Tumorigenicity by human papillomavirus type 16 E6 and E7 in transgenic mice correlates with alterations in epithelial cell growth and differentiation

The human papillomavirus type 16 (HPV-16) E6 and E7 oncogenes are thought to play a role in the development of most human cervical cancers. These E6 and E7 oncoproteins affect cell growth control at least in part through their association with and inactivation of the cellular tumor suppressor gene products, p53 and Rb. To study the biological activities of the HPV-16 E6 and E7 genes in epithelial cells in vivo, transgenic mice were generated in which expression of E6 and E7 was targeted to the ocular lens. Expression of the transgenes correlated with bilateral microphthalmia and cataracts (100% penetrance) resulting from an efficient impairment of lens fiber cell differentiation and coincident induction of cell proliferation. Lens tumors formed in 40% of adult mice from the mouse lineage with the highest level of E6 and E7 expression. Additionally, when lens cells from neonatal transgenic animals were placed in tissue culture, immortalized cell populations grew out and acquired a tumorigenic phenotype with continuous passage. These observations indicate that genetic changes in addition to the transgenes are likely necessary for tumor formation. These transgenic mice and cell lines provide the basis for further studies into the mechanism of action of E6 and E7 in eliciting the observed pathology and into the genetic alterations required for HPV-16-associated tumor progression.

Interleukin-1 beta differentially represses drug-metabolizing enzymes in arthritic female rats

Experimental arthritis and inflammation have been reported to reduce liver cytochrome P-450-dependent mono-oxygenase activities with subsequent impairment of drug metabolism. Interleukin-1 beta (IL-1) is among the proven mediators of both inflammation and P-450 decrease, although some paradoxical effects were sometimes reported in experimental models of arthritis. The aim of the present study was to evaluate the main liver drug-metabolizing isoenzymes during established collagen-induced arthritis in rats, and to investigate whether a systemic IL-1 treatment was able to mimic or sometimes to reverse the influence of the inflammatory process on these enzymes. Arthritis was induced on day 0 by type II collagen and a low dose (0.2 mg) of N-acetylmuramyl-L-alanyl-D-isoglutamine, and human recombinant IL-1 was administered s.c. at the daily dose of 0.02, 0.2 or 2.0 micrograms per arthritic rat, from day 21 to 25 and on day 28. Ethoxyresorufin-O-deethylation was depressed 6-fold in arthritic rat liver microsomes and the highest dosage of IL-1 potentiated this depression. Pentoxyresorufin-O-deethylation decreased by 50% in arthritic rat, a dose-dependent decrease being observed after IL-1 treatment. Progesterone 6 beta-hydroxylation and P-450 IIIA protein increased by 2-fold in both untreated arthritic rat liver microsomes and those treated by the lowest dose of IL-1. The two higher doses decreased this activity, vs. the dose, to reach the naive level. Lauric acid hydroxylation increased 2-fold in arthritic rat and was further potentiated by IL-1. UDP glucuronosyl transferase IA2 activity was increased 2-fold in arthritic rats, with subsequent decrease after 2.0 micrograms of IL-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucuronidation of 3'-azido-3'-deoxythymidine in human liver microsomes: enzyme inhibition by drugs and steroid hormones

The molecular form of UDP-glucuronosyltransferase involved in the catalysis of 3'-azido-3'-deoxythymidine (AZT)-5'-O-glucuronide was characterized in human liver microsomes. The specific activity (1.3 nmol/min per mg protein) in transplantable liver was more than 2-times higher than in post-mortem fragments. Liver microsomes from patients suffering Crigler-Najjar syndrome, who are genetically deficient in bilirubin UDP-glucuronosyltransferase, could also glucuronidate AZT to a similar extent, thus indicating that this protein was not involved in that process. A genetically engineered V79 cell line stably expressing a cDNA which encodes a human isozyme active towards 1-naphthol was unable to glucuronidate AZT. Clinically used drugs, most of them being glucuronidated, were tested as potential inhibitors of the glucuronidation of AZT in human liver microsomes. The drugs chemically related to 2-phenylpropionic acid, naproxen and flurbiprofen, and the steroid compounds testosterone, estrone and ethynylestradiol strongly inhibited AZT glucuronidation. Codeine and morphine also decreased the reaction rate although to a lower extent. Except estrone which elicited a partial competitive inhibition, ethynylestradiol, flurbiprofen naproxen and testosterone could competitively inhibit AZT glucuronidation with an apparent Ki of 38, 50, 172 and 250 microM, respectively. The results suggest that these drugs were substrates of the same isozyme(s) involved in AZT glucuronidation. Probenecid was a weak inhibitor of the reaction (Ki 900 microM), only when non-disrupted microsomes were used. This drug may compete with the anion carrier system involved in the microsomal uptake of UDP-glucuronic acid.

Induction of a mucosal barrier to bovine herpesvirus 1 replication in cattle

Current vaccines for human and animal herpesviruses engender an immunity that may ameliorate disease but generally fails to prevent infection, latency, reactivation from latency, or spread through a population. By administering intranasally to cattle bovine herpesvirus type 1 virion envelope proteins combined with the potent mucosal immune system adjuvant, cholera toxin B subunit, we engendered a local antibody response that acted as a barrier to infection of mucosal epithelial cells and thereby prevented viral replication, consequently precluding disease, latency, and spread.

Addition of enemas to oral lavage preparation for colonoscopy is not necessary

To evaluate whether the addition of enemas to oral electrolyte lavage is helpful for colonoscopic preparation, we conducted a prospective, randomized, observer-blinded trial to compare oral lavage plus enemas with oral lavage alone. The quality of preparation, mucosal visualization, and the volume of retained colonic fluid did not differ between the two groups. Twenty-two percent of the patients in the group who received oral lavage plus enemas compared with 12% of the patients in the group that only received oral lavage stated that they would refuse to repeat the preparation for future colonoscopic examination. Seventeen percent of the patients in the group that received oral lavage plus enemas demonstrated anorectal trauma or inflammation compared with only 5% in the group that received oral lavage alone (p = 0.09). These results indicate that the addition of enemas to oral lavage preparation for colonoscopic evaluation cannot be routinely recommended. However, enemas may be considered on an individual basis in the occasional patient unable to consume the complete oral lavage or in whom residual stool is found during colonoscopic evaluation after oral lavage preparation.

In vitro N-glucuronidation of a novel antiepileptic drug, lamotrigine, by human liver microsomes

The metabolism of the antiepileptic drug lamotrigine was characterized in human liver microsomes. For that purpose a high performance liquid chromatography method allowing the separation of lamotrigine glucuronide from the parent compound, and the quantitation of the glucuronide, was developed. The drug undergoes glucuronidation on the 2-nitrogen atom of the triazine ring, leading to a quaternary ammonium-linked glucuronide. This metabolite was positively identified from its hydrolysis by beta-glucuronidase and its associated radioactivity when UDP-[U-14C] glucuronic acid was used as the cosubstrate. Structural confirmation of the glucuronide was finally obtained by high performance liquid chromatography-mass spectrometry, by using a thermospray interface. The reaction proceeded with an apparent Vmax of 0.65 nmol/min/mg and Km of 2.56 mM. The average value of lamotrigine glucuronidation in four human samples of transplantable liver was 0.43 +/- 0.14 nmol/min/mg, thus indicating a large interindividual variation. An interspecies comparison of hepatic lamotrigine glucuronidation (human, rabbit, rat, monkey) revealed that the rate of glucuronidation was low. Of all the species considered, humans glucuronidated the drug to the greatest extent, with a specific activity 2-fold higher than that observed in rabbit liver microsomes. In contrast, the activity was greater than 20 times lower in monkey (0.019 nmol/min/mg) and at the limit of detection in rat liver microsomes. However, in this species, phenobarbital treatment enhanced lamotrigine glucuronidation slightly (0.017 nmol/min/mg). Among the drugs that undergo quaternary ammonium-linked glucuronidation, chlorpromazine, but not imipramine, amitriptyline and cyproheptadine, inhibited the glucuronidation of lamotrigine in vitro (IC50 of 5.0 x 10(-4) M).(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of novel phencyclidine metabolites formed in vitro by rabbit microsomal metabolism

1. Phencyclidine (PCP) was incubated with rabbit liver and brain microsomal fractions, and the structures of metabolites formed by oxidation determined by g.l.c.-mass spectrometry. 2. The formation of several known mono- and di-hydroxylated metabolites, as well as two new metabolites, was seen in the liver preparations. 3. Hydroxylated PCP metabolites were also formed after incubation of PCP with brain microsomes, indicating that PCP biotransformation may occur in the brain itself.

Effects of RP 52028 and phenobarbital on mRNA levels of inducible and constitutive sex-specific cytochrome P450 isozymes in rat liver

Sex-related differences in basal levels of mRNA coding for various cytochrome P450 isozymes and their inducibility by 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3- isoquinoline carboxamide (RP 52028) in comparison to phenobarbital (PB) were investigated in Sprague-Dawley rats. We observed that the inducible isozymes, namely cytochromes P450IIB1/2 and P450IIIA1/2 were barely detectable in non-induced animal livers. On the contrary, mRNAs coding for two constitutive forms of cytochrome, P450IIC7 and IIC11, were expressed at a high level in untreated rats in a sex-dependent manner. Cytochrome P450IIC11 mRNA was present in male rats only whereas P450IIC7 was expressed in both sexes but at a higher level in female rats. RP 52028 had a dose-dependent inducing effect on the P450IIB1/2 and IIIA1/2 isoforms in both sexes. After administration of a high dose (500 mg/kg), this molecule exhibited a pattern of induction similar to that of PB. Increases in the accumulation of these IIB1/2 and IIIA1/2 messengers were correlated with protein data, suggesting that RP 52028, like PB, induces these isozymes mainly through a pretranslational regulatory mechanism. On the other hand, PB and RP 52028 caused only a slight increase, less pronounced than in Wistar rats, in the mRNA level of the constitutive female-predominant P450IIC7, indicating a strain-related difference in inducibility of this isozyme. RP 52028 had no effect on P450IIC11 mRNA level in male rat liver, in contrast to the decreasing effect obtained with PB. Furthermore, the non-correlated changes in P450IIC11 mRNA level and microsomal testosterone 2 alpha-hydroxylase activity after treatment with RP suggests that this molecule modulates the expression of P450IIC11 at a posttranscriptional level only.

Zinc protoporphyrin as an indicator of lead exposure: precision of zinc protoporphyrin measurements

In lead-exposed workers many factors affect the relationship between the levels of lead and of zinc protoporphyrin (ZPP) in blood. When the zinc protoporphyrin level is used to assess the lead in the blood level, the analytical accuracy of the ZPP and the PbB determinations should be known. Also the variability of lead exposure over time is an important parameter of this assessment. The absolute and relative precision of ZPP measurements with two brands of ZPP meters (AVIV and ESA) were compared. The absolute precision of the ZPP measurements is not constant for the AVIV meter, but is constant for the ESA meter. The relative precision for both brands of meters decreases with increasing ZPP levels. Between the AVIV and the ESA meters, a significant difference in response, irrespective of the kind of anticoagulant used, was observed. The regression equations between PbB and ZPP levels were studied. Different factors can affect the relationship between PbB and ZPP, e.g. variability in lead exposure, the time-lag between the increase of PbB and ZPP, and the precision and accuracy of PbB and ZPP measurements.

Renal function of workers with low-level cadmium exposure

The influence of occupational exposure to cadmium on renal function was examined in 27 male cadmium workers from plants with second-degree usage of cadmium. The levels of cadmium in the blood and urine and various protein concentrations in the urine and serum were determined. The urinary levels of beta 2-microglobulin, retinol-binding protein, and N-acetyl-beta-D-glucosaminidase were statistically significantly increased in workers with urinary cadmium levels above 50 nmol/l. SDS-PAGE electrophoresis with silver staining is probably a sensitive indicator of the early effects of cadmium on protein excretion. The currently recommended biological exposure limits may have to be lowered.

Influence of occupational low-level lead exposure on renal parameters

The influence of lead exposure on renal function was examined. In 155 lead workers and 126 control workers, lead in blood (PbB) and zinc protoporphyrin in blood (ZPP) were measured as indicators of exposure to lead; various proteins in urine were measured as parameters of renal functions. Regression and matched-pair analyses suggest that tubular parameters may be more influenced by lead exposure than glomerular parameters. Changes in renal function parameters may already occur at PbB levels below 3 mumol/liter (600 micrograms/liter). The excretion of N-acetyl-beta-D-glucosaminidase appears to be the most consistent and sensitive parameter of an early effect on the tubular function.

[Influence of anaerobiosis on the sterol composition of Mucor hiemalis]

Strict anaerobic cultures of Mucor hiemalis lead to major modifications of the quantitative and qualitative composition of sterols. Sterols of which the lateral chain contains an ethyl or ethylidene group in C24 are for the first time brought to evidence in a Mucorales. Isolation in the same conditions of E-ethylidene-24 (28) lanostene-8 ol-3 beta lets us suppose that sterols, which are absent in aerobic cultures, are derived from this triterpene of 32 C atoms.

Composés stéroliques des spores d'Anthurus muellerianus (Basidiomycète)

We have shown the presence of lupeol, ψ-taraxasterol, germanicol, and β-amyrin in the sterol fraction isolated from the spores of Anthurus muellerianus. Besides these pentacyclic triterpenes, known up to now to be present in higher plants, we have also characterized ergosterol, methyl-24 cholesta-7, 22 diene ol-3β, and methyl-24 cholestene 7 ol-3β.[Traduit par le journal]

Lead uptake from vegetables grown along highways

Blood-lead levels were measured in tenants of vegetable gardens located in close proximity to busy highways (average: greater than 25000 vehicles per workday) in the Netherlands. For comparison, blood-lead levels were determined in tenants of vegetable gardens located away from busy traffic. The results indicate that there is no significant difference between the geometric mean blood-lead levels of the two populations, despite a 2-3-fold difference in the lead content of their vegetables, and despite frequent consumption of these vegetables in the exposed group. Mean PbB-values were around 0.48 mumol/1 (100 micrograms/1), which is well below existing health guidelines and slightly below the levels found in another recent survey of Dutch suburban residents.