CVD diamond detector with interdigitated electrode pattern for time-of-flight energy-loss measurements of low-energy ion bunches.

Ion stopping experiments in plasma for beam energies of few hundred keV per nucleon are of great interest to benchmark the stopping-power models in the context of inertial confinement fusion and high-energy-density physics research. For this purpose, a specific ion detector on chemical-vapor-deposition diamond basis has been developed for precise time-of-flight measurements of the ion energy loss. The electrode structure is interdigitated for maximizing its sensitivity to low-energy ions, and it has a finger width of 100 µm and a spacing of 500 µm. A short single α-particle response is obtained, with signals as narrow as 700 ps at full width at half maximum. The detector has been tested with α-particle bunches at a 500 keV per nucleon energy, showing an excellent time-of-flight resolution down to 20 ps. In this way, beam energy resolutions from 0.4 keV to a few keV have been obtained in an experimental configuration using a 100 µg/cm2 thick carbon foil as an energy-loss target and a 2 m time-of-flight distance. This allows a highly precise beam energy measurement of δE/E ≈ 0.04%-0.2% and a resolution on the energy loss of 0.6%-2.5% for a fine testing of stopping-power models.

Antibody responses to Plasmodium falciparum sporozoite-, liver- and blood-stage synthetic peptides in migrant and autochthonous populations in malaria endemic areas.

This study evaluates the differences in host immune responses to defined plasmodial antigens in four geographically different regions in which malaria is endemic. Sera from 527 individuals were tested for the presence of antibodies specific for three types of plasmodial antigen: liver-stage antigen (LSA-1), blood-stage antigen (SPF 70) and circumsporozoite (CS) antigen (NANP)4. The individuals taking part in the study comprised: patients with transfusional malaria due to Plasmodium falciparum or P. vivax; non-immune migrants residing in an endemic area in Rondônia; Amazonian Indians from the states of Pará (Xingu PA) and Mato Grosso (Xingu MT); people living in a hyperendemic area in Africa (Burkina-Faso); and controls that had never been to a malaria endemic area. None of the transfusional sera displayed antibodies against sporozoite or to liver stage antigen, although 80% of the P. falciparum transfusional malaria sera contained IgG antibodies against the blood-stage peptide. A low percentage of Indians from Xingu PA and of non-immune migrants displayed antibodies against liver-stage (27% and 17%) and sporozoite (11% or d 12%) peptides, although a greater frequency of antibodies against blood-stage peptide (50% and 49%) was observed in both cases. Indians from Xingu MT exhibited a greater frequency of antibodies against liver, sporozoite and blood-stage peptides (45%, 50% and 58%). Only hyperimmune African individuals exhibited higher percentages of antibodies against liver- (64%) and blood-stage antigens (87%), contrasting with a low frequency of antibodies against the CS repeat (33%). Taken together, the present data confirm that Rondonian migrants and Indians from Xingu PA constitute populations with limited exposure and immunity to P. falciparum malaria infection and conversely, Xingu MT Indians and Africans have been more exposed to malaria infection. In conclusion this study indicates that the immune response to these malaria parasite peptides can be used to assess malaria transmission in epidemiological surveys.

Cross-reactions between idiotypes, Plasmodium falciparum derived peptides, dinitrophenyl and beta(2-->6) polyfructosan.

In this paper we seek evidence for the participation of the idiotype-anti-idiotype network in the polyclonal B-cell activation (PBA) associated to malaria. For this purpose we tested by an immunoradiometric assay a panel of nine monoclonal antibodies (including seven anti-idiotype antibodies) against three different (plasmodial or non plasmodial) heteroantigens: the 307 synthetic peptide (an epitope of a P. falciparum hepatic stage specific antigen) the (NANP)4 synthetic peptide (a repetitive epitope of the circumsporozoite protein of the P. falciparum sporozoite surface), and dinitrophenyl (DNP) molecule coupled to bovine serum albumin (BSA). Besides the anti-TNP-DNP antibody, the ABPC48 idiotype (directed against beta polyfructosan a fragment of levan molecule) and one anti-idiotype antibody reacted with DNP-BSA. Two other anti-idiotype antibodies (directed against idiotypes of antibodies specific of beta poly-fructosan and phosphorylcholine) were positive against the (NANP)4 antigen. Three antibodies reacted with the 307 antigen which was also recognized by the ABPC48. One of these antibodies was positive to both P. falciparum peptides tested. These preliminary results suggest the existence of crossreactions between plasmodial antigens and idiotypes of antibodies directed against other heterologous antigens. Thus, malaria induced cross-reactive antibodies could act as hetero and/or auto-antibodies explaining, at least partially, the malaria associated PBA phenomenon and modulating the specific immune response during the course of the infection.

Influenza vaccination in the elderly: improved antibody response with Imuthiol (Na diethyldithiocarbamate) adjuvant therapy.

To improve influenza vaccine efficacy in hospitalized elderly, we compared the evolution of antibody level after vaccination in three patient groups. A sample of apparently primo vaccinated elderly were randomized to receive either Imuthiol (Na diethyldithiocarbamate: group 1) or a placebo (group P). They were compared to patients who had been vaccinated annually for several years (group C). All patients were immunized in the same week. Antibody responses increase within 15 days to reach a plateau in group P and C, while they continue to increase in the Imuthiol treated group, reaching higher antibody levels 30 days after vaccination. This higher antibody rise in group I is essentially due to higher antibody responses in patients with initially low antibody levels and who exhibited at least a four-fold antibody rise. This effect of Imuthiol on influenza antibody responses was observed in spite of a lower nutritional status in this group, a condition that induces lower antibody responses. The higher antibody responses observed in the Imuthiol treated group allow longer protection against influenza.