Protein and nucleic acid content in the aging human brain

The frontal cortex, white matter, cerebellum, caudate nucleus, thalamus and putamen of human brains, ranging from 16 to 91 years, were assayed for protein and nucleic acids. In all these areas the protein content decreased by 5--15% between 30 years and 90 years-of-age. The nucleic acid content, however, did not show any significant change. During a post-mortem interval of 6--25 hours there was no significant decrease found in either the protein or the nucleic acid content of brain tissue.

[Study of the constituent proteins of brain structures by the technic of electrophoresis in a continuous polyacrylamide gel gradient in capillaries]

The author compared the protein composition of the brain structures (premotor zone of the cortex, CA3 are of the hyppocampus, the caudate nucleus, the frontal lobe of the cerebellum) in rats by electrophoresis in the continuous gradient of polyacrylamide gel pores in capillaries. The method used proved to possess a much greater resolving capacity in comparison with electrophoresis in the homogeneous gel concentration; no differences could be revealed in the protein composition of the brain structures under study.

Biochemical and immunological studies with human optic and olfactory tracts

Clinical and pathological studies have revealed that in multiple sclerosis (MS) the involvement of the optic tracts is much more frequent than that of the olfactory tracts. To investigate the possible reasons for this difference in involvement of these two adjacent structures, both containing a central type myelin, we have studied optic and olfactory tracts obtained at autopsy from 7 adult males ranging in age from 54 to 64 years. White matter from the frontal poles of the same individuals was used for reference. These tissues were compared with respect to the relative content of a) water, b) soluble proteins, c) 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) activity, and d) immunologically precipitable basic protein (BP). Homogenates from these tissues were further compared by disc gel electrophoresis in two systems; phenolformic acid-water and SDS-urea gels. Results indicate that while the optic tracts and the frontal pole white matter were similar with respect to their water, total protein content and BP content, the optic tracts had lower CNP activity than the frontal poles. The olfactory tracts contained more water and less BP and the CNP activity of these structures was lower than that of the frontal pole white matter. Assuming the CNP activity and the BP content are true measures of the total myelin content of a given tissue, it appears that olfactory tracts have smaller amounts of myelin. On the other hand, the optic tracts contain only half as much CNP-activity with a disproportionately greater amount of BP. The possible significance of these findings is discussed.

Determination of choline and acetylcholine in distinct rat brain regions by stable isotope dilution and field desorption mass spectrometry

The determination of choline and acetylcholine by field desorption mass spectrometry from rat brain tissue samples has been demonstrated. Essential points of the assay are the use of stable isotope labelled internal standards, a simple ion pair extraction procedure, direct analysis of the quaternary ammonium ions without derivatization, and accumulation of the electrically recorded field desorption ion signals with a multi-channel analyser. The analysis of sample amounts in the picogram range gave quantitative data of good precision (0.6--10% standard deviation).

RNA content and volume of nerve cell bodies in human brain. I. Prefrontal cortex in aging normal and demented patients

The age-related change in the neuronal RNA content, volume, and the RNA concentration of 2,160 single cell bodies was examined from the prefrontal cortex. Human brains from 15 normal and 3 demented patients of ages ranging from 8 months to 94 years were obtained at post-mortem examination. The neuronal RNA showed an adult level at age 9 years and remained unchanged until age 66; the mean RNA content was 27.15 pg during this period of time. A decline in the RNA content followed with increasing ages, but it leveled off to an average of 17.97 pg after the age of 80 years. A comparative observation of morphological changes of normal and demented patients reveal the quantitative spectrum of senile plaques. In spite of the presence of significantly more senile plaques, patients with senile dementia showed the RNA content and the volume of the cell body like those of normal patients of similar age. There seems to be no criterion which is characteristic of senile dementia in terms of the RNA content in cortical cell bodies.

Distribution of myosin and the glial fibrillary acidic protein (GFA protein) in rat spinal cord and in the human frontal cortex as revealed by immunofluorescence microscopy

The glial fibrillary acidic (GFA) protein and myosin were localized in rat spinal cord and human frontal cortex using specific antibodies against GFA protein from human spinal cord and highly purified smooth myosin from chicken gizzard by means of an indirect immunofluorescence microscopical approach. A strong GFA protein and myosin immunoreactivity was found in astrocytes of the white and grey matter and in the external glial limitans membrane. The very fine branches of astrocytic processes stained with anti-GFA protein, but not with anti-myosin. Similar results were obtained with the human frontal cortex, where myosin antibodies failed to reveal the very fine branches of protoplasmic astrocytes. As a whole, staining with the GFA protein antiserum was more crisp than with the myosin antibody.

Brain-aluminium concentration in dialysis encephalopathy

Brain-aluminium concentrations were found to be significantly higher in 7 patients dying with dialysis encephalopathy (mean 15.9 microgram aluminium/g dry weight) than in 11 dialysed controls (4.4 microgram/g) and in 2 uraemic patients who were not dialysed (2.7 microgram/g). The grey matter from the patients with dialysis encephalopathy contained about three times as much aluminium as white matter. The results suggest that dialysis with untreated and/or softened tap-water (aluminium concentration 0.1-1.2 mg/1) makes the major contribution to brain-aluminium levels; dialysis with deionised water (aluminium concentration normally less than 0.02 mg/1) and intake of phosphate-binding AL(OH)3 gel are less important. Brain aluminium levels remain elevated for up to four years after restoration of good renal function by transplantation. The association of dialysis encephalopathy with high levels of aluminium in the brain and in the dialysis water emphasises the potential neurotoxicity of aluminium in man.

Noradrenaline neuron innervation of the neocortex in the rat

Noradrenaline innervation of the rat neocortex is studied by glyoxylic acid histochemistry and radioisotopic biochemical analysis. The data indicate that all neocortical areas receive a noradrenergic innervation which is identical in organization but varies in density from area to area. Radioisotopic analysis of catecholamines in the cortical areas studied reveals only the presence of significant levels of noradrenaline. Unilateral locus coerulus ablation greatly diminishes ipsilateral noradrenaline content and fiber innervation in all neocortical areas studied. Detailed histochemical analysis reveals a diffuse plexus-like arrangement of noradrenaline fibers, with each cortical layer having a distinctive pattern of innervation. Single noradrenergic fibers enter layer VI of cortex and branch at all levels to undergo extensive collateralization. Terminal horizontal branching in the molecular layer results in the most dense fiber plexus of all cortical layers. This pattern of noradrenaline innervation is similar to that of other non-specific afferent systems innervating neocortex.

Cortico-striate projections in the rhesus monkey: the organization of certain cortico-caudate connections

The organization of cortical projections to the caudate nucleus was investigated in the rhesus monkey, using the autoradiographic tracing method. Following injections of tritiated leucine and proline into selected pre- and post-Rolandic association areas in the frontal, parietal, occipital and temporal lobes, widespread projections were observed to one, or more typically, more than one of the major subdivisions of the caudate nucleus. When cortical areas having strong reciprocal cortico-cortical connections were compared, a considerable communality of their cortico-caudate projections was noted; depending on the location of the cortical areas, the region of common distribution lay within the head, the body, or the tail of the caudate nucleus. This correlation between cortico-cortical and cortico-striate projections characterized all pairs of cases studied. It suggests a previously undescribed principle of organization within the telencephalon, namely, that areas of cerebral cortex having reciprocal cortico-cortical connections, while having unique overall patterns of projection to the caudate nucleus, project, in part, to one and the same region of the nucleus. This might imply that a given region of the caudate nucleus receives input not only from a particular area of cortex, but also from all other cortical areas reciprocally interconnected with that area.

S-100 in the central nervous system of rat, rabbit and guinea pig during postnatal development

The accumulation of the brain-specific S-100 protein has been studied during postnatal development of rat, rabbit and guinea pig quantitatively, using immunoelectrophoresis, and qualitatively, by immunoelectron microscopy. Newborn guinea pigs show high levels of S-100. The distribution was similar to that of adult animals with an enrichment of S-100 to the postsynaptic membranes and to the astrocytic filaments. The neuronal plasma membranes as well as the neuronal nuclear membranes, astrocytic and oligodendroglial plasma membranes, also showed a specific activity for S-100. The amount of S-100 increased linearly from birth until the 3rd and 4th postnatal week of rabbit and rat, respectively. During the 2nd and 3rd week rabbit and rat nervous systems showed an accumulation of S-100, especially in the postsynaptic membranes and in the astrocytic filaments. In this study we present evidence that the S-100 protein quantitatively and ultrastructurally appears according to a pattern which parallels the muturation of brain, showing adult characteristics already at birth in early developing brains (guinea pig) and a change towards adult pattern after birth in late developing brains (rat and rabbit). In the latter two species change towards an adult S-100 distribution pattern proceeds during the postnatal period concomitant with the enzymatic and electrophysiogical maturation of the brain.

Qualitative and quantitative studies on human myelin basic protein in situ with respect to time interval between death and autopsy

Normal human frontal lobe white matter obtained at autopsy was used to determine the extent of in situ post-mortem degradation of myelin basic protein (BP). Effects of the following two factors were studied: 1) time interval between death and autopsy, and 2) freezing and thawing the tissue. Quantitative extraction of BP from the autopsy material showed only minimal loss of BP that could be attributed to the time interval between death and autopsy (up to 48 h). The purified BP from these samples was electrophoresed on acrylamide gels at pH 4.3 and it was found that the electrophoretic patterns were comparable to zero hour bovine BP samples. The BP obtained from the autopsy samples was found to be encephalitogenic in guinea pigs. When tested against rabbit anti-human-BP serum, the purified BP preparations gave a single arc in immunoprecipitin test. BP extracted and purified from tissue that was frozen once and processed before it could thaw showed yields, encephalitogenic activity and acrylamide disc gel electrophoretic patterns that were similar to those of BP from tissue that was never frozen. However, frozen tissue that was thawed and then incubated for 8 h at room temperature before processing yielded only 13-25% of the total extractable protein. This BP also was encephalitogenic and showed acrylamide banding pattern that was similar to BP from tissue that was never frozen. Samples of white matter were examined by electron microscope. Unfrozen autopsy material showed some separation of myelin lamellae. Myelin in sections of frozen and thawed white matter showed separation as well as disruption of the lamellae. Samples that were frozen, thawed and then incubated at room temperature for 8 h showed sporadic loss of dense line material in addition to lamellar separation and disruption. The results a) show that BP is quite resistant to autolytic changes and b) are consistent with the location of BP along the cytoplasmic surface of the myelin membrane.

[Catecholaminergic axons in the human cerebral cortex. Observation by histofluorescence of cerebral biopsies in 2 cases of Alzheimer's disease]

Catecholamine axons have been visualized in human cerebral cortex obtained during routine neurosurgical operations. The fluorescence histochemical method of Lindvall et al. was used, slightly modified (calcium-deprived buffer, glyoxylic acid fixation followed by formaldehyde vapours exposition). The frontal cortex was more richely provided with catecholamine terminals than the parietal cortex. Two general types of axon morphology are evident. The most frequent is thin and sinous, sometimes forming clews, or loose basket-like arrangement around presumed nerve cells. The other one is moniliform and demonstrates spherical evenly-spaced varicosities. They look like, respectively, the well characterized dopaminergic and noradrenergic axons of the rat cerebral cortex. In two cases of Alzheimer's disease, noradrenergic-like fibers were missing and voluminous green-fluorescent varicosities, sometimes in obvious connection with typical axons, were observed in the proximity of senile plaques.

Human myelin basic proteins: a comparison of proteins from six different anatomic sites

Myelin basic proteins were isolated from six different anatomic sites of the human nervous system and were compared with regard to the yield, encephalitogenic activity, and electrophoretic pattern in polyacrylamide gel. The yield of basic proteins decreased progressively from the central to the peripheral nervous system. Basic protein extracted from human oculomotor nerve induced experimental allergic encephalomyelitis in 44 percent of guinea pigs injected with the extract. Patterns obtained after electrophoresis in 15 percent and 5 percent acrylamide gels at pH 4.3 and 10.6 for proteins from different anatomic sites were compared, and regional variation in chemical composition was found. This may account for preferential involvement of specific anatomic sites in certain neurologic diseases.