All-trans retinol and retinol-binding protein from embryonic cerebrospinal fluid exhibit dynamic behaviour during early central nervous system development.

Embryonic cerebrospinal fluid (E-CSF) is involved in the regulation of survival, proliferation and neurogenesis of neuroectodermal progenitor cells, as well as in the control of mesencephalic gene expression in collaboration with the isthmic organizer. Recently, we showed the presence of retinol-binding protein (RBP) within the E-CSF proteome. RBP is an all-trans retinol carrier, a molecule that can be metabolized into retinoic acid, a morphogen involved in central nervous system (CNS) morphogenesis and patterning. Here we demonstrate the presence of all-trans retinol within the E-CSF and analyse the dynamics of RBP and all-trans retinol within this fluid, as well as the expression of retinoic acid-synthesizing enzymes during early CNS development. Our results suggest a relationship between the dynamics of these molecules and the early events of CNS patterning.

Characterisation of transthyretin and retinol-binding protein in plasma and cerebrospinal fluid of dogs.

The aim of this study was to investigate differences in concentrations of vitamin A, transthyretin (TTR) and retinol-binding protein (RBP) between plasma and cerebrospinal fluid (CSF) in dogs. RBP was detected using ELISA, and both RBP and TTR by Western blot analysis after separation on SDS-PAGE. Vitamin A was determined by high performance liquid chromatography. RBP and TTR as well as vitamin A were detected in all samples but at substantially lower concentrations in CSF compared to plasma. RBP in dog plasma showed a similar molecular mass to that of humans, whereas canine TTR had a lower molecular mass. Comparison between plasma and CSF showed that both RBP and TTR were of lower molecular mass in CSF. In CSF, RBP and retinol were present at 10-100-fold lower concentrations compared to plasma. Retinyl esters were present only in minute amounts in 5/17 samples. In conclusion, the CSF of dogs compared to humans is significantly different in terms of both quality and quantity of transport proteins for vitamin A.

Transthyretin, thyroxine, and retinol-binding protein in human cerebrospinal fluid: effect of lead exposure.

Transthyretin (TTR), synthesized by the choroid plexus, is proposed to have a role in transport of thyroid hormones in the brain. Our previous studies in animals suggest that sequestration of lead (Pb) in the choroid plexus may lead to a marked decrease in TTR levels in the cerebrospinal fluid (CSF). The objectives of this study were to establish in humans whether TTR and thyroxine (T(4)) are correlated in the CSF, and whether CSF levels of Pb are associated with those of TTR, T(4), and/or retinol-binding protein (RBP). Eighty-two paired CSF and blood/serum samples were collected from patients undergoing clinical diagnosis of CSF chemistry. Results showed that the mean value of CSF concentrations for TTR was 3.33 +/- 1.60 microg/mg of CSF proteins (mean +/- SD, n = 82), for total T(4) (TT(4)) was 1.56 +/- 1.68 ng/mg (n = 82), for RBP was 0.34 +/- 0.19 microg/mg (n = 82), and for Pb was 0.53 +/- 0.69 microg/dl (n = 61 for those above the detection limit). Linear regression analyses revealed that CSF TTR levels were positively associated with those of CSF TT(4) (r = 0.33, p < 0.005). CSF TTR concentrations, however, were inversely associated with CSF Pb concentrations (r = -0.29, p < 0.05). There was an inverse, albeit weak, correlation between CSF TT(4) and CSF Pb concentrations (r = -0.22, p = 0.09). The concentrations of TTR, TT(4), and Pb in the CSF did not vary as the function of their levels in blood or serum, but RBP concentrations in the CSF did correlate to those of serum (r = 0.39, p < 0.0005). Unlike TTR, CSF RBP concentrations were not influenced by PB: These human data are consistent with our earlier observations in animals, which suggest that TTR is required for thyroxine transport in the CSF and that Pb exposure is likely associated with diminished TTR levels in the CSF.

Low molecular weight plasma proteins in the cerebrospinal fluid of children with hematological malignancies.

The concentration of beta-2-microglobulin (beta 2-m) and of post gamma globulin (P gamma G) was examined in serum and cerebrospinal fluid from children with acute lymphatic leukemia (ALL) and non-Hodgkin's lymphoma (NHL). Data were analysed in order to determine whether concentration of beta 2-m or P gamma G during remission would be of value in predicting relapse or eventual outcome. Mean serum concentration of beta 2-m was similar in good and poor prognosis patients with ALL in remission and was not significantly altered in CNS or marrow relapse. Mean CSF concentration in NHL was also similar in both prognostic groups, and in poor prognosis patients was not significantly altered in relapse. The same pattern was seen when P gamma G was measured in CSF (serum concentration of this protein being too low for accurate determination). High within patient variability of levels of beta 2-m and P gamma G appeared to relate to chemotherapy rather than the disease process. Concentration of P gamma G was persistently raised in three children with brain damage of differing etiologies. Levels of two other low molecular weight proteins, retinol binding protein and alpha 1-microglobulin, were also determined in order to establish that beta 2-m and P gamma G concentration was not influenced by alteration in permeability of the blood-brain barrier. The beta 2-m and P gamma G concentration, although higher than reported in healthy children [5] does not appear to be of value as a prognostic indicator in ALL and NHL in children.

Latex immunoassay of retinol-binding protein.

Latex immunoassay, a sensitive method based on latex particle agglutination, is used here for the determination of retinol-binding protein in human biological fluids. The assay, similar to that described previously for beta 2-microglobulin (Clin. Chem. 27:832-837, 1981), consists of incubating the sample at 37 degrees C for 30 min with antibody-coated particles, then quantifying the resulting agglutination by particle-counting or turbidimetry. Latex particles coated with antibody are stabilized just before use by dispersing them in a solution of bovine serum albumin at pH 10. The standard curve ranges from 0.5 to 32 micrograms/L; recovery averages 102% in urine and 93.5% in serum; between- and within-assay CVs range from 5.1 to 11.7%. The correlation coefficients of latex immunoassay with rocket immunoelectrophoresis for analysis of retinol-binding protein in 26 urines and with radial immunodiffusion in 30 sera are 0.99 and 0.91, respectively. In healthy subjects, the mean urinary excretion of retinol-binding protein is 52.5 micrograms/g of creatinine (SD = 59.2 micrograms/g of creatinine; n = 150) and the concentration in serum averages 46 mg/L (SD = 10.4 mg/L, n = 22).