Microcystin-producing genotypes from cyanobacteria in Brazilian reservoirs

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

Static balance and function in children with cerebral palsy submitted to neuromuscular block and neuromuscular electrical stimulation: Study protocol for prospective, randomized, controlled trial

Background: The use of botulinum toxin A (BT-A) for the treatment of lower limb spasticity is common in children with cerebral palsy (CP). Following the administration of BT-A, physical therapy plays a fundamental role in potentiating the functionality of the child. The balance deficit found in children with CP is mainly caused by muscle imbalance (spastic agonist and weak antagonist). Neuromuscular electrical stimulation (NMES) is a promising therapeutic modality for muscle strengthening in this population. The aim of the present study is to describe a protocol for a study aimed at analyzing the effects of NMES on dorsiflexors combined with physical therapy on static and functional balance in children with CP submitted to BT-A.Methods/Design: Protocol for a prospective, randomized, controlled trial with a blinded evaluator. Eligible participants will be children with cerebral palsy (Levels I, II and III of the Gross Motor Function Classification System) between five and 12 years of age, with independent gait with or without a gait-assistance device. All participants will receive BT-A in the lower limbs (triceps surae). The children will then be randomly allocated for either treatment with motor physical therapy combined with NMES on the tibialis anterior or motor physical therapy alone. The participants will be evaluated on three occasions: 1) one week prior to the administration of BT-A; 2) one week after the administration of BT-A; and 3) four months after the administration of BT-A (end of intervention). Spasticity will be assessed by the Modified Ashworth Scale and Modified Tardieu Scale. Static balance will be assessed using the Medicapteurs Fusyo pressure platform and functional balance will be assessed using the Berg Balance Scale.Discussion: The aim of this protocol study is to describe the methodology of a randomized, controlled, clinical trial comparing the effect of motor physical therapy combined with NMES on the tibialis anterior muscle or motor physical therapy alone on static and functional balance in children with CP submitted to BT-A in the lower limbs. This study describes the background, hypotheses, methodology of the procedures and measurement of the results.

Histopathological changes induced by extracts from the tissue covering the stingers of Potamotrygon falkneri freshwater stingrays

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

Supersensitivity of the isolated guinea-pig vas deferens induced by a toxic fraction of scorpion venom (Tityus serrulatus)

1. Tityustoxin (TsTx), a toxic fraction of Tityus serrulatus venom, was studied on the isolated guinea-pig vas deferens. It increased significantly the maximal response of the preparation to both norepinephrine and acetylcholine and decreased the effective median dose of norepinephrine. 2. The effect of TsTx on norepinephrine median dose was unchanged when atropinized or pharmacologically 'denervated' preparations were used but was abolished when both procedures were associated. 3. Atropinization of pharmacologically denervated muscles almost never modify the TsTx-induced increase in the maximal response to norepinephrine. 4. On denervated or phentolamine-treated muscles TsTx-induced increase in the maximal response to acetylcholine was abolished. 5. It was concluded that toxin predominantly induces adrenergic postsynaptic supersensitivity. 6. Of minor significance, it also induces presynaptic cholinergic and adrenergic supersensitivity. 7. Comparison of these results with those of crude venom indicates that TsTx effects may result from the sum of the effects of subcomponents not demonstrated by the chemical procedures here utilized.

High-performance gel filtration patterns of venoms from three species of wasps of the genus Polybia (hymenoptera, vespidae).

The profiles of high-performance gel filtration of venoms from Polybia paulista, Polybia ignobilis and Polybia occidentalis occidentalis showed 13 peaks distributed among the three species. These profiles presented similarities that permitted the chromatographic characterization of the genus Polybia and differences that permitted the identification of each species studied. Thus, the comparative analysis of chromatographic profiles of high-performance gel filtration of venoms may be used as an auxiliary tool in taxonomic studies of Polybia wasps.

Sistema de ensino à distância sobre toxinologia: implantando um novo paradigma

The author suggests a long-distance teaching on toxinology using the following media: conventional printed book, scientific electronic journal, video library and the Internet. These new media are discussed as new alternatives for long-distance learning without the teacher.

Polybitoxins: A group of phospholipases A2 from the venom of the neotropical social wasp paulistinha (Polybia paulista)

The neotropical wasp Polybia paulista is very aggressive and endemic in south-east Brazil, where it frequently causes stinging accidents. By using gel filtration on Sephadex G-200, followed by ion-exchange chromatography on DEAE-Cellulose under a pH gradient, a group of four toxins (designated as polybitoxins-I, II, lII and IV) presenting phospholipase A2 (PLA2) activities was purified. These toxins are dimeric with mol. wts ranging from 115,000 to 132,000 and formed by different subunits. The four toxins contain very high sugar contents attached to their molecules (22-43% w/w) and presented different values of pH optimum from 7.8 to 9.0; when dissociated, only residual catalytic activities were maintained. The catalytic activities of polybitoxins (from 18 to 771 μmoles/mg per minute) are lower than that of PLA2 from Apis mellifera venom and hornetin from Vespa basalis. The polybitoxins presented a non-linear steady-state kinetic behavior for the hydrolysis of phosphatidylcholine at pH 7.9, compatible with the negative co- operativity phenomena. All of the polybitoxins were very potent direct hemolysins, especially the polybitoxins-III and IV, which are as potent as the lethal toxin from V. basalis and hornetin from Vespa flavitarsus, respectively; polybitoxin-IV presented hemolytic action 20 times higher than that of PLA2 from A. mellifera, 17 times higher than that of neutral PLA2 from Naja nigricolis and about 37 times higher than that of cardiotoxin from Naja naja atra venom.

Ultrastructural changes on the epithelial cells of uterine tubes of Wistar rats after chronic ethanol ingestion

The present paper describes the morphological alterations of the epithelial layer of the uterine tubes of rats submitted to experimental chronic alcoholism using anatomical, histological, ultrastructural and morphometric methods. Sixty adult rats (Rattus norvegicus albinus) at the same age (3 months) and with a mean body weight of 228 g were divided into two groups. The control group received solid diet (Purina rat chow) and tap water ad libitum. The alcoholic group received the same solid diet and was allowed to drink only sugar cane brandy dissolved in 30° Gay Lussac (v/v). After periods of 90, 180 and 270 days of treatment animals at normal estrus were anaesthetised with ethyl ether, weighed and sacrificed. Subsequently, the uterine tubes were dissected, weighed and prepared for TEM and SEM methods. The final mean body weights were similar in the control and alcoholic groups. The morphometric analysis showed no difference between control and alcoholic epithelial height. The alcoholic animals showed ultrastructural alterations: intense lipid droplet and lysosomes accumulation, dilated rough endoplasmic reticulum cisternae and vacuolization in both periods of treatment. It was concluded that alcohol acts as a toxin on the epithelial layer of the uterine tubes of rats.

Study of the presence of the spores of Clostridium botulinum in honey in Brazil

The isolation of Clostridium botulinum from honey samples is described. Botulism is characterized as an intoxication provoked by ingestion of contaminated foods with this toxin. Infant botulism happens by the ingestion of spores of C. botulinum together with food that in special conditions of the intestinal tract, such as those present in babies of less than 1 year old, will allow the germination and colonization of the intestine with production and absorption of botulinic toxin. The samples were subjected to dilution and to a thermal shock and cultivated in modified CMM (Difco). Cultures were subjected to Gram smears and toxicity tests in mice. The toxic cultures were purified in RFCA (Oxoid) plates and incubated in anaerobic jars. Positive samples were typed using the mouse assay neutralization test. From the 85 honey samples analyzed, six were positive for C. botulinum (7.06%), and identified as producers of type A, B, and D toxins.

Effects of chronic experimental alcoholism on the epithelium of the uterine horn of rats (Rattus norvegicus albinus)

Sixty adult tats (Rattus norvegicus albinus) of the same age (3 months) and with a mean body weight of 228 g were divided into two experimental groups. The control group received solid diet (Purina rat chow) and tap water ad libitum. The other (alcoholic group), received the same solid diet and was allowed to drink only sugar cane brandy dissolved in 30° Gay Lussac (v/v). At the end of periods of 90, 180 and 270 days of treatment, the animals were anaesthetized with ethyl ether during estrus, weighed and sacrificed. The final mean body weights were similar in the control and alcoholic groups. The results showed intense atrophy on the lining epithelium of the endometrium of uterine horns in the alcoholic group. Important ultrastructural epithelial alterations were also observed in the female alcoholic group, such as: intense lipid droplet accumulation, increased rough endoplasmic reticulum cisternae and mitochondrial size and presence of intraepithelial neutrophils. The secretory activity of these rats was reduced. Therefore, we concluded that alcohol acts as a toxin on the epithelial layer of the rat endometrium.

Occurrence of killer yeasts in leaf-cutting ant nests

Killer activity was screened in 99 yeast strains isolated from the nests of the leaf-cutting ant Atta sexdens against 6 standard sensitive strains, as well as against each other. Among this yeast community killer activity was widespread since 77 strains (78 %) were able to kill or inhibit the growth of at least one standard strain or nest strain. Toxin production was observed in representatives of all the studied genera including Aureobasidium, Rhodotorula, Tremella and Trichosporon, whose killer activity has not yet been described.

Anesthesia of fish with benzocaine does not interfere with comet assay results

Fish blood erythrocytes are frequently used as sentinels in biomonitoring studies. Usually, fish blood is collected by painful cardiac or caudal vein punctures. Previous anesthesia could decrease animal suffering but it is not known at present whether anesthesia can cause confounding effects. Therefore, using the alkaline single cell gel (SCG)/comet assay with blood erythrocytes of the cichlid fish Nile tilapia, we tested for a possible modulation of induced DNA damage (methyl methanesulfonate; MMS) by the anesthetic benzocaine administered by bath exposure (80mg/l for ∼10min). Furthermore, benzocaine (80-600mg/l) was tested for its genotoxic potential on fish erythrocytes in vitro and for potential interactions with two known genotoxins (MMS and hydrogen peroxide). Our results did neither indicate a significant increase in the amount of DNA damage (even after a 48h follow-up), nor indicated interactions with MMS-induced DNA damage when fish were exposed to benzocaine in vivo. There was also no increase in DNA damage after in vitro exposure of fish erythrocytes to benzocaine. Clear concentration-related effects were observed for the two genotoxins in vitro, which were not significantly altered by the presence of benzocaine. These results suggest that anesthesia of fish does not confound comet assay results and the use of blood samples from anesthetized fish can be recommended with regard to animal welfare. © 2002 Elsevier Science B.V. All rights reserved.