Anoctamin-like protein 1 regulates repolarization in Paramecium behavioral responses

Paramecium exhibits responsive behavior to environmental changes, moving either closer to or further away from stimuli. Electrophysiological experiments have revealed that these behavioral responses are controlled by membrane potentials. Anoctamin, a Ca2+-activated Cl- channel, is involved in the regulation of membrane potential in mammals. However, it remains uncertain whether Cl- channels like anoctamin regulate Paramecium behavior. Herein, replacement of external Cl- ions with acetate ion and application of Cl- channel blocker niflumic acid (NFA, 0.1 μM) increased spontaneous avoiding reactions (sARs). Hence, we hypothesized that anoctamin is involved in the stabilization of membrane potential fluctuation. Paramecium cells in which the anoctamin-like protein 1 gene was knocked down displayed frequent sARs in the culture medium without external stimulation. Treatment of anoctamin-like protein 1-knockdown cells with the Ca2+ chelator BAPTA or Ca-channel blocker nicardipine reversed the increase in sARs. Electrophysiological experiments revealed extension of membrane depolarization when positive currents were applied to anoctamin-like protein 1-knockdown cells. We concluded that anoctamin-like protein 1 works as a Cl-channel and stabilizes the membrane potential oscillation, reducing sARs.

Nationwide data from comprehensive genomic profiling assays for detecting driver oncogenes in non-small cell lung cancer

Driver oncogenes are investigated upfront at diagnosis using multi-CDx systems with next-generation sequencing techniques or multiplex reverse-transcriptase polymerase chain reaction assays. Additionally, from 2019, comprehensive genomic profiling (CGP) assays have been available in Japan for patients with advanced solid tumors who had completed or were expected to complete standard chemotherapy. These assays are expected to comprehensively detect the driver oncogenes, especially for patients with non-small cell lung cancer (NSCLC). However, there are no reports of nationwide research on the detection of driver oncogenes in patients with advanced NSCLC who undergo CGP assays, especially in those with undetected driver oncogenes at diagnosis. In this study, we investigated the proportion of driver oncogenes detected in patients with advanced NSCLC with undetectable driver oncogenes at initial diagnosis and in all patients with advanced NSCLC who underwent CGP assays. We retrospectively analyzed data from 986 patients with advanced NSCLC who underwent CGP assays between August 2019 and March 2022, using the Center for Cancer Genomics and Advanced Therapeutics database. The proportion of driver oncogenes newly detected in patients with NSCLC who tested negative for driver oncogenes at diagnosis and in all patients with NSCLC were investigated. Driver oncogenes were detected in 451 patients (45.7%). EGFR was the most common (16.5%), followed by KRAS (14.5%). Among the 330 patients with undetected EGFR, ALK, ROS1, and BRAF V600E mutations at diagnosis, 81 patients (24.5%) had newly identified driver oncogenes. CGP assays could be useful to identify driver oncogenes in patients with advanced NSCLC, including those initially undetected, facilitating personalized treatment.

Visceral Adipose Tissue Percentage Compared to Body Mass Index as Better Indicator of Surgical Outcomes in Women With Obesity and Endometrial Cancer

STUDY OBJECTIVE

To assess the impact visceral adipose tissue percentage (VAT%) on surgical outcomes during minimally invasive surgery in obese women with endometrial cancer.

DESIGN

Retrospective observational cohort study.

SETTING

Mie University Hospital, Japan.

PATIENTS

Of the 73 women (body mass index [BMI] >30 kg/m2) with obesity and primary endometrial cancer, 52 underwent robotic surgery, while 21 underwent laparoscopic surgery between April 2014 and December 2022.

INTERVENTIONS

We investigated the correlation between surgical outcomes (operative time and blood loss) and obesity (BMI and visceral adipose tissue percentage [VAT%]).

MEASUREMENTS AND MAIN RESULTS

Abdominal fat-related parameters were measured at the level of the umbilicus using preoperative computed tomography. A weak negative correlation was found between BMI and VAT% (CC = -0.313, p = .001). Multivariate analysis showed that VAT% had a stronger correlation to total and practical operative time than BMI (β = 0.338 vs 0.267, β = 0.311 vs 0.209, respectively) and was an independent predictor of blood loss. VAT% was an independent predictive marker prolonged for operative time and increased blood loss during lymphadenectomy.

CONCLUSION

VAT% could be an indicator of surgical outcomes for patients with obesity and endometrial cancer.

AXL signal mediates adaptive resistance to KRAS G12C inhibitors in KRAS G12C-mutant tumor cells

Recently, novel Kirsten rat sarcoma viral oncogene homolog (KRAS) inhibitors have been clinically developed to treat KRAS G12C-mutated non-small cell lung cancer (NSCLC) patients. However, achieving complete tumor remission is challenging. Therefore, the optimal combined therapeutic intervention with KRAS G12C inhibitors has a potentially crucial role in the clinical outcomes of patients. We investigated the underlying molecular mechanisms of adaptive resistance to KRAS G12C inhibitors in KRAS G12C-mutated NSCLC cells to devise a strategy preventing drug-tolerant cell emergence. We demonstrate that AXL signaling led to the adaptive resistance to KRAS G12C inhibitors in KRAS G12C-mutated NSCLC, activation of which is induced by GAS6 production via YAP. AXL inhibition reduced the viability of AXL-overexpressing KRAS G12C-mutated lung cancer cells by enhancing KRAS G12C inhibition-induced apoptosis. In xenograft models of AXL-overexpressing KRAS G12C-mutated lung cancer treated with KRAS G12C inhibitors, initial combination therapy with AXL inhibitor markedly delayed tumor regrowth compared with KRAS G12C inhibitor alone or with the combination after acquired resistance to KRAS G12C inhibitor. These results indicated pivotal roles for the YAP-GAS6-AXL axis and its inhibition in the intrinsic resistance to KRAS G12C inhibitor.

Optimal Protocol for Contrast-enhanced Free-running 5D Whole-heart Coronary MR Angiography at 3T

Free-running 5D whole-heart coronary MR angiography (MRA) is gaining in popularity because it reduces scanning complexity by removing the need for specific slice orientations, respiratory gating, or cardiac triggering. At 3T, a gradient echo (GRE) sequence is preferred in combination with contrast injection. However, neither the injection scheme of the gadolinium (Gd) contrast medium, the choice of the RF excitation angle, nor the dedicated image reconstruction parameters have been established for 3T GRE free-running 5D whole-heart coronary MRA. In this study, a Gd injection scheme, RF excitation angles of lipid-insensitive binominal off-resonance RF excitation (LIBRE) pulse for valid fat suppression and continuous data acquisition, and compressed-sensing reconstruction regularization parameters were optimized for contrast-enhanced free-running 5D whole-heart coronary MRA using a GRE sequence at 3T. Using this optimized protocol, contrast-enhanced free-running 5D whole-heart coronary MRA using a GRE sequence is feasible with good image quality at 3T.

Two-dimensional phase-contrast MRI reveals changes in uterine arterial blood flow in pregnant women administered tadalafil for fetal growth restriction

INTRODUCTION

We aimed to examine the effect of uterine arterial (UtA) blood flow changes after tadalafil treatment for fetal growth restriction (FGR) using two-dimensional (2D) phase-contrast magnetic resonance imaging (PC-MRI).

METHODS

We recruited 14 pregnant women with FGR aged 20-44 years, at ≥20 weeks' gestation, between May 2019 and July 2020. They underwent 2D PC-MRI for UtA blood flow measurement 3 days (interquartile range: 2-4) after diagnosis. This group (FGR group) was compared with 14 gestational age (GA)-matched healthy pregnant women (control group). Six patients in the FGR group received treatment with tadalafil administered at 20 mg twice daily after the first MRI until delivery. They underwent a second MRI a week later.

RESULTS

The median total UtA blood/body surface area was 420 mL/min/m2 (290-494) in the FGR group and 547 mL/min/m2 (433-681) in the control group (p = 0.01). Percent increase in blood flow were significantly different between the FGR cases treated with tadalafil and control at 15.8 % (14.3-21.3) and 4.2 % (3.6-8.7), respectively (p = 0.03).

DISCUSSION

UtA blood flow in pregnant women with FGR was significantly lower than that in healthy pregnant women. Tadalafil is expected to improve UtA blood flow, thereby improving placental function in pregnant patients with FGR.

Effects of Combined Therapeutic Targeting of AXL and ATR on Pleural Mesothelioma Cells

Few treatment options exist for pleural mesothelioma (PM), which is a progressive malignant tumor. However, the efficacy of molecular-targeted monotherapy is limited, and further therapeutic strategies are warranted to treat PM. Recently, the cancer cell-cycle checkpoint inhibitors have attracted attention because they disrupt cell-cycle regulation. Here, we aimed to establish a novel combinational therapeutic strategy to inhibit the cell-cycle checkpoint kinase, ATR in PM cells. The siRNA screening assay showed that anexelekto (AXL) knockdown enhanced cell growth inhibition when exposed to ATR inhibitors, demonstrating the synergistic effects of the ATR and AXL combination in some PM cells. The AXL and ATR inhibitor combination increased cell apoptosis via the Bim protein and suppressed cell migration when compared with each monotherapy. The combined therapeutic targeting of AXL and ATR significantly delayed regrowth compared with monotherapy. Thus, optimal AXL and ATR inhibition may potentially improve the PM outcome.

Associating the Severity of Emphysema with Coronary Flow Reserve and Left Atrial Conduit Function for the Emphysema Patients with Known or Suspected Coronary Artery Disease

PURPOSE

Pulmonary emphysema may associate with ischemic heart disease through systemic microvascular abnormality as a common pathway. Stress cardiovascular MR (CMR) allows for the assessment of global coronary flow reserve (CFR). The purpose of this study was to evaluate the association between the emphysema severity and the multiple MRI parameters in the emphysema patients with known or suspected coronary artery disease (CAD).

METHODS

A total of 210 patients with known or suspected CAD who underwent both 3.0T CMR including cine CMR, stress and rest perfusion CMR, stress and rest phase-contrast (PC) cine CMR of coronary sinus, and late gadolinium enhancement (LGE) CMR, and lung CT within 6 months were studied. Global CFR, volumes and functions of both ventricles and atria, and presence or absence of myocardial ischemia and infarction were evaluated. Emphysema severity was visually determined on lung CT by Goddard method.

RESULT

Seventy nine (71.0 ± 7.9 years, 75 male) of 210 patients with known or suspected CAD had emphysema on lung CT. Goddard score was significantly correlated with CFR (r = -0.246, P = 0.029), left ventricular end-diastolic volume index (LV EDVI) (r = -0.230, P = 0.041), right ventricular systolic volume index (RV SVI) (r = -0.280, P = 0.012), left atrial (LA) total emptying volume index (r = -0.269, P = 0.017), LA passive emptying volume index (r = -0.309, P = 0.006), LA systolic strain (Es) (r = -0.244, P = 0.030), and LA conduit strain (Ee) (r = -0.285, P = 0.011) in the patients with emphysema. Multiple linear regression analysis revealed LA conduit function was independently associated with emphysema severity as determined by Goddard method (beta = -0.361, P = 0.006).

CONCLUSION

LA conduit function independently associates with emphysema severity in the emphysema patients with known or suspected CAD after adjusting age, sex, smoking, and the CMR indexes including CFR. These findings suggest that impairment of LA function predominantly occurs prior to the reduction of the CFR in the emphysema patients with known or suspected CAD.

COVID-19 during pregnancy could potentially affect placental function

OBJECTIVE

COVID-19 is an ongoing pandemic and has been extensively studied. However, the effects of COVID-19 during pregnancy, particularly on placental function, have not been verified. In this study, we used blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) to evaluate whether COVID-19 incidence during pregnancy has any lasting effects with respect to placental oxygenation.

METHODS

This is a case-control study, in which eight cases of singleton pregnancies before 30 weeks gestation with COVID-19 mothers were included. Placental oxygenation was evaluated using BOLD-MRI after 32 weeks of gestation. BOLD-MRI was consecutively performed under normoxia (21% O2), hyperoxia (100% O2), and normoxia for 4 min each. Individual placental time-activity curves were evaluated to calculate the peak score (peakΔR2*) and the time from the start of maternal oxygen administration to the time of peakΔR2* (time to peakΔR2*). Eighteen COVID-19-free normal pregnancies from a previous study were used as the control group.

RESULTS

No significant differences were found between the two groups regarding maternal background, number of days of delivery, birth weight, and placental weight. The parameter peakΔR2* was significantly decreased in the COVID-19 group (8 ± 3 vs. 5 ± 1, p < .001); however, there was no significant difference in time to peakΔR2* (458 ± 74 s vs. 471 ± 33 s, p = .644).

CONCLUSIONS

In this study, BOLD-MRI was used to evaluate placental oxygenation during pregnancy in COVID-19-affected patients. COVID-19 during pregnancy decreased placental oxygenation even post-illness, but had no effect on fetal growth; further investigation of the possible effects of COVID-19 on the fetus and mother is warranted.

Microvascular Dysfunction in Patients with Idiopathic Dilated Cardiomyopathy: Quantitative Assessment with Phase Contrast Cine MR Imaging of the Coronary Sinus

PURPOSE

The purposes of this study were to compare global coronary flow reserve (CFR) between patients with idiopathic dilated cardiomyopathy (DCM) and risk-matched controls using cardiac MRI (CMR), and to evaluate the relationship between global CFR and CMR left ventricular (LV) parameters.

METHODS

Twenty-six patients with DCM and 26 risk-matched controls who underwent comprehensive CMR examination, including stress-rest coronary sinus flow measurement by phase contrast (PC) cine CMR were retrospectively studied. LV peak global longitudinal, radial, and circumferential strains (GLS, GRS, and GCS) were determined by feature tracking.

RESULTS

Patients with DCM had significantly lower global CFR compared with the risk-matched controls (2.87 ± 0.86 vs. 4.03 ± 1.47, P = 0.001). Among the parameters, univariate linear regression analyses revealed significant correlation of global CFR with LV end-diastolic volume index (r = -0.396, P = 0.045), LV mass index (r = -0.461, P = 0.018), GLS (r = -0.558, P = 0.003), and GRS (r = 0.392, P = 0.047). Multiple linear regression analysis revealed GLS as the only independent predictor of global CFR (standardized β = -0.558, P = 0.003).

CONCLUSION

Global CFR was significantly impaired in patients with idiopathic DCM and independently associated with LV GLS, suggesting that microvascular dysfunction may contribute to deterioration of LV function in patients with idiopathic DCM.

Mixed epithelial and stromal tumor of the kidney with long-term imaging follow-up

Mixed epithelial and stromal tumor (MEST) of the kidney is a rare benign tumor with malignant potential, and is characterized by epithelial and stromal proliferation with a variety of cellularity and growth pattern. MEST of the kidney is often depicted as a well-defined, solid mass with a cystic component. However, due to the rarity of the disease, there are no reports of its progression in serial imaging examinations. This report presents the case of a 68-year-old woman with MEST who was followed for 13 years by computed tomography (CT). To the best of our knowledge, this is the first report of image findings of MEST of the kidney over a follow-up period longer than 10 years.

Application of Deep Learning-Based Denoising Technique for Radiation Dose Reduction in Dynamic Abdominal CT: Comparison with Standard-Dose CT Using Hybrid Iterative Reconstruction Method

The purpose is to evaluate whether deep learning-based denoising (DLD) algorithm provides sufficient image quality for abdominal computed tomography (CT) with a 30% reduction in radiation dose, compared to standard-dose CT reconstructed with conventional hybrid iterative reconstruction (IR). The subjects consisted of 50 patients who underwent abdominal CT with standard dose and reconstructed with hybrid IR (ASiR-V50%) and another 50 patients who underwent abdominal CT with approximately 30% less dose and reconstructed with ASiR-V50% and DLD at low-, medium- and high-strength (DLD-L, DLD-M and DLD-H, respectively). The standard deviation of attenuation in liver parenchyma was measured as image noise. Contrast-to-noise ratio (CNR) for portal vein on portal venous phase was calculated. Lesion conspicuity in 23 abdominal solid mass on the reduced-dose CT was rated on a 5-point scale: 0 (best) to -4 (markedly inferior). Compared with hybrid IR of standard-dose CT, DLD-H of reduced-dose CT provided significantly lower image noise (portal phase: 9.0 (interquartile range, 8.7-9.4) HU vs 12.0 (11.4-12.7) HU, P < 0.0001) and significantly higher CNR (median, 5.8 (4.4-7.4) vs 4.3 (3.3-5.3), P = 0.0019). As for DLD-M of reduced-dose CT, no significant difference was found in image noise and CNR compared to hybrid IR of standard-dose CT (P > 0.99). Lesion conspicuity scores for DLD-H and DLD-M were significantly better than hybrid IR (P < 0.05). Dynamic contrast-enhanced abdominal CT acquired with approximately 30% lower radiation dose and generated with the DLD algorithm exhibit lower image noise and higher CNR compared to standard-dose CT with hybrid IR.

Concomitant Proton Pump Inhibitor Use With Pembrolizumab Monotherapy vs Immune Checkpoint Inhibitor Plus Chemotherapy in Patients With Non-Small Cell Lung Cancer

Importance

Immune checkpoint inhibitor (ICI) monotherapy with pembrolizumab and ICI plus chemotherapy have been approved as first-line treatments for non-small cell lung cancer (NSCLC) for patients with a programmed cell death ligand-1 (PD-L1) tumor proportion score (TPS) of 50% or more, but the choice between these 2 therapeutic options is unclear.

Objective

To clarify the association of a history of concurrent medication use with treatment outcomes for ICIs with or without chemotherapy in patients with NSCLC with a high PD-L1 TPS and to determine whether these clinical histories are biomarkers for appropriate treatment selection.

Design, Setting, and Participants

This retrospective, multicenter cohort study at 13 hospitals in Japan included patients with advanced NSCLC with a PD-L1 TPS of 50% or more who had received pembrolizumab ICI monotherapy or ICI plus chemotherapy as the initial treatment between March 2017 and December 2020. The median (IQR) follow-up duration was 18.5 (9.2-31.2) months. Data were analyzed from April 2022 through May 2023.

Exposure

ICI monotherapy with pembrolizumab or ICI plus chemotherapy as first-line treatment.

Main Outcomes and Measures

The primary analysis was the association of treatment outcomes with baseline patient characteristics, including concomitant drug history, after propensity score matching. Cox proportional hazard models were used to determine the associations of patient characteristics with survival outcomes. Logistic regression analysis was used to determine the association of concomitant medication history with treatment outcomes and other patient characteristics.

Results

A total of 425 patients with NSCLC were enrolled in the study including 271 patients (median [range] age, 72 [43-90] years; 215 [79%] men) who were treated with pembrolizumab monotherapy as the first-line treatment and 154 patients (median [range] age, 69 [36-86] years; 121 [79%] men) who were treated with ICI plus chemotherapy as the first-line treatment. In multivariable analysis, a history of proton pump inhibitor (PPI) use was independently associated with shorter progression-free survival (PFS) in the pembrolizumab monotherapy group (hazard ratio [HR], 1.38; 95% CI, 1.00-1.91; P = .048), but not in the ICI plus chemotherapy group. In patients with a PPI history, both the median (IQR) PFS (19.3 [9.0 to not reached] months vs 5.7 [2.4 to 15.2] months; HR, 0.38; 95% CI, 0.20-0.72; P = .002) and the median (IQR) overall survival (not reached [9.0 months to not reached) vs 18.4 [10.5 to 50.0] months; HR, 0.43; 95% CI, 0.20-0.92; P = .03) were significantly longer in the ICI plus chemotherapy group than in the pembrolizumab monotherapy group. In patients without a history of PPI use, both the median (IQR) PFS (18.8 months [6.6 months to not reached] vs 10.6 months [2.7 months to not reached]; HR, 0.81; 95% CI, 0.56-1.17; P = .26) and the median (IQR) overall survival (not reached [12.6 months to not reached] vs 29.9 [13.3 to 54.3] months, HR, 0.75; 95% CI, 0.48-1.18; P = .21) did not differ between groups.

Conclusions and Relevance

This cohort study found that a history of PPI use could be an important clinical factor in treatment decision-making for patients with NSCLC with a PD-L1 TPS of 50% or more.

RNA interference reveals the escape response mechanism of Paramecium to mechanical stimulation

In Paramecium, a mechanical stimulus applied to the posterior portion of the cell causes a transient increase in membrane permeability to potassium ions, transiently rendering the membrane in a hyperpolarized state. Hyperpolarization causes a transient increase in Cyclic adenosine monophosphate (cAMP) concentration in the cilia, resulting in a transient fast-forward swimming of the cell. Schultz and coworkers (1992) reported that a unique adenylate cyclase (AC)-coupled potassium channel is involved in the reaction underlying this response, which is known as the "escape response." However, the AC responsible for this reaction remains to be identified. Moreover, the molecular linkage between mechanoreception and AC activation has not been elucidated adequately. Currently, we can perform an efficient and simple gene-knockdown technique in Paramecium using RNA interference (RNAi). Paramecium is one of the several model organisms for which whole-genome sequences have been elucidated. The RNAi technique can be applied to whole genome sequences derived from the Paramecium database (ParameciumDB) to investigate the types of proteins that elicit specific biological responses and compare them with those of other model organisms. In this review, we describe the applications of the RNAi technique in elucidating the molecular mechanism underlying the escape response and identifying the AC involved in this reaction. The findings of this study highlight the advantages of the RNAi technique and ParameciumDB.

Prospective Observational Study Evaluating the Prognostic Value of the G8 Screening Tool for Extensive-Stage Small Cell Lung Cancer Patients Who Received Programmed Death-Ligand 1 Inhibitor plus Platinum-Etoposide Chemotherapy

BACKGROUND

Programmed death-ligand 1 (PD-L1) inhibitor plus platinum-etoposide chemotherapy is used as a first-line treatment for extensive-stage small cell lung cancer (ES-SCLC), regardless of age.

OBJECTIVE

We examined the role of the Geriatric 8 (G8) screening tool for evaluating treatment outcomes in patients with ES-SCLC treated with PD-L1 inhibitor plus platinum-etoposide chemotherapy as first-line therapy.

PATIENTS AND METHODS

Between September 2019 and October 2021, we prospectively evaluated patients with ES-SCLC treated with immunochemotherapy at ten institutions in Japan. The G8 score was assessed before treatment initiation.

RESULTS

We evaluated 44 patients with ES-SCLC. Patients with G8 score > 11 had longer overall survival (OS) than those with G8 score ≤ 11 (not reached versus 8.3 months; log-rank test, p = 0.005). In univariate and multivariate analyses, G8 score > 11 [hazard ratio (HR) 0.34; 95% confidence interval (CI) 0.15-0.75; p = 0.008 and HR 0.34; 95% CI 0.14-0.82; p = 0.02, respectively) and performance status (PS) of 2 (HR 5.42; 95% CI 2.08-14.2; p < 0.001 and HR 6.94; 95% CI 2.25-21.4; p < 0.001, respectively) were independent prognostic factors for OS. Among patients with good PS (0 or 1), the OS in patients with G8 score > 11 was significantly longer than that in patients with G8 score ≤ 11 (not reached versus 12.3 months; log-rank test, p = 0.02).

CONCLUSIONS

G8 score evaluation before treatment initiation was useful as a prognostic factor for ES-SCLC patients who received PD-L1 inhibitors and platinum-etoposide chemotherapy, even with good PS.

Complementary prognostic value of stress perfusion imaging and global coronary flow reserve derived from cardiovascular magnetic resonance: a long-term cohort study

BACKGROUND

Phase-contrast cine cardiovascular magnetic resonance (CMR) quantifies global coronary flow reserve (CFR) by measuring blood flow in the coronary sinus (CS), allowing assessment of the entire coronary circulation. However, the complementary prognostic value of stress perfusion CMR and global CFR in long-term follow-up has yet to be investigated. This study aimed to investigate the complementary prognostic value of stress myocardial perfusion imaging and global CFR derived from CMR in patients with suspected or known coronary artery disease (CAD) during long-term follow-up.

METHODS

Participants comprised 933 patients with suspected or known CAD who underwent comprehensive CMR. Major adverse cardiac events (MACE) comprised cardiac death, non-fatal myocardial infarction, unstable angina, hospitalization for heart failure, stroke, ventricular arrhythmia, and late revascularization.

RESULTS

During follow-up (median, 5.3 years), there were 223 MACE. Kaplan-Meier curve analysis revealed a significant difference in event-free survival among tertile groups for global CFR (log-rank, p < 0.001) and between patients with and without ischemia (p < 0.001). The combination of stress perfusion CMR and global CFR enhanced risk stratification (p < 0.001 for overall), and prognoses were comparable between the subgroup with ischemia and no impaired CFR and the subgroup with no ischemia and impaired CFR (p = 0.731). Multivariate Cox proportional hazard regression analysis showed that impaired CFR remained a significant predictor for MACE (hazard ratio, 1.6; p = 0.002) when adjusted for coronary risk factors and CMR predictors, including ischemia. The addition of impaired CFR to coronary risk factors and ischemia significantly increased the global chi-square value from 88 to 109 (p < 0.001). Continuous net reclassification improvement and integrated discrimination with the addition of global CFR to coronary risk factors plus ischemia improved to 0.352 (p < 0.001) and 0.017 (p < 0.001), respectively.

CONCLUSIONS

During long-term follow-up, stress perfusion CMR and global CFR derived from CS flow measurement provided complementary prognostic value for prediction of cardiovascular events. Microvascular dysfunction or diffuse atherosclerosis as shown by impaired global CFR may play a role as important as that of ischemia due to epicardial coronary stenosis in the risk stratification of CAD patients.

Exploratory analysis of immunochemotherapy compared to chemotherapy after EGFR-TKI in non-small cell lung cancer patients with EGFR mutation: A multicenter retrospective study

BACKGROUND

Patients with epidermal growth factor receptor (EGFR)-mutated, advanced non-small cell lung cancer have received immunochemotherapy as one of the treatment options after tyrosine kinase inhibitor (TKI) failure.

METHODS

We retrospectively examined EGFR-mutant patients treated with atezolizumab-bevacizumab-carboplatin-paclitaxel (ABCP) therapy or platinum-based chemotherapy (Chemo) after EGFR-TKI therapy at five institutions in Japan.

RESULTS

A total of 57 patients with EGFR mutation were analyzed. The median progression-free survival (PFS) and overall survival (OS) in the ABCP (n = 20) and Chemo (n = 37) were 5.6 and 20.9 months, 5.4 and 22.1 months, respectively (PFS, p = 0.39; OS, p = 0.61). In programmed death-ligand 1 (PD-L1)-positive patients, median PFS in the ABCP group was longer than in the Chemo group (6.9 vs. 4.7 months, p = 0.89). In PD-L1-negative patients, median PFS in the ABCP group was significantly shorter than in the Chemo group (4.6 vs. 8.7 months, p = 0.04). There was no difference in median PFS between the ABCP and Chemo groups in the subgroups of brain metastases, EGFR mutation status, or chemotherapy regimens, respectively.

CONCLUSION

The effect of ABCP therapy and chemotherapy was comparable in EGFR-mutant patients in a real-world setting. The indication for immunochemotherapy should be carefully considered, especially in PD-L1-negative patients.

Adaptive resistance to lorlatinib via EGFR signaling in ALK-rearranged lung cancer

Anaplastic lymphoma kinase (ALK)-tyrosine kinase inhibitors rarely elicit complete responses in patients with advanced ALK-rearranged non-small cell lung cancer (NSCLC), as a small population of tumor cells survives due to adaptive resistance. Therefore, we focused on the mechanisms underlying adaptive resistance to lorlatinib and therapeutic strategies required to overcome them. We found that epidermal growth factor receptor (EGFR) signaling was involved in the adaptive resistance to lorlatinib in ALK-rearranged NSCLC, activation of which was induced by heparin-binding EGF-like growth factor production via c-Jun activation. EGFR inhibition halted ALK-rearranged lung cancer cell proliferation by enhancing ALK inhibition-induced apoptosis via suppression of Bcl-xL. Xenograft models showed that the combination of EGFR inhibitor and lorlatinib considerably suppressed tumor regrowth following cessation of these treatments. This study provides new insights regarding tumor evolution due to EGFR signaling after lorlatinib treatment and the development of combined therapeutic strategies for ALK-rearranged lung cancer.

Different Types of Myocardial Injury due to the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Omicron Variant

Coronavirus disease 2019 (COVID-19) associated myocardial injury was caused by various mechanisms. We herein describe 2 cases presenting different types of myocardial injury due to Omicron variant. In both patients, diffuse reduced left ventricular (LV) wall motion in transthoracic echocardiography, electrocardiographic abnormality, and elevated myocardial enzymes were demonstrated. In addition, cardiovascular magnetic resonance (CMR) findings fulfilled the 2018 Lake Louise Criteria (LLC) for myocarditis. However, histological findings in 1 patient showed inflammatory cell infiltration with myocyte degeneration, while those in the other showed interstitial edema without inflammatory cell infiltration. Histological findings were crucial for a differential diagnosis of myocardial injury due to Omicron variant.

Assessment of Pseudocoarctation of the Aorta with Saccular Aneurysms by Four-Dimensional Flow Magnetic Resonance Imaging and Histological Analysis

In this study, we present the case of a 21-year-old woman with pseudocoarctation of the aorta with saccular aneurysms that were evaluated by four-dimensional flow magnetic resonance imaging and histological analysis. We observed complete occupation of the aneurysm sacs by vortex flow and high peak wall shear stress in the proximal region of the kinked aorta. The aortic replacement was performed for the thoracic aortic aneurysms and the clinical course was uneventful. The aneurysms were histopathologically diagnosed as pseudoaneurysms based on the disappearance of all three layers and their replacement with collagen-rich connective tissues. These findings indicate that abnormal flow dynamics and the resulting abnormal shear stress in the aorta may play central roles in the formation and development of a saccular aneurysm.

Preliminary results of reduced myocardial blood flow in the subacute phase after radiation therapy for thoracic esophageal cancer: A quantitative analysis with stress dynamic myocardial computed tomography perfusion imaging

BACKGROUND AND PURPOSE

Late adverse cardiac events after radiation therapy (RT) for thoracic malignancies are known, but the underlying mechanisms are poorly understood. This study aimed to determine the radiation dose that can cause MBF alterations in the subacute phase after RT for thoracic esophageal cancer using stress dynamic myocardial computed tomography perfusion imaging (CTP).

MATERIALS AND METHODS

Twenty-five patients with esophageal cancer scheduled for RT were prospectively enrolled. The quantitative analysis of MBF by CTP was performed before and 3 months after RT. The mean radiation dose and hyperemic MBF in 15 segments of the left ventricular (LV) myocardium were determined. ΔMBF was calculated in each segment as MBFafter RT - MBFbeforeRT. The myocardial segments were classified into the following 5 groups according to the mean radiation dose: group A, <10 Gy; B1, 10-15 Gy; B2, 15-20 Gy; C, 20-30 Gy; and D, >30 Gy.

RESULTS

The final cohort included 22 patients who completed pre- and post-RT CTP. A one-way analysis of variance revealed a significant difference (p=0.005) in ΔMBF among the five groups of LV segments classified by the mean radiation dose. ΔMBF was significantly lower in group C (-7.7 ± 28.9 mL/min/100 g, p=0.020) and group D (-8.4 ± 34.8 mL/min/100 g, p=0.004) in comparison to ΔMBF in group A (4.9 ± 26.1 mL/min/100 g).

CONCLUSIONS

This study using CTP early after RT demonstrated a significant reduction of the MBF in the LV segments with ≥20 Gy of radiation. The results might provide important insights into preventing radiotherapy-induced cardiac events.

DNA damage induced by radiation exposure from cardiac catheterization – an analysis in patients and operators

Background

The biological effects of low-dose radiation from cardiac imaging or intervention remain largely unknown. This study aimed to evaluate the effects of ionized radiation from cardiac catheterization on genomic DNA integrity and inflammatory cytokines in patients and operators.

Methods

Peripheral mononuclear cells (MNCs) were isolated from patients (n=52) and operators (n=35) before and after coronary angiography and/or percutaneous coronary intervention. Expression of gammaH2AX, a marker for DNA double-strand breaks, was measured by immunofluorescence. Dicentric chromosomes (DICs), a form of chromosome aberrations, were assayed using a fluorescent in situ hybridization technique.

Results

In the patient MNCs, the numbers of gammaH2AX foci and DICs increased after cardiac catheterization by 101±75% and 28±99%, respectively (P&lt;0.05 for both). The mRNA expressions of interleukin (IL)-1α, IL-1β, leukemia inhibitory factor (LIF) and caspase-1 were significantly increased by radiation exposure from cardiac catheterization. The increase in IL-1β was significantly correlated with that of gammaH2AX, but not with dose area product. In the operators, neither gammaH2AX foci nor DICs level was changed, but IL-1β mRNA was significantly increased. Protein expression of IkappaBα was significantly decreased in both groups.

Conclusions

DNA damage was increased in the MNCs of patients, but not of operators, who underwent cardiac catheterization. Inflammatory cytokines were increased both in the patients and operators, presumably through activation of NF-kappaB. Further efforts to reduce radiation exposure from cardiac catheterization are necessary both for patients and operators.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grants-in-Aid for Scientific Research (KAKENHI)

Peripartum Mid-Ventricular-Type Takotsubo Cardiomyopathy After Cesarean Delivery

There are several causes of heart failure during pregnancy and the peripartum period, which include peripartum cardiomyopathy, Takotsubo cardiomyopathy or stress cardiomyopathy, exacerbation of a preexisting cardiomyopathy, and acute myocarditis. It is important to determine the cause of the heart failure as the medical treatment may be different based on the diagnosis. However, it has been sometimes challenging to diagnose the cause because of the limited diagnostic tools, especially in pregnant women. Cardiac MRI can characterize myocardial injury and can be used to track the changes in myocardial tissue. We herein report a 35-year-old woman diagnosed with peripartum mid-ventricular-type Takotsubo cardiomyopathy, who was referred to our hospital due to worsening dyspnea the day after cesarean delivery. On admission, electrocardiography showed sinus tachycardia and poor progression of R waves in the precordial leads. Bedside echocardiography revealed severe hypokinesis in the mid- and apical left ventricle (LV) with a LV ejection fraction of 20%. Cardiac catheterization showed normal coronary arteries, and myocardial biopsy revealed contraction band necrosis. On acute phase (Day 4), cardiac MRI showed prolonged native T1 and T2, and severe hypokinesis and decreased regional longitudinal peak strain in the mid-anterior LV wall. During the 1^st week, precordial ST fluctuation was observed, and LV wall motion had gradually recovered. Repeat cardiac MRI revealed normalized LV wall motion and shortened values for global native T1 and T2. Thus, she was diagnosed with peripartum Takotsubo cardiomyopathy. Serial cardiac MRI may be able to differentiate Takotsubo cardiomyopathy during pregnancy and the peripartum period from other preexisting cardiomyopathies.

Efficacy and safety of immuno-chemotherapy in patients with advanced non-small-cell lung cancer harboring oncogenic mutations: a multicenter retrospective study

PURPOSE

The effect of immuno-chemotherapy on patients with advanced non-small-cell lung cancer (NSCLC) harboring oncogenic mutations remains poorly understood. This study aimed to characterize the efficacy of immuno-chemotherapy and determine the optimal treatment strategy for such patients.

METHODS

We conducted this retrospective cohort study on patients with NSCLC harboring oncogenic driver alterations and treated with an immune checkpoint inhibitor combined with chemotherapy at five institutions. The clinical characteristics and outcomes of immuno-chemotherapy for NSCLC with oncogenic mutations in a real-world setting were analyzed.

RESULTS

Among 846 patients diagnosed with advanced or recurrent NSCLC between April 2017 and April 2021, 43 patients with oncogenic mutations were treated with immuno-chemotherapy. The median age of patients was 68 (range 44-78) years; 42% of patients never smoked, and adenocarcinoma was the most common histology (95%). In patients with KRAS mutations (n = 10) or PD-L1 expression of 50% or greater (n = 10), the disease control rate was 100%. The median progression-free survival (PFS) was 5.4, 6.3, and 8.9 months in patients harboring mutations in EGFR, KRAS, and other genes, respectively (P = 0.22). Patients with PD-L1 expression of 50% or greater had significantly longer median PFS than patients with PD-L1 expression of less than 50% (16.4 vs. 5.1 months; P = 0.001). Two patients experienced grade 3 immuno-related adverse events.

CONCLUSION

Immuno-chemotherapy has a clinical benefit and is safe for patients with oncogenic mutations. Notably, patients with PD-L1 expression of 50% or more experience greater benefit from immuno-chemotherapy than those with PD-L1 expression of less than 50%.

Subtle-but-smouldering myocardial injury after immune checkpoint inhibitor treatment accompanied by amyloid deposits

Although cardiac troponin is a highly specific biomarker for myocardial cell injury, it is important to recognize the pitfalls of this test in the diagnosis and management of immune checkpoint inhibitor (ICI) myocarditis. We describe the challenging case of an 81‐year‐old woman with persistently high troponin after undergoing immunotherapy with ipilimumab and nivolumab, and histological evidence of amyloid deposition in the myocardium. The patient received immunosuppressive treatments based on the magnitude of troponin changes because myocarditis was clinically suspected. However, histological examination revealed the deposition of transthyretin amyloid fibrils with only minimal T‐lymphocyte infiltration and no myocyte necrosis, suggesting transthyretin cardiac amyloidosis rather than ICI myocarditis. This case highlights the importance of assessing other causes of persistently high troponin, and the necessity of incorporating comprehensive histological and immunohistochemical examinations of the endomyocardial biopsy, especially when cardiovascular magnetic resonance imaging is inconclusive.

Advances in Myocardial Perfusion MR Imaging: Physiological Implications, the Importance of Quantitative Analysis, and Impact on Patient Care in Coronary Artery Disease

Stress myocardial perfusion imaging (MPI) is the preferred test in patients with intermediate-to-high clinical likelihood of coronary artery disease (CAD) and can be used as a gatekeeper to avoid unnecessary revascularization. Cardiac magnetic resonance (CMR) has a number of favorable characteristics, including: (1) high spatial resolution that can delineate subendocardial ischemia; (2) comprehensive assessment of morphology, global and regional cardiac functions, tissue characterization, and coronary artery stenosis; and (3) no radiation exposure to patients. According to meta-analysis studies, the diagnostic accuracy of perfusion CMR is comparable to positron emission tomography (PET) and perfusion CT, and is better than single-photon emission CT (SPECT) when fractional flow reserve (FFR) is used as a reference standard. In addition, stress CMR has an excellent prognostic value. One meta-analysis study demonstrated the annual event rate of cardiovascular death or non-fatal myocardial infarction was 4.9% and 0.8%, respectively, in patients with positive and negative stress CMR. Quantitative assessment of perfusion CMR not only allows the objective evaluation of regional ischemia but also provides insights into the pathophysiology of microvascular disease and diffuse subclinical atherosclerosis. For accurate quantification of myocardial perfusion, saturation correction of arterial input function is important. There are two major approaches for saturation correction, one is a dual-bolus method and the other is a dual-sequence method. Absolute quantitative mapping with myocardial perfusion CMR has good accuracy in detecting coronary microvascular dysfunction. Flow measurement in the coronary sinus (CS) with phase contrast cine CMR is an alternative approach to quantify global coronary flow reserve (CFR). The measurement of global CFR by quantitative analysis of perfusion CMR or flow measurement in the CS permits assessment of microvascular disease and diffuse subclinical atherosclerosis, which may provide improved prediction of future event risk in patients with suspected or known CAD. Multi-institutional studies to validate the diagnostic and prognostic values of quantitative perfusion CMR approaches are required.

Impact of docetaxel plus ramucirumab in a second-line setting after chemoimmunotherapy in patients with non-small-cell lung cancer: A retrospective study

BACKGROUND

Chemoimmunotherapy has become a standard treatment option for patients with untreated advanced non-small-cell lung cancer (NSCLC). However, numerous patients with advanced NSCLC develop disease progression. Therefore, the selection of second-line treatment after chemoimmunotherapy is crucial for improving clinical outcomes.

METHODS

Of 88 enrolled patients with advanced NSCLC who received chemoimmunotherapy, we retrospectively evaluated 33 who received second-line chemotherapy after progression of chemoimmunotherapy at six centers in Japan. Among them, 18 patients received docetaxel plus ramucirumab and 15 patients received single-agent chemotherapy.

RESULTS

The objective response rate in patients treated with docetaxel plus ramucirumab was significantly higher than that in patients treated with a single-agent chemotherapy regimen (55.6% vs. 0%, p < 0.001). The median progression-free survival (PFS) of patients who received docetaxel plus ramucirumab and single-agent chemotherapy was 5.8 months and 5.0 months, respectively (log-rank test p = 0.17). In the docetaxel plus ramucirumab regimen group, patients who responded to chemoimmunotherapy for ≥8.8 months had a significantly longer response to docetaxel plus ramucirumab than those who responded for <8.8 months (not reached vs. 4.1 months, log-rank test p = 0.003). In contrast, in the single-agent chemotherapy group, there was no significant difference in PFS between the ≥8.8- and <8.8-month PFS groups with chemoimmunotherapy (5.0 vs. 1.6 months, log-rank test p = 0.66).

CONCLUSION

Our retrospective observations suggest that the group with longer PFS with chemoimmunotherapy might be expected to benefit from docetaxel plus ramucirumab treatment in second-line settings for patients with advanced NSCLC.

Wild-type Transthyretin Amyloidosis with Diffuse Alveolar-septal Amyloidosis Diagnosed by a Transbronchial Lung Biopsy

A 69-year-old man visited our pulmonary medicine department for dyspnea. Chest computed tomography (CT) revealed ground-glass opacity bilaterally in the lungs. Upon performing a transbronchial lung biopsy (TBLB), organizing pneumonia was diagnosed. His electrocardiogram revealed low voltage, and the cardiac ultrasound revealed hypertrophy of the interventricular septum. The patient had bilateral carpal tunnel syndrome, and amyloidosis was suspected. Congo red stain was added to the lung biopsy specimen. Amyloid deposition of transthyretin (ATTR) was positive, mutations with amino acid changes were not observed in the TTR gene. Wild-type ATTR Amyloidosis (ATTRwt amyloidosis) was diagnosed using a TBLB. Chest CT after treatment with steroids revealed diffuse alveolar-septal amyloidosis.

Prognostic Markers of Survival among Japanese Patients with Anaplastic Lymphoma Kinase-Positive Non-Small-Cell Lung Cancer Receiving First-Line Alectinib

The prognoses of patients with non-small-cell lung cancer (NSCLC) harboring anaplastic lymphoma kinase (ALK) gene rearrangement have dramatically improved with the use of ALK tyrosine kinase inhibitors. Although immunological and nutritional markers have been investigated to predict outcomes in patients with several cancers, their usefulness in targeted therapies is scarce, and their significance has never been reported in patients receiving first-line treatment with alectinib. Meanwhile, neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio (PLR) has been investigated during crizotinib treatment. This multicenter retrospective study evaluated 42 consecutive Japanese patients with ALK-positive NSCLC who received first-line treatment with alectinib. Immunological and nutritional markers were evaluated at baseline and 3 weeks after alectinib introduction, and their significance in predicting progression-free survival (PFS) was explored. PFS duration was significantly associated with baseline PLR (hazard ratio (HR): 2.49, p = 0.0473), systemic immune-inflammation index (SII; HR: 2.65, p = 0.0337), prognostic nutrition index (PNI; HR: 4.15, p = 0.00185), and the 3-week values for SII (HR: 2.85, p = 0.0473) and PNI (HR: 3.04, p = 0.0125). Immunological and nutritional markers could be useful in predicting the outcomes of first-line treatment with alectinib. Since PLR and SII consist of platelet counts, platelet count could be an important constituent of these markers.

Clinical Validation of the Accuracy of Absolute Myocardial Blood Flow Quantification with Dual-Source CT Using 15O-Water PET

PURPOSE

To determine the fitting equation that can correct for the underestimation of myocardial blood flow (MBF) measurement by using dynamic CT perfusion (CTP) with dual-source CT (MBFCT), using MBF with oxygen 15-labeled water (15O-water) PET (MBFPET) as a reference, and to determine the accuracy of corrected MBFCT (MBFCT-corrected) compared with MBFPET in a separate set of participants.

MATERIALS AND METHODS

In this prospective study (reference no. 2466), 34 participants (mean age, 70 years ± 8 [standard deviation]; 27 men) known or suspected to have coronary artery disease underwent dynamic stress CTP and stress 15O-water PET between January 2014 and December 2018. The participants were randomly assigned to either a pilot group (n = 17), to determine the fitting equation on the basis of the generalized Renkin-Crone model that can explain the relation between MBFCT and MBFPET, or to a validation group (n = 17), to validate MBFCT-corrected compared with MBFPET. The agreement between MBFCT-corrected and MBFPET was evaluated by intraclass correlation and Bland-Altman analysis.

RESULTS

In the pilot group, MBFCT was lower than MBFPET (1.24 mL/min/g ± 0.28 vs 2.51 mL/min/g ± 0.89, P < .001) at the segment level. The relationship between MBFCT and MBFCT-corrected was represented as MBFCT = MBFCT-corrected × {1-exp[-(0.11 × MBFCT-corrected + 1.54)/MBFCT-corrected]}. In the validation group, MBFCT-corrected was 2.66 mL/min/g ± 1.93, and MBFPET was 2.68 mL/min/g ± 1.87 at the vessel level. MBFCT-corrected showed an excellent agreement with MBFPET (intraclass correlation coefficient = 0.93 [95% CI: 0.87, 0.96]). The measurement bias of MBFCT-corrected and MBFPET was -0.02 mL/min/g ± 0.74.

CONCLUSION

Underestimation of MBF by CT was successfully corrected with a correction method that was based on contrast kinetics in the myocardium.Keywords: CT, CT-Perfusion, PET, Cardiac, Heart Supplemental material is available for this article. © RSNA, 2021.

Improving Image Resolution of Whole-Heart Coronary MRA Using Convolutional Neural Network

Whole-heart coronary magnetic resonance angiography (WHCMRA) permits the noninvasive assessment of coronary artery disease without radiation exposure. However, the image resolution of WHCMRA is limited. Recently, convolutional neural networks (CNNs) have obtained increased interest as a method for improving the resolution of medical images. The purpose of this study is to improve the resolution of WHCMRA images using a CNN. Free-breathing WHCMRA images with 512 × 512 pixels (pixel size = 0.65 mm) were acquired in 80 patients with known or suspected coronary artery disease using a 1.5 T magnetic resonance (MR) system with 32 channel coils. A CNN model was optimized by evaluating CNNs with different structures. The proposed CNN model was trained based on the relationship of signal patterns between low-resolution patches (small regions) and the corresponding high-resolution patches using a training dataset collected from 40 patients. Images with 512 × 512 pixels were restored from 256 × 256 down-sampled WHCMRA images (pixel size = 1.3 mm) with three different approaches: the proposed CNN, bicubic interpolation (BCI), and the previously reported super-resolution CNN (SRCNN). High-resolution WHCMRA images obtained using the proposed CNN model were significantly better than those of BCI and SRCNN in terms of root mean squared error, peak signal to noise ratio, and structure similarity index measure with respect to the original WHCMRA images. The proposed CNN approach can provide high-resolution WHCMRA images with better accuracy than BCI and SRCNN. The high-resolution WHCMRA obtained using the proposed CNN model will be useful for identifying coronary artery disease.

Prognostic importance of acute phase extracellular volume evaluated by cardiac magnetic resonance imaging for patients with acute myocardial infarction

Myocardial extracellular volume (ECV) by cardiac magnetic resonance (CMR) in the acute phase of acute myocardial infarction (MI) more precisely predicts the functional recovery of infarct-related wall motion abnormalities and left ventricular (LV) remodeling than late gadolinium enhancement (LGE). The purpose of this study was to evaluate the prognostic importance of acute phase ECV in patients with AMI. We evaluated 61 consecutive AMI patients using 3.0 T CMR. CMR examination was performed median 10 days (7-15 days) after PCI. Primary endpoint was defined as major adverse cardiac event (MACE). The median follow-up duration was 3.1 years, and MACE occurred in 11 (18%) patients. Although LVEF and % infarct LGE volume were not associated with MACE in this study population, higher infarct ECV predicted the MACE with a hazard ratio (HR) of 4.04 (P = 0.02). High global ECV, which was a combined assessment of infarct ECV and remote ECV, also predicted MACE with a HR of 5.24 (P = 0.035). The addition of infarct ECV to remote ECV (global chi-squared score: 1.4) resulted in a significantly increased global chi-squared score (6.7; P = 0.017). Furthermore, after adjusting for the calculated propensity score for high global ECV, it remained an independent predictor of MACE with HR of 5.10 (P = 0.04). The quantification of ECV in the acute phase among AMI patients may provide an incremental prognostic value for predicting MACE beyond that of clinical, angiographic, and functional variables.

Characterization of a novel type of carbonic anhydrase that acts without metal cofactors

Background

Carbonic anhydrases (CAs) are universal metalloenzymes that catalyze the reversible conversion of carbon dioxide (CO₂) and bicarbonate (HCO₃^-). They are involved in various biological processes, including pH control, respiration, and photosynthesis. To date, eight evolutionarily unrelated classes of CA families (α, β, γ, δ, ζ, η, θ, and ι) have been identified. All are characterized by an active site accommodating the binding of a metal cofactor, which is assumed to play a central role in catalysis. This feature is thought to be the result of convergent evolution.

Results

Here, we report that a previously uncharacterized protein group, named “COG4337,” constitutes metal-independent CAs from the newly discovered ι-class. Genes coding for COG4337 proteins are found in various bacteria and photosynthetic eukaryotic algae. Biochemical assays demonstrated that recombinant COG4337 proteins from a cyanobacterium (Anabaena sp. PCC7120) and a chlorarachniophyte alga (Bigelowiella natans) accelerated CO₂ hydration. Unexpectedly, these proteins exhibited their activity under metal-free conditions. Based on X-ray crystallography and point mutation analysis, we identified a metal-free active site within the cone-shaped α+β barrel structure. Furthermore, subcellular localization experiments revealed that COG4337 proteins are targeted into plastids and mitochondria of B. natans, implicating their involvement in CO₂ metabolism in these organelles.

Conclusions

COG4337 proteins shared a short sequence motif and overall structure with ι-class CAs, whereas they were characterized by metal independence, unlike any known CAs. Therefore, COG4337 proteins could be treated as a variant type of ι-class CAs. Our findings suggested that this novel type of ι-CAs can function even in metal-poor environments (e.g., the open ocean) without competition with other metalloproteins for trace metals. Considering the widespread prevalence of ι-CAs across microalgae, this class of CAs may play a role in the global carbon cycle.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-021-01039-8.

Long-term prognostic value of whole-heart coronary magnetic resonance angiography

BACKGROUND

Coronary magnetic resonance angiography (CMRA) allows non-ionizing visualization of luminal narrowing in coronary artery disease (CAD). Although a prior study showed the usefulness of CMRA for risk stratification in short-term follow-up, the long-term prognostic value of CMRA remains unclear. The purpose of this study was to evaluate the long-term prognostic value of CMRA.

METHODS

A total of 506 patients without history of myocardial infarction or prior coronary artery revascularization underwent free-breathing whole-heart CMRA between 2009 and 2015. Images were acquired using a 1.5 T or 3 T scanner and visually evaluated as the consensus decisions of two observers. Obstructive CAD on CMRA was defined as luminal narrowing of ≥ 50% in at least one coronary artery. Major adverse cardiac events (MACE) comprised cardiac death, nonfatal myocardial infarction, and unstable angina.

RESULTS

Obstructive CAD on CMRA was observed in 214 patients (42%). During follow-up (median, 5.6 years), 31 MACE occurred. Kaplan-Meier curve analysis revealed a significant difference in event-free survival between patients with and without obstructive CAD for MACE (log-rank, p = 0.003) and cardiac death (p = 0.012). Annualized event rates for MACE in patients with no obstructive CAD, 1-vessel disease, 2-vessel disease, and left-main or 3-vessel disease were 0.6%, 1.5%, 2.3%, and 3.6%, respectively (log-rank, p = 0.003). Cox proportional hazard regression analysis showed that, among obstructive CAD on CMRA and clinical risk factors (age, sex, hypertension, diabetes, dyslipidemia, smoking, and family history of CAD), obstructive CAD and diabetes were significant predictors of MACE (hazard ratios, 2.9 [p = 0.005] and 2.2 [p = 0.034], respectively). In multivariate analysis, obstructive CAD remained an independent predictor (adjusted hazard ratio, 2.6 [p = 0.010]) after adjusting for diabetes. Addition of obstructive CAD to clinical risk factors significantly increased the global chi-square result from 8.3 to 13.8 (p = 0.022).

CONCLUSIONS

In long-term follow-up, free breathing whole heart CMRA allows non-invasive risk stratification for MACE and cardiac death and provides incremental prognostic value over conventional risk factors in patients without a history of myocardial infarction or prior coronary artery revascularization. The presence and severity of obstructive CAD detected by CMRA were associated with worse prognosis. Importantly, patients without obstructive CAD on CMRA displayed favorable prognosis.

A Functional Aqp1 Gene Product Localizes on The Contractile Vacuole Complex in Paramecium multimicronucleatum

In a ciliate Paramecium, the presence of water channels on the membrane of contractile vacuole has long been predicted by both morphological and physiological data, however, to date either the biochemical or the molecular biological data have not been provided. In the present study, to examine the presence of aquaporin in Paramecium, we carried out RT-PCR with degenerated primers designed based on the ParameciumDB, and an aquaporin cDNA (aquaporin 1, aqp1) with a full-length ORF encoding 251 amino acids was obtained from Paramecium multimicronucleatum by using RACE. The deduced amino acid sequence of AQP1 had NPA-NPG motifs, and the prediction of protein secondary structure by CNR5000 and hydropathy plot showed the presence of six putative transmembrane domains and five connecting loops. Phylogenetic analysis results showed that the amino acid sequence of AQP1 was close to that of the Super-aquaporin group. The AQP1-GFP fusion protein clearly demonstrated the subcellular localization of AQP1 on the contractile vacuole complex, except for the decorated spongiome membrane. The functional analyses of aqp1 were done by RNA interference-based gene silencing, using an established feeding method. The aqp1 was found to be crucial for the total fluid output of the cell, the function of contractile vacuole membranes.

Evaluation of placental oxygenation index using blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) during normal late pregnancy

AIM

Noninvasive blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) has recently been used to evaluate placental oxygenation. However, this method still has unresolved problems, such as long testing times and lack of normal values set. In the present study, we used a shorter protocol in BOLD-MRI and established normal values for placental oxygenation in late pregnancy.

METHODS

We recruited 18 healthy singleton pregnant women (>32 weeks of gestation) who had a normal body size before pregnancy and a normal course of pregnancy. They underwent BOLD-MRI with three consecutive 4-min periods of different oxygenation: normoxia (21% O₂), hyperoxia (10 L O₂/min), and then normoxia. Placental time-activity curves were presented as signal intensity change relative to baseline (ΔR2*). The time from starting maternal oxygen administration to peak ΔR2*. To assess the relationship between peak ΔR2* values and placenta-related parameters and fetal development, the correlation between peak ΔR2*, placental weight, and neonatal birth weight was evaluated using Spearman's rank correlation test.

RESULTS

In all cases, the BOLD signal was elevated by maternal oxygen administration, with the peak resolving within 4 min after the end of oxygen administration. Peak ΔR2* and time to peak ΔR2* during oxygenation were 7.99 ± 2.58, and 458.1 ± 73.9 s, respectively. There was a significant correlation between peak ΔR2* and neonatal birth weight (percentile) (r = 0.537, p = .022), and between placental weight and neonatal birth weight (r = 0.769, p < .01).

CONCLUSIONS

In all cases, the BOLD signal increased with maternal hyperoxia using this protocol. So, 4 min observation following maternal oxygen administration is sufficient for peak ΔR2* evaluation. These reference values set in this study may be one of the indicators of BOLD signal changes in normal pregnancies after 32 weeks of gestation.