Interview with Guillermo Arrévalo, a Shipibo urban shaman, by Roger Rumrrill. Interview by Roger Rumrrill

Roger Rumrrill, a journalist headquartered in Lima, Peru who is a noted expert on the Peruvian Amazon, interviewed Guillermo Arrévalo, a Shipibo urban shaman in Pucallpa, who utilizes ayahuasca in curing rituals. Sr. Arrévalo comments on the phenomenon known as drug tourism, where urban men and women provide tours for foreigners, for a price, to experience drug-induced mystical experiences in urban settings like Iquitos and Pucallpa, Peru, as well as in Brazil, Bolivia and Ecuador. Arrévalo distinguishes between folkloric shamanism and touristic practices which are currently in vogue and, in his opinion, are the result of people trying to resolve personal problems. Arrévalo sees a spiritual and psychological crisis in Europe and North American society. The Shipibo shaman laments the misuse of toxic plants as additives to the ayahuasca potion and the damage that these plants cause to the unsuspecting tourist who doesn't really get his money's worth from shamans without experience, people who are liars and cheats and who don't have the capacity, the preparation or the boldness to do the work.     

Ochratoxin-induced toxicity,oxidative stress and apoptosis ameliorated by quercetin – Modulation by Nrf2

Ochratoxin (OTA) is one of the most abundant food contaminating mycotoxins and is commonly present in the food chain. Many of the effects associated with OTA, appear to be mediated through oxidative stress. Although the toxicity of OTA is fairly well characterized, antidotes for alleviating the toxicity are sparsely reported. Dietary antioxidants have gained much importance in the recent years for their antioxidative and therapeutic properties. In the present study the therapeutic strategy was directed towards use of quercetin, a dietary antioxidant to combat OTA-induced toxicity in Vero cell line. Our results demonstrate that quercetin pre-treatment suppressed OTA-induced cytotoxicity and oxidative stress. It modulated OTA-induced alteration on the antioxidant defence through activation of Nrf2 pathway. Morphological studies by scanning electron microscopy (SEM) and cell cycle analysis indicated that quercetin prevented OTA-induced apoptosis. It also inhibited the activation of caspase cascade that leads to DNA fragmentation. Quercetin also exhibited antigenotoxic potential by attenuating OTA-induced DNA damage and micronucleus (MN) formation. The results of the study demonstrate for the first time that quercetin pre-treatment prevents OTA-induced oxidative stress and apoptosis in Vero cell line.     

Neutralization, by a monospecific Bothrops lanceolatus antivenom, of toxic activities induced by homologous and heterologous Bothírops snake venoms.

A monospecific Bothrops lanceolatus antivenom, currently used in Martinique, was tested for its efficacy in the neutralization of several toxic and enzymatic activities of the venoms of B. lanceolatus, B. atrox and B. asper. When tested by the i.p. route in mice, B. lanceolatus venom had an LD50 of 12.8 microg/g. In addition, it induced local tissue damage (hemorrhage, edema and myotoxicity) and showed indirect hemolytic activity, but was devoid of coagulant effect on human plasma in vitro and of defibrinating activity in mice. Antivenom was fully effective in the neutralization of lethal, hemorrhagic, edema-forming, myotoxic and indirect hemolytic effects of B. lanceolatus venom in assays involving preincubation of venom and antivenom. When tested against the venoms of B. asper and B. atrox, the antivenom completely neutralized the lethal, hemorrhagic, myotoxic and indirect hemolytic effects, and was partially effective in neutralizing edema-forming activity. In contrast, the antivenom was ineffective in the neutralization of in vitro coagulant and in vivo defibrinating effects induced by these two venoms.     

Noradrenaline release in rodent tissues is inhibited by interleukin-1β but is not affected by urotensin II, MCH, NPW and NPFF

We studied whether noradrenaline release is affected by interleukin-1β and the neuropeptides urotensin II, melanin-concentrating hormone (MCH), neuropeptide W (NPW) and neuropeptide FF (NPFF). Rodent tissues preincubated with [3H]noradrenaline were superfused, and the effect of peptides on the electrically-evoked tritium overflow ("noradrenaline release") was studied. In mouse brain cortex, interleukin-1β at 0.3 nM and the prostaglandin E2 analogue sulprostone at 3 nM inhibited noradrenaline release by about 40% the effect of interleukin-1β developed gradually, whereas the effect of sulprostone occurred promptly. Urotensin II at 0.001-1 μM did not affect noradrenaline release in rat kidney cortex, whereas 0.01 μM angiotensin II increased it (positive control). MCH at 0.01-1 μM did not alter noradrenaline release in the rat brain cortex, and NPW 1 μM did not affect noradrenaline release in the mouse hypothalamus or hippocampus. In each model, 0.1 μM sulprostone inhibited noradrenaline release (positive control). NPFF and the NPFF2 receptor agonist dNPA (1 μM) did not affect noradrenaline release in the mouse atria; the inhibitory effect of the δ opioid receptor agonist 1 μM DPDPE on noradrenaline release in this tissue was not altered by NPFF or dNPA at 0.32 μM but was counteracted by the δ opioid antagonist naltrindole at 0.001 μM. In conclusion, interleukin-1β inhibits noradrenaline release in the mouse cortex; the effect develops gradually, suggesting that it affects protein biosynthesis. Noradrenergic neurons in various tissues from rodents are devoid of presynaptic receptors for urotensin II, MCH, NPW and NPFF. Finally, an interaction between a δ opioid agonist and NPFF could not be detected.     

Central antinociception induced by μ-opioid receptor agonist morphine,but not δ- or κ-, is mediated by cannabinoid CB1 receptor

Background and purpose:

It has been demonstrated that cannabinoids evoke the release of endogenous opioids to produce antinociception; however, no information exists regarding the participation of cannabinoids in the antinociceptive mechanisms of opioids. The aim of the present study was to determine whether endocannabinoids are involved in central antinociception induced by activation of µ-, δ- and κ-opioid receptors.

Experimental approach:

Nociceptive threshold to thermal stimulation was measured according to the tail-flick test in Swiss mice. Morphine (5 µg), SNC80 (4 µg), bremazocine (4 µg), AM251 (2 and 4 µg), AM630 (2 and 4 µg) and MAFP (0.1 and 0.4 µg) were administered by the intracerebroventricular route.

Key results:

The CB₁-selective cannabinoid receptor antagonist AM251 completely reversed the central antinociception induced by morphine in a dose-dependent manner. In contrast, the CB₂-selective cannabinoid receptor antagonist AM630 did not antagonize this effect. Additionally, the administration of the anandamide amidase inhibitor, MAFP, significantly enhanced the antinociception induced by morphine. In contrast, the antinociceptive effects of δ- and κ-opioid receptor agonists were not affected by the cannabinoid antagonists. The antagonists alone caused no hyperalgesic or antinociceptive effects.

Conclusions and implications:

The results provide evidence for the involvement of cannabinoid CB₁ receptors in the central antinociception induced by activation of µ-opioid receptors by the agonist morphine. The release of endocannabinoids appears not to be involved in central antinociception induced by activation of κ- and δ-opioid receptors.     

Hydrolysis of Carbonates,Thiocarbonates, Carbamates,and Carboxylic Esters of α-Naphthol, β-Naphthol,and p-Nitrophenol by Human,Rat, and Mouse Liver Carboxylesterases

Thirty carbonates, thiocarbonates, carbamates, and carboxylic esters of -naphthol, -naphthol, and p-nitrophenol were synthesized and tested as substrates for liver carboxylesterases from the crude microsomal fractions of human and mouse, and purified isozymes, hydrolases A and B, from rat liver microsomes. The carbonates, thiocarbonates, and carboxylic esters of -naphthol were cleaved more rapidly than the corresponding -naphthol isomers by the mammalian liver esterases. -Naphthyl esters of acetic, propionic, and butyric acids were among the best substrates tested for these enzymes. The majority of the substrates was consistently hydrolyzed at higher rates by hydrolase B compared with hydrolase A, although the Michaelis–Menten constant (K _m) values of selected substrates differed widely with these two isozymes. Malathion was a 15-fold better substrate for hydrolase B than for hydrolase A. Compared with the corresponding carboxylates, the carbonate moiety of - and -naphthol and p-nitrophenol lowered the specific activities of the enzymes by about fivefold but improved stability under basic conditions. The optimum pH of mouse liver esterase with the acetate, methylcarbonate, and ethylthiocarbonate of -naphthol was between pH 7.0 and pH 7.6. Human and mouse liver microsomal esterase activities were about five orders of magnitude lower than the esterase activities of purified rat liver hydrolase B. A relationship between the catalytic activity of the enzymes and the lipophilicity of the naphthyl substrates indicated that (i) in the - and -naphthyl carbonate series, an inverse relationship between enzyme activity and lipophilicity of the substrates was observed, whereas (ii) in the -naphthyl carboxylate series, an increase in enzyme activity with increasing lipophilicity of the substrates up to a log P value of about 4.0 was observed, after which the enzyme activity decreased.     

Peripheral antinociception induced by δ-opioid receptors activation, but not μ- or κ-, is mediated by Ca²⁺-activated Cl⁻ channels

Studies have demonstrated that the L-arginine/NO/cGMP pathway and the potassium and calcium channels are involved in the mechanisms underlying opioid receptor activation. As additional pathways may participate in the observed antinociceptive effects following opioid exposure, the aim of our study was to determine whether Ca(2+)-activated Cl(-) channels (CaCCs) are involved in peripheral antinociception induced by μ-, δ- and κ-opioid receptor activation. Hyperalgesia was induced by intraplantar injection of prostaglandin E(2) (PGE(2), 2 μg). Nociceptive thresholds to pressure (grams) were measured using an algesimetric apparatus 3h following injection. The μ-opioid receptor agonist morphine (200 μg), δ-opioid receptor agonist (+)-4-[(alphaR)-alpha-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide (SNC80, 80 μg), κ-opioid receptor agonist bremazocine (50 μg), CaCCs blocker niflumic acid (8-64 μg), CaCCs blocker 5-Nitro-2-(3-phenylpropylamino) benzoic acid (NPPB, 32-128 μg), nitric oxide donor sodium nitroprusside (SNP, 500 μg) and cGMP exogenous analogs dibutyryl cGMP (db-cGMP, 100 μg) were also administered into the paw. The CaCCs blocker niflumic acid and NPPB partially reversed the peripheral antinociception induced by exposure to the SNC80 in a dose-dependent manner. In contrast, niflumic acid did not modify the antinociceptive effect observed following exposure to morphine or bremazocine. Additionally, the peripheral antinociception induced by the NO donor SNP or by db-cGMP was not inhibited by niflumic acid. These results provide evidence for the involvement of CaCCs in the peripheral antinociception induced by SNC80. CaCCs activation does not appear to be involved when μ- and κ-opioid receptors are activated. In addition, we did not observe a link between CaCCs and the L-arginine/NO/GMPc pathway.     

The pharmacokinetics of the β2-adrenoceptor agonist,tulobuterol, given transdermally and by inhalation

Summary We have studied the pharmacokinetics of tulobuterol given transdermally or by aerosol inhalation in healthy male volunteers.Tulobuterol was rapidly absorbed after inhalation, with a t_max of 0.8–1.5 h. The C_max and the AUC increased linearly with dose.Tulobuterol was well absorbed after transdermal administration, with an absorption lag-time of about 4 h. The C_max and AUC increased linearly with dose and the t_max was about 9–12 h. The mean percentage of drug absorbed during the application of a patch for 24 h was 82–90% after a single dose and 82–85% during repeated dosing.The mean urinary recoveries as unchanged drug after a single inhalation and patch application were 3–4% and 5–6% respectively.Tulobuterol did not accumulate during repeated inhalation or transdermal application. It was well tolerated, except for an increase in heart rate of 10–20 beats · min^–1 after five repeated applications of a 4 mg patch.     

Salvicine, a novel topoisomerase Ⅱ inhibitor, exerts its potent anticancer activity by ROS generation

Salvicine is a novel diterpenoid quinone compound obtained by structural modification of a natural product lead isolated from a Chinese herb with potent growth inhibitory activity against a wide spectrum of human tumor cells in vitro and in mice bearing human tumor xenografts. Salvicine has also been found to have a profound cytotoxic effect on multidrug-resisitant （MDR） cells. Moreover, Salvicine significantly reduced the lung metastatic foci of MDA-MB-435 orthotopic xenograft. Recent studies demonstrated that salvicine is a novel non-intercalative topoisomerase Ⅱ （Topo Ⅱ） poison by binding to the ATPase domain, promoting DNA-Topo Ⅱ binding and inhibiting Topo Ⅱ-mediated DNA relegation and ATP hydrolysis. Further studies have indicated that salcivine-elicited ROS plays a central role in salvicine-induced cellular response including Topo Ⅱ inhibition, DNA damage, circumventing MDR and tumor cell adhesion inhibition.     

Determination of buprenorphine,norbuprenorphine, naloxone,and their glucuronides in urine by liquid chromatography–tandem mass spectrometry

A liquid chromatography–tandem mass spectrometry method for the simultaneous quantification of buprenorphine (BUP), norbuprenorphine (NBUP), naloxone (NAL), and their glucuronide conjugates BUP-G, NBUP-G, and NAL-G in urine samples was developed. The method, omitting a hydrolysis step, involved non-polar solid-phase extraction, liquid chromatography on a C18 column, electrospray positive ionization, and mass analysis by multiple reaction monitoring. Quantification was based on the corresponding deuterium-labelled internal standards for each of the six analytes. The limit of quantification was 0.5 μg/L for BUP and NAL, 1 μg/L for NAL-G, and 3 μg/L for NBUP, BUP-G, and NBUP-G. Using the developed method, 72 urine samples from buprenorphine-dependent patients were analysed to cover the concentration ranges encountered in a clinical setting. The median (maximum) concentration was 4.2 μg/L (102 μg/L) for BUP, 74.7 μg/L (580 μg/L) for NBUP, 0.9 μg/L (85.5 μg/L) for NAL, 159.5 μg/L (1370 μg/L) for BUP-G, 307.5 μg/L (1970 μg/L) for NBUP-G, and 79.6 μg/L (2310 μg/L) for NAL-G.     

Quantitative determination by HPLC of urinary 6β-hydroxycortisol,an indicator of enzyme induction by rifampicin and antiepileptic drugs

Summary A method for determination of 6-hydroxycortisol in urine by means of high performance liquid chromatography is described. After extraction of 10–30 ml aliquots of urine with ethylacetate, separation is accomplished on a silica gel column (30 cm, Lichrosorb Si 100) with a special two-phase four-component eluent of methylene chloride, n-hexane, ethanol and water. Complete separation of - and-isomers requires 15 to 20 min. For routine determinations precolumn cleaning by backflush permits injections of samples at minimum time intervals. For quantitative determinations, each injection should contain at least 0.05–0.5 µg of 6-hydroxycortisol, depending on the detector employed. The mean excretion rate in healthy male adults (26–40 years) was 273 µg/day (SD=74.5; n=12). In patients on long term mono-therapy with rifampicin, 6-hydroxycortisol excretion had risen fourfold (1166 µg/d; SEM=248; n=7), paralleling the known enzyme-inducing effect of rifampicin. The relatively smaller increase to 498 µg/d observed in patients receiving triple therapy with rifampicin, isoniazid and ethambutol points to possible inhibition by isoniazid. The greatest stimulation of 6-hydroxycortisol excretion (2352 µg/d) was found in patients receiving antiepileptic therapy (phenytoin and/or carbamazepine and other drugs). The HPLC technique for 6-hydroxycortisol proved to be a tool routinely applicable to non-invasive evaluation of drug metabolizing enzyme activity in man.     

Differential modulation by muscimol and baclofen on antinociception induced by morphine, β-endorphin,d-Pen2,5-enkephalin and U50,488H administered intracerebroventricularly in the mouse

The present study was designed to investigate the modulatory effects of stimulation of GABA_A and GABA_B receptors at supraspinal sites on antinociception induced by supraspinally administered -, -, -, and -opioid receptor agonists. The effects of the GABA_A and GABA_B receptor agonists, muscimol and baclofen respectively, on the antinociception induced by morphine (a -receptor agonist), -endorphin (an -receptor agonist), D-Pen^2,5-enkephalin (DPDPE, a -receptor agonist) and U50,488H ({trans-3,4-di-chloroN-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl] benzeocetamide}; a -receptor agonist) injected intracerebroventricularly (i.c.v.) were studied. The anti-nociception was assayed using the tail-flick and hot-plate tests. Muscimol at doses of 25–200 ng, administered i.c.v. alone did not affect the latencies of tail-flick and hot-plate thresholds, but attenuated dose-dependently the inhibition of the tail-flick and hot-plate responses induced by i.c.v. administered morphine (2 g), -endorphin (1 g), DPDPE (10 g), and U50,488H (60 g). Baclofen (1.25–10 ng) administered i.c.v. alone did not affect the latencies of the tail-flick and hot-plate responses, but attenuated dose-dependently the inhibition of the tail-flick and hot-plate responses induced by -endorphin and U50,488H, without affecting morphine-or DPDPE-induced responses. Our results indicate that activation of GABA_A receptors at the supraspinal sites by i.c.v. injection of muscimol antagonizes antinociception induced by supraspinally administered -, -, -, and -opioid receptor agonists. On the other hand, activation of GABA_B receptors at supraspinal sites by i.c.v. baclofen antagonizes antinociception induced by i.c.v. administered - and -opioid agonists, but not - or -opioid agonists.     

Nicousamide,a potent inhibitor of phosphorylation by TGF-β receptor II

Renal fibrogenesis is related to the development of diabetic nephropathy. TGF-β receptor II (TGF-β RII) plays a vital role during renal fibrogenesis by phosphorylation and activation of type I receptors and downstream regulators. Nicousamide is a 1.1 class of drug, which can inhibit renal fibrosis in animal models of diabetic nephropathy. After cloning and purification of TGF-β RII, an in vitro substrate phosphorylation assay was set up to investigate the ability of nicousamide to inhibit phosphorylation and formation of cellular downstream proteins. Our results validate nicousamide as a potent inhibitor of phosphorylation of TGF-β RII.     

Antagonism of γ-aminobutyric acid and muscimol by picrotoxin,bicuculline, strychnine,bemegride, leptazol,d-tubocurarine and theophylline in the isolated olfactory cortex

Summary -Aminobutyric acid (GABA) applied to neurones in the olfactory cortex slice in vitro, increases input conductance and produces a small depolarization, which mimicks the action of the inhibitory transmitter. In previous experiments it was shown that this inhibition could be blocked by picrotoxin, bicuculline, strychnine, leptazol, bemegride, theophylline and d-tubocurarine. In the present study the effects of the above blockers on the action of bathapplied GABA were assessed. These blockers all antagonised the action of GABA at concentrations similar to those required to block synaptic inhibition. However, the amount of antagonism of GABA action was variable and this variability was attributed to the cellular uptake of GABA. The variability was circumvented by using muscimol, a GABA agonist not subjected to uptake. This GABA antagonism explains the convulsant action of many of the agents studied and reinforces the idea that GABA mediated inhibitory transmission in the olfactory cortex.     

Miscibility studies of indomethacin and Eudragit® E PO by thermal, rheological, and spectroscopic analysis

The objective of this study is to understand the underlying mechanisms responsible for the superior stability of indomethacin (INM)–Eudragit® E PO (E PO) system by exploring the miscibility and intermolecular interactions through the combination of thermal, rheological, and spectroscopic analysis. The zero shear rate viscosity drops monotonically with the increase of INM concentration at 145°C, suggesting that E PO and INM form a solution and the small molecular drug acts as a plasticizer. Flow activation energy was calculated from the viscosity data at different temperature. The glass transition temperature (T_g) of the mixture at different composition was determined using differential scanning calorimetry. The T_g and flow activation energy peak at the INM concentration around 60%–70%. Fourier transform infrared analysis provided direct evidence for the intermolecular ionic interactions, which may disrupt the dimer formation of amorphous INM. The study explained the superior stability of INM–E PO mixtures, and demonstrated that a combination of thermal, rheological, and spectroscopic technologies can help us to obtain a full picture of the drug–polymer interactions and to determine the formulation and processing conditions.     

Modification of ethanol’s reinforcing effectiveness in rhesus monkeys by cocaine,flunitrazepam, or gamma-hydroxybutyrate

Background Although ethanol is frequently used in combination with other psychoactive drugs, the behavioral and pharmacological reasons for this form of polydrug abuse have not been well described. Materials and methods Rhesus monkeys with indwelling intravenous catheters produced intravenous injections of ethanol (50, 100, or 200 mg/kg/inj), flunitrazepam (0.001–0.03 mg/kg/inj), cocaine (0.01 or 0.03 mg/kg/inj), or combinations of ethanol and these drugs or gammahydroxybutyrate (GHB) (1.0 or 3.2 mg/kg/inj) by lever pressing according to a fixed-ratio schedule. The response requirement for each drug or drug combination was increased across sessions (10, 32, 100, 320, or 1,000). The dependent variables were rates of responding maintained by the drug or drug combination and the elasticity of drug demand when consumption was expressed as a function of price. Results Elasticity (P _max) values for each drug varied among the monkeys but retained the same rank order for the monkeys, suggesting a fundamental difference in the animals’ apparent sensitivities to the reinforcing effects of the drugs. Combining ethanol with the other drugs did not increase their reinforcing effectiveness. GHB (ineffective in previous studies) did not modify ethanol’s reinforcing effects; demand functions for the combination of ethanol and flunitrazepam were slightly less elastic than for ethanol alone, but no different from that for flunitrazepam alone; adding ethanol to cocaine detracted from the reinforcing effectiveness of cocaine. Conclusions The hypothesis that use of ethanol in combination with sedative and stimulant drugs is due to an ability of ethanol to enhance the reinforcing effects of these drugs is not supported.     

Different types of opioid receptors mediating analgesia induced by morphine,DAMGO, DPDPE,DADLE and β-endorphin in mice

Summary The effects of intracerebroventricular (i.c.v.) administration of d-Phe-Cys-Tyr-d-Try-Orn-Thr-Pen-Thr-NH₂ (CTOP), a selective mu-opioid receptor antagonist, (Allyl)2-Tyr-Aib-Aib-Phe-Leu-OH (ICI 174864) and (N,N-Bisallyl-Tyr-Gly-Gly--(CH₂S)-Phe-Leu-OH (ICI 154129), selective delta-opioid receptor antagonists on blocking analgesia induced by -endorphin, morphine, d-Ala²-NMePhe⁴-Gly-ol-enkephalin (DAMGO), d-Ala²-d-Leu⁵-enkephalin (DADLE) and d-Pen²-enkephalin (DPDPE) administered i.c.v. were studied in male ICR mice. The analgesia was assessed by the tail-flick and paw-licking (hot-plate) tests. The potencies of opioid agonists injected i.c.v. for producing analgesia were DAMGO > DADLE > -endorphin > morphine > DPDPE. Intracerebroventricular administration of CTOP (0.05 g) selectively antagonized inhibition of the tail-flick and paw-licking response induced by morphine, DAMGO or DADLE but not -endorphin or DPDPE. ICI 174864 (5 g) and ICI 154129 (5 g) injected i.c.v. selectively antagonized analgesia induced by DPDPE or DADLE but not -endorphin, morphine or DAMGO injected i.c.v. These results indicate that analgesia induced by morphine and DAMGO is mediated by the stimulation of mu-opioid receptors while analgesia induced by DPDPE is mediated by the stimulation of delta-opioid receptors. DADLE-induced analgesia is mediated by the stimulation of both mu- and delta-opioid receptors. Analgesia induced by -endorphin is mediated by neither munor delta-opioid receptors.Abbreviations i.c.v. intracerebroventricular - i.t. intrathecal - CTOP d-Phe-Cys-Tyr-d-Try-Orn-Thr-Pen-Thr-NHZ - DAMGO d-Ala²-NMePhe²-Gly-ol-enkephalin - DADLE d-Ala²-d-Leus-enke-phalin - DPDPE dd-Pen²-dd-Pen⁵-enkephalin - ICI 174864 (Allyl)2Tyr-Aib-Aib-Phe-Leu-OH - ICI 154129 (N,N-Bisallyl-Tyr-Gly-Gly-(CH₂S)-Phe-Leu-OH