EBSD investigation of microstructure and microtexture evolution on additively manufactured TiC-Fe based cermets-Influence of multiple laser scanning

Sustainable TiC-Fe-based cermets have been fabricated by adopting an Additive Manufacturing route based on laser powder bed fusion technology (L-PBF). The objective is to produce crack-free cermet components by employing novel multiple laser scanning techniques with variations in laser process parameters. Electron backscatter diffraction analysis (EBSD) was used to study the microstructure and microtexture evolution with variations in laser process parameters. The investigation revealed that adjusting the preheating scan speed (PHS) and melting scan speed (MS) influenced the growth and nucleation of TiC phases. Lowering these speeds resulted in grain coarsening, while higher scan speeds led to grain refinement with larger sub-grain boundaries. Moreover, a high scanning speed increases the degree of dislocation density and internal stress in the fabricated cermet parts. Notably, it is revealed that decreasing the laser scan speed enhanced the proportion of high-angle grain boundaries in the cermet components, signifying an increase in material ductility.

DIdM-EIoTD: Distributed Identity Management for Edge Internet of Things (IoT) Devices

The Internet of Things (IoT) paradigm aims to enhance human society and living standards with the vast deployment of smart and autonomous devices, which requires seamless collaboration. The number of connected devices increases daily, introducing identity management requirements for edge IoT devices. Due to IoT devices' heterogeneity and resource-constrained configuration, traditional identity management systems are not feasible. As a result, identity management for IoT devices is still an open issue. Distributed Ledger Technology (DLT) and blockchain-based security solutions are becoming popular in different application domains. This paper presents a novel DLT-based distributed identity management architecture for edge IoT devices. The model can be adapted with any IoT solution for secure and trustworthy communication between devices. We have comprehensively reviewed popular consensus mechanisms used in DLT implementations and their connection to IoT research, specifically identity management for Edge IoT devices. Our proposed location-based identity management model is generic, distributed, and decentralized. The proposed model is verified using the Scyther formal verification tool for security performance measurement. SPIN model checker is employed for different state verification of our proposed model. The open-source simulation tool FobSim is used for fog and edge/user layer DTL deployment performance analysis. The results and discussion section represents how our proposed decentralized identity management solution should enhance user data privacy and secure and trustworthy communication in IoT.

FedSepsis: A Federated Multi-Modal Deep Learning-Based Internet of Medical Things Application for Early Detection of Sepsis from Electronic Health Records Using Raspberry Pi and Jetson Nano Devices

The concept of the Internet of Medical Things brings a promising option to utilize various electronic health records stored in different medical devices and servers to create practical but secure clinical decision support systems. To achieve such a system, we need to focus on several aspects, most notably the usability aspect of deploying it using low-end devices. This study introduces one such application, namely FedSepsis, for the early detection of sepsis using electronic health records. We incorporate several cutting-edge deep learning techniques for the prediction and natural-language processing tasks. We also explore the multimodality aspect for the better use of electronic health records. A secure distributed machine learning mechanism is essential to building such a practical internet of medical things application. To address this, we analyze two federated learning techniques. Moreover, we use two different kinds of low-computational edge devices, namely Raspberry Pi and Jetson Nano, to address the challenges of using such a system in a practical setting and report the comparisons. We report several critical system-level information about the devices, namely CPU utilization, disk utilization, process CPU threads in use, process memory in use (non-swap), process memory available (non-swap), system memory utilization, temperature, and network traffic. We publish the prediction results with the evaluation metrics area under the receiver operating characteristic curve, the area under the precision-recall curve, and the earliness to predict sepsis in hours. Our results show that the performance is satisfactory, and with a moderate amount of devices, the federated learning setting results are similar to the single server-centric setting. Multimodality provides the best results compared to any single modality in the input features obtained from the electronic health records. Generative adversarial neural networks provide a clear superiority in handling the sparsity of electronic health records. Multimodality with the generative adversarial neural networks provides the best result: the area under the precision-recall curve is 96.55%, the area under the receiver operating characteristic curve is 99.35%, and earliness is 4.56 h. FedSepsis suggests that incorporating such a concept together with low-end computational devices could be beneficial for all the medical sector stakeholders and should be explored further.

5G-Enabled Distributed Intelligence Based on O-RAN for Distributed IoT Systems

Edge-based distributed intelligence techniques, such as federated learning (FL), have recently been used in many research fields thanks, in part, to their decentralized model training process and privacy-preserving features. However, because of the absence of effective deployment models for the radio access network (RAN), only a tiny number of FL apps have been created for the latest generation of public mobile networks (e.g., 5G and 6G). There is an attempt, in new RAN paradigms, to move toward disaggregation, hierarchical, and distributed network function processing designs. Open RAN (O-RAN), as a cutting-edge RAN technology, claims to meet 5G services with high quality. It includes integrated, intelligent controllers to provide RAN with the power to make smart decisions. This paper proposes a methodology for deploying and optimizing FL tasks in O-RAN to deliver distributed intelligence for 5G applications. To accomplish model training in each round, we first present reinforcement learning (RL) for client selection for each FL task and resource allocation using RAN intelligence controllers (RIC). Then, a slice is allotted for training depending on the clients chosen for the task. Our simulation results show that the proposed method outperforms state-of-art FL methods, such as the federated averaging algorithm (FedAvg), in terms of convergence and number of communication rounds.

A letter to editor related to: "Relationship between workplace ergonomics and musculoskeletal pain, range of motion and spinal deformities in employees: A case study, Kermanshah Oil Refinery"

A few points about the published article in the Occupational Medicine Quarterly Journal Volume 12 Issue 4 entitled Relationship between workplace ergonomics and musculoskeletal pain, range of motion and spinal deformities in employees:A case study, Kermanshah Oil Refinery were discussed.The article included the  term "workplace ergonomics", "prevalence of musculoskeletal pain", and "application of RULA for posture assessment". These points were discussed in this letter.

Federated Semi-Supervised Multi-Task Learning to Detect COVID-19 and Lungs Segmentation Marking Using Chest Radiography Images and Raspberry Pi Devices: An Internet of Medical Things Application

Internet of Medical Things (IoMT) provides an excellent opportunity to investigate better automatic medical decision support tools with the effective integration of various medical equipment and associated data. This study explores two such medical decision-making tasks, namely COVID-19 detection and lung area segmentation detection, using chest radiography images. We also explore different cutting-edge machine learning techniques, such as federated learning, semi-supervised learning, transfer learning, and multi-task learning to explore the issue. To analyze the applicability of computationally less capable edge devices in the IoMT system, we report the results using Raspberry Pi devices as accuracy, precision, recall, Fscore for COVID-19 detection, and average dice score for lung segmentation detection tasks. We also publish the results obtained through server-centric simulation for comparison. The results show that Raspberry Pi-centric devices provide better performance in lung segmentation detection, and server-centric experiments provide better results in COVID-19 detection. We also discuss the IoMT application-centric settings, utilizing medical data and decision support systems, and posit that such a system could benefit all the stakeholders in the IoMT domain.

IMSC-EIoTD: Identity Management and Secure Communication for Edge IoT Devices

The Internet of things (IoT) will accommodate several billions of devices to the Internet to enhance human society as well as to improve the quality of living. A huge number of sensors, actuators, gateways, servers, and related end-user applications will be connected to the Internet. All these entities require identities to communicate with each other. The communicating devices may have mobility and currently, the only main identity solution is IP based identity management which is not suitable for the authentication and authorization of the heterogeneous IoT devices. Sometimes devices and applications need to communicate in real-time to make decisions within very short times. Most of the recently proposed solutions for identity management are cloud-based. Those cloud-based identity management solutions are not feasible for heterogeneous IoT devices. In this paper, we have proposed an edge-fog based decentralized identity management and authentication solution for IoT devices (IoTD) and edge IoT gateways (EIoTG). We have also presented a secure communication protocol for communication between edge IoT devices and edge IoT gateways. The proposed security protocols are verified using Scyther formal verification tool, which is a popular tool for automated verification of security protocols. The proposed model is specified using the PROMELA language. SPIN model checker is used to confirm the specification of the proposed model. The results show different message flows without any error.

Enhancing the Internet of Things with Knowledge-Driven Software-Defined Networking Technology: Future Perspectives

The Internet of Things (IoT) connects smart devices to enable various intelligent services. The deployment of IoT encounters several challenges, such as difficulties in controlling and managing IoT applications and networks, problems in programming existing IoT devices, long service provisioning time, underused resources, as well as complexity, isolation and scalability, among others. One fundamental concern is that current IoT networks lack flexibility and intelligence. A network-wide flexible control and management are missing in IoT networks. In addition, huge numbers of devices and large amounts of data are involved in IoT, but none of them have been tuned for supporting network management and control. In this paper, we argue that Software-defined Networking (SDN) together with the data generated by IoT applications can enhance the control and management of IoT in terms of flexibility and intelligence. We present a review for the evolution of SDN and IoT and analyze the benefits and challenges brought by the integration of SDN and IoT with the help of IoT data. We discuss the perspectives of knowledge-driven SDN for IoT through a new IoT architecture and illustrate how to realize Industry IoT by using the architecture. We also highlight the challenges and future research works toward realizing IoT with the knowledge-driven SDN.

A Blockchain-Assisted Intelligent Transportation System Promoting Data Services with Privacy Protection

Being able to obtain various environmental and driving data from vehicles is becoming more and more important for current and future intelligent transportation systems (ITSs) to operate efficiently and economically. However, the limitations of privacy protection and security of the current ITSs are hindering users and vehicles from providing data. In this paper, we propose a new ITS architecture by using blockchain technology solving the privacy protection and security problems, and promoting users and vehicles to provide data to ITSs. The proposed architecture uses blockchain as a trust infrastructure to protect users’ privacy and provide trustworthy services to users. It is also compatible with the legacy ITS infrastructure and services. In addition, the hierarchical organization of chains enables the scalability of the system, and the use of smart contracts provides a flexible way for introducing new services in the ITS. The proposed architecture is demonstrated by a proof of concept implementation based on Ethereum. The test results show that the proposed architecture is feasible.

Improved diagnostic accuracy for myocardial perfusion imaging using artificial neural networks on different input variables including clinical and quantification data

OBJECTIVE

Diagnostic accuracy of myocardial perfusion imaging (MPI) is not optimal to predict the result of angiography. The current study aimed at investigating the application of artificial neural network (ANN) to integrate the clinical data with the result and quantification of MPI.

METHODS

Out of 923 patients with MPI, 93 who underwent angiography were recruited. The clinical data including the cardiac risk factors were collected and the results of MPI and coronary angiography were recorded. The quantification of MPI polar plots (i.e. the counts of 20 segments of each stress and rest polar plots) and the Gensini score of angiographies were calculated. Feed-forward ANN was designed integrating clinical and quantification data to predict the result of angiography (normal vs. abnormal), non-obstructive or obstructive coronary artery disease (CAD), and Gensini score (≥10 and <10). The ANNs were designed to predict the results of angiography using different combinations of data as follows: reports of MPI, the counts of 40 segments of stress and rest polar plots, and the count of these 40 segments in addition to age, gender, and the number of risk factors. The diagnostic performance of MPI with different ANNs was compared.

RESULTS

The accuracy of MPI to predict the result of angiography, obstructive CAD, and Gensini score increased from 81.7% to 92.9%, 65.0% to 85.7%, and 50.5% to 92.9%, respectively by ANN using counts and clinical risk factors.

CONCLUSION

The diagnostic accuracy of MPI could be improved by ANN, using clinical and quantification data.

Multiscale Friction in Lubricant-Surface Systems for High-Performance Transmissions Under Mild Wear

The lubricant-surface system is complex in nature and can significantly affect the frictional performance of high-performance transmission systems. The complexity stems from the coupled mechanical and chemical phenomena that occur at the interfacial tooth conjunctions. A combined analytical and precision experimental approach is presented to analyse the salient parameters of the lubricant-surface system. A multiscale procedure comprising topographical measurement, pin-on-disc tribometry, atomic force microscopy in lateral force mode, X-ray photo-electron spectroscopy and continuum contact mechanics analysis under mixed non-Newtonian thermo-elastohydrodynamics is used to describe the formation of a tribo-film, as well as wear and frictional characteristics of the lubricant-surface system. The contribution of chemisorbed and physisorbed bonded tribo-film on the boundary coefficient of friction is ascertained at different physical scales. Therefore, the paper presents a novel multiscale analysis, promoting improved understanding of the complex interactions between mechanisms of friction, wear and surface chemistry.

Analysis of real-time mixture cytotoxicity data following repeated exposure using BK/TD models

Cosmetic products generally consist of multiple ingredients. Thus, cosmetic risk assessment has to deal with mixture toxicity on a long-term scale which means it has to be assessed in the context of repeated exposure. Given that animal testing has been banned for cosmetics risk assessment, in vitro assays allowing long-term repeated exposure and adapted for in vitro - in vivo extrapolation need to be developed. However, most in vitro tests only assess short-term effects and consider static endpoints which hinder extrapolation to realistic human exposure scenarios where concentration in target organs is varies over time. Thanks to impedance metrics, real-time cell viability monitoring for repeated exposure has become possible. We recently constructed biokinetic/toxicodynamic models (BK/TD) to analyze such data (Teng et al., 2015) for three hepatotoxic cosmetic ingredients: coumarin, isoeugenol and benzophenone-2. In the present study, we aim to apply these models to analyze the dynamics of mixture impedance data using the concepts of concentration addition and independent action. Metabolic interactions between the mixture components were investigated, characterized and implemented in the models, as they impacted the actual cellular exposure. Indeed, cellular metabolism following mixture exposure induced a quick disappearance of the compounds from the exposure system. We showed that isoeugenol substantially decreased the metabolism of benzophenone-2, reducing the disappearance of this compound and enhancing its in vitro toxicity. Apart from this metabolic interaction, no mixtures showed any interaction, and all binary mixtures were successfully modeled by at least one model based on exposure to the individual compounds.

Cryopreserved porcine hepatocytes: expression and induction of cytochrome P450, isoform CYP2E1

Cryopreservation of porcine hepatocytes for their use in bioartificial liver devices may result in reduced cytochrome P450 (CYP) enzyme activity. The aim of this study was to assess the effects of several CYP inducers on the isoform CYP2E1 protein expression in cryopreserved porcine hepatocytes. Isolated porcine hepatocytes were cryopreserved for 1 month, thawed, and cultured for 3 days. During medium culture, the hepatocytes were exposed to the following CYP inducers: dimethyl sulfoxide, rifampicin, phenobarbital, 3-methylcholanthrene, and dexamethasone. CYP2E1 protein expression was determined by immunoblotting. CYP2E1 protein levels were constantly detected in cryopreserved porcine hepatocytes. CYP inducers did not modify CYP2E1 protein levels. Long-term cryopreserved porcine hepatocytes preserved their capacity for CYP2E1 protein expression, although exposure of these hepatocytes to CYP inducers did not modify the CYP2E1 protein expression.

Effect of oral carbohydrate intake on labor progress: randomized controlled trial

BACKGROUND

Lack of information regarding biochemical changes in women during labor and its outcomes on maternal and neonatal health still is an unanswered question. This study aims to explore the effectiveness of oral carbohydrate intake during labor on the duration of the active phase and other maternal and neonatal outcomes.

METHODS

A parallel prospective randomized controlled trial, conducted at the University Affiliated Teaching Hospital in Gonabad. Totally, 190 women were randomly assigned to an intervention (N=87) or control (N=90) group. Inclusion criteria were low-risk women with singleton cephalic presentation; and cervical dilatation 3-4 cm. Randomization was used by random number generator on every day. Odd numbers was used for intervention and even numbers for control group. Intervention was based on the preferences between: 3 medium dates plus 110 ml water; 3 dates plus 110 ml light tea without sugar; or 110 ml orange juice. The protocol is only run once but women ate and drank gradually before second stage of labor. Control group were fasted as routine practice. Neither participants nor care givers or staff could be blinded to group allocation. Differences between duration of the active phase of labor were assessed as primary outcome measure.

RESULTS

There was significant difference in the length of second stage of labor (P <.05). The effect size for this variable was 0.48. There were no significant differences in other maternal and neonatal outcomes.

CONCLUSIONS

Oral intake of carbohydrate was an effective method for shortening the duration of second stage of labor in low-risk women.

Parametric modelling of cardiac system multiple measurement signals: an open-source computer framework for performance evaluation of ECG, PCG and ABP event detectors

The major focus of this study is to present a performance accuracy assessment framework based on mathematical modelling of cardiac system multiple measurement signals. Three mathematical algebraic subroutines with simple structural functions for synthetic generation of the synchronously triggered electrocardiogram (ECG), phonocardiogram (PCG) and arterial blood pressure (ABP) signals are described. In the case of ECG signals, normal and abnormal PQRST cycles in complicated conditions such as fascicular ventricular tachycardia, rate dependent conduction block and acute Q-wave infarctions of inferior and anterolateral walls can be simulated. Also, continuous ABP waveform with corresponding individual events such as systolic, diastolic and dicrotic pressures with normal or abnormal morphologies can be generated by another part of the model. In addition, the mathematical synthetic PCG framework is able to generate the S4-S1-S2-S3 cycles in normal and in cardiac disorder conditions such as stenosis, insufficiency, regurgitation and gallop. In the PCG model, the amplitude and frequency content (5-700 Hz) of each sound and variation patterns can be specified. The three proposed models were implemented to generate artificial signals with varies abnormality types and signal-to-noise ratios (SNR), for quantitative detection-delineation performance assessment of several ECG, PCG and ABP individual event detectors designed based on the Hilbert transform, discrete wavelet transform, geometric features such as area curve length (ACLM), the multiple higher order moments (MHOM) metric, and the principal components analysed geometric index (PCAGI). For each method the detection-delineation operating characteristics were obtained automatically in terms of sensitivity, positive predictivity and delineation (segmentation) error rms and checked by the cardiologist. The Matlab m-file script of the synthetic ECG, ABP and PCG signal generators are available in the Appendix.

Clotrimazole protects the liver against normothermic ischemia-reperfusion injury in rats

OBJECTIVE

To investigate the possible antiapoptotic prosurvival role of the pregnane X receptor (PXR) in hepatic ischemia-reperfusion injury in rats using clotrimazole (CTZ), a strong PXR transactivator.

MATERIALS AND METHODS

Male Sprague-Dawley rats were divided into 3 groups of 6 each: sham-treated, control, and CTZ-treated animals. Control and CTZ-treated animals were subjected to 30 minutes of normothermic ischemia of the whole liver followed by 6 hours of reperfusion. The animals were then killed, and the liver was excised and blood samples collected.

RESULTS

Clotrimazole induced a significant increase in expression of the CYP3A gene, indicating PXR transactivation, whereas expression of the antiapoptotic Bcl-xL gene was not increased. Serum concentrations of aspartate aminotransaminase and alanine aminotransaminase were lower in CTZ-treated animals than in control animals (difference not significant). Levels of poly(adenosine diphosphate-ribose) polymerase, a caspase-3 substrate, remained significantly higher in the CTZ-treated group compared with controls (P < .05). Clotrimazole increased the expression of phospho-p 44/42 extracellular signal-regulated kinase 1,2 (P < .05). The gene expression of the heat shock proteins 27, 70 and 90 was significantly lower in CTZ-treated animals than in controls (P < .05).

CONCLUSION

Clotrimazole-mediated PXR transactivation protects the liver against ischemia-reperfusion apoptosis in rats. Phospho-p 44/42 extracellular signal-regulated kinase 1,2 is activated, whereas gene expression of heat shock proteins 27, 70, and 90 is downregulated by induction of PXR.

Stand structure and spatial patterns of trees in mixed Hyrcanian Beech forest, Iran

The mixed beach forests (Fagus orientalis) commonly dominate by shade tolerance species with irregular uneven age stand structure. The aim of this study was to analyze the stand structure and spatial pattern in order to identify specific structural patterns. Data was collected from a 16 ha permanent plot. We mapped all stems > 7.5 cm in diameter at breast height on permanent plot. The six main species were divided into two groups based on density and stand structure. Group A had higher density than group B, as well as L-shaped DBH distribution of live stems. Species in group B had bell-shaped DBH distributions. Species in group A have clump spatial distribution pattern in all layers but clump intensity is more than in understory layer and size of patch clump is small in this group. This phenomenon for group A may explaining by having numerous coppice, sucker and patch regeneration in the understory layer. Middlestory and understory stems of the six major tree species were patchily distributed throughout the plot but for Alder and Maple species common pattern in canopy layer was complete spatial randomness. The distribution of Beech and Hornbeam trees were negatively associated with other species. These results suggest species differences in favorable canopy condition.

Cadmium-induced apoptosis through the mitochondrial pathway in rainbow trout hepatocytes: involvement of oxidative stress

Cadmium (Cd) induces oxidative stress and apoptosis in trout hepatocytes. We therefore investigated the involvement of the mitochondrial pathway in the initiation of apoptosis and the possible role of oxidative stress in that process. This study demonstrates that hepatocyte exposure to Cd (2, 5 and 10 microM) triggers significant caspase-3, but also caspase-8 and -9 activation in a dose-dependent manner. Western-blot analysis of hepatocyte mitochondrial and cytosolic fractions revealed that cytochrome c (Cyt c) was released in the cytosol in a dose-dependent manner, whereas the pro-apoptotic protein Bax was redistributed to mitochondria after 24 and 48 h exposure. We also found that the expression of anti-apoptotic protein Bcl-xL, known to be regulated under mild oxidative stress to protect cells from apoptosis, did not change after 3 and 6 h exposure to Cd, then increased after 24 and 48 h exposure to 10 microM Cd. In the second part of this work, two antioxidant agents, 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) (100 microM) and N-acetylcysteine (NAC, 100 microM) were used to determine the involvement of reactive oxygen species (ROS) in Cd-induced apoptosis. Simultaneously exposing trout hepatocytes to Cd and TEMPO or NAC significantly reduced caspase-3 activation after 48 h and had a suppressive effect on caspase-8 and -9 also, mostly after 24 h. Lastly, the presence of either one of these antioxidants in the treatment medium also attenuated Cd-induced Cyt c release in cytosol and the level of Bax in the mitochondria after 24 and 48 h, while high Bcl-xL expression was observed. Taken together, these data clearly evidenced the key role of mitochondria in the cascade of events leading to trout hepatocyte apoptosis in response to Cd and the relationship that exists between oxidative stress and cell death.

The role of protein tyrosine kinases in CYP1A1 induction by omeprazole and thiabendazole in rat hepatocytes

Benzimidazoles compounds like omeprazole (OME) and thiabendazole (TBZ) mediate CYP1A1 induction differently from classical aryl hydrocarbon receptor (AhR) ligands, 3-methylcholanthrene (3-MC) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). To clarify the involvement of an intracellular signal pathway in CYP1A1 induction by OME and TBZ, the TBZ, OME and 3-MC signal-transducing pathways were compared by using specific protein tyrosine kinase inhibitors in primary culture of rat hepatocytes. The effect of OME and TBZ (75-250 microM) on cytochrome P450 1A1 (CYP1A1) expression was therefore studied in primary cultures of rat hepatocytes after 24 h, 48 h and 72 h of exposure. Both compounds provoked a dose- and time-dependent increase in CYP1A1 (EROD activity, protein and mRNA levels), but OME was less effective at all the concentrations and times tested. The mechanism of benzimidazole-mediated induction of CYP1A1 was investigated by comparison with 3-MC, a prototypical AhR ligand. As expected, OME and TBZ were unable to displace [(3)H]-TCDD from its binding sites to the AhR in competitive binding studies. Moreover, classic tyrosine kinase inhibitor herbimycin A (HA) inhibited the two benzimidazoles-mediated CYP1A1 inductions, but only partially inhibited the 3-MC-mediated one. Another two tyrosine kinase inhibitors, Lavendustin A (LA) and genistein (GEN), had no effect on CYP1A1 induction by benzimidazoles and 3-MC. These results are consistent with the implication of a tyrosine kinase, most probably the Src tyrosine kinase, in the mechanism of CYP1A1 induction in rat hepatocytes.

Spontaneous apoptosis in primary cultures of human and rat hepatocytes: molecular mechanisms and regulation by dexamethasone

To elucidate the biochemical pathways leading to spontaneous apoptosis in primary cultures of human and rat hepatocytes, we examined the activation of the caspase cascade, the expression of Bcl-2-related-proteins and heat shock proteins. Comparisons were made before and after dexamethasone (DEX) treatment. We show that DEX inhibited spontaneous apoptosis in a dose-dependent manner. DEX increases the expression of anti-apoptotic Bcl-2 and Bcl-x(L) proteins, decreases the expression of pro-apoptotic Bax and inhibits Bad translocation thereby preventing the release of cytochrome c, the activation of caspases, and cell death. Although, the expression of Hsp27 and Hsp70 proteins remained unchanged, the oncogenic protein c-Myc is upregulated upon DEX-treatment. These results indicate that DEX mediates its survival effect against spontaneous apoptosis by acting upstream of the mitochondrial changes. Thus, the mitochondrial apoptotic pathway plays a major role in regulating spontaneous apoptosis in these cells. Blocking this pathway therefore may assist with organ preservation for transplant, drug screening, and other purposes.

QSAR modeling of the adult and developmental toxicity of glycols, glycol ethers and xylenes to Hydra attenuata

Autocorrelation descriptors encoding lipophilicity, molar refractivity, the H-bonding acceptor ability and H-bonding donor ability of the molecules were used to describe glycols, glycol ethers, and xylenes characterized by their adult and developmental toxicities to Hydra attenuata. A PLS regression analysis was employed to derive a QSAR model allowing to simulate both endpoints. Comparisons were made with classical regression analyses using the 1-octanol/water partition coefficient as molecular descriptor.

Spot 14 protein interacts and co-operates with chicken ovalbumin upstream promoter-transcription factor 1 in the transcription of the L-type pyruvate kinase gene through a specificity protein 1 (Sp1) binding site

In hepatocytes, the amount of the Spot 14 (S14) protein is closely related to the full expression of enzymes involved in the glycolytic and lipogenic pathways. In the present study we address the role played by this protein in the control of transcription of the L-type pyruvate kinase (L-PK) gene in primary hepatocytes. We show that human S14, which by itself does not bind to the L-PK promoter, physically interacts with the human chicken ovalbumin upstream promoter-transcription factor 1 (COUP-TF1) and induces the switch of this factor from a repressor to an activator. However, the enhancing activity of S14 and COUP-TF1 depends on the presence of a proximal GC-rich box (the L0 element) that specifically binds nuclear proteins from the livers of rats fed a glucose-rich diet. Moreover, the L0 element, which strongly binds dephosphorylated specificity protein 1 (Sp1), loses all affinity when this factor is phosphorylated by cAMP-dependent protein kinase. Mutations that affect binding of Sp1 and nuclear proteins to the L0 box also decrease basal transcription and impair glucose responsiveness of the promoter. These results therefore shed light on the mechanism by which the S14 protein, whose concentration rapidly rises after glucose intake, contributes to the full activity of the L-PK promoter.

Toxic effects of wastewaters collected at upstream and downstream sites of a purification station in cultures of rainbow trout hepatocytes

The toxic effects of wastewater samples, collected in December 1998, from upstream (U) and downstream (D) sites of the purification station of the town of Nice (South-East France on the coast of the Mediterranean Sea) were assessed undiluted and at various dilutions (75%, 50%, and 25% of collected water sample), on trout hepatocyte cultures treated for 48 or 72 h. Chemical contamination (PCBs, PAHs, Cd, Cu, Pb, and Zn) was also evaluated by chemical analysis. The water samples from the upstream site were more cytotoxic than those from the downstream site. The induction of CYP1A enzyme and metallothioneins (MTs) were selected as specific indicators of exposure to organic contaminants and metals, respectively. CYP1A-related EROD activity as well as protein expression were found to be greatly induced after 72 h exposure of the hepatocytes to the undiluted water samples (U(100%) and D(100%)), but CYP1A1 mRNA was significantly overexpressed only by samples from the upstream site. Maximal MT levels were reached after 48 h of treatment with the least concentrated water samples (U(25%) and D(25%)). Glutathione S-transferase (GST) activities were similarly increased under the same conditions. On the other hand, there was no significant glutathione peroxidase (GPx) activity response. Induction of apoptosis was analyzed by using as markers both the fragmentation of the nuclear DNA into oligonucleosomal-length fragments recognized as a "DNA ladder" and the activation of DEVD (Asp-Glu-Val-Asp)-dependent protease considered as the central mediator of programmed cell death. Significant DNA cleavage was only detectable after 72-h exposure to the most concentrated water samples from upstream sites (U(75%) and U(100%)). DEVD-dependent protease activities were significantly increased, mainly in cells exposed to U(75%) and D(25%) for 72 h. In addition, pollution-related DNA damage assessed by using the Comet assay was approximatively 1.5 times greater than that of the control level with the undiluted water samples U(100%) and D(100%), after 72-h and 48-h exposure, respectively. The present study shows that such a multibiomarker-based approach could provide complementary information, for aquatic pollution monitoring, about the early biochemical effects in cells exposed to complex chemical pollution and could be considered as early warning systems to aquatic pollution.

Cadmium induces apoptosis and genotoxicity in rainbow trout hepatocytes through generation of reactive oxygene species

Cadmium poses a serious environmental threat in aquatic ecosystems but the mechanisms of its toxicity remain unclear. The purpose of this work was first to determine whether cadmium induced apoptosis in trout hepatocytes, second to determine whether or not reactive oxygen species (ROS) were involved in cadmium-induced apoptosis and genotoxicity. Hepatocytes exposed to increasing cadmium concentrations (in the range of 1-10 microM) showed a molecular hallmark of apoptosis which is the fragmentation of the nuclear DNA into oligonucleosomal-length fragments, resulting from an activation of endogenous endonucleases and recognized as a 'DNA ladder' on conventional agarose gel electrophoresis. Exposure of hepatocytes to cadmium led clearly to the DEVD-dependent protease activation, acting upstream from the endonucleases and considered as central mediators of apoptosis. DNA strand breaks in cadmium-treated trout hepatocytes was assessed using the comet assay, a rapid and sensitive single-cell gel electrophoresis technique used to detect DNA primary damage in individual cells. Simultaneous treatment of trout hepatocytes with cadmium and the nitroxide radical TEMPO used as a ROS scavenger, reduced significantly DNA fragmentation, DEVD-related protease activity and DNA strand breaks formation. These results lead to a working hypothesis that cadmium-induced apoptosis and DNA strand breaks in trout hepatocytes are partially triggered by the generation of ROS. Additional studies are required for proposing a mechanistic model of cadmium-induced apoptosis and genotoxicity in trout liver cells, in underlying the balance between DNA damage and cellular defence systems in fish.

Dexamethasone inhibits spontaneous apoptosis in primary cultures of human and rat hepatocytes via Bcl-2 and Bcl-xL induction

We examined the effects of dexamethasone (DEX) on the apoptotic process in primary cultures of human and rat hepatocytes. DEX prolonged cell viability, inhibited the development of an apoptotic morphology, and stabilised the expression of procaspase-3 in both human and rat hepatocytes. In addition, the inhibition of apoptosis by DEX was strongly correlated with a decrease of caspase-3-like protease activity. Moreover, DEX treatment increased the expression of anti-apoptotic Bcl-2 and Bcl-xL proteins in human and rat hepatocytes, respectively, whereas the expression of pro-apoptotic proteins Bcl-xS or Bad was not detected or remained unchanged. The bcl-xL transcript is regulated at the transcriptional level and its expression paralleled that of Bcl-xL protein in DEX-treated rat hepatocytes. Taken together, these results indicate that this glucocorticoid exerts a protective role on cell survival and it delays apoptosis of human and rat hepatocytes by modulating caspase-3-like protease activity and bcl-2 and bcl-x gene expression.

Induction of cytochrome P450 1A1 gene expression, oxidative stress, and genotoxicity by carbaryl and thiabendazole in transfected human HepG2 and lymphoblastoid cells

Carbaryl and thiabendazole, two widely used pesticides, have been shown to induce cytochrome P450 1A1 (CYP1A1) expression, but neither compound is capable of displacing [3H] 2,3,7,8-tetrachlorodibenzo-P-dioxin from its aryl hydrocarbon receptor binding site. In the present study, we investigated the transcriptional regulation of CYP1A1 as well as other genes in various human hepatoma HepG2 cell lines stably transfected with the chloramphenicol acetyl transferase (CAT) reporter gene and cloned under the control of each of 14 promoters or response elements from relevant stress genes. Carbaryl and thiabendazole were found to activate CYP1A1 at the level of transcription, as demonstrated by the dose-dependent increase in reporter CAT and CYP1A1 mRNAs. Moreover, this effect appeared to be mediated via the xenobiotic responsive element (XRE), because both pesticides specifically activated various fusion constructs containing XRE sequences (CYP1A, glutathione S-transferase, and XRE). Carbaryl and to a lesser extent thiabendazole also activated other stress genes such as c-fos and NF-kappaBRE, HSP70 and GRP78, and GADD153 at a transcriptional level. These data suggest that these molecules induce early alert genes, including those known to be sensitive to oxidative stress. This led us to examine the genotoxic effect of carbaryl and thiabendazole by an in vitro DNA repair solid-phase assay. Both compounds provoked a strong DNA-damaging activity in the human lymphoblastoid cell line that constitutively expresses human CYP1A1 cDNA, but not in the parental line, indicating that CYP1A1 is chiefly implicated in carbaryl and thiabendazole genotoxicity. This effect was confirmed on HepG2 cells. These observations support the notion that intracellular signals leading to CYP1A1 induction, oxidative stress, and genotoxicity are intimately related.

Effects of macrolide antibiotics on CYP3A expression in human and rat hepatocytes: interspecies differences in response to troleandomycin

The effects of various macrolide antibiotics [triacetyloleandomycin (TAO), clarithromycin, azithromycin, roxithromycin, erythromycin base] and the new ketolide HMR3004 on CYP3A expression were evaluated in human and rat hepatocytes. Cells were treated for 3 days with nontoxic concentrations of the drugs, and CYP3A induction was assessed through midazolam hydroxylase activity and Western and Northern blot analyses. In rat hepatocytes, no induction of CYP3A1 expression was observed following exposure to macrolides, even to erythromycin base and TAO (well known in vivo CYP3A1 inducers), whereas dexamethasone and phenobarbital were confirmed to induce this enzyme. In contrast, treatment of fresh and thawed human hepatocytes with TAO, produced an increase of midazolam hydroxylation (4-fold over control). This result was in agreement with the high amount of CYP3A4 protein and mRNA revealed by Western and Northern blot analyses. Other tested macrolides had no induction effect on CYP3A expression. These results confirmed the interspecies variability of CYP3A regulation in hepatocytes and raised the question of its mechanism of induction by macrolides in human liver.