Interethnic and interindividual variabilities of platelet sulfotransferases activity in Italians and Finns

Objective: The aim of this investigation was to see whether there was interethnic variability in the platelet activities of catechol- and phenol sulfotransferases in Italians and Finns. Methods: The activities of catechol- and phenol sulfotransferases were measured in platelets obtained from 103 Italian and 74 Finnish individuals. Blood donors were obtained from healthy volunteers free from drugs and without apparent disease. The activities of catechol- and phenol sulfotransferases were measured with 60 μM dopamine and 4 μM 4-nitrophenol as substrates, respectively Results: The activity of catechol sulfotransferase was not gender dependent and the median estimates (pmol/min/mg) were 9.10 in Italians and 6.37 in Finns (P = 0.0018). The activity of phenol sulfotransferase activity was gender dependent in Finns but not in Italians. The median estimates (pmol/min/mg) were 3.81 in Finnish men and 1.18 in Finnish women (P = 0.0007). In Italian men and women, the median estimates (pmol/min/mg) of phenol sulfotransferase activity were 1.25 and 1.24, respectively (NS). Conclusion: This study shows that platelet catechol sulfotransferase activity is greater in Italians than Finns and that the activity of phenol sulfotransferase is gender regulated in Finns but not in Italians. Thus, interethnic differences exist in platelet sulfotransferases between Italians and Finns. Received: 16 April 1999 / Accepted in revised form: 20 August 1999     

Evaluation of in vitro toxicity of N,N-dimethyl-2-propen-1-amines isomers

The trypanocidal activities of cis-3-(4'-bromo[1,1'-biphenyl]-4-yl)- 3-(phenyl)-N,N-dimethyl-2-propen-1-amine (Vb) and cis-3-(4'-bromo[1,1'-biphenyl]-4-yl)-3-(4-bromophenyl)-N,N-dimethyl-2- propen-1-anine (Vg) appeared 6.3 and 3.5 fold more active than the trans-isomers, respectively. Multi-endpoints for toxicity were also applied. Neutral red uptake (NRU), tetrazolium salt reduction (MTT), DNA content on V79 fibroblast cell culture and acute toxicity von E. coli were measured. The IC50 through DNA contents was lower for the cis-isomers in both series of compounds 5b: 7.8 microM and 5g: 5.2 microM). NRU values for derivative 5b in isomeric mixture shows the same value as the isolated isomers however, in the case of 5g a more significant toxicity of the cis-isomer was found. MTT values show that 5g is more toxic than 5b. In both cases, the acute toxicity of the trans-isomers was higher than that of the cis-isomers.     

Bremazocine reduces unrestricted free-choice ethanol self-administration in rats without affecting sucrose preference

It has been postulated that opioid systems in the brain may play a role in ethanol reinforcement. In this respect, μ- and δ-opioid receptors may mediate the rewarding effects whereas κ receptors are thought to mediate the aversive effects of opioids. Accordingly, long-acting benzomorphans such as bremazocine, that simultaneously act as μ and δ receptor antagonists and κ receptor agonists may be particularly effective in reducing ethanol self-administration. Therefore, we studied the effect of bremazocine on oral ethanol self-administration in rats using a paradigm [unrestricted free-choice drinking of 10% (v/v) ethanol], previously shown to cause long-term neuroadaptations in the nucleus accumbens and caudate putamen. Bremazocine (0.1 mg/kg, once daily for five consecutive days) reduced ethanol drinking by about 50% during the active period of the animals, whereas the intake of sucrose (3–10% w/v) was affected neither in naive nor in ethanol-experienced rats. This effect of bremazocine appeared not to be secondary to its acute sedative effect or the slight increase in total fluid consumption. Unlike bremazocine, the selective κ-opioid receptor agonist U50,488H (10 mg/kg, once daily) inhibited ethanol drinking only during the first of 5 treatment days and the opioid receptor antagonist naltrexone (0.3–10 mg/kg, once daily) only caused a modest (about 20%) suppression of ethanol drinking during the first hours after drug injection. Thus, bremazocine appears to be far more potent than the clinically applied drug naltrexone in this respect. Our data further support the role of opioid receptors in ethanol reinforcement and indicate that long-acting mixed-action opioids such as bremazocine may be useful as adjuvants for the clinical management of ethanol addiction. Received: 1 July 1998/Final version: 3 September 1998     

Dopaminergic mechanisms mediating the incentive to seek cocaine and heroin following long-term withdrawal of IV drug self-administration

  Rationale: The neurobiological mechanisms underlying the persistence of drug craving in detoxified addicts are still poorly understood. Objective: The present study was designed to evaluate dopaminergic mechanisms in drug-seeking behaviour following long-term (>3 weeks) extinction of IV drug self-administration in rats. Methods: To that end, we studied the effects of direct and indirect dopamine (DA) agonists on reinstatement of previously extinguished responding for heroin (50 μg/kg per injection; 14–15 daily 3-h sessions) and cocaine (500 μg/kg per injection; 10–11 daily 2-h sessions). Results: In animals with a cocaine history, priming with cocaine, the selective DA reuptake inhibitor GBR-12909 and the DA D₂ receptor agonist quinpirole resulted in robust and selective reinstatement of non-reinforced nose poking behaviour in the previously drug-paired hole. In contrast, the D₁ agonist SKF-82958 failed to reinstate responding and the non-selective DA agonist apomorphine even suppressed responding in these animals. In heroin-trained rats, heroin and GBR-12909 strongly reinstated responding, whereas all direct DA agonists were ineffective. Again, the two highest doses of apomorphine decreased responding in these animals. In a parallel study, the ability of DA ligands to express behavioural sensitization in animals pretreated with amphetamine or morphine was evaluated. Interestingly, all agonists that reinstated responding in the present study caused expression of locomotor sensitization and vice versa. Conclusions: The differences between direct and indirect agonists indicate a clear, but complex, involvement of DA in drug-seeking behaviour long after detoxification. Moreover, the results show an important role of D₂ receptor activation in the persistence of cocaine- but not heroin-seeking behaviour. Finally, the results from both studies suggest a relationship between drug-induced reinstatement and drug hyperresponsiveness in long-term abstinent rats. Received: 14 May 1998 / Final version: 1 December 1998     

Phyllanthus orbicularis aqueous extract: cytotoxic, genotoxic, and antimutagenic effects in the CHO cell line

The present work evaluates the cytotoxic, genotoxic, and antimutagenic effects of Phyllanthus orbicularis (plant of genus Phyllantus) aqueous extract in Chinese hamster ovary (CHO) cells. P. orbicularis aqueous extracts are used in Cuban traditional medicine for their antiviral activity against Hepatitis B virus and A and B flu virus. The cytotoxicity of the extract was tested by means of colony-forming ability and growth-inhibition assays as well as by measuring the mitotic index. Apoptosis induction and cell-cycle kinetics were analyzed by cytofluorimetric methods. Chromosome aberration assays were performed to study the genotoxic and antimutagenic activity of the extract. Results show that doses of up to 100 microg/ml of the extract did not induce any cytotoxic effects. Cell survival and mitotic index decreased significantly at doses higher than 100 microg/ml as a function of dose as well as of treatment time. Moreover, continuous treatments of up to 18 h induced the appearance of a significant number of apoptotic cells. Following a 3-h exposure to a dose of 750 microg/ml, cells accumulated significantly in G(2)-M phase and remained blocked in G(1-) and G(2)-M phases after several posttreatments in fresh growth medium. The aqueous extract alone did not induce chromosome aberrations but, in combined treatment with H(2)O(2), significantly reduced H(2)O(2)-induced chromosome aberrations. Flow cytometric analysis of DCFH intracellular oxidation showed that the extract decreased the oxidizing power of H(2)O(2.) This ability could possibly explain the extract's antigenotoxic activity. Absence of cytotoxicity at the lower tested doses and the antimutagenic properties of the extract stimulate the interest in studying possible new pharmaceutical uses of P. orbicularis.     

Effect of montelukast on the pharmacokinetics and pharmacodynamics of warfarin in healthy volunteers

Montelukast, a cysteinyl leukotriene receptor antagonist, is being developed for the treatment of asthma and related diseases. This study was designed to evaluate whether montelukast at clinically used dosage levels would interfere with the anticoagulant effect of warfarin. In a two-period, double-blind, randomized crossover study, 12 healthy male subjects received a single oral dose of 30 mg warfarin on the 7th day of a 12-day treatment with montelukast, 10 mg daily by mouth, or a placebo. Montelukast had no significant effect on the area under the plasma concentration-time curves and peak plasma concentrations of either R- or S-warfarin. However, slight but statistically significant decreases in time to peak concentration of both warfarin enantiomers and in elimination half-life of the less potent R-warfarin were observed in the presence of montelukast. These changes were not considered as clinically relevant. Montelukast had no significant effect on the anticoagulant effect of warfarin, as assessed by the international normalized ratio (INR) for prothrombin time (AUC0-144 and INR maximum). The results of this study suggest that a clinically important interaction between these drugs is unlikely to occur in patients requiring concomitant administration of both drugs.     

Pharmacological evaluation of ricinine, a central nervous system stimulant isolated from Ricinus communis.

The extract of the pericarp of castor bean (Ricinus communis) showed some typical central nervous system stimulant effects when administered to mice. The animals became exophthalmic, presented tremors and clonic seizures and died a few minutes after receiving larger doses of the extract. At lower doses the extract improved memory consolidation and showed some neuroleptic-like properties, such as a decrease in exploratory behavior and catalepsy. The memory-improving effect and the seizure-eliciting properties of the extract were also observed with the administration of ricinine, a neutral alkaloid isolated from the extract. However, the neuroleptic-like properties of the extract were not observed with ricinine. As the therapeutic index of ricinine is of the order of 200, the compound may be considered as a promising cognition-enhancing drug that may be used for the treatment of human amnesias.     

Anticonvulsant activity and plasma level of 2,3-benzodiazepin-4-ones (CFMs) in genetically epilepsy-prone rats.

Anticonvulsant properties of some 2,3-benzodiazepine derivatives acting as alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) antagonists have been examined in vivo in the genetically epilepsy-prone rats using an audiogenic seizures assay. 2,3-Benzodiazepin-4-ones (CFMs) are nonselective AMPA antagonists that have been found to be potent anticonvulsant compound is in acute models of epilepsy. Because very little is known about their actions in a chronic model of epilepsy, and no correlations exist between anticonvulsant potency and plasma levels of these derivatives, we planned to investigate such a relationship. Maximal anticonvulsant protection occurred 15-60 min after the IP administration of GYKI 52466, 30-90 min after CFM-2, and 45-120 min after CFM-3. In addition, maximal anticonvulsant effect was observed 60-120 min after the IP administration of CFM-4 and at 90 min after CFM-5. The therapeutic index revealed that GYKI 52466 was slightly more toxic than CFM-2 and CFM-3. The time course of plasma levels of rats treated showed that peak plasma concentration was observed 45 min after IP administration of CFM-2 and CFM-3 and 75 min after CFM-4 and CFM-5. Following IP administration of CFM-3 two curves were detected, one is referred to the injected compound, and the other to its demethylated metabolite, which corresponds to CFM-2. Also. for the nitroderivative CFM-4 two curves were detected: one of an injected compound and the second due to its reduced metabolite (CFM-2). Finally, three different metabolites were detected in rat plasma after IP administration of CFM-5. The present study demonstrated that CFMs showed a significant protection against auditory stimulation during the period of peak plasma concentrations, suggesting a marked inhibition of those brain structures involved in the initiation and/or spreading of the audiogenic seizures.     

Long-term results of the Spanish trial on treatment and survival of patients with predominantly mild heart failure

A randomized open-label clinical trial was conducted to determine whether mortality, readmission, or quality of life differed between heart failure patients managed with captopril plus diuretics and those with digoxin plus diuretics. A total of 345 heart failure patients in New York Heart Association functional classes 2 and 3 without atrial fibrillation, dyspnea of bronchopulmonary origin, or hypertension not controlled with diuretics was randomized for digoxin (n = 175) or captopril (n = 170) treatment and followed up for a median of 4.5 years. Socioeconomic, demographic, electrocardiographic, echocardiographic, spirometric, and chest radiograph data were obtained at the initial examination. In a random sample of half the patients, ergometric, echocardiographic, and Holter records were obtained at entry and at 3 and 18 months. Patients were followed up for > or = 3 years. The end points were mortality, hospitalization for cardiac events, deterioration in quality of life, worsening of functional class, and need for digoxin or captopril in the captopril and digoxin groups, respectively. The trial had to be terminated prematurely owing to the difficulty in finding candidates free of angiotensin-converting enzyme (ACE)-inhibitor treatment. Baseline patient characteristics were similar in both groups. From the clinical point of view, only the 48-month mortality was relevantly lower (20.9 vs. 31.9%, respectively) among patients treated with captopril than that in those receiving digoxin (log rank test, p = 0.07). No statistically or clinically relevant differences were found in other end points or adverse effects. The results suggest but do not confirm the hypothesis that captopril treatment in mild to moderate heart failure might provide better long-term survival than digoxin.     

Analytic performance of two automated nonpretreatment digoxin immunoassays

The analytic performance of two automated nonpretreatment digoxin methods, AxSYM Digoxin II and Vitros digoxin immunoassays, was assessed. Both assays had analytic sensitivities of less than 0.2 microg/L, were linear from digoxin concentrations of 0.5 to 4.0 microg/L, and showed acceptable precision, with a maximum total coefficient of variation (CV) of 8.9% and 6.4% for the AxSYM and Vitros, respectively. Comparison of the two methods using samples from patients receiving digoxin gave the following relationship: Vitros = 0.91 x AxSYM + 0.23 (r = 0.97, Sy,x = 0.12). Digoxinlike immunoreactive factor (DLIF) crossreactivity was examined in specimens from patients who had hepatic disease, renal insufficiency, had undergone cardiac surgery, and in neonatal cord blood samples. Minimal crossreactivity was observed for most samples and the average crossreactivity for each group of samples was comparable for the two methods. The recovery of digoxin added to samples from each group of DLIF was similar, except for that from cord blood samples, for which recovery was significantly lower with the AxSYM method. Titration of a digoxin-spiked serum pool with digoxin-immune Fab showed a similar decrease in the measured digoxin concentration for both methods. Overall, the analytic performance characteristics of these two methods were comparable.