Cross-species analysis of Fc engineered anti-Lewis-Y human IgG1 variants in human neonatal receptor transgenic mice reveal importance of S254 and Y436 in binding human neonatal Fc receptor

IgG has a long half-life through engagement of its Fc region with the neonatal Fc receptor (FcRn). The FcRn binding site on IgG1 has been shown to contain I253 and H310 in the CH2 domain and H435 in the CH3 domain. Altering the half-life of IgG has been pursued with the aim to prolong or reduce the half-life of therapeutic IgGs. More recent studies have shown that IgGs bind differently to mouse and human FcRn. In this study we characterize a set of hu3S193 IgG1 variants with mutations in the FcRn binding site. A double mutation in the binding site is necessary to abrogate binding to murine FcRn, whereas a single mutation in the FcRn binding site is sufficient to no longer detect binding to human FcRn and create hu3S193 IgG1 variants with a half-life similar to previously studied hu3S193 F(ab')₂ (t_1/2β, I253A, 12.23 h; H310A, 12.94; H435A, 12.57; F(ab')₂, 12.6 h). Alanine substitutions in S254 in the CH2 domain and Y436 in the CH3 domain showed reduced binding in vitro to human FcRn and reduced elimination half-lives in huFcRn transgenic mice (t_1/2β, S254A, 37.43 h; Y436A, 39.53 h; wild-type, 83.15 h). These variants had minimal effect on half-life in BALB/c nu/nu mice (t_1/2β, S254A, 119.9 h; Y436A, 162.1 h; wild-type, 163.1 h). These results provide insight into the interaction of human Fc by human FcRn, and are important for antibody-based therapeutics with optimal pharmacokinetics for payload strategies used in the clinic.     

Simultaneous determination of lamotrigine and its glucuronide and methylated metabolites in human plasma by automated sequential trace enrichment of dialysates and gradient high-performance liquid chromatography

The use of the system, automated sequential trace enrichment of dialysates (ASTED), to prepare plasma samples for the estimation of lamotrigine, its glucuronide and methylated metabolites in plasma prior to gradient high-performance liquid chromatography (HPLC) is described. Using this technique the procedure was observed to be specific for all three compounds and linear over the range 0.04 to 10 μg/ml for lamotrigine and the glucuronide metabolite and 2 to 500 ng/ml for the methylated metabolite. The within-run precision (C.V.) at four different supplemented plasma lamotrigine concentrations of 0.04, 0.10, 2.5 and 10.0 μg/ml was 6.21, 5.17, 1.29 and 0.73%, respectively, and the between-run precision (C.V.) estimated to be 13.49, 6.08, 1.95 and 1.78%, respectively. The overall accuracy (% bias) of the procedure was estimated to be 12.50, 0.00, 2.80 and 1.80%, respectively. The glucuronide and methylated metabolites in plasma showed similar assay performance.     

Fern spore and pollen airspora profile of Singapore

Monitoring atmospheric fern spore and pollen loads in Singapore was initiated in June 1990. Aside from the more numerous fungal spores, fern spores and pollen grains made up 6.2–8.6% and 4.4–5.4% of the total airspora sampled, respectively. The most frequently encountered fern spores, in descending order, were those of Nephrolepis auriculata, Dicranopteris linearis, Stenochlaena palustris, Asplenium nidus, Pteridium aquilinum, and Dicranopteris curranii. For pollen grains, the most frequently encountered, in descending order, were Elaeis guineensis, Casuarina equisetifolia, Acacia auriculiformis, Kyllingia polyphylla, Podocarpus, and Poaceae pollen grains. Seasonal patterns for individual fern spore or pollen types were discernible despite the relatively uniform tropical climate in Singapore. The fern spore and pollen calendar for the period 1991–1995 was compared to that of 2005–2006 as a follow-up study to keep abreast with the rapidly changing landscape of Singapore. Diurnal patterns showing a late morning to afternoon peak period were seen in fern spores, while the peak period was in the morning for pollen types studied with the exception to oil palm pollen. Additionally, association between fern spore and pollen counts and local meteorological conditions were also analyzed and found to be highly correlated. This study has thus identified the fern spores and pollen airspora components, and determined the calendars, as well as diurnal profiles of the Singapore airspora and provides invaluable information for allergy studies by highlighting the trigger sources present in the environment.     

Phylogenetic analysis of different breeds of domestic chickens in selected area of Peninsular Malaysia inferred from partial cytochrome b gene information and RAPD markers

The present investigation was carried out in an attempt to study the phylogenetic analysis of different breeds of domestic chickens in Peninsular Malaysia inferred from partial cytochrome b gene information and random amplified polymorphic DNA (RAPD) markers. Phylogenetic analysis using both neighbor-joining (NJ) and maximum parsimony (MP) methods produced three clusters that encompassed Type-I village chickens, the red jungle fowl subspecies and the Japanese Chunky broilers. The phylogenetic analysis also revealed that majority of the Malaysian commercial chickens were randomly assembled with the Type-II village chickens. In RAPD assay, phylogenetic analysis using neighbor-joining produced six clusters that were completely distinguished based on the locality of chickens. High levels of genetic variations were observed among the village chickens, the commercial broilers, and between the commercial broilers and layer chickens. In this study, it was found that Type-I village chickens could be distinguished from the commercial chickens and Type-II village chickens at the position of the 27th nucleotide of the 351?bp cytochrome b gene. This study also revealed that RAPD markers were unable to differentiate the type of chickens, but it showed the effectiveness of RAPD in evaluating the genetic variation and the genetic relationships between chicken lines and populations.     

Comparison between effects of various partial inferior turbinectomy options on nasal airflow: a computer simulation study

Partial inferior turbinectomy is typically performed on patients suffering from chronic nasal obstruction due to hypertrophy of inferior turbinates and is refractory to other more conservative treatments. The effects of the various options of incision performed on the inferior turbinate in terms of the resulting nasal airflow pattern are examined using computational fluid mechanics. The pressure drops across the severely blocked nose and healthy nose models were found to be 32.3 and 12.3 Pa, respectively, whereas the pressure drops across the nasal cavity following one-third turbinate resection, total turbinate resection and front-end resection were obtained as 5.8, 6.1 and 30.5 Pa correspondingly. Based on the total pressure drop results, the one-third resection option seems to be better than the front-end surgery and the total turbinate resection.     

Association of Interleukin-13 SNP rs20541 (Arg > Gln) to allergic rhinitis in an Asian population of ethnic Chinese in Singapore

In this study, we report our findings as we evaluated the association of IL-13 SNP rs20541 to AR as reported in the meta-analysis (Ying, X-J et al., April, Gene 2013) in an Asian population of 1322 ethnic Chinese recruited in Singapore well defined and characterized for allergic rhinitis. The SNP was significantly associated with AR at an odds ratio of 1.57 for the homozygous genotype comparisons indicating a strong risk for AR. This highlights the importance of this mutation in Asian populations for risk towards allergic phenotypes and also warrants further functional work to characterize the mechanism behind this genetic predisposition.