Medical image segmentation network based on multi-scale frequency domain filter

With the development of deep learning, medical image segmentation in computer-aided diagnosis has become a research hotspot. Recently, UNet and its variants have become the most powerful medical image segmentation methods. However, these methods suffer from (1) insufficient sensing field and insufficient depth; (2) computational nonlinearity and redundancy of channel features; and (3) ignoring the interrelationships among feature channels. These problems lead to poor network segmentation performance and weak generalization ability. Therefore, first of all, we propose an effective replacement scheme of UNet base block, Double residual depthwise atrous convolution (DRDAC) block, to effectively improve the deficiency of receptive field and depth. Secondly, a new linear module, the Multi-scale frequency domain filter (MFDF), is designed to capture global information from the frequency domain. The high order multi-scale relationship is extracted by combining the depthwise atrous separable convolution with the frequency domain filter. Finally, a channel attention called Axial selection channel attention (ASCA) is redesigned to enhance the network's ability to model feature channel interrelationships. Further, we design a novel frequency domain medical image segmentation baseline method FDFUNet based on the above modules. We conduct extensive experiments on five publicly available medical image datasets and demonstrate that the present method has stronger segmentation performance as well as generalization ability compared to other state-of-the-art baseline methods.

Mass transport to generate the channels in cellulose polymers by vacuum-assisted process

This study developed a pore-connected PP-CA membrane by coating cellulose acetate onto a polypropylene filter. A new method was proposed to attach a CA/glycerin coating layer to a porous PP support without a separate binder. The pores of CA and PP were interconnected using a vacuum filtration device. By adding glycerin to the CA chains, the membrane region became more flexible due to glycerin plasticization. Water passed through the membrane under pressure differences, resulting in the formation of interconnected pores between cellulose acetate and polypropylene. The pore size and quantity could be adjusted by varying the molar ratio of glycerin. Fourier transform infrared spectroscopy revealed the interaction between CA and glycerin, while thermogravimetric analysis showed that the membrane's thermal stability increased by approximately 20 °C after vacuum filtration. This simple and cost-effective manufacturing process holds potential for mass-producing separators in the lithium-ion battery industry.

Purification, Reconstitution, and Functional Analysis of Connexin Hemichannels

Connexins are the proteins that form the gap junction channels that are essential for cell-to-cell communication. These channels are formed by head-to-head docking of hemichannels (each from one of two adjacent cells). Free "undocked" hemichannels at the plasma membrane are mostly closed, although they are still important under physiological conditions. However, abnormal and sustained increase in hemichannel activity due to connexin mutations or acquired conditions can produce or contribute to cell damage. For example, mutations of Cx26, a connexin isoform, can increase hemichannel activity and cause deafness. Studies using purified isolated systems under well-controlled conditions are essential for a full understanding of molecular mechanisms of hemichannel function under normal conditions and in disease, and here, we present methodology for the expression, purification, and functional analysis of hemichannels formed by Cx26.

PS-VTS: particle swarm with visit table strategy for automated emotion recognition with EEG signals

Recognizing emotions accurately in real life is crucial in human-computer interaction (HCI) systems. Electroencephalogram (EEG) signals have been extensively employed to identify emotions. The researchers have used several EEG-based emotion identification datasets to validate their proposed models. In this paper, we have employed a novel metaheuristic optimization approach for accurate emotion classification by applying it to select both channel and rhythm of EEG data. In this work, we have proposed the particle swarm with visit table strategy (PS-VTS) metaheuristic technique to improve the effectiveness of EEG-based human emotion identification. First, the EEG signals are denoised using a low pass filter, and then rhythm extraction is done using discrete wavelet transform (DWT). The continuous wavelet transform (CWT) approach transforms each rhythm signal into a rhythm image. The pre-trained MobilNetv2 model has been pre-trained for deep feature extraction, and a support vector machine (SVM) is used to classify the emotions. Two models are developed for optimal channels and rhythm sets. In Model 1, optimal channels are selected separately for each rhythm, and global optima are determined in the optimization process according to the best channel sets of the rhythms. The best rhythms are first determined for each channel, and then the optimal channel-rhythm set is selected in Model 2. Our proposed model obtained an accuracy of 99.2871% and 97.8571% for the classification of HA (high arousal)-LA (low arousal) and HV (high valence)-LV (low valence), respectively with the DEAP dataset. Our generated model obtained the highest classification accuracy compared to the previously reported methods.

Electrical performance enhancement of MHD microgenerators through the longitudinal shaping of the cross-section

In the present work, the impact that the longitudinal shape of channels has on the current produced in the flow of a magneto-hydrodynamic microgenerator (MHDMG) is studied. The goal is to find the micro-channel geometry via modeling to maximize the current output for low Reynolds and Mach regimes. To carry out this study, a 3D dynamic numerical tool relying on the finite volume method was handled with the open-source software OpenFOAM. It is the base model to study the impact of intricate geometries on the ability to produce energy. An additional steady-state 2D analytical model was also developed to check some basic modeling assumptions. Both models have been experimentally validated on the simplest flow system having a constant square cross-section throughout. The results produced by both models cross-check very well and compare favorably with respect to experimental data. Hence, using the validated numerical tool, three shapes have been further investigated, namely, progressive (linear decrease of the cross-section), arc (parabolic decrease of the cross-section), and wavy (sinusoidal shape). It was found that the arc channel provides the greatest current output for the same volumetric flow. It is therefore the preferred choice for developing high current gain and more efficient MHDMG used in micro-scaled actuators and sensors.

Nutrient carriers at the heart of plant nutrition and sensing

Plants require water and several essential nutrients for their development. The radial transport of nutrients from the soil to the root vasculature is achieved through a combination of three different pathways: apoplastic, symplastic, and transcellular. A common feature for these pathways is the requirement of carriers to transport nutrients across the plasma membrane. An efficient transport of nutrients across the root cell layers relies on a large number of carriers, each of them having their own substrate specificity, tissular and subcellular localization. Polarity is also emerging as a major feature allowing their function. Recent advances on radial transport of nutrients, especially carrier mediated nutrient transport will be discussed in this review, as well as the role of transporters as nutrient sensors.

Characterization of Chlamydomonas voltage-gated calcium channel and its interaction with photoreceptor support VGCC modulated photobehavioral response in the green alga

Calcium (Ca2+) signaling plays a major role in regulating multiple processes in living cells. The photoreceptor potential in Chlamydomonas triggers the generation of all or no flagellar Ca2+ currents that cause membrane depolarization across the eyespot and flagella. Modulation in membrane potential causes changes in the flagellar waveform, and hence, alters the beating patterns of Chlamydomonas flagella. The rhodopsin-mediated eyespot membrane potential is generated by the photoreceptor Ca2+ current or P-current however, the flagellar Ca2+ currents are mediated by unidentified voltage-gated calcium (VGCC or CaV) and potassium channels (VGKC). The voltage-gated ion channel that associates with ChRs to generate Ca2+ influx across the flagella and its cellular distribution has not yet been identified. Here, we identified putative VGCCs from algae and predicted their novel properties through insilico analysis. We further present experimental evidence on Chlamydomonas reinhardtii VGCCs to predict their novel physiological roles. Our experimental evidences showed that CrVGCC4 localizes to the eyespot and flagella of Chlamydomonas and associates with channelrhodopsins (ChRs). Further in silico interactome analysis of CrVGCCs suggested that they putatively interact with photoreceptor proteins, calcium signaling, and intraflagellar transport components. Expression analysis indicated that these VGCCs and their putative interactors can be perturbed by light stimuli. Collectively, our data suggest that VGCCs in general, and VGCC4 in particular, might be involved in the regulation of the photobehavioral response of Chlamydomonas.

The economic impacts of introducing biodegradable fishing gear as a ghost fishing mitigation in the English Channel static gear fishery

We address the economic impacts of the role of Biodegradable Fishing Gear (BFG) as a mitigation measure for the ghost fishing impact of lost fishing gear, through scenarios based on industry interviews. We find that the use of BFG is a technical challenge and not an economic problem. The majority of costs to fishermen in terms of BFG use are not related to investment and maintenance costs rather the impact of reduced fishing efficiency. At the Channel static gear fishery level, we estimate the costs of implementing BFG to be as high as £8 million. If the issue of fishing efficiency was resolved (i.e. BFG was a like-for-like) then the large negative costs could be overturned to between a cost of £880,000 and a small positive benefit of around £150,000. Considering the negative environmental impacts of lost gear, the benefits of BFG use over traditional fishing gear would grow exponentially.

Whole-cell patch-clamp recording and parameters

The patch-clamp technique represents an electrophysiology type of method. This is one of several insightful approaches with five major configurations, namely a loose patch, cell-attached (also known as on-cell), whole-cell, inside-out, and outside-out modes. The patch-clamp method is more advanced compared to classical electrophysiology since it elucidates single-channel activation in a tiny portion of the membrane in addition to action potential (AP), junction potential (JP), endplate potential (EP), electrical coupling between two adjacent cells via Gap junction hemi-channels, excitatory/inhibitory postsynaptic potentials, and resting membrane potential (RMP). In fact, a malfunction of only one channel or even one component will alter AP amplitude or duration in vitro. If parameters are inferred appropriately and recordings are performed properly, the patch-clamp trace readouts and results are robust. The main hallmarks of currents via voltage-dependent calcium (Cav), hyperpolarization-activated cyclic nucleotide gated non-selective cation (HCN), inwardly rectifying potassium (Kir), voltage-dependent potassium (Kv), and voltage-dependent sodium (Nav) channels are similar and tractable among cells even when they are derived from evolutionary distinct organs and species. However, the size of the membrane area, where the functional subunits reside, and current magnitudes vary among cells of the same type. Therefore, dividing current magnitudes by cell capacitance- current density enables the estimate of functional and active channels relative to recorded cytoplasmic membrane area. Since the patch-clamp recordings can be performed in both current- and voltage-clamp modes, the action potential or spike durations can be adequately elucidated. Sometimes, optical methods are preferred to patch-clamp electrophysiology, but the obtained signals and traces are not robust. Finally, not only an alternans of AP durations, but also that of 'action potential shape' is observed with electrophysiology.

Exploring culturally-preferred communication approaches for increased uptake of voluntary medical male circumcision (VMMC) services in rural Malawi

BACKGROUND

In 2007 WHO and UNAIDS recommended communication interventions as a key strategy for creating demand for Voluntary Medical Male Circumcision (VMMC) in Southern Africa. In Malawi, VMMC communication interventions, implemented by health communication agencies, have effectively raised awareness of services. However, high awareness of VMMC has not resulted in increased uptake. Consequently, Malawi has achieved the lowest number of circumcisions in Southern Africa.

METHODS

These researchers carried out a study among the traditionally circumcising Yaos of Mangochi in Southern Region and the non-circumcising Chewas in Central Region. Data were collected using FGDs, KIIs, IDIs, Life Histories and Participatory Rural Appraisal methods. Data were analyzed thematically.

RESULTS

This study demonstrates two lessons. First, Laswell's Theory, which has traditionally been used in politics, is relevant to the health sector where the message delivery continuum also needs to be clear on source, message, audience, channel and intended effects. Secondly, according to informants, allowing communities to give feedback to the VMMC messages delivered by health promoters is fundamental. Therefore, failure by Laswell Theory to emphasize on feedback compromises its efficacy. It weakens its ability to foster a common vision between the source and the audience which is prerequisite for behavioral change.

CONCLUSION

The study concluded that community engagement and interpersonal communication which provide room for real-time feedback in any communicative event are the most preferred communication interventions for VMMC services among Yaos and Chewas.

Decreased heat sensitivity of lungfish TRPV1 revealed by the heterologous expression system

In this study, we focused on TRPV1 of African lungfish, Protopterus annectens. During drought at high temperature, African lungfish can survive by undergoing into aestivation in mud cocoons. Therefore, lungfish is considered to have some specialized heat-sensor, TRPV1, for heat tolerance. Further, lungfish which shares similarities with fishes and amphibians, is one of important species for investigating the fish-tetrapod transition. Since fish TRPV1 and tetrapod TRPV1 have some differences, character of lungfish TRPV1 attracts attention. Here, we first cloned TRPV1 paralogue from lungfish, Protopterus annectens (lfTRPV1) and determined the chemical and thermal sensitivities of lfTRPV1 by two-electrode voltage clamp method using frog oocytes. We detected activation of lfTRPV1 by acid and 2-APB, but capsaicin-induced activation was not observed. The sensitivity to acid of lfTRPV1 was similar to that of rat TRPV1 (rTRPV1), but the 2-APB sensitivity of lfTRPV1 was relatively weaker than rTRPV1. Heat stimulation up to 44 °C did not activate lfTRPV1 and the heat-activation was not detected even on acid condition of pH6. This dramatically decreased heat-sensitivity of TRPV1 may contribute the heat tolerance of African lungfish. Moreover, this might be the property of ancient tetrapod-type TRPV1 gene.

Health communication needs for COVID-19 prevention and control among college students

Objectives: During the early COVID-19 pandemic, college students had to switch to an online learning and online communication environment facing the chances of information overload, misinformation or conflicting information about COVID-19. This study aims to assess the communication needs that have arisen among college students to shed light on the development of a health communication campaign tailored toward college students. Methods: A series of 10 focus group discussions were conducted with 38 total participants. Each group has 2-6 undergraduate or graduate student participants. Nvivo was used to analyze the transcripts. Results: The students reported that they received conflicting information or misinformation. They requested messages with language that was easy to understand with infographics while being culturally appropriate. They advocated for regular and concise email updates from campus leadership. Most participants also preferred COVID-19 control and prevention information on social media. Conclusion: This study revealed the current status and the needs for health information about COVID-19 prevention and control among college students.

Intracardiac Electrogram Targets for Ventricular Tachycardia Ablation

The pathogenesis of ventricular tachycardia (VT) in most patients with a prior myocardial scarring is reentry involving compartmentalized muscle fibers protected within the scar. Often the 12-lead ECG morphology of the VT itself is not available when treated with a defibrillator. Consequently, VT ablation takes on an interesting challenge of finding critical targets in sinus rhythm. High-density recordings are essential to evaluate a substrate based on whole electrogram voltage and activation delay, supplemented with substrate perturbation through alternate site pacing or introducing an extra stimulation. In this article, we discuss contemporary intracardiac electrogram targets for VT ablation, with explanation on each of their specific fundamental physiology.

Functional assay of light-induced ion-transport by rhodopsins

Microbial rhodopsins are photoreceptive membrane proteins found from diverse microorganisms such as archaea, eubacteria, eukaryotes and viruses. Many microbial rhodopsins possess ion-transport activity by light, such as channels and pumps, and ion-transporting rhodopsins are important tools in optogenetics that control animal behavior by light. Historically, molecular mechanism of rhodopsins has been studied by spectroscopic methods for purified proteins. On the other hand, ion-transport function has to be studied by different methods. This chapter introduces two methods of functional assay of ion-transporting rhodopsins by light. One is a patch clamp method using mammalian cells, and another is an ion-transport assay using pH electrode and microbial cells. These functional assay provides fundamental data of ion-transporting rhodopsins, and thus contributes to evaluation for optogenetic tools.

Clinical efficacy and safety of posterior minimally invasive surgery in cervical spondylosis: a systematic review

Background

Posterior minimally invasive surgery has been increasingly used in in recent years for the clinical treatment of cervical spondylosis. However, this treatment remains challenging and has not been comprehensively reported. The aim of this study was to provide a systematic review of posterior minimally invasive treatment for cervical spondylosis to demonstrate the clinical efficacy and safety of this procedure.

Method

We collected information from patients with myelopathy or radiculopathy cervical spondylosis who underwent posterior minimally invasive surgery and verified the clinical efficacy and safety of these surgeries with different measurement indicators from five electronic databases: the Nurick, visual analog scale score, Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), EuroQol Five Dimensions Questionnaire (EQ-5D) score, Short-Form Health Survey Physical Component Summary (SF12-PCS) questionnaire score, Short-Form Health Survey Mental Component Summary (SF12-MCS) questionnaire score, and the MOS item short form health survey (HF-36) score. The decompression effect, cervical spine stability, average surgery time, surgical blood loss volume, length of hospital stay, and related complications were included in the descriptive analysis. Reporting of this protocol followed the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines checklist.

Results

We identified 14 observational studies of cervical spondylosis with 479 patients, mainly including 197 cases of myelopathy and 207 cases of radiculopathy. Channel and endoscopic techniques were used. This study was certified by PROSPERO: CRD42021290074. Significant improvements in the quantitative indicators (Neck-VAS in 9 studies, JOA in 7 studies, NDIs in 5 studies, Nurick, ARM-VAS, and EQ-5D in 2 studies each, and the SF12-PCS, SF12-MCS, and HF-36 in 1 study each) were observed between pre- and postoperation (P < 0.05), and satisfactory clinical significance was acquired in the descriptive indicators [average surgery time (94.56 ± 37.26 min), blood loss volume (68.78 ± 103.31 ml), average length of stay (2.39 ± 1.20 d), and cervical spine stability after surgery]. Additionally, we showed that there was a 4.9% postoperative complication rate and the types of complications that may occur.

Conclusion

Posterior minimally invasive surgery is an effective and safe method for the treatment of cervical spondylosis and is a recommended optional surgical procedure for single-segment myelopathy and radiculopathy.

Structural and functional comparison of magnesium transporters throughout evolution

Magnesium (Mg²⁺) is the most prevalent divalent intracellular cation. As co-factor in many enzymatic reactions, Mg²⁺ is essential for protein synthesis, energy production, and DNA stability. Disturbances in intracellular Mg²⁺ concentrations, therefore, unequivocally result in delayed cell growth and metabolic defects. To maintain physiological Mg²⁺ levels, all organisms rely on balanced Mg²⁺ influx and efflux via Mg²⁺ channels and transporters. This review compares the structure and the function of prokaryotic Mg²⁺ transporters and their eukaryotic counterparts. In prokaryotes, cellular Mg²⁺ homeostasis is orchestrated via the CorA, MgtA/B, MgtE, and CorB/C Mg²⁺ transporters. For CorA, MgtE, and CorB/C, the motifs that form the selectivity pore are conserved during evolution. These findings suggest that CNNM proteins, the vertebrate orthologues of CorB/C, also have Mg²⁺ transport capacity. Whereas CorA and CorB/C proteins share the gross quaternary structure and functional properties with their respective orthologues, the MgtE channel only shares the selectivity pore with SLC41 Na⁺/Mg²⁺ transporters. In eukaryotes, TRPM6 and TRPM7 Mg²⁺ channels provide an additional Mg²⁺ transport mechanism, consisting of a fusion of channel with a kinase. The unique features these TRP channels allow the integration of hormonal, cellular, and transcriptional regulatory pathways that determine their Mg²⁺ transport capacity. Our review demonstrates that understanding the structure and function of prokaryotic magnesiotropic proteins aids in our basic understanding of Mg²⁺ transport.

Fast approximative methods for study of ligand transport and rational design of improved enzymes for biotechnologies

Acceleration of chemical reactions by the enzymes optimized using protein engineering represents one of the key pillars of the contribution of biotechnology towards sustainability. Tunnels and channels of enzymes with buried active sites enable the exchange of ligands, ions, and water molecules between the outer environment and active site pockets. The efficient exchange of ligands is a fundamental process of biocatalysis. Therefore, enzymes have evolved a wide range of mechanisms for repetitive conformational changes that enable periodic opening and closing. Protein-ligand interactions are traditionally studied by molecular docking, whereas molecular dynamics is the method of choice for studying conformational changes and ligand transport. However, computational demands make molecular dynamics impractical for screening purposes. Thus, several approximative methods have been recently developed to study interactions between a protein and ligand during the ligand transport process. Apart from identifying the best binding modes, these methods also provide information on the energetics of the transport and identify problematic regions limiting the ligand passage. These methods use approximations to simulate binding or unbinding events rapidly (calculation times from minutes to hours) and provide energy profiles that can be used to rank ligands or pathways. Here we provide a critical comparison of available methods, showcase their results on sample systems, discuss their practical applications in molecular biotechnologies and outline possible future developments.

Cloning and functional characterization of medaka TRPV4

Medaka, Oryzias latipes is distributed in fresh water of South Asia. To study roles of TRPV4 in osmosensing and adaption mechanism of medaka during changes in salinity environment, we isolated the cDNA for TRPV4 from medaka (olTRPV4) and characterized it. The electrophysiological analysis using Xenopus oocytes revealed that olTRPV4 can be activated by a TRPV4-specific agonist, GSK1016790A and acid at pH 5. Further, olTRPV4 was sensitive to 2-APB. Although warm temperatures activate mammalian TRPV4, olTRPV4 was activated by cold and hot stimulation. The threshold for cold activation was determined as 13.13 ± 0.60 °C, and the heat-activation threshold was 40.26 ± 0.25 °C. Further, when olTRPV4-expressing oocytes were stimulated by hypotonic solution, an apparent activation was observed. We further found that the expression of this hypotonic sensor, olTRPV4 was significantly down-regulated in gills but up-regulated in brains of sea water-acclimated medaka. Results demonstrated that olTRPV4 must function as an osmosensor and play important roles in adaption mechanism of medaka fish in various salinity environments.

Kinetic and thermodynamic modeling of a voltage-gated sodium channel

Like all biological and chemical reactions, ion channel kinetics are highly sensitive to changes in temperature. Therefore, it is prudent to investigate channel dynamics at physiological temperatures. However, most ion channel investigations are performed at room temperature due to practical considerations, such as recording stability and technical limitations. This problem is especially severe for the fast voltage-gated sodium channel, whose activation kinetics are faster than the time constant of the standard patch-clamp amplifier at physiological temperatures. Thus, biologically detailed simulations of the action potential generation evenly scale the kinetic models of voltage-gated channels acquired at room temperature. To quantitatively study voltage-gated sodium channels' temperature sensitivity, we recorded sodium currents from nucleated patches extracted from the rat's layer five neocortical pyramidal neurons at several temperatures from 13.5 to 30 °C. We use these recordings to model the kinetics of the voltage-gated sodium channel as a function of temperature. We show that the temperature dependence of activation differs from that of inactivation. Furthermore, the data indicate that the sustained current has a different temperature dependence than the fast current. Our kinetic and thermodynamic analysis of the current provided a numerical model spanning the entire temperature range. This model reproduced vital features of channel activation and inactivation. Furthermore, the model also reproduced action potential dependence on temperature. Thus, we provide an essential building block for the generation of biologically detailed models of cortical neurons.

Urban drainage channels as microplastics pollution hotspots in developing areas: A case study in Da Nang, Vietnam

This study provides information on the current situation of microplastics contamination in inland freshwater bodies in Vietnam. An urban drainage channel in Da Nang City was selected as a case study. Receiving mainly domestic wastewater and landfill leachate, the channel itself is becoming a microplastic pollution hotspot with a microplastic concentration of 1482.0 ± 1060.4 items m^-3 in waters and 6120.0 ± 2145.7 items kg^-1 in sediments. The dominant shapes of microplastics were fibers and fragments, in which the polymer types were mainly polyethylene, polypropylene, and polyethylene terephthalate. Microplastics with sizes ranging from 1000 to 5000 μm tended to be distributed primarily in surface waters, whereas particles from 300 to 1000 μm accumulated in sediments. The channel places Da Nang Bay at a high risk for microplastic pollution, with an estimated pollution load of approximately 623 × 10⁶ items d^-1 in dry weather.

Regulation of TRPV1 channel activities by intracellular ATP in the absence of capsaicin

Transient receptor potential vanilloid 1 (TRPV1) is a voltage-dependent non-selective cation channel activated by capsaicin, the main pungent ingredient of chili peppers, and noxious heat. Although TRPV1 channels produce outwardly rectifying currents even in the absence of capsaicin, little is known about the regulation mechanism of the TRPV1 currents. In the present study, we found that intracellular ATP regulates the basal activities of TRPV1 channels in a concentration-dependent manner. The ATP-dependent regulation of TRPV1 channels was mediated by phosphoinositides. Moreover, an increase in intracellular ATP concentration negatively shifted voltage-dependent activation of TRPV1 channels. These results suggest that the ATP-dependent production of phosphoinositides regulates the voltage-dependent gating of the basal TRPV1 channel activities in the absence of capsaicin.

exerts analgesic activity by inhibiting NaV1.7 channel

ETHNOPHARMACOLOGICAL RELEVANCE

Allium macrostemon Bunge. is an edible Chinese herb traditionally used for the treatment of thoracic pain, stenocardia, heart asthma and diarrhea. Although its biological potential has been extensively proven such as antioxidant activity, antiplatelet aggregation, vasodilation and antidepressant-like activity, there are no reports in the literature regarding its pharmacological analgesic activity.

AIM OF THE STUDY

The study was carried out to examine the anti-nociceptive activity of the crude extract of A. macrostemon bulbs and interpret its likely molecular target.

MATERIALS AND METHODS

The bulbs of A. macrostemon were gathered, dried-up, and extracted with water (AMWD). AMWD was subjected to activity testing, using chemical-induced (acetic acid and formalin test) and heat-induced (hot plate) pain models. To evaluate the likely mechanistic strategy involved in the analgesic effect of AMWD, whole-cell patch clamp recordings were conducted in acutely dissociated dorsal root ganglion (DRG) neurons and human embryonic kidney 293T (HEK293T) cells expressing pain-related receptors. Electrophysiological methods were employed to detect the action potentials of DRG neurons and potential targets of A. macrostemon.

RESULTS

AMWD showed significant palliative effect in all heat and chemical induced pain assays. Moreover, AMWD significantly reduces the excitability of dorsal root ganglion neurons by reducing the firing frequency of action potentials. Further analysis revealed that voltage-gated sodium channel Nav1.7 is the potential target of A. macrostemon for its analgesic activity.

CONCLUSION

This study has brought new scientific evidence of preclinical efficacy of A. macrostemon as an anti-nociceptive agent. Apparently, these effects are involved with the inhibition of the voltage-sensitive Nav1.7 channel contributing to the reduction of peripheral neuronal excitability. Our present study justifies the folkloric usage of A. macrostemon as a remedy for several pain states. Furthermore, A. macrostemon is a good resource for the development of analgesic drugs targeting Nav1.7 channel.

Human CALHM5: Insight in large pore lipid gating ATP channel and associated neurological pathologies

Recently calcium homeostasis modulators (CALHMs) are identified as ATP release channels play crucial role in functioning of neurons including gustatory signaling and neuronal excitability. Pathologies of Alzheimer's disease and depression have been associated with the dysfunction of CALHMs. Recently, CALHMs has been emerged as an important therapeutic research particularly in neurobiological studies. CALHM1 is most extensively studied among CALHMs and is an ATP and ion channel that is activated by membrane depolarization or removal of extracellular Ca²⁺. Despite the emerged role of CALHM5 shown by an recently assembled data; however, the neuronal function remains obscure until the first Cryo-EM structure of CALHM5 was recently solved by various research group which acts as a template to study the hidden functional properties of the CALHM5 protein based on structure function mechanism. It provides insight in some of the different pathophysiological roles. CALHM5 structure showed an abnormally large pore channel structure assembled as an undecamer with four transmembrane helices (TM1-TM4), an N-terminal helix (NTH), an extracellular loop region and an intracellular C-terminal domain (CTD) that consists of three α-helices CH1-3. The TM1 and NTH were always poorly defined among all CALHMs; however, these regions were well defined in CALHM5 channel structure. In this context, this review will provide insight in structure, function and mechanism to understand its significant role in pathological diseases particularly in Alzheimer's disease. Moreover, it focuses on CALHM5 structure and recent associated properties based on Cryo-EM research.

Mechanisms in cochlear hair cell mechano-electrical transduction for acquisition of sound frequency and intensity

Sound signals are acquired and digitized in the cochlea by the hair cells that further transmit the coded information to the central auditory pathways. Any defect in hair cell function may induce problems in the auditory system and hearing-based brain function. In the past 2 decades, our understanding of auditory transduction has been substantially deepened because of advances in molecular, structural, and functional studies. Results from these experiments can be perfectly embedded in the previously established profile from anatomical, histological, genetic, and biophysical research. This review aims to summarize the progress on the molecular and cellular mechanisms of the mechano-electrical transduction (MET) channel in the cochlear hair cells, which is involved in the acquisition of sound frequency and intensity-the two major parameters of an acoustic cue. We also discuss recent studies on TMC1, the molecule likely to form the MET channel pore.

Effective production of oligomeric membrane proteins by EarlyBac-insect cell system

Despite major advances in methodologies for membrane protein production over the last two decades, there remain challenging protein complexes that are technically difficult to yield by conventional recombinant expression methods. A large number of these proteins are multimeric membrane proteins from eukaryotic species, which are required to pass through stringent quality control mechanisms of host cells for proper folding and complex assembly. Here, we describe the development procedure to improve the production efficiency of multi-oligomeric membrane protein complexes in insect cells and recombinant baculovirus, which involves screening of promoters, enhancers, and untranslated regions for expression levels, using calcium homeostasis modulator (CALHM) and N-methyl-d-aspartate receptor (NMDAR) proteins as examples. We demonstrate that our insect cell expression strategy is effective in expression of both multi-homomeric CALHM proteins and multi-heteromeric NMDARs.

Human Pannexin 1 channel: Insight in structure-function mechanism and its potential physiological roles

Pannexins, large non-gap junction super family exists in vertebrates, play multiple roles in different cellular functions through their ATP release. Panx1-mediated adenosine 5'-triphosphate (ATP) release plays a vital role in physiological and pathophysiological conditions and is known major extracellular molecule in purinergic signaling. To modulate their function in vivo, a proper regulation of channel is necessary. Post-translational modifications are considered to be some regulating mechanisms for PANX1, while PANX2, PANX3 have been uncharacterized to date. Through their significant evidences, PANXs exclude from gap junction and conduits ATP release and other cellular molecules from cells by various mechanisms. PANX1 is most extensive characterized and implicated in ATP signaling and inflammatory processes. Despite the constant advances, much significance of PANX1 in physiological processes remains elusive. Recently, various research groups along with our group have reported the Cryo-EM structure of Panx1 channel and uncovered the hidden functions in structure-function mechanism as well as to provide the clear understanding in physiological and pathophysiological roles. These research groups reported the novel heptameric structure with contains 4 transmembrane helices (TM), two extracellular loops and one intracellular loop with N and C terminus located at the intracellular side. In addition, the structure contains a large pore of which an inhibitor CBX act as a plug that blocking the passage of substrate. In this context, this review will present current mechanistic understanding in structure and function together with significant physiological roles particularly ATP release in health and disease. As such, this review emphasizes on recent functional properties associated with novel heptameric channel and demystifies channel-mediated ATP release function.

Requirement of the Ca2+ channel β2 subunit for sympathetic PKA phosphorylation

Facilitation of cardiac function in response to signals from the sympathetic nervous system is initiated by the phosphorylation of L-type voltage-dependent Ca²⁺ channels (VDCCs) by protein kinase A (PKA), which in turn is activated by β-adrenoceptors. Among the five subunits (α₁, β, α₂/δ, and γ) of VDCCs, the α₁ subunit and the family of β subunits are substrates for PKA-catalyzed phosphorylation; however, the subunit responsible for β-adrenergic augmentation of Ca²⁺ channel function has yet to be specifically identified. Here we show that the VDCC β₂ subunit is required for PKA phosphorylation upon sympathetic acceleration. In mice with β₂ subunit-null mutations, cardiac muscle contraction in response to isoproterenol was reduced and there was no significant increase in Ca²⁺ channel currents upon PKA-dependent phosphorylation. These findings indicate that within the sympathetic nervous system the β₂ subunit of VDCCs is required for physiological PKA-dependent channel phosphorylation.

History and Perspectives of Ion-Transporting Rhodopsins

The first light-sensing proteins used in optogenetics were rhodopsins. The word "rhodopsin" originates from the Greek words "rhodo" and "opsis," indicating rose and sight, respectively. Although the classical meaning of rhodopsin is the red-colored pigment in our eyes, the modern meaning of rhodopsin encompasses photoactive proteins containing a retinal chromophore in animals and microbes. Animal and microbial rhodopsins possess 11-cis and all-trans retinal, respectively, to capture light in seven transmembrane α-helices, and photoisomerizations into all-trans and 13-cis forms, respectively, initiate each function. We are able to find ion-transporting proteins in microbial rhodopsins, such as light-gated channels and light-driven pumps, which are the main tools in optogenetics. In this chapter, historical aspects and molecular properties of rhodopsins are introduced. In the first part, "what is rhodopsin?", general introduction of rhodopsin is presented. Then, molecular mechanism of bacteriorodopsin, a light-driven proton pump and the best-studied microbial rhodopsin, is described. In the section of channelrhodopsin, the light-gated ion channel, molecular properties, and several variants are introduced. As the history has proven, understanding the molecular mechanism of microbial rhodopsins is a prerequisite for useful functional design of optogenetics tools in future.

Molecular mechanisms of trigeminal neuralgia: A systematic review

OBJECTIVE

To conduct a systematic review of the available literature for primary research articles identifying potential gene mutations, polymorphisms and other molecular regulatory mechanisms related to trigeminal neuralgia in order to identify the genetic and molecular models of primary trigeminal neuralgia currently being investigated.

METHODS

PubMed and Web of Science were systematically searched to identify primary research articles discussing genetic predictors of trigeminal neuralgia and neuropathic pain that were published prior to July 2020. This review was conducted according to PRISMA guidelines.

RESULTS

Out of the 333 articles originally identified, a total of 14 papers were selected for study inclusion. These articles included 5 human studies, 6 mouse studies and 3 rat studies. Four articles investigated sodium channels, 1 investigated a sodium channel and nerve growth factor receptor, 2 investigated potassium channels, 1 investigated calcium channels, 1 investigated the downstream regulatory element antagonist modulator protein, 1 investigated the dynorphin-kappa opioid receptor system, 1 investigated TRPA1, 1 investigated the Nrg1/ErbB3/ErbB2 signaling complex, 1 investigated a serotonin transporter and 1 investigated potassium channels, sodium channels, calcium channels, chloride channels, TRP channels and gap junctions.

CONCLUSION

Researchers have identified multiple genetic and molecular targets involved with potential pathophysiologies that have a relationship to the creation of trigeminal neuralgia. At this time, there does not seem to be clear causal frontrunner, demonstrating the possibility that genetic predisposition to trigeminal neuralgia may involve multiple genes and/or downstream products, such as ion channels.

Spiralling curve characterization of nitrate-nitrogen absorption in a channel at a rural-urban ecotone in Northeast China

To determine the dynamic change characteristics of NO₃-N in a rural-urban ecotone channel, five tracer tests were conducted in the Dongda Channel in the suburbs of Changchuan city, Jilin province, China, from October 2016 to April 2017. NaBr was used as conservative tracer and KNO₃ served as an added nutritive salt. The kinetic features of NO₃-N were simulated via the addition of tracers and by employing the spiralling curve characterization approach and the Michaelis-Menten (M-M) equation. The average absorption length of NO₃^--N background concentration (S_w-amb) is 199 m, which is much less than the discharge channel length (2.5 km), thereby suggesting that the channel has a strong NO₃-N retention potential. Moreover, the M-M equation fits well the kinetic features of NO₃-N adsorption. The average maximum absorption rate and subsaturation constant are 631 μg (m² s)^-1 and 1.46 mg L^-1, respectively. The correlation analysis reveals that S_w-amb and NO₃^--N absorption rates (NO₃-N_amb) are significantly negatively correlated whereas the absorption rates of NO₃^--N background concentration (U_amb) and NO₃-N_amb are significantly positively correlated. The other spiralling indices show faint correlations with the background concentration of NO₃-N. Meanwhile, the hydrological factors slightly influence NO₃-N retention, but the geomorphic features of the channel, including (width residual) Ф_w and (cross-sectional area residual) Ф_A, have significant correlations with most spiralling indices, thereby highlighting the relatively important roles of geomorphic features in NO₃-N retention.

Gating and calcium-sensing mechanisms of TRPA1 channels revealed

Novel structures of the human TRPA1 channel were determined in the presence of the agonist iodoacetamide and the antagonist A-967079, to reveal the open and closed states of the channel, respectively. The structures further revealed the location of Ca²⁺ modulatory site that is likely conserved among several TRP subgroups.

Pannexin 1 Channels as a Therapeutic Target: Structure, Inhibition, and Outlook

Pannexin 1 (Panx1) channels are transmembrane proteins that release adenosine triphosphate and play an important role in intercellular communication. They are widely expressed in somatic and nervous system tissues, and their activity has been associated with many pathologies such as stroke, epilepsy, inflammation, and chronic pain. While there are a variety of small molecules known to inhibit Panx1, currently little is known about the mechanism of channel inhibition, and there is a dearth of sufficiently potent and selective drugs targeting Panx1. Herein we provide a review of the current literature on Panx1 structural biology and known pharmacological agents that will help provide a basis for rational development of Panx1 chemical modulators.

Mitochondrial F-ATP synthase as the permeability transition pore

The current state of research on the mitochondrial permeability transition pore (PTP) can be described in terms of three major problems: molecular identity, atomic structure and gating mechanism. In this review these three problems are discussed in the light of recent findings with special emphasis on the discovery that the PTP is mitochondrial F-ATP synthase (mtF_oF₁). Novel features of the mitochondrial F-ATP synthase emerging from the success of single particle cryo electron microscopy (cryo-EM) to determine F-ATP synthase structures are surveyed along with their possible involvement in pore formation. Also, current findings from the gap junction field concerning the involvement of lipids in channel closure are examined. Finally, an earlier proposal denoted as the 'Death Finger' is discussed as a working model for PTP gating.

Microinjection of urotensin II into the rostral ventrolateral medulla increases sympathetic vasomotor tone via the GPR14/ERK pathway in rats

The present study aimed to reveal the effects of urotensin II (UII) on sympathetic vasomotor tone in the rostral ventrolateral medulla (RVLM). UII (0.3, 3, and 30 nmol/L, 50 nL) was microinjected into the RVLM. Blood pressure (BP), heart rate (HR), and renal sympathetic nerve activity (RSNA) were measured to determine the sympathetic vasomotor tone. BP, HR, and RSNA were simultaneously recorded after drugs had been microinjected into the RVLM. Microinjection of UII (0.3, 3, and 30 nmol/L, 50 nL) into the RVLM significantly increased BP, HR, and RSNA. Pretreatment with BIM23127 (300 nmol/L, 50 nL), a potent antagonist of the UII receptor GPR14, abolished the effect of UII. Previous microinjection of PD98059 (25 μmol/L, 50 nL), an inhibitor of ERK, significantly suppressed the effects of UII. Preinjection of an inhibitor of the N-type Ca²⁺ channel, ω-conotoxin GVIA (50 nmol/L, 50 nL), inhibited the effects of UII. The present study demonstrated that microinjection of UII into the RVLM significantly increased sympathetic vasomotor tone, which was mediated by the GPR14/ERK/N-type Ca²⁺ channel pathway. UII may become a novel therapeutic target for autonomic nervous system regulation, especially in hypertension.

Biophysics of rhodopsins and optogenetics

Rhodopsins are photoreceptive proteins and key tools in optogenetics. Although rhodopsin was originally named as a red-colored pigment for vision, the modern meaning of rhodopsin encompasses photoactive proteins containing a retinal chromophore in animals and microbes. Animal and microbial rhodopsins respectively possess 11-cis and all-trans retinal, respectively. As cofactors bound with their animal and microbial rhodopsin (seven transmembrane α-helices) environments, 11-cis and all-trans retinal undergo photoisomerization into all-trans and 13-cis retinal forms as part of their functional cycle. While animal rhodopsins are G protein coupled receptors, the function of microbial rhodopsins is highly divergent. Many of the microbial rhodopsins are able to transport ions in a passive or an active manner. These light-gated channels or light-driven pumps represent the main tools for respectively effecting neural excitation and silencing in the emerging field of optogenetics. In this article, the biophysics of rhodopsins and their relationship to optogenetics are reviewed. As history has proven, understanding the molecular mechanism of microbial rhodopsins is a prerequisite for their rational exploitation as the optogenetics tools of the future.

Retirement Effect on Health Status and Health Behaviors in Urban China

This paper analyzes the causal impact of retirement in China on Body Mass Index (BMI) and weight, which are a good gauge of the risk for some diseases. Many middle income developing countries are aging very rapidly and may have to adjust the retirement age to have financially feasible government budgets. It is important to know and understand any plausible health consequences of raising the retirement age in developing countries, and which sub-populations within these countries may be most affected. By using 2011, 2013 and 2015 waves of the China Health and Retirement Longitudinal Study (CHARLS), our identification strategy uses variation in China's mandatory retirement age with a fuzzy discontinuity design to examine an exogenous shock to retirement behavior. Our study finds that retirement will increase weight and BMI among men. This effect is much larger for men with low education. The channel may be that men with low education drink more and take less vigorous exercises after they get retired. Retirement does not affect weight and BMI for women. These effects are robust with different definitions of retirement, narrow retirement bandwidth for samples as well as dropping samples with rural Hukou.

Who buys nets? Factors associated with ownership and use of purchased mosquito nets in sub-Saharan Africa

BACKGROUND

Public sector strategies to promote insecticide-treated net (ITN) access have resulted in increased ITN ownership across sub-Saharan Africa. However, the current status of the private sector distribution channel for nets has not been fully explored. This multi-country study explored the prevalence of net purchases and the characteristics of households that had purchased nets and used such nets in sub-Saharan Africa.

METHODS

Data from recent Malaria Indicator Survey (MIS) or Demographic and Health Survey (DHS) in 16 countries were analysed to explore the prevalence of purchased nets. Purchased nets were defined as nets obtained from shops/markets or pharmacies. Additional sub-analysis of factors associated with ownership and use of purchased nets was conducted in seven countries with over 10% of nets reported as purchased. Key outcomes included: prevalence of purchased nets out of all nets, household ownership of a purchased net, and whether a purchased net was used the previous night. Analytical methods included country level tests of association and multivariable logistic regressions.

RESULTS

Among all nets, the proportion of purchased nets in the study countries ranged from 0.8 to 32.7% and most (median = 77%) of these purchased nets were ITNs. Although the private nets are presumed to be from the retail, non-public sector, the prevalence of treated purchased nets suggests that some purchased nets may be "leaked" ITNs from public sector distributions, and thus, may be an informal sector rather than part of the formal "private sector". Urban, wealthier households as well as those with educated heads were more likely to own purchased nets. Use of such nets was, however, lower in wealthier households. In addition, net use was higher in households owning insufficient nets for their family size, and when the nets were newer than 24 months.

CONCLUSION

The formal and informal private sector have played a role in bolstering net access rates in some settings. Study findings can help relevant malaria control stakeholders gain insight on the contribution of purchased nets on their overall ITN strategy, identify potential target populations for private sector nets as well as inform the design and distribution of private sector insecticide-treated nets that appeal to their target groups.

Unique high sensitivity to heat of axolotl TRPV1 revealed by the heterologous expression system

The thermosensation mechanism plays critical roles in various animals living in different thermal environment. We focused on an axolotl, which is a tailed amphibian originally from Lake Xochimilco area in the Vally of Mexico, and examined its behavior response to heat stimulation. Mild heat at 33 °C induced noxious locomotive activity to axolotls, but the noxious response of another tailed amphibian, Iberian ribbed newt, was not observed at 33 °C. To explore the mechanism for the temperature sensitivity of axolotls, we isolated a cDNA of TRPV1. Using the degenerate primer PCR method, we identified the DNA fragment encoding axolotl TRPV1 (axTRPV1), and then cloned a full-length cDNA. We studied the chemical and thermal sensitivities of axTRPV1 by two-electrode voltage clamp method using Xenopus oocyte expression system. Capsaicin, acid, and 2-aminoethoxydiphenylborane apparently activated axTRPV1 channels in a dose-dependent manner. The analysis of thermal sensitivity showed that axTRPV1 was significantly activated by heat but not by cold. The average temperature threshold for heat-activation was 30.95 ± 0.12 °C. This thermal activation threshold of axTRPV1 is unique and significantly low, when compared with the known thresholds of TRPV1s from various animals. Further, this threshold of axTRPV1 is well consistent with the observation of heat-induced behavior of axolotls at 33 °C, demonstrating that axolotl shows noxious response to mild heat mediated through axTRPV1.

Solid-State NMR Approaches to Study Protein Structure and Protein-Lipid Interactions

Solid-state NMR spectroscopy has been developed for the investigation of membrane-associated polypeptides and remains one of the few techniques to reveal high-resolution structural information in liquid-disordered phospholipid bilayers. In particular, oriented samples have been used to investigate the structure, dynamics and topology of membrane polypeptides. Much of the previous solid-state NMR work has been developed and performed on peptides but the technique is constantly expanding towards larger membrane proteins. Here, a number of protocols are presented describing among other the reconstitution of membrane proteins into oriented membranes, monitoring membrane alignment by ³¹P solid-state NMR spectroscopy, investigations of the protein by one- and two-dimensional ¹⁵N solid-state NMR and measurements of the lipid order parameters using ²H solid-state NMR spectroscopy. Using such methods solid-state NMR spectroscopy has revealed a detailed picture of the ensemble of both lipids and proteins and their mutual interdependence in the bilayer environment.

Engineering enzyme access tunnels

Enzymes are efficient and specific catalysts for many essential reactions in biotechnological and pharmaceutical industries. Many times, the natural enzymes do not display the catalytic efficiency, stability or specificity required for these industrial processes. The current enzyme engineering methods offer solutions to this problem, but they mainly target the buried active site where the chemical reaction takes place. Despite being many times ignored, the tunnels and channels connecting the environment with the active site are equally important for the catalytic properties of enzymes. Changes in the enzymatic tunnels and channels affect enzyme activity, specificity, promiscuity, enantioselectivity and stability. This review provides an overview of the emerging field of enzyme access tunnel engineering with case studies describing design of all the aforementioned properties. The software tools for the analysis of geometry and function of the enzymatic tunnels and channels and for the rational design of tunnel modifications will also be discussed. The combination of new software tools and enzyme engineering strategies will provide enzymes with access tunnels and channels specifically tailored for individual industrial processes.

Ca2+ to the rescue - Ca2+channels and signaling in plant immunity

Ca²⁺ is a universal second messenger in many signaling pathways in all eukaryotes including plants. Transient changes in [Ca²⁺]cyt are rapidly generated upon a diverse range of stimuli such as drought, heat, wounding, and biotic stresses (infection by pathogenic and symbiotic microorganisms), as well as developmental cues. It has been known for a while that [Ca²⁺]cyt transient signals play crucial roles to activate plant immunity and recently significant progresses have been made in this research field. However the identity and regulation of ion channels that are involved in defense related Ca²⁺ signals are still enigmatic. Members of two ligand gated ion channel families, glutamate receptor-like channels (GLRs) and cyclic nucleotide-gated channels (CNGCs) have been implicated in immune responses; nevertheless more precise data to understand their direct involvement in the creation of Ca²⁺ signals during immune responses is necessary. Furthermore, the study of other ion channel groups is also required to understand the whole picture of the intra- and inter-cellular Ca²⁺ signalling network. In this review we summarize Ca²⁺ signals in plant immunity from an ion channel point of view and discuss future challenges in this exciting research field.

Loss of cytosolic Mg2+ binding sites in the Thermotoga maritima CorA Mg2+ channel is not sufficient for channel opening

The CorA Mg²⁺ channel is a homopentamer with five-fold symmetry. Each monomer consists of a large cytoplasmic domain and two transmembrane helices connected via a short periplasmic loop. In the Thermotoga maritima CorA crystal structure, a Mg²⁺ is bound between D89 of one monomer and D253 of the adjacent monomer (M1 binding site). Release of Mg²⁺ from these sites has been hypothesized to cause opening of the channel. We generated mutants to disrupt Mg²⁺ interaction with the M1 site. Crystal structures of the D89K/D253K and D89R/D253R mutants, determined to 3.05 and 3.3 Å, respectively, showed no significant structural differences with the wild type structure despite absence of Mg²⁺ at the M1 sites. Both mutants still appear to be in the closed state. All three mutant CorA proteins exhibited transport of ⁶³Ni²⁺, indicating functionality. Thus, absence of Mg²⁺ from the M1 sites neither causes channel opening nor prevents function. We also provide evidence that the T. maritima CorA is a Mg²⁺ channel and not a Co²⁺ channel.

Molecular regulation of MCU: Implications in physiology and disease

Ca2+ flux across the inner mitochondrial membrane (IMM) regulates cellular bioenergetics, intra-cellular cytoplasmic Ca2+ signals, and various cell death pathways. Ca2+ entry into the mitochondria occurs due to the highly negative membrane potential (ΔΨm) through a selective inward rectifying MCU channel. In addition to being regulated by various mitochondrial matrix resident proteins such as MICUs, MCUb, MCUR1 and EMRE, the channel is transcriptionally regulated by upstream Ca2+ cascade, post transnational modification and by divalent cations. The mode of regulation either inhibits or enhances MCU channel activity and thus regulates mitochondrial metabolism and cell fate.

An experimental investigation of head loss through a triangular "V- shaped" screen

Common traditional screens (screens perpendicular and vertical to the flow direction) face extensive problems with screen blockage, which can result in adverse hydraulic, environmental, and economic consequences. Experimentally, this paper presents an advanced trash screen concept to reduce traditional screen problems and improve the hydraulic performance of screens. The traditional screen is re-developed using a triangular V shape with circular bars in the flow direction. Triangular V-shaped screen models with different angles, blockage ratios, circular bar designs, and flow discharges were tested in a scaled physical model. The analyses provide promising results. The findings showed that the head loss coefficients were effectively reduced by using the triangular V-shaped screens with circular bars (α < 90°) in comparison with the traditional trash screen (α = 90). Additionally, the results indicated that the head loss across the screen increased with increasing flow discharge and blockage ratio. The losses considerably increase by large percentages when the screen becomes blocked by 40%. Low head losses were recorded at low screen angles for the circular bars. A new head loss equation is recommended for triangular screens with circular bars.

Effect of Site-Specific Intermolecular Lysine-Tryptophan Interactions on the Aggregation of Gramicidin-Based Peptides Leading to Pore Formation in Lipid Membranes

In contrast to the parent pentadecapeptide gramicidin A (gA), some of its cationic analogs have been shown previously to form large-diameter pores in lipid membranes. These pores are permeable to fluorescent dyes, which allows one to monitor pore formation by using the fluorescence de-quenching assay. According to the previously proposed model, the gA analog with lysine substituted for alanine at position 3, [Lys3]gA, forms pores by a homopentameric assembly of gramicidin double-stranded β-helical dimers. Here, we studied the newly synthesized analogs of [Lys3]gA with single, double and triple substitutions of isoleucines for tryptophans at positions 9, 11, 13, and 15. Replacement of any of the tryptophans of [Lys3]gA with isoleucine resulted in suppression of the pore-forming activity of the peptide, the effect being significantly dependent on the position of tryptophans. In particular, the peptide with a single substitution of tryptophan 13 showed much lower activity than the analogs with single substitutions at positions 9, 11, or 15. Of the peptides with double substitutions, the strongest suppression of the leakage was observed with tryptophans 13 and 15. In the case of triple substitutions, only the peptide retaining tryptophan 11 exhibited noticeable activity. It is concluded that tryptophans 11 and 13 contribute most to pore stabilization in the membrane, whereas tryptophan 9 is not so important for pore formation. Cation-π interactions between the lysine and tryptophan residues of the peptide are suggested to be crucial for the formation of the [Lys3]gA pore.

Bacterial denitrifying nitric oxide reductases and aerobic respiratory terminal oxidases use similar delivery pathways for their molecular substrates

The superfamily of heme‑copper oxidoreductases (HCOs) include both NO and O₂ reductases. Nitric oxide reductases (NORs) are bacterial membrane enzymes that catalyze an intermediate step of denitrification by reducing nitric oxide (NO) to nitrous oxide (N₂O). They are structurally similar to heme‑copper oxygen reductases (HCOs), which reduce O₂ to water. The experimentally observed apparent bimolecular rate constant of NO delivery to the deeply buried catalytic site of NORs was previously reported to approach the diffusion-controlled limit (10⁸-10⁹ M^-1 s^-1). Using the crystal structure of cytochrome-c dependent NOR (cNOR) from Pseudomonas aeruginosa, we employed several protocols of molecular dynamics (MD) simulation, which include flooding simulations of NO molecules, implicit ligand sampling and umbrella sampling simulations, to elucidate how NO in solution accesses the catalytic site of this cNOR. The results show that NO partitions into the membrane, enters the enzyme from the lipid bilayer and diffuses to the catalytic site via a hydrophobic tunnel that is resolved in the crystal structures. This is similar to what has been found for O₂ diffusion through the closely related O₂ reductases. The apparent second order rate constant approximated using the simulation data is ~5 × 10⁸ M^-1 s^-1, which is optimized by the dynamics of the amino acid side chains lining in the tunnel. It is concluded that both NO and O₂ reductases utilize well defined hydrophobic tunnels to assure that substrate diffusion to the buried catalytic sites is not rate limiting under physiological conditions.

Ion and metabolite transport in the chloroplast of algae: lessons from land plants

Chloroplasts are endosymbiotic organelles and play crucial roles in energy supply and metabolism of eukaryotic photosynthetic organisms (algae and land plants). They harbor channels and transporters in the envelope and thylakoid membranes, mediating the exchange of ions and metabolites with the cytosol and the chloroplast stroma and between the different chloroplast subcompartments. In secondarily evolved algae, three or four envelope membranes surround the chloroplast, making more complex the exchange of ions and metabolites. Despite the importance of transport proteins for the optimal functioning of the chloroplast in algae, and that many land plant homologues have been predicted, experimental evidence and molecular characterization are missing in most cases. Here, we provide an overview of the current knowledge about ion and metabolite transport in the chloroplast from algae. The main aspects reviewed are localization and activity of the transport proteins from algae and/or of homologues from other organisms including land plants. Most chloroplast transporters were identified in the green alga Chlamydomonas reinhardtii, reside in the envelope and participate in carbon acquisition and metabolism. Only a few identified algal transporters are located in the thylakoid membrane and play role in ion transport. The presence of genes for putative transporters in green algae, red algae, diatoms, glaucophytes and cryptophytes is discussed, and roles in the chloroplast are suggested. A deep knowledge in this field is required because algae represent a potential source of biomass and valuable metabolites for industry, medicine and agriculture.

Low impedance nature of 12 acupoints on the limbs, and the unexpected dependence on limb angle

OBJECTIVE

To better understand the working mechanism of acupuncture, we investigated the skin electrical impedance distribution around acupoints, and the impedance changes at 12 original acupoints bilaterally after bending the limbs.

METHODS

We measured the skin electrical impedance in three study subjects in the frequency range of 40 to 10 kHz using the four-electrode method with a sharp probe and a large reference electrode. A measurement matrix of 7 mm ¡Á 7 mm with spacing of 2.0 (or 3.0) mm was measured to obtain 2D impedance mapping of acupoints. The impedance spectra of 12 original acupoints were measured at the 0? position and the 90? position.

RESULTS

The electrical impedance of some acupoints, such as Yangchi (TE 4), was 16 times lower than that of the surrounding area, showing a recognizable small central area of low impedance with a diameter of less than 4 mm. In contrast, other acupoints, such as Laogong (PC 8), had an electrical impedance that was not significantly different from that of the surrounding area. When the limb was bent from a straight position (0?) to a vertical position (90?), the electrical impedance of the 12 original acupoints showed varied trends, either increasing or decreasing by a factor of up to ten times, or remaining at the same level.

CONCLUSION

Not all acupoints tested show the property of low impedance, which might be related to the varied depth of the openings of superficial collaterals. The unexpected dependence of acupoint impedance on limb angle is a novel discovery, which implies that the channel paths are located in interstitial structures in the limbs. It might be possible to determine an optimized limb position for each particular acupuncture treatment in clinical practice.

Analyzing the channel dopant profile in next-generation FinFETs via atom probe tomography

Dopant analysis in next-generation semiconductor devices has become increasingly difficult for traditionally used analytical techniques. Atom probe tomography has been viewed by some as a possible solution to these challenges because of its three-dimensional capabilities, forcing the atom probe to mature at a rapid pace in this particular field. This work presents a well-rounded analysis of how APT can be used to examine B dopant diffusion into the channel of a next-generation FinFET, where the channel dimensions and the number of dopants atoms are significantly smaller than any devices measured by APT to date. Complimentary EELS analysis of the gate and channel provides a better understanding of how distortions and artifacts in the APT reconstruction affect the overall integrity of the dataset. Dopant measurements in the channel are confirmed through in-depth mass spectrum analysis and compared with values proposed by TCAD modeling.

Magnesium Extravaganza: A Critical Compendium of Current Research into Cellular Mg(2+) Transporters Other than TRPM6/7

Magnesium research has boomed within the last 20 years. The real breakthrough came at the start of the new millennium with the discovery of a plethora of possible Mg homeostatic factors that, in particular, included putative Mg²⁺ transporters. Until that point, Mg research was limited to biochemical and physiological work, as no target molecular entities were known that could be used to explore the molecular biology of Mg homeostasis at the level of the cell, tissue, organ, or organism and to translate such knowledge into the field of clinical medicine and pharmacology. Because of the aforementioned, Mg²⁺ and Mg homeostasis, both of which had been heavily marginalized within the biomedical field in the twentieth century, have become overnight a focal point of many studies ranging from primary biomedical research to translational medicine.The amount of literature concerning cellular Mg²⁺ transport and cellular Mg homeostasis is increasing, together with a certain amount of confusion, especially about the function(s) of the newly discovered and, in the majority of instances, still only putative Mg²⁺ transporters/Mg²⁺ homeostatic factors. Newcomers to the field of Mg research will thus find it particularly difficult to orient themselves.Here, we briefly but critically summarize the status quo of the current understanding of the molecular entities behind cellular Mg²⁺ homeostasis in mammalian/human cells other than TRPM6/7 chanzymes, which have been universally accepted as being unspecific cation channel kinases allowing the flux of Mg²⁺ while constituting the major gateway for Mg²⁺ to enter the cell.