Four protein concentration methods, applicable to cerebrospinal fluid, were compared in order to choose a procedure that not causing protein denaturation, is accurate, precise and easy to perform in routine laboratories. The studied methods were: dialysis against arabic-gum solution, centrifuge-ultrafiltration, absorption of low molecular weight substances by dry polyacrylamide gel and pressure ultrafiltration. Blood serum was diluted, then concentrated by these procedures and analyzed by cellulose acetate electrophoresis; the undiluted serum served as control. It was observed that two methods: pressure ultrafiltration and absorption of low molecular weight substances by polyacrylamide hydrogel, are not suitable for concentrating diluted fluids because they frequently cause protein denaturation. It was concluded that dialysis against arabic-gum is the most suitable, of the methods studied, for application in routine laboratories taking in account that this procedure is precise, relatively accurate, simple and of low cost.
The total protein content and protein fractions, obtained by electrophoresis on cellulose acetate strips, of CSF collected from the cisterna magna of 213 patients (with no neurological diseases) were determined in order to verify variations related to race, sex and age, as well as to establish the proteinogram normal limits. No differences between caucasians and coloured persons were observed with respect to CSF total protein and protein fractions. Children (5 months to 11 years old) do not present differences related to sex or age, on their proteinogram. Children's CSF total protein, relative values of pre-albumin, alpha 1--and beta-globulins, absolute values of albumin, alfa 2--, beta--, tau --and gamma-globulins, differ from those found in adults. Differences between males and females in the normal CSF proteinogram were found in adults. As a consequence of these findings, the CSF proteinogram normal limits for children, males and females were separately established. In adults, statistically significant positive correlation between age and the 7 protein fractions when expressed in mg/100 ml were observed, as well as between age and total protein. Comparison of the results obtained in this research with those found in some publications was carried out and is briefly discussed.
The literature on quantitation of immunoglobulins in normal CSF and variations of these values related to race, sex and age was reviewed. Immunoglobulins (Ig) G, A and M of normal CSF (sub-occipital puncture) of 116, 78 and 45 patients respectively, were measured by radial immunodiffusion, in order to verify variations related to race, sex and age, as well as to establish their normal limits. The results allowed us to conclude that: a) there are no differences between races with respect to the levels of IgG, A and M; b) variations related to sex or age on the CFS immunoglobulins content in children (1 to 11 years old) are not found; c) the mean IgG (mg/100 ml) level in children is lower than in adults, although the mean IgG percentage concentration in children is not different from that found in adults; the normal range for CSF IgG in children is 0.21 to 2.93 mg/100 ml; d) the mean IgA content (mg/100 ml and % of the total protein) in children are lower than in adults and in physiological conditions do not exceed 0.15 mg/100 ml (0.7% of the total protein); e) there are no differences related to sex or age with respect to the CSF levels of immunoglobulins in adults; the normal range of IgG in adults is 0.51 to 4.00 mg/100 ml; in children and adults the normal limits for the relative values of IgG are 3 to 12%; IgA is found in the CFS of adults in a concentration up to 0.32 mg/100 ml (0.9%); f) IgM is found in both children's and adults' CSF at very low levels, not exceeding 0.2 mg/100 ml (0.25%). Comparison of the results obtained in this work with those found in some publications was carried out and is briefly discussed.
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