Biomedical subjects

B Gressier

Publications and source records attributed to B Gressier.

71 records · Page 4Linked to original sources

PubMed1993

Human leucocyte elastase (HLE) preferentially cleaves the heavy chain H2 of inter-alpha-trypsin inhibitor (ITI).

Inter-alpha-trypsin inhibitor (ITI) is a complex protein containing two heavy polypeptide chains (H1 and H2) and a light chain, which in the free state is known as bikunin. In vitro cleavage of ITI with different proteases releases bikunin, but does not abolish the antitryptic activity. To study the mechanism of bikunin release, ITI was incubated with human leucocyte elastase (HLE). The resulting ITI fragments were characterized by (i) their electrophoretic and chromatographic behavior. (ii) their immunological reactivity towards antibodies specific for each of the heavy chains H1 and H2, and (iii) their N-terminal sequences. Our results demonstrate that the H2 heavy chain of ITI is particularly sensitive to HLE, and that early cleavage products (M(r)-values 120-150,000) consist of H1 linked to bikunin. A scheme is proposed for the mechanism for ITI degradation.

Alpha-Globulins↗

PubMed1993

Comparison of in vitro effects of two thiol-containing drugs on human neutrophils hydrogen peroxide production.

During inflammatory disorders, potentially destructive reactive oxygen species, especially hydrogen peroxide, are produced by activated phagocytic cells. It was demonstrated in vitro that mesna and N-acetylcysteine (NAC), mucolytic thiols, have antioxidant properties. An estimation was made of the 50% inhibitory concentration (IC50) of mesna and NAC for PMA-induced H2O2 production by human neutrophils, the results being 70 mcM and 77 mcM, respectively. The mechanism which governs mesna and NAC reactions results from a scavenging effect of H2O2: the calculated IC50s of this effect were 30 mcM and 42 mcM, respectively, in free cellular experimentation. The results suggest that mesna and NAC might be used as antioxidants in aerosols to prevent tissue damage inflicted by this reactive oxygen species, especially in the lungs.

Acetylcysteine↗

PubMed1992

Stability and compatibility of four anthracyclines: doxorubicin, epirubicin, daunorubicin and pirarubicin with PVC infusion bags.

A rapid isocratic technique was developed for the analysis of four anthracyclines (doxorubicin, epirubicin, daunorubicin and pirarubicin) in parenteral solutions using high pressure liquid chromatography (HPLC) with fluorescence detection and a C18 Hypersil ODS column. The availability and compatibility of these drugs from solutions infused via PVC infusion bags through PVC administration sets have been examined. No significant drug loss was observed during simulated infusions (n = 4) for 24 h using PVC infusion bags and administration sets. No significant difference was found between infusion solutions (5% glucose or 0.9% NaCl), except for pirarubicin. The reconstitution of pirarubicin in 0.9% NaCl was impossible, because we observed a precipitation of the compound in solution. The stability of the drugs was also studied in solution, in PVC bags after storage at 4 degrees C with protection from light. The results show the stability of doxorubicin, epirubicin and daunorubicin during 7 days of storage to be satisfactory, irrespective of the infusion solution (5% glucose or 0.9% NaCl). In the case of pirarubicin, the stability of the drug was satisfactory during 5 days of storage in 5% glucose, but beyond, we observed a degradation of the compound with formation of doxorubicin in the infusion solution.

Antibiotics, Antineoplastic↗

PubMed1991

Oxidative inactivation of alpha 1-proteinase inhibitor by alveolar macrophages from healthy smokers requires the presence of myeloperoxidase.

The aim of this work was to study the ability of human alveolar macrophages (AM) of 10 healthy smokers to inactivate alpha 1-proteinase inhibitor (alpha 1PI). Purified alpha 1PI was incubated for 45 min, with human alveolar macrophages before and after stimulation by phorbol myristate acetate (PMA) or opsonized zymosan. As a positive control, the same experiments were performed in parallel with blood human neutrophils (PMN). Results are expressed as percentage of inactivation of alpha 1PI as evaluated from its inhibitory activity against porcine pancreatic elastase. A strong correlation (r = 0.99) was shown when inhibitory activity of alpha 1PI was evaluated against porcine pancreatic elastase or human neutrophil elastase. Unstimulated AM (1.57 +/- 0.9%) as well as stimulated AM (PMA: 1 +/- 0.4%; zymosan: 3 +/- 0.6%) were unable to inactivate alpha 1PI. Gel electrophoresis of alpha 1PI demonstrated that AM before or after stimulation induced a slight proteolysis of alpha 1PI, whereas both cleaved and complexed alpha 1PI were found when alpha 1PI was incubated with activated PMN. Both unstimulated (22 +/- 2.6%) and activated PMN (PMA: 91.7 +/- 4.7%; zymosan: 90 +/- 5.5%) were responsible for a significant inactivation of alpha 1PI. Catalase, in contrast to superoxide dismutase, was responsible for a near complete protection of alpha 1PI inactivation by PMN. To better determine the role of PMN secretory products, especially myeloperoxidase (MPO), we also investigated the effect of zymosan-activated PMN supernatants or of purified MPO on the alpha 1PI-AM reaction. MPO assay in PMN supernatants demonstrated that activated neutrophils released significant amounts of MPO (16.8 +/- 4.1 U/ml), whereas MPO was undetectable in activated AM supernatants.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Crossed immunoelectrophoresis does not allow accurate determination of inter-alpha-trypsin inhibitor and its derivatives in plasma.

By crossed-immunoelectrophoresis (CIE) of plasma, using anti-inter-alpha-trypsin inhibitor (ITI) immunoglobulins, beside native ITI, related components are visualized as an heterogeneous peak migrating farther than ITI. The area corresponding to this peak is largely increased in case of inflammatory disease. So, quantitative CIE has been previously proposed for discrete evaluation of ITI and its derivatives. We herein present evidence that CIE does not allow a clear separation of ITI from its derivatives: in this system, they are to some extent coprecipitated. Therefore the resulting overestimation of ITI may explain the previously reported absence of inverse relation between relative contents of ITI and derivatives in case of inflammatory disorders. Our data confirm the view that ITI acts as a precursor of smaller immunologically related inhibitors.

Alpha-Globulins↗

PubMedDate not supplied

A routine HPLC method for monitoring midazolam in serum.

A routine high-performance liquid chromatographic method for measuring midazolam in human serum has been developed. The sample preparation procedure consisted of simple liquid-liquid extraction with dichloromethane, followed by evaporation under nitrogen. The mobile phase used was a mixture of acetonitrile at 0.02 M and sodium acetate at pH 3.0 (80:20, v/v) and a flow-rate of 1.2 mL/min. The separation was performed on two cyanopropyl columns (150 x 4.6 mm). The detection was by UV absorption at 240 nm. A linear range from 10 to 1,000 ng/mL and a quantification limit of 7.4 ng/mL of serum was reached. The mean intra-assay and inter-assay reproducibility from serum sample spiked with 100 ng/mL were 4.1 and 4.7%, respectively. The recoveries from serum sample spiked with 50, 100, 500 ng/mL were 85.46, 85.38 and 85.57%, respectively. This method was developed to allow pharmacokinetics study of midazolam in young patients in short surgical interventions.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

On-line HPLC-electrospray ionization mass spectrometry: a pharmacological tool for identifying and studying the stability of Gd3+ complexes used as magnetic resonance imaging contrast agents.

The identification of MRI contrast agents (CAg) as gadolinium complexes often used at very low concentrations in Pharmacology was carried out by ESI-MS or HPLC-ESI-MS. Firstly, Omniscan, Dotarem and Magnevist were tested. In these compounds, the Gd3+ ion must be solidly chelated by linear or macrocyclic ligands because of the severe toxicity of the free Gd3+. Spectra were obtained at low voltage, preserving the non-covalent binding integrity of the complexes, and at various higher voltages showing the progressive destruction of the complexes. Secondly, a direct reaction of these drugs with the oxidative human neutrophil production, induced in vitro by Phorbol 12-myristate 13-acetate enhancing the respiratory burst, was investigated. This was done to mimic what happens in the case of inflammatory diseases, or infection, or when people are likely to develop anaphylactoid reactions, as the i.v. injection of CAg causes contact between the complexes and neutrophils in the blood. Analysis by HPLC-ESI-MS coupling did not show any direct reaction between Gd complexes and the chemical compounds in the neutrophil oxidative metabolism, even if uncertainty remains as regards meglumine salt. HPLC-ESI-MS is a good way of visualizing characteristic, Gd isotopic distribution and of following its associations in biological samples.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

Determination of cyclohexamone after derivatization with 2,4-dinitrophenyl hydrazine in intravenous solutions stored in PVC bags by high performance liquid chromatography.

A high performance liquid chromatographic procedure is described for the determination of cyclohexanone leached in intravenous solutions from the poly(vinyl chloride) bags. After derivatization with 2,4-dinitrophenylhydrazine and extraction with pentane, the cyclohexanone derivative was analysed on a C18 BDS Hypersil column using mobile phase mixture of acetonitrile:water (55:45). Ultra-violet detection was performed at 368 nm. The limit of quantification was 30 ng/mL and the assay was linear from 0.05 to 50 micrograms/mL. The recovery was better than 95%. The proposed method is satisfactory in its accuracy and precision with particularly relative standard deviations (RSD) for intra-assay and inter-assay of below 10%. This method has been successfully used for the determination of cyclohexanone in aqueous solutions such as sodium chloride (0.9%) and glucose (5%) stored in PVC containers. The values obtained varied between 2.04 and 44.9 micrograms/mL according to solutions and volume.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

Solid phase extraction and high performance liquid chromatographic determination of dobutamine in plasma of dialysed patients.

An isocratic reversed-phase high performance liquid chromatographic method has been developed for th e determination of dobutamine in the plasma of dialysed patients. A solid phase extraction method with a Sep-Pak C18 cartridge was used to isolate the drug and isoxsuprine (internal standard) from plasma. The separation was carried out on an ODS-Hypersil column with 0.1 M phosphate buffer:acetonitrile:methanol (72:20:8 v/v/v) as the mobile phase. The recovery of dobutamine added to plasma by the extraction procedure was 87 +/- 2.3% (mean +/- SD). The accuracy and reproducibility of the method were within acceptable limits over the concentration range 0-1000 ng/mL. Quantification was by fluorescence detection at 275 nm excitation and 310 nm emission wavelengths with a detection limit of 5 ng/mL for dobutamine. This procedure was applied to ascertain the pharmacokinetics of dobutamine infusion in nine patients with cardiogenic shock and end-stage renal disease undergoing haemodialysis.

Chemical Phenomena↗

PubMedDate not supplied

Oxidant radical release by alveolar macrophages after cadmium chloride exposure in vitro.

Chronic exposure to cadmium can cause lung emphysema, the mechanism of which is unknown. Current concepts on the pathogenesis of emphysema largely emphasize the role of a protease-antiprotease imbalance. The aim of this work was to study the effects of cadmium on the regulation of antiprotease activity and the release of oxidant radicals from alveolar macrophages. Guinea pig alveolar macrophages (AM) were exposed overnight to cadmium chloride (CdCl2) in vitro. To define the cytolytic threshold dose, cell lysis was evaluated by trypan blue exclusion and lactate dehydrogenase release. Non-cytolytic concentrations were then used (0.1, 0.4 and 0.8 ppm) to simulate chronic exposure conditions. Overnight exposure to 0.1, 0.4 and 0.8 ppm CdCl2 decreased intracellular ATP (mean +/- SD: 91 +/- 8%, 72 +/- 7%, 50 +/- 8% of control cells, respectively), suggesting that even at non-cytolytic doses, Cd2+ can cause cell injury. The assessment of oxygen radical release from AM after overnight exposure to CdCl2 showed a dose-dependent decrease to 54.3 +/- 8.2%, 32.2 +/- 4.3% and 25 +/- 3% of control after exposure to 0.1, 0.4 and 0.8 ppm Cd2+, respectively. At non-cytolytic concentrations (0.1, 0.4 and 0.8 ppm) CdCl2 did not decrease alpha 1-proteinase inhibitor activity either in the absence of AM or in the presence of AM and myeloperoxidase. In conclusion, our in vitro results do not suggest that a protease-antiprotease imbalance is involved in the pathogenesis of cadmium-induced emphysema.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

PubMedDate not supplied

Pharmacokinetics of midazolam: comparison of sublingual and intravenous routes in rabbit.

In France, the legal routes used to administer midazolam to a patient are intravenously and intramuscularly. For anaesthetists, these routes are not well adapted to paediatric use; they lead to pain at injection site and stress on children. The sublingual route should be a good compromise between stress and quick efficiency. We have developed a sublingual tablet of midazolam. The aim of the present investigation is to compare the pharmacokinetic parameters of midazolam tablets administered by the sublingual and intravenous routes in 6 rabbits to determine the bioequivalence between these routes. We have estimated the 1-hydroxy-midazolam serum level by difference between RRA and HPLC values. By the sublingual route, midazolam absorption is substantial and fast. The statistical analysis, on data obtained with HPLC dosage, shows no significant difference between pharmacokinetic parameter values calculated after intravenous and sublingual administration (0.5 mg). The absolute bioavailability was close to 100%. With RRA dosage, however, AUCs were greater than those obtained by HPLC dosage (174%). 1-hydroxy-midazolam seems to have a great importance in BZD activity. To estimate the bioequivalence between intravenous and sublingual midazolam administration, it is necessary to take into account the active metabolites.

Administration, Sublingual↗

PubMedDate not supplied

Induction of propranolol metabolism in isolated rats hepatocytes treated by di(2-ethylhexyl) phthalate (DEHP) and mono(2-ethylhexyl) phthalate (MEHP).

Blood lines of polyvinyl chloride (PVC) for hemodialysis usually contain di(2-ethylhexyl) phthalate (DEHP) as a plasticizer. Previous studies show that 1 mg/kg of this plasticizer can leach into the blood during one dialysis session. It is rapidly metabolized in the liver. Mono(2-ehtylhexyl) phthalate (MEHP), its main metabolite can be detected as well. After oral administration to rodents, both compounds caused a variety of adverse biological effects such as testicular atrophy, peroxisome proliferation and hepatic peroxisomal enzyme induction. Male wistar rats were treated intraperitoneally by DEHP and MEHP using twice the dose of that involved in human exposure during a dialysis session. Propranolol metabolism by hepatocytes was investigated after fresh isolation from treated and untreated rats by means of reverse phase HPLC. The choice of propranolol as a substrate was made because of its rather quick liver metabolisation. Phenobarbital was chosen in the study as a reference of enzymatic inducer to evaluate the inducing effect of DEHP and MEHP. Propranolol was metabolized by the hepatocytes of both treated and untreated rats. Hepatocytes isolated from rats treated by phenobarbital, MEHP and DEHP were shown to have a higher speed constant of metabolism indicating a rapid metabolism of propranolol. Under these conditions, in fact, propranolol metabolisation was found to be respectively 6, 2.7, 2 times faster than the propranolol metabolisation of untreated rats. The hypothesis that DEHP and MEHP are enzymatic inducers, particularly cytochrome P450 (CYP) inducers of the xenobiotics metabolism on the intact liver after IP administration has become been found to be valid. The results obtained in this study confirm the value of isolated hepatocytes as an in vivo drug metabolism predictive model.

Animals↗

PubMedDate not supplied

In vitro effects of spiramycin and dirithromycin on IL1 beta production by human LPS-stimulated mononuclear cells.

Polymorphonuclear neutrophils are the predominant cells in acute inflammatory lesions and their functions and recruitment are regulated by cytokines, including IL1, TNF and IL8. Antibiotic modulation of inflammatory effects has stimulated investigations of antibiotics for their potential activity as immunomodulators over their primary bactericidal or bacteriostatic activities. This study reports the influence of macrolides, spiramycin and dirithromycin on IL1 beta production. Mononuclear cells, isolated from healthy human volunteers, were preincubated with macrolides (0.1 to 500 micrograms/ml) and stimulated by Escherichia coli lipopolysaccharide. Then, IL1 beta production was detected by western blotting analysis. At therapeutic concentrations, dirithromycin and spiramycin seemed to enhance IL1 beta production by LPS-stimulated cells, with +37 per cent and +28 per cent at 1 microgram/ml respectively. At supratherapeutic concentrations, these drugs seemed to inhibit IL1 beta production through protein kinase C inhibition, with inhibitory concentrations 50 per cent of 378 micrograms/ml for dirithromycin and 234 micrograms/ml for spiramycin. So, macrolides may modulate the host defence system through their influence on cytokine production.

Anti-Bacterial Agents↗

PubMedDate not supplied

Compatibility study of 5-fluorouracil with PVC bags after repackaging into two types of infusion admixtures.

The stability and compatibility of 5-fluorouracil (5-FU) in admixtures for continuous intravenous infusion using PVC bags and administration sets were studied. 5-fluorouracil was reconstituted and diluted to 1.8 mg/ml for infusion in polyvinyl chloride and glass containers, and to 1 mg/ml to 16 mg/ml for storage in polyvinyl chloride bags containing 5 per cent dextrose or 0.9 per cent sodium chloride injections. Admixtures were stored at +4 degrees C and with protection from light, for 7 days. Analyses were performed by HPLC. No significant drug loss was observed during simulated infusions using PVC infusion bags and administration sets vs glass bottles and administration sets, over an infusion period used in hospitals (24 h). The solution stored at +4 degrees C with protection from light in PVC bags showed that at 1 mg/ml to 16 mg/ml, 5-fluorouracil was stable at least for 7 days in 0.9 per cent sodium chloride and 5 per cent dextrose.

Antimetabolites, Antineoplastic↗

PubMedDate not supplied

Functional and immunoreactive alpha 1 proteinase inhibitor in bronchoalveolar lavages: methodological studies.

The functional activity of alpha 1 proteinase inhibitor (alpha 1PI) in bronchoalveolar lavages (BAL) was determined with an automated method, using its inhibitory capacity against porcine pancreatic elastase. Immunoreactive alpha 1PI was measured by immunonephelometry-laser (INL). These two methods may generally be applied on unconcentrated samples. Precision and accuracy of both methods are studied. INL was preferably used to electroimmunodiffusion (EID) because it gave unchanged values after alpha 1PI had reacted with proteases. In BAL, for some specimens, the alpha 1PI content evaluated by EID was underestimated with respect to its measurement by INL. The degree of underestimation is related to the presence of non-functional forms of alpha 1PI.

Blood Proteins↗

PubMedDate not supplied

Amisulpride evaluation by radioreceptor assay comparison with HPLC procedure after single administration in the rabbit.

A radioreceptor assay (RRA) was developed to determine plasma levels of amisulpride. In in vitro binding conditions, the RRA technique was sensitive (11.6 nmol/l) and reliable, with a high degree of precision. The reproducibility of the method through statistical coefficients was < 7%. This method was applied to a pilot pharmacokinetic study in rabbits following single i.v. administration of amisulpride at 10 mg/kg. The results obtained were compared with those obtained by high performance liquid chromatography method (HPLC) in order to assess the validity of this new RRA technique.

Amisulpride↗

PubMedDate not supplied

Decrease of hypochlorous acid and hydroxyl radical generated by stimulated human neutrophils: comparison in vitro of some thiol-containing drugs.

Among reactive oxygen species generated by human neutrophils during inflammatory disorders, hypochlorous acid and hydroxyl radical are especially involved in many diseases such as arteriosclerosis or emphysema. It was shown in vitro that two thiol-containing drugs, mesna and N-acetylcysteine, have antioxidant properties towards these oxidants. The 50% inhibitory concentrations (IC50s) of mesna and N-acetylcysteine for hypochlorous acid production by stimulated neutrophils were 29 and 30 mcM, respectively, and for hydroxyl radical production, IC50s were 520 and 480 mcM, respectively. With this in vitro demonstrated effectiveness, both mesna and N-acetylcysteine have been considered as therapeutic antioxidants to decrease tissue damage inflicted by an excess of activated neutrophils by scavenging hypochlorous acid and hydroxyl radical.

Acetylcysteine↗