Rattlesnake Crotalus molossus nigrescens venom induces oxidative stress on human erythrocytes

Background Globally, snake envenomation is a well-known cause of death and morbidity. In many cases of snakebite, myonecrosis, dermonecrosis, hemorrhage and neurotoxicity are present. Some of these symptoms may be provoked by the envenomation itself, but others are secondary effects of the produced oxidative stress that enhances the damage produced by the venom toxins. The only oxidative stress effect known in blood is the change in oxidation number of Fe (from ferrous to ferric) in hemoglobin, generating methemoglobin but not in other macromolecules. Currently, the effects of the overproduction of methemoglobin derived from snake venom are not extensively recorded. Therefore, the present study aims to describe the oxidative stress induced by Crotalus molossus nigrescens venom using erythrocytes. Methods Human erythrocytes were washed and incubated with different Crotalus molossus nigrescens venom concentrations (0-640 μg/mL). After 24 h, the hemolytic activity was measured followed by attenuated total reflectance-Fourier transform infrared spectroscopy, non-denaturing PAGE, conjugated diene and thiobarbituric acid reactive substances determination. Results Low concentrations of venom (<10 μg/mL) generates oxyhemoglobin release by hemolysis, whereas higher concentrations produced a hemoglobin shift of valence, producing methemoglobin (>40 μg/mL). This substance is not degraded by proteases present in the venom. By infrared spectroscopy, starting in 80 μg/mL, we observed changes in bands that are associated with protein damage (1660 and 1540 cm−1) and lipid peroxidation (2960, 2920 and 1740 cm−1). Lipid peroxidation was confirmed by conjugated diene and thiobarbituric acid reactive substance determination, in which differences were observed between the control and erythrocytes treated with venom. Conclusions Crotalus molossus nigrescens venom provokes hemolysis and oxidative stress, which induces methemoglobin formation, loss of protein structure and lipid peroxidation.(AU)

Rattlesnake Crotalus molossus nigrescens venom induces oxidative stress on human erythrocytes

Background Globally, snake envenomation is a well-known cause of death and morbidity. In many cases of snakebite, myonecrosis, dermonecrosis, hemorrhage and neurotoxicity are present. Some of these symptoms may be provoked by the envenomation itself, but others are secondary effects of the produced oxidative stress that enhances the damage produced by the venom toxins. The only oxidative stress effect known in blood is the change in oxidation number of Fe (from ferrous to ferric) in hemoglobin, generating methemoglobin but not in other macromolecules. Currently, the effects of the overproduction of methemoglobin derived from snake venom are not extensively recorded. Therefore, the present study aims to describe the oxidative stress induced by Crotalus molossus nigrescens venom using erythrocytes. Methods Human erythrocytes were washed and incubated with different Crotalus molossus nigrescens venom concentrations (0-640 μg/mL). After 24 h, the hemolytic activity was measured followed by attenuated total reflectance-Fourier transform infrared spectroscopy, non-denaturing PAGE, conjugated diene and thiobarbituric acid reactive substances determination. Results Low concentrations of venom (<10 μg/mL) generates oxyhemoglobin release by hemolysis, whereas higher concentrations produced a hemoglobin shift of valence, producing methemoglobin (>40 μg/mL). This substance is not degraded by proteases present in the venom. By infrared spectroscopy, starting in 80 μg/mL, we observed changes in bands that are associated with protein damage (1660 and 1540 cm−1) and lipid peroxidation (2960, 2920 and 1740 cm−1). Lipid peroxidation was confirmed by conjugated diene and thiobarbituric acid reactive substance determination, in which differences were observed between the control and erythrocytes treated with venom. Conclusions Crotalus molossus nigrescens venom provokes hemolysis and oxidative stress, which induces methemoglobin formation, loss of protein structure and lipid peroxidation.(AU)

Rattlesnake Crotalus molossus nigrescens venom induces oxidative stress on human erythrocytes

Abstract Background Globally, snake envenomation is a well-known cause of death and morbidity. In many cases of snakebite, myonecrosis, dermonecrosis, hemorrhage and neurotoxicity are present. Some of these symptoms may be provoked by the envenomation itself, but others are secondary effects of the produced oxidative stress that enhances the damage produced by the venom toxins. The only oxidative stress effect known in blood is the change in oxidation number of Fe (from ferrous to ferric) in hemoglobin, generating methemoglobin but not in other macromolecules. Currently, the effects of the overproduction of methemoglobin derived from snake venom are not extensively recorded. Therefore, the present study aims to describe the oxidative stress induced by Crotalus molossus nigrescens venom using erythrocytes. Methods Human erythrocytes were washed and incubated with different Crotalus molossus nigrescens venom concentrations (0640 g/mL). After 24 h, the hemolytic activity was measured followed by attenuated total reflectance-Fourier transform infrared spectroscopy, non-denaturing PAGE, conjugated diene and thiobarbituric acid reactive substances determination. Results Low concentrations of venom ( 10 g/mL) generates oxyhemoglobin release by hemolysis, whereas higher concentrations produced a hemoglobin shift of valence, producing methemoglobin (>40 g/mL). This substance is not degraded by proteases present in the venom. By infrared spectroscopy, starting in 80 g/mL, we observed changes in bands that are associated with protein damage (1660 and 1540 cm1) and lipid peroxidation (2960, 2920 and 1740 cm1). Lipid peroxidation was confirmed by conjugated diene and thiobarbituric acid reactive substance determination, in which differences were observed between the control and erythrocytes treated with venom. Conclusions Crotalus molossus nigrescens venom provokes hemolysis and oxidative stress, which induces methemoglobin formation, loss of protein structure and lipid peroxidation.

Estudo comparativo de doses de propofol para a indução da anestesia no cão obeso

A indução da anestesia no cão obeso é de grande desafio para o anestesista veterinário, pois estes pacientes apresentam alterações respiratórias e cardiovasculares. Além disso, há carência de protocolos anestésicos na literatura. Desta forma, objetivou-se comparar a indução da anestesia em cães obesos (escore corporal igual ou superior a 8) com propofol empregando-se a dose baseada no peso de massa magra ou baseada no peso total. Trinta e cinco cães foram distribuídos em três grupos: 13 cães de peso normal no grupo controle (GC); 15 cães obesos no grupo peso total (GPT) e sete cães obesos no grupo peso de massa magra (GPMM). Todos os cães foram avaliados com auxílio de escala escore de condição corporal (ECC) de 9 pontos e também tiveram a composição de condição corporal determinada por meio do método de diluição de isótopos de deutério. A anestesia foi induzida com 150 mg/kg/h com auxílio de bomba de infusão de propofol até os animais perderem a consciência. Os animais do GPT receberam a infusão de propofol baseado no peso total; os animais do GPMM receberam infusão de propofol baseado no peso de massa magra; e os cães do GC receberam propofol baseado no peso total. Os parâmetros fisiológicos como frequência cardíaca, pressão arterial sistêmica, saturação de oxi-hemoglobina e presença de apneia foram registrados antes e após a indução. A dose empregada de propofol foi 10,7 ± 2,8mg/kg, 14,1 ± 4,7mg/kg e 7,6 ± 1,5mg/kg nos grupos GC, GPMM e GPT, respectivamente, sendo a diferença significante (p<0,001). Na comparação entre os diferentes momentos dentro de cada grupos, observou-se diferença significativa no GC em relação à PAS, onde os valores obtidos após a indução da anestesia (150,8 ± 32,2mmHg) foram menores do que o basal (180,0 ± 34,8mmHg) (p=0,048). No grupo GPMM observou-se diferença na PAD, sendo que os valores basais (103,6 ± 29,1mmHg) foram mais elevados do que após a indução anestésica (79,3 ± 22,8) (p=0,018). Em relação a oxi-hemoglobina periférica houve diferença significativa entre os valores basais e os obtidos após indução da anestesia em todos os grupos sendo. p=0,027, p=0,006 e p=<0,001, respectivamente nos grupos GC, GPMM e GPT. O presente estudo demonstrou que cães obesos requerem dose menor de propofol (7,6 ± 1,5mg/kg) na indução da anestesia em relação aos cães com peso normal (10,7 ± 2,8mg/kg) ao serem anestesiados com a dose baseada no peso total. Não foi possível demostrar que cães obesos que tiveram a dose calculada baseada apenas no peso de massa magra (14,1 ± 4,7mg/kg) necessitem de doses similares a de cães com peso normal com o calculo baseado no peso total (10,7 ± 2,8mg/kg).

The anesthesia induction of the obese dog poses a great challenge to the veterinary anesthesiologist since these patients present respiratory and cardiovasvular alterations. Besides that, there is little information on anesthetic protocols in the literature. Therefore, the objective was to compare the anesthesia induction in obese dogs (body score condicional equal to or greater than 8) using propofol in dosages based on lean body weight or total body weight. Thirty-five dogs were distributed in three groups: 13 dogs with average weight in the control group (CG); 15 obese dogs in total body weight group (TBWG) and seven obese dogs in lean body weight group (LBWG). All dogs were evaluated according to a body condition score chart (BCS) of 9 points and also had their body composition determined using the deuterium dilution method. Anesthesia was inducted with 150 mg/kg/h through a propofol infusion pump until animals lost consciousness. Animals in TBWG received propofol infusion based on total body weight; the animals in LBWG received propofol infusion based on lean body mass, and the dogs in CG received propofol infusion based on total body weight. Physiological parameters such as heart rate, systemic arterial pressure, oxyhemoglobin saturation and the presence of apnea were recorded previous to and post induction. Propofol dose used was 10.7 ± 2.8mg/kg, 14.1 ± 4.7mg/kg and 7.6 ± 1.5mg/kg in groups CG, LBWG and TBWG, respectively, with a significant difference (p<0.001). Comparing different moments within each group, there was a significant difference in GC related to SAP, where values obtained post induction (150.8 ± 32.2) were smaller than basal (180 ± 34.8) (p=0.048). In LBWG there was a difference in DAP, where basal values (103.6 ± 29.1) were higher than post induction (79.3 ± 22.8) (p=0.018). There were significant differences in peripheral oxyhemoglobin saturation between basal values and post anesthesia induction values in all groups with p=0.027, p=0.006 and p<0.001 in CG, LBWG and TBWG, respectively. The current study shows that obese dogs require smaller propofol doses (7.6 ± 1.5mg/kg) than average weight dogs (10.7 ± 2.8mg/kg) when induction anesthesia based on total body weight dosage. It was not possible to demonstrate that obese dogs with doses based on lean body mass (14.1 ± 4.7mg/kg) have propofol dosage needs similar to average weight dogs with dosage based on total body weight (10.7 ± 2.8mg/kg).