Structural basis for human Cav3.2 inhibition by selective antagonists.

The Cav3.2 subtype of T-type calcium channels has been targeted for developing analgesics and anti-epileptics for its role in pain and epilepsy. Here we present the cryo-EM structures of Cav3.2 alone and in complex with four T-type calcium channel selective antagonists with overall resolutions ranging from 2.8 Å to 3.2 Å. The four compounds display two binding poses. ACT-709478 and TTA-A2 both place their cyclopropylphenyl-containing ends in the central cavity to directly obstruct ion flow, meanwhile extending their polar tails into the IV-I fenestration. TTA-P2 and ML218 project their 3,5-dichlorobenzamide groups into the II-III fenestration and place their hydrophobic tails in the cavity to impede ion permeation. The fenestration-penetrating mode immediately affords an explanation for the state-dependent activities of these antagonists. Structure-guided mutational analysis identifies several key residues that determine the T-type preference of these drugs. The structures also suggest the role of an endogenous lipid in stabilizing drug binding in the central cavity.

Mechanism of NLRP3 Inflammasome in Epilepsy and Related Therapeutic Agents.

Epilepsy is one of the most widespread and complex diseases in the central nervous system (CNS), affecting approximately 65 million people globally, an important factor resulting in neurological disability-adjusted life year (DALY) and progressive cognitive dysfunction. Medication is the most essential treatment. The currently used drugs have shown drug resistance in some patients and only control symptoms; the development of novel and more efficacious pharmacotherapy is imminent. Increasing evidence suggests neuroinflammation is involved in the occurrence and development of epilepsy, and high expression of NLRP3 inflammasome has been observed in the temporal lobe epilepsy (TLE) brain tissue of patients and animal models. The inflammasome is a crucial cause of neuroinflammation by activating IL-1ß and IL-18. Many preclinical studies have confirmed that regulating NLRP3 inflammasome pathway can prevent the development of epilepsy, reduce the severity of epilepsy, and play a neuroprotective role. Therefore, regulating NLRP3 inflammasome could be a potential target for epilepsy treatment. In summary, this review describes the priming and activation of inflammasome and its biological function in the progression of epilepsy. In addition, we reviewes the current pharmacological researches for epilepsy based on the regulation of NLRP3 inflammasome, aiming to provide a basis and reference for developing novel antiepileptic drugs.

Dissection of the structure-function relationship of Nav channels.

Voltage-gated sodium channels (Nav) undergo conformational shifts in response to membrane potential changes, a mechanism known as the electromechanical coupling. To delineate the structure-function relationship of human Nav channels, we have performed systematic structural analysis using human Nav1.7 as a prototype. Guided by the structural differences between wild-type (WT) Nav1.7 and an eleven mutation-containing variant, designated Nav1.7-M11, we generated three additional intermediate mutants and solved their structures at overall resolutions of 2.9-3.4 Å. The mutant with nine-point mutations in the pore domain (PD), named Nav1.7-M9, has a reduced cavity volume and a sealed gate, with all voltage-sensing domains (VSDs) remaining up. Structural comparison of WT and Nav1.7-M9 pinpoints two residues that may be critical to the tightening of the PD. However, the variant containing these two mutations, Nav1.7-M2, or even in combination with two additional mutations in the VSDs, named Nav1.7-M4, failed to tighten the PD. Our structural analysis reveals a tendency of PD contraction correlated with the right shift of the static inactivation I-V curves. We predict that the channel in the resting state should have a "tight" PD with down VSDs.

Effect of hospital elder life program on the incidence of delirium: A systematic review and meta-analysis of clinical trials.

OBJECTIVE: This meta-analysis aims to investigate the effect of the Hospital Elder Life Program (HELP) on the incidence of delirium, delirium scores, length of hospital stay, and incidence of falls. METHODS: Four databases (PubMed, Embase, Cochrane Library, and Web of Science) were searched from inception until January 18, 2024. The search specifically targeted randomized controlled trials (RCTs). Two independent researchers conducted literature screening, quality assessment, and data extraction. The meta-analysis was performed using Review Manager 5.4.1 and Stata 15.1 software. RESULTS: The final analysis included a total of 9 RCTs with 2583 patients. The findings from the meta-analysis indicated that HELP was found to considerably reduce the incidence of delirium and the length of hospital stay when compared to the control group. Nevertheless, no statistically significant differences were observed between the two groups in terms of delirium scores and fall rates. CONCLUSION: In this meta-analysis, HELP can effectively reduce the incidence of delirium and lead to a shorter hospital stay.

The association between oral carbohydrate intake before orthopedic surgery for osteoporotic fractures and outcomes in elderly patients.

BACKGROUND: Oral carbohydrate (CHO) intake is a safe method with effective clinical results in various surgical patients before surgery. Nevertheless, due to a lack of adequate clinical data, it is not frequently utilized in older patients undergoing orthopedic surgery for osteoporotic fractures (OPFs), especially in China. The purpose of the present study was to examine the relationship between preoperative oral CHO consumption and outcomes in elderly patients undergoing surgical treatment for OPFs. METHODS: This retrospective cohort study was conducted at a single Chinese institution and included a total of 879 elderly patients (median age: 71 years; range: 50-99 years) who underwent OPF surgery. Various exclusion criteria were established as follows: (a) the necessity for urgent surgical intervention; (b) the existence of hypoglycemia, hyperglycemia, or diabetes mellitus with blood glucose levels lower than 2.8 mmol/L; (c) a medical history of gastrointestinal motility disorders or delayed gastric emptying; (d) the utilization of local anesthesia; (e) a Charlson comorbidity index (CCI) score over 2; and (f) an American Society of Anesthesiologists (ASA) score exceeding 3. After propensity score (PS) matching, 264 patients from each cohort were included in the analysis. The primary outcome was the all-cause mortality rate within 60 days post-surgery, while secondary outcomes included the length of hospital stay (LOS), hospitalization costs, intraoperative and postoperative blood transfusions, and the incidence of postoperative nausea and vomiting (PONV) and aspiration. The relationship between preoperative oral CHO intake and outcomes was evaluated using multivariate regression analysis. RESULTS: After PS matching, preoperative oral CHO intake was negatively associated with 60-day mortality in the fully adjusted model (odds ratio 0.35; 95% confidence interval 0.12-0.97; P-value: 0.04). Patients who received preoperative oral CHO intake also had a shorter LOS and lower hospitalization costs than those who did not receive CHO intake. However, none of the models showed a significant association between CHO intake and PONV or blood transfusion risk. Furthermore, no cases of aspiration were observed in either cohort. CONCLUSIONS: Preoperative oral CHO intake may be associated with reduced mortality risk and improved outcomes in elderly patients undergoing surgical treatment for OPFs. However, it is important to acknowledge the limitations of our study, including its retrospective nature, potential unmeasured confounding variables, the small sample size, incomplete data on important variables such as duration of surgery and inflammatory markers, and the limited generalizability due to the participation of only one institution. Future research with larger sample sizes and a broader range of events is warranted to validate and enhance the validity of our findings, particularly in assessing long-term results and understanding the underlying mechanisms.

Structural basis for human Cav1.2 inhibition by multiple drugs and the neurotoxin calciseptine.

Cav1.2 channels play crucial roles in various neuronal and physiological processes. Here, we present cryo-EM structures of human Cav1.2, both in its apo form and in complex with several drugs, as well as the peptide neurotoxin calciseptine. Most structures, apo or bound to calciseptine, amlodipine, or a combination of amiodarone and sofosbuvir, exhibit a consistent inactivated conformation with a sealed gate, three up voltage-sensing domains (VSDs), and a down VSDII. Calciseptine sits on the shoulder of the pore domain, away from the permeation path. In contrast, when pinaverium bromide, an antispasmodic drug, is inserted into a cavity reminiscent of the IFM-binding site in Nav channels, a series of structural changes occur, including upward movement of VSDII coupled with dilation of the selectivity filter and its surrounding segments in repeat III. Meanwhile, S4-5III merges with S5III to become a single helix, resulting in a widened but still non-conductive intracellular gate.

Dual-pocket inhibition of Nav channels by the antiepileptic drug lamotrigine.

Voltage-gated sodium (Nav) channels govern membrane excitability, thus setting the foundation for various physiological and neuronal processes. Nav channels serve as the primary targets for several classes of widely used and investigational drugs, including local anesthetics, antiepileptic drugs, antiarrhythmics, and analgesics. In this study, we present cryogenic electron microscopy (cryo-EM) structures of human Nav1.7 bound to two clinical drugs, riluzole (RLZ) and lamotrigine (LTG), at resolutions of 2.9 Å and 2.7 Å, respectively. A 3D EM reconstruction of ligand-free Nav1.7 was also obtained at 2.1 Å resolution. RLZ resides in the central cavity of the pore domain and is coordinated by residues from repeats III and IV. Whereas one LTG molecule also binds to the central cavity, the other is found beneath the intracellular gate, known as site BIG. Therefore, LTG, similar to lacosamide and cannabidiol, blocks Nav channels via a dual-pocket mechanism. These structures, complemented with docking and mutational analyses, also explain the structure-activity relationships of the LTG-related linear 6,6 series that have been developed for improved efficacy and subtype specificity on different Nav channels. Our findings reveal the molecular basis for these drugs' mechanism of action and will aid the development of novel antiepileptic and pain-relieving drugs.

Cannabidiol inhibits Nav channels through two distinct binding sites.

Cannabidiol (CBD), a major non-psychoactive phytocannabinoid in cannabis, is an effective treatment for some forms of epilepsy and pain. At high concentrations, CBD interacts with a huge variety of proteins, but which targets are most relevant for clinical actions is still unclear. Here we show that CBD interacts with Nav1.7 channels at sub-micromolar concentrations in a state-dependent manner. Electrophysiological experiments show that CBD binds to the inactivated state of Nav1.7 channels with a dissociation constant of about 50 nM. The cryo-EM structure of CBD bound to Nav1.7 channels reveals two distinct binding sites. One is in the IV-I fenestration near the upper pore. The other binding site is directly next to the inactivated "wedged" position of the Ile/Phe/Met (IFM) motif on the short linker between repeats III and IV, which mediates fast inactivation. Consistent with producing a direct stabilization of the inactivated state, mutating residues in this binding site greatly reduced state-dependent binding of CBD. The identification of this binding site may enable design of compounds with improved properties compared to CBD itself.

Structural mapping of Nav1.7 antagonists.

Voltage-gated sodium (Nav) channels are targeted by a number of widely used and investigational drugs for the treatment of epilepsy, arrhythmia, pain, and other disorders. Despite recent advances in structural elucidation of Nav channels, the binding mode of most Nav-targeting drugs remains unknown. Here we report high-resolution cryo-EM structures of human Nav1.7 treated with drugs and lead compounds with representative chemical backbones at resolutions of 2.6-3.2 Å. A binding site beneath the intracellular gate (site BIG) accommodates carbamazepine, bupivacaine, and lacosamide. Unexpectedly, a second molecule of lacosamide plugs into the selectivity filter from the central cavity. Fenestrations are popular sites for various state-dependent drugs. We show that vinpocetine, a synthetic derivative of a vinca alkaloid, and hardwickiic acid, a natural product with antinociceptive effect, bind to the III-IV fenestration, while vixotrigine, an analgesic candidate, penetrates the IV-I fenestration of the pore domain. Our results permit building a 3D structural map for known drug-binding sites on Nav channels summarized from the present and previous structures.

Proteomics Analysis of Lipid Metabolism and Inflammatory Response in the Liver of Rabbits fed on a High Cholesterol Diet.

In this study, we aimed to analyze the proteomics of the liver in rabbits on a high cholesterol diet (HCD). We randomly divided New Zealand white rabbits into the normal diet group and the HCD group. We established the atherosclerosis model and measured plasma cholesterol and triglycerides. The model was successfully established using ultrasound examination and histopathological staining of the intima of aorta and liver of the two groups of rabbits. The differential proteins in the rabbit liver were analyzed using Tandem Mass Tags proteomic analysis technology. Finally, we used western blot to verify the reliability of proteomics. The results showed that compared with the control group, the serum lipid levels of rats in the HCD group was significantly increased, and the pathological sections showed the formation of atherosclerotic plaques in the aorta, inflammation, and adipose lesions in the liver. Proteomic analysis of the liver revealed 149 differences in HCD-expressed protein, which is mainly involved in inflammation and regulation of lipid and sugar metabolism. In addition, we verified differentially expressed liver proteins in the HCD group using western blot. We found that HCD caused lipid accumulation, abnormal glucose metabolism, and inflammatory response in the liver.

Cryo-EM structure of human voltage-gated sodium channel Nav1.6.

Voltage-gated sodium channel Nav1.6 plays a crucial role in neuronal firing in the central nervous system (CNS). Aberrant function of Nav1.6 may lead to epilepsy and other neurological disorders. Specific inhibitors of Nav1.6 thus have therapeutic potentials. Here we present the cryo-EM structure of human Nav1.6 in the presence of auxiliary subunits ß1 and fibroblast growth factor homologous factor 2B (FHF2B) at an overall resolution of 3.1 Å. The overall structure represents an inactivated state with closed pore domain (PD) and all "up" voltage-sensing domains. A conserved carbohydrate-aromatic interaction involving Trp302 and Asn326, together with the ß1 subunit, stabilizes the extracellular loop in repeat I. Apart from regular lipids that are resolved in the EM map, an unprecedented Y-shaped density that belongs to an unidentified molecule binds to the PD, revealing a potential site for developing Nav1.6-specific blockers. Structural mapping of disease-related Nav1.6 mutations provides insights into their pathogenic mechanism.

Structural basis for the severe adverse interaction of sofosbuvir and amiodarone on L-type Cav channels.

Drug-drug interaction of the antiviral sofosbuvir and the antiarrhythmics amiodarone has been reported to cause fatal heartbeat slowing. Sofosbuvir and its analog, MNI-1, were reported to potentiate the inhibition of cardiomyocyte calcium handling by amiodarone, which functions as a multi-channel antagonist, and implicate its inhibitory effect on L-type Cav channels, but the molecular mechanism has remained unclear. Here we present systematic cryo-EM structural analysis of Cav1.1 and Cav1.3 treated with amiodarone or sofosbuvir alone, or sofosbuvir/MNI-1 combined with amiodarone. Whereas amiodarone alone occupies the dihydropyridine binding site, sofosbuvir is not found in the channel when applied on its own. In the presence of amiodarone, sofosbuvir/MNI-1 is anchored in the central cavity of the pore domain through specific interaction with amiodarone and directly obstructs the ion permeation path. Our study reveals the molecular basis for the physical, pharmacodynamic interaction of two drugs on the scaffold of Cav channels.

Consequences of Preoperative Oral Carbohydrate Consumption in Septal Deviation Patients Undergoing Endoscopic Septoplasty: A Retrospective Cohort Study.

PURPOSE: Multiple reports have demonstrated the benefits of preoperative oral carbohydrates (CHO) in patients receiving open abdominal, thoracic, and orthopedic surgeries. However, thus far, no reports have investigated the benefits of CHO in patients undergoing nasal endoscopic surgery. Our goal was to evaluate the outcome of preoperative oral of administration of CHO in septal deviation patients, undergoing endoscopic septoplasty, under general anesthesia. DESIGN: A retrospective cohort study from a prospectively collected database. METHODS: Consecutive 400 septal deviation patients, undergoing endoscopic septoplasty, were randomly assigned to receive CHO or plain water (80 CHO cohort vs. 320 control cohort) before general anesthesia. The primary outcome was the risk of acute postoperative hypertension (APH). The secondary outcomes included length of hospital stay (LOS), hospitalization cost, sleep time the day before surgery, fluid infusion volume on surgical day, as well the incidence of postoperative nausea and vomiting (PONV) and aspiration. FINDINGS: Patients in the CHO cohort experienced a lower risk of both diastolic blood pressure (DBP)-based APH (OR, 0.49; 95% CI, 0.25 to 0.96; P = 0.0375) and total APH (OR, 0.49; 95% CI, 0.26 to 0.92; P = 0.0258), lower LOS, lower hospitalization cost, longer sleep time and less fluid infusion volume after adjusting for gender, age, BMI, preoperative blood pressure and pulse. Besides, data showed no significant differences in the incidence of (P = 0.4173) and aspiration (P > 0.99). CONCLUSIONS: Preoperative CHO administration can reduce APH risk in patients undergoing endoscopic septoplasty under general anesthesia. Besides, preoperative CHO administration can improve other clinical outcomes, such as, LOS, hospitalization cost, sleep time, and fluid infusion volume. Moreover, CHO safety was confirmed in our study. In the future, additional investigation is necessary to confirm our results.

Unwinding and spiral sliding of S4 and domain rotation of VSD during the electromechanical coupling in Nav1.7.

Voltage-gated sodium (Nav) channel Nav1.7 has been targeted for the development of nonaddictive pain killers. Structures of Nav1.7 in distinct functional states will offer an advanced mechanistic understanding and aid drug discovery. Here we report the cryoelectron microscopy analysis of a human Nav1.7 variant that, with 11 rationally introduced point mutations, has a markedly right-shifted activation voltage curve with V1/2 reaching 69 mV. The voltage-sensing domain in the first repeat (VSDI) in a 2.7-Å resolution structure displays a completely down (deactivated) conformation. Compared to the structure of WT Nav1.7, three gating charge (GC) residues in VSDI are transferred to the cytosolic side through a combination of helix unwinding and spiral sliding of S4I and ∼20° domain rotation. A conserved WNФФD motif on the cytoplasmic end of S3I stabilizes the down conformation of VSDI. One GC residue is transferred in VSDII mainly through helix sliding. Accompanying GC transfer in VSDI and VSDII, rearrangement and contraction of the intracellular gate is achieved through concerted movements of adjacent segments, including S4-5I, S4-5II, S5II, and all S6 segments. Our studies provide important insight into the electromechanical coupling mechanism of the single-chain voltage-gated ion channels and afford molecular interpretations for a number of pain-associated mutations whose pathogenic mechanism cannot be revealed from previously reported Nav structures.

Structural basis for high-voltage activation and subtype-specific inhibition of human Nav1.8.

The dorsal root ganglia-localized voltage-gated sodium (Nav) channel Nav1.8 represents a promising target for developing next-generation analgesics. A prominent characteristic of Nav1.8 is the requirement of more depolarized membrane potential for activation. Here we present the cryogenic electron microscopy structures of human Nav1.8 alone and bound to a selective pore blocker, A-803467, at overall resolutions of 2.7 to 3.2 Å. The first voltage-sensing domain (VSDI) displays three different conformations. Structure-guided mutagenesis identified the extracellular interface between VSDI and the pore domain (PD) to be a determinant for the high-voltage dependence of activation. A-803467 was clearly resolved in the central cavity of the PD, clenching S6IV. Our structure-guided functional characterizations show that two nonligand binding residues, Thr397 on S6I and Gly1406 on S6III, allosterically modulate the channel's sensitivity to A-803467. Comparison of available structures of human Nav channels suggests the extracellular loop region to be a potential site for developing subtype-specific pore-blocking biologics.

A survey of cognitive function in peritoneal dialysis patients.

INTRODUCTION: The aim of this study was to investigate how peritoneal dialysis and other influencing factors affect patients' cognitive function. METHODS: The 85 subjects in the study group were regular patients in our center. The control group included 88 age and gender matched healthy individuals who were with normal renal function. The study subjects' cognitive levels and related factors were analyzed using several screening instruments: the cognitive function was measured using the Montreal Cognitive Assessment Scale and statistical analysis was conducted based on the relevant data. RESULTS: The results showed that cognitive impairment was higher in peritoneal dialysis patients than in non-dialysis subjects. Age and educational background were single factors that affected cognitive function, which was more likely to be impaired at a higher age level and/or a lower educational level. CONCLUSION: Cognitive function can be impaired by peritoneal dialysis, and age and education levels are influencing factors.

Structural Basis for Pore Blockade of the Human Cardiac Sodium Channel Nav 1.5 by the Antiarrhythmic Drug Quinidine*.

Nav 1.5, the primary voltage-gated Na+ (Nav ) channel in heart, is a major target for class I antiarrhythmic agents. Here we present the cryo-EM structure of full-length human Nav 1.5 bound to quinidine, a class Ia antiarrhythmic drug, at 3.3 Šresolution. Quinidine is positioned right beneath the selectivity filter in the pore domain and coordinated by residues from repeats I, III, and IV. Pore blockade by quinidine is achieved through both direct obstruction of the ion permeation path and induced rotation of an invariant Tyr residue that tightens the intracellular gate. Structural comparison with a truncated rat Nav 1.5 in the presence of flecainide, a class Ic agent, reveals distinct binding poses for the two antiarrhythmics within the pore domain. Our work reported here, along with previous studies, reveals the molecular basis for the mechanism of action of class I antiarrhythmic drugs.

Structure of human Nav1.5 reveals the fast inactivation-related segments as a mutational hotspot for the long QT syndrome.

Nav1.5 is the primary voltage-gated Na+ (Nav) channel in the heart. Mutations of Nav1.5 are associated with various cardiac disorders exemplified by the type 3 long QT syndrome (LQT3) and Brugada syndrome (BrS). E1784K is a common mutation that has been found in both LQT3 and BrS patients. Here we present the cryo-EM structure of the human Nav1.5-E1784K variant at an overall resolution of 3.3 Å. The structure is nearly identical to that of the wild-type human Nav1.5 bound to quinidine. Structural mapping of 91- and 178-point mutations that are respectively associated with LQT3 and BrS reveals a unique distribution pattern for LQT3 mutations. Whereas the BrS mutations spread evenly on the structure, LQT3 mutations are clustered mainly to the segments in repeats III and IV that are involved in gating, voltage-sensing, and particularly inactivation. A mutational hotspot involving the fast inactivation segments is identified and can be mechanistically interpreted by our "door wedge" model for fast inactivation. The structural analysis presented here, with a focus on the impact of mutations on inactivation and late sodium current, establishes a structure-function relationship for the mechanistic understanding of Nav1.5 channelopathies.