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Graphical abstract Abstract Despite great advances in contemporary medicine, brain death still remains enigmatic and its cellular and molecular mechanisms unsettled. This review summarizes recent findings that substantiate the notion that PTEN/FLJ10540/PI3K/Akt cascade, the classical tumorigenic signaling pathway, is actively engaged in experimental brain stem death. These results were based on a clinically relevant animal model that employs the pesticide mevinphos as the experimental insult in Sprague-Dawley rats to mimic brain stem death in patients died of organophosphate poisoning. The neural substrate investigated is the rostral ventrolateral medulla (RVLM), a brain stem site classically known to maintain arterial pressure (AP) and is established to be the origin of a “life-and-death” signal detected from AP, which reflects brain stem cardiovascular dysregulation that precedes death. Activation of PI3K/Akt signaling pathway in the RVLM upregulates the nuclear factor-κB/nitric oxide synthase II/peroxynitrite cascade, resulting in impairment of brain stem cardiovascular regulation that leads to the loss of the “life-and-death” signal in experimental brain stem death. This process is reinforced by FLJ10540, a PI3K-association protein; and is counteracted by PTEN, a negative regulator of PI3K/Akt signaling. The concept that a classical signaling pathway in tumorigenesis is also an active player in cardiovascular dysregulation in brain stem death provides new ramifications for translational medicine. It promulgates the concept that rather than focusing on a particular disease condition, a new vista for future therapeutic strategy against both fatal eventualities should target at this common cellular cascade. [ABSTRACT FROM AUTHOR]

• Database contains of FRP retrofitted corroded columns was established. • Rotation angles of FRP retrofitted corroded columns at yielding and ultimate states are determined. • The prediction models for yield and ultimate rotation angles of FRP retrofitted corroded columns were developed. • Nonlinear modeling parameter a consistent with ASCE 41 for FRP-retrofitted corroded columns was determined. FRP retrofitting is an effective way to promote the degraded seismic capacity of reinforced concrete (RC) columns with corroded reinforcing bars. It is important to evaluate whether the performance of a corroded RC column meets the requirement of safety after FRP retrofitting. However, there is little available guidance for evaluating the deformation capacity of FRP retrofitted corroded columns. In this study, the test data of 63 FRP retrofitted corroded columns and 17 FRP retrofitted uncorroded columns under repeated cyclic loads are collected to establish a database. For each specimen, the rotation angles at yielding and ultimate states are determined from the backbone curve. The empirical prediction models are then developed for the yield and ultimate rotation angles of FRP retrofitted corroded columns, which include two parts: 1) the predicted rotation angle for the FRP retrofitted uncorroded RC column, and 2) a Corrosion Influence Factor (CIF) defined as the ratio between the rotation angles of the FRP retrofitted corroded columns to that of the FRP retrofitted uncorroded ones. The former part is represented using the available empirical prediction models, whereas the latter part is represented using the multi-linear relationships through stepwise regression with a backward elimination procedure. Through comparing with the experimental data, the developed empirical prediction models for the yield and ultimate rotation angles of FRP retrofitted corroded columns provide sufficient accuracy. Finally, the parameter " a " is determined in corresponding to different target probability of exceedance, which is required by the ASCE 41-compliant force versus displacement relation for FRP retrofitted corroded RC columns. [ABSTRACT FROM AUTHOR]

• A total of 29 corrosion damage models were collected to represent the corrosion induced deterioration mechanisms. • The variability in the available corrosion damage models was examined. • Seismic collapse fragility relationships were developed for the corroded RC frame structures with different corrosion damage models. • The effect of the variability in the corrosion damage models on the seismic collapse fragility of corroded RC frames was investigated. Corrosion of embedded reinforcement is an important form of degradation of reinforced concrete (RC) structures. The corrosion damage can degrade the mechanical behaviors of the corroded reinforcement, the surrounding concrete, and the interaction between them. These deterioration mechanisms can be simulated by different corrosion damage models. Different corrosion damage models could result in difference in the structural collapse capacity under earthquake excitations. However, the variability in these corrosion damage models and its effect on seismic collapse fragility of corroded RC structures are not well examined in the past studies. This study conducts an investigation of the variability in the available corrosion damage models. To do this, a total of 29 empirical models are collected to represent the corrosion-induced deterioration mechanisms. The results show that different corrosion damage models lead to significant variability. The changing range of the prediction by different corrosion damage models for the bond strength is even beyond three times wider than the minimum prediction value. As a further step, two typical RC frame structures are designed as the study cases. Then a suite of 19 corroded frame cases are modeled with their material parameters deteriorated according to the collected corrosion damage models. Their seismic collapse fragility curves are then generated and compared. It is found that, at a high corrosion rate of 0.2, the variability in the corrosion damage models can cause a significant difference in the collapse probability as high as 8.4% and 6.54% for the case frames designed with a low and high earthquake hazard levels, respectively. However, this effect due to the variability in the corrosion damage models is limited to the collapse probability when the structure is slightly or moderately corroded. Among the considered deterioration mechanism due to corrosion damage, the maximum difference of collapse probability are caused by the variability in the corrosion damage models for the yield strength and ultimate deformation of the corroded reinforcement, which are as high as 6.18% and 5.32%, respectively. While for the other deterioration mechanisms, the variability in their corresponding damage models leads to a limited effect on the collapse probability of structures. [ABSTRACT FROM AUTHOR]

• Cyclic loading tests were conducted for the ACE and ECE technologies corroded RC columns. • Appearance, corrosion crack, corrosion characteristics of corroded columns using ACE and ECE were compared. • The c orrosion products due to ACE and ECE were analyzed using X-ray diffraction. • Specimen's failure mode, hysteresis curve, backbone curve, and seismic performance indexes were compared. Corrosion of reinforcement bars can cause reinforced concrete (RC) columns more vulnerable under seismic loads. In this study, the seismic behavior of corroded RC columns was experimentally studied with a focus on the comparison between two different accelerated corrosion techniques by using artificial climate environment (ACE) and electrochemical chloride extraction (ECE). To do this, six RC square columns were designed and fabricated as the test specimens. The test specimens were categorized into two groups with a low level and a high level of axial compression ratio (i.e., 0.1 and 0.45), respectively, and each group includes three test specimens, i.e., an uncorroded column and two corroded columns under ACE and ECE techniques. An X-ray diffraction approach was used to examine the major ingredients of corrosion products attached on the corroded reinforcement bars under ACE and ECE techniques. The column specimens were subjected to repeated cyclic loadings, and the failure modes, hysteresis and backbone curves, stiffness degradation, ductility level and energy dissipation of the specimens corroded under different techniques were compared. The results show that, under a consistent target corrosion level, the ECE corrosion technique can cause more significant damage to the corroded RC columns than the ACE corrosion technique, leading to a change of failure mode and worse hysteretic performance. [ABSTRACT FROM AUTHOR]

• A phenomenological hysteretic model for corroded RC columns was developed. • The parameters of the phenomenological hysteretic model were calibrated based on test data. • Empirical prediction equations were generated for the parameters of the developed hysteretic model. A phenomenological hysteretic model is developed for corroded RC columns in this study. To this end, the test data of 77 corroded rectangular RC columns and 26 uncorroded ones under repeated cyclic loads are collected to establish a database. A polygonal hysteretic model that can well incorporate the degradation of stiffness and strength is adopted to describe the hysteretic behavior of corroded columns. The hysteretic model parameters related to monotonic backbone (i.e., yield moment M y , yield rotation θ y , pre-capping rotation θ p , post-capping rotation θ pc , the ratio of capping moment to yield moment k) and cyclic deterioration (i.e., cyclic deterioration parameter λ) are identified for each of the test specimens in the database after a careful calculation with the experimental data. The backbone parameters identified for the corroded columns are compared to those for the uncorroded columns to quantify the corrosion-induced deterioration coefficients (CIDCs). Multivariate-linear-type empirical relationships are then developed to relate each of the CIDCs to the corrosion rate and critical structural design variables using stepwise regression analysis. A multilinear empirical relationship is also proposed for the cyclic deterioration parameter. The developed hysteretic model together with the predictive equations for the model parameters are proved of high accuracy through simulating the intra-database tests considering varying corrosion levels. They are further applied to the corroded columns beyond the database, those without data on uncorroded counterparts provided in particular, also indicating a desirable accuracy. [ABSTRACT FROM AUTHOR]

DJ-1 (also known as PARK7) is a redox-active protein that protects against oxidative stress. This study evaluated the hypothesis that DJ-1 sustains brainstem cardiovascular regulation via maintaining mitochondrial function in the rostral ventrolateral medulla (RVLM), a brainstem site known to maintain blood pressure and sympathetic vasomotor tone, during cardiovascular depression elicited by the organophosphate insecticide mevinphos. In Sprague–Dawley rats, intravenous administration of mevinphos (640 μg kg−1) resulted in progressive hypotension, accompanied by an increase (Phase I) followed by a decrease (Phase II) of an experimental index for spontaneous baroreflex-mediated sympathetic vasomotor tone, alongside elevation in mitochondrial superoxide levels in the RVLM. There was concurrent activation of DJ-1 induced by oxidative stress in the RVLM, which was causally and temporally related to translocation of DJ-1 to mitochondria, reduction in mitochondrial membrane potential, increase in cytosolic apoptosis-inducing factor level, and apoptotic cell death in this brainstem site. Loss-of-function by immunoneutralization of DJ-1 in the RVLM significantly exacerbated those biochemical and cellular events, enhanced the progressive hypotension, diminished the increased and augmented the decreased spontaneous baroreflex-mediated sympathetic vasomotor tone respectively during Phases I and II, and heightened lethality during mevinphos intoxication. We conclude that DJ-1 in the RVLM sustains brainstem cardiovascular regulation induced by mevinphos via maintaining mitochondrial function. • Oxidative stress underlies cardiovascular dysregulation in mevinphos intoxication. • Oxidative stress also causes activation of DJ-1. • DJ-1 translocates to mitochondria and maintains mitochondrial membrane potential. • DJ-1 sustains cardiovascular regulation via maintaining mitochondrial function. [ABSTRACT FROM AUTHOR]