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F Grégoire

Publications and source records attributed to F Grégoire.

At least 19 recordsLinked to original sources
PubMed2000

Culture of porcine stromal-vascular cells in serum-free medium: differential action of various hormonal agents on adipose conversion.

We developed a strictly controlled serum-free culture system and tested the effects of adipogenic and antiadipogenic agents on the proliferation and(or) adipose conversion of porcine stromal-vascular cells. To avoid any interference with serum components, stromal-vascular cells were isolated, plated, and grown in absence of serum. In these culture conditions, a very limited growth phase and the absence of cell confluence were observed. However, when compared with continuous culture in serum-containing medium, the serum-free conditions were significantly more adipogenic as assessed by increased lipid content and increased enzymatic activities for lipoprotein lipase, glycerol 3-phosphate dehydrogenase, and malic enzyme. In serum-free medium, physiological concentrations of insulin or IGF-I were sufficient to significantly increase the percentage of lipid-containing cells, whereas triiodothyronine (T3) and GH had no effect. Insulin, IGF-I, and, more moderately, T3 also accelerated the lipid filling in the lipid-containing cells. In the presence of insulin, stimulation by T3 or hydrocortisone alone had no effect on glycerol 3-phosphate dehydrogenase activity, whereas their concomitant addition significantly increased it. Chronic exposure to tumor necrosis factor-alpha dose-dependently stimulated cell proliferation but clearly inhibited differentiation. Epidermal growth factor, another known antiadipogenic agent, also significantly increased the proliferation of stromal-vascular cells, but, surprisingly, this was not correlated with inhibition of adipocyte differentiation. Indeed, epidermal growth factor treatment did not decrease lipid filling and significantly improved lipoprotein lipase and malic enzyme activities. Taken together, the results obtained in these strictly controlled serum-free culture conditions point out functions for insulin, IGF-I, hydrocortisone, and T3 during early and(or) later steps of porcine adipose conversion. In addition, this study reports a positive activity of epidermal growth factor on porcine adipocyte differentiation that is in clear contrast with previous works performed with rodent cells.

Adipocytes↗
PubMed1999

Regulation of porcine adipogenesis in vitro, as compared with other species.

In vitro studies, mostly performed on murine cell lines, allowed us to identify the role played by hormonal agents, second-messenger pathways, extracellular matrix proteins, and transcription factors in adipose conversion. Some information has also been reported when studies were conducted on primary cultures that originated from various species. However, because of conflicting results, probably caused, at least in part, by species specificity, developing cultures of preadipose cells from economically important species appeared necessary to better understand and control the animals' fat development. We reviewed our current knowledge concerning the regulation of cultured porcine preadipose cells by hormones, second-messenger pathways, and extracellular matrix proteins. The results clearly demonstrate that such primary cultures are essential to avoid the establishment of hazardous concepts originated from rodent and aneuploid cell lines in particular.

Adipocytes↗
PubMed1999

Various stimulators of the cyclic AMP pathway fail to promote adipose conversion of porcine preadipocytes in primary culture.

The cyclic adenosine-monophosphate (cAMP) pathway is generally recognized as one of the essential pathways for the adipose conversion of rodent preadipocytes in vitro. However, divergent effects of cAMP on adipocyte differentiation have also been reported. Since there is very little data on non-rodent preadipose cells, the aim of the present work was to analyze the effects of classic activators of the cAMP pathway on the proliferation and differentiation of porcine preadipocytes grown either in serum-free or in serum-containing medium. In both media, the addition of 10 microM forskolin from day 1 after cell plating to day 3 or 7 did not affect cell proliferation. Such stimulations also failed to enhance preadipocyte differentiation, as assessed by the measurement of lipoprotein lipase (LPL) and glycerol 3-phosphate dehydrogenase (GPDH) activities, two markers of adipose conversion. Similar results were obtained when various concentrations of forskolin (0.1 nM-100 microM) were added for 2 days either during the growth phase (days 1-3) or after confluence (days 5-7). Addition of methylisobutylxanthine (MIX) or 8-bromo-cAMP was also found inefficient to stimulate porcine preadipocytes differentiation clearly. By contrast, post-confluence treatment of the murine 3T3-L1 cell line with either forskolin or MIX markedly enhanced lipid accumulation and led to a dramatic increase in GPDH activity (up to 120 times). This indicates that similar culture conditions are adipogenic for the murine 3T3-L1 preadipocytes but not for porcine preadipose cells. In summary, this work clearly highlights the finding that porcine preadipocytes do not respond to classic activators of the cAMP pathway like rodent cells do. This calls in question again the general model proposed for the action of this pathway in adipose conversion and suggests that the mechanisms regulating adipocyte differentiation may differ among species.

1-Methyl-3-isobutylxanthine↗
PubMed1998

BMCP1, a novel mitochondrial carrier with high expression in the central nervous system of humans and rodents, and respiration uncoupling activity in recombinant yeast.

We report here the cloning and functional analysis of a novel homologue of the mitochondrial carriers predominantly expressed in the central nervous system and referred to as BMCP1 (brain mitochondrial carrier protein-1). The predicted amino acid sequence of this novel mitochondrial carrier indicates a level of identity of 39, 31, or 30%, toward the mitochondrial oxoglutarate carrier, phosphate carrier, or adenine nucleotide translocator, respectively, and a level of identity of 34, 38, or 39% with the mitochondrial uncoupling proteins UCP1, UCP2, or UCP3, respectively. Northern analysis of mouse, rat, or human tissues demonstrated that mRNA of this novel gene is mainly expressed in brain, although it is 10-30-fold less expressed in other tissues. In situ hybridization analysis of brain showed it is particularly abundant in cortex, hippocampus, thalamus, amygdala, and hypothalamus. Chromosomal mapping indicates that BMCP1 is located on chromosome X of mice and at Xq24 in man. Expression of the protein in yeast strongly impaired growth rate. Analysis of respiration of total recombinant yeast or yeast spheroplasts and in particular of the relationship between respiratory rate and membrane potential of yeast spheroplasts revealed a marked uncoupling activity of respiration, suggesting that although BMCP1 sequence is more distant from the uncoupling proteins (UCPs), this protein could be a fourth member of the UCP family.

Amino Acid Sequence↗
PubMed1998

12-O-tetradecanoylphorbol-13-acetate (TPA) stimulates the adipose conversion of piglet preadipocytes in primary culture.

The effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) were analyzed on the proliferation and differentiation of cultured porcine preadipocytes. In both chemically-defined and serum-containing media, short term treatment (2 days), either during the growth phase or from confluence, significantly enhanced cell proliferation, as assessed by tritiated thymidine incorporation and protein content assay. Addition of TPA during the growth phase in serum-free medium had no effect on lipoprotein lipase (LPL), glycerol 3-phosphate dehydrogenase (GPDH) and malic enzyme (ME) activities after 14 days of culture. By contrast, similar treatments in serum-containing medium significantly increased all these enzyme activities. Addition of TPA from confluence in both media stimulated LPL activity on day 14 as well as ME activity on day 17. These results were confirmed by morphologic studies. In conclusion, this study demonstrates that a short stimulation of the protein kinase C pathway can enhance the differentiation of porcine preadipocytes. Such a positive effect is however dependent on the time of TPA addition as well as the culture conditions, indicating a complex regulation of the protein kinase C pathway in this cell type.

Adipose Tissue↗
PubMed1992

Interferon-gamma and interleukin-1 beta inhibit adipoconversion in cultured rodent preadipocytes.

Cytokines like tumor necrosis factor (TNF), interferon-gamma (IFN-gamma), and interleukin-1 (IL-1) are known to interfere with the differentiation of cultured cell lines of adipocyte precursors. In the present study, the effect of mouse and rat IFN-gamma, as well as human IL-1 beta, was investigated on rodent preadipocytes in primary cultures, either in the presence of fetal bovine serum (FBS, 10%) or in serum-free defined medium. IFN-gamma exerted an antiproliferative action that was more pronounced when cells reached confluency than during the growth phase of the culture. Morphological observation and quantifications of undifferentiated and differentiating cells revealed that IFN-gamma caused a decrease in the proportion of cells devoid of lipid droplets which would correspond to fibroblast-like cells, whereas preadipocytes remained unaffected. IFN-gamma induced a marked retardation of adipoconversion, resulting in a partial inhibition of lipoprotein lipase (LPL) activity and a severe decrease in glycerol-3-phosphate dehydrogenase (GPDH) activity. The antiproliferative and anti-LPL effects of IFN-gamma were neutralized by adding anti-IFN-gamma antibodies, while these antibodies prevented only partially the depressing effect of IFN-gamma on GPDH activity. Contrary to IFN-gamma, IL-1 beta slightly enhanced the proliferation in preadipocyte cultures. IL-1 beta also depressed adipoconversion, inhibited markedly LPL activity, and partially reduced GPDH activity. These results show that the influence of cytokines on adipoconversion observed in preadipocyte cell lines can be found in normal preadipocytes in culture.

Adipose Tissue↗
PubMed1991

Glucocorticoids induce a drastic inhibition of proliferation and stimulate differentiation of adult rat fat cell precursors.

The effects of physiological glucocorticoids such as cortisol and corticosterone, as well as dexamethasone, on proliferation and differentiation of rat fat cell precursors kept in primary culture were analyzed. In serum-containing medium (10%), glucocorticoids markedly decreased cell proliferation, either on subconfluent or on confluent cultures. This effect was independent of the presence of insulin. In contrast, acute amplification of adipose conversion was observed mainly when glucocorticoids and insulin were added simultaneously. Morphological quantification of lipid-containing cells confirmed acceleration of the maturation process, and an early and specific reorganization of the cytoskeleton was detected at the ultrastructural level. In the presence of insulin, glucocorticoids also enhanced the main marker enzymes, lipoprotein lipase, and glycerol phosphate dehydrogenase. Glucocorticoid effects on precursor proliferation and differentiation were clearly dose-dependent, dexamethasone being 10 times more potent than cortisol and corticosterone. Similar results were obtained in serum-free medium, as well as in preadipocyte cultures derived from different fat deposits. This study demonstrates that in addition to an acute inhibition of precursor growth, glucocorticoids exert a clear stimulation of adipose conversion, which depends mainly on the presence of insulin and the glucocorticoid concentration.

Adipose Tissue↗
PubMed1991

[Organic morbidity of a hospitalized psychiatric population].

In order to determine organic morbidity in psychiatry, 140 psychiatric inpatients (aged between 20 and 49) were examined. After various investigations (physical, biological, chest film, EEG, ECG), it was concluded that 52% of the patients suffer from at least one physical disease, and 23% suffer from more than one. The most frequent diseases are digestive (hepatic), respiratory and cardiovascular. The relationship between opiate addiction and stomatological, urogenital and dermatological diseases, and between alcoholism and liver diseases seems clear. It would appear that a medical approach adapted to psychiatric patients is necessary in order better to diagnose these physical diseases, and to reduce psychiatric overmorbidity, which might lead to a decrease in psychiatric excess mortality.

Adult↗
PubMed1990

The stroma-vascular fraction of rat inguinal and epididymal adipose tissue and the adipoconversion of fat cell precursors in primary culture.

The stroma-vascular fraction (SVF) of inguinal and epididymal fat pads of 4 week-old rats was studied by electron microscopy. Among the various cell types, endothelial cells and preadipocytes were found in both SVF, while mesothelial cells were only detected in the epididymal SVF. The resulting heterogeneity of primary culture and the adipoconversion of the fat cell precursors were studied in a serum-supplemented medium enriched with insulin (14.5 nM) and exogenous triglycerides. Despite the heterogeneity of the inoculum, the primary cultures were rather homogeneous, fat cell precursors being the main cell type. Distinctive contaminant fibroblast-like cells were observed in both cultures, whereas epithelial-like cells, which correspond most probably to mesothelial cells, were only found in epididymal cultures. Differentiation of fat cell precursors was assessed by the appearance of lipoprotein lipase (LPL) and glycerol-3-phosphate dehydrogenase (GPDH). LPL activity was found in the same level in cells of both deposits while GPDH activity was elevated in inguinal vs epididymal derived stroma-vascular cells. The different adipose conversion pattern of both cultures was confirmed by morphological quantification: the maturation of epididymal fat cell precursors was faster but less extensive. These differences could be related mainly to regional localization rather than to different maturation of the two fat deposits.

Adipose Tissue↗
PubMed1975

Glomerular metabolic changes in compensatory renal hypertrophy.

In compensatory hypertrophy, 7 days after unilateral nephrectomy, an increase in respiration and glucose-6-P dehydrogenase activity are observed in the glomeruli of the hypertrophied kidney. It is suggested that is is related to the clearing of an increased amount of filtration residues by the glomerular cells.

Animals↗