Humoral immune responses in human infection with the whipworm Trichuris trichiura

The humoral immune response to infection with Trichuris trichirua was investigated by ELISA and immunoblotting using human sera from the Caribbean island of St Lucia. Immunoblot analysis of the degree of cross-reactivity with the related trichuroid Trichinella spiralis and with the other commonly co-existent nematodes, Ascaris lumbricoides and Toxocara canis, was carried out using selected sera. The IgM, IgA, IgE, and IgG subclass antibody levels were measured in ELISA using a detergent solubilized extract of adult T. trichiura. The IgG and IgE responses were highly Trichuris specific. Anti-T. trichiura IgM responses were totally cross-reactive with A. lumbricoides and were completely ablated by pre-incubation of sera with Ascaris antigen. The IgG response was predominantly of the IgG1 subclass with a minimal IgG3 response. Only 1 person out of 130 tested had a detectable IgG3 response. The IgG2 response appeared to be directed primarily against carbohydrate or polysaccharide antigens as pre-treatment of the ELISA plates with poly-L-lysine was necessary before a response could be detected. These data are the first demonstration of human isotypic responses to infection with T. trichiura.     

Role of sensory innervation and mast cells in neurogenic plasma protein exudation into the airway lumen

Abstract Neurogenic inflammation in the airways involves both mucosal oedema and plasma protein exudation into the airway lumen. We aimed to investigate the mechanism of exudation of plasma proteins into the airway lumen. Neurogenic inflammation was induced in anaesthetized Sprague-Dawley rats by electrical stimulation of both vagal nerves at 20 V, 10 Hz, 5 ms. Vascular permeability was measured as ¹²⁵I-albumin extravasation into both the airway wall and tracheobronchial lavage fluid. Following vagal stimulation, tracheobronchial lavages were analysed for albumin, total protein, histamine, immunoreactive substance P (SP), and immunoreactive calcitonin gene-related peptide (CGRP). Vagal stimulation rapidly increased vascular permeability in the airway mucosa and induced exudation of plasma proteins into the tracheobronchial fluid. Pretreatment with capsaicin inhibited both neurogenic vascular permeability and movement of albumin into the airway lumen. SP and CGRP were detectable in basal lavages (1.37 ± 0.12 ng/mL and 2.17 ± 0.21 ng/mL, respectively) and the concentration of SP fell by 43% following treatment with capsaicin. Following vagal stimulation, concentrations of both SP and CGRP decreased significantly. Although basal tracheobronchial lavages contained histamine, vagal stimulation did not increase the histamine concentration. These results indicate that both neurogenic vascular permeability and plasma protein exudation into the airway lumen results from activation of capsaicin-sensitive sensory nerves and the reaction is not associated with mast cell activation.     

Bioavailability of Phenytoin Following Oral Administration of Phenytoin-lipid Conjugates to Rats

The bioavailability of phenytoin was evaluated in rats upon oral administration of phenytoin-lipid conjugates obtained by covalent binding of 3-hydroxymethylphenytoin to 1,3-dimyristoylglyceride via a succinidyl linkage, to 2-(1,3-dimyristoyl-2-glyceryl)butyric acid and to 3-myristoyloxy-2-myristoyloxy-methylpropionic acid. Despite differences of the phenytoin plasma concentrations all three compounds approximately doubled the AUC compared with the dosing of phenytoin itself. The early onset and the long duration of the anticonvulsant activity after administration of the triglyceride-derived conjugate could be correlated to the increased phenytoin plasma levels. It is concluded that drug-lipid conjugates may be useful prodrugs for the oral delivery of poorly watersoluble drugs.     

Age-dependency of serum isotype responses and antigen recognition in human whipworm (Trichuris trichiura) infection

The present study examines the age-dependency of parasite-specific isotype responses and antigen recognition profiles of individuals within a Trichuris trichiura endemic community, in order to evaluate the significance of serum antibodies as determinants of observed age-related patterns of infection intensity. A high degree of individual heterogeneity is observed in isotype responses to separated T. trichiura antigens by Western blot. Recognition by IgG₁ antibodies exhibits marked age-dependency. The age-profiles of IgG₁ responses to selected antigens of 16–17 kDa and 90 kDa molecular weight reflect the age-related changes in current infection intensity at the population level. Similarly, mean age patterns of IgG₂ responses to a 90 kDa antigen, and mean IgG₄ responses to a 16–17 kDa antigen reflect mean infection levels. IgG₃ responses are negligible, and for methodological reasons, both IgE and IgM specificities are not presented. IgA responses to separated antigens of 16–17 kDa and 90 kDa, exhibit age-profiles which may suggest the development of an IgA-mediated acquired resistance to T. trichiura with age. IgA levels remain elevated throughout early adulthood, when infection intensity levels markedly decrease, supporting the hypothesis that IgA antibodies may be significant in generating the convex nature of the age-infection profile of T. trichiura.     

A method for simultaneous determination of plasma and erythrocyte antioxidant status. Evaluation of the antioxidant activity of vitamin E in healthy volunteers

1Since oxygen free radicals are directly involved in a variety of pathologies such as atherosclerosis, diabetes mellitus, inflammation and/or when a deficit of defences of the organism against radicals occurs, we developed a suitable and simple method to determine both the erythrocyte sensitivity to an oxidative stress and plasma antioxidant protective capacity. 2This test is based on the introduction at 37° C of a radical initiator, 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH), within an erythrocyte suspension leading to a membrane alteration and ultimately to haemolysis. The latter can be quantified by determining the lacticodeshydrogenase activity released in the medium. The erythrocyte sensitivity to haemolysis and the volume of plasma inhibiting 50% of the haemolysis were determined. 3Intra-assay CVs were 1.9 % for erythrocyte sensitivity to oxidative stress and 3.4% for inhibitory 50% plasma volume. Inter-assay CVs for both erythrocyte sensitivity and inhibitory 50% plasma volume were 4%. 4The reliability of this method was assessed and applied to test the protective effect of vitamin E, a well known antioxidant agent, in six healthy volunteers. Two weeks after daily administration of 500 mg of vitamin E, the mean plasma vitamin E concentration increased by 41% from 10.7±2.0 mg l⁻¹ before treatment (P<0.05). As the vitamin E concentration increased, the mean inhibitory 50% plasma volume and the percentage of haemolysed erythrocytes decreased respectively by 29% from 3.35±0.5 μl (P<0.05) and 18% from 71.5±3.8% (P<0.05). No significative variation of these parameters was observed in six adult men without vitamin E supplementation. 5Thus, this global and simple test permits an antioxidant status evaluation of a patient. It can be applied to various pathologies and allows the potency of new antioxidant molecules to be evaluated.