Biomedical subjects

C Giroud

Publications and source records attributed to C Giroud.

At least 19 recordsLinked to original sources

PubMed2000

Salvia divinorum: an hallucinogenic mint which might become a new recreational drug in Switzerland.

Salvia divinorum Epling & Jativa is an hallucinogenic mint traditionally used for curing and divination by the Mazatec Indians of Oaxaca, Mexico. Young people from Mexican cities were reported to smoke dried leaves of S. divinorum as a marijuana substitute. Recently, two S. divinorum specimens were seized in a large-scale illicit in-door and out-door hemp plantation. Salvinorin A also called divinorin A, a trans-neoclerodane diterpene, was identified in several organic solvent extracts by gas chromatography-mass spectrometry. The botanical identity of the plant was confirmed by comparing it to an authentic herbarium specimen. More plants were then discovered in Swiss horticulturists greenhouses. All these data taken together suggest that many attempts exist in Switzerland to use S. divinorum as a recreational drug. This phenomenon may be enhanced because neither the magic mint, nor its active compound are banned substances listed in the Swiss narcotic law.

Diterpenes↗

PubMed2000

Effects of ultraviolet light on free and peptide-bound pyridinoline and deoxypyridinoline cross-links. Protective effect of acid pH against photolytic degradation.

Little is known about the photodegradation of pyridinoline (Pyd) and deoxypyridinoline (Dpd), which are two mature cross-links stabilizing collagen within extracellular matrix. In this study, highly purified free Pyd and Dpd cross-links have been degraded by irradiation with ultraviolet light and we have shown that photolysis varies with the pH value. Assessment of photolysis in basic (pH 9) and neutral (pH 7) solutions by high-performance liquid chromatography as well as by UV absorbance measurement indicates that both cross-links are degraded after a 24 h UV exposure, while in acidic solution (pH 3) only Dpd is photolysed, suggesting that acid pH provides major protection against Pyd photolysis. Photodegradation products have been studied by amino-acid and mass spectral analysis. Both methods confirm the lack of Pyd degradation in acid pH. Furthermore, amino-acid analysis allows us to identify hydroxylysine and lysine as a result of Pyd and Dpd photolysis, respectively, indicating that the mechanism of photodegradation involves the cleavage of the pyridinium ring on each side of the quaternary nitrogen. Finally, we have also studied the photolysis of different molecular species of type I collagen peptides, obtained by digestion with collagenase of demineralized turkey bone. Our results indicate that even when they are part of the structure of collagen peptide, Pyd and Dpd can be photolysed. However, we have shown that the larger the peptide is, the smaller are the effects of UV irradiation.

Amino Acids↗

PubMed1999

Fatal flecainide intoxication.

A fatal case attributed to flecainide acetate (Tambocor), a class Ic antiarrythmic drug, is presented. Flecainide was detected by GC/MS in gastric contents, blood and liver as well. The urine analysis revealed the presence of its dealkylated metabolite. Body fluids and tissue concentrations determined by GC/ECD were 7.7 mg/kg in femoral blood, 0.26 mg/kg in bile, 18 mg/kg in liver, 0.17 mg/kg in cerebrospinal fluid, 0.22 mg/kg in brain cortex and 28.9 mg/kg in urine. The total amount of flecainide in gastric contents was about 43 mg. Even taking into account the postmortem redistribution of flecainide, its blood level still remains in the toxic range.

Aged↗

PubMed1999

Fatal overdose of tramadol and alprazolam.

A 30-year-old woman, with history of depression, was found dead after the ingestion of an unknown quantity of Xanax (alprazolam), Tramal (tramadol) and alcohol. At the autopsy only a slight decomposition and a diffuse visceral congestion were noticed. Biological samples obtained at autopsy were analysed to detect the presence of alprazolam, tramadol and alcohol. Blood concentrations of alprazolam, alcohol and tramadol were 0.21 mg/l, 1.29 g/kg and 38.3 mg/l, respectively.

Adult↗

PubMed1999

Method for quantification of morphine and its 3- and 6- glucuronides, codeine, codeine glucuronide and 6-monoacetylmorphine in human blood by liquid chromatography-electrospray mass spectrometry for routine analysis in forensic toxicology.

Simultaneous determination of opiates and their glucuronides in body fluids has a great practical interest in the forensic assessment of heroin intoxication. A selective and sensitive method for quantification of morphine and its 3- and 6-glucuronides, codeine, codeine glucuronide and 6-monoacetylmorphine (6-MAM) based on liquid chromatography-electrospray ionisation mass spectrometry is described. The drugs were analysed in human autopsy whole blood after solid-phase extraction on a C8 cartridge. The separation was performed on an ODS column in acetonitrile (analysis time 15 min). For the quantitative analysis, deuterated analogues of each compound were used as internal standards. Selected-ion monitoring was applied where the molecular ion was chosen for quantification. The limits of quantification were 0.5 ng/ml for morphine and 6-MAM and 1 ng/ml for the 6-glucuronide of morphine, codeine-6-glucuronide and codeine and 5 ng/ml for the 3-glucuronide of morphine.

Calibration↗

PubMed1999

[Brief history of recent hemp cultivation in Switzerland and subsequent medico-legal problems resulting from hemp cultivation].

In March 1995, a decision about cultivation of cannabis was issued by the Swiss Federal Offices of Public Health, Police and Agriculture in order to satisfy the growing interest of farmers and other people in hemp farming. It pointed out that 1)... each hemp plant contains THC and must be therefore considered a drug, 2)... no permission is required for those who grow hemp without the intention to produce drugs ... meaning that the choice of the plant variety was not restricted to those which are characterized by a low THC concentration and grown in a few countries belonging to the European Union. Claiming that natural hemp must contain significant amounts of THC and thanks to the Swiss legislation, areas dedicated to hemp cultivation develop considerably. Most hemp plants which are submitted to our laboratories by the police for THC quantification belong to the drug-type. Nowadays, a great deal of goods (food and beverages, cosmetics, drugs) made of hemp are marketed in Switzerland. Strong suspicions exist however that several of these products could be used as a screen for the illegal market of cannabis. For instance, despite financial support from the state, fiber hemp cultivation remains unsuccessful. No advantage with regard to seed productivity, edible seed and essential oils qualities and yields have been found for drug hemp over fiber hemp by agricultural research stations up to now. Several clues about the possible illicit use of hemp goods rich in THC, especially hemp tea made of flower tops and "therapeutic" pillows filled with cannabis exist. Recently, two Federal edits were issued in order to restrict the selling of hemp seedlings and of hemp foods and beverages to those containing only low amounts of THC. However, the marketing of hemp plants used for decorating remains free partly explaining the recent success of these "beautiful" plants. Broadly speaking, the Swiss and European legislations about hemp have approached mutually during the last years.

Agriculture↗

PubMed1999

Affinity chromatography using trypanocidal arsenical drugs identifies a specific interaction between glycerol-3-phosphate dehydrogenase from Trypanosoma brucei and Cymelarsan.

A 36-kDa protein was isolated by affinity chromatography using Cymelarsan, an arsenical drug currently used in African trypanosomiasis treatment, as ligand. This protein was identified as glycerol-3-phosphate dehydrogenase. Trypanosomal glycerol-3-phosphate was bound covalently, whereas its counterpart from rabbit muscle bound by ionic interaction. Arsenical drugs inhibit the enzyme in a dose-dependent manner. Oxidation of cysteine residues protects against inactivation without significantly diminishing enzymic activity. Drug concentrations giving 50% inhibition of the dehydrogenase activity were determined for the enzyme from both Trypanosoma brucei and rabbit and indicate a higher sensitivity of the trypanosomal enzyme to arsenical drugs and thiol reagents. MS was used to identify residues of glycerol-3-phosphate dehydrogenase bound by Cymelarsan; they are not conserved in the mammalian enzyme.

Animals↗

PubMed1999

Method for the isolation and purification of pyridinoline and deoxypyridinoline crosslinks from bone by liquid chromatographic techniques.

Significant progress has been made in recent years in the development of new bone resorption markers, based principally on the urinary excretion of pyridinoline (Pyd) and deoxypyridinoline (Dpd) crosslinks. For their measurement, in spite of the recent development of immunoassays, HPLC remains the method of reference. However, the lack of an appropriate internal standard requires large amounts of pure crosslinks for external standardisation. Herein, we describe an efficient method for the isolation of both crosslinks from bone of adult turkey by isocratic semi-preparative HPLC. Demineralized bone is hydrolysed in hydrochloric acid, 9 M. A first liquid extraction step in butanol allowed to eliminate less polar compounds. The aqueous phase was concentrated and separated by gel filtration on Biogel P2 and eluted by acetic acid solution (10%). Fractions containing pyridinoline were pooled, concentrated, and purified on a CF1 cellulose column. Pyd and Dpd crosslinks were then separated isocratically by HPLC on a C18 reversed phase column (Vydac 218 TP 1010, 250x10 mm) and eluted with HFBA as the ion-pairing agent. Retention times of Pyd and DPD were 23.6 and 28.7 min, respectively. Both crosslinks prepared by HPLC were then transformed as hydrochloride to cellulose phosphate and desalted on Sephadex G-10 columns. These two further steps yielded highly purified compounds (the purity was greater than 98% evaluated by aminoacid analysis). In conclusion, the efficiency of this method allows to obtain rapidly Pyd and Dpd without interfering compounds as proven by spectral studies (NMR and mass spectroscopy).

Amino Acids↗

PubMed1999

Exit association-mediated suicide: toxicologic and forensic aspects.

The Swiss German chapter of the Exit Association provides conditional assistance to individuals wishing to end their own lives. The Exit Association advocates death with dignity and fights for the right to freely choose the timing of one's own death. According to the Swiss criminal code (articles 114 and 115), altruistic assistance to suicide is not punishable. Active euthanasia is punished by imprisonment. An individual commits active euthanasia if he or she is driven by honorable motives (e.g., pity) and causes the death of another person wishing to die who seriously and insistently requests such action. Based on our information, the preparation for suicide and its completion relies on a well-defined protocol. First, the candidate's eligibility for Exit Association assistance is verified. The candidate then writes a farewell declaration that explicitly confirms the will to terminate his or her own life. A written report describes the events during the suicide procedure. Depending on the circumstances, the investigative judge requests a forensic autopsy and toxicologic analyses. The results of the forensic investigations conducted in the cases presented here are in agreement with the scenario described in the reports of the Exit Association, namely, suicide by massive ingestion of pentobarbital.

Aged↗

PubMed1999

Interferon-beta inhibits activated leukocyte migration through human brain microvascular endothelial cell monolayer.

Perivascular leukocyte infiltration into the central nervous system is characteristic of multiple sclerosis (MS) pathology. Interferon-beta (IFN-beta) has shown efficacy in the treatment of patients with MS, but the relevant mechanisms remain incompletely understood. In this study the effects of IFN-beta on leukocyte transendothelial migration were investigated using cells relevant to MS pathogenesis, namely human brain microvascular endothelial cells (HB-MVEC). Activated, but not resting leukocytes exhibited a high transendothelial migration capacity. HB-MVEC prestimulated with tumor necrosis factor (TNF) and IFN-gamma significantly promoted leukocyte transendothelial migration. IFN-beta inhibited the activated leukocyte transendothelial migration on TNF/IFN-gamma-activated HB-MVEC in a dose-dependent manner. A matrix metalloproteinase (MMP) inhibitor and monoclonal antibodies to lymphocyte function antigen-1 (LFA-1) or intercellular adhesion molecule-1 (ICAM-1), but not to very late antigen-4 or to vascular cell adhesion molecule-1 significantly inhibited the transendothelial migration of stimulated leukocytes, suggesting that this phenomenon involves the LFA-1/ICAM-1 interaction and MMP. However IFN-beta did not interfere with the binding of leukocytes to HB-MVEC unless IFN-beta was preincubated with leukocytes or added to HB-MVEC at the time of stimulation. Furthermore IFN-beta did not modulate the expression of adhesion molecules on either stimulated leukocytes or activated HB-MVEC, but partially reduced TNF and interleukin-1 production from stimulated leukocytes during coculture with HB-MVEC. Interestingly, in the presence of IFN-beta, a significant down-regulation of MMP-9 release from stimulated leukocytes was found, especially for the activated form of MMP-9. These results indicate that inhibition of leukocyte transendothelial migration is an important mechanism accounting for the beneficial effects of IFN-beta in the treatment MS patients.

Brain↗

PubMed1998

Both TNF receptors are required for direct TNF-mediated cytotoxicity in microvascular endothelial cells.

The conditions under which tumor necrosis factor-alpha (TNF) induces apoptosis in primary microvascular endothelial cells (MVEC) were investigated. In the absence of sensitizing agents, TNF induced apoptosis after 3 days of incubation in confluent MVEC. In contrast, upon addition of the transcriptional inhibitor actinomycin D (Act. D), confluence was no longer required and apoptosis occurred already after 16 h. To assess the role of either TNF receptor (TNFR) type in apoptosis, MVEC isolated from mice genetically deficient in TNFR1 (Tnfr1o mice) or TNFR2 (Tnfr2o mice) were incubated with TNF in the presence or absence of Act. D. Under sensitized conditions, Tnfr2o MVEC were lysed like controls, whereas Tnfr1o MVEC were completely resistant, indicating an exclusive role for TNFR1. In contrast, in the absence of Act. D, confluent monolayers of wild-type cells were lysed by TNF, but both Tnfr1o and Tnfr2o MVEC were resistant to TNF-mediated toxicity, indicating a requirement for both TNFR types. Overexpression of the anti-apoptotic protein bcl-xL in MVEC led to a protection against the direct, but not the sensitized cytotoxicity of TNF. In conclusion, in pathophysiologically relevant conditions, both TNFR appear to be required for TNF-induced apoptosis in MVEC.

Animals↗

PubMed1998

Car crash after massive ingestion of digoxin and midazolam.

In a case where a 32-year-old man lost control of his vehicle, urine and blood samples were taken 6 h after the crash for toxicological investigations. In the hospital, the driver admitted consumption of some drugs, in particular digoxin and midazolam just before the crash which corresponded to the results of blood analyses. Toxicological findings indicated the presence of digoxin at 12.9 ng/ml and midazolam at 7 ng/ml in the blood. These results suggested that at the moment of the crash digoxin and midazolam blood levels were in the range of toxic and therapeutic concentrations, respectively. Therefore the respective roles of the drugs in the impairment of the ability to drive at the moment of the crash is discussed.

Accidents, Traffic↗

PubMed1998

2C-B: a new psychoactive phenylethylamine recently discovered in Ecstasy tablets sold on the Swiss black market.

This study sought to identify, by means of several analytical methods (GC-MS, HPLC-DAD, CE-DAD, FTIR, and NMR), 4-bromo-2,5-dimethoxyphenethylamine (2C-B), which was found in two sets of tablets obtained from the Swiss black market. Unequivocal identification of 2C-B was only achieved by a combination of mass spectrometric and NMR analysis. Quantitation of 2C-B was performed by HPLC-DAD and CE-DAD. The amounts of 2C-B found in the tablets (3-8 mg) were in the range of the minimum quantity required to induce the effects characteristic of this drug.

Chromatography, High Pressure Liquid↗

PubMed1997

[Ecstasy--the status in French-speaking Switzerland. Composition of seized drugs, analysis of biological specimens and short review of its pharmacological action and toxicity].

Methylenedioxy-N-methylamphetamine (MDMA, "Ecstasy") and other related phenylethylamines are nowadays used extensively in Western Switzerland at dance clubs and raves. There is a widely held belief among teenagers and misusers that ecstasy is safe. In the last years however, an increasing number of reports of MDMA-related deaths has been reported. Acute clinical toxicity problems following MDMA ingestion include hyperthermia, convulsions and arrhythmias. There is also growing concern that these phenylethylamines are neurotoxic and cause long-term damage to serotonineric nerve terminals in animal brains. Qualitative analyses by GC-MS of street samples of ecstasy showed that only a part of them contain MDMA or related phenylethylamines (MDA, MDEA, MBDB and 2C-B). Most of them were mixed with caffeine and an excipient (sugars or polyols [e.g. mannitol]). Amphetamine cut with caffeine and other drugs (e.g. testosterone), stimulants (e.g. pseudoephedrine) and other drugs unrelated to stimulants and phenylethylamines (e.g. LSD, chloroquine, vasodilators) were also detected. Quantitative determinations performed by HPLC-DAD or EC-DAD reveal huge fluctuations in the amount of active substance(s) per tablet. MDMA and related compounds display unique psychoactive properties, acting as a stimulant and inducing feelings of empathy. The effects of MDMA intake are very likely the results of the large release of serotonin (5-HT) in the synaptic cleft, of the inhibition of the re-uptake inactivation of 5-HT and of the inhibition of a key-enzyme involved in the biosynthesis of 5-HT. Forensic investigations performed at our institute showed significant blood levels of MDMA, MDEA and MDA in samples drawn from people suspected of driving under the influence of psychoactive drugs. Up to now, no death could be attributed to MDMA intoxication only because our analyses always revealed the additional presence of toxic amounts of other psychoactive drugs (e.g. opiates, cocaine). Our study shows that because of the variable composition of ecstasy tablets, unpredictable types and amounts of drugs may be taken by MDMA misusers. Moreover, there is considerable concern that traffic accidents may be caused by MDMA-abusers. MDMA intake could result in severe intoxication and even death, especially when combined with other types of drugs.

Chromatography, High Pressure Liquid↗

PubMed1997

Crucial role of tumor necrosis factor (TNF) receptor 2 and membrane-bound TNF in experimental cerebral malaria.

Tumor necrosis factor (TNF) has been implicated in the pathogenesis of experimental cerebral malaria (CM), but the respective role of its two types of receptors has not been established. A significant increase in the expression of TNF-receptor 2 (TNFR2, p75), but not of TNFR1 (p55), was found on brain microvessels at the time of CM in susceptible animals. Moreover, mice genetically deficient for TNFR2 (Tnfr2null) were significantly protected from experimental CM, in contrast to TNFR1-deficient (Tnfr1null) mice, which were as susceptible as wild-type mice. To identify the factors involved in the protection from CM conferred by the lack of TNFR2, we assessed in both knockout and control mice the serum concentrations of mediators that are critical for the development of CM, as well as the up-regulation of intercellular adhesion molecule-1 (ICAM-1) in the brain microvessels. No significant difference in serum levels of TNF and interferon-gamma was found between infected wild-type and Tnfr1null or Tnfr2null mice. Interestingly, the pronounced ICAM-1 up-regulation and leukocyte sequestration, typically occurring in brain microvessels of CM-susceptible animals, was detected in infected control and Tnfr1null mice-both of which developed CM-whereas no such ICAM-1 up-regulation or leukocyte sequestration was observed in Tnfr2null mice, which were protected from CM. Making use of microvascular endothelium cells (MVEC) isolated from wild-type, Tnfr1null or Tnfr2null mice, we show that soluble TNF requires the presence of both TNF receptors, whereas membrane-bound TNF only needs TNFR2 for TNF-mediated ICAM-1 up-regulation in brain MVEC. Thus, only in MVEC lacking TNFR2, neither membrane-bound nor soluble TNF cause the up-regulation of ICAM-1 in vitro. In conclusion, these results indicate that the interaction between membrane TNF and TNFR2 is crucial in the development of this neurological syndrome.

Animals↗

PubMed1997

Platelets play an important role in TNF-induced microvascular endothelial cell pathology.

Tumor necrosis factor-alpha (TNF) is known to be an important mediator in the pathogenesis of several inflammatory diseases. Vascular endothelial cells represent a major target of TNF effects. Platelet sequestration has been found in brain microvessels during experimental cerebral malaria and lung in experimental pulmonary fibrosis, implying that it may participate in TNF-dependent microvascular pathology. In this study, we investigated the mechanisms of platelet-endothelial interaction, using co-cultures between platelets and TNF-activated mouse brain microvascular endothelial cells (MVECs). Adhesion and fusion of platelets to MVECs was evidenced by electron microscopy, dye transfer, and flow cytometry. It was induced by TNF and interferon-gamma and depended on LFA-1 expressed on the platelet surface and ICAM-1 expressed on MVECs. The adhesion and fusion also led to the transfer of platelet markers on the MVEC surface, rendering these more adherent for leukocytes, and to an enhanced MVEC sensitivity to TNF-induced injury. These results suggest that platelets can participate in TNF-induced microvascular pathology.

Animals↗

PubMed1996

Hexose uptake in Trypanosoma cruzi: structure-activity relationship between substrate and transporter.

The gene encoding a hexose transporter, TcrHt1, from Trypanosoma cruzi has been functionally expressed in mammalian Chinese hamster ovary cells. Kinetic parameters of the heterologously expressed protein are very similar to those of the transporter identified in T. cruzi epimastigotes, confirming that TcrHT1 is the major transporter functioning in these parasites. A detailed analysis of substrate recognition using analogues of D-glucose substituted at each carbon position has been performed. The glucose transporter of T. cruzi does not recognize C-3 or C-6 analogues of D-glucose, whereas these analogues were recognized by the glucose transporter of bloodstream-form T. brucei. As for other kinetoplastid transporters, but in stark contrast to the mammalian GLUT family, TcrHT1 can also transport D-fructose, with relatively high affinity (Km = 0.682 +/- 0.003 mM). Amino acid side-chain-modifying reagents were also used to identify residues of the transporter present at the substrate-binding site. While specific modifiers of cysteine, histidine and arginine all inhibited catalytic activity, protection using substrate was only observed using the arginine-specific reagent, phenylglyoxal. Reagents which modify lysine residues had no effect on transport.

Amino Acids↗

PubMed1995

A diamidine-resistant Trypanosoma equiperdum clone contains a P2 purine transporter with reduced substrate affinity.

Following the demonstration that the transport of melaminophenyl arsenical drugs in Trypanosoma brucei is dependent upon an unusual adenosine nucleoside transporter (Carter and Fairlamb, Nature 361 (1993) 173-175) we have investigated adenosine transport in the related parasite Trypanosoma equiperdum (Botat1.1) and a cloned derivative resistant to the diamidine drug berenil (diminazene aceturate) with limited cross-resistance to the melaminophenyl arsenical cymelarsen. The parental strain possesses a bipartite adenosine transport system consisting of one component which is inhibited in a dose-dependent and saturable manner with increasing concentrations of inosine and a second component which is similarly inhibited by adenine. Uptake of adenosine on this second transporter is also inhibited in a dose-dependent fashion by berenil and cymelarsen. Both transporters have high affinity for adenosine (apparent Km values of 0.60 and 0.70 mM and Vmax values of 8.4 and 6.9 pmol (s (10(8) trypanosomes))-1 at 25 degrees C, respectively). Thus T. equiperdum shares with T. brucei a system comprising two adenosine transporters named P1 and P2, respectively. The P1 transporter is similar in the sensitive and resistant T. equiperdum clones, whereas the P2 transporter has reduced transport capacity at physiological adenosine concentration and decreased affinity for adenosine in the drug-resistant clone.

Adenosine↗