Electrically-Evoked Frequency-Following Response (EFFR) in the Auditory Brainstem of Guinea Pigs

It is still a difficult clinical issue to decide whether a patient is a suitable candidate for a cochlear implant and to plan postoperative rehabilitation, especially for some special cases, such as auditory neuropathy. A partial solution to these problems is to preoperatively evaluate the functional integrity of the auditory neural pathways. For evaluating the strength of phase-locking of auditory neurons, which was not reflected in previous methods using electrically evoked auditory brainstem response (EABR), a new method for recording phase-locking related auditory responses to electrical stimulation, called the electrically evoked frequency-following response (EFFR), was developed and evaluated using guinea pigs. The main objective was to assess feasibility of the method by testing whether the recorded signals reflected auditory neural responses or artifacts. The results showed the following: 1) the recorded signals were evoked by neuron responses rather than by artifact; 2) responses evoked by periodic signals were significantly higher than those evoked by the white noise; 3) the latency of the responses fell in the expected range; 4) the responses decreased significantly after death of the guinea pigs; and 5) the responses decreased significantly when the animal was replaced by an electrical resistance. All of these results suggest the method was valid. Recording obtained using complex tones with a missing fundamental component and using pure tones with various frequencies were consistent with those obtained using acoustic stimulation in previous studies.     

Effects of SARA on Oxygen–Glucose Deprivation in PC12 Cell Line

Ischemic stroke is a major composition of cerebrovascular disease, seriously threatening to human health in the world. Activin A (ActA), belonging to transforming growth factor-beta (TGF-β) super family, plays an important role in the hypoxic-ischemic brain injury through ActA/Smads pathway. While as an essential phosphorylation assistor in TGF-β signaling, the functions and mechanisms of smad anchor for receptor activation (SARA) in ischemic brain injury remain poorly understood. To solve this problem and explore the pathological processes of ischemic stroke, we used an Oxygen–Glucose deprivation (OGD) model in nerve growth factor-induced differentiated rattus PC12 pheochromocytoma cells and down regulated the expressions of SARA by RNA interference technology. Our results showed that the repression of SARA before OGD exposure reduced the expressions of Smad2, 3, 4 mRNA and the phosphorylation rate of Smad2 protein, but it did not affect the mRNA expressions of Smad7. After OGD treatment, ActA/Smads pathway was activated and the expression of SARA in the SARA pre-repression group was significantly up-regulated. The pre-repression of SARA increased the sensitivities of nerve-like cells to OGD damage. Moreover, the mRNA expression of Smad7 which was supposed to participate in the negative feedback of ActA/Smads pathway was also elevated due to OGD injury. Taken together, these results suggest a positive role of SARA in assisting the phosphorylation of Smad2 and maintaining the neuron protective effect of ActA/Smads pathway.     

Fluid shear stress regulates HepG2 cell migration though time-dependent integrin signaling cascade

Hepatocellular carcinoma (HCC) is a subtype of malignant liver cancer with poor prognosis and limited treatment options. It is noteworthy that mechanical forces in tumor microenvironment play a pivotal role in mediating the behaviors and functions of tumor cells. As an instrumental type of mechanical forces in vivo, fluid shear stress (FSS) has been reported having potent physiologic and pathologic effects on cancer progression. However, the time-dependent mechanochemical transduction in HCC induced by FSS remains unclear. In this study, hepatocellular carcinoma HepG2 cells were exposed to 1.4 dyn/cm² FSS for transient duration (15s and 30s), short duration (5 min, 15 min and 30 min) and long duration (1h, 2h and 4h), respectively. The expression and translocation of Integrins induced FAK-Rho GTPases signaling events were examined. Our results showed that FSS endowed HepG2 cells with higher migration ability via reorganizing cellular F-actin and disrupting intercellular tight junctions. We further demonstrated that FSS regulated the expression and translocation of Integrins and their downstream signaling cascade in time-dependent patterns. The FSS downregulated focal adhesion components (Paxillin, Vinculin and Talin) while upregulated the expression of Rho GTPases (Cdc42, Rac1 and RhoA) in long durations. These results indicated that FSS enhanced tumor cell migration through Integrins-FAK-Rho GTPases signaling pathway in time-dependent manners. Our in vitro findings shed new light on the role of FSS acting in physiologic and pathological processes during tumor progression, which has emerged as a promising clinical strategy for liver carcinoma.     

α‐ketoglutarate delays age‐related fertility decline in mammals

The fecundity reduction with aging is referred as the reproductive aging which comes earlier than that of chronological aging. Since humans have postponed their childbearing age, to prolong the reproductive age becomes urgent agenda for reproductive biologists. In the current study, we examined the potential associations of α‐ketoglutarate (α‐KG) and reproductive aging in mammals including mice, swine, and humans. There is a clear tendency of reduced α‐KG level with aging in the follicle fluids of human. To explore the mechanisms, mice were selected as the convenient animal model. It is observed that a long term of α‐KG administration preserves the ovarian function, the quality and quantity of oocytes as well as the telomere maintaining system in mice. α‐KG suppresses ATP synthase and alterations of the energy metabolism trigger the nutritional sensors to down‐regulate mTOR pathway. These events not only benefit the general aging process but also maintain ovarian function and delay the reproductive decline. Considering the safety of the α‐KG as a naturally occurring molecule in energy metabolism, its utility in reproduction of large mammals including humans deserves further investigation.     

Yaks and sheep trigger different changes in the grasshopper assemblages of the Qilian Mountains via differentially altering plant assemblages

1. The Qilian Mountains represent one of the key livestock‐raising grasslands in China. The two main herbivore species raised in this area – yaks and sheep – are of critical economical value. Grasshoppers compete with these animals for available nutrients, creating multifaceted relationships between livestock, grasshoppers and plants. A clear understanding of such relationships is lacking and is urgently needed to guide conservation efforts. 2. This study aims to document the effects of yak and sheep grazing on grasshopper assemblages and to elucidate the underlying mechanisms of such effects. 3. It is shown here that yaks and sheep impact grasshopper assemblages differently. Grasshopper assemblages exhibited lower density, biodiversity, richness, and evenness of distribution in yak‐grazed pastures than in grazing‐free grasslands. Sheep‐grazed pastures exhibited a dramatically divergent picture, with elevated density, biodiversity and richness, and a slightly decreased evenness of distribution. Grasshoppers were generally larger in grazed pastures than in grazing‐free grasslands, especially in yak‐grazed plots. 4. The present study suggests that differences between yak and sheep pastures in plant assemblage structure and plant traits are probably the underlying forces driving the differences in grasshopper assemblage structure and grasshopper traits, respectively. 5. The study shows that the grasshopper habitat indicator species differ between yak and sheep pastures, raising the possibility that such indicators can be used to monitor grassland usage and degradation in the Qilian Mountains. 6. These results provide novel insights into the dynamic interactions of common domesticated herbivore species, grasshoppers and plants in Qilian Mountains, which augment current knowledge and may ultimately lead to better conservation practices.     

Binding of B‐cell maturation antigen to B‐cell activating factor induces survival of multiple myeloma cells by activating Akt and JNK signaling pathways

B‐cell maturation antigen (BCMA) is expressed on normal and malignant plasma cells and represents a potential target for therapeutic intervention. In this study, we characterized the mechanism underlying the protein kinase B (Akt) and c‐Jun N‐terminal kinase (JNK) pathways and BCMA interactions in regulating multiple myeloma (MM) cell survival. It was found that the expression levels of B cell‐activating factor (BAFF) and BCMA were increased in MM cells as compared with those in normal controls. The proliferation of U266 cells was induced by recombinant human BAFF (rhBAFF) and could also be decreased by BCMA siRNA. The expression of Bcl‐2 protein was up‐regulated, and Bax protein was down‐regulated after rhBAFF treatment, which could be reversed by BCMA siRNA. Similarly, the protein p‐JNK and p‐Akt were activated by rhBAFF and could be changed by BCMA siRNA. In addition, the BCMA mRNA and protein expression levels were decreased after treatment with Akt and JNK pathway inhibitors. These results suggest that Akt and JNK pathways are involved in the regulation of BCMA. A novel BAFF/BCMA signalling pathway in MM may be a new therapeutic target for MM. Copyright © 2016 John Wiley & Sons, Ltd.     

A Mathematical Framework for Combining Decisions of Multiple Experts toward Accurate and Remote Diagnosis of Malaria Using Tele-Microscopy

We propose a methodology for digitally fusing diagnostic decisions made by multiple medical experts in order to improve accuracy of diagnosis. Toward this goal, we report an experimental study involving nine experts, where each one was given more than 8,000 digital microscopic images of individual human red blood cells and asked to identify malaria infected cells. The results of this experiment reveal that even highly trained medical experts are not always self-consistent in their diagnostic decisions and that there exists a fair level of disagreement among experts, even for binary decisions (i.e., infected vs. uninfected). To tackle this general medical diagnosis problem, we propose a probabilistic algorithm to fuse the decisions made by trained medical experts to robustly achieve higher levels of accuracy when compared to individual experts making such decisions. By modelling the decisions of experts as a three component mixture model and solving for the underlying parameters using the Expectation Maximisation algorithm, we demonstrate the efficacy of our approach which significantly improves the overall diagnostic accuracy of malaria infected cells. Additionally, we present a mathematical framework for performing ‘slide-level’ diagnosis by using individual ‘cell-level’ diagnosis data, shedding more light on the statistical rules that should govern the routine practice in examination of e.g., thin blood smear samples. This framework could be generalized for various other tele-pathology needs, and can be used by trained experts within an efficient tele-medicine platform.     

Motor-Substrate Interactions in Mycoplasma Motility Explains Non-Arrhenius Temperature Dependence

Mycoplasmas exhibit a novel, substrate-dependent gliding motility that is driven by ∼400 “leg” proteins. The legs interact with the substrate and transmit the forces generated by an assembly of ATPase motors. The velocity of the cell increases linearly by nearly 10-fold over a narrow temperature range of 10-40°C. This corresponds to an Arrhenius factor that decreases from ∼45 k_BT at 10°C to ∼10 k_BT at 40°C. On the other hand, load-velocity curves at different temperatures extrapolate to nearly the same stall force, suggesting a temperature-insensitive force-generation mechanism near stall. In this article, we propose a leg-substrate interaction mechanism that explains the intriguing temperature sensitivity of this motility. The large Arrhenius factor at low temperature comes about from the addition of many smaller energy barriers arising from many substrate-binding sites at the distal end of the leg protein. The Arrhenius dependence attenuates at high temperature due to two factors: 1), the reduced effective multiplicity of energy barriers intrinsic to the multiple-site binding mechanism; and 2), the temperature-sensitive weakly facilitated leg release that curtails the power stroke. The model suggests an explanation for the similar steep, sub-Arrhenius temperature-velocity curves observed in many molecular motors, such as kinesin and myosin, wherein the temperature behavior is dominated not by the catalytic biochemistry, but by the motor-substrate interaction.     

Analysis of a common inheritable idiotype in IgA-deficient sera using monoclonal antibodies

In these studies we describe the production of three mAb raised to an idiotype on an IgG anticasein antibody isolated from the serum of one IgA-deficient blood donor. These are IgM kappa and block the binding of casein Ag to anticasein antibody. Sera of unrelated IgA-deficient donors were tested for the presence of the idiotype; 15 of 56 IgA-deficient sera (25%) contain the anticasein idiotype, whereas 1 of 45 normal sera was positive. Anticasein antibodies as a whole were predominantly of the IgG1 and IgG3 subclass; idiotype-positive anticaseins are predominantly of the IgG1 subclass. For IgA-deficient donors, the relative amount of idiotype-positive anticasein antibody was correlated with the level of anticasein present in the serum. Studies were done to investigate the potential inheritance of the idiotype in families; in three of four families the idiotype was inherited in an apparent autosomal dominant pattern. Our data show that a common cross-reactive idiotype can be detected in the sera of IgA-deficient individuals and their family members. This suggests that V region markers may be conserved in this humoral immunodeficiency disease.     

Predicting Metabolic Pathways of Small Molecules and Enzymes Based on Interaction Information of Chemicals and Proteins

Metabolic pathway analysis, one of the most important fields in biochemistry, is pivotal to understanding the maintenance and modulation of the functions of an organism. Good comprehension of metabolic pathways is critical to understanding the mechanisms of some fundamental biological processes. Given a small molecule or an enzyme, how may one identify the metabolic pathways in which it may participate? Answering such a question is a first important step in understanding a metabolic pathway system. By utilizing the information provided by chemical-chemical interactions, chemical-protein interactions, and protein-protein interactions, a novel method was proposed by which to allocate small molecules and enzymes to 11 major classes of metabolic pathways. A benchmark dataset consisting of 3,348 small molecules and 654 enzymes of yeast was constructed to test the method. It was observed that the first order prediction accuracy evaluated by the jackknife test was 79.56% in identifying the small molecules and enzymes in a benchmark dataset. Our method may become a useful vehicle in predicting the metabolic pathways of small molecules and enzymes, providing a basis for some further analysis of the pathway systems.