The Helix aspersa (brown garden snail) allergen repertoire

BACKGROUND: Ingestion of snails can induce strong asthmatic or anaphylactic responses, mainly in house-dust-mite-sensitized patients. The aim of this study was to identify the Helix aspersa (Hel a), Theba pisana (The p) and Otala lactea (Ota l) allergens and the extent of their cross-reactivity with the Dermatophagoides pteronyssinus (Der p) mite. PATIENTS AND METHODS: In 60 atopic patients, skin prick tests (SPT) to snail and D. pteronyssinus, total and specific IgE, specific IgE immunoblots, RAST and immunoblot inhibition assays were performed. RESULTS: Mean total IgE was >1,000 kU/l. Mean specific IgE (class 6 for Der p and class 2 for Hel a) SPT were positive in 44 patients for snail and in 56 for mite. Isoelectric focusing (IEF) and SDS-PAGE followed by immunoblotting of H. aspersa extract enabled the identification of 27 and 20 allergens, respectively. Myosin heavy chains from snails (molecular weight >208 kDa) disclosed two major allergens. Hel a and Der p RAST were strongly inhibited by their homologous extracts, with Hel a RAST being inhibited by the Der p extract to a much greater extent (72.6%) than the inverse (5.6%). A complete inhibition of the immunoblots by their homologous extract was obtained. However, Hel a extract did not inhibit Der p IEF separated recognition. On the other hand, mite extract extensively inhibited snail immunoblots from both IEF and SDS-PAGE separations. Immune detection on chicken, pig, rabbit, cow and horse myosins did not reveal any IgE cross recognition with snail. CONCLUSIONS: In most cases of snail allergy, mite appeared to be the sensitizing agent. Nevertheless, snails may also be able to induce sensitization by themselves. This hypothesis is supported by the finding of specific IgE to Hel a in 2 patients who did not show specific IgE to Der p, and one of them was suffering from asthma after snail ingestion.     

T cell subpopulations in myocardial inflammatory infiltrates detected by confocal microscopy: dose dependence in mice treated with cyclophosphamide during acute Trypanosoma cruzi infection

In this article, we have characterized cell subpopulations found in the hearts of mice presenting acute Chagas' disease by immunocytochemistry and subjected to different schedules of an immunosuppressive therapy with cyclophosphamide (CY). In this comparative study, CY treatment with different doses was carried out before or after infection with Trypanosoma cruzi Y strain trypomastigotes, enabling us to discriminate the parasitemic kinetics and inflammatory processes in the heart, 12 d after infection. Animals treated with 200 mg/kg of CY 2 d before infection presented high parasitaemia as well as heavy inflammation and low parasite loads in the heart. Mice treated 5 d after infection with the same dose, developed the same parasitaemic peak but were not able to control it. Their heart did not present inflammation, but a high number of parasites could be seen. Animals treated with five 3 mg/kg doses of CY every other day presented heavy inflammatory reaction and low parasitaemia. In this group, as well as the one treated before infection, immunocytochemistry studies have shown predominance of CD8(+) T cells in the myocardium. On the other hand, mice treated with 200 mg/kg of CY 5 d after infection, presented small amounts of CD4(+) T cells while no CD8(+) could be found. These results have confirmed the dose dependence influence of this drug on the T cell populations in the inflammatory infiltrates as well as the importance of the schedule employed.     

B-1 cells are pivotal for in vivo inflammatory giant cell formation

The mechanisms that govern giant cell (GC) formation in inflammatory, neoplastic and physiologic conditions are far from being understood. Here, we demonstrate that B-1 cells are essential for foreign-body GC formation in the mouse. GCs were analysed on the surface of glass cover slips implanted into the subcutaneous tissue of the animals. It was demonstrated that GCs are almost absent on cover slips implanted into the subcutaneous tissue of BALB/c or CBA/N X-linked immunodeficient mice. As these animals do not have B-1 cells in the peritoneal cavity, they were reconstituted with B-1 cells obtained from cultures of adherent mouse peritoneal cells. Results showed that in B-1-reconstituted animals, the number of GCs on the implant surface surpassed the values obtained with preparations from wild animals. In animals selectively irradiated (pleural and peritoneal cavities) to deplete these cavities of B-1 cells, GCs were also not formed. Enriched suspensions of B-1 cells grown in culture were labelled with [(3)H]-tymidine and injected into the peritoneal cavity of naive mice before implantation of glass cover slips. After 4 days, about 17% of mononuclear cells had their nuclei labelled, and almost 70% of GCs had one or more of their nuclei labelled when analysed by histoautoradiographic technique. A few GCs expressed an immunoglobulin M when analysed by immunostaining and confocal microscopy. Overall, these data demonstrate that B-1 cells are pivotal in the mechanisms of foreign-body GC formation in the mouse.     

Antibodies to staphylococcal enterotoxins and toxic shock syndrome toxin 1 in sera of patients and healthy people in Rio de Janeiro, Brazil.

Sera from 33 persons with staphylococcal infections and from 37 healthy persons were surveyed for the presence of antibody to staphylococcal enterotoxins A, B, C, D, and E and toxic shock syndrome toxin 1. Thirty-one (93.9%) of the patients and 35 (94.6%) of the control group had antibodies to one or more of the enterotoxins. The numbers of patients with antibody to the enterotoxins were as follows: A, 8; B, 9; C, 7; D, 17; E, 21; and toxic shock syndrome toxin 1, 11. The numbers of healthy individuals with antibody to the enterotoxins were as follows: A, 6; B, 12; C, 8; D, 27; E, 21; and toxic shock syndrome toxin 1, 9.     

Trypanosoma cruzi histone H1 is phosphorylated in a typical cyclin dependent kinase site accordingly to the cell cycle

Histone H1 of most eukaryotes is phosphorylated during the cell cycle progression and seems to play a role in the regulation of chromatin structure, affecting replication and chromosome condensation. In trypanosomatids, histone H1 lacks the globular domain and is shorter when compared with the histone of other eukaryotes. We have previously shown that in Trypanosoma cruzi, the agent of Chagas' disease, histone H1 is phosphorylated and this increases its dissociation from chromatin. Here, we demonstrate using mass spectrometry analysis that T. cruzi histone H1 is only phosphorylated at the serine 12 in the sequence SPKK, a typical cyclin-dependent kinase site. We also found a correlation between the phosphorylation state of histone H1 and the cell cycle. Hydroxyurea and lactacystin, which, respectively, arrest parasites at the G1/S and G2/M stages of the cell cycle, increased the level of histone H1 phosphorylation. Cyclin-dependent kinase-related enzymes TzCRK3, and less intensely the TzCRK1 were able to phosphorylate histone H1 in vitro. Histone H1 dephosphorylation was prevented by treating the parasites with okadaic acid but not with calyculin A. These findings suggest that T. cruzi histone H1 phosphorylation is promoted by cyclin dependent kinases, present during S through G2 phase of the cell cycle, and its dephosphorylation is promoted by specific phosphatases.     

Heterogeneity of brainstem blood flow response to hypoxia in the anesthetized rat

Cerebral blood flow is strictly regulated during hypoxic stress. Because of the preponderant role of the brainstem in cardiorespiratory controls, blood flow response to hypoxia is stronger in this region than in the cortex. However, the brainstem is made up of various regions which differ in their responsiveness to chemical stimuli. The objective of this study was to evaluate the distribution of blood flow during hypoxia using microsphere deposition methods in three brainstem regions containing key structures in cardiorespiratory controls: the nucleus tractus solitarus (NTS), the ventral respiratory groups (VRG) and the pontine respiratory groups (PRG). Microsphere injections were made during normoxia (FIO2=0.21) and after 15 min of hypoxia (FIO2=0.21). Based on this index, blood flow increase during hypoxia was higher in the VRG than in the dorsal part of the brainstem, containing the NTS and the PRG (P=0.002, n=10). These results suggest that blood flow response to hypoxia favours O(2) delivery in brainstem regions involved in respiratory rhythm generation.     

Monitoring and assessment indicators in 2001 of "Roll Back Malaria" initiative in Benin

Within the context of WHO/CDS/RBM/2000, a survey was conducted in 2001 by the National Malaria Control Program of Benin. Following a well-thought-out choice, the survey took place simultaneously in health areas corresponding to epidemiological regions. Morbidity due to malaria is very high among children under five years admitted in external clinic (44.3% of cases) and (46.5%) for hospitalization. The crude rate of mortality is 129%. The use of non-impregnated bednet is usually met in three health areas, where 47.4% of the household have at least one non-impregnated bednet versus 5.4% of household with impregnated bednets. Percentage of pregnant women sleeping under an impregnated bednet and following chemoprophylaxis is respectively 43.3% and 3.8%. Results obtained at the end of this database survey in 2001 have facilitated the definition of indicators of the process, results and impact which remain very useful for the implementation of the monitoring and assessment system of "Roll Back Malaria" in Benin.