Biomedical subjects

F Alliot

Publications and source records attributed to F Alliot.

At least 19 recordsLinked to original sources

PubMed2002

The myelin basic protein gene is expressed in differentiated blood cell lineages and in hemopoietic progenitors.

Myelin basic proteins (MBP) are major constituents of the myelin sheath of oligodendrocytes and Schwann cells in the central nervous system and the peripheral nervous system, respectively. We previously showed that MBP-related transcripts are present in the bone marrow and the immune system. These mRNAs are transcribed from a region called 0', consisting of three exons, located upstream of the classical MBP exons; these three exons belong to the long MBP gene otherwise called "Golli-MBP." The most abundant of these mRNAs, now called HMBP (hemopoietic MBP), encompasses the sequence encoded by the region 0' plus exon 1 and part of intron 1 of the classic MBP gene. Antisera to recombinant HMBP proteins are immunoreactive with proteins of about 26-28 kDa in brain, thymus, and spleen. This report demonstrates that HMBP proteins are present in the vast majority (>95%) of thymic T cells, which express the corresponding transcripts, as do mature T cells from lymph nodes and spleen. HMBP mRNAs and proteins are also manifest in the majority of spleen B lymphocytes and in B cell lines. In addition to lymphoid cells, HMBP proteins are in all types of myeloid lineage cells, i.e., macrophages, dendritic cells, and granulocytes, as well as in megakaryocytes and erythroblasts. Finally, HMBP proteins are present in CD34+ bone marrow cells, and, furthermore, in highly proliferative cultures, these CD34+ cells express HMBP RNAs and proteins. Thus, MBP gene products are present both in the nervous system and in the entire hemopoietic system.

Animals↗

PubMed2001

[Microglia: origin and development].

As suggested by Del Rio Ortega a long time ago, it is now widely accepted that microglia are the resident macrophages of the central nervous system. Microglia represent about 10% of the adult brain cell population. We have previously shown that the late embryonic and adult mouse brain contain potential microglial progenitors. We report here that microglial progenitors can be detected in neural folds from embryonic day 8. They originate from the yolk sac in which macrophage progenitors are found from embryonic day 7. We also report that the bulk of microglial cells (about 95%) appear during post-natal development. A major finding is that microglia arise by an intense in situ proliferation comparable to that of neural cells. Taken together, these results show that adult mouse microglia originate from cells migrating from the yolk sac and whose progeny actively proliferates in the brain during development.

Age Factors↗

PubMed2000

Expression of gamma-glutamyl transpeptidase in mouse perivascular astrocytes and in a protoplasmic-like astroglial cell clone.

Gamma-glutamyl transpeptidase (GGT) is known to be present in the central nervous system (CNS) but its cellular localization is still subject to controversy. In this report, we have investigated, with a specific antiserum, the immunolabelling pattern of GGT in the adult mouse CNS at the light and electron microscopic (EM) levels. At the optical level, GGT immunoreactivity ensheathes the majority of vessels in the grey matter. Immunoelectron microscopy shows that labelling is essentially due to the presence of GGT in the astrocytic endfeet which surround vessels. In addition, some pericytes and periendothelial cells are also clearly labelled. We then investigated GGT activity in astroglial cell clones which may represent the in vitro counterpart of the main astroglial cell types. The striking result is that a protoplasmic-like astroglial cell clone shows a noticeable GGT activity, while, in contrast, no activity was detected in the fibrous and the Golgi-Bergmann-like astroglial clones. Taken together, these data indicate that, in the mouse CNS, GGT is essentially present in protoplasmic astrocytes.

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PubMed1999

Microglia derive from progenitors, originating from the yolk sac, and which proliferate in the brain.

Microglia, the resident CNS macrophages, represent about 10% of the adult brain cell population. Although described a long time ago, their origin and developmental lineage is still debated. While del Rio-Hortega suggested that microglia originate from meningeal macrophages penetrating the brain during embryonic development, many authors claim that brain parenchymal microglia derive from circulating blood monocytes originating from bone marrow. We have previously reported that the late embryonic and adult mouse brain parenchyma contains potential microglial progenitors [F. Alliot, E. Lecain, B. Grima, B. Pessac, Microglial progenitors with a high proliferative capacity in the embryonic and the adult mouse brain, Proc. Natl. Acad. Sci. U.S.A. 88 (1991) 1541-1545]. We now report that they can be detected in the brain rudiment from embryonic day 8, after their appearance in the yolk sac and that their number increases until late gestation. We also show that microglia appear during embryonic development and that their number increases steadily during the first two postnatal weeks, when about 95% of microglia are born. Finally, the main finding of this study is that microglia is the result of in situ proliferation, as shown by the high proportion of parenchymal microglial cells that express PCNA, a marker of cell multiplication, in embryonic and postnatal brain. Taken together, our data support the hypothesis that terminally differentiated brain parenchymal microglia are derived from cells originating from the yolk sac whose progeny actively proliferates in situ during development.

Animals↗

PubMed1999

Pericytes and periendothelial cells of brain parenchyma vessels co-express aminopeptidase N, aminopeptidase A, and nestin.

Within the parenchyma of the CNS, the endothelium of all vessels is surrounded by a layer of cells, pericytes in capillaries and periendothelial or intima smooth muscle cells in other vessels. The origin of these cell types, their relationship, and their role are unclear. However, it has been recently shown that genetically engineered mice that lack pericytes develop microaneurysms at late gestation and die before birth (Lindahl et al. [1997] Science 277:242-245). The goal of this study was to identify in situ molecular markers that would be common to pericytes and periendothelial cells of adult mouse brain. Immunocytochemistry experiments were carried out at the optical and electron-microscopic levels on mouse brain sections with antibodies specific for aminopeptidase N, aminopeptidase A, and the intermediate filament nestin. The results of our experiments show that in all brain parenchyma vessels of all sizes, pericytes and periendothelial cells are immunoreactive for aminopeptidase N, essentially at the plasma membrane level, and are also labeled by nestin specific antibodies, which decorate typical intermediate filaments. In addition, brain pericytes and periendothelial cells are also immunoreactive to monoclonal antibodies to aminopeptidase A. In contrast, pericytes and periendothelial cells do not express microglial markers. Taken together these data show that pericytes and periendothelial intima smooth muscle cells share common markers, suggesting a common origin or function, and are distinct from microglia.

Aminopeptidases↗

PubMed1999

Brain parenchyma vessels and the angiotensin system.

It is now recognized that the brain contains an autonomous angiotensin (AG) system, including the aminopeptidases A and N required for angiotensin metabolism. Using immunohistochemical techniques, we show that capillary pericytes and periendothelial cells of other vessels express aminopeptidase A (APA) and aminopeptidase N (APN) at their plasma membrane in adult mouse brain parenchyma. We therefore investigated the localization of angiotensin II(III), known as putative substrates for these enzymes, as well as that of their precursor angiotensin I. We report here the presence of immunoreactivity to angiotensin I and II(III) around most brain vessels. Angiotensins are present at the plasma membrane of brain parenchymal cells, presumably perivascular astrocytes which are also immunoreactive to AT1-receptor antibodies. The very close relationship between AGII(III) and their metabolizing enzymes APA and APN suggests a specific functional role for brain perivascular angiotensins.

Aminopeptidases↗

PubMed1999

[Results of a neurophysiologic consultation in patients with secondary lymphedema of the arm after breast cancer associated with neurological symptoms].

The aim of this study was to identify the nature of the nerve lesions found in patients with neurological complains and with lymphedema occurring after breast cancer treated by surgery and radiotherapy. Twelve patients treated in a specialised centre for lymphology had clinical and neurophysiological examinations. This study found 9 radiation-induced plexopathies, 1 neoplasic plexopathy, 2 carpal tunnel syndromes (one isolated), 1 cervical root disease and 1 normal examination. The radiation-induced plexopathy is characterised by a chronic neurogenic involvement and the presence of (motor and sensory) proximal persistent conduction blocks. This study demonstrated that it is essential to identify with electrodiagnosis the exact nature of the nerve lesion to determine the most appropriate and effective treatment.

Arm↗

PubMed1998

Ly-6C is expressed in brain vessels endothelial cells but not in microglia of the mouse.

The Ly-6C antigen is expressed in various cell types of the immune system, including macrophages. Using the monoclonal antibody ER-MP20 which specifically recognises Ly-6C, we have investigated whether brain parenchymatous microglia express Ly-6C in vivo as well as in vitro. In brain sections from developing and adult C57/BI mice, all vessels were strongly immunolabelled. Electron microscopic immunohistochemistry showed that the endothelial cells are the cell type expressing Ly-6C. In contrast, we never observed immunoreactivity on microglia; however, microglial cells proliferating in vitro were strongly ER-MP20 positive. These data show that Ly-6C is not a marker for microglia in vivo.

Animals↗

PubMed1998

[Computerized tomography of 150 cases of lymphedema of the leg].

The aim of this work was to evaluate the usefulness of CT imaging to stage lower limb lymphedemas. Between 1992 and 1997, we studied 150 cases of lymphedema, half idiopathic and half secondary. Methods used are described. In decreasing order of frequency, we found: skin thickening, increased subcutaneous tissue surface area compared with the healthy limb, thickening of the perimuscular aponevrosis, fat infiltration: lines parallel to the skin (parallel), edematous areas along the perimuscular aponevrosis, lines perpendicular to the skin (perpendicular). The lowest fat density was increased on the diseased side. The subfascial tissue showed some fat accumulation. These results were compared with findings reported in the literature. There were very major differences between idiopathic lymphedema and secondary lymphedema of the thigh. Similar images were generally generated by new and long-standing lymphedema. Rarely useful for positive diagnosis, CT is indispensable for establishing stage initially or after recent increase and, in our opinion, is essential for pretherapeutic assessment. The CT-scan gives objective evidence of overall disorders, the exact upper limit of the lymphedema, and sometimes reveals infraclinical bilateral involvement.

Adult↗

PubMed1998

Transaxial computer tomography of lower extremity lymphedema.

We examined retrospectively 11 patients with isolated unilateral lower limb lymphedema (clinical criteria confirmed by isotope lymphography) using computer tomography. In conjunction with earlier observations, the findings of soft tissue stranding, skin thickening, fat deposition in the epifascial compartment and perimuscular fascial thickening and edema relate to lymph stasis. This noninvasive and relatively simple imaging technique allows analysis of soft tissue changes in leg lymphedema and can be used to evaluate lymphatic insufficiency and its extent as well as document the response to treatment.

Adult↗

PubMed1996

A spontaneously immortalized mouse microglial cell line expressing CD4.

We have derived a microglial clone, named C8-B4, from the 8-day mouse cerebellum organ culture which gave rise to distinct astroglial cell lines as previously reported. Indeed, the C8-B4 clone expresses classical microglial markers (MAC1, F4/80, 2-4G2) and appears to be derived from a committed microglial precursor since it does not express differentiation antigens present during the early stage of the monocytic lineage. This microglial clone expresses two characteristics not previously reported for microglial cell lines: it synthesizes the CD4 molecule and produces and releases large amounts of glutamate.

Animals↗

PubMed1996

The Lck tyrosine kinase is expressed in brain neurons.

The lck gene product, p56lck, is a member of the src-related family of protein tyrosine kinases. It is known as lymphocyte specific and involved in thymocyte development and in the immune response mediated by the T cell receptor. We report that the lck gene is also expressed in adult mouse CNS and that brain p56lck is similar to the thymus protein. In situ hybridization and immunohistochemistry show that the lck gene is expressed in neurons throughout the brain in distinct regions, including hippocampus and cerebellum. In primary cultures from fetal mouse brain, neuronal cells are immunoreactive to Lck antiserum. This suggests that the lck gene product might be involved in a new signal transduction pathway in mouse brain.

Animals↗

PubMed1996

Treatment of secondary lymphedema of the upper limb with CYCLO 3 FORT.

Fifty seven patients with secondary lymphedema of the upper limb after previous treatment for breast cancer were treated for 3 months with an extract of Ruscus + Hesperidin Methyl Chalcone (CYCLO 3 FORT) or placebo according to a double-blind protocol in the context of a controlled clinical trial. All patients also underwent manual lymphatic drainage twice a week for at least one month. With CYCLO 3 FORT, the reduction in volume of arm edema, the main assessment criteria, was 12.9% after 3 months of treatment as compared with a placebo (p=0.009). Decreased edema tended to be more marked in the forearm compared with the upper arm where excess fat deposition seemed to dominate over excess fluid accumulation. CYCLO 3 FORT was well tolerated with minimal adverse reaction.

Adult↗

PubMed1994

CD4 expression in neurons of the central nervous system.

CD4 is a member of the Ig gene super family expressed on the surface of many thymocytes and of a subset of T lymphocytes. Human CD4 is the receptor for HIV envelope glycoprotein gp120. Human and mouse CD4 transcripts are expressed in human and mouse central nervous system (CNS), but no corresponding proteins have been reported yet. We have analyzed mRNA expression and carried out immunological experiments on adult mouse brain with probes specific for the long and short CD4 transcripts and with antibodies monospecific for mouse CD4. The main result of these experiments is that the full length CD4 transcript and the CD4 protein are expressed coordinately in neurons throughout the adult mouse brain. CD4 immunoreactivity is also present in brain small vessel walls, ependymal cells, and choroid plexus. The brain mouse CD4 protein is indistinguishable from the thymus protein. In addition, we show that neuronal cells in primary cultures from human fetal CNS are immunoreactive to human CD4 mAbs.

Animals↗

PubMed1991

Microglial progenitors with a high proliferative potential in the embryonic and adult mouse brain.

Single cell suspensions, prepared from brain stem, cerebellum, and forebrain parenchyma of embryonic and adult mice, were plated on monolayers of an astroglial cell line derived from a spontaneously immortalized mouse cerebellar culture, the D19 clone. A few of the brain cells adhering to the D19 monolayers were immunoreactive to the Mac-1 antibody, which labels all cells of the monocytic and granulocytic lineages. The Mac-1-positive cells proliferated vigorously and later most of them acquired the F4/80 epitope specific for macrophages and microglia cells. Studies in clonal conditions allowed development of large colonies of about 2 x 10(5) cells that expressed typical microglia markers. Bone marrow Mac-1-positive cells cocultured on D19 monolayers were also induced to proliferate, whereas peritoneal macrophages were not. D19 astrocytes express macrophage colony-stimulating factor (CSF-1) activity at a high level, and their conditioned media induced the proliferation of brain and bone marrow Mac-1-positive cells. A specific anti-CSF-1 antiserum completely blocked bone marrow macrophage progenitor proliferation and significantly reduced the multiplication of microglial precursors induced by the D19-conditioned medium. These data indicate that the embryonic and adult mouse brain parenchyma contains potential progenitors for microglial cells.

Animals↗

PubMed1991

Alpha isoform of smooth muscle actin is expressed in astrocytes in vitro and in vivo.

We have previously reported that astroglial cell lines derived from spontaneously immortalized mouse cerebellar cultures as well as primary astrocyte cultures express the mRNA of the alpha isoform of smooth muscle actin. In this report, we have used an antiserum specific for the alpha smooth muscle actin protein to investigate the presence and the pattern of expression of alpha smooth muscle actin protein at the cellular level with immunocytochemical methods. The results show that an anti-smooth muscle vessels alpha actin antiserum labels a typical actin network in the D19 astroglial cell clone and in flat astrocytes of primary cultures derived from various CNS regions of embryonic and postnatal mice. Furthermore, this antiserum labels distinct populations of astrocytes in the adult mouse brain, in particular in the corpus callosum and the fornix. However, in the corpus callosum, astrocytic processes are strongly labeled by anti-SMV alpha actin antibodies only in parasagittal planes. Thus, alpha smooth muscle actin represents a new marker for subsets of astrocytes.

Actins↗

PubMed1989

[Immunocytochemical localization of cytochrome P-450scc in cultured rat oligodendrocytes].

Primary cultures of glial cells from newborn rat forebrain were tested after 3 to 4 weeks. Oligodendrocytes and astrocytes were characterized by immunofluorescence with monoclonal antibodies to galactocerebroside and glial fibrillary acidic protein, respectively. The cytoplasm of oligodendrocytes was specifically and intensely immunostained with monospecific polyclonal antibodies to the cytochrome P-450scc involved in the synthesis of pregnenolone from cholesterol. This observation brings additional support to the concept of "neurosteroids".

Animals↗

PubMed1988

Role of astroglial cell clones in the survival and differentiation of cerebellar embryonic neurons.

To investigate the role of astrocytes in the survival and differentiation of cerebellar neurons during development, we have used astroglial cell clones, derived from 8-day postnatal cerebellar explants and which might be the in vitro equivalents of the 3 main types of cerebellar astrocytes, the Golgi epithelial cells and their Bergmann processes, the velate protoplasmic and the fibrous astrocytes (F. Alliot and B. Pessac, Brain Res., 306 (1984) 283-291). Nearly all single cells, dissociated from 15-day embryonic mouse cerebella and seeded at low density, adhered to layers of each of the cerebellar astroglial cell clones as well as to other glial lines or artificial substrates. However, the cerebellar embryonic neurons survived well only on monolayers of either the 'Golgi-Bergmann'-like or the 'velate protoplasmic'-like clones. On these layers, 60-80% of the neurons were still present after 5 days of co-culture, while only less than 5% survived on the other types of substrates. The differentiation pattern of the neurons surviving on the 'Golgi-Bergmann' and the 'velate protoplasmic' astroglial clones was studied with markers of postmitotic granule cells, the major neuronal population in adult cerebellum. The velate protoplasmic-like clone was the only one able to support the coordinate acquisition by most surviving neurons of the phenotypic characteristics of granule cells, i.e. a distinct morphology, a specific epitope binding the monoclonal antibody 7-8 D2 and immunoreactivity to glutamate. These data show a broad heterogeneity in the capacity of astroglial cell clones to support embryonic cerebellar neurons. In addition, they indicate that neuronal survival per se is not sufficient for the acquisition of a differentiated neuronal phenotype.

Animals↗