The beneficial effects of virgin olive oil against oxidative stress induced by hypercholesterolemia in rats

Cardiovascular disease(CVD) remains the major cause of mortality in the world, typically claiming a third of all deaths. The primary cause of CVD is atherosclerosis. Therefore, timely prevention and therapy of atherosclerosis are able to reduce the risk of the development of its clinical manifestations. Anti-atherosclerotic activity of medicinal plants mainly appears in their multiple effects.This study was carried out to evaluate the hypolipidemic activity of virgin olive oil in experimentally induced hyperlipemic Wistar. A total of 24 rats were randomly allocated to 4 equal groups and treated as follows for 50 days: (1) Normal control (NC); that were fed with a standart diet; (2) High Cholesterol Diet Control (HCD); which received high cholesterol diet for 50 days; (3) Animals receiving high cholesterol diet for 50 days, after this period the animals are fed for eight days by the standard foodand receiving by gavage virgin olive oil (HCD+VOO) and(4) Animals fed for eight days with the standard food and receiving by gavage olive oil (VOO). High Cholesterol Diet containing yolk egg and coconut oil. Results showed that olive oil caused a significant (p < 0.01) reduction in serum levels of Total Cholesterol (TC), Triglycerides (TG), Low­Density Lipoprotein Cholesterol (LDL) and Atherogenic Index Serum (AIS). The results also demonstrated a significant (p < 0.01) increase in High­Density Lipoprotein Cholesterol (HDL). Moreover, virgin olive oil induced a significant reduction in liver lipid content. On the other hand, a High cholesterol diet induced oxidative stress was measured by estimating reduced glutathione level and amount of thiobarbituric acid reactive substances (TBARS) formed as an index of lipid peroxidation in a liver and a heart. Virgin olive oil supplementation attenuated all these variations. Our observations of the study indicate that the virgin olive oil has a significant antihyperlipidemic potential.

Tyramine exerts hypolipidemic and anti-obesity effects in vivo

Abstract Obesity and dyslipidemia are conditions often associated with cardiovascular risk, inflammation, oxidative stress, and death. Thus, a new approach has been highlighted to promote research and development of pharmacological tools derived from natural sources. Among the most widely studied groups of substances, polyphenols such as tyramine stand out. This study investigated hypolipidemic and anti-obesity properties of tyramine. Oral toxicity evaluation, models of dyslipidemia and obesity were used. To induce dyslipidemia, Poloxamer-407 (P-407) was administered intraperitoneally. In the hypercholesterolemic and obesity model, specific diet and oral tyramine were provided. After 24h of P-407 administration, tyramine 2 mg/kg (T2) decreased triglycerides (TG) (2057.0 ± 158.5 mg/dL vs. 2838 ± 168.3 mg/dL). After 48h, TG were decreased by T2 (453.0 ± 35.47 vs. 760.2 ± 41.86 mg/dL) and 4 mg/kg (T4) (605.8 ± 26.61 760.2 ± 41.86 mg/dL). T2 reduced total cholesterol (TC) after 24h (309.0 ± 11.17 mg/dL vs. 399.7 ± 15.7 mg/dL); After 48h, 1 mg/kg (T1) (220.5 ± 12.78 mg/dL), T2 (205.8 ± 7.1 mg/dL) and T4 (216.8 ± 12.79 mg/dL), compared to P-407 (275.5 ± 12.1 mg/dL). The treatment decreased thiobarbituric acid reactive substances and nitrite in liver, increased superoxide dismutase, reduced the diet-induced dyslipidemia, decreasing TC around 15%. Tyramine reduced body mass, glucose, and TC after hypercaloric feed. Treatment with 5 mg/L (0.46 ± 0.04 ng/dL) and 10 mg/L (0.44 ± 0.02 ng/dL) reduced plasma insulin (1.18 ± 0.23 ng/dL). Tyramine increased adiponectin at 5 mg/L (1.02 ± 0.02 vs. 0.83 ± 0.02 ng/mL) and 10mg/L (0.96 ± 0.04 ng/mL). In conclusion, tyramine has low toxicity in rodents, has antioxidant effect, reduces plasma triglycerides and cholesterol levels. However, further studies should be conducted in rodents and non-rodents to better understand the pharmacodynamic and pharmacokinetic properties of tyramine

Efficacy of an herbal compound in decreasing steatosis and transaminase activities in non-alcoholic fatty liver disease: A randomized clinical trial

Abstract Hepatoprotective effects of many herbal agents have been reported in animal studies and clinical trials. In this study, five hepatoprotective plants with potent antioxidant, anti-inflammatory, and hypolipidemic effects were chosen to prepare a polyherbal compound for managing NAFLD. Sixty patients with NAFLD were randomly divided into treatment and control groups (2:1 ratio). Both group were advised to take healthy diet and exercise. The treatment group also received herbal capsules containing 400 mg of the mixture of Anethum graveolens, Citrus aurantium, Cynara scolymus, Portulaca oleracea, and Silybum marianum (2 capsules, thrice daily, for two months). The liver ultrasound and biochemical markers including the serum lipids, liver enzymes, and glucose were evaluated before starting the study and at the end of the treatment. Thirty patients in the treatment group and sixteen patients in the control group completed the study. The herbal compound significantly decreased the serum level of alanine transaminase (ALT), aspartate transaminase (AST), and total cholesterol. Treatment with the herbal compound significantly improved the grade of the fatty liver, but no significant change was found in the control group. In conclusion, the formulated herbal compound appeared to be effective in biochemical improvement and decreasing the grade of the fatty liver in the patients with NAFLD.

Simvastatin treatment reduces the cholesterol content of membrane/lipid rafts, implicating the N -methyl-D-aspartate receptor in anxiety: a literature review

ABSTRACT Membrane/lipid rafts (MLRs) are plasmalemmal microdomains that are essential for neuronal signaling and synaptic development/stabilization. Inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme-A reductase (statins) can disable the N-methyl-D-aspartate (NMDA) receptor through disruption of MLRs and, in turn, decrease NMDA-mediated anxiety. This hypothesis will contribute to understanding the critical roles of simvastatin in treating anxiety via the NMDA receptor.

Avaliação de aspectos funcionais da lipoproteína de alta densidade (HDL) e suas subfrações em pacientes com doença arterial coronária / Evalution of functional aspects from high density lipoproteins (HDL) and their subfractions from coronary heart disease patients

Estudos clínicos e epidemiológicos indicam que baixas concentrações plasmáticas da lipoproteína de alta densidade (HDL) estão forte e independentemente associadas a uma maior incidência de doença arterial coronária (DAC). Entretanto, o insucesso dos agentes que são capazes de aumentar a concentração de HDL-C sugere que a funcionalidade da HDL pode representar um alvo terapêutico mais apropriado. Para a avaliação de um dos aspectos funcionais da HDL, o presente trabalho descreve o desenvolvimento de um método de grande praticidade que permite uma visão integrada de uma etapa fundamental do metabolismo que é a transferência de lípides entre as diferentes classes de lipoproteínas. A avaliação deste fenômeno nas subfrações de HDL, aspecto ainda não explorado, poderá fornecer novas informações a respeito da fisiopatologia da DAC. O método descrito no presente trabalho permite a avaliação da transferência simultânea das quatro principais classes lipídicas doadas por uma nanoemulsão semelhante à LDL para a HDL3. Foi realizada análise dos possíveis interferentes neste método. Verificou-se que a elevação da temperatura de 0 a 40 °C resultou em aumento progressivo na transferência de todos os lipídeos para a HDL3. A variação de pH entre 6,5 e 8,5 e o aumento na concentração de albumina não alteraram os valores de transferência. O aumento no tempo de incubação acima de 60 minutos promoveu diminuição na transferência de colesterol esterificado para a HDL3 e aumento na transferência de fosfolipídeos. O método apresentou boa precisão intra e inter-ensaio, sendo o coeficiente de variação menor que 5% para todos os lipídeos. A porcentagem média de transferência de colesterol livre, fosfolipídeos, triacilglicerol e colesterol em 45 invíduos saudáveis foi de respectivamente de 1,1±0,06; 13,5±0,15; 2±0,05 e 0,84±0,04% e em 45 portadores de doença arterial coronária foi respectimente 1,0±0,04; 15,8±0,44; 1,77±0,04 e 1,0±0,06%. Não houve diferença nos valores de idade, IMC, colesterol total, HDL-C, LDL-C, triacilglicerol, apo A-1, apo B, CETP, PLTP e LCAT, mas os indivíduos portadores de doença arterial coronária apresentaram valores maiores de colesterol livre e colesterol total em relação aos indivíduos saudáveis. O método desenvolvido no presente estudo é prático, preciso e de potencial relevância como ferramenta no estudo dos distúrbios de função da HDL

Clinical and epidemiological studies show that low concentrations of high density lipoproteins (HDL) are strongly and independently associated to an increased incidence of coronary artery disease (CAD). However, the lack of success of some drugs developed to increase HDL cholesterol concentrations (HDL-C) suggests that the functional aspects of HDL may represent a more appropriate therapeutic target. To study one of the functional aspects of HDL, the present work describes the development of a practical method that provides an integrated view of a fundamental step of lipid metabolism, namely, the lipid transfer among different lipoprotein classes. This phenomenon in the HDL subfractions is yet unexplored, and could provide new insights on the pathophysiology of CAD. The method described here allows the measurement of the ability of HDL3 to receive the major lipid classes from a radioactively labeled nanoparticle that resemble LDL. The possible interfering factors at the lipid transfer to HDL3 were studied. The increase in the assay temperature from 0 to 40 °C results in a progressive increase in the net transfer of all lipids to HDL3. The increase in incubation time above 60 minutes resulted in a reduced transfer of cholesterol esters to HDL3 with a concomitant increase in the transfer of phospholipids to the latter. The method presented adequate intra and inter-assay precision, with a coefficient of variation smaller than 5% for all lipids. The average percentage of free cholesterol, phospholipids, triacilglycerol an cholesterol transfer to HDL3 was respectively of 1,1±0,06; 13,5±0,15; 2±0,05 e 0,84±0,04% in 45 healthy individuals and 1,0±0,04; 15,8±0,44; 1,77±0,04 e 1,0±0,06% in 45 CAD patients. There was no difference in the age, BMI, total cholesterol, HDL-C, LDL-C, triacilglycerol, apo A-1, apo B, CETP, PLTP and LCAT but the CAD patients had higher levels of total cholesterol and free cholesterol. The method described here is practical, precise and potentially relevant as a tool to study HDL function

Pharmacological activity of the hydroalcoholic extract from Hovenia dulcis thunberg fruit and the flavonoid dihydromyricetin during hypercholesterolemia induced in rats

Cerebrovascular accidents and coronary artery disease are the leading causes of cardiovascular mortalities in Brazil and high levels of LDL cholesterol are one of the main risk factors. In this context, several plant extracts and natural substances have shown promise as cholesterol-lowering. The objective of this study was to evaluate the potential of the hydroalcoholic extract of the fruit of H. dulcis and of dihydromyricetin in cholesterol reduction in hypercholesterolemic rats. Forty-two Wistar male rats were distributed into seven groups of six animals that received diets supplemented with 1% cholesterol and 0.3% cholic acid, with the exception of the control group, which received conventional diets. Animals were treated with oral suspensions containing: atorvastatin 1.0 mg/kg; H. dulcis extract at 50.0 and 100.0 mg/kg and dihydromyricetin at 25.0 and 50.0 mg/kg vehicle (control group). The following biochemical markers were evaluated; total cholesterol, HDL-C, LDL-C, triglycerides, AST, ALT, and alkaline phosphatase. The hypercholesterolemic diet was effective in inducing hypercholesterolemia, increasing total cholesterol by 112.7% relative to the control group. The treatments with two doses of the extract proved to be promising hypocholesterolemic agents, as they were able to substantially reduce total cholesterol and LDL-C, without significantly altering triglycerides, hepatic transaminases, and alkaline phosphatase, thereby encouraging the studies with the plant H. dulcis. The groups treated with the flavonoid dihydromyricetin, although they showed a significant reduction in total cholesterol and LDL-C, and found increases in triglycerides and hepatic transaminases, which is unwanted in the context of hypercholesterolaemia.

No Brasil, o acidente vascular cerebral e a doença arterial coronariana constituem as principais causas de mortalidade cardiovascular, sendo os altos níveis de colesterol LDL um dos principais fatores de risco. Nesse contexto, diversos extratos vegetais e substâncias naturais isoladas têm se mostrado promissoras como hipocolesterolemiantes. O objetivo do trabalho foi avaliar o potencial do extrato hidroalcoólico dos frutos de Hovenia dulcis e do flavonóide diidromiricetina na redução do colesterol em ratos hipercolesterolêmicos. Quarenta e dois ratos Wistar machos, foram distribuídos em 7 grupos de 6 animais, que receberam dieta suplementada com 1% de colesterol e 0,3% de ácido cólico, à exceção do grupo controle, que recebeu ração convencional. Posteriormente, os animais foram tratados com suspensões orais contendo: atorvastatina 1,0 mg/kg; extrato de H. dulcis de 50,0 e 100,0 mg/kg; diidromiricetina de 25,0 e 50,0 mg/kg e veículo (grupo controle). Avaliaram-se os parâmetros bioquímicos: colesterol total, HDL-C, LDL-C, triglicérides, AST, ALT e fosfatase alcalina. A dieta hipercolesterolêmica foi efetiva na indução da hipercolesterolemia, aumentando o colesterol total em 112,7% em relação ao controle. Os tratamentos com as duas doses do extrato mostraram-se promissores como agentes hipocolesterolemiantes, já que foram capazes de reduzir substancialmente o colesterol total e LDL-C, sem alterar significativamente triglicérides, as transaminases hepáticas e a fosfatase alcalina, incentivando, assim, a continuidade de estudos com a planta H. dulcis. Já os grupos tratados com o flavonóide diidromiricetina, apesar de apresentarem redução significativa do colesterol total e de LDL-C, apresentaram elevações nos triglicérides e nos parâmetros hepáticos, resultado indesejável no âmbito das hipercolesterolemias.

Incorporação de esterificação do colesterol na lipoproteína de alta densidade(HDL): avaliação de biomarcadores plasmaticos e do diadnóstico por imagem (ecografia vascular com doppler) relacionados com a doença aterogênica de carótidas extracranianas e artérias vertebrais / Incorporation of cholesterol esterification in high-density lipoprotein (HDL): evaluation of plasma biomarkers and imaging diadnóstico (vascular ultrasound Doppler) disease-related atherogenic extracranial carotid and vertebral arteries

As complicações da aterosclerose agregam as principais causas de morte no mundo relacionada a problemas cardiovasculares. É caracterizada por distúrbio da condição mecânica e fisiológica, que promove espessamento e endurecimento nas artérias coronárias, cerebrais e periféricos, ocasionando lesão inflamatória crônica, rica em lipídios e células características do processo inflamatório nas paredes vasculares. Objetivos: Avaliar concentrações plasmáticas de biomarcadores do metabolismo lipídico e resultados de doppler de carótidas, relacionando-os com a doença aterogênica de carótidas. Delineamento: Estudo de Corte Transverso. Casuística e Métodos: 66 pacientes com idade 57,5 ± 15,5 anos, (20 a 77), 63% mulheres. Na análise estatística utilizaram-se testes paramétricos e nãoparamétricos, valores de p < 0,05 foram considerados estatisticamente significantes. Resultados: Verificou-se DCA na população masculina a partir da faixa 36-45 anos; nas mulheres, a doença pôde ser detectada a partir de 46-55 anos, elevando-se em ambos gêneros conforme aumento da idade. Tivemos maior prevalência de DCA no gênero feminino (33% contra apenas 15%), na faixa de 56-65 anos, mostrando RR de 1,56 para o gênero feminino (p<0,002; teste de Fisher, com aproximação de Katz). Quanto ao perfil clínico, houve prevalência de 53% pacientes com DCA; 82% pacientes estavam em uso de medicação regular para quaisquer das doenças pregressas; 68% hipertensos; 73% dislipidêmicos; 11% coronariopatas; 4% apresentaram AVE e 64% faziam uso regular de hipolipemiantes. O teste de Fisher evidenciou diferentes RR em função da presença ou não de DCA: Hipotireoidismo (DCA vs NDCA, p< 0,555; RR=1,0); (DCA vs EMI, p < 0,0001; RR=5,2); Dislipidemia (DCA vs NDCA, p< 0,001; RR=1,62); HAS (DCA vs NDCA, p< 0,003; RR=1,76); DM (DCA vs NDCA, p< 0,001; RR=3,6); AVE (DCA vs NDCA, p< 0,0001; RR=2,03); DAC (DCA vs NDCA, p< 0,0001; RR=6,14). Predominaram estenoses leves em 44%, estenoses moderadas em 9%, não foram observados pacientes com estenose severa ou oclusão. A avaliação dos dados de colesterol livre e total de colesterol marcado na fração HDL diferiu entre os grupos estratificados por HDL-C maior e menor do que 40mg/dl e para as condições DCA e sem DCA (p = 0,0409 e, p = 0,0475 teste t), respectivamente. A análise de correlação linear de Pearson entre os dados de atividade de PON1 quando HDL-C < 40mg/dl e incorporação de colesterol livre e, também entre percentual de esterificação CL/CE foi significativa (r = -0,6; p = 0,048; n = 20 e r = -0,7; p = 0,006; n = 12), respectivamente. Conclusões: Evidenciado presença da DCA com aumento da idade conforme literatura; prevaleceu DCA no perfil clínico dos participantes do estudo; as doenças de base identificadas elevam o risco para DCA; o transporte reverso de colesterol é prejudicado na DCA.

Avaliação preliminar in vivo do efeito hipocolesterolêmico do polvilho da fruta-de-lobo (Solanum lycocarpum A. St.-Hil. ) / Preliminary evaluation of in vivo hypocholesterolemic effect of the flour of fruit-of-wolf (Solanum lycocarpum A. St.-Hil. )

O polvilho da fruta-de-lobo é um produto extraído da polpa da fruta-de-lobo verde (Solanum lycocarpum A. St.-Hil.), popularmente utilizado. Pouco se conhece a respeito desse polvilho, mas são atribuídos a ele vários efeitos terapêuticos, dentre eles a redução do colesterol. Este trabalho teve o objetivo de verificar a ação da administração do polvilho da fruta-de-lobo sobre animais hipercolesterolêmico. Utilizou-se 24 ratos Wistar fêmeas distribuídas em delineamento ao acaso, em três grupos contendo 8 animais em cada grupo. Estes grupos foram definidos como: controle normal (CN), controle hipocolesterolêmico (CH) e hipocolesterolêmico tratado (HT). O grupo CN recebeu dieta comercial, os grupo CH e HT receberam a dieta comercial enriquecida de colesterol e ácido cólico e o grupo HT recebeu também, 100 mg de polvilho da fruta-lobo, diariamente, por sonda orogástrica. O experimento teve uma duração de 6 semanas onde se avaliou o colesterol total sérico semanalmente, peso dos animais semanalmente e o consumo diário de ração. Ao término do experimento, foram avaliados os seguintes parâmetros: frações séricas de colesterol HDL, LDL+VLDL, peso do fígado, colesterol total hepático, lipídeos totais hepático e lâminas de microscopia foram feitas para avaliação dos hepatócitos. Não houve diferença significativa em relação ao peso corporal dos animais, ao consumo da dieta e nas análises de colesterol total sérico entre os grupos estudados. Avaliando-se a relação VLDL +LDL/HDL, os níveis encontrados no grupo HT foram significativamente menores que o grupo CH. Já em relação ao colesterol hepático, o grupo HT mostrou níveis menores de colesterol que o CH. Observou-se nos lipídeos hepáticos que não houve diferença significativa entre os grupo CH e HT, e no peso do fígado houve diferença significativa entre os grupos avaliados. Em relação à microscopia, os grupos hipercolesterolêmicos apresentaram discreta vacuolização no citoplasma dos hepatócitos. Concluiu-se, que o polvilho da fruta-de-lobo não influenciou o colesterol sérico dos animais, entretanto, reduziu os níveis de colesterol hepático.

The fruit-of-wolf flour is a product extracted from the pulp of green fruit-of-wolf (Solanum lycocarpum A. St .- Hil.) and is commonly used. Little is known about this flour, but several therapeutic effects, including cholesterol reduction, are attributed to it. This study aimed to verify the action of the administration of fruit-of-wolf flour to hypercholesterolemic animals. We used 24 female Wistar rats allocated in randomized design to three groups containing 8 animals each. These groups were defined as normal control (CN), hypocholesterolemic control (CH) and hypocholesterolemic treated rats (HT). The CN group received a commercial diet, while the CH and the HT group received the commercial diet enriched with cholesterol and cholic acid; the HT group also received 100 mg of fruit-of-wolf flour, daily, by orogastric tube. The experiment lasted for six weeks and the following characteristics were evaluated: weekly total serum cholesterol, weekly weight of animals and daily food intake. At the end of the experiment, we assessed the following parameters: serum cholesterol fractions HDL, LDL + VLDL, liver weight, liver total cholesterol, liver total lipids and microscopic slides were prepared for the evaluation of hepatocytes. There was no significant difference in body weight of animals, diet consumption and analysis of serum total cholesterol among the studied groups. Assessing the relationship VLDL + LDL / HDL, the levels found for the HT group were significantly lower than those for the CH group. As regards liver cholesterol, the HT group showed lower cholesterol levels than the CH group. For liver lipids there was no significant difference between the CH and the HT group, and for liver weight there was no significant difference among the studied groups. As to microscopy, the hypercholesterolemic groups showed slight vacuolization in the cytoplasm of hepatocytes. It was concluded that fruit-of-wolf flour did not influence the serum cholesterol of animals but reduced the levels of liver cholesterol.

Fluconazole-loaded liposomes for ocular delivery: characterization and antifungal activity

Fluconazole loaded liposomes were prepared using reverse phase evaporation technique for ocular delivery of the drug. Characterization of fluconazole liposomes including; particle size and physical morphology were studied. The effects of different variables [cholesterol weight ratio and charge type] on the loading efficiency of liposomes as well as particle size were determined. Inclusion of cholesterol in liposomal formulations improved the encapsulation of fluconazole into liposomes at certain Phosphatidylcholine: Cholesterol [PC: Ch] weight ratios further increase in cholesterol content resulted in a decrease in the encapsulation percent of the drug. A significant increase in the encapsulation at ratio 7:3 was noticed. At ratio 7:6, the encapsulation significantly decreased. Incorporation of stearylamine [SA] into liposomes decreased the loading efficiency of fluconazole at ratio [PC: Ch: SA] 5: 5: 0.25 followed by insignificant increase in the entrapment of the drug into liposomes at ratio 5: 5: 0.5. On the other hand, addition of dicetyl phosphate [DP] into liposomes resulted in a significant increase in fluconazole encapsulation into liposomes at all tested [PC: Ch: DP] ratios. The loading efficiency of the neutral liposomes was found to be in between those of positively and negatively charged liposomes. The particle size studies showed that, increasing cholesterol amount, led to an increase in the particle size. While increasing stearylamine and dicetyl phosphate led to decrease in the particle size of liposomes. An in-vitro study was done to know the effect of fluconazole loaded liposomes on different fungi isolated from eye

Specific nutrient supplementation of defined serum-free medium for the improvement of CHO cells growth and t-PA production

Recombinant CHO TF70R cells are able to grow and produce t-PA on serum-free medium BIOPRO1 (BioWhitaker Europe, Belgium). The purpose of the present study was to determine the effect of medium supplementation with vitamins, lipids, and specific amino acids on cell growth, t-PA production and biological functionality. Among vitamins, only biotin, folic acid, cobalamine and benzoic acid were required for improving growth and t-PA production. Lipid supplement allowed a significant increase cell concentration and t-PA specific activity and concentration, though its specific production rate decreased slightly. Medium supplementation with proline, serine and asparagine had also positive effects on cell growth. Besides, the addition of asparagine (even in the presence of glutamine) was essential for the production and biological quality of the t-PA. This systematic approach for media supplementation produced an increase in cell concentration around 100 percent and in t-PA production around 80 percent, with no detrimental effect on its biological activity. The effect of asparagine on t-PA production was unexpected and needs to be further studied. The above modifications of the production medium did not produce a significant effect on the metabolism of the main carbon and energy sources (glucose and glutamine) and the level of by-product formation (lactate and ammonia).

Influencia del colesterol en membrana sobre la deformabilidad y la fragilidad osmótica eritrocitarias / Variation of erythrocyte deformability and osmotic fragility with cholesterol

La incorporación de colesterol (hemisuccinato de colesterol) a la membrana eritrocitaria afecta sus propiedades reológicas. Esta influencia ha sido evaluada a través de dos parámetros reológicos característicos de la membrana celular: la deformabilidad celular y la fragilidad osmótica. Para ello se aplicaron dos técnicas ambas basadas en el fenómeno de difracción láser, cada una de las cuales presenta diferente sensibilidad de respuesta. Se aplicaron dos protocolos de incubación (12 h a 25ºC el primero y 12 h a 25ºC + 12 h a 37ºC el segundo); en cada uno de ellos se fue variando la cantidad de colesterol incorporado, expresado como Tasa Colesterol/Proteína (Tcp = 0,18 a 0,83). La alteración de las propiedades reológicas de la membrana eritrocitaria producida por la incorporación de colesterol se traduce por una reducción de la deformabilidad celular y por un aumento de la fragilidad osmótica. Se observó que tanto la deformabilidad como la fragilidad, aparecen en relación inversa a la concentración de colesterol incorporado. Sin embargo, deben considerarse que tipos diferentes de deformación se aplican en cada técnica: transformación a esferocito en la fragilidad osmótica y cisallamiento en la deformabilidad

Cholesterol mediated changes in beta-glucuronidase activities of rat theca interstitial cells and granulosa cells.

Effects of steroid hormones on beta-glucuronidase activities of granulosa cells and theca interstitial cells were studied in vitro in the presence and absence of cholesterol in minimum essential medium (MEM with Hank's salts). Conspicuous fall in the enzyme activities of both these cells were noticed during first 10 min of incubation in MEM without cholesterol and remained lower throughout the experiment. Addition of cholesterol to incubation medium maintained beta-glucuronidase activities of both the cells as observed in the cells of immature ovary immediately after isolation. 17 beta-estradiol did not affect beta-glucuronidase activities of these cells, while testosterone and progesterone suppressed the enzyme activities of these cells in the presence of cholesterol.

Lipid effects on nicotinic acetylcholine receptor gating and kinetics: a structural-functional correlation

The nicotinic acetylcholine receptor (AChR) is still the paradigm of rapid ligand-gated ion channels. Since the early finding of a motionally restricted shell of lipids ( annulus ) in the immediate perimeter of the membrane-bound AChR, experimental evidence has supported the notion that the interface between the protein moiety and the adjacent lipid molecules is the site of action of a variety of pharmacologically relevant substances, including non-competitive inhibitors of the cholinergic system like some local anesthetics, short-chain alcohols, and steroids. Patch-clamp data on cells expressing the AChR protein add another dimension to this knowledge, enabling correlations to be established between the chemical composition of lipid-modified cells and the functional properties (ligand binding, channel gating) of the receptor protein in situ

Synthesis and secretion of VLDL by rat hepatocytes--modulation by cholesterol and phospholipids.

The synthesis and secretion of apoB, the major protein component of very low density lipoprotein (VLDL) and low density lipoprotein (LDL), were studied using rat hepatocytes maintained in primary culture. Supplementation of hepatocytes with rat serum VLDL and LDL increased the production of apoB while delipidated lipoproteins had no significant effect, suggesting a role for lipids in the production of apoB. Addition of cholesterol to the culture medium also increased the production of apoB in a concentration-dependent manner. Pulse labelling followed by chase in presence of cholesterol indicated enhancement in apoB secretion. Mevinolin which inhibits cholesterol synthesis significantly reduced the secretion of apoB. The presence of phosphatidylcholine and phosphatidylethanolamine in the culture medium also increased the secretion of apoB into the medium. These data suggest that availability of lipids, particularly cholesterol, is an important determinant of apoB synthesis and secretion as VLDL.

Effect of temperature, cholesterol and nerve tissue on multiplication of armadillo M. leprae.

The effect of temperature, nerve tissue and certain constituents of the medium on multiplication of armadillo M. leprae was studied using Hanks BSS. An equal or better growth was seen at 30 degrees C and 10 degrees C compared to 37 degrees C. Multiplication was also seen at -20 degrees C. Adding cholesterol, foetal calf serum, cystine-HCl, sodium thioglycollate or nerve suspension and covering medium with liquid paraffin each showed beneficial effect. Hanks containing foetal calf serum, cholesterol with sodium thioglycollate or cystine-hydrochloride showed maximum multiplication. These combinations may be used for testing additional factors for further improvement of the medium.