Reactivity and selectivity of the reaction of O,O-diethyl 2,4-dinitrophenyl phosphate and thionophosphate with thiols of low molecular weight.

A reactivity and selectivity study of O,O-diethyl 2,4-dinitrophenyl phosphate () and O,O-diethyl 2,4-dinitrophenyl thionophosphate () with a series of thiols of low molecular weight: N-acetyl cysteine (NAC), l-cysteine (Cys), homocysteine (Hcys), glutathione (GSH), and d-penicillamine (Pen) was conducted. Results show that (i) these nucleophiles only attack at the aromatic moiety of both triester derivatives, (ii) a kinetic control product by sulfhydryl attack of thiols was observed in the reactions of both triesters with Cys and Hcys, followed by an intramolecular amine attack leading to a thermodynamic control product. The kinetic study leads to the proposal of Meisenheimer complex formation and then proton transfer to the reaction media as the mechanism of these reactions.

Iron oxide nanostructured electrodes for detection of copper(II) ions.

Iron oxide nanostructured (ION) electrodes were assembled layer-by-layer onto ITO-coated glass substrates and their structure, morphology, and electrochemical properties were investigated, the latter aiming at the development of a chemical sensor for Cu2+. The electrodes were built by immersing the substrate alternately into an aqueous colloidal suspension of positively charged magnetite nanoparticles (np-Fe3O4, 8 nm) and an aqueous solution of anionic sodium sulfonated polystyrene (PSS). The adsorbed amount of both materials was monitored ex-situ by UV-vis spectroscopy and it was found to increase linearly with the number of deposition cycles. The resulting films feature a densely-packed structure of magnetite nanoparticles, as suggested by AFM and Raman spectroscopy, respectively. Cyclic voltammograms of electrodes immersed in acetate buffer (pH 4.6) displayed three electrochemical events that were tentatively ascribed to the reduction of Fe(III) oxy-hydroxide to magnetite, reduction of maghemite to magnetite, and finally oxidation of magnetite to maghemite. The effect of np-Fe3O4/PSS bilayers on the ION electrode performance was to increase the anodic and cathodic currents produced during electrochemical oxidation-reduction of the Fe(CN)(3-/4-) redox couple. With more bilayers, the ION electrode provided higher anodic/cathodic currents. Moreover, the redox couple exhibited a quasi-reversible behavior at the ION electrode as already observed with other working electrode systems. Fitting of voltammetry data provided the apparent electron transfer constants, which were found to be higher in ION electrodes for both redox couples (Fe(CN)(3-/4-) and Cu(2+/0)). By means of differential pulsed anodic stripping voltammetry, the ION electrodes were found to respond linearly to the presence of Cu2+ in aqueous samples in the range between 1.0 and 8.0 x 10(-6) mol x L(-1) and displayed a limit of detection of 0.3 x 10(-8) mol x L(-1). The sensitivity was - 0.6µA/µmol x L(-1). In standard addition and recovery experiments performed with tap water the recovery was about 102%-119%. In similar experiments conducted with ground and instant coffee samples the recovery was 92.5% and 103%, respectively. Furthermore, the ION electrodes were almost insensitive to the presence of common interfering ions, such as Zn2+, Mn2+, Ni2+, and Fe3+, even at concentrations ten times higher than that of Cu2+.

Separation of solids and disinfection for agronomical use of the effluent from a UASB reactor.

The present work addresses the preparation of the effluent from a full-scale upflow anaerobic sludge blanket (UASB) reactor for drip irrigation of orange crops. The pilot plant included a lamella plate clarifier followed by a geo-textile blanket filter and a UV disinfection reactor. The clarifier operated with a surface load of 115 m(3)m(-2)d(-1), whereas the filter operated with 10 m(3)m(-2)d(-1). The UV reactor was an open-channel type and the effective dose was approximately 2.8 W h m(-3). The effluent of the UASB reactor received 0.5 mg L(-1) cationic polyelectrolyte before entering the high-rate clarifier. Suspended solids' concentrations and Escherichia coli and helminth egg's densities were monitored throughout the treatment system for 12 months. Results showed that the total suspended solids concentration in the filter effluent was lower than 7 mg L(-1) and helminth density was below 1.0 egg L(-1). The UV disinfection demonstrated the ability to produce a final effluent with E. coli density lower than 10(3)MPN/100 mL (MPN: most probable number) during the entire process. Thus, the World Health Organization standards for unrestricted crop use were met. Agronomic interest parameters were controlled and it was possible to identify the important contribution of treated sewage in terms of the main nutrients.

Effects of the juçara fruit (Euterpe edulis Martius) pulp and lyophilized extract on NRF2, KEAP1, SOD1, and GPX2 expression in human colorectal cancer cell lines.

We investigated the effects of the juçara fruit (Euterpe edulis Martius) pulp and lyophilized extract on the expression of cytoprotective genes nuclear factor erythroid 2 (NF-E2)-related factor 2 (NRF2), kelch-like ECH-associated protein 1 (KEAP1), superoxide dismutase (SOD1), and glutathione peroxidase (GPX2) in human colorectal cancer cell lines (HT-29 and Caco-2). Cells were cultured for 24 h in Dulbecco's Modified Eagle's Medium containing juçara fruit pulp (5, 10, or 50 mg/mL) or lyophilized extract (0.05, 0.1, or 0.5 mg/mL), and gene expression was quantified using real-time quantitative reverse transcription polymerase chain reaction. All studied genes showed significant variation in gene expression among different concentrations of pulp or lyophilized extract. Overall, the expression of the selected genes decreased in both cell lines following exposure to the pulp or lyophilized extract in a dose-dependent manner for most of the concentrations studied. In summary, our study showed that the compounds in juçara fruit inhibited the expression of cytoprotective genes associated with the antioxidant response and that, although not cytotoxic at the concentrations studied, they could potentially block the activation of the NRF2/KEAP1 pathway.

Preparation of nanocomposites resin from seed Pterodon emarginatus doped maghemite nanoparticles.

Electrical characterization and magnetic nanocomposite resin seeds Pterodon emarginatus (PE) doped with nanoparticles of maghemite and treated by different chemical processes is reported in this paper. The pure PE resin showed semiconducting characteristics probably the presence of natural iron oxide in its molecular structure. The analysis of Mössbauer spectra pure resin showed two magnetic sites presented on measurements made at temperature of 300 K. Six "LEDs" to have been doped maghemite nanoparticles forming concentrations of 2.6 x 10(15) to 1.56 x 10(16) particles/cm2 forming the LED-PEMN. In the presence of the applied current versus voltage (0 to 0.9 V) LED-PEMN shown semiconducting properties. In the presence of frequency versus voltage sample of pure resin and LED features small decrease. While samples of LED-PEMN suffers loss frequency linearly with concentration and voltage. The pure PE resin shows high resistance to the applied voltage while the LED-PEMN is observed linear increase with the strength and concentration of nanoparticles of maghemite.

New magnetic fluid developed with natural organic compounds biocompatible.

This work was developed with an aqueous suspension of maghemite nanoparticles and colloidal emulsions with nanoparticles of magnetite. The nanoparticles were synthesized by co-precipitation method. The first was the magnetic emulsion nanoparticles of maghemite dispersed in the aqueous extract obtained from the leaf embauba (Cecropia Obtusifolia), whose tree is native to Central and South America. Thereby achieving the magnetic fluid extract embauba stabilized with ionic buffer solution pH 7.4. A second emulsion was prepared with colloidal magnetite nanoparticles with surfaces previously coated with oleic acid as a means of dispersing and using the oil extracted from in nature seed Andiroba (Carapa Guianensis), tree of the Brazilian Amazon. These new magnetic fluids the nanoparticles were characterized by Photoacoustic spectroscopy (PAS) to determine the coating layer of molecules on the surfaces of nanoparticles. In aqueous ionic magnetic fluid Cecropia Obtusifolia (MFCO) chlorogenic acid contributes to the electron density in the presence of four groups alcohols, a ketone group and a carboxylic group. In magnetic fluid-based oil andiroba MFAD PAS spectra show that oleic acid molecules are tightly linked on the surface of the nanoparticles.

Computational structural, electronic and optical properties of the palmitic acid in its C form.

In this work, we report a theoretical study of the structural, electronic, and optical properties of palmitic acid crystal in its C form under DFT calculations level. Palmitic acid is a fatty acid that constitutes the large majority of vegetable oils with recognized potential applications in medicine, pharmaceuticals, cosmetics technology, foods, and fuel. As a main result, we have found that the electronic bandstructure reveals an indirect gap given by 3.713 eV (E→B andE→Γ), as a main bandgap, while the secondary bandgaps found were 4.175 eV (γ1→Γ) and 4.172 eV (γ2→B). It behaves like a wide bandgap semiconductor, which points to potential applications in optoelectronic devices.

Dynamic susceptibility investigation of maghemite nanoparticles incorporated in bovine serum albumin template.

Room-temperature measurements of the magnetic susceptibility of Bovine Serum Albumin-based nanocapsules (50 to 300 nm in size) loaded with different amounts of maghemite nanoparticles (7.6 nm average diameter) have been carried out in this study. The field (H) dependence of the imaginary peak susceptibility (fp) of the nanocomposite samples was investigated in the range of 0 to 4 kOe. From the analysis of the fp x H curves the concentration (N) dependence of the effective maghemite magnetocrystalline energy barrier (E) was obtained. Analysis of the E x N data was performed using a modified Mørup-Tronc [Phys. Rev. Lett. 72, 3278 (1994)] model, from which a huge contribution from the magnetocrystalline surface anisotropy was observed.

Effects of the juçara fruit (Euterpe edulis Martius) pulp and lyophilized extract on NRF2, KEAP1, SOD1, and GPX2 expression in human colorectal cancer cell lines

We investigated the effects of the juçara fruit (Euterpe edulis Martius) pulp and lyophilized extract on the expression of cytoprotective genes nuclear factor erythroid 2 (NF-E2)-related factor 2 (NRF2), kelch-like ECH-associated protein 1 (KEAP1), superoxide dismutase (SOD1), and glutathione peroxidase (GPX2) in human colorectal cancer cell lines (HT-29 and Caco-2). Cells were cultured for 24 h in Dulbecco's Modified Eagle's Medium containing juçara fruit pulp (5, 10, or 50 mg/mL) or lyophilized extract (0.05, 0.1, or 0.5 mg/mL), and gene expression was quantified using real-time quantitative reverse transcription polymerase chain reaction. All studied genes showed significant variation in gene expression among different concentrations of pulp or lyophilized extract. Overall, the expression of the selected genes decreased in both cell lines following exposure to the pulp or lyophilized extract in a dose-dependent manner for most of the concentrations studied. In summary, our study showed that the compounds in juçara fruit inhibited the expression of cytoprotective genes associated with the antioxidant response and that, although not cytotoxic at the concentrations studied, they could potentially block the activation of the NRF2/KEAP1 pathway.

An ontogenic study of the behavioral effects of chronic intermittent exposure to ayahuasca in mice.

Ayahuasca is a beverage obtained from decoctions of the Banisteriopsis caapi plus Psychotria viridis. In religious contexts, ayahuasca is used by different age groups. However, little is known of the effects of ayahuasca during ontogenic development, particularly with regard to the functional characteristics of the central nervous system. Animal models are useful for studying the ontogenic effects of ayahuasca because they allow exclusion of the behavioral influence associated with the ritualistic use. We investigated the effects of exposure to ayahuasca (1.5 mL/kg, orally, twice a week) on memory and anxiety in C57BL/6 mice, with the post-natal day (PND) being used as the ontogenic criterion for classification: childhood (PND21 to PND35), adolescence (PND35 to PND63), adulthood (PND90-PND118), childhood-adolescence (PND21 to PND63), childhood-adulthood (PND21 to PND118) and adolescence-adulthood (PND35 to PND118). One day after the last ayahuasca exposure, the mice were subjected to the Morris water maze (MWM), open field and elevated plus maze tasks (EPM). Ayahuasca did not affect locomotion in the open field or open arms exploration in the EPM, but increased the risk assessment behavior in the childhood group. Ayahuasca did not cause any change in acquisition of spatial reference memory in the MWM task, but decreased the time spent on the platform quadrant during the test session in the adolescence group. These results suggest that, in mice, exposure to ayahuasca in childhood and adolescence promoted anxiety and memory impairment, respectively. However, these behavioral changes were not long-lasting since they were not observed in the childhood-adulthood and adolescence-adulthood groups.

Chronic intermittent exposure to ayahuasca during aging does not affect memory in mice.

The Quechua term ayahuasca refers to a beverage obtained from decoctions of the liana Banisteriopsis caapi with leaves of Psychotria viridis. The ritualistic use of ayahuasca is becoming a global phenomenon, with some individuals using this beverage throughout life, including in old age. Cognitive impairment is a common manifestation during aging. There are conflicting reports on the ability of some ayahuasca compounds to exert neuroprotective or neurotoxic effects that could improve or impair learning and memory. Animal models provide a relevant and accessible means of investigating the behavioral effects of ayahuasca without the environmental conditions associated with the ritualistic use of the beverage. In this study, we investigated the influence of chronic ayahuasca exposure throughout aging on the spatial reference and habituation memories of mice. Twenty-eight male c57bl/6 mice (6 months old) received ayahuasca or water (1.5 mL/kg, orally) twice a week for 12 months and were tested in the Morris water maze (MWM), open field and elevated plus maze (EPM) tasks before and after treatment. During aging, there was significant impairment in the evocation (but not acquisition) of spatial reference memory and in habituation to the open field. There was also a decrease in locomotor activity in the open field and EPM tests, whereas the anxiety parameters were unaltered. Ayahuasca treatment did not alter any of these parameters associated with aging. These findings indicate that chronic exposure to ayahuasca during aging did not affect memory in mice.

Pulmonary ventilation/perfusion single photon emission tomography--Initial experience of a Nuclear Medicine Department.

INTRODUCTION: Lung ventilation/perfusion scintigraphy with planar images (V/QS-planar) is very useful for the diagnosis and follow-up of pulmonary thromboembolism (PTE). Acquiring tomographic images (V/QS-SPECT) is a recent development with potential to increase the technique's accuracy. The purpose of this work is to evaluate the added benefits of V/QS-SPECT studies as opposed to traditional planar imaging. PATIENTS AND METHODS: We prospectively revised 53 V/QS-planar and V/QS-SPECT exams, performed according to the European Association of Nuclear Medicine guidelines. We evaluated the exams independently, by consensus of two Nuclear Medicine physicians. For both methods, we gave each lung a score expressing the dimension and extension of perfusion defects with normal ventilation. For each lung, we compared the scores with the paired Wilcoxon test, estimating the 95% confidence interval (95 CI) for the respective difference. RESULTS: We performed V/QS-SPECT exams without technical difficulties. The paired Wilcoxon test estimated the score difference to be -0.75 (95 CI of -1.0 to -0.5; p-value=9.6 × 10(-7)), expressing a statistically significant difference of about 1 subsegmental defect between both methods, with V/QS-SPECT detecting more defects. DISCUSSION: The results demonstrate that V/QS-SPECT identifies a slightly larger number of perfusion defects than V/QS-planar, suggesting a higher sensitivity of this technique. However, more studies are necessary to evaluate the clinical meaning of this fact. CONCLUSION: V/QS-SPECT demonstrates a higher capability to identify perfusion defects. This method looks promising, allowing for a greater role of this exam in pulmonary thromboembolism diagnosis and follow-up.

Final results of a phase III clinical trial of adjuvant chemotherapy with the modified fluorouracil, doxorubicin, and mitomycin regimen in resectable gastric cancer.

PURPOSE: In a randomized clinical trial (European Organization for the Research and Treatment of Cancer [EORTC] no. 40813) on adjuvant chemotherapy in gastric cancer, results obtained after administration of the FAM2 regimen (fluorouracil [5-FU], doxorubicin, and mitomycin) were compared with results obtained after surgery alone to assess the effect of this regimen on overall survival, time to progression, and disease-free interval. PATIENTS AND METHODS: Three hundred fourteen patients who had undergone curative resection for stage II or stage III (International Union Against Cancer [UICC] 1978) gastric adenocarcinoma were randomized to receive chemotherapy (treatment arm) or no further treatment (control arm). The chemotherapy schedule was repeated every 43 days for seven cycles. The log-rank test and the Cox model were used for statistical analysis. RESULTS: Of 314 patients, 159 comprised the control group and 155 the FAM2 group. Nineteen FAM2 patients never received chemotherapy. The median number of cycles was five. Of the patients started on adjuvant treatment, severe hematologic and nonhematologic toxicity (grades 3 or 4, World Health Organization [WHO] scale) occurred, respectively, in 6% to 9% and in 1% to 29% of cases. The overall 5-year survival rate was 70% for stage II and 32% for stage III patients. No statistically significant difference was found between overall survival of the two treatment arms (P = .295). However, time to progression was significantly delayed in the FAM2 arm (P = .020) and disease-free survival showed borderline significance (P = .068). CONCLUSION: FAM2, in view of its high toxicity, cannot be advocated as standard adjuvant treatment for gastric cancer. Large-scale clinical trials using more active, less toxic regimens are required to demonstrate whether adjuvant chemotherapy provides any real benefit.

Final results of a randomized phase III trial of sequential high-dose methotrexate, fluorouracil, and doxorubicin versus etoposide, leucovorin, and fluorouracil versus infusional fluorouracil and cisplatin in advanced gastric cancer: A trial of the European Organization for Research and Treatment of Cancer Gastrointestinal Tract Cancer Cooperative Group.

PURPOSE: To compare the efficacy and tolerability of etoposide, leucovorin, and bolus fluorouracil (ELF) or infusional fluorouracil plus cisplatin (FUP) with that of the reference protocol of fluorouracil, doxorubicin, and methotrexate (FAMTX) in advanced gastric cancer. PATIENTS AND METHODS: A total of 399 patients with advanced adenocarcinoma of the stomach were randomized and analyzed for toxicity, tumor response, and progression-free and overall survival. Only reviewed and confirmed responses were considered. The analysis of remission was based on assessable patients with documented measurable lesions. The intent-to-treat principle, log-rank test, and Cox regression model were used for the statistical analysis of time-to-event end points. RESULTS: The overall response rate for 245 eligible patients with measurable disease was 9% with ELF, 20% with FUP, and 12% with FAMTX, with no significant differences. One hundred twelve patients were eligible for efficacy in assessable, nonmeasurable disease. No change was observed in 66% of patients treated with ELF, 56% with FUP, and 55% with FAMTX. Two patients achieved a complete tumor regression (one each for ELF and FAMTX). With a median follow-up time of 4.5 years, the median survival times were 7.2 months with ELF, 7.2 months with FUP, and 6.7 months with FAMTX, respectively, with no significant differences. Nonhematologic and hematologic toxicities of ELF, FUP, and FAMTX were acceptable, with neutropenia being the major toxicity for all three regimens. Seven treatment-related deaths occurred (two with FUP and five with FAMTX). CONCLUSION: All three investigated regimens demonstrate modest clinical efficacy and should not be regarded as standard treatment for advanced gastric cancer. New strategies should be considered to achieve a better clinical efficacy in the treatment of advanced gastric cancer.

Sedative and anticonvulsant effects of hydroalcoholic extract of Equisetum arvense.

The hydroalcoholic extract of Equisetum arvense (HAE) tested at the doses of 200 and 400 mg/kg showed a significant activity on the open-field, enhanced the number of falls in the rota-rod reducing the time of permanence in the bar and increased the sleeping time (46% and 74%) in the barbiturate-induced sleeping time. In the pentylenetetrazole-seizure, it increased the first convulsion latency, diminished the severity of convulsions, reduced the percentage of animals which developed convulsion (50% and 25%) and protected animals from death. On the contrary, in the elevated plus maze, the doses 50, 100 and 150 mg/kg did not affect the evaluated parameters. Thus, HAE presented anticonvulsant and sedative effects. Phytochemical analysis detected the presence of tannins, saponins, sterols and flavonoids.

Final results of a phase III clinical trial on adjuvant intraportal infusion with heparin and 5-fluorouracil (5-FU) in resectable colon cancer (EORTC GITCCG 1983-1987). European Organization for Research and Treatment of Cancer. Gastrointestinal Tract Cancer Cooperative Group.

In this phase III clinical trial conducted by the Gastrointestinal Tract Cancer Cooperative Group of the European Organization for Research and Treatment of Cancer (GITCCG-EORTC), we evaluated the effect of adjuvant intraportal infusion of heparin (HEP) and 5-fluorouracil (5-FU) on overall survival, disease-free survival and time to progression in patients with resectable colon cancer. From January 1983 to June 1987, 235 patients were randomised from 14 institutions in seven European countries: 79 patients made up the control group (control): 72 the portal vein infusion group given heparin alone (5000 IU daily x 7 consecutive days) (HEP); 84 the portal vein infusion group given heparin (5000 IU daily x 7 consecutive days) and 5-FU (500 mg/m2 daily x 7 consecutive days) (HEP/5-FU); 34 patients were considered ineligible. The 199 patients considered eligible were well balanced for age, sex, Karnofsky index, tumour location, surgery, surgical procedure and Dukes' stage. Four patients (2 control, 1 HEP, 1 HEP/5-FU) died of surgical complications. No differences were observed between control group and treatment groups (HEP, HEP/5-FU) for postoperative complications and number of hospitalisation days. Severe toxicity (grade 3-4, WHO) was found in 12% of patients in the HEP group and 8% in the HEP/5-FU group. After a median follow-up of 9 years, disease progression was reported in 40% of patients in the control group, 40% in the HEP group and 29% in the HEP/5-FU group. Five-year survival, time to progression and disease-free survival were 69%, 58% and 56%, respectively, in the control arm, 61%, 58% and 56% in the HEP arm, and 71%, 69% and 65% in the HEP/5-FU arm. Based on all randomised patients, the effect of treatment was not statistically significant with respect to any of the endpoints. It is confirmed that intraportal 5-FU infusion is safe and has a tolerable toxicity, but cannot be considered standard treatment for patients with resectable colon cancer.

Isolated limb perfusion with fotemustine after chemosensitization with dacarbazine in melanoma.

Isolated limb perfusion (ILP) has been reported as the most effective treatment for localized recurrent melanoma of the limbs. In terms of local and regional control with melphalan, complete remission is achieved in about 40% of patients, with frequent toxicity causing significant short-term disability in many and long-term incapacity in a few. Since 1989, several studies have reported success using a combination of fotemustine and dacarbazine (DTIC) in the systemic treatment of disseminated melanoma and brain metastasis. In May 1995, we began a pilot study with systemic DTIC 400 mg/m2 given intravenously about 4 h before ILP using fotemustine in an intra-arterial bolus of 100-150 mg/m2 as the perfusion agent. By July 1996, 10 patients had been included in the study. The results were evaluated in terms of the response rate (five complete responses and one partial response in the six patients who could be evaluated), local toxicity (nine patients with level I and one with level II, measured on the Wieberdink scale) and systemic toxicity (nine patients with level 0 and one with level 1, measured on the World Health Organization scale). Treatment was effective, with a similar response rate to that obtained with melphalan but with much lower toxicity, so this protocol may represent an innovation in loco-regional therapy and should be further investigated in a large trial.

Adjuvant FAM2 in resectable gastric cancer.

In spite of the improvements in surgical techniques and intensive care, no important benefit in the prognosis of patients with gastric carcinoma has been attained in the last twenty years. Different adjuvant treatment protocols have been proposed in an attempt to improve upon the results obtained with surgery only. In western countries, the FAM chemotherapeutic regimen is one on the most widely used for the treatment of advanced gastric carcinoma. In 1982 the G.I. GROUP of the EORTC proposed a modification (FAM2) to the original FAM as an adjuvant treatment in a controlled clinical study for gastric carcinoma. It is still too early to determine any therapeutic advantages of FAM2 in this protocol. Although the FAM2 regimen is fairly well tolerated, there is some toxicity which, however, seems to be slightly higher than in the regular FAM. It remains to be seen if this is a reasonable price to pay for still unknown therapeutic advantages. In view of the scarcity of available data in this field and the conflicting results which have emerged so far, the results of our study are awaited with great interest.

An improved technique for a stapled transabdominal esophagojejunostomy.

BACKGROUND: In the performance of a stapled transabdominal esophagojejunostomy there are two main technical problems involved and related to a difficult surgical exposure. One is the placement of the purse-string suture and the second is the insertion of the anvil of the circular intraluminal stapler into the distal esophagus. METHODS: These technical difficulties can be overcome by opening just the anterior wall of the esophagus at the anastomosis level, leaving the posterior wall intact. RESULTS: The integrity of the posterior wall avoids retraction of the mucosa, allowing the esophagus to remain opened for the placement of a through and through purse-string suture under direct vision. It also acts as a conduit for the insertion of the anvil of the circular intraluminal stapler. CONCLUSIONS: The technique described herein avoids stay sutures, purse-string instruments, and forceful instrumental dilatation of the distal esophagus, making these very important operative steps much easier, safer, and more reliable.

Proconvulsant effects of high doses of venlafaxine in pentylenetetrazole-convulsive rats.

Venlafaxine, an atypical antidepressant drug, has been used to treat several neurological disorders, presenting excellent efficacy and tolerability. Clinical seizures after venlafaxine treatment have occasionally been reported when the drug was used at very high doses or in combination with other medications. The aim of the present study was to investigate the convulsant effects of venlafaxine in rats under controlled laboratory conditions. Adult male Wistar rats (8 per group) receiving venlafaxine or saline at the doses of 25-150 mg/kg were subjected 30 min later to injections of pentylenetetrazole at the dose of 60 mg/kg. The animals receiving 75, 100 and 150 mg/kg venlafaxine presented increased severity of convulsion when compared to controls (P = 0.02, P = 0.04, and P = 0.0004, respectively). Indeed, an increased percentage of death was observed in these groups (50, 38, and 88%, respectively) when compared to the percentage of death in the controls (0%). The group receiving 150 mg/kg showed an reduction in death latency (999 +/- 146 s) compared to controls (1800 +/- 0 s; cut-off time). Indeed, in this group, all animals developed seizures prior to pentylenetetrazole administration. Surprisingly, the groups receiving venlafaxine at the doses of 25 and 50 mg/kg showed a tendency towards an increase in the latency to the first convulsion. These findings suggest that venlafaxine at doses of 25 and 50 mg/kg has some tendency to an anticonvulsant effect in the rat, whereas doses of 75, 100 and 150 mg/kg presented clear proconvulsant effects in rats submitted to the pentylenetetrazole injection. These findings are the first report in the literature concerning the role of venlafaxine in seizure genesis in the rat under controlled conditions.