Jose Guadalupe Quezada Amezcua - Academia.edu (original) (raw)

Papers by Jose Guadalupe Quezada Amezcua

Research paper thumbnail of Anionic currents of chick sensory neurons are affected by a phospholipase A2 purified from the venom of the taipan snake

… et Biophysica Acta (BBA …, 1992

A neurotoxic phospholipase A 2 was purified from the venom of the taipan snake Oxyuranus scutella... more A neurotoxic phospholipase A 2 was purified from the venom of the taipan snake Oxyuranus scutellatus scutellatus by three consecutive chromatographic steps on ion exchange resins, followed by an affinity column prepared with a phosphatidylcholine derivative attached to Sepharose. The phospholipase was shown to be of type A 2 (specific activity of 85 units/rag protein), and an apparent molecular weight of 16000. Amino acid analysis shows the presence of approx. 150 residues with the N-terminal amino acid sequence: NLAQFGFMIRCANGGSRSALDYADYGC, different from all the phospholipases described until now. This enzyme is lethal to experimental mice (LDse ffi 10 ttg/20 g mouse weight) and affects ionic currents in chick (Gallus domesticus) 'dorsal root ganglion cells, measured by the whole-cell clamp technique. In symmetrical external/internal ionic solutions, after suppression of Na +, K + and Ca 2+ currents, external application of phospholipase at a low concentration (30 aM) was shown to increase the baseline current in a reversible manner. The augmented response was voltage-dependent and the effect was much greater for negative currents. In the presence of a salt gradient across the membrane (out 40 mM NaCI/in 140 mM CsCI), the current reversal potential revealed a shift in the positive direction typically due to CI-ion flux through the membrane. External application of a 50 ttM concentration of picrotoxin caused a reversible reduction of the phospholipaseinduced chloride current. Moreover, no appreciable current block was detected after addition of 50/tM DIDS.

Research paper thumbnail of Anionic currents of chick sensory neurons are affected by a phospholipase A2 purified from the venom of the taipan snake

… et Biophysica Acta (BBA …, 1992

A neurotoxic phospholipase A 2 was purified from the venom of the taipan snake Oxyuranus scutella... more A neurotoxic phospholipase A 2 was purified from the venom of the taipan snake Oxyuranus scutellatus scutellatus by three consecutive chromatographic steps on ion exchange resins, followed by an affinity column prepared with a phosphatidylcholine derivative attached to Sepharose. The phospholipase was shown to be of type A 2 (specific activity of 85 units/rag protein), and an apparent molecular weight of 16000. Amino acid analysis shows the presence of approx. 150 residues with the N-terminal amino acid sequence: NLAQFGFMIRCANGGSRSALDYADYGC, different from all the phospholipases described until now. This enzyme is lethal to experimental mice (LDse ffi 10 ttg/20 g mouse weight) and affects ionic currents in chick (Gallus domesticus) 'dorsal root ganglion cells, measured by the whole-cell clamp technique. In symmetrical external/internal ionic solutions, after suppression of Na +, K + and Ca 2+ currents, external application of phospholipase at a low concentration (30 aM) was shown to increase the baseline current in a reversible manner. The augmented response was voltage-dependent and the effect was much greater for negative currents. In the presence of a salt gradient across the membrane (out 40 mM NaCI/in 140 mM CsCI), the current reversal potential revealed a shift in the positive direction typically due to CI-ion flux through the membrane. External application of a 50 ttM concentration of picrotoxin caused a reversible reduction of the phospholipaseinduced chloride current. Moreover, no appreciable current block was detected after addition of 50/tM DIDS.

Research paper thumbnail of Genome amplification of human papillomavirus types 16 and 18 in cervical carcinomas is related to the retention of E1/E2 genes

International Journal of Cancer, 1994

The level of amplification (copy number/cell) of HPV16 and HPV18 viral genomes and its correlatio... more The level of amplification (copy number/cell) of HPV16 and HPV18 viral genomes and its correlation with the presence of EI/E2 genes were analyzed in a sample of 42 HPVl6-and 21

Research paper thumbnail of Anionic currents of chick sensory neurons are affected by a phospholipase A2 purified from the venom of the taipan snake

… et Biophysica Acta (BBA …, 1992

A neurotoxic phospholipase A 2 was purified from the venom of the taipan snake Oxyuranus scutella... more A neurotoxic phospholipase A 2 was purified from the venom of the taipan snake Oxyuranus scutellatus scutellatus by three consecutive chromatographic steps on ion exchange resins, followed by an affinity column prepared with a phosphatidylcholine derivative attached to Sepharose. The phospholipase was shown to be of type A 2 (specific activity of 85 units/rag protein), and an apparent molecular weight of 16000. Amino acid analysis shows the presence of approx. 150 residues with the N-terminal amino acid sequence: NLAQFGFMIRCANGGSRSALDYADYGC, different from all the phospholipases described until now. This enzyme is lethal to experimental mice (LDse ffi 10 ttg/20 g mouse weight) and affects ionic currents in chick (Gallus domesticus) 'dorsal root ganglion cells, measured by the whole-cell clamp technique. In symmetrical external/internal ionic solutions, after suppression of Na +, K + and Ca 2+ currents, external application of phospholipase at a low concentration (30 aM) was shown to increase the baseline current in a reversible manner. The augmented response was voltage-dependent and the effect was much greater for negative currents. In the presence of a salt gradient across the membrane (out 40 mM NaCI/in 140 mM CsCI), the current reversal potential revealed a shift in the positive direction typically due to CI-ion flux through the membrane. External application of a 50 ttM concentration of picrotoxin caused a reversible reduction of the phospholipaseinduced chloride current. Moreover, no appreciable current block was detected after addition of 50/tM DIDS.

Research paper thumbnail of Anionic currents of chick sensory neurons are affected by a phospholipase A2 purified from the venom of the taipan snake

… et Biophysica Acta (BBA …, 1992

A neurotoxic phospholipase A 2 was purified from the venom of the taipan snake Oxyuranus scutella... more A neurotoxic phospholipase A 2 was purified from the venom of the taipan snake Oxyuranus scutellatus scutellatus by three consecutive chromatographic steps on ion exchange resins, followed by an affinity column prepared with a phosphatidylcholine derivative attached to Sepharose. The phospholipase was shown to be of type A 2 (specific activity of 85 units/rag protein), and an apparent molecular weight of 16000. Amino acid analysis shows the presence of approx. 150 residues with the N-terminal amino acid sequence: NLAQFGFMIRCANGGSRSALDYADYGC, different from all the phospholipases described until now. This enzyme is lethal to experimental mice (LDse ffi 10 ttg/20 g mouse weight) and affects ionic currents in chick (Gallus domesticus) 'dorsal root ganglion cells, measured by the whole-cell clamp technique. In symmetrical external/internal ionic solutions, after suppression of Na +, K + and Ca 2+ currents, external application of phospholipase at a low concentration (30 aM) was shown to increase the baseline current in a reversible manner. The augmented response was voltage-dependent and the effect was much greater for negative currents. In the presence of a salt gradient across the membrane (out 40 mM NaCI/in 140 mM CsCI), the current reversal potential revealed a shift in the positive direction typically due to CI-ion flux through the membrane. External application of a 50 ttM concentration of picrotoxin caused a reversible reduction of the phospholipaseinduced chloride current. Moreover, no appreciable current block was detected after addition of 50/tM DIDS.

Research paper thumbnail of Genome amplification of human papillomavirus types 16 and 18 in cervical carcinomas is related to the retention of E1/E2 genes

International Journal of Cancer, 1994

The level of amplification (copy number/cell) of HPV16 and HPV18 viral genomes and its correlatio... more The level of amplification (copy number/cell) of HPV16 and HPV18 viral genomes and its correlation with the presence of EI/E2 genes were analyzed in a sample of 42 HPVl6-and 21