Early vs. non-early intervention in acute migraine-'Act when Mild (AwM)'. A double-blind, placebo-controlled trial of almotriptan.

The study was designed to compare the response to almotriptan in migraine patients who take medication early in the course of the attack with that when medication is taken after pain has become moderate or severe. A randomized, four-arm, multicentre, multinational, double-blind, placebo-controlled trial of almotriptan (12.5 mg) comparing treatment administration when pain intensity was mild and within 1 h of headache onset vs. pain that had become moderate or severe was conducted. Of 491 migraineurs enrolled, 403 were evaluable [intention-to-treat population (ITT)]. Their mean age was 38 years, 84% were female and they had a mean of 3.7 attacks/month. Of these patients, 10% did not take medication according to their randomly allocated basal pain intensity (mild or moderate/severe) and were subsequently reassigned to that group for this analysis-'Act when Mild (AwM)' group. In the almotriptan arms, 53% of mild basal pain and 38% of moderate/severe basal pain patients were pain free at 2 h (P = 0.03; primary end-point). Corresponding proportions in the placebo groups were 25% and 17% (statistically significant vs. respective almotriptan arms). Secondary end-points (ITT) were also significantly in favour of early intervention with almotriptan, both between and across treatment groups, such as sustained pain free: 45.6% vs. 30.5% (P = 0.02). Adverse events were reported in < 5% of treated patients in all groups (NS), with no serious events. Treatment with almotriptan while migraine pain is still mild provides statistically significant and clinically relevant enhancements in efficacy compared with treatment when pain has reached higher severity levels.

Binding of ferric enterobactin by the Escherichia coli periplasmic protein FepB.

The periplasmic protein FepB of Escherichia coli is a component of the ferric enterobactin transport system. We overexpressed and purified the binding protein 23-fold from periplasmic extracts by ammonium sulfate precipitation and chromatographic methods, with a yield of 20%, to a final specific activity of 15,500 pmol of ferric enterobactin bound/mg. Periplasmic fluid from cells overexpressing the binding protein adsorbed catecholate ferric siderophores with high affinity: in a gel filtration chromatography assay the K(d) of the ferric enterobactin-FepB binding reaction was approximately 135 nM. Intrinsic fluorescence measurements of binding by the purified protein, which were more accurate, showed higher affinity for both ferric enterobactin (K(d) = 30 nM) and ferric enantioenterobactin (K(d) = 15 nM), the left-handed stereoisomer of the natural E. coli siderophore. Purified FepB also adsorbed the apo-siderophore, enterobactin, with comparable affinity (K(d) = 60 nM) but did not bind ferric agrobactin. Polyclonal rabbit antisera and mouse monoclonal antibodies raised against nearly homogeneous preparations of FepB specifically recognized it in solid-phase immunoassays. These sera enabled the measurement of the FepB concentration in vivo when expressed from the chromosome (4,000 copies/cell) or from multicopy plasmids (>100,000 copies/cell). Overexpression of the binding protein did not enhance the overall affinity or rate of ferric enterobactin transport, supporting the conclusion that the rate-limiting step of ferric siderophore uptake through the cell envelope is passage through the outer membrane.

Bordetella pertussis filamentous hemagglutinin enhances the immunogenicity of liposome-delivered antigen administered intranasally.

In an attempt to increase the immunogenicity of mucosally delivered antigens, we incorporated the Bordetella pertussis filamentous hemagglutinin (FHA) adhesin into liposomes containing the glutathione S-transferase of Schistosoma mansoni (Sm28GST) as a model antigen. Outbred mice immunized twice intranasally with liposomes containing a constant suboptimal dose of Sm28GST and increasing doses of FHA produced anti-Sm28GST antibodies in a FHA dose-dependent manner. The addition of 3 microg of FHA to the liposomes induced more than 10-fold-higher anti-Sm28GST antibody titers, compared to those induced by liposomes without FHA. The presence of FHA did not alter the nature of the humoral immune response, and the sera contained anti-Sm28GST immunoglobulin G1 (IgG1), IgG2a, and IgG2b. However, anti-Sm28GST IgA was only detected when at least 3 microg of FHA was added to the preparation. These results show a promising potential for FHA to enhance the immunogenicity of mucosally administered antigens incorporated into liposomes.

Intradermal immunization of rats with plasmid DNA encoding Schistosoma mansoni 28 kDa glutathione S-transferase.

Direct administration of plasmid DNA encoding an antigen represents an attractive approach to vaccination against infectious diseases, particularly in developing countries where easy-to-handle and cost-effective vaccines are needed. We have investigated the potential of DNA immunization to induce a specific antibody response against Schistosoma mansoni, using plasmid-DNA encoding the protective antigen, S. mansoni 28 kDa glutathione S-transferase (Sm28GST). Since S. mansoni parasite penetrates into its host through the skin, this tissue was chosen for plasmid DNA delivery. Following plasmid DNA administration into the skin of rats, the parasite antigen was detected in skin cells by immunohistochemistry. Three administrations of 200 micrograms plasmid at 14 day intervals led to the induction of a long-lasting specific IgG antibody response in the sera of immunized rats, with a predominance of IgG2a and IgG2b subclasses. Sera of immunized animals were able to mediate antibody-dependent cellular cytotoxicity in vitro, leading to the specific killing of parasite larvae. A parasite challenge performed on plasmid DNA-immunized animals induced a strong and rapid boosting effect on the specific IgG antibody response. These results demonstrate the potential of genetic immunization via the skin with plasmid DNA encoding Sm28GST for inducing immune responses with protective patterns against an S. mansoni infection.

Mucosal vaccination against schistosomiasis using liposome-associated Sm 28 kDa glutathione S-transferase.

A variety of experimental models have shown that immunization using the glutathione S-transferase from Schistosoma mansoni (Sm28GST) can induce protective immunity against this parasite. This immunity has been related to the production of Th2 type antibodies against the antigen in both mice and humans. The work presented in this paper describes the development of a mucosal immunization protocol using liposomes which is designed to promote production of specific antibodies of isotypes related to a Th2 immune response. The liposomes were multilamellar and composed of various synthetic phospholipid mixtures. The liposome vector was used to convey the Sm28GST antigen to gut associated lymphoid tissue. The association of the Sm28GST antigen with liposomes containing different lipid mixtures was initially studied. The degree of interaction of the antigen was found to increase with the hydrocarbon chain length of the lipids used. It was demonstrated that the protein was present on both the inner and the outer membranes of the liposome vesicles. It was also shown that the major epitopes of Sm28GST were accessible to specific antibodies, confirming a conservation of its main antigenic features. Additionally, enzymatic activity of the protein/liposome complex was also demonstrated, indicating a conservation of the tertiary structure of the protein. An optimal Sm28GST/ liposome complex was established and administered orally to mice. This treatment resulted in both a mucosal and systemic immune response to the antigen Sm28GST. This was demonstrated by the detection of specific IgA in gut washes and specific IgG1, IgG2b in sera. Immunization by Sm28GST/liposome complex followed by challenge with parasite showed that Sm28GST given orally in these conditions bore protective activity. This last result opens the possibility of mucosal vaccination against schistosomiasis.

Influence of phospholipid composition on antibody responses to liposome encapsulated protein and peptide antigens.

The effect of phospholipid composition on mouse IgG antibody responses to liposomal bovine serum albumin (BSA), murine monoclonal antibody GK1.5 (anti-CD4) or a 21 amino acid peptide from the second conserved domain of HIV gp120 after s.c. administration, and on the IgA, IgE, and IgG antibody response to liposomal Shistosoma mansoni glutathione-S-transferase (Sm28GST) after oral administration, was determined. Antibody responses were compared with alum-adsorbed and N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP)-antigen mixtures. For the s.c. route, dipalmitoylphosphatidylcholine (DPPC)/dimyristoylphosphatidylglycerol (DMPG) liposomes induced 54-60% IgG1 and 35-44% IgG(2a+2b). DPPC/dipalmitoylphosphatidylethanolamine (DPPE) liposomes induced 73-78% IgG1 and 15-25% IgG(2a+2b). DPPC/ phosphatidylserine (PS) liposomes induced 86-89% IgG1 and 8-12% IgG(2a+2b). Alum and MDP induced 79-91% IgG1 and 4-17% IgG(2a+2b). The rank order of adjuvanticity for induction of IgG antibody was DPPC/DMPGDPPC/PE > > alum > > MDPDPPC/PS for all three antigens. DPPC/DMPG liposomes were the only effective adjuvant for the induction of secretory IgA and circulatory IgE and IgG antibodies against Sm28GST after oral administration. The failure of liposome-antigen mixtures to elicit an antibody response showed that liposomal incorporation of the antigens was obligatory for adjuvant activity. These results demonstrate that the correlation between phospholipid composition and adjuvanticity is independent of liposome charge, antigen, or route of administration.

Computation of drug concentrations in endocardial vegetations in patients during antibiotic therapy.

The treatment of endocarditis often requires prolonged antibiotic therapy. Individualized drug dosage regimens have made such therapy possible even in patients with impaired renal function. However, the problem of efficacy remains. Especially for aminoglycosides, it would be a useful guide to have at least an approximate idea of the concentration of an antibiotic within an endocardial vegetation. This study was designed to develop software to model the drug concentrations at different layers within spherical vegetations to provide a guide during clinical therapy of patients with endocarditis. A general model describing the diffusion of antibiotics in spheres has now been developed and interfaced with the USC*PACK PC Clinical Programs in order to compute and plot concentrations, within the vegetation, based on the regimen given to the patient and the diffusitivity of the antibiotic into the vegetation. Some preliminary results of this research, which are still in progress, are presented. Diffusion into simulated spherical vegetations has been computed for different treatment regimens for endocarditis: amikacin or netilmicin and vancomycin were given to three elderly patients (3 women, 74, 75 and 92 years old, with initial estimated creatinine clearances of 51, 36, and 31 ml/min/1.73 m2, respectively). Although Amikacin has a low diffusivity, the concentrations, even in the center of the vegetation, appear to be effective. The effects of various regimens, including a 'once-a-day' aminoglycoside regimen, are presented.