The Effects of Extremely Low-Frequency Magnetic Fields on Reproductive Function in Rodents

Extremely low-frequency electromagnetic fields (ELF-EMF) are defined as those having frequencies up to 300 Hz, representing a non-ionising radiation having photon energy too weak to interact with biomolecular systems. Exposure to low-frequency electric field and magnetic field (MF) generally results in negligible energy absorption in the body. However, it is well established that ELF-MF induces biologic effects in various cellular functions. ELF-MF acting as a co-inducer can potentiate weak mutagenic signalling. The concern about possible adverse effects on human health of long-term exposure to ELF-MFs, especially at frequencies of 50 or 60 Hz generated from power lines and electric devices, has been increasing. Conversely, long-term effects of chronic exposure have been excluded from the scope of the guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) because of insufficient consistent scientific evidence to fix the thresholds for such possible biological effects. The results regarding the adverse effects of ELF-MF on human or animal reproductive functions are contradictory or inconclusive. Overall conclusion of epidemiologic studies on ambient residential MF exposure consistently failed to establish a link between human adverse reproductive outcomes and chronic maternal or paternal exposure to low-frequency MFs. In animal studies, there is no compelling evidence for a causal relationship between disturbed prenatal development and ELF-MF exposure. Testicular spermatogenesis progresses through a complexly regulated cellular process involving mitosis and meiosis; this process seems to be vulnerable to external stressors, such as heat, MF exposure or chemical and physical agents. Exposure to ELF-MF did significant risk impaired implantation or the foetal development in animal studies. However, there is some consistency in the increase of minor skeletal alterations in animal experiments. The evidence derived from recent studies in male mice demonstrates that ELF-MF exposure is involved with an increase in the frequency of apoptosis in spermatogenic cells. Those results suggest that exposure to MF is related to possible cytogenetic effects on testicular germ cells and therefore may negatively affect reproduction. This chapter intends to present an overview on the effects of ELF-EMF exposure on the reproductive function and a plausible mechanism in rodent species

Clinical Evaluation of Rapid Diagnostic Test Kit Using the Polysaccharide as a Genus-Specific Diagnostic Antigen for Leptospirosis in Korea, Bulgaria, and Argentina

Leptospirosis, a zoonotic disease that is caused by many serovars which are more than 200 in the world, is an emerging worldwide disease. Accurate and rapid diagnostic tests for leptospirosis are a critical step to diagnose the disease. There are some commercial kits available for diagnosis of leptospirosis, but the obscurity of a species- or genus-specific antigen of pathogenic Leptospira interrogans causes the reduced sensitivity and specificity. In this study, the polysaccharide derived from lipopolysaccharide (LPS) of nonpathogenic Leptospira biflexa serovar patoc was prepared, and the antigenicity was confirmed by immunoblot and enzyme linked immunosorbent assay (ELISA). The performance of the rapid diagnostic test (RDT) kit using the polysaccharide as a diagnostic antigen was evaluated in Korea, Bulgaria and Argentina. The sensitivity was 93.9%, 100%, and 81.0% and the specificity was 97.9%, 100%, and 95.4% in Korea (which is a rare region occurring with 2 serovars mostly), Bulgaria (epidemic region with 3 serovars chiefly) and Argentina (endemic region with 19 serovars mainly) respectively. These results indicate that this RDT is applicable for global diagnosis of leptospirosis. This rapid and effective diagnosis will be helpful for diagnosis and manage of leptospirosis to use and the polysaccharide of Leptospira may be called as genus specific antigen for diagnosis

The Association of AMPK with ULK1 Regulates Autophagy

Autophagy is a highly orchestrated intracellular bulk degradation process that is activated by various environmental stresses. The serine/threonine kinase ULK1, like its yeast homologue Atg1, is a key initiator of autophagy that is negatively regulated by the mTOR kinase. However, the molecular mechanism that controls the inhibitory effect of mTOR on ULK1-mediated autophagy is not fully understood. Here we identified AMPK, a central energy sensor, as a new ULK1-binding partner. We found that AMPK binds to the PS domain of ULK1 and this interaction is required for ULK1-mediated autophagy. Interestingly, activation of AMPK by AICAR induces 14-3-3 binding to the AMPK-ULK1-mTORC1 complex, which coincides with raptor Ser792 phosphorylation and mTOR inactivation. Consistently, AICAR induces autophagy in TSC2-deficient cells expressing wild-type raptor but not the mutant raptor that lacks the AMPK phosphorylation sites (Ser722 and Ser792). Taken together, these results suggest that AMPK association with ULK1 plays an important role in autophagy induction, at least in part, by phosphorylation of raptor to lift the inhibitory effect of mTOR on the ULK1 autophagic complex

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Department of Mechanical Engineeringclos

AKT function and human oncogenesis

Accumulated evidence indicates that, by the phosphorylation of its physiological substrates, Akt promotes cell survival, proliferation and angiogenesis. While a number of Akt targets have been identified, the mechanism by which Akt regulates cell survival and growth and induces malignant transformation still remains elusive. During the last 5 years, I have shown that AKT1 cross-talks with Src/Stat3 pathway. AKT1 is a direct target gene of Stat3. Protein/mRNA levels and promoter activity of AKT1 are significantly induced by constitutively active Src and Stat3. Knockdown of Stat3 or dominant-negative Stat3 reduced AKT1 expression induced by constitutively active Src. Blockage of AKT1 expression largely reduced Stat3 function in cell survival and angiogenesis. Furthermore, I have shown that proapoptotic protein 24p3 is a major target of Akt to mediate IL3 signaling in hematopoietic cells. Forkhead transcription factor FOXO3a directly binds to and activates 24p3 promoter leading to expression of 24p3 in response to IL3 withdrawal. Akt phosphorylates FOXO3a and inhibits its action toward 24p3. Finally, I have identified a novel transcription factor TZP that interacts with Akt and p53. Expression of TZP inhibits cell growth and survival and induces both G1 and G2/M cell cycle arrest. TZP directly binds to the p53 promoter and induces p53 transcription. In addition, TZP interacts with p53 and prevents p53 from Mdm2-mediated degradation. In response to genotoxic stress, both TZP and p53 were upregulated and knockdown of TZP reduced p53 expression. Akt phosphorylated TZP resulting in its translocation from the nucleus into the cytoplasm, and thus inhibits TZP function. These data indicate that Akt induced by STAT3 confers oncogenesis through inhibition of the transcription factors

AKT function and human oncogenesis

Accumulated evidence indicates that, by the phosphorylation of its physiological substrates, Akt promotes cell survival, proliferation and angiogenesis. While a number of Akt targets have been identified, the mechanism by which Akt regulates cell survival and growth and induces malignant transformation still remains elusive. During the last 5 years, I have shown that AKT1 cross-talks with Src/Stat3 pathway. AKT1 is a direct target gene of Stat3. Protein/mRNA levels and promoter activity of AKT1 are significantly induced by constitutively active Src and Stat3. Knockdown of Stat3 or dominant-negative Stat3 reduced AKT1 expression induced by constitutively active Src. Blockage of AKT1 expression largely reduced Stat3 function in cell survival and angiogenesis. Furthermore, I have shown that proapoptotic protein 24p3 is a major target of Akt to mediate IL3 signaling in hematopoietic cells. Forkhead transcription factor FOXO3a directly binds to and activates 24p3 promoter leading to expression of 24p3 in response to IL3 withdrawal. Akt phosphorylates FOXO3a and inhibits its action toward 24p3. Finally, I have identified a novel transcription factor TZP that interacts with Akt and p53. Expression of TZP inhibits cell growth and survival and induces both G1 and G2/M cell cycle arrest. TZP directly binds to the p53 promoter and induces p53 transcription. In addition, TZP interacts with p53 and prevents p53 from Mdm2-mediated degradation. In response to genotoxic stress, both TZP and p53 were upregulated and knockdown of TZP reduced p53 expression. Akt phosphorylated TZP resulting in its translocation from the nucleus into the cytoplasm, and thus inhibits TZP function. These data indicate that Akt induced by STAT3 confers oncogenesis through inhibition of the transcription factors

Performance Evaluation of a Tactile and Kinesthetic Finger Feedback System for Teleoperation

Teleoperation during a catastrophic event requires an interface that can perform under frequently changing circumstances caused by unpredictable and dangerous conditions. Thus, teleoperation interfaces are under active development to provide both visual and haptic feedback to the fingers. However, studies of teleoperation systems with finger haptic feedback based on force profiles are difficult to conduct because of interface limitations. Therefore, in this paper, we introduce an intuitive teleoperation interface, an anthropomorphic teleoperated robot, and a hand-wearable force-feedback system that provides various feedbacks to the fingers. We combined these systems to compare and evaluated the performance of tactile and kinesthetic finger feedback using two experiments: maintaining appropriate grip force for variably fragile objects and following a force trajectory that changed in real time. Ten subjects participated in the experiments. The results were analyzed using repeated measures analysis of variance. Feedback factors differed significantly. Provision of force feedback to the user???s finger was most effective in both teleoperation experiments

A tele-operation interface with a motion capture system and a haptic glove

Tele-operation systems have been developed to perform tasks in extreme environments which cannot be easily accessed by human. However, non-intuitive control interfaces using only a keyboard or a joystick and wireless communication issues have prohibited the wide application of the tele-operation systems. In this work, an intuitive operation interface using inertial measurement units (IMUs) and a haptic glove was proposed to control a six degrees of freedom (DOFs) robot arm in remote place. Using the measured joint angles by the IMUs, the wrist position of the human arm was obtained by forward kinematics, which was used to calculate the robot joint angles by inverse kinematics. Considering workspace of the robot and human arms, robot joint angles were selected from many feasible solutions by the inverse kinematics. Also, the robot hand was controlled by the measured finger joint angles from the haptic glove, which also delivered vibration to the fingers according to the grasp force of the robot hand. As a tele-communication method, the 3GPP (3rd Generation Partnership Project) Long Term Evolution (LTE) network and a virtual private network (VPN) were utilized. The performance of the proposed system was verified by experiments

Extremely Low Frequency Magnetic Fields Induce Spermatogenic Germ Cell Apoptosis: Possible Mechanism

The energy generated by an extremely low frequency electromagnetic field (ELF-EMF) is too weak to directly induce genotoxicity. However, it is reported that an extremely low frequency magnetic field (ELF-MF) is related to DNA strand breakage and apoptosis. The testes that conduct spermatogenesis through a dynamic cellular process involving meiosis and mitosis seem vulnerable to external stress such as heat, MF exposure, and chemical or physical agents. Nevertheless the results regarding adverse effects of ELF-EMF on human or animal reproductive functions are inconclusive. According to the guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP; 2010) for limiting exposure to time-varying MF (1 Hz to 100 kHz), overall conclusion of epidemiologic studies has not consistently shown an association between human adverse reproductive outcomes and maternal or paternal exposure to low frequency fields. In animal studies there is no compelling evidence of causal relationship between prenatal development and ELF-MF exposure. However there is increasing evidence that EL-EMF exposure is involved with germ cell apoptosis in testes. Biophysical mechanism by which ELF-MF induces germ cell apoptosis has not been established. This review proposes the possible mechanism of germ cell apoptosis in testes induced by ELF-MF

Extension of the DG Model to the Second-Order Quantum Correction for Analysis of the Single-Charge Effect in Sub-10-nm MOS Devices

We extended the density-gradient (DG) model to include a second-order quantum correction (SOQC) term. The DG model has been widely used as a device simulation model capable of simulating quantum effects in efficient way. However, when only the first order quantum correction term is considered in the DG model, it is difficult to accurately describe device characteristics such as carrier density or potential fluctuation in the narrow region due to discrete charges such as dopants and interface traps. Thus, we extended the DG model to the SOQC, implemented it as a three-dimensional (3D) simulator, and compared the simulation results for sub-10-nm devices, which have a single point charge, in the DG model and the 3D Schrödinger–Poisson (SP) solver. Through this, we identified that the DG extended to SOQC well reproduces the SP simulation results in terms of both capacitance–voltage (C–V) and local fluctuation in electron density