Bothrops atrox venom: Biochemical properties and cellular phenotypes of three highly toxic classes of toxins

Snake venoms have a complex mixture of compounds that are conserved across species and act synergistically, triggering severe local and systemic effects. Identification of the toxin classes that are most damaging to cell homeostasis would be a powerful approach to focus on the main activities that underpin envenomation. Here, we focus on the venom of Bothrops atrox, snake responsible for most of the accidents in Amazon region of South America. We identified the key cytotoxic toxin fractions from B. atrox venom and mapped their biochemical properties, protein composition and cell damage. Five fractions were obtained by mass exclusion chromatography and contained either a single class of enzymatic activity (i.e., L-amino acid oxidases or Hyaluronidases) or different activities co-distributed in two or more protein fractions (e.g., Metalloproteinases, Serine Proteases, or Phospholipases A2). Only three protein fractions reduced cell viability of primary human cells. Strikingly, such activity is accompanied by disruption of cell attachment to substratum and to neighbouring cells. Such strong perturbation of morphological cell features indicates likely defects in tissue integrity in vivo. Mass spectrometry identified the main classes of toxins that contribute to these phenotypes. We provide here a strategy for the selection of key cytotoxic proteins for targeted investigation of their mechanism of action and potential synergism during snakebite envenomation. Our data highlights putative toxins (or combinations of) that may be the focus of future therapeutic interference.

Proteomic and toxinological characterization of Peruvian pitviper Bothrops brazili ("jergón shushupe"), venom

Bothrops brazili is a pitviper from Amazonian region, responsible for many accidents in Peru. Despite its relevance, its venom has not been extensively characterized. In the present work, Bothrops brazili venom (BbV) components were analyzed by RP-HPLC, SDS-PAGE and MALDI-TOF/TOF. Approximately 37 proteins were identified, belonging to 7 families. Snake venom metalloproteinases (SVMPs) were the most abundant proteins of the venom (33.05%), followed by snake venom serine proteinases (SVSPs, 26.11%), phospholipases A₂ (PLA₂, 25.57%), snake C-type lectins (CTLs, 9.61%), L-aminoacid oxidase (LAAO, 3.80%), cystein-rich secretory proteins (CRISP, 1.67%) and Bradykinin-potentiating peptide (BPP, 0.20%). In vitro enzymatic activities of BbV showed high levels of SVMP activity and reduced Hyal activity in comparison with other bothropic venoms. Furthermore, BbV reduced VERO cells viability. ELISA and Western Blotting showed that both Peruvian and Brazilian bothropic antivenoms were able to recognize BbV components. This work provides an overview of BbV venom content and indicates a potential efficiency of Peruvian and Brazilian antivenoms to treat accidents with this species.

Regional diastolic function in normotensive versus hypertensive subjects: comparison using Doppler myocardial imaging

BACKGROUND

Pulsed Doppler myocardial imaging (DMI) is a new technique that makes it possible to obtain an on-line quantitative assessment of wall motion in different myocardial segments through sample-volume placement. Therefore, this tool is suitable for identifying changes in regional diastolic function in uncomplicated arterial hypertension. In this study, we examined standard Doppler-derived indexes of global left ventricular diastolic function and regional diastolic parameters obtained by pulse-wave DMI in a population of hypertensive patients, comparing them with the indexes found in a control group of normotensive subjects.

METHODS

Thirty-six patients with uncomplicated hypertension and 10 normotensive subjects (all males) underwent a complete Doppler echocardiographic examination and a pulsed DMI assessment of 4 different myocardial segments: basal and middle septum, basal and middle lateral wall.

RESULTS

The 2 groups were comparable in age and heart rate, but body mass index, systolic and diastolic blood pressure and left ventricular mass index were higher in hypertensives. All of the transmitral diastolic measurements were impaired in hypertensives, without any difference in the Doppler indexes of global systolic function. While there were no changes in the regional systolic measurements, most of the DMI parameters for diastolic function changed significantly in all 4 of the segments examined, with a greater statistical difference at the basal and middle septum. We found a relationship between the number of segments involved in the diastolic dysfunction (ie with peak velocity E/A < 1) and the degree of impairment of the transmitral E/A ratio solely in the hypertensive population.

CONCLUSIONS

DMI is a useful tool for distinguishing left ventricular diastolic function in hypertensive patients and it provides information about the extent and degree of diastolic impairment in different myocardial segments. The basal and middle septum present more evident diastolic alterations. Minor but significant changes can be identified at the basal and middle lateral walls. The higher the prevalence of the myocardial segments involved in diastolic dysfunction, the greater the impairment of the global diastolic function of the left ventricle will be.