Biomedical subjects

C A Vieira

Publications and source records attributed to C A Vieira.

10 recordsLinked to original sources

PubMed2003

Renal artery aneurysm in hand-assisted laparoscopic donor nephrectomy: case report.

We report a living donor who underwent laparoscopic nephrectomy using a hand-assisted device (HALD). At preoperative arteriography the donor showed a renal artery aneurysm. The patient was a 37-year-old female, 166 cm height, white, weighing 87 kg, HLA identical to the recipient. HALD was indicated due to the better visualization of renal pedicle and greater security in an obese patient. Renal artery aneurysm is a rare condition, with many possible complications. The method proved to be adequate and safe for donor nephrectomy, despite a renal artery aneurysm.

Aneurysm↗

PubMed1998

Amino acid sequence of piratoxin-I, a myotoxin from Bothrops pirajai snake venom, and its biological activity after alkylation with p-bromophenacyl bromide.

The complete sequence of the 121 amino acid residues of piratoxin-I (PrTX-I), a phospholipase A2 (PLA2)-like myotoxin from Bothrops pirajai snake (Bahia jararacussu) venom, is reported. From the sequence, an M, of 13,825 and an approximate pI of 8.3 were calculated. PrTX-I shows a high sequence homology with Lys-49 myotoxins from other bothropic (approximately 95%) and nonbothropic (approximately 80%) venoms, but only 70-75% homology when aligned with the catalytically active Asp-49 PLA2s. When compared with bothropstoxin-I from Bothropsjararacussu, which is morphologically almost identical to B. pirajai, only two changes out of 121 total amino acid residues have been observed. The approximate minimal lethal dose LD50 (mice, i.p., 24 hr) of PrTX-I was 8 (6.8-9.1) mg/kg, and the minimal edematogenic dose (MED) in a rat paw model was 39.5+/-1.8 ug. After alkylation of His-48 with p-bromophenacyl bromide, the MED was 40.1+/-1.9 ug, but up to 4 LD50 were unable to cause death in any of a group of eight mice after 72 hr. Therefore the edematogenic activity was retained and apparently did not involve His-48, suggesting that at least two biologically active sites are present in PrTX-I.

Acetophenones↗

PubMed1997

The histamine releasers crotamine, protamine and compound 48/80 activate specific proteases and phospholipases A2.

Crotamine, a basic, myonecrotic, histamine-releasing neurotoxin, was isolated from Crotalus durissus terrificus venom. Carboxypeptidase A was shown to be activated by crotamine when acting upon N-carbobenzoxyglycil-L-phenylalanine. However the activity of carboxypeptidase B upon the substrate hippuryl-L-arginine was not enhanced by this toxin. Teh basic histamine releasers protamine and compound 48/80 also activated carboxypeptidase A. These three agents activated both alpha-chymotrypsin when acting upon acetyl-L-tyrosine ethyl ester and also five snake venom phospholipase-like myotoxins acting upon egg yolk phosphatidylcholine. These findings suggest that the action of these agents during histamine release may involve the participation of specific intermediary hydrolases which, upon activation, would enhance their cytolytic effects on the sequence of events which lead to granule extrusion and histamine release from mast cells.

Carboxypeptidases↗

PubMed1995

Fractionation of Bothrops pirajai snake venom: isolation and characterization of piratoxin-I, a new myotoxic protein.

Whole desiccated venom of Bothrops pirajai was fractionated on a gel filtration (Sephadex G-75) column. Phospholipase A2, arginine esterase and clotting activity profiles of the six fractions (SI to SVI) obtained were determined. Fraction SIV from the gel filtration column was subjected to chromatography on SP-Sephadex C-25. It was resolved into five subfractions (SIV-SP1, to SIV-SP5). Fractions SIV-SP1, SIV-SP2 and SIV-SP3 showed phospholipase A2 activity but, among these fractions, only SIV-SP3 was homogeneous. Induction of myonecrosis by SIV-SP3, SIV-SP4 and SIV-SP5 was demonstrated by their ability to release serum creatine kinase, and for SIV-SP5, to induce histological alterations in the injected mouse muscle. Chemical characterization by determination of mol. wts, isoelectric focusing and direct manual sequencing of the N-terminal region was performed for SIV-SP3, SIV-SP4 and SIV-SP5. When compared with bothropstoxin-I, the myotoxin SIV-SP5 showed the same total number of amino acid residues (121) and constant molar ratio for all but three amino acids. We have named this toxin piratoxin-I (PrTX-I).

Amino Acid Sequence↗

PubMed1994

Isolation and characterization of TsTX-V, a new neurotoxin from Tityus serrulatus scorpion venom which delays the inactivation of Na+ channels.

TsTX-V, a new neurotoxin from Tityus serrulatus scorpion venom able to induce a prolongation of the inactivation of Na+ channels, has been purified to homogeneity. The venom was chromatographed on CM-cellulose-52 and 13 fractions were first collected. A subsequent stepwise elution chromatography of fraction XI afforded, among other toxins, highly purified TsTX-V, which showed a single band by PAGE, SDS-PAGE or isoelectric focusing, a distinctive amino acid composition, mol. wt. = 7230, pI = 8.0 and i.v. LD50 = 94 +/- 7 micrograms/kg in mice. TsTX-V induced a long lasting hypertension in anesthetized rats and prolonged the action potential of the B fibers of the rabbit vagus nerve at 0.03 microgram/ml. At 0.3 microgram/ml and higher concentrations it caused also a nerve depolarization. These effects on nerve membranes were irreversible and could be suppressed by tetrodotoxin (200-500 nM). Nerve fibers depolarized by high extracellular K+(15-30mM) concentrations still displayed long duration action potentials after TsTX-V treatment. It is suggested that TsTX-V blocks the Na+ channel inactivation system probably as an alpha-toxin.

Action Potentials↗

PubMed1993

Biochemical characterization of a vascular smooth muscle contracting polypeptide purified from Phoneutria nigriventer (armed spider) venom.

Biochemical characterization of a vascular smooth muscle contracting polypeptide purified from Phoneutria nigriventer (armed spider) venom. Toxicon 31, 377-384, 1993. Crude Phoneutria nigriventer venom was fractionated by Sephadex, ion-exchange and reverse-phase high performance liquid chromatography. One protein (PNV1) with spasmogenic activity in rabbit vascular smooth muscle was isolated and biochemically characterized. PNV1 has 125 amino acid residues and a calculated mol. wt of 13,899. Special features of the amino acid composition of PNV1 are the presence of two disulfide bridges and the high percentage (27%) of Asx and Glx. The N-terminal amino acid sequence indicates that PNV1 is different from other polypeptides isolated from Phoneutria nigriventer venom.

Amino Acid Sequence↗

PubMed1992

What is tityustoxin?

Tityus serrulatus scorpion venom was fractionated by gel filtration affording two heterogeneous toxic fractions, T1 and T2; the latter was further fractionated by ion-exchange chromatography. The fraction of T2 eluted with 0.15 M ammonium acetate buffer, originally named 'tityustoxin', was shown to be a pool of several proteins. One of them, TsTX, as well as T1, was also named 'tityustoxin'. The major and perhaps most potent toxin of the venom, gamma-toxin, was eluted with 0.30 M buffer as a highly purified protein and shown to be different from TsTX. gamma-Toxin is contained in both T1 and T2.

Chromatography, Gel↗

PubMed1990

Primary structure and biological activity of bradykinin potentiating peptides from Bothrops insularis snake venom.

Several bradykinin potentiating peptides (BPPs) were isolated from the venom of the Brazilian arboricole snake Bothrops insularis by gel filtration on Sephadex G-150-120, followed by sequencial high-voltage paper electrophoreses at pH 3.5, 6.5, and 2.1. The BPPs were assayed by their ability to potentiate the contractile activity, on the isolated guinea pig ileum, and the hypotensive activity, on anesthetized rats, of bradykinin. Eight BPPs, containing 3-13 amino acid residues, were sequenced and their primary structures were shown to have a marked degree of homology with those of several BPPs from other venoms.

Amino Acid Sequence↗

PubMed1990

Interchain disulfide bonds in crotamine self-association.

Crotamine, a basic neurotoxic protein, was isolated from the venom of the Southern Brazilian rattlesnake (Crotalus durissus terrificus) by gel filtration. The isolated protein showed a single band on PAGE at pH 4.5 and 7% (w/v) gel concentration, but two or more bands at 14% gel concentration, even in the presence of 4 M urea. After reduction and carboxymethylation, however, a single band was again detected. SDS-PAGE as well as ultracentrifugal analysis of the native (NC) and of the reduced and carboxymethylated (RCC) crotamine revealed a molecular weight of 4,500-5,000 for RCC and 9,000-10,000 for NC. Both components of a two-band crotamine preparation were isolated by preparative PAGE and characterized. Their particular electrophoretic mobility was retained. Their amino acid composition. N-terminal residue, and apparent toxicity were the same as those of the original sample. It was concluded that crotamine is able to form a dimer of 9,760 Da with two identical polypeptide chains crosslinked by interchain disulfide bonds and a shape not very far from spherical, which covalently binds extra subunits of 4,880 Da each.

Animals↗

PubMed1980

[An experience in training health personnel in Brazil].

This paper analyses the experience of the Strategic Health Personnel Training Program (PPREPS) in Brazil during 1976-1978. It describes the Program's general characteristics, objectives, and strategies, operational methods, and results. The article also evaluates information regarding the health-related human resource development process and its political and social context. Finally, several perspectives are considered for its continuity in the future.

Allied Health Personnel↗