Identification, structural, and biophysical characterization of a positive modulator of human Kv3.1 channels.

Voltage-gated potassium channels (Kv) are tetrameric membrane proteins that provide a highly selective pathway for potassium ions (K+) to diffuse across a hydrophobic cell membrane. These unique voltage-gated cation channels detect changes in membrane potential and, upon activation, help to return the depolarized cell to a resting state during the repolarization stage of each action potential. The Kv3 family of potassium channels is characterized by a high activation potential and rapid kinetics, which play a crucial role for the fast-spiking neuronal phenotype. Mutations in the Kv3.1 channel have been shown to have implications in various neurological diseases like epilepsy and Alzheimer's disease. Moreover, disruptions in neuronal circuitry involving Kv3.1 have been correlated with negative symptoms of schizophrenia. Here, we report the discovery of a novel positive modulator of Kv3.1, investigate its biophysical properties, and determine the cryo-EM structure of the compound in complex with Kv3.1. Structural analysis reveals the molecular determinants of positive modulation in Kv3.1 channels by this class of compounds and provides additional opportunities for rational drug design for the treatment of associated neurological disorders.

[Clinical effect of Kirschner wire intramedullary fixation in the treatment of pediatric both-bone forearm fractures at high altitude area].

OBJECTIVE: To explore the clinical effect of Kirschner wire intramedullary fixation in the treatment of both-bone forearm fractures in children of high altitude area. METHODS: From August 2020 to December 2021, 19 children were treated with Kirschner wire intramedullary fixation including 11 males and 8 females, aged from 4 to 13 years old with an average of (8.16±2.71) years old. The course of disease was 1 to 10 days, with a mean of (4.11±2.51) d. First, close reduction was performed. If the reduction was unsuccessful, limited open reduction was performed, followed by Kirschner wire intramedullary fixation of the radius and ulna. The fracture healing was evaluated by X-ray after operation, and the curative effect was evaluated by Anderson forearm function score standard. RESULTS: The wound healed well after operation, 2 cases had clinical manifestations of needle tail irritation after operation, and the symptoms disappeared after removing the internal fixation. The average follow-up time was(7.68±3.50) months (3 to 14 months). X-ray showed that all fracture healing in follow-up, Anderson forearm function score showed excellent in 16 cases, good in 2 cases and fair in 1 case at the final follow-up. CONCLUSION: Children with fractures in plateau areas often have delayed medical treatment, lack of medical conditions and insufficient compliance. Based on these characteristics, Kirschner wire intramedullary fixation for the treatment of children's double forearm fractures has the advantages of small injury and rapid recovery. It is a kind of operation method that can be popularized.

[Treatment of spinal burst fractures with pedicle screw fixation at high altitude area].

OBJECTIVE: According to the characteristics of spinal burst fractures in high-altitude areas and the local medical conditions, to explore the clinical efficacy of short-segment fixation with pedicle screws combined with screw placement in injured vertebrae in the treatment of thoracolumbar burst fractures. METHODS: From August 2018 to December 2021, 12 patients with single-vertebral thoracolumbar burst fractures without neurological symptoms were treated with injured vertebral screw placement technique, including 7 males and 5 females;aged 29 to 54 years old, with an average of(42.50±7.95) years old;6 cases of traffic accident injury, 4 cases of high fall injury, 2 cases of heavy object injury;2 cases of T11, 4 cases of T12, 3 cases of L1, 2 cases of L2, and 1 case of L3. In the operation, screws were first placed in the upper and lower vertebrae of the fracture, pedicle screws were placed in the injured vertebra, and connecting rods were installed, and the fractured vertebral body was reset by positioning and distraction. Visual analogue scale (VAS) and Japanese Orthopedic Association (JOA) scoring were used to evaluate the changes in pain and quality of life of patients, and the kyphotic correction rate and correction loss rate of the injured segment were measured by X-ray. RESULTS: All operations were successful without significant intraoperative complications. All 12 patients were followed up, the duration ranged from 9 to 27 months, with an mean of (17.75±5.79) months. VAS at 3 days after operation was significantly higher than that at admission (t=6.701, P=0.000). There was significant difference in JOA score between 9 months after operation and at admission (t=5.085, P=0.000). Three days after operation, Cobb angle was (4.42±1.16)°, and the correction rate was (82±5)% compared with (25.67±5.71)° at admission. Cobb angle was (5.08±1.24) °at 9 months after operation, with a corrected loss rate of (16±13)%. No loosening or breakage of internal fixation was found. CONCLUSION: Under the high-altitude hypobaric and hypoxic environment, the effect of the operation should be ensured while reducing the trauma. The application of the technique of placing screws on the injured vertebra can effectively restore and maintain the height of the injured vertebra, with less bleeding and shorter fixed segments, which is an effective method.

Developmental neuronal origin regulates neocortical map formation.

Sensory neurons in the neocortex exhibit distinct functional selectivity to constitute the neural map. While neocortical map of the visual cortex in higher mammals is clustered, it displays a striking "salt-and-pepper" pattern in rodents. However, little is known about the origin and basis of the interspersed neocortical map. Here we report that the intricate excitatory neuronal kinship-dependent synaptic connectivity influences precise functional map organization in the mouse primary visual cortex. While sister neurons originating from the same neurogenic radial glial progenitors (RGPs) preferentially develop synapses, cousin neurons derived from amplifying RGPs selectively antagonize horizontal synapse formation. Accordantly, cousin neurons in similar layers exhibit clear functional selectivity differences, contributing to a salt-and-pepper architecture. Removal of clustered protocadherins (cPCDHs), the largest subgroup of the diverse cadherin superfamily, eliminates functional selectivity differences between cousin neurons and alters neocortical map organization. These results suggest that developmental neuronal origin regulates neocortical map formation via cPCDHs.

Wide field of view chiral imaging with a liquid crystal planar lens enabled by digitalized nanogratings.

To compensate for the inability for polarization imaging by conventional methods, metasurface optics with compactness and multi-function emerge as an approach to provide images with different linear and circular polarizations. Here, we propose a liquid crystal (LC) geometric phase-based chiral imaging lens (CIL) that simultaneously forms images of objects with opposite helicity. The CIL (Diameter 2.3 cm) was optimized by a spatial multiplexing algorithm and realized using the digital holography technique, where the LC domains were regulated by pixelated nanogratings with varied orientation. We investigated the potential of the patterning technique toward high order LC alignment by balancing the periodicity and depth of the nanogratings. The CIL exhibited a wide field of view of ±20°, which is attributed to the self- assembling effects of LC molecules. The compactness, lightness, and ability to produce chiral images of the LC CIL even at large angles have significant potential for practical polarization imaging.

High-throughput and controllable manufacturing of liquid crystal polymer planar microlens array for compact fingerprint imaging.

The microlens array (MLA) with a small geometric footprint and unique performances, is the key enabler to push the development of photonic devices toward miniaturization, multi-function and large-scale integration. However, the realization of 100% fill-factor (FF) MLAs with high controllability and its mass manufacturing without complex steps has always been a difficult issue. Here, we propose an efficient, highly flexible and low-cost manufacturing approach for MLAs with a high FF via snapshot polarization patterning. The digitalized linear polarization pattern was distributed across the photo-alignment layer with both high efficiency and accuracy, enabling large-area liquid crystal MLA with parameter controllability from element to element. The MLA manufacturing process does not involve developing, etching and deposition steps and is suitable for industry up-scaling. We further proposed a novel compact compound-eye imaging system for biometrics with the obtained MLAs. The 100% FF MLA enables high light utilization efficiency and low background crosstalk, yielding compact biometrics indentation with high recognition accuracy. The realization of such planar optics would lead to a plethora of different miniaturized multiaperture imaging systems in the future.

A mechanically bendable and conformally attachable polymer membrane microlaser array enabled by digital interference lithography.

The progressive miniaturization and thinning of photonic devices would enable the realization of multi-functional photonic integrated circuits and expand the application frontier to novel fields including wearable and disposable electronics. Herein, we have demonstrated a mechanically bendable and conformally attachable polymer membrane microcavity laser array using digital interference lithography. The developed lithography system could distribute a number of subwavelength grating pixels with both high efficiency (1k pixels per second) and excellent versatility (ease of control in the pixel size, spacing, and grating periodicity) as the microcavity laser array, in which a pair of subwavelength gratings constitutes a distributed Bragg resonator microcavity via coherent interference, furnishes a vertically emitting microcavity laser array for convenient light coupling and utilization. The microlaser array polymer membrane presented a total thickness of only 30 µm with excellent performance stability and reliability against long time operation and harsh environmental conditions, which could be further reversibly stretched, repeatedly bendable and conformally attached onto rounded or irregular surfaces or biological tissues with no degradation in single-mode or low-threshold characteristics, paving a way for on-chip optical functionalization toward wearable electronics and outdoor environmental monitoring applications.

TBR2 coordinates neurogenesis expansion and precise microcircuit organization via Protocadherin 19 in the mammalian cortex.

Cerebral cortex expansion is a hallmark of mammalian brain evolution; yet, how increased neurogenesis is coordinated with structural and functional development remains largely unclear. The T-box protein TBR2/EOMES is preferentially enriched in intermediate progenitors and supports cortical neurogenesis expansion. Here we show that TBR2 regulates fine-scale spatial and circuit organization of excitatory neurons in addition to enhancing neurogenesis in the mouse cortex. TBR2 removal leads to a significant reduction in neuronal, but not glial, output of individual radial glial progenitors as revealed by mosaic analysis with double markers. Moreover, in the absence of TBR2, clonally related excitatory neurons become more laterally dispersed and their preferential synapse development is impaired. Interestingly, TBR2 directly regulates the expression of Protocadherin 19 (PCDH19), and simultaneous PCDH19 expression rescues neurogenesis and neuronal organization defects caused by TBR2 removal. Together, these results suggest that TBR2 coordinates neurogenesis expansion and precise microcircuit assembly via PCDH19 in the mammalian cortex.

No association between low-dose reserpine use and depression in older hypertensive patient: result of a multicenter, cross-sectional study.

BACKGROUND: Reserpine is currently used by millions of Chinese hypertensive patients, in spite of the continued concern of its depressogenic effect, even when used in low dose. This study aimed to investigate the association between low-dose reserpine use and depression in older Chinese hypertensive patient. METHODS: In this cross-sectional, case-control study, we recruited patient aged 60 years or over who had regularly taken one or two tables of "compound reserpine and triamterene tablets (CRTTs)" for more than one year (reserpine user) from 26 community health centers located in 10 provinces in China. For each patient who took CRTTs, we selected an age (within five years) and sex matched hypertensive patient who had never taken any drugs containing reserpine (non-reserpine user) as control. Depressive symptoms were evaluated using a Chinese depression scale adapted from the Zung Self-Rating Depression Scale. Demographic, clinical data and laboratory examination results within six months were collected. RESULTS: From August 2018 to December 2018, 787 reserpine user and 787 non-reserpine user were recruited. The mean age of all study subjects was 70.3 years, with about equal numbers of males and females. The mean depression score was 40.4 in reserpine users and 40.6 in non-reserpine users (P = 0.7). The majority of study subject had a depression score < 53 (87.6% in reserpine users and 88.2% in non-reserpine users, respectively). There were no significant differences in the prevalence of mild, moderate or severe depression in reserpine users and non-reserpine users. CONCLUSIONS: There is no association between low-dose reserpine use and depression in older hypertensive patient. The role of reserpine in the treatment and control of hypertension should be reconsidered; and further studies, especially randomized, controlled clinical trials to compare efficacy and safety of reserpine and other widely recommended anti-hypertensive agents are needed.

Progressive divisions of multipotent neural progenitors generate late-born chandelier cells in the neocortex.

Diverse γ-aminobutyric acid (GABA)-ergic interneurons provide different modes of inhibition to support circuit operation in the neocortex. However, the cellular and molecular mechanisms underlying the systematic generation of assorted neocortical interneurons remain largely unclear. Here we show that NKX2.1-expressing radial glial progenitors (RGPs) in the mouse embryonic ventral telencephalon divide progressively to generate distinct groups of interneurons, which occupy the neocortex in a time-dependent, early inside-out and late outside-in, manner. Notably, the late-born chandelier cells, one of the morphologically and physiologically highly distinguishable GABAergic interneurons, arise reliably from continuously dividing RGPs that produce non-chandelier cells initially. Selective removal of Partition defective 3, an evolutionarily conserved cell polarity protein, impairs RGP asymmetric cell division, resulting in premature depletion of RGPs towards the late embryonic stages and a consequent loss of chandelier cells. These results suggest that consecutive asymmetric divisions of multipotent RGPs generate diverse neocortical interneurons in a progressive manner.

Mature Hippocampal Neurons Require LIS1 for Synaptic Integrity: Implications for Cognition.

BACKGROUND: Platelet-activating factor acetylhydrolase 1B1 (LIS1), a critical mediator of neuronal migration in developing brain, is expressed throughout life. However, relatively little is known about LIS1 function in the mature brain. We previously demonstrated that LIS1 involvement in the formation and turnover of synaptic protrusions and synapses of young brain after neuronal migration is complete. Here we examine the requirement for LIS1 to maintain hippocampal circuit function in adulthood. METHODS: Effects of conditional Lis1 inactivation in excitatory pyramidal neurons, starting in juvenile mouse brain, were probed using high-resolution approaches combining mouse genetics, designer receptor exclusively activated by designer drug technology to specifically manipulate CA1 pyramidal neuron excitatory activity, electrophysiology, hippocampus-selective behavioral testing, and magnetic resonance imaging tractography to examine the connectivity of LIS1-deficient neurons. RESULTS: We found progressive excitatory and inhibitory postsynaptic dysfunction as soon as 10 days after conditional inactivation of Lis1 targeting CA1 pyramidal neurons. Surprisingly, by postnatal day 60 it also caused CA1 histological disorganization, with a selective decline in parvalbumin-expressing interneurons and further reduction in inhibitory neurotransmission. Accompanying these changes were behavioral and cognitive deficits that could be rescued by either designer receptor exclusively activated by designer drug-directed specific increases in CA1 excitatory transmission or pharmacological enhancement of gamma-aminobutyric acid transmission. Lagging behind electrophysiological changes was a progressive, selective decline in neural connectivity, affecting hippocampal efferent pathways documented by magnetic resonance imaging tractography. CONCLUSIONS: LIS1 supports synaptic function and plasticity of mature CA1 neurons. Postjuvenile loss of LIS1 disrupts the structure and cellular composition of the hippocampus, its connectivity with other brain regions, and cognition dependent on hippocampal circuits.

Precise inhibitory microcircuit assembly of developmentally related neocortical interneurons in clusters.

GABA-ergic interneurons provide diverse inhibitions that are essential for the operation of neuronal circuits in the neocortex. However, the mechanisms that control the functional organization of neocortical interneurons remain largely unknown. Here we show that developmental origins influence fine-scale synapse formation and microcircuit assembly of neocortical interneurons. Spatially clustered neocortical interneurons originating from low-titre retrovirus-infected radial glial progenitors in the embryonic medial ganglionic eminence and preoptic area preferentially develop electrical, but not chemical, synapses with each other. This lineage-related electrical coupling forms predominantly between the same interneuron subtype over an extended postnatal period and across a range of distances, and promotes action potential generation and synchronous firing. Interestingly, this selective electrical coupling relates to a coordinated inhibitory chemical synapse formation between sparsely labelled interneurons in clusters and the same nearby excitatory neurons. These results suggest a link between the lineage relationship of neocortical interneurons and their precise functional organization.

Combined small-molecule inhibition accelerates the derivation of functional cortical neurons from human pluripotent stem cells.

Considerable progress has been made in converting human pluripotent stem cells (hPSCs) into functional neurons. However, the protracted timing of human neuron specification and functional maturation remains a key challenge that hampers the routine application of hPSC-derived lineages in disease modeling and regenerative medicine. Using a combinatorial small-molecule screen, we previously identified conditions to rapidly differentiate hPSCs into peripheral sensory neurons. Here we generalize the approach to central nervous system (CNS) fates by developing a small-molecule approach for accelerated induction of early-born cortical neurons. Combinatorial application of six pathway inhibitors induces post-mitotic cortical neurons with functional electrophysiological properties by day 16 of differentiation, in the absence of glial cell co-culture. The resulting neurons, transplanted at 8 d of differentiation into the postnatal mouse cortex, are functional and establish long-distance projections, as shown using iDISCO whole-brain imaging. Accelerated differentiation into cortical neuron fates should facilitate hPSC-based strategies for disease modeling and cell therapy in CNS disorders.

Clonally Related GABAergic Interneurons Do Not Randomly Disperse but Frequently Form Local Clusters in the Forebrain.

Progenitor cells in the medial ganglionic eminence (MGE) and preoptic area (PoA) give rise to GABAergic inhibitory interneurons that are distributed in the forebrain, largely in the cortex, hippocampus, and striatum. Two previous studies suggest that clonally related interneurons originating from individual MGE/PoA progenitors frequently form local clusters in the cortex. However, Mayer et al. and Harwell et al. recently argued that MGE/PoA-derived interneuron clones disperse widely and populate different forebrain structures. Here, we report further analysis of the spatial distribution of clonally related interneurons and demonstrate that interneuron clones do not non-specifically disperse in the forebrain. Around 70% of clones are restricted to one brain structure, predominantly the cortex. Moreover, the regional distribution of clonally related interneurons exhibits a clear clustering feature, which cannot occur by chance from a random diffusion. These results confirm that lineage relationship influences the spatial distribution of inhibitory interneurons in the forebrain. This Matters Arising paper is in response to Harwell et al. (2015) and Mayer et al. (2015), published in Neuron. See also the response by Turrero García et al. (2016) and Mayer et al. (2016), published in this issue.

Vascular Influence on Ventral Telencephalic Progenitors and Neocortical Interneuron Production.

The neocortex contains glutamatergic excitatory neurons and γ-aminobutyric acid (GABA)ergic inhibitory interneurons. Extensive studies have revealed substantial insights into excitatory neuron production. However, our knowledge of the generation of GABAergic interneurons remains limited. Here we show that periventricular blood vessels selectively influence neocortical interneuron progenitor behavior and neurogenesis. Distinct from those in the dorsal telencephalon, radial glial progenitors (RGPs) in the ventral telencephalon responsible for producing neocortical interneurons progressively grow radial glial fibers anchored to periventricular vessels. This progenitor-vessel association is robust and actively maintained as RGPs undergo interkinetic nuclear migration and divide at the ventricular zone surface. Disruption of this association by selective removal of INTEGRIN ß1 in RGPs leads to a decrease in progenitor division, a loss of PARVALBUMIN and SOMATOSTATIN-expressing interneurons, and defective synaptic inhibition in the neocortex. These results highlight a prominent interaction between RGPs and periventricular vessels important for proper production and function of neocortical interneurons.

Molecular cloning and pharmacological characterization of giant panda (Ailuropoda melanoleuca) melanocortin-4 receptor.

The melanocortin-4 receptor (MC4R) is critical in regulating mammalian food intake and energy expenditure. Giant panda (Ailuropoda melanoleuca), famous as the living fossil, is an endangered species endemic to China. We are interested in exploring the functions of the giant panda MC4R (amMC4R) in regulating energy homeostasis and report herein the molecular cloning and pharmacology of the amMC4R. Sequence analysis revealed that amMC4R was highly homologous (>88%) at nucleotide and amino acid sequences to several mammalian MC4Rs. Western blot revealed that the expression construct myc-amMC4R in pcDNA3.1 was successfully constructed and expressed in HEK293T cells. With human MC4R (hMC4R) as a control, pharmacological characteristics of amMC4R were analyzed with binding and signaling assays. Four agonists, including [Nle(4), D-Phe(7)]-α-melanocyte stimulating hormone (NDP-MSH), α- and ß-MSH, and a small molecule agonist, THIQ, were used in binding and signaling assays. We showed that amMC4R bound NDP-MSH with the highest affinity followed by THIQ, α-MSH, and ß-MSH, with the same ranking order as hMC4R. Treatment of HEK293T cells expressing amMC4R with different concentrations of agonists resulted in dose-dependent increase of intracellular cAMP levels, with similar EC50s for the four agonists. The results suggested that the cloned amMC4R encoded a functional MC4R. The availability of amMC4R and its binding and signaling properties will facilitate the investigation of amMC4R in regulating food intake and energy homeostasis.

Genetic diversity and population structure of an extremely endangered species: the world's largest Rhododendron.

Comprehensive studies on the genetic diversity and structure of endangered species are urgently needed to promote effective conservation and management activities. The big tree rhododendron, Rhododendron protistum var. giganteum, is a highly endangered species with only two known endemic populations in a small area in the southern part of Yunnan Province in China. Unfortunately, limited information is available regarding the population genetics of this species. Therefore, we conducted amplified fragment length polymorphism (AFLP) analysis to characterize the genetic diversity and variation of this species within and between remaining populations. Twelve primer combinations of AFLP produced 447 unambiguous and repetitious bands. Among these bands, 298 (66.67 %) were polymorphic. We found high genetic diversity at the species level (percentage of polymorphic loci = 66.67 %, h = 0.240, I = 0.358) and low genetic differentiation (Gst = 0.110) between the two populations. Gene flow between populations (Nm) was relatively high at 4.065. Analysis of molecular variance results revealed that 22 % of the genetic variation was partitioned between populations and 78 % of the genetic variation was within populations. The presence of moderate to high genetic diversity and low genetic differentiation in the two populations can be explained by life history traits, pollen dispersal and high gene flow (Nm = 4.065). Bayesian structure and principal coordinate analysis revealed that 56 sampled trees were clustered into two groups. Our results suggest that some rare and endangered species are able to maintain high levels of genetic diversity even at small population sizes. These results will assist with the design of conservation and management programmes, such as in situ and ex situ conservation, seed collection for germplasm conservation and reintroduction.

Lineage-dependent circuit assembly in the neocortex.

The neocortex plays a key role in higher-order brain functions, such as perception, language and decision-making. Since the groundbreaking work of Ramón y Cajal over a century ago, defining the neural circuits underlying brain functions has been a field of intense study. Here, we review recent findings on the formation of neocortical circuits, which have taken advantage of improvements to mouse genetics and circuit-mapping tools. These findings are beginning to reveal how individual components of circuits are generated and assembled during development, and how early developmental processes, such as neurogenesis and neuronal migration, guide precise circuit assembly.

The performance determination of a Compton-suppression spectrometer and the measurement of the low level radioactive samples.

The performance of a new Compton-suppression spectrometer consisting of one HPGe detector and three NaI(Tl) detectors was studied. The peak-to-Compton ratio for a (137)Cs source is 1150 and the integral background count rate is 0.3 5s(-1) over the energy interval 20-3000 keV. The spectrometer was used to acquire both Compton-suppressed and non-suppressed spectra of aerosol samples collected in Beijing following the Fukushima nuclear accident.