Age-dependent neurological phenotypes in a mouse model of PRRT2-related diseases

Paroxysmal kinesigenic dyskinesia is an episodic movement disorder caused by dominant mutations in the proline-rich transmembrane protein PRRT2, with onset in childhood and typically with improvement or resolution by middle age. Mutations in the same gene may also cause benign infantile seizures, which begin in the first year of life and typically remit by the age of 2 years. Many details of PRRT2 function at the synapse, and the effects of mutations on neuronal excitability in the pathophysiology of epilepsy and dyskinesia, have emerged through the work of several groups over the last decade. However, the age dependence of the phenotypes has not been explored in detail in transgenic models. Here, we report our findings in heterozygous and homozygous Prrt2 knockout mice that recapitulate the age dependence of dyskinesia seen in the human disease. We show that Prrt2 deletion reduces the levels of synaptic proteins in a dose-dependent manner that is most pronounced at postnatal day 5 (P5), attenuates at P60, and disappears by P180. In a test for foot slippage while crossing a balance beam, transient loss of coordination was most pronounced at P60 and less prominent at age extremes. Slower traverse time was noted in homozygous knockout mice only, consistent with the ataxia seen in rare individuals with biallelic loss of function mutations in Prrt2. We thus identify three age-dependent phenotypic windows in the mouse model, which recapitulate the pattern seen in humans with PRRT2-related diseases.

     

微小残留病灶在非小细胞肺癌中的研究进展与应用

部分非小细胞肺癌患者在早期治愈后会发生远期复发或转移,这可能与治疗后患者体内仍存在影像学或是实验室方法检测不到的肿瘤病灶,即微小残留病灶相关。这些肿瘤复发的潜在来源与患者较差的预后有着紧密的联系,因此, 在非小细胞肺癌病程中对这些病灶的监测十分重要。目前,针对微小残留病灶的检测主要依靠于液体活检,包括了循环肿瘤DNA检测、循环肿瘤细胞检测等方法。通过无创的检测手段,残留的肿瘤病灶为我们提供了肿瘤的进展状况以及具体的分子信息,预测了患者的预后状况,并进一步指导后续治疗方案。在这篇综述中,我们将探讨微小残留病灶发生发展的机制与影响,并关注对其的监测在临床治疗过程中可能的应用前景。     

Reliability and validity of the sideways step test and its correlation with motor function after stroke

[Purpose] This study investigated the intra-rater, inter-rater and test-retest reliability of the sideways step test (SST), its correlation with other indicators of stroke-specific impairment, and the cut-off count best discriminating subjects with stroke from their healthy counterparts. [Subjects and Methods] Forty-three subjects with chronic stroke and 41 healthy subjects older than 50 years participated in this study. The SST was administered along with the Fugl-Meyer motor assessment for the lower extremities (FMA-LE), the five-times sit to stand (5TSTS) test, the Berg Balance Scale (BBS), the movement velocity (MVL) by the limits of stability (LOS) test, the ten-metre walk (10mW) test, the timed “Up and Go” (TUG) test and the Activities-specific Balance Confidence (ABC) scale. [Results] The SST showed good to excellent intra-rater, inter-rater and test-retest reliability. The SST counts correlated with 5TSTS times, 10mW times, TUG times, and the FMA-LE and BBS scores. SST counts of 11 for the paretic leg and 14 for the non-paretic leg were found to distinguish the healthy adults from subjects with stroke. [Conclusion] The sideways step test is a reliable clinical test, which correlates with the functional strength, gait speed, and functional balance of people with chronic stroke.Key words: Balance, Stroke, Rehabilitation     

FGF21 protects human umbilical vein endothelial cells against high glucose-induced apoptosis via PI3K/Akt/Fox3a signaling pathway

Aims

Diabetic macroangiopathy is the main cause of morbidity and mortality in patients with diabetes. Endothelial cell injury is a pathological precondition for diabetic macroangiopathy. Fibroblast growth factor 21 (FGF21) is a key metabolic regulator which has recently been suggested to protect cardiac myocytes and vascular cells against oxidative stress-induced injury in vitro and vivo. In this study, we aimed to investigate the protective capacity of FGF21 in human umbilical vein endothelial cells (HUVECs) against high glucose (HG)-induced apoptosis via phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt)/FoxO3a pathway.

Regulating kinetics and thermodynamics of electrochemical nitrogen reduction with metal single-atom catalysts in a pressurized electrolyser

Using renewable electricity to synthesize ammonia from nitrogen paves a sustainable route to making value-added chemicals but yet requires further advances in electrocatalyst development and device integration. By engineering both electrocatalyst and electrolyzer to simultaneously regulate chemical kinetics and thermodynamic driving forces of the electrocatalytic nitrogen reduction reaction (ENRR), we report herein stereoconfinement-induced densely populated metal single atoms (Rh, Ru, Co) on graphdiyne (GDY) matrix (formulated as M SA/GDY) and realized a boosted ENRR activity in a pressurized reaction system. Remarkably, under the pressurized environment, the hydrogen evolution reaction of M SA/GDY was effectively suppressed and the desired ENRR activity was strongly amplificated. As a result, the pressurized ENRR activity of Rh SA/GDY at 55 atm exhibited a record-high NH₃ formation rate of 74.15 μg h⁻¹⋅cm⁻², a Faraday efficiency of 20.36%, and a NH₃ partial current of 0.35 mA cm⁻² at −0.20 V versus reversible hydrogen electrode, which, respectively, displayed 7.3-, 4.9-, and 9.2-fold enhancements compared with those obtained under ambient conditions. Furthermore, a time-independent ammonia yield rate using purified ¹⁵N₂ confirmed the concrete ammonia electroproduction. Theoretical calculations reveal that the driving force for the formation of end-on N₂* on Rh SA/GDY increased by 9.62 kJ/mol under the pressurized conditions, facilitating the ENRR process. We envisage that the cooperative regulations of catalysts and electrochemical devices open up the possibilities for industrially viable electrochemical ammonia production.

Ammonia is essential for human propagation and thriving (1, 2). Today’s global ammonia production is excessively dependent on the Haber–Bosch method, which converts nitrogen and hydrogen to ammonia at high temperature (300–500 °C) and pressure (200–300 atm) (3). So far, this century-old strategy has contributed vastly annual productions, yet significantly exacerbating the global energy consumption and greenhouse-gas emission. Electrocatalytic N₂ reduction reaction (ENRR) to synthesize ammonia from nitrogen and water under mild conditions represents a viable alternative that strategically transforms the energy-intensive sector toward sustainability, while its efficiency achieved so far is fairly low (4–8).The primary hurdle obstructing the ENRR lies in issues such as the inherent inertness of N₂, the high-energy barrier of N₂ activation, multiple electron–proton transfers, the low solubility of N₂ in aqueous solutions and competing hydrogen evolution reaction (HER), etc. (9–12). On the basis of these premises, strategies are highlighted to modulate the kinetics and thermodynamic equilibrium of the progress, thus steering the reaction toward the production of ammonia while mitigating HER (13–16). From a kinetic perspective, many catalyst-centric approaches, such as introducing alloy, defects, doping, and strain, etc., have been explored to improve nitrogen reduction performance (17–21). The overall ENRR efficiency, however, is still insufficient to meet the practical requirements. On the other hand, the improvement of the thermodynamic driving force for ammonia production, such as regulating electrochemical reaction conditions, may offer equally positive effects to efficiently promote the N₂ reduction process and suppress the unwanted side reactions (22). Conventionally, exploration of the innovation of electrocatalysts or electrochemical cell devices has always been undergone independently, despite their indivisible interconnection nature. Indeed, the ENRR advancements toward the envisioned practical applications depend very much on the cooperative development of both electrocatalysts and electrochemical cell devices (23).Given that the reductive N₂ adsorption (N₂ + e⁻ + H⁺ → *N = NH) is usually regarded as the potential limiting step, novel metal single-atom catalysts (SACs, e.g., Ru, Rh, Co) with a favorable ENRR kinetics guarantee a great promise to circumvent the N₂ activation energy barrier (24–27). These catalysts, on the other hand, also suffer vigorous competition from HER and low content of metal loading (28–30). Encouragingly, the most recent research work demonstrated that the system-level regulation of the pressurized electrocatalytic environment could affect the chemical equilibrium of the ammonia production reaction and meanwhile endow tangible HER suppression (31). It thus warrants research efforts to query whether the integration of SACs with pressurized electrochemical environments will lever synergies between kinetics and thermodynamic driving forces and be the game-changer for the ENRR.Herein, we showcase that SACs-catalyzed N₂ reduction in a pressurized system is an effective design principle to enhance both the chemical kinetics and thermodynamic process, leading to the amplified ENRR activity with simultaneously retarded HER. The deployed SACs contain Ru, Rh, and Co atoms featured with densely populated active sites and stabilized on graphdiyne (GDY) support (referred to as M SA/GDY; M = Rh, Ru, and Co); these electrocatalysts were prepared by a facile and mild method via stereoconfinement of metal atoms on the GDY framework. Through extensive ENRR test using adequately cleaned N₂, we found that the as-prepared M SA/GDY electrocatalysts render prominently enhanced ammonia electroproduction with obvious HER inhibition at the pressurized electrocatalytic system, suggesting positive cooperation between SAC and the pressurized environment. Remarkably, a record-high ammonia yield rate of 74.15 μg h⁻¹⋅cm⁻², a Faraday efficiency (FE) of 20.36%, and a NH₃ partial current density of 0.35 mA cm⁻² were achieved for Rh SA/GDY at 55 atm of N₂, which shows 7.3-, 4.9-, and 9.2-fold enhancement in comparison with those obtained in ambient conditions, outperforming the state-of-art ENRR catalysts. Additionally, a time-independent ammonia yield rate using adequately cleaned ¹⁵N₂ ensured the ammonia electrosynthesis from N₂.     

Assessment of aldehyde dehydrogenase in viable cells

Cytosolic aldehyde dehydrogenase (ALDH), an enzyme responsible for oxidizing intracellular aldehydes, has an important role in ethanol, vitamin A, and cyclophosphamide metabolism. High expression of this enzyme in primitive stem cells from multiple tissues, including bone marrow and intestine, appears to be an important mechanism by which these cells are resistant to cyclophosphamide. However, although hematopoietic stem cells (HSC) express high levels of cytosolic ALDH, isolating viable HSC by their ALDH expression has not been possible because ALDH is an intracellular protein. We found that a fluorescent aldehyde, dansyl aminoacetaldehyde (DAAA), could be used in flow cytometry experiments to isolate viable mouse and human cells based on their ALDH content. The level of dansyl fluorescence exhibited by cells after incubation with DAAA paralleled cytosolic ALDH levels determined by Western blotting and the sensitivity of the cells to cyclophosphamide. Moreover, DAAA appeared to be a more sensitive means of assessing cytosolic ALDH levels than Western blotting. Bone marrow progenitors treated with DAAA proliferated normally. Furthermore, marrow cells expressing high levels of dansyl fluorescence after incubation with DAAA were enriched for hematopoietic progenitors. The ability to isolate viable cells that express high levels of cytosolic ALDH could be an important component of methodology for identifying and purifying HSC and for studying cyclophosphamide-resistant tumor cell populations.     

Protection of murine bone marrow by dexamethasone during cytotoxic chemotherapy

Corticosteroids have the ability to suppress the production of growth factors and cytokines and are thus implicated in the negative regulation of hematopoiesis. We have shown that the corticosteroids, prednisolone and dexamethasone, were able to effectively protect progenitor cells in four strains of mice against cell-cycle-specific antimetabolic chemotherapy agents. The highest levels of protection against 5-fluorouracil (FU; 200 mg/kg) were achieved when two or three intraperitoneal injections of dexamethasone were administered between - 7 and +3 hours at a dose of 7.5 mg/kg/injection (optimal dose) or by continuous infusion between -4 and +20 hours. This protective effect is manifested as an increase in the number of high proliferative potential colony-forming cells that survive in the bone marrow 3 days after treatment with FU from between 0.5% and 11% to between 10% and 34% of normal. The bone marrow progenitors and blood cell numbers return to normal from 3 to 5 days and 1 to 2 days earlier, respectively. Less dexamethasone than prednisolone is required to give an equivalent protective effect, which is consistent with their anti-inflammatory potency. These findings are further evidence of the negative regulatory role played by corticosteroids, and indicate that the treatment schedules of corticosteroids during cancer therapy need to be reexamined to obtain the maximum benefit from their use.