Interphase Delay Research Articles

Nup2 performs diverse interphase functions in Aspergillus nidulans.

The nuclear pore complex (NPC) protein Nup2 plays interphase nuclear transport roles and in Aspergillus nidulans also functions to bridge NPCs at mitotic chromatin for their faithful coinheritance to daughter G1 nuclei. In this study, we further investigate the interphase functions of Nup2 in A. nidulans. Although Nup2 is not required for nuclear import of all nuclear proteins after mitosis, it is required for normal G1 nuclear accumulation of the NPC nuclear basket–associated components Mad2 and Mlp1 as well as the THO complex protein Tho2. Targeting of Mlp1 to nuclei partially rescues the interphase delay seen in nup2 mutants indicating that some of the interphase defects in Nup2-deleted cells are due to Mlp1 mislocalization. Among the inner nuclear membrane proteins, Nup2 affects the localization of Ima1, orthologues of which are involved in nuclear movement. Interestingly, nup2 mutant G1 nuclei also exhibit an abnormally long period of extensive to-and-fro movement immediately after mitosis in a manner dependent on the microtubule cytoskeleton. This indicates that Nup2 is required to limit the transient postmitotic nuclear migration typical of many filamentous fungi. The findings reveal that Nup2 is a multifunctional protein that performs diverse functions during both interphase and mitosis in A. nidulans.

MASTL overexpression promotes chromosome instability and metastasis in breast cancer

MASTL kinase is essential for correct progression through mitosis, with loss of MASTL causing chromosome segregation errors, mitotic collapse and failure of cytokinesis. However, in cancer MASTL is most commonly amplified and overexpressed. This correlates with increased chromosome instability in breast cancer and poor patient survival in breast, ovarian and lung cancer. Global phosphoproteomic analysis of immortalised breast MCF10A cells engineered to overexpressed MASTL revealed disruption to desmosomes, actin cytoskeleton, PI3K/AKT/mTOR and p38 stress kinase signalling pathways. Notably, these pathways were also disrupted in patient samples that overexpress MASTL. In MCF10A cells, these alterations corresponded with a loss of contact inhibition and partial epithelial–mesenchymal transition, which disrupted migration and allowed cells to proliferate uncontrollably in 3D culture. Furthermore, MASTL overexpression increased aberrant mitotic divisions resulting in increased micronuclei formation. Mathematical modelling indicated that this delay was due to continued inhibition of PP2A-B55, which delayed timely mitotic exit. This corresponded with an increase in DNA damage and delayed transit through interphase. There were no significant alterations to replication kinetics upon MASTL overexpression, however, inhibition of p38 kinase rescued the interphase delay, suggesting the delay was a G2 DNA damage checkpoint response. Importantly, knockdown of MASTL, reduced cell proliferation, prevented invasion and metastasis of MDA-MB-231 breast cancer cells both in vitro and in vivo, indicating the potential of future therapies that target MASTL. Taken together, these results suggest that MASTL overexpression contributes to chromosome instability and metastasis, thereby decreasing breast cancer patient survival.

The application of household appliances' flexibility by set of sequential uninterruptible energy phases model in the day-ahead planning of a residential microgrid

In this work, an accurate energy consumption model of household appliances based on Set of Sequential Uninterruptible Energy Phases (SSUEP) is applied to day-ahead energy management framework of a residential microgrid in order to effectively activate time-based demand response programs. The homes in the microgrid include the essential and/or shiftable household appliances accurately modeled by the SSUEP. These homes are also equipped with the photovoltaic systems, battery energy storages and electric vehicles. The residential microgrid is assumed to be connected to a smart grid such that bi-directional exchange of electric power would be possible. Being aware of the amount of power demand for the appliances and the day-ahead prices of the energy, the consumer provides the required energy from the photovoltaic systems, battery energy storages and electric vehicles (by Vehicle-to-Home and Vehicle-to-Grid capabilities). Moreover, using the flexibility of the shiftable loads, the consumer can be involved in the demand response strategies to reduce the costs. This flexibility is a result of delaying or anticipating the start time and the inter-phase delay modeled by the SSUEP. Lastly, the effects of the accurate SSUEP model on the day-ahead planning of the residential microgrid will be investigated by various scenarios.

Design and development of a low-cost biphasic charge-balanced functional electric stimulator and its clinical validation.

Functional electric stimulators that produce near-ideal, charge-balanced biphasic stimulation waveforms with interphase delay are considered safer and more efficacious than conventional stimulators. An indigenously designed, low-cost, portable FES device named InStim is developed. It features a charge-balanced biphasic single channel. The authors present the complete design, mathematical analysis of the circuit and the clinical evaluation of the device. The developed circuit was tested on stroke patients affected by foot drop problems. It was tested both under laboratory conditions and in clinical settings. The key building blocks of this circuit are low dropout regulators, a DC-DC voltage booster and a single high-power current source OP-Amp with current-limiting capabilities. This allows the device to deliver high-voltage, constant current, biphasic pulses without the use of a bulky step-up transformer. The advantages of the proposed design over the currently existing devices include improved safety features (zero DC current, current-limiting mechanism and safe pulses), waveform morphology that causes less muscle fatigue, cost-effectiveness and compact power-efficient circuit design with minimal components. The device is also capable of producing appropriate ankle dorsiflexion in patients having foot drop problems of various Medical Research Council scale grades.

Spike history model for neural control

There is increased interest from the research community and clinicians to implement closed-loop stimulation strategies in neurobionic devices. That is, to adjust stimulation levels dynamically based on the responses of neural tissue in real time. To adjust electrical stimulation in a closed-loop bionic device, a model-based controller design can be implemented. Here, we collect experimental data from retina slices and use data-driven technique to model neural dynamics. Our motivation comes from visual prostheses. In vitro experiments were conducted on NZ white rabbit retina tissue. Electrical stimulation of the retinal ganglion cells consisted of a train of pulses whose amplitudes had a white Gaussian distribution with zero mean and standard deviation of 1uA. In this pulse train, there were a total of 5000 biphasic pulses with 100µs/phase duration, equal phase amplitude, and no interphase delay. Frequency pulse trains of 25-1000Hz were used. Experimental data were used to characterize the response properties of neurons to the electrical stimulation. The reverse-correlation approach, widely used to predict neural response to light stimulation, was adapted to predict neural response of ganglion cells to electrical stimulation. In contrast to the traditional reverse-correlation schemes, the model proposed here incorporated the history of the response of a neuron. To emphasize this, we call it the “spike history” model. To estimate the responses of cells to electrical stimulation, we used a novel pseudo-random stimulation. To validate the fitness of the model, we performed statistical analysis of the simulated spike trains. In particular, we compared the values of the coefficient of variation of the interspike interval for the experimentally recorded spike train, for the simulated spike train with the history model, and for the simulated spike train using the model without the response kernel. To compare how well the simulated spike train approximated experimentally recorded spikes, we compared the penalty terms for the spike history model and for the model without the response kernel. The penalty term was calculated based on the time difference between each simulated spike and the closest spike in time in the experimentally recorded train. Cells responded to all stimulation frequencies. A phenomena of clusters of spikes followed by periods of suppression was observed in raw spike trains above 200 Hz stimulation. The phenomenon of cluster-suppression with white-noise stimulation may be indicative of memory in the system; i.e., the response depends not only on the current stimulus but also on the responses within a time window preceding the current time. To confirm this, we calculated the auto-correlation function of the recorded spike trains for different frequencies of stimulation. This showed that there was memory in the system for stimulation at frequencies higher than 100Hz. Robustness of the model parameters was confirmed by repeated stimulation of the same cell at the same frequency (up to 20 repetitions). Statistical comparison of the model with history and the model without history confirmed that the model with history approximates experimental data better. The proposed model can be used to design a stimulation strategy to control neural excitation.

Flexible Charge Balanced Stimulator With 5.6 fC Accuracy for 140 nC Injections

Electrical stimulations of neuronal structures must ensure net injected charges to be zero for biological safety and voltage compliance reasons. We present a novel architecture of general purpose biphasic constant current stimulator that exhibits less than 5.6 fC error while injecting 140 nC charges using 1.4 mA currents. The floating current sources and conveyor switch based system can operate in monopolar or bipolar modes. Anodic-first or cathodic-first pulses with optional inter-phase delays have been demonstrated with zero quiescent current requirements at the analog front-end. The architecture eliminates blocking capacitors, electrode shorting and complex feedbacks. Bench-top and in-vivo measurement results have been presented with emulated electrode impedances (resistor-capacitor network), Ag-AgCl electrodes in saline and in-vivo (acute) peripheral nerve stimulations in anesthetized rats.

Optimized single pulse stimulation strategy for retinal implants

Retinal implants offer prospects of vision restoration for some blind patients by eliciting visual percepts of spots of light called ‘phosphenes’. Recently, a mathematical model has been developed that predicts patients' perception of phosphene brightness for current-driven electrical stimulation of the retina. This model is explored for different stimulation parameters on a single electrode, including safety and hardware limitations, to produce phosphenes of specified brightness. We describe a procedure to derive stimulation parameters to account for such constraints, and describe methods to construct optimal stimuli in terms of producing maximal perceived brightness and efficient generation of phosphenes of a given brightness by employing minimal energy. In both cases, it is found that the resulting optimized stimulation waveforms consist of a long stimulation period, and interphase delays between initial and charge-balancing phases.

The effect of the inter-phase delay interval in the spontaneous object recognition test for pigs

In the neuroscience community interest for using the pig is growing. Several disease models have been developed creating a need for validation of behavioural paradigms in these animals. Here, we report the effect of different inter-phase delay intervals on the performance of Göttingen minipigs in the spontaneous object recognition test. The test consisted of a sample and a test phase. First, the pigs explored two similar objects. After a 10-min, 1-h, or 24-h delay two different objects were presented; one familiar from the sample phase and one novel. An exploration-time difference between the novel and the familiar object was interpreted as recognition of the familiar object. We scored the exploration times both manually and automatically, and compared the methods. A strong discrimination between novel and familiar objects after a 10-min inter-phase delay interval and no discrimination after 24 h were found in our set-up of the spontaneous object recognition test. After a 1-h delay, the pigs still showed a significant habituation to the familiar object, but no discrimination was observed. Discrimination between the two objects was mainly confined to the first half of the test phase, and we observed a high between-subject variation. Furthermore, automatic tracking was valid for determination of habituation and discrimination parameters but lead to an overestimation of individual measurements. We conclude that the spontaneous object recognition test for pigs is sensitive to increasing inter-phase delay intervals, and that automatic data acquisition can be applied.

A custom designed chip to control an implantable stimulator and telemetry system for control of paralyzed muscles.

A custom designed chip has been developed for the control of paralyzed muscles. The system is capable of fulfilling the stimulus and telemetry needs of advanced functional neuromuscular stimulation (FNS) applications requiring multiple channels of stimulation and multiple channels for sensor or biopotential sensing. An inductive radiofrequency link provides power to the implant device as well as 2 way transcutaneous communication. An application specific integrated circuit (ASIC) decodes the commands and provides functional control within the implant, and modular circuitry provides specific implant functions. The ASIC chip provides up to 32 independent channels of stimulation with independent control of stimulus pulse duration, pulse amplitude, interphase delay, recharge phase duration, and pulse interval. It can also control up to 8 independent back telemetry analog channels with independent control of sampling rate and pulse powering parameters (amplitude and duration). The mixed analog digital chip has been fabricated in 1.2 microm n-well CMOS technology.

The effect of phase separation on biphasic waveform defibrillation.

It has been hypothesized that the defibrillation efficacy of a biphasic shock is caused by the large change in voltage between the two phases. This study examined the effects of separating the two phases in time thus splitting in half the rapid voltage change at phase reversal. The study was performed in three parts each using six dogs. Part I determined defibrillation thresholds (DFTs) for two exponentially truncated biphasic waveforms (3.5/2 msec and 6/6 msec) with interphase time delays of 0, 1, 2, 3, 4, 6, 8, and 10 msec. In Part II, probability of success curves were generated using an up down method with 15 shocks for each delay for the 3.5/2 msec biphasic waveform with interphase delays of 0, 2, 3, 4, and 5 msec. In Part III, DFTs were determined using a 3.5/2 msec and 6/6 msec biphasic as well as a third waveform that consisted of two sequential 6-msec pulses of the same polarity with interphase delays of 0, 5, 10, 15, 20, 25, 50, and 100 msec. In all three parts the defibrillating cathode was a 6.17 cm2 transvenous spring electrode positioned in the RV apex and the anode was a 113 cm2 cutaneous left chest wall electrode patch. With all waveforms, the trailing edge voltage of the first phase was equal to the negative of the leading edge voltage of the second phase. There was no statistical difference in DFTs or in 50% successful defibrillation points for phase separations from 0 to 6 msec and 0 to 5 msec for Parts I and II, respectively. In Part I there was a significant increase in DFTs for phase separations of 8 and 10 msec compared to a phase separation of 0 msec. In Part III there was no significant difference for separations of 0 and 5 msec; however, there was a significant increase in DFT requirements for separations from 5 to 50 msec, which then decreased with a separation of 100 msec for all three waveforms tested. In conclusion, defibrillation efficacy was unchanged with phase separations up to 6 msec. With phase separation, the rapid voltage change during phase reversal is split in half and, thus, cannot explain the improved efficacy of biphasic waveforms.

The Relationship between Colony-forming Ability and Chromosomal Aberrations Induced in Human T-lymphocytes after γ-Irradiation

Using aliquots from the same samples of irradiated normal human blood, T-lymphocyte survival was measured by (a) 14-day colony growth, (b) the proportion of chromosomally normal first post-irradiation metaphases and (c) the proportion of cells not suffering interphase death and delay within 48 h after irradiation. Combining (b) and (c) gives a prediction of the proportion of cytogenetically undamaged cells which reach metaphase after 48 h. These cells should be capable of producing viable colonies under suitable culture conditions. A comparison of these values with those observed in (a) shows a reasonable agreement in accordance with the hypothesis that gross chromosomal damage and cell reproductive death are closely related.

4456960 Method and device for detecting tool abnormality in machine tools : Hideyuki Wakai, Hirakata, Japan assigned to Kabushiki Kaisha Komatsu Seisakusho

In this work, an accurate energy consumption model of household appliances based on Set of Sequential Uninterruptible Energy Phases (SSUEP) is applied to day-ahead energy management framework of a residential microgrid in order to effectively activate time-based demand response programs. The homes in the microgrid include the essential and/or shiftable household appliances accurately modeled by the SSUEP. These homes are also equipped with the photovoltaic systems, battery energy storages and electric vehicles. The residential microgrid is assumed to be connected to a smart grid such that bi-directional exchange of electric power would be possible. Being aware of the amount of power demand for the appliances and the day-ahead prices of the energy, the consumer provides the required energy from the photovoltaic systems, battery energy storages and electric vehicles (by Vehicle-to-Home and Vehicle-to-Grid capabilities). Moreover, using the flexibility of the shiftable loads, the consumer can be involved in the demand response strategies to reduce the costs. This flexibility is a result of delaying or anticipating the start time and the inter-phase delay modeled by the SSUEP. Lastly, the effects of the accurate SSUEP model on the day-ahead planning of the residential microgrid will be investigated by various scenarios.