Rigorous Criteria for the Collapse of Nonlinear Cooperative Networks.

Many real-world complex systems, when hitting a tipping point, undergo irreversible sudden shifts that can eventually take a great toll on humanity and the natural world, such as ecosystem collapses, disease outbreaks, etc. Previous work has adopted approximations to predict the tipping points, but due to the nature of nonlinearity, this may lead to unexpected errors in predicting real-world systems. Here we obtain the rigorous bounds of the tipping points for general nonlinear cooperative networks. Our results offer two rigorous criteria that determine the collapse and survival of such a system. These two criteria are decided by the combined effect of dynamical parameters and interaction topology.

Analysis of serum homocysteine concentration in patients less than 35 years of age with polycystic ovary syndrome and hyperandrogenism.

OBJECTIVES: An increase in homocysteine (Hcy) concentration is closely related to polycystic ovary syndrome (PCOS). This study aimed to further explore serum homocysteine concentration and its influencing factors in clinically young (≤ 35 years) patients with PCOS and hyperandrogenism. MATERIAL AND METHODS: An electrochemical immunoassay was used to investigate the changes in serum homocysteine and related indexes in clinically young patients with PCOS and hyperandrogenism, and the results were statistically analyzed. RESULTS: Serum homocysteine concentration in clinically young patients with PCOS and hyperandrogenism (n = 208) was found to be significantly higher than in the control group (n = 663) (15.21 ± 9.99 vs. 12.56 ± 7.20 µmol/L, p < 0.0001), and the total testosterone concentration (1.65 ± 0.68 ng/mL) was higher in the PCOS group than in the control group (1.52 ± 0.58 ng/mL), p = 0.007. The receiver operating characteristic curve showed that the area under the curve of homocysteine in predicting PCOS was 0.606, and the 95% confidence interval (CI) was 0.563-0.650 (p < 0.001). The homocysteine concentrations of the two groups were graded, and it was found that the percentage of patients with homocysteine levels > 15 µmol/L was 26.92% in the PCOS group and 19.15% in the control group; the difference between the two groups was statistically significant (p = 0.0143). The serum homocysteine levels of the two groups were higher in obese patients than in non-obese patients (normal weight vs. overweight), and the difference in the control group was statistically significant. CONCLUSIONS: Serum homocysteine concentration in clinically young patients with PCOS and hyperandrogenism is elevated, so hyperhomocysteinemia can be used as one of the potential indicators of PCOS. In the process of the diagnosis and treatment of patients with PCOS, serum homocysteine concentration and body weight should both be considered.

Proteomic analysis of peach endocarp and mesocarp during early fruit development.

The development of the stone and formation of peach (Prunus persica) fruit were explored in this work using a proteomic approach. Sixty-eight proteins with different expression patterns were identified in both the endocarp and mesocarp during early fruit development (from 28 to 59 days after flowering) and the majority were involved in primary or secondary metabolism. In contrast to most proteins associated with primary metabolism in the endocarp, whose expression is down-regulated, expression of pyruvate dehydrogenase (PDH) unexpectedly increased exponentially. Moreover, its expression pattern was linearly positively correlated with the exponentially growing lignin content (R = 0.940), which suggests that PDH may play a role in endocarp lignification. Our data also revealed different spatiotemporal expressions of enzymes involved in the lignin and flavonoid pathways that provided proteome-level evidence to support the hypothesis that these two pathways are competitive during endocarp development. In addition, we observed endocarp-specific oxidative stress and propose that it may act as a stimulating factor in activating lignification and subsequent programmed cell death in the endocarp.

The Structural Features of α-Conotoxin Specifically Target Different Isoforms of Nicotinic Acetylcholine Receptors.

α-Conotoxins (α-Ctxs) are the major class of Ctxs extracted from the venom of marine cone snails. Most α-Ctxs specifically target various subtypes of the nicotinic acetylcholine receptors (nAChRs) with high affinity and potency as antagonists. Therefore, they may be used for the treatment of numerous diseases that nAChRs involved. The subtype affinity and selectivity of α-Ctxs arise from their amino acid composition and geometric conformation of microsites. To reveal the structural features of α-Ctxs, detailed structural information on the various nAChR subtypes and their ligand complexes is needed. This review article provides an overview of the structural data on α-Ctx-nAChR interactions to investigate the prediction and evaluation of the affinity and selectivity of α-Ctx.