Standardization of anti-lethal toxin potency test of antivenoms prepared from two different Agkistrodon halys venoms

In Korea, antivenoms for the treatment of patients bitten by venomous snakes have been imported from Japan or China. Although there is cross-reactivity between these antibodies and venoms from snakes indigenous to Korea (e.g. Agkistrodon genus), protection is not optimal. Antivenoms specifically prepared to neutralize Korean snake venoms could be more effective, with fewer side effects. To this end, we established an infrastructure to develop national standards and created a standardized method to evaluate the efficacy of two horse-derived antivenoms using mouse lethal toxin test. Additionally, we determined the antivenoms neutralizing activity against lethal doses (LD50) of Agkistrodon halys (from Japan) and Jiangzhe Agkistrodon halys (from China) venoms. We also performed cross-neutralization tests using probit analysis on each pairing of venom and antivenom in order to check the possibility of using Jiangzhe A. halys venom as a substitute for A. halys venom, the current standard. Slope of A. halys venom with A. halys antivenom was 10.2 and that of A. halys venom with Jiangzhe A. halys antivenom was 9.6. However, Slope of Jiangzhe A. halys venom with A. halys antivenom was 4.7 while that of Jiangzhe A. halys venom with Jiangzhe A. halys antivenom was 11.5. Therefore, the significant difference in slope patterns suggests that Jiangzhe A. halys venom cannot be used as a substitute for the standard venom to test the anti-lethal toxin activity of antivenoms (p 0.05).

Standardization of an antihemorrhagic potency test of antivenoms prepared from two different Agkistrodon halys venoms

To establish Korea National Standards for venoms and antivenoms, it is necessary to have standardized assay methods. In this study, we standardized a method to evaluate the antihemorrhagic potency of two horse-derived antivenoms using rabbit intracutaneous injection. We expressed the capability of these antivenoms to neutralize the hemorrhagic activities triggered by the venoms of Agkistrodon halys from Japan and Jiangzhe Agkistrodon halys from China as Minimum Hemorrhagic Dose (MHD). We also performed cross-neutralization tests employing the parallel line assay on different pairings of venoms and antivenoms to check the possibility of using Jiangzhe Agkistrodon halys venom as a substitute for the standard Agkistrodon halys venom in measurements of the antihemorrhagic activity, since A. halys venom is not easily available. Slope function ratio (S.R.) was 0.957 for Agkistrodon halys venom either with Agkistrodon halys antivenom or with Jiangzhe Agkistrodon halys antivenom (p>0.05). Similarly, S.R. was 0.348 for Jiangzhe Agkistrodon halys venom either with Agkistrodon halys antivenom or with Jiangzhe Agkistrodon halys antivenom (p>0.05). Thus, in this study we established antihemorrhagic potency test methods for both Agkistrodon halys and Jiangzhe Agkistrodon halys antivenoms and we could also show it is possible to use Jiangzhe Agkistrodon halys venom as a standard.

Standardization of an antihemorrhagic potency test of antivenoms prepared from two different Agkistrodon halys venoms

To establish Korea National Standards for venoms and antivenoms, it is necessary to have standardized assay methods. In this study, we standardized a method to evaluate the antihemorrhagic potency of two horse-derived antivenoms using rabbit intracutaneous injection. We expressed the capability of these antivenoms to neutralize the hemorrhagic activities triggered by the venoms of Agkistrodon halys from Japan and Jiangzhe Agkistrodon halys from China as Minimum Hemorrhagic Dose (MHD). We also performed cross-neutralization tests employing the parallel line assay on different pairings of venoms and antivenoms to check the possibility of using Jiangzhe Agkistrodon halys venom as a substitute for the standard Agkistrodon halys venom in measurements of the antihemorrhagic activity, since A. halys venom is not easily available. Slope function ratio (S.R.) was 0.957 for Agkistrodon halys venom either with Agkistrodon halys antivenom or with Jiangzhe Agkistrodon halys antivenom (p>0.05). Similarly, S.R. was 0.348 for Jiangzhe Agkistrodon halys venom either with Agkistrodon halys antivenom or with Jiangzhe Agkistrodon halys antivenom (p>0.05). Thus, in this study we established antihemorrhagic potency test methods for both Agkistrodon halys and Jiangzhe Agkistrodon halys antivenoms and we could also show it is possible to use Jiangzhe Agkistrodon halys venom as a standard.

Standardization of anti-lethal toxin potency test of antivenoms prepared from two different Agkistrodon halys venoms

In Korea, antivenoms for the treatment of patients bitten by venomous snakes have been imported from Japan or China. Although there is cross-reactivity between these antibodies and venoms from snakes indigenous to Korea (e.g. Agkistrodon genus), protection is not optimal. Antivenoms specifically prepared to neutralize Korean snake venoms could be more effective, with fewer side effects. To this end, we established an infrastructure to develop national standards and created a standardized method to evaluate the efficacy of two horse-derived antivenoms using mouse lethal toxin test. Additionally, we determined the antivenoms neutralizing activity against lethal doses (LD50) of Agkistrodon halys (from Japan) and Jiangzhe Agkistrodon halys (from China) venoms. We also performed cross-neutralization tests using probit analysis on each pairing of venom and antivenom in order to check the possibility of using Jiangzhe A. halys venom as a substitute for A. halys venom, the current standard. Slope of A. halys venom with A. halys antivenom was 10.2 and that of A. halys venom with Jiangzhe A. halys antivenom was 9.6. However, Slope of Jiangzhe A. halys venom with A. halys antivenom was 4.7 while that of Jiangzhe A. halys venom with Jiangzhe A. halys antivenom was 11.5. Therefore, the significant difference in slope patterns suggests that Jiangzhe A. halys venom cannot be used as a substitute for the standard venom to test the anti-lethal toxin activity of antivenoms (p<0.05).(AU)

A structural motif of acetylcholinesterase that promotes amyloid beta-peptide fibril formation.

Acetylcholinesterase (AChE) has been found to be associated with the core of senile plaques. We have shown that AChE interacts with the amyloid beta-peptide (Abeta) and promotes amyloid fibril formation by a hydrophobic environment close to the peripheral anionic binding site (PAS) of the enzyme. Here we present evidence for the structural motif of AChE involved in this interaction. First, we modeled the docking of Abeta onto the structure of Torpedo californica AChE, and identified four potential sites for AChE-Abeta complex formation. One of these, Site I, spans a major hydrophobic sequence exposed on the surface of AChE, which had been previously shown to interact with liposomes [Shin et al. (1996) Protein Sci. 5, 42-51]. Second, we examined several AChE-derived peptides and found that a synthetic 35-residue peptide corresponding to the above hydrophobic sequence was able to promote amyloid formation. We also studied the ability to promote amyloid formation of two synthetic 24-residue peptides derived from the sequence of a Omega-loop, which has been suggested as an AChE-Abeta interacting motif. Kinetic analyses indicate that only the 35-residue hydrophobic peptide mimics the effect of intact AChE on amyloid formation. Moreover, RP-HPLC analysis revealed that the 35-residue peptide was incorporated into the growing Abeta-fibrils. Finally, fluorescence binding studies showed that this peptide binds Abeta with a K(d) = 184 microM, independent of salt concentration, indicating that the interaction is primarily hydrophobic. Our results indicate that the homologous human AChE motif is capable of accelerating Abeta fibrillogenesis.