Protein in CSF

X-Protein. Amyloid p i 42 peptide and r-protein have a clinical significance as early diagnostic markers in Alzheimer s disease (AD), and its evaluation is mandatory for efficient treatment. The mean levels of A/3i 42 and r-protein in CSF were significantly reduced (with high specificity and sensitivity) in patients in comparison to normal findings (M6). 

Changes in biochemical composition of CSF could serve as a useful tool for investigations of pathological processes in the CNS. CSF is also in contact wdth the blood plasma through the blood-brain barrier, thus resembling an ultrafiltrate of plasma in its protein constituents. CSF contains sugars, lipids, electrolytes and proteins. Protein concentration in CSF ranges from 0.2mg/ml to 0.8mg/ml (0.3 - 1% of serum protein concentration) wdth more than 70% of the proteins in CSF... 

Dye-Binding Methods. Dye-binding methods are based on the ability of proteins to bind dyes, such as Coumassie brilliant blue (CBB). The unequal affinities and binding capacities of individual proteins for dyes are a limitation and are complicated further by the inability to define a consistent material for use as a calibrator. The dye-binding method of greatest contemporary interest uses CBB G-250 for assay of total protein in CSF or urine. CBB binds to protonated amine groups of amino acid residues in the polypeptide chain, resulting in decreased absorbance at 465 nm and increased absorbance at 595 nm. 

The low levels of protein in CSF limit the methods that are used to measure total protein in it. Turbidimetric methods and versions of the CBB dye-binding method are commonly used for this purpose. The most serious disadvantage of turbidimetric methods is the requirement for 0,2 to 0.5 mL of sample. Coomassie Brilliant Blue (CBB) methods are sensitive enough for use with samples of as little as 25 XL> but they... 

Ailing, C., Karlsson, B., and Vallfors, B., Increase in myelin basic protein in CSF after brain surgery, J. Neurol., 223, 225, 1980. 

The main clinical significance of cerebrospinal fluid (CSF) protein electrophoresis is for the detection of the oligoclonal bands, which are present in multiple sclerosis in the gamma region. Because proteins in CSF occur at much lower concentrations than in serum (100 times less), a 10-20-fold sample concentration is needed. CSF protein separation can be accomplished in less than 10 min with CE versus 2h for AG with the ability to detect oligoclonal banding by this technique. 

Tumani, H., et al. (1998). Beta-trace protein in cerebrospinal fluid a blood-CSF barrier-related evaluation in neurological diseases. Ann. Neurol. 44, 882-9. 

It overcomes the problem of source availability. Many proteins of therapeutic potential are produced naturally in the body in minute quantities. Examples include interferons (Chapter 8), interleukins (Chapter 9) and colony-stimulating factors (CSFs Chapter 10). This rendered impractical their direct extraction from native source material in quantities sufficient to meet likely clinical demand. Recombinant production (Chapters 3 and 5) allows the manufacture of any protein in whatever quantity it is required. 

GM-CSF and IL-3 have been shown to compete for receptors in some types of cells (e.g. eosinophils and KG-1 cells), indicating some structural homology between GM-CSF and IL-3 receptors, perhaps because they share certain subunits or adapter proteins. GM-CSF occupancy results in phosphorylation of certain proteins, and because the receptor possesses no inherent kinase activity, receptor occupancy must be linked to kinase activity via the generation of second messenger molecules. Pretreatment of cells with pertussis toxin abolishes the effects of GM-CSF, indicating the involvement of G-proteins in signal transduction. Priming of neutrophil functions with GM-CSF involves the activation of phospholipases A2 and D. 

Figure 7.1. Effect of GM-CSF on neutrophil protein biosynthesis. Human neutrophils were incubated in RPMI1640 medium supplemented with 2.5% foetal calf serum and 60 jtCi/ml [35S]-methionine, in the presence and absence of 50 U/ml GM-CSF. After 4 h incubation at 37 °C, the cells were pelleted by low-speed centrifugation. The proteins in the cell pellets were precipitated by 10% trichloracetic acid and then analysed by two-dimensional polyacrylamide gel electrophoresis, using iso-electrofocussing in the first dimension. Electrophoresis in the second dimension was performed in the presence of SDS and used a 12% acrylamide gel. Source Experiment of Becky Stringer.

Finally, it can be stated that in the tropics the commonest proteins that may be detected in the CSF of normal persons are albumin, IgG, transferrin, and ceruloplasmin, the most consistent finding being the albumin. There seems to be some relationship between infections and transferrin in CSF in affected patients, and this could be fruitful ground for further research. 

Distribution - Valproic acid is rapidly distributed. Volume of distribution of total or free valproic acid is 11 or 92 L/1.73 m, respectively. Valproic acid has been detected in CSF (approximately 10% of total concentrations) and milk (about 1% to 10% of serum concentrations). Therapeutic range is commonly considered to be 50 to 100 mcg/mL of total valproate. The plasma protein binding of valproate is concentration-dependent. Protein binding of valproate is reduced in the elderly, in patients with chronic hepatic diseases, in patients with renal impairment, and in the presence of other drugs (eg, aspirin). Conversely, valproate may displace certain protein-bound drugs (eg, phenytoin, carbamazepine, warfarin, tolbutamide). 

Absorption/Distribution - Metronidazole is well absorbed after oral administration. Peak serum levels occur at about 1 to 2 hours. Metronidazole appears in CSF, saliva, and breast milk in concentrations similar to those found in plasma. Less than 20% of the circulating metronidazole is bound to plasma proteins. 

Absorption/Distribution - When acyclovir was administered to adults at 5 mg/kg by 1 hour infusions every 8 hours, mean steady-state peak and trough concentrations were 9.8 mcg/mL and 0.7 mcg/mL, respectively. When acyclovir was administered to adults at 10 mg/kg by 1 hour infusions every 8 hours, mean steady-state peak and trough concentrations were 22.9 mcg/mL and 1.9 mcg/mL, respectively. Absorption is unaffected by food. Bioavailability is between 10% and 20% and decreases with increasing doses. Concentrations achieved in CSF are approximately 50% of plasma values. Plasma protein binding is 9% to 33%. Acyclovir distributes widely in... 

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