Antigenic response to CT-P13 and infliximab originator in inflammatory bowel disease patients shows similar epitope recognition

AIM

To test the cross-immunogenicity of anti-CT-P13 IBD patients' sera to CT-P13/infliximab originator and the comparative antigenicity evoked by CT-P13/infliximab originator sera.

METHODS

Sera of patients with IBD with measurable anti-CT-P13 antibodies were tested for their cross-reactivity to 5 batches of infliximab originator and CT-P13. Anti-drug antibody positive sera from treated patients were used to compare antigenic epitopes.

RESULTS

All 42 anti-CT-P13 and 37 anti-infliximab originator IBD sera were cross-reactive with infliximab originator and CT-P13 respectively. Concentration of anti-drug antibodies against infliximab originator or CT-P13 were strongly correlated both for IgG1 and IgG4 (P < 0.001). Anti-CT-P13 sera of patients with IBD (n = 32) exerted similar functional inhibition on CT-P13 or infliximab originator TNF binding capacity and showed reduced binding to CT-P13 in the presence of five different batches of CT-P13 and infliximab originator. Anti-CT-P13 and anti-infliximab originator IBD sera selectively enriched phage-peptides from the VH (CDR1 and CDR3) and VL domains (CDR2 and CDR3) of infliximab. Sera reactivity detected major infliximab epitopes in these regions of infliximab in 60%-79% of patients, and no significant differences were identified between CT-P13 and infliximab originator immunogenic sera. Minor epitopes were localised in framework regions of infliximab with reduced antibody reactivity shown, in 30%-50% of patients. Monoclonal antibodies derived from naïve individuals and ADA-positive IBD patients treated with CT-P13 provided comparable epitope specificity to five different batches of CT-P13 and infliximab originator.

CONCLUSIONS

These results strongly support a similar antigenic profile for infliximab originator and CT-P13, and point toward a safe switching between the two drugs in anti-drug antibody negative patients.

Iron isotope fingerprints of redox and biogeochemical cycling in the soil-water-rice plant system of a paddy field

The iron isotope composition was used to investigate dissimilatory iron reduction (DIR) processes in an iron-rich waterlogged paddy soil, the iron uptake strategies of plants and its translocation in the different parts of the rice plant along its growth. Fe concentration and isotope composition (δ⁵⁶Fe) in irrigation water, precipitates from irrigation water, soil, pore water solution at different depths under the surface water, iron plaque on rice roots, rice roots, stems, leaves and grains were measured. Over the 8.5-10cm of the vertical profiles investigated, the iron pore water concentration (0.01 to 24.3mg·l^-1) and δ⁵⁶Fe (-0.80 to -3.40‰) varied over a large range. The significant linear co-variation between Ln[Fe] and δ⁵⁶Fe suggests an apparent Rayleigh-type behavior of the DIR processes. An average net fractionation factor between the pore water and the soil substrate of Δ⁵⁶Fe≈-1.15‰ was obtained, taking the average of all the δ⁵⁶Fe values weighted by the amount of Fe for each sample. These results provide a robust field study confirmation of the conceptual model of Crosby et al. (2005, 2007) for interpreting the iron isotope fractionation observed during DIR, established from a series of laboratories experiments. In addition, the strong enrichment of heavy Fe isotope measured in the root relative to the soil solution suggest that the iron uptake by roots is more likely supplied by iron from plaque and not from the plant-available iron in the pore water. Opposite to what was previously observed for plants following strategy II for iron uptake from soils, an iron isotope fractionation factor of -0.9‰ was found from the roots to the rice grains, pointing to isotope fractionation during rice plant growth. All these features highlight the insights iron isotope composition provides into the biogeochemical Fe cycling in the soil-water-rice plant systems studied in nature.

Modifying effect of prenatal care on the association between young maternal age and adverse birth outcomes

OBJECTIVES

The objectives were to investigate the prevalence of adverse birth outcomes according to maternal age range in the city of Rio de Janeiro, Brazil, in 2002, and to evaluate the association between maternal age range and adverse birth outcomes using additive interaction to determine whether adequate prenatal care can attenuate the harmful effect of young age on pregnancy outcomes.

METHODS

A cross-sectional analysis was performed in women up to 24 years of age who gave birth to live children in 2002 in the city of Rio de Janeiro. To evaluate adverse outcomes, the exposure variable was maternal age range, and the outcome variables were very preterm birth, low birth weight, prematurity, and low 5-minute Apgar score. The presence of interaction was investigated with the composite variable maternal age plus prenatal care. The proportions and respective 95% confidence intervals were calculated for adequate schooling, delivery in a public maternity hospital, and adequate prenatal care, and the outcomes according to maternal age range. The chi-square test was used. The association between age range and birth outcomes was evaluated with logistic models adjusted for schooling and type of hospital for each prenatal stratum and outcome. Attributable proportion was calculated in order to measure additive interaction.

RESULTS

Of the 40,111 live births in the sample, 1.9% corresponded to children of mothers from 10-14 years of age, 38% from 15-19 years, and 59.9% from 20-24 years. An association between maternal age and adverse outcomes was observed only in adolescent mothers with inadequate prenatal care, and significant additive interaction was observed between prenatal care and maternal age for all the outcomes.

CONCLUSION

Adolescent mothers and their newborns are exposed to greater risk of adverse outcomes when prenatal care fails to comply with current guidelines.

Rapid liquid chromatographic determination of dimetridazole and ipronidazole in swine feed

A simple and rapid method is described for the determination of dimetridazole (DMZ) and ipronidazole (IPR) in swine feeds at various levels (0.11-110 ppm). The drugs are released from feed by prewetting with a buffer, followed by extraction with either methanol or methylene chloride, depending on the drug level; if necessary, an acid-base cleanup is used before the liquid chromatographic analysis. The analytes are separated on a C18 column and monitored at 320 nm for detection and quantitation. Recoveries of DMZ from several feed formulations averaged 108% at the 92.8 ppm level with a standard deviation (SD) of 4.00% and a coefficient of variation (CV) of 3.70%, 101% at the 11.2 ppm level with an SD of 11.9% and a CV of 11.8%, and 100% at the 0.112 ppm level with an SD of 9.27% and a CV of 9.25%. Recoveries of IPR averaged 77.1% at the 12.9 ppm level with an SD of 1.75% and a CV of 2.27%; IPR recoveries averaged 35.2% at the 0.129 ppm level with an SD of 3.39% and a CV of 9.63%.