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Aim: To determine the safe dose range and pharmacokinetics of metronomic oral vinorelbine and obtain preliminary data on biomarkers and efficacy in patients with advanced cancer.Methods: Successive cohorts of patients received escalated doses of oral vinorelbine given thrice a week until disease progression, unacceptable toxicity (UT), or consent withdrawal. UT was any grade 4 toxicity, or grade 2 or 3 toxicity that would result to longer than 2-week break during the first 2 months of treatment. Blood samples were collected for pharmacokinetics and quantification of angiogenesis regulatory proteins.Results: Sixty-two patients (median age, 60 years) enrolled at six dose levels from 20 to 70 mg and received treatment for median 12.25 weeks (range, 2-216+). Unacceptable toxicity occurred in two of six patients treated at 60 mg (leucopenia grade 4 and epistaxis grade 2) and in one at 70 mg (leucopenia grade 2). The upper metronomic dose was 50 mg. Objective antitumor response documented in eight cases and 32% of patients experienced disease stability for minimum 6 months. Three responders (renal cancer, medullary thyroid carcinoma, and Kaposi sarcoma) received nonstop treatment for over 3 years without overt toxicity. Low pretreatment levels of circulating interleukin-8, vascular endothelial growth factor, and basic fibroblast growth factor were found predictors of efficacy. Steady-state concentrations of vinorelbine and its active metabolite ranged from 0.5 to 1.5 ng/mL.Conclusions: Metronomic administration of oral vinorelbine is feasible at doses up to 50 mg thrice a week and can yield sustainable antitumor activity without overt toxicity, probably through antiangiogenic mechanism. Further clinical investigation is warranted. (Clin Cancer Res 2009;15(20):6454–61)

Supplementary Data from Dose-Ranging Study of Metronomic Oral Vinorelbine in Patients with Advanced Refractory Cancer

Several pharmaceutical agents are known to produce ethanol intolerance, which is often depicted as disulfiram-like reaction. As in the case with disulfiram, the underlying mechanism is believed to be the accumulation of acetaldehyde in the blood, due to inhibition of the hepatic aldehyde dehydrogenases, albeit this has not been confirmed in all cases by blood acetaldehyde measurements. Herein, cefamandole, cotrimoxazole, griseofulvin, procarbazine, and propranolol, which are reported to produce a disulfiram-like reaction, as well as disulfiram, were administered to Wistar rats and the hepatic activities of ethanol metabolizing enzymes along with the levels of brain monoamines were determined. Blood acetaldehyde was also evaluated after ethanol administration in rats pretreated with the abovementioned pharmaceutical products. Disulfiram, cefamandole, and procarbazine significantly increased blood acetaldehyde levels after ethanol administration, while on the contrary, cotrimoxazole, griseofulvin, and propranolol had no effect on blood acetaldehyde. Interestingly, all substances used, except disulfiram, increased the levels of brain serotonin. According to our findings, cotrimoxazole, griseofulvin, and propranolol do not produce a typical disulfiram-like reaction, because they do not increase blood acetaldehyde when given together with ethanol. On the other hand, all tested agents share the common property to enhance brain serotonin, whereas a respective effect of ethanol is well established. Hence, the ethanol intolerance produced by these agents, whether blood acetaldehyde concentration is elevated or not, could be the result of a “toxic serotonin syndrome,” as in the case of the concomitant use of serotonin-active medications that provoke clinical manifestations similar to those of a disulfiram reaction.

Ethnopharmacological relevance Dynameron is a Byzantine medical compendium, divided into 24 sections, the “Elements”, containing 2667 recipes, most of which inherited by previous physicians of the classic ancient Greek and Hellenistic, and imperial Roman periods. Aim of the study In continuation to our previous study concerning the first and largest chapter of the “Element Alpha” of Nikolaos Myrepsos׳ Dynameron (Valiakos et al., 2015), this paper focuses on the plants quoted in the recipes of the eight following chapters entitled “About Salts”, “About Honeypacks” and “About Spreads”, all belonging to the same “Element Alpha”; “About Antitussives” and “About Suppositories” belonging to the “Element Beta”; “About women's Cathartics” belonging to the “Element Gamma”; “About Drossaton” and “About Diachrisma”, both belonging to the “Element Delta”. Materials and methods Our main primary source material was the codex kept in the National Library of France (in Paris) under the number grec. 2243, which is the older and larger codex of Dynameron (Valiakos et al., 2015). Results The present study led us to the interpretation of 277 plants under different names, among which we recognized 57 medicinal plants listed by the European Medicines Agency, one of them with negative monograph (i.e. Chelidonium majus ). In addition, there are identified taxa related to those quoted by EMA as herbal medicines. The plants appearing in the examined Elements belong to various families of which the most frequent are: Apiaceae 10.11%; Lamiaceae 7.22%; Asteraceae 6.86%; Rosaceae 6.5% and Fabaceae 6.14%. Conclusions A total of 277 species have been catalogued, most of which are referred in our previous publication (Valiakos et al., 2015). Among them, 56 plants still play a very important role in medical practice, as they are used as traditional herbal medicines ( www.ema.eu ). This evidence is a proof that the use of medicinal plants remains valuable from the ancient times until today. The recipes, in contrast to older medical compendia, contain precise measurements of ingredients and dosages for every drug, which seem to reflect empirical logic.

Oleuropein (OLE), a main constituent of olive, exhibits antioxidant and hypolipidemic effects, while it reduces the infarct size in chow- and cholesterol-fed rabbits. Peroxisome proliferator-activated receptor α (PPARα) has essential roles in the control of lipid metabolism and energy homeostasis. This study focused on the mechanisms underlying the hypolipidemic activity of OLE and, specifically, on the role of PPARα activation in the OLE-induced effect. Theoretical approach using Molecular Docking Simulations and luciferase reporter gene assay indicated that OLE is a ligand of PPARα. The effect of OLE (100 mg/kg, p.o., per day, ×6 weeks) on serum triglyceride (TG) and cholesterol levels was also assessed in adult male wild-type and Ppara-null mice. Molecular Docking Simulations, Luciferase reporter gene assay and gene expression analysis indicated that OLE is a PPARα agonist that up-regulates several PPARα target genes in the liver. This effect was associated with a significant reduction of serum TG and cholesterol levels. In contrast, OLE had no effect in Ppara-null mice, indicating a direct involvement of PPARα in the OLE-induced serum TG and cholesterol reduction. Activation of hormone-sensitive lipase in the white adipose tissue (WAT) and the liver of wild-type mice and up-regulation of several hepatic factors involved in TG uptake, transport, metabolism and clearance may also contribute in the OLE-induced TG reduction. In summary, OLE has a beneficial effect on TG homeostasis via PPARα activation. OLE also activates the hormone sensitive lipase in the WAT and liver and up-regulates several hepatic genes with essential roles in TG homeostasis.

Glioblastoma multiforme (GBM) is the most common and aggressive malignancy of the central nervous system. Treatment usually involves a combination of surgical resection, chemotherapy, and radiotherapy, but ultimately this condition is incurable. Besides the dismal prognosis of GBM, financial factors have also presented challenges for advancing treatments. Taking into consideration the high cost of developing new anticancer drugs as well as the fact that GBM is a rare disease, thus further limiting financial incentive for drug development, it becomes obvious that there has been growing interest for repurposing candidates. One of the most promising drugs to repurpose for treating GBM is disulfiram (DSF). DSF is a relatively nontoxic drug used for more than sixty years in the treatment of chronic alcoholism with the ability to readily cross the blood-brain barrier. Repurposing DSF for use as an anticancer drug in general has recently become of interest because of its preclinically described anticancer effects against various human cancers. Interestingly, a number of these effects were shown to be copper (Cu)-dependent. The purpose of this paper was to review the existing literature surrounding preclinical and clinical data on the effects of DSF -alone or in combination with Cu- in GBM. In addition, we present the first case of a GBM patient safely treated with DSF/Cu combination along with standard therapy exhibiting remarkably increased progression-free (PFS) and overall survival (OS).

Malassezia yeasts are commensal microorganisms, which under insufficiently understood conditions can become pathogenic. We have previously shown that specific strains isolated from diseased human skin can preferentially produce agonists of the aryl hydrocarbon receptor (AhR), whose activation has been linked to certain skin diseases. Investigation of skin scale extracts from patients with Malassezia-associated diseases demonstrated 10- to 1,000-fold higher AhR-activating capacity than control skin extracts. Liquid chromatography-tandem mass spectrometry analysis of the patients' extracts revealed the presence of indirubin, 6-formylindolo[3,2-b]carbazole (FICZ), indolo[3,2-b]carbazole (ICZ), malassezin, and pityriacitrin. The same compounds were also identified in 9 out of 12 Malassezia species culture extracts tested, connecting their presence in skin scales with this yeast. Studying the activity of the Malassezia culture extracts and pure metabolites in HaCaT cells by reverse transcriptase real-time PCR revealed significant alterations in mRNA levels of the endogenous AhR-responsive genes Cyp1A1, Cyp1B1, and AhRR. Indirubin- and FICZ-activated AhR in HaCaT and human HepG2 cells with significantly higher, yet transient, potency as compared with the prototypical AhR ligand, dioxin. In loco synthesis of these highly potent AhR inducers by Malassezia yeasts could have a significant impact on skin homeostatic mechanisms and disease development.

Early maternal deprivation (MD) is an animal model of neurodevelopmental stress associated with a variety of abnormalities during adulthood. The present study investigated specific behavioral, neurochemical and neurobiological parameters related to dopaminergic and serotonergic function in adult rats subjected to early life MD. Behavioral responses, including the reaction to novelty, the response to d-amphetamine (d-AMP) and the susceptibility to apomorphine (APO) were evaluated in adulthood. Dopamine (DA) and serotonin (5-HT) levels, their metabolites along with their turnover ratios were assessed in distinct rat brain regions. The impact of MD on DARPP-32 protein, D2 and 5-HT2A receptor expression was also estimated in the same brain regions during adulthood. Our results indicated that MD rats were more reactive to novelty behavior and more sensitive to dopaminergic agonists compared to controls. MD rats displayed elevated dopaminergic and serotonergic function in the amygdala and prefrontal cortex, whereas in the striatum only the dopaminergic activity was also increased. Interestingly, MD induced a region-dependent modulation of D2, 5-HT2A receptor and DARPP-32 protein expression. Our findings clearly indicated that early MD stress produces long term behavioral impairments and region-dependent modifications in various neurochemical and neurobiological indices of dopaminergic and serotonergic function in brain regions holding critical roles in the pathophysiology of central nervous system disorders.

To investigate the relationship among brain derived neurotrophic factor (BDNF) serum concentrations, BDNF Val66Met polymorphism and personality profile in drug-naïve schizophrenic patients with first-episode psychosis (FEP) and healthy participants.This cross-sectional study included fifty FEP patients and fifty healthy participants who served as controls. To study their personality profile the standardized Greek version of the Alternative Five-Factor Zuckerman-Kuhlman Personality Questionnaire (ZKPQ) was administered. Serum BDNF levels were measured and genotyping of BDNF Val66Met polymorphism was performed in patients and healthy subjects.FEP patients presented lower BDNF serum concentrations (P=0.002) and higher scores in ZKPQ Neuroticism (P=0.001) and Aggression-Hostility (P=0.002) scales while lower scores in the ZKPQ Sociability scale (P0.001) than healthy participants. Multivariate analysis revealed that the odds of being assessed with FEP were 0.4 times lower in those with higher BDNF values (P0.001) and 1.8 times greater in those with higher Neuroticism scores (P0.001). There were no significant differences with respect to the Val66Met polymorphism between patients and healthy participants.Reduced BDNF serum concentrations along with higher Neuroticism scores might be associated with FEP. A complex interplay between BDNF serum concentrations, personality traits, BDNF Val66Met polymorphism, and psychotic symptomatology has been arisen but further investigation is needed to better clarify the observed associations.

Background/Aims: Isoniazid (ISO) has been reported to inhibit the hepatic aldehyde dehydrogenase (ALDH) and to cause a disulfiram (DIS)-like reaction, albeit there are no reports demonstrating increased blood acetaldehyde levels after co-administration of ISO with alcohol. The aim of our study was to clarify whether the alcohol intolerance produced by ISO is indeed due to a typical DIS-like reaction. Methods: DIS and ISO were administered to Wistar rats and the hepatic ethanol (ETH) metabolizing enzyme activities along with the levels of brain monoamines were determined. Blood acetaldehyde levels were also evaluated after co-administration of ETH with DIS or ISO. Results: Despite inhibition of the hepatic ALDH, ISO did not result in elevated blood acetaldehyde levels after ETH administration, probably due to the induction of cytochrome P450 2E1 which theoretically leads to an increased elimination rate of acetaldehyde preventing its accumulation. Moreover, ISO produced some minor, but statistically significant, alterations in central monoaminergic neurotransmission. Conclusion: Our results demonstrate for the first time that despite ALDH inhibition ISO does not provoke a typical DIS-like reaction since it does not increase blood acetaldehyde levels after co-administration with ETH. The possibility that the ETH intolerance observed in ISO treatment is a central synergistic effect cannot be excluded.

Various hormonal and monoaminergic systems play determinant roles in the regulation of several cytochromes P450 (P450s) in the liver. Growth hormone (GH), prolactin, and insulin are involved in P450 regulation, and their release is under dopaminergic control. This study focused on the role of D-2-dopaminergic systems in the regulation of the major drug-metabolizing P450s, i.e., CYP3A, CYP2C, and CYP2D. Blockade of D-2-dopaminergic receptors with either sulpiride (SULP) or 4-(4-chlorophenyl)-1-(1H-indol-3-ylmethyl) piperidin-4-ol (L-741,626) markedly down-regulated CYP3A1/2, CYP2C11, and CYP2D1 expression in rat liver. This suppressive effect appeared to be mediated by the insulin/phosphatidylinositol 3-kinase/Akt/FOXO1 signaling pathway. Furthermore, inactivation of the GH/STAT5b signaling pathway appeared to play a role in D-2-dopaminergic receptor-mediated down-regulating effects on these P450s. SULP suppressed plasma GH levels, with subsequently reduced activation of STAT5b, which is the major GH pulse-activated transcription factor and has up-regulating effects on various P450s in hepatic tissue. Levels of prolactin, which exerts down-regulating control on P450s, were increased by SULP, which may contribute to SULP-mediated effects. Finally, it appears that SULP-induced inactivation of the cAMP/protein kinase A/cAMP-response element-binding protein signaling pathway, which is a critical regulator of pregnane X receptor and hepatocyte nuclear factor 1 alpha, and inactivation of the c-Jun N-terminal kinase contribute to SULP-induced down-regulation of the aforementioned P450s. Taken together, the present data provide evidence that drugs acting as D-2-dopaminergic receptor antagonists might interfere with several major signaling pathways involved in the regulation of CYP3A, CYP2C, and CYP2D, which are critical enzymes in drug metabolism, thus affecting the effectiveness of the majority of prescribed drugs and the toxicity and carcinogenic potency of a plethora of toxicants and carcinogens.

Stress is a critical player in the regulation of the major cytochrome P-450s ( CYPs) that metabolize the majority of the prescribed drugs. Early in life, maternal deprivation (MD) stress and repeated restraint stress (RS) modified CYP expression in a stress-specific manner. In particular, the expression of CYP3A1 and CYP2C11 was increased in the liver of MD rats, whereas RS had no significant effect. In contrast, hepatic CYP2D1/2 activity was increased by RS, whereas MD did not affect it. The primary effectors of the stress system, glucocorticoids and epinephrine, highly induced CYP3A1/2. Epinephrine also induced the expression of CYP2C11 and CYP2D1/2. Further investigation indicated that AR-agonists may modify CYP regulation. In vitro experiments using primary hepatocyte cultures treated with the AR-agonists phenylephrine, dexmedetomidine, and isoprenaline indicated an AR-induced upregulating effect on the above-mentioned CYPs mediated by the cAMP/protein kinase A and c-Jun NH2-terminal kinase signaling pathways. Interestingly though, in vivo pharmacological manipulations of ARs using the same AR-agonists led to a suppressed hepatic CYP expression profile, indicating that the effect of the complex network of central and peripheral AR-linked pathways overrides that of the hepatic ARs. The AR-mediated alterations in CYP3A1/2, CYP2C11, and CYP2D1/2 expressions are potentially connected with those observed in the activation of signal transducer and activator of transcription 5b. In conclusion, stress and AR-agonists may modify the expression of the major CYP genes involved in the metabolism of drugs used in a wide range of diseases, thus affecting drug efficacy and toxicity.

Supplemental Digital Content is available in the text., Metronomic oral vinorelbine (VRL; Navelbine) was shown in clinical trials to yield sustainable antitumor activity possibly through antiangiogenic mechanisms. We investigated the effects of protracted low-dose VRL on human umbilical vein endothelial cells, compared with a conventional chemotherapy model. Human umbilical vein endothelial cell cultures were treated with different concentrations of VRL (0.001 nmol/l to 1 mmol/l) for 4, 24 and 96 h. The effects of different drug concentrations on cell growth, cell cycle, apoptosis and expression of the angiogenesis-modulating genes interleukin-8, cyclooxygenase-2, CD36 and peroxisome proliferator-activated receptor γ were assessed using the metronomic or conventional chemotherapy model. Apoptosis and cell-cycle effects were assessed by flow cytometry. Gene expression was measured at the transcript level by quantitative reverse transcriptase-PCR, protein expression by immunoblotting and levels of proteins secreted in the cell medium by enzyme-linked immunosorbent assay. Activation of the nuclear factor-κB pathway was investigated by immunoblot analysis of cytosolic and nuclear protein extracts. The half-maximal inhibitory concentrations (IC50) of VRL at 96 h were four orders lower compared with those after a 24-h exposure (1.23 nmol/l vs. 32 mmol/l for VRL). Drug concentrations at high nanomolar levels and above, which are relevant to conventional pulsatile dosing of VRL, induced a dose-dependent and nuclear factor-κB-related increase in proangiogenic interleukin-8 and cyclooxygenase-2 and a decrease in the thrombospondin-1 receptor CD36 and peroxisome proliferator-activated receptor γ at mRNA and protein levels. In contrast, the opposite was evident with protracted picomolar to low nanomolar concentrations (metronomic dosing). Our data provide experimental support for metronomic VRL by showing that a protracted low dose outperforms pulsed high-dose administration in inducing antiangiogenic effects in proliferating human endothelial cells.

This study explored the behavioural, neurochemical and molecular effects of Delta9-tetrahydrocannabinol (Delta9-THC) and WIN55,212-2, in two rat phenotypes, distinguished on the basis of their vertical activity upon exposure to a novel environment, as high responders (HR) and low responders (LR). Motor effects were assessed under habituated vs. non-habituated conditions. Dopaminergic activity and DARPP-32 phosphorylation were measured in the dorsal striatum, nucleus accumbens, prefrontal cortex and amygdala. These cannabinoids influenced motor activity in a biphasic manner, i.e. low doses stimulated, whereas high doses suppressed motor activity. Dopamine (DA) biosynthesis was increased in most brain regions studied following Delta9-THC administration mainly in HR rats, and low-dose WIN55,212-2 increased DA biosynthesis in HR rats only. Both high and low doses of Delta9-THC increased DARPP-32 phosphorylation in most brain regions studied in both phenotypes, an effect that was also observed following high-dose WIN55,212-2 administration only in the striatum. The present results provide further support for a key role of cannabinoids in the regulation of motoric responses and elements of dopaminergic neurotransmission and reveal their complex differential effects in distinct rat phenotypes, as seen with other drugs of abuse. Int J Neuropsychopharmacol

PURPOSE: To determine the dose-limiting toxicities (DLTs) and the maximum tolerated doses (MTDs) of the paclitaxel, gemcitabine, oxaliplatin combination administered biweekly in patients with advanced solid tumors. PATIENTS AND METHODS: Patients received escalated doses of paclitaxel (starting dose: 100 mg/m(2)), gemcitabine (starting dose: 800 mg/m(2)) and oxaliplatin (starting dose: 50 mg/m(2)) on days 1 and 15 in cycles of every 4 weeks. DLTs were evaluated during the first cycle. RESULTS: Twenty-seven patients (median age 65 years) with performance status 0-1 were treated on six dose escalation levels. Eleven patients (40.7%) were chemotherapy naive, six (22.2%) had received 1 prior chemotherapy regimen and ten (37.1%) 2 or more. The DLT level was reached at the doses of paclitaxel 110 mg/m(2), gemcitabine 1,150 mg/m(2) and LOHP 70 mg/m(2). The dose-limiting events were grade 4 neutropenia and grade 3 febrile neutropenia. Neutropenia was the most common adverse event. A median of 3 cycles per patient was administered. One complete and five partial responses were observed in patients with ovarian carcinoma, NSCLC, urothelial cancer, mesothelioma and cancer of unknown primary. No pharmacokinetic drug interactions were detected. CONCLUSIONS: The recommended doses for future phase II studies of this combination are paclitaxel 110 mg/m(2), gemcitabine 1,000 mg/m(2) and oxaliplatin 70 mg/m(2) every 2 weeks. The regimen is generally well tolerated and merits further evaluation. Cancer Chemother Pharmacol

Rats of the Wistar/Af/Han/Mol/(Han 67) strain were preselected for the inducibility of the hepatic soluble aldehyde dehydrogenase, after treatment with phenobarbital (80 mg/kg daily, intraperitoneally, for 4 days) and open liver biopsy. Animals with highly induced aldehyde dehydrogenase also had a 50 and 40 % difference in the induction of D–glucuronolactone dehydrogenase and NADPH–cytochrome c reductase respectively. Other enzymes of the hepatic drug hydrox–ylation and glucuronidation did not show significant variation in the induction pattern between the two genetic groups. After inbreeding, the second filial generation was used in order to determine enzyme activities without any pretreatment. The basal activities of aldehyde and D–glucuronolactone dehydrogenase, but not of NADPH–cytochrome c reductase, were also different in the untreated animals. Urinary excretion of D–glucaric acid was the same in the two groups, both in the basal and the induced state.

The hepatic D-glucuronic acid pathway was studied in male rats after administration of 3, 3′, 5-triidothyronine (20 μg intraperitoneally daily, for three weeks). Some of the key enzymes of the pathway showed decreased activities during hyperthyroidism. D-glucuronolactone dehydrogenase, UDPglucuronosyltransferase and UDPglucuronic acid pyrophosphatase were not affected, whilst the activity of β-glucuronidase was significantly increased. D-Glucaric acid excretion in urine was enhanced and that of L-ascorbic acid was decreased. Phenobarbital administered to hyperthyroid and euthyroid animals (80 mg/kg intraperitoneally, daily, for 3 days) did not markedly affect the differences in the enzyme activities between the two groups. UDP-Glucuronosyltransferase and D-glucuronolactone dehydrogenase activities were induced, and in the case of UDPglucuronosyltransferase the induction was more pronounced during hyperthyroidism. D-Glucaric acid excretion in the urine was increased by phenobarbital treatment both in hyperthyroid and normal animals. L-Ascorbic acid excretion was also increased, but the increase was greater in euthyroid than in hyperthyroid animals. The results suggest that hyperthyroidism favours the metabolism of free D-glucuronic acid towards the formation of D-glucaric acid. Treatment with phenobarbital, however, also enhances to some extent the biosynthesis of L-ascorbic acid.

Rats of the Wistar/Af/Han/Mol/(Han 67) strain have previously been shown to respond in a variable way to phenobarbital treatment, as far as the induction of aldehyde dehydrogenase activity is concerned (Marselos 1976). This biochemical property is genetically determined and concerns the high-Km aldehyde dehydrogenase of the hepatic cytosol. In this study, administration of phenobarbital (1 mg/mo of drinking water, for 1 week) produces a uniform induction of aldehyde dehydrogenase in all rats, when measured with micromolar substrate concentration. The inducible low-Km enzyme of the cytosol is not genetically determined like the high-Km enzyme, and shows a wide specificity for aliphatic as well as for aromatic aldehydes. Despite the inducibility of the cytosolic enzymes, no alterations are found in the mitochondrial aldehyde dehydrogenase activities after phenobarbital treatment. The oxidation of D-glucuronolactone takes place only in the cytosol, and seems to be dependent on the low-Km aldehyde dehydrogenase. This is consistent with NMR studies, which showed that a very minimal amount of D-glucuronolactone is in aldehyde form under the measurement conditions usually applied. Further, the oxidation of D-glucuronolactone is also enhanced by phenobarbital in all rats without a genetic predisposition, and its dose-response curve is very similar to that of the low-Km aldehyde dehydrogenase. Acta Pharmacol Toxicol (Copenh)

Choline is an essential nutrient that seems to be involved in a wide variety of metabolic reactions and functions in both humans and rodents. Various pathophysiological states have been linked to choline deprivation (CD). The aim of the present study was to determine the effect of CD upon biochemical, histological and metabolic alterations induced by drugs that affect hepatic functional integrity and various drug metabolizing systems via distinct mechanisms. For this purpose, paracetamol (ACET) or phenobarbital (PB) were administered to male Wistar rats that were fed with standard rodent chow (normally fed, NF) or underwent dietary CD. The administration of ACET increased the serum aspartate aminotransferase levels in NF rats, while CD restricted this increase. On the other hand, ACET suppressed alkaline phosphatase levels only in CD rats. Moreover, CD prevented the PB-induced increase of the mitotic activity of hepatocytes. The administration of ACET down-regulated CYP1A2 and CYP2B1 expression in CD rats, while up-regulating them in NF rats. The administration of PB suppressed CYP1A2 apoprotein levels in CD rats, whereas the drug had no effect on NF rats. The PB-induced up-regulation of CYP2B, CYP2E1 and CYP1A1 isozymes was markedly higher in CD than in NF rats. In addition, PB increased glutathione-S-transferase activity only in CD rats. Hepatic glutathione content (GSH) was suppressed by ACET in NF rats, whereas the drug increased GSH in CD rats. Our data suggest that CD has a significant impact on the hepatic metabolic functions, and in particular on those related to drug metabolism. Thus, CD may modify drug effectiveness and toxicity, as well as drug-drug interactions, particularly those related to ACET and PB. J Appl Toxicol

The aim of the present study was to investigate the course of levodopa induced dyskinesia (LID) development in parkinsonian rats treated with several different levodopa dosing regiments. Administration of 6.25 mg/kg levodopa once daily did not induce any dyskinesia for the first 12.5 ± 2.5 days. Then, LID gradually increased in intensity reaching an AIMs score on day 40 of 6.3 ± 0.9. Treatment with 6.25 mg/kg of levodopa qid resulted in the rapid appearance of LID with a mean latency of 2 days and an AIMs score of 19.9 ± 2.9 on day 10. Levodopa (25 mg/kg) once daily induced severe LID from the second day of treatment reaching an AIMs score of 35 ± 3.2. In summary, the worst way for delivering levodopa was through intermittent administration of high doses. The daily cumulative dose of levodopa was found more important for LID induction than the total amount of levodopa received. In contrast, the best way to administer levodopa in respect to prevention/delay of LID was “low dopaminergic stimulation” with one low daily dose, instead of trying to achieve “continuous dopaminergic stimulation” using several levodopa doses throughout the day. The benefits of this strategy offered protection against severe dyskinesia even if subsequently subjects were switched to high dose levodopa. © 2007 Movement Disorder Society

The aim of this study was to investigate the effect of benzo(alpha)pyrene (B(alpha)P), a representative polycyclic aromatic hydrocarbon (PAH), on dopaminergic activity in brain. (B(alpha)P) altered dopaminergic activity in discrete regions of the rat brain, including the hippocampus, hypothalamus, caudate putamen and nucleus accumbens. Specifically, B(alpha)P increased DA levels in the hippocampus and DA turnover in the caudate putamen. In addition, B(alpha)P suppressed DA levels in the caudate putamen and DA turnover in the nucleus accumbens. B(alpha)P also altered the effect of several dopaminergic agents, L-DOPA, sulpiride and bromocriptine, on DA activity. In particular, B(alpha)P enhanced the L-DOPA-induced increase in the DA turnover ratio in the caudate putamen and increased DA levels in the nucleus accumbens. B(alpha)P also reversed the sulpiride-induced increase of DA turnover in the nucleus accumbens and the bromocriptine-induced increase of DA turnover in the hippocampus. In addition, DA turnover was increased by B(alpha)P in the nucleus accumbens and caudate putamen and DA levels were suppressed in the nucleus accumbens of bromocriptine treated rats, though the drug alone had no effect. These changes indicate that exposure to B(alpha)P and related compounds may affect dopaminergic function in discrete brain regions that are implicated in cognitive functions, psychosis, depression and Parkinson's disease, and may possibly interfere with their pharmacological intervention.

To determine the maximum tolerated doses (MTDs) and dose-limiting toxicities (DLTs) of pegylated liposomal doxorubicin (PLD), paclitaxel (PCX) and gemcitabine (GEM) combination administered biweekly in patients with advanced solid tumours. Twenty-two patients with advanced-stage solid tumours were treated with escalated doses of PLD on day 1 and PCX plus GEM on day 2 (starting doses: 10, 100 and 800 mg m(-2), respectively) every 2 weeks. DLTs and pharmacokinetic (PK) parameters of all drugs were determined during the first cycle of treatment. All but six (73%) patients had previously received at least one chemotherapy regimen. The DLT dose level was reached at PLD 12 mg m(-2), PCX 110 mg m(-2) and GEM 1000 mg m(-2) with neutropaenia being the dose-limiting event. Of the 86 chemotherapy cycles delivered, grade 3 and 4 neutropaenia occurred in 20% with no cases of febrile neutropaenia. Non-haematological toxicities were mild. The recommended MTDs are PLD 12 mg m(-2), PCX 100 mg m(-2) and GEM 1000 mg m(-2) administered every 2 weeks. The PK data revealed no obvious drug interactions. Biweekly administration of PLD, PCX and GEM is a well-tolerated chemotherapy regimen, which merits further evaluation in various types of solid tumours. Br J Cancer

Metronomic chemotherapy is the protracted, dense administration of low sub-toxic doses of chemotherapy, to inhibit tumor angiogenesis. Vinorelbine is an orally bioavailable vinca alkaloid shown to be useable for metronomic administration. In clinical trials, metronomic vinorelbine has been demonstrated to generate sustainable antitumor efficacy at low nanomolar (nM) concentrations with negligible toxicity. We sought to determine whether the clinically relevant metronomic concentration of vinorelbine is anti-angiogenic in vitro and whether hypoxia, often induced by anti-angiogenic therapy, modifies its effectiveness. We found that the metronomic concentration of 10 nM vinorelbine inhibited human umbilical vein endothelial cell (HUVEC) proliferation, migration, tube formation and sprouting. Severe hypoxia, did not affect the inhibitory effect of metronomic vinorelbine on migration, tube formation and sprouting. However, severe hypoxia reduced its anti-proliferative effect by decreasing its ability to induce G2/M block as it shifted the cell population to the G1 phase and decreased the fraction of the cells in the DNA synthesis S phase. Furthermore, the pro-apoptotic effects of 10 nM vinorelbine were also decreased. Metronomic vinorelbine decreased the Bcl-2/Bax ratio in normoxia whereas the ratio was reduced in severe hypoxia but unaltered by vinorelbine treatment. Akt signals to an anti-apoptotic pathway and we demonstrated that the Akt inhibitor V reversed the protective effect of severe hypoxia. Thus, we provide evidence for the anti-angiogenic basis of metronomic vinorelbine and we show that severe hypoxia mediates resistance to its anti-proliferative effect on endothelial cells. Akt warrants further investigation as a potential target to circumvent this hypoxic resistance.

CYP1A2, a principal catalyst for metabolism of various therapeutic drugs and carcinogens, among others, is in part regulated by the stress response. This study was designed to assess whether catecholamines and in particular adrenergic receptor-dependent pathways, modulate benzo(alpha)pyrene (B(alpha)P)-induced hepatic CYP1A2. To distinguish between the role of central and peripheral catecholamines in the regulation of CYP1A2 induction, the effect of central and peripheral catecholamine depletion using reserpine was compared to that of peripheral catecholamine depletion using guanethidine. The effects of peripheral adrenaline and L-DOPA administration were also assessed. The results suggest that alterations in central catecholamines modulate 7-methoxyresorufin O-demethylase activity (MROD), CYP1A2 mRNA and protein levels in the B(alpha)P-induced state. In particular, central catecholamine depletion, dexmedetomidine-induced inhibition of noradrenaline release and blockade of alpha(1)-adrenoceptors with prazosin, up-regulated CYP1A2 expression. Phenylephrine and dexmedetomidine-induced up-regulation may be mediated, in part, via peripheral alpha(1)- and alpha(2)-adrenoceptors, respectively. On the other hand, the L-DOPA-induced increase in central dopaminergic activity was not followed by any change in the up-regulation of CYP1A2 expression by B(alpha)P. Central noradrenergic systems appeared to counteract up-regulating factors, most likely via alpha(1)- and alpha(2)-adrenoceptors. In contrast, peripheral alpha- and beta-adrenoceptor-related signaling pathways are linked to up-regulating processes. The findings suggest that drugs that bind to adrenoceptors or affect central noradrenergic neurotransmission, as well as factors that challenge the adrenoceptor-linked signaling pathways may deregulate CYP1A2 induction. This, in turn, may result in drug-therapy and drug-toxicity complications.

RATIONALE: There is no consensus on the contribution of adenosine A(1) and A(2A) receptor blockade to motor-activating effects of caffeine. OBJECTIVE: Our aim was to use a detailed and continuous observational method to compare the motor effects induced by caffeine with those induced by selective A(1) and A(2A) receptor antagonists. METHODS: The behavioral repertoire induced by systemic administration of caffeine (3, 10, and 30 mg/kg), A(1) receptor antagonist 8-cyclopentyl-1,3-dimethylxanthine (CPT; 1.2, 4.8 and 7.2 mg/kg), and A(2A) receptor antagonist 3-(3-hydroxypropyl)-8-(m-methoxystyryl)-7-methyl-1-propargylxanthine phosphate disodium salt (MSX-3; 1, 3, and 10 mg/kg) was analyzed. The effects of pretreatment with the selective A(1) receptor agonist N (6)-cyclopentyladenosine (CPA; 0.1 mg/g) and the selective A(2A) receptor agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxyamidoadenosine (CGS 21680; 0.2 mg/kg) on the pattern of motor activation induced by caffeine, CPT, or MSX-3 were also examined. RESULTS: The pattern of behavioral activation induced by caffeine was better mimicked by CPT than by MSX-3. Coadministration of CPT and MSX-3 gave different results depending on the dose and the type of behavioral response. CPA was more effective at decreasing the activating effects of caffeine and CPT than those of CGS 21680. On the other hand, CGS 21680 was more effective at decreasing the activating effects of MSX-3 than those of caffeine or CPT. Factor analysis revealed a complex three-dimensional behavioral profile for caffeine that was similar to the profile for CPT and was different from the profile for MSX-3. CONCLUSIONS: The results indicate a predominant role for A(1) receptors in the motor-activating effects of acutely administered caffeine. Psychopharmacology (Berl)

Alpha2-adrenoceptor agents as well as stress affect the activity of several hepatic monoxygenases including those related to CYP1A enzymes. This study was therefore designed to assess the role of central and/or peripheral catecholamines and, in particular, of adrenoceptors in the regulation of B(alpha)P-induced cytochrome CYP1A1 expression. In order to discriminate the role of central from that of peripheral catecholamines in the regulation of CYP1A1 induction, the effect of central and peripheral catecholamine depletion using reserpine versus only peripheral catecholamine depletion using guanethidine was assessed. By using selected agonists and antagonists, the role of alpha and beta-adrenoceptors in the regulation of CYP1A1 induction was evaluated. The results showed that the central catecholaminergic system has a negative regulatory effect on 7-ethoxyresorufin O-deethylase (EROD) inducibility by benzo(alpha)pyrene (B(alpha)P), and that this may be mediated via alpha1-, alpha2- and beta-adrenoceptors. Specifically, stimulation of alpha2-adrenoceptors with dexmedetomidine and blockade of alpha1- or beta-adrenoceptors with prazosin or propranolol respectively, resulted in a further increase of EROD inducibility. Adrenoceptors were found to be involved in the regulation of the CYP1A1 gene at mRNA level. Both, reduced noradrenaline release in central nervous system induced with dexmedetomidine and central catecholamine depletion, as well as blockade of central alpha1-adrenoceptors induced with prazosin, all were associated with up-regulation of CYP1A1 expression. In contrast, stimulation of central beta-adrenoceptors with isoprenaline resulted in a down-regulation of CYP1A1 expression. Our observations indicate that drugs, which stimulate or block adrenoceptors and catecholamine release may lead to complications in drug therapy and modulate the toxicity or carcinogenicity of drugs that are substrates for the CYP1A1. Biochem Pharmacol

The present study investigated the involvement of catecholamines in stress-mediated alterations in CYP1A1 induction by benzo()pyrene (B()P) inWistar rats. This was achieved by measuring EROD activity and CYP1A1 mRNA levels in liver tissue from rats exposed to restraint stress and B()P coupled with pharmacological modulation of peripheral and central catecholamine levels and different adrenoceptors. In a state of reserpine-induced central and peripheral catecholamine depletion, stress strongly suppressed EROD induction. Peripheral catecholamines do not appear to play a critical role in the stress-mediated modulation of EROD inducibility by B()P. Stress did not alter EROD inducibility by B()P when peripheral catecholamines were either depleted by guanethidine or supplemented by peripheral adrenaline administration. On the other hand, central noradrenergic systems appear to have a role in the stress-mediated changes in B()P-induced EROD activity and Cyp1A1 gene expression. Stimulation or blockade of noradrenaline release with atipamezole and dexmedetomidine, respectively, significantly modified the up-regulating effect of stress. Alpha1 adrenoceptors also appear to participate in the effect of stress on EROD inducibility. Alpha1-blockade with prazosin potentiated the up-regulating effect of stress, possibly preventing the down-regulating effect of noradrenaline. Beta adrenoceptors also seem to be involved directly or indirectly in the stress-mediated modulation of Cyp1A1, as propranolol (beta-antagonist) blocked the down-regulating effect of stress on B()P-induced Cyp1A1 gene expression. Plasma corticosterone alterations after stress were not related to alterations in the B()P-induced EROD activity and Cyp1A1 gene expression. In conclusion, stress appears to interfere in the regulation of B()P-induced hepatic CYP1A1 in an unpredictable manner and via signalling pathways not always directly related to catecholamines. In particular, whenever drug treatment disrupts noradrenergic neurotransmission, other stress-stimulated factors appear to modify the induction of CYP1A1. In summary, regulation of induction of hepatic CYP1A1 during stress appears to involve various components of the stress system, including central and peripheral catecholamines, which interact in a complex manner, yet to be elucidated. © 2003 Elsevier Ireland Ltd. All rights reserved.

Antihistamines , such as chlorpheniramine (CPA), are lipophilic agents which readily cross the blood–brain barrier , producing sedation in 10–25% of users. However, with excessive doses instead of sedation a stimulating action has been reported. The aim of the present study was to investigate the influence of CPA on the locomotor activity of the rat in relation to its effects on brain biogenic monoamines . Wistar rats were given CPA (40 mg/kg, i.p.) and locomotor activity was measured in a photocell cage. Body temperature was also monitored. In addition, in three brain subregions (striatum, hypothalamus , and midbrain), the levels of 5-HT, NA, DA, as well as their metabolites, were determined by HPLC. Soon after injection, CPA produced a significant increase in locomotor activity, while a hypothermic response was also induced. In striatum and hypothalamus, which are known to be rich in postsynaptic 5-HT 1A receptors, we found a significant time-dependent increase of 5-HT, correlated with the clearly enhanced locomotor activity of the animals. On the contrary, in midbrain, where presynaptic 5-HT1A receptors are dominating, no changes could be detected in 5-HT. In all three brain regions measured, 5-HIAA levels were decreased. The levels of the other brain monoamines were only marginally affected. In support of a role in receptor specificity, pretreatment with the 5-HT 1A receptor agonist 8-OH-DPAT (1.25 mg/kg, i.p., two times) or with the 5-HT1A/B receptor antagonist pindolol (30 mg/kg, i.p., two times), enhanced or blocked, respectively, the hyperlocomotion induced by CPA. These findings suggest that the central serotonergic system may play a key role in the locomotor stimulant effects of CPA in the rat. Moreover, this behavioral component of CPA seems to be primarily mediated via the postsynaptic 5-HT1A receptors.

Ethnopharmacological relevance: This paper focuses on the plants quoted in the recipes of the first chapter entitled “About the Antidotes” belonging to the first and largest section “Element Alpha” of Nikolaos Myrepsos׳ Dynameron, a medieval medical manuscript. Nikolaos Myrepsos was a Byzantine physician at the court of John III Doukas Vatatzes at Nicaea (13th century). He wrote in Greek a rich collection of 2667 recipes, the richest number known in late Byzantine era, conventionally known as Dynameron and divided into 24 sections, the “Elements”. The only existing translation of this work is in Latin, released in 1549 in Basel by Leonhart Fuchs. Since no other translation has ever been made in any language, this work still remains poorly known. Materials and Methods: Our primary source material was the codex written in 1339 and kept in the National Library of France (in Paris) under the number grec. 2243. For comparison, all the other codices, which contain the entire manuscript, have also been studied, namely the codices EBE 1478 (National Library of Greece, Athens), grec. 2237 and grec. 2238 (both in Paris), Lavra E 192 (Mont Athos, Monastery of Megisti Lavra), Barocci 171 (Oxford) and Revilla 83 (Escorial). Results: The exhaustive study of the “About the Antidotes” led us to the interpretation of 293 plant names among which we recognized 39 medicinal plants listed by the European Medicines Agency, (Herbal Medicines, www.ema.eu); the therapeutic indications of some of them provided by Myrepsos were similar or related to their current ones, as given in their monographs. The plants belong to various families of which the most frequent are: Apiaceae 10.6%; Lamiaceae 9.2%; Asteraceae 8.9%; Fabaceae 6.8% and Rosaceae 5.1%. The most frequently mentioned plants even under several different names are the following: Apium graveolens L., Crocus sativus L., Nardostachys jatamansi (D. Don) DC., Zingiber officinale Roscoe, Rosa centifolia L., Syzygium aromaticum (L.) Merr. & L.M. Perry, Papaver somniferum L., Costus sp., Petroselinum crispum (Mill.) Fuss, Anethum graveolens L., Foeniculum vulgare Mill., Daucus carota L. Conclusions: This research led us to the conclusion that the content of “About the Antidotes” is a valuable source for the study of recipes based mainly on medicinal plants, most of them inherited from classic ancient Greek and Hellenistic periods.

Dopaminergic systems regulate the release of several hormones including growth hormone (GH), thyroid hormones, insulin, glucocorticoids and prolactin (PRL) that play significant roles in the regulation of various Cytochrome P450 (CYP) enzymes. The present study investigated the role of dopamine D2-receptor-linked pathways in the regulation of CYP1A1, CYP1A2 and CYP1B1 that belong to a battery of genes controlled by the Aryl Hydrocarbon Receptor (AhR) and play a crucial role in the metabolism and toxicity of numerous environmental toxicants. Inhibition of dopamine D2-receptors with sulpiride (SULP) significantly repressed the constitutive and benzo[a]pyrene (B[a]P)-induced CYP1A1, CYP1A2 and CYP1B expression in the rat liver. The expression of AhR, heat shock protein 90 (HSP90) and AhR nuclear translocator (ARNT) was suppressed by SULP in B[a]P-treated livers, whereas the AhRR expression was increased by the drug suggesting that the SULP-mediated repression of the CYP1 inducibility is due to inactivation of the AhR regulatory system. At signal transduction level, the D2-mediated down-regulation of constitutive CYP1A1/2 and CYP1B1 expression appears to be mediated by activation of the insulin/PI3K/AKT pathway. PRL-linked pathways exerting a negative control on various CYPs, and inactivation of the glucocorticoid-linked pathways that positively control the AhR-regulated CYP1 genes, may also participate in the SULP-mediated repression of both, the constitutive and induced CYP1 expression. The present findings indicate that drugs acting as D2-dopamine receptor antagonists can modify several hormone systems that regulate the expression of CYP1A1, CYP1A2 and CYP1B1, and may affect the toxicity and carcinogenicity outcome of numerous toxicants and pre-carcinogenic substances. Therefore, these drugs could be considered as a part of the strategy to reduce the risk of exposure to environmental pollutants and pre-carcinogens.

Disulfiram is used in the treatment of chronic alcoholism, because of the unpleasant symptoms it provokes after ethanol intake. The underlying mechanism is believed to be the accumulation of acetaldehyde in the blood, due to inhibition of the liver aldehyde dehydrogenases. In addition, it is known that disulfiram also has some neurotoxic properties. The aim of our study was to investigate the relationship between the pharmacological and neurotoxicological properties of disulfiram with respect to the doses applied. Increasing doses of disulfiram (25, 50, 75, 100 and 150 mg/kg) were administered intraperitoneally to Wistar rats and the hepatic enzyme activities of alcohol and aldehyde dehydrogenases were measured. Also, in two brain subregions (midbrain and hypothalamus) the levels of noradrenaline, dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid were determined. The higher dose of disulfiram (150 mg/kg) produced lethal effects in all treated animals. Aldehyde dehydrogenase activities were inhibited by disulfiram in a dose-dependent way, while alcohol dehydrogenase was not affected at all. Concerning the levels of brain biogenic amines, disulfiram produced a significant reduction in noradrenaline and an increase in dopamine levels in both structures of the brain, in a dose-dependent way. However, the lowest dose applied (25 mg/kg) had no effects on brain catecholamines. It is known that high doses of disulfiram may cause severe encephalopathy and peripheral neuropathy in humans, which could be attributed to the impairment of the metabolism of brain biogenic amines, due to inhibition of dopamine-beta-hydroxylase. Our experimental data show that disulfiram affects the level of brain biogenic amines at dose levels higher than those inhibiting the activity of aldehyde dehydrogenase. Therefore, in clinical practice 'disulfiram reaction' could still be achieved with a low dosage regimen not producing neurotoxicity

The effects of two different protocols of 3-methylcholanthrene (3MC) and aspirin co-administration were studied in a well-established human hepatoma cell line (HepG2). During this work, we have performed toxicity tests for cell viability:cell proliferation as well as studies on the expression of ALDH3A1 after exposure of HepG2 cells to 3MC or:and aspirin. For the evaluation of toxic concentrations of 3MC and aspirin, the WST-1 test was used. WST-1 is a reliable cytotoxicity test which is based on the cleavage of the tetrazolium salt WST-1 to formazan by mitochondrial enzymes of living cells. A broad range of drug concentrations for either 3MC (0.25‐50.0 mM) or aspirin (0.05‐10.0 mM) were used for cell exposure, in several periods of time. The expression of ALDH3A1 in HepG2 cells showed typical time- and dose-response curves of induction after application of 3MC (1‐5 days, 1.5‐5.0 mM, respectively). When cells were firstly exposed to 3MC (2.5 and 5.0 mM) and then to aspirin (0.25 mM), the induced ALDH3A1 activity was further enhanced in a statistically significant way (PB0.05). On the contrary, when aspirin application was preceded 3MC exposuring a statistically significant decrease in ALDH3A1 inducibility was observed, as compared with the application of 3MC alone. © 2001 Elsevier Science Ireland Ltd. All rights reserved.

The role of stress on the inducibility by benzo[alpha]pyrene (B[alpha]P), a representative polycyclic aromatic hydrocarbon, of several drug-metabolizing enzymes was investigated in rats, using restraint stress and mild unpredictable stress as models of psychological stress. Restraint stress was found to significantly suppress basal ethoxyresorufin 7-dealkylase (EROD) and pentoxyresorufin 7-dealkylase (PROD) activities (two-fold). In contrast, mild unpredictable stress markedly increased basal EROD activity, while PROD activity was not affected. In addition, both types of stress resulted in a significant reduction of basal p -nitrophenol hydroxylation (PNP). It is worth noting that restraint stress greatly enhanced the inducibility of EROD, methoxyresorufin 7-dealkylase (MROD) and to a lesser extent PROD activities by B[alpha]P, while mild unpredictable stress had no, or only a mild effect on the inducibility of cytochrome P450s (CYPs) by B[alpha]P. In conclusion, psychological stress may modulate different enzymatic systems which are vital elements of the detoxification mechanisms of the body. The two distinct types of psychological stress used in this study appear to affect the enzymatic systems under investigation in a stress-specific manner at the basal level and at the induced state by B[alpha]P.

Two kaempferol coumaroyl glycosides (i.e. platanoside and tiliroside) isolated from the methanolic extract of Platanus orientalis L. buds, were examined for their in vitro cytotoxic activity against a panel of human leukaemic cell lines. Platanoside (1) exhibited cytotoxic activity against most of the cell lines tested, while tiliroside (2) was active against two of the nine tested cell lines. Compound 1, was examined for its effect on the uptake of [(3)H]thymidine as a marker of DNA synthesis. Kaempferol was used as a control. 2000 Academic Press@p$hr Copyright 2000 Academic Press. Pharmacol Res

Sclareol, a labdane-type diterpene, was tested for cytotoxic effect against a panel of established human leukemic cell lines. The compound showed an IC50 lower than 20 microg/ml in most cell lines tested, while it was higher for resting peripheral blood mononuclear leukocytes (PBML). Furthermore, the compound was tested for cytostatic activity against four of the leukemic cell lines used. At a concentration of 20 microg/ml the compound showed a significant cytostatic effect as soon as 4 h after continuous incubation against two from B and two from T lineage cell lines. The morphology and the kind of death induced from sclareol in three cell lines, was also investigated. The effect of sclareol on the cell cycle progression of two cell lines, using flow cytometry, was examined. The results show that sclareol kills cell lines, through the process of apoptosis. The appearance of the apoptotic signs is time and dose dependent. From the flow cytometry experiments, a delay of the cell population on G0/1 seems to take place. This is the first report, that a labdane type diterpene kills tumor cells via a phase specific mechanism which induces apoptosis. Leuk Res

Two rat liver cytosolic aldehyde dehydrogenases, ALDH1 and ALDH3c, are of particular interest because they are inducible by different classes of xenobiotics. ALDHI is mainly increased by phenobarbital-type inducers; polycyclic aromatic hydrocarbons (PAHs), such as 3- methylcholanthrene (3MC), increase ALDH3c enzyme activity in all rat species currently tested. In addition, ALDH3c has been found to reflect the subfamily CYPIA of cytochrome P-450, as well as other enzymes functionally related to the aryl hydrocarbon receptor (the "Ah-receptor enzyme battery"), which is activated by the same type of inducers. In the present study we investigated whether the induction of ALDH3c might be connected with a chemically produced aseptic inflammation of the hepatocyte. To answer this question, we examined the relationship between the induction of ALDH3c by 3MC and the arachidonic acid cascade. Different non-steroid anti-inflammatory drugs (NSAIDs) were tested in combination with 3MC and in post-treatment. The 3MC-induced ALDH3c activity was significantly diminished by the co-administered anti-inflammatory agents. Two microsomal enzyme activities (ethoxyresorufin-O-deethylase, EROD; aryl-hydrocarbon-hydroxylase, AHH) were also decreased. Similar results were obtained with NSAIDs administered to animals pre- treated with 3MC, as far as the ALDH3c activity was concerned, but not for the microsomal enzyme activity (EROD and AHH). In conclusion, the induction of ALDH3c, after PAH treatment, may be related to an aseptic inflammation of the hepatocytes. This effect is reduced by commonly used steroid and non-steroid anti- inflammatory drugs, and although the mechanism of inhibition has not yet been elucidated, it appears likely that ALDH3c and CYP1A activities are associated with the "acute phase" response. Eur J Drug Metab Pharmacokinet

Central to the appropriate regulation of behavioral and physiological changes induced by stress are the noradrenergic neuronal systems which have been implicated in a large number of stress-induced pathophysiological states. Endoplasmic reticulum-bound cytochromes (CYPs) play a crucial role in drug metabolism, resulting in deactivation or formation of reactive derivatives. In turn, these products may be responsible for the chemotherapeutic, mutagenic or carcinogenic properties of the parent compound. The present study assesses the effect of a specific alpha2- adrenoceptor agonist, dexmedetomidine (DEXT), on stress-induced modification of cytochrome activity in rats using a restraint stress model. The results indicated that activation of the alpha2-adrenoceptor with DEXT did not alter basal hepatic methoxyresorufin 7-dealkylase (MROD). On the other hand, it appeared to enhance MROD in benzo[alpha]pyrene (B[alpha]P) treated animals. Of interest was the finding that stress blocked DEXT-induced MROD enhancement in B[alpha]P- treated rats. In addition, DEXT had no effect on basal hepatic pentoxyresorufin 7-dealkylase (PROD), while it further enhanced the strong induction by B[alpha]P. Stress was also found to block this effect. Hepatic ethoxyresorufin 7-dealkylase (EROD) activity was strongly increased by B[alpha]P; this effect was enhanced by DEXT. In contrast, the DEXT enhanced induction was further strengthened by stress. These findings suggest that alpha2-adrenoceptors may modulate the induction of cytochromes CYP1A1, 1A2 and 2B1 by B[alpha]P in rats and that stress may modify this process. In particular, stress may regulate the inducibility of P4501A1 activity by B[alpha]P via mechanisms related to alpha2-adrenoceptors.

Repeated treatment with 3-methylcholanthrene (MC; 25 mg/kg body weight, i.p., two times per week, 1 month) in both male and female Wistar rats resulted in decreased performance in two sessions of a two-way active avoidance procedure. In addition, young male rats that were injected repeatedly with MC prepubertally showed diminished acquisition in conditioned avoidance behavior during both sessions. It appears that MC can alter both avoidance acquisition and retention test performance in adult male and female rats, as well as in young males. This effect was not associated with alterations in sex hormone levels. The findings of this study suggest a significant influence of MC on specific mental functions. Pharmacol Biochem Behav

A survey was conducted among 1,057 students of the University of Ioannina, Greece, investigating the prevalence of cannabis use, the attitude to and the knowledge on cannabis, as well as the intention of students to experiment with other illicit drugs. Students who had tried cannabis amounted to 17.9%, but regular users were 8.7% of the sample. There was an obvious predominance of 'male users' (14.4% of the male sample) over 'female users' (5.1% of the female sample). Age was also correlated with cannabis use, since students older than 24 years predominated over the younger ones among regular users (20.8 vs. 6.5%, respectively). Heavy daily tobacco smoking (20 cigarettes or more) and use of psychotropic drugs were also among the factors strongly correlated with cannabis use. The students who admitted a regular use of cannabis expressed their doubt on the harmfulness of the drug and its dependence liability. As a rule, they held strong views on issues pertaining to the properties of cannabis, whereas most of the other respondents often admitted ignorance on the same issues. In addition, regular users declared their willingness to experiment with other illicit drugs, such as cocaine and heroin, if they were available. As for the general attitude towards illicit drugs, cocaine seems to hold a more acceptable place than heroin for all students included in our epidemiological sample. European Addiction Research

Using six ligands that bind to four different receptors in the nuclear steroid/thyroid hormone superfamily, we have examined the effects of these chemicals on induction of the cytosolic aldehyde dehydrogenase (ALDH3c) activity by 3-methylcholanthrene (3MC) in rat liver and uterus. In contrast to negligible activities in the untreated rat, ALDH3c enzyme activities are induced after a single dose of 3MC. Hepatic ALDH3c induction is decreased 60% to 90% when 3MC is administered together with any of the following ligands: estradiol, testosterone, progesterone, hydrocortisol, diethylstilbestrol, or tamoxifen. None of these same doses of chemicals, administered alone, affects ALDH3c enzyme activity. In addition, when these ligands are injected 2 days after 3MC, no changes are observed in liver or uterus ALDH3c induction. These results suggest that ligands that bind to different receptors in the nuclear steroid/thyroid hormone superfamily might inhibit the ALD3H3c induction process by polycyclic aromatic hydrocarbons; the molecular mechanism(s) of this inhibitory effect is not yet understood. Biochem Pharmacol

Various hormonal and monoaminergic systems play determinant roles in the regulation of several cytochromes P450 (P450s) in the liver. Growth hormone (GH), prolactin, and insulin are involved in P450 regulation, and their release is under dopaminergic control. This study focused on the role of D₂-dopaminergic systems in the regulation of the major drug-metabolizing P450s, i.e., CYP3A, CYP2C, and CYP2D. Blockade of D₂-dopaminergic receptors with either sulpiride (SULP) or 4-(4-chlorophenyl)-1-(1H-indol-3-ylmethyl)piperidin-4-ol (L-741,626) markedly down-regulated CYP3A1/2, CYP2C11, and CYP2D1 expression in rat liver. This suppressive effect appeared to be mediated by the insulin/phosphatidylinositol 3-kinase/Akt/FOXO1 signaling pathway. Furthermore, inactivation of the GH/STAT5b signaling pathway appeared to play a role in D₂-dopaminergic receptor-mediated down-regulating effects on these P450s. SULP suppressed plasma GH levels, with subsequently reduced activation of STAT5b, which is the major GH pulse-activated transcription factor and has up-regulating effects on various P450s in hepatic tissue. Levels of prolactin, which exerts down-regulating control on P450s, were increased by SULP, which may contribute to SULP-mediated effects. Finally, it appears that SULP-induced inactivation of the cAMP/protein kinase A/cAMP-response element-binding protein signaling pathway, which is a critical regulator of pregnane X receptor and hepatocyte nuclear factor 1α, and inactivation of the c-Jun N-terminal kinase contribute to SULP-induced down-regulation of the aforementioned P450s. Taken together, the present data provide evidence that drugs acting as D₂-dopaminergic receptor antagonists might interfere with several major signaling pathways involved in the regulation of CYP3A, CYP2C, and CYP2D, which are critical enzymes in drug metabolism, thus affecting the effectiveness of the majority of prescribed drugs and the toxicity and carcinogenic potency of a plethora of toxicants and carcinogens.

Data on the mutagenicity, developmental toxicity and carcinogenicity of cannabis are reviewed in this article. The available evidence on the possible mutagenic effects of cannabinoids is still inconclusive. There is no consensus on the induction of point mutations, while some experimental results suggest that cannabinoids may cause chromosomal damage. Concerning the developmental effects of cannabis, an increased embryolethality and somatic growth retardation have been observed in animals, as well as changes in motor behaviour, after perinatal exposure to cannabinoids. An elevated risk for infertility has been suggested for women smoking marijuana. On the other hand, intrauterine exposure to cannabinoids may be followed by changes of behaviour later in childhood. Finally, the experimental work concerning the possible carcinogenic action of cannabinoids has shown that cannabis acts as a tumour promotor in animals. Epidemiological studies have incriminated cannabis smoking for the development of head and neck carcinomas and for carcinomas of the respiratory tract in humans, but several confounding factors have rendered this evidence inconclusive. At least part of the great popularity of cannabis smoking is due to the widespread belief that it is harmless. However, the studies presented in this review show that, despite their low acute toxicity profile, cannabinoids represent several risks in terms of chronic toxicity. Addict Biol

The Flinders Sensitive Line (FSL) rat model of depression exhibits some behavioral, neurochemical, and pharmacological features that have been reported in depressed patients and has been very effective in screening antidepressants. Major factor that determines the effectiveness and toxicity of a drug is the drug metabolizing capacity of the liver. Therefore, in order to discriminate possible differentiation in the hepatic drug metabolism between FSL rats and Sprague-Dawley (SD) controls, their hepatic metabolic profile was investigated in this study. The data showed decreased glutathione (GSH) content and glutathione S-transferase (GST) activity and lower expression of certain major CYP enzymes, including the CYP2B1, CYP2C11 and CYP2D1 in FSL rats compared to SD controls. In contrast, p-nitrophenol hydroxylase (PNP), 7-ethoxyresorufin-O-dealkylase (EROD) and 16alpha-testosterone hydroxylase activities were higher in FSL rats. Interestingly, the wide spread environmental pollutant benzo(alpha)pyrene (B(alpha)P) induced CYP1A1, CYP1A2, CYP2B1/2 and ALDH3c at a lesser extend in FSL than in SD rats, whereas the antidepressant mirtazapine (MIRT) up-regulated CYP1A1/2, CYP2C11, CYP2D1, CYP2E1 and CYP3A1/2, mainly, in FSL rats. The drug also further increased ALDH3c whereas suppressed GSH content in B(alpha)P-exposed FSL rats. In conclusion, several key enzymes of the hepatic biotransformation machinery are differentially expressed in FSL than in SD rats, a condition that may influence the outcome of drug therapy. The MIRT-induced up-regulation of several drug-metabolizing enzymes indicates the critical role of antidepressant treatment that should be always taken into account in the designing of treatment and interpretation of insufficient pharmacotherapy or drug toxicity. Prog Neuropsychopharmacol Biol Psychiatry

PURPOSE: Patients with recurrent and/or metastatic squamous cell carcinoma of the head and neck (RM-SCCHN) bear a grave prognosis. There are unmet needs for the development of novel agents for this incurable disease. Angiogenesis is an important biological process in SCCHN. We, therefore, evaluated the activity and safety of sunitinib, an oral tyrosine kinase inhibitor that targets multiple receptors, in patients with RM-SCCHN. PATIENTS AND METHODS: Seventeen patients were treated with sunitinib 50 mg per day administrated in 4-week cycles followed by a rest period of 2 weeks. Sunitinib and SU012662 plasma levels were determined based on a validated liquid chromatography-tandem mass spectrometry method and pharmacokinetic data were fitted in a non-compartmental analysis. RESULTS: Totally, 28 6-week cycles of treatment with sunitinib were administered (median, 2 cycles). Only three patients demonstrated stabilization of the disease; therefore, the study had to be terminated prematurely due to futility. Grade 3 toxicities, apart from fatigue, were infrequent. Other frequently reported side effects were skin discoloration, neutropenia, and thrombocytopenia. Ten various bleeding complications were reported in seven patients. Mean maximum concentrations (C(max)) were reached during the first day of treatment for sunitinib at 38.98 (+ or - 22.66) ng/ml and for SU012662 at 11.12 (+ or - 24.57) ng/ml. Our results showed that SU012662 has a longer half-life and a larger volume of distribution than the parent drug sunitinib. None of the biological markers tested was of any prognostic value. CONCLUSIONS: According to our findings, sunitinib monotherapy was not proven active in RM-SCCHN, and no further development of the drug in this indication is warranted. Cancer Chemother Pharmacol