Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 94
Filtrar
Mais filtros











Intervalo de ano de publicação
1.
J. Venom. Anim. Toxins incl. Trop. Dis. ; 17(1): 23-33, 2011. graf, ilus
Artigo em Inglês | VETINDEX | ID: vti-4436

RESUMO

Gyroxin, a thrombin-like enzyme isolated from Crotalus durissus terrificus venom and capable of converting fibrinogen into fibrin, presents coagulant and neurotoxic activities. The aim of the present study was to evaluate such coagulant and toxic properties. Gyroxin was isolated using only two chromatographic steps - namely gel filtration (Sephadex G-75) and affinity (Benzamidine Sepharose 6B) - resulting in a sample of high purity, as evaluated by RP-HPLC C2/C18 and electrophoretic analysis that showed a molecular mass of 30 kDa. Gyroxin hydrolyzed specific chromogenic substrates, which caused it to be classified as a serine proteinase and thrombin-like enzyme. It was stable from pH 5.5 to 8.5 and inhibited by Mn²+, Cu²+, PMSF and benzamidine. Human plasma coagulation was more efficient at pH 6.0. An in vivo toxicity test showed that only behavioral alterations occurred, with no barrel rotation. Gyroxin was not able to block neuromuscular contraction in vitro, which suggests that its action, at the studied concentrations, has no effect on the peripheral nervous system.(AU)


Assuntos
Animais , Crotalus cascavella/classificação , Animais Peçonhentos , Peptídeo Hidrolases
2.
J. venom. anim. toxins incl. trop. dis ; J. venom. anim. toxins incl. trop. dis;17(1): 23-33, 2011. graf
Artigo em Inglês | LILACS | ID: lil-576879

RESUMO

Gyroxin, a thrombin-like enzyme isolated from Crotalus durissus terrificus venom and capable of converting fibrinogen into fibrin, presents coagulant and neurotoxic activities. The aim of the present study was to evaluate such coagulant and toxic properties. Gyroxin was isolated using only two chromatographic steps - namely gel filtration (Sephadex G-75) and affinity (Benzamidine Sepharose 6B) - resulting in a sample of high purity, as evaluated by RP-HPLC C2/C18 and electrophoretic analysis that showed a molecular mass of 30 kDa. Gyroxin hydrolyzed specific chromogenic substrates, which caused it to be classified as a serine proteinase and thrombin-like enzyme. It was stable from pH 5.5 to 8.5 and inhibited by Mn²+, Cu²+, PMSF and benzamidine. Human plasma coagulation was more efficient at pH 6.0. An in vivo toxicity test showed that only behavioral alterations occurred, with no barrel rotation. Gyroxin was not able to block neuromuscular contraction in vitro, which suggests that its action, at the studied concentrations, has no effect on the peripheral nervous system.


Assuntos
Animais , Ratos , Venenos de Crotalídeos , Trombina/isolamento & purificação , Trombina/toxicidade
3.
Toxicon ; 56(8): 1477-86, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20837041

RESUMO

The aim of this work was to evaluate the hematological changes induced by Tityus serrulatus venom (TsV). Blood of Wistar rats was collected 0.5, 2, 6 and 24 h after i.p. injection of TsV (0.5 mg/kg) or saline (controls). Two additional groups were injected with 0.67 mg/kg and 0.25 mg/kg of TsV and the blood was collected after 0.5 and 2 h, respectively. The results showed an increase on hematocrit (Ht), red blood cells (RBC) count, hemoglobin concentration (Hb), albumin and total protein, mainly 2-6 h after envenoming. Increase in serum activities of amylase, creatine kinase and aspartate aminotransferase were also observed, indicating tecidual damages. Hyperglycemia was observed at all times analyzed, as a consequence of catecholamine release. No significant changes were detected in the urea, [Na(+)] and [Ca(2+)], but an increase of [Mg(2+)], [K(+)] and conductivity was observed. TsV induced a reduction of erythrocytes osmotic fragility as consequence of dehydration and increase in plasma electrolytes concentration, as evidenced by its higher conductivity. This study demonstrated that TsV is able to induce severe hematological changes, that appear within the first hours after envenoming, justifying the seeking of medical attention as soon as possible to avoid worsening of clinical symptoms.


Assuntos
Venenos de Escorpião/toxicidade , Escorpiões/química , Albuminas/metabolismo , Animais , Sangue/efeitos dos fármacos , Proteínas Sanguíneas/metabolismo , Contagem de Eritrócitos , Hematócrito , Hemoglobinas/metabolismo , Pressão Osmótica , Ratos , Ratos Wistar , Fatores de Tempo , Testes de Toxicidade
4.
Phytother Res ; 22(6): 784-90, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18389489

RESUMO

Casearia sylvestris Sw., popularly known in Brazil as 'guaçatonga', has been used as antitumor, antiseptic, antiulcer, local anaesthetic and healer in folk medicine. Snakebite envenomation by Bothrops jararacussu (Bjssu) constitutes a relevant public health hazard capable of inducing serious local damage in victims. This study examined the pharmacological action of apolar and polar C. sylvestris leaf extracts in reverting the neuromuscular blockade and myonecrosis, which is induced by Bjssu venom and its major toxin bothropstoxin-I on the mouse phrenic nerve-diaphragm preparations. The polar methanol extract (ME) was by far the most efficacious. ME not only prevented myonecrosis and abolished the blockade, but also increased ACh release. Such facilitation in neuromuscular transmission was observed with ME alone, but was accentuated in preparations incubated with ME plus venom or toxin. This established synergy opens an interesting point of investigation because the venom or toxin in contact with ME changes from a blocking to a facilitating effect. It is suggested that rutin, known to have potent antioxidant properties, and one of the components present in the ME, could have a role in the observed effects. Since commercial rutin did not reproduce the ME effects, it is likely that a rutin-containing phytocomplex is neutralizing the bothropic envenoming effects.


Assuntos
Casearia/química , Contração Muscular/efeitos dos fármacos , Extratos Vegetais/farmacologia , Animais , Brasil , Cromatografia Líquida de Alta Pressão , Cromatografia em Camada Fina , Diafragma/efeitos dos fármacos , Diafragma/inervação , Diafragma/fisiologia , Técnicas In Vitro , Masculino , Metanol/química , Camundongos , Junção Neuromuscular/efeitos dos fármacos , Junção Neuromuscular/fisiologia , Extratos Vegetais/química
5.
J. venom. anim. toxins incl. trop. dis ; J. venom. anim. toxins incl. trop. dis;13(1): 103-121, 2007. graf, tab
Artigo em Inglês | LILACS | ID: lil-444615

RESUMO

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 (æBondapak 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 10æg/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 percent (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 percent homology with bothropstoxin-II and 54 percent homology with caudoxin) and that of NeuTX-II was SLFEFAKMILEETKRLPFPYYGAYGCYCGWGGQGQPKDAT (92 percent homology with Basp-III and 62 percent 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.


Assuntos
Animais , Bothrops/metabolismo , Venenos de Crotalídeos , Fosfolipases A/química , Neurotoxinas/intoxicação
6.
Biochim Biophys Acta ; 1760(9): 1450-7, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16828972

RESUMO

Phospholipases A(2) are components of Bothrops venoms responsible for disruption of cell membrane integrity via hydrolysis of its phospholipids. This study used a large nonimmune human scFv library named Griffin.1 (MRC, Cambridge, UK) for selection of recombinant antibodies against antigens present in Bothrops jararacussu venom and identification of specific antibodies able to inhibit phospholipase activity. Four clones were identified as capable of inhibiting this activity in vitro. These clones were able to reduce in vivo the myotoxic activity of BthTX-I and BthTX-II PLA(2), but had no effect on the in vitro anticoagulant activity of BthTX-II. This work shows the potential of using recombinant scFv libraries in the search for antibodies that neutralize relevant venom components.


Assuntos
Anticorpos/imunologia , Anticorpos/metabolismo , Bothrops/metabolismo , Venenos de Crotalídeos/enzimologia , Venenos de Crotalídeos/toxicidade , Coração/efeitos dos fármacos , Fosfolipases A/toxicidade , Animais , Anticorpos/genética , Anticorpos/isolamento & purificação , Coagulação Sanguínea/imunologia , Venenos de Crotalídeos/imunologia , Ensaio de Imunoadsorção Enzimática , Expressão Gênica , Fosfolipases A2 do Grupo II , Humanos , Cinética , Camundongos , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/imunologia , Fragmentos de Peptídeos/isolamento & purificação , Fragmentos de Peptídeos/metabolismo , Fosfolipases A/imunologia , Fosfolipases A/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Proteínas de Répteis , Solubilidade
7.
Phytomedicine ; 12(1-2): 123-30, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15693719

RESUMO

Partial neutralization of the myotoxic effect of Bothrops jararacussu venom (BV) and two of its myotoxins [bothropstoxin-I (BthTX-I), catalytically inactive, and II (BthTX-II), showing low PLA2 activity], by the lyophilized aqueous extract of Tabernaemontana catharinensis (AE), was studied in rat isolated soleus muscle preparations (in vitro) and through i.m. injection in the gastrocnemius muscle (in vivo) by determination of creatine kinase (CK) activity and histopathological analysis. Incubation of soleus muscle for 1 h with BV or toxins (20 microg/ml) plus AE (400 microg/ml) added immediately after BV, BthTX-I or BthTX-II reduced CK levels by 53%, 37% and 56%, respectively. The myonecrotic effects of BV (20 microg/ml) upon soleus muscle was reduced 24%, 35% and 36% when AE (400 microg/ml) was added 1 h after BV and CK was evaluated 30 min, 1 and 2 h later, respectively. For BthTX-I these values were 46%, 48% and 47%, while for BthTX-II no inhibitory effect was detected. Histological analysis of soleus muscle after incubation with AE (400 microg/ml, 1 h) did not reveal any change in muscle fibers, but severe necrosis induced by BV or toxins (20 microg/ml) was clearly in evidence, and decreased significantly when soleus muscle was protected by AE. This protection was also observed when AE was administered 1 h after BV or BthTX-I, but not after BthTX-II. AE did not inhibit the catalytic PLA2 activity of BthTX-II or BV and did not change the PAGE pattern of BV, BthTX-I or BthTX-II. In vivo assays were performed in 100-g rats and maximal CK release was attained at a dose of 100 microg of BV, 3 h after injection. AE was not effective when injected 20 s after BV or toxins. However, injecting BV or toxins (100 microg), which were pre-incubated with AE (2 mg) caused an inhibition of 57%, 59% and 51%, respectively, with zero time pre-incubation, but was less effective with 1 h pre-incubation. This plant represents a potential source of promising myotoxin inhibitors.


Assuntos
Antivenenos/farmacologia , Bothrops , Venenos de Crotalídeos/antagonistas & inibidores , Fitoterapia , Extratos Vegetais/farmacologia , Tabernaemontana , Animais , Antivenenos/administração & dosagem , Antivenenos/uso terapêutico , Creatina Quinase/metabolismo , Venenos de Crotalídeos/química , Venenos de Crotalídeos/toxicidade , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/enzimologia , Extratos Vegetais/administração & dosagem , Extratos Vegetais/uso terapêutico , Raízes de Plantas , Ratos , Ratos Wistar
8.
Comp Biochem Physiol C Toxicol Pharmacol ; 138(4): 429-36, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15536050

RESUMO

Myonecrosis, in addition to edema and other biological manifestations, are conspicuous effects of Bothrops snake venoms, some of them caused by phospholipases A(2) (PLA(2)s). Asp49-PLA(2)s are catalytically active, whereas Lys49-PLA(2)s, although highly toxic, have little or no enzymatic activity upon artificial substrates, due to a substitution of lysine for aspartic acid at position 49. Crotapotin (CA), the acidic counterpart of crotoxin PLA(2) (CB), is a PLA(2)-like protein from Crotalus durissus terrificus snake venom, and is considered a chaperone protein for CB, able to increase its lethality about ten fold, but to inhibit the formation of the rat paw edema induced by carrageenin and by snake venoms. In this study, we demonstrate that CA significantly inhibits the edema induced by BthTX-I (23% inhibition), BthTX-II (27%), PrTX-I (25%), PrTX-III (35%) and MjTX-II (10%) on the mouse paw. CK levels evoked by isolated Asp49 or Lys49-PLA(2)s were reduced by 40% to 54% in the presence of CA and, in all cases, the membrane damaging activity of the toxins was also reduced. Circular dichroism spectra of the PLA(2)s in the presence and absence of CA showed that there was not any detectable secondary structural modification due to association between CA and the myotoxins. However, Fourier Transformed Infrared (FT-IR) analysis indicated that ionic and hydrophobic contacts contributed to stabilize this interaction.


Assuntos
Bothrops , Venenos de Crotalídeos/enzimologia , Crotoxina/toxicidade , Inibidores Enzimáticos/toxicidade , Músculo Esquelético/efeitos dos fármacos , Fosfolipases A/antagonistas & inibidores , Animais , Dicroísmo Circular/métodos , Creatina Quinase/metabolismo , Crotoxina/análise , Relação Dose-Resposta a Droga , Edema/induzido quimicamente , Edema/patologia , Inibidores Enzimáticos/análise , Membro Posterior , Masculino , Camundongos , Músculo Esquelético/enzimologia , Músculo Esquelético/patologia , Fosfolipases A/análise , Fosfolipases A/classificação , Isoformas de Proteínas , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
9.
Artigo em Inglês | VETINDEX | ID: vti-442983

RESUMO

This paper describes a brief study on the crotoxin mechanism of action, regarding the transport of GABA and L-glutamate in rats cortico-cerebral synaptosomes and in heterologous systems, such as COS-7 cells expressing gabaergic transporters, and C6 glioma cells and Xenopus oocytes expressing glutamatergic transporters. Crotoxin concentrations over 1 µM caused an inhibitory effect of ³H-L-glutamate and ³H-GABA, and reversibly inhibited L-glutamate uptake by C6 glioma cells. When COS-7 cells were assayed, no inhibition of the ³H-GABA transport could be evidenced. Crotoxin kept its inhibitory effect on neurotransmitters uptake even when Ca2+ ions were removed from the medium, therefore, independently of its PLA2 activity. In addition, high concentrations (2 mM) of BPB did not avoid the action of crotoxin on the neurotransmitters uptake. Crotoxin also inhibited ³H-L-glutamate, independently on Na+ channel blockade by TTX. In addition, an evaluation of the lactic dehydrogenase activity indicated that uptake inhibition does not involve a hydrolytic action of crotoxin upon the membrane. We may also suggest that crotoxin acts, at least partially, altering the electrogenic equilibrium, as evidenced by confocal microscopy, when a fluorescent probe was used to verify cell permeability on C6 glioma cells in presence of crotoxin.

10.
J. venom. anim. toxins incl. trop. dis ; J. venom. anim. toxins incl. trop. dis;10(3): 260-279, 2004. graf
Artigo em Inglês | LILACS | ID: lil-383136

RESUMO

This paper describes a brief study on the crotoxin mechanism of action, regarding the transport of GABA and L-glutamate in rats cortico-cerebral synaptosomes and in heterologous systems, such as COS-7 cells expressing gabaergic transporters, and C6 glioma cells and Xenopus oocytes expressing glutamatergic transporters. Crotoxin concentrations over 1 µM caused an inhibitory effect of ³H-L-glutamate and ³H-GABA, and reversibly inhibited L-glutamate uptake by C6 glioma cells. When COS-7 cells were assayed, no inhibition of the ³H-GABA transport could be evidenced. Crotoxin kept its inhibitory effect on neurotransmitters uptake even when Ca2+ ions were removed from the medium, therefore, independently of its PLA2 activity. In addition, high concentrations (2 mM) of BPB did not avoid the action of crotoxin on the neurotransmitters uptake. Crotoxin also inhibited ³H-L-glutamate, independently on Na+ channel blockade by TTX. In addition, an evaluation of the lactic dehydrogenase activity indicated that uptake inhibition does not involve a hydrolytic action of crotoxin upon the membrane. We may also suggest that crotoxin acts, at least partially, altering the electrogenic equilibrium, as evidenced by confocal microscopy, when a fluorescent probe was used to verify cell permeability on C6 glioma cells in presence of crotoxin.


Assuntos
Animais , Masculino , Ratos , GABAérgicos , Crotoxina , Glutamatos , Neurotoxinas , Venenos de Crotalídeos/farmacologia , Sistema Nervoso
11.
Biochimie ; 85(10): 983-91, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14644553

RESUMO

Acidic phospholipase A(2) (PLA(2)) isoforms in snake venoms, particularly those from Bothrops jararacussu, have not been characterized. This article reports the isolation and partial biochemical, functional and structural characterization of four acidic PLA(2)s (designated SIIISPIIA, SIIISPIIB, SIIISPIIIA and SIIISPIIIB) from this venom. The single chain purified proteins contained 122 amino acid residues and seven disulfide bonds with approximate molecular masses of 15 kDa and isoelectric points of 5.3. The respective N-terminal sequences were: SIIISPIIA-SLWQFGKMIDYVMGEEGAKS; SIIISPIIB-SLWQFGKMIFYTGKNEPVLS; SIIISPIIIA-SLWQFGKMILYVMGGEGVKQ and SIIISPIIIB-SLWQFGKMIFYEMTGEGVL. Crystals of the acidic protein SIIISPIIB diffracted beyond 1.8 A resolution. These crystals are monoclinic with unit cell dimensions of a = 40.1 A, b = 54.2 A and c = 90.7 A. The crystal structure has been refined to a crystallographic residual of 16.1% (R(free) = 22.9%). Specific catalytic activity (U/mg) of the isolated acidic PLA(2)s were SIIISPIIA = 290.3 U/mg; SIIISPIIB = 279.0 U/mg; SIIISPIIIA = 270.7 U/mg and SIIISPIIIB = 96.5 U/mg. Although their myotoxic activity was low, SIIISPIIA, SIIISPIIB and SIIISPIIIA showed significant anticoagulant activity. However, there was no indirect hemolytic activity. SIIISPIIIB revealed no anticoagulant, but presented indirect hemolytic activity. With the exception of SIIISPIIB, which inhibited platelet aggregation, all the others were capable of inducing time-independent edema. Chemical modification with 4-bromophenacyl bromide did not inhibit the induction of edema, but did suppress other activities.


Assuntos
Bothrops , Venenos de Crotalídeos/enzimologia , Fosfolipases A/química , Sequência de Aminoácidos , Animais , Creatina Quinase/metabolismo , Venenos de Crotalídeos/química , Venenos de Crotalídeos/toxicidade , Cristalografia por Raios X , Edema/induzido quimicamente , Técnicas In Vitro , Isoenzimas/química , Isoenzimas/isolamento & purificação , Isoenzimas/farmacologia , Camundongos , Modelos Moleculares , Dados de Sequência Molecular , Músculos/efeitos dos fármacos , Fosfolipases A/isolamento & purificação , Fosfolipases A/farmacologia , Fosfolipases A/toxicidade , Fosfolipases A2 , Inibidores da Agregação Plaquetária/química , Inibidores da Agregação Plaquetária/isolamento & purificação , Inibidores da Agregação Plaquetária/farmacologia , Conformação Proteica
12.
Protein Pept Lett ; 10(5): 525-30, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14561144

RESUMO

Lys49-Phospholipase A2 (Lys49-PLA(2) - EC 3.1.1.4) homologues damage membranes by a Ca2+-independent mechanism which does not involve catalytic activity. Both MjTX-II from Bothrops moojeni and BthTX-I from Bothrops jararacussu are dimeric in solution and in the crystalline states, and a model for the Ca2+-independent membrane damaging mechanism has been suggested in which flexibility at the dimer interface region permits quaternary structural transitions between "open" and "closed" membrane bound dimer conformations which results in the perturbation of membrane phospholipids and disruption of the bilayer structure. With the aim of gaining insights into the structural determinants involved in protein/lipid association, we report here the crystallization and preliminary X-ray analysis of the (i) MjTX-II/SDS complex at a resolution of 2.78A, (ii) MjTX-II/STE complex at a resolution of 1.8 A and (iii) BthTX-I/DMPC complex at 2.72A. These complexes were crystallized by the hanging drop vapour-diffusion technique in (i) HEPES buffer (pH 7.5) 1.8M ammonium sulfate with 2% (w/v) polyethyleneglycol 400, in (ii) 0.6-0.8 M sodium citrate as the precipitant (pH 6.0-6.5) and in (iii) sodium citrate buffer (pH 5.8) and PEG 4000 and 20% isopropanol, respectively. Single crystals of these complexes have been obtained and X-ray diffraction data have been collected at room temperature using a R-AXIS IV imaging plate system and graphite monochromated Cu Kalpha X-ray radiation generated by a Rigaku RU300 rotating anode generator for (i) and (iii) and using using a Synchrotron Radiation Source (Laboratório Nacional de Luz Sincrotron, LNLS, Campinas, Brazil) for (ii).


Assuntos
Venenos de Crotalídeos/química , Fosfolipases A/química , Animais , Cristalização , Dimiristoilfosfatidilcolina/química , Fosfolipases A2 , Dodecilsulfato de Sódio/química , Ácidos Esteáricos/química , Difração de Raios X/estatística & dados numéricos
13.
Biochimie ; 85(7): 669-75, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-14505822

RESUMO

The aqueous extract from the leaves of Casearia mariquitensis (C. m.), a plant found in Brazilian open pastures, was assayed for its ability to inhibit some hematological and hemostatic effects induced by neuwiedase, a 22 kDa class P-I metalloproteinase from the venom of the South American pit viper Bothrops neuwiedi pauloensis. The aqueous extract from C. m. was able to neutralize the hematological alterations induced by the crude venom (C.V.) upon erythrocytes when the venom was incubated at a ratio of 1:10 (w/w, venom/extract), but it did not neutralize the platelet decreasing ability of C.V. The plasma fibrinogen concentration decreased approximately 36% and 83% when 0.6 LD(50) of the C.V. or neuwiedase, respectively, were injected by i.p. route in mice, and the aqueous extract from C. m. was able to inhibit this effect. The Bbeta fibrinogen chain was protected against degradation caused by crude venom and neuwiedase when the venom or toxin were incubated with C. m. extract. We also observed that this extract exerted a very slight effect on the clotting time, prolonging it only to a little extent. The pulmonary hemorrhage induced by neuwiedase when injected intravenously with 0.6 LD(50) was completely inhibited when this toxin was incubated with the extract at a ratio of 1:10 (w/w, toxin/extract). It is concluded that C. m. displays components able to inhibit some hematological and systemic alterations induced by C.V.


Assuntos
Casearia/química , Inibidores Enzimáticos/farmacologia , Metaloendopeptidases/antagonistas & inibidores , Venenos de Víboras/antagonistas & inibidores , Animais , Coagulação Sanguínea/efeitos dos fármacos , Plaquetas/efeitos dos fármacos , Bothrops , Venenos de Crotalídeos/antagonistas & inibidores , Venenos de Crotalídeos/enzimologia , Eritrócitos/efeitos dos fármacos , Fibrinogênio/análise , Fibrinogênio/metabolismo , Fibrinólise/efeitos dos fármacos , Hematócrito , Metaloproteases/antagonistas & inibidores , Metaloproteases/metabolismo , Camundongos , Extratos Vegetais/farmacologia , Venenos de Víboras/enzimologia
14.
J. venom. anim. toxins ; 8(2): 226-243, 2002. ilus, graf
Artigo em Inglês | LILACS | ID: lil-314695

RESUMO

Bothrops jararacussu venom and its major toxin bothropstoxin-I (BthTX-I) possess myotoxic and neurotoxic properties. The efficacy of a rabbit antivenom raised against B. jararacussu venom in the neutralization of physiological, biochemical, and morphological changes induced by the venom and its major toxin BthTX-I was studied in mouse isolated phrenic nerve-diaphragm (PND) and extensor digitorum longus (EDL) preparations. The times required for 50 per cent neuromuscular blockade in PND and EDL preparations for venom were 70ñ11.5 (S.E.M., n=5) min and 58ñ8 (n=16) (50 µ/mL), and for BthTX-I 31ñ6 (n=3) min and 30ñ3 (n=5) min (20 µg/mL), respectively. After 120 min incubation, creatine kinase (CK) concentrations in solution containing the EDL preparations were 3464ñ346 U/L after exposure to venom (50 µg/mL, n=5) and 3422ñ135 U/L to BthTX-I (20µg/mL, n=4), respectively. Rabbit antivenom dose-dependently neutralized venom and toxin-induced neuromuscular blockade in both preparations and effectively prevented venom and toxin-induced CK release from EDL. Histological analysis showed that rabbit antivenom neutralized morphological damage caused by B.jararacussu venom and BthTX-I in EDL preparations. these results indicate that rabbit antivenom effectively neutralized the biological activities of B.jararacussu venom and BthTX-I.


Assuntos
Animais , Masculino , Coelhos , Ratos , Antitoxinas , Antivenenos , Venenos de Crotalídeos , Coelhos , Bothrops
15.
J. venom. anim. toxins ; 8(1): 88-101, 2002. ilus, tab, graf
Artigo em Inglês | LILACS | ID: lil-303724

RESUMO

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 per cent to 100 per cent after 120 min incubation with venoms (50µg/ml). In all cases, this blockade was irreversible and concentration-dependent; at low concentrations (10-20 µg/ml), 15 of the 16 venom lots failed to abolish responses to acetylcholine (110µM), but blocked responses to KCI (13.4mM), and induced contracture. At 5-20µg/ml, the most active venom totally blocked twitch-tension without affecting responses to acetylcholine and KCI. Polyacrylamine 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. ineuwiedii venoms, whereas myotoxic activity is less variable.


Assuntos
Animais , Masculino , Bothrops , Brasil , Galinhas , Miotonia , Sistema Nervoso , Neurotoxinas , Venenos de Crotalídeos/efeitos adversos , Venenos de Crotalídeos/toxicidade , Acetilcolina , Contratura , Bloqueio Neuromuscular
16.
Biochem Pharmacol ; 62(11): 1521-9, 2001 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-11728388

RESUMO

Anti-bothropic complex (ABC) was isolated from the serum of the South American opossum (Didelphis albiventris) by single-step affinity chromatography using a Sepharose-immobilized metalloprotease (BaP1) from Bothrops asper as the binding protein. Biochemical characterization of ABC showed the presence of two glycosylated subunits of 43 and 45 kDa, respectively, with an isoelectric point < 4. The two subunits were separated by ion-exchange HPLC. The N-terminal sequences of both subunits (LKAMDPTPXLWIETESP, where X is Arg-9 and Pro-9, respectively) showed a high degree of identity with other serum inhibitors isolated from different marsupials. Functional studies pointed out that ABC inhibits the hemorrhagic and proteolytic activities on fibrin, fibrinogen, and casein induced by the metalloproteases BaP1 and BaH4 isolated from B. asper venom. In addition to the anti-hemorrhagic and anti-proteolytic activities, ABC also showed anti-myotoxic, anti-lethal, and anti-edematogenic effects against myotoxic phospholipases A(2) isolated from the same venom. Moreover, it had inhibitory effects on the phospholipase A(2) activity of the crude venom as well as the isolated venom phospholipases A(2).


Assuntos
Proteínas Sanguíneas/farmacologia , Proteínas de Transporte/farmacologia , Venenos de Crotalídeos/antagonistas & inibidores , Metaloendopeptidases/antagonistas & inibidores , Neurotoxinas/antagonistas & inibidores , Gambás/sangue , Fosfolipases A/antagonistas & inibidores , Aminoácidos/química , Animais , Proteínas Sanguíneas/química , Proteínas Sanguíneas/isolamento & purificação , Bothrops , Proteínas de Transporte/química , Proteínas de Transporte/isolamento & purificação , Venenos de Crotalídeos/química , Venenos de Crotalídeos/enzimologia , Fosfolipases A2 do Grupo II , Hemorragia/prevenção & controle , Proteínas de Répteis , Análise de Sequência de Proteína
17.
J Protein Chem ; 20(5): 377-82, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11732689

RESUMO

Bothropstoxin-I (BthTX-I), a Lys49 phospholipase A2 homolog with no apparent catalytic activity, was first isolated from Bothropsjararacussu snake venom and completely sequenced in this laboratory. It is a 121-amino-acid single polypeptide chain, highly myonecrotic, despite its inability to catalyze hydrolysis of egg yolk phospholipids, and has 14 half-cystine residues identified at positions 27, 29. 44. 45, 50, 51, 61, 84, 91, 96, 98, 105, 123, and 131 (numbering according to the conventional alignment including gaps, so that the last residue is Cys 131). In order to access its seven disulfide bridges, two strategies were followed: (1) Sequencing of isolated peptides from (tryptic + SV8) and chymotryptic digests by Edman-dansyl degradation; (2) crystallization of the protein and determination of the crystal structure so that at least two additional disulfide bridges could be identified in the final electron density map. Identification of the disulfide-containing peptides from the enzymatic digests was achieved following the disappearance of the original peptides from the HPLC profile after reduction and carboxymethylation of the digest. Following this procedure, four bridges were initially identified from the tryptic and SV8 digests: Cys5O-Cysl31, Cys51-Cys98, Cys61-Cys91, and Cys84-Cys96. From the chymotryptic digest other peptides were isolated either containing some of the above bridges, therefore confirming the results from the tryptic digest, or presenting a new bond between Cys27 and Cys123. The two remaining bridges were identified as Cys29-Cys45 and Cys44-Cys105 by determination of the crystal structure, showing that BthTX-I disulfide bonds follow the normal pattern of group II PLA2s.


Assuntos
Bothrops , Venenos de Crotalídeos/química , Neurotoxinas/química , Fosfolipases A/química , Sequência de Aminoácidos , Animais , Venenos de Crotalídeos/genética , Dissulfetos , Fosfolipases A2 do Grupo II , Modelos Moleculares , Dados de Sequência Molecular , Fosfolipases A2 , Conformação Proteica , Proteínas de Répteis
18.
Toxicon ; 39(12): 1863-9, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11600149

RESUMO

Aqueous extract from Casearia sylvestris leaves, a typical plant from Brazilian open pastures, was able to neutralize the hemorrhagic activity caused by Bothrops asper, Bothrops jararacussu, Bothrops moojeni, Bothrops neuwiedi and Bothrops pirajai venoms. It also neutralized two hemorrhagic metalloproteinases from Bothrops asper venom. Proteolytic activity on casein induced by bothropic venoms and by isolated proteases, including Bn2 metalloproteinase from B. neuwiedi venom, was also inhibited by the C. sylvestris extract in different levels. The alpha-fibrinogen chain was partially protected against degradation caused by B. jararacussu venom, when this venom was incubated with C. sylvestris extract. We also observed that this extract partially increased the time of plasma coagulation caused by B. jararacussu, B. moojeni and B. neuwiedi venoms. C. sylvestris extract did not induce proteolysis in any substrate assayed.


Assuntos
Bothrops/fisiologia , Venenos de Crotalídeos/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Metaloendopeptidases/antagonistas & inibidores , Extratos Vegetais/farmacologia , Animais , Caseínas/metabolismo , Venenos de Crotalídeos/enzimologia , Fibrinogênio/metabolismo , Fibrinólise/efeitos dos fármacos , Hemorragia/patologia , Hemorragia/prevenção & controle , Metaloendopeptidases/metabolismo , Dermatopatias/patologia , Dermatopatias/prevenção & controle
19.
Toxicon ; 39(10): 1495-504, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11478957

RESUMO

The purification procedure of a hyaluronidase from Tityus serrulatus scorpion venom is described. It involves basically an ion-exchange chromatography on CM-cellulose at pH 7.8 followed by a rechromatography of the active fraction on the same column at pH 4.7. The optima pH and temperature for maximum activity of the isolated enzyme was 6.0 and 40 degrees C, respectively. Its K(M) was 69.7 microg/ml at 37 degrees C and its specific activity was 19,900+/-1,730 turbidity reducing units (TRU)/mg against 845+/-88TRU/mg for the whole desiccated venom, representing a 23- to 24-fold purification range. The hyaluronidase activity of the purified protein (51kDa) was inhibited by some flavonoid compounds. This article also showed that T. serrulatus hyaluronidase affected on the activity of the venom's major toxin, tityustoxin-I (TsTX-I or Ts1), as reflected by alterations in the serum levels of creatine kinase (CK), lactate dehydrogenase (LD) and aspartate aminotransferase (AST) following injection of TsTX-I, in the presence or absence of hyaluronidase.


Assuntos
Hialuronoglucosaminidase/isolamento & purificação , Neurotoxinas/toxicidade , Venenos de Escorpião/toxicidade , Adjuvantes Imunológicos/metabolismo , Animais , Aspartato Aminotransferases/sangue , Cromatografia por Troca Iônica , Creatina Quinase/sangue , Eletroforese em Gel de Poliacrilamida , Flavonoides/metabolismo , Temperatura Alta , Ácido Hialurônico/metabolismo , Hialuronoglucosaminidase/análise , Hialuronoglucosaminidase/antagonistas & inibidores , Hialuronoglucosaminidase/metabolismo , Concentração de Íons de Hidrogênio , Proteínas de Insetos , Cinética , L-Lactato Desidrogenase/sangue , Masculino , Peso Molecular , Ratos , Ratos Wistar , Venenos de Escorpião/química , Escorpiões , Sesquiterpenos/metabolismo , Relação Estrutura-Atividade
20.
Toxicon ; 39(10): 1477-85, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11478955

RESUMO

Bothropstoxin-I (BthTX-I), the principal myotoxin of Bothrops jararacussu venom, is devoid of phospholipase A(2) (PLA(2)) activity but capable of blocking neuromuscular transmission in mouse nerve-muscle preparations. In this study, the ability of crotoxin antiserum and heparin in preventing the neurotoxic and myotoxic effects of BthTX-I was investigated. Phrenic nerve-diaphragm preparations (PND) stimulated indirectly with supramaximal stimuli (0.2 ms, 0.1 Hz) were incubated with BthTX-I (20 microg/ml) alone or with BthTX-I preincubated with antiserum or heparin for 30 min at 37 degrees C prior to testing. Control preparations were incubated with Tyrode solution, antiserum or heparin alone. BthTX-I (20 microg/ml) produced 50% neuromuscular blockade in the PND preparations in 31+/-4min, with complete blockade occurring in 120 min. The antiserum and heparin significantly prevented the neuromuscular blockade caused by BthTX-I (84 +/- 4% and 100% protection, respectively). Light microscopy examination of the muscles at the end of the 120 min incubation showed that BthTX-I damaged 48 +/- 6% of the fibers. Preincubating the toxin with antivenom significantly reduced the extent of this damage (only 15 +/- 4% of fibers affected, corresponding to 69% protection, P<0.01) whereas heparin offered no protection (34 +/- 7% of fibers affected, not significantly different from that seen with toxin alone). These results show that the antivenom was more effective in neutralizing the myotoxic effects of BthTX-I than was heparin.


Assuntos
Antivenenos/farmacologia , Venenos de Crotalídeos/antagonistas & inibidores , Crotoxina/antagonistas & inibidores , Imunoglobulina G/análise , Músculo Esquelético/efeitos dos fármacos , Nervo Frênico/efeitos dos fármacos , Animais , Antivenenos/imunologia , Antivenenos/uso terapêutico , Bothrops , Venenos de Crotalídeos/imunologia , Venenos de Crotalídeos/toxicidade , Crotoxina/imunologia , Crotoxina/toxicidade , Estimulação Elétrica , Eletroforese em Gel de Poliacrilamida , Heparina/uso terapêutico , Imunoglobulina G/sangue , Imunoglobulina G/isolamento & purificação , Técnicas In Vitro , Injeções Subcutâneas , Masculino , Camundongos , Músculo Esquelético/patologia , Músculo Esquelético/fisiologia , Bloqueio Neuromuscular , Junção Neuromuscular/efeitos dos fármacos , Junção Neuromuscular/patologia , Junção Neuromuscular/fisiologia , Testes de Neutralização , Nervo Frênico/fisiologia , Coelhos , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA