Search

Vertical nanostructure technologies are becoming more important for the down scaling of nanoelectronic devices such as logic transistors or memories. Such devices require dense vertical nanostructured channel arrays (VNCA) that can be fabricated through a top-down approach based on group IV materials. We present progresses on the top-down fabrication of highly anisotropic and ultra-dense Si

International audience; A thorough study of the phosphorus (P) heavy doping of thin Silicon-On-Insulator (SOI) layers by UV nanosecond Laser Thermal Annealing (LTA) is presented in this work. As a function of the implant dose and laser annealing conditions, the melting regimes and regrowth processes, as well as the redistribution and activation of P in the top-Si amorphized layer, were investigated. The findings emphasize the critical role of the thin crystalline silicon layer that remains after the top-Si layer amorphizes, as it provides nucleation seeds for liquid phase recrystallization. The effect of the implant dose on the recrystallization process is thoroughly investigated in terms of melt energy thresholds, crystallographic nature of the resolidified layer, defect formation, surface roughness, and the formation of hillocks on the silicon surface. Optimized laser annealing conditions, corresponding to the laser energies just preceding the onset of the full melt, were identified for all implanted doses. Such optimized layers have perfect crystallinity, negligible P out-diffusion, a nearly perfectly flat P depth profile located below the segregation-induced surface pileup peak, and dopant active concentrations well above 1021 cm−3, which is close to the highest reported values for phosphorus in bulk Si substrates.

International audience; This paper presents the set of simulation means used to develop the concept of N2C2 (neural network compute cube) based on a vertical transistor technology platform. On the basis of state-of-the-art junctionless nanowire transistors (JLNT), TCAD simulation, compact modeling and EM simulation are leveraged through a Design- Technology Co-Optimization (DTCO) to achieve innovative 3D circuit architectures. Further, System-Technology Co-Optimization (STCO) implications on 3D NN system architecture are explored.

In this study we compared the molecular signalling elicited by rexinoids, selective retinoid X receptor (RXR)-activators, in several organs (i.e. liver, kidney, heart) and in hepatocytes of various species. RXR plays the pivotal role of a hetero-dimerization partner for the members of the class II subset of nuclear receptors which regulate the transcription of numerous target genes, following chemical activation. Several of these selective activators are currently used to treat hyperlipidaemia (fibrates), type II diabetes (glitazones), or skin disorders (retinoic acid). Although these therapeutic pathways are not fully elucidated, receptor activation is considered a pre-requisite for efficacy. Therefore RXR, which accepts numerous dimeric partners, is considered a worthwhile pharmacological target. We analysed a number of biochemical and molecular responses to rexinoids which were given orally to mice. Our results showed a prominent involvement of the peroxisome proliferator-activated receptor (PPARα) as a majority of the observed hepatic and renal regulations were abolished in PPARα-knockout animals. Therefore we documented the species-specificity of these rexinoid actions which were reproduced in rat primary hepatocyte cultures but not in cultures of rabbit or human origin. Conversely, we established that the regulation of the pyruvate dehydrogenase kinase (PDK4) gene in the heart, by rexinoids, is independent of PPARα expression. Our results support the obligatory expression of the active, although quiescent, PPARα to sustain a subset of relevant regulations attributable to rexinoids in the liver and kidney. Their cardiac molecular signalling unveiled an alternate transduction pathway and therefore opens new prospects in the therapeutic potential of rexinoids. British Journal of Pharmacology (2003) 138, 845–854. doi:10.1038/sj.bjp.0705113

This report characterized one of the major cytochrome P450 isozyme involved in thiabendazole metabolism. This study was undertaken by using both cultured rabbit hepatocytes treated or not with drugs known to specifically induced various cytochromes P450 isoenzymes (i.e., P450 1A1/2 by beta-naphthoflavone, P450 2B4 by phenobarbital, P450 3A6 by rifampicine and P450 4A by clofibrate) and human liver (THLE-5) and bronchial (BEAS-2B) epithelial cells expressing or not the major constitutive human cytochromes P450 (i.e., CYP1A2, 2A6, 2B6, 2C9, 2D6, 2E1 or 3A4). Only hepatocytes exposed to beta-naphthoflavone and clofibrate significantly metabolized thiabendazole to 5-hydroxythiabendazole. Extensive biotransformation of this anthelmintic only occurred in human cells expressing CYP1A2. Moreover, experiments performed on rabbit preparations showed good correlations between thiabendazole 5-hydroxylase activity and both ethoxyresorufin and methoxyresorufin O-dealkylase activities. Thus, CYP1A2 is a major isoenzyme involved in thiabendazole 5-hydroxylation.

Since 1995 more than 1000 cases of hantavirus pulmonary syndrome (HPS) were reported in Argentina, a severe disease and often fatal to humans. Most cases were associated with Andes virus (AND) that caused few events of person-to-person transmission. Several lineages of pathogenic AND viruses have been described, including AND South, hosted by the rodent Oligoryzomys longicaudatus which affects the Patagonian region of Argentina and Chile. We studied the clinical and epidemiological characteristics of a HPS case. The objective was to describe the clinical presentation of the case, its epidemiology, the likely site of infection, the viral variant implicated and its relationship with the closest reported cases. We carried out the clinical follow up, serological and molecular diagnosis and the epidemiological research, including a rodent reservoir study. The clinical presentation of the case was the classical and moderate, caused by AND South virus. Its viral nucleotide sequence was compared with cases from Southern Argentina and Chile. This case was found to be the most Southern (48 degrees 46' 1.2'' S; 70 degrees 15' O) case reported and involved a new Argentinean province.

Kaddouri, M., Larrieu, G., Eeckhoutte, C. & Galtier, P. The development of drug-metabolizing enzymes in female sheep livers. J. vet. Pharmacol. Therap. 13, 340–349. The purpose of this investigation was to determine age-related changes of some hepatic drug-metabolizing activities in Lacaune ewes in the foetal, neonatal (1 and 4 weeks), growing (7 months), pregnant (11 months) and adult (6 years) stages. Although microsomal cytochrome P-450 was not detected in 3-month-old foetuses, it increased regularly from 1-week-to 11-month-old animals. Among mixed-function oxidases, the development of aminopyrine and ethylmorphine N-demethylases, benzo(α)pyrene hydroxylase and ethoxycoumarin O-deethylase were correlated to that of total cytochrome P-450. Due to their presence in foetal liver or their more rapid evolution, cytochrome b5, NADPH cytochrone c reductase, aniline hydroxylase, benzphetamine N-demethylase and erythromycin N-demethylase did not parallel the ontogenesis of cytochrome P-450. Hepatic transferases showed different developmental patterns from mono-oxygenases, so UDP glucuronyltransferase was detected in the foetus, reached maximum activity in all young ages up to the pregnant stage and subsequently fell in adult ewes. Concerning glutathione S-transferase accepting l-chloro-2,4-dinitrobenzene as substrate, similar values were obtained in the foetus and all young animals, whereas five-to tenfold higher values were obtained in both pregnant and adult female sheep. N-acetyltransferase using sulphamethazine did not significantly change from foetuses to adults but there were large differences in the capacity of hepatic acetylation between animals belonging to the same group. P. Galtier, Laboratoire de Pharmacologie-Toxicologie, INRA, 180 chemin de Tournefeuille, BP 3, 31931 Toulouse, France.

Moxidectin is an antiparasitic drug widely used in cattle, sheep and companion animals. Due to the involvement of P-glycoprotein (P-gp) and cytochrome P450 3A in the metabolism of moxidectin, we studied the influence of various P-gp interfering agents (ivermectin, quercetin and ketoconazole) on the metabolism of 14C moxidectin in cultured rat hepatocytes over 72 h. This in vitro study allowed selection of compounds which are able to increase the moxidectin bioavailability in lambs. From this, the modulation of moxidectin pharmacokinetics in plasma of lambs was studied after co-administration of 0.2 mg kg(-1) moxidectin (subcutaneously (SC)) and 0.2 mg kg(-1) ivermectin (SC), or 10 mg kg(-1) quercetin (SC), or 10 mg kg(-1) ketoconazole (orally). Ivermectin and quercetin increased significantly the quantity of 14C moxidectin in the rat hepatocytes. Ketoconazole co-administration led to a higher concentration of moxidectin in the rat hepatocytes. In vivo, only quercetin was able to modify the pharmacokinetics of moxidectin in plasma of lambs by increasing significantly the area under the plasma concentration-time curve. This study allowed the use of a natural agent, quercetin, to improve the bioavailability of moxidectin.

The activity and expression of cytochromes P450 were determined in liver, kidneys, lungs, duodenum, jejunum, ileum, and caecum of adult Lacaune sheep. High expression of total P450, benzphetamine and erythromycin demethylase activities, and P450 2B isoforms, as two distinct proteins that were detected and called P4502 Bm and P4502 Bx, was found in the lungs (in addition to liver). By contrast, the P450 3A subfamily was only expressed in liver and duodenal mucosa of untreated sheep. Phenobarbital (PB) treatment led to significant increases in all measured hepatic parameters and in total P450 of each investigated organ with the exception of ileum and caecum. Benzphetamine demethylase activity increased in liver and kidneys, correlating with the expression of the two P450 2B proteins, which were also induced in duodenum and ileum. By contrast, benzphetamine demethylase activity and expression of the P450 2B isoforms in lungs were unchanged by PB treatment. Erythromycin demethylation activity and P450 3A subfamily expression was increased only in liver of PB-treated sheep.

Moxidectin (MOX) is an antiparasitic drug widely used in cattle, sheep and companion animals. As a result of the implication of cytochrome P450 3 A in the metabolism of MOX and the role of competitor substrates of P-glycoprotein (Pgp) in modification of the bioavailability of endectocides, we studied the influence of verapamil (a multidrug-resistance reversing agent) on the metabolism of 14C moxidectin in cultured rat hepatocytes over 72 h. The metabolism of MOX remained low: 10.79 +/- 1.99% of the total 14C moxidectin for the main detected metabolite in verapamil-treated cells and 7.17 +/- 0.74% for the control cells after 24 h. The main detected metabolite in rat hepatocytes was the same as that detected in rat hepatic microsomes (the C29 monohydroxymethyl metabolite). Verapamil increased the quantity of MOX in the cells after 24, 48 and 72 h. Examination of the Area Under the concentration time Curve (AUC) of the main detected metabolite revealed a significant increase in the exposure of cells to MOX after verapamil treatment throughout the experiment. It is hypothesized that verapamil interfered with MOX as a substrate for Pgp during the initial incubation period. After this initial interaction, verapamil metabolites were able to interfere with Pgp. This experiment demonstrated the implication of Pgp in the transport of MOX and allowed prediction of the drug-drug interactions which might modify the bioavailability of endectocides.

The activity and expression of cytochromes P450 were determined in liver, kidneys, lungs, duodenum, jejunum, ileum, and caecum of adult Lacaune sheep. High expression of total P450, benzphetamine and erythromycin demethylase activities, and P450 2B isoforms, as two distinct proteins that were detected and called P4502 Bm and P4502 Bx, was found in the lungs (in addition to liver). By contrast, the P450 3A subfamily was only expressed in liver and duodenal mucosa of untreated sheep. Phenobarbital (PB) treatment led to significant increases in all measured hepatic parameters and in total P450 of each investigated organ with the exception of ileum and caecum. Benzphetamine demethylase activity increased in liver and kidneys, correlating with the expression of the two P450 2B proteins, which were also induced in duodenum and ileum. By contrast, benzphetamine demethylase activity and expression of the P450 2B isoforms in lungs were unchanged by PB treatment. Erythromycin demethylation activity and P450 3A subfamily expression was increased only in liver of PB-treated sheep.Key words: phenobarbital, sheep, cytochromes P450, inducibility, tissue distribution.

Thiabendazole (TBZ), an anthelmintic and fungicide benzimidazole, was recently demonstrated to be extensively metabolized by cytochrome P450 (CYP) 1A2 in man and rabbit, yielding 5-hydroxythiabendazole (5OH-TBZ), the major metabolite furtherly conjugated, and two minor unidentified metabolites (M1 and M2). In this study, exposure of rabbit and human cells to 14C-TBZ was also shown to be associated with the appearance of radioactivity irreversibly bound to proteins. The nature of CYP isoforms involved in this covalent binding was investigated by using cultured rabbit hepatocytes treated or not with various CYP inducers (CYP1A1/2 by β-naphthoflavone, CYP2B4 by phenobarbital, CYP3A6 by rifampicine, CYP4A by clofibrate) and human liver and bronchial CYP-expressing cells. The covalent binding to proteins was particularly increased in β-naphthoflavone-treated rabbit cells (2- to 4-fold over control) and human cells expressing CYP1A2 (22- to 42-fold over control). Thus, CYP1A2 is a major isoenzyme involved in the formation of TBZ-derived residues bound to protein. Furthermore, according to the good correlation between covalent binding and M1 or 5OH-TBZ production, TBZ would be firstly metabolized to 5OH-TBZ and subsequently converted to a chemically reactive metabolic intermediate binding to proteins. This metabolic activation could take place preferentially in liver and lung, the main biotransformation organs, rather than in intestines where TBZ was shown to be not metabolized. Moreover, TBZ was rapidly transported by passive diffusion through the human intestinal cells by comparison with the protein-bound residues which were not able to cross the intestinal barrier. Consequently, the absence of toxicity measured in intestines could be related to the low degree of TBZ metabolism and the lack of absorption of protein adducts. Nevertheless, caution is necessary in the use of TBZ concurrently with other drugs able to regulate CYP1A2, particularly in respect to liver and lung tissues, recognised as sites of covalent-binding.

Although numerous studies report hepatic drug metabolizing enzyme alterations during aflatoxicosis, the mechanisms involved in P450 decreases remain to be established. The purpose of this work is to investigate whether increased oxidative damage revealed by the detection of malondialdehyde (MDA), lipofuscin substances, and conjugated dienes in microsomes, could explain the decreased P450 content. Studies were conducted with two different doses of aflatoxin B1 (AFB1), both in vivo in rabbits and ex vivo in primary cultures of rabbit hepatocytes, in the presence or absence of β-naphthoflavone or rifampicin used as respective P450 inducers. Strong negative correlations were observed between MDA and P450 contents, both in vivo and ex vivo, whereas rifampicin appears to protect the hepatocytes from oxidative damage but not AFB1 toxicity. Positive correlation were also obtained between MDA formation and lactate dehydrogenase (LDH), aspartate aminotransferase (ASAT) or alanine aminotransferase (ALAT) releases, used as non-specific markers of AFB1 toxicity. Taken together these results suggest that the dramatic decreases of cytochrome P450 observed in vivo during aflatoxicosis could be linked, at least in part, to microsomal oxidative damage.

Cultured rabbit hepatocytes were used to compare the relative activities of cytokines to inhibit the constitutive or rifampicin (RIF)-induced expression of the cytochrome P450 3A6 gene (CYP3A6). Human recombinant cytokines tested were interleukin-1beta (IL-1beta) (2 U/mL), interleukin-2 (IL-2) (5,000 U/mL) and interferon-gamma (IFN-gamma) (50 U/mL). Hepatocytes were cultured in the presence or absence of 25 microM RIF for 24 hr, with or without cytokines alone or in combination. All these cytokines inhibited RIF-induced P4503A6 expression without apparent cellular toxicity. By contrast, only IFN-gamma treatment provided a significant decrease (41%) in the constitutive P4503A6 protein level. Moreover, cytokines differed in their ability to repress RIF-dependent transcriptional induction of CYP3A6: IL-1beta and IL-2 were approximately equipotent, causing an almost 40-50% suppression of CYP3A6 mRNA and protein levels, whereas IFN-gamma exerted repressive effects only on P4503A6-related erythromycin N-demethylase activity and inducible protein expression. In fact, although strongly reducing P4503A6 protein content (an approximate 70% decrease), IFN-gamma did not exhibit any influence on CYP3A6 mRNAs with the exception of its association with interleukins. All these results suggest that IL-1beta and IL-2 mainly promote a transcriptional repression mechanism, given the absence of effect of these cytokines on the basal P4503A6 level, whereas IFN-gamma exerts a post-transcriptional suppressive action on both induced and constitutive P4503A6 expression. Consequently, P4503A6-dependent progesterone 6beta-hydroxylase activity also presented a cytokine-specific pattern of inhibition, with a much greater sensitivity than P4503A6 immunoreactive protein to IL-1beta and IL-2 + IFN-gamma treatments. Thus, this study underlines the significant impact of inflammation on steroid metabolism.

Cultured hepatocytes from rat, rabbit, calf, pig, and sheep were used to study metabolism and formation of protein-bound residues of thiabendazole ([(14)C]TBZ), a benzimidazole anthelmintic and fungicide. In all investigated species, major pathways corresponded to 5-hydroxylation of TBZ and its further conjugation. However, marked interspecies differences in rates of TBZ disappearance and 5-hydroxy metabolite formation were demonstrated. Rabbit hepatocytes presented the fastest TBZ biotransformation and were the most extensive hydroxylators. By contrast, the lowest capacity of oxidation was observed for the rat. Two unidentified minor metabolites, designated M1 and M2, were particularly produced by sheep hepatocytes. Moreover, the protein-bound residues in these cells, which could be related to cytochrome P450-dependent oxidation, were formed in 4 times greater amounts than in the other animal cells. These findings substantiate hepatocytes as an in vitro model for prediction of hepatic metabolism in vivo.

The effects of interleukin-1 beta, interleukin-2 and interferon-gamma and their combinations were investigated on induced cytochrome P 4501A of cultured rabbit hepatocytes considered 72 h after plating. Without apparent cellular toxicity, these cytokines provoke a significant decrease in TBZ- and BNF-induced P4501A1/ 2 expression. However specific patterns of action are revealed: IL-1 beta is the most potent cytokine in regard to CYP1A1/2 mRNA suppression whereas IL-2 exerts repressive effects only on P4501A1 induced expression. Although being a strong inhibitor of induced enzymatic activities and protein contents, IFN-gamma exhibits only a weak influence on CYP1A1/2 mRNAs with the exception of its association with interleukins. All these results suggest that IL-1 beta and IL-2 promote mainly transcriptional repression mechanism whereas IFN-gamma would stimulate a post-transcriptional suppressive pathway.

The expression of cytochrome P4501A1 and 1A2 was investigated in rabbit hepatocytes maintained in primary cultures for 96 hr in the absence or presence of 100 μ m of the benzimidazole anthelmintics oxfendazole or fenbendazole. Total cytochrome P-450, ethoxyresorufin O-deethylase and acetanilide hydroxylase activities were significantly increased in cell cultures receiving benzimidazoles. These increases were more marked after exposure of cultured hepatocytes to oxfendazole (OFZ) than to fenbendazole (FBZ). Western and Northern blot analysis of microsomes and RNA prepared from these cultures revealed increased levels of both protein and specific mRNA for P4501A1. The inhibition of these inductions in the presence of actinomycin D suggests a transcriptional way of activation of this gene. The ability of OFZ to bind to the Ah receptor has been examined. Data obtained from competition experiments with dioxin demonstrated that OFZ and other compounds in the benzimidazole series are not ligand of the Ah receptor. From saturation experiments and Scatchard plot analysis, rabbit hepatocyte Ah receptor (Kd = 10.6 n m ) seems to belong, as does the human Ah receptor, to a low-affinity category. Different induction rates obtained with several benzimidazole drugs suggest that the sulfur atom within the molecule is critical for CYP1A1 induction. The widely used benzimidazole anthelmintics OFZ and FBZ may exert an inducing effect through an original pathway that does not require a specific binding step to the Ah receptor.

The effect of sulfur-containing benzimidazoles (thiabendazole, 5-hydroxy-thiabendazole, cambendazole) and sulfur-free derivatives (benzimidazole, carbendazim and 5-hydroxycarbendazim) on cytochrome P450 enzymes was investigated in primary cultures of rabbit hepatocytes considered 72 h after plating. Thiabendazole, cambendazole and carbendazim led to a significant dose-dependent increase in both EROD activity and cytochrome P4501A1/2 proteins and mRNA expression. Experiments using actinomycin D strongly suggest that these compounds have a transcriptional control on both CYP1A1 and CYP1A2 genes in primary hepatocytes. Thiabendazole increased both COH activity and P4502A protein levels. We conclude that sulfur is not a prerequisite to the P450 induction potential of benzimidazoles, while 5-hydroxylation leads to inefficient metabolites in terms of inducibility.

The effects of chronic administration of aflatoxin B1 (AFB1) on liver drug metabolism enzymes were measured in New Zealand rabbits divided into three groups of 5 animals, each receiving over 5 days either arabic gum or AFB1 in arabic gum at a daily oral dose of 0.05 or 0.10 mg/kg. These treatments did not lead to any lethality in any of the treated groups, but the body weight gain was altered. Biochemical exploration of plasma components revealed a dose-dependent hepatotoxicity characterized by cytolysis and cholestasis. At 0.10 mg/kd/day of AFB1, significant decreases were observed in total liver microsomal cytochrome P450, several P450-dependent monooxygenase activities, all individual P450 isoenzymes levels analysed by Western-blotting and glutathione S-transferase activities. By contrast, at 0.05 mg/kg/day of AFB1, even though total cytochrome P450 was decreased by 30%, only P450 1A1 and 3A6 isoenzymes, and aniline hydroxylation, pentoxyresorufin O-depentylation, aminopyrine, erythromycin, ethylmorphine and dimethylnitrosamine N-demethylations were affected. In the same animal group, the only glutathione S-transferase accepting CDNB (1-chloro-2,4-dinitrobenzene) as substrate was decreased by 22%. UDP-glucuronyltransferase accepting p-nitrophenol as substrate was increased in both groups of animals (33-62%). The mechanisms that could contribute to the observed changes in drug metabolizing enzymes are discussed.

The effect of TBZ (30-100 microM) was investigated on cytochromes P450 of cultured rabbit hepatocytes considered 72 h after plating. At the highest concentrations and without apparent cellular toxicity, the drug provokes a dose-dependent increase in total microsomal cytochrome P450 and a rise in EROD activity which was correlated to a specific increase in P4501A1 level. Northern blot analysis of RNA reveals an increased level of mRNA specific to P4501A1. The transcriptional activation of this isoenzyme is proposed because of the significant inhibition of the above-mentioned increases when actinomycin was added to the culture medium. Data obtained from competition experiments demonstrate that TBZ is not a ligand of Ah receptor. A down-regulation process could explain the slight decrease in both ANOH and P4502E1 level observed in hepatocytes treated with the highest dose of TBZ.

The comparative distribution of p-nitrophenol UDP-glucuronosyl-transferase, 1-chloro-2,4-dinitrobenzene glutathione-S-transferase and sulphamethazine N-acetyltransferase activities was studied along the gastrointestinal mucosa of female Lacaune sheep. Gastrointestinal mucosa was characterized by a very low and unequal N-acetyltransferase activity when activities were expressed per g of wet organ. The duodenum contained highest activities (4.1 nmol/g min). When results were expressed per mg of cytosolic protein, the duodenal activity (0.64 nmol/mg min) was sixfold higher than in liver (0.11 nmol/mg min). There was a lack in N-acetyltransferase activity accepting isoniazid as substrate. Glucuronosyltransferase activity was approximately threefold higher in microsomal fractions of the mucosal lining of gastric and colonic intestine (0.43-0.58 nmol/g min) than in small intestine or caecum (0.10-0.26 nmol/mg min). Concerning cytosolic glutathione S-transferase activity, two- to threefold higher activities were obtained in omasum, jejunum, duodenum and ileum (1021-2164 nmol/g min) than in other parts (341-799 nmol/g min) when results were expressed per g of wet organ. These data were compared with corresponding hepatic activities determined in the same six female sheep.

1. The comparative activity of hepatic cytochrome P-450 monooxygenase system, glucuronyltransferase, glutathione S-transferase and N-acetyltransferase was studied in three-month-old male and female Lacaune lambs and male Saanen kids. 2. The study of mixed-function oxidase components showed that total cytoehromc P-450 ranged from 0.54 in kids to 0.85–0.88 nmol/mg−1 in lambs. Male lambs had higher levels than kids (122–165%) for aminopyrine, benzphetamine, ethylmorphine and erythromycin demethylases or benzo(a)pyrene hydroxylase whereas NADPH-cytochrome c reductase was 1.19-fold lower in lambs. 3. Sex-related changes were observed in lambs in case of microsomal benzo(a)pyrene hydroxylase activity which appeared 1.31-fold more potent in male liver. Cytosolic N-acetyltransferase accepting sulfamethazine as substrate was about 8-fold higher in female than in male lambs. 4. The analysis of samples from various liver lobes, indicated the heterogenous distribution of micro- somal proteins which is related to higher concentrations of both cytochrome b5, NADPH-cytochrome c reductase and p-nitrophenol glucuronyltransferase in left lobes.

Bioavailability and activity of ampicillin were evaluated in the pig after preventive and curative doses by using small filter membrane bags containing strains of Escherichia coli placed into the caecum. A peak concentration of 720 μg ampicillin per ml was obtained in caecal liquor which was effective against E coli K82 and E coli 127 in the bags, in pigs orally administered with 20 mg/kg of the drug. After intramuscular injection of ampicillin with 40 mg/kg, the peak concentration in caecum reached 15 μg/ml but no activity against the strains of E coli K82 and 127 was recorded.

Observations were made for two consecutive days on the disposition of oxytetracycline, chloramphenicol, neomycin and gentamicin through the digestive tract of pigs given an oral drench. The effect of these antibiotics upon the colibacilli flora and upon an Escherichia coli 127 strain in small filter membrane bags placed into the caecum was also investigated. For chloramphenicol, inactivation by antibiotic resistant colibacilli and, for neomycin, losses of activity by digestive content may explain the lower concentrations obtained in the gut and the correlative lack of curative or preventive action against E coli 127 in small bags. Tetracycline and gentamicin prevented growth of E coli 127 from the second day.

Adult male rats were sorted into control and infected groups, the latter receiving an oral dose of 20 metacercariae of Fasciola hepatica. In Weeks 3 and 6 after infection, some rats received phenobarbital or 3-methylcholanthrene which induced drug metabolizing enzymes. The parasitic pathology was ascertained by clinical observation of the rats and at autopsy. Hepatic microsomal cytochrome P-450 content was significantly decreased in infected rats compared to untreated phenobarbital treated groups. In all infected rats, the simultaneous increase in cytosolic calcium and decrease in cytosolic glutathione corresponded to oxidative cell injury occurring in the course of fascioliasis. Both arylamine acetyltransferase (EC 2.3.1.5.) and glutathione transferase (EC 2.5.1.18) activities were decreased in all newly infected and 6 week infected groups. Fascioliasis did not alter the substrate related uridine diphosphate glucuronosyltransferase activities (EC 2.4.1.17) of any rat group.

Mycotoxicosis has been produced in the rat by daily oral administrations of ochratoxin A (1.5 mg/kg/day) or aflatoxin B1 (1 mg/kg/day). Hepatic microsomal cytochrome P-450 and b5 contents and many phase I and II biotransformation systems have been measured in the course of ochratoxicosis (4 to 15 dosings) and aflatoxicosis (1 to 8 dosings). In case of ochratoxicosis, decreases in cytochrome P-450 level, aminopyrine demethylase and aniline hydroxylase activities were observed in rats receiving 15 administrations of the toxin. Aflatoxicosis induced more severe decreases in cytochrome P-450, aminopyrine demethylase and ethoxycoumarin deethylase following 8 daily gavages. In the two studies, there was no significant change in activities of liver phase II biotransformation enzymes.

Adult, male rats were infected with 20 metacercariae of Fasciola hepatica given orally, other rats were left untreated. Five weeks after infestation, some animals received phenobarbitone, 3-methylcholanthrene, β-naphthoflavone or Arochlor 1254, to induce liver drug metabolizing enzymes. Fascioliasis provoked decreases in aminopyrine N-demethylase, aniline hydroxylase, the mutagenic activity of cyclophosphamide and cytochrome P-450 concentration in untreated or phenobarbitone or Arochlor pretreated rats. In contrast, cytochrome b5, NADPH cytochrome c reductase, ethyoxycoumarin O-deethylase and the enzymatic activation of ethidium bromide were not affected by fascioliasis whatever pretreatment was given. Fascioliasis decreased liver drug metabolizing enzymes which were specifically induced by both phenobarbitone and Arochlor, this could be due to either the specific action of toxic excretions of flukes or to the particular localization of tissue damage within the liver lobule.

[7-3H]Tetracycline and [carbonyl-14C]rafoxanide were injected intravenously into anesthetized controls and rats in which experimental fascioliasis had been induced by 20 Fasciola hepatica metacercariae. The biliary excretion (1 and 3 h, respectively) of the radioactivity consisted of approximately 4% of the administered dose. In 4-week infested rats, biliary excretion of [3H]tetracycline and hepatic levels of radioactivity were decreased, whereas bile flow did not vary and plasma clearance of the antibiotic was significantly decreased in comparison with control animals. These differences could be the result of the fascioliasis-induced decrease in the hepatic uptake of tetracycline and the limited active transport for its output into bile canaliculi. No change in [14C]rafoxanide disposition was shown in infested rats.

The growth of Byssochlamys nivea and P. granulatum was reduced by ochratoxin A (1 ppm, 10 ppm), whereas Aspergillus ochraceus growth and toxinogenesis were not affected by 1 and 10 ppm of patulin. When Penicillium granulatum and Asperigillus ochraceus were placed in the same medium the former grew and produced its toxin and ochratoxin production by the latter was weakened. Since patulin and ochratoxin can be found in the same substrate; the toxinogenic significance of in vitro strains is questionned.

Ampicillin administered to rabbits (20 mg/kg per day) over a period of three days subsequently provoked a death rate of 40%. No deaths were observed after treatment with gentamycin (10 mg/kg per day) or with a combination of ampicillin and gentamycin. On the fourth day weight loss in the three treated groups was 12%, 11% and 9%, respectively, compared to controls. At the same time food intake in the treated groups was only 15% to 20% of the amount consumed by controls. In the caecum, ampicillin treatment resulted in dominance of a strain of Enterobacter aerogenes. Gentamycin had no effect on bacterial flora, although in combination with ampicillin, the number of caecal bacteria (aerobic and anaerobic) was reduced. Flora modification might be responsible for accumulation of NH3 and an unbalance of free acids. Caecotrophy was inhibited by administration of ampicillin. When administered intramuscularly, ampicillin produced results comparable with those obtained orally, although gentamycin was ineffective.

In order to assess drug renal kinetics in vivo, the two kidneys of seven ewes were surgically placed under the skin. Through the use of renal function tests and a series of biopsies, we found that the kidneys remained normal in their subcutaneous location. Gentamicin renal kinetics were evaluated in conscious animals by a series of biopsies. Histological controls showed only slight lesions due to biopsy; based upon plasma hydrocortisone concentration, there was no indication of chronic stress affecting the renal pharmacokinetics. We suggest that this model has great potential as a method for studying in vivo the kinetics of drug disposition in the renal tissue and assessing the residue level of a drug.

Minocycline administered to rabbits per os or intramuscularly (30 mg/kg) over a period of three days led neither to digestive problems nor mortality. Administration per os left the growth curve unchanged. Intramuscular administration reduced rate of growth, and on the 15th day weight loss compared to controls was 3.2% or 11.7% depending on whether the place of administration was in the back muscles or in the thigh, and this despite a normal food intake. Minocycline did not modify microbial flora and level of ammonia in the caecum. Level of acetic acid was reduced by 50% on the fourth and 15th day after intramuscular administration of minocycline into the thigh. The depressive effect of minocycline on growth remains unexplained.

Intramuscular injection of bromhexin (Quentan) results in increased bioavailability of spiramycin in nasal secretions. In the presence of a mucolytic agent, the area under the curve calculated according to spiramycin concentrations found in nasal secretions increases by 6%, 41% and 32% respectively in the course of three days of treatment. This potentiation reveals the interest involved in administering a combination of bromhexine and antibiotics in the treatment of infectious diseases of the respiratory tract.

The purpose of this investigation was to determine the effects of a subclinical fascioliasis at various stages of its development (by week--4, 8, 12, and 16 weeks after the infestation by an oral administration of 150 metacercariae of Fasciola hepatica) on the activity of some hepatic drug-metabolizing systems in lamb. The parasitic pathology was ascertained at autopsy and by clinical observation of animals. Hepatic microsomal cytochrome P-450 content was significantly decreased (by 9-22%) in all infected groups of animals. In early stages of the parasitic disease, decreases in cytochrome b5 content (10-18%) and ethoxycoumarin O-deethylase (25%) were observed, whereas aminopyrine N-demethylase, benzphetamine N-demethylase, and aniline hydroxylase were significantly lowered by 8 to 16 weeks postinfection. Among investigated transferases, glutathione transferase was only decreased (28%) in animals killed 16 weeks after the infestation; in these animals a significant increase in microsomal gamma-glutamyltransferase was observed, probably related to the elevated plasma activity of this enzyme. By 8 weeks postinfection, a simultaneous increase in cytosolic calcium (38%) and decrease in cytosolic glutathione (22%) would correspond to an oxidative cell injury occurring in the course of fascioliasis. The consequences of the fascioliasis-induced decreases in liver-oxidative and conjugative liver drug metabolism are discussed.

Bioavailability of erythromycin and colistin was studied in plasma, ruminal liquid and nasal mucus after simultaneous injection by intraruminal or intramuscular route. After intramuscular injection, erythromycin was found in plasma and respiratory tract, colistin in plasma. After oral administration, only erythromycin was found in nasal cavity secretions but nitrogen metabolism and volatile fatty acid production were modified in rumen.

Observations were made for two consecutive days on the disposition of oxytetracycline, chloramphenicol, neomycin and gentamicin through the digestive tract of pigs given an oral drench. The effect of these antibiotics upon the colibacilli flora and upon an Escherichia coli 127 strain in small filter membrane bags placed into the caecum was also investigated. For chloramphenicol, inactivation by antibiotic resistant colibacilli and, for neomycin, losses of activity by digestive content may explain the lower concentrations obtained in the gut and the correlative lack of curative or preventive action against E coli 127 in small bags. Tetracycline and gentamicin prevented growth of E coli 127 from the second day.

The effects of T-2 toxin and diacetoxyscirpenol on tissue drug-metabolizing enzymes in young male rats were compared. Mycotoxicoses were produced by daily oral administration of toxins at 1.0 mg/kg body weight for 1, 4 or 8 days. Many hepatic, renal and pulmonary oxidative and conjugative enzymes were measured in animals killed 24 hr following the last administration. The effects of the two trichothecene mycotoxins were generally similar. In liver the decrease in microsomal and cytosolic proteins paralleled the decline in total plasma proteins or the increase in plasma GOT activity. Hepatic microsomal cytochrome P-450 decreased in rats receiving trichothecenes for 8 days. This effect was more marked when aminopyrine, benzphetamine, ethylmorphine and ethoxycoumarin dealkylations or aniline and benzopyrene hydroxylations were measured. p-nitrophenol glucuronyltransferase activity was enhanced in animals receiving at least one administration of trichothecenes, whereas there was no change in conjugation to glutathione or acetate. In other tissues, there was no change in any renal enzymes whereas a significant rise in pulmonary monooxygenase was observed in T-2 toxin administered to rats for 4 or 8 days.

1. The comparative distribution of cytochrome P-450 monooxygenase system, glucuronyltransferase, glutathione S-transferase and N-acetyltransferase was studied in the liver, lung and kidney of young male sheep. 2. The sheep liver was characterized by a lack in glutathione S-transferase activity with isoniazid as substrate. 3. The oxidative drug metabolizing enzymes of lung were generally close to those of liver; benzphetamine N-demethylase and ethoxycoumarin O-deethylase were even found to be higher in lung (213 and 148%, respectively). 4. Pulmonary conjugative and both renal oxidative and conjugative systems accounted only for 9-38% of hepatic corresponding enzymes. 5. The enzyme determination in various sampling sites of the three organs, demonstrated the homogeneous distribution of all investigated monooxygenases and transferases in liver, lung and kidney of sheep.

0,1 and 1,9 p. 100 of French corn samples harvested in 1973 and 1974 contain respectively 4 to 42 ppb aflatoxin and 15 to 200 ppb ochratoxin A. Because the dilution of this product in the feed, such amounts could not be considered causing acute or chronic mycotoxicosis. In case of corn contamination by ochratoxin A, the analysis of technologic parameters conclude to question the drying corn with ears in cribs and the delayed drying after the reception of corn in storage corporation.