Suppression of cardiomyocyte functions by ß-CTX isolated from the Thai king cobra (Ophiophagus hannah) venom via an alternative method

Beta-cardiotoxin (ß-CTX), the three-finger toxin isolated from king cobra (Ophiophagus hannah) venom, possesses ß-blocker activity as indicated by its negative chronotropy and its binding property to both ß-1 and ß-2 adrenergic receptors and has been proposed as a novel ß-blocker candidate. Previously, ß-CTX was isolated and purified by FPLC. Here, we present an alternative method to purify this toxin. In addition, we tested its cytotoxicity against different mammalian muscle cell types and determined the impact on cardiac function in isolated cardiac myocyte so as to provide insights into the pharmacological action of this protein. Methods: ß-CTX was isolated from the crude venom of the Thai king cobra using reverse-phased and cation exchange HPLC. In vitro cellular viability MTT assays were performed on mouse myoblast (C2C12), rat smooth muscle (A7r5), and rat cardiac myoblast (H9c2) cells. Cell shortening and calcium transient dynamics were recorded on isolated rat cardiac myocytes over a range of ß-CTX concentration. Results: Purified ß-CTX was recovered from crude venom (0.53% w/w). MTT assays revealed 50% cytotoxicity on A7r5 cells at 9.41 ± 1.14 µM (n = 3), but no cytotoxicity on C2C12 and H9c2 cells up to 114.09 µM. ß-CTX suppressed the extend of rat cardiac cell shortening in a dose-dependent manner; the half-maximal inhibition concentration was 95.97 ± 50.10 nM (n = 3). In addition, the rates of cell shortening and re-lengthening were decreased in ß-CTX treated myocytes concomitant with a prolongation of the intracellular calcium transient decay, indicating depression of cardiac contractility secondary to altered cardiac calcium homeostasis. Conclusion: We present an alternative purification method for ß-CTX from king cobra venom. We reveal cytotoxicity towards smooth muscle and depression of cardiac contractility by this protein. These data are useful to aid future development of pharmacological agents derived from ß-CTX.(AU)

Pseudotumor hemofílico. Reporte de caso / Hemophiliac Pseudotumor. Case report

Teniendo en cuenta la baja prevalencia del pseudotumor hemofílico en pacientes con hemofilia, consideramos de interés presentar los hallazgos en un niño de 13 años con uno localizado en la mandíbula. Caso clínico Se trata de un niño de 13 años de edad, con el antecedente de hemofilia tipo B, que consulta por una masa submandibular bilateral de crecimiento progresivo en 9 meses de evolución, dolorosa, la cual presentó ruptura espontánea con abundante sangrado y descompensación hemodinámica que requirió manejo en la unidad de cuidado intensivo y embolización de la arteria facial derecha. En el examen físico se observan masas submandibulares bilaterales, la del lado derecho con ulceración de fondo sanguinolento.

Hemolitic action of Naja naja atra cardiotoxin on erythrocytes from different animals

A comparative study on the sensitivity of erythrocytes from different vertebrate species (avian, mammalian and reptilian) to the hemolytic action caused by cardiotoxin isolated from Naja naja atra venom was carried out. Cardiotoxin was able to induce direct hemolysis in washed erythrocytes from several animals, except for llama. The EC50 values from hemolysis of the most sensitive (cat) and the most resistant (snake) animal varied approximately tenfold. According to the cell behavior, it was possible to characterize four types of behavior: The first was observed in cat, horse and human cells; the second in rat, rabbit and dog erythrocytes; and the third only in llama erythrocytes, which were resistant to cardiotoxin concentrations up to 300 æg/ml. Finally, avian and reptilian erythrocytes were more resistant to cardiotoxin III-induced hemolysis than those of the mammalian species.

Actividad hemolítica de venenos de serpientes de los géneros Bothrops, Lachesis, Crotalus y Micrurus (Serpentes: Viperidae y Elapidae) / Haemolytic activity of venoms from snakes of the genera Bothrop, Lachesis, Crotalus and Micrurus (Serpentes: Viperidae and Elapidae)

Hemolytic activity of eight Peruvian snake venoms from the families Viperidae and Elapidae (Bothrops atrox, B. pictus, B. hyoprorus, B. bilineatus, B. neuwedii, Lachesis m. muta, Crotalus d. terrificus, Microrus tschudi), and three Brazilian viperids (B. jararacussu, B. alternatus and C. d. collilineatus) is described. None of the venoms cause direct lysis on washed human erythrocytes. However, all of then caused indirect hemolysis provided that the incubation medium contains an exogenous source of lecithin. Venom of Micrurus tschudi was the most hemolytic (HD50 2.8 ug/ml) while that of B. bilineatus was the least (HD50 681.3 ug/ml). Only six of eleven venoms showed parallel curves of hemolytic activity, and the HD50 varied from 198 to 681 ug/ml and the following decreasing order of hemolytic activity was obtained: L. muta, C. d. terrificus, C. d. collilineatus, B. hyoprorus, B. bilineatus, B. alternatus

Actividad microbicida de la ribonucleasa y desoxirribonucleasa en cepas de bacterias patógenas in vitro / Microbicidal activity of ribonuclease and deoxyribonuclease in pathogenic bacterias strains in vitro

Las nucleasas son enzimas que por muchos años se han relacionado exclusivamente con la actividad digestiva. Sin embargo, diversos estudios han demostrado que en condiciones naturales, tienen una función microbicida importante. El presente trabajo se desarrolló con el objetivo de demostrar in vitro la acción germicida de la ribonuclease (RNasa) y la desoxirribonucleasa (DNasa) cuando se aplican exógenamente en algunas cepas patógenas. Surge como una necesidad de analizar la acción directa de las nucleasas sobre ciertos microorganismos, debido a que al aplicarse terapéuticamente en pacientes afectados de procesos infecciosos producidos por estos microorganismos, se ha obtenido el control del padecimiento. En cultivos de cepas puras de Staphylococcus, Proteus vulgaris, proteus mirabilis, Klebsiella pneumoniase, Pseudomonas aeruginosa, Salmonella typhi y Escherichia coli, se aplicaron directamente al medio de cultivo soluciones al 0.1, 1, 10, 25, 50, y 75 por ciento de RNasa (0.00070 mg/mL) y/o DNasa (0.00035 mg/mL). Se valoró la viabilidad y el crecimiento de las colonias bacterianas conservadas en condiciones óptimas de nutrición, temprana, pH y osmolaridad, a las 24, 48, 72 y 192 horas de exposición a estas nucleasas. Se observó que el efecto lítico se manifiesta en la mayor concentración y que las distintas cepas muestran una sensibilidad diferente a las enzimas, ya sea que se apliquen individualmente o en forma simultánea. Se concluye, que las nucleasas tienen actividad antimicrobiana selectiva in vitro, que corrobora el efecto que se ha observado in vivo, en donde además, de demostrar el efecto microbicida selectivo y lisar directamente a los microorganismos, controlan la infección porque destruyen a las células infectadas e inhiben la replicación de los microorganismos que se mantienen en el interior de algunas células.

In vitro cytotoxicity of Rhodnius prolixus hemolytic factor and mellitin towards different trypanosomatids

Trypanosoma cruzi strain Y and clone Dm28c and other trypanosomatids were exposed to two lytic agents, Rhodnius prolixus hemolytic factor (RHF) and mellitin, in vitro. In both cases, the result was a significant decrease in the number of parasites after a 30-min treatment at 37-C. RHF and mellitin had distinct activities on differente strains and species of trypanosomatids. These observations suggest that RHF may be an important factor in selecting resistant strains of trypanosomes for development in the vector's gut