Abstract Ceramic compounds with complex cubic perovskite structures have shown to be promising materials for encapsulations for temperature sensors in the petroleum industry due to their high mechanical resistance and chemical inertness to the corrosive environment of crude oil. In this work, ceramic compounds were produced by solid-state calcination and the X-ray diffraction analysis verified the formation of the compound Sr2NiZrO6 with the ordered complex cubic perovskite structure of the A2BB’O6 type. The sintered Sr2NiZrO6 compound was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and Vickers microhardness. The chemical stability of the compound was verified through the structural, microstructural, and mechanical characterization of the specimens after 60 days of immersion in crude oil. The results showed that the compound did not present changes in the structure and did not suffer a chemical attack on its surface, thus presenting suitable properties for use as encapsulation for temperature sensors in oil wells.

Two presynaptic phospholipases A2 (PLA2), neuwieditoxin-I (NeuTX-I) and neuwieditoxin-II (NeuTX-II), were isolated from the venom of Bothrops neuwiedi pauloensis (BNP). The venom was fractionated using molecular exclusion HPLC (Protein-Pak 300SW column), followed by reverse phase HPLC (µBondapak C18 column). Tricine-SDS-PAGE in the presence or absence of dithiothreitol showed that NeuTX-I and NeuTX-II had a molecular mass of approximately 14 kDa and 28kDa, respectively. At 10µg/ml, both toxins produced complete neuromuscular blockade in indirectly stimulated chick biventer cervicis isolated preparation without inhibiting the response to acetylcholine, but NeuTX-II reduced the response to KCl by 67.0±8.0% (n=3; p<0.05). NeuTX-I and NeuTX-II are probably responsible for the presynaptic neurotoxicity of BNP venom in vitro. In fact, using loose patch clamp technique for mouse phrenic nerve-diaphragm preparation, NeuTX-I produced a calcium-dependent blockade of acetylcholine release and caused appearance of giant miniature end-plate potentials (mepps), indicating a pure presynaptic action. The N-terminal sequence of NeuTX-I was DLVQFGQMILKVAGRSLPKSYGAYGCYCGWGGRGK (71% homology with bothropstoxin-II and 54% homology with caudoxin) and that of NeuTX-II was SLFEFAKMILEETKRLPFPYYGAYGCYCGWGGQGQPKDAT (92% homology with Basp-III and 62% homology with crotoxin PLA2). The fact that NeuTX-I has Q-4 (Gln-4) and both toxins have F-5 (Phe-5) and Y-28 (Tyr-28) strongly suggests that NeuTX-I and NeuTX-II are Asp49 PLA2.

Two fibrinogenolytic enzymes, Bothrops alternatus metalloprotease isoform (BaltMP)-I and II, were purified from Bothrops alternatus venom using Diethylaminoethyl (DEAE) Sephacel, Sephadex G-75 and Heparin-Agarose column chromatography. Purified BaltMP-I and II ran as single protein bands on analytical polyacrylamide gel electrophoresis and showed molecular weights of 29000 and 36000, respectively, under reducing conditions in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). BaltMP-II, but not BaltMP-I, displayed blood-clotting activity in bovine plasma, which was about 10-fold higher than that of the crude venom. Both enzymes were proteolytically active against bovine fibrinogen as substrate. When fibrinogen and each enzyme were incubated at 37°C, at a ratio of 1:100 (w/w), BaltMP-II cleaved preferentially the Aalpha -chain and more slowly the Bbeta -chain. The action of BaltMP-I was similar, but lower. None of the proteases degraded the gamma-chain of fibrinogen. The fibrinogenolytic activity of the enzymes was inhibited by 1,10-phenanthroline, suggesting they are metalloproteases. Since both enzymes were found to cause defibrinogenation when intraperitoneally (i.p.) administered to mice, they can be of medical interest as a therapeutic agent in the treatment and prevention of arterial thrombosis.

This work succinctly describes the professional and scientific life of Dr. José R. Giglio, one of the most outstanding Brazilian researchers in the field of Toxinology. During his long and successful career, he has made major contributions, especially in elucidating the function, structure, and mechanisms of action of animal venom proteins (from snakes, scorpions and spiders) as well as the characterization of antibodies and several inhibitors of venoms and toxins. We present here a brief history of Dr. Giglio’s personal and professional life, also reporting some of his numerous published scientific articles on venoms from snakes (Bothrops, Crotalus, and other genera), scorpions (Tityus sp), spiders (Phoneutria sp), their isolated toxins and natural inhibitors. Thus, this work is a tribute to Dr. Giglio in his 73rd birthday, having devoted 48 years of his life studying animal venoms, an effort that has continued even after his formal retirement from university duties.

Snake venoms frequently vary in composition. In this work, we compared the neurotoxic and myotoxic activities of 16 lots of Bothrops neuwiedii venoms from different regions of Brazil, using chick biventer cervicis preparations. The neuromuscular blockade varied from 2% to 100% after 120 min incubation with venoms (50 mug/ml). In all cases, this blockade was irreversible and concentration-dependent; at low concentrations (10-20 mug/ml), 15 of the 16 venom lots failed to abolish responses to acetylcholine (110 muM), but blocked responses to KCl (13.4 muM), and induced contracture. At 5-20 mug/ml, the most active venom totally blocked twitch-tension without affecting responses to acetylcholine and KCl. Polyacrylamide gel electrophoresis for basic proteins showed that the most active samples contained a band that was absent in the less active venoms. These results indicate that there may be considerable intraspecific variation in the neurotoxic activity of B. neuwiedii venoms, whereas myotoxic activity is less variable.

Polyacrylamide gel electrophoresis (PAGE) for basic proteins may be a useful tool for the characterization of whole snake venoms and for the taxonomic classification of snakes of the Elapidae and Viperidae families. However, due to the close proximity of molecular weights among toxins bearing different net charges, sodium dodecyl sulfate (SDS) - PAGE was not able to provide an efficient differentiation. This article reports the electrophoretic analysis of several venoms from the genera Micrurus, Bothrops, Bothriopsis, Crotalus and Lachesis and shows a typical and distinctive electrophoretic profile for each species, with intraspecific and geographic variations. Even in cases in which extreme morphological similarities were present, such as between B. jararacussu and B. pirajai ("Bahia jararacuçu"), differentiation could be evidenced by PAGE. This simple and sensitive procedure may be applied to similar cases involving basic toxins.