LD5o of the bacteria Aeromonas hydrophila to matrinxã, Brycon amazonicus

In order to determine the lethal dose (96-h LD50) of the bacteria Aeromonas hydrophila to matrinxã, Brycon amazonicus, to be applied in challenge tests, 90 fish (63.23 ± 6.39 g) were divided into five treatments, with different bacterial solutions: T1 - Control (0.9% NaCl saline solution); T2 (4 x 10(11) cells/ mL); T3 (5 x 10(11) cells/ mL); T4 (1.36 x 10(12) cells/ mL) and T5 (3.06 x 10(12) cells/ mL). Fish were previously anesthetized with benzocaine (60 mg L-1), inoculated in the peritoneal cavity with the bacterial suspensions and then distributed into fifteen 80-L test chambers, where the water variables were monitored and fish mortality was observed. The experiment was randomly designed in three replicates and the 96-h LD50 was estimated according to the trimmed Spearman-Karber method. Water quality variables remained within adequate ranges for fish health and performance. Fish mortality rate increased with the bacterial concentrations of A. hydrophila (T1 = 0%; T2 = 16.66%; T3 = 44.44%; T4 = 72.22% and T5 = 100%), and the first mortalities were observed after 57 h, although the signs of the bacterial infection were already observed 24 h after the inoculation. The results indicate that the 96-h LD50 value of A. hydrophila to matrinxã is 6.66 x 10(11) cells/ mL.

Some characteristics of hyperreactivity to bacterial lipopolysaccharide induced in mice by Trypanosoma cruzi infection

Mice infected with T. cruzi strain, acquire a high level of susceptibility to the effects of bacterial gram-negative LPS. The LD50 of adult female SW mice to LPS from S. typhosa, decreases from 450 to 2,5 mcg 10-12 days after T. cruzi infection. This hyperreactivity to LPS induced by T. cruzi presents all the characteristics of that found in infection caused by many other agents. During the acaute phase of experimental infection with T. cruzi Y strain, mice generally die with a hypovolemic shock very similar to that induced in uninfected animals injected with an adequate dose of bacterial endotoxin. There is evidence for and against the hypothesis that LPS absorbed from the instestinal tract may be involved in the mechanism of death of mice during the acute phase of T. cruzi infection.

Molluscicide activity of the "Avelós" plant (Euphorbia tirucalli, L. ) on Biomphalaria glabrata, the mollusc vector of schistosomiasis

An aqueous solution of the latex of Euphorbia tirucalli collected at sites receiving large amounts of sunlight showed molluscicide action on Biomphalaria glabrata, with LD50 obtained at the concentration of 28,0 ppm and LD90 at the concentration of 85,0 ppm. The toxicity of the product for fish was similar to that of Bayluscide and of copper sulfate used for comparison. However, the wide distribution of the plant, its easy propagation and the simple procedure for extraction of the active substance, which is biodegradable, favor "avelós" as a promising agent in the control of schistosomiasis.

Identificació de noves dianes terapèutiques en neoplàsies limfoides

El limfoma de cèl•lules de mantell (LCM) és un limfoma de cèl•lules B incurable que presenta sobreexpressió de ciclina D1. Això fa necessari el desenvolupament de noves teràpies. Els gens supressors de tumors estan alterats en càncer pel silenciament epigenètic aberrant, com a conseqüència de la desacetilació de les histones dels seus promotors. Els inhibidors de les desacetilases d'histones (HDACi) són nous compostos amb resultats prometedors per al tractament de tumors. L'objectiu principal, i que ha durat 7 mesos, va ser analitzar l'activitat antitumoral de l'àcid hidroxàmic suberoilanílid (SAHA, vorinostat), un HDACi en fase d'assajos clínics per al tractament de varis tumors, en cèl•lules de LCM. Es va analitzar la sensibilitat al SAHA (Merck Pharmaceuticals) en nou línies cel•lulars humanes de LCM, que es diferenciaven en les alteracions genètiques, les característiques replicatives i la sensibilitat als fàrmacs; i cèl•lules primàries de 6 pacients. El SAHA va presentar un efecte citotòxic heterogeni amb DL50 (Dosi Letal 50) de 3.25 μM a &25 μM amb 24 d'incubació. Aquest efecte citotòxic s'incrementava notablement després de 48 hores d'incubació assolint una DL50 de 0.34 a 5.69 μM. Cal destacar que 5 dels 6 casos de les mostres primàries de LCM van mostrar una elevada sensibilitat (DL50 & 8.07 μM). A nivell mecanistic, el SAHA va augmentar l'acetilació de les histones H3 i H4, i va disminuir els nivells de proteïna de la ciclina D1 i c-Flip. La citometria de flux i els anàlisis per Western Blot van posar de manifest que l'efecte citotòxic del SAHA es dóna a través de l'activació de la via mitocondrial de mort cel•lular i la cascada de caspases. El SAHA indueix l'expressió transcripcional de la proteïna proapoptòtica Bmf. Aquests resultats suggereixen que el SAHA podria ser una nova teràpia prometedora per al tractament del LCM.

Methods for field detection of resistance to temephos in simuliids. Larval esterase level and topical application of the insecticide to adults

Two practical field methods for indirect detection of simuliid populations resistant to temephos are proposed. The first is based on high esterase activity in resistant larvae and involves adaptations of a filter paper test in which faintly stained spots indicate susceptible populations and strongly stained ones reveal populations resistant to temephos. The second is based on the resistance to the larvicide when adults are topically exposed, and involves the use of diagnostic doses obtained by the comparison between the LD50 for susceptible and resistant populations. The relevance of such methods is discussed in order to help resistance detection in Simulium pertinax Kollar control programmes.

Pharmacological and toxicological evaluation of Alpinia speciosa

Alpinia speciosa Schum or A. nutans is a plant of the Zingiberanceae family, Known popularly as "colony" (colônia) and used as a diuretic and to control hypertensión. We have determinated the concentration of Na+ and K+ found in the alcoholic extract and in the tea concoction. They contained 51.0mEq Na+, and 132 mEq K+ in the extract, and 0,0 mEq of Na+ and 26 mEq K+ in the tea. Phytochemical analysis of the leaves demonstrated the presence of catecquic tanins, phenols and alkaloids, and also some essential oils. When injected intra-peritoneally the hydroalcoholic extract, in range of 100 a 1400 mg/Kg, (or 2500-18000 mg/Kg orally) produced in mice: writhing, psychomorot excitation, hypokinesis and pruritus. The LD50 by ip was 0.760 + or - 0.126 g/Kg and 10.0 + or - 2.5 g/Kg by oral administration for the hydroalcoholic extract. Subacute toxicity made injecting daily for 30 days the LD10 in rats caused an increase in transaminases and lactate dehydrogenase, whereas other parameters such as nlood glucose, urea and creatinine were normal. A histopathological analysis of liver, spleen, gut, lung and heart showed no alterations. The drug also produced a prolongation of the sleeping time. The hydroalcoholic extract induced int he rat and in the dog a dose-dependent fall in blood pressure in doses of 10 to 30 mg/Kg. In isolated atria the extract induced a reduction of the frequnecy and in the inotropic responses. Neither the extract nor the tea had an effect on the diuresis of the rat.

Relative susceptibility of different stages of Rhodinius Prolixus to the entomopathogenic Hyphomycete Beauveria Bassiana

Laboratory bioassays were conducted to determine the relative suscepbility of eggs, 1st-, 3rd-, 5th- instar nymphs and adults of Rhodnius prolixus to one isolate of the entomopathogenic hyphomycete, Beauveria bassiana. Treatments consisted of directly spraying on insects of increasing doses of inoculum (3 x 10* to 3 x 10 (elevated to 5th potency) conidia per cm*). Mortality due to all doses of conidia was very high in the five tested stages of the target insect. Experiments on eggs demonstrated that the fungal isolate was able to kill eggs before they hatched. Both time-mortality and dose-mortality responses showed that the susceptibility of R. prolixus varied according to its stage of development and increased with age. As matter of fact, at the dose of 3 x 10* conidia per cm*, LD50 varied between 11.2 days in 1st-instar nymphs and 6.4 days in both 5th-instar nymphs and adults. Comparison of LD50 permitted to estimate that 1st-instar nymphs were about 700-fold less susceptible than the two oldest stages

The value of selected in vitro and in silico methods to predict acute oral toxicity in a regulatory context: results from the European Project ACuteTox.

ACuteTox is a project within the 6th European Framework Programme which had as one of its goals to develop, optimise and prevalidate a non-animal testing strategy for predicting human acute oral toxicity. In its last 6 months, a challenging exercise was conducted to assess the predictive capacity of the developed testing strategies and final identification of the most promising ones. Thirty-two chemicals were tested blind in the battery of in vitro and in silico methods selected during the first phase of the project. This paper describes the classification approaches studied: single step procedures and two step tiered testing strategies. In summary, four in vitro testing strategies were proposed as best performing in terms of predictive capacity with respect to the European acute oral toxicity classification. In addition, a heuristic testing strategy is suggested that combines the prediction results gained from the neutral red uptake assay performed in 3T3 cells, with information on neurotoxicity alerts identified by the primary rat brain aggregates test method. Octanol-water partition coefficients and in silico prediction of intestinal absorption and blood-brain barrier passage are also considered. This approach allows to reduce the number of chemicals wrongly predicted as not classified (LD50>2000 mg/kg b.w.).

Present development concerning antimalarial activity of phospholipid metabolism inhibitors with special reference to in vivo activity

The systematic screening of more than 250 molecules against Plasmodium falciparum in vitro has previously shown that interfering with phospholipid metabolism is lethal to the malaria parasite. These compounds act by impairing choline transport in infected erythrocytes, resulting in phosphatidylcholine de novo biosynthesis inhibition. A thorough study was carried out with the leader compound G25, whose in vitro IC50 is 0.6 nM. It was very specific to mature parasites (trophozoïtes) as determined in vitro with P. falciparum and in vivo with P. chabaudi -infected mice. This specificity corresponds to the most intense phase of phospholipid biosynthesis activity during the parasite cycle, thus corroborating the mechanism of action. The in vivo antimalarial activity (ED50) against P. chabaudi was 0.03 mg/kg, and a similar sensitivity was obtained with P. vinckei petteri, when the drug was intraperitoneally administered in a 4 day suppressive test. In contrast, P. berghei was revealed as less sensitive (3- to 20-fold, depending on the P. berghei-strain). This difference in activity could result either from the degree of synchronism of every strain, their invasion preference for mature or immature red blood cells or from an intrinsically lower sensitivity of the P. berghei strain to G25. Irrespective of the mode of administration, G25 had the same therapeutic index (lethal dose 50 (LD50)/ED50) but the dose to obtain antimalarial activity after oral treatment was 100-fold higher than after intraperitoneal (or subcutaneous) administration. This must be related to the low intestinal absorption of these kind of compounds. G25 succeeded to completely inhibiting parasitemia as high as 11.2% without any decrease in its therapeutic index when administered subcutaneously twice a day for at least 8 consecutive days to P. chabaudi -infected-rodent model. Transition to human preclinical investigations now requires a synthesis of molecules which would permit oral absorption.

Effects of Bayluscide WP 70® on the Survival and Water-leaving Behaviour of Biomphalaria straminea, Snail Host of Schistosomiasis in Northeast Brazil

The toxic and behavioural effects of niclosamide (Bayluscide WP 70®) on Biomphalaria straminea from a highly endemic area of schistosomiasis in northeastern Brazil were investigated through laboratory bioassays. The LD50 and LD90 were 0.114 mg/l and 0.212 mg/l, respectively. Water-leaving behaviour occurred among 14% to 30% of the snails in the presence of sublethal doses of niclosamide and among 16% of the controls. It was concluded that both the relatively low susceptibility to niclosamide and water-leaving behaviour of local B. straminea may be responsible for the recolonization of transmission foci after mollusciciding. It was suggested that recently improved measures of snail control, such as controlled-release formulations of niclosamide and plant molluscicides should be considered in areas where snail control is recommended

Zinc Sulphate in the Treatment of Cutaneous Leishmaniasis: an in Vitro and Animal Study

This study was designed to evaluate the effectiveness of zinc sulphate both in vitro and in an animal model against both strains of old world cutaneous leishmaniasis. The in vitro sensitivities of promastigotes and axenic amastigotes of both Leishmania major and L. tropica to zinc sulphate was determined, the LD50 calculated and compared to the standard treatment for cutaneous leishmaniasis pentavalent antimony compounds. The results show that the two forms of both strains were sensitive to zinc sulphate and their respective LD50 were lower compared to the pentavalent antimony compound. Furthermore the sensitivities of the forms of both strains were tested using a simple slide method and compared to results of the standard method. To confirm this result, zinc sulphate was administered orally to mice infected with cutaneous leishmaniasis both therapeutically and prophylactically. Results showed that oral zinc sulphate was effective in both treatment and prophylaxis for cutaneous leishmaniasis. These results encourage the use of oral zinc sulphate in the treatment of cutaneous leishmaniasis clinically.

Rapidly fatal poisoning with an insecticide containing rotenone.

Introduction: Rotenone is a botanical pesticide derived from extracts of Derris roots, which is traditionally used as piscicide, but also as an industrial insecticide for home gardens. Its mechanism of action is potent inhibition of mitochondrial respiratory chain by uncoupling oxidative phosphorylation by blocking electron transport at complex-I. Despite its classification as mild to moderately toxic to humans (estimated LD50, 300-500 mg/kg), there is a striking variety of acute toxicity of rotenone depending on the formulation (solvents). Human fatalities with rotenone-containing insecticides have been rarely reported, and a rapid deterioration within a few hours of the ingestion has been described previously in one case. Case report: A 49-year-old Tamil man with a history of asthma, ingested 250 mL of an insecticide containing 1.24% of rotenone (3.125 g, 52.1-62.5 mg/kg) in a suicide attempt at home. The product was not labeled as toxic. One hour later, he vomited repeatedly and emergency services were alerted. He was found unconscious with irregular respiration and was intubated. On arrival at the emergency department, he was comatose (GCS 3) with fixed and dilated pupils, and absent corneal reflexes. Physical examination revealed hemodynamic instability with hypotension (55/30 mmHg) and bradycardia (52 bpm). Significant laboratory findings were lactic acidosis (pH 6.97, lactate 17 mmol/L) and hypokalemia (2 mmol/L). Cranial computed tomography (CT) showed early cerebral edema. A single dose of activated charcoal was given. Intravenous hydration, ephedrine, repeated boli of dobutamine, and a perfusor with 90 micrograms/h norepinephine stabilized blood pressure temporarily. Atropine had a minimal effect on heart rate (58 bpm). Intravenous lipid emulsion was considered (log Pow 4.1), but there was a rapid deterioration with refractory hypotension and acute circulatory failure. The patient died 5h after ingestion of the insecticide. No autopsy was performed. Quantitative analysis of serum performed by high-resolution/accurate mass-mass spectrometry and liquid chromatography (LC-HR/AM-MS): 560 ng/mL rotenone. Other substances were excluded by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS/MS). Conclusion: The clinical course was characterized by early severe symptoms and a rapidly fatal evolution, compatible with inhibition of mitochondrial energy supply. Although rotenone is classified as mild to moderately toxic, physicians must be aware that suicidal ingestion of emulsified concentrates may be rapidly fatal. (n=3): stridor, cyanosis, cough (one each). Local swelling after chewing or swallowing soap developed at the earliest after 20 minutes and persisted beyond 24 hours in some cases. Treatment with antihistamines and/or steroids relieved the symptoms in 9 cases. Conclusion: Bar soap ingestion by seniors carries a risk of severe local reactions. Half the patients developed symptoms, predominantly swellings of tongue and/or lips (38%). Cognitive impairment, particularly in the cases of dementia (37%), may increase the risk of unintentional ingestion. Chewing and intraoral retention of soap leads to prolonged contact with the mucosal membranes. Age-associated physiological changes of oral mucosa probably promote the irritant effects of the surfactants. Medical treatment with antihistamines and corticosteroids usually leads to rapid decline of symptoms. Without treatment, there may be a risk of airway obstruction.

Differences of susceptibility of five triatomine species to pyrethroid insecticides - implications for Chagas disease vector control

As pyrethroids are presently the favored group of insecticides to control triatomines, we performed a series of bioassays to determine the intrinsic activity of some of the main compounds used in the control campaigns, against five of the main species of triatomines to be controlled. Comparing the insecticides it can be seen that lambdacyhalothrin is more effective than the other three pyrethroids, both considering the LD50 and 99 for all the three species with comparable results. On Triatoma infestans the LD50 of lambdacyhalothrin was followed by that of alfacypermethrin, cyfluthrin and deltamethrin. On Rhodnius prolixus the sequence, in decreasing order of activity, was lambdacyhalothrin, alfacypermethrin, deltamethrin and cyfluthrin. Some modifications can be seen when we compare the LD99, that has more to see to what happens in the field. T. brasiliensis showed to be as sensible to lambdacyhalothrin as T. infestans, the most susceptible for this product. By the other side T. sordida is the least susceptible considering the LD99 of this insecticide.

Sawhorse-type diruthenium tetracarbonyl complexes containing porphyrin-derived ligands as highly selective photosensitizers for female reproductive cancer cells.

Diruthenium tetracarbonyl complexes of the type [Ru2(CO)4(l2-g2-O2CR)2L2] containing a Ru-Ru backbone with four equatorial carbonyl ligands, two carboxylato bridges, and two axial two-electron ligands in a sawhorse-like geometry have been synthesized with porphyrin-derived substituents in the axial ligands [1: R is CH3, L is 5-(4-pyridyl)-10,15,20-triphenyl-21,23H-porphyrin], in the bridging carboxylato ligands [2: RCO2H is 5-(4-carboxyphenyl)-10,15,20-triphenyl-21,23H-porphyrin, L is PPh3; 3: RCO2H is 5-(4-carboxyphenyl)-10,15,20-triphenyl-21,23H-porphyrin, L is 1,3,5-triaza-7-phosphatricyclo [3.3.1.1]decane], or in both positions [4: RCO2H is 5-(4-carboxyphenyl)-10,15,20-triphenyl-21,23H-porphyrin, L is 5-(4-pyridyl)-10,15,20-triphenyl-21,23H-porphyrin]. Compounds 1-3 were assessed on different types of human cancer cells and normal cells. Their uptake by cells was quantified by fluorescence and checked by fluorescence microscopy. These compounds were taken up by human HeLa cervix and A2780 and Ovcar ovarian carcinoma cells but not by normal cells and other cancer cell lines (A549 pulmonary, Me300 melanoma, PC3 and LnCap prostate, KB head and neck, MDAMB231 and MCF7 breast, or HT29 colon cancer cells). The compounds demonstrated no cytotoxicity in the absence of laser irradiation but exhibited good phototoxicities in HeLa and A2780 cells when exposed to laser light at 652 nm, displaying an LD50 between 1.5 and 6.5 J/cm2 in these two cell lines and more than 15 J/cm2 for the others. Thus, these types of porphyric compound present specificity for cancer cell lines of the female reproductive system and not for normal cells; thus being promising new organometallic photosensitizers.

The molluscicidal activity of the latex of Euphorbia splendens var. hislopii on Melanoides tuberculata (Thiaridae), a snail associated with habitats of Biomphalaria glabrata (Planorbidae)

The use of the latex of Euphorbia splendens var. hislopii was considered as an effective control method for Biomphalaria glabrata in Sumidouro, Rio de Janeiro. However, the appearance and expansion of the snail Melanoides tuberculata since August 1997, with the concomitant reduction of the population of B. glabrata suggest that competitive exclusion might be taking place. Depending on the susceptibility of the thiarid to the E. splendens toxin, the natural control that is occurring could be interrupted by the employment of the latex if the planorbid were less susceptible to the toxin. The aim of this study is to investigate the molluscicidal activity of the latex on M. tuberculata. We used 420 M. tuberculata, from Sumidouro. Fourteen different latex concentrations were tested using World Health Organization general methodology. Probit analysis was used for LD90 and LD50 determination. The LD50 was 3.57 mg/l and LD90 was 6.22 mg/l. At the highest concentration (10 mg/l) there was no survival. No significant differences among replicas (chi2 = 8.31; gl = 13; p > 0.05) were found. The LD90 dose for M. tuberculata was 13.8 times greater than that for B. glabrata, so that the molluscicide in the presence of the thiarid may have a synergic effect on reduction of Biomphalaria populations.