Saori Nagura

Selective isolation of nanog-positive human amniotic mesenchymal cells and differentiation into cardiomyocytes.

Adult cardiomyocytes have little ability to regenerate, thus cardiac regeneration therapy represents a potential method for treating severe heart failure. Human amniotic mesenchymal cells (hAMCs) have the potential to be a useful cell source for cardiac regeneration therapy. We attempted to isolate stem cells from hAMCs and differentiate them into cardiomyocytes. Nanog promoter-Cre plasmid and cytomegalovirus (CMV) promoter-loxP-STOP-loxP-Red-puro(r) plasmid were co-transfected into immortalized hAMCs (iHAMs). Nanog-positive iHAMs were treated with 5-azacytidine (5-aza), trichostatin A (TA), activin A (AA), and bone morphogenetic protein-4 (BMP-4), or co-cultured with murine fetal cardiomyocytes for cardiomyocytes differentiation. Isolated Nanog-positive iHAMs were analyzed by quantitative RT-PCR and immunofluorescent staining before and after differentiation. Expression of Nanog, Oct3/4, Sox2, and Klf4 was significantly higher in Nanog-positive than in Nanog-negative iHAMs. Nanog-positive iHAMs were stained for Nanog and Oct3/4 in the nucleus. Nanog-positive iHAMs treated with 5-aza expressed Nkx2.5, GATA-4, human atrial natriuretic peptide (hANP), cardiac troponin T (cTnT), myocin light chain (Mlc)-2a, Mlc-2v, β-myosin heavy chain (β-MHC), hyperpolarization-activated cyclic nucleotide gated channels (HCN)-4, and inwardly rectifying potassium channels (Kir)-2.1. Although Nanog-positive iHAMs treated with TA, AA, or BMP-4 expressed several cardiac markers, no contraction was observed. Co-cultured Nanog-positive iHAMs with murine fetal cardiomyocytes spontaneously contracted in a synchronized manner and expressed the cardiac markers. In conclusion, Nanog-positive hAMCs with characteristics of stem cells were isolated and differentiated into cardiomyocyte-like cells, suggesting that these isolated hAMCs could be a useful cell source for cardiac regeneration therapy.

Treatment of mediastinitis due to methicillin-resistant Staphylococcus aureus in a renal dysfunction patient undergoing adjustments to the linezolid dose.

This study is the first case report of the treatment of methicillin-resistant Staphylococcus aureus (MRSA) mediastinitis using therapeutic drug monitoring of the serum and wound exudate concentrations of linezolid in a renal dysfunction patient. In the present study, the serum trough concentration of linezolid was maintained between 2 and 7 μg/mL. Therapeutic drug monitoring dosage adjustments may be especially useful in patients with renal dysfunction and severe MRSA infection.

Effect of Exogenous Oct4 Overexpression on Cardiomyocyte Differentiation of Human Amniotic Mesenchymal Cells

Regenerative therapy is a new strategy for the end-stage heart failure; however, the ideal cell source has not yet been established for this therapy. We expected that the amnion might be an ideal cell source for cardiac regenerative therapy and that the differentiation potency of the human amnion mesenchymal cells (hAMCs) could be improved by overexpression of Oct4, a key factor that maintains the undifferentiated state. A plasmid vector was made by insertion of the Oct4 open reading frame (ORF) under control of a cytomegalovirus (CMV) promoter (pCMV-hOct4) and transfected into hAMCs by electroporation. The optimum induction time was investigated by comparing the quantity of stem cell-specific mRNAs, cardiac-specific mRNAs, and cardiac-specific proteins with time. hAMCs already expressed cardiac-specific proteins such as Nkx2.5 and Connexin43. After pCMV-hOct4 transfection, endogenous Oct4 mRNA and other stem cell markers showed a transient increase. With 5-azacytidine treatment, quantities of the cardiac-specific mRNAs, such as GATA4 and myosin light-chain-2v (Mlc-2v), were increased significantly. After Oct4 overexpression, the highest expression of cardiac-specific mRNAs and stem cell makers was seen at almost the same time. Furthermore, more mature myocardial contraction proteins were observed when hAMCs were induced at specific optimal times after gene transfection. In conclusion, hAMCs were activated to an undifferentiated state by overexpression of Oct4, and their cardiac differentiation potency was improved. Thus, the single-time transfection of the Oct4 expression vector may be a useful strategy for effective cell therapy. The use of cryopreserved hAMCs in cell therapy still requires more investigation.

Surgical Treatment of Complete Anterolateral Papillary Muscle Rupture Following Acute Myocardial Infarction

Papillary muscle rupture is a lethal complication of after acute myocardial infarction. We report the successful surgical management of complete anterolateral papillary muscle rupture associated with cardiogenic shock in an 80-year-old woman. The patient was admitted with the sudden onset of chest pain and dyspnea. After hemodynamics deteriorated rapidly, she was intubated and intra-aortic balloon pump was started immediately. Transthoracic echocardiography revealed severe mitral regurgitation due to complete anterolateral papillary muscle rupture associated with lateral myocardial infarction. Coronary angiography demonstrated complete occlusion of the first obtuse marginal artery. She underwent emergency mitral valve replacement and coronary artery bypass grafting. There were no complications of surgery and she was discharged on postoperative day 35. Rapid preoperative assessment and aggressive surgical management are important to improve the prognosis in this setting.

Management of pulmonary venous obstruction

Although improved surgical techniques have led to significantly better outcomes of surgery for total anomalous pulmonary venous connection, the risk of progressive pulmonary venous obstruction continues to be a clinical problem. Both obstructed total anomalous pulmonary venous connection and post-repair pulmonary venous obstruction are associated with a significant risk of recurrent obstruction or death, requiring reoperation for stenosis. In general, side to side anastomosis of the pulmonary venous confluence to the functional left atrium has been performed for supracardiac and infracardiac total anomalous pulmonary venous connection. Repair of total anomalous pulmonary venous connection to the coronary sinus invariably involved unroofing the coronary sinus, followed by pericardial patch closure of the atrial septal defect. Recently, sutureless technique has been adopted as the primary operation for the subgroups of patients that are thought to be at high risk for post-repair pulmonary venous obstruction, such as those with total anomalous pulmonary venous connection associated with right isomerism, infracardiac total anomalous pulmonary venous connection with small individual pulmonary veins, or mixed-type total anomalous pulmonary venous connection. Because the sutureless technique does not require direct anastomosis to the confluence, aggressive resection of the obstructed pulmonary venous tissue can be achieved, and surgically induced distortion of the suture line can be avoided, which may help to prevent subsequent pulmonary venous obstruction. Conventional management strategies for recurrent pulmonary venous obstruction have typically been associated with poor outcomes. Recent reports have supported the use of the sutureless technique to treat post-repair pulmonary venous obstruction.

Transcatheter Aortic Valve Implantation Improves Cardiac Sympathetic Nerve Activity on 123I-Metaiodobenzylguanidine Myocardial Scintigraphy in Severe Aortic Valve Stenosis

BACKGROUND There is a consensus that overactivation of the cardiac sympathetic nervous system (CSN) proportionately increases the severity of heart failure and is accompanied by worse prognosis. Because it is unknown whether patients with aortic valve stenosis (AS) have similar CSN activation, we investigated the effect of transcatheter aortic valve implantation (TAVI).Methods and Results:We enrolled 31 consecutive patients with AS treated by TAVI. 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy was performed at baseline and at 2 weeks after TAVI. At baseline, the early heart-mediastinum ratio (H/M) was within normal limits (3.0±0.5), but the delayed H/M was low (2.6±0.6) and the washout rate (WR) was high (34±13%). WR negatively correlated with aortic valve area (r=-0.389, P<0.01) and cardiac output (r=-0.595, P<0.01) and positively correlated with norepinephrine (r=0.519, P<0.01) and log NT-proBNP level (r=0.613, P<0.01). After TAVI, there were significant decreases in the norepinephrine level (366±179 ng/mL vs. 276±125 ng/mL, P<0.01) and WR (34±13 vs. 26±11%, P<0.01). CONCLUSIONS The WR of MIBG was a useful marker of CSN activity and severity of AS. Immediate improvement of CSN activity after TAVI implied that AS hemodynamics per se enhanced CSN.

Primary Cardiac Malignant Lymphoma: Survival for 13 Years After Surgical Resection and Adjuvant Chemotherapy

We report a patient who has survived for 13 years after surgical resection of a cardiac malignant lymphoma. A 73-year-old woman underwent partial resection of a tumor occluding the tricuspid valve, which arose from the right atrium. The pathologic diagnosis was diffuse large B cell lymphoma. She was treated with adjuvant chemotherapy for 6 months postoperatively. Since then, she has shown no evidence of recurrence, without any further treatment. To our knowledge, this is the longest surviving case of cardiac malignant lymphoma. The therapeutic strategy for this malignant cardiac tumor is discussed briefly.

On-Pump Beating Heart Extraanatomical Ascending-Descending Aortic Bypass Using a Beating Heart Positioner in an Adult with Aortic Coarctation

The prognosis of uncorrected aortic coarctation is poor due to development of heart failure. We performed an on-pump beating heart extraanatomical ascending-descending aortic bypass using a beating heart positioner in an adult with coarctation complicated by severe left ventricular hypertrophy. A 51-year-old woman was referred with severe hypertension. Computed tomography demonstrated severe distal aortic arch narrowing. Coarctation of the aorta was diagnosed. A posterior pericardial beating heart extraanatomical bypass via median sternotomy was performed from the ascending to descending aorta using a heart positioner. Her postoperative course was uneventful and blood pressure was normal on a low-dose beta-blocker.

Experimental Mitral Valve Plasty under the Beating Heart Guided by Real-Time 3-Dimensional Echocardiography

BACKGROUND This study examines whether real-time 3-dimensional echocardiography can provide an image resolution to serve as a substitute for optical visualization in performing mitral valve plasty. METHODS Three pigs were used in this study. A 3-dimensional echocardiographic system was evaluated on an epicardial surface. Beating heart mitral valve plasty was performed with a surgical stapler inserted from the apex of the left ventricle using only 3-dimensional echocardiographic visualization. RESULTS The high-quality images of the mitral valve were obtained with the probe at the epicardial position. However, by inserting the surgical instrument into the left ventricle, an acoustic shadow developed on the images. The images became indistinct because of the acoustic shadow, and operation became difficult. For the mitral valve plasty, an edge-to-edge mitral valve repair was carried out using a stapler (10 mm) under the beating heart. The stapler was confirmed to seize both leaflets evenly in only 1 of the 3 pigs. CONCLUSIONS Real-time 3-dimensional echocardiography provided clear 3-dimensional images of the mitral valve; however, when a surgical instrument was inserted into the left ventricle, an acoustic shadow appeared on the image and made detailed confirmation difficult. Lessening or eliminating the acoustic shadow would be a key point to improve this procedure.