Single-crystal growth, structure and thermal transport properties of the metallic antiferromagnet Zintl-phase β-EuIn2As2

Zintl-phase materials have attracted significant research interest owing to the interplay of magnetism and strong spin-orbit coupling, providing a prominent material platform for axion electrodynamics. Here, we report the single-crystal growth, structure, magnetic and electrical/thermal transport properties of the antiferromagnet layer Zintl-phase compound β-EuIn2As2. Importantly, the new layered structure of β-EuIn2As2, in rhombohedral (R3̄m) symmetry, contains triangular layers of Eu2+ ions. The in-plane resistivity ρ(H, T) measurements reveal metal behavior with an antiferromagnetic (AFM) transition (TN ∼ 23.5 K), which is consistent with the heat capacity Cp(H, T) and magnetic susceptibility χ(H, T) measurements. Negative MR was observed in the temperature range from 2 K to 20 K with a maximum MR ratio of 0.06. Unique 4f7J = S = 7/2 Eu2+ spins were supposed magnetically order along the c-axis. The Seebeck coefficient shows a maximum thermopower |Smax| of about 40 μV K-1. The kink around 23 K in the Seebeck coefficient originates from the effect of the antiferromagnetic phase on the electron band structure, while the pronounced thermal conductivity peak at around 10 K is attributed to the phonon-phonon Umklapp scattering. The results suggest that the Eu2+ spin arrangement plays an important role in the magnetic, electrical, and thermal transport properties in β-EuIn2As2, which might be helpful for future potential technical applications.

Urinary metabolite biomarkers of pregnancy complications associated with maternal exposure to particulate matter

Particulate matter 2.5 (PM2.5) is associated with reproductive health and adverse pregnancy outcomes. However, studies evaluating biological markers of PM2.5 are lacking, and identifying biomarkers for estimating prenatal exposure to prevent pregnancy complications is essential. Therefore, we aimed to explore urine metabolites that are easy to measure as biomarkers of exposure. In this matched case-control study based on the PM2.5 exposure, 30 high PM2.5 group (>15 μg/m3) and 30 low PM2.5 group (<15 μg/m3) were selected from air pollution on pregnancy outcome (APPO) cohort study. We used a time-weighted average model to estimate individual PM exposure, which used indoor PM2.5 and outdoor PM2.5 concentrations by atmospheric measurement network based on residential addresses. Clinical characteristics and urine samples were collected from participants during the second trimester of pregnancy. Urine metabolites were quantitatively measured using gas chromatography-mass spectrometry following multistep chemical derivatization. Statistical analyses were conducted using SPSS version 21 and MetaboAnalyst 5.0. Small for gestational age and gestational diabetes (GDM) were significantly increased in the high PM2.5 group, respectively (P = 0.042, and 0.022). Fifteen metabolites showed significant differences between the two groups (P < 0.05). Subsequent pathway enrichment revealed that four pathways, including pentose and glucuronate interconversion with three pentose sugars (ribose, arabinose, and xylose; P < 0.05). The concentration of ribose increased preterm births (PTB) and GDM (P = 0.044 and 0.049, respectively), and the arabinose concentration showed a tendency to increase in PTB (P = 0.044). Therefore, we identified urinary pentose metabolites as biomarkers of PM2.5 and confirmed the possibility of their relationship with pregnancy complications.

Proinsulin C-peptide inhibits high glucose-induced migration and invasion of ovarian cancer cells

Proinsulin C-peptide, a biologically active polypeptide released from pancreatic β-cells, is known to prevent hyperglycemia-induced microvascular leakage; however, the role of C-peptide in migration and invasion of cancer cells is unknown. Here, we investigated high glucose-induced migration and invasion of ovarian cancer cells and the inhibitory effects of human C-peptide on metastatic cellular responses. In SKOV3 human ovarian cancer cells, high glucose conditions activated a vicious cycle of reactive oxygen species (ROS) generation and transglutaminase 2 (TGase2) activation through elevation of intracellular Ca2+ levels. TGase2 played a critical role in high glucose-induced ovarian cancer cell migration and invasion through β-catenin disassembly. Human C-peptide inhibited high glucose-induced disassembly of adherens junctions and ovarian cancer cell migration and invasion through inhibition of ROS generation and TGase2 activation. The preventive effect of C-peptide on high glucose-induced ovarian cancer cell migration and invasion was further demonstrated in ID8 murine ovarian cancer cells. Our findings suggest that high glucose conditions induce the migration and invasion of ovarian cancer cells, and human C-peptide inhibits these metastatic responses by preventing ROS generation, TGase2 activation, and subsequent disassembly of adherens junctions.

Ultrasonographic assessment of abnormal fetal growth related to uteroplacental-fetal biometrics and Doppler (U-AID) indices: Protocol for multicenter retrospective cohort study trial

Fetal growth restriction (FGR) is one of the leading causes of perinatal morbidity and mortality. Many studies have reported an association between FGR and fetal Doppler indices focusing on umbilical artery (UA), middle cerebral artery (MCA), and ductus venosus (DV). The uteroplacental-fetal circulation which affects the fetal growth consists of not only UA, MCA, and DV, but also umbilical vein (UV), placenta and uterus itself. Nevertheless, there is a paucity of large-scale cohort studies that have assessed the association between UV, uterine wall, and placental thickness with perinatal outcomes in FGR, in conjunction with all components of the uteroplacental-fetal circulation. Therefore, this multicenter study will evaluate the association among UV absolute flow, placental thickness, and uterine wall thickness and adverse perinatal outcome in FGR fetuses. This multicenter retrospective cohort study will include singleton pregnant women who undergo at least one routine fetal ultrasound scan during routine antepartum care. Pregnant women with fetuses having structural or chromosomal abnormalities will be excluded. The U-AID indices (UtA, UA, MCA, and UV flow, placental and uterine wall thickness, and estimated fetal body weight) will be measured during each trimester of pregnancy. The study population will be divided into two groups: (1) FGR group (pregnant women with FGR fetuses) and (2) control group (those with normal growth fetus). We will assess the association between U-AID indices and adverse perinatal outcomes in the FGR group and the difference in U-AID indices between the two groups.

Maternal PM2.5 exposure is associated with preterm birth and gestational diabetes mellitus, and mitochondrial OXPHOS dysfunction in cord blood

Maternal exposure to fine particulate matter (PM2.5) is associated with adverse pregnancy and neonatal health outcomes. To explore the mechanism, we performed mRNA sequencing of neonatal cord blood. From an ongoing prospective cohort, Air Pollution on Pregnancy Outcome (APPO) study, 454 pregnant women from six centers between January 2021 and June 2022 were recruited. Individual PM2.5 exposure was calculated using a time-weighted average model. In the APPO study, age-matched cord blood samples from the High PM2.5 (˃15 ug/m3; n = 10) and Low PM2.5 (≤ 15 ug/m3; n = 30) groups were randomly selected for mRNA sequencing. After selecting genes with differential expression in the two groups (p-value < 0.05 and log2 fold change > 1.5), pathway enrichment analysis was performed, and the mitochondrial pathway was analyzed using MitoCarta3.0. The risk of preterm birth (PTB) increased with every 5 µg/m3 increase of PM2.5 in the second trimester (odds ratio 1.391, p = 0.019) after adjusting for confounding variables. The risk of gestational diabetes mellitus (GDM) increased in the second (odds ratio 1.238, p = 0.041) and third trimester (odds ratio 1.290, p = 0.029), and entire pregnancy (odds ratio 1.295, p = 0.029). The mRNA-sequencing of cord blood showed that genes related to mitochondrial activity (FAM210B, KRT1, FOXO4, TRIM58, and FBXO7) and PTB-related genes (ADIPOR1, YBX1, OPTN, NFkB1, HBG2) were upregulated in the High PM2.5 group. In addition, exposure to high PM2.5 affected mitochondrial oxidative phosphorylation (OXPHOS) and proteins in the electron transport chain, a subunit of OXPHOS. These results suggest that exposure to high PM2.5 during pregnancy may increase the risk of PTB and GDM, and dysregulate PTB-related genes. Alterations in mitochondrial OXPHOS by high PM2.5 exposure may occur not only in preterm infants but also in normal newborns. Further studies with larger sample sizes are required.

Correction: Park et al. Effect of Particulate Matter 2.5 on Fetal Growth in Male and Preterm Infants through Oxidative Stress. Antioxidants 2023, 12, 1916

In the original publication [...].

Personal exposure of PM2.5 and metabolic syndrome markers of pregnant women in South Korea: APPO study

We examined the association between exposure to PM2.5, focused on individual exposure level, and metabolic dysfunction during pregnancy. APPO study (Air Pollution on Pregnancy Outcome) was a prospective, multicenter, observational cohort study conducted from January 2021 to March 2023. Individual PM2.5 concentrations were calculated using a time-weighted average model. Metabolic dysfunction during pregnancy was assessed based on a modified definition of metabolic syndrome and its components, accounting for pregnancy-specific criteria. Exposure to PM2.5 during pregnancy was associated with worsened metabolic parameters especially glucose metabolism. In comparison to participants exposed to the low PM2.5 group, those exposed to high PM2.5 levels exhibited increased odds of gestational diabetes mellitus (GDM) after adjusting for confounding variables in different adjusted models. Specifically, in model 1, the adjusted odds ratio (aOR) was 3.117 with a 95% confidence interval (CI) of 1.234-7.870; in model 2, the aOR was 3.855 with a 95% CI of 1.255-11.844; in model 3, the aOR was 3.404 with a 95% CI of 1.206-9.607; and in model 4, the aOR was 2.741 with a 95% CI of 0.712-10.547. Exposure to higher levels of PM2.5 during pregnancy was associated with a tendency to worsen metabolic dysfunction markers specifically in glucose homeostasis. Further research is needed to investigate the mechanisms underlying the effects of ambient PM2.5 on metabolic dysfunction during pregnancy.

Inhibition of voltage-dependent K+ currents of rabbit coronary arterial smooth muscle cells by the atypical antipsychotic paliperidone

Paliperidone, an atypical antipsychotic, is widely used to treat schizophrenia. In this study, we explored whether paliperidone inhibited the voltage-dependent K+ (Kv) channels of rabbit coronary arterial smooth muscle cells. Paliperidone reduced Kv channel activity in a concentration-dependent manner with a half-maximal inhibitory concentration (IC50 ) of 16.58 ± 3.03 μM and a Hill coefficient of 0.60 ± 0.04. It did not significantly shift the steady-state activation or inactivation curves, suggesting that the drug did not affect the gating properties of Kv channels. In the presence of paliperidone, the application of 20 repetitive depolarizing pulses at 1 and 2 Hz gradually increased the inhibition of the Kv current. Further, the recovery time constant after Kv channel inactivation was increased by paliperidone, indicating that it inhibited the Kv channel in a use (state)-dependent manner. Its inhibitory effects were reduced by pretreatment with a Kv1.5 subtype inhibitor. However, pretreatment with a Kv2.1 or Kv7 inhibitor did not reduce its inhibitory effect. We conclude that paliperidone inhibits Kv channels (mainly Kv1.5 subtype channels) in a concentration- and use (state)-dependent manner without changing channel gating.

Effect of Particulate Matter 2.5 on Fetal Growth in Male and Preterm Infants through Oxidative Stress

Particulate matter 2.5 (PM2.5) levels are associated with adverse pregnancy outcomes. In this retrospective cohort study, we examined whether the concentration of indoor PM2.5 affected pregnancy outcomes. Additionally, we evaluated biomarkers of pregnancy-related complications caused by fine dust. We collected clinical information and data based on residential addresses from the Air Korea database to assess PM2.5 exposure levels. As a multicenter prospective cohort study, we measured the indoor PM2.5 concentration and inflammatory and oxidative stress markers. The PM2.5 concentration of the low-birth-weight (LBW) delivery group was 27.21 μg/m3, which was significantly higher than that of the normal-birth-weight (NBW) group (26.23 μg/m3) (p = 0.02). When the newborns were divided by sex, the PM2.5 concentration of the LBW group was 27.89 μg/m3 in male infants, which was significantly higher than that of the NBW group (26.26 μg/m3) (p = 0.01). In the prospective study, 8-hydroxy-2-deoxyguanosine significantly increased in the high-concentration group (113.55 ng/mL, compared with 92.20 ng/mL in the low-concentration group); in the high-concentration group, the rates of preterm birth (PTB) and small size for gestational age significantly increased (p < 0.01, p = 0.01). This study showed an association between PM2.5, oxidative stress, and fetal growth, with the PTB group being more vulnerable.

RAS‑stimulated release of exosomal miR‑494‑3p promotes the osteolytic bone metastasis of breast cancer cells

RAS activation is a key determinant of breast cancer progression and metastasis. However, the role of the interaction among exosomes, RAS and microRNAs (miRNAs/miRs) in the osteolytic bone metastasis of breast cancer remains unclear. Therefore, the present study aimed to examine the role of activated RAS (KRAS, HRAS and NRAS) in the release of exosome‑mediated osteoclastogenic miRNAs and to elucidate their functional role in bone microenvironment remodeling in vitro and in vivo. Exosomes derived from RAS‑activated breast cancer cells promoted RANKL‑induced osteoclastogenesis; however, RAS inhibition abolished this effect. miR‑494‑3p, miR‑4508 and miR‑6869‑5p were identified as osteoclastogenic miRNAs in the exosomes secreted by RAS‑activated breast cancer cells. The levels of these osteoclastogenic miRNAs in the sera of patients with human epidermal growth factor receptor 2‑positive luminal breast cancer were significantly higher than those in the sera of patients with triple‑negative breast cancer. miR‑494‑3p exhibited both osteoclastogenic and anti‑osteoblastogenic activity. Treatment with a miR‑494‑3p inhibitor abolished the exosome‑mediated increase in RANKL‑induced osteoclastogenesis. Treatment with a miR‑494‑3p mimic enhanced RANKL‑induced osteoclast formation; however, treatment with its inhibitor suppressed this effect by targeting leucine‑rich repeat‑containing G‑protein coupled receptor 4 in osteoclast precursors. Furthermore, miR‑494‑3p inhibited bone morphogenetic protein 2‑induced osteoblast formation by targeting semaphorin 3A. In a mouse model, exosomes derived from breast cancer cells promoted osteolytic bone lesions; however, treatment with a miR‑494‑3p inhibitor significantly suppressed this effect. On the whole, the present study provides a novel mechanism, demonstrating that the RAS activation of breast cancer cells induces osteolytic bone metastasis by stimulating the exosome‑mediated transfer of osteoclastogenic miRNAs, including miR‑494‑3p to bone cells.

The introduction to air pollution on pregnancy outcome (APPO) study: a multicenter cohort study

The air pollution on pregnancy outcome, (APPO) study is a prospective hospital-based cohort study designed to investigate the maternal and fetal effects of particulate matter with an aerodynamic diameter <10 μm (PM10) and particulate matter with an aerodynamic diameter below 10 μm <2.5 μm (PM2.5) exposure. Specifically, approximately 1,200 pregnant women will be recruited for 3 years to collect data on exposure to fine dust, and the methods for measuring exposure to fine particles for each pregnant woman and estimating output will be established. This study aims to analyze the relationship between particulate matter and adverse pregnancy outcomes, identify related biomarkers, and develop management guidelines. We recruited early pregnant women without underlying diseases and collected biological samples using 5 mL of maternal venous blood and 15 mL of urine in each trimester of pregnancy; in addition, 5 mL of umbilical cord blood and 2×2×2 cm of placental tissue were collected after delivery. By applying PM10 and PM2.5 and time-activity patterns from the time-weighted average model, the individual predicted exposure to air pollution for the pregnant women was obtained. The APPO study can identify the degree of exposure to air pollution in pregnant women and use it as basic data for estimating individual exposure to particulate matter. The results of this APPO study will facilitate the development of health management strategies for pregnant women against air pollution.

Heterogeneity among countries in primary cardiovascular prevention guidelines: missed opportunities for adherence and improved outcomes

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Bayer AG

Background

· Specialty-driven guidelines identify risk factors for cardiovascular (CV) events that may potentially be modified by lifestyle or pharmacotherapy.

Purpose

· Worldwide, the control of modifiable risk factors in people at high cardiovascular disease (CVD) risk remains poor. Our hypothesis is that differences in multiple, specialty-driven guidelines do not help, and may hinder, the accurate assessment of CV risk factors and their appropriate management in the individual patient that has multiple risk factors or comorbidities.

Methods

· We conducted a review of the most recent guidelines for CVD prevention, diabetes, hypertension, dyslipidaemia and chronic kidney disease used in Europe, Italy, the USA, China and South Korea to establish the commonalities and differences between risk factor targets, risk modifiers and treatment approaches.

Results

· The use of low dose aspirin in patients at high risk of CVD varies between regions, and between those with and without type 2 diabetes (T2D). In addition, the use of concomitant proton pump inhibitor (PPI) treatment, that may reduce the gastrointestinal bleeding risk and therefore allow more people to be included for low dose aspirin treatment consideration, is variable (see table).

· There are also differences in the definitions of risk stratification, targets for major risk factors and the use of coronary artery calcium score (CAC) to identify high-risk, asymptomatic patients.

· The LDL-C targets for patients with T2D at high CV risk vary from &lt;1.8 mmol/L (&lt;70 mg/dL)1,2,10 to &lt;2.6 mmol/L (&lt;100mg/dL);9 and those for patients with T2D at very high CV risk vary from &lt;1.4 mmol/L (&lt;55 mg/dL)1,2 to &lt;1.8 mmol/L (&lt;70 mg/dL).9

· Although CAC score is identified as a risk modifier in most guidelines, its use to guide treatment decisions in patients with ≥7.5% to &lt;20% 10-year ASCVD risk is recommended in only two guidelines.4,6

Conclusion(s)

· We suggest that physicians cannot synthesise specialty-based recommendations for a single patient with multiple comorbidities within a limited consultation time, and that this may be a major factor in the lack of progress in managing CV risk factors.

· A more unified, consistent and global approach to primary prevention of CV disease across specialties may lead to greater guideline adherence, greater patient understanding and acceptance of therapy, and improved outcomes.

Downregulation of large-conductance Ca2+-activated K+ channels in human umbilical arterial smooth muscle cells in gestational diabetes mellitus

AIMS

We investigated the changes in large-conductance Ca²⁺-activated K⁺ (BK_Ca) channels from human umbilical arterial smooth muscle cells experiencing gestational diabetes mellitus (GDM).

MAIN METHODS

Whole-cell patch-clamp technique, arterial tone measurement, RT-PCR, Quantitative real-time PCR, western blot were performed in human umbilical arterial smooth muscle cells.

KEY FINDINGS

Whole-cell BK_Ca current density was decreased in the GDM group compared with the normal group. The vasorelaxant effects of the synthetic BK_Ca channel activator NS-1619 (10 μM) were impaired in the GDM group compared with the normal group. Reverse-transcription polymerase chain reaction (RT-PCR), real-time RT-PCR, and western blot analyses suggested that the mRNA, total RNA, and protein expression levels of the BK_Ca channel were decreased in the GDM group relative to the normal group. In addition, the expression levels of protein kinase A and protein kinase G, which regulate BK_Ca channel activity, remained unchanged between the groups. Applying the BK_Ca channel inhibitor paxilline (10 μM) induced vasoconstriction and membrane depolarization of isolated umbilical arteries in the normal group but showed less of an effect on umbilical arteries in the GDM group.

SIGNIFICANCE

Our results demonstrate for the first time impaired BK_Ca current and BK_Ca channel-induced vasorelaxation activities that were not caused by impaired BK_Ca channel-regulated protein kinases, but by decreased expression of the BK_Ca channels, in the umbilical arteries of GDM patients.

Suppression of voltage-gated K+ channels by darifenacin in coronary arterial smooth muscle cells

Darifenacin, an anticholinergic agent, has been used to treat overactive bladder syndrome. Despite its extensive clinical use, there is little information about the effect of darifenacin on vascular ion channels, specifically K⁺ channels. This study aimed to investigate the effect of the anti-muscarinic drug darifenacin on voltage-gated K⁺ (Kv) channels, vascular contractility, and coronary blood flow in rabbit coronary arteries. We used the whole-cell patch-clamp technique to evaluate the effect of darifenacin on Kv channels. Darifenacin inhibited the Kv current in a concentration-dependent manner. Applying 1 μM darifenacin shifted the activation and inactivation curves toward a more positive and negative potential, respectively. Darifenacin slowed the time constants of recovery from inactivation. Furthermore, blockade of the Kv current with darifenacin was increased gradually by applying a train of pulses, indicating that darifenacin inhibited Kv currents in a use- (state)-dependent manner. The darifenacin-mediated inhibition of Kv currents was associated with the Kv1.5 subtype, not the Kv2.1 or Kv7 subtype. Applying another anti-muscarinic drug atropine or ipratropium did not affect the Kv current or change the inhibitory effect of darifenacin. Isometric organ bath experiments using isolated coronary arteries were applied to evaluate whether darifenacin-induced inhibition of the Kv channel causes vasocontraction. Darifenacin substantially induced vasocontraction. Furthermore, darifenacin caused membrane depolarization and decreased coronary blood flow. From these results, we concluded that darifenacin inhibits the Kv currents in concentration- and use- (state)-dependent manners. Inhibition of the Kv current with darifenacin occurred by shifting the steady-state activation and inactivation curves regardless of its anti-muscarinic effect.

Dipeptidyl peptidase-4 inhibitor sitagliptin induces vasorelaxation via the activation of Kv channels and PKA

The present study investigated the vasorelaxant effects of sitagliptin, which is a dipeptidyl peptidase-4 (DPP-4) inhibitor in aortic rings pre-contracted with phenylephrine (Phe). Sitagliptin induced vasorelaxation in a concentration-dependent manner but the inhibition of voltage-dependent K⁺ (Kv) channels by pretreatment with 4-aminopyridine (4-AP) effectively reduced this effect. By contrast, the inhibition of inward rectifier K⁺ (Kir) channels by pretreatment with barium (Ba²⁺), large-conductance calcium (Ca²⁺)-activated K⁺ (BK_Ca) channels with paxilline, and adenosine triphosphate (ATP)-sensitive K⁺ (K_ATP) channels with glibenclamide did not change this effect. Although the application of SQ 22536, which is an adenylyl cyclase inhibitor, also did not change this effect, treatment with KT 5720, a protein kinase A (PKA) inhibitor, effectively reduced the vasorelaxant effects of sitagliptin. ODQ, which is a guanylyl cyclase inhibitor, and KT 5823, a protein kinase G (PKG) inhibitor, did not impact the effect. Furthermore, neither the inhibition of Ca²⁺ channels by pretreatment with nifedipine nor the inhibition of sarcoplasmic/endoplasmic reticulum Ca²⁺-ATPase (SERCA) pumps by pretreatment with thapsigargin changed the effect. Similarly, the effects of sitagliptin were not altered by eliminating the endothelium, by pretreatment with a nitric oxide (NO) synthase inhibitor (L-NAME), or by inhibition of small- and intermediate-conductance Ca²⁺-activated K⁺ channels (SK_Ca and IK_Ca) using apamin and TRAM-34. Taken together, these results suggest that sitagliptin induces vasorelaxation by inhibiting both membrane potential (Em)-dependent and -independent vasoconstriction and activating PKA and Kv channels independently of PKG signaling pathways, other K⁺ channels, SERCA pumps, and the endothelium.

Identification and characterization of Pv50, a novel Plasmodium vivax merozoite surface protein

Background

Plasmodium vivax contains approximately 5400 coding genes, more than 40% of which code for hypothetical proteins that have not been functionally characterized. In a previous preliminary screening using pooled serum samples, numerous hypothetical proteins were selected from among those that were highly transcribed in the schizont-stage of parasites, and highly antigenic P. vivax candidates including hypothetical proteins were identified. However, their immunological and functional activities in P. vivax remain unclear. From these candidates, we investigated a P. vivax 50-kDa protein (Pv50, PVX_087140) containing a highly conserved signal peptide that shows high transcription levels in blood-stage parasites.

Results

Recombinant Pv50 was expressed in a cell-free expression system and used for IgG prevalence analysis of patients with vivax malaria and healthy individuals. Immune responses were analyzed in immunized mice and mouse antibodies were used to detect the subcellular localization of the protein in blood-stage parasites by immunofluorescence assay. A protein array method was used to evaluate protein-protein interactions to predict protein functional activities during the invasion of parasites into erythrocytes. Recombinant Pv50 showed IgG prevalence in patient samples with a sensitivity of 42.9% and specificity of 93.8% compared to that in healthy individuals. The non-cytophilic antibodies IgG1 and IgG3 were the major components involved in the antibody response in Pv50-immunized mice. Pv50 localized on the surface of merozoites and a specific interaction between Pv50 and PvMSP1 was detected, suggesting that Pv50-PvMSP1 forms a heterodimeric complex in P. vivax.

Conclusions

Increased immune responses caused by native P. vivax parasites were detected, confirming its immunogenic effects. This study provides a method for detecting new malaria antigens, and Pv50 may be a vivax malaria vaccine candidate with PvMSP1.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3434-7) contains supplementary material, which is available to authorized users.

The anti-diabetic drug dapagliflozin induces vasodilation via activation of PKG and Kv channels

AIM

Considering the clinical efficacy of dapagliflozin in patients with type 2 DM and the pathophysiological relevance of Kv channels for vascular reactivity. We investigate the vasodilatory effect of dapagliflozin and related mechanisms using phenylephrine (Phe)-induced contracted aortic rings.

MATERIAL AND METHODS

Arterial tone measurement was performed in aortic smooth muscle.

KEY FINDINGS

Application of dapagliflozin induced vasodilation in a concentration-dependent manner. Pre-treatment with the BK_Ca channel inhibitor paxilline, the K_ATP channel inhibitor glibenclamide, and the Kir channel inhibitor Ba²⁺ did not change dapagliflozin-induced vasodilation. However, application of the Kv channels inhibitor 4-AP effectively inhibited dapagliflozin-induced vasodilation. Application of the Ca²⁺ channel inhibitor nifedipine and the sarcoplasmic/endoplasmic reticulum Ca²⁺-ATPase (SERCA) pump inhibitor thapsigargin did not alter the vasodilatory effect of dapagliflozin. Moreover, the adenylyl cyclase inhibitor SQ 22536 and the protein kinase A (PKA) inhibitor KT 5720 had no effect on dapagliflozin-induced vasodilation. Although guanylyl cyclase inhibitors, NS 2028 and ODQ, did not reduce the vasodilatory effect of dapagliflozin, the protein kinase G (PKG) inhibitor KT 5823 effectively inhibited dapagliflozin-induced vasodilation. The vasodilatory effect of dapagliflozin was not affected by elimination of the endothelium. Furthermore, pretreatment with the nitric oxide synthase inhibitor L-NAME or the small-conductance Ca²⁺-activated K (SKCa) channel inhibitor apamin did not change the vasodilatory effect of dapagliflozin.

SIGNIFICANCE

We concluded that dapagliflozin induced vasodilation via the activation of Kv channels and PKG, and was independent of other K⁺ channels, Ca²⁺ channels, intracellular Ca²⁺, and the endothelium.

The vasorelaxant effect of antidiabetic drug nateglinide via activation of voltage-dependent K+ channels in aortic smooth muscle

AIMS

We investigated the vasorelaxant effect of nateglinide and its related mechanisms using phenylephrine (Phe)-induced precontracted aortic rings.

METHODS

Arterial tone measurement was performed in aortic smooth muscle.

RESULTS

The application of nateglinide induced vasorelaxation in a concentration-dependent manner. Pretreatment with the large-conductance Ca²⁺ -activated K⁺ (BK_Ca ) channel inhibitor paxilline, the inwardly rectifying K⁺ (Kir) channel inhibitor Ba²⁺ , and ATP-sensitive K⁺ (K_ATP ) channel inhibitor glibenclamide did not affect the vasorelaxant effect of nateglinide. However, pretreatment with the voltage-dependent K⁺ (Kv) channel inhibitor 4-aminopyridine (4-AP) effectively reduced the vasorelaxant effect of nateglinide. Pretreatment with the Ca²⁺ inhibitor nifedipine and the sarcoplasmic/endoplasmic reticulum Ca²⁺ -ATPase inhibitor thapsigargin did not change the vasorelaxant effect of nateglinide. Additionally, the vasorelaxant effect of nateglinide was not altered in the presence of an adenylyl cyclase, a protein kinase A, a guanylyl cyclase, or a protein kinase G inhibitor. The vasorelaxant effect of nateglinide was not affected by the elimination of the endothelium. In addition, pretreatment with a nitric oxide synthase inhibitor, L-NAME, and a small-conductance Ca²⁺ -activated K⁺ (SK_Ca ) channel inhibitor, apamin, did not change the vasorelaxant effect of nateglinide.

CONCLUSION

Nateglinide induced vasorelaxation via the activation of the Kv channel independent of other K⁺ channels, Ca²⁺ channels, intracellular Ca²⁺ ([Ca²⁺ ]_i ), and the endothelium.

Alterations of voltage-dependent K(+) channels in the mesenteric artery during the early and chronic phases of diabetes

This study investigated the alteration of voltage-dependent K(+) (Kv) channels in mesenteric arterial smooth muscle cells from control (Long-Evans Tokushima Otsuka [LETO]) and diabetic (Otsuka Long-Evans Tokushima Fatty [OLETF]) rats during the early and chronic phases of diabetes. We demonstrated alterations in the mesenteric Kv channels during the early and chronic phase of diabetes using the patch-clamp technique, the arterial tone measurement system, and RT-PCR in Long-Evans Tokushima (LETO; for control) and Otsuka Long-Evans Tokushima Fatty (OLETF; for diabetes) type 2 diabetic model rats. In the early phase of diabetes, the amplitude of mesenteric Kv currents induced by depolarizing pulses was greater in OLETF rats than in LETO rats. The contractile response of the mesenteric artery induced by the Kv inhibitor, 4-aminopyridine (4-AP), was also greater in OLETF rats. The expression of most Kv subtypes- including Kv1.1, Kv1.2, Kv1.4, Kv1.5, Kv1.6, Kv2.1, Kv3.2, Kv4.1, Kv4.3, Kv5.1, Kv6.2, Kv8.1, Kv9.3, and Kv10.1-were increased in mesenteric arterial smooth muscle from OLETF rats compared with LETO rats. However, in the chronic phase of diabetes, the Kv current amplitude did not differ between LETO and OLETF rats. In addition, the 4-AP-induced contractile response of the mesenteric artery and the expression of Kv subtypes did not differ between the two groups. The increased Kv current amplitude and Kv channel-related contractile response were attributable to the increase in Kv channel expression during the early phase of diabetes. The increased Kv current amplitude and Kv channel-related contractile response were reversed during the chronic phase of diabetes.

W-7 inhibits voltage-dependent K(+) channels independent of calmodulin activity in rabbit coronary arterial smooth muscle cells

We investigated the effect of W-7, a calmodulin inhibitor, on voltage-dependent K(+) (Kv) channels in freshly isolated coronary arterial smooth muscle cells using the whole-cell patch clamp technique. The amplitude of Kv currents was inhibited by W-7 in a concentration-dependent manner, with an IC50 value of 3.38±0.47μM and a Hill coefficient of 0.84±0.10. W-7 shifted the activation curve to a more positive potential but had no significant effect on the inactivation curve, which indicated that W-7 inhibited the Kv current in a closed state of the Kv channel. Another calmodulin inhibitor, W-13, had no significant effect on Kv currents and did not change the inhibitory effect of W-7 on Kv channels. From these results, we conclude that W-7 inhibited the Kv current in a dose-dependent manner, but this inhibition occurred independent of calmodulin activity and in a closed (inactivated) state of the Kv channels.

Ca2+ channel inhibitor NNC 55-0396 inhibits voltage-dependent K+ channels in rabbit coronary arterial smooth muscle cells

We demonstrated the inhibitory effect of NNC 55-0396, a T-type Ca(2+) channel inhibitor, on voltage-dependent K(+) (K(V)) channels in freshly isolated rabbit coronary arterial smooth muscle cells. NNC 55-0396 decreased the amplitude of K(V) currents in a concentration-dependent manner, with an IC(50) of 0.080 μM and a Hill coefficient of 0.76.NNC 55-0396 did not affect steady-state activation and inactivation curves, indicating that the compound does not affect the voltage sensitivity of K(V) channel gating. Both the K(V) currents and the inhibitory effect of NNC 55-0396 on K(V) channels were not altered by depletion of extracellular Ca(2+) or intracellular ATP, suggesting that the inhibitory effect of NNC 55-0396 is independent of Ca(2+)-channel activity and phosphorylation-dependent signaling cascades. From these results, we concluded that NNC 55-0396 dosedependently inhibits K(V) currents, independently of Ca(2+)-channel activity and intracellular signaling cascades.

Electrical properties and surface morphology of SiO(x)-Pt nano-composite thin films

Recently, ceramic metals (cermets) have been widely investigated for use as embedded resistor materials. In this study, SiO-Pt nano-composite cermets were developed to control the resitivity and temperature coefficients of resistance (TCR) of embedded thin film resistors. The SiO-Pt nano-composite was prepared by the co-sputtering of a SiO(x) target and Pt chips onto glass. The experiments were conducted Pt concentrations in order to find the optimum conditions to achieve a high resistivity and low TCR. The electrical properties of the sputtered SiO-Pt thin films were investigated by probe station and their crystal structures were observed by X-Ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). The surface morphology was observed by field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). It was found that the Pt particles with a size of 3 approximately 5 nm were uniformly dispersed in the SiO matrix. A stable resistivity value of 26000 approximately 57000 microomega x cm and TCR value of -197 approximately -322 ppm/K were obtained at 3.5 approximately 3.7 at.% Pt.

The survival response of Escherichia coli K12 in a natural environment

To verify the hypothesis of cryptic growth and viable but nonculturable (VBNC) state, survival responses of Escherichia coli cells were examined under oligotrophic microcosm conditions for an extended period. In the case of filtered distilled water at 4 degrees C, E. coli cells definitely entered the VBNC state within 56 days. However, culturability and viability increased while the total number of cells declined after 110 days. This phenomenon can be explained by considering three possible states. The first is the existence of the VBNC state, the second is cryptic growth, and the third is the death of E. coli cells. In the case of artificial seawater at 4 degrees C, VBNC E. coli cells confirmed the existence of two log units of elongated VBNC cells. Moreover, elongated VBNC cells showed the most significant change among all the other transformed cells. Also, E. coli cells in microcosms at 28 degrees C indicated the entrance to the classical starvation survival state. In resuscitation tests, 1% diluted Luria-Bertani agar medium showed the highest level of resuscitation among amended agar media. To evaluate the survival ability of E. coli cells in the activated sludge samples, we used an E. colistrain XL-1 blue containing plasmids pQ2 including GFPcDNA (XL/GFP). In supernatant of activated sludge (SUP) at 28 degrees C, XL/GFP cells entered the VBNC state after 10 days, whereas existence of VBNC cells was not detectable in resuspended activated sludge (ACT) at 28 degrees C.