Using a recombinant bispecific antibody to block Na<Superscript>+</Superscript>-channel toxins protects against experimental scorpion envenoming

In recent years, several molecular engineering methods of designing bispecific antibodies in various formats have been developed. Tandem-scFvs comprising two scFvs fused together via a peptide are 55-kDa molecules, and are one of the most promising and most straightforward approaches to bispecific antibody production. We report an attempt to design more effective antivenoms to the Androctonus australis scorpion using murine scFvs as building blocks to create a unique bispecific molecule that neutralizes the potent neurotoxins AahI and AahII. The tandem-scFv was produced in recombinant bacteria, purified by immobilized metal ion affinity chromatography, and analyzed by polyacrylamide gel electrophoresis, Western blot, gel filtration, mass spectrometry, and direct and competitive radioimmunoassay. In vivo, it neutralized the binding of the AahI and AahII toxins to their receptor, and protected mice against experimental envenomation. The findings reported here highlight the potential of recombinant antibody fragments for protecting against scorpion venom toxicity. Received 8 September 2006; received after revision 10 November 2006; accepted 27 November 2006     

Transgenic and mutant animal models to study mechanism of protection of red cell genetic defects against malaria

Malaria, caused by members of the genusPlasmodia, is still the most prevalent parasitic disease in the world. In an attempt to understand genetic factors conferring resistance to malaria, mouse models of thalassemia, sickle trait, and ankyrin and spectrin deficiency were studied during infection with species of malaria infectious to rodents. Although growth ofP. falciparum is not inhibited in thalassemic erythrocytes in culture, mice carrying a -thalassemia mutation were protected fromPlasmodium chabaudi adami, supporting epidemiologic findings. Transgenic mice expressing ^s hemoglobin were also significantly protected from two species of rodent malaria. Importantly, a significant role for the spleen in protection in the ^s transgenic mice was found. Finally, mice deficient in spectrin and ankyrin were studied with respect to their ability to support the growth of malaria. It was found that spectrin deficient mice were almost completely refractory toP. chabaudi adami andP. berghei. These models will allow further study of host factors in resistance to malaria.     

Immunopetentiators and the protection they give against carbon tetrachloride hepatotoxicity

Summary Immunopotentiators such as BCG, levamisole, PS-K and OK-432 prevent carbon tetrachloride (CCl₄) hepatotoxicity, and in spite of exposure to CCl₄ the liver tissue levels of thiobarbituric acid (TBA) reactive substances were not increased in rats pretreated with such immunopotentiators.     

The spectral sensitivity of the tail ofUrodacus,a scorpion

Zusammenfassung Die spektrale Empfindlichkeit des extraokularen Lichtsinnes des australischen SkorpionsUrodacus wurde bestimmt. Das Maximum liegt im Bereich von 480 nm. Die Einberechnung der Kutikulartransmission verändert die Form der Kurve, besonders im UV, aber das Intensitätsmaximum bleibt dasselbe.     

Dexamethasone protection against the acute lethality of ethanol in mice

Summary The administration of dexamethasone (DXM, 2.00 mg/kg) 1 h prior to the injection of lethal doses of ethanol was found to offer complete protection against ethanol toxicity at doses up to 5.25 g/kg and partial protection using higher doses. It is suggested that DXM central action might be involved in the protection against ethanol toxicity.Supported by a grant from U.S. National Aeronautics and Space Administration.     

Chemical protection of mouse spermatocytes against gamma-rays with 2-mercaptopropionylglycine

The radiosensitivity of primary spermatocytes in pachytene stage was estimated by counting the number of spermatids in the testes of control and MPG-treated mouse after exposure to 500, 1000 and 1500 R of Co60 gamma-rays. For this purpose, control and MPG-treated mice were killed 5 days after irradiation and countings of spermatids was made in stages I and II of the tubules. It has been observed that, although there was a death of primary spermatocytes in irradiated MPG-protected groups, quantitatively significant protection was afforded by this drug at all the 3 dose-levels studied.     

Chemical protection of mouse spermatocytes against gamma-rays with 2-mercaptopropionylglycine

Summary The radiosensitivity of primary spermatocytes in pachytene stage was estimated by counting the number of spermatids in the testes of control and MPG-treated mouse after exposure to 500, 1000 and 1500 R of Co⁶⁰ gammarays. For this purpose, control and MPG-treated mice were killed 5 days after irradiation and countings of spermatids was made in stages I and II of the tubules. It has been observed that, although there was a death of primary spermatocytes in irradiated MPG-protected groups, quantitatively significant protection was afforded by this drug at all the 3 dose-levels studied.     

Behavioural aspects of the extraocular light sense ofUrodacus,a scorpion

Zusammenfassung Nach Ausschaltung der Augen vermag der SkorpionUrodacus zwei Formen lichtabhängigen Verhaltens aufrechtzuerhalten (negative Phototaxis und Aktivitätsrhythmus). Dies geschieht mit Hilfe des bereits beschriebenen extraokulären Lichtsinnes.     

The maternal protection reaction against a mother's rejection of her own larva in Salamandra salamandra L]

In vitro experiments have shown that maternal spleen cells from Salamandra salamandra are cytotoxic to cells from their embryos. This reaction can be inhibited by maternal serum. In this paper, we show that maternal serum protection acts through two effects: by inactivating spleen cells and by protecting embryonic cells. The more numerous the embryos are in a female, the stronger the protection is. The effect of the maternal serum does not appear to be individual specific.     

Taxuspine D,a new taxane diterpene fromTaxus cuspidata with potent inhibitory activity against Ca2+-induced depolymerization of microtubules

A new taxane diterpenoid, taxuspine D (1), possessing an enolacetate moiety, has been isolated from stems of the Japanese yewTaxus cuspidata Sieb. et Zucc., and the structure elucidated on the basis of spectroscopic data. Taxuspine D (1) markedly inhibited Ca²⁺-induced depolymerization of microtubules.