Residual concentrations of antimicrobial growth promoters in poultry litter favour plasmid conjugation among Escherichia coli.

Considering that plasmid conjugation is a major driver for the dissemination of antimicrobial resistance in bacteria, this study aimed to investigate the effects of residual concentrations of antimicrobial growth promoters (AGPs) in poultry litter on the frequencies of IncFII-FIB plasmid conjugation among Escherichia coli organisms. A 2 × 5 factorial trial was performed in vitro, using two types of litter materials (sugarcane bagasse and wood shavings) and five treatments of litter: non-treated (CON), herbal alkaloid sanguinarine (SANG), AGPs monensin (MON), lincomycin (LCM) and virginiamycin (VIR). E. coli H2332 and E. coli J62 were used as donor and recipient strains, respectively. The presence of residues of monensin, lincomycin and virginiamycin increased the frequency of plasmid conjugation among E. coli in both types of litter materials. On the contrary, sanguinarine significantly reduced the frequency of conjugation among E. coli in sugarcane bagasse litter. The conjugation frequencies were significantly higher in wood shavings compared with sugarcane bagasse only in the presence of AGPs. Considering that the presence of AGPs in the litter can increase the conjugation of IncFII-FIB plasmids carrying antimicrobial resistance genes, the real impact of this phenomenon on the dissemination of antimicrobial resistant bacteria in the poultry production chain must be investigated.

Microbiological, immunological, and histological changes in the gut of Salmonella Enteritidis-challenged rats fed goat cheese containing Lactobacillus rhamnosus EM1107.

Cheeses are able to serve as suitable matrices for supplying probiotics to consumers, enabling appropriate conditions for bacteria to survive gastric transit and reach the gut, where they are assumed to promote beneficial processes. The present study aimed to evaluate the microbiological, immunological, and histological changes in the gut of Salmonella Enteritidis-challenged rats fed goat cheese supplemented with the probiotic strain Lactobacillus rhamnosus EM1107. Thirty male albino Wistar rats were randomly distributed into 5 experimental groups with 6 animals each: negative (NC) and positive (PtC) control groups, control goat cheese (CCh), goat cheese added with L. rhamnosus EM1107 (LrCh), and L. rhamnosus EM1107 only (EM1107). All animals, except NC group were challenged with Salmonella Enteritidis (109 cfu in 1 mL of saline through oral gavage). Microbial composition was assessed with high-throughput 16S rRNA sequencing by means of Illumina MiSeq (Illumina, San Diego, CA). Nuclear factor kappa B (NF-κB) from the animal cecum tissue was determined by real-time PCR and interleukins (TNF-α, IL-1ß, IL-10, and IFN-γ) by means of ELISA. Myeloperoxidase and malondialdehyde levels were determined biochemically. The administration of the L. rhamnosus EM1107 probiotic strain, either as a pure culture or added to a cheese matrix, was able to reduce Salmonella colonization in the intestinal lumen and lessen tissue damage compared with rats from PtC group. In addition, the use of cheese for the probiotic strain delivery (LrCh) was associated with a marked shift in the gut microbiota composition toward the increase of beneficial organisms such as Blautia and Lactobacillus and a reduction in NF-κB expression. These findings support our hypothesis that cheeses might be explored as functional matrices for the efficacious delivery of probiotic strains to consumers.

Polymorphism of mitochondrial DNA in the Brazilian Canindé goat breed.

The success of the geographical distribution of goat populations around the world is a consequence of the adaptive potential of these breeds. Several relevant traits to the success of the species in colonizing different ecosystems (and use by man) evolved before domestication. These features were relevant for the selection of different breeds. Each breed represents a genetic heritage that may be unique and essential for maintaining the species. The objective of this study was to catalog the mtDNA haplotypes of the Brazilian autochthonous Canindé goat breed and to characterize the genetic diversity observed in subpopulations by sequencing a 481-bp fragment corresponding to the first portion of the control region in 178 individuals from 10 herds, sampled in six Brazilian states. The global population displays a total of 29 haplotypes and 56 polymorphic sites. About one-third (10) of the haplotypes were common to all subpopulations while the remaining (19) were exclusive to a single subpopulation. The population exhibited high average haplotype diversity (0.82), with maximum and minimum values of 0.90 and 0.56 in individual subpopulations, respectively. In contrast, nucleotide diversity was 0.014, with maximum and minimum values of 0.020 and 0.004, respectively. The spatial analysis of molecular variance did not detect structure within the Canindé goat breed, and analysis of molecular variance revealed that 88.4% of the variation observed in the population was due to differences among individuals in the same subpopulation. Only 11.4% of the genetic variation referred to differences among subpopulations. About one-third (33.1%) of the individuals within population shared the same haplotype, which may be due not only to the breed developing from a small number of matrilines. The Brazilian autochthonous Canindé breed was classified as haplogroup A, a haplotype predominant in the Europe region.

Phenotypic and genotypic characterization of two Toxoplasma gondii isolates in free-range chickens from Uberlândia, Brazil.

The aim of this study was to determine the seroprevalence of Toxoplasma gondii infection in free-range chickens from Uberlândia, Minas Gerais state, Brazil, and characterize the genotypic and phenotypic features of two isolates of this parasite, considering the importance of these hosts in the epidemiology of toxoplasmosis. Serum samples from 108 free-range chickens were obtained from ten different districts, and submitted to the modified agglutination test (MAT) for the presence of anti-T. gondii antibodies, and brain and heart tissue samples from infected chickens were processed for mouse bioassay. An overall seroprevalence of 71·3% was found and antibody titres ranged from 16 to 4096. After confirmation of seropositivity by mouse bioassay, the determination of the T. gondii genotypes of two isolates was performed by PCR-RFLP, using primers for the following markers: SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, new SAG2, Apico and CS3. These T. gondii isolates, designated TgChBrUD1and TgChBrUD2, were obtained from heart samples of free-range chickens. The TgChBrUD1 isolate belonged to ToxoDB PCR-RFLP genotype 11 and the TgChBrUD2 isolate belonged to ToxoDB PCR-RFLP genotype 6. Both isolates demonstrated high virulence in a rodent model, with the TgChBrUD1 isolate able to induce brain cysts, in accord with its pattern of multiplication rates in human fibroblast culture. Taken together, these results reveal high prevalence of T. gondii infection in free-range chickens throughout Uberlândia, indicating an important degree of oocyst environmental contamination and the existence of considerable risk for T. gondii transmission to humans by consumption of free-range chicken as a food source.

Can probiotic gargles reduce post-tonsillectomy morbidity in adult patients? A pilot, triple-blind, randomised, controlled trial and feasibility study.

OBJECTIVE: This study aimed to determine the efficacy of probiotic gargles compared with placebo gargles on reducing post-tonsillectomy morbidity in adults. METHOD: This was a triple-blind, randomised, controlled trial and feasibility study. Thirty adults underwent elective tonsillectomy and were randomly assigned to receive either probiotic or placebo gargles for 14 days after surgery. Daily pain scores and requirement of analgesia were measured for 14 days post-operatively. Secondary outcomes assessed probiotic safety and tolerability and the feasibility of the trial. RESULTS: The probiotic group experienced less pain at rest on day 2. However, the amount of oxycodone (5 mg) tablets used was greater in the probiotic group compared with placebo. There were no statistically significant differences in the frequency of adverse effects between both groups. This trial was feasible. CONCLUSION: This pilot study suggested that probiotic gargles do not reduce post-tonsillectomy pain or bleeding, highlighting the importance of pilot and feasibility studies in clinical research.

Evaluation of cleaning and sterilization of liposuction cannulas after intentional contamination with human fat, Mycobacterium abscessus subspecies bolletii, and Geobacillusstearothermophilus.

BACKGROUND: The complex design of cannulas is a major challenge for reprocessing due to the retention and accumulation of fat residues. AIM: To evaluate the cleaning of liposuction cannulas and the protective effects of the remaining fat residues on Mycobacterium abscessus subspecies bolletii (MASB) and Geobacillus stearothermophilus inactivation during steam sterilization. METHODS: In phase 1, six standard operating procedures were evaluated for cleaning of liposuction cannulas. In phase 2, the sectioned lumens of the liposuction cannulas were contaminated with the largest and smallest volume of human fat found in phase 1, with the addition of MASB. In phase 3, the same volumes of human fat from phase 2 were used to contaminate paper strips containing G. stearothermophilus. FINDINGS: In phase 1 the residual amount of fat ranged from 6 to 52 mg. In phases 2 and 3, the minimum and maximum amounts of fat (6 and 50 mg) protected micro-organisms during steam sterilization at 134 °C for 1.5 and 3 min. CONCLUSION: Effective cleaning and sterilization of liposuction cannulas intentionally contaminated with human fat, MASB and G. stearothermophilus could not be performed.

Multiple genetic variants explain measurable variance in type 2 diabetes-related traits in Pakistanis.

AIMS/HYPOTHESIS: Multiple genetic variants are associated with type 2 diabetes-related traits in Europeans, but their role in South Asian populations needs further study. We hypothesised that genetic variants associated with diabetes-related traits in Europeans would explain a similar proportion of phenotypic variance in a Pakistani population and could be used in Mendelian randomisation analyses. METHODS: We used data from 2,131 individuals from the Control of Blood Pressure and Risk Attenuation Trial (COBRA) in Karachi, Pakistan. Individuals were aged 40 years or older. RESULTS: Combining information from multiple genetic variants showed that fasting glucose, BMI, triacylglycerol, and systolic and diastolic blood pressure variants explained 2.9%, 0.7%, 5.5%, 1.2% and 1.8% of the variance in those traits respectively. Genetic risk scores of fasting glucose, triacylglycerol, BMI, systolic blood pressure and diastolic blood pressure variants were associated with these traits, with per allele SD effects of 0.057 (95% CI 0.041, 0.074), p=3.44 × 10(-12), 0.130 (95% CI 0.105, 0.155), p=2.9 × 10(-21), 0.04 (95% CI 0.014, 0.072), p=0.004, 0.031 (95% CI 0.016, 0.047), p=7.9 × 10(-5), 0.028 (95% CI 0.015, 0.042), p = 5.5 × 10(-5), respectively. These effects are consistent with those observed in Europeans, except that the effect of triacylglycerol variants in South Asians was slightly lower. Mendelian randomisation provided evidence that genetically influenced, raised triacylglycerol levels do not causally affect type 2 diabetes risk to the extent predicted from observational data (p=0.0003 for difference between observed and instrumental variables correlations). CONCLUSIONS/INTERPRETATION: Genetic variants identified in Europeans are associated with type 2 diabetes-related traits in Pakistanis, with comparable effect sizes. Larger studies are needed to perform adequately powered Mendelian randomisation and help dissect the relationships between type 2 diabetes-related traits in diverse South Asian subgroups.

Swine as reservoirs of zoonotic borderline oxacillin-resistant Staphylococcus aureus ST398.

Methicillin resistance mediated by the mecA gene in Staphylococcus aureus, also known as "true MRSA", is typically associated with high oxacillin MIC values (≥8 mg/L). Because non-mecA-mediated oxacillin resistant S. aureus phenotypes can also cause hard-to-treat diseases in humans, their misidentification as methicillin-susceptible S. aureus strains (MSSA) can compromise the efficiency of the antimicrobial therapy. These strains have been refereed as Borderline Oxacillin-Resistant S. aureus (BORSA) but their characterization and role in clinical microbiology have been neglected. Considering the increasing importance of livestock-associated methicillin-resistant S. aureus ST398 (LA-MRSA) as an emerging zoonotic pathogen worldwide, this study aimed to report the genomic context of oxacillin resistance in porcine S. aureus ST398 strains. S. aureus isolates were recovered from asymptomatic pigs from three herds. Oxacillin MIC values ranged from 4 to 32 mg/L. MALDI-TOF-confirmed isolates were screened for mecA and mecC by PCR and genotyped by means of PFGE and Rep-PCR. Seven isolates were whole genome sequenced. None of the isolates harbored the mecA gene or its variants. Although all seven sequenced isolates belonged to one sequence type (ST398), two different spa types (t571 and t1471) were identified. All isolates harbored conserved blaZ gene operon and no mutations on genes encoding for penicillin-binding-proteins were detected. Genes conferring resistance against other drugs such as aminoglycosides, chloramphenicol, macrolide, lincosamide and streptogramin (MLS), tetracycline and trimethoprim were also detected. Isolates also harbored virulence genes encoding for adhesins (icaA; icaB; icaC; icaD; icaR), toxins (hlgA; hlgB; hlgC; luk-PV) and protease (aur). Pigs can serve as reservoirs of non-mecA-mediated oxacillin-resistant ST398 strains potentially pathogenic to humans. Considering that mecA has been the main target to screen methicillin-resistant staphylococci, the occurrence of BORSA phenotypes is probably underestimated in livestock.

Isolation and basic characterization of a beta-glucosidase from a strain of Lactobacillus brevis isolated from a malolactic starter culture.

AIMS: To study glycosidase activities of a Lactobacillus brevis strain and to isolate an intracellular beta-glucosidase from this strain. METHODS AND RESULTS: Lactic acid bacteria (LAB) isolated from a commercially available starter culture preparation for malolactic fermentation were tested for beta-glycosidase activities. A strain of Lact. brevis showing high intracellular beta-D-glucosidase, beta-D-xylosidase and alpha-L-arabinosidase activities was selected for purification and characterization of its beta-glucosidase. The pure glucosidase from Lact. brevis has also side activities of xylosidase, arabinosidase and cellobiosidase. It is a homotetramer of 330 kDa and has an isoelectric point at pH 3.5. The K(m) for p-nitrophenyl-beta-D-glucopyranoside and p-nitrophenyl-beta-D-xylopyranoside is 0.22 and 1.14 mmol l(-1), respectively. The beta-glucosidase activity was strongly inhibited by gluconic acid delta-lactone, partially by glucose and gluconate, but not by fructose. Ethanol and methanol were found to increase the activity up to twofold. The free enzyme was stable at pH 7.0 (t(1/2) = 50 day) but not at pH 4.0 (t(1/2) = 4 days). CONCLUSIONS: The beta-glucosidase from Lact. brevis is widely different to that characterized from Lactobacillus casei (Coulon et al. 1998) and Lactobacillus plantarum (Sestelo et al. 2004). The high tolerance to fructose and ethanol, the low inhibitory effect of glucose on the enzyme activity and the good long-term stability could be of great interest for the release of aroma compounds during winemaking. SIGNIFICANCE AND IMPACT OF THE STUDY: Although the release of aroma compounds by LAB has been demonstrated by several authors, little information exists on the responsible enzymes. This study contains the first characterization of an intracellular beta-glucosidase isolated from a wine-related strain of Lact. brevis.

Mechanisms of transport of H+, Na+ and K+, across the distal gastric caecum of larval Aedes aegypti.

Measured changes in ion fluxes, transepithelial potential (TEP) and basolateral membrane potential (Vb) in response to ion transporter inhibitors were used to assess the mechanisms of transport of H+, Na+ and K+, across the distal gastric caecum of larval Aedes aegypti, a vector of yellow fever. Preparations were stimulated with 5-hydroxytryptamine (5-HT, 10-6 M) in order to maintain stable rates of H+, Na+, and K+ transport across the distal caecum. Transepithelial potential (TEP), basolateral membrane potential (Vb), and H+, Na+ and K+ fluxes all declined after the addition of a vacuolar-type H+-ATPase (VA) inhibitor, n-ethlymaleimide (NEM), consistent with a primary role for VA in energizing ion transport across the distal gastric caecum. Amiloride also inhibited H+, Na+, and K+ fluxes, consistent with an apically expressed VA that is coupled to a cation:H+ antiporter (AeNHE8), analogous to the coupling of apical VA and cation:nH+ antiporter in Malpighian tubules. A working model of transport of H+, Na+ and K+ across the distal gastric caecum proposes that coupling of VA and AeNHE8 in the apical membrane leads to the removal of intracellular Na+ or K+, thus creating favourable ion gradients to promote the activity of two transporters in the basal membrane, cation:H+ antiporter (AeNHE3) and a bumetanide-sensitive cation chloride cotransporter (CCC).

Investigation of mutations associated with pyrethroid resistance in populations of the New World Screwworm fly, Cochliomyia hominivorax (Diptera: Calliphoridae).

Cochliomyia hominivorax larvae are known for their parasitic habit in living vertebrates, causing considerable economic losses to livestock industry. This ectoparasite has been controlled mainly by applying insecticides, but this method usually results in the selection of resistant individuals. The resistance mechanism known as knockdown resistance (kdr) is a generic term for amino acid substitutions in the sodium channel associated with pyrethroid resistance, and substitutions in residue 251 of the carboxylesterase E3 have been associated with organophosphate and pyrethroid hydrolysis. We looked for L1014F kdr and W251S mutations in the sodium channel and E3 genes, respectively, in C. hominivorax populations. Ten populations obtained from its current distribution were investigated using the polymerase chain reaction-restriction fragment length polymorphism technique. No mutant individuals were found for the kdr mutation. However, the W251S mutation was found in all populations investigated. Results from a bioassay with cypermethrin (a pyrethroid) indicated that the survival at the lowest concentration (Fisher exact test, P = 0.0003) and an intermediate concentration (P = 0.024) were associated with the W251S mutation. This correlation was not significant at the highest concentration tested (P = 0.221). We suggest that the W251S mutation in the C. hominivorax carboxylesterase E3 is also associated with pyrethroid hydrolysis. This information may contribute to the elaboration of improved management programs for this ectoparasite.

Immunolocalization and pathological alterations following Strongyloides venezuelensis infection in the lungs and the intestine of MHC class I or II deficient mice.

The present study, investigated the mechanisms involved in the immune responses of Major Histocompatibility Complex class I or class II knockout mice, following Strongyloides venezuelensis infection. Wild-type C57BL/6 (WT), MHC II(-/-) and MHC I(-/-) mice were individually inoculated with 3000 larvae (L3) of S. venezuelensis and sacrificed on days 1, 3, 5, 8, 13 and 21 post-infection (p.i.). Samples of blood, lungs and small intestines were collected. The tissue samples were stained with hematoxylin-eosin for the pathological analysis. The presence of the parasite was demonstrated by immunoperoxidase analysis. MHC II(-/-) mice presented a significantly higher number of adult worms recovered from the small intestine on day 5p.i. and presented elevated numbers of eggs in the feces. The infection by S. venezuelensis was completely eliminated 13 days after infection in WT as well as in MHC I(-/-) mice. In MHC II(-/-) mice, eggs and adult worms were still found on day 21 p.i., however, there was a significant reduction in their numbers. In the lung, the parasite was observed in MHC I(-/-) on day 1 p.i. and in MHC II(-/-) mice on days 1 and 5 p.i. In the small intestine of WT mice, a larger number of parasites were observed on day 8 p.i. and their absence was observed after day 13 p.i. Through immunohistochemistry analysis, the parasite was detected in the duodenum of WT on days 5 and 8 p.i., and in knockout mice on days 5, 8 and 13 p.i.; as well as in posterior portions of the small intestine in MHC I(-/-) and MHC II(-/-) on day 13 p.i., a finding which was not observed in WT mice. We concluded that immunohistochemistry analysis contributed to a more adequate understanding of the parasite localization in immunodeficient hosts and that the findings aid in the interpretation of immunopathogenesis in Strongyloides infection.

Analysis of the landscape complexity and heterogeneity of the Pantanal wetland.

This is the first report on analysis of habitat complexity and heterogeneity of the Pantanal wetland. The Pantanal encompasses a peculiar mosaic of environments, being important to evaluate and monitor this area concerning conservation of biodiversity. Our objective was to indirectly measure the habitat complexity and heterogeneity of the mosaic forming the sub-regions of the Pantanal, by means of remote sensing. We obtained free images of Normalized Difference Vegetation Index (NDVI) from the sensor MODIS and calculated the mean value (complexity) and standard deviation (heterogeneity) for each sub-region in the years 2000, 2008 and 2015. The sub-regions of Poconé, Canoeira, Paraguai and Aquidauana presented the highest values of complexity (mean NDVI), between 0.69 and 0.64 in the evaluated years. The highest horizontal heterogeneity (NDVI standard deviation) was observed in the sub-region of Tuiuiú, with values of 0.19 in the years 2000 and 2015, and 0.21 in the year 2008. We concluded that the use of NDVI to estimate landscape parameters is an efficient tool for assessment and monitoring of the complexity and heterogeneity of the Pantanal habitats, applicable in other regions.

Free-floating adult human brain-derived slice cultures as a model to study the neuronal impact of Alzheimer's disease-associated Aß oligomers.

BACKGROUND: Slice cultures have been prepared from several organs. With respect to the brain, advantages of slice cultures over dissociated cell cultures include maintenance of the cytoarchitecture and neuronal connectivity. Slice cultures from adult human brain have been reported and constitute a promising method to study neurological diseases. Despite this potential, few studies have characterized in detail cell survival and function along time in short-term, free-floating cultures. NEW METHOD: We used tissue from adult human brain cortex from patients undergoing temporal lobectomy to prepare 200 µm-thick slices. Along the period in culture, we evaluated neuronal survival, histological modifications, and neurotransmitter release. The toxicity of Alzheimer's-associated Aß oligomers (AßOs) to cultured slices was also analyzed. RESULTS: Neurons in human brain slices remain viable and neurochemically active for at least four days in vitro, which allowed detection of binding of AßOs. We further found that slices exposed to AßOs presented elevated levels of hyperphosphorylated Tau, a hallmark of Alzheimer's disease. COMPARISON WITH EXISTING METHOD(S): Although slice cultures from adult human brain have been previously prepared, this is the first report to analyze cell viability and neuronal activity in short-term free-floating cultures as a function of days in vitro. CONCLUSIONS: Once surgical tissue is available, the current protocol is easy to perform and produces functional slices from adult human brain. These slice cultures may represent a preferred model for translational studies of neurodegenerative disorders when long term culturing in not required, as in investigations on AßO neurotoxicity.

Hepatitis A virus in environmental water samples from the Amazon Basin.

Hepatitis A virus (HAV) is a significant waterborne human pathogen. Of the global supply of potable water, Brazil retains 13%, of which 75% resides in the Amazon Basin. Although hepatitis A morbidity has declined progressively in Brazil as a whole, it remains high in the Amazon region. We used nested and real-time reverse-transcription polymerase chain reaction (RT-PCR) to detect and quantify the viral load in water samples from the Amazon Basin. Most samples tested positive (92%), with viral loads varying from 60 to 5500 copies /L, depending on sanitary conditions and the degree of flooding. Nested RT-PCR of the VP1-2A region detected HAV RNA in 23% of the samples. In low viral load samples, HAV was detected only with real-time RT-PCR, suggesting that this technique is useful for monitoring HAV contamination. The presence of HAV in water samples constitutes a serious public health problem.

BeWo trophoblasts are unable to control replication of Toxoplasma gondii, even in the presence of exogenous IFN-gamma.

The ability of RH strain of Toxoplasma gondii to invade and grow into BeWo cells was investigated in the present study using IFN-gamma, l-tryptophan, or alpha-methyl-tryptophan treatments. HeLa cells were used in the same conditions for comparison purposes. It was demonstrated that BeWo cells are more permissive to T. gondii infection, making them more susceptible to this pathogen when compared to HeLa cells. Infection rates of BeWo cells do not show any significant alteration in different protocols using IFN-gamma. In addition, BeWo treated with l-tryptophan was unable to significantly increase parasite growth. In contrast, HeLa cells treated with IFN-gamma or IFN-gamma plus l-tryptophan are able to impair or increase, respectively, parasite replication, providing evidence that this indoleamine-2,3-dioxygenase-dependent phenomenon is operant in these cells, whereas it is inactive in BeWo. Therefore, our data support the hypothesis that the immunological mechanisms controlling infection at the maternal-fetal interface are different from those occurring in the periphery. At the same time that operating regulatory mechanisms work inside and outside the cells located at that microenvironment to prevent maternal rejection of the concept, these events might facilitate the progression of infection caused by intracellular pathogens, as T. gondii.

Clostridium perfringens infection of pancreatic necrosis: absolute indication for early surgical intervention.

It is generally accepted that the surgical treatment of pancreatic necrosis should be delayed as long as possible and after there is laboratory confirmation of infection, determined by image guided fine-needle aspiration. Two cases of severe necrotizing pancreatitis are presented where gas developed in the pancreatic bed, detected by CT scanning, within 2--4 days of the onset of symptoms. Bacteriology studies showed clostridium perfringens and other gram negative flora. The presence of retroperitoneal gas in this context is an absolute indication for early surgical intervention.

Effect of suramin on myotoxicity of some crotalid snake venoms.

We investigated the protective effect of suramin, an enzyme inhibitor and an uncoupler of G protein from receptors, on the myotoxic activity in mice of different crotalid snake venoms (A.c. laticinctus, C.v. viridis, C.d. terrificus, B. jararacussu, B. moojeni, B. alternatus, B. jararaca, L. muta). Myotoxicity was evaluated in vivo by injecting im the venoms (0.5 or 1.0 mg/kg) dissolved in physiological saline solution (0.1 ml) and measuring plasma creatine kinase (CK) activity. Two experimental approaches were used in mice (N = 5 for each group). In protocol A, 1 mg of each venom was incubated with 1.0 mg suramin (15 min, 37 degrees C, in vitro), and then injected im into the mice at a dose of 1.0 mg/kg (in vivo). In protocol B, venoms, 1.0 mg/kg, were injected im 15 min prior to suramin (1.0 mg/kg, iv). Before and 2 h after the im injection blood was collected by orbital puncture. Plasma was separated and stored at 4 degrees C for determination of CK activity using a diagnostic kit from Sigma. Preincubation of some venoms (C.v. viridis, A.c. laticinctus, C.d. terrificus and B. jararacussu) with suramin reduced (37-76%) the increase in plasma CK, except for B. alternatus, B. jararaca or L. muta venoms. Injection of suramin after the venom partially protected (34-51%) against the myotoxicity of B. jararacussu, A.c. laticinctus and C.d. terrificus venom, and did not protect against C.v. viridis, L. muta, B. moojeni, B. alternatus or B. jararaca venoms. These results show that suramin has an antimyotoxic effect against some, but not all the North and South American crotalid snake venoms studied here.