis, as well as LDL uptake. In the presence of LDL, HMGR mRNA levels and synthesis along with LDL uptake were little affected after incubation with Ro 48-8071. Still, simvastatin markedly increased both HMGR mRNA levels and synthesis in cells incubated in the presence of LDL, leaving LDL uptake unaffected. These data suggest that inhibition of OSC by Ro 48-8071 results in an indirect down-regulation of HMGR mRNA levels and synthesis.
Assuntos
Benzofenonas/farmacologia , Inibidores Enzimáticos/farmacologia , Hidroximetilglutaril-CoA Redutases/genética , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Transferases Intramoleculares/antagonistas & inibidores , RNA Mensageiro/análise , Sinvastatina/farmacologia , Animais , Células Cultivadas , Cricetinae , Regulação para Baixo , Hidroximetilglutaril-CoA Redutases/biossíntese , Lipoproteínas LDL/metabolismo , MesocricetusRESUMO
Recent data indicate that sterol carrier protein-2 (SCP-2) functions in the rapid movement of newly synthesized cholesterol to the plasma membrane (Puglielli, L., Rigotti, A., Greco, A. V., Santos, M. J., and Nervi, F. (1995) J. Biol. Chem. 270, 18723-18726). In order to further characterize the cellular function of SCP-2, we transfected McA-RH7777 rat hepatoma cells with a pre-SCP-2 cDNA expression construct. In stable transfectants, pre-SCP-2 processing resulted in an 8-fold increase in peroxisomal levels of SCP-2. SCP-2 overexpression increased the rates of newly synthesized cholesterol transfer to the plasma membrane and plasma membrane cholesterol internalization by 4-fold. There was no effect of SCP-2 overexpression on the microsomal levels of acyl-CoA:cholesterol acyltransferase and neutral cholesterol ester (CE) hydrolase; however, in the intact cell, CE synthesis and mass were reduced by 50%. SCP-2 overexpression also reduced high density lipoprotein-cholesterol secretion and apoA-I gene expression by 70% and doubled the rate of plasma membrane desmosterol conversion to cholesterol. We conclude that SCP-2 overexpression enhances the rate of cholesterol cycling, which reduces the availability of cholesterol for CE synthesis and alters the activity of a cellular cholesterol pool involved in regulating apoA-I-mediated high density lipoprotein cholesterol secretion. The net result of these changes in cholesterol metabolism is a 46% increase in plasma membrane cholesterol content, the implications of which are discussed.
Assuntos
Proteínas de Transporte/fisiologia , Ésteres do Colesterol/biossíntese , HDL-Colesterol/metabolismo , Proteínas de Plantas , Esteróis/metabolismo , Animais , Apolipoproteína A-I/metabolismo , Apolipoproteínas E/metabolismo , Membrana Celular/metabolismo , Hidroxicolesteróis/metabolismo , Fígado/metabolismo , Neoplasias Hepáticas Experimentais/metabolismo , Ratos , Esqualeno/metabolismo , Transfecção , Células Tumorais CultivadasRESUMO
Previously, we found that mevalonate-derived products together with an oxysterol regulated reductase synthesis at a posttranscriptional level. To determine which products were responsible for this regulation, either the squalene synthase inhibitor zaragozic acid A or the squalene cyclase inhibitor 4,4,10-beta-trimethyl-trans-decal-3beta-ol (TMD) was added to lovastatin-treated Syrian hamster cells in conjunction with mevalonate. Mevalonate alone decreased reductase synthesis 50% compared with lovastatin-treated cells. In contrast, when both zaragozic acid A and mevalonate were added to lovastatin-treated cells, there was no change in reductase synthesis. With either treatment, reductase mRNA levels did not change compared with lovastatin-treated cells. When both 25-hydroxycholesterol and mevalonate were added to lovastatin-treated cells, reductase synthesis and mRNA levels were decreased 95 and 50%, respectively. The 10-fold difference between changes in reductase synthesis and mRNA levels under these conditions reflects a specific effect of mevalonate-derived isoprenoids on reductase synthesis at the translational level. In contrast, coincubation of cells with mevalonate plus 25-hydroxycholesterol in the presence of zaragozic acid decreased reductase synthesis and mRNA levels 60 and 50%, respectively, compared with lovastatin-treated cells. Moreover, degradation of reductase was increased approximately 7-fold in cells treated with mevalonate alone but only 3-fold in cells treated with mevalonate and zaragozic acid A. These results indicate that isoprenoid products between mevalonate and squalene affect reductase at a posttranslational level by increasing degradation but do not regulate reductase synthesis at a posttranscriptional level. In contrast, when both TMD and mevalonate were added to lovastatin-treated cells, reductase synthesis was decreased approximately 50% with no corresponding decrease in reductase mRNA levels, similar to mevalonate only. Reductase degradation was increased approximately 7-fold under these conditions. Cellular incubation in TMD, mevalonate, and 25-hydroxycholesterol decreased reductase synthesis and mRNA levels 95 and 50%, respectively. From these results we concluded that mevalonate-derived nonsterols synthesized between squalene and lanosterol decrease reductase synthesis at a translational level-either alone or in combination with 25-hydroxycholesterol-and also increase reductase degradation.
Assuntos
Farnesil-Difosfato Farnesiltransferase/antagonistas & inibidores , Hidroximetilglutaril-CoA Redutases/biossíntese , Liases/antagonistas & inibidores , Ácido Mevalônico/farmacologia , Animais , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Linhagem Celular , Cricetinae , Inibidores Enzimáticos/farmacologia , Hidroxicolesteróis/farmacologia , Hidroximetilglutaril-CoA Redutases/genética , Hidroximetilglutaril-CoA Redutases/metabolismo , Lovastatina/farmacologia , Mesocricetus , Naftóis/farmacologia , Biossíntese de Proteínas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transcrição Gênica , Ácidos Tricarboxílicos/farmacologiaRESUMO
Transcripts for hamster 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase are heterogeneous in length. This heterogeneity is due to variations in the length of 5'-untranslated leader (UTL) sequences, which are generated by both alternate splicing within the first exon as well as alternate transcription start sites. Because mRNA 5'-UTL sequences have a role in regulating translational efficiency, the level and distribution of HMG-CoA reductase transcripts were measured in both total cellular RNA and polysomes from the Syrian hamster cell line C100. Cells were treated with either lovastatin alone, lovastatin and 25-hydroxycholesterol (25-OH C), or lovastatin, 25-OH C, and mevalonate, three treatment regimens used in an earlier study to demonstrate nonsterol-mediated translational control of HMG-CoA reductase synthesis [D. M. Peffley (1992) Somat. Cell Mol. Genet. 18, 19-32]. When reductase mRNA was measured by 5'-extension analysis under the same conditions, levels of transcripts with 5'-UTL regions ranging from 41 to 81 bases were reduced approximately four- to eightfold. In contrast, transcripts with 5'-UTL regions 93 to 100 bases in length were not reduced, and transcripts with 5'-UTL regions approximately 300-400 bases in length increased twofold. The addition of 25-OH C alone or both 25-OH C and mevalonate to lovastatin-treated cells lowered HMG-CoA reductase mRNA levels fivefold in total cellular RNA as determined by RNase protection assay. No comparable change was observed with control ribosomal protein S17 mRNA. Postmitochondrial supernatants representing both translationally inactive monosomes and translationally active polysomes were prepared by sucrose gradient fractionation from cells incubated with the standard three treatments. Because 5'-UTL sequences of many mRNAs have a role in regulating translational efficiency we isolated RNA from each fraction and measured levels of reductase transcripts by 5'-extension analysis. Under all three conditions, transcripts with 5'-UTL sequences 41-103 bases in length were primarily associated with dense sucrose fractions that contain polysomes. In contrast, reductase transcripts with leader sequences 300 to 400 bases were almost exclusively associated with the less dense sucrose fractions containing monosomes. These results indicate that both the level and polysome distribution of individual reductase transcripts are influenced by the length of 5'-UTL sequences.
Assuntos
Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Hidroximetilglutaril-CoA Redutases/genética , Biossíntese de Proteínas/efeitos dos fármacos , RNA Mensageiro/genética , Ribossomos/metabolismo , Processamento Alternativo , Animais , Sequência de Bases , Linhagem Celular , Cricetinae , DNA Complementar/genética , Hidroxicolesteróis/farmacologia , Lovastatina/farmacologia , Ácido Mevalônico/farmacologia , Dados de Sequência Molecular , Polirribossomos/metabolismo , Processamento Pós-Transcricional do RNA , RNA Mensageiro/classificação , Proteínas Ribossômicas/genética , Transcrição GênicaRESUMO
We reported previously that 3-hydroxy-3-methylglutaryl coenzyme A reductase synthesis is regulated at the translational level by mevalonate. To determine at what stage mevalonate affects reductase synthesis, we examined the distribution of reductase mRNA in polysomes from cells treated with lovastatin alone; lovastatin and 25-hydroxycholesterol; or lovastatin, 25-hydroxycholesterol, and mevalonate. In lovastatin-treated cells, reductase mRNA was primarily associated with heavy polysome fractions. When 25-hydroxycholesterol was added to lovastatin-treated cells, reductase mRNA levels were reduced approximately fourfold in all polysome fractions, with no accompanying redistribution of reductase mRNA into lighter polysome fractions. However, addition of both 25-hydroxycholesterol and mevalonate to lovastatin-treated cells shifted reductase mRNA from heavier to lighter polysome fractions. No change in the distribution of control beta-actin or ribosomal protein S17 mRNA occurred with any of the treatments. These results suggest that mevalonate suppresses reductase synthesis at the level of initiation. When the translation inhibitor cycloheximide was added to all three regimens, reductase mRNA shifted into heavy polysome fractions. Treatment with either lovastatin alone or lovastatin plus 25-hydroxycholesterol resulted in a 50% greater loss of reductase mRNA from the heavy polysome fractions compared to the same fractions from noncycloheximide-treated cells. No loss of reductase mRNA occurred when cycloheximide was added to cells treated with both 25-hydroxycholesterol and mevalonate. beta-Actin mRNA levels and polysome distribution were not significantly changed by cycloheximide under any of these conditions. Translationally mediated suppression of reductase mRNA did not occur when protein synthesis was inhibited with puromycin. Our results indicate that regulation of reductase mRNA levels is translation-dependent and is linked to the rate of elongation.
Assuntos
Regulação da Expressão Gênica/efeitos dos fármacos , Hidroximetilglutaril-CoA Redutases/genética , Ácido Mevalônico/farmacologia , Polirribossomos/metabolismo , RNA Mensageiro/metabolismo , Supressão Genética , Actinas/genética , Animais , Linhagem Celular , Cricetinae , Cicloeximida/farmacologia , Sinergismo Farmacológico , Hidroxicolesteróis/farmacologia , Hidroximetilglutaril-CoA Redutases/biossíntese , Inibidores de Hidroximetilglutaril-CoA Redutases , Lovastatina/farmacologia , Mesocricetus , Polirribossomos/enzimologia , Biossíntese de Proteínas , Processamento Pós-Transcricional do RNARESUMO
Isoxazole derivatives have been shown to possess antiparasitic activity. In the present study, 3-substituted 5-methylthio-isoxazoles were synthesized and tested for anthelmintic activity, along with some other isoxazoles which have been reported but not tested earlier. Nine compounds (2a, 2b, 2e, 2g, 2u, 3a, 3b, 3e and 3f) showed activity against both A. ceylanicum and N. dubius in vitro. Twelve compounds (2a, 2b, 2d, 2e, 2f, 2h, 2l, 2n, 2o, 2u, 3d and 3e) showed activity against N. dubius in vivo, a parasite of veterinary importance.
Assuntos
Anti-Helmínticos/síntese química , Isoxazóis/síntese química , Ancylostoma , Ancilostomíase/tratamento farmacológico , Ancilostomíase/psicologia , Animais , Anti-Helmínticos/farmacologia , Anti-Helmínticos/uso terapêutico , Cricetinae , Feminino , Himenolepíase/tratamento farmacológico , Himenolepíase/parasitologia , Hymenolepis , Isoxazóis/farmacologia , Isoxazóis/uso terapêutico , Masculino , Mesocricetus , Camundongos , Nematospiroides dubius , Nippostrongylus , Ratos , Estereoisomerismo , Infecções por Strongylida/tratamento farmacológico , Infecções por Strongylida/parasitologiaRESUMO
In order to determine whether hydration of the delta 24 bond of desmosterol contributes to the formation of the regulatory oxysterol, 25-hydroxycholesterol, [3H]desmosterol was incubated with two cultured cell lines and the labeled products were analyzed. Small amounts of 25-hydroxycholesterol were formed with Chinese hamster lung (Dede) cell cultures, but not with mouse fibroblast (L) cell cultures. Apparently, desmosterol was converted into cholesterol, a process that does not occur in L cells, before 25-hydroxycholesterol takes place. No reliable evidence could be obtained for hydration of the delta 24 bond or for the reverse reaction upon incubation of [3H]25-hydroxycholesterol. Oxygenation of desmosterol occurred in both Dede and L cell cultures to give a mixture of 24(R)- and 24(S)-25-epoxy-cholesterol. This reaction, along with the production of 7-oxygenated sterols, may account for low levels of HMG-CoA reductase repressor activity previously found to be associated with delta 24 sterols.
Assuntos
Colesterol/metabolismo , Desmosterol/metabolismo , Oxigênio/metabolismo , Animais , Células Cultivadas , Cromatografia Líquida de Alta Pressão , Cricetinae , Fibroblastos , Hidroxicolesteróis/metabolismo , Pulmão/citologia , Pulmão/metabolismo , Camundongos , Fatores de TempoRESUMO
Hepatic regulatory oxysterols were analyzed to determine which oxysterols were present in livers of mice fed a cholesterol-free diet and whether repression of 3-hydroxy-3-methylglutaryl-CoA reductase following cholesterol feeding was accompanied by an increase in one or more oxysterols. Analysis of free and esterified sterols from mice fed a cholesterol-free diet resulted in the identification and quantitation of six regulatory oxysterols: 24-hydroxycholesterol, 25-hydroxycholesterol, 26-hydroxycholesterol, 7 alpha-hydroxycholesterol, 7 beta-hydroxycholesterol, and 7-ketocholesterol. Following the addition of cholesterol to the diet for 1 or 2 nights, hepatic 3-hydroxy-3-methylglutaryl-CoA reductase activity declined and the levels of oxysterols, especially those of the side-chain-hydroxylated sterols, increased. Total 3-hydroxy-3-methylglutaryl-CoA reductase repressor units attributable to identified free oxysterols increased 2.5- and 6-fold after 1 and 2 nights, respectively, of cholesterol feeding. The amounts of esterified 24-, 25-, and 26-hydroxycholesterol also increased, with the increase in esterified 24-hydroxycholesterol being the greatest. The 24-hydroxycholesterol was predominantly the 24S epimer and the 26-hydroxycholesterol was predominantly the 25R epimer, indicating enzymatic catalysis of their formation. The observed correlation between increased levels of regulatory oxysterols and repression of 3-hydroxy-3-methylglutaryl-CoA reductase in cholesterol-fed mice is consistent with a hypothesis that intracellular oxysterol metabolites regulate the level of the reductase.
Assuntos
Colesterol na Dieta/fisiologia , Hidroxicolesteróis/fisiologia , Hidroximetilglutaril-CoA Redutases/metabolismo , Fígado/enzimologia , Animais , Cromatografia , Repressão Enzimática , Camundongos , Camundongos Endogâmicos C3HRESUMO
Previous studies on a somatic cell mutant auxotrophic for mevalonate (Mev-1) have shown that these cells rapidly lose viability when deprived of mevalonic acid in culture medium supplemented with serum cholesterol. Testing of all known end products of mevalonate metabolism in cultured mammalian cells has been conducted to determine the basis for this mevalonate requirement. It has been found that the recently discovered mevalonate metabolite 24(S),25-epoxycholesterol produces a partial restoration of viability of Mev-1 cells starved for mevalonate, whereas other structurally similar oxysterols do not. It appears that 24(S),25-epoxycholesterol has a specific, vital cellular function in CHO-K1 cells.
Assuntos
Colesterol/análogos & derivados , Fibroblastos/fisiologia , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Colesterol/farmacologia , Cricetinae , Fibroblastos/efeitos dos fármacos , Hidroxicolesteróis/farmacologia , Ácido Mevalônico/farmacologia , Ácido Mevalônico/fisiologiaRESUMO
In view of the potential importance of 24,25-epoxysterols as intracellular regulators of 3-hydroxy-3-methylglutaryl-CoA reductase, the C-24 epimers of 24,25-oxidolanosterol and 24,25-epoxycholesterol were tested for their biological activity and metabolism in cell cultures. All four compounds produced repression of the reductase in cultured mouse fibroblasts (L cells), and both 24(S)- and 24(R),25-epoxycholesterol exhibited high affinity binding to the cytosolic oxysterol-binding protein. However, binding of the epimeric 24,25-oxidolanosterols was not detected. 24(S),25-Epoxycholesterol was not rapidly metabolized in either L cells or Chinese hamster lung (Dede) cells. 24(S),25-Oxidolanosterol was rapidly converted to 24(S),25-epoxycholesterol in both cell lines. 24(R),25-Oxidolanosterol was converted to 24(R)-hydroxycholesterol in Dede cells, but was converted instead to 24(R),25-epoxycholesterol in L cells, which lack sterol delta 24-reductase activity. Although 24(S),25-oxidolanosterol does not appear to accumulate in these cell cultures, it was found in human liver in about one-fifth the amount of 24(S),25-epoxycholesterol. 24(R),25-Epoxycholesterol was also converted to 24(R)-hydroxycholesterol in Dede cells, but not in L cells. Triparanol inhibited the reduction of the 24(R),25-epoxides in Dede cells, consistent with the idea that this reaction is catalyzed by the delta 24-reductase. 24(R)-Hydroxycholesterol and its 24(S) epimer exhibited affinity for the binding protein and repressed 3-hydroxy-3-methylglutaryl-CoA reductase.
Assuntos
Colesterol/análogos & derivados , Hidroximetilglutaril-CoA Redutases/biossíntese , Lanosterol/análogos & derivados , Animais , Linhagem Celular , Colesterol/síntese química , Colesterol/metabolismo , Cromatografia Líquida de Alta Pressão , Repressão Enzimática , Células L/enzimologia , Lanosterol/síntese química , Lanosterol/metabolismo , Camundongos , TrítioRESUMO
Previously we showed that 24(S),25-epoxycholesterol is formed from acetate, via squalene 2,3(S),22(S),23-dioxide and 24(S),25-oxidolanosterol, during the normal course of cholesterol biosynthesis in S10 rat liver homogenate (Nelson, J. A., Steckbeck, S. R., and Spencer, T. A. (1981) J. Biol. Chem. 256, 1067-1068; Nelson, J. A., Steckbeck, S. R., and Spencer, T. A. (1981) J. Am. Chem. Soc. 103, 6974-6975). Herein we demonstrate that the nonsaponifiable extract from human liver tissue contains 24(S),25-epoxycholesterol in an amount approximately 10(-3) relative to cholesterol. We show that 24(S),25-epoxycholesterol, like many other oxygenated sterols, represses hydroxymethylglutaryl-CoA reductase activity in cultured cells and binds to the cytosolic oxysterol-binding protein. Furthermore, we show that this epoxide is not rapidly metabolized in cultured cells. These results suggest that 24(S),25-epoxycholesterol may participate in the regulation of hepatic cholesterol metabolism in vivo.
Assuntos
Colesterol/análogos & derivados , Colesterol/biossíntese , Fígado/metabolismo , Colesterol/análise , Colesterol/fisiologia , Cromatografia Líquida de Alta Pressão , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases , Fígado/análiseRESUMO
Biosynthetically tritiated sterols from Chinese hamster lung (Dede) cells were fractionated by high performance liquid chromatography, and fractions were assayed for their ability to repress 3-hydroxy-3-methylglutaryl-CoA reductase in L cell cultures. Most of the activity found was associated with two oxysterols, 24(S),25-epoxycholesterol and 25-hydroxycholesterol. The identities of the two sterols were established by co-chromatography with authentic samples and by isotopic dilution and recrystallization. Only low levels of repressor activity were found in other fractions of the sterol extract. The endogenous concentrations of 24(S),25-epoxycholesterol (7.2 fg/cell) and 25-hydroxycholesterol (1.5 fg/cell) appear to be within the ranges required for the regulation of HMG-CoA reductase.
Assuntos
Colesterol/análogos & derivados , Hidroxicolesteróis/biossíntese , Animais , Bovinos , Linhagem Celular , Colesterol/biossíntese , Cromatografia Líquida de Alta Pressão , Cromatografia em Camada Fina , Cricetinae , Cricetulus , Meios de Cultura , Repressão Enzimática , Feto , Fibroblastos/metabolismo , Hidroxicolesteróis/isolamento & purificação , Hidroxicolesteróis/farmacologia , Hidroximetilglutaril-CoA Redutases/biossíntese , Pulmão , Ácido Mevalônico/metabolismo , TrítioRESUMO
The hydroxylations of the cholesterol side chain at C-20, 22, and 25 are key terminal events in ecdysone biogenesis. We have prepared the C-20, C-22, C-24, and C-25 monofluorinated cholesterols as potential inhibitors of these hydroxylation events, and preliminary bioassay results in Manduca sexta are reported. The synthesis of [26(14)C]-20-fluorocholesterol is also described. Although the 20-, 22-, and 25-monofluorocholesterols do not appear to affect larval growth and development, the 24-fluoro isomer shows a moderate retardation of growth and a modest increase in mortality.
Assuntos
Colesterol/análogos & derivados , Ecdisona/biossíntese , Lepidópteros/metabolismo , Mariposas/metabolismo , Esteroides Fluorados/síntese química , Animais , Radioisótopos de Carbono , Colesterol/síntese química , Colesterol/metabolismo , Colesterol/farmacologia , Cromatografia Gasosa , Larva/efeitos dos fármacos , Larva/metabolismo , Espectroscopia de Ressonância Magnética , Esteroides Fluorados/metabolismo , Esteroides Fluorados/farmacologia , Relação Estrutura-AtividadeRESUMO
The penetration and fate of methomyl and its oxime metabolite, methomyl oxime or S-methyl N-hydroxythioacetimidate, were examined in house flies (Musca domestica Linnaeus), face flies (Musca autumnalis De Geer), black cutworm larvae (Agrotis ipsilon (Hufnagel), and twospotted spider mites (Tetranychus urticae Koch). Generally, penetration and metabolism of methomyl-1-14C were rapid in insects and spider mites although differences in rates among the different test organisms were observed. Metabolites from methomyl included CO2, methomyl oxime, and several unknowns. Penetration and metabolism of methomyl oxime-1-14C also were rapid in insects. Metabolites from methomyl oxime included a small amount of CO2 and several unidentified compounds. Organosoluble metabolites from methomyl oxime generally displayed similar chromatographic behavior as those from methomyl. Methomyl was hydrolyzed to its oxime metabolite, which, apparently, was further metabolized to 14CO2 presumably via a Beckmann rearrangement reaction.