Protein cerebrospinal fluid content

The determination of ammonia after the regular or modified Kjeldahl digestion presents rather less serious problems than those already dis cussed. The advantages of the micro-Kjeldahl distillation (69, 80, 81, 82, 83) as compared with the macro>method, or even the semimicro-method are now generally recognized. A comparative study of the macro-and microscale determination in the analysis of flour, wheat and com for their protein content was made by Robinson and Shellenberger (27). The micro-Kjeldahl method has been used for systematic plasma protein analysis (84, 85), saliva proteins (86), milk proteins (87), and cerebrospinal fluid protein (88),... 

Hypothalamic content and mRNA levels of TNF-a peak during the early light period, when NREM sleep is maximal, in the rat (70,71). IL-1-like activity varies with the sleep-wake cycle in the cerebrospinal fluid of cats (72). IL-lp protein levels in plasma (73) and hypothalamic IL-lp mRNA levels (74) are highest during the sleep period in rats. Sleep deprivation increases IL-ip and TNF-a mRNA levels in the hypothalamus (75-77) and expression of the 55-kD TNFR is also stimulated in the brain (77). In humans, peak levels of IL-1 occur at sleep onset in the blood (78) and IL-1 blood levels also increase during sleep deprivation (79). Blood levels of TNF-a correlate with EEG slow-wave activity (80), and concentrations of circulating TNF-a and the soluble 55-kD TNFR increase after sleep deprivation in humans (81). 

Contrasting milieux. Cerebrospinal fluid has a low content of albumin and other proteins compared with plasma. 

The bioanalyst can be required to analyse most biofluids although the most common are urine and the aqueous phase of blood, i.e. plasma or serum. Other samples may be cell and tissue extracts, synovial fluid, cerebrospinal fluid (CSF) and saliva. In the case of urine and CSF with their very low protein content it might be possible to directly inject the sample into an HPLC column. With most silica-based packing materials, direct injection of blood proteins will rapidly lead to column deterioration. HPLC columns are expensive and their efficiency is easily lost so correct preparation of samples will not only improve column life but also improve the results. At its simplest it is only necessary to remove particulate matter from samples to prevent clogging of the column and frits. Modern HPLC packings are very susceptible to contamination by proteins, fats and other macromolecules from biological samples and it is necessary to remove these (except of course for protein analysis). 

Chronic intoxication with vitamin A has been reported to cause variously hypercalcemia, hyperglycae-mia, increased alkaline phosphatase, hypoproteinemia, hypoprothrombinemia, increased sulfobromphthalein retention, raised serum transaminases, low serum ascorbic acid, reduced protein content of the cerebrospinal fluid, raised urinary hydroxyproline, and hypercalciuria (SED-8, 800) (14). It is not always clear, however, whether these deviations are a cause or an effect of hypervitaminosis A. 

Protein content, particularly in urine or cerebrospinal fluid, may also be estimated by methods based on precipitation using sulfosalicylic acid (an anionic protein precipitant) or heat. The turbidity, which is a measure of protein concentration, can be quantitated by spectropho-tometric absorbance methods or light scattering analysis. Absorbance of a hydrophobic indicator dye that binds to protein and changes color is also used. 

The polarographic method based on the suppression of maxima is very simple but seldom suitable for analysis because of its high sensitivity and lack of specificity. For this reason its practical use is limited. The extraordinary sensitivity of this method suggests its application to examinations of very small samples of materials, having a low protein content. Biological fluids having these properties include the lymph, transudates, intraocular humors, blister fluids, cerebrospinal fluid, and others (13). 

The false maximum observed in the presence of sodium ions was investigated in an attempt at a clinical use in 550 samples of cerebrospinal fluids. The experiment proved that an increase in the protein content in the cerebrospinal fluid was always manifested by the appearance of the maximum. However, the question whether this phenomenon will ever And any application to clinical examinations still remains open. 

Earlier examinations of cerebrospinal fluid were performed on the basis of suppression of polarographic maxima (214). The estimation of total protein in 0.1 ml of cerebrospinal fluid, calculated from the percentile depression of the maximum, is in fact an estimation of surface-active substances although protein is much active in this respect, the method represents no specific determination of protein. The same author (214) and also further authors (215) also made use of the pre-sodium wave and of the protein wave in buffered solutions of Co salts, but here also no parallelity was found between the wave height and the protein content, since the number of polarographically active groups present was variable. 

No regular dependence exists between the wave height and the total protein content in the cerebrospinal fluid (220,222). Similarly, there exists no dependence of the resulting value upon the count of elements in the cerebrospinal fluid (220), nor any correlation with the colloidal gold or silver tests, nor with the glucose or chloride levels (223). 

Clinical laboratories have to be able to determine a wide range of analytes. These encompass a wide range ions, small organic molecules, proteins, and lipids. Typically measurements are made on biological fluids. Most determinations are performed on plasma (or serum) the liquid fraction of blood, or urine occasionally other fluids such as cerebrospinal fluid may be examined. While some of the measurements relate directly to pathology in the blood cells or plasma, many are markers of changes happening at the cellular level. Cell destruction releases intracellular contents, e.g., enzymes, tumors release products cell dysfunction causes buildup or diminution of normal concentrations of molecules. 

The protein content of urine and cerebrospinal fluid is much lower than that of blood, and dilution is often the only sample treatment necessary. However, protein removal is necessary before reversed-phase column chromatography to protect the lifespan of the column. Sample dilution helps reduce the presence of proteins, but even running untreated urine samples diluted 50-fold can very quickly destroy a column. 

The brain is prone to suffer oxidant damage due to its relatively low content of antioxidant enzymes (Carrillo et al. 1992) and its high content of iron, as shown in neuromelanin by Laser microprobe mass analysis (LAMMA) (Good et al. 1992). Immu-noreactive catalase protein decreased in the hypothalamus and the prefrontal cortex of the ageing rat brain (3 vs. 12 months) by 63 and 55 %, respectively (CiRiOLO et al. 1997). Iron will be easily released when the cells are injured and cannot be safely bound as cerebrospinal fluid has not any significant iron binding capacity. The toxicity of 02 " has been... 

The cerebrospinal fluid is usually normal, though the protein content may be raised. EEG abnormalities are not very specific and are not related to the severity of the neurological symptoms. The alpha rhythm is more or less preserved but is associated with delta and theta waves (14 —17 ). 

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