Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
1.
BMC Complement Altern Med ; 18(1): 258, 2018 Sep 24.
Artículo en Inglés | MEDLINE | ID: mdl-30249222

RESUMEN

BACKGROUND: For decades, various cardiovascular symptoms have been relieved by the use of Ya-Hom Navakot, which is a formulation comprising 54 herbal medicines. The Thailand Ministry of Public Health listed Ya-Hom Navakot's nine active principle and nomenclative herbal ingredients and termed them 'Phikud Navakot' (PN). Several reports have confirmed that PN has cardiovascular benefits similar to Ya-Hom Navakot. However, whether PN facilitates lipid-lowering activity remains unclear. METHODS: The present study investigated an in vitro model for examining the gene expression levels of 3-hydroxyl-3-methylglutaryl-CoA reductase (HMGCR) and low-density lipoprotein receptor (LDL-R) in HepG2 cells using qRT-PCR. The ethanol and water extractions of Ya-Hom Navakot, PN and Ya-Hom Navakot without PN were compared. RESULTS: One mg/ml of both NYEF and NYWF were found to significantly lower cholesterol by either the up-regulation of LDL-R or down-regulation of HMGCR compared with negative controls and 1 mg/ml simvastatin (p < 0.05). PNEF also up-regulated LDL-R gene expression, even more than NYEF (p < 0.05). In addition, the ethanol and water extracts of PN significantly down-regulated HMGCR gene expression compared with those of Ya-Hom Navakot without PN (p < 0.05). CONCLUSION: The use of Ya-Hom Navakot or PN may provide an alternative treatment to lower cholesterol through HMGCR gene inhibition and LDL-R gene enhancement.


Asunto(s)
Anticolesterolemiantes/farmacología , Expresión Génica/efectos de los fármacos , Hidroximetilglutaril-CoA Reductasas/metabolismo , Extractos Vegetales/farmacología , Receptores de LDL/metabolismo , Anticolesterolemiantes/toxicidad , Colesterol/sangre , Células Hep G2 , Humanos , Hidroximetilglutaril-CoA Reductasas/análisis , Hidroximetilglutaril-CoA Reductasas/genética , Extractos Vegetales/toxicidad , Receptores de LDL/análisis , Receptores de LDL/genética , Simvastatina/farmacología
2.
Eur J Nutr ; 57(1): 405-415, 2018 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-28718016

RESUMEN

PURPOSES: We previously showed that polyphenol-rich blackcurrant extract (BCE) showed a hypocholesterolemic effect in mice fed a high fat diet. As direct cholesterol removal from the body via the intestine has been recently appreciated, we investigated the effect of BCE on the modulation of genes involved in intestinal cholesterol transport using Caco-2 cells as an in vitro model. METHODS: Caco-2 cells were treated with BCE to determine its effects on mRNA and protein expression of genes important for intestinal cholesterol transport, low-density lipoprotein (LDL) uptake, cellular cholesterol content, and cholesterol transport from basolateral to apical membrane of Caco-2 cell monolayers. Cells were also treated with anthocyanin-rich or -poor fraction of BCE to determine the role of anthocyanin on BCE effects. RESULTS: BCE significantly increased protein levels of LDL receptor (LDLR) without altering its mRNA, which consequently increased LDL uptake into Caco-2 cells. This post-transcriptional induction of LDLR by BCE was markedly attenuated in the presence of rapamycin, an inhibitor of mechanistic target of rapamycin complex 1 (mTORC1). In addition, BCE altered genes involved in cholesterol transport in the enterocytes, including apical and basolateral cholesterol transporters, in such a way that could enhance cholesterol flux from the basolateral to apical side of the enterocytes. Indeed, BCE significantly increased the flux of LDL-derived cholesterol from the basolateral to the apical chamber of Caco-2 monolayer. LDLR protein levels were markedly increased by anthocyanin-rich fraction, but not by anthocyanin-free fraction. CONCLUSION: mTORC1-dependent post-transcriptional induction of LDLR by BCE anthocyanins drove the transport of LDL-derived cholesterol to the apical side of the enterocytes. This may represent a potential mechanism for the hypocholesterolemic effect of BCE.


Asunto(s)
Antocianinas/farmacología , Colesterol/metabolismo , Frutas/química , Extractos Vegetales/farmacología , Receptores de LDL/genética , Ribes , Transporte Biológico/efectos de los fármacos , Transporte Biológico/genética , Células CACO-2 , LDL-Colesterol/metabolismo , Enterocitos/metabolismo , Expresión Génica/efectos de los fármacos , Humanos , Diana Mecanicista del Complejo 1 de la Rapamicina/antagonistas & inhibidores , Diana Mecanicista del Complejo 1 de la Rapamicina/fisiología , ARN Mensajero/análisis , Receptores de LDL/análisis , Receptores de LDL/efectos de los fármacos , Sirolimus/farmacología , Transcripción Genética/efectos de los fármacos
3.
Food Chem ; 169: 59-64, 2015 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-25236198

RESUMEN

Since saving time and money are critical issues while developing innovative functional foods and nutraceutics, the use of specific and high-throughput assays for the fast screening of potentially bioactive ingredients is crucial. In this context, the aim of the present investigation was the development of an in-cell Western (ICW) assay, a quantitative colorimetric cell-based technique, at the HepG2 cell line for screening and evaluating the effects of potentially bioactive compounds on the low density lipoprotein (LDL) receptor (LDLR). It is known that LDLR plays a pivotal role in the binding and endocytosis of circulating LDL, increasing its plasma clearance. The ICW was optimised and validated using monacolin K, the main hypocholesterolemic component of red yeast rice. This provided a robust and reproducible assay useful for characterising the cholesterol-lowering properties of bioactive food components. To our knowledge, this is the first application of the ICW technique in the field of functional foods and nutraceutics.


Asunto(s)
Anticolesterolemiantes/química , Células/química , Colesterol/metabolismo , Colorimetría/métodos , Suplementos Dietéticos/análisis , Ensayos Analíticos de Alto Rendimiento/métodos , Anticolesterolemiantes/farmacología , Células/efectos de los fármacos , Células/metabolismo , Endocitosis , Células Hep G2 , Humanos , Receptores de LDL/análisis , Receptores de LDL/metabolismo
4.
Chin J Integr Med ; 14(1): 71-5, 2008 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-18568331

RESUMEN

Hyperlipidemia (HLP) is the No.1 risk factor for patients with atherosclerosis (AS) and is directly related to the occurrence of coronary artery disease (CAD) and cerebrovascular disease. Therefore, prevention and treatment of AS is of great importance and of practical significance in controlling the incidence and mortality of CAD. With its peculiar syndrome-dependent therapy, traditional Chinese medicine (TCM) has accumulated abundant practical experiences in this field and good clinical effects have been achieved. Chinese herbal medicine, with its particularly unique advantages and high potentials yet to be tapped, displays its huge strength in HLP prevention and treatment. The progress of studies concerning prevention and treatment of HLP by Chinese herbal medicines, in the form of monomers or compound recipes, is reviewed in this paper.


Asunto(s)
Medicamentos Herbarios Chinos/uso terapéutico , Hiperlipidemias/tratamiento farmacológico , Colesterol/metabolismo , Humanos , Metabolismo de los Lípidos , Peroxidación de Lípido , Receptores de LDL/análisis
5.
Mol Nutr Food Res ; 52(8): 950-8, 2008 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-18496813

RESUMEN

Previous reports demonstrated that hypocholesterolemic activity of apple was associated with its pectin and fiber. This report was to investigate the effect of apple polyphenols (AP) on blood cholesterol level and gene expression of cholesterol-regulating enzymes in Golden Syrian hamsters maintained on a 0.1% cholesterol diet. It was found that dietary supplementation of 0.3 or 0.6% of AP did not affect plasma total cholesterol (TC), but it increased HDL cholesterol (HDL-C) and decreased non-HDL-C, thus leading to a lower ratio of non-HDL-C to HDL-C. Plasma total triacylglycerol (TG) level was also significantly reduced when hamsters were fed a diet supplemented with 0.6% AP. Western blot analysis did not find any effect of AP on sterol regulatory element-binding protein 2 (SREBP-2), LDL receptor (LDLR), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), and cholesterol-7alpha-hydroxylase (CYP7A). Most interesting was that supplementation of AP had no effect on protein abundance of plasma cholesteryl ester transport protein (CETP), but it suppressed plasma CETP activity. A series of in vitro assays confirmed that AP inhibited CETP in a dose dependent manner. It was concluded that AP favorably improved distribution of cholesterol in lipoproteins, most likely, by its inhibition on CETP activity.


Asunto(s)
Proteínas de Transferencia de Ésteres de Colesterol/sangre , HDL-Colesterol/sangre , Colesterol/sangre , Flavonoides/farmacología , Malus/química , Fenoles/farmacología , Animales , Western Blotting , Cricetinae , Ingestión de Alimentos/efectos de los fármacos , Heces/química , Hidroximetilglutaril-CoA Reductasas/análisis , Masculino , Mesocricetus , Tamaño de los Órganos/efectos de los fármacos , Polifenoles , Receptores de LDL/análisis , Proteína 2 de Unión a Elementos Reguladores de Esteroles/análisis , Aumento de Peso/efectos de los fármacos
6.
J Nutr ; 135(11): 2541-5, 2005 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-16251608

RESUMEN

The objective of this study was to investigate the effect of individual PUFAs on LDL receptor (LDLr) expression in human fibroblasts and HepG2 cells, and to evaluate whether acyl CoA:cholesterol acyltransferase (ACAT) and sterol regulatory element-binding protein 1 (SREBP-1) were involved in the regulation of LDLr expression by fatty acids. When fibroblasts and HepG2 cells were cultured with serum-free defined medium for 48 h, there was a 3- to 5-fold (P < 0.05) increase in LDLr protein and mRNA levels. Incubation of fibroblasts and HepG2 cells in serum-free medium supplemented with 25-hydroxycholesterol (25OH-cholesterol, 5 mg/L) for 24 h decreased LDLr protein and mRNA levels by 50-90% (P < 0.05). Arachidonic acid [AA, 20:4(n-6)], EPA [20:5(n-3)], and DHA [22:6(n-3)] antagonized the depression of LDLr gene expression by 25OH-cholesterol and increased LDLr protein abundance 1- to 3-fold (P < 0.05), but had no significant effects on LDLr mRNA levels. Oleic (18:1), linoleic (18:2), and alpha-linolenic acids [18:3(n-3)] did not significantly affect LDLr expression. ACAT inhibitor (58-035, 1 mg/L) attenuated the regulatory effect of AA on LDLr protein abundance by approximately 40% (P < 0.05), but did not modify the regulatory effects of other unsaturated fatty acids in HepG2 cells. The present results suggest that AA, EPA, and DHA increase LDLr protein levels, and that ACAT plays a role in modulating the effects of AA on LDLr protein levels. Furthermore, the effects of the fatty acids appeared to be independent of any change in SREBP-1 protein.


Asunto(s)
Ácidos Grasos Insaturados/farmacología , Fibroblastos/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Receptores de LDL/genética , Ácido Araquidónico/farmacología , Línea Celular Tumoral , Células Cultivadas , Medios de Cultivo , Ácidos Docosahexaenoicos/farmacología , Ácido Eicosapentaenoico/farmacología , Humanos , Hidroxicolesteroles/administración & dosificación , ARN Mensajero/análisis , Receptores de LDL/análisis , Esterol O-Aciltransferasa/antagonistas & inhibidores , Esterol O-Aciltransferasa/metabolismo , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/metabolismo
7.
J Nutr ; 134(1): 18-23, 2004 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-14704287

RESUMEN

White lupin (Lupinus albus, L.), a widely cultivated crop that has been consumed for many years in Western Europe, may provide a useful alternative for individuals wishing to substitute animal with plant proteins for cardiovascular disease prevention. Lupin seeds have a very low content of isoflavones, and lupin protein isolates are essentially isoflavone free. In rats fed a casein-based cholesterol + cholic acid diet, a relatively low daily intake (50 mg/d by gavage for 2 wk) of total lupin protein extract reduced plasma total and VLDL + LDL cholesterol concentrations by 21 and 30%, respectively (both P<0.001). In an attempt to elucidate the lipid-lowering mechanism, LDL receptor activity was evaluated in a human hepatoma cell line (HepG2). In this model, the lupin total protein extract was essentially inactive, whereas one purified minor protein component, conglutin gamma, had a remarkable upregulatory effect, with maximal increases of 53 and 21% (both P<0.05) for LDL uptake and degradation, respectively. This initial study indicates that lupin, although isoflavone free, has hypocholesterolemic activity similar to that of other leguminous proteins in an established animal model. Further, the cholesterol reduction appears to be associated with stimulation of LDL receptors by a well-defined protein component of the lupin seeds as demonstrated by in vitro studies.


Asunto(s)
Anticolesterolemiantes/farmacología , Colesterol/sangre , Hígado/química , Lupinus/química , Extractos Vegetales/administración & dosificación , Proteínas de Plantas/administración & dosificación , Receptores de LDL/análisis , Semillas/química , Animales , Carcinoma Hepatocelular , Caseínas/administración & dosificación , Colesterol en la Dieta/administración & dosificación , Ácido Cólico/administración & dosificación , Hipercolesterolemia/etiología , Isoflavonas/análisis , Neoplasias Hepáticas , Masculino , Ratas , Ratas Sprague-Dawley , Células Tumorales Cultivadas
8.
J Nutr ; 134(1): 68-71, 2004 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-14704295

RESUMEN

Conjugated linoleic acid (CLA) exerts anticarcinogenic and antiatherosclerotic effects in animals. The present study was conducted to examine the effects of CLA on LDL receptor (LDLr) expression in HepG2 cells, and to evaluate whether the sterol response element binding protein 1 (SREBP-1) and acyl CoA:cholesterol acyltransferase (ACAT) were involved in the regulation of LDLr expression by CLA. When HepG2 cells were cultured with serum-free DMEM for 48 h, there was a three- to fivefold (P<0.05) increase in LDLr protein and mRNA levels. Incubation of HepG2 cells in serum-free medium supplemented with 25-hydroxycholesterol (25OH, 5 mg/L) for 24 h decreased LDLr protein and mRNA by 50-70% (P<0.05) and mature SREBP-1 by 20-40% (P<0.05). CLA, but not linoleic acid, antagonized the depressive effects of 25OH and increased both LDLr protein and mRNA abundance twofold (P<0.05). LDLr protein and mRNA abundance were not different when HepG2 cells were cultured with CLA (0.4 mmol/L) plus 25OH in the presence or absence of an ACAT inhibitor (58-035, 1 mg/L). Furthermore, CLA had no effect on SREBP-1 abundance. These results suggest that CLA upregulates LDLr expression via a mechanism that is independent of ACAT and SREBP-1.


Asunto(s)
Regulación de la Expresión Génica/efectos de los fármacos , Ácidos Linoleicos Conjugados/farmacología , Receptores de LDL/genética , Factores de Transcripción , Western Blotting , Proteínas Potenciadoras de Unión a CCAAT/análisis , Carcinoma Hepatocelular/química , Medio de Cultivo Libre de Suero , Proteínas de Unión al ADN/análisis , Ácidos Grasos/análisis , Ácidos Grasos/farmacología , Humanos , Hidroxicolesteroles/farmacología , Neoplasias Hepáticas/química , ARN Mensajero/análisis , Receptores de LDL/análisis , Esterol O-Aciltransferasa/antagonistas & inhibidores , Proteína 1 de Unión a los Elementos Reguladores de Esteroles , Células Tumorales Cultivadas
9.
Kidney Int ; 61(1): 113-24, 2002 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11786091

RESUMEN

BACKGROUND: Progression of diabetic nephropathy is closely associated with morphological changes in glomeruli, such as thickening of the glomerular basement membrane, mesangial expansion, and glomerulosclerosis. To elucidate early glomerular events, we compared the mitogenic activity and extracellular matrix production in mesangial cells (MC) isolated from diabetic rats prior to the manifestation of nephropathy and those showing overt nephropathy. This study may help to clarify the mechanisms underlying diabetic nephropathy and provide clues about early therapeutic interventions for preventing or slowing this process. METHODS: Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a chronic model for human type 2 diabetes mellitus, and age-matched control (LETO) rats were used. Glomerular cell numbers, expression of immediate early genes (c-Fos and c-Myc) and proliferating cell nuclear antigen (PCNA), and low-density lipoprotein (LDL) deposition were determined in renal tissue sections from rats aged 15 to 75 weeks. Mesangial cells (MCs) from OLETF rats at two different stages of the disease, that is, young (12- to 14-week-old) OLETF rats (y-OLETF) prior to the manifestation of nephropathy and old (48- to 50-week-old) OLETF rats (o-OLETF) showing nephropathy, were isolated and cultured. After stimulation with native (n-) or oxidized (ox-) LDL or angiotensin II (Ang II), DNA synthesis and extracellular matrix (ECM) production were examined. Cellular expression of LDL/scavenger receptors was analyzed using fluorescence-labeled LDL and binding to 125I-labeled-LDL. RESULTS: The number of cells per glomerular cross section was significantly higher in OLETF rats than in LETO rats between 25 and 65 weeks of age. In OLETF glomeruli, c-Fos, c-Myc, and PCNA were transiently expressed in the early phase. Glomerular LDL deposition increased with the age of OLETF rats. Addition of a low dose of n-LDL (10 microg/mL) to the culture medium significantly stimulated DNA synthesis of y-OLETF MCs, as compared with o-OLETF MCs and LETO MCs (P < 0.05). A high dose of n-LDL (100 microg/mL) caused cytotoxic effects in all cells. Exposure to ox-LDL minimally affected DNA synthesis of OLETF or LETO MCs. LDL receptors and scavenger receptors were predominant in y-OLETF and o-OLETF, respectively. After stimulation with n-LDL and ox-LDL, expression of type I and type III collagen, along with transforming growth factor-beta (TGF-beta), was higher in o-OLETF MCs that in y-OLETF MCs or LETO MCs. Exposure to Ang II markedly induced DNA synthesis and ECM mRNA expression in y-OLETF MCs and o-OLETF MCs, respectively. CONCLUSIONS: These findings indicate that the cell proliferation process precedes the evolution of diabetic glomerulopathy. The responses of OLETF MCs to n-LDL/ox-LDL and Ang II differed depending on the stage of diabetes. In the early phase, MCs were prone to proliferate, whereas in the late stage, MCs, which expressed higher levels of TGF-beta, tended to synthesize ECM. A functional switch in MCs may contribute to the development of glomerulosclerosis in diabetic nephropathy.


Asunto(s)
Angiotensina II/farmacología , LDL-Colesterol/farmacocinética , Nefropatías Diabéticas/patología , Mesangio Glomerular/patología , Vasoconstrictores/farmacología , Animales , Recuento de Células , División Celular/fisiología , Células Cultivadas , Colágeno Tipo I/genética , ADN/biosíntesis , Diabetes Mellitus Tipo 2/patología , Diabetes Mellitus Tipo 2/fisiopatología , Nefropatías Diabéticas/fisiopatología , Matriz Extracelular/metabolismo , Matriz Extracelular/patología , Expresión Génica/efectos de los fármacos , Expresión Génica/fisiología , Mesangio Glomerular/efectos de los fármacos , Radioisótopos de Yodo , Lipoproteínas LDL/farmacocinética , Masculino , Metaloproteinasa 2 de la Matriz/genética , Antígeno Nuclear de Célula en Proliferación/genética , Proteínas Proto-Oncogénicas c-fos/genética , Proteínas Proto-Oncogénicas c-myc/genética , ARN Mensajero/análisis , Ratas , Ratas Endogámicas OLETF , Receptores de LDL/análisis , Factor de Crecimiento Transformador beta/genética
10.
Biochim Biophys Acta ; 1257(2): 189-97, 1995 Jul 13.
Artículo en Inglés | MEDLINE | ID: mdl-7619860

RESUMEN

The effects of hyodeoxycholic (HDCA) and alpha-hyocholic acids (alpha-HCA), on cholesterol, bile acid and lipoprotein metabolism, were studied in hamsters. The animals were fed a low cholesterol control diet supplemented with 0.1% HDCA or alpha-HCA for 3 weeks. In both treated groups, the LDL-cholesterol concentration was significantly lowered and was associated with a global hypocholesterolemic effect. Moreover, hepatic cholesterol ester storage was reduced and HMGCoA reductase activity was respectively enhanced 13.5-times and 7.7-times in HDCA and alpha-HCA groups compared to controls. In contrast, cholesterol 7 alpha-hydroxylase activity and LDL-receptor activity and mass were not modified. In bile, the cholesterol saturation index was increased 5-fold (HDCA group) and 2-fold (alpha-HCA group) as a consequence of an enlarged proportion of biliary cholesterol. The two 6-hydroxylated bile acids induced an enhanced fecal excretion of neutral sterols (HDCA group: 11.6-times, alpha-HCA group: 3.2-times versus controls) which was consistent with a 59% decrease in intestinal cholesterol absorption in the HDCA group. The major effects due to bile acid treatments were a decrease in LDL-cholesterol concentration, a strong stimulation of hepatic cholesterol biosynthesis and an excessive loss of cholesterol in feces. These perturbations might be the result of the enrichment of bile with hydrophilic bile acids, leading to a limited return of endogenous cholesterol from the intestine to the liver.


Asunto(s)
Ácidos y Sales Biliares/metabolismo , Colesterol/metabolismo , Ácidos Cólicos/administración & dosificación , Ácido Desoxicólico/administración & dosificación , Animales , Bilis/metabolismo , Cricetinae , Dieta , Absorción Intestinal , Lipoproteínas/metabolismo , Hígado/metabolismo , Mesocricetus , Receptores de LDL/análisis
11.
Atherosclerosis ; 114(2): 213-21, 1995 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-7605390

RESUMEN

We investigated the differences between the hypocholesterolemic effects induced by dietary linoleic acid and those induced by oleic acid in hamsters. Addition of 5% linoleic acid or oleic acid to a 0.1% cholesterol-supplemented diet diminished the increases in plasma total and low density lipoprotein (LDL) cholesterol induced by cholesterol alone. Linoleic acid decreased high density lipoprotein (HDL) cholesterol in comparison with cholesterol alone, whereas oleic acid did not. As compared with a standard diet or a cholesterol-supplemented diet, linoleic acid and oleic acid each prevented hepatic LDL receptor suppression, although linoleic acid was more effective. Oleic acid prevented the increase in plasma cholesteryl ester transfer protein (CETP) activity induced by dietary cholesterol, whereas linoleic acid did not. Neither linoleic acid nor oleic acid altered hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase activity. Only oleic acid increased hepatic cholesterol 7 alpha-hydroxylase activity. These results suggest that dietary linoleic and oleic acids diminish the cholesterol-induced increases in plasma total and LDL-cholesterol by preventing hepatic LDL receptor suppression, and in the case of oleic acid by also preventing the increase in the plasma CETP activity. These effects on cholesterol 7 alpha-hydroxylase activity may influence bile lipid metabolism.


Asunto(s)
Colesterol/sangre , Glicoproteínas , Ácidos Linoleicos/administración & dosificación , Ácidos Oléicos/administración & dosificación , Animales , Proteínas Portadoras/sangre , Colesterol 7-alfa-Hidroxilasa/metabolismo , Proteínas de Transferencia de Ésteres de Colesterol , Ésteres del Colesterol/sangre , Colesterol en la Dieta/farmacología , HDL-Colesterol/sangre , LDL-Colesterol/sangre , Cricetinae , Dieta , Ácido Linoleico , Hígado/química , Masculino , Mesocricetus , Ácido Oléico , Receptores de LDL/análisis
12.
J Nutr ; 122(10): 1960-70, 1992 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-1527637

RESUMEN

To determine effect of interaction between dietary cholesterol and triglyceride, i.e., polyunsaturated to saturated (P:S) fatty acid ratio, on LDL metabolism, male cynomolgus macaques were fed purified diets for 83 wk with cholesterol levels of 0.01, 0.06 and 0.50 mg/kJ and P:S ratios of 0.5 and 0.9, oleic acid constant. There were six groups of five animals each (cholesterol, mg/kJ--P:S ratio): Group 1, 0.01--0.5; Group 2, 0.01--0.9; Group 3, 0.06--0.5; Group 4, 0.06--0.9; Group 5, 0.50-0.5; Group 6, 0.50-0.9. LDL (1.019 less than d less than 1.063 kg/L) and glucosylated LDL were iodinated for turnover studies. Hepatic LDL transport was determined using 125I-tyramine-cellobiose-LDL as tracer. Plasma cholesterol increased in proportion to dietary cholesterol, and concentrations (mmol/L) at 77-78 wk were (mean +/- SEM): Group 1, 434 +/- 0.31; Group 2, 3.03 +/- 0.14; Group 3, 8.28 +/- 1.48; Group 4, 7.34 +/- 1.31; Group 5, 15.54 +/- 1.44; Group 6, 15.54 +/- 1.41. LDL cholesterol was 45% higher in Group 1 (2.43 mmol/L) than in Group 2 (1.68 mmol/L). In vivo studies showed that LDL clearance was suppressed by excess dietary cholesterol; receptor-independent LDL clearance was relatively constant. Hepatic LDL protein transport was greater in Group 2 (P:S 0.9) compared with Group 1 (P:S 0.5). The LDL protein synthetic rate was lower in Groups 2, 4 and 6 (P:S 0.9) relative to Groups 1, 3 and 5 (P:S 0.5). We conclude that in this model hepatic LDL receptor activity is altered by degree of saturation in dietary triglycerides when dietary cholesterol is minimal, and that saturated dietary triglycerides enhance LDL protein secretion when dietary cholesterol is ample.


Asunto(s)
Colesterol en la Dieta/administración & dosificación , Grasas de la Dieta/farmacología , Ácidos Grasos Insaturados/farmacología , Ácidos Grasos/farmacología , Hígado/efectos de los fármacos , Animales , Transporte Biológico/efectos de los fármacos , Colesterol/sangre , Colesterol en la Dieta/farmacología , Glicosilación , Lipoproteínas LDL/análisis , Lipoproteínas LDL/biosíntesis , Hígado/metabolismo , Macaca fascicularis , Masculino , Receptores de LDL/análisis
13.
Int J Cancer ; 46(2): 320-5, 1990 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-2384278

RESUMEN

The metabolism of human low-density lipoproteins was studied in 2 subpopulations deriving from cells of HT29, a human colon carcinoma cell line. When grown on standard medium (25 mM glucose), about 95% of these cells are undifferentiated (G+ cells). From this heterogeneous population, a subpopulation with features of differentiated small-intestinal cells was selected by glucose deprivation (G- cells). The characteristics of the LDL receptor were first investigated. The results showed that the binding of 125I-LDL to G+ and G- cells performed at 4 degrees C was saturable and specific. The Kd values were not statistically different in the 2 cell subpopulations. The Bmax of G+ cells was 55 +/- 6 ng 125I-LDL/mg cell protein and showed no changes whatever the phase of culture. In G- cells, the Bmax was higher during the exponential phase of culture and decreased in the post-confluent phase (82 +/- 5 versus 15 +/- 6.8 ng 125I-LDL/mg cell protein). Cellular degradation of 125I-LDL was effective in both cell subpopulations but time-course studies showed that, in post-confluent G- cells, degradation was slowed as compared to G+ cells (4 hr vs. 2 hr to reach maximal degradation). The rate of LDL processing at 37 degrees C was enhanced by pre-incubation with FCS-supplemented medium, suggesting the existence of a serum component which stimulates the total degradation of 125I-LDL. Concerning regulation of the LDL receptor activity, we demonstrated that pre-incubation of G+ cells with LDL induced 80% down-regulation of receptor number in both phases of culture. This was also observed in G- cells during the exponential phase while only a 20% decrease of the receptor number was observed in post-confluent G- cells. The LDL degradation of G+ cells resulted in an inhibition of the cholesterogenic activity by 30% and 60% depending on the phase of culture. In G- cells, LDL pre-incubation inhibited cholesterol synthesis to the same extent (45%) in the exponential phase but did not affect the rate of cholesterol synthesis when cells were confluent. The defective regulatory role of LDL on receptor number and cholesterol synthesis suggests that, in the post-confluent differentiated cells, cholesterol derived from LDL does not reach the regulatory pool. Taken together, our findings indicate the existence of functional LDL receptors in the HT29 cell line, either in the differentiated or in the undifferentiated form.


Asunto(s)
Adenocarcinoma/metabolismo , Transformación Celular Neoplásica/metabolismo , Neoplasias del Colon/metabolismo , Lipoproteínas LDL/metabolismo , Adenocarcinoma/análisis , Línea Celular , Transformación Celular Neoplásica/análisis , Colesterol/análisis , Colesterol/biosíntesis , Neoplasias del Colon/análisis , Humanos , Radioisótopos de Yodo , Lipoproteínas LDL/análisis , Unión Proteica , Ensayo de Unión Radioligante , Receptores de LDL/análisis , Receptores de LDL/metabolismo , Células Tumorales Cultivadas/análisis , Células Tumorales Cultivadas/metabolismo
14.
Am J Clin Nutr ; 52(2): 300-6, 1990 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-2375296

RESUMEN

Sixty-four male, healthy volunteers aged 35-45 y were randomly assigned to receive (as 1-g capsules) either 14 g fish-oil concentrate/d (55% n-3 fatty acids) or 14 g olive oil/d for 6 wk. Plasma fibrinogen was reduced by 13% and serum triglycerides by 22% after fish-oil supplementation ended. Three weeks after supplementation ended both variables were back to baseline values. An appreciable increase in the ratio of eicosapentaenoic acid to arachidonic acid (EPA:AA) in plasma eicosapentaenoic acid to arachidonic acid (EPA:AA) in plasma and red blood cell phospholipids occurred during the fish-oil intake. High-density-lipoprotein (HDL) cholesterol and HDL2 activity tended to be lowered by fish-oil supplementation. Systolic and diastolic blood pressures, serum cholesterol, gamma-glutamyltransferase, blood glucose, and monocyte low-density-lipoprotein receptor activity did not differ significantly between the two groups. The reduction in plasma fibrinogen concentration seems of special interest because this variable in several recent studies emerges as a separate cardiovascular risk factor with a high predictive value.


Asunto(s)
Enfermedades Cardiovasculares/prevención & control , Fibrinógeno/análisis , Aceites de Pescado/farmacología , Adulto , Presión Sanguínea , Enfermedades Cardiovasculares/etiología , Método Doble Ciego , Ingestión de Alimentos , Eritrocitos/análisis , Ácidos Grasos/sangre , Aceites de Pescado/uso terapéutico , Humanos , Masculino , Fosfolípidos/sangre , Distribución Aleatoria , Receptores de LDL/análisis , Análisis de Regresión , Factores de Riesgo , Triglicéridos/sangre
15.
Am J Pathol ; 121(2): 200-11, 1985 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-3840653

RESUMEN

Uptake of low density lipoprotein (LDL) and of acetyl LDL was compared in skin fibroblasts, smooth muscle cells, and peritoneal macrophages with the use of lipoproteins labeled with either 125I or the fluorescent probe 3,3'-dioctadecylindocarbocyanine (DiI). The uptake of DiI-labeled lipoproteins was assessed by quantitative spectrofluorometry and by fluorescence microscopy. The DiI was quantitatively retained by the cells, while the 125I-LDL was degraded and 125I-labeled degradation products were excreted from the cells. In smooth muscle cells and fibroblasts the uptake of LDL was virtually the same whether measured with the use of the DiI or 125I-label (sum of cell-associated and degraded 125I). The labeling of acetyl LDL with DiI enhanced its uptake in peritoneal macrophages by an average of 18%. With the DiI label, lipoprotein uptake (DiI-LDL for smooth muscle cells and skin fibroblasts and DiI-acetyl-LDL for mouse peritoneal macrophages) could be determined after as little as 10 minutes of incubation at 37 C. The pattern of uptake of the DiI-labeled lipoproteins was consistent with binding to specific receptors, because no DiI could be detected in mutant cells without LDL receptors, and uptake was competitively inhibited by addition of excess unlabeled lipoprotein. When the DiI-labeled lipoproteins were removed from the medium, there was a 5-15% loss of DiI from all cell types studied over the first 24 hours. Thereafter, DiI loss from cells was dependent on cell type and culture medium. No further loss of DiI occurred from skin fibroblasts for up to 96 hours of incubation in medium supplemented with either lipoprotein-deficient serum (LPDS) or 10% fetal bovine serum. During this same time period there was a 40-60% loss of DiI from smooth muscle cells and macrophages incubated in medium supplemented with LPDS. Most of the DiI lost from the cells (60-70%) could be recovered in the culture medium but was not the result of cell death, as was indicated by the relatively constant protein concentrations per dish. The loss of DiI was markedly reduced in smooth muscle cells and macrophages when 10% fetal bovine serum was substituted for the LPDS in the culture medium. This suggests that some cells incubated with LPDS undergo changes, perhaps in the plasma membrane, that alter their ability to retain the DiI. In the presence of 10% fetal bovine serum, however, the DiI label is quantitatively retained by all cells tested for up to 96 hours.(ABSTRACT TRUNCATED AT 400 WORDS)


Asunto(s)
Lipoproteínas/metabolismo , Macrófagos/metabolismo , Músculo Liso/metabolismo , Piel/metabolismo , Animales , Aorta , Carbocianinas , Células Cultivadas , Femenino , Fibroblastos/metabolismo , Colorantes Fluorescentes , Humanos , Radioisótopos de Yodo , Lipoproteínas LDL/metabolismo , Macaca mulatta , Ratones , Microscopía Fluorescente , Peritoneo/citología , Receptores de LDL/análisis , Espectrometría de Fluorescencia , Factores de Tiempo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA