Tetsuo Minamino

Novel Synthesized Radical-Containing Nanoparticles Limit Infarct Size Following Ischemia and Reperfusion in Canine Hearts

PurposeAlthough nitroxyl radicals such as 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) scavenge free radicals, their short half-life and considerable side effects such as systemic hypotension and bradycardia have limited their clinical application. Since a radical-containing nanoparticle (RNP) delivers nitroxyl radicals with a prolonged half-life specific to ischemic hearts, we investigated whether RNPs reduce infarct size without the occurrence of substantial side effects and whether nitric oxide (NO) contributes to the cardioprotective effects of RNPs.MethodsThe left anterior descending coronary arteries of dogs were occluded for 90xa0min, followed by reperfusion for 6xa0h. Either RNPs, micelles (not containing TEMPO) (control), or 4-hydroxy-TEMPO (TEMPOL) was injected into a systemic vein for 5xa0min before reperfusion. We evaluated the infarct size, myocardial apoptosis, plasma NO levels in coronary venous blood, and the RNP spectra using an electron paramagnetic resonance assay.ResultsRNPs reduced infarct size compared with the control group and TEMPOL group (19.5xa0±xa03.3 vs. 42.2xa0±xa03.7 vs. 30.2xa0±xa03.4%). RNPs also reduced myocardial apoptosis compared with the control and TEMPOL group. Coronary venous NO levels increased in the RNP group.ConclusionsIn conclusion, the administration of 2,2,6,6-tetramethylpiperidine-1-oxyl as a RNP exerted cardioprotective effects against ischemia and reperfusion injury in canine hearts without exerting unfavorable hemodynamic effects. RNPs may represent a promising new therapy for patients with acute myocardial infarction.

Increase in tumor suppressor Arf compensates gene dysregulation in in vitro aged adipocytes

Deterioration of adipocyte function due to increased oxidative stress predisposes patients to metabolic disorders in advanced age. However, the roles of tumor suppressors in such conditions remain largely unknown. Therefore, we aimed to address their dynamics in aged adipocytes using a long-term culture model. We compared 3T3-L1 adipocytes at 17–19xa0days (long-term) with those at 8–10xa0days (short-term) after initiation of adipogenic induction for mimicking ‘aged’ and ‘young’ adipocytes, respectively. H2O2 release and dihydroethidium (DHE) staining was increased, while superoxide dismutase (SOD) activity was reduced in long-term cultured adipocytes, which is suggestive of enhanced oxidative stress in this group. Moreover, qRT-PCR revealed increased mRNAs of Nox4 (a subunit of NADPH oxidase complex), Ccl2 (a proinflammatory chemokine) and Il6 [a marker of senescence-associated secretory phenotype (SASP)] along with decreased levels of Pparγ, Adipoq and Slc2a4 (genes related to glucose metabolism). These alterations were associated with increased expression of the tumor suppressors alternate-reading-frame protein p19Arf (Arf) and p16Ink4a. However, silencing of Arf reduced mRNAs of Adipoq and Slc2a4 and enhanced release of Il6. The effect was opposite in Arf overexpressing adipocytes, which showed reduced superoxide production as assessed with DHE staining and SOD activity. Western blots showed that Arf negatively regulates the phosphorylation of Akt. Luciferase assay in Hela cells additionally suggested that Arf negatively regulates Il6 transcriptional activity through a PI3xa0K/Akt mediated pathway. These findings strongly suggest that the enhanced Arf expression in oxidative stress plays compensatory protective roles against aging-related dysregulation of gene expression in adipocytes.

Targeted Therapy for Acute Autoimmune Myocarditis with Nano-Sized Liposomal FK506 in Rats.

Immunosuppressive agents are used for the treatment of immune-mediated myocarditis; however, the need to develop a more effective therapeutic approach remains. Nano-sized liposomes may accumulate in and selectively deliver drugs to an inflammatory lesion with enhanced vascular permeability. The aims of this study were to investigate the distribution of liposomal FK506, an immunosuppressive drug encapsulated within liposomes, and the drug’s effects on cardiac function in a rat experimental autoimmune myocarditis (EAM) model. We prepared polyethylene glycol-modified liposomal FK506 (mean diameter: 109.5 ± 4.4 nm). We induced EAM by immunization with porcine myosin and assessed the tissue distribution of the nano-sized beads and liposomal FK506 in this model. After liposomal or free FK506 was administered on days 14 and 17 after immunization, the cytokine expression in the rat hearts along with the histological findings and hemodynamic parameters were determined on day 21. Ex vivo fluorescent imaging revealed that intravenously administered fluorescent-labeled nano-sized beads had accumulated in myocarditic but not normal hearts on day 14 after immunization and thereafter. Compared to the administration of free FK506, FK506 levels were increased in both the plasma and hearts of EAM rats when liposomal FK506 was administered. The administration of liposomal FK506 markedly suppressed the expression of cytokines, such as interferon-γ and tumor necrosis factor-α, and reduced inflammation and fibrosis in the myocardium on day 21 compared to free FK506. The administration of liposomal FK506 also markedly ameliorated cardiac dysfunction on day 21 compared to free FK506. Nano-sized liposomes may be a promising drug delivery system for targeting myocarditic hearts with cardioprotective agents.

Low-Dose Erythropoietin in Patients With ST-Segment Elevation Myocardial Infarction (EPO-AMI-II) ― A Randomized Controlled Clinical Trial ―

BACKGROUNDnErythropoietin (EPO) has antiapoptotic and tissue-protective effects, but previous clinical studies using high-dose EPO have not shown cardioprotective effects, probably because of platelet activation and a lack of knowledge regarding the optimal dose. In contrast, a small pilot study using low-dose EPO has shown improvement in left ventricular function without adverse cardiovascular events.Methodsu2004andu2004Results:We performed a multicenter (25 hospitals), prospective, randomized, double-blind, placebo-controlled, dose-finding study to clarify the efficacy and safety of low-dose EPO in patients with ST-segment elevation myocardial infarction (STEMI) under the Evaluation System of Investigational Medical Care of the Ministry of Health, Labor and Welfare of Japan. In total, 198 STEMI patients with low left ventricular ejection fraction (LVEF <50%) were randomly assigned to receive intravenous administration of EPO (6,000 or 12,000 IU) or placebo within 6 h of successful percutaneous coronary intervention. At 6 months, there was no significant dose-response relationship in LVEF improvement among the 3 groups tested (EPO 12,000 IU: 5.4±9.3%, EPO 6,000 IU: 7.3±7.7%, Placebo: 8.1±8.3%, P=0.862). Low-dose EPO also did not improve cardiac function, as evaluated by 99 mTc-MIBI SPECT or NT-proBNP at 6 months and did not increase adverse events.nnnCONCLUSIONSnAdministration of low-dose EPO did not improve LVEF at 6 months in STEMI patients (UMIN000005721).

Protein Quality Control Dysfunction in Cardiovascular Complications Induced by Anti-Cancer Drugs

Cardiovascular complications, including heart failure, hypertension, ischemic syndromes and venous thromboembolism, have been identified in patients treated with anti-cancer drugs. Oxidative stress, mitochondrial dysfunction and DNA synthesis inhibition are considered to be responsible for the cardiotoxicity induced by these agents. Protein quality control (PQC) has 3 major components, including the endoplasmic reticulum (ER), the ubiquitin-proteasome system (UPS) and the autophagy-lysosome system, and participates in protein folding and degradation to maintain protein homeostasis. We have demonstrated that PQC dysfunction is a new causal mechanism for the development of cardiac hypertrophy and failure. Increasing evidence shows that anti-cancer drugs, such as tyrosine kinase inhibitors, proteasome inhibitors, anthracyclines and autophagy inhibitors, cause PQC dysfunction. Here, we provide an overview of the potential role of PQC dysfunction in the development of cardiovascular complications induced by anti-cancer drugs.

Role of Activation of Ecto-5’-Nucleotidase for Cardioprotection in Ischemic Preconditioning

When brief periods of ischemia precede sustained ischemia, infarct size is markedly limited, a phenomenon known as ischemic preconditioning [1,2]. The precise mechanisms underlying this phenomenon have been investigated [3,4] because identification of the primary mediator of ischemic preconditioning may contribute to the development of the potential treatment of acute myocardial infarction. Several lines of evidence suggest that beneficial effects of ischemic preconditioning are observed in clinical settings [5,6]. Recently, Liu et al. [7] experimentally demonstrated that an exposure to 8-sulfophenyl-theophylline blunts the infarct-size—limiting effect of ischemic preconditioning and that brief periods of exposures to adenosine, instead of transient ischemia, mimic ischemic pre-conditioning. Thornton et al. [8] showed that adenosine A1-receptor activation is responsible for the infarct-size—limiting effect of ischemic preconditioning.

Post-transplant immunoglobulin A deposition and nephropathy in allografts: Post-transplant IgA deposition

Post‐transplant immunoglobulin A (IgA) nephropathy (IgAN) in the allograft is the major cause of allograft loss. Using a protocol biopsy, latent mesangial IgA deposition (IgAD) can be detected in the allograft. Latent IgAD is distinguished from IgAN by the absence of urinary abnormalities, although IgA is observed in the mesangium. However, the pathophysiology and most appropriate treatment strategy for latent mesangial IgAD in the allograft remain to be fully determined. Importantly, it is unknown whether all cases of post‐transplant asymptomatic IgAD progress to symptomatic IgAN; indeed, IgA deposits disappear in some cases. The differences in allograft prognosis between asymptomatic IgAD and IgAN have also not been determined. Non‐invasive methods of diagnosis of IgAD in the allograft using serological and pathological biomarkers are being developed. Possible serum biomarkers include serum galactose‐deficient IgA1 (Gd‐IgA1), Gd‐IgA1‐specific IgG and Gd‐IgA1‐specific IgA, and its immune complexes. Immunofluorescence analysis using Gd‐IgA1 monoclonal antibody may provide a pathological biomarker. These serological and pathological biomarkers may be suitable for the characterization of the stage of IgAD. However, there is insufficient information regarding whether serological and pathological biomarkers can predict the progression of asymptomatic IgAD to symptomatic IgAN. We propose that the pathogenesis of IgAN can be defined through the clinical study of IgAD in the allograft using protocol biopsies conducted by nephrologists involved in clinical kidney transplantation.

Systemic Administration of siRNA with Anti-HB-EGF Antibody-Modified Lipid Nanoparticles for the Treatment of Triple-Negative Breast Cancer

Triple-negative breast cancer is one of the intractable cancers that are not sensitive to treatment with existing molecular-targeted drugs. Recently, there has been much interest in RNA interference-mediated treatment of triple-negative breast cancer. In the present study, we have developed lipid nanoparticles encapsulating siRNA (LNP-siRNA) decorated with an Fab antibody against heparin-binding EGF-like growth factor (αHB-EGF LNP-siRNA). αHB-EGF LNP-siRNA targeting polo-like kinase 1 (PLK1) was prepared and evaluated for its anticancer effect using MDA-MB-231 human triple-negative breast cancer cells overexpressing HB-EGF on their cell surface. Biodistribution data of radioisotope-labeled LNP and fluorescence-labeled siRNA indicated that αHB-EGF LNP effectively delivered siRNA to tumor tissue in MDA-MB-231 carcinoma-bearing mice. Expression of PLK1 protein in the tumors was clearly suppressed after intravenous injection of αHB-EGF LNP-siPLK1. In addition, tumor growth was significantly inhibited by treatment with this formulation of siRNA and an antibody-modified carrier. These findings indicate that αHB-EGF LNP is a promising carrier for the treatment of HB-EGF-expressing cancers, including triple-negative breast cancer.

Adult aortic coarctation presenting with refractory heart failure and pulsation below the bilateral clavicle

Adult aortic coarctation is often asymptomatic and this condition can be detected because of a murmur or unexplained hypertension. Here, we report an adult case of aortic coarctaion with heart failure and a characteristic finding of pulsation below the bilateral clavicle.u3000 A 58-year-old man with refractory heart failure due to unknown reasons was referred to our hospital. Auscultation presented no murmur and high blood pressure had been treated with medicine. Interestingly, precise physical examination revealed the bilateral pulsation at the midclavicular line from the 2nd to the 5th intercostal areas. Echographic examination revealed the dilated vessel and arterial blood flow 1-2xa0cm in depth from the body surface at the midclavicular 2nd intercostal areas. Contrast-enhanced computed tomography showed thoracic aortic coarctation and a well-developed collateral circulation via the bilateral internal thoracic arteries and epigastric arteries. The cause of heart failure was diagnosed as aortic coarctation. Palliative revascularization was performed and his blood pressure was lowered. When we see the patients with refractory heart failure due to unknown reasons, pulsation below the bilateral clavicle may give us a clue to diagnose the hidden aortic coarctation. <Learning objective: We must consider adult aortic coarctation when we see patients with refractory heart failure. Although the present case did not show a cardiac murmur characteristic of aortic coarctation, we found out the very unique sign of pulsation below the bilateral clavicle. When we see patients with refractory heart failure due to unknown reasons, pulsation below the bilateral clavicle may give us an important clue to diagnose the hidden aortic coarctation.>.

Subclavian Fat Biopsy with the PacemakerImplantation is Useful for the Diagnosis of Amyloidosis

Amyloidosis has been regarded as a rare disease, however, recent reports demonstrated that the prevalence of wild type ATTR amyloidosis (ATTRwt) is up to 25% in elderly persons aged 80 years or older[1].Progressive conduction disease is common in ATTR amyloidosis and approximately 20-40% of patients with amyloidosis is estimated to require the pacemaker implantation. Because many promising diseasemodifying therapies have emerged over the past decade[2]the correct diagnosis of amyloidosis will become more important for better treatment. However, the diagnosis of amyloidosis in these patients would beunderestimated because the additional invasive biopsy is often hesitated in elderly persons.Therefore, it is ideal to perform the invasive biopsy to diagnose amyloidosis at the timing of pacemaker implantation. We here report the case that the subclavian fat biopsy with the pacemaker implantation was useful for the diagnosis of amyloidosis.