Renin-angiotensin system inhibitors for patients with mild or moderate chronic kidney disease and heart failure with mildly reduced or preserved ejection fraction.

BACKGROUND: Renin-angiotensin system inhibitors (RASI) reduce adverse cardiovascular events in patients with heart failure (HF) with left ventricular ejection fraction (LVEF) ≤40% and mild or moderate chronic kidney disease (CKD). However, RASI administration rate and its association with long-term outcomes in patients with CKD complicated by HF with LVEF >40% remain unclear. METHODS: We analyzed 1923 consecutive patients with LVEF >40% registered within the multicenter database for hospitalized HF. We assessed RASI administration rate and its association with all-cause mortality among patients with mild or moderate CKD (estimated glomerular filtration rate [eGFR]: 30-60 mL/min/1.73 m2). Exploratory subgroups included patients grouped by age (<80, ≥80 years), sex, previous HF hospitalization, B-type natriuretic peptide (higher, lower than median), eGFR (30-44, 45-59 mL/min/1.73 m2), systolic blood pressure (<120, ≥120 mmHg), LVEF (41-49, ≥50%), and mineralocorticoid receptor antagonists (MRA) use. RESULTS: Among patients with LVEF >40%, 980 (51.0%) had mild or moderate CKD (age: 81 [74-86] years; male, 52.6%; hypertension, 69.7%; diabetes, 25.9%), and 370 (37.8%) did not receive RASI. RASI use was associated with hypertension, absence of atrial fibrillation, and MRA use. After multivariable adjustments, RASI use was independently associated with lower all-cause mortality over a 2-year median follow-up (hazard ratio: 0.58, 95% confidence interval: 0.43-0.79, P = 0.001), and the mortality rate difference was predominantly due to cardiac death, consistent in all subgroups. CONCLUSIONS: Approximately one-third of HF patients with mild or moderate CKD and LVEF >40% were discharged without RASI administration and demonstrated relatively guarded outcomes.

Phenomapping in patients experiencing worsening renal function during hospitalization for acute heart failure.

AIMS: The impact of worsening renal function (WRF) on the prognosis of patients with acute heart failure (AHF) remains controversial. We aimed to identify phenotypically distinct subgroups among individuals with both AHF and WRF using cluster analysis. METHODS AND RESULTS: Overall, the data of 483 patients with both AHF and WRF enrolled in the West Tokyo Heart Failure Registry were analysed. Using cluster analysis, we identified three phenotypically distinct subgroups (phenogroups 1, 2, and 3). We assessed the impact of WRF on the prognosis of each phenogroup by comparing the incidence of composite endpoints, including all-cause death and re-hospitalization due to heart failure, with those of a propensity score-matched, non-WRF control group. Participants in phenogroup 1 (N = 122) were the youngest (69.3 ± 13.7 years), had relatively preserved estimated glomerular filtration rate (eGFR, 70.0 ± 27.7 mL/min/1.73 m2 ), and reduced left ventricular ejection fraction (LVEF) (41.8 ± 13.7%). Conversely, participants in phenogroup 3 (N = 122) were the oldest (81.7 ± 8.5 years), had the worst eGFR (33.0 ± 20.9 mL/min/1.73 m2 ), and had preserved LVEF (51.7 ± 14.8%). The characteristics of the participants in phenogroup 2 (N = 239) were between those of phenogroups 1 and 3. The propensity score matching analysis showed that WRF was associated with a higher incidence of composite endpoints in phenogroup 1, whereas this association was not observed in phenogroups 2 and 3. CONCLUSIONS: Using cluster analysis, we revealed three phenotypically distinct subgroups of patients with both AHF and WRF. WRF was associated with worse clinical outcomes in the subgroup of younger patients with reduced LVEF and preserved renal function.

Moderate-to-severe obstructive sleep apnea is associated with subclinical myocardial injury and impaired hemodynamics in pulmonary hypertension patients.

BACKGROUND: The clinical significance of obstructive sleep apnea (OSA) in pulmonary hypertension (PH) patients remains unclear. We investigated the hemodynamics and serum troponin T concentrations associated with OSA in PH patients. METHODS: Cross-sectional study was performed on data from 97 clinically stable PH patients. Using overnight sleep study, we evaluated apnea-hypopnea index (AHI) and divided patients into two groups: none-to-mild OSA (AHI < 15/h, N = 81) and moderate-to-severe OSA (AHI ≥ 15/h, N = 16). Clinical, hemodynamic, and laboratory data were compared with OSA severity. RESULTS: Moderate-to-severe OSA patients had higher pulmonary vascular resistance (PVR; 6.5 [5.7-12.9] vs 4.4 [2.9-6.4] Wood units, p = 0.001) and mean pulmonary artery pressure (mPAP; 37 [30-49] vs 30 [22-37] mmHg, p = 0.045), and a lower cardiac index (2.2 [1.6-2.6] vs 2.8 [2.3-3.5] L/min/m2, p = 0.001) than those without. There was no association between plasma B-type natriuretic peptide (BNP) or serum C-reactive protein levels and OSA. However, high-sensitivity troponin T (hs-TnT) level was significantly higher in moderate-to-severe OSA patients (13 [8-18] vs 6 [4-10] ng/L, p <0.001). The hs-TnT level positively correlated with the plasma BNP level, mPAP, PVR, AHI, obstructive apnea index, and 6-min walking distance. After adjustment for age, estimated glomerular filtration rate, hypertension, smoking, and plasma BNP level, moderate-to-severe OSA was an independent factor for determining the plasma level of log hs-TnT level (ß = 0.419, 95% confidence interval 0.119-0.718, p = 0.007). CONCLUSIONS: Moderate-to-severe OSA is associated with impaired hemodynamics and subclinical myocardial damage in PH patients. Thus, OSA-related myocardial injury may play a role in hemodynamic destabilization with its associated poor prognosis.

H1foo Has a Pivotal Role in Qualifying Induced Pluripotent Stem Cells.

Embryonic stem cells (ESCs) are a hallmark of ideal pluripotent stem cells. Epigenetic reprogramming of induced pluripotent stem cells (iPSCs) has not been fully accomplished. iPSC generation is similar to somatic cell nuclear transfer (SCNT) in oocytes, and this procedure can be used to generate ESCs (SCNT-ESCs), which suggests the contribution of oocyte-specific constituents. Here, we show that the mammalian oocyte-specific linker histone H1foo has beneficial effects on iPSC generation. Induction of H1foo with Oct4, Sox2, and Klf4 significantly enhanced the efficiency of iPSC generation. H1foo promoted in vitro differentiation characteristics with low heterogeneity in iPSCs. H1foo enhanced the generation of germline-competent chimeric mice from iPSCs in a manner similar to that for ESCs. These findings indicate that H1foo contributes to the generation of higher-quality iPSCs.

Evaluation of [(11)C]oseltamivir uptake into the brain during immune activation by systemic polyinosine-polycytidylic acid injection: a quantitative PET study using juvenile monkey models of viral infection.

BACKGROUND: Abnormal behaviors of young patients after taking the anti-influenza agent oseltamivir (Tamiflu®, F. Hoffmann-La Roche, Ltd., Basel, Switzerland) have been suspected as neuropsychiatric adverse events (NPAEs). Immune response to viral infection is suspected to cause elevation of drug concentration in the brain of adolescents. In the present study, the effect of innate immune activation on the brain uptake of [(11)C]oseltamivir was quantitatively evaluated in juvenile monkeys. METHODS: Three 2-year-old monkeys underwent positron emission tomography (PET) scans at baseline and immune-activated conditions. Both scans were conducted under pre-dosing of clinically relevant oseltamivir. The immune activation condition was induced by the intravenous administration of polyinosine-polycytidylic acid (poly I:C). Dynamic [(11)C]oseltamivir PET scan and serial arterial blood sampling were performed to obtain [(11)C]oseltamivir kinetics. Brain uptake of [(11)C]oseltamivr was evaluated by its normalized brain concentration, brain-to-plasma concentration ratio, and plasma-to-brain transfer rate. Plasma pro-inflammatory cytokine levels were also measured. RESULTS: Plasma interleukin-6 was elevated after intravenous administration of poly I:C in all monkeys. Brain radioactivity was uniform both at baseline and under poly I:C treatment. The mean brain concentrations of [(11)C]oseltamivir were 0.0033 and 0.0035% ID/cm(3) × kg, the mean brain-to-plasma concentration ratios were 0.58 and 0.65, and the plasma-to-brain transfer rates were 0.0047 and 0.0051 mL/min/cm(3) for baseline and poly I:C treatment, respectively. Although these parameters were slightly changed by immune activation, the change was not notable. CONCLUSIONS: The brain uptake of [(11)C]oseltamivir was unchanged by poly I:C treatment in juvenile monkeys. This study demonstrated that the innate immune response similar to the immune activation of influenza would not notably change the brain concentration of oseltamivir in juvenile monkeys.

Molecular imaging of ectopic metabotropic glutamate 1 receptor in melanoma with a positron emission tomography radioprobe (18) F-FITM.

Oncoimaging using positron emission tomography (PET) with a specific radioprobe would facilitate individualized cancer management. Evidence indicates that ectopically expressed metabotropic glutamate 1 (mGlu1) receptor independently induces melanocyte carcinogenesis, and it is therefore becoming an important target for personalized diagnosis and treatment strategies for melanomas. Here, we report the development of an oncoprotein-based PET imaging platform in melanomas for noninvasive visualization and quantification of mGlu1 with a novel mGlu1-specific radioprobe, 4-(18)F-fluoro-N-[4-[6-(isopropyl amino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-N-methylbenzamide ((18)F-FITM). (18)F-FITM shows excellent pharmacokinetics, namely the dense and specific accumulation in mGlu1-positive melanomas versus mGlu1-negative hepatoma and normal tissues. Furthermore, the accumulation levels of radioactivity corresponded to the extent of tumor and to levels of mGlu1 protein expression in melanomas and melanoma metastasis. The (18)F-FITM PET imaging platform, as a noninvasive personalized diagnostic tool, is expected to open a new avenue for defining individualized therapeutic strategies, clinical trials, patient management and understanding mGlu1-triggered oncologic events in melanomas.

Generation and characterization of functional cardiomyocytes derived from human T cell-derived induced pluripotent stem cells.

Induced pluripotent stem cells (iPSCs) have been proposed as novel cell sources for genetic disease models and revolutionary clinical therapies. Accordingly, human iPSC-derived cardiomyocytes are potential cell sources for cardiomyocyte transplantation therapy. We previously developed a novel generation method for human peripheral T cell-derived iPSCs (TiPSCs) that uses a minimally invasive approach to obtain patient cells. However, it remained unknown whether TiPSCs with genomic rearrangements in the T cell receptor (TCR) gene could differentiate into functional cardiomyocyte in vitro. To address this issue, we investigated the morphology, gene expression pattern, and electrophysiological properties of TiPSC-derived cardiomyocytes differentiated by floating culture. RT-PCR analysis and immunohistochemistry showed that the TiPSC-derived cardiomyocytes properly express cardiomyocyte markers and ion channels, and show the typical cardiomyocyte morphology. Multiple electrode arrays with application of ion channel inhibitors also revealed normal electrophysiological responses in the TiPSC-derived cardiomyocytes in terms of beating rate and the field potential waveform. In this report, we showed that TiPSCs successfully differentiated into cardiomyocytes with morphology, gene expression patterns, and electrophysiological features typical of native cardiomyocytes. TiPSCs-derived cardiomyocytes obtained from patients by a minimally invasive technique could therefore become disease models for understanding the mechanisms of cardiac disease and cell sources for revolutionary cardiomyocyte therapies.

Radiosynthesis of [13N]dantrolene, a positron emission tomography probe for breast cancer resistant protein, using no-carrier-added [13N]ammonia.

Dantrolene (1) is a substrate for breast cancer resistant protein, which is widely distributed in the blood-brain-barrier, intestine, gall bladder, and liver. PET study with 1 labeled with a positron emitter can be used to visualize BCRP and to elucidate the effect of BCRP on the pharmacokinetics of drugs. The objective of this study was to label 1 using nitrogen-13 ((13)N, a positron emitter; half-life: 9.9min). Using no-carrier-added [(13)N]NH(3) as the labeling agent, we synthesized [(13)N]dantrolene ([(13)N]1) for the first time. The reaction of carbomyl chloride 2b with [(13)N]NH(3) gave an unsymmetrical urea [(13)N]3, followed by cyclization of [(13)N]3 to afford [(13)N]1. Due to its instability, 2b was prepared in situ by treating amine 5 with triphosgene in a ratio of 4 to 1 and used for subsequent [(13)N]ammonolysis without purification.

Evaluation of limiting brain penetration related to P-glycoprotein and breast cancer resistance protein using [(11)C]GF120918 by PET in mice.

PURPOSE: GF120918 has a high inhibitory effect on P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). We developed [(11)C]GF120918 as a positron emission tomography (PET) probe to assess if dual modulation of P-gp and BCRP is useful to evaluate brain penetration. PROCEDURES: PET studies using [(11)C]GF120918 were conducted on P-gp and/or Bcrp knockout mice as well as wild-type mice. RESULTS: In PET studies, the AUC(brain) ([0-60 min]) and K (1) value in P-gp/Bcrp knockout mice were nine- and 26-fold higher than that in wild-type mice, respectively. These results suggest that brain penetration of [(11)C]GF120918 is related to modulation of P-gp and BCRP and is limited by two transporters working together. CONCLUSIONS: PET using [(11)C]GF120918 may be useful for evaluating the function of P-gp and BCRP. PET using P-gp/Bcrp knockout mice may be an effective method to understand the overall contributions the functions of P-gp and BCRP.

Ethylene glycol monomethyl ether-induced toxicity is mediated through the inhibition of flavoprotein dehydrogenase enzyme family.

Ethylene glycol monomethyl ether (EGME) is a widely used industrial solvent known to cause adverse effects to human and other mammals. Organs with high metabolism and rapid cell division, such as testes, are especially sensitive to its actions. In order to gain mechanistic understanding of EGME-induced toxicity, an untargeted metabolomic analysis was performed in rats. Male rats were administrated with EGME at 30 and 100 mg/kg/day. At days 1, 4, and 14, serum, urine, liver, and testes were collected for analysis. Testicular injury was observed at day 14 of the 100 mg/kg/day group only. Nearly 1900 metabolites across the four matrices were profiled using liquid chromatography-mass spectrometry/mass spectrometry and gas chromatography-mass spectrometry. Statistical analysis indicated that the most significant metabolic perturbations initiated from the early time points by EGME were the inhibition of choline oxidation, branched-chain amino acid catabolism, and fatty acid ß-oxidation pathways, leading to the accumulation of sarcosine, dimethylglycine, and various carnitine- and glycine-conjugated metabolites. Pathway mapping of these altered metabolites revealed that all the disrupted steps were catalyzed by enzymes in the primary flavoprotein dehydrogenase family, suggesting that inhibition of flavoprotein dehydrogenase-catalyzed reactions may represent the mode of action for EGME-induced toxicity. Similar urinary and serum metabolite signatures are known to be the hallmarks of multiple acyl-coenzyme A dehydrogenase deficiency in humans, a genetic disorder because of defects in primary flavoprotein dehydrogenase reactions. We postulate that disruption of key biochemical pathways utilizing flavoprotein dehydrogenases in conjugation with downstream metabolic perturbations collectively result in the EGME-induced tissue damage.

Synthesis and evaluation of [11C]XR9576 to assess the function of drug efflux transporters using PET.

OBJECTIVE: XR9576 (tariquidar) is an anthranilic acid derivative and potent P-glycoprotein (P-gp) inhibitor. XR9576 has undergone phase I and II studies as combined chemotherapy against cancer. XR9576 has been developed as a useful therapeutic agent but not as a PET probe. We therefore developed [(11)C]XR9576 as a PET probe and assessed whether PET studies using [(11)C]XR9576 are a promising approach to assess P-gp function primarily. METHODS: We synthesized [(11)C]XR9576 by methylation of 7-O-desmethyl XR9576 with [(11)C]methyl iodide. In in vivo tissue distribution, the effects of co-injection with XR9576 on the uptake of [(11)C]XR9576 in mice were investigated. PET studies using [(11)C]XR9576 were performed in P-gp and/or Bcrp knockout mice as well as in wild-type mice. Metabolites of [(11)C]XR9576 were measured in the brain and plasma of mice. RESULTS: [(11)C]XR9576 was successfully synthesized with suitable radioactivity for injection as well as appropriate radiochemical purity and stability. In in vivo tissue distribution, the brain uptake of [(11)C]XR9576 significantly increased about tenfold of control on co-injection with >10 mg/kg of XR9576. In PET studies, the AUC(brain) ([0-60 min]) in P-gp and P-gp/Bcrp knockout mice was 2- and 11-fold higher than that in wild-type mice. [(11)C]XR9576 showed a high metabolic stability (>90% unchanged form) in the brain and plasma of mice 30 min after injection. These results suggest that a tracer amount of [(11)C]XR9576 behave as the P-gp and Bcrp substrate, and the increased brain uptake or AUC(brain) of [(11)C]XR9576 correlates with P-gp and Bcrp functions. CONCLUSIONS: PET studies using [(11)C]XR9576 may be a promising approach for evaluating deficiency of the function of drug efflux transporters targeting intracranial diseases and tumors.

In vivo evaluation of limiting brain penetration of probes for α(2C)-adrenoceptor using small-animal positron emission tomography.

To evaluate in vivo brain penetration of α(2C)-adrenoceptor (α(2C)-AR) antagonists as a therapeutic agent, we synthesized two new (11)C-labeled selective α(2C)-AR antagonists 4-(6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolin-2-yl)methyl-2-aryl-7-methoxybenzofuran ([(11)C]MBF) and acridin-9-yl-[4-(4-methylpiperazin-1-yl)phenyl]amine ([(11)C]JP-1302) as α(2C)-AR-selective positron emission tomography (PET) probes. The radiochemical yield, specific activity, and radiochemical purity of these probes was appropriate for injection. To evaluate whether the brain penetration of these probes is related to the function of two major drug efflux transporters, P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), we performed PET studies using wild-type and P-gp/Bcrp knockout mice. In wild-type mice, the radioactivity level after injection with [(11)C]MBF initially increased and effluxed immediately from the brain, whereas that with [(11)C]JP-1302 was distributed throughout the brain. However, the regional distribution of radioactivity after injection with [(11)C]JP-1302 in the brain was different from that of α(2C)-ARs. In P-gp/Bcrp knockout mice, uptake of [(11)C]MBF was approximately 3.7-fold higher and that of [(11)C]JP-1302 was approximately 1.6-fold higher than those in wild-type mice. These results indicate that brain penetration of the two PET probes was affected by modulation of P-gp and Bcrp functions.

Imaging of peripheral-type benzodiazepine receptor in tumor: in vitro binding and in vivo biodistribution of N-benzyl-N-[(11)C]methyl-2-(7-methyl-8-oxo-2-phenyl-7,8-dihydro-9H-purin-9-yl)acetamide.

INTRODUCTION: The aim of this study was to evaluate N-benzyl-N-[(11)C]methyl-2-(7-methyl-8-oxo-2-phenyl-7,8-dihydro-9H-purin-9-yl)acetamide ([(11)C]DAC) as a novel peripheral-type benzodiazepine receptor (PBR) ligand for tumor imaging. METHODS: [(11)C]DAC was synthesized by the reaction of a desmethyl precursor with [(11)C]CH(3)I. In vitro uptake of [(11)C]DAC was examined in PBR-expressing C6 glioma and intact murine fibrosarcoma (NFSa) cells. In vivo distribution of [(11)C]DAC was determined using NFSa-bearing mice and small-animal positron emission tomography (PET). RESULTS: [(11)C]DAC showed specific binding to PBR in C6 glioma cells, a standard cell line with high PBR expression. Specific binding of [(11)C]DAC was also confirmed in NFSa cells, a target tumor cell line in this study. Results of PET experiments using NFSa-bearing mice, showed that [(11)C]DAC was taken up specifically into the tumor, and pretreatment with PK11195 abolished the uptake. CONCLUSIONS: [(11)C]DAC was taken up into PBR-expressing NFSa. [(11)C]DAC is a promising PET ligand that can be used for imaging PBR in tumor-bearing mice.

Noninvasive and quantitative assessment of the function of multidrug resistance-associated protein 1 in the living brain.

Multidrug resistance-associated protein 1 (MRP1) acts as a defense mechanism by pumping xenobiotics and endogenous metabolites out of the brain. The currently available techniques for studying brain-to-blood efflux have significant limitations related to either their invasiveness or the qualitative assessment. Here, we describe an in vivo method, which overcomes these limitations for assessing MRP1 function, using positron emission tomography (PET) and a PET probe. 6-Bromo-7-[(11)C]methylpurine was designed to readily enter the brain after intravenous administration and to be efficiently converted to its glutathione conjugate (MRP1 substrate) in situ. Dynamic PET scan provided the brain time-activity curve after injection of 6-bromo-7-[(11)C]methylpurine into mice. The efflux rate of the substrate was kinetically estimated to be 1.4 h(-1) with high precision. Moreover, knockout of Mrp1 gene caused approximately a 90% reduction of the efflux rate, compared with wild-type mice. In conclusion, our method allows noninvasive and quantitative assessment for MRP1 function in the living brain.

How to introduce radioactive chlorine into a benzene ring using [*Cl]Cl-?

The aim of this study was how to introduce radioactive chlorine (*Cl) isotope into a benzene ring to afford *Cl-labeled chlorobenzene ([*Cl]1). Using tributylphenylstannyl compound (2) as a starting material, we determined two routes for introducing *Cl into the benzene ring: reaction of [*Cl]Cl(-) with 2 in the presence of chloramine-T and nucleophilic reaction of [*Cl]Cl(-) with diphenyliodonium tosylate (3). The two routes provide suitable tools to prepare [*Cl]1 without electron-abstracting group in the benzene ring.