Development of cerebrospinal fluid and the blood-cerebrospinal fluid barrier in rabbits.

Blood plasma and cerebrospinal fluid (CSF) samples were collected from adult female rabbits (New Zealand White), newborn, and embryos at 18, 20, 24, and 28 days of gestation. Samples were analyzed for total protein using the Folin phenol reagent. During development, mean total protein of blood plasma rose sharply from 12.45 to 12.51 mg/ml at 18 to 20 days to 37.56 mg/ml at 28 days. Levels further increased to 54.06 mg/ml in the newborn and to 66.18 mg/ml in the adult. The protein concentration of cerebrospinal fluid was constant at 5.20 to 5.29 mg/ml between 18 and 20 days of gestation, but steadily decreased to 3.53 mg/ml at 28 days. By birth, the CSF protein concentration was further reduced to 2.08 mg/ml, and this level differed only slightly (P < 0.05) from CSF protein values determined for adults. These data indicate that the blood-cerebrospinal fluid barrier to proteins begins to function by 18 to 20 days of gestation, and the protein concentration of cerebrospinal fluid approaches the normal adult value soon after birth.     

Structural basics for development of blood-cerebrospinal fluid barrier in man

Studies of development of hematoliquorian barrier in man represent significant difficulties, as it is not possible to employ the experimental-physiological approaches. In these conditions, the morphological analysis based on application of modern immunocytochemistry methods acquires the key role in fundamental physiological studies of onthogenesis of barrier central neurology systems. The current article presents an analytical review of publications and results of own authors research of structural organization of the hematoliquorian barrier in man during the prenatal ontogenesis.     

Quantification of albumin in cerebrospinal fluid

A standard spectrophotometric method for the quantitation of urinary albumin using bromphenol blue is evaluated to determine whether this method could be used to quantify cerebrospinal fluid albumin. In the modified procedure, 200 microliters of sample is added to 3 ml of bromphenol blue solution and the absorbance is read spectrophotometrically at 610 nm. Using standards and controls, the results were compared with known values and found to be both precise and accurate. The bromphenol blue method was compared with an immunoturbidometric method and found to be more precise and accurate, easier to perform, and cost effective. When compared to other dye-binding methods the bromphenol blue method is unique in its extremely low linear range and limit of detection. A minor disadvantage was the increased sample size necessary to obtain the increased precision.     

Side chain oxidized oxysterols in cerebrospinal fluid and the integrity of blood-brain and blood-cerebrospinal fluid barriers

The side chain oxidized oxysterol 24S-hydroxycholesterol (24-OH-chol) is formed almost exclusively in the brain, and there is a continuous passage of this oxysterol through the circulation to the liver. 27-Hydroxycholesterol (27-OH-chol) is produced in most organs and is also taken up by the liver. The 27-OH-chol-24-OH-chol ratio is about 0.1 in the brain and about 2 in the circulation. This ratio was found to be about 0.4 in cerebrospinal fluid (CSF) of asymptomatic patients, consistent with a major contribution from the circulation in the case of 27-OH-chol. In accordance with this, we demonstrated a significant flux of deuterium labeled 27-OH-chol from plasma to the CSF in a healthy volunteer. Patients with a defective blood-brain barrier were found to have markedly increased absolute levels (up to 10-fold) of both 27-OH-chol and 24-OH-chol in CSF, with a ratio between the two sterols reaching up to 2. There was a significant positive correlation between the levels of both oxysterols in CSF and the albuminCSF-albuminplasma ratio. The 27-OH-cholCSF-24-OH-cholCSF ratio was found to be about normal in patients with active multiple sclerosis and significantly increased in patients with meningitis, polyneuropathy, or hemorrhages. Results are discussed in relation to the possible use of 24-OH-cholCSF as a surrogate marker of central nervous system demyelination and/or neuronal death.     

Strain-dependent disruption of blood-cerebrospinal fluid barrier by Streptoccocus suis in vitro

Streptococcus suis capsular type 2 is an important agent of diseases including meningitis among pigs worldwide, and is also a zoonotic agent. The barrier function of the choroid plexus epithelium that constitutes the structural basis for the blood-cerebrospinal fluid (CSF) barrier has not been elucidated yet in bacterial meningitis. We investigated the influence of various S. suis isolates on the barrier function of cultured porcine choroid plexus epithelial cells with respect to the transepithelial resistance and paracellular [(3)H]-mannitol flux. Preferentially apical application of S. suis isolates significantly decreased transepithelial resistance and significantly increased paracellular [(3)H]-mannitol flux in a time-, dose- and strain-dependent manner. Viable S. suis isolates caused cytotoxicity determined by lactate dehydrogenase assay and electron microscopy, whereas S. suis sonicates and UV-inactivated S. suis did not cause cytotoxicity. The observed effects on porcine choroid plexus epithelial cells barrier function could not exclusively be ascribed to known virulence factors of S. suis such as suilysin. In conclusion, S. suis isolates induce loss of blood-cerebrospinal fluid barrier function in an in vitro model. Thus, S. suis may facilitate trafficking of bacteria and leucocytes across the blood-cerebrospinal fluid barrier. The underlying mechanisms for the barrier breakdown have yet to be determined.     

Interaction of alpha 2-macroglobulin with trypsin, chymotrypsin, plasmin, and papain

The interaction alpha 2-macroglobulin with four proteinases has been investigated by binding assays and by gel electrophoresis. At pH 7.65 the binding ratios of the proteinase-alpha 2-macroglobulin complexes were found to be 2:1 (trypsin and papain), 1.4:1 (chymotrypsin), and 1:1 (plasmin). The progressive decrease in the stoichiometry of the three seryl proteinase complexes was paralleled by a concomitant decrease in the proteinase-dependent specific cleavage of the alpha 2-macroglobulin peptide chains. Rate studies have shown that the relative rates of reaction of the proteinases with alpha 2-macroglobulin also varied greatly: papain greater than trypsin greater than chymotrypsin greater than plasmin. The data suggest that the ability of a proteinase to saturate the second proteinase binding site is a reflection of its ability to bind to alpha 2-macroglobulin and cleave the second pair of scissile alpha 2-macroglobulin peptide bonds before the alpha 2-macroglobulin has undergone the conformational change initiated by the formation of the 1:1 proteinase alpha 2-macroglobulin complex.     

Covalent and non-covalent interaction of chymotrypsin with alpha 2-macroglobulin

The pattern of covalent crosslinking between human alpha 2-macroglobulin (alpha 2M) and chymotrypsin has been investigated by chromatography and polyacrylamide gel electrophoresis in denaturing medium. Reaction with a single mol of chymotrypsin per mol alpha 2M results in the formation of a 95% covalent 1:1 chymotrypsin-alpha 2M complex and in the proteolytic cleavage of both 180 kDa monomers in one alpha 2M subunit. Proteolytic cleavage in the other alpha 2M subunit requires the presence of a second mol of chymotrypsin; part (20%) of the protease in the 2:1 chymotrypsin-alpha 2M complex thus formed appears to be non-covalently bound to the alpha 2M chains. Covalent binding is abolished when the reaction of alpha 2M with the protease is carried out in the presence of hydroxylamine. A single mol of the protease is then able to cleave all four 180 kDa monomers in alpha 2M.     

Impact of manganese on and transfer across blood-brain and blood-cerebrospinal fluid barrier in vitro

Manganese occupational and dietary overexposure has been shown to result in specific clinical central nervous system syndromes, which are similar to those observed in Parkinson disease. To date, modes of neurotoxic action of Mn are still to be elucidated but are thought to be strongly related to Mn accumulation in brain and oxidative stress. However, the pathway and the exact process of Mn uptake in the brain are yet not fully understood. Here, two well characterized primary porcine in vitro models of the blood-brain and the blood-cerebrospinal fluid (CSF) barrier were applied to assess the transfer of Mn in the brain while monitoring its effect on the barrier properties. Thus, for the first time effects of MnCl(2) on the integrity of these two barriers as well as Mn transfer across the respective barriers are compared in one study. The data reveal a stronger Mn sensitivity of the in vitro blood-CSF barrier compared with the blood-brain barrier. Very interestingly, the negative effects of Mn on the structural and functional properties of the highly Mn-sensitive blood-CSF barrier were partly reversible after incubation with calcium. In summary, both the observed stronger Mn sensitivity of the in vitro blood-CSF barrier and the observed site-directed, most probably active, Mn transport toward the brain facing compartment, reveal that, in contrast to the general assumption in literature, after oral Mn intake the blood-CSF barrier might be the major route for Mn into the brain.     

Development of blood-cerebrospinal fluid barrier to horseradish peroxidase in the avian choroidal epithelium

Summary Four neurons in the brain of the migratory locust were immunohistologically identified with an anti-met-enkephalin antiserum. The perikarya of two of these cells are located in the center of each of the two groups of lateral protocerebral neurosecretory cells. The fibres coming from these perikarya terminate in numerous immunoreactive ramifications visible at the periphery of both tractus I to the corpora cardiaca, through which pass the neurosecretory products of the pars intercerebralis. The other two cell bodies are located at the bases of the two optic lobes; their fibres enter the posterior part of the protocerebrum and ramify around the root of the nervus corporis cardiaci II, another area through which neurosecretory products pass. The topographic distribution of these met-enkephalin arborizations suggests that these four neurons may act as neuromodulators of the acitivity of the major neurosecretory cells in the brain of this insect.     

Stoichiometry of reactions of alpha 2-macroglobulin with trypsin and chymotrypsin.

The stoichiometry of the individual steps, i.e. polypeptide chain cleavage, hydrolysis of the putative thioester bond and conformational change, of the reaction between alpha 2-macroglobulin and trypsin or chymotrypsin was analysed. The chain cleavage was monitored by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, the thioester hydrolysis by both a spectroscopic and a fluorimetric technique and the conformational change by tryptophan fluorescence. A stoichiometry of close to 2:1 was obtained for all reactions. This finding indicates that the alpha 2-macroglobulin half-molecule is an independent functional unit of the inhibitor, within which co-operativity between the two subunits may occur.     

Relationship of total lipids,proteins, and albumin in human cerebrospinal fluid with age

A study of the changes with age in the concentrations of macro- and micromolecular components in human cerebrospinal fluid (CSF) was conducted to assess indirectly the alterations in blood-brain-CSF barriers during the aging process. Human CSF was obtained from adult patients ranging in age from 27 to 71 years during routine clinical myelographic examinations. Total lipids in the CSF were assayed spectrophotometrically using the sulfo-phospho-vanillin reaction. Albumin contents were assayed by immuno-nephelometry and the total protein levels were assayed by the Lowry method. The 42 subjects were divided into the normal CSF protein group (protein concentration ≤50 mg/dl) and the elevated CSF protein group (protein concentration >50 mg/dl). The average CSF total lipid level on these subjects was very low: 0.78 mg/dl for the group with normal CSF protein levels, and 1.4 mg/dl for the elevated-CSF protein group. The CSF total lipid levels had a significantly positive correlation with total protein in both groups, suggesting that the entry of the small endogenous lipid molecules into the CSF is governed by their affinity of binding to the macromolecular proteins. There were no significant correlations between CSF total lipids, total proteins, or albumins with age in either the low or high CSF protein groups. It is suggested by the data that in man the blood-brain-CSF barriers are not altered with age.