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D Cambier

Publications and source records attributed to D Cambier.

31 records · Page 2Linked to original sources
PubMed1995

Astrocytosis in wobbler mouse spinal cord involves a population of astrocytes which is glutamine synthetase-negative.

Mice affected by the wobbler mutation are characterized by a muscular atrophy associated with motoneuron degeneration. As soon as the first clinical signs of the disease appear, reactive astrocytes, strongly glial fibrillary acidic protein (GFAP)-positive, are observed in the spinal cord grey matter. They become prevalent at all levels with disease progression. Immunostaining of glutamine synthetase (GS) shows that these reactive astrocytes are never GS-positive. The activity and protein amounts of GS remain normal in wobbler spinal cord although astrocytosis develops. Thus, gliosis in the wobbler mouse seems to involve a subpopulation of astrocytes, which is strongly GFAP-positive but GS-negative.

Animals↗
PubMed1995

Excess extracellular and low intracellular glutamate in poorly differentiating wobbler astrocytes and astrocyte recovery in glutamine-depleted culture medium.

The wobbler mouse develops an inherited motoneuronal degeneration of unknown origin in the spinal cord. Primary cultures of adult wobbler spinal cord astrocytes display abnormal morphological characteristics with fewer processes and paucity of cell-cell contacts. We have searched for a possible involvement of glutamate and glutamine intra- and extracellular accumulations in vitro in the abnormal differentiation of mutant astrocytes. We have found significantly higher glutamate and glutamine concentrations in the culture media of mutant astrocytes over a 3-day period compared with normal control astrocytes. Moreover, intracellular glutamate concentrations decreased substantially in mutant astrocytes, but intracellular glutamine concentrations remained unchanged. Furthermore, decreasing initial glutamine concentrations in the culture medium (glutamine-depleted medium) led to the recovery of normal extra- and intracellular concentrations of glutamate and recovery of quasi-normal morphological differentiation and increased cell-cell contacts, leading to an essentially normal looking astrocyte network after 3 days of culture. Under these conditions, which lead to recovery, the only remaining abnormality was the higher glutamine extracellular concentration attained in the originally depleted glutamine media. These findings suggest that mechanisms regulating glutamate/glutamine synthesis and/or influx/efflux are defective in wobbler astrocytes, leading to metabolic imbalance and possible cytotoxic effects characterized by disturbed intercellular networks and poor differentiation.

Animals↗
PubMed1989

Spontaneous glutamate release by a "fibrous"-like cerebellar astroglial cell clone.

To investigate the role of astrocytes in the metabolism of glutamate, the neurotransmitter of the granule cells of the cerebellar cortex, we have analyzed various parameters related to the synthesis of glutamate in astroglial cell clones that may be the in vitro counterparts of the cerebellar astrocytes. The "fibrous"-like clone spontaneously released large quantities of glutamate, even in the absence of glutamine in the culture medium, but did not release alanine. In contrast, the "Golgi-Bergmann"-like cells released alanine but not glutamate, whereas the "velate-protoplasmic"-like astrocytes released little glutamate and alanine. However, the glutamate oxaloacetate transaminase and glutamate pyruvate transaminase activities of the three astroglial cell lines, measured in the direction of glutamate synthesis, were comparable. In addition, the "velate protoplasmic" and "Golgi-Bergmann" clones did not consume glutamine present at 2 mM in the culture medium. These data suggest that the different types of in vivo cerebellar astrocytes may have distinct roles regarding glutamate-glutamine metabolism.

Alanine↗
PubMed1988

Glutamate dehydrogenase activity is markedly higher in a "Golgi-Bergmann"-like glial clone than in other astroglial cell lines.

Glutamate appears to be the neurotransmitter of granule cells, the major neuronal population of the cerebellar cortex. To determine the role of astroglial cells in the synthesis of glutamate, we have measured the specific activity of glutamate dehydrogenase (GDH) in clonal cell lines that might be the in vitro equivalents of the different cerebellum astroglial cell types. In conditions where GDH operates in the direction of glutamate synthesis, the specific activity of GDH measured in the "Golgi-Bergmann"-like clone was 4-6 times higher than in the "velate protoplasmic"- or "fibrous-like" astrocytic clones. These data correlate well with the intense immunoreactivity to GDH in Golgi-Bergmann astrocytes in vivo that has been recently reported.

Animals↗
PubMed1987

Free amino acid content of astroglial cell clones derived from 8-day postnatal mouse cerebella.

We have measured the free amino acid content of three distinct astroglial cell clones derived from permanent lines obtained after "spontaneous immortalization" of 8-day postnatal mouse cerebellar cultures; these clones show characteristics similar to the Golgi Bergmann glia cells, the fibrous astrocytes, and the velate protoplasmic astrocytes, i.e., the three main types of cerebellar astrocytes. The relative concentrations of amino acids that are thought to act as neurotransmitters were compared in confluent cultures of the different astroglial clones. The most striking result was a high concentration of glycine (20% of free amino acids), even in astroglial cells cultured in a glycine-free medium, a finding suggesting that glycine is synthesized by the astroglial clones. Furthermore, no gamma-aminobutyric acid (GABA) was detected. In contrast, a "neuron-like" clone derived from the same cerebellar culture contained GABA, whereas its glycine content was much lower than that of the astroglial clones. The present results, together with our previous finding of glycine synthesis in an astrocytic clone derived from 14-day postnatal mouse cerebella transformed by simian virus 40, indicate that a high glycine content may be characteristic of many cerebellar astroglial types.

Amino Acids↗
PubMed1983

A glycine-enriched astrocytic cell clone derived from mouse cerebella transformed in vitro by simian virus-40.

Measurements were made of the amino acid content of a cellular clone (K55) derived from mouse cerebellar cultures transformed in vitro by simian virus-40 (Alliot and Pessac, 1981) and that appears to be astroglial. Both the total amount of amino acids as well as the percentage of glycine in K55 cells were higher than in the mixed cultures from which they are derived. Further, glycine accumulates in the culture medium of K55 cells, but not in the medium of the parental mixed cell culture (C14), thereby suggesting that glycine is synthesized and released by K55 cells.

Amino Acids↗
PubMed1978

On a rabbit hyperlipemia induced by a fungic galactomannane peptide.

I.v. injection into rabbits of a fungic galactomannane peptide isolated from the culture medium of Aspergillus oryzae induced the apparition, 20 h later, of an hypertriglyceridemia, with a concomittant decrease of about 70% of the post-heparin lipoprotein lipase activity. The same effect had been obtained earlier with a carbohydrate-rich fraction purified from a crude papain preparation. The 2 fractions are compared.

Animals↗
PubMedDate not supplied

Intrinsic risk factors for the development of anterior knee pain in an athletic population. A two-year prospective study.

Many variables have retrospectively been associated with the presence of anterior knee pain. Very few prospective data exist, however, to determine which of these variables will lead to the development of anterior knee pain. It was our purpose in this study to determine the intrinsic risk factors for the development of anterior knee pain in an athletic population over a 2-year period. Before the start of training, 282 male and female students enrolled in physical education classes were evaluated for anthropometric variables, motor performance, general joint laxity, lower leg alignment characteristics, muscle length and strength, static and dynamic patellofemoral characteristics, and psychological parameters. During this 2-year follow-up study, 24 of the 282 students developed patellofemoral pain. Statistical analyses revealed a significant difference between those subjects who developed patellofemoral pain and those who did not concerning quadriceps and gastrocnemius muscle flexibility, explosive strength, thumb-forearm mobility, reflex response time of the vastus medialis obliquus and vastus lateralis muscles, and the psychological parameter of seeking social support. However, only a shortened quadriceps muscle, an altered vastus medialis obliquus muscle reflex response time, a decreased explosive strength, and a hypermobile patella had a significant correlation with the incidence of patellofemoral pain. We concluded that the latter four parameters play a dominant role in the genesis of anterior knee pain and we therefore deem them to be risk factors for this syndrome.

Adolescent↗
PubMedDate not supplied

Intrinsic risk factors for the development of patellar tendinitis in an athletic population. A two-year prospective study.

Retrospective studies have suggested various factors that might cause a disposition to develop patellar tendinitis, but no prospective data exist to determine any relationships. The purpose of this study was to determine the intrinsic risk factors for the development of patellar tendinitis in an athletic population. Before the study, 138 male and female students of physical education were evaluated for anthropometric variables, leg alignment characteristics, and muscle tightness and strength parameters. During the 2-year study, 19 of the 138 students developed patellar tendinitis. In all cases the diagnosis was confirmed by the presence of a hypoechogenic nodular lesion in the proximal region of the patellar tendon. Univariate and stepwise discriminant function analyses were performed comparing the various measurements. These analyses revealed that the only significant determining factor was muscular flexibility, with the patellar tendinitis patients being less flexible in the quadriceps and hamstring muscles (P < 0.05). The results of this study demonstrate that lower flexibility of the quadriceps and hamstring muscles may contribute to the development of patellar tendinitis in an athletic population. Therefore, the prevention of this condition in athletes should be focused on screening for and treating poor quadriceps and hamstring muscle flexibility.

Adolescent↗
PubMedDate not supplied

Induction of hyperlipemia by carbohydrate-rich fractions isolated from crude papain.

A hyperlipemia was obtained in rabbits injected intravenously with two carbohydrate-rich fractions isolated from crude papain dialyzate. The fractions have an approximative molecular weight of 15,000 and 5,000 daltons and contains 35% and 15% of sugars respectively. The hyperlipemia appears 20 hours after the injection and consists in a hypertriglyceridaemia as suggested by the enrichment of serum in very light lipoproteins of density about 1.006. Concomittantly a decrease of the post-heparin lipase activity (PHLA) of the plasma was observed. After a few days the hyperlipemia disappears and the PHLA returns to a normal value. It is suggested that the hypertriglyceridaemia can be due to an inhibitory effect of the injected fractions on the removal action of the lipases which are released into the blood by an heparin injection.

Animals↗