Ago2 and a miRNA reduce Topoisomerase 1 for enhancing DNA cleavage in antibody diversification by activation-induced cytidine deaminase.

Activation-induced cytidine deaminase (AID) is the essential enzyme for imprinting immunological memory through class switch recombination (CSR) and somatic hypermutation (SHM) of the immunoglobulin (Ig) gene. AID-dependent reduction of Topoisomerase 1 (Top1) promotes DNA cleavage that occurs upon Ig gene diversification, whereas the mechanism behind AID-induced Top1 reduction remains unclear. Here, we clarified the contribution of the microRNA-Ago2 complex in AID-dependent Top1 decrease. Ago2 binds to Top1 3'UTR with two regions of AID-dependent Ago2-binding sites (5'- and 3'dABs). Top1 3'UTR knockout (3'UTRKO) in B lymphoma cells leads to decreases in DNA break efficiency in the IgH gene accompanied by a reduction in CSR and SHM frequencies. Furthermore, AID-dependent Top1 protein reduction and Ago2-binding to Top1 mRNA are down-regulated in 3'UTRKO cells. Top1 mRNA in the highly translated fractions of the sucrose gradient is decreased in an AID-dependent and Top1 3'UTR-mediated manner, resulting in a decrease in Top1 protein synthesis. Both AID and Ago2 localize in the mRNA-binding protein fractions and they interact with each other. Furthermore, we found some candidate miRNAs which possibly bind to 5'- and 3'dAB in Top1 mRNA. Among them, miR-92a-3p knockdown induces the phenotypes of 3'UTRKO cells to wild-type cells whereas it does not impact on 3'UTRKO cells. Taken together, the Ago2-miR-92a-3p complex will be recruited to Top1 3'UTR in an AID-dependent manner and posttranscriptionally reduces Top1 protein synthesis. These consequences cause the increase in a non-B-DNA structure, enhance DNA cleavage by Top1 in the Ig gene and contribute to immunological memory formation.

Lysophospholipid Acyltransferase 9 Promotes Emphysema Formation via Platelet-activating Factor.

Cigarette smoking is known to be the leading cause of chronic obstructive pulmonary disease (COPD). However, the detailed mechanisms have not been elucidated. PAF (platelet-activating factor), a potent inflammatory mediator, is involved in the pathogenesis of various respiratory diseases such as bronchial asthma and COPD. We focused on LPLAT9 (lysophospholipid acyltransferase 9), a biosynthetic enzyme of PAF, in the pathogenesis of COPD. LPLAT9 gene expression was observed in excised COPD lungs and single-cell RNA sequencing data of alveolar macrophages (AMs). LPLAT9 was predominant and upregulated in AMs, particularly monocyte-derived AMs, in patients with COPD. To identify the function of LPLAT9/PAF in AMs in the pathogenesis of COPD, we exposed systemic LPLAT9-knockout (LPALT9-/-) mice to cigarette smoke (CS). CS increased the number of AMs, especially the monocyte-derived fraction, which secreted MMP12 (matrix metalloprotease 12). Also, CS augmented LPLAT9 phosphorylation/activation on macrophages and, subsequently, PAF synthesis in the lung. The LPLAT9-/- mouse lung showed reduced PAF production after CS exposure. Intratracheal PAF administration accumulated AMs by increasing MCP1 (monocyte chemoattractant protein-1). After CS exposure, AM accumulation and subsequent pulmonary emphysema, a primary pathologic change of COPD, were reduced in LPALT9-/- mice compared with LPLAT9+/+ mice. Notably, these phenotypes were again worsened by LPLAT9+/+ bone marrow transplantation in LPALT9-/- mice. Thus, CS-induced LPLAT9 activation in monocyte-derived AMs aggravated pulmonary emphysema via PAF-induced further accumulation of AMs. These results suggest that PAF synthesized by LPLAT9 has an important role in the pathogenesis of COPD.

Durvalumab after chemoradiotherapy in non-small cell lung cancer with EGFR mutation: A real-world study (HOT2101).

Durvalumab has been administered to patients with unresectable stage III non-small cell lung cancer (NSCLC). However, it remains unclear whether durvalumab benefits these patients with epidermal growth factor receptor (EGFR) mutation. We conducted a retrospective, multicenter study of patients with EGFR mutation who received chemoradiotherapy (CRT) between June 2018 and March 2021. We assessed patient characteristics, efficacy of durvalumab, and durvalumab safety before and after targeted therapy. We collected data on a total of 673 patients, of whom 401 (59.6%) underwent EGFR mutation testing. Fifty-one patients were EGFR positive and 311 were EGFR negative. In the EGFR-positive group, there were higher proportions of females, never-smokers, and patients with adenocarcinoma histology. Of the 51 patients in the positive group and 311 in the negative group who received CRT, 45 (88.2%) and 247 (79.4%) received durvalumab, with median progression-free survival of 23.0 and 24.2 months in the positive and negative groups, respectively (hazard ratio 1.03; 95% confidence interval: 0.64-1.67). The main adverse event was pneumonitis (positive group: 62.2%; 4.4% grade 3; negative group: 62.3%; 6.9% grade 3). No treatment-related deaths were observed. Of the 45 patients in the positive group who received durvalumab, 14 (31.1%) received targeted therapy after durvalumab at the data cutoff. One patient discontinued targeted therapy after developing pneumonitis. In patients with unresectable stage III NSCLC with EGFR mutation, durvalumab after CRT is potentially safe and effective. This may be a suitable treatment sequence for these patients.

SAMHD1-mediated dNTP degradation is required for efficient DNA repair during antibody class switch recombination.

Sterile alpha motif and histidine-aspartic acid domain-containing protein 1 (SAMHD1), a dNTP triphosphohydrolase, regulates the levels of cellular dNTPs through their hydrolysis. SAMHD1 protects cells from invading viruses that depend on dNTPs to replicate and is frequently mutated in cancers and Aicardi-Goutières syndrome, a hereditary autoimmune encephalopathy. We discovered that SAMHD1 localizes at the immunoglobulin (Ig) switch region, and serves as a novel DNA repair regulator of Ig class switch recombination (CSR). Depletion of SAMHD1 impaired not only CSR but also IgH/c-Myc translocation. Consistently, we could inhibit these two processes by elevating the cellular nucleotide pool. A high frequency of nucleotide insertion at the break-point junctions is a notable feature in SAMHD1 deficiency during activation-induced cytidine deaminase-mediated genomic instability. Interestingly, CSR induced by staggered but not blunt, double-stranded DNA breaks was impaired by SAMHD1 depletion, which was accompanied by enhanced nucleotide insertions at recombination junctions. We propose that SAMHD1-mediated dNTP balance regulates dNTP-sensitive DNA end-processing enzyme and promotes CSR and aberrant genomic rearrangements by suppressing the insertional DNA repair pathway.

Necessity of HuR/ELAVL1 for the activation-induced cytidine deaminase-dependent decrease in topoisomerase 1 in antibody diversification.

Activation-induced cytidine deaminase (AID)-dependent DNA cleavage is the initial event of antibody gene-diversification processes such as class switch recombination (CSR) and somatic hypermutation (SHM). We previously reported the requirement of an AID-dependent decrease of topoisomerase 1 (Top1) for efficient DNA cleavage, but the underlying molecular mechanism has remained elusive. This study focuses on HuR/ELAVL1, a protein that binds to AU-rich elements in RNA. HuR-knockout (KO) CH12 cells derived from murine B lymphoma cells were found to have lower CSR and hypermutation efficiencies due to decreased AID-dependent DNA cleavage levels. The HuR-KO CH12 cells do not show impairment in cell cycles and Myc expression, which have been reported in HuR-reduced spleen B cells. Furthermore, drugs that scavenge reactive oxygen species (ROS) do not rescue the lower CSR in HuR-KO CH12 cells, meaning that ROS or decreased c-Myc protein amount is not the reason for the deficiencies of CSR and hypermutation in HuR-KO CH12 cells. We show that HuR binds to Top1 mRNA and that complete deletion of HuR abolishes AID-dependent repression of Top1 protein synthesis in CH12 cells. Additionally, reduction of CSR to IgG3 in HuR-KO cells is rescued by knockdown of Top1, indicating that elimination of the AID-dependent Top1 decrease is the cause of the inefficiency of DNA cleavage, CSR and hypermutation in HuR-KO cells. These results show that HuR is required for initiation of antibody diversification and acquired immunity through the regulation of AID-dependent DNA cleavage by repressing Top1 protein synthesis.

Photocatalytic degradation process of antibiotic sulfamethoxazole by ZnO in aquatic systems: a dynamic kinetic model based on contributions of OH radical, oxygenated radical intermediates and dissolved oxygen.

The photocatalytic degradation process of sulfamethoxazole (SMX) using ZnO in aquatic systems has been systematically studied by varying initial SMX concentration from 0 to 15 mgL-1, ZnO dosage from 0 to 4 gL-1 and UV light intensity at the light source from 0 to 18 W(m-lamp length)-1 at natural pH. Almost complete degradations of SMX were achieved within 120 min for the initial SMX concentration ≤15 mgL-1 with ZnO dosage of 3 gL-1 and UV light intensity of 18 W(m-lamp length)-1. The photocatalytic degradation process was found to be interacted with the dissolved oxygen (DO) consumption. With oxygen supply through the gas-liquid free-surface, the DO concentration decreased significantly in the initial SMX degradation phase and increased asymptotically to the saturated DO concentration after achieving about 80% SMX degradation. The change in DO concentration was probably controlled by the oxygen consumption in the formation of oxygenated radical intermediates. A novel dynamic kinetic model based on the fundamental reactions of photocatalysis and the formation of oxygenated radical intermediates was developed. In the modeling the dynamic concentration profiles of OH radical and DO are considered. The dynamics of SMX degradation process by ZnO was simulated reasonably by the proposed model.

Changes in HER3 expression profiles between primary and recurrent gynecological cancers.

BACKGROUND: Human epidermal growth factor receptor-3 (HER3) is a member of the epidermal growth factor receptor family of receptor tyrosine kinases, and its overexpression is associated with inferior prognosis in several cancers. However, it is unclear whether HER3 expression status changes in tumor tissue at recurrence. Therefore, this study aimed to evaluate the changes in HER3 expression between primary and recurrent status in gynecological cancers. METHODS: This retrospective study used matched-pair tissues of gynecological cancer patients at initial diagnosis and at recurrence. Immunohistochemical (IHC) scores of 3 + or 2 + were termed "HER3-high", while IHC scores of 1 + or 0 were designated as "HER3-low/zero". RESULTS: A total of 86 patients (40 with ovarian cancers, 32 with endometrial cancers, and 14 with cervical cancers) were included in this study. In ovarian cancer, 67.5% and 80.0% of the patients received a HER3-high at initial and recurrent diagnosis, respectively. The H-score was significantly increased at recurrence (p = 0.004). The proportion of HER3-high endometrial cancer patients increased from 46.9% at initial diagnosis to 68.8% at recurrence, and the H-score tended to increase at recurrence (p = 0.08). The fraction of HER3-high-rated cervical cancer patients remained unchanged at 85.7% both at initial and recurrent diagnosis. The discordance rate of HER3 expression detection in initial and recurrent diagnosis samples was 27.5%, 53.1%, and 14.3% for ovarian, endometrial, and cervical cancers, respectively. Ovarian and endometrial cancers with a HER3-high recurrent score tended to show shorter median survival time than those with a HER3-low/zero recurrent rating. CONCLUSION: Our findings suggest that, in main types of gynecological cancers, the proportion of patients having a HER3-high score increased from initial to recurrent diagnosis.

RNA-binding motifs of hnRNP K are critical for induction of antibody diversification by activation-induced cytidine deaminase.

Activation-induced cytidine deaminase (AID) is the key enzyme for class switch recombination (CSR) and somatic hypermutation (SHM) to generate antibody memory. Previously, heterogeneous nuclear ribonucleoprotein K (hnRNP K) was shown to be required for AID-dependent DNA breaks. Here, we defined the function of major RNA-binding motifs of hnRNP K, GXXGs and RGGs in the K-homology (KH) and the K-protein-interaction (KI) domains, respectively. Mutation of GXXG, RGG, or both impaired CSR, SHM, and cMyc/IgH translocation equally, showing that these motifs were necessary for AID-dependent DNA breaks. AID-hnRNP K interaction is dependent on RNA; hence, mutation of these RNA-binding motifs abolished the interaction with AID, as expected. Some of the polypyrimidine sequence-carrying prototypical hnRNP K-binding RNAs, which participate in DNA breaks or repair bound to hnRNP K in a GXXG and RGG motif-dependent manner. Mutation of the GXXG and RGG motifs decreased nuclear retention of hnRNP K. Together with the previous finding that nuclear localization of AID is necessary for its function, lower nuclear retention of these mutants may worsen their functional deficiency, which is also caused by their decreased RNA-binding capacity. In summary, hnRNP K contributed to AID-dependent DNA breaks with all of its major RNA-binding motifs.

Current status of first-line treatment with pembrolizumab for non-small-cell lung cancer with high PD-L1 expression.

It is not clear whether pembrolizumab monotherapy (MONO) or pembrolizumab plus platinum-based chemotherapy (COMB) should be selected for patients with advanced non-small-cell lung cancer (NSCLC) exhibiting high PD-L1 expression (tumor proportion score ≥ 50%). We performed a retrospective, multicenter study of 300 patients with NSCLC exhibiting high PD-L1 expression who received MONO or COMB as first-line treatment between December 2018 and January 2020. We reviewed the medical records of all consecutive patients with no driver mutations, and assessed the patient characteristics, therapeutic regimens, treatment periods, and adverse events. In total, 166 (55%; median age: 74 years) and 134 (45%; median age: 68 years) patients received MONO and COMB, respectively. Patients were younger and had better performance status (0-1) in the COMB group (p < 0.01). With a median follow-up time of 10.6 (range: 0.1-20.6) months, the median progression-free survival was 7.1 months with MONO and 13.1 months with COMB. The objective response rate was 42.2% with MONO and 67.9% with COMB. With respect to treatment discontinuation, 36 out of 166 (21.7%) and 28 out of 134 (20.1%) patients discontinued MONO and COMB, respectively. In conclusion, COMB may be a promising option for first-line treatment for NSCLC with high PD-L1 expression and good performance status.

Spatial and Quantitative Analysis of Tumor-Associated Macrophages: Intratumoral CD163-/PD-L1+ TAMs as a Marker of Favorable Clinical Outcomes in Triple-Negative Breast Cancer.

Tumor-associated macrophages (TAMs) and abnormalities in cancer cells affect cancer progression and response to therapy. TAMs are a major component of the tumor microenvironment (TME) in breast cancer, with their invasion affecting clinical outcomes. Programmed death-ligand 1 (PD-L1), a target of immune checkpoint inhibitors, acts as a suppressive signal for the surrounding immune system; however, its expression and effect on TAMs and the clinical outcome in breast cancer are unknown. In this study, we used high-throughput multiple immunohistochemistry to spatially and quantitatively analyze TAMs. We subjected 81 breast cancer specimens to immunostaining for CD68, CD163, PD-1, PD-L1, CD20, and pan-CK. In both stromal and intratumoral areas, the triple-negative subtype had significantly more CD68/CD163, CD68/PD-L1, and CD163/PD-L1 double-positive cells than the estrogen receptor (ER)/progesterone receptor (PR) subtype. Interestingly, a higher number of CD68+/PD-L1+/CK-/CD163- TAMs in the intratumoral area was correlated with a favorable recurrence rate (p = 0.048). These findings indicated that the specific subpopulation and localization of TAMs in the TME affect clinical outcomes in breast cancer.

[Determination of Chlorothalonil Metabolite I in Livestock Products by LC-MS/MS].

An analytical method based on LC-MS/MS was developed for the determination of chlorothalonil metabolite I in livestock products. Chlorothalonil metabolite I in livestock products was extracted with acetone. The crude extracts were defatted by acetonitrile and n-hexane partitioning. Cleanup was carried out using a combination of ethylene diamine-N-propyl silylation silica gel (PSA) and silica gel (SI) mini columns with acidic condition. The sample solution was subjected to LC-MS/MS using an external solvent calibration curve. The average recovery (n=5) of chlorothalonil metabolite I from five types of livestock products (cattle muscle, cattle fat, cattle liver, milk and egg) spike at the maximum residue limits (MRLs) or at a uniform limit of 0.01 mg/kg was 97.1-102.9%, with a relative standard deviation of 1.4-6.8%. The limit of quantitation of the developed method was calculated to be 0.01 mg/kg.

MK-6, a novel not-α IL-2, elicits a potent antitumor activity by improving the effector to regulatory T cell balance.

IL-2 is a pleiotropic cytokine that regulates immune cell homeostasis. Its immunomodulatory function has been used clinically as an active immunotherapy agent for metastatic cancers. However, severe adverse effects, including the vascular leak syndrome and the preferential stimulation of anti-immunogenic Treg rather than effector T cells, have been obstacles. We newly designed a mutein IL-2, Mutakine-6 (MK-6), with reduced IL-2Rα-binding capability. MK-6 induced comparable cell growth potential toward IL-2Rßγ-positive T cells but was far less efficient in in vitro Treg proliferation and STAT5 activation. Unlike IL-2, in vivo administration of MK-6 produced minimal adverse effects. Using CT26 and B16F10-syngeneic tumor models, we found MK-6 was highly efficacious on tumor regression. Serum albumin conjugation to MK-6 prolonged in vivo half-life and accumulated in CT26 tumors, showing enhanced antitumor effect. Tumor-infiltrating leukocytes analysis revealed that albumin-fused MK-6 increased the ratio of effector CD8+ T cells to CD4+ Treg cells. These results demonstrated that MK-6 is an efficient immunomodulator potentially used for improved immunotherapy with decreased adverse effects and attenuated Treg stimulation.

[Determination of Asulam in Livestock Products by LC-MS/MS].

An analytical method based on LC-MS/MS was developed for the determination of asulam in livestock products. Asulam in livestock products was extracted with acetone. The crude extracts were defatted by acetonitrile and n-hexane partitioning. Cleanup was carried out using a combination of ethylene diamine-N-propyl silylation silica gel (PSA) and octadecyl silylated silica gel (C18) mini columns with acidic condition. The sample solution was subjected to LC-MS/MS using an external solvent calibration curve. The average recovery (n=5) of Asulam from four types of livestock products (bovine muscle, bovine fat, bovine liver and milk) spike at the maximum residue limits (MRLs) or at a uniform limit of 0.01 mg/kg was 92.7-98.7%, with a relative standard deviation of 3.1-11.6%. The limit of quantitation of the developed method was calculated to be 0.01 mg/kg.

Apurinic/apyrimidinic endonuclease 1 (APE1) is dispensable for activation-induced cytidine deaminase (AID)-dependent somatic hypermutation in the immunoglobulin gene.

Activation-induced cytidine deaminase (AID) initiates DNA breakage in the variable (V) and switch (S) regions of the immunoglobulin gene, which results in somatic hypermutation (SHM) and class switch recombination (CSR), respectively. Apurinic/apyrimidinic endonuclease 1 (APE1) has been shown to be important for CSR, and is supposed to cleave at abasic sites when AID-dependently deaminated cytidine is removed by uracil DNA glycosylase. However, APE1 is unexpectedly dispensable for SHM in the S region and translocation between immunoglobulin heavy chain (IgH) and c-myc genes in the mouse B lymphoma cell line, CH12F3-2A. This suggested that APE1 is not involved in AID-dependent DNA breakage, but rather, in DNA repair. In order to investigate detailed molecular mechanisms underlying APE1's involvement in CSR and SHM, we measured apurinic/apyrimidinic (AP) sites via aldehyde reactive probe labeling. Results indicated that the frequencies of AP sites in the S regions were not different between APE1-/-/-CH12F3-2A and wild-type CH12F3-2A cells. To carry out similar experiments in SHM of the V region, we generated an APE1 knockout (APE1-/-) human Burkitt's lymphoma cell line, and compared SHM between APE1-proficient and -deficient BL2 lymphoma cells. SHM frequencies in the V regions of APE1-/-BL2 and APE1-proficient cells were also similar. Taken together, we showed that AID does not induce AP sites in the S region of the IgH gene, and that APE1 is not necessary for SHM in the V and S regions; however, it is required for DNA repair following DNA breakage in CSR.

Exercise echocardiography demonstrates potential myocardial damage in patients with repaired tetralogy of Fallot using layer-specific strain analysis.

INTRODUCTION: Exercise stress echocardiography and layer-specific strains are emerging as important tools for cardiac assessment. This study was aimed to evaluate layer-specific strains and torsion parameters during exercise in order to investigate the characteristics of cardiac dysfunction in patients with repaired tetralogy of Fallot and to detect subclinical left ventricular dysfunction. MATERIALS AND METHODS: Thirteen patients with repaired tetralogy of Fallot (median age, 17.3 [interquartile range, 14.5-22.9] years; 6 males) and 13 controls (median age, 28.5 [interquartile range, 27.6-31.6] years; 13 males) underwent echocardiography at rest and during supine exercise. Layer-specific longitudinal strain and circumferential strain of three myocardial layers (endocardium, midmyocardium, and epicardium), torsion, and untwisting rate were measured using two-dimensional speckle-tracking echocardiography. RESULTS: Peak endocardial papillary circumferential strain (-21.1 ± 2.6% vs. -25.8 ± 3.8%, p = 0.007), midmyocardial apical circumferential strain (-11.1 ± 4.0% vs. -15.6 ± 3.2%, p = 0.001), epicardial apical circumferential strain (-11.1 ± 4.0% vs. -15.6 ± 3.2%, p = 0.021), and torsion (8.9 ± 6.0 vs. 14.9 ± 4.8 degree, p = 0.021) were significantly lower in the repaired tetralogy of Fallot group than in the control group during exercise, though no significant difference was found between patients and controls at rest. CONCLUSIONS: Analysis of layer-specific strains and torsion parameters during exercise could detect subclinical left ventricular dysfunction in patients with repaired tetralogy of Fallot, which might reflect potential myocardial damage, at a stage where these parameters have normal values at rest. This finding provides new insight into the mechanisms of cardiac dysfunction in patients with repaired tetralogy of Fallot.

Immunohistochemical evaluation of tumor budding for stratifying T1 colorectal cancer: optimal cut-off value and a novel computer-assisted semiautomatic method.

High-grade tumor budding is an adverse prognostic factor for submucosal invasive (T1) colorectal cancer used to predict the risk for lymph node metastasis in endoscopically resected specimens. Cytokeratin immunohistochemistry is a potential option for evaluating tumor budding. The optimal cut-off value between low- and high-grade budding has not yet been determined, however, and the high inter-observer variability in selecting budding foci remains problematic. We explored the optimal cut-off value for predicting lymph node metastasis using cytokeratin immunohistochemistry, and developed a novel computer-assisted semiautomatic quantification method to reduce inter-observer variability. A retrospective single-institution study of 463 T1 colorectal cancer cases was conducted. Cases were split into derivation and validation datasets. Tumor budding foci were counted manually and semiautomatically using Image J software on cytokeratin immunohistochemistry-stained specimens. We determined the cut-off values and compared inter-observer variability among pathologists between the two methods. Univariate and multivariate analyses of the derivation dataset were performed to select the risk factors for lymph node metastasis. Predictive simulation for the validation dataset was conducted. The optimal cut-off values for the manual and semiautomatic methods were ≥10 and ≥12, respectively. For both methods, multivariate analyses revealed that venous invasion, lymphatic invasion, and high-grade tumor budding were independent risk factors for lymph node metastasis. The semiautomatic method provided significantly better inter-observer agreement. The predictive and observed lymph node metastasis frequencies were highly correlated in the validation dataset.

Development of suction force during early diastole from the left atrium to the left ventricle in infants, children, and adolescents.

Although the suction force that moves blood into the left ventricle during early diastole is thought to play an important role in diastolic function, there have been a few studies of this phenomenon in normal children. Suction force is measured as the intraventricular pressure difference (IVPD) and intraventricular pressure gradient (IVPG), which is calculated as IVPD divided by left ventricular length. The purpose of this study was to determine the suction force in infants, children, and adolescents using IVPD and IVPG. We included 120 normal children categorized into five groups based on age: G1 (0-2 years), G2 (3-5 years), G3 (6-8 years), G4 (9-11 years), and G5 (12-16 years). The total, basal, and mid-apical IVPD and IVPG were calculated using color M-mode Doppler imaging of the mitral valve inflow using the Euler equation. The total IVPD increased with age from G1 to G5 (1.75 + 0.51 vs. 2.95 + 0.72 mmHg, respectively; p < 0.001), due to an increase in mid-apical IVPD with constant basal IVPD. Although total IVPG was constant, mid-apical IVPG was larger in G5 than in G1 (0.21 + 0.06 vs. 0.16 + 0.07 mmHg/cm, respectively; p = 0.006). Total, basal, and mid-apical IVPDs were significantly correlated with age and the parameters of heart size and mitral annular e'. Mid-apical IVPG correlated with age and e' positively, but basal IVPG did with age negatively and did not with e'. The suction force increased at the mid-apical segment, correlating with increasing heart size and developing left ventricular relaxation, even after adjustment for left ventricular length.

New insight into the intraventricular pressure gradient as a sensitive indicator of diastolic cardiac dysfunction in patients with childhood cancer after anthracycline therapy.

Cardiac dysfunction due to cardiotoxicity from anthracycline chemotherapy is a leading cause of morbidity and mortality in survivors of childhood cancer. The intraventricular pressure gradient (IVPG) of the left ventricle (LV) is the suction force of blood from the left atrium to the LV apex during early diastole and is a sensitive indicator of diastolic function. We assessed IVPG as a new indicator of the cardiac dysfunction in survivors of childhood cancer after anthracycline therapy. We performed a prospective echocardiographic study on 40 survivors of childhood cancer aged 6-26 years who received anthracycline therapy (group A) and 53 similar-age normal controls (group N). The subjects were divided into the younger groups, N1 and A1 (age < 16 years); older groups, N2 and A2 (age ≥ 16 years). IVPG was calculated using color M-mode Doppler imaging of the mitral inflow using Euler's equation. Total IVPG was divided into the basal and mid-to-apical IVPG to demonstrate more clearly the mechanisms of the LV diastolic suction force. The total anthracycline dose was 16.2-600.0 mg/m2 (median 143.5 mg/m2). Total IVPG significantly decreased in group A2 compared with that in group N2 (0.39 ± 0.07 vs. 0.29 ± 0.11 mmHg/cm; p = 0.010). The mid-to-apical IVPG significantly decreased in groups A1 and A2 compared with that in groups N1 and N2, respectively (N1 vs. A1: 0.20 ± 0.05 vs. 0.16 ± 0.05 mmHg/cm, p = 0.036; N2 vs. A2: 0.21 ± 0.06 vs. 0.14 ± 0.06 mmHg/cm, p = 0.001). Basal IVPG, E wave, and E/e' were not significantly different between patients and normal controls. The total and mid-to-apical IVPG, especially mid-to-apical IVPG, could be sensitive new indicators in survivors of childhood cancer after anthracycline therapy.

Depletion of recombination-specific cofactors by the C-terminal mutant of the activation-induced cytidine deaminase causes the dominant negative effect on class switch recombination.

Activation-induced cytidine deaminase (AID) is essential for class-switch recombination (CSR) and somatic hypermutation (SHM) of immunoglobulin genes. Studies on in vitro mutagenized AID as well as its mutations in human patients with hyper-IgM (HIGM)-syndrome type II revealed that C-terminal AID mutations were defective in CSR whereas their DNA cleavage and SHM activities remained intact. The C-terminal mutants of AID were speculated to exert the dominant negative effect on wild-type (WT) AID whereas its mechanism remains unknown. We generated the JP41 (R190X) mutation in one allele and a null mutation on the other allele in a mouse B cell line (CH12F3-2A) using CRISPR/Cas9 genome-editing tools and studied the effect of JP41 expression on the function of exogenously introduced WT AID fused with estrogen receptor (AIDER) in AIDJP41/∆/AIDER CH12F3-2A cells. We found that JP41 expression strongly suppressed not only CSR but also Igh/c-Myc chromosomal translocations by AIDER. We showed that the dominant negative effect is not evident at the DNA cleavage step but obvious at both deletional and inversional recombination steps. We also confirmed the dominant negative effect of other C-terminal mutants, JP8Bdel (R183X) and P20 (34-aa insertion at residue 182) in AID-deficient spleen B cells. Finally, we showed that the expression of JP41 reduced the binding of AIDER with its cofactors (hnRNP L, SERBP1 and hnRNP U). Together, these data indicate that dominant negative effect of JP41 on CSR is likely due to the depletion of the CSR-specific RNA-binding proteins from WT AID.

In-Depth Insight Into the Mechanisms of Cardiac Dysfunction in Patients With Childhood Cancer After Anthracycline Treatment Using Layer-Specific Strain Analysis.

BACKGROUND: Anthracycline cardiotoxicity affects clinical outcomes, and its early detection using methods that rely on conventional echocardiography, such as left ventricular ejection fraction (LVEF) is difficult. This study aimed to evaluate the characteristics and the differences in cardiac dysfunction among childhood cancer survivors in 3 age groups using layer-specific strain analysis in a wide age range.Methods and Results:The 56 patients (median age: 15 [range: 6.8-40.2] years) who had been treated with anthracycline for childhood cancer were divided into 3 age groups (C1: 6-12 years, C2: 13-19 years, C3: 20-40 years) after anthracycline treatment, and 72 controls of similar ages were divided into 3 corresponding groups (N1, N2, and N3). Layer-specific longitudinal strain (LS) and circumferential strain (CS) of 3 myocardial layers (endocardium, midmyocardium, and epicardium) were determined using echocardiography. Myocardial damage had not occurred yet in C1. Endocardial CS at the basal level was less in C2 than in N2. Endocardial CS at all levels and midmyocardial CS at the basal and papillary levels were lower in C3 than in N3. LVEF and LS were not significantly different between patients and controls. CONCLUSIONS: Among survivors of childhood cancer, impaired myocardial deformation starts in adolescence and extends from the endocardium towards the epicardium and from the base towards the apex with age. These findings are a novel insight into the time course of anthracycline cardiotoxicity.