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Biomedical subjects

L Rivier

Publications and source records attributed to L Rivier.

29 records · Page 2Linked to original sources
PubMed1991

[Assessment of the intake of opiates (heroin, morphine, codeine and ethylmorphine) by the analysis of intermediate metabolites in the urine: which are the criteria to adopt?].

This report presents the different strategies for identifying heroin users. The criteria allowing a clear distinction between an abuse of heroin and a lawful consumption of opiates are deeply discussed. Reliable and sensitive analytical methods are now available for forensic opiate testing. The detection of 6-mono-acetylmorphine (MAM) indicates that heroin was administered within 24 hours or less of specimen collection. In the absence of MAM or after consumption of several opiates, the relative ratios of morphine, codeine and eventually ethylmorphine must be known in order to determine which opiate(s) was (were) taken. A total amount of opiates of less than 0.3 mg/l very often precludes any characterization of the ingested drug(s). Here we have to point out that forensic opiate testing should be done carefully. Interpretation of results requires more than detection of opiates or morphine alone, irrespective of the number of techniques used.

Forensic Medicine↗
PubMed1991

Rapid high-performance liquid chromatographic determination with fluorescence detection of furosemide in human body fluids and its confirmation by gas chromatography-mass spectrometry.

Furosemide (FD: Lasix) is a loop diuretic which strongly increases both urine flow and electrolyte urinary excretion. Healthy volunteers were administered 40 mg orally (dissolved in water) and concentrations of FD were determined in serum and urine for up to 6 h for eight subjects, who absorbed water at a rate of 400 ml/h. Quantification was performed by HPLC with fluorescence detection (excitation at 233 nm, emission at 389 nm) with a limit of detection of 5 ng/ml for a 300-microliters sample. The elution of FD was completed within 4 min using a gradient of acetonitrile concentration rising from 30 to 50% in 0.08 M phosphoric acid. The delay to the peak serum concentration ranged from 60 to 120 min. FD was still easily measurable in the sera from all subjects 6 h after administration. In urine, the excretion rates reached their maximum between 1 and 3 h. The total amount of FD excreted in the urine averaged 11.2 mg (range 7.6-14.0 mg), with a mean urine volume of 3024 ml (range 2620-3596 ml). Moreover, the urine density was lower than 1.010 (recommended as an upper limit in doping analysis to screen diuretics) only for 2 h. An additional volunteer was administered 40 mg of FD and his urine was collected over a longer period. FD was still detectable 48 h after intake. Gas chromatography-mass spectrometry with different types of ionization was used to confirm the occurrence of FD after permethylation of the extract. Negative-ion chemical ionization, with ammonia as reactant gas, was found to be the most sensitive method of detection.

Administration, Oral↗
PubMed1990

Characteristics of 167 consecutive traffic accident victims with special reference to alcohol intoxication: a prospective emergency room study.

This prospective study examined the characteristics of 167 consecutive traffic accident victims admitted to the emergency room of a major Swiss hospital with particular attention to the presence of a detectable blood alcohol concentration (BAC). The majority of the study population were male (71%), 16-29 years of age (56%) and occupants of an automobile or motorcycle (70%). Most patients were injured during the daytime, with nighttime accidents increasing towards the end of the week. Seventy-five percent of the injured were drivers of the crash vehicle and the majority (56%) were involved in multi-vehicle accidents. Fifty-three percent of all injuries consisted of internal lesions and/or fractures with motorcyclists and pedestrians being the most severely injured. There was a 21% incidence of alcohol intoxication (BAC greater than = 0.8 g/kg); 97% of intoxicated patients were male, of which 38% were 16-29 years of age. There was a distinct age-related alcohol intoxication pattern among males, with an intoxication rate of 20% in the 16-29 age range and 40% in the 30-75 age range. Alcohol-related accidents occurred predominantly in the nighttime and towards the end of the week, and victims of single-vehicle crashes were more likely to be intoxicated (28%) than those injured in multi-vehicle crashes (17%). Moped drivers exhibited the highest rate of intoxication (45%) followed by pedestrians (42%). Our study confirms the high prevalence of acute alcohol intoxication among traffic accident victims in Switzerland, a fact which needs to be considered by the treating medical care providers for the early detection and referral of alcohol-related problems, and which should be limited by effective preventive measures.

Accidents, Traffic↗
PubMed1989

Evidence for the presence of tetrodotoxin in a powder used in Haiti for zombification.

A powder prepared by Haitian voodoo sorcerers for the making of zombis was extracted with acetic acid, the extract concentrated and applied to a small cation exchange column followed by elution with water and then acetic acid. The water and acetic acid eluents were analysed by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. The analyses indicated the presence of an alkaline degradation product of tetrodotoxin, namely 2-amino-6-hydroxymethyl-8-hydroxyquinazoline, after base treatment, and of tetrodotoxin and an isomer on direct thermospray mass spectral activity.

Chemical Phenomena↗
PubMed1985

Identification of Endogenous Gibberellins from Salix pentandra.

Gibberellins A(1), A(19), A(20), and A(29) have been identified by sequential high-performance liquid chromatography retention time (Rt) and combined gas chromatography-mass spectrometry (Rt and characteristic mass spectra) from elongating shoots of Salix pentandra L. Gibberellins A(1) and A(19) were also detected in purified extracts from male and female flowers (catkins) of S. pentandra.

Journal Article↗
PubMed1982

The effects of field preservation on alkaloid content of fresh coca leaves (Erythroxylum spp.).

In order to test the effects of commonly used preservation agents on the alkaloid content of herbarium specimens, fresh leaves of Erythroxylum coca, E. novogranantense, and E. novogranatense var. truxillense were air-or heat-dried or treated with six different liquid preservatives. The leaves were then extracted and analyzed quantitatively for cocaine content. Leaves which were soaked in preservatives showed appreciable pre-extraction of cocaine and probably of other alkaloids. The results compare well with a similar experiment conducted on flavonoid content of the leaves of a palm Jessenia bataua. If portions of herbarium specimens are to be useful for phytochemical screening using microtechniques, at least part of the collection must be air- or heat-dried to retain the chemical constituents.

Alkaloids↗
PubMed1979

Cocaine in blood of coca chewers.

Coca leaves (Erythroxylum coca Lamarck) and powder (5 - 10 g) were taken orally by human subjects in the same way as South American natives do. The cocaine, as measured by mass fragmentography, was immediately detected in the blood, reached peak concentrations from 10 - 150 ng/ml plasma at 0.38 - 1.95 hours, and persisted in the plasma for more than 7 hours. Half-lives of the elimination of cocaine were calculated and ranged from 1.0 to 1.9 hours. The absorption half-lives ranged from 0.2 to 0.6 hours. The shape of the curves fits with the subjective effects reported. There is no reason to believe that the stimulating effect achieved by the use of either coca leaves or powder is not due to cocaine.

Adult↗
PubMedDate not supplied

Analysis of alkaloids in leaves of cultivated Erythroxylum and characterization of alkaline substances used during coca chewing.

Several solvents were tested for the extraction of the alkaloids in Erythroxylum coca. The resulting crude extracts were analyzed by gas chromatography--mass spectrometry. Ethanol extraction was found to be the only quantitative method presenting no artifacts. It was established that cocaine and cis- and trans-cinnamoylcocaine were the endogenous alkaloids in E. coca leaves. From the several breakdown compounds arising during long-term extraction with H2SO4 or CHCl3, ecgonine methyl ester was the only alkaloid fully identified; ecgonine methyl ester was tentatively identified on the basis of its mass spectrum fragmentation pattern. Quantification by mass fragmentography of the three endogenous compounds was performed using a stable-isotope dilution technique on individual leaves of single branches of E. coca, E. novogranatense and E. novogranatense var. truxillense. The relative amounts of these alkaloids changed with leaf age as well as between species and varieties. The variation in alkaloid levels between individual leaves was too great to allow the use of the ratio between cocaine and the cinnamoylcocaine levels as a taxonomic marker. The initial pH value of 17 different alkaline substances traditionally used during coca leaf chewing was measured after dissolution in H2O; values ranged between 10.1 and 12.8. Buffer capacity was determined by titration with HCl. Three types of curve shapes were obtained which could correspond to NaOH, Na2CO3 and NaHCO3 titration curves. One sample of alkaline material had no buffer capacity at all. The recovery and breakdown of the cocaine contained in E. coca leaf power was monitored for one hour at various pHs at 37 degrees C. The levels of cocaine and benzoylecgonine did not change by more than 17% at any of the pHs tested (6.0, 9.0 and 11.5). It was concluded that the alkaline substances are mainly responsible for the transformation of the alkaloids to free bases and not for a major hydrolysis of cocaine.

Alkalies↗