Motor coordination and spatial orientation are affected by neurofilament maldistribution: correlations with regional brain activity of cytochrome oxidase

NFH-LacZ transgenic mice are characterized by an early accumulation of the neurofilament cytoskeleton in the cell bodies of neurons with age-associated abnormalities of motor neurons and cerebellar Purkinje cells. In comparison to normal littermate controls, irrespective of age (3 and 12-20 months), NFH-LacZ transgenic mice had a lower number of rears in an open field, deficiencies in some motor-coordination tests, and a higher number of quadrant entries and escape latencies while swimming toward a visible platform. Decreased cytochrome oxidase activity in the lateral reticular nucleus of NFH-LacZ mice was associated with poor performance in two motor coordination tests. Lower metabolic activity in the lateral reticular nucleus may be secondary to previously described cerebellar abnormalities, leading to deficient motor control. The dramatic cytoskeletal perturbation characterizing NFH-LacZ mice affects only selective neuronal populations and results in selective behavioral deficits, which can be correlated with regional brain metabolic activity.

Protective effect of docosahexaenoic acid against hydrogen peroxide-induced oxidative stress in human lymphocytes

Oxidatively stressed lymphocytes exhibit decreased proliferative response to mitogenic stimulation. Although several sensitive targets involved in lymphocyte suppression have already been identified, little is known about the influence of oxidative stress on cyclic nucleotide phosphodiesterases (PDE) (EC 3.1.4.17), thought to play a major role in the control of cyclic AMP (cAMP) level, a well-recognized negative effector of lymphoproliferation. Although the polyunsaturated fatty acid content of membrane phospholipids is thought to be directly related to the extent of oxidant-induced lipid peroxidation, some n-3 fatty acids also seem to have antioxidant effects, depending on the concentration used and the overall redox status of the cells in question. Results of the present study showed that human peripheral blood mononuclear cells (PBMC) as well as rat thymocytes were relatively resistant to a short-term exposure (10 min) to hydrogen peroxide (H2O2). Indeed, H2O2-induced lipid peroxidation, estimated by malondialdehyde (MDA) production, was only 2-fold increased by H2O2 concentrations lower than 2 mM, whereas a larger increase (10-fold) could be observed in PBMC at the highest dose (5 mM). Previous enrichment of PBMC with 5 microM docosahexaenoic acid (22:6n-3), brought to the cells as a fatty acid-albumin complex (ratio 1), significantly reduced MDA production induced by low doses of H2O2, the protective effect no longer being observed at the highest doses. In contrast, eicosapentaenoic acid (20:5n-3) did not have any protective effect. Cytosolic PDE activities of both human PBMC and rat thymocytes were significantly inhibited (40-50%) after H2O2 treatment of the cells, whereas particulate PDE activities were not modified. Different responses of PDE activities to H2O2 treatment were observed when PBMC were first enriched with 22:6n-3 prior to H2O2 addition. In 22:6n-3-treated cells, the H2O2-induced inhibition of both cAMP- and cGMP-PDE cytosolic activities was abolished, whereas the particulate activities were increased by the highest H2O2 concentration used (5 mM). At the same time, the glutathione peroxidase (glutathione: oxidoreductase, EC 1.11.1.9) (GSH-Px) activity of PBMC and thymocytes was only marginally inhibited by H2O2 addition (20%), and pretreatment of the cells with 22:6n-3 did not modify the slight inhibitory effect of H2O2. Collectively, these results suggest that lymphocytes are relatively resistant to H2O2-induced lipid peroxidation due to their high GSH-Px content, and that low doses of 22:6n-3 are able to prevent some of the H2O2-induced alterations such as lipid peroxidation and PDE inhibition. Docosahexaenoic acid might thus offer some protection against oxidant-induced lymphocyte suppression.

[Successful PMA. Review of the activities of the Center for Medically Assisted Procreation of University of Liege, 1985-1997]

Assisted reproductive treatments (ART) hold an increasing place in the field of female infertility but also of male infertility with the development of new micromanipulative technologies. From January 1985 to December 1997, more than 3,000 ovarian punctures were achieved at the CPMA of the University of Liege and more than 40,000 oocytes were recovered. Global results show a take home baby rate of 23% per ovum pick-up and 27% per embryo transfer. Embryo cryopreservation offers an efficient solution to the problem of supernumerary embryos and opens the way for IVF-derived procedures such as oocyte or embryo donation, surrogate mother. The transfer of frozen-thawed embryos increases the total ongoing pregnancy rate per cycle of 31%. One of the aims of our Centre in the near future is the development of new technologies such as control of chromosomal abnormalities or genetic defect in preimplantation embryos and clinical applications of oocyte or ovarian tissue freezing.

Self-assembly of flat nanodiscs in salt-free catanionic surfactant solutions

Discs of finite size are a very rare form of stable surfactant self-assembly. It is shown that mixing of two oppositely charged single-chain surfactants can produce rigid nanodiscs as well as swollen lamellar liquid crystals with frozen bilayers. The crucial requirement for obtaining nanodisc self-assembly is the use of H+ and OH- as counterions. These counterions then form water and lower the conductivity to 10 microsiemens per centimeter. In the case of cationic component excess, a dilute solution of nanodiscs is in thermodynamic equilibrium with a lamellar phase. The diameter of the cationic nanodiscs is continuously adjustable from a few micrometers to 30 nanometers, with the positive charge located mainly around the edges.

Renal effects of low and isoosmolar contrast media on renal hemodynamic in a normal and ischemic dog kidney

RATIONALE AND OBJECTIVES

The authors investigated the comparative effects of a nonionic dimer contrast medium (iodixanol) with an ionic low osmolar contrast media (locm) (ioxaglate) on renal blood in a normal and an ischemic dog kidney.

METHODS

Six dogs were studied for two periods. During the first period (the control period) a renal arteriography was performed with either iodixanol (Visipaque) or ioxaglate (Hexabrix) in a randomized order. Twenty minutes after applying a suprarenal clamp just above the right renal artery, two selective intrarenal contrast media administrations were performed at 30-minute intervals in a randomized order (ischemic period).

RESULTS

During the control period ioxaglate and iodixanol induced no change in mean arterial blood pressure and pulse rate. The maximum decrease in renal blood flow (rbf) observed with ioxaglate was 19 +/- 4%. The maximum decrease in rbf observed with iodixanol was 51 +/- 16% versus control period (P = 0.05 compared with ioxaglate). During the ischemic period, renal perfusion pressure was 72 +/- 2 mm Hg and 73 +/- 2 mm Hg before iodixanol and ioxaglate administration, respectively (P = NS). Iodixanol induced a 61 +/- 11% decrease in RBF. These changes were significantly higher than those observed with ioxaglate during the control period and with the control ischemic period. Ioxaglate induced a maximum 11 +/- 6% decrease in RBF at 1 min (P < 0.05 versus iodixanol). These modifications were not significantly higher than those observed during the control period.

CONCLUSIONS

In this study the authors found that the renal effect of iodixanol are markedly more pronounced than that of ioxaglate. In the setting of ischemia the effects of iodixanol were only slightly enhanced whereas those of ioxaglate were not modified.

GC-MS determination of anabolic steroids after multi-immunoaffinity purification

For many years, EC regulations have prohibited the use of anabolic agents in food-producing animals. Multiple screening methods have been published, but some lack specificity and some are difficult to apply when screening for unknowns in surveillance programmes. This paper presents a new and powerful technique, combining multiresidue immunoaffinity chromatography and GC-MS, for the simultaneous identification and semi-quantification of various anabolic steroids in urine and faeces samples of bovine origin. It should reduce the cost, time and effort of screening by limiting the number of tedious clean-up steps and analyses required. A preliminary extraction step is applied to the individual biological specimens: solid-phase extraction followed by enzymatic digestion in the case of urine samples and a single liquid extraction step for faeces. This step is followed by a first clean-up step involving both a solid-phase column and a rapid RP-HPLC separation. The individual biological fractions (urine or faeces) are further purified on a multiresidue immunoaffinity chromatographic gel (MIAC-steroids-CER) so as to decrease interferences due mainly to background signals. A final trimethylsilyl derivatization is followed by the analysis of the biological samples by a sensitive and specific GC-MS procedure.

Multi-laboratory study of the analysis and kinetics of stanozolol and its metabolites in treated calves

The European Union banned the use of anabolic steroids for cattle fattening in 1988. Analytical techniques able to detect trace amounts of the parent drugs and their metabolites are mandatory for the control of abuse. Stanozolol (Stan) is an anabolic steroid that is often found in injection sites and cocktails. However, it has never been detected in tissues (kidney fat, meat) or excreta (urine, faeces) taken during regulatory inspection. The difference between the structure of Stan and the other steroids (a pyrazole ring fused to the androstane ring system) is probably the cause of this phenomenon. In the multi-laboratory study described here, veal calves were treated with intramuscular doses of Stan. In the excreta of these calves the presence, absence and/or concentration of Stan and of its major metabolites 16 beta-hydroxystanozolol and 3'-hydroxystanozolol were determined. For the determination of these analytes the different laboratories used different extraction and clean-up procedures and also evaluated different analytical techniques such as GC-MS (negative chemical ionization) and LC-MS-MS. The aim of this investigation was to explore which analyte should be validated for veterinary inspection purposes.

[Foreign bodies in the ear; report of 40 cases]

BACKGROUND

Foreign bodies in the external ear canal present a frequent situation in pediatric practice. It is generally benign, but infectious complications may occur.

POPULATION

Between January 1996 and March 1997, 35 children with a foreign body in the ear canal were treated in the ENT department of Robert-Debré hospital.

RESULTS

Age ranged from 15 months to 14 years, with a mean of 6.5 years. The sex ratio was 1.2 (19 boys/16 girls). Five children had bilateral foreign bodies. The most frequent foreign bodies were pearls (8/40) and cockroaches (7/40). Eleven children had complications: ear canal laceration in five cases, otitis externa in five cases, cervical adenitis in three cases, general septic syndrome with fever in one case, and drum perforation in one case.

CONCLUSION

The methods of extraction and the management of the complications are discussed.

Docosahexaenoic acid lowers phosphatidate level in human activated lymphocytes despite phospholipase D activation

N-3 polyunsaturated fatty acids from marine oil have been shown to decrease T cell-mediated immune function both in animals and humans, and to inhibit the mitogen-induced lymphoproliferative response when added to lymphocyte culture medium. As phosphatidic acid (PA) is a key mediator of the mitogenic process, the present study aims to investigate whether docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids, the main n-3 fatty acids from fish oil, are able to alter the mitogen-induced synthesis of PA, when added to the culture medium of human peripheral blood mononuclear cells (PBMC). Incubation of PBMC in a medium containing 5 microM DHA bound to 5 microM human delipidated serum albumin induced a 2-fold increase in the basal PA mass whereas incubation with EPA, in the same conditions, had no effect. In contrast, both fatty acids markedly reduced the concanavalin A (ConA)-induced production of PA as compared with untreated cells. Paradoxically, phospholipase D (PLD) activity, evidenced by the synthesis of phosphatidylbutanol, was only detected in DHA-treated cells further stimulated by ConA, indicating that both DHA and ConA are required for PLD activation. Similarly, an increased diacylglycerol (DAG) mass was only observed in DHA-treated cells stimulated by ConA, whereas no modification occurred in control or EPA-treated cells stimulated or not by ConA. Furthermore, 1-butanol suppressed the ConA-induced increase of DAG mass observed in DHA-treated cells, indicating that phosphatidate was the source of the newly synthesized diacylglycerol. Altogether, these results show that, in concanavalin A-activated human peripheral blood mononuclear cells, docosahexaenoate stimulates both phospholipase D and phosphatidate phosphohydrolase activities, which ultimately results in an increased diacylglycerol production at the expense of phosphatidate.

Sarcoidosis of the paranasal sinuses treated with hydroxychloroquine

A case of sarcoidosis of the paranasal sinuses is reported. Biopsies of the sinus mucosa showed typical noncaseating granulomas. Hydroxychloroquine, which is known to be active on the cutaneous form of sarcoidosis, was used here with success and is proposed as an effective alternative to high-dose systemic steroids.

GEMHEP multicenter quality control study of PCR detection of GB virus C/hepatitis G virus RNA in serum

PCR is, to date, the only available tool for the detection of GB virus C (GBV-C) and hepatitis G virus (HGV) RNAs. Twenty-two French laboratories participated in a quality control study to assess the sensitivity and specificity of their procedures. The panel included 13 positive controls and 7 negative controls. The laboratories used either in-house PCR techniques adapted from the literature or partly standardized commercial tests. Three laboratories performed faultlessly with the entire panel. Most laboratories had excellent specificity (100% in 20 of 22 laboratories). Sensitivity was acceptable (85 to 100%) in 15 centers and insufficient (38 to 77%) in 7. As with nonstandardized in-house PCR, the commercial assays gave discrepant performances in different laboratories. These results suggest that laboratories willing to use PCR for detection of GBV-C/HGV RNA for research or diagnostic purposes should participate in multicenter quality control trials.

High rate of hepatitis C virus clearance in hemodialysis patients after interferon-alpha therapy

To gain insight into the long-term effect of interferon-alpha (IFN-alpha) therapy on hepatitis C virus (HCV) RNA-positive hemodialysis patients, 23 subjects were given 3 MU of IFN-alpha 3 times a week for 6 (n = 12) or 12 months (n = 11). They were followed for 19 months after cessation of therapy. Sustained serum HCV RNA clearance occurred in 42% of patients treated for 6 months and in 64% of those treated for 12 months. HCV was eradicated from 6 of 13 patients infected with HCV genotype 1b and from 2 of 6 patients also infected with hepatitis G virus. HCV RNA remained undetectable in both serum and a liver biopsy of 2 patients who were given cadaveric kidney transplants after IFN-alpha treatment. These data suggest that HCV RNA-positive dialysis patients can be considered for treatment while receiving dialysis, particularly those awaiting transplant.

Kinetics of HCV viremia in kidney transplant recipients during and after alpha-interferon therapy

Fifteen kidney transplant recipients with chronic hepatitis C were given 3 million units recombinant alpha2b-interferon for 142+/-35 days. There were significant decreases in hepatitis C virus (HCV) RNA 1 month after the initiation of treatment (p < 0.01), and at the end of treatment (p < 0.05). HCV RNA was undetectable by PCR analysis during treatment in 5 patients. But HCV RNA reappeared in all patients 1 month after the cessation of therapy, and the level of viremia returned to baseline. While all patients had normalized alanine aminotransferase (ALT) activities at the end of therapy, 11 experienced a relapse during the follow-up period (1 year). There was a correlation between the amount of HCV RNA at the end of treatment and the time of relapse. Serum IgM against core protein of HCV were detected in 7/15 patients. Anti-core IgM remained detectable during treatment and afterwards. There was no correlation between IgM status and other virological parameters, or ALT activity.

[Precancerous states of the endometrium: hormonal aspects]

The two types of endometrial carcinomas are preceded by precancerous lesions. Type I endometrial carcinomas are most commonly encountered in perimenopausal women with the classical risk factors associated with estrogen exposure: obesity, multiparity, diabetes, estrogen treatment, ... Hyperplasia (simple, followed by complex forms without cellular atypias and subsequently by complex hyperplasias with cellular transformation) precede such cancers. Estrogens exert a promoting effect on these lesions but do not initiate them. Progesterone and progestins exert a preventive and protective effect. However, the progressive loss of steroidal receptors is correlated to the progression of tissular anomalies and to the onset of cytogenetic anomalies and to mutations of p53 anti-oncogene. The preventive role of progestin is well established, but their curative beneficial effect on atypical precursors forms of endometrial cancers and on endometrial carcinomas remains controversial. The second type of endometrial cancer appears during the postmenopause and is characterized by an increased invasiveness and a poor prognosis, devoid of identifiable risks factors, these aggressive cancers are not preceded by hormone-sensitive precancerous lesions, but by an intra-epithelial endometrial carcinoma. This lesion appears most often in an atrophic endometrium. Finally, the two types of precancerous states are characterized by distinct gene anomalies suggesting two different pathogenic mechanisms of cancerisation.

Quantitative determination of several synthetic corticosteroids by gas chromatography-mass spectrometry after purification by immunoaffinity chromatography

A study was conducted to test a multiresidue analytical procedure for detecting and quantifying several corticosteroids on which the European Union imposes maximum residue limits (MRLs). Primary extracts from different matrices (liver, milk, urine, faeces) were first purified on C18 cartridges. A new immunoaffinity clean-up step was included. The immunoaffinity gel was used to purify several corticosteroids simultaneously with enrichment of the corresponding fractions. The extracts were treated with an aqueous solution of pyridinium chlorochromate to fully oxidise all corticosteroids and to facilitate their extraction with dichloromethane. After evaporation, the final extract was reconstituted with toluene before injection into the GC-MS apparatus. The analysis was performed in the CI-negative ionisation mode using ammonia as the reactant gas. The estimated detection and quantification limits were, respectively, 0.25 and 0.5 ppb or lower. Overall, the method is reproducible to within 20%. Recovery is between 50 and 80% according to the corticosteroid.

Losartan: a new antihypertensive drug

Hypertension is a major risk factor for cardiovascular disease. It affects approximately one in five, or 20 per cent of Canadians. The consequences of untreated hypertension include myocardial infarction, stroke, congestive heart failure, peripheral vascular disease and renal disease. By lowering a person's diastolic blood pressure 5 to 6 mmHg, their chances of having a stroke are reduced by 35 to 40 per cent and 20 to 25 per cent for coronary heart disease. While the treatment for hypertension includes both nonpharmacological and pharmacological therapy, this article will explore losartan or Cozaar, which falls under the newest class of antihypertensive drugs, angiotensin II antagonists.

Role of endothelium-derived nitric oxide-endothelin balance in contrast medium-induced acute renal vasoconstriction in dogs

RATIONALE AND OBJECTIVES

The authors evaluated the involvement of nitric oxide and endothelin in radiographic contrast medium-induced changes in renal hemodynamics.

METHODS

Eleven anesthetized healthy dogs were each studied during three periods. Thirty minutes before the first, second, and third periods, the dogs received 1 mL per kilogram of body weight of isotonic saline, L-N-nitro-L-arginine-methyl-ester (L-Name, 10 mg/kg intravenously), and L-arginine (500 mg/ kg intravenously), respectively. Renal blood flow (RBF) and mean arterial blood pressure were continuously monitored. The glomerular filtration rate (GFR) was evaluated by means of polyfructosan clearance.

RESULTS

Contrast medium induced a significant (P < .05) decrease in RBF and GFR and a significant (P < .05) increase in urinary endothelin excretion. L-Name enhanced the effect of contrast media on RBF and GFR. L-arginine attenuated the effect of L-Name on the contrast medium-induced reduction of GFR.

CONCLUSION

These findings support the hypothesis that acute contrast medium-induced intrarenal vasoconstriction may involve an imbalance of endothelial vasoactive agents, nitric oxide, and endothelin, and they confirm the involvement of hemodynamic changes in contrast medium-induced nephropathy.

Comparative acute nephrotoxicity of FK-506 and ciclosporin in an isolated in situ autoperfused rat kidney model

The acute hemodynamic effects of ciclosporin A (Cs-A; 40 and 20 mg/kg), FK506 (1.5 and 0.4 mg/kg), and their vehicles were studied in an in situ autoperfused rat kidney model. Cs-A (60 +/- 7 and 66 +/- 5% of the initial value, respectively; p < 0.05 vs. control group) and FK506 (89 +/- 3 and 77 +/- 3% of the initial value respectively; p < 0.05 vs. control group) induced a significant fall in renal blood flow. Cs-A significantly increased the renal vascular resistance, whereas FK506 had no effect. The glomerular filtration rate (inulin clearance) declined significantly in all groups. Cremophore and FK506 vehicle had no hemodynamic effect on the glomerular filtration rate. In our model, FK506 had less vasoactive effects on the renal hemodynamics than Cs-A.

Specific effects of n-3 fatty acids and 8-bromo-cGMP on the cyclic nucleotide phosphodiesterase activity in neonatal rat cardiac myocytes

The authors have previously resolved four forms of cyclic nucleotide phosphodiesterase (PDE) in neonatal rat cultured cardiomyocytes by use of high-performance liquid chromatography (HPLC) and have shown that the response of the cGMP-stimulated PDE to the effector cGMP was markedly reduced as compared to that of the corresponding isoform present in the heart ventricle of adult rat (70% v 350%). When neonatal rat ventricular myocytes were grown in a medium enriched in docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA), an increase of the basal level of cAMP and mainly cGMP was observed. The cGMP-PDE specific activity in the unfractionated cytosol of DHA-, EPA- or 8-bromo-cGMP-enriched cardiomyocytes was lower than that observed in control cells. Whereas the cAMP-PDE specific activity remained unchanged whatever the treatment used. At the same time, the response of the cGMP-stimulated PDE to cGMP was substantially increased in n-3 fatty acid-enriched cardiomyocytes and reached the same level as in the whole ventricle (340%). The treatment of neonatal cardiomyocytes with 8-bromo-cGMP also re-established the sensitivity of this cGMP-stimulated isozyme to cGMP (320%). These results suggest a common mechanism for polyunsaturated fatty acids and 8-bromo-cGMP in the regulation of the cGMP-stimulated PDE activity in cardiomyocytes from new-born rats.

Hierarchical cluster analysis of environmental pollutants through P450 induction in cultured hepatic cells

Environmental pollutants are classically associated with increased drug metabolism. Cultures of rat hepatocytes, quail hepatocytes, and human hepatoma (Hep G2) cells were used to study the effects of pesticides on drug-metabolizing enzymes. Membrane integrity and mitochondrial activity were evaluated and induction of ethoxycoumarin-O-deethylase and ethoxyresorufin-O-deethylase activities were measured. Induced P450s were identified by immunoblotting. Pentachlorophenol and lindane appeared as the strongest inducers. On the immunoblots, specific antibodies revealed induced CYP1A1 in fetal rat hepatocytes, CYP2B in quail hepatocytes, and CYP3A7 in Hep G2 cells. Pesticide effects on these different activities in each type of cultured cells were compared by cluster analysis. Results obtained under similar conditions with reference inducers phenobarbital (PB) and benzo[a]anthracene and other environmental pollutants (polychlorobiphenyls) were added to previous data prior to multivariate analysis. The tested products fell into four major groups: a first group with pentachlorophenol, identified as a CYP3A inducer; a second group containing the methylcholanthrene-type inducers that increase CYP1A-related activities; a third class represented by dieldrin, a PB-type inducer; a fourth group including inert compounds or weak inducers. Lindane shares the criteria of the second and third groups and seems to induce both CYP1A and CYP2B activities. The current study results highlight the advantage of using several types of cultured hepatocytes to evaluate the short-term toxicity of environmental pollutants in vitro and constitute a useful model for predicting the potential toxicity of pesticides in humans (Hep G2 cells) and wildlife (fetal quail hepatocytes).

Selective inhibition of rat heart cAMP phosphodiesterases by lipophilic C-methyl-2-phenyl-4H-1-benzopyran-4-ones (C-methylflavones)

A series of eight methoxylated C-methyl-2-phenyl-4H-1-benzopyran-4-ones 3, 6, 10-15 was evaluated as inhibitors of rat heart cytosolic cyclic nucleotide phosphodiesterase (PDE). The 2-(3,4-dimethoxyphenyl)-5,7-dimethoxy-3,8-dimethyl-4H-1-benzopyran-4-one (3) and the 2-(4-methoxyphenyl)-5,7-dimethoxy-3,8-dimethyl-4H-1-benzopyran-4-one (10) have never been previously described. Inhibition was performed on the whole cytosolic preparation and on the four PDE isoforms after HPLC purification. The flavones 3, 6, 10, 13 and 14 were selective and potent inhibitors of the isoforms, namely ROI (rolipram-sensitive) and CGI (cGMP-sensitive) PDEs specifically hydrolyzing cAMP. The di-C-methylflavones 3 and 13 have been shown to be potent inhibitors of these two isoforms, with IC50 values in the micromolar range.

Selective induction of the CYP3A family by endosulfan and DNA-adduct formation in different hepatic and hepatoma cells

Endosulfan, a chlorinated cyclodiene insecticide, is known to cause a significant enhancement of altered hepatic foci in rats and to be a potent inhibitor of gap-junctional intercellular communication in vitro. Both of these features are common to many tumor promoters. However, long-term studies in rodents provide no evidence that it is carcinogenic or genotoxic. In the present study, endosulfan genotoxicity is evaluated and the formation of DNA adducts is investigated in three types of cultured hepatic cells (rodent, bird, and human). DNA-adduct formation in response to endosulfan treatment is measured by the (32)P-postlabelling method. The results have shown a high genotoxicity of endosulfan only in rat and human cells. Therefore, to better understand these findings and because nothing is known about the xenobiotic-metabolizing enzymes involved in endosulfan metabolism, we have attempted to identify the cytochromes P450 induced, which can transform endosulfan into reactive intermediates capable of interacting with DNA. To examine if endosulfan induces CYP1A-, CYP2B-, or CYP3A-family transcripts, we measured transcript levels by Northern blot and RT-PCR analyses. Endosulfan appears to selectively induce expression of the CYP3A gene family. It is a potent inducer of CYP3A1 mRNA in rat and is also shown, by RT-PCR. to increase the CYP3A7 transcript level in Hep G2 human hepatoma cells. In contrast, in fetal quail hepatocytes, CYP3A is not expressed and no endosulfan-DNA adducts are formed.

Ultrastructural modifications in cultured fetal quail hepatocytes exposed to pesticides and PCBs

There is increasing interest in cultured hepatocytes as a tool for solving toxicological and pharmacological problems while reducing laboratory animal experimentation. In the present study, fetal hepatocytes from the Japanese quail (Coturnix coturnix japonica) were used as an in vitro alternative model for evaluating the effects of PCBs and various pesticide-type chemicals on cell ultrastructure. Major alterations were demonstrated. The most striking effects of toxicants were an increase in the number of cisternae of the rough endoplasmic reticulum (RER), various alterations of mitochondrial morphology, a decreased glycogen content, vacuolization of the cytoplasm, and the appearance of concentric membrane arrays (CMA's), also called myelin-like figures. Other changes were sometimes observed, such as altered cell junctions, an increased lipid content, deformations of the nuclei, or the appearance of crystalline structures. These ultrastructural modifications seem to be dose-dependent. The present in vitro findings are validated by similar observations previously made in vivo on Japanese quail. They confirm the effectiveness of this technique as a biomonitoring tool for the evaluation of environmental quality. Yet the multiplicity of possible toxic effects, even for xenobiotics of a same category, makes it necessary to screen additional indicators of toxicity, such as the detoxifying activity of monooxygenases.

Prevention of cyclosporin nephrotoxicity with a platelet-activating factor (PAF) antagonist

BACKGROUND

Cyclosporin (CsA) is a potent immunosuppressive drug whose main side-effect is nephrotoxicity. In the kidney, CsA induces vasoconstriction with a decrease in renal blood flow (RBF) and glomerular filtration rate (GFR) and a significant increase in renal vascular resistance (RVR). CsA enhances platelet-activating factor (PAF) synthesis in mesangial cells in vitro. PAF, a secondary mediator of anaphylaxis and inflammation, exhibits vasoactive properties in the kidney similar to those of CsA.

METHODS

The in situ autoperfused rat kidney model was used to investigate whether PAF plays a role in the haemodynamic injury induced by CsA.

RESULTS

In this model, CsA (40 mg/kg and 20 mg/kg i.v.) induced a significant decrease in RBF and in GFR and an increase in RVR. BN 52021, a potent and specific PAF antagonist (20 mg/kg i.v. bolus dose) induced a significant increase in GFR (137 +/- 32% of initial value, P < 0.05). BN 52021 (20 and 10 mg/kg) also significantly prevented the decline in RBF and GFR induced by CsA.

CONCLUSIONS

We have demonstrated that the PAF antagonist BN 52021 can minimize the alteration of renal function induced by CsA.

Chronic effects of endothelin-3 on blood pressure and renal haemodynamics in rats

BACKGROUND

Renal vasoconstriction and systemic hypertension are well-known effects of bolus or short-term endothelin administration. However, the role of endothelin as a circulating hormone remains largely unknown.

METHODS

The present study explores the effects of endothelin-3 (ET-3) on renal haemodynamics and systemic blood pressure during a 3-h and a 3-day intravenous infusion in rats. Male Sprague-Dawley (SD) rats were infused with vehicle (group 1) or ET-3 (group 2), 10 ng/kg per min; group 3, 50 ng/kg per min) delivered via osmotic minipumps into the right jugular vein for 3 days. On day 3 after pump implantation, rats were anaesthetized with Inactin and surgically prepared for assessment of mean arterial blood pressure (MABP), renal plasma flow (RPF), glomerular filtration rate (GFR), and renal vascular resistance (RVR). The same parameters were assessed during a 3-h ET-3 infusion study in SD rats (group 4, vehicle; group 5, ET-3, 10 ng/kg per min; group 6, ET-3, 50 ng/kg per min).

RESULTS

In 3-day infused rats, ET-3 induced a significant decrease in RPF (-22+/-7% and -26+/-8% for group 2 and group 3 respectively, P<0.05 vs group 1) and an increase in RVR (+40+/-11% for groups 2 and 3; P<0.05 vs group 1); 50 ng/kg per min ET-3 significantly decreased GFR (-17%, P<0.05 vs group 1). MABP was not significantly affected by endothelin infusion. In acute infusion studies a decrease of the same magnitude was seen for the renal haemodynamics values. 50 ng/kg per min ET-3 increased MABP; a systemic effect that disappeared after the 3-day infusion.

CONCLUSIONS

This study suggests that intravenously administered ET-3 in the rat has only a transient effect on systemic blood pressure, whereas it induces alterations in renal haemodynamics after both acute and chronic perfusions.

P450 induction by Aroclor 1254 and 3,3',4,4'-tetrachlorobiphenyl in cultured hepatocytes from rat, quail and man: interspecies comparison

Polychlorobiphenyls are potent inducers of hepatic cytochrome P450 in various species. Until now, no model based on cultured cells can be considered as a universal surrogate for in vivo metabolism. In this respect, cultured rat hepatocytes, quail hepatocytes, and human hepatoma (HepG2) cells were used to study the effects of 3,3',4,4'-tetrachlorobiphenyl (3,3',4,4'-TCB) and Aroclor 1254 on drug-metabolizing enzymes. The presence of dexamethasone in the culture medium allows the expression and the induction of several cytochrome P450 isoenzymes found in adult cells. Induction of ethoxycoumarin-(ECOD) and ethoxyresorufin-O-deethylase (EROD), activities were measured. Induced P450s were identified by immunoblotting and Northern blotting. Aroclor 1254 induced ECOD activity in all three cell types, but the effect was much stronger in fetal rat hepatocytes than in human or quail cells. Aroclor failed to induce EROD activity in quail cells, had a slight inducer effect in HepG2 cells, and a marked effect in rat hepatocytes. 3,3',4,4'-TCB had no effect in HepG2 cells but significantly increased EROD and ECOD activities, especially the latter, in rat and quail cells. On the immunoblots, specific antibodies revealed essentially CYP1A1 in fetal rat hepatocytes, CYP2B1/2 in quail hepatocytes and CYP3A1 in HepG2 cells. Analysis of Northern blots showed an hybridization with CYP1A1, 2B1 and 3A1 mRNA in fetal rat hepatocytes, CYP3A and 1A mRNA in HepG2 cells, and a form of CYP2 mRNA in fetal quail hepatocytes closely related to homolog rat CYP2E or CYP2C. In quail hepatocytes, induction did not increase proportionally with the concentration of inducer in the culture medium. Instead, the dose-response curves (for EROD activity especially) peaked sharply at 1 muM Aroclor 1254, an effect attributed to changes in membrane fluidity or lipid content. Our results highlight the advantage of using several types of cultured hepatocytes to investigate fundamental aspects of drug-metabolism-linked toxicity, the balance between xenobiotic bioactivation and detoxication being differently affected by PCBs in different animal species.

Psychodynamic aspects of smoking cessation among physicians

After approximately 10 years of research on smoking habits with an emphasis on prevention and dishabituation, we focused on the training of teachers and general practitioners. A fairly wide-ranging inquiry within the Communauté francaise de Belgique was conducted among nearly 2000 doctors. The study showed that the proportion of smokers, although lower than the average in the general population, was higher among the doctors than other socio-professional categories. A comparison of the results registered in 1983 and 1991 revealed a decrease in the number of smokers and an increase in the number of non-smokers (those who have never smoked). This change stemmed largely from a sharply lower smoking rate among young doctors. These findings impelled us to study the resistance to dishabituation among doctors who smoked. The inquiry was comprised of non-authoritative, Rogerian-style talks that enabled us to isolate a number of motivating factors and some rather typical defense mechanisms that, until recently, went partly unnoticed. The denial, indeed the placation, of anxieties in the medical profession fostered by the constant confrontation with illness and the challenge of and victory over death apparently plays a crucial role, albeit on the unconscious plane.

DNA adducts and P450 induction in human, rat and avian liver cells after exposure to polychlorobiphenyls

Polychlorinated biphenyls (PCBs) are industrial chemicals which have been detected in fish, birds and humans. They are known to exert marked effects on the liver. They induce hepatocellular carcinoma in rats and birds, and are suspected of being carcinogenic to humans. To better understand the genotoxic effects of PCBs, we used 32P-postlabelling to investigate DNA adduct formation, after exposure to PCBs (Aroclor 1254 and 3,3',4,4'-tetrachlorobiphenyl), in primary cultures of fetal hepatocytes from two animal species and in a human cell line (Hep G2). We also studied the induction of 7-ethoxyresorufin-O-deethylase (EROD) in these PCB-treated cells. The three cell types used are known to express different cytochrome P450 families. The aim was to see whether a correlation could be established between EROD activity (a CYP1A1-related activity) and DNA adduct formation. DNA adducts were found in all three models after exposure to 50 microM 3,3',4,4'-tetrachlorobiphenyl. The number of adducts was higher in quail hepatocytes (37 adducts per 10(9) nucleotides) than in rat hepatocytes or Hep G2 cells (20 adducts per 10(9) nucleotides in both cases). The major adduct was the same in all three cell types, but some adducts were found in only one or two species. These inter-species differences probably reflect metabolic differences leading to different ultimate carcinogens. Exposure to Aroclor 1254 failed to produce significant levels of DNA adducts, suggesting that pre-treated cells are required to magnify Aroclor 1254 metabolism. No correlation was found between adduct formation and the level of EROD induction.

Developmental differences in distribution of cyclic nucleotide phosphodiesterase isoforms in cardiomyocytes and the ventricular tissue from newborn and adult rats

We characterized cyclic nucleotide phosphodiesterase (PDE) activities in neonatal rat cardiomyocytes and in whole ventricle from newborn and adult rats, to determine whether cyclic nucleotide hydrolytic activities might be influenced by the developmental stage of the animal or by cell isolation and culture procedures. Using anion-exchange high-performance liquid chromatography (HPLC), we obtained four soluble PDE activities from adult rat ventricle. Peak 1, a cyclic GMP-specific PDE was stimulated by Ca2+/calmodulin; peak 2 hydrolyzed cyclic AMP and cyclic GMP, the addition of cyclic GMP stimulating the hydrolysis of cyclic AMP. Peaks 3 and 4 selectively hydrolyzed cyclic AMP, peak 3 being very sensitive to inhibition by rolipram and peak 4 consisting of two different enzyme activities, one inhibited by cyclic GMP (peak 4b) and the other inhibited by rolipram (peak 4a). In cardiomyocytes and whole ventricle from newborn rats, the response of the two cyclic GMP-sensitive PDE isoforms (cyclic GMP-stimulated and cyclic GMP-inhibited PDE) to the effector cyclic GMP was markedly reduced as compared with that of the corresponding isoforms (peaks 2 and 4b) present in the heart ventricle of adult rats. The other peaks were analogous to peaks 1, 3, and 4a of the whole ventricle. The profile of PDE activities in nonmyocardial cells did not differ from that of myocytes. Therefore, the lack of cyclic GMP effects was not due to culture conditions. Differences in PDE activities observed between cardiomyocytes from newborn rats and ventricle from adult rats might be age dependent.

Effect of inducers and PCBs on the cytochrome P450 enzymes in cultured quail hepatocytes

Hepatocytes isolated from fetal quail livers (Coturnix coturnix japonica) were cultured in vitro. Their capacity to metabolize drugs and xenobiotics was explored with typical cytochrome P450 substrates: ethoxycoumarin (known to be metabolized by several P450s), ethoxyresorufin (essentially dealkylated by P450IA1), and testosterone (specifically hydroxylated at several positions by several P450s). The cells could be kept metabolically active in culture for at least 4 days. Their drug-metabolizing activities were inducible by the usual P450 inducers, like phenobarbital and benzanthracene, but also by Aroclor 1254, a PCB mixture. The results obtained indicate that this experimental model could certainly be very helpful in ecotoxicological studies.

The team approach

Cardiovascular disease continues to be the major cause of death and illness in Canada. But the news is not all bad. The incidence can be reduced by minimizing one or more cardiovascular risk factors.

[Intravenous glucose tolerance test in the functional exploration of segmental pancreatic autografts in the dog]

The aim of the present study is based on the comparison of intravenous tolerance testing before and after segmental pancreas autotransplantation in the dog. The results show that such testing must take in account the "glucose diffusion space", using the same glucose load in order to avoid the bias related to the post-operative loss of body weight.

Renal tolerance of gadolinium-DOTA and gadolinium-DTPA in rats

RATIONALE AND OBJECTIVES

Although gadolinium chelates are mainly eliminated by the kidney, there is limited information about their effects. The renal tolerance of these compounds on renal function in an in vivo rat model are evaluated.

METHODS

A combination of renal ischemia and intrarenal iodinated contrast agent infusion (diatrizoate) led to a reproducible and reversible model of acute renal failure (n = 5). Using this model, the renal tolerance of gadolinium DOTA (Gd-DOTA) (n = 10) and gadolinium DTPA (Gd-DTPA) (n = 10) were evaluated. The effects of the association of Gd-DOTA with diatrizoate (n = 5) on renal function also were assessed.

RESULTS

Gadolinium DOTA induced no change in serum creatinine and creatinine clearance. Gadolinium DTPA induced a significant increase in serum creatinine (50 to 83 +/- 5 and 70 +/- 6 mumol/L) before and at 24 and 48 hours, respectively (P < .05), and a decrease in creatinine clearance from 1.6 +/- 0.1 to 0.8 +/- 0.1; 1.2 +/- 0.1 mL/mL before and at 24 and 48 hours, respectively (P < .05). In this model, Gd-DOTA did not modify the renal tolerance of diatrizoate as assessed with serum creatinine and creatinine clearance.

CONCLUSIONS

Gadolinium DOTA is not nephrotoxic and can be infused in association with iodinated contrast media. In this model, Gd-DTPA induced reversible renal failure.

Prevention of acute cyclosporin nephrotoxicity by verapamil and atrial natriuretic factor in the rat

Nephrotoxicity is the most common and important side-effect of cyclosporin (CsA) therapy. CsA alters renal haemodynamics with a reduction in renal blood flow (RBF) and glomerular filtration rate (GFR) and a significant increase in renal vascular resistances (RVR). The present experimental study investigates whether verapamil or atrial natriuretic factor (ANF) are able to prevent the nephrotoxicity of CsA. All studies were conducted in an in-situ autoperfused rat kidney model which allows continuous measurement of renal blood flow without dissection of the renal artery. CsA as a 40 mg/kg bolus dose significantly decreased RBF (from 2.15 +/- 0.1 and 2.19 +/- 0.1 before CsA, to 1.29 +/- 0.16 ml/min/100 g BW, 60 min after CsA administration) (P < 0.05), and GFR (from 0.14 +/- 0.1 and 0.13 +/- 0.01 before CsA, to 0.08 +/- 0.01 ml/min/100 g BW, 60 min after CsA administration) (P < 0.05). CsA significantly increased RVR (from 9.5 +/- 0.73 and 9.8 +/- 0.78 before CsA, to 16.7 +/- 2.9 mmHg x min/ml 60 min after CsA administration) (P < 0.05). Verapamil pretreatment (as continuous intrarenal infusion at the rate of 1.25 micrograms/kg/min) attenuated the fall in GFR (from 0.16 +/- 0.01 and 0.19 +/- 0.03 ml/min/100 g before CsA to 0.20 +/- 0.05 ml/min/100 g BW, 60 min after CsA administration) (NS) and in RBF (from 2.42 +/- 0.2 and 2.6 +/- 0.22 ml/min/100 g before CsA to 1.79 +/- 0.17 ml/min/100 g BW, 60 min after CsA administration (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)