Lack of replication of higher genetic risk load in men than in women with systemic lupus erythematosus

Introduction

We aimed to replicate a recent study which showed higher genetic risk load at 15 loci in men than in women with systemic lupus erythematosus (SLE). This difference was very significant, and it was interpreted as indicating that men require more genetic susceptibility than women to develop SLE.

Methods

Nineteen SLE-associated loci (thirteen of which are shared with the previous study) were analyzed in 1,457 SLE patients and 1,728 healthy controls of European ancestry. Genetic risk load was calculated as sex-specific sum genetic risk scores (GRS_s).

Results

Our results did not replicate those of the previous study at either the level of individual loci or the global level of GRS_s. GRS_s were larger in women than in men (4.20 ± 1.07 in women vs. 3.27 ± 0.98 in men). This very significant difference (P < 10⁻¹⁶) was more dependent on the six new loci not included in the previous study (59% of the difference) than on the thirteen loci that are shared (the remaining 41%). However, the 13 shared loci also showed a higher genetic risk load in women than in men in our study (P = 6.6 × 10⁻⁷), suggesting that heterogeneity of participants, in addition to different loci, contributed to the opposite results.

Conclusion

Our results show the lack of a clear trend toward higher genetic risk in one of the sexes for the analyzed SLE loci. They also highlight several limitations of assessments of genetic risk load, including the possibility of ascertainment bias with loci discovered in studies that have included mainly women.     

Challenges and Opportunities to Use Biowaivers to Compare Generics in China

Biowaivers for class I drugs according to the biopharmaceutics classification system (BCS) were first introduced in 2000. The in vitro equivalence can be used to document bioequivalence between products. This study compared the in vitro dissolution behavior of two BCS class I drugs, amoxicillin and metronidazole, which are sold in China. Identifying a reference product on the Chinese domestic market was impossible. Three 250-mg and two 500-mg amoxicillin capsules and four metronidazole tablet products were tested. None of the amoxicillin products and three of the four metronidazole tablets were found to be equivalent to each other when the same strengths were compared. The bioequivalence of products that fail the in vitro test can be established via in vivo clinical studies which are expensive and time consuming. Establishing nationally or globally accepted reference products may provide regulatory agencies with an efficient mechanism approving high quality generics.     

Systematic Regional Variations in Purkinje Cell Spiking Patterns

In contrast to the uniform anatomy of the cerebellar cortex, molecular and physiological studies indicate that significant differences exist between cortical regions, suggesting that the spiking activity of Purkinje cells (PCs) in different regions could also show distinct characteristics. To investigate this possibility we obtained extracellular recordings from PCs in different zebrin bands in crus IIa and vermis lobules VIII and IX in anesthetized rats in order to compare PC firing characteristics between zebrin positive (Z+) and negative (Z−) bands. In addition, we analyzed recordings from PCs in the A2 and C1 zones of several lobules in the posterior lobe, which largely contain Z+ and Z− PCs, respectively. In both datasets significant differences in simple spike (SS) activity were observed between cortical regions. Specifically, Z− and C1 PCs had higher SS firing rates than Z+ and A2 PCs, respectively. The irregularity of SS firing (as assessed by measures of interspike interval distribution) was greater in Z+ bands in both absolute and relative terms. The results regarding systematic variations in complex spike (CS) activity were less consistent, suggesting that while real differences can exist, they may be sensitive to other factors than the cortical location of the PC. However, differences in the interactions between SSs and CSs, including the post-CS pause in SSs and post-pause modulation of SSs, were also consistently observed between bands. Similar, though less strong trends were observed in the zonal recordings. These systematic variations in spontaneous firing characteristics of PCs between zebrin bands in vivo, raises the possibility that fundamental differences in information encoding exist between cerebellar cortical regions.     

Ran localizes around the microtubule spindle in vivo during mitosis in Drosophila embryos

The GTPase Ran regulates multiple cellular functions throughout the cell cycle, including nucleocytoplasmic transport, nuclear membrane assembly, and spindle assembly. Ran mediates spindle assembly by affecting multiple spindle assembly pathways: microtubule dynamics, microtubule motor activity, and spindle pole assembly. Ran is predicted to facilitate spindle assembly by remaining in the GTP-bound state around the chromatin in mitosis. Here, we directly test the central tenet of this hypothesis in vivo by determining the cellular localization of Ran pathway components in Drosophila embryos. We find that, during mitosis, RCC1, the nucleotide exchange factor for Ran, is associated with chromatin, while Ran and RanL43E, an allele locked in the GTP-bound state, localize around the spindle. In contrast, nuclear proteins redistribute throughout the embryo upon nuclear envelope breakdown (NEB). Thus, in vivo RanGTP has the correct spatial localization within the cell to modulate spindle assembly.     

Growth and proteomic analysis of tomato fruit under partial root-zone drying

The effects of partial root-zone drying (PRD) on tomato fruit growth and proteome in the pericarp of cultivar Ailsa Craig were investigated. The PRD treatment was 70% of water applied to fully irrigated (FI) plants. PRD reduced the fruit number and slightly increased the fruit diameter, whereas the total fruit fresh weight (FW) and dry weight (DW) per plant did not change. Although the growth rate was higher in FI than in PRD fruits, the longer period of cell expansion resulted in bigger PRD fruits. Proteins were extracted from pericarp tissue at two fruit growth stages (15 and 30 days post-anthesis [dpa]), and submitted to proteomic analysis including two-dimensional gel electrophoresis and mass spectrometry for identification. Proteins related to carbon and amino acid metabolism indicated that slower metabolic flux in PRD fruits may be the cause of a slower growth rate compared to FI fruits. The increase in expression of the proteins related to cell wall, energy, and stress defense could allow PRD fruits to increase the duration of fruit growth compared to FI fruits. Upregulation of some of the antioxidative enzymes during the cell expansion phase of PRD fruits appears to be related to their role in protecting fruits against the mild stress induced by PRD.     

Reversibly shielded DNA polyplexes based on bioreducible PDMAEMA-SS-PEG-SS-PDMAEMA triblock copolymers mediate markedly enhanced nonviral gene transfection

Reversibly shielded DNA polyplexes based on bioreducible poly(dimethylaminoethyl methacrylate)-SS-poly(ethylene glycol)-SS-poly(dimethylaminoethyl methacrylate) (PDMAEMA-SS-PEG-SS-PDMAEMA) triblock copolymers were designed, prepared and investigated for in vitro gene transfection. Two PDMAEMA-SS-PEG-SS-PDMAEMA copolymers with controlled compositions, 6.6-6-6.6 and 13-6-13 kDa, were obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization of dimethylaminoethyl methacrylate (DMAEMA) using CPADN-SS-PEG-SS-CPADN (CPADN: 4-cyanopentanoic acid dithionaphthalenoate; PEG: 6 kDa) as a macro-RAFT agent. Like their nonreducible PDMAEMA-PEG-PDMAEMA analogues, PDMAEMA-SS-PEG-SS-PDMAEMA triblock copolymers could effectively condense DNA into small particles with average diameters less than 120 nm and close to neutral zeta potentials (0 ～ +6 mV) at and above an N/P ratio of 3/1. The resulting polyplexes showed excellent colloidal stability against 150 mM NaCl, which contrasts with polyplexes of 20 kDa PDMAEMA homopolymer. In the presence of 10 mM dithiothreitol (DTT), however, polyplexes of PDMAEMA-SS-PEG-SS-PDMAEMA were rapidly deshielded and unpacked, as revealed by significant increase of positive surface charges as well as increase of particle sizes to over 1000 nm. Release of DNA in response to 10 mM DTT was further confirmed by gel retardation assays. These polyplexes, either stably or reversibly shielded, revealed a low cytotoxicity (over 80% cell viability) at and below an N/P ratio of 12/1. Notably, in vitro transfection studies showed that reversibly shielded polyplexes afforded up to 28 times higher transfection efficacy as compared to stably shielded control under otherwise the same conditions. Confocal laser scanning microscope (CLSM) studies revealed that reversibly shielded polyplexes efficiently delivered and released pDNA into the perinuclei region as well as nuclei of COS-7 cells. Hence, reduction-sensitive reversibly shielded DNA polyplexes based on PDMAEMA-SS-PEG-SS-PDMAEMA are highly promising for nonviral gene transfection.     

Differences in metabolomic profiles of male db/db and s/s, leptin receptor mutant mice

Leptin, a protein hormone secreted by adipose tissue, plays an important role in regulating energy metabolism and the immune response. Despite similar extremes of adiposity, mutant mouse models, db/db, carrying spontaneous deletion of the active form of the leptin receptor (LEPR-B) intracellular signaling domain, and the s/s, carrying a specific point mutation leading to a dysfunctional LEPR-B-STAT3 signaling pathway, have been shown to have robust differences in glucose homeostasis. This suggests specific effects of leptin, mediated by non-STAT3 LEPR-B pathways. Differences in the LEPR-B signaling pathways in these two LEPR-B mutant mice models are expected to lead to differences in metabolism. In the current study, the hypothesized differences in metabolism were investigated using the metabolomics approach. Proton nuclear magnetic resonance spectroscopy ((1)HNMR) was conducted on 24 h urine samples in deuterium oxide using a 500 MHz instrument at 25°C. Principle Component Analysis showed clear separation of urine NMR spectra between the groups (P < 0.05). The CHENOMX metabolite database was used to identify several metabolites that differed between the two mouse models. Significant differences (P < 0.05) in metabolites associated with the glycine, serine, and homocysteine metabolism were observed. The results demonstrate that the metabolomic profile of db/db and s/s mice are fundamentally different and provide insight into the unique metabolic effects of leptin exerted through non-STAT3 LEPR-B pathways.     

Egg cell signaling by the secreted peptide ZmEAL1 controls antipodal cell fate

Unlike in animals, female gametes of flowering plants are not the direct products of meiosis but develop from a functional megaspore after three rounds of free mitotic divisions. After nuclei migration and positioning, the eight-nucleate syncytium differentiates into the embryo sac, which contains two female gametes as well as accessory cells at the micropylar and chalazal pole, respectively. We report that an egg-cell-specific gene, ZmEAL1, is activated at the micropylar pole of the eight-nucleate syncytium. ZmEAL1 translation is restricted to the egg cell, resulting in the generation of peptide-containing vesicles directed toward its chalazal pole. RNAi knockdown studies show that ZmEAL1 is required for robust expression of the proliferation-regulatory gene IG1 at the chalazal pole of the embryo sac in antipodal cells. We further show that ZmEAL1 is required to prevent antipodal cells from adopting central cell fate. These findings show how egg cells orchestrate differentiation of the embryo sac.