Expression of the Plasmodium berghei ookinete protein Pbs21 in a baculovirus-insect cell system produces an efficient transmission blocking immunogen

A surface protein of Plasmodium berghei ookinetes, Pbs21, was expressed in a baculovirus-insect cell system in cell culture and in Heliothis virescens larvae. Groups of BALB/c mice received two intraperitoneal inoculations of either i) Tris-buffer or homogenized H. virescens larvae infected with wild-type baculovirus; ii) enriched, homogenized ookinetes, or Hi) homogenizedH. virescens larvae expressing recombinant Pbs21 (rPbs21). All animals immunized with ookinetes or with rPbs21 had high litres of antibodies (IgG isotype) that bound to native Pbs21. The large majority of antibodies in immune sera of both groups recognized the antigen under non-reducing but not under reducing conditions. The predominant IgG-sub-classes in mice immunized with ookinetes was IgGl and in mice immunized with rPbs21, the subclasses were IgGl and IgG2a. Immunization with rPbs21 reduced the infec-tivity of P. berghei to mosquitoes by 91% compared to a 99% reduction following immunization with ookinetes. This preliminary data indicate that rPbs21 expressed in this eukaryotic system induces a transmission-blocking immunity which is more effective than that achieved using rPbsll expressed in Escherichia coli (Matsuoka et al. 1994).     

Synthesis of phosphotyrosine-containing peptides by the solid-phase method

A practical and convenient procedure for making phosphotyrosine-containing peptides by the solid-phase method was developed. Phosphotyrosine was incorporated via Boc-Tyr(PO₃Bzl₂)-OH. The completed peptide was cleaved from the solid support by treatment with 1 M TMSBr-thioanisole-TFA. By gel-phase ³¹P-NMR spectroscopy we found that one of the benzyl protecting groups on phosphate was completely removed by two consecutive runs of Boc deprotection with 50% TFA-DCM. However, the other benzyl group remained intact throughout the synthesis (35 cycles).     

Use of a super active luteinizing hormone releasing hormone (LHRH) agonist in the treatment of menorrhagia

Summary. A luteinizing hormone releasing hormone agonist, d-Ser(But)⁶des Gly¹⁰-LHRH ethylamide, was administered intranasally to four women with unexplained ovulatory menorrhagia. Dramatic reductions in excessive menstrual blood losses were induced without significant side-effects, although the pattern of loss returned to pretreatment levels within 2 months of ceasing therapy.     

Studies on the Nature of the Circulating Anticoagulant Directed against Antihemophilic Factor: With Notes on an Assay for Antihemophilic Factor

Modification of the kaolin clotting time has produced a reliable, simple assaysystem for antihemophilic factor. This system has been utilized for an investigation of the nature and mode of action of the circulating anticoagulantdirected against antihemophilic factor.

The anticoagulant has been shown to be present in equal amounts in plasmaand serum, to be associated with fractions II and III of plasma prepared bythe method of Cohn, to be relatively heat stable and to be stable for prolonged periods at -20 C.

Investigation of the kinetics of the anticoagulant-antihemophilic reactionhas demonstrated its temperature, time, pH, and substrate concentration dependency. The anticoagulant is not inactivated during the reaction with antihemophilic factor, and there is a proportional relationship between the anticoagulant and the antihemophilic factor during their interaction.

No antigen-antibody manifestations could be detected during the anticoagulant-antihemophilic factor reaction. These characteristics support thehypothesis that the inactivation of antihemophilic factor by specific circulatinganticoagulants is enzymatic.

Submitted on February 19, 1962 Accepted on April 6, 1962