Cholesterol parameters

Often you need to carry forward data to a specific time point due to holes or sparseness of data. The previous example on determining baseline cholesterol level provides an excellent context for this problem. Assume that you have several cholesterol readings of HDL, LDL, and triglycerides for patients before they take an experimental pill designed to reduce cholesterol levels. For each cholesterol parameter, you want the last observation carried forward so long as the measures occur within a five-day window before the pill is taken. Here are some sample data that illustrate the problem ... 

Prabhakaran et al. indicated that noise could be a potent stressor and cause disturbances in the biochemical parameters of the body. It is presumed that most of the effects are indirect, being manifested through the activation of autonomic nervous system that liberates catecholamines and HPA axis responsible for the liberation of corticosteroids [104], In 1989, Hershock and Vogel found that in male Sprague-Dawley rats, acute immobilization stress could affect serum triglyceride and nonesterified fatty acid values and that these effects were diet and time dependent however, the rats total cholesterol levels were unaffected by stress [105], In addition, in 1996 Brennan et al. pointed out that stressed animals had higher levels of the cholesterol parameters than did home cage controls [106],... 

Forsythe, W.A., Miller, E.R., Hill, G.M., Romsos, D.R., and Simpson, R.C. 1980. Effects of dietary protein and fat sources on plasma cholesterol parameters, LCAT activity and amino acid levels and on tissue lipid content of growing pigs. J. Nutr. 110(12), 2467-2479. 

A.M. van Bennekum, D.V. Nguyen, G. Schulthess, H. Hauser, and M.C. Phillips, Mechanisms of cholesterol-lowering effects of dietary insoluble fibres Relationships with intestinal and hepatic cholesterol parameters, Br. J. Nutr, 94 (3), 331-337, 2005. 

Parameter Cholesterol oxidase (CO) Cholesterol esterase (CE) Glucose oxidase (GOD) Peroxidase (POD)... 

This proves our theory that the membrane fluidity is an important parameter increasing shear stress resistance. The studies give two possibilities of improving the resistance lowering temperature or adding cholesterol. Which one is the most convenient is dependent on the cell line and the constraints of the process. 

Patients with metabolic syndrome have an additional lipid parameter that needs to be assessed, namely non-high-density lipoprotein (non-HDL) cholesterol (total cholesterol minus HDL cholesterol). The target for non-HDL cholesterol is less than the patient s LDL cholesterol target plus 30 mg/dL (0.78 mmol/L). 

Cholesterol s presence in liposome membranes has the effect of decreasing or even abolishing (at high cholesterol concentrations) the phase transition from the gel state to the fluid or liquid crystal state that occurs with increasing temperature. It also can modulate the permeability and fluidity of the associated membrane—increasing both parameters at temperatures below the phase transition point and decreasing both above the phase transition temperature. Most liposomal recipes include cholesterol as an integral component in membrane construction. 

Biological membranes Fluidity and order parameters Determination of the phase transition temperature Effect of additives (e.g. cholesterol)... 

In a trial, the parameters for comparison may be the mean level of cholesterol (in the case of a cholesterol-lowering drug), the amount of antibodies in the body (a vaccine trial), or the reduction in the size and severity of tumor (a cancer trial). A test statistic is normally used to compute and compare the means for the placebo and active groups. 

Figure 3 Molecular relaxivities of liposomes with different Gd-containing membranotropic chelators. Liposomes (egg lecithin cholesterol chelator = 72 25 3) were prepared by consecutive extrusion of lipid suspension in HEPES buffered saline, pH 7.4, through the set of polycarbonate filters with pore size of 0.6, 0.4, and 0.2 mm. Liposome final size was between 205 and 225 nm. Gd content determination was performed by Galbraith Laboratories, Inc. The relaxation parameters of all preparations were measured at room temperature using a 5-MHz RADX nuclear magnetic resonance proton spin analyzer. The relaxivity of liposomes with polymeric chelators is noticeably greater because of the larger number of Gd atoms bound to a single lipid residue [16].

A population of patients in a cholesterol lowering study have total cholesterol measured at baseline. Assume that total cholesterol is normally distributed with mean, p = 7.0 mmol/1 and standard deviation, s = 1.1 mmol/1 so that the variance is 1.21 (= 1.1 ). We write this as N(7.0, 1.21). For historical reasons we put the variance as the second parameter here. Under these assumptions the following results hold ... 

A variety of experiments were carried out to determine the influence of chemical and pltysi< parameters on the extractability of cholesterol. Results... 

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