946 resultados para cholesterol derivative
Resumo:
In two separate studies, the cholesterol-lowering efficacy of a diet high in monounsaturated fatty acids (MUFA) was evaluated by means of a randomized crossover trial. In both studies subjects were randomized to receive either a high-MUFA diet or the control diet first, which they followed for a period of 8 weeks; following a washout period of 4–6 weeks they were transferred onto the opposing diet for a further period of 8 weeks. In one study subjects were healthy middle-aged men (n 30), and in the other they were young men (n 23) with a family history of CHD recruited from two centres (Guildford and Dublin). The two studies were conducted over the same time period using identical foods and study designs. Subjects consumed 38% energy as fat, with 18% energy as MUFA and 10% as saturated fatty acids (MUFA diet), or 13% energy as MUFA and 16% as saturated fatty acids (control diet). The polyunsaturated fatty acid content of each diet was 7%. The diets were achieved by providing subjects with manufactured foods such as spreads, ‘ready meals’, biscuits, puddings and breads, which, apart from their fatty acid compositions, were identical for both diets. Subjects were blind to which of the diets they were following on both arms of the study. Weight changes on the diets were less than 1 kg. In the groups combined (n 53) mean total and LDL-cholesterol levels were significantly lower at the end of the MUFA diet than the control diet by 0×29 (SD 0×61) mmol/l (P,0×001) and 0×38 (SD 0×64) mmol/l (P, 0×0001) respectively. In middle-aged men these differences were due to a mean reduction in LDL-cholesterol of ¹11 (SD 12) % on the MUFA diet with no change on the control diet (¹1×1 (SD 10) %). In young men the differences were due to an increase in LDL-cholesterol concentration on the control diet of þ6×2 (SD 13) % and a decrease on the MUFA diet of ¹7×8 (SD 20) %. Differences in the responses of middle-aged and young men to the two diets did not appear to be due to differences in their habitual baseline diets which were generally similar, but appeared to reflect the lower baseline cholesterol concentrations in the younger men. There was a moderately strong and statistically significant inverse correlation between the change in LDLcholesterol concentration on each diet and the baseline fasting LDL-cholesterol concentration (r¹0×49; P,0×0005). In conclusion, diets in which saturated fat is partially replaced by MUFA can achieve significant reductions in total and LDL-cholesterol concentrations, even when total fat and energy intakes are maintained. The dietary approach used to alter fatty acid intakes would be appropriate for achieving reductions in saturated fat intakes in whole populations.
Resumo:
Ross divides prima facie duties into derivative and foundational ones, but seems to understand the notion of a derivative prima facie duty in two very different ways. Sometimes he understands them in a non-eliminativist way. According to this understanding, basic prima facie duties ground distinct derivative ones. According to the eliminativist understanding, basic duties do not ground distinct derivative duties, but replace (eliminate) them. On the eliminativist view, discovering that a prima facie duty is derivative is discovering that it is not genuine. The genuine one is the basic one. I argue that Ross is best understood as an eliminativist.
Resumo:
The synthesis and characterisation of the complexes [η2-{2-H-1-(Me3SiC ≡ C)-C60}Co2(CO)6] (2)} and [η-2-{2-H-1-(Me3SiC ≡ C)-C60}Ni2η-C5H5)2] (3)} is reported, together with a single-crystal molecular structure for (3). This provides the first structural data for an acyclic metal derivative of [60]-fullerene.
Resumo:
For linear multivariable time-invariant continuous or discrete-time singular systems it is customary to use a proportional feedback control in order to achieve a desired closed loop behaviour. Derivative feedback is rarely considered. This paper examines how derivative feedback in descriptor systems can be used to alter the structure of the system pencil under various controllability conditions. It is shown that derivative and proportional feedback controls can be constructed such that the closed loop system has a given form and is also regular and has index at most 1. This property ensures the solvability of the resulting system of dynamic-algebraic equations. The construction procedures used to establish the theory are based only on orthogonal matrix decompositions and can therefore be implemented in a numerically stable way. The problem of pole placement with derivative feedback alone and in combination with proportional state feedback is also investigated. A computational algorithm for improving the “conditioning” of the regularized closed loop system is derived.
Resumo:
The reaction of cis-[RuCl2(dmso)(4)] with [6-(2-pyridinyl)-5,6-dihydrobenzimidazo[1,2-c] quinazoline] (L) afforded in pure form a blue ruthenium(II) complex, [Ru(L-1)(2)] (1), where the original L changed to [2-(1H-benzoimidazol-2-yl)-phenyl]-pyridin-2-ylmethylene-amine (HL1). Treatment of RuCl3 center dot 3H(2)O with L in dry tetrahydrofuran in inert atmosphere led to a green ruthenium(II) complex, trans-[RuCl2(L-2)(2)] (2), where L was oxidized in situ to the neutral species 6-pyridin-yl-benzo[4,5]imidazo[1,2-c] quinazoline (L-2). Complex 2 was also obtained from the reaction of RuCl3 center dot 3H(2)O with L-2 in dry ethanol. Complexes 1 and 2 have been characterized by physico-chemical and spectroscopic tools, and 1 has been structurally characterized by single-crystal X-ray crystallography. The electrochemical behavior of the complexes shows the Ru(III)/Ru(II) couple at different potentials with quasi-reversible voltammograms. The interaction of these complexes with calf thymus DNA by using absorption and emission spectral studies allowed determination of the binding constant K-b and the linear Stern-Volmer quenching constant K-SV
Resumo:
We investigate Fréchet differentiability of the scattered field with respect to variation in the boundary in the case of time–harmonic acoustic scattering by an unbounded, sound–soft, one–dimensional rough surface. We rigorously prove the differentiability of the scattered field and derive a characterization of the Fréchet derivative as the solution to a Dirichlet boundary value problem. As an application of these results we give rigorous error estimates for first–order perturbation theory, justifying small perturbation methods that have a long history in the engineering literature. As an application of our rigorous estimates we show that a plane acoustic wave incident on a sound–soft rough surface can produce an unbounded scattered field.
Resumo:
OBJECTIVE: Circulating levels of 25-hydroxyvitamin D (25OHD) are positively associated with high density lipoprotein (HDL) cholesterol. We sought to replicate a previously reported interaction between APOA5 genotype and vitamin D, and to examine whether HDL-associated genetic loci modify the association between serum 25OHD and HDL cholesterol. METHODS: We examined whether 42 single nucleotide polymorphisms (SNPs) modify the association between serum 25OHD and HDL cholesterol in the 1958 British Birth cohort (aged 45 years, n = 4978). RESULTS: We identified a borderline interaction between the SNP rs12272004 (near the APOA5) and serum 25OHD on HDL cholesterol (P(interaction) = 0.05). The interaction was particularly prominent among the samples collected during winter (P(interaction) = 0.001). None of the other loci showed an interaction with serum 25OHD concentrations on HDL cholesterol. CONCLUSIONS: Our study in 4978 British Whites provides further support that APOA5 genotype modifies the association between vitamin D metabolites and HDL cholesterol.
Resumo:
Cholesterol is one of the key constituents for maintaining the cellular membrane and thus the integrity of the cell itself. In contrast high levels of cholesterol in the blood are known to be a major risk factor in the development of cardiovascular disease. We formulate a deterministic nonlinear ordinary differential equation model of the sterol regulatory element binding protein 2 (SREBP-2) cholesterol genetic regulatory pathway in an hepatocyte. The mathematical model includes a description of genetic transcription by SREBP-2 which is subsequently translated to mRNA leading to the formation of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), a main precursor of cholesterol synthesis. Cholesterol synthesis subsequently leads to the regulation of SREBP-2 via a negative feedback formulation. Parameterised with data from the literature, the model is used to understand how SREBP-2 transcription and regulation affects cellular cholesterol concentration. Model stability analysis shows that the only positive steady-state of the system exhibits purely oscillatory, damped oscillatory or monotic behaviour under certain parameter conditions. In light of our findings we postulate how cholesterol homestasis is maintained within the cell and the advantages of our model formulation are discussed with respect to other models of genetic regulation within the literature.
Resumo:
Cruciferous-rich diets have been associated with reduction in plasma LDL-cholesterol (LDL-C), which may be due to the action of isothiocyanates derived from glucosinolates that accumulate in these vegetables. This study tests the hypothesis that a diet rich in high glucoraphanin (HG) broccoli will reduce plasma LDL-C. METHODS AND RESULTS: One hundred and thirty volunteers were recruited to two independent double-blind, randomly allocated parallel dietary intervention studies, and were assigned to consume either 400 g standard broccoli or 400 g HG broccoli per week for 12 weeks. Plasma lipids were quantified before and after the intervention. In study 1 (37 volunteers), the HG broccoli diet reduced plasma LDL-C by 7.1% (95% CI: -1.8%, -12.3%, p = 0.011), whereas standard broccoli reduced LDL-C by 1.8% (95% CI +3.9%, -7.5%, ns). In study 2 (93 volunteers), the HG broccoli diet resulted in a reduction of 5.1% (95% CI: -2.1%, -8.1%, p = 0.001), whereas standard broccoli reduced LDL-C by 2.5% (95% CI: +0.8%, -5.7%, ns). When data from the two studies were combined the reduction in LDL-C by the HG broccoli was significantly greater than standard broccoli (p = 0.031). CONCLUSION: Evidence from two independent human studies indicates that consumption of high glucoraphanin broccoli significantly reduces plasma LDL-C