Biomedical subjects

F Garnier

Publications and source records attributed to F Garnier.

At least 37 records · Page 2Linked to original sources

PubMed1999

Galectin-1 expression in prostate tumor-associated capillary endothelial cells is increased by prostate carcinoma cells and modulates heterotypic cell-cell adhesion.

Besides providing tumors with nutrients, newly formed capillaries constitute a potential escape route for tumor cells favoring metastatic dissemination, and constitute an access for the anti-tumoral host immune cells. Galectin-1, a soluble human lectin, is involved in numerous biological functions including cell-cell and cell-substrate interactions. In addition, galectin-1 is able to induce apoptosis of activated T-lymphocytes. In this study, we have examined galectin-1 expression in capillaries associated to the carcinoma cells or present in the remote non-tumoral stroma of 100 human prostate carcinoma samples by immunoperoxidase staining. Galectin-1 was expressed by endothelial cells from capillaries infiltrating the tumor tissue in 64% (64/100) of the cases. On the contrary, endothelial cells in the adjacent non-tumoral stroma expressed galectin-1 in very few cases (7/100). Increased frequency of galectin-1-positive capillaries in the tumor-associated compared to the tumor-free areas was observed in 63% of the cases. This striking contrast led us to set up an in vitro model to test whether tumor cells could induce galectin-1 expression by endothelial cells. Incubation of human umbilical vein endothelial cells with conditioned media from PC-3 or DU 145 prostate carcinoma cells led to a significant increase of galectin-1 protein expression (+32.97% and 37.91% P < 0.01 and P < 0.05, respectively). PC-3 conditioned medium also induced increased adhesion values of PC-3 cells to the endothelial cells (53.4 +/- 4.7 vs. 38.5 +/- 3.5 after 30 min; 66.6 +/- 7.8 vs. 46.2 +/- 6.4 after 60 min). An anti-galectin-1 antiserum abolished this modulation, and recombinant galectin-1 also induced increased adhesion values in a dose-dependent fashion. This effect was specific as no such modulations were observed using normal lymphocytes instead of PC-3 cells. Preferential galectin-1 expression in the endothelial cells close to the cancer cells could provide these latter with increased abilities to interact with the endothelial cells as well as a defense against the host immune system.

Journal Article↗

PubMed1999

Shemin pathway and peroxidase deficiency in a fully habituated and fully heterotrophic non-organogenic sugarbeet callus: an adaptative strategy or the consequence of modified hormonal balances and sensitivities in these cancerous cells? A review and reassessment.

There are many arguments for considering a specific fully habituated (auxin and cytokinin-independent) and fully heterotrophic non-organogenic (HNO) sugarbeet callus cell line as terminating a neoplastic progression, and thus to be made of cancerous cells. The similarities with animal tumour and cancer cells are recalled. All types of habituated tissues examined in the literature share at least three common biochemical characteristics: low apparent peroxidase activity, high content of polyamines (PAs) and low production of ethylene. However, results concerning their auxin and cytokinin levels are not consistent. Peroxidase synthesis in the achlorophyllous HNO callus appears to arise from aminolevulinic acid (ALA) synthesis through the Shemin pathway, commonly used by animals and fungi. This pathway is limited by disturbed nitrogen metabolism that diverts glutamate (directly used for ALA synthesis in green higher plants) from the Kreb's cycle into PA synthesis. There is no argument to suggest that the low ethylene production is caused by a competition with PAs for their common precursor, S-adenosylmethionine. The results we report here indicate modified anabolic and catabolic pathways of auxins and cytokinins but also the possibilities of unusual compounds playing similar roles (dehydrodiconiferyl alcohol glucosides, for instance). A higher turnover of PAs is shown in the HNO callus, which could suggest a role for H2O2 and gamma-aminobutyric acid, products or intermediates in the PA catabolic pathway, as secondary messengers. The habituated cells retain some sensitivity towards exogenous auxins and cytokinins. Their increased sensitivity to PAs and ethylene suggests modified hormonal balances for the control of these actively dividing cells.

Aminolevulinic Acid↗

PubMed1998

Enantioselectivity of the enterohepatic recycling of carprofen in the dog.

The disposition of the two enantiomers of carprofen (CPF), the (R)-CPF and the (S)-CPF, was investigated after iv administration of the racemate (4 mg/kg) in dogs equipped with a chronic bile duct catheter. Studies in dogs with diverted bile flow showed that both enantiomers were extensively excreted in bile with 74% of the (R)-enantiomer and 92% of the (S)-enantiomer from the iv administered dose being recovered in the bile as the respective glucuronide conjugates. The direct administration of acidic bile containing acyl-glucuronides of CPF in the duodenum showed that both conjugated enantiomers led to high CPF enantiomer systemic availability. However, comparison of CPF pharmacokinetics between dogs with nondiverted bile flow and dogs with diverted bile flow suggested that CPF was subjected to enantioselective enterohepatic recycling (EHC) and that only the (S)-CPF was recycled. The absence of EHC for the (R)-CPF is hypothesized to be the result of formation of glucuronidase-resistant isoglucuronides (epimers) to a greater extent for the (R)-CPF than for the (S)-CPF.

Animals↗

PubMed1997

Cystic fibrosis phenotype associated with pancreatic insufficiency does not always reflect the cAMP-dependent chloride conductive pathway defect. Analysis of C225R-CFTR and R1066C-CFTR.

We have previously screened the cystic fibrosis transmembrane conductance regulator (CFTR) gene and identified new disease-causing mutations. C225R and R1066C are both associated with pancreatic insufficiency, but the former mutation is associated with mild and unusual lung disease, whereas the latter is associated with severe lung disease. In the present study, we expressed these mutants heterologously in HeLa cells, and we analyzed protein synthesis by immunoprecipitation and chloride channel function by using a halide-sensitive fluorescent dye, 6-methoxy-N-ethylquinolinium. Immunoprecipitation and functional studies showed that cells transfected with C225R-CFTR exhibit cAMP-dependent chloride fluxes; C225R-CFTR protein is poorly expressed but fully glycosylated and can be compared with R117H-CFTR. R1066C-CFTR protein is not correctly processed and, unlike DeltaF508-CFTR, this defect cannot be corrected by reduced temperature or overexpression in butyrate-treated cells; defective processing may occur at a different step in the biosynthetic pathway. These results point to two different mechanisms underlying the same pancreatic status and suggest that it is unwise to use pancreatic sufficiency and insufficiency to define mild and severe cystic fibrosis (CF) disease, respectively. Finally, the experimental model described here may be helpful to predict the pulmonary status of CF patients bearing mutations located in putative membrane-spanning domains of the CFTR protein.

Amino Acid Substitution↗

PubMed1997

Identification of clinically relevant viridans group streptococci to the species level by PCR.

A PCR assay that allows identification of clinically relevant viridans group streptococci (Streptococcus gordonii, S. mitis, S. mutans, S. oralis, S. salivarius, and S. sanguis) to the species level and identification of milleri group streptococci (S. anginosus, S. constellatus, and S. intermedius) to the group level was developed. This assay was based on specific amplification of internal fragments of genes encoding D-alanine:D-alanine ligases which are species specific and ubiquitous in prokaryotes possessing peptidoglycan. The specificity of this assay was tested on 9 reference strains and 91 characterized clinical isolates. This assay offers a specific and rapid alternative to phenotypic or DNA-DNA hybridization methods for identification of clinically relevant viridans group streptococci.

Alanine↗

PubMed1996

Differential transcription of phycobiliprotein components in Rhodella violacea. Light and nitrogen effects on the 33-kilodalton phycoerythrin rod linker polypeptide, phycocyanin, and phycoerythrin transcripts.

In Rhodella violacea phycoerythrin (PE) has two transcripts, a premessenger and a mature messenger (the gene contains an intron). Phycocyanin, which is plastid-encoded, and the 33-kD PE rod linker polypeptide, which is nuclear-encoded, have only one transcript. The PE premessenger had a rapid turnover; mature transcripts were stable in the light and more stable in the dark. In the presence of rifampicin, cells that shifted from dark to light exhibited an active translation of preexisting transcripts. There are indications of a modulation of the nuclear genome expression by the chloroplast; it may involve an unstable, plastid-encoded translational activator. All transcripts disappeared rapidly during nitrogen starvation. If nitrogen addition was carried out in the dark, active transcription and translation resumed as in light conditions, but ceased after 2 d. Both nitrogen and light were required for a total recovery after nitrogen starvation. Compared with the transcripts of phycobilisome components studied so far in cyanobacteria and Rhodophyceae, the mature transcripts of R. violacea are very stable when nitrogen is not limiting. The unstable PE premessenger is a good indicator of active transcription. This organism is therefore an interesting model to study the regulation of gene expression and the interactions between chloroplastic and nuclear genomes.

Amino Acid Sequence↗

PubMed1996

[Enantioselectivity in the excretion of glucuronides of carprofen in man, dogs and horses].

After administration of the racemic drug, the stereoselective quantification of the enantiomers of free and conjugated carprofen was performed in human plasma and in plasma, urine and bile of dogs and horses. In humans, the plasma profile of free carprofen and its glucuronides is not stereoselective and the glucuronides excreted in urine are close to a racemate. In dogs and horses on the contrary, the R(-) enantiomer of the free drug is predominant in plasma, while urine and/or bile concentrations of the glucuronides are high in comparison to plasma with a strong selectivity for the S(+) enantiomer. Because glucuronidation of carprofen, as a carboxylic compound, is known to be the major metabolic pathway in most species, interspecies discrepancies in the stereoselective disposition of carprofen seem to be mainly related to the stereoselectivity in the excretion of the glucuronides. Finally, the high plasma concentrations of carprofen glucuronides in human in comparison to other animal species suggest that the former could be specifically subjected to immunological side effects in the time course of treatments by this type of compounds.

Animals↗

PubMed1995

Growth hormone responses to growth hormone-releasing hormone and clonidine in dogs with Cushing's syndrome.

The effects of clonidine, a growth hormone (GH) secretagogue, acting at the hypothalamic level and synthetic GH-releasing hormone (GHRH), a physiological stimulus of somatotrophs, on GH secretion were measured in 11 dogs with Cushing's syndrome. Eight healthy dogs served as controls. After the administration of GHRH the dogs with hyperadrenocorticism had a mean (SEM) GH peak of 11.2 (2.5) ng ml-1 which was significantly lower than the peak of 48.6 (13.4) ng ml-1 observed in the healthy dogs. Similarly, the GH response to clonidine was inhibited in the dogs with hyperadrenocorticism, the mean GH peak being 9.3 (3.3) ng ml-1 compared with 135.6 (43.3) ng ml-1 in the control dogs. No significant difference between the GH responses to GHRH and clonidine was observed in the dogs with Cushing's syndrome, the areas under the response curves being 567.9 (78.2) and 478.0 (102.6) ng.min ml-1, respectively. These results demonstrate that the function of somatotrophs is abnormal in dogs with Cushing's syndrome. There is evidence that the likely action of clonidine in dogs is to inhibit the release of somatostatin and the results therefore suggest that the effect of an excess of glucocorticoid in the dog is probably not mediated through an increase in somatostatin tone.

Animals↗

PubMed1993

N-acetylcysteine and captopril protect DNA and cells against radiolysis by fast neutrons.

N-Acetylcysteine and captopril, respectively mucolytic and antihypertensive drugs, contain free sulfhydryl groups. Since in general thiols have well-established radioprotective abilities, we sought putative radioprotective effects of these drugs against therapeutic fast neutrons. We show that pBR322 plasmid DNA is indeed protected against radiolytic strand breakage by both drugs. The oxygen independent protection is consistent with a hydroxyl radical scavenging mechanism. A clonogenicity assay reveals an increase of the survival of SCL-1 cultured keratinocytes irradiated in the presence of the drugs compared with cells irradiated without drugs. Our results suggest possible interferences between treatment with drugs bearing-SH groups and radiotherapy.

Acetylcysteine↗

PubMed1992

Metal ions protect DNA against strand breakage induced by fast neutrons.

Single and double strand breaks (SSB and DSB) are induced by fast neutrons in plasmid (pBR322) DNA in 1 mM potassium phosphate buffer (pH 7.25). Increasing the concentration of monovalent (Na+, Cs+, Li+), divalent (Mg2+, Ca2+) and trivalent (Al3+, Co3+ (NH3)6) metal cations strongly decreases the yield of DSB. The extent of the observed protection depends on the valence of the cation. The production of SSB is only slightly decreased, except for Al3+ and Co3+ (NH3)6, whose effects are particularly large (complete protection at 1 and 0.1 mM respectively). Circular dichroism spectra show that Al3+ induces an important structural change of DNA at the ion concentration where the protection becomes total. This change is probably a condensation (collapse), as in the well-known case of Co3+ (NH3)6. Our results suggest two mechanisms of protection by metal ions: (i) the induction of structural changes of DNA, that render less accessible the critical sites of attack by OH. radicals; and (ii) the stabilization of the double helical regions between two close-set nicks on opposite strands, that hinders the effective double strand breakage of DNA.

Cations↗

PubMed1991

Chiral behaviour of the metabolite albendazole sulphoxide in sheep, goats and cattle.

Three sheep, three goats and three cattle were dosed orally with 5.0, 7.5 and 10 mg albendazole kg-1 bodyweight, respectively. Blood samples were taken at intervals for 48 hours after administration. The enantiomeric ratio of the metabolite albendazole sulphoxide (SO.ABZ) was determined by liquid chromatography on chiral stationary phases. At To, the plasma concentration ratio (+)SO.ABZ/(-)SO.ABZ was estimated at 3.0 in sheep, 1.5 in goats and 4.0 in cattle. The proportion of the (+) enantiomer then increased linearly as a function of time during the course of the kinetics. In comparison to the area under the curve for total SO.ABZ, the (+) enantiomer represented 86 per cent in sheep, 80 per cent in goats and 91 per cent in cattle. The specific behaviour of the two enantiomers is probably the result of the enantioselectivity of the flavine adenosine dinucleotide and cytochrome P450 dependent enzymatic systems which are involved in the sulphoxidation and the sulphonation of ABZ.

Administration, Oral↗

PubMed1991

Enhancement of in vivo and in vitro T cell response against measles virus haemagglutinin after its incorporation into liposomes: effect of the phospholipid composition.

Artificial phospholipid bilayer vesicles were tested for their capacity to enhance the priming and the restimulation of mouse T cells against the haemagglutinin (H) glycoprotein of the measles virus in vivo and in vitro. H glycoprotein was purified and incorporated into liposomes made of cholesterol, dicetylphosphate and dilauroylphosphatidylcholine (DLPC) or distearoylphosphatidylcholine (DSPC). H in DLPC or DSPC-liposomes was found to be a potent in vivo stimulator of lymph node T cells harvested from mice immunized with measles virus, whereas H glycoprotein in free form did not elicit any proliferative T cell response. When used to immunize naive mice, only H in DSPC-liposomes was able to prime T cells as evidenced by the capacity of lymph node cells to proliferate in the presence of H in liposomes or measles virus as secondary stimulating agents in vitro. H-specific T cell clones derived from animals immunized with H in DSPC-liposomes were able to recognize H glycoprotein both in free form and incorporated into liposomes in the presence of naive spleen cells as APC. However, compared with the liposome forms, 20-fold more H protein in free form was required to elicit a T cell clone response at a similar level. This liposome immune enhancing effect on the T cell clone recognition of H glycoprotein was also observed when peritoneal exudate cells were used as APC. These data demonstrate that the insertion of a membrane-derived antigen into artificial membranes may be a prerequisite for the priming and stimulation of specific T cells both in vivo and in vitro. In addition, the nature of the phospholipid used to build the liposomes appears to be a critical parameter.

Animals↗

PubMed1990

Chirality of the sulphoxide metabolites of fenbendazole and albendazole in sheep.

Two prochiral sulphide drugs, fenbendazole (FBZ) and albendazole (ABZ) were administered orally to sheep. Blood samples were analysed for parent drug and S-oxidation metabolites and the chirality of the sulphoxide metabolites was determined. The plasma concentrations of the enantiomers of the sulphoxides were never a racemate. On the contrary, the ratios were greater than 1 as soon as the sulphoxide compounds could be detected in plasma. They subsequently increased linearly throughout the time course of the kinetics, reaching the level 86:14 after FBZ and 95:5 after ABZ treatment. The major enantiomer represented 74% and 86% of the total AUC of SO.FBZ and SO.ABZ, respectively.

Albendazole↗

PubMed1990

Adrenal cortical response in clinically normal dogs before and after adaptation to a housing environment.

58 dogs (29 males and 29 females) selected as healthy on clinical and biochemical evaluations were subjected to an ACTH adrenal function test 2 days after their admission to a veterinary hospital (t + 0). Basal female serum cortisol concentrations were significantly higher than concentrations in males (77 nmol/l versus 43 nmol/l; P less than 0.01). Concentrations post stimulation were not statistically different (P greater than 0.05) between males and females: 306 (+/- 69) nmol/l versus 291 (+/- 73) nmol/l, respectively. Twelve dogs (6 males and 6 females), randomly selected from the 58, were subjected to the same test 5 weeks later (t + 5) and 12 weeks later (t + 12). Basal cortisol concentrations were lower at t + 5 or at t + 12 than at t + 0. Post stimulation mean cortisol concentrations were lower in males than in females at t + 5 (162 versus 232 nmol/l; P less than 0.05) but not at t + 0 (262 versus 320 nmol/l; P greater than 0.05) and t + 12 (188 versus 233 nmol/l; P greater than 0.05). These findings are indicating an increased susceptibility of bitches to environmental stress.

Adaptation, Psychological↗

PubMed1988

Haemagglutinin of measles virus: purification and storage with preservation of biological and immunological properties.

Measles virus envelope haemagglutinin (H) was purified rapidly with Triton X-100-solubilized virions by a two-step anion-exchange chromatography using fast protein liquid chromatography. The purity of the glycoprotein in its dimeric form was demonstrated by SDS-PAGE followed by silver staining or autoradiography. The purified H glycoprotein was further freed from contaminating detergent by dialysis of octylglucoside detergent. This purification procedure, together with subsequent lyophilization and storage at -70 degrees C of the H glycoprotein which was incorporated into phospholipid vesicles allowed the full preservation of its haemagglutinating activity, its reactivity with a monoclonal anti-H antibody that recognized a conformational epitope and its capacity to elicit anti-H antibodies with haemagglutination-inhibiting and neutralizing activities.

Animals↗

PubMed1988

[Transplacental administration of diethylstilbestrol (DES) in the rat: effects on fertility and on hormonal receptors in the endometrium].

To determine the effects of transplacental exposure to diethylstilboestrol (DES) on the fertility and endometrial hormonal receptors of the offsprings, timed pregnant OFA rats were treated with DES (10, 20, 50 and 100 micrograms/kg/day, subcutaneous) on days 10 to 18 of gestation (long time) or days 13 to 18 of gestation (short time). Only the lowest dosed groups (10 micrograms/kg/day, short and long times, and 20 micrograms/kg/day, short time) gave birth to living offsprings. The fertility of the male and female offsprings was determined postnatally by a breeding technique and appeared to be strongly decreased among females of all groups (70 to 100% of sterility) and slowly decreased among males (12 to 26% of pathological fecundity). Progesterone receptor concentrations were significantly decreased for treated group (0.40 and 0.44 pmol/mg cytosol proteins) versus control group (0.74 pmol/mg cytosol proteins). Estradiol receptor concentrations were significantly higher for long time treated groups (0.26 pmol/mg cytosol proteins) versus control or short time treated groups (0.15 and 0.13 pmol/mg cytosol proteins).

Animals↗

PubMed1987

Pharmacokinetics of albendazole administered by an intraruminal pulse release electronic device in cattle.

Albendazole was administered to 12 young Charolais cattle, 300 kg bodyweight, using an intraruminal pulse release electronic device. The device released 2 g albendazole three times at 31 day intervals. The kinetic study of two main metabolites of albendazole in all animals at the time of each release showed that on 36 occasions the devices worked at the expected time; the mean kinetic profiles were nearly identical at first, second and third release. A good repeatability was generally also noticed for each animal individually; the bioavailability of the drug did not seem to be different from that obtained after administration of albendazole as an oral drench.

Administration, Oral↗

PubMed1986

Sustained IL-2 production by the EL4 subline during continuous phorbol diester stimulation is related to an increase of IL-2-mRNA.

The murine T lymphoma EL4 subline produces large amounts of interleukin 2 (IL-2) upon stimulation with phorbol myristate acetate (PMA). It was found to survive continuous PMA stimulation (10 ng/ml, renewed daily, at 10(6) cells/ml), and to maintain its IL-2 production for several days in a culture medium low in protein. IL-2 production varied from day to day with a peak within the first 2 days of stimulation. PMA stimulation was accompanied by morphologic changes (enlargement and adhesiveness), arrest in cell division and DNA replication, continued RNA synthesis and increased mitochondrial activity. These effects were reversible upon removal of PMA, with a decrease of IL-2 secretion to the background level and a progressive recovery of cell growth. The reverted EL4 cells were again able to produce large amounts of IL-2 upon restimulation with PMA. Growth of EL4 cells was shown not to depend on autologous production of IL-2, and their DNA synthesis could be arrested by aphidicolin without a concomitant accumulation of IL-2 in the supernatant. This indicates that the increase in the amount of free IL-2 is not simply due to reduced consumption by the EL4 cells themselves. PMA appears to act at the level of the expression of the IL-2 gene, since IL-2 mRNA was much more abundant in the IL-2-secreting PMA-treated cells than in untreated controls. Our observations show that considerable amounts of IL-2 can be obtained from a single EL4 cell inoculum and may represent an original model to study the effects of PMA on the differentiation and maturation processes of cells.

Animals↗