Purification and properties of human erythrocyte delta-amino-levulinic acid dehydratase (EC 4-2-1-24).

Human delta-aminolevulinic acid dehydratase (ALA-D) was purified 9 000-fold by salt precipitation, ion-exchange chromatography and gel filtration. These methods resulted into an electrophoretically and immunologically pure protein. The optimum pH of the enzyme is 6.6 and its Km with ALA : 4.8 X 10(-4) M. The enzymatic activity was increased by thiol-containing substances, such as dithiothreitol (DTT), which protect the -SH groups of the protein. Zinc, a portion of the enzyme molecule, was partly lost during the purification procedure; its addition enhances the enzymatic activity. Determination of molecular weights and electron microscopy study are in favor of an octameric structure.

Effect of pretreatment with cimetidine or phenobarbital on lipoperoxidation in carbon tetrachloride- and trichloroethylene-dosed rats.

Lipid peroxidation (LP) in vivo as reflected by the exhalation of ethane and n-pentane and by thiobarbituric acid reactive substances (TBARS) in liver microsomes was studied in rats injected with carbon tetrachloride (CCl4) and trichloroethylene (TCE), each at 2 dose levels. Interactions between these chlorinated solvents and cimetidine (CM), an inhibitor of cytochrome P-450-dependent monooxygenases, or phenobarbital (PB) the well known inducer of microsomal enzyme activities were also assessed. A non-hepatotoxic dose of CCl4 did not cause a significant increase in ethane production except in PB-induced rats but did enhance n-pentane elimination, whereas an hepatotoxic dose increased the emission of both hydrocarbons. No interaction between CM and CCl4 could be shown but, as expected, PB potentiated the effect of CCl4. TCE administration led to a moderate dose-independent elevation of n-pentane production but did not affect that of ethane and the effect of TCE was smaller in PB-induced than in CM- or non-pretreated rats. There was no difference in microsomal TBARS content in rats injected with the chlorinated hydrocarbons. The use of butylated hydroxytoluene (BHT) and ethylene diaminetetraacetic acid (EDTA) revealed that direct measurement of TBARS gave inadequate results due to substantial chemical LP in vitro during the whole procedure. With the "ethane-pentane test" it was established that: CM cannot prevent CCl4-induced LP; and TCE hepatotoxicity does not involve increased LP of membrane lipids.

Effects of lead microparticles on the growth characteristics of the BHK21 fibroblast cell line.

BHK21 fibroblastic cells were exposed in vitro to lead microparticles produced by pyrolysis of the organic lead used as an antiknock agent in gasoline. Although non-cytolethal, 10 micrograms of lead/10(6) cells rapidly inhibited cell growth kinetics as well as [3H]thymidine and L-[3H]leucine incorporation by the BHK21 cell line. The growth rate inhibition provoked by chronic exposure to lead microparticles became reversible when the cells were cultured without the microparticulate pollutant. The cloning efficiency of BHK21 cells was impaired by lead concentrations above 1 mg/10(6) cells.

In vivo modulation of muscarine receptors in rat brain by acute lead intoxication.

In our experiments on acutely lead exposed rats we observed a marked increase (a 2-fold or 3-fold increase with 30 mg/kg or 60 mg/kg lead acetate, respectively) in [3H]quinuclidinyl benzilate [( 3H]QNB) specific binding to muscarine receptors from striatum and cortex, without any change in receptor affinity. Muscarine receptor level was maximal 2 h after intoxication, but the effect of lead on [3H]QNB binding was completely reversible in 24 h, without any lead redistribution to other brain areas being observed during this time period. Modulation of muscarine receptors in rat brain during in vivo acute intoxication might be involved in some of the observed neurotoxic effects of lead, resulting of an action on cholinergic neurotransmission. The various possible mechanisms of the lead effect on [3H]QNB binding are discussed.

Urinary excretion of porphyrins by smelter workers chronically exposed to arsenic dust.

Urinary arsenic (inorganic arsenic and methylated metabolites), uroporphyrin and coproporphyrin I and III isomers were determined in 84 smelter workers exposed to arsenic trioxide and in 22 non-exposed controls. Both 'high' and 'low' exposure groups were defined, based on individual's work area (arsenic recovery plant and maintenance) and mean urinary excretion of arsenic was compared to the control group (257 and 129 micrograms/g creatinine against 9.9 micrograms/g creatinine). Total coproporphyrin (I+III) increased in each exposure group as compared to control (63.3 and 59 micrograms/g creatinine against 27.2 micrograms/g creatinine), as a consequence of a 2-fold increase in each coproporphyrin isomer. The mean concentration of uroporphyrin in each exposure group was very similar to that of the non-exposed controls (9.5 and 8.8 micrograms/g creatinine against 10.7 micrograms/g creatinine). These results suggest that long-term occupational exposure of humans to arsenic is associated with coproporphyrinuria and raise the question of the use of this parameter in addition to urinary arsenic for biological monitoring.

In vitro cytotoxicity of cadmium microparticles for rabbit pulmonary alveolar macrophages.

A cytotoxic effect of cadmium monoxide microparticles on rabbit pulmonary alveolar macrophages was observed in vitro from 1 to 2 microg of metal cadmium per million cells (and per milliliter of incubation medium). This threshold was close to the one observed with lead microparticles, which in addition appeared to have a faster cytotoxic action. On the other hand, cadmium microparticles inhaled in vivo are known to be much more toxic to the respiratory system and much more slowly cleared from it than lead particles. These contradictions can be partially explained by our observation that in vitro the ability of alveolar macrophages to phagocytize microparticles was significantly lower for cadmium monoxide than for lead monoxide microparticles.

Toxic effects of cadmium microparticles on the respiratory system. An experimental study on rats and mice.

An experimental study on rats and mice. Scand. j. work environ. & health 3 (1977) 116--121. Experiments on male, specific pathogen-free rats (193) and mice (66) are reported. The test and control animals received a single 15-min exposure to cadmium (cadmium oxide) and aluminum (alumina) microparticles, respectively. The air cadmium content was 10 mg/m3, and 4 microgram of this metal was retained by the lungs of the rats. The animals were observed for 24 days. The following significant differences appeared between the control and test groups: in the cadmium exposed rats the relative lung weight (percentage of body weight) became temporarily higher; the absolute number of alveolar macrophages decreased at first and then increased; numerous polymorphonuclear and lymphocytic cells appeared in the alveoli. According to these inflammatory phenomena, at the 48th h after exposure, there was an alteration in the clearance kinetics of inhaled bacteria and an increase in the death rate of cadmium exposed animals following a test infection with Salmonella enteritidis (rats) or Pasteurella multocida (mice) aerosols. The mechanism of cadmium toxic action on the respiratory system is discussed.

Natural and acquired resistance of mice to infection by airborne Klebsiella pneumoniae after subchronic intoxication by cadmium administered orally.

Mice daily ingested about 22 mg of cadmium per kg of body weight in drinking water for 30 days. On the 30th day, the liver and kidneys of the mice contained about 18 micrograms of Cd2+ per g of fresh organ. A group of these mice was immunized against Klebsiella pneumoniae using two injections of vaccine, the first on the 7th day and the second on the 14th day of intoxication. On the 28th day, the non-immunized and the immunized mice were infected via a respiratory route by one lethal dose 50% of K. pneumoniae (the LD50 for the immunized mice was 2.4 times higher than the LD50 for the non-immunized mice). Comparison with the non-intoxicated control mice showed that the ingestion of Cd2+ did not significantly modify the natural resistance or the acquired resistance of the mice to the infection by airborne K. pneumoniae.

Opposite effects of inhaled cadmium microparticles on mouse susceptibility to an airborne bacterial and an airborne viral infection.

An experimental study on 489 mice is reported. The test animals were submitted to a single 15-mn exposure to atmosphere containing about 10 mg of cadmium microparticles (CdO) per m3 of air and the controls to an equivalent amount of aluminium microparticles (Al2o3). At the 48th hour after exposures, the test and control mice were submitted to a bacterial (Pasteurella multocida) or to a viral (Orthomyxovirus influenzae A) challenge, via the respiratory route. The exposure to cadmium significantly increased the death-rate of mice submitted to the bacterial challenge, but it significantly decreased the death-rate following the viral challenge.

GC/MS confirmatory method for etorphine in horse urine.

A highly sensitive procedure for GC/MS determination of etorphine in horse urine is described. This assay provides both specificity and reliability and is particularly well suited for the confirmation of radioimmunoassay screening procedures usually used for etorphine. After solvent extraction and purifications, the etorphine is characterized as a pentafluoroacetic derivative (PFAA) by using mass fragmentography. The detection limit is 0.1 ng/mL in urine; the coefficient of variation of the estimations is 10.9%. The procedure has been validated after on-field administration of 5 to 90 micrograms of etorphine to five thoroughbred horses (10 to 180 ng/kg).

Lead effect on the oxidation resistance of erythrocyte membrane in rat triton-induced hyperlipidemia.

The anemia observed in severe chronic lead poisoning is in part attributable to alterations in the erythrocyte physicochemical properties. Since they are partly related to the membrane lipid composition, the aim of the present study was to determine the effects of a triton-induced hyperlipidemia on the resistance to oxidation of erythrocyte membranes in lead-treated Wistar rats. Our results showed that triton administration to lead-treated rats induced an increase in erythrocyte choline phospholipid levels together with a significant decrease in the erythrocyte membrane lipid resistance to oxidation. These results led us to suggest that anemia in lead poisoning is linked to interactions between lead present in the membrane and plasma phospholipids. Their increase in rat hyperlipidemia induced by triton resulted in a decrease in the membrane resistance to oxidation and finally in an erythrocyte fragility leading to their destruction.

[Factors of interindividual variations of blood lead levels (author's transl)]. / Facteurs de variation interindividuelle de la plombémie.

The blood lead levels of 1.877 persons living in 8 large French cities or in their suburbs were measured. Blood lead level varies with sex, age, tobacco, wine consumption and date of construction of the house. The specific effect of each of these variables can be quantified. The slope of the regression of blood lead level on age is approximatively 1 microgram/dl per 14 years. Blood lead level increases by 1 microgram for people living in houses built before 1945. The effect of tobacco and wine consumption is greater among males than females. For males the increase is about 3 microgram/dl between non smokers and heavy smokers whereas for females it is about 2 microgram/dl. Wine effect is about 2 microgram/dl among males and 1 microgram/dl among females. These findings are discussed in terms of differences in lead supply or modifications in the number and condition of red blood cells.

Cadmium and lead content of maternal and newborn hair: relationship to parity, birth weight, and hypertension.

Head hair samples were taken from 110 mothers and their newborns at delivery and analyzed for cadmium and lead content. Positive association for cadmium content, but not lead, was found between mothers and newborns. Correlation between the two metals was observed in the babies' hair. Lead levels in the mothers' hair were higher in mothers of parity three or greater than in primiparous mothers. Inverse relationships were found (1) between the cadmium content in babies' hair and their birthweight and (2) between the lead content in mothers' hair and the babies' gestational age. Cadmium levels in babies of hypertensive mothers were 3 times as high as in the hypertensive mothers themselves. A possible change in the permeability of the placenta during pregnancy was postulated.

[Cytochrom P-450. Its value in toxicology. I. Physicochemical and biochemical properties]. / Le cytochrome P450. Son intérêt en toxicologie. I. - Propriétés physicochimiques et biochimiques

We present the distribution of cytochrome P450, the terminal oxidase of the microsomal drug-metabolizing system among the different species, organs, and its subcellular localization. Physicochemical properties, and more specially spectral properties, of this hemoprotein are reviewed. We also described the two microsomal electron transport chains and the hypothetical cyclic oxidoreduction mechanism of cytochrome P450 in the hydroxylation reactions.

[Cytochrome P450. Its importance in toxicology. II. Regulation of its biosynthesis and its activity. Activation and inhibition]. / Le cytochrome P450. Son intérêt en toxicologie. II. Régulation de sa biosynthèse et de son activité. Activation et inhibition

The authors emphasize the influence of hormonal and nutritional factors on the activity level of microsomal enzymes. Induction process of hepatic cytochrome P450 and microsomal enzymes by xenobiotics are described. The existence of different types of hemoprotein P450 in response to the action of different inductors is discussed. We also propose some hypothesis concerning the action mechanism of inhibitors of microsomal enzymes and we point out the role of environmental pollutants.

[Evaluation of a technique for determining blood ethanol levels by gas chromatography. Committee for "determination of blood ethanol levels"].

Art. R.24-1 of the Code governing distribution of beverages and preventive measures against alcoholism: "If the verifications are performed following a traffic accident having occurred under the conditions provided at article L.88 of the present code or in application of articles L.1 and L.3 of the traffic code, the requesting authority keeps a copy of form A and sends: 1. The first blood specimen samples, along with four copies of forms A, B and C, to a laboratory of an establishment part of the public hospital system as defined at article 3 of law n. 70-1318 of December 31 1970 or to an expert biologist registered on the list held by the court of appeals as provided by article R.32 of the code governing distribution of beverages and preventive measures against alcoholism; 2. The second sample, along with one copy of forms A, B and C, to another expert biologist registered on the same list and in charge of eventually performing a control analysis. The laboratory or the expert biologist having performed the analysis reports the results on forms C and forwards one copy of forms A, B and C directly, under separate cover and stamped confidential to the competent Procureur de la Republique, to the region in which the misdemeanor or the accident occurred. The results reported on the form are immediately transmitted to the requesting authority.

[Risks related to the uncontrolled development of pharmacognosy in the United States and France]. / Risques liés à l'essor incontrôlé de la pharmacognosie aux Etats-Unis et en France.

A number of plants of ancestral tradition exhibit properties deserving therapeutic applications. However, their use in conditions which do not guarantee sufficient safety may lead to incidences and sometimes serious accidents. In the US the weakness of the present provisions of the federal regulation do not allow a satisfactory and preliminary control. Moreover, these plants are mostly prescribed by non-medicals and outside the authority of pharmacists. This situation would be highly prejudicial if it would be implemented in Europe. France has a well conceived and satisfactory system, but which is unable to benefit from new accessions, namely exotic plants. To ignore them would lead to strengthening the already existing and parallel organizations. The authors suggest that the health authorities should create a complementary system open to new medicinal plants, avoiding uncontrolled sales. They suggest also that before any acceptance a realistic probationary period would be applied in order to evaluate the quality but overall the eventual toxicity of these plants.