Biomedical subjects

F Roux

Publications and source records attributed to F Roux.

At least 37 records · Page 2Linked to original sources

PubMed1999

Effect of digital rectal examination on serum complexed and free prostate-specific antigen and percentage of free prostate-specific antigen.

OBJECTIVES: To evaluate the effects of digital rectal examination (DRE) on serum total, calculated complexed, and free prostate-specific antigen (PSA) and the free/total PSA ratio and factors affecting variations of PSA. METHODS: Serum total and free PSA and the percent free PSA ratio were determined in 91 urologically referred men (mean age 64 +/- 9 years) before and 30 minutes after DRE, with the Hybritech Tandem-R assay. Complexed PSA was calculated as the difference between total and free PSA. DRE effects on PSA were analyzed comparing pre-DRE and post-DRE values and by calculating the difference between pre-DRE and post-DRE PSA and the post/pre-DRE geometric ratio as a coefficient of variation. RESULTS: Thirty minutes after DRE, the increase in total, calculated complexed, and free PSA and the percent free PSA ratio was statistically significant. The difference between post-DRE and pre-DRE values of serum total, calculated complexed, and free PSA and percent free PSA was +0.9, +0.3, and +0.6 ng/mL and + 10%, respectively. The post/pre-DRE ratio of serum total, calculated complexed, and free PSA and percent free PSA was x1.5, x1.22, and x2.5 and x1.7, respectively. Patient age, DRE findings, prostate volume, prostate histologic features, and the initial value of total PSA had no statistically significant effect on the change of percent free PSA after DRE. The initial percent free PSA had a statistically significant effect on the change of percent free PSA after DRE. The values of calculated complexed PSA before and after DRE were significantly higher in patients with a prostate volume greater than 40 cc, prostate cancer on biopsy, and an initial free/total PSA ratio greater than 18%. CONCLUSIONS: In this study, DRE significantly increased total, calculated complexed, and free PSA and percent free PSA. The increase of PSA immediately after DRE was mainly due to the increase of free PSA. The change of percent free PSA after DRE depended on the initial percentage of free PSA. Complexed PSA seems less sensitive to DRE, and its changes after DRE were clinically modest. Free PSA measurement should be done before DRE and percent free PSA should be used only when the venipuncture is done before the DRE.

Aged↗

PubMed1999

Dexamethasone regulation of P-glycoprotein activity in an immortalized rat brain endothelial cell line, GPNT.

The blood-brain barrier (BBB) plays an important role in controlling the passage of molecules from the blood to the extracellular fluid environment of the brain. The multidrug efflux pump P-glycoprotein (P-gp) is highly expressed in the luminal membrane of brain capillary endothelial cells, thus forming a functional barrier to lipid-soluble drugs, notably, antitumor agents. It is of interest to develop an in vitro BBB model that stably expresses P-gp to investigate the mechanisms of regulation in expression and activity. The rat brain endothelial cell line, GPNT, was derived from a previously characterized rat brain endothelial cell line. A strong expression of P-gp was found in GPNT monocultures, whereas the multidrug resistance-associated pump Mrp1 was not expressed. The transendothelial permeability coefficient of the P-gp substrate vincristine across GPNT monolayers was close to the permeability coefficient of bovine brain endothelial cells cocultured with astrocytes, a previously documented in vitro BBB model. Furthermore, the P-gp blocker cyclosporin A induced a large increase in apical to basal permeability of vincristine. Thus, P-gp is highly functional in GPNT cells. A 1-h treatment of GPNT cells with dexamethasone resulted in decreased uptake of vincristine without any increase in P-gp expression. This effect could be mimicked by protein kinase C (PKC) activation and prevented by PKC inhibition, strongly suggesting that activation of P-gp function may involve a PKC-dependent pathway. These results document the GPNT cell line as a valuable in vitro model for studying drug transport and P-gp function at the BBB and suggest that activation of P-gp activity at the BBB might be considered in chemotherapeutic treatment of cancer patients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1999

Transport of cationized anti-tetanus Fab'2 fragments across an in vitro blood-brain barrier model: involvement of the transcytosis pathway.

Tetanus neurotoxin reaches the CNS by axonal retrograde transport and thus becomes inaccessible to current treatments. A possible strategy to improve current therapy for tetanus disease would be the vectorization of Fab'2 fragments, allowing their delivery into the CNS. The purpose of this study was to investigate whether after cationization anti-tetanus Fab'2 fragments are able to cross the blood-brain barrier, the first obstacle to CNS delivery. We used primary cocultures of bovine brain capillary endothelial cells and newborn rat astrocytes as an in vitro model to study the binding and transport of cationized Fab'2 (cFab'2) fragments across the brain endothelium. We first show that cationization does not alter Fab'2 affinity for tetanus toxin. Then we demonstrate that after cationization Fab'2 fragments are able to bind to the negative charges on the surface of endothelial cells and subsequently to be transported across the endothelial cell monolayer without any modification of affinity. Finally, using fluorescence microscopy, we show that cFab'2 fragments are transported through endocytotic vesicles. The present study demonstrates that cationization allows Fab'2 directed against tetanus toxin to be transported through brain endothelium by adsorptive-mediated transcytosis. We suggest that this vectorization way could be a promising delivery strategy for carrying anti-tetanic immunoglobulin fragments across the blood-brain barrier to improve tetanus treatment.

Animals↗

PubMed1998

Synthesis and biological activity of chimeric structures derived from the cytotoxic natural compounds dolastatin 10 and dolastatin 15.

The natural cytotoxic compounds dolastatins 10 and 15 exhibit great similarities in structure and in their biological activity profiles. Two compounds (1 and 2) formed by interchanging the dolaisoleuine residue of dolastatin 10 and the MeVal-Pro dipeptide of dolastatin 15 were synthesized in order to evaluate the possible equivalence of these units. These compounds can be considered as chimeras of dolastatins 10 and 15 formed by the N-terminal part of the former and the C-terminal part of the latter and vice versa. Both analogues exhibited a marked decrease in their cytotoxic activity but showed similar differential cytotoxicity with regard to the cell lines assayed compared with the parent compounds. HT-29 cell line was the least sensitive one. However, this activity was in the nanomolar level and close to that of vincristine. The differences in their effect on tubulin polymerization were less pronounced. We confirmed the already known crucial role of the Dil residue in this assay. The nonequivalence of the Dil unit and the MeVal-Pro dipeptide probably reflects modification in the relative positions of the N-dimethylamino and the phenyl moieties.

Animals↗

PubMed1998

Drug metabolizing enzyme activities and superoxide formation in primary and immortalized rat brain endothelial cells.

The activities of several enzymes involved in drug metabolism, NADPH-cytochrome P450 reductase, cytochrome P450 isoforms CYP1A and CYP2B, and uridine diphosphate glucuronosyltransferase (UGT) have been measured in primary cultures of rat cerebrovascular endothelial cells and in the immortalized rat brain endothelial cell line RBE4. These drug metabolizing activities were similar in the microsomes prepared from both cell types, even after 20 passages for RBE4 cells. These results were confirmed by Western immunoblotting analysis, using polyclonal antibodies raised against rat liver enzymes. The superoxide production observed during NADPH-cytochrome P450 reductase-dependent monoelectronic reduction of four xenobiotics, menadione, anthraquinone, nitrofurazone and diquat, was also investigated in these cultured cells at confluence. The rates of radical production were concentration-dependent. The superoxide formation induced by quinone metabolism was comparable in both cell cultures, and high amounts of superoxide radicals were produced even after 20 passages of RBE4 cells. On the other hand, nitrofurazone and diquat metabolism produced weak amounts of superoxide radicals in both cell types. Taken together, these results suggest that RBE4 cell line seems to constitute a valuable in vitro model for studies on the activity of some enzymatic systems involved in drug metabolism at the blood-brain barrier and the functional consequences of their activity.

Animals↗

PubMed1998

[Controlled analgesia in a burn patient: fentanyl sparing effect of clonidine].

OBJECTIVE: To determine the sparing effect of clonidine (C) on fentanyl (F) demand in burned patients under PCA. STUDY DESIGN: Prospective, randomized, double blind study versus placebo. PATIENTS: Twelve consecutive patients with mean burn surface area of 20 +/- 9%, studied between the third and the eighth day post-burn. METHODS: F was delivered by a PCA pump (bolus: 1 mg.kg-1). In the morning, burn patients received additional F (5 mg.kg-1) before hydrotherapy. After randomisation, C or placebo (P) were alternatively infused over 24 hours. Demands for F during the morning, the afternoon and the evening were noted. Pain scores were measured on a visual analogic scale. In eight patients, plasma levels of F (pF) were iteratively measured. Heart rate, arterial pressure, respiratory rate and SpO2 were monitored. RESULTS: Analgesic demands were 19.5/day under P and 9.5 under C (P < 0.0001). Pain reoccurred for pF of 4.1 under C vs 5.7 under P (P < 0.05) with same pain scores in the two groups. After a pain stimulus, pain scores were lower under F, despite lower pF (P < 0.05). Arterial pressure and heart rate were significantly lowered during the first hour of C infusion. CONCLUSION: Doses of F and pF required to reach analgesia were very high. Adding C decreases by 50% the F demand and lowers pF. Minor haemodynamic effects were observed during the first hour of C infusion.

Adolescent↗

PubMed1998

Mrp1 multidrug resistance-associated protein and P-glycoprotein expression in rat brain microvessel endothelial cells.

Two membrane glycoproteins acting as energy-dependent efflux pumps, mdr-encoded P-glycoprotein (P-gp) and the more recently described multidrug resistance-associated protein (MRP), are known to confer cellular resistance to many cytotoxic hydrophobic drugs. In the brain, P-gp has been shown to be expressed specifically in the capillary endothelial cells forming the blood-brain barrier, but localization of MRP has not been well characterized yet. Using RT-PCR and immunoblot analysis, we have compared the expression of P-gp and Mrp1 in homogenates, isolated capillaries, primary cultured endothelial cells, and RBE4 immortalized endothelial cells from rat brain. Whereas the mdr1a P-gp-encoding mRNA was specifically detected in brain microvessels and mdr1b mRNA in brain parenchyma, mrp1 mRNA was present both in microvessels and in parenchyma. However, Mrp1 was weakly expressed in microvessels. Mrp1 expression was higher in brain parenchyma, as well as in primary cultured brain endothelial cells and in immortalized RBE4 cells. This Mrp1 overexpression in cultured brain endothelial cells was less pronounced when the cells were cocultured with astrocytes. A low Mrp activity could be demonstrated in the endothelial cell primary monocultures, because the intracellular [3H]vincristine accumulation was increased by several MRP modulators. No Mrp activity was found in the cocultures or in the RBE4 cells. We suggest that in rat brain, Mrp1, unlike P-gp, is not predominantly expressed in the blood-brain barrier endothelial cells and that Mrp1 and the mdr1b P-gp isoform may be present in other cerebral cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1998

Endemic goitre: a research protocol elaboration for eradication.

The iodine deficiency (ID), which affects 1 person out of 6, is relatively neglected by the responsible of Public Health Service, particularly in developing countries. Consequences of ID are far from being negligible: mental retardation, hypofertility, hyperplasia, carcinoma, early ageing and, in very exposed areas, endemic cretinism. Nevertheless, eradication is easy and cheap but it requires rigorous protocols and control of results. The elaboration of these protocols is complex because it must be adapted to environment, population and financial possibilities of concerned countries. Based on our experience in this field, we propose a combined protocol, between the Public Health too liberal approach and that of too expensive research, which can be adapted to several situations.

Data Collection↗

PubMed1998

Endemic cretinism in a traditional society in Mali: from the collectivity to the individual.

The prevalence of endemic cretinism was measured in a village belonging to the Bwa ethnic group in Mali liable to iodine deficiency and suffering from endemic goitre. In this village according to mental and motor handicaps found in cretinism, we used two psychometric tests: the Raven's Progressive Matrice (PM 47) and a "peg test". Using the fiduciary inference method on the two tests associated with a clinical and qualitative approach, we obtained a prevalence of myxedematous cretinism close to 1.2%.

Adolescent↗

PubMed1998

The prevalence of goitre and cretinism in a population of the west Ivory Coast.

Iodine deficiency is a major public health problem in developing countries. The main areas where goitre is prevalent have been identified, but the different degrees of severity and the populations affected have not. Most countries are now attempting to obtain reliable and more extensive data. A pilot study was carried out in the Ivory Coast in order to improve epidemiological knowledge of iodine deficiency and collect the information required to set up an elimination programme. The aim of this study was to assess the prevalence of goitre and cretinism and to measure the main biochemical indicators of thyroid function (T3, T4 and TSH). The study involved 1433 people identified from a census. The prevalence of goitre was 50.3%. There was a significant difference between the examined ethnic groups: 52.7% of the Yacouba and 28.6% of the non-Yacouba had goitre. The most affected age group was 15-45 year. The predominance of women demonstrated the susceptibility of women at child-bearing age to develop the condition. The prevalence of cretinism was approximately 1.5%. Through the assessment carried out using a grid of clinical indicators, it was possible to identify 10 cases of laboratory proven myxedematous cretinism due to hypothyroidism. The concentration of iodine in foodstuffs was below the limit of detection (< 7.5 micrograms/kg) and iodine could not be detected in the water (< 1 microgram.l) The biological profile of the population was affected to a very limited extent, with a mean value (+/- standard deviation) for TSH of 1.93 (+/- 1.56) mIU/l (0.1-4.0) and a free T4 value of 10 (+/- 3.46) pmol/l (8.2-20). These initial results confirm the high prevalence of endemic goitre and the low iodine content of the soil, water and food in the investigated region. The study will be complemented by a nutritional investigation to improve the understanding of iodine balance, after which an appropriate action plan will be proposed.

Adolescent↗

PubMed1998

Epidemiology and prophylaxis of endemic goitre in the Bwa village of Sirao (Mali).

A study was conducted in Mali, in some villages exposed to iodine deficiency disorders (IDD). To treat and, above all, prevent endemic goitre, Lipiodol UF was dispensed in two ways: by intra-muscular injection (475 mg I) or by oral administration (48 mg I to 240 mg I). In two cases, hormone levels regained normal values and thyroid hypertrophies regressed significantly. Nevertheless, the impact of the treatment on the size of the goitres seems to be in favour of injections; which is probably due to the fact that in the village which received Lipiodol UF per os, many goitres were nodular.

Administration, Oral↗

PubMed1997

Modulation of P-glycoprotein activity by glial factors and retinoic acid in an immortalized rat brain microvessel endothelial cell line.

P-glycoprotein (P-gp), a product of the multidrug-resistant (mdr) genes, is expressed in the endothelial cells of the blood-brain barrier (BBB). Effects of glial factors and retinoic acid (RA) on P-gp activity and level were investigated in the immortalized rat brain endothelial cell line RBE4, which expressed immunodetectable P-gp associated with a decrease in accumulation of the P-gp substrates, vinblastine and colchicine. When RBE4 cells were cultured either in the presence of C6-conditioned medium or on C6- or astrocyte-extracellular matrix, intracellular vinblastine and colchicine concentrations were decreased. When the cells were treated with RA, increases in P-gp activities were correlated with increases in P-gp levels. Effects of simultaneous treatments with glial factors and RA were studied in RBE4 cells cultured on astrocyte-extracellular matrix and were shown to be additive on P-gp activity and level. RBE4 cells may serve as a useful in vitro model for basic research on P-gp regulation at the level of the BBB.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1997

F-actin cytoskeleton and sucrose permeability of immortalised rat brain microvascular endothelial cell monolayers: effects of cyclic AMP and astrocytic factors.

The immortalised RBE4 cell line, derived from rat brain capillary endothelial cells, preserves many features of the in vivo brain endothelium, and hence is of interest as a potential in vitro model of the blood-brain barrier (BBB). This study reports the effects of elevated intracellular cAMP and factors released by astrocytes on the F-actin cytoskeleton and paracellular sucrose permeability of monolayers of RBE4 cells. RBE4 cells grown in control medium showed a marked increase in the F-actin staining at the cytoplasmic margin at confluence, which was not significantly enhanced by elevation of intracellular cAMP and/or addition of astrocyte-conditioned medium (ACM). The formation of the marginal band of F-actin was accompanied by an increase in the F-actin content of the RBE4 cells up to confluence, and a decline in F-actin content thereafter. Elevation of intracellular cAMP or co-culture above astrocytes significantly decreased the paracellular sucrose permeability of confluent RBE4 cell monolayers grown on collagen filters (P < 0.01 and P < 0.001, respectively). Co-culture above astrocytes together with elevated cAMP also produced a significant decrease in the sucrose permeability of the monolayer (P < 0.01) but this was no greater than with astrocytes alone. These findings show that the RBE4 cell line may serve as a useful in vitro model for the study of brain endothelial cell physiology and agents which alter the permeability of the BBB.

Actins↗

PubMed1997

Role of P-glycoprotein in colchicine and vinblastine cellular kinetics in an immortalized rat brain microvessel endothelial cell line.

Uptake and efflux of colchicine and vinblastine, whose effects are related to their high-affinity binding to tubulin, were studied in the immortalized rat brain microvessel endothelial cell line RBE4. At 10 nM extracellular drug concentration, uptake equilibrium was approached at 45 hr for colchicine, but at only 3.5 hr for vinblastine. After 1 hr preincubation with 200 nM colchicine or vinblastine, drug efflux fitted biexponential kinetics with an initial fast phase (half-life = 2.2 min and 9.6 min, respectively) and a later slow phase (half-life = 3.6 hr and 1.8 hr, respectively). After 6 hr preincubation with 200 nM colchicine, only the slow phase (half-life = 3.6 hr) could be observed. The colchicine and vinblastine uptake rate was increased by cyclosporin A, an inhibitor of the drug efflux pump P-glycoprotein, which is expressed at the blood-brain barrier. Whereas cyclosporin A decreased vinblastine efflux, its effect on colchicine efflux was apparent after only 13 hr washout and was associated with the re-uptake by cells of colchicine molecules. Differences in uptake kinetics of colchicine and vinblastine could be related to differences in their lipid solubility, and mainly in their binding affinities to tubulin. Differences in efflux kinetics could in addition be explained by the involvement of P-glycoprotein in the efflux of vinblastine, whereas efflux of colchicine was not influenced by this pump. Indeed, binding of colchicine to tubulin would imply that most intracellular colchicine may be inaccessible to P-glycoprotein. In the case of a cytotoxic drug such as colchicine, which is tightly bound to intracellular receptors, the role of P-glycoprotein within the blood-brain barrier would be more to protect the brain against entry of this drug than to detoxify the brain by its extraction.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1997

Glucose transport in immortalized rat brain capillary endothelial cells in vitro: transport activity and GLUT1 expression.

RBE4 cells, an immortalized cell line derived from primary cultures of rat brain capillary endothelial cells, transport 3-O-methylglucose by a mechanism which is saturable with an apparent Km of 14.3 mM. The 3-O-MG uptake can be inhibited by other potential substrates and by non-competitive inhibitors, but not by L-glucose or sucrose. The transport is unaffected by removal or disruption of the sodium gradient. Under conditions of glucose deprivation the Vmax is increased by 100% with no significant change in Km. GLUT1 protein expression in glucose-deprived cells is also increased by 116%. This increase in Vmax can be blocked by the protein synthesis inhibitor, cycloheximide. Uptake was also increased in preconfluent cells and this increase was associated with increases in GLUT1 protein expression. This suggests that the changes in uptake are due to a de novo synthesis of transporters and not to insertion of transporters from an intracellular pool. This study would support the conclusion that the GLUT1 isoform is responsible for glucose transport in RBE4 cells and that these immortalized brain capillary endothelial cells may be used as an in vitro model for analysis of glucose transport regulation at the blood-brain barrier.

3-O-Methylglucose↗

PubMed1997

Usefulness of longitudinal evaluation of Cyfra 21-1 variations in advanced lung cancer monitoring.

To investigate the usefulness of Cyfra 21-1 as an indicator of therapy effectiveness and prognosis in advanced primary lung cancer, sixty-three patients were selected on the basis of a high Cyfra 21-1 serum level (> 3.3 ng/ml) at the time of diagnosis. Serial assays of Cyfra 21-1 were performed during the first three courses of chemotherapy among 63 patients. The serial-values were analysed according to response to treatment and overall survival. After three courses of chemotherapy, a 70% reduction under the initial marker's value or a return to normal was observed for 36 patients. Twenty-two (61%) of these patients presented an objective response to therapy, making Cyfra 21-1 a moderate indicator in terms of positive predictive value (PPV). However, a significant decrease of Cyfra 21-1 was observed in 88% (sensitivity) of the 25 objective responders. Cyfra 21-1 changes after one course of chemotherapy (61 patients) were not sufficient to predict the future response after three courses (sensitivity 52%, specificity 56%, PPV 45%). Among 30 clinical or radiological relapses, a 10% increase or a return upper reference limit in Cyfra 21-1 level was observed in 18 cases (sensitivity 60%, specificity 100%, PPV 100%). Survival data were available for 61 patients. No significant statistical difference (P > 0.05) was found between survival curves depending on a significant decrease of Cyfra 21-1 after the first course of chemotherapy. We can conclude that the only interest of serial Cyfra 21-1 assays may be the detection of relapse, where one observes a significant decrease of the marker correlated with an objective response to first treatment.

Adult↗

PubMed1997

Potential interest of anti-ischemic agents for limiting cyclosporin A nephrotoxicity.

Chronic administration of cyclosporin A induces nephrotoxicity in humans. This is related to a cyclosporin A-induced constriction of afferent glomerular arterioles and mesangial cells, which leads to a decrease in filtration pressure and creatinine clearance. Afterwards, cellular lesions are observed involving mainly tubular atrophy and interstitial fibrosis, both of which are nonspecific. The initial mechanism of its toxicity is not clearly explained. The current pharmacological approach is symptomatic in order to counteract or minimize the consequences of a prime cause, which still remains to be defined. However, cyclosporin A has a deletereous effect on mitochondrial functions and mainly on ATP synthesis, which occurs when Ca2+ accumulates in matrix mitochondria. The effects of trimetazidine, an antischemic drug used in the treatment of angina pectoris, have been assessed. This drug is effective in experimental models of hypoxia induced by cyclosporin A: it restores ATP synthesis previously decreased by Ca2+ and cyclosporin A, and releases a part of Ca2+ excess accumulated by mitochondria at concentrations reached in humans at usual dosage regimens. At higher concentrations, it reverses the mitochondrial permeability transition previously generated (opened) by Ca2+ and a pro-oxidant such as terbutylperoxide (t-BH). It was also observed that trimetazidine does not modify the immunosuppressive effects of cyclosporin A in various models. These data suggest that nephrotoxicity of cyclosporin A is not irrevocably linked to its immunosuppressive effect but that it may be possible to counteract at least partly its nephrotoxic effects without altering its effectiveness in preventing graft rejection.

Adenosine Triphosphate↗

PubMed1996

Ethanol potentiates lipopolysaccharide- or interleukin-1 beta-induced nitric oxide generation in RBE4 cells.

Our present study investigated the effects of ethanol treatment on inducible nitric oxide (NO) synthase pathway from lipopolysaccharide- or interleukin-1 beta-treated cultured rat blood-brain barrier cell line (rat brain endothelial 4 cells: RBE4 cells). Cells were lipopolysaccharide- or interleukin-1 beta-treated with or without ethanol (50, 100 or 200 mM) for 16 or 24 h. Inducible NO synthase activity and mRNA expression were measured using Griess reaction and reverse transcription-polymerase chain reaction (RT-PCR) respectively. In the absence of lipopolysaccharide or interleukin-1 beta, ethanol treatments failed to stimulate inducible NO synthase gene expression. Lipopolysaccharide or interleukin-1 beta increased nitrite production and inducible NO synthase mRNA levels, and ethanol potentiated this effect. We concluded that ethanol could aggravate the consequences of NO generation by RBE4 cells after inducible NO synthase induction following inflammation or sepsis. This ethanol action on NO generation could contribute to circulatory failure associated with shock due to sepsis or hemorrhage, and alter blood-brain barrier permeability.

Animals↗