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Biomedical subjects

U De Boni

Publications and source records attributed to U De Boni.

50 records · Page 3Linked to original sources
PubMed1983

Pure population of viable neurons from rabbit dorsal root ganglia, using gradients of Percoll.

Nonneuronal cells complicate the study of neurons in vitro. A pure population of viable neurons can be obtained easily using gradients of Percoll. For each experiment, 20 dorsal root ganglia (DRG) are minced, then sequentially dissociated in collagenase and trypsin, which digest all the intercellular connections. The dissociated tissue is separated first on the basis of density, creating an interphase fraction enriched in neurons and satellite cells, which are then further separated on the basis of size. The neurons, obtained in the final pellet, number approximately 50,000 (2500 per DRG), routinely exhibit a viability of over 80% initially and are of a purity of over 90%. The viability of the neurons is confirmed by the occurrence of neurite outgrowth in culture. Thus, a pure and viable neuronal population is obtained by a simple and rapid method.

Animals↗
PubMed1982

Inhibition of corticosterone binding in vitro, in rabbit hippocampus, by chromatin bound aluminum.

Brains of patients with senile dementia of the Alzheimer type and with the dialysis encephalopathy syndrome, exhibit elevated aluminum levels. In Alzheimer's disease and in the experimental aluminum induced encephalopathy, intracellular aluminum is associated with nuclear chromatin. The work reported here was undertaken to test whether chromatin bound aluminum in hippocampus of the rabbit interferes with nuclear binding of corticosterone-receptor complexes. The results showed that the mean binding of corticosterone decreased from 460 +/- 71 fmol/mg DNA in controls, to 343 +/- 81 fmol/mg DNA in hippocampal nuclei from aluminum treated rabbits, representing a decrease of 25%. This reduction occurred in the absence of aluminum induced neurofibrillary degeneration and indicates a possible functional consequence of the presence of aluminum on chromatin, and importantly, in the absence of morphological changes.

Aluminum↗
PubMed1981

Changes in chromatin structure associated with Alzheimer's disease.

The enzyme micrococcal nuclease was used to examine the accessibility of chromatin extracted from brains of 13 patients with senile and presenile dementia of the Alzheimer type. Compared with chromatin extracted from brains of 8 patients without neurological signs or brain pathology and brains of 7 patients with nonAlzheimer dementia, Alzheimer chromatin was less accessible to this enzyme. Reduced accessibility was reflected by a reduced yield of mononucleosomes in comparison with dinucleosomes and larger oligomers. Both neuronal and glial chromatin were found to be similarly affected. The reduced yield of mononucleosomes from Alzheimer chromatin is not due to their increased breakdown, but is probably related to protein associated with the internucleosomal linker region that retards nuclease action. Dinucleosomes isolated from control and Alzheimer nuclease digests were examined for their protein complement. Three perchloric acid-soluble proteins situated in the histone H1 region of sodium dodecyl sulfate (SDS) gels were present in elevated levels in Alzheimer dinucleosomes. These results represent the first example of altered chromosomal proteins associated with a diseased state of the brain.

Adult↗
PubMed1980

Intranuclear aluminum content in Alzheimer's disease, dialysis encephalopathy, and experimental aluminum encephalopathy.

Nuclear and chromatin fractions were prepared from cerebral cortex of 34 human and 37 animal brains. Chromatin was separated into a heavy heterochromatin fraction and two euchromatin fractions: intermediate euchromatin and light euchromatin. Compared to age-matched controls, aluminum content expressed per gram of DNA was significantly increased in nuclear and heterochromatin fractions in pre-senile Alzheimer's disease. In contrast nuclear preparations from brains of patients who had died with dialysis encephalopathy contained less aluminum than controls, although whole tissue concentrations were elevated ten to fifteen times above the control concentrations. Direct injection of aluminum into the cerebrospinal fluid of cats resulted in a progressive encephalopathy with neurofibrillary degeneration and increased intranuclear aluminum content. It is speculated that in Alzheimer's disease the normal blood-brain and cytoplasmic barriers for this neurotoxic metal are defective permitting aluminum to gain access to DNA-containing constitutents of the nuclei.

Adolescent↗
PubMed1976

Neuron culture from adult goldfish.

Neurons and glia from the central nervous system of the adult teleost Carassius auratus have been grown as explant cultures of minced brain tissue and as trypsin dissociated cells. These cultures exhibit extensive neurite growth from two neuronal types, have organotypic ultrastructure, and contain electrically active cells. Autoradiographic data indicate that these neurons do not divide in culture, and histological evidence suggests that some mature neurons survive explantation and regenerate processes. However, explantation of brain fragments not containing undifferentiated cells, localized in the ventricular and subventricular zones in the brains of fish, resulted in mesenchymal and glial cell cultures only. Therefore, a contribution to the population of cells in culture by undifferentiated cells must be considered. The cultured neurons remained viable for at least 19 weeks and ultrastructural and electrophysiological data indicate synaptic interaction between cells in explant cultures.

Action Potentials↗
PubMedDate not supplied

Effect of aluminum upon conditioned avoidance response acquisition in the absence of neurofibrillary degeneration.

Aluminum induces neurofibrillary degeneration in cats but not rats. Cats develop a progressive encephalopathy in which an early manifestation is impaired learning-memory performance. At brain aluminum concentrations of 5 to 6 times that found in cat, rats demonstrate an initial transient weight loss and acquisition deficit immediately following intracranial injection. However, rats do not develop a progressive encephalopathy or a chronic learning deficit.

Aluminum↗
PubMedDate not supplied

Cultured cells of the nervous system, including human neurones, in the study of the neuro-degenerative disorder, Alzheimer's disease: an overview.

Human nervous-system cells in culture are a suitable model for the study of the degenerative changes associated with Alzheimer's disease. Alzheimer-diseased brain contains a factor which induces the formation of paired helical filaments (PHF) in cultured cells, similar to that seen in Alzheimer's disease. The excitotoxic amino acids, glutamate and aspartate, induce similar PHE formation in cultured cells. The neurotoxic element aluminium is present in high concentrations in the brain in several human neurological disorders, including Alzheimer's disease. In cultured-cell systems, aluminium interacts with acidic nuclear proteins, decreases steroid binding, produces a form of neurofibrillary degeneration and alters nucleoside metabolism.

Aluminum↗
PubMedDate not supplied

Chromatin motion in interphase nuclei, its modulation and its potential role in gene expression.

Nuclear Rotation (NR) refers to the rotatory motion of nuclei in cells in vitro, a motion measured as the displacement of nucleoli over time. NR occurs in cycling cells; however, its observation in neurons indicates that mechanisms related to mitosis are not a prerequisite. We have shown that NR includes motion of chromatin domains in addition to those represented by nucleoli, that movements are saltatory, with periods of stationarity and reversal of direction. The observation that NR occurs independently of concurrent motion of juxtanuclear, cytoplasmic structures, leads to the concept of a stationary outer nuclear membrane. Although traditionally perceived as rotation in a two-dimensional plane, NR represents a complex, three-dimensional motion of chromatin within the interphase nucleus, with nucleoli and DAPI-stained, fluorescent chromatin domains describing curvilinear trajectories extending throughout the nucleus. Based upon evidence that the rate of this motion changes with metabolic demands, we have postulated that NR functions in gene expression, by transposing chromatin domains to be transcribed to specific nuclear compartments. In a test of this hypothesis, Nerve Growth Factor (NGF), which alters gene expression, increased NR at a time post-NGF coincident with increased activity of RNA polymerases, while GABA, also postulated to alter transcription, increased NR with near instantaneous shifts of nucleolar positions within the nuclear space. The calcium ionophore A23187 and the chelator EGTA, agents which redistribute calcium (Ca), also increased NR, while additional Ca, in presence of EGTA, returned NR to control rates. It is difficult to link NR with the action of agents which alter transcription or ion balance. Nevertheless, in support of our hypothesis, available evidence indicates that agents which alter gene expression, alter NR and that they do so, probably through calcium dependent mechanisms.

Animals↗