Molecular Determinants of BK Channel Functional Diversity and Functioning.

Large-conductance Ca2+- and voltage-activated K+ (BK) channels play many physiological roles ranging from the maintenance of smooth muscle tone to hearing and neurosecretion. BK channels are tetramers in which the pore-forming α subunit is coded by a single gene (Slowpoke, KCNMA1). In this review, we first highlight the physiological importance of this ubiquitous channel, emphasizing the role that BK channels play in different channelopathies. We next discuss the modular nature of BK channel-forming protein, in which the different modules (the voltage sensor and the Ca2+ binding sites) communicate with the pore gates allosterically. In this regard, we review in detail the allosteric models proposed to explain channel activation and how the models are related to channel structure. Considering their extremely large conductance and unique selectivity to K+, we also offer an account of how these two apparently paradoxical characteristics can be understood consistently in unison, and what we have learned about the conduction system and the activation gates using ions, blockers, and toxins. Attention is paid here to the molecular nature of the voltage sensor and the Ca2+ binding sites that are located in a gating ring of known crystal structure and constituted by four COOH termini. Despite the fact that BK channels are coded by a single gene, diversity is obtained by means of alternative splicing and modulatory ß and γ subunits. We finish this review by describing how the association of the α subunit with ß or with γ subunits can change the BK channel phenotype and pharmacology.

Folic acid in carboxymethylcellulose/polyethylene oxide electrospun nanofibers: preparation, release and stability.

BACKGROUND: Folic acid (FA), a synthetically produced compound analogous to vitamin B9, also referred to as vitamin folate, is an essential compound in human health and faces challenges in stability during food processing. This study explores the incorporation of FA into carboxymethylcellulose (CMC) nanofibers using electrospinning to enhance its stability. RESULTS: In this study, optimization of both electrospinning and solution parameters facilitated the fabrication of nanofibers. Furthermore, incorporating FA into CMC/polyethylene oxide (PEO) nanofibers resulted in thinner fibers, with an average diameter of 88 nm, characterized by a flat shape and smooth surface. Fourier transform infrared spectroscopic analysis demonstrated substantial hydrogen bonding interactions between FA and the polar groups present in CMC. This interaction contributed to an encapsulation efficiency of 94.5%, with a yield exceeding 87%. Thermal analysis highlighted mutual interference between CMC and PEO, with FA enhancing the thermal stability and reducing the melting temperatures and enthalpies of PEO, while also increasing the reaction heats of CMC. The encapsulated FA remained stable in acidic conditions, with only 6% degradation over 30 days, demonstrating the efficacy of CMC/PEO nanofibers in safeguarding FA against acidic environments. Moreover, the nanofibers provided a protective barrier against UV radiation, thereby preserving the stability of FA. CONCLUSION: This study emphasizes the efficacy of CMC/PEO nanofibers as a protective matrix against FA degradation. The findings indicate that this innovative approach could significantly diversify the applications of FA in food fortification, addressing concerns regarding its vulnerability to temperature and hydrolysis reactions during food processing. © 2024 Society of Chemical Industry.

A folding reaction at the C-terminal domain drives temperature sensing in TRPM8 channels.

In mammals, temperature-sensitive TRP channels make membrane conductance of cells extremely temperature dependent, allowing the detection of temperature ranging from noxious cold to noxious heat. We progressively deleted the distal carboxyl terminus domain (CTD) of the cold-activated melastatin receptor channel, TRPM8. We found that the enthalpy change associated with channel gating is proportional to the length of the CTD. Deletion of the last 36 amino acids of the CTD transforms TRPM8 into a reduced temperature-sensitivity channel (Q10 ∼4). Exposing the intracellular domain to a denaturing agent increases the energy required to open the channel indicating that cold drives channel gating by stabilizing the folded state of the CTD. Experiments in the presence of an osmoticant agent suggest that channel gating involves a change in solute-inaccessible volume in the CTD of ∼1,900 Å3 This volume matches the void space inside the coiled coil according to the cryogenic electron microscopy structure of TRPM8. The results indicate that a folding-unfolding reaction of a specialized temperature-sensitive structure is coupled to TRPM8 gating.

Congenital Cytomegalovirus Awareness and Knowledge among Health Professionals and Pregnant Women: An Action towards Prevention.

INTRODUCTION: Cytomegalovirus (CMV) is a major cause of childhood disabilities, and consensus recommendations emphasize the importance of hygienic measures to reduce perinatal infection. Our study aimed to evaluate the level of awareness about CMV among health professionals and pregnant women. METHODS: We submitted a 20-item online survey regarding CMV perinatal infection to all obstetricians and midwives in Catalonia (Spain) and a 7-item lay version of the questionnaire to 700 pregnant women. Levels of knowledge were compared among groups. RESULTS: Of the 1,449 health professionals approached, 338 surveys were answered. 72% of professionals considered CMV a relevant problem. 47% of obstetricians and 28% of midwives (p ≤ 0.001) routinely informed pregnant women, and less than half knew the risk of fetal transmission. We observed significant differences in knowledge between obstetricians and midwives concerning the risks of recurrent infections, risk of transmission, and risk of severe infection (60.7% vs. 45.6%, p = 0.006 and 50.6% vs. 22.5%, p ≤ 0.001); and regarding maternal and neonatal symptoms and newborn sequelae (23% vs. 8.8%, p ≤ 0.001). Of the 700 women approached, we obtained a response rate of 72%. Only 23% had previously heard about CMV, 22% identified transmission routes, and 15% preventive measures. Compared to women without risk factors for CMV infection, women at greater risk had heard more about CMV (mothers of children <3 years: 36% vs. 20%, p < 0.001; occupational exposure: 43% vs. 20%, p ≤ 0.001) and had received more information (mothers of children <3 years: 18% vs. 9.5%, p ≤ 0.001; occupational exposure: 23% vs. 9.3%, p = 0.001). CONCLUSION: Health care professionals have limited knowledge about CMV and may fail to enforce preventive measures. While pregnant women have limited awareness about CMV infection, they recognize the need for information. Health campaigns should be promoted to enhance awareness about this perinatal infection.

Thermally activated TRP channels: molecular sensors for temperature detection.

Temperature sensing is one of the oldest capabilities of living organisms, and is essential for sustaining life, because failure to avoid extreme noxious temperatures can result in tissue damage or death. A subset of members of the transient receptor potential (TRP) ion channel family is finely tuned to detect temperatures ranging from extreme cold to noxious heat, giving rise to thermoTRP channels. Structural and functional experiments have shown that thermoTRP channels are allosteric proteins, containing different domains that sense changes in temperature, among other stimuli, triggering pore opening. Although temperature-dependence is well characterized in thermoTRP channels, the molecular nature of temperature-sensing elements remains unknown. Importantly, thermoTRP channels are involved in pain sensation, related to pathological conditions. Here, we provide an overview of thermoTRP channel activation. We also discuss the structural and functional evidence supporting the existence of an intrinsic temperature sensor in this class of channels, and we explore the basic thermodynamic principles for channel activation. Finally, we give a view of their role in painful pathophysiological conditions.

Molecular mechanism underlying ß1 regulation in voltage- and calcium-activated potassium (BK) channels.

Being activated by depolarizing voltages and increases in cytoplasmic Ca(2+), voltage- and calcium-activated potassium (BK) channels and their modulatory ß-subunits are able to dampen or stop excitatory stimuli in a wide range of cellular types, including both neuronal and nonneuronal tissues. Minimal alterations in BK channel function may contribute to the pathophysiology of several diseases, including hypertension, asthma, cancer, epilepsy, and diabetes. Several gating processes, allosterically coupled to each other, control BK channel activity and are potential targets for regulation by auxiliary ß-subunits that are expressed together with the α (BK)-subunit in almost every tissue type where they are found. By measuring gating currents in BK channels coexpressed with chimeras between ß1 and ß3 or ß2 auxiliary subunits, we were able to identify that the cytoplasmic regions of ß1 are responsible for the modulation of the voltage sensors. In addition, we narrowed down the structural determinants to the N terminus of ß1, which contains two lysine residues (i.e., K3 and K4), which upon substitution virtually abolished the effects of ß1 on charge movement. The mechanism by which K3 and K4 stabilize the voltage sensor is not electrostatic but specific, and the α (BK)-residues involved remain to be identified. This is the first report, to our knowledge, where the regulatory effects of the ß1-subunit have been clearly assigned to a particular segment, with two pivotal amino acids being responsible for this modulation.

[Effectiveness of cigarette-pack warning labels in capturing the attention of smokers and nonsmokersEficácia das tarjas de advertência em maços de cigarro para atrair a atenção de fumantes e não fumantes]. / Eficacia de las etiquetas de advertencia en las cajetillas de cigarrillo.

OBJECTIVE: To determine the ability of cigarette-pack warning labels, of the minimum size required by the World Health Organization, to capture the attention of smokers and nonsmokers. METHODS: In this study, 30 smokers and 30 nonsmokers completed a dot-probe task in which they simultaneously observed images of cigarette packs split in two: the top contained the cigarette brand and the bottom contained the warning label. During the task, brain activity was recorded through two event-related potentials of the negative-polarity type--the potential that occurs in the posterior-contralateral zone approximately 200 ms after a stimulus (N2pc) and the sustained posterior contralateral negativity (SPCN) response--which are indicators of early and sustained attention. RESULTS: In both groups, a greater amplitude of N2pc and SPCN potentials was found for the part of the pack containing the cigarette brand. However, during the dot-probe task, reaction times were shorter for the warning label. CONCLUSIONS: These results suggest that, initially, attention is focused on the cigarette brand, and only then on the warning label. The inability of warning labels to capture early-phase attention decreases their effectiveness, especially in smokers. We suggest that warning labels be enlarged to facilitate increased attention response.

OBJETIVO: Determinar a capacidade das tarjas de advertência com o tamanho mínimo exigido pela Organização Mundial da Saúde (OMS) de atrair a atenção de fumantes e não fumantes. MÉTODOS: A amostra do estudo consistiu de 30 fumantes e 30 não fumantes que foram testados com uma tarefa de sondagem (dot-probe task) em que tiveram de observar simultaneamente imagens de um maço de cigarro dividido ao meio: a parte superior continha a marca do cigarro e a parte inferior continha a tarja de advertência. Durante o teste, foi registrada a atividade cerebral com a análise de potenciais evocados relacionados a eventos do tipo potencial negativo que ocorre em cerca de 200 ms na área posterior contralateral ao estímulo (N2pc) e da ocorrência de negatividade contralateral posterior sustentada (SPCN, em inglês), que são indicadores de atenção mais rápida e sustentada. RESULTADOS: Em ambos os grupos de participantes foi observada maior amplitude dos potenciais N2pc e SPCN na parte do maço que continha a marca. Porém, o tempo de reação na tarefa de sondagem foi menor diante da tarja de advertência. CONCLUSÕES: Os resultados deste estudo sugerem que, ao início, a atenção é dirigida à marca do cigarro e depois à tarja de advertência. A incapacidade da tarja de advertência de atrair a atenção nas primeiras fases diminui sua eficácia, sobretudo entre os fumantes. Recomenda-se aumentar o tamanho das tarjas de advertência para estimular um incremento na resposta de atenção.

[Main immunoregulatory mechanisms that favor breast cancer development]. / Principales mecanismos inmunorreguladores que favorecen el desarrollo del cáncer de mama.

Even after the improvements made in recent years in early diagnosis and treatments, breast cancer is still the most common cancer and the leading cause of cancer death in women around the world. Several attempts to design new alternative therapies like immunotherapy have been evaluated in clinical trials, but they have shown limited efficacy. The failure of immunotherapy may be related to suppressive mechanisms in the tumor environment. Consequently, the development of new immunotherapy based treatment strategies is very important to understand the immunoregulatory mechanisms present in the tumor microenvironment. Some of the immunoregulatory mechanisms described in breast cancer will be discussed in this review.

BAX inhibitor-1 regulates autophagy by controlling the IRE1α branch of the unfolded protein response.

Both autophagy and apoptosis are tightly regulated processes playing a central role in tissue homeostasis. Bax inhibitor 1 (BI-1) is a highly conserved protein with a dual role in apoptosis and endoplasmic reticulum (ER) stress signalling through the regulation of the ER stress sensor inositol requiring kinase 1 α (IRE1α). Here, we describe a novel function of BI-1 in the modulation of autophagy. BI-1-deficient cells presented a faster and stronger induction of autophagy, increasing LC3 flux and autophagosome formation. These effects were associated with enhanced cell survival under nutrient deprivation. Repression of autophagy by BI-1 was dependent on cJun-N terminal kinase (JNK) and IRE1α expression, possibly due to a displacement of TNF-receptor associated factor-2 (TRAF2) from IRE1α. Targeting BI-1 expression in flies altered autophagy fluxes and salivary gland degradation. BI-1 deficiency increased flies survival under fasting conditions. Increased expression of autophagy indicators was observed in the liver and kidney of bi-1-deficient mice. In summary, we identify a novel function of BI-1 in multicellular organisms, and suggest a critical role of BI-1 as a stress integrator that modulates autophagy levels and other interconnected homeostatic processes.

Voltage-dependent BK and Hv1 channels expressed in non-excitable tissues: New therapeutics opportunities as targets in human diseases.

Voltage-gated ion channels are the molecular determinants of cellular excitability. This group of ion channels is one of the most important pharmacological targets in excitable tissues such as nervous system, cardiac and skeletal muscle. Moreover, voltage-gated ion channels are expressed in non-excitable cells, where they mediate key cellular functions through intracellular biochemical mechanisms rather than rapid electrical signaling. This review aims at illustrating the pharmacological impact of these ion channels, highlighting in particular the structural details and physiological functions of two of them - the high conductance voltage- and Ca(2+)-gated K(+) (BK) channels and voltage-gated proton (Hv1) channels- in non-excitable cells. BK channels have been implicated in a variety of physiological processes ranging from regulation of smooth muscle tone to modulation of hormone and neurotransmitter release. Interestingly, BK channels are also involved in modulating K(+) transport in the mammalian kidney and colon epithelium with a potential role in the hyperkalemic phenotype observed in patients with familial hyperkalemic hypertension type 2, and in the pathophysiology of hypertension. In addition, BK channels are responsible for resting and stimulated Ca(2+)-activated K(+) secretion in the distal colon. Hv1 channels have been detected in many cell types, including macrophages, blood cells, lung epithelia, skeletal muscle and microglia. These channels have a central role in the phagocytic system. In macrophages, Hv1 channels participate in the generation of reactive oxygen species in the respiratory burst during the process of phagocytosis.

Large conductance voltage-and calcium-activated K+ (BK) channel in health and disease.

Large Conductance Voltage- and Calcium-activated K+ (BK) channels are transmembrane pore-forming proteins that regulate cell excitability and are also expressed in non-excitable cells. They play a role in regulating vascular tone, neuronal excitability, neurotransmitter release, and muscle contraction. Dysfunction of the BK channel can lead to arterial hypertension, hearing disorders, epilepsy, and ataxia. Here, we provide an overview of BK channel functioning and the implications of its abnormal functioning in various diseases. Understanding the function of BK channels is crucial for comprehending the mechanisms involved in regulating vital physiological processes, both in normal and pathological conditions, controlled by BK. This understanding may lead to the development of therapeutic interventions to address BK channelopathies.

A journey from molecule to physiology and in silico tools for drug discovery targeting the transient receptor potential vanilloid type 1 (TRPV1) channel.

The heat and capsaicin receptor TRPV1 channel is widely expressed in nerve terminals of dorsal root ganglia (DRGs) and trigeminal ganglia innervating the body and face, respectively, as well as in other tissues and organs including central nervous system. The TRPV1 channel is a versatile receptor that detects harmful heat, pain, and various internal and external ligands. Hence, it operates as a polymodal sensory channel. Many pathological conditions including neuroinflammation, cancer, psychiatric disorders, and pathological pain, are linked to the abnormal functioning of the TRPV1 in peripheral tissues. Intense biomedical research is underway to discover compounds that can modulate the channel and provide pain relief. The molecular mechanisms underlying temperature sensing remain largely unknown, although they are closely linked to pain transduction. Prolonged exposure to capsaicin generates analgesia, hence numerous capsaicin analogs have been developed to discover efficient analgesics for pain relief. The emergence of in silico tools offered significant techniques for molecular modeling and machine learning algorithms to indentify druggable sites in the channel and for repositioning of current drugs aimed at TRPV1. Here we recapitulate the physiological and pathophysiological functions of the TRPV1 channel, including structural models obtained through cryo-EM, pharmacological compounds tested on TRPV1, and the in silico tools for drug discovery and repositioning.

Medication-related osteonecrosis of the jaw in cancer patients: Case series and review of the current literature.

Currently, a large proportion of cancer patients are treated with bone modifying agents (BMA). In this regard, the increase in the prescription of these drugs has lead to concerns in the increment of osteonecrosis of the jaws. This article describes four patients with BMA cancer treatments requested dental evaluation at our institution due to pain and swelling of the mandibular bone after tooth extraction, tooth loss, or unknown risk factor. Oral and radiographic evaluation reveals Medication-related osteonecrosis of the jaw (MRONJ) at different clinical stages according to the American Association of Oral and Maxillofacial Surgeons (AAOMS) classification. Some patients underwent abscess drainage, oral cleaning and antibiotic therapy with complete recovery. Follow-up showed treatment success in all patients. That is why we emphasize the importance of early establishment of appropriate treatment and emphasize the avoidance of dental procedures during BMA therapy.

En la actualidad, una gran cantidad de pacientes con cáncer son tratados con agentes modificadores óseos (AMO). En relación con esto, el aumento en la prescripción de estos fármacos ha generado preocupación por el incremento en la osteonecrosis de los maxilares. Este artículo describe cuatro casos de pacientes con cáncer, tratados con AMO, que acuden a nuestra institución debido a que padecen dolor e inflamación de la mandíbula, después de la extracción dental, así como pérdida de dientes con un factor de riesgo desconocido. La evaluación clínica y radiográfica evidenció osteonecrosis de los maxilares en diferentes etapas clínicas, según la clasificación de la Asociación Estadounidense de Cirujanos Orales y Maxilofaciales (AAOMS). Algunos de los pacientes fueron sometidos a drenaje de abscesos, limpieza bucal y antibioticoterapia con recuperación completa. El seguimiento clínico fue exitoso en todos los pacientes. Es por eso que hacemos énfasis en la importancia de establecer un tratamiento apropiado y evitar procedimientos dentales durante la terapia con AMO.

Young Argentine Children's Attributions about Hypothetical Socially Withdrawn Peers.

This study assessed young children's attributions about different subtypes of hypothetical socially withdrawn peers. Participants were N = 114 (56% boys, Mage= 60.53 months, SD = 7.58) children attending urban public kindergartens in Mendoza, Argentina. Children were presented with vignettes describing hypothetical shy, unsociable, aggressive, and socially competent peers, and were asked a series of questions to assess their attributions toward each behavior. The results indicated that Argentine children characterized hypothetical unsociable peers as behaving with greater intentionality and lesser social motivations than shy children. No differences were found between the unsociable and shy hypothetical peers regarding the attributions of sympathy, affiliative preference, negative impact and social standing in the class. These findings provide some of the first evidence about Argentine children understanding of social withdrawal. Results are discussed in terms of the possible cultural meanings and implications of these behaviors.

Correction: Prion Protein Misfolding Affects Calcium Homeostasis and Sensitizes Cells to Endoplasmic Reticulum Stress.

[This corrects the article DOI: 10.1371/journal.pone.0015658.].

Bisphosphonates Targeting Ion Channels and Musculoskeletal Effects.

Bisphosphonates (BPs) are the most used bone-specific anti-resorptive agents, often chosen as first-line therapy in several bone diseases characterized by an imbalance between osteoblast-mediated bone production and osteoclast-mediated bone resorption. BPs target the farnesyl pyrophosphate synthase (FPPS) in osteoclasts, reducing bone resorption. Lately, there has been an increasing interest in BPs direct pro-survival/pro-mineralizing properties in osteoblasts and their pain-relieving effects. Even so, molecular targets involved in these effects appear now largely elusive. Ion channels are emerging players in bone homeostasis. Nevertheless, the effects of BPs on these proteins have been poorly described. Here we reviewed the actions of BPs on ion channels in musculoskeletal cells. In particular, the TRPV1 channel is essential for osteoblastogenesis. Since it is involved in bone pain sensation, TRPV1 is a possible alternative target of BPs. Ion channels are emerging targets and anti-target for bisphosphonates. Zoledronic acid can be the first selective musculoskeletal and vascular KATP channel blocker targeting with high affinity the inward rectifier channels Kir6.1-SUR2B and Kir6.2-SUR2A. The action of this drug against the overactive mutants of KCNJ9-ABCC9 genes observed in the Cantu' Syndrome (CS) may improve the appropriate prescription in those CS patients affected by musculoskeletal disorders such as bone fracture and bone frailty.

Fetal Liver Volume Assessment Using Magnetic Resonance Imaging in Fetuses With Cytomegalovirus Infection†.

Objective: To assess fetal liver volume (FLV) by magnetic resonance imaging (MRI) in cytomegalovirus (CMV)-infected fetuses compared to a group of healthy fetuses. Method: Most infected cases were diagnosed by the evidence of ultrasound abnormalities during routine scans and in some after maternal CMV screening. CMV-infected fetuses were considered severely or mildly affected according to prenatal brain lesions identified by ultrasound (US)/MRI. We assessed FLV, the FLV to abdominal circumference (AC) ratio (FLV/AC-ratio), and the FLV to fetal body volume (FBV) ratio (FLV/FBV-ratio). As controls, we included 33 healthy fetuses. Hepatomegaly was evaluated post-mortem in 11 cases of congenital CMV infection. Parametric trend and intraclass correlation analyses were performed. Results: There were no significant differences in FLV between infected (n = 32) and healthy fetuses. On correcting the FLV for AC and FBV, we observed a significantly higher FLV in CMV-infected fetuses. There were no significant differences in the FLV, or the FLV/AC or FLV/FBV-ratios according to the severity of brain abnormalities. There was excellent concordance between the fetal liver weight estimated by MRI and liver weight obtained post-mortem. Hepatomegaly was not detected in any CMV-infected fetus. Conclusion: In CMV-infected fetuses, FLV corrected for AC and FBV was higher compared to healthy controls, indicating relative hepatomegaly. These parameters could potentially be used as surrogate markers of liver enlargement.

Physiological and affective responses to emoji faces: Effects on facial muscle activity, skin conductance, heart rate, and self-reported affect.

The objective of the present study was to evaluate emotional responses to emoji faces through physiological and self-report measures, and evaluate possible differences between men and women. One hundred participants (50 women) observed pictures of happy, neutral, and angry emoji faces, while activity of the zygomatic and corrugator muscles, skin conductance, and heart rate were measured. Self-report measures of emotional experience were also recorded. The results showed an increase in zygomatic muscle activity toward happy emoji faces. An increasing trend in corrugator muscle activity toward angry emoji faces was observed; however, this trend was only marginally significant. Happy emoji faces generated an increase in the skin conductance response. The emotional experience of the participants was also consistent with the emotions that were expressed by the emoji faces. No differences were found between sexes. Overall, the results suggest that emoji faces can especially induce pleasant affective states.