Search Results (260)

The cement sheath is critical for ensuring the long-term safety and operational efficiency of oil and gas wells. However, complex geological conditions and operational stresses during production can induce cement sheath deterioration and cracking, leading to reduced zonal isolation, diminished hydrocarbon recovery, and elevated operational expenditures. This study investigates the development of a novel microbial self-healing well cement slurry system, employing fly ash as microbial carriers and sustained-release microcapsules encapsulating calcium sources and nutrients. Systematic evaluations were conducted, encompassing microbial viability, cement slurry rheology, fluid loss control, anti-channeling capability, and the mechanical strength, permeability, and microstructural characteristics of set cement stones. Results demonstrated that fly ash outperformed blast furnace slag and nano-silica as a carrier, exhibiting superior microbial loading capacity and viability. Optimal performance was observed with additions of 3% microorganisms and 3% microcapsules to the cement slurry. Microscopic analysis further revealed effective calcium carbonate precipitation within and around micro-pores, indicating a self-healing mechanism. These findings highlight the significant potential of the proposed system to enhance cement sheath integrity through localized self-healing, offering valuable insights for the development of advanced, durable well-cementing materials tailored for challenging downhole environments. Full article

Redox regulation is crucial for the cardiac action potential, coordinating the sodium-driven depolarization, calcium-mediated plateau formation, and potassium-dependent repolarization processes required for proper heart function. Under physiological conditions, low-level reactive oxygen species (ROS), generated by mitochondria and membrane oxidases, adjust ion channel function and support excitation–contraction coupling. However, when ROS accumulate, they modify a variety of important channel proteins in cardiomyocytes, which commonly results in reducing potassium currents, enhancing sodium and calcium influx, and enhancing intracellular calcium release. These redox-driven alterations disrupt the cardiac rhythm, promote after-depolarizations, impair contractile force, and accelerate the development of heart diseases. Experimental models demonstrate that oxidizing agents reduce repolarizing currents, whereas reducing systems restore normal channel activity. Similarly, oxidative modifications of calcium-handling proteins amplify sarcoplasmic reticulum release and diastolic calcium leak. Understanding the precise redox-dependent modifications of cardiac ion channels would guide new possibilities for targeted therapies aimed at restoring electrophysiological homeostasis under oxidative stress, potentially alleviating myocardial infarction and cardiovascular dysfunction. Full article

Calcium (Ca²⁺) signaling is a fundamental regulatory mechanism controlling essential processes in the endothelium, vascular smooth muscle cells (VSMCs), and the extracellular matrix (ECM), including maintaining the endothelial barrier, modulation of vascular tone, and vascular remodeling. Cytosolic free Ca²⁺ concentration is tightly regulated by a balance between Ca²⁺ mobilization mechanisms, including Ca²⁺ release from the intracellular stores in the sarcoplasmic/endoplasmic reticulum and Ca²⁺ entry via voltage-dependent, transient-receptor potential, and store-operated Ca²⁺ channels, and Ca²⁺ elimination pathways including Ca²⁺ extrusion by the plasma membrane Ca²⁺-ATPase and Na⁺/Ca²⁺ exchanger and Ca²⁺ re-uptake by the sarco(endo)plasmic reticulum Ca²⁺-ATPase and the mitochondria. Some cell membranes/organelles are multifunctional and have both Ca²⁺ mobilization and Ca²⁺ removal pathways. Also, the individual Ca²⁺ handling pathways could be integrated to function in a regenerative, capacitative, cooperative, bidirectional, or reciprocal feed-forward or feed-back manner. Disruption of these pathways causes dysregulation of the Ca²⁺ signaling dynamics and leads to pathological cardiovascular conditions such as hypertension, coronary artery disease, atherosclerosis, and vascular calcification. In the endothelium, dysregulated Ca²⁺ signaling impairs nitric oxide production, reduces vasodilatory capacity, and increases vascular permeability. In VSMCs, Ca²⁺-dependent phosphorylation of the myosin light chain and Ca²⁺ sensitization by protein kinase-C (PKC) and Rho-kinase (ROCK) increase vascular tone and could lead to increased blood pressure and hypertension. Ca²⁺ activation of matrix metalloproteinases causes collagen/elastin imbalance and promotes vascular remodeling. Ca²⁺-dependent immune cell activation, leukocyte infiltration, and cholesterol accumulation by macrophages promote foam cell formation and atherosclerotic plaque progression. Chronic increases in VSMCs Ca²⁺ promote phenotypic switching to mesenchymal cells and osteogenic transformation and thereby accelerate vascular calcification and plaque instability. Emerging therapeutic strategies targeting these Ca²⁺-dependent mechanisms, including Ca²⁺ channel blockers and PKC and ROCK inhibitors, hold promise for restoring Ca²⁺ homeostasis and mitigating vascular disease progression. Full article

The search for novel compounds with anticonvulsant properties remains a key focus in neuropharmacology. Recently, the diazepine-benzimidazole derivative, DAB-19, has emerged as a promising candidate due to its demonstrated anxiolytic and analgesic effects. In this study, we investigate the mechanisms underlying DAB-19’s activity, focusing on its impact on glutamatergic transmission, a key target in the pathophysiology of various central nervous system disorders. Intriguingly, while DAB-19 suppressed evoked glutamatergic transmission in rat brain slices, it simultaneously enhanced spontaneous neurotransmission. Further experiments on glutamatergic neuromuscular synapses in fly larvae revealed two distinct mechanisms: calcium-dependent potentiation of glutamate release and inhibition of spike propagation via blockade of voltage-gated sodium channels. The latter effect was directly confirmed in rat brain neurons. Given its action on sodium channels, we tested DAB-19 in the pentylenetetrazole model, where it delayed seizure onset but did not prevent seizures. These findings position DAB-19 as a multifaceted compound with significant therapeutic potential. Full article

Neuropathic pain is a chronic and debilitating disorder of the somatosensory system that affects a significant proportion of the population and is characterized by abnormal responses such as hyperalgesia and allodynia. Voltage-gated ion channels, including sodium (Na_V), calcium (Ca_V), and potassium (K_V) channels, play a pivotal role in modulating neuronal excitability and pain signal transmission following nerve injury. This review intends to provide a comprehensive analysis of the molecular and cellular mechanisms by which dysregulation in the expression, localization, and function of specific Na_V channel subtypes (mainly Na_V1.7 and Na_V1.8) and their auxiliary subunits contributes to aberrant neuronal activation, the generation of ectopic discharges, and sensitization in neuropathic pain. Likewise, special emphasis is placed on the crucial role of Ca_V channels, particularly Ca_V2.2 and the auxiliary subunit Ca_Vα₂δ, whose overexpression increases calcium influx, neurotransmitter release, and neuronal hyperexcitability, thus maintaining persistent pain states. Furthermore, K_V channels (particularly K_V7 channels) function as brakes on neuronal excitability, and their dysregulation facilitates the development and maintenance of neuropathic pain. Therefore, targeting specific K_V channel subtypes to restore their function is also a promising therapeutic strategy for alleviating neuropathic pain symptoms. On the other hand, recent advances in the development of small molecules as selective modulators or inhibitors targeting voltage-gated ion channels are also discussed. These agents have improved efficacy and safety profiles in preclinical and clinical studies by attenuating pathophysiological channel activity and restoring neuronal function. This review seeks to contribute to guiding future research and drug development toward more effective mechanism-based treatments by discussing the molecular mechanisms underlying neuropathic pain and highlighting translational therapeutic opportunities. Full article

Hypertension disorders of pregnancy affect almost 10% of pregnancies. Most hypertensive disorders associated with pregnancy, including chronic hypertension and gestational hypertension, often persist into the postpartum period. Thus, many breastfeeding mothers require ongoing antihypertensive treatment with antihypertensive medications while nursing. This highlights the importance of understanding the efficacy, safety, and potential adverse effects of antihypertensive therapy in breastfeeding mothers. Unfortunately, research in this area is limited, and references in clinical guidelines remain sparse. Our review aims to provide a comprehensive summary of the current knowledge on antihypertensive medications during breastfeeding, drawing from available research and evidence-based guidelines. This article discusses all groups of antihypertensive drugs, presenting societies’ recommendations and available clinical data. Based on the available literature, calcium channel blockers (extended-release nifedipine as the first choice) and beta-blockers (labetalol, metoprolol) appear to be the drugs of choice. Our review highlights the need for further research to evaluate the long-term safety of antihypertensive medications during breastfeeding, improve clinical guidelines, and ensure optimal treatment for nursing mothers. Full article

Ryanodine receptors (RyRs) are large intracellular Ca²⁺ release channels primarily found in muscle and nerve cells and also present at low levels in pancreatic islet endocrine cells. This review examines the role of RyRs in islet cell function, focusing on calcium signaling and hormone secretion, while addressing the ongoing debate regarding their significance due to their limited expression. We explore conflicting experimental results and their potential causes, synthesizing current knowledge on RyR isoforms in islet cells, particularly in beta and delta cells. The review discusses how RyR-mediated calcium-induced calcium release enhances, rather than drives, glucose-stimulated insulin secretion. We examine the phosphorylation-dependent regulation of beta-cell RyRs, the concept of “leaky ryanodine receptors”, and the roles of RyRs in endoplasmic reticulum stress, apoptosis, store-operated calcium entry, and beta-cell electrical activity. The relationship between RyR dysfunction and the development of impaired insulin secretion in diabetes is assessed, noting their limited role in human diabetes pathogenesis given the disease’s polygenic nature. We highlight the established role of RyR-mediated CICR in the mechanism of action of common type 2 diabetes treatments, such as glucagon-like peptide-1, which enhances insulin secretion. By integrating findings from electrophysiological, molecular, and clinical studies, this review provides a balanced perspective on RyRs in islet cell physiology and pathology, emphasizing their significance in both normal insulin secretion and current diabetes therapies. Full article

Background: Blueberry anthocyanin such as Cyanidin-3-O-glucoside may help prevent Alzheimer’s disease. We aimed to investigate the preventive and therapeutic effects of Cyanidin-3-O-glucoside against Aβ_1–42-induced apoptosis of SH-SY5Y cells as well as the underlying mechanisms. Methods: Cell viability and intracellular and mitochondrial reactive oxygen species were detected by MTT, a reactive oxygen species detection kit, and a MitoSOX red mitochondrial superoxide indicator. The mitochondrial membrane potential, intracellular calcium ion content, and adenotriphophate (ATP) were identified via a mitochondrial membrane potential detection kit, calcium ion detection kit, and ATP detection kit, and apoptosis was detected via flow cytometry. Transcription of apoptosis-related genes was detected using real-time fluorescence quantitative polymerase chain reaction, and expression of apoptosis-related proteins was identified using Western blot. Results: We found that Cyanidin-3-O-glucoside could downregulate the expression of cytochrome c, caspase 9, caspase 3, and other genes and proteins, which consequently reduced the rate of apoptosis. Additionally, it could upregulate Bcl-2 gene and protein expression, downregulate Bax gene and protein expression, regulate mitochondrial membrane permeability and calcium-release channels, reduce calcium influx into mitochondria, maintain intracellular calcium ion levels, reduce intracellular levels of reactive oxygen species and increase ATP levels, maintain the mitochondrial membrane potential at a normal level, maintain normal mitochondrial functioning, and prevent apoptosis. Discussion: Taken together, Cyanidin-3-O-glucoside showed dose-dependent preventive and therapeutic effects against Aβ_1–42-induced apoptosis of SH-SY5Y cells. Conclusions: Cyanidin 3-O-glucoside showed a better preventive effect than therapeutic effect against Aβ_1–42-induced apoptosis in SH-SY5Y cells. Full article

High-risk neuroblastoma (HRNB) is an extracranial solid pediatric cancer. Despite the plethora of treatments available for HRNB, up to 65% of patients are refractory or exhibit an initial response to treatment that transitions to therapy-resistant relapse, which is invariably fatal. A key feature that promotes HRNB progression is aberrant calcium (Ca²⁺) signaling. Ca²⁺ signaling is regulated by several druggable channel proteins, offering tremendous therapeutic potential. Unfortunately, many of the Ca²⁺ channels in HRNB also perform fundamental functions in normal healthy cells, hence targeting them increases the potential for adverse effects. To overcome this challenge, we sought to identify novel Ca²⁺ signaling pathways that are observed in HRNB but not normal non-cancerous cells with the hypothesis that these novel pathways may serve as potential therapeutic targets. One Ca²⁺ signaling pathway that is deregulated in HRNB is store-operated Ca²⁺ entry (SOCE). SOCE relays the release of Ca²⁺ from the endoplasmic reticulum (ER) and Ca²⁺ influx via the plasma membrane and promotes cancer drug resistance by regulating transcriptional programming and the induction of mitochondrial Ca²⁺ (mtCa²⁺)-dependent signaling. mtCa²⁺ signaling is critical for cellular metabolism, reactive oxygen production, cell cycle, and proliferation and has a key role in the regulation of cell death. Therefore, a dynamic interplay between ER, SOCE, and mitochondria tightly regulates cell survival and apoptosis. From a library of synthesized novel molecules, we identified two structurally related compounds that uniquely disrupt the dynamic interplay between SOCE, ER, and mitochondrial signaling pathways and induce cell death in HRNB. Our results revealed that compounds 248 and 249 activate distinct aberrant Ca²⁺ signals that are unique to relapsed HRNB and could be exploited to induce mtCa⁺ overload, a novel calcium influx current, and subsequent cell death. These findings establish a potential new pathway of calcium-mediated cell death; targeting this pathway could be critical for the treatment of refractory and relapsed HRNB. Full article

Metabolic stress on the heart can cause dilation of coronary arterioles for blood flow recruitment. Although potassium ions (K⁺) released from the myocardium are a major mediator for this response, the underlying signaling pathways for vasodilation are incompletely understood. Herein, the roles of smooth muscle inward-rectifier K⁺ channel subtype 2.1 (K_ir2.1) and Na⁺/K⁺-ATPase were examined. Porcine coronary arterioles were isolated, cannulated, and pressurized for vasomotor study. Vessels developed basal tone and dilated concentration-dependently to extraluminal K⁺ from 7 to 20 mM. Higher K⁺ concentrations (25–40 mM) caused graded vasoconstriction. Vasodilation to K⁺ (10 mM) was not altered by endothelial removal, and blockade of ATP-sensitive K⁺ channels, voltage-sensitive K⁺ channels, or calcium-activated K⁺ channels did not affect K⁺-induced vasodilation. However, sustained but not abrupt transient vasodilation to K⁺ was reduced by the nonspecific K_ir channel inhibitor Ba²⁺ or K_ir2.1 channel blocker chloroethylclonidine. The Na⁺/K⁺-ATPase inhibitor ouabain attenuated K⁺-elicited vasodilation, and ouabain with Ba²⁺ abolished the response. Transfection of arterioles with K_ir2.1 antisense oligonucleotides abolished sustained but not transient dilation. It is concluded that extraluminal K⁺ elevation within the physiological range induces initial transient dilation of porcine coronary arterioles by activating smooth muscle Na⁺/K⁺-ATPase and sustained dilation via smooth muscle K_ir2.1 channels. Full article

Extracellular vesicles (EVs) contain bioactive lipids that play a key role in pathophysiology. We hypothesized that EVs released from salt-loaded hypertensive diabetic db/db mice have increased bioactive lipid content that inhibits intracellular calcium mobilization and increases the activity of renal epithelial sodium channels (ENaC). An enrichment of sphingomyelins (SMs) was found in small urinary EVs (uEVs) isolated from salt-loaded hypertensive diabetic db/db mice (n = 4) compared to non-salt loaded db/db mice with diabetes alone (n = 4). Both groups of mice were included in the same cohort to control for variability. Cultured mouse cortical collecting duct (mpkCCD) cells loaded with a calcium reporter dye and challenged with small uEVs from hypertensive diabetic db/db mice showed a decrease in calcium mobilization when compared to cells treated with small uEVs from diabetic db/db mice. The amiloride-sensitive transepithelial current was increased in mpkCCD cells treated with small uEVs with abundant sphingomyelin content from hypertensive diabetic db/db mice in a dose- and time-dependent manner. Similar results were observed in mpkCCD cells and Xenopus 2F3 cells treated with exogenous sphingomyelin in a time-dependent manner. Single-channel patch clamp studies showed a decrease in ENaC activity in cells transiently transfected with sphingomyelin synthase 1/2 specific siRNA compared to non-targeting siRNA. These data suggest EVs with high sphingomyelin content positively regulate renal ENaC activity in a mechanism involving an inhibition of calcium mobilization. Full article

The response of ryanodine receptor (RyR) channels to increases in free cytoplasmic calcium concentration ([Ca²⁺]) is tuned by several mechanisms, including redox signaling. Three different responses to [Ca²⁺] have been described in RyR channels, low, moderate and high activity responses, which depend on the RyR channel protein oxidation state. Thus, reduced RyR channels display the low activity response, whereas partially oxidized channels display the moderate response and more oxidized channels, the high activity response. As described here, RyR channels from rat brain cortices or hippocampi displayed aged-related marked changes in the distribution of these channel responses; RyR channels from aged rats displayed reduced fraction of low activity channels and increased fraction of high activity channels, which would favor Ca²⁺-induced Ca²⁺ release. In addition, compared with young rats, aged rats displayed learning and memory defects, with lower hit rates when tested in the Oasis maze, a dry version of the Morris water maze. Previous oral administration of N-acetylcysteine for 3 weeks prevented both the age-dependent effects on RyR channel activation by [Ca²⁺], and the learning and memory defects. Based on these results, it is proposed that redox-sensitive neuronal RyR channels partake in the mechanism underlying the learning and memory disruptions displayed by aged rats. Full article

Background: Transient receptor potential vanilloid subtype 4 (TRPV4) is a Ca²⁺-permeable non-selective cation channel that is involved in the development of cough hypersensitivity. Purinergic 2 receptors (P2X) belong to a class of adenosine triphosphate (ATP)-gated non-selective cation channels that also play an important role in cough hypersensitivity. Nevertheless, little is known about the interaction between them for cough hypersensitivity. The present study was designed to clarify the roles of TRPV4 and ATP-P2X receptors in cough hypersensitivity, and to explore the possible involvement of ATP-P2X receptors in the development of cough hypersensitivity mediated by TRPV4. Design and Method: This study aims to establish a guinea pig model of citric acid-induced enhanced cough to confirm the effects of the TRPV4-mediated purinergic signaling pathway on cough sensitivity by testing the number of coughs, the release of ATP, and the expressions of P2X and TRPV4 receptors in the tracheal carina and vagal ganglion; recording the activity of cellular currents with the whole-cell patch clamp technique; and detecting changes in intracellular calcium flow in the vagus nerve cells. Results: The number of coughs in the TRPV4 agonist GSK1016790A-treated control group was elevated compared with that in the control group, whereas the number of coughs in the TRPV4 antagonist HC067047-treated model group was significantly reduced compared with that in the chronic cough group. When the individuals in the chronic cough group were treated with A317491, PSB12062, and A804598 (P2X3,4,7 antagonists), the number of coughs was significantly decreased. This suggests that TRPV4 and P2X3, P2X4, and P2X7 receptors have an effect on cough hyper-responsiveness in guinea pigs with chronic cough. Enzyme-linked immunosorbent assay results suggested that TRPV4 antagonist and P2X3,4,7 antagonist could differentially reduce the levels of inflammatory factor SP and CGRP in alveolar lavage fluid, and TRPV4 antagonist could reduce the ATP content in the alveolar lavage fluid of guinea pigs in the model. Western blot and immunohistochemistry results showed that, in the tracheal carina and vagal ganglion, the TRPV4 and P2X3,4,7 expression was elevated in the chronic cough group compared with the control group, and could be significantly inhibited by TRPV4 antagonist. Vagus ganglion neurons were isolated, cultured, identified, and subjected to whole-cell membrane clamp assay. When ATP was given extracellularly, a significant inward current was recorded in the examined cells of individuals in the chronic cough and control groups, and the inward current induced by ATP was higher in the chronic cough group relative to the control group. This inward current (I_ATP) was differentially blocked by P2X3, P2X4, and P2X7 antagonists. Further studies revealed that TRPV4 agonists potentiated ATP-activated currents, and the potentiated currents could still be inhibited by P2X3, P2X4, and P2X7 receptor antagonists, whereas TRPV4 inhibitors partially blocked ATP-activated currents. It is suggested that TRPV4 affects P2X3, P2X4, and P2X7 receptor-mediated ATP-activated currents. Calcium imaging also showed that TRPV4 agonists induced different degrees of calcium inward currents in the vagal neurons of the chronic cough and the control group, and the calcium inward currents were more significant in the model group. Conclusions: The TRPV4-mediated purinergic signaling pathway was identified to be involved in the development of cough hypersensitivity in guinea pigs with chronic cough; i.e., TRPV4 can lead to the release of airway epithelial ATP, which can stimulate P2X receptors on the cough receptor, and further activate the sensory afferent nerves in the peripheral airway, leading to increased cough sensitivity. Full article

Background/Objectives: Cilnidipine (CIL) is a calcium channel blocker that exhibits low bioavailability (~13%) due to poor aqueous solubility and extensive pre-systemic gut wall metabolism. The current study aimed to enhance the oral bioavailability of CIL by formulation of polymeric spherical agglomerates (CILSAs)-based orodispersible tablets (ODTs). Methods: Eight different batches of CILSAs were prepared by a crystallo-co-agglomeration technique using different proportions of hydrophilic polymers like hydroxy propyl methyl cellulose E50, polyvinyl pyrrolidone K30, or polyethylene glycol (PEG) 6000 as carriers. Fourier transform infrared spectroscopy (FTIR) of CILSAs proved the chemical integrity of CIL in SAs, while scanning electron microscopy revealed the spherical shape of CILSAs. Results: Differential scanning calorimetry and powder X-ray diffraction studies confirmed that CIL was rendered more amorphous in CILSAs. CILSAs displayed good flow behavior, high percentage yield, and high drug loads. The batch F4 composed of PEG 6000 emerged as the optimized batch as it displayed high percentage dissolution efficiency (57.01 ± 0.01%), which was significantly greater (p < 0.001) compared to CIL (26.27 ± 0.06%). The optimized formulation of CILSAs was directly compressed into ODTs that were rendered porous by vacuum drying. The optimized formulation of porous ODTs (T3) displayed low friability (0.28 ± 0.03%), short disintegration time (6.26 ± 0.29 s), and quicker dissolution (94.16 ± 1.41% in 60 min) as compared to marketed tablet Cildipin^® 10 mg (85 ± 2.3%). Conclusions: Thus, porous ODTs of CILSAs can rapidly release the drug, bypass gut metabolism, enhance oral bioavailability, and improve CIL’s therapeutic effectiveness for angina and hypertension. Full article

The RyR1 calcium release channel is a key player in skeletal muscle excitation–contraction coupling. Mutations in the RYR1 gene are associated with congenital myopathies. Recently, a role of RyR1 in myotubes differentiation has been proposed and attributed to its calcium channel function, which nonetheless remains to be clearly demonstrated. In order to clarify RyR1 role in myogenesis, we have developed an in vitro model, the so-called RyR1-Rec myotubes, which are mouse primary myotubes with an inducible decrease in RyR1 protein amount and in RyR1-mediated calcium release. Using this model, we showed that the RyR1 protein decrease was responsible for an increase in both differentiation and fusion, from the RNA level to the morphological level, without affecting the myogenic factors MyoD and MyoG. Although an increase in mTOR pathway was observed in RyR1-Rec myotubes, it did not seem to be responsible for the role of RyR1 in myogenesis. Additionally, even if modulation of intracellular calcium level affected RyR1-Rec myotubes differentiation, we have shown that the role of RyR1 in myogenesis was independent of its calcium channel function. Therefore, our findings indicate that, besides its pivotal role as a calcium channel responsible for muscle contraction, RyR1 fulfills a calcium-independent inhibitor function of myogenesis. Full article