The Energetic Origins of Pi-Pi Contacts in Proteins.

Accurate potential energy models of proteins must describe the many different types of noncovalent interactions that contribute to a protein's stability and structure. Pi-pi contacts are ubiquitous structural motifs in all proteins, occurring between aromatic and nonaromatic residues and play a nontrivial role in protein folding and in the formation of biomolecular condensates. Guided by a geometric criterion for isolating pi-pi contacts from classical molecular dynamics simulations of proteins, we use quantum mechanical energy decomposition analysis to determine the molecular interactions that stabilize different pi-pi contact motifs. We find that neutral pi-pi interactions in proteins are dominated by Pauli repulsion and London dispersion rather than repulsive quadrupole electrostatics, which is central to the textbook Hunter-Sanders model. This results in a notable lack of variability in the interaction profiles of neutral pi-pi contacts even with extreme changes in the dielectric medium, explaining the prevalence of pi-stacked arrangements in and between proteins. We also find interactions involving pi-containing anions and cations to be extremely malleable, interacting like neutral pi-pi contacts in polar media and like typical ion-pi interactions in nonpolar environments. Like-charged pairs such as arginine-arginine contacts are particularly sensitive to the polarity of their immediate surroundings and exhibit canonical pi-pi stacking behavior only if the interaction is mediated by environmental effects, such as aqueous solvation.

Hexavalent Chromium as a Smart Switch for Peroxidase-like Activity Regulation via the Surface Electronic Redistribution of Silver Nanoparticles Anchored on Carbon Spheres.

Although some ions, due to their unique chemical properties, can regulate the enzyme-like activity of nanomaterials, it is still a huge challenge to explore the mechanism of regulation. Herein, we found that Cr6+ (CrO42-) as a smart switch can significantly increase the peroxidase-like (POD-like) activity of silver nanoparticles (Ag NPs), which were anchored efficiently on carbon spheres (Cal-CS/PEG/Ag) using amino-modified poly(ethylene glycol) (PEG) as a bridge. Density functional theory (DFT) calculations demonstrated that the addition of Cr6+ can not only adjust the surface electronic redistribution of Ag atoms but also improve the geometric structure of the adsorbed intermediate, which resulted in the optimization of free energy and change of bond lengths in the catalytic reaction process, increasing the POD-like activity of Cal-CS/PEG/Ag. Based on the Cr6+-increased POD-like activity of Cal-CS/PEG/Ag, we successfully constructed a visual sensor of Cr6+ along with quantitative analysis by the UV spectrum. The sensor has good selectivity for other 29 interfering ions and molecules with a detection limit of 79 nM. In this work, the detailed mechanism of the Cr6+-increased POD-like activity of Ag NPs was studied and a new possibility for the rational design of ion visual sensors using nanomaterials was proposed.

Patient satisfaction and its health provider-related determinants in primary health facilities in rural China.

BACKGROUND: Patient satisfaction is an important outcome measure of health service and is one of the main reasons for the gradual deterioration of doctor-patient relationships in China. This study used the standardized patient (SP) method to explore patient satisfaction and its health provider-related determinants among primary health facilities in rural China. METHODS: The dataset comprised 1138 clinic cases in 728 rural primary health facilities in 31 counties, spread across four provinces. Information regarding the consultation interaction between the unannounced SPs and primary physicians was recorded. Patient satisfaction was gathered from the feedback of SPs after the visit. RESULTS: The overall average score of SP satisfaction with rural primary health facilities was only 13.65 (SD = 3.22) out of 20. The SP scores were found to be consistent with those of real patients. After controlling variances in patient population via the SP method, the regression analysis demonstrated that health provider-related factors, such as physician-level characteristics, consultation process, affordability, and convenience, have a significant correlation with patient satisfaction among primary physicians. Among factors relating to physician-level characteristics, affordability, convenience and the consultation process of the visit, the quality of the consultation process (e.g., consultation time, proactively providing necessary instructions and other crucial information) were found to be the prominent determinants. CONCLUSIONS: This study revealed the need to improve patient satisfaction in primary health facilities in rural China. To solve this issue, we recommend that policies to increase medical service quality be implemented in rural primary healthcare systems.

Knockdown of SGLT1 prevents the apoptosis of cardiomyocytes induced by glucose fluctuation via relieving oxidative stress and mitochondrial dysfunction.

Fluctuations in the concentration of glucose in the blood is more detrimental than a constantly high level of glucose with respect to the development of cardiovascular complications associated with diabetes mellitus (DM). Sodium glucose cotransporter 2 (SGLT2) inhibitors have been developed as antidiabetic drugs with cardiovascular benefits; however, whether inhibition of SGLT1 protects the diabetic heart remains to be determined. This study investigated the role of SGLT1 in rat H9c2 cardiomyocytes subjected to fluctuating levels of glucose and the underlying mechanisms. The results indicated that knockdown of SGLT1 restored cell proliferation and suppressed the cytotoxicity associated with fluctuating glucose levels. Oxidative stress was induced in H9c2 cells subjected to fluctuating glucose levels, but these changes were effectively reversed by knockdown of SGLT1, as manifested by reductions in the level of intracellular reactive oxygen species and increased antioxidant activity. Further study demonstrated that knockdown of SGLT1 attenuated the mitochondrial dysfunction in H9c2 cells exposed to fluctuating glucose levels, by restoring mitochondrial membrane potential and promoting mitochondrial fusion. In addition, knockdown of SGLT1 downregulated the expression of Bax, upregulated the expression of Bcl-2, and reduced the activation of caspase-3 in H9c2 cells subjected to fluctuating levels of glucose. Collectively, our results show that knockdown of SGLT1 ameliorates the apoptosis of cardiomyocyte caused by fluctuating glucose levels via regulating oxidative stress and combatting mitochondrial dysfunction.

Intermittent high glucose induces pyroptosis of rat H9C2 cardiomyocytes via sodium-glucose cotransporter 1.

Cardiomyocyte death is an important pathogenic process in cardiac complications of diabetes. Diabetic patients often suffer glycemic variability. Pyroptosis is a form of programmed cell death triggered by inflammasomes and related with caspase-1 and gasdermin D activation. The present study was designed to examine the effects of intermittent high glucose simulating glycemic variability on the pyroptosis of cardiomyocytes in vitro. Rat H9C2 cardiomyocytes were incubated with normal glucose (NG), constant high glucose (CHG) and intermittent high glucose (IHG). Results showed that compared to CHG treatment, IHG further inhibited cell proliferation and promoted cell death of H9C2 cardiomyocytes. In addition, IHG upregulated higher levels of the expressions of inflammasome NLR family pyrin domain containing 3 (NLRP3) and adaptor protein apoptosis-associated speck-like protein containing CARD domain (ASC) and increased higher levels of activated caspase-1 and gasdermin D than CHG treatment. Moreover, the production of reactive oxygen species (ROS) and activation of NF-κB that is induced by IHG were significantly higher than that induced by CHG. Knockdown of sodium-glucose cotransporters 1 (SGLT1) in H9C2 cardiomyocytes was performed and the effects of SGLT1 on IHG-induced pyroptosis was evaluated. The results demonstrated that knockdown of SGLT1 partially reduced IHG-induced pyroptosis, ROS generation and NF-κB activation. Our results indicated that IHG is harmful to cardiomyocytes and it might be partially because of the SGLT1-depedent pyroptosis in cardiomyocytes.

Investigation of the Detailed AMPylated Reaction Mechanism for the Huntingtin Yeast-Interacting Protein E Enzyme HYPE.

AMPylation is a prevalent posttranslational modification that involves the addition of adenosine monophosphate (AMP) to proteins. Exactly how Huntingtin-associated yeast-interacting protein E (HYPE), as the first human protein, is involved in the transformation of the AMP moiety to its substrate target protein (the endoplasmic reticulum chaperone binding to immunoglobulin protein (BiP)) is still an open question. Additionally, a conserved glutamine plays a vital key role in the AMPylation reaction in most filamentation processes induced by the cAMP (Fic) protein. In the present work, the detailed catalytic AMPylation mechanisms in HYPE were determined based on the density functional theory (DFT) method. Molecular dynamics (MD) simulations were further used to investigate the exact role of the inhibitory glutamate. The metal center, Mg2+, in HYPE has been examined in various coordination configurations, including 4-coordrinated, 5-coordinated and 6-coordinated. DFT calculations revealed that the transformation of the AMP moiety of HYPE with BiP followed a sequential pathway. The model with a 4-coordinated metal center had a barrier of 14.7 kcal/mol, which was consistent with the experimental value and lower than the 38.7 kcal/mol barrier of the model with a 6-coordinated metal center and the 31.1 kcal/mol barrier of the model with a 5-coordinated metal center. Furthermore, DFT results indicated that Thr518 residue oxygen directly attacks the phosphorus, while the His363 residue acts as H-bond acceptor. At the same time, an MD study indicated that Glu234 played an inhibitory role in the α-inhibition helix by regulating the hydrogen bond interaction between Arg374 and the Pγ of the ATP molecule. The revealed sequential pathway and the inhibitory role of Glu234 in HYPE were inspirational for understanding the catalytic and inhibitory mechanisms of Fic-mediated AMP transfer, paving the way for further studies on the physiological role of Fic enzymes.

Configurational Entropy of Folded Proteins and Its Importance for Intrinsically Disordered Proteins.

Many pairwise additive force fields are in active use for intrinsically disordered proteins (IDPs) and regions (IDRs), some of which modify energetic terms to improve the description of IDPs/IDRs but are largely in disagreement with solution experiments for the disordered states. This work considers a new direction-the connection to configurational entropy-and how it might change the nature of our understanding of protein force field development to equally well encompass globular proteins, IDRs/IDPs, and disorder-to-order transitions. We have evaluated representative pairwise and many-body protein and water force fields against experimental data on representative IDPs and IDRs, a peptide that undergoes a disorder-to-order transition, for seven globular proteins ranging in size from 130 to 266 amino acids. We find that force fields with the largest statistical fluctuations consistent with the radius of gyration and universal Lindemann values for folded states simultaneously better describe IDPs and IDRs and disorder-to-order transitions. Hence, the crux of what a force field should exhibit to well describe IDRs/IDPs is not just the balance between protein and water energetics but the balance between energetic effects and configurational entropy of folded states of globular proteins.

[Portable Pulse Detection System Based on IoT].

Aiming at the current situation of high cost, huge volume, complex operation and difficulty in real application of pulse analyzer, this study designs and implements a portable pulse detection system based on IoT. The design utilizes Raspberry Pi 3B+, STM32 series MCU and cloud server to collect, store, display and recognize pulse signals at CUN, GUAN and CHI. The system is small in size and low in cost, which can be connected with cloud server through network to make full use of resources. The experimental results show that the recognition accuracy of the main feature points of the pulse signal by the portable pulse analyzer is higher than 97%, which has a broad prospect of development and application.

Recombinant Cellular Repressor of E1A-Stimulated Genes Protects against Renal Fibrosis in Dahl Salt-Sensitive Rats.

BACKGROUND: Human cellular repressor of E1A-stimulated genes (CREG) is a secreted glycoprotein that attenuates angiotensin II-induced hypertension, alleviates myocardial fibrosis, and improves heart function. However, the role of CREG in high-salt (HS) diet-induced hypertensive nephropathy is unclear. METHODS: To determine the effects and molecular mechanisms of CREG in HS diet-induced hypertensive nephropathy, we established a hypertensive nephropathy animal model in Dahl salt-sensitive (SS) rats fed a HS diet (8% NaCl, n = 20) for 8 weeks. At week 4 of HS loading, these rats were administered recombinant CREG (reCREG; 35 µg/kg·day, n = 5) and saline (n = 5) via subcutaneously implanted pumps and were also administered the vasodilator hydralazine (20 mg/kg·day, n = 5) in drinking water. We used hematoxylin and eosin staining, Masson's trichrome staining, immunohistochemical labeling, western blotting, RT-PCR, and Tunel staining to determine the signaling pathways of CREG in HS diet-induced hypertensive nephropathy. RESULTS: After 8 weeks of HS intake, the Dahl SS rats developed renal dysfunction and severe renal fibrosis associated with reductions of 78 and 67% in CREG expression, respectively, at both mRNA and protein levels in the kidney. Administration of reCREG improved renal function and relieved renal fibrosis. Administration of CREG also inhibited monocyte infiltration and reduced apoptosis in the kidney cells. CREG overexpression upregulated forkhead box P1 expression and inhibited the transforming growth factor-ß1 signaling pathway. CONCLUSION: Our study shows that CREG protected the kidney against HS-diet-induced renal damage and provides new insights into the mechanisms underlying kidney injury.

Chemokine CC-motif ligand 2 participates in platelet function and arterial thrombosis by regulating PKCα-P38MAPK-HSP27 pathway.

BACKGROUND: Studies indicate that chemokine CC-motif ligand 2 (CCL2) is involved in inflammation and atherosclerosis. However, the roles and mechanisms of CCL2 on platelet function and arterial thrombosis are unknown. METHODS: The expressions of CCL2 or CCR2 in the plasma, platelets and coronary thrombus of ST-elevated myocardial infarction (STEMI) patients were examined by ELISA, Western blot, immunohistochemistry and immunofluorescence. The roles of CCL2 on platelet aggregation, activation and secretion were examined by light transmission aggregometry, flow cytometry and ELISA. RESULTS: The expressions of CCL2 or CCR2 in the plasma or platelets of STEMI patients with platelet high response were higher than those with platelet normal response; In vitro, exogenous recombinant human CCL2 markedly increased platelet aggregation, activation and granule secretion, which were abolished by CCL2 neutralizing antibody or CCR2 inhibiter. CCL2 increased the phosphorylation levels of PKCα (Thr638), P38MAPK (Thr180/Tyr182) and HSP27 (S78/S82) in human platelets, which were abrogated by PKCα inhibitor (RO 318220) or P38MAPK inhibitor (SB 203580). RO 318220 or SB 203580 diminished CCL2-induced platelet function. In CCL2-/- mice, platelet aggregation and secretion were attenuated; the phosphorylation of PKCα, P38MAPK and HSP27 were decreased. In a carotid arterial thrombus mouse model, CCL2-/- mice displayed a significantly extended carotid artery occlusion time compared with wild type. CONCLUSIONS: CCL2 played important roles in regulating platelet function and arterial thrombosis through the PKCα-P38MAPK-HSP27 pathway, which might provide theoretical basis for searching new antiplatelet drugs and the treatment for cardiovascular diseases.

Cellular Repressor of E1A-Stimulated Genes Is a Critical Determinant of Vascular Remodeling in Response to Angiotensin II.

OBJECTIVE: Cellular repressor of E1A-stimulated genes (CREG) is a lysosomal glycoprotein implicated in maintaining vascular homeostasis. Here, we have hypothesized that CREG is a critical target of intervention for the prevention of hypertensive vascular remodeling. APPROACH AND RESULTS: CREG gene expression was significantly decreased accompanied by an upregulated expression of angiotensin II (Ang II) in remodeled vascular tissues of high salt-induced Dahl salt-sensitive rats and Ang II-induced mice. In particular, the downregulation of CREG gene was Ang II specific and independent from blood pressure. Prominent medial hypertrophy and vascular fibrosis in both thoracic aortas and mesenteric arteries were observed in CREG+/- mice infused with Ang II than in CREG+/+ mice, but blunted response in CREG+/+ mice received recombinant human CREG protein, suggesting that changes in CREG expression account for the different phenotype between genotypes. Within a tiled promoter array, E26 transformation-specific-1 binds to CREG promoter at high stringency with the stimulation of Ang II. Moreover, the Ang II-induced E26 transformation-specific-1 directly interacted with the CREG promoter (-1179 and -271 bp) and inhibited its transcription in vascular smooth muscle cells. Selective, pharmacological inhibition of E26 transformation-specific-1 led to restoration of CREG expression in aortas and rescue of experimental vascular remodeling by systemic administration of dominant negative E26 transformation-specific-1 membrane-permeable peptides. CONCLUSIONS: CREG is a novel mediator of vascular remodeling in response to Ang II and may be an attractive therapeutic target for prevention of vascular diseases.

CREG protects from myocardial ischemia/reperfusion injury by regulating myocardial autophagy and apoptosis.

AIMS: Human cellular repressor of E1A-stimulated genes (CREG) is a secreted glycoprotein that regulates tissue and cell homeostasis and has been shown to antagonize heart fibrosis, which indicates a potential protective effect of CREG against cardiomyocyte chronic damage. However, little is known about the role of CREG in myocardial tissue acute injury, in this study, we aimed to investigate the role of CREG in myocardial ischemia/reperfusion (MI/R) injury and clarify the mechanism of action. METHODS AND RESULTS: Wild-type Creg (Creg+/+), heterozygous Creg (Creg+/-) mice and mice pretreated with infusion of recombinant 0.3mg/kg·d CREG protein (reCreg+/+) were subjected to 30min of left ascending coronary ischemia and 24h of reperfusion. Evan's Blue-triphenyl- tetrazolium chloride (TTC) solution and echocardiography analysis were used to evaluate the effects of CREG on MI/R mice. The underlying mechanisms were further determined by cultured myocardial cells in vitro. Our findings revealed that the level of CREG protein in mouse hearts was significantly decreased after mice were subjected to MI/R. Moreover, Creg+/- mice had larger infarction size 2h after reperfusion and worse cardiac function 28days after MI/R injury compared to that in Creg+/+ mice. However, reCreg+/+ mice could maintain CREG at a high level even after MI/R injury, and mitigated infarction size and improved cardiac function significantly. In Creg+/- mice, myocardial autophagy was dysfunctional characterized by accumulation of LC3A and p62, while apoptotic cell number increase was detected by cleaved caspase-3 blotting and TUNEL staining. Conversely, decreased apoptosis and activated autophagy were detected in reCreg+/+ mice. Furthermore, chloroquine, a kind of autophagy blocker, was used to demonstrate recombinant CREG protected cardiomyocytes against apoptosis mediated by activating autophagy both in vivo and in vitro. Finally, we found CREG was involved into lysosomal protein transfer and improve cellular autophagy. CONCLUSION: CREG protects heart against MI/R injury-induced cardiomyocytes apoptosis by activating lysosomal autophagy. This article is part of a Special Issue entitled: Genetic and epigenetic control of heart failure - edited by Jun Ren and Megan Yingmei Zhang.

Quantitative Studies of Endothelial Cell Fibronectin and Filamentous Actin (F-Actin) Coalignment in Response to Shear Stress.

Both fibronectin (FN) and filamentous actin (F-actin) fibers play a critical role for endothelial cells (ECs) in responding to shear stress and modulating cell alignment and functions. FN is dynamically coupled to the F-actin cytoskeleton via focal adhesions. However, it is unclear how ECs cooperatively remodel their subcellular FN matrix and intracellular F-actin cytoskeleton in response to shear stress. Current studies are hampered by the lack of a reliable and sensitive quantification method of FN orientation. In this study, we developed a MATLAB-based feature enhancement method to quantify FN and F-actin orientation. The role of F-actin in FN remodeling was also studied by treating ECs with cytochalasin D. We have demonstrated that FN and F-actin codistributed and coaligned parallel to the flow direction, and that F-actin alignment played an essential role in regulating FN alignment in response to shear stress. Our findings offer insight into how ECs cooperatively remodel their subcellular ECM and intracellular F-actin cytoskeleton in response to mechanical stimuli, and are valuable for vascular tissue engineering.

Psychometric testing of the Chinese Mandarin version of the Mental Health Inventory among Chinese patients with coronary heart disease in Mainland China.

This study aimed to develop a Chinese Mandarin version of the Mental Health Inventory (CM:MHI). The English version MHI was translated into Chinese (simple Chinese character) using the forward-backward translation method while establishing the semantic equivalence and content validity. A convenience sample of 204 coronary heart disease (CHD) patients was recruited to evaluate the internal consistency, concurrent validity and construct validity of the CM:MHI. Forty patients completed the CM:MHI to evaluate the test-retest reliability after 2 weeks. The CM:MHI demonstrated good semantic equivalent rate (92%) and satisfactory content validity index (0.91). The internal consistency was acceptable for total and all subscales with Cronbach's alpha greater than 0.70, with the exception of the subscale of Emotional Ties (Cronbach's alpha = 0.64). The test-retest reliability was also satisfactory with intraclass correlation coefficients higher than 0.75. The concurrent validity was acceptable with significantly strong correlations between the CM:MHI and the Chinese Mandarin versions of Short Form 36 Health survey and Hospital Anxiety and Depression Scale. Confirmatory factor analysis further supported the five-factor structure of the CM:MHI. The CM:MHI demonstrated to be a valid and reliable measure for assessing psychological distress and well-being in Chinese-speaking CHD patients.

Effects of supplementary Da Dingfeng Zhu therapy on patients with Parkinson's disease of liver-kidney yin deficiency pattern.

BACKGROUND: This study aimed to verify whether the combined use of Da Dingfengzhu and Western medicine in treating Parkinson's disease (PD) can lead to therapeutic efficacy and symptom alleviation, thereby achieving a complementary and synergistic effect. METHODS: In this study, 158 patients were initially enrolled, with 116 eligible patients randomly divided into a control and an observation group. The control group received levodopa/benserazide and pramipexole, while the observation group received Da Dingfengzhu combined with levodopa/benserazide and pramipexole for 12 weeks. Baseline patient characteristics, adverse reactions, and blood samples were collected at baseline and 12 weeks post-treatment. The Unified Parkinson's Disease Rating Scale (UPDRS) was used to assess symptom severity at baseline, four weeks into treatment, and 12 weeks post-treatment. RESULTS: Adverse reactions during treatment were similar in both groups, suggesting that the combined therapy in the observation group did not increase adverse effects. Both groups showed improvements in UPDRS scores, with the observation group displaying more significant symptom alleviation at 4 and 12 weeks. Moreover, the observation group exhibited more pronounced increases in serum neurotrophic factor-3 and dopamine levels and greater reductions in oxidative stress and inflammatory response markers. CONCLUSION: In conclusion, the combination of Da Dingfengzhu with levodopa/benserazide and pramipexole for treating PD shows significant clinical potential and is worthy of broader application.

TRIM55 Aggravates Cardiomyocyte Apoptosis After Myocardial Infarction via Modulation of the Nrf2/HO-1 Pathway.

Tripartite motif-containing 55 (Trim55) is mainly expressed in myocardium and skeletal muscle, which plays an important role in promoting the embryonic development of the mouse heart. We investigated the role of Trim55 in myocardial infarction and the associated molecular mechanisms. We studied both gain and loss of function in vivo and in vitro. The results showed that Trim55 knockout improved cardiac function and apoptosis after myocardial infarction, and overexpression aggravated cardiac function damage. The mechanism is that Trim55 interacts with nuclear factor, erythroid derived 2 (Nrf2) to accelerate its degradation and inhibit the expression of heme oxygenase 1, thereby promoting cardiomyocyte apoptosis.

Cervical Cancer Screening via Visual Inspection With Acetic Acid and Lugol Iodine for Triage of HPV-Positive Women.

Importance: Limited evidence supports the performance of human papillomavirus (HPV) DNA testing as a primary screening method, followed by triage with visual inspection with acetic acid, in areas with limited health care resources, as suggested by the 2021 World Health Organization guidelines. Objective: To evaluate the performance of visual inspection with acetic acid and Lugol iodine as a triage method for detecting cervical precancerous lesions among HPV-positive women in 1 visit. Design, Setting, and Participants: This cohort study examined the implementation of a government-led cervical cancer screening program conducted from January 1, 2016, to December 31, 2020, in Ordos City, China. Female residents, aged 35 to 64 years, who understood the screening procedures and voluntarily participated were included in the study. Women were excluded if they reported never having had sexual intercourse, were pregnant, had a hysterectomy, or had ever undergone treatment for cervical lesions. Statistical analysis was conducted from December 2022 to December 2023. Exposures: The program used the careHPV DNA assay as the primary screening method, and immediate triage was performed by visual inspection if HPV screening results were positive, with a 5-year screening interval. A colposcopy was performed for the women who had suspected cancer on visual inspection results or who were HPV positive and had abnormal visual inspection results, all in 1 visit. Main Outcomes and Measures: The rate of compliance with colposcopy and the detection rate of cervical intraepithelial neoplasia grade 2 or higher (CIN2+). Results: The study included 187 863 women (median age, 46 years [IQR, 40-52 years]) who participated in the program and had valid HPV test results. The overall prevalence of HPV positivity was 12.8% (24 070 of 187 863), and the adherence to triage with visual inspection among HPV-positive women was 93.9% (22 592 of 24 070). Among HPV-positive women, the rate of compliance with colposcopy was 65.6% (2714 of 4137), and the CIN2+ detection rate was 2.8% (643 of 22 592). Conclusions and Relevance: The findings of this cohort study suggest that the implementation of HPV testing, visual inspection, and colposcopy within 1 visit may mitigate losses to follow-up, detect precancerous lesions, and hold significant implications for screening in comparable areas with limited health care resources.

Involvement of large conductance Ca(2+)-activated K (+) channel in laminar shear stress-induced inhibition of vascular smooth muscle cell proliferation.

The large conductance Ca(2+)-activated K(+) (BK(Ca)) channel in vascular smooth muscle cell (VSMC) is an important potassium channel that can regulate vascular tone. Recent work has demonstrated that abnormalities in BK(Ca) channel function are associated with changes in cell proliferation and the onset of vascular disease. However, until today there are rare reports to show whether this channel is involved in VSMC proliferation in response to fluid shear stress (SS). Here we investigated a possible role of BK(Ca) channel in VSMC proliferation under laminar SS. Rat aortic VSMCs were plated in parallel-plate flow chambers and exposed to laminar SS with varied durations and magnitudes. VSMC proliferation was assessed by measuring proliferating cell nuclear antigen (PCNA) expression and DNA synthesis. BK(Ca) protein and gene expression was determined by flow cytometery and RT-PCR. The involvement of BK(Ca) in SS-induced inhibition of proliferation was examined by BK(Ca) inhibition using a BK(Ca) specific blocker, iberiotoxin (IBTX), and by BK(Ca) transfection in BK(Ca) non-expressing CHO cells. The changes in [Ca(2+)](i) were determined using a calcium-sensitive dye, fluo 3-AM. Membrane potential changes were detected with a potential-sensitive dye, DiBAC(4)(3). We found that laminar SS inhibited VSMC proliferation and stimulated BK(Ca) channel expression. Furthermore, laminar SS induced an increase in [Ca(2+)](i) and membrane hyperpolarization. Besides in VSMC, the inhibitory effect of BK(Ca) channel activity on cell proliferation in response to SS was also confirmed in BK(Ca)-transfected CHO cells showing a decline in proliferation. Blocking BK(Ca) channel reversed its inhibitory effect, providing additional support for the involvement of BK(Ca) in SS-induced proliferation reduction. Our results suggest, for the first time, that BK(Ca) channel mediates laminar SS-induced inhibition of VSMC proliferation. This finding is important for understanding the mechanism by which SS regulates VSMC proliferation, and should be helpful in developing strategies to prevent flow-initiated vascular disease formation.

Catalytic deAMPylation in AMPylation-inhibitory/assistant forms of FICD protein.

DeAMPylation, as a reversible reaction of AMPylation and mediated by the endoplasmic reticulum-localized enzyme FICD (filamentation induced by cAMP domain protein, also known as HYPE), is an important process in protein posttranslational modifications (PTMs). Elucidating the function and catalytic details of FICD is of vital importance to provide a comprehensive understanding of protein folding homeostasis. However, the detailed deAMPylation mechanism is still unclear. Furthermore, the role of a conserved glutamine (Glu234), that plays an inhibitory role in the AMPylation response, is still an open question in the deAMPylation process. In the present work, the elaborated deAMPylation mechanisms with AMPylation-inhibitory/assistant forms of FICD (wild type and Glu234Ala mutant) were investigated based on the QM(DFT)/MM MD approach. The results revealed that deAMPylation was triggered by proton transfer from protonated histidine (His363) to AMPylated threonine, instead of a nucleophilic attack of water molecules adding to the phosphorus of AMP. The free energy barrier of deAMPylation in the wild type (∼17.3 kcal/mol) is consistent with that in the Glu234Ala mutant of FICD (∼17.1 kcal/mol), suggesting that the alteration of the Glu234 residue does not affect the deAMPylation reaction and indirectly verifying the inducement of deAMPylation in FICD. In the wild type, the proton in the nucleophilic water molecule is transferred to Glu234, whereas it is delivered to Asp367 through the hydrogen-bond network of coordinated water molecules in the Glu234Ala mutant. The present findings were inspirational for understanding the catalytic and inhibitory mechanisms of FICD-mediated AMP transfer, paving the way for further studies on the physiological role of FICD protein.

Dynamic changes in lactate levels within the first 24 hours in septic patients as a prognostic indicator: A retrospective cohort study utilizing latent class growth analysis.

Elevated lactate levels are common in sepsis patients. This study aimed to assess the effect of dynamic changes in lactate levels within the first 24 hours following admission on patient prognosis. We extracted data from the Medical Information Mart for Intensive Care (MIMIC)-IV database and classified patients using latent class growth analysis (LCGA). This analysis classified sepsis patients into different groups based on dynamic changes in lactate levels during the initial 24 hours post-admission, dividing this time frame into four periods (0-3 h, 3-6 h, 6-12 h, and 12-24 h). The highest lactate level recorded in each period was then used for patient classification. We subsequently compared the baseline characteristics and outcomes between these different groups. Our study encompassed 7,830 patients, whom LCGA successfully divided into two classes: class 1 (steady lactate class) and class 2 (increasing lactate class). Class 2 demonstrated a worse clinical status at baseline, as indicated by vital signs, disease severity scores, and laboratory results. Importantly, class 2 also had a significantly higher 28-day mortality rate than class 1 (55.6% vs 13.5%, P < 0.001). In conclusion, LCGA effectively categorized sepsis patients into two distinct groups based on their dynamic changes in lactate levels during the first 24 hours post-admission. This methodology has potential utility in clinical practice for managing sepsis patients.