Assessment of genetic damage induced by dental bleaching agents on mouse lymphoma cells by single cell gel (comet) assay

Dental bleaching is a simple and conservative procedure for aesthetic restoration of vital discoloured teeth. However, dental bleaching agents may represent a hazard to human health, especially by causing DNA strand breaks. Genotoxicity tests form an important part of cancer research and risk assessment of potential carcinogens. In the current study, the genotoxic potential associated with exposure to dental bleaching agents was assessed by the single cell gel (comet) assay in vitro. Six commercial dental bleaching agents (Clarigel Gold - Dentsply; Whitespeed - Discus Dental; Nite White - Discus Dental; Magic Bleaching - Vigodent; Whiteness HP - FGM and Lase Peroxide - DMC) were exposed to mouse lymphoma cells in vitro. The results pointed out that all dental bleaching agents tested contributed to the DNA damage as depicted by the mean tail moment. Clear concentration-related effects were obtained for DNA damaging, being the strongest effect observed at the highest dose of the hydrogen peroxide (Whiteness HP and Lase Peroxide, at 35% concentration). on the contrary, Whitespeed (Discus Dental) induced the lowest level of DNA breakage. Taken together, these results suggest that dental bleaching agents may be a factor that increases the level of DNA damage as detected by the single cell gel (comet) assay.

Decreased Sperm Motility in Rats Orally Exposed to Single or Mixed Pesticides

The Brazilian Agency of Sanitary Vigilance (ANVISA) conducted a study that demonstrated the presence of residues of several pesticides in fresh fruits and vegetables that were available for purchase by the general populace. In order to evaluate potential adverse health effects of low-level exposure to agrochemicals, the reproductive toxicity of the pesticides dicofol, dichlorvos, permethrin, endosulfan, and dieldrin was evaluated in rats dosed with these chemicals individually or as mixtures. Sixty male Lewis rats (6 wk old, 200 x g) were randomly allocated to 8 groups: (1) control group, received basal diet; (2) 5 groups designated a to e received the diet containing each pesticide individually, at the respective effective doses: lowest-observed-adverse-effect level (LOAEL) for dieldrin and endosulfan, lowest-observed-effect level (LOEL) for dicofol, and lowest effect level (LEL) for dichlorvos and permethrin, respectively, depending on the published data; (3) effective dose group, which received a mixture of pesticides added to basal diet at the respective doses reported to produce adverse effects; and (4) low dose group, which received a pesticide mixture added to the basal diet, where each pesticide was at its no-observed-effect level (NOEL). After 8 wk of treatment, reproductive parameters were evaluated. Sperm morphology, daily sperm production (DSP), sperm transit time through the epididymis, hormonal levels, and histopathological evaluation of testis and epididymis did not differ significantly among the groups. However, sperm motility was significantly decreased in animals that received a mixture of dieldrin, endosulfan, dicofol, dichlorvos, and permethrin, as well as in the group receiving dicofol alone. Exposure to the individual pesticides endosulfan, dichlorvos, and permethrin did not markedly affect sperm motility. The impairment of sperm motility in the mixture of pesticides at the NOEL level indicates that reproductive effects not seen with individual pesticides may occur in presence of several pesticides due to an additive effect. However, the pesticide mixtures did not appear to affect DSP or spermatogenesis despite reduced sperm motility.

Constituents and antiulcer effect of Alchornea glandulosa: Activation of cell proliferation in gastric mucosa during the healing process

Alchornea glandulosa (Euphorbiaceae) is a plant used in folk medicine as an antiulcer agent. Rats pretreated with methanolic extract obtained from the leaves of A. glandulosa (AG) showed a dose-dependent effect and significant reduction of gastric ulcers induced by absolute ethanol at the doses of 500 (57%) and 1000 mg/kg (35%) in relation to the control group. Pretreatment of mice with AG (500, 1000 mg/kg, p.o.) showed dose-dependent activity and significantly decreased the severity of lesions caused by HCl/ethanol and by non steroidal anti inflammatory drug-induced gastric lesions. Pretreatment with AG also induced antisecretory action via local and systemic routes and a significant decrease in the total gastric acid content. The gastroprotective effects of AG involved the participation of nitric oxide and increased levels of endogenous sulfhydryl compounds, which are defensive mechanisms of the gastrointestinal mucosa against aggressive factors. The ability of AG to heal gastric ulcers was evaluated after 14 consecutive days of treatment. The results showed that single oral administrations of AG (250 mg/kg/once daily) potently stimulates gastric epithelial cell proliferation that contributes to the accelerated healing of gastric ulcers induced by acetic acid. In addition, no subacute toxicity (body weight gain, vital organs, and serum biochemical parameters) was observed during treatment with AG. Phytochemical investigation of AG led to the isolation of myricetin-3-O-alpha-L-rhamnopyranoside, quercetin-3-O-alpha-L-arabinopyranoside, quercetin-3-O-beta-D-galactopyranoside, quercetin, amentoflavone, methyl gallate, gallic acid, and pterogynidine. We also established the phytochemical profile of AG with the quantification of total phenolic compounds. These compounds may contribute to the observed antiulcerogenic effects of AG.

Induction of luteolysis in mares utilizing a micro-dose of prostaglandin F-2 alpha in the sacral lumbar space

An experiment was conducted to examine the luteolytic effectiveness of using low or micro doses of PGF(2 alpha) when administered at the (BAI HUI) acupuncture point, which is frequently used to treat ovarian disturbances in Veterinary Acupuncture. The results indicate that PGF(2 alpha) given at a very low micro dose of 0.5mg (one tenth the conventional recommended dose) when administered at the BAI HUI acupuncture point located at the sacral lumbar space is equally effective at inducing luteolysis in mid-luteal phase mares as conventional PGF(2 alpha) i.m. treatment using a tenfold higher dose. Therefore, based on the results of the present study we suggest that the BAI HUI sacral lumbar route somehow provides an extremely efficient pathway for the drug to the ovarian level.

Use of a Low Dose of Equine Purified FSH to Induce Multiple Ovulations in Mares

The effects of a low dose of equine purified FSH (eFSH) on incidence of multiple ovulations and embryo recovery rate in mares were studied. During the physiological breeding season in Brazil (19 degrees 45'45'S), 14 Mangalarga Marchador donor mares were used in a crossover study and another 25 mares of the same breed, between 3 years and 12 years of age were used as recipients for the embryo transfers. Donors were monitored during two consecutive oestrus cycles, an untreated control cycle followed by a treated cycle, when eFSH was administered. In both cycles, after an embryo collection attempt on day 8 post-ovulation all mares received 7.5 mg dinoprost and had their two largest follicles tracked daily by ultrasonography until the period of ovulation. Mares were inseminated every 48 h with extended fresh semen from a single stallion after the identification of a 35-mm follicle until the period of ovulation. Ovulations were induced by intravenous administration of 2.500 IU of human chorionic gonadotropin, upon detection of a 35- to 40-mm follicle. In the treated cycle, 5 mg eFSH was given intramuscularly once a day, from day 8 post previous ovulation until at least one follicle reached 35 mm in diameter. Embryo flushes were performed on day 8 of dioestrus (day 0 = ovulation). Treatment with eFSH resulted in higher (p < 0.05) ovulation rate and incidence of multiple ovulations compared to the control (1.6 vs 1.0 and 50% vs 0%, respectively - one mare had triple ovulation). However, embryo recovery rates in the control and treated cycles were similar (0.8 and 1.0, respectively; p > 0.05). Pregnancy rates in the recipient mares following embryo transfer were similar for the control and eFSH cycles (11/11 and 10/14, respectively). Additional studies are necessary in order to develop a low-dose protocol for the use of eFSH that brings a more consistent contribution to the efficiency of commercial equine embryo transfer programs.

Efeito da nicotina na viabilidade e morfologia de fibroblastos: estudo in vitro

O objetivo do estudo foi avaliar in vitro o efeito da nicotina sobre a viabilidade e a morfologia celular utilizando-se uma linhagem contínua de fibroblastos. Para tal, foram formados dois grupos experimentais segundo a dose (0 - controle, 10 mig, 100 mig, 0,5 mg, 1 mg) e o tempo de condicionamento (1 e 24 horas). Cada um dos 12 orifícios de uma placa para cultura celular recebeu 2 ml de meio de Eagle, e 1 ml de suspensão de meio de cultura contendo aproximadamente 1 × 10(5) células/ml. Foi, então, acrescentada a solução de nicotina nas diferentes concentrações. Após o condicionamento com a droga, nos dois períodos testados, as células foram coradas com azul de trypan 0,4%, e observadas em microscópio invertido por um examinador cego para os grupos experimentais, que avaliou a viabilidade e a morfologia segundo o índice de Gamal. Os experimentos foram repetidos 5 vezes. Quanto à morfologia, os resultados obtidos demonstraram, no grupo condicionado por 1 h, que os controles apresentaram diferenças estatisticamente significantes em relação apenas à maior dose de nicotina; no entanto, foram encontradas diferenças estatisticamente significantes entre o controle e todas as concentrações após 24 horas de condicionamento. Na viabilidade celular, um maior número de células não viáveis foi observado nas diferentes concentrações de nicotina em comparação aos controles tanto após 1 quanto 24 horas de condicionamento (p < 0,05). em ambos períodos existiu uma tendência significativa de aumento do número de células não viáveis com o aumento da dose de nicotina (p = 0,0053; p = 0,00001 após 1 e 24 h respectivamente). Portanto, conclui-se que a nicotina pode alterar, in vitro, a viabilidade e a morfologia de fibroblastos de forma proporcional à dose e ao tempo de exposição.

Can a Strychnos species be used as antiulcer agent? Ulcer healing action from alkaloid fraction of Strychnos pseudoquina St. Hil. (Loganiaceae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Antiulcerogenic activity of four extracts obtained from the bark wood of Quassia amara L. (Simaroubaceae)

Quassia amara L., a neotropical forest shrub of the Simaroubaceae family, is widely used in Caribbean folk medicine and in some northern states of Brazil for the treatment of gastric ulcers. This plant is a source of numerous compounds including both beta-carbonile and cantin-6 alkaloids as well as, primarily, the bitter compounds known as quassinoids. We analyzed the possible antiulcerogenic activities of four extracts of different polarities: 70% ethanol (70% EtOH), 100% EtOH, 100% dichloromethane (DCM), and 100% hexane (HEX) obtained from Quassia amara bark. All extracts, administered at doses of 5000 mg/kg orally and 1000 mg/kg intraperitoneally, caused neither toxicity or death. In the indomethacin[bethanechol-induced gastric ulcer, 70% EtOH, 100% EtOH, DCM and HEX extracts, 100 mg/kg, p.o., inhibited the gastric ulcer (22.5, 23.4, 50.5, 46.8%, respectively). 70% EtOH, 100% EtOH, DCM, and HEX extracts reduced the gastric injury induced by the hypothermic restraint-stress test in mice (70.7, 80, 60, 82.7%, respectively). In the pylorus ligature of the mouse stomach, following pre-treatment with a single intraduodenal administration of 100 mg/kg of each extract, only 70% EtOH did not change the biochemical parameters of gastric juice. 100% EtOH, DCM and HEX extracts presented decreased gastric juice content, increased pH values and decreased acid output. We also determined the antiulcerogenic activity on HCl-EtOH-induced gastric ulcers in mice at four doses (25, 50, 75, 100 mg/kg, p.o.), then evaluated the possible dose-dependent relation and calculated the ED50 values. Except for 70% EtOH at a dose of 25 mg/kg, the other extracts showed significantly activity (p<0.05). The free mucous amount in the gastric stomach content was also evaluated. All extracts showed significant increases (p<0.05) of free mucous. This effect was abolished when the animals were pre-treated with indomethacin. Prostaglandin synthesis was evaluated by the administration of HEX extracts by the oral route (100 mg/kg). Prostaglandin synthesis was significantly, increased by 52.3% (p<0.05), and this effect was abolished with prior administration of indomethacin. We concluded that Quassia amara is a probable source for a new drug to treat gastric ulcers, and the mechanism of its activity relates to cytoprotective factors, such as mucous and prostaglandins, but there is still the possibility that antisecretory activity is involved in its antiulcerogenic effect.

In situ evaluation of anticancer drug methotrexate-DNA interaction using a DNA-electrochemical biosensor and AFM characterization

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Inhibition of myotoxic activity of Bothrops asper myotoxin II by the anti-trypanosomal drug surarnin

Suramin, a synthetic polysulfonated compound, developed initially for the treatment of African trypanosomiasis and onchocerciasis, is currently used for the treatment of several medically relevant disorders. Suramin, heparin, and other polyanions inhibit the myotoxic activity of Lys49 phospholipase A(2) analogues both in vitro and in vivo, and are thus of potential importance as therapeutic agents in the treatment of viperid snake bites. Due to its conformational flexibility around the single bonds that link the central phenyl rings to the secondary amide backbone, the symmetrical suramin molecule binds by an induced-fit mechanism complementing the hydrophobic surfaces of the dimer and adopts a novel conformation that lacks C2 symmetry in the dimeric crystal structure of the suramin-Bothrops asper myotoxin II complex. The simultaneous binding of suramin at the surfaces of the two monomers partially restricts access to the nominal active sites and significantly changes the overall charge of the interfacial recognition face of the protein, resulting in the inhibition of myotoxicity. (c) 2005 Elsevier Ltd. All rights reserved.

Short and long period optimization of drug doses in the treatment of AIDS

Técnicas de otimização numérica são úteis na solução de problemas de determinação da melhor entrada para sistemas descritos por modelos matemáticos e cujos objetivos podem ser expressos de uma maneira quantitativa. Este trabalho aborda o problema de otimizar as dosagens dos medicamentos no tratamento da AIDS em termos de um balanço entre a resposta terapêutica e os efeitos colaterais. Um modelo matemático para descrever a dinâmica do vírus HIV e células CD4 é utilizado para calcular a dosagem ótima do medicamento no tratamento a curto prazo de pacientes com AIDS por um método de otimização direta utilizando uma função custo do tipo Bolza. Os parâmetros do modelo foram ajustados com dados reais obtidos da literatura. Com o objetivo de simplificar os procedimentos numéricos, a lei de controle foi expressa em termos de uma expansão em séries que, após truncamento, permite obter controles sub-ótimos. Quando os pacientes atingem um estado clínico satisfatório, a técnica do Regulador Linear Quadrático (RLQ) é utilizada para determinar a dosagem permanente de longo período para os medicamentos. As dosagens calculadas utilizando a técnica RLQ , tendem a ser menores do que a equivalente terapia de dose constante em termos do expressivo aumento na contagem das células T+ CD4 e da redução da densidade de vírus livre durante um intervalo fixo de tempo.

Effects of a single near-infrared laser treatment on cutaneous wound healing: Biometrical and histological study in rats

Background: Low intensity laser therapy has been recommended to support the cutaneous repair; however, so far studies do not have evaluated the tissue response following a single laser treatment. This study investigated the effect of a single laser irradiation on the healing of full-thickness skin lesions in rats.Methods: Forty-eight male rats were randomly divided into three groups. One surgical lesion was created on the back of rats using a punch of 8 mm in diameter. One group was not submitted to any treatment after surgery and it was used as control. Two energy doses from an 830-nm near-infrared diode laser were used immediately post-wounding: 1.3 J cm(-2) and 3 J cm(-2). The laser intensity 53 mW cm(-2) was kept for both groups. Biometrical and histological analyses were accomplished at days 3, 7 and 14 post-wounding.Results: Irradiated lesions presented a more advanced healing process than control group. The dose of 1.3 J cm(-2) leaded to better results. Lesions of the group irradiated with 1.3 J cm(-2) presented faster lesion contraction showing quicker re-epithelization and reformed connective tissue with more organized collagen fibers.Conclusions: Low-intensity laser therapy may accelerate cutaneous wound healing in a rat model even if a single laser treatment is performed. This finding might broaden current treatment regimens. (c) 2007 Elsevier B.V. All rights reserved.

Anti-inflammatory efficacy of a single posterior subtenon injection of triamcinolone acetonide versus prednisolone acetate 1% eyedrops after pars plana vitrectomy

Purpose: To compare the safety and anti-inflammatory efficacy of a single posterior subtenon injection of triamcinolone acetonide (TA) with prednisolone acetate 1% eyedrops after pars plana vitrectomy (PPV).Methods: the study included 40 consecutive phakic eyes of 40 patients undergoing PPV for non-clearing vitreous haemorrhage with attached retina (verified by echography), epiretinal membrane or macular hole. At the end of the surgical procedure, eyes were randomized to receive either a single posterior subtenon injection of TA (40 mg in 1 ml) plus sham eyedrops (prednisolone acetate 1% vehicle) postoperatively (group TA), or a posterior subtenon sham injection (1 ml balanced salt solution) plus prednisolone acetate 1% eyedrops postoperatively (group ED).Results: There was no difference in the severity of anterior chamber cell and flare between the two groups at any time-point during the study period (p > 0.05). Separate within-group analysis revealed a significant decrease in anterior chamber cell and flare from postoperative day 1 to postoperative days 7, 14 and 28 in both groups (p < 0.05). There was no difference in pain, photophobia, conjunctival erythema, ciliary flush or chemosis scores between the two groups at any time-point during the study period (p > 0.05). Steroid-induced intraocular hypertension was not observed in either group.Conclusions: A single posterior subtenon injection of TA can be as effective and safe as a 4-week regimen of prednisolone acetate 1% eyedrops in controlling intraocular inflammation after PPV.

Phentolamine bioequivalence study

Objective: To assess the bioequivalence of 2 tablet formulations of phentolamine (Regitine phentolamine 40 mg tablet formulation by Novartis, Brazil, as test formulation, and Vasomax, phentolamine 40 mg tablet formulation by Schering Plough S.A., Brazil, as reference formulation). Methods: A single 40 mg oral dose of each formulation was administered to 36 male healthy volunteers. The study was conducted after screening, using an open, randomized, 2-period crossover design, a 7-day interval between doses, and wash-out period of at least 4 weeks. Plasma samples for determination of phentolarnine were obtained predose and at intervals over 720 min postdose. Plasma concentrations were quantified by reversed-phase liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS) with positive ion electrospray ionization using multiple reactions monitoring (MRM) method. Precision of the method was evaluated using calibration curves and plasma quality control samples. The subjects were monitored throughout the study. Systolic and diastolic blood pressure and pulse rate measurement were taken predose and at intervals up to 720 min. Tolerance of both products was good. No serious adverse reactions were reported. The pharmacokinetic parameters calculated for both compounds included: AUC((0-720 min)), AUC((0-infinity)), C-max,C- C-max/AUC((0-720 min),) t(max), t(1/2) and k(c). Results: the maximum concentrations reached (Cmax) were compared. Regitine 40 mg formulation C-max geometric mean ratio was 108.29% (90% Cl = 98.58 - 118.96) of Vasomax 40 mg formulation. The areas under the curve (AUC((0-720 min))) were compared. Regitine 40 formulation (AUC((0-720 min)) geometric mean ratio was 102.33% (90% Cl = 97.21 - 107.72) of Vasomax 40 mg formulation. Conclusion: Since the 90% Cl for both Cmax and AUC ratio where inside the 80 to 125% interval proposed by the Food and Drug Administration, it is concluded that Regitine 40 mg tablet is bioequivalent to Vasomax for the rate and extent of absorption.

Tissue tolerance of diclofenac sodium encapsulated in liposomes after intramuscular administration

In this work the effect of the encapsulation of diclofenac sodium within liposomes on the reduction of the myotoxicity after intramuscular administration in rats was studied. Diclofenac sodium was encapsulated in small unilamellar liposomes obtained from phosphatidylcholine, cholesterol, and a-tocopherol (40:10:0.04 mM), and administered by intramuscular injection in the quadriceps femoral muscle of male Wistar rats. After a single dose of 0.2 mg diclofenac formulations the local tissue damage was assessed by plasma creatine kinase (CPK) activity and histological analysis. It was demonstrated that formulations containing free diclofenac produced a higher increase in CPK activity, while those encapsulated in liposomes exhibited CPK activity similar to the control groups. Histopathological analysis of local muscle tissue performed on the third and seventh days following the injection showed intense cellular damage when free drug solution was used, while encapsulation in liposome protected the tissue against the local tissue inflammation.