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A C Kato

Publications and source records attributed to A C Kato.

At least 37 records · Page 2Linked to original sources
PubMed1996

Injury-induced synthesis and release of apolipoprotein E and clusterin from rat neural cells.

Apolipoproteins in the brain have assumed major clinical importance since it was shown that one of the allelic forms of apolipoprotein E, apoE-4, is a risk factor for Alzheimer's disease. Using tissue culture of embryonic rat spinal cord, we examined the effect of neuronal injury on the up-regulation of two apolipoproteins, apolipoprotein E and clusterin (apoJ). In order to study the influence of neuronal cells, we exploited the specific neurotoxic effect of elevated glutamate on these cells. Overstimulation by excess glutamate induced neuronal degeneration as assessed by morphological and biochemical criteria, notably the activity of choline acetyltransferase, which serves as a marker for cholinergic neurons. High concentrations of glutamate increased mRNA synthesis and the production and secretion of both apolipoprotein E and clusterin protein. Both neuronal cell death and release of the peptides were calcium-dependent and could be blocked by the NMDA receptor antagonist MK-801. Immunohistochemical data revealed the presence of clusterin in both neuronal and non-neuronal cells whereas apolipoprotein E was mainly expressed in non-neuronal cells. The results are suggestive of concerted up-regulation of apolipoprotein E and clusterin when neural cells are subjected to injury.

Animals↗
PubMed1995

Polymer encapsulated cell lines genetically engineered to release ciliary neurotrophic factor can slow down progressive motor neuronopathy in the mouse.

Ciliary neurotrophic factor (CNTF) has recently generated great interest due to its potential as a therapeutic agent for the treatment of human neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS). Because the systemic half-life of CNTF is only in the order of a few minutes, continuous delivery of this trophic factor could be attractive or even necessary in the therapy of these diseases. One promising technique involves the polymer encapsulation of cells which have been genetically modified to secrete neurotrophic factors. The polymer capsules can be implanted into animals and effect the slow release of the protein for several months. The encapsulation technique immuno-isolates the foreign cells from host immune cells and at the same time prevents tumour formation by the transplanted cells. In this study, we have used progressive motoneuronopathy (pmn) mice to determine the extent to which encapsulated cell lines secreting CNTF could alter the course of the disease. pmn/pmn homozygotes present severe loss of myelinated motor fibres and a significant reduction of facial motoneuron cell bodies. The mice develop weakness of the hindlimbs and die during the sixth week after birth. We found that CNTF delayed the disease progression by increasing the survival time by 40% and by improving motor function as assessed by three behavioural tests. Moreover, histological counts of the phrenic nerve myelinated axons and facial nucleus motoneurons indicated a significant reduction of motoneuron loss. These results suggest that polymer-encapsulated cells releasing neurotrophic factors may provide a potential delivery system for treating neurodegenerative diseases such as ALS.

Animals↗
PubMed1995

Quantitative comparison of the transient rescue effects of neurotrophic factors on axotomized motoneurons in vivo.

A reproducible neuronal degeneration induced by nerve lesion in neonatal rats or mice provides a convenient in vivo assay for testing the survival-promoting activity of putative growth factors on motoneurons. The goal of this study was to compare the rescue effects of the four known neurotrophins [nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and neurotrophin-4 (NT-4)] and two of the cytokines [ciliary neurotrophic factor (CNTF) and leukaemia inhibitory factor (LIF)] in one particular experimental model of spinal motoneuron degeneration at two different survival times. The sciatic nerve was cut in neonatal rats and the factors were applied onto the nerve stump; bovine serum albumin was used in controls. Simultaneous application of the retrograde tracer fluoro-gold made it possible to count motoneurons specifically in the sciatic pool. One week after lesion, the neurotrophins BDNF, NT-3 and NT-4, but not NGF, equally enhanced motoneuron survival compared to controls; their effects were significantly better than those of the cytokines. However, the rescue from cell death was only transitory because a great number of the motoneurons died during the second week after nerve lesion. Additional BDNF and/or CNTF supplied by repeated subcutaneous injections (1 mg/ml) over 2 weeks could not prevent this delayed motoneuron loss. These results suggest that still other factors or alternative routes of administration may be required for permanent rescue of the lesioned immature motoneurons.

Animals↗
PubMed1995

Treatment of amyotrophic lateral sclerosis using a gene therapy approach.

Neurotrophic factors which act on motor neurons may provide an efficient treatment for amyotrophic lateral sclerosis. In order to overcome the difficulty of administering proteins into the central nervous system, it is possible to use a gene therapy approach, i.e. the polymer encapsulation of cells which have been genetically engineered to release one of these neurotrophic factors. The polymer-encapsulated cells can be implanted subcutaneously or even intrathecally and permit continuous, slow release of proteins. There is no rejection of the cells due to their isolation by a semi-permeable membrane, no risk of tumor formation and the polymer device can be removed in the event of a problem.

Amyotrophic Lateral Sclerosis↗
PubMed1995

Bcl-2 overexpression prevents motoneuron cell body loss but not axonal degeneration in a mouse model of a neurodegenerative disease.

Bcl-2 and its analogs protect different classes of neurons from apoptosis in several experimental situations. These proteins may therefore provide a means for treatment of neurodegenerative diseases. We examined the effects of Bcl-2 overexpression in a genetic mouse model with motor neuron disease (progressive motor neuronopathy/pmn). Pmn/pmn mice lose motoneurons and myelinated axons, and die at 6 weeks of age. When these mice were crossed with transgenic mice that overexpress human Bcl-2, there was a rescue of the facial motoneurons with a concomitant restoration of their normal soma size and expression of choline acetyltransferase. However, Bcl-2 overexpression did not prevent degeneration of myelinated axons in the facial and phrenic motor nerves and it did not increase the life span of the animals. Since Bcl-2 acts strictly on neuronal cell body survival without compensating for nerve degeneration in pmn/pmn/bcl-2 mice, this proto-oncogene would not in itself be sufficient for treatment of neurodegenerative diseases where axonal impairment is a major component.

Animals↗
PubMed1994

BDNF-mediated rescue of axotomized motor neurones decreases with increasing dose.

Direct application of brain-derived neurotrophic factor (BDNF) to the cut end of axotomized immature motor neurones had only transient survival-promoting effects. Therefore, we have examined whether additional delivery of BDNF with repeated subcutaneous injections (1 mg/ml) could potentiate this short-term rescue of the lesioned sciatic and facial motor neurones in neonatal rats. Direct application of BDNF combined with intermittent (3-day intervals) injections slightly improved motor neurone survival. However, when BDNF was injected daily in addition to the direct application, the number of surviving lesioned motor neurones was markedly reduced. These findings, corroborated by results in embryonic spinal cord cultures, show that a dose-dependent reversal of BDNF-mediated positive effects on motor neurones occurs in vivo.

Animals↗
PubMed1994

Overlapping and additive effects of neurotrophins and CNTF on cultured human spinal cord neurons.

Ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF) have been shown both in vitro and in vivo to support the survival and differentiation of developing chick or rat motoneurons. To explore the potential use of these and other neurotrophic factors as therapeutic agents in human motoneuron diseases, we have examined the effects of the neurotrophins NGF, BDNF, neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4/5) and the cytokines CNTF and cholinergic differentiation factor/leukemia inhibitory factor (CDF/LIF) and combinations of these factors on fetal human spinal cord neurons grown for 7-10 days in monolayer cultures. The level of choline acetyltransferase (ChAT) was determined in cultures grown in the presence of NGF, BDNF, NT-3, NT-4/5, CNTF, or CDF/LIF or with combinations of these factors. With the exception of NGF, each of these factors alone increased ChAT activity by two- to three-fold above control levels; combinations of NT-3 and CNTF were greater than either alone. As a single factor NT-4/5 produced the greatest increase in ChAT activity, but was not additive with any other neurotrophin or CNTF. A combination of the three factors CNTF, BDNF, and NT-3 or the four factors CNTF, BDNF, NT-3, and NT-4 increased ChAT levels by four-fold, an effect greater than any individual factor. The finding that combinations of these factors show some additive effects toward human spinal cord cholinergic neurons in culture has prompted the testing of such combinations in animal models of motoneuron disease.

Brain-Derived Neurotrophic Factor↗
PubMed1993

Migration of purified embryonic motoneurons grafted into adult mouse CNS.

Embryonic motoneurons were fluorescently-labelled with carbocyanine (diI) by means of retrograde transport and then grafted into the adult mouse spinal cord (L2) and brain (striatum) for 2-10 weeks. The motoneurons were grafted either following purification on the fluorescence-activated cell sorter or in the presence of embryonic glial cells and interneurons from the spinal cord. In both conditions of grafting, motoneurons were found to survive and develop in both grey and white matter and were found to migrate long distances in both regions of the central nervous system. Migration of neurons after grafting remains a controversial issue, therefore we have discussed the work of other groups that have described the same phenomenon.

Animals↗
PubMed1992

A monoclonal antibody distinguishes anterior horn cells of human embryonic spinal cord during a transient period of development.

Monoclonal antibodies were prepared by using the anterior horn region of human embryonic spinal cord as immunogen. To increase the specificity of the immune response towards the anterior horn cells, mice were first injected with antigens from the posterior horn and then immunosuppressed with cyclophosphamide; subsequently antigens from the anterior horn were injected. One of the monoclonal antibodies recognizes a small population of anterior horn cells of human embryonic spinal cord during a transient period of development (9-10th embryonic week); these cells are probably motoneurons according to their location in the spinal cord, their positive staining for acetylcholinesterase and their large nuclei. The staining pattern has a special axial distribution as it is limited to the cervical and thoracic regions of the spinal cord. The antibody is species-specific and shows a high degree of tissue specificity. Since this antibody distinguishes a small group of anterior horn cells in the spinal cord during a specific developmental stage, it opens stimulating perspectives for further investigation on the nature of the antigen and its putative role during the development of the human embryonic spinal cord.

Animals↗
PubMed1992

Cholinergic differentiation factor (CDF/LIF) promotes survival of isolated rat embryonic motoneurons in vitro.

We present evidence that the cholinergic differentiation factor (CDF), originally purified from cardiac and skeletal muscle cell-conditioned medium and found to be identical to leukemia inhibitory factor (LIF), promotes survival of embryonic day 14 rat motoneurons in vitro. These neurons were retrogradely labeled with the fluorescent tracer Dil and enriched on a density gradient or purified to homogeneity by fluorescence-activated cell sorting. Subnanomolar concentrations of CDF/LIF supported the survival of 85% of the motoneurons that would have died between days 1 and 4 of culture. The enhanced survival was accompanied by a 4-fold increase in choline acetyltransferase (ChAT) activity per culture. CDF/LIF also increased ChAT activity in dorsal spinal cord cultures, but had no detectable effect on ChAT levels in septal or striatal neuronal cultures. For comparison, other neurotrophic molecules were tested on motoneuron cultures. Ciliary neurotrophic factor had effects on motoneuron survival similar to those of CDF/LIF, whereas basic fibroblast growth factor was somewhat less effective. Nerve growth factor had no effect on the survival of rat motoneurons.

Animals↗
PubMed1991

Differential modulation of the cholinergic activity of rat CNS neurons in culture.

Treatment of septal cultures prepared from 17-day-old embryos with two different antimitotic agents, cytosine arabinoside (ara C) and 5'-fluoro-2'-deoxyuridine (FUdR), caused a 2-fold increase in the level of choline acetyltransferase (CAT) activity and no change in the glutamic acid decarboxylase (GAD) activity. In these cultures, there was also a large decrease in the number of astrocytes as determined by immunofluorescence for glial fibrillary acidic protein (GFAP). Furthermore, when epidermal growth factor (EGF) was added to the septal cultures to increase the astrocyte population, the CAT activity decreased. Therefore, it would appear that the astrocytes are responsible for producing this down-regulation on cholinergic neurons. In order to determine whether all CNS cholinergic neurons can be inhibited in this manner, cultures were prepared from two other CNS regions that contain a high percentage of cholinergic neurons, i.e. the striatum and the ventral spinal cord. When these cultures were treated with the antimitotic agents, there was little modification of the CAT or GAD activities. These results suggest that the astrocytic microenvironment of the septal neurons exerts an inhibitory effect on the CAT activity either via a soluble factor or via cell-cell contact. Such studies are an important demonstration that non-neuronal cells may alter cholinergic properties during CNS development.

Animals↗
PubMed1990

Embryonic motoneurons grafted into the adult CNS can differentiate and migrate.

Embryonic mouse motoneurons were labelled by retrograde transport with a fluorescent dye (diI), partially purified on a density gradient and grafted into adult mouse CNS for a maximum of 10 weeks. In both the spinal cord and striatum, a small number of fluorescently labelled motoneurons were found to survive as judged by their round, bright appearance and also to differentiate as assessed by their ability to extend neurites. The motoneurons travelled long distances in the spinal cord (2 mm) and in the brain (4 mm) in both white and grey matter.

Animals↗
PubMed1990

Grafting of embryonic motoneurons into spinal cord and striatum of adult mice.

The aim of the present work was to determine whether embryonic motoneurons could survive in the adult CNS and whether they display different survival and growth characteristics in their natural site (the spinal cord) as compared to an ectopic site (the striatal region of the brain). Specific labelling of embryonic motoneurons was obtained by retrograde transport of a fluorescent tracer (carbocyanine) followed by partial purification of the dissociated motoneurons on a density gradient. This technique offers the advantage that only the motoneurons in the cell suspension used for the grafts contain the fluorescent tracer. This study demonstrates that these motoneurons can survive and differentiate in the white and grey matters, not only in the adult spinal cord, but also in the brain. Furthermore, these motoneurons can migrate approximately 2 mm in the spinal cord and 4 mm in the brain.

Animals↗
PubMed1989

Interferon induces astrocyte maturation causing an increase in cholinergic properties of cultured human spinal cord cells.

It has been well established that interferon-gamma (IFN-gamma) can modify the immune status of cells in the central nervous system (CNS) by inducing major histocompatibility antigens. Furthermore, it has been shown that endogenous IFN can be produced in the brain following viral infection and a form of IFN-alpha/beta can be produced by astrocytes in culture. Here we show that IFN can induce astrocyte maturation and alter neurotransmitter properties in cultured CNS neurons at a given developmental stage. IFN causes a dose-dependent increase in choline acetyltransferase activity and glial fibrillary acidic protein (GFAP) immunoreactivity in cultures of human embryonic spinal cord neurons. The GABAergic activity and the Thy1 immunoreactivity remain unchanged. IFN-gamma does not act directly on the neurons but via the nonneuronal cells, probably the astrocytes, which in turn stimulate the cholinergic traits. These studies could be important for demonstrating an action of the immune system on glial cell maturation and on the neurotransmitter phenotype expression in CNS neurons.

Astrocytes↗
PubMed1989

Characterization of dissociated monolayer cultures of human spinal cord.

Embryonic human spinal cord cells have been grown in dissociated monolayer cultures for 1 to 7 weeks. Using cell type specific markers, it was possible to show that the cultures contain neurons, astrocytes and fibroblasts. Electrical membrane properties were studied with patch electrodes using the whole cell recording technique. Neurons had short duration action potentials that could be blocked by tetrodotoxin. The membrane currents in these neurons were studied in voltage clamp experiments. Three types of voltage-dependent currents were observed: a sodium current; a potassium current made up of two components, IA and IK; and a calcium current. Both cholinergic and GABAergic neurons are present in the cultures. There is more choline acetyltransferase activity in cultures prepared from the anterior as compared to the posterior part of the spinal cord, suggesting that the cultures contain motoneurons. This tissue culture preparation was developed for the study of amyotrophic lateral sclerosis; we have been unable to detect the presence of any toxic agent from the serum of these patients on the cultured cells. Experiments are in progress to purify the motoneurons using Percoll gradients.

Acetylcholine↗
PubMed1988

[Interferon stimulates the expression of cholinergic properties in human spinal cord neurons in culture].

A preparation of dissociated monolayer cultures from embryonic human spinal cord has been developed and characterized (Kato, Touzeau, Bertrand, Bader, 1985) as a model system for the study of amyotrophic lateral sclerosis (Touzeau and Kato, 1986). The cultures contain cholinergic and GABAergic neurons, astrocytes and fibroblasts. We have recently found that gamma-interferon (IFN) can increase the choline acetyltransferase (CAT) activity without altering the level of glutamic acid decarboxylase (GAD) or the neuronal survival; an antibody to IFN can prevent these effects. Gamma-IFN appears to mediate these effects via the non-neuronal cells since in the absence of non-neuronal cells, gamma-IFN has no effect on the cholinergic properties. The non-neuronal cells alone have no CAT or GAD activity. Astrocytes may be responsible for these changes since gamma-IFN increases the development of GFAP immunoreactivity in cultures of 6-7 week old spinal cord cells and it causes no visible change in the Thy-1 immunoreactivity of the fibroblasts. Thus we propose that IFN acts on non-neuronal cells, possibly the astrocytes, which in turn stimulate neuronal cholinergic traits either by means of a diffusible factor or via cell-cell contact. These studies could be relevant in understanding the effects of the immune system on the nervous system and also in the search for new drugs which act specifically on cholinergic neurons.

Amyotrophic Lateral Sclerosis↗