Altered Hippocampal-Prefrontal Neural Dynamics in Mouse Models of Down Syndrome

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Nearest Neighbor Classification Rule for Mixtures of Discrete and Continuous Random Variables

In this paper very simple nonparametric classification rule for mixtures of discrete and continuous random variables is described. It is based on the method of nearest neighbor proposed by Cover and Hart (1967). The bounds on the limit of the nearest neighbor rule risks are given. Both lower and upper bound depend on the Bayes risk and the loss function. Finally the method is compared with other existing methods on some practical data set.     

A Cross-linking Mass Spectrometry Approach Defines Protein Interactions in Yeast Mitochondria

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Highlights

• •XL-MS reveals new PPIs in yeast mitochondria under glycerol and glucose condition.
• •Significant but limited results from quantitative XL-MS experiments.
• •Ndi1 participates in a CIII₂CIV₂ respiratory supercomplex.
• •Min8 promotes assembly of Cox12 into an intermediate complex IV.

     

An active balance board system with real-time control of stiffness and time-delay to assess mechanisms of postural stability

Increased time-delay in the neuromuscular system caused by neurological disorders, concussions, or advancing age is an important factor contributing to balance loss (Chagdes et al., 2013, 2016a,b). We present the design and fabrication of an active balance board system that allows for a systematic study of stiffness and time-delay induced instabilities in standing posture. Although current commercial balance boards allow for variable stiffness, they do not allow for manipulation of time-delay. Having two controllable parameters can more accurately determine the cause of balance deficiencies, and allows us to induce instabilities even in healthy populations. An inverted pendulum model of human posture on such an active balance board predicts that reduced board rotational stiffness destabilizes upright posture through board tipping, and limit cycle oscillations about the upright position emerge as feedback time-delay is increased. We validate these two mechanisms of instability on the designed balance board, showing that rotational stiffness and board time-delay induced the predicted postural instabilities in healthy, young adults. Although current commercial balance boards utilize control of rotational stiffness, real-time control of both stiffness and time-delay on an active balance board is a novel and innovative manipulation to reveal balance deficiencies and potentially improve individualized balance training by targeting multiple dimensions contributing to standing balance.     

Mitochondrial Oxidative Phosphorylation Complex Regulates NLRP3 Inflammasome Activation and Predicts Patient Survival in Nasopharyngeal Carcinoma

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Highlights

• •Flow cytometry analysis is used to isolate ASC speck⁽⁺⁾ NPC cells.
• •Proteome analysis of ASC speck⁽⁺⁾ NPC cells reveals enriched mitochondrial OxPhos proteins.
• •OxPhos proteins mediate NLRP3 inflammasome activation through mtROS.
• •OxPhos proteins, NDUFB8 and ATP5B are correlated with NPC local recurrence.

     

Evolutionary assembly of cooperating cell types in an animal chemical defense system

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Relationship between postabsorptive respiratory exchange ratio and plasma free fatty acid concentrations

The relationship between overnight postabsorptive (fasting) respiratory exchange ratio (RER) and plasma FFA concentrations was addressed using data from three separate protocols, each of which involved careful control of the antecedent diet. Protocol 1 examined the relationship between fasting RER and the previous daytime RER. In Protocol 2 fasting, RER and plasma palmitate concentrations were measured in 29 women and 31 men (body mass index <30 kg·m⁻²). Protocol 3 analyzed data from Nielsen et al. (Nielsen, S., Z. K. Guo, J. B. Albu, S. Klein, P. C. O''Brien, M. D. Jensen. 2003. Energy expenditure, sex and endogenous fuel availability in humans. J. Clin. Invest. 111: 981-988.) to understand how fasting RER and palmitate concentrations relate within individuals during four consecutive measurements. The results were as follows: 1) Fasting RER was correlated (r = 0.74, P < 0.001) with the previous day''s average RER, and less so with RER variability. 2) Fasting RER was correlated (r = −0.39, P = 0.007) with fasting plasma palmitate concentrations. 3) The pattern of the RER/palmitate relationship was similar within individuals and between individuals; a negative slope was observed significantly more often than a positive slope (χ² test; P < 0.001). Our findings suggest that, despite a fixed food quotient, the slight departures from energy equilibrium in a controlled General Clinical Research Center environment can effect plasma FFA concentrations. We suggest that including indirect calorimetry as part of FFA metabolism studies may aid in data interpretation.     

N-糖蛋白去糖基化酶（PNGase）的研究进展

N-糖蛋白去糖基化酶（PNGase）是一种广泛存在于真菌、植物、哺乳动物中的去糖基化酶，可以水解N-糖蛋白或 N-糖肽上天冬酰胺与寡糖链连接的化学键，并释放出完整的N-寡糖。PNGase在生物体内参与蛋白质降解、器官发育、个体生长等过程。人PNGase基因功能缺陷会导致先天性去糖基化障碍，小鼠PNGase缺陷会导致胚胎致死性，线虫PNGase缺陷使其寿命下降。本文对PNGase在不同物种的分布、蛋白质结构、酶学功能及生物学功能进行阐述，为PNGase的生理病理功能及致病机制的基础研究提供思路，为PNGase作为糖生物学工具酶或药物开发的创新应用研究奠定基础。     

Climate change and seasonal reproduction in mammals

Seasonal reproduction is common among mammals at all latitudes, even in the deep tropics. This paper (i) discusses the neuroendocrine pathways via which foraging conditions and predictive cues such as photoperiod enforce seasonality, (ii) considers the kinds of seasonal challenges mammals actually face in natural habitats, and (iii) uses the information thus generated to suggest how seasonal reproduction might be influenced by global climate change. Food availability and ambient temperature determine energy balance, and variation in energy balance is the ultimate cause of seasonal breeding in all mammals and the proximate cause in many. Photoperiodic cueing is common among long-lived mammals from the highest latitudes down to the mid-tropics. It is much less common in shorter lived mammals at all latitudes. An unknown predictive cue triggers reproduction in some desert and dry grassland species when it rains. The available information suggests that as our climate changes the small rodents of the world may adapt rather easily but the longer lived mammals whose reproduction is regulated by photoperiod may not do so well. A major gap in our knowledge concerns the tropics; that is where most species live and where we have the least understanding of how reproduction is regulated by environmental factors.     

Sex differences in leg dexterity are not present in elite athletes

We studied whether the time-varying forces that control unstable foot–ground interactions provide insight into the neural control of dynamic leg function. Twenty elite (10 F, 26.4 ± 3.5 yrs) and 20 recreational (10 F, 24.8 ± 2.4 yrs) athletes used an isolated leg to maximally compress a slender spring designed to buckle at low forces while seated. The foot forces during the compression at the edge of instability quantify the maximal sensorimotor ability to control dynamic foot–ground interactions. Using the nonlinear analysis technique of attractor reconstruction, we characterized the spatial (interquartile range IQR) and geometric (trajectory length TL, volume V, and sum of edge lengths SE) features of the dynamical behavior of those force time series. ANOVA confirmed the already published effect of sex, and a new effect of athletic ability, respectively, in TL (p = 0.014 and p < 0.001), IQR (p = 0.008 and p < 0.001), V (p = 0.034 and p = 0.002), and SE (p = 0.033 and p < 0.001). Further analysis revealed that, for recreational athletes, females exhibited weaker corrective actions and greater stochasticity than males as per their greater mean values of TL (p = 0.003), IQR (p = 0.018), V (p = 0.017), and SE (p = 0.025). Importantly, sex differences disappeared in elite athletes. These results provide an empirical link between sex, athletic ability, and nonlinear dynamical control. This is a first step in understanding the sensorimotor mechanisms for control of unstable foot–ground interactions. Given that females suffer a greater incidence of non-contact knee ligament injuries, these non-invasive and practical metrics of leg dexterity may be both indicators of athletic ability, and predictors of risk of injury.