The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform
Pa Zhou - One of the best experts on this subject based on the ideXlab platform.
-
PROPERTIES AND AMINO-ACID-SEQUENCE OF HUWENTOXIN-I, A NEUROTOXIN PURIFIED FROM THE VENOM OF THE CHINESE BIRD SPIDER SELENOCOSMIA-HUWENA
toxicon, 1993Co-Authors: S P Liang, Dy Zhang, Pan X, Chen Q, Pa ZhouAbstract:By means of reverse phase and ion-exchange high performance liquid chromatography, a neurotoxic peptide named huwentoxin-I was purified from the venom of the Chinese bird spider Selenocosmia huwena. The intraperitoneal and intracisternal LD50 in mice of the toxin were 0.70 mg/kg and 9.40 mug/kg, respectively. This toxin at the concentration of 1 x 10(-5) g/ml can irreversibly block the neuromuscular transmission of the isolated mouse Phrenic Nerve-Diaphragm Preparation in 13.4 +/- 1.3 min (mean +/- S.D., n = 5). The isoelectric point is 8.95 determined by isoelectric focusing electrophoresis. It consists of 33 amino acids including 6 Cys and 6 Lys determined by amino acid analysis. The complete amino sequence of huwentoxin-I was determined. The N-terminal and C-terminal residues were Ala and Leu, respectively. The primary structure showed partial homology with that of mu-agatoxins from the funnel-web spider Agelenopsis aperta.Pharmacology & PharmacyToxicologySCI(E)63ARTICLE8969-9783
S P Liang - One of the best experts on this subject based on the ideXlab platform.
-
purification and characterization of huwentoxin ii a neurotoxic peptide from the venom of the chinese bird spider selenocosmia huwena
Journal of Peptide Research, 1999Co-Authors: Qin Shu, S P LiangAbstract:A neurotoxic peptide, huwentoxin-II (HWTX-II), was purified from the venom of the Chinese bird spider Selenocosmia huwena by ion exchange chromatography and reversed phase HPLC. The toxin can reversibly paralyse cockroaches for several hours, with an ED50 of 127 +/- 54 microg/g. HWTX-II blocks neuromuscular transmission in an isolated mouse Phrenic nerve diaphragm Preparation and acts cooperatively to potentiate the activity of huwentoxin-I. The complete amino sequence of HWTX-II was determined and found to consist of 37 amino acid residues, including six Cys residues. There is microheterogeneity (Ile/Gln) in position 10, and mass spectrometry indicated that the two isoproteins have a tendency to dimerize. It was determined by mass spectrometry that the six Cys residues are involved in three disulphide bonds. The sequence of HWTX-II is highly homologous with ESTX, a toxin from the tarantula Eurypefina californicum.
-
PROPERTIES AND AMINO-ACID-SEQUENCE OF HUWENTOXIN-I, A NEUROTOXIN PURIFIED FROM THE VENOM OF THE CHINESE BIRD SPIDER SELENOCOSMIA-HUWENA
toxicon, 1993Co-Authors: S P Liang, Dy Zhang, Pan X, Chen Q, Pa ZhouAbstract:By means of reverse phase and ion-exchange high performance liquid chromatography, a neurotoxic peptide named huwentoxin-I was purified from the venom of the Chinese bird spider Selenocosmia huwena. The intraperitoneal and intracisternal LD50 in mice of the toxin were 0.70 mg/kg and 9.40 mug/kg, respectively. This toxin at the concentration of 1 x 10(-5) g/ml can irreversibly block the neuromuscular transmission of the isolated mouse Phrenic Nerve-Diaphragm Preparation in 13.4 +/- 1.3 min (mean +/- S.D., n = 5). The isoelectric point is 8.95 determined by isoelectric focusing electrophoresis. It consists of 33 amino acids including 6 Cys and 6 Lys determined by amino acid analysis. The complete amino sequence of huwentoxin-I was determined. The N-terminal and C-terminal residues were Ala and Leu, respectively. The primary structure showed partial homology with that of mu-agatoxins from the funnel-web spider Agelenopsis aperta.Pharmacology & PharmacyToxicologySCI(E)63ARTICLE8969-9783
Stephen Hart - One of the best experts on this subject based on the ideXlab platform.
-
A preliminary study of the effect of essential oils on skeletal and smooth muscle in vitro
Journal of ethnopharmacology, 1997Co-Authors: M. Lis-balchin, Stephen HartAbstract:The pharmacological activity of nine commercial essential oils was studied on the rat isolated Phrenic nerve diaphragm Preparation and compared with activity on field-stimulated guinea-pig ileum Preparations. The essential oils at final bath concentrations of 2 x 10(-5) and 2 x 10(-4) g/ml produced four different effects on skeletal muscle, whilst only a contracture with or without a decrease in response to field stimulation in smooth muscle. The first type of effect on skeletal muscle involved a contracture and inhibition of the twitch response to nerve stimulation shown by a sample of clary sage, dill, fennel, frankincense and nutmeg; a second, shown by thyme produced a contracture without a change in the twitch response; a third, shown by lavender reduced the twitch response alone and the fourth, shown by camphor, increased the size of the twitch response. Angelica root oil at the highest concentration studied showed no response on skeletal muscle.
Léa Rodrigues-simioni - One of the best experts on this subject based on the ideXlab platform.
-
Shared structural determinants for the calcium-independent liposome membrane permeabilization and sarcolemma depolarization in Bothropstoxin-I, a LYS49-PLA2 from the venom of Bothrops jararacussu
The international journal of biochemistry & cell biology, 2009Co-Authors: Elisangela Aparecida Aragão, Léa Rodrigues-simioni, Priscila Randazzo-moura, Sandro Rostelato-ferreira, Richard J. WardAbstract:The structural determinants of myotoxicity of bothropstoxin-I (BthTX-I), a Lys49 phospholipase A(2) from Bothrops jararacussu venom, were studied by measuring the resting membrane potential in the mouse Phrenic Nerve-Diaphragm Preparation. This method proved to be around 100-fold more sensitive than the creatine kinase release assay, and was used to evaluate a total of 31 site-directed BthTX-I alanine scanning mutants. Mutants that reduced the resting membrane potential were located in a surface patch defined by residues in the C-terminal loop (residues 115-129), positions 37-39 in the membrane interfacial recognition surface (Y46 and K54), and residue K93. These results expand the known structural determinants of the biological activity as evaluated by previous creatine kinase release experiments. Furthermore, a strong correlation is observed between the structural determinants of sarcolemma depolarization and calcium-independent disruption of liposome membranes, suggesting that a common mechanism of action underlies the permeabilization of the biological and model membranes.
-
Antineurotoxic activity of Galactia glaucescens against Crotalus durissus terrificus venom.
Fitoterapia, 2008Co-Authors: C. A. Dal Belo, G. B. Leite, Léa Rodrigues-simioni, A. V. Colares, Fábio Kiss Ticli, Suely Vilela Sampaio, Adélia Cristina Oliveira Cintra, M. G. Dos SantosAbstract:Ethanolic extract of leaves of Galactia glauscescens (GGE) at concentration of 100 and 500 μg/ml prevented the neuromuscular paralysis induced by Crotalus durissus terrificus venom on mouse Phrenic Nerve-Diaphragm Preparation.
-
Myonecrosis induced by guanidine in the mouse isolated Phrenic nerve diaphragm Preparation
General pharmacology, 1997Co-Authors: Maria Alice Da Cruz-höfling, I. Silva-carvalho, G. B. Leite, A.p. Corrado, Léa Rodrigues-simioniAbstract:Abstract 1. 1. The myonecrosis induced by guanidine in the mouse Phrenic nerve diaphragm Preparation was investigated using both light microscopy and myographic recordings. Preparations were incubated with 10 mM guanidine for 60 min in the absence and presence of electrical stimulation. At the end of this period, the drug was washed out and the nutritive medium replaced with fixative solution to prevent morphological artefacts. 2. 2. Guanidine produced a triphasic change in the amplitude of twitch tension evoked indirectly through the motor nerve. This response consisted of an initial facilitation followed by a neuromuscular blockade and a secondary facilitatory effect after removal of the drug. 3. 3. Morphological analysis of the muscle showed various structural alterations of the fibers, including the presence of very dark swollen cells with or without small clear vacuoles, delta lesions with densely or loosely clumped myofibrils, irregular clear spaces, indistinct masses of degraded myofibrils, and, in extreme cases, “ghost” cells. All of these effects were attributed to the presence of high cytosolic calcium concentrations. 4. 4. Pretreatment with tetrodotoxin (TTX, 3.13 μM) diminished but did not prevent the guanidine-induced morphological abnormalities in the muscle cells. This finding suggests that TTX can interfere to a certain extent with the influx of guanidine into muscle fibers through sodium channels. 5. 5. An attempt was made to correlate the myographic findings with the muscle morphological alterations seen after guanidine removal.
Philip M. Hopkins - One of the best experts on this subject based on the ideXlab platform.
-
5‐Hydroxytryptamine potentiates post‐tetanic twitch responses in the rat Phrenic nerve diaphragm Preparation
European journal of anaesthesiology, 1998Co-Authors: A. T. Hindle, Philip M. HopkinsAbstract:5-Hydroxytryptamine has wide-ranging effects on a number of physiological systems. In addition the exogenous application of 5-hydroxytryptamine or 5-hydroxytryptamine type drugs to tissue bath Preparations has revealed the presence of a large and ever growing population of 5-hydroxytryptamine receptors. The discovery that 5-hydroxytryptamine is released at the neuromuscular junction raises the question as to whether it has a physiological function and whether or not applying low concentrations of 5-hydroxytryptamine transmitter would have any significant effect on twitch response at different rates of stimulation. Previous studies have demonstrated both facilitatory and depressant effects upon twitch responses in a variety of animal models. Single twitch responses of the rat Phrenic nerve diaphragm Preparation at non-fatiguing (0.3 Hz) and tetanic rates of stimulation (50 Hz) were recorded under conditions of indirect (nerve) stimulation at 4 g resting tension. The Preparation was incubated with 0.5, 1, 2, 4, 16 mumol litre-1 concentrations of 5-hydroxytryptamine. The results of our investigations demonstrate that while low concentrations of 5-hydroxytryptamine have no effect upon the single twitch response at resting rates of stimulation (0.3 Hz), the initial single twitch and the subsequent eighteen responses immediately following a tetanus are facilitated (P < 0.05). This work demonstrates that 5-hydroxytryptamine does have significant effects upon the neuromuscular junction under conditions of physiological compromise (following tetanus). These observations are the first step, therefore, in a series of studies aimed at identifying the resident 5-hydroxytryptamine receptors within the neuromuscular junction which will subsequently enable us to predict therapeutic effect or toxicity.