Serum samples

The analysis of clinical samples is often complicated by the complexity of the sample matrix, which may contribute a significant background absorption at the desired wavelength. The determination of serum barbiturates provides one example of how this problem is overcome. The barbiturates are extracted from a sample of serum with CHCI3, and extracted from the CHCI3 into 0.45 M NaOH (pH 13). The absorbance of the aqueous extract is measured at 260 nm and includes contributions from the barbiturates as well as other components extracted from the serum sample. The pH of the sample is then lowered to approximately 10 by adding NH4CI, and the absorbance remeasured. Since the barbiturates do not absorb at this pH, the absorbance at pH 10 is used to correct the absorbance at pH 13 thus... 

Description of Method. Fluoxetine, whose structure is shown in Figure 12.31a, is another name for the antidepressant drug Prozac. The determination of fluoxetine and its metabolite norfluoxetine. Figure 12.31 b, in serum is an important part of monitoring its therapeutic use. The analysis is complicated by the complex matrix of serum samples. A solid-phase extraction followed by an HPLC analysis using a fluorescence detector provides the necessary selectivity and detection limits. 

A serum sample treated in the same way as the standards has an initial rate of 0.313 emission intensity/s. What is the concentration of aluminum in the serum sample ... 

A 10.00-mL sample of serum is analyzed, yielding a rate of 6.84 X 10 pmol mL s h How much more dilute is the enzyme in the serum sample than in the serum calibration standard ... 

Fatal reactions to Hymenoptera stings are rare they range from 0.09 to 0.48 per million inhabitants and year [31, 32]. However, the true number may be underestimated in one study, specific IgE antibodies to Hymenoptera venoms were detected in 23% of postmortem serum samples from patients who died outdoors from unknown reasons [33]. Between 1961 and 2004, 140 fatal Hymenoptera sting reactions were registered by the federal administration for statistics in Switzerland with about 7.5 million inhabitants, resulting in an average annual fatality rate of 3.18. If these data are extrapolated to Europe with a population of around 500 million, the annual death rate in Europe would amount to about 200. 

Sample Collection and Enzyme Stability. Serum samples are collected with chemically clean, sterile glassware. Blood is allowed to clot at room temperature, the clot is gently separated from the test tube with an applicator stick, and the blood is centrifuged for 10 minutes at 1,000 g. If the red cells are known to contain the enzymes whose activity is being measured, as in the case of LD, even slightly hemolyzed serums must be discarded. When acid phosphatase is to be measured, the serum should be placed immediately in ice and processed as soon as possible, or it should be acidified by the addition of a small amount of sodium citrate. Anticoagulants such as EDTA, fluoride and oxalate inhibit some serum enzymes. However, heparin activates serum lipoprotein lipase. 

Cherry and Crandall in 1932 (86) used olive oil as substrate with gum acacia as the emufsTfier. This method has served as the basis for a number of modifications that increased the stability of the emulsion, decreased incubation time and gave better precision. When a serum sample is incubated with a stabilized olive oil emulsion, lipase acts at the interface of substrate and water to hydrolyze olive oil into fatty acid plus diglycerides, and to a small extent to monoglycerides and glycerol. The bile salt sodium deoxycholate activates the reaction. These methods measure the liberated fatty acids by titration with a standardized NaOH solution. An indicator such as phenolphatalein, thymolphthalein or methyl red or a pH meter are used to detect the end point. 

Ross, R. T. and Gonzalez, J. G. "Direct Determination of Trace Quantities of Manganese In Blood and Serum Samples Using Selective Volatilization and Graphite Tube Reservoir Atomic Absorption Spectrophotometry". Bull. Environ. 

The importance of vitamin E for maintenance of lipid integrity in vivo is emphasized by the fact that it is the only major lipid-soluble chain-breaking antioxidant found within plasma, red cells and tissue cells. Esterbauer etal. (1991) have shown that the oxidation resistance of LDL increases proportionately with a-tocopherol concentration. In patients with RA, synovial fluid concentrations of a-tocopherol are significantly lower relative to paired serum samples (Fairburn et al., 1992). The low level of vitamin E within the inflamed joint implies it is being consumed via its role in terminating lipid peroxidation and this will be discussed further in Section 3.3. 

Farrell, A.J., Blake, D.R., Palmer, R.J. and Moncada, S. (1992). Increased concentrations of nitrite in synovial fluid and serum samples surest increased nitric oxide synthesis in rheumatic diseases. Ann. Rheum. Dis. 51, 1219-1222. 

Applicability in biological ion assay is an important factor for biocompatible potentio-metric ion sensors. Attempts were made to determine Na" " concentrations in human blood sera by using silicone-rubber membrane Na+-ISFETs based on (5) [Fig. 17(a)] [29]. The found values for Na concentration in undiluted, 10-fold diluted, and 100-fold diluted serum samples are in good agreement with the Na" " calibration plots. Even in the undiluted serum samples, only a slight potential shift was observed from the calibration. This indicates that the calixarene-based silicone-rubber-membrane Na+-ISFETs are reliable on serum Na assay. For comparison with the silicone-rubber membrane, Na -ISFETs with corresponding plasticized-PVC membrane containing (2) or (5) were also tested for the Na assay. The found values of Na" " concentration... 

Bjorhall, K., Miliotis, T., Davidsson, P. (2005). Comparison of different depletion strategies for improved resolution in proteomic analysis of human serum samples. Proteomics 5, 307-317. 

Division of Research and the University of Califomia-San Francisco School of Medicine (Cohn et al., 2003). They measured pesticide metabolites in preserved postpartum maternal serum samples from 1960 to 1963. They also recorded time to pregnancy in their eldest daughters 28-31 years later. The daughters probability of pregnancy fell by 32% for each 10 mcg/1 detected, three decades after the exposure. 

Human embryo lung fibroblasts infected with a reference laboratory strain of herpes simplex virus (HS V) type 2 were used to detect antibody to HSV type 2 in serum samples. After treatment of cells with serial dilutions of sera, HRP-labeled immunoglobulins to human IgG (class G immunoglobulins) were added and detected with CL substrate [36], In both cases a sharp detection of the specific antibodies was achieved with chemiluminescent assays, which proved more sensitive than the colorimetric immunoperoxidase assays. 

Carbamazepine serum levels are usually obtained every 1 or 2 weeks during the first 2 months, and then every 3 to 6 months during maintenance therapy. Serum samples are drawn 10 to 12 hours after the dose and at least 4 to 7 days after dosage initiation or change. Most clinicians attempt to maintain levels between 6 and 10 mcg/mL, but some patients may require up to 14 mcg/mL. 

Recently, Noort et al developed a procedure that is based on straightforward isolation of adducted BuChE from plasma by means of affinity chromatography with a procainamide column, followed by pepsin digestion and LC/electrospray tandem MS analysis of a specific nonapeptide containing the phosphonylated active site serine-198 residue (5). This method surpasses the limitations of the fluoride-reactivation method, since it can also deal with dealkylated ( aged ) phosphonylated BuChE. The method allowed the positive analysis of several serum samples of Japanese victims of the terrorist attack in the Tokyo subway in 1995. Furthermore, the method could be applied for detection of ChE modifications induced by, e.g., diethyl paraoxon and pyridostigmine bromide, illustrating the broad scope of this approach. This new approach... 

Two variations of the basic technique are isoelectric focusing and immuno-electrophoresis. The former offers improved resolution and sharper bands in the separation of weak acids, weak bases and ampholytes through the use of pH and density gradients superimposed along the potential gradient. The latter employs specific antigen-antibody interactions (Chapter 10) to visualize the separated components of serum samples. 

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