Alejandro Alagón

Publications of Alejandro Alagón

• Neutralization of Vipera and Macrovipera venoms by two experimental polyvalent antisera: a study of paraspecificity.

  Authors: Irving G Archundia, Adolfo R de Roodt, Blanca Ramos-Cerrillo, Jean-Philippe Chippaux, Laura Olguín-Pérez, Alejandro Alagón, Roberto P Stock

  Toxicon : official journal of the International Society on Toxinology. 06/2011; 57(7-8):1049-56.

  We conducted an extensive study of neutralization of lethality of 11 species and one subspecies of snakes of the genus Vipera, and of five species of Macrovipera, by two experimental equine antisera.We conducted an extensive study of neutralization of lethality of 11 species and one subspecies of snakes of the genus Vipera, and of five species of Macrovipera, by two experimental equine antisera. One antiserum was a trivalent preparation raised against the venoms of Vipera aspis aspis, Vipera berus berus and Vipera ammodytes ammodytes; the other was a pentavalent preparation that also included venoms of Vipera (now Montivipera) xanthina and Macrovipera lebetina obtusa. We measured specific neutralization of lethality against all venoms included in the immunization schemes, and paraspecific neutralization against the venoms of Vipera ammodytes montandoni, Vipera (Montivipera) bornmuelleri, Vipera latastei, Vipera (Mo.) latifii, Vipera (Mo.) lotievi, Vipera (Daboia) palaestinae, Vipera (Mo.) raddei and Vipera seoanei, as well as against Macrovipera (D.) deserti, Macrovipera lebetina cernovi, Macrovipera lebetina turanica and Macrovipera schweitzeri. We found an important degree of paraspecific protection within each genera (omitting recent reclassification) that was quite independent of both the lethal potency of the venoms and their geographic origin. This information may be of use to clinicians charged with the treatment of Vipera or Macrovipera envenomations with non-specific antivenoms.

• Pharmacokinetics of a F(ab')2 scorpion antivenom administered intramuscularly in healthy human volunteers.

  Authors: Hilda Vázquez, Alfredo Chávez-Haro, Walter García-Ubbelohde, Jorge Paniagua-Solís, Alejandro Alagón, Carlos Sevcik

  International immunopharmacology. 11/2010; 10(11):1318-24.

  This paper presents the first study of F(ab')(2) scorpion antivenom pharmacokinetics in humans after intramuscular (im) administration. The specific anti-Centruroides scorpion antivenom was used in 6This paper presents the first study of F(ab')(2) scorpion antivenom pharmacokinetics in humans after intramuscular (im) administration. The specific anti-Centruroides scorpion antivenom was used in 6 human healthy volunteers. The fabotherapeutic was administered as a 47.5mg im bolus. Blood samples were drawn at 0, 5, 15, 30, 45, 60 , 90, 120, and 180 min, 6h and at 1, 2, 3, 4, 10 and 21 days after antivenom administration. We measured antivenom concentrations in serum using a specific high sensitivity ELISA method for F(ab')(2). Antivenom concentration in serum was fit to a 3 compartment model (inoculation site, plasma and extra vascular extracellular space), it was assumed that the venom may also be irreversibly removed from plasma. Calculated time course of antivenom content shows that at any time no more that 16.6 (5.3, 31.9)% (median and 95% confidence interval) of the antivenom bolus is present in plasma. The time to peak plasma [F(ab')(2)] was 45 (33, 74) h. The most significant antivenom pharmacokinetic parameters determined were: AUC(im,∞)=803 (605, 1463) mg·h·L(-1); V(c)=8.8 (2.8, 23.6) L; V(ss,im)=55 (47, 64) L; MRT(im)=776(326, 1335) h; CL(t)=3.7 (0.6, 1.9) mL·min(-1); f(im,)V(ss)=0.300 (0.153, 0.466). Comparing these parameters with the ones obtained intravenously by Vázquez et al., the parameters were more disperse between subjects, determined with more uncertainty in each individual subject, and the peak F(ab')(2) in plasma occurred with considerable delay; all indicating that the IM route should not be used to administer the antivenom, with the possible exception of cases occurring very far from hospitals, as an extreme means to provide some protection before the IV route becomes available.

• Antivenom for critically ill children with neurotoxicity from scorpion stings.

  Authors: Leslie V Boyer, Andreas A Theodorou, Robert A Berg, Joanne Mallie, Ariana Chávez-Méndez, Walter García-Ubbelohde, Stephen Hardiman, Alejandro Alagón

  The New England journal of medicine. 06/2009; 360(20):2090-8.

  BACKGROUND: Clinically significant scorpion envenomation by Centruroides sculpturatus produces a dramatic neuromotor syndrome and respiratory insufficiency that often necessitate intensive supportiveBACKGROUND: Clinically significant scorpion envenomation by Centruroides sculpturatus produces a dramatic neuromotor syndrome and respiratory insufficiency that often necessitate intensive supportive care. We hypothesized that a scorpion-specific F(ab')(2) antivenom would promptly resolve clinical symptoms in children with this syndrome. METHODS: In a randomized, double-blind study, the efficacy of scorpion-specific F(ab')(2) antivenom, as compared with placebo, was assessed in 15 children 6 months to 18 years of age who were admitted to a pediatric intensive care unit with clinically significant signs of scorpion envenomation. The primary end point was the resolution of the clinical syndrome within 4 hours after administration of the study drug. Secondary end points included the total dose of concomitant midazolam for sedation and quantitative plasma venom levels, before and after treatment. RESULTS: The clinical syndrome resolved more rapidly among recipients of the antivenom than among recipients of placebo, with a resolution of symptoms in all eight antivenom recipients versus one of seven placebo recipients within 4 hours after treatment (P=0.001). More midazolam was administered in the placebo recipients than in the antivenom recipients (mean cumulative dose, 4.61 vs. 0.07 mg per kilogram of body weight; P=0.01). Plasma venom concentrations were undetectable in all eight antivenom recipients but in only one placebo recipient 1 hour after treatment (P=0.001). CONCLUSIONS: Among critically ill children with neurotoxic effects of scorpion envenomation, intravenous administration of scorpion-specific F(ab')(2) antivenom resolved the clinical syndrome within 4 hours, reduced the need for concomitant sedation with midazolam, and reduced the levels of circulating unbound venom. (ClinicalTrials.gov number, NCT00685230.)

• Paraspecific neutralization of the venom of African species of cobra by an equine antiserum against Naja melanoleuca: a comparative study.

  Authors: Andrea Casasola, Blanca Ramos-Cerrillo, Adolfo R de Roodt, Alejandro Carbajal Saucedo, Jean-Philippe Chippaux, Alejandro Alagón, Roberto P Stock

  Toxicon : official journal of the International Society on Toxinology. 06/2009; 53(6):602-8.

  Venoms of snakes belonging to the same Genera tend to share biochemical, toxinological and antigenic characteristics. Accordingly, paraspecific neutralization of venom lethality by experimentalVenoms of snakes belonging to the same Genera tend to share biochemical, toxinological and antigenic characteristics. Accordingly, paraspecific neutralization of venom lethality by experimental antisera and commercial antivenoms has been reported. We studied the spectrum of neutralization of lethality of an experimental monovalent equine antiserum against the strongly neurotoxic African forest cobra (Naja melanoleuca) when tested against venoms of most species of African Naja, both neuro and cytotoxic as described by some authors. We report a comparison of the median lethal doses (LD50) of the venoms and the paraspecific median effective doses (ED50) of the antiserum calculated using three methods: Spearman-Kärber and Probit (currently recommended by the World Health Organization), and non-linear regression. An ample--but not complete--spectrum of paraspecific neutralization of lethality was observed against both spitting and non-spitting species of African Naja with a clearly more efficient neutralization of the more potent venoms, the implications of which are discussed. The median lethal and effective doses calculated by the three methods are remarkably consistent and may warrant consideration of non-linear regression methods for the calculation of venom lethality and antivenom potency by venom/antivenom researchers and producers.

• Insecticidal peptides from the theraposid spider Brachypelma albiceps: A NMR-based model of Ba2.

  Authors: Gerardo Corzo, Cedric Bernard, Herlinda Clement, Elba Villegas, Frank Bosmans, Jan Tytgat, Lourival D Possani, Herve Darbon, Alejandro Alagón

  Biochimica et biophysica acta. 05/2009;

  Soluble venom and purified fractions of the theraposid spider Brachypelma albiceps were screened for insecticidal peptides based on toxicity to crickets. Two insecticidal peptides, named Ba1 and Ba2,Soluble venom and purified fractions of the theraposid spider Brachypelma albiceps were screened for insecticidal peptides based on toxicity to crickets. Two insecticidal peptides, named Ba1 and Ba2, were obtained after the soluble venom was separated by high performance liquid chromatography and cation exchange chromatography. The two insecticidal peptides contain 39 amino acid residues and three disulfide bonds, and based on their amino acid sequence, they are highly identical to the insecticidal peptides from the theraposid spiders Aphonopelma sp. from USA and Haplopelma huwenum from China indicating a relationship among these genera. Although Ba1 and Ba2 were not able to modify currents in insect and vertebrate cloned voltage-gated sodium ion channels, they have noteworthy insecticidal activities compared to classical arachnid insecticidal toxins indicating that they might target unknown receptors in insect species. The most abundant insecticidal peptide Ba2 was submitted to NMR spectroscopy to determine its 3-D structure; a remarkable characteristic of Ba2 is a cluster of basic residues, which might be important for receptor recognition.

• Characterization of a new polyvalent antivenom (Antivipmyn((R)) Africa) against African vipers and elapids.

  Authors: Blanca Ramos-Cerrillo, Adolfo R de Roodt, Jean-Philippe Chippaux, Laura Olguín, Andrea Casasola, Guadalupe Guzmán, Jorge Paniagua-Solís, Alejandro Alagón, Roberto P Stock

  Toxicon : official journal of the International Society on Toxinology. 10/2008;

  As a response to the antivenom shortage in Sub-Saharan Africa, evident for well over a decade, we developed a new polyvalent anti-ophidian antivenom (Antivipmyn((R)) Africa) designed for use in theAs a response to the antivenom shortage in Sub-Saharan Africa, evident for well over a decade, we developed a new polyvalent anti-ophidian antivenom (Antivipmyn((R)) Africa) designed for use in the region. We report a detailed characterization of its biochemical composition (protein content and profiling by size-exclusion chromatography and electrophoresis) as well as the specific and para-specific neutralization potencies (as median effective dose in the mouse lethality test). Additionally, we studied the neutralization of hemorrhagic, anti-hemostatic and necrotic activities of Echis ocellatus venom, responsible for a majority of severe envenomations in the continent according to existing epidemiological data. The antivenom is currently under production and has already been employed in the field in a pragmatic Phase III clinical trial in the Republic of Benin. It is a purified lyophilized polyvalent equine F(ab')(2)-based product obtained by immunization with the venoms of eleven species of African snakes of the Genera Echis, Bitis, Naja and Dendroaspis. The criteria for its design are discussed, particularly in terms of the implementation of realistic public health policies targeting mostly rural populations in the continent.

• An insecticidal peptide from the theraposid Brachypelma smithi spider venom reveals common molecular features among spider species from different genera.

  Authors: Gerardo Corzo, Elia Diego-García, Herlinda Clement, Steve Peigneur, George Odell, Jan Tytgat, Lourival D Possani, Alejandro Alagón

  Peptides. 08/2008;

  The soluble venom of the Mexican theraposid spider Brachypelma smithi was screened for insecticidal peptides based on toxicity to house crickets. An insecticidal peptide, named Bs1 (which stands forThe soluble venom of the Mexican theraposid spider Brachypelma smithi was screened for insecticidal peptides based on toxicity to house crickets. An insecticidal peptide, named Bs1 (which stands for Brachypelma smithi toxin 1) was obtained in homogeneous form after the soluble venom was fractionated using reverse-phase and cation-exchange chromatography. It contains 41 amino acids cross-linked by three disulfide bridges. Its sequence is similar to an insecticidal peptide isolated from the theraposid spider Ornithoctonus huwena from China, and another from the hexathelid spider Macrothelegigas from Japan, indicating that they are phylogenetically related. A cDNA library was prepared from the venomous glands of B. smithi and the gene that code for Bs1 was cloned. Sequence analysis of the nucleotides of Bs1 showed similarities to that of the hexathelid spider from Japan proving additional evidence for close genetic relationship between these spider peptides. The mRNAs of these toxins code for signal peptides that are processed at the segment rich in acidic and basic residues. Their C-terminal amino acids are amidated. However, they contain only a glycine residue at the most C-terminal position, without the presence of additional basic amino acid residues, normally required for post-translation processing of other toxins reported in the literature. The possible mechanism of action of Bs1 was investigated using several ion channels as putative receptors. Bs1 had minor, but significant effects on the Para/tipE insect ion channel, which could indirectly correlate with the observed lethal activity to crickets.

• Toxicity of two North American Loxosceles (brown recluse spiders) venoms and their neutralization by antivenoms.

  Authors: Adolfo Rafael de Roodt, Judith Estevez-Ramírez, Silvana Litwin, Penélope Magaña, Alejandro Olvera, Alejandro Alagón

  Clinical toxicology (Philadelphia, Pa.). 10/2007; 45(6):678-87.

  The toxic, biochemical, and immunological characteristics of L. boneti and L. reclusa venoms and its neutralization by anti-L. boneti and anti-L. reclusa antivenoms were studied. The electrophoreticThe toxic, biochemical, and immunological characteristics of L. boneti and L. reclusa venoms and its neutralization by anti-L. boneti and anti-L. reclusa antivenoms were studied. The electrophoretic profile showed very similar patterns and the toxic activities were very close. Immunological studies showed cross-reactivity among L. boneti and L. reclusa venoms, with L. boneti and L. reclusa experimental antivenoms, and anti-L. gaucho and anti-L. laeta antivenoms. The venom of L. laeta showed low immunological reactivity with the North American Loxosceles antivenoms. Experimental anti-North American Loxosceles antivenoms protected mice of the systemic toxicity and were able to prevent necrosis in rabbit skin after the injection of the venom. Both antivenoms displayed cross neutralization. The results showed that both Loxosceles venoms have very close toxic, biochemical, and immunological characteristics, and that either monospecific antivenoms or an antivenom raised with L. boneti and L. reclusa venoms as immunogens could be useful for treating bites by North American Loxosceles spiders.

• Isolation and characterization of a novel toxin from the venom of the spider Grammostola rosea that blocks sodium channels.

  Authors: Herlinda Clement, George Odell, Fernando Z Zamudio, Elisa Redaelli, Enzo Wanke, Alejandro Alagón, Lourival D Possani

  Toxicon : official journal of the International Society on Toxinology. 08/2007; 50(1):65-74.

  This communication reports the chemical and physiological characterization of a novel peptide (GrTx1) isolated from the venom of the "rosean-tarantula"Grammostola rosea. This component was one amongThis communication reports the chemical and physiological characterization of a novel peptide (GrTx1) isolated from the venom of the "rosean-tarantula"Grammostola rosea. This component was one among more than 15 distinct components separated from the soluble venom by high-performance liquid chromatography (HPLC). GrTx1 has 29 amino-acid residues, compactly folded by three disulfide bridges with a molecular weight of 3697Da. Here we show that this peptide blocks Na(+) currents of neuroblastoma F-11 cells with an IC(50) of 2.8+/-0.1muM, up to a maximum of about 85% at 10muM. Moreover, the right-shift (+20.1+/-0.4mV) of the fractional voltage-dependent conductance could be also compatible with a putative "gating-modifier" mechanism. No effects were seen on common K(+) channels, such as K(v)1.1 and 1.4, using concentrations of toxin up to 10muM. Sequence analysis reveals that GrTx1 is closely related to other spider toxins reported to affect various distinct ion channel functions. A critical analysis of this study suggests the necessity to search for other potential receptor sites in order to establish the preferred specificity of these kind of peptides.

• Bringing antivenoms to Sub-Saharan Africa.

  Authors: Roberto P Stock, Achille Massougbodji, Alejandro Alagón, Jean-Philippe Chippaux

  Nature biotechnology. 03/2007; 25(2):173-7.

  To reduce unacceptably high death rates from snakebite envenomation, sub-Saharan Africa must adopt not only a new generation of multivalent biotech antivenoms, but also an infrastructure to deliverTo reduce unacceptably high death rates from snakebite envenomation, sub-Saharan Africa must adopt not only a new generation of multivalent biotech antivenoms, but also an infrastructure to deliver them.

• North and South American Loxosceles spiders: development of a polyvalent antivenom with recombinant sphingomyelinases D as antigens.

  Authors: Alejandro Olvera, Blanca Ramos-Cerrillo, Judith Estévez, Herlinda Clement, Adolfo de Roodt, Jorge Paniagua-Solís, Hilda Vázquez, Alfonso Zavaleta, María Salas Arruz, Roberto P Stock, Alejandro Alagón

  Toxicon : official journal of the International Society on Toxinology. 08/2006; 48(1):64-74.

  We report the cloning of sphingomyelinase D (SMD) cDNA from Loxosceles reclusa, Loxosceles boneti and Loxosceles laeta into bacterial expression systems, as well as optimization of expressionWe report the cloning of sphingomyelinase D (SMD) cDNA from Loxosceles reclusa, Loxosceles boneti and Loxosceles laeta into bacterial expression systems, as well as optimization of expression conditions so as to obtain soluble and active recombinant enzymes. The recombinant mature SMDs, tagged with a histidine tail at the N- or C-termini, were compared in terms of toxicity and enzymatic activity, and were used as immunogens for the production of monovalent antisera in rabbits and F(ab')(2) preparations in animals used for commercial antivenom production (horses). We performed studies on in vitro inhibition of enzymatic activity of natural venom preparations by antibodies generated against the tagged proteins. We also present and discuss the results of studies on the specific and para-specific in vivo protective potential of the rabbit and equine antibody preparations against the recombinant proteins themselves and natural venom preparations. Our conclusions support the feasibility of using recombinant SMDs for production and evaluation of polyvalent anti-Loxosceles antivenoms, and we offer data on the potential of paraspecific neutralization in the context of the antigenic groupings and the molecular phylogeny of those active SMDs for which amino acid sequence information is available.

• Identification of an Entamoeba histolytica gene encoding a protein disulfide isomerase that functionally complements the dsbA mutation in Escherichia coli.

  Authors: Marco A Ramos, Rosana Sanchez-Lopez, Rosa E Mares, Felipe Olvera, Alejandro Alagón

  Molecular and biochemical parasitology. 11/2005; 143(2):236-40.

• Entamoeba histolytica: biochemical and molecular insights into the activities within microsomal fractions.

  Authors: Milena Salgado, Julio C Villagómez-Castro, Rocío Rocha-Rodríguez, Myrna Sabanero-López, Marco A Ramos, Alejandro Alagón, Everardo López-Romero, Rosana Sánchez-López

  Experimental parasitology. 09/2005; 110(4):363-73.

  One of the most fascinating aspects of the Entamoeba histolytica trophozoite ultrastructure is the lack of a typical secretory pathway, particularly of rough endoplasmic reticulum and Golgi system,One of the most fascinating aspects of the Entamoeba histolytica trophozoite ultrastructure is the lack of a typical secretory pathway, particularly of rough endoplasmic reticulum and Golgi system, in a cell with such a high secretory activity. Here, we describe the isolation of amoeba cell structures containing ER-typical activities. Following isopycnic centrifugation of plasma membrane-free extracts, microsomes enriched in enzymatic activities such as dolichol-P-mannose synthase (DPMS; EC 2.4.1.83), UDP-GlcNAc:dolichol-P GlcNAc-1-P transferase (NAGPT; EC 2.7.8.15), and UDP-D-GlcNAc:dolichol-PP GlcNAc (NAGT; EC 2.4.1.141) were resolved from phagolysosomal fractions. Sec61alpha-subunit, an ER-marker involved in the translocation of nascent proteins to the ER, was found to co-fractionate with DPMS activity indicating that they are contained in microsomes with a similar density. Further, we optimized conditions for trophozoite homogenization and differential centrifugation that resulted in the separation of a 57,000 g-sedimenting microsomal fraction containing EhSec61alpha-subunit, EhDPMS, and EhPDI (protein disulfide isomerase, a soluble marker of the lumen of the ER). A relevant observation was the lack of ER markers associated to the nuclear fraction. Large macromolecular structures such as Ehproteasome were sedimented at a higher speed. Our knowledge of the molecular machinery involved in the biosynthesis of dolichol-linked oligosaccharide was enriched with the identification of putative genes related to the stepwise assembly of the dolichol-PP-GlcNAc(2)Man(5) core. No evidence of genes supporting further assembly steps was obtained at this time.

• Report of the 2nd International Conference on Envenomations in Africa (Deuxième Colloque International sur les Envenomations en Afrique).

  Authors: Jean-Philippe Chippaux, Roberto P Stock, Alejandro Alagón

  Toxicon : official journal of the International Society on Toxinology. 08/2005; 46(1):115-8.

  An international meeting on envenomations in Africa was held in Cotonou, Republic of Benin, the 19th and 20th of September, 2004, to gather clinical practitioners, epidemiologists, health authoritiesAn international meeting on envenomations in Africa was held in Cotonou, Republic of Benin, the 19th and 20th of September, 2004, to gather clinical practitioners, epidemiologists, health authorities and antivenom producers to present and discuss the most recent available data on the prevalence of snake envenomations in Africa. The meeting concluded with a round table which had the objective of evaluating the problems facing the epidemiology and therapy of envenomations by African snakes and making some general recommendations at the level of national health authorities, researchers, medical practitioners, and international antivenom producers.

• Entamoeba histolytica: intracellular distribution of the sec61alpha subunit of the secretory pathway and down-regulation by antisense peptide nucleic acids.

  Authors: Ricardo Sánchez, Andrés Saralegui, Alfonso Olivos-García, Carlo Scapolla, Gianluca Damonte, Rosana Sanchez-Lopez, Alejandro Alagón, Roberto P Stock

  Experimental parasitology. 05/2005; 109(4):241-51.

  The Sec61alpha protein is defined as a highly conserved essential integral component of the endoplasmic reticulum in eukaryotic cells. We report a detailed immunolocalization of the EntamoebaThe Sec61alpha protein is defined as a highly conserved essential integral component of the endoplasmic reticulum in eukaryotic cells. We report a detailed immunolocalization of the Entamoeba histolytica homologue of the Sec61alpha subunit (EhSec61alpha), which shows an irregular pattern throughout the cell and is also found on the cell surface, its effective down-regulation by means of antisense peptide nucleic acids and its effects on cell proliferation, subcellular distribution of two virulence factors, and the ability of the trophozoites to cause liver abscess in hamsters. Although Sec61alpha levels are specifically decreased in antisense PNA-treated trophozoites, which proliferate more slowly than the controls, mobilization of the cysteine protease 5 and amoebapore to the cell surface is not significantly impeded and the capacity to induce liver abscess in hamsters is largely unaffected. The implications of these findings are discussed in the context of the peculiar cell biology of E. histolytica.

• Genetic and enzymatic characterization of sphingomyelinase D isoforms from the North American fiddleback spiders Loxosceles boneti and Loxosceles reclusa.

  Authors: Blanca Ramos-Cerrillo, Alejandro Olvera, George V Odell, Fernando Zamudio, Jorge Paniagua-Solís, Alejandro Alagón, Roberto P Stock

  Toxicon : official journal of the International Society on Toxinology. 11/2004; 44(5):507-14.

  In this study we report the isolation and characterization of several sphingomyelinase D isoforms from the venoms of the North American spiders Loxosceles boneti and Loxosceles reclusa, from MexicoIn this study we report the isolation and characterization of several sphingomyelinase D isoforms from the venoms of the North American spiders Loxosceles boneti and Loxosceles reclusa, from Mexico and the United States, respectively. We have measured their enzymatic activity, their capacity to induce necrotic lesions in rabbits, cloned the cDNAs coding for the mature forms of two of the isoforms from L. boneti and two of L. reclusa based on N-terminal sequence information of the purified proteins, and performed a comprehensive comparison of the sequence data generated by us with that reported for other sphingomyelinase genes to date.

• Effectiveness of two common antivenoms for North, Central, and South American Micrurus envenomations.

  Authors: Adolfo R de Roodt, Jorge F Paniagua-Solis, Jorge A Dolab, Judith Estévez-Ramiréz, Blanca Ramos-Cerrillo, Silvana Litwin, José C Dokmetjian, Alejandro Alagón

  Journal of toxicology. Clinical toxicology. 02/2004; 42(2):171-8.

  Micrurus snakes (coral snakes) may produce severe envenomation that can lead to death by peripheral respiratory paralysis. Only few laboratories produce specific antivenoms, and despite theMicrurus snakes (coral snakes) may produce severe envenomation that can lead to death by peripheral respiratory paralysis. Only few laboratories produce specific antivenoms, and despite the cross-reactivity found in some Micrurus species venoms, the treatment is not always effective. To test two therapeutic antivenoms against the venom of four species of Micrurus from Southern America, North of South America, Central America, and North America, the determination of the lethal potency of the venoms, the study of some biochemical and immunochemical characteristics, and the determination of the neutralizing activity of both antivenoms were studied. North American and South American antivenoms neutralized well venoms from Micrurus species of the corresponding hemisphere but displayed lower effectiveness against venoms of species from different hemispheres. It was concluded that the neutralization of Micrurus venoms by regional antivenoms could be useful to treat the envenomation by some Micrurus snakes but is necessary to evaluate carefully the antivenoms to be used with the venoms from the snakes of the region. Also, considering the difficulties for coral snake antivenom production, the development of a polyvalent antivenom is useful to treat the envenomation by coral snakes from different regions is necessary.

• Maize HSP101 plays important roles in both induced and basal thermotolerance and primary root growth.

  Authors: Jorge Nieto-Sotelo, Luz María Martínez, Georgina Ponce, Gladys I Cassab, Alejandro Alagón, Robert B Meeley, Jean-Marcel Ribaut, Runying Yang

  The Plant cell. 08/2002; 14(7):1621-33.

  HSP101 belongs to the ClpB protein subfamily whose members promote the renaturation of protein aggregates and are essential for the induction of thermotolerance. We found that maize HSP101HSP101 belongs to the ClpB protein subfamily whose members promote the renaturation of protein aggregates and are essential for the induction of thermotolerance. We found that maize HSP101 accumulated in mature kernels in the absence of heat stress. At optimal temperatures, HSP101 disappeared within the first 3 days after imbibition, although its levels increased in response to heat shock. In embryonic cells, HSP101 concentrated in the nucleus and in some nucleoli. Hsp101 maps near the umc132 and npi280 markers on chromosome 6. Five maize hsp101-m-::Mu1 alleles were isolated. Mutants were null for HSP101 and defective in both induced and basal thermotolerance. Moreover, during the first 3 days after imbibition, primary roots grew faster in the mutants at optimal temperature. Thus, HSP101 is a nucleus-localized protein that, in addition to its role in thermotolerance, negatively influences the growth rate of the primary root. HSP101 is dispensable for proper embryo and whole plant development in the absence of heat stress.

• Entamoeba histolytica genomic organization: identification, structure, and phylogenetic relationship of two serine-threonine protein kinases.

  Authors: Marco A Ramos, Rosana Sanchez-Lopez, Felipe Olvera, Alejandro Alagón

  Experimental parasitology. 03/2002; 100(2):135-9.

• Insecticidal peptides from the theraposid spider Brachypelma albiceps: An NMR-based model of Ba2

  Authors: Gerardo Corzo, Cedric Bernard, Herlinda Clement, Elba Villegas, Frank Bosmans, Jan Tytgat, Lourival D. Possani, Herve Darbon, Alejandro Alagón

  Biochimica et Biophysica Acta (BBA) - Proteins & Proteomics.

  Soluble venom and purified fractions of the theraposid spider Brachypelma albiceps were screened for insecticidal peptides based on toxicity to crickets. Two insecticidal peptides, named Ba1 and Ba2,Soluble venom and purified fractions of the theraposid spider Brachypelma albiceps were screened for insecticidal peptides based on toxicity to crickets. Two insecticidal peptides, named Ba1 and Ba2, were obtained after the soluble venom was separated by high performance liquid chromatography and cation exchange chromatography. The two insecticidal peptides contain 39 amino acid residues and three disulfide bonds, and based on their amino acid sequence, they are highly identical to the insecticidal peptides from the theraposid spiders Aphonopelma sp. from the USA and Haplopelma huwenum from China indicating a relationship among these genera. Although Ba1 and Ba2 were not able to modify currents in insect and vertebrate cloned voltage-gated sodium ion channels, they have noteworthy insecticidal activities compared to classical arachnid insecticidal toxins indicating that they might target unknown receptors in insect species. The most abundant insecticidal peptide Ba2 was submitted to NMR spectroscopy to determine its 3-D structure; a remarkable characteristic of Ba2 is a cluster of basic residues, which might be important for receptor recognition.