Restless legs syndrome in patients with type 2 diabetes: effectiveness of pramipexole therapy.

OBJECTIVE: We investigated the prevalence of restless legs syndrome (RLS) in Japanese patients with type 2 diabetes and assessed the efficacy of pramipexole therapy. DESIGN: One hundred patients with type 2 diabetes without secondary causes of RLS were sequentially screened for the 12-week, prospective, single arm study. RLS was screened by essential diagnostic criteria developed by the International Restless Legs Study Group. Diabetic neuropathy was diagnosed by nerve conductance study. Severity of RLS and sleep quality were assessed by the International Restless Legs Rating Scale (IRLS) and the Japanese version of the Pittsburgh Sleep Quality Index (PSQI-J), respectively. Pramipexole was administered for 12 weeks. The primary end point was change in the IRLS score in 12 weeks and secondary end points were change in PSQI-J and glycated haemoglobin (HbA1c) in 12 weeks. RESULTS: RLS was diagnosed in 8 of 100 participants (8%). Diabetic neuropathy was most likely associated with RLS (OR 3.81, 95% CI 0.85 to 17.05, p=0.111). The IRLS score was improved from 19.0±5.6 to 5.4±4.8 by pramipexole in 12 weeks (p<0.001). The change in the score was -13.6 (95% CI -15.5 to -11.7; p<0.05). PSQI-J was improved from 6.0±4.4 to 1.5±1.3 in 12 weeks (p<0.05). Change in PSQI-J was -4.5 (95% CI -6.8 to -2.1; p<0.05). HbA1c was slightly decreased from 7.19±0.56% (55±6 mmol/mol) to 6.90±0.48% (52±5 mmol/mol) in 12 weeks (p<0.05). Change in HbA1c was -0.29% (-3 mmol/mol) (95% CI -0.37% to -0.20% (-4 to -2 mmol/mol;) p<0.05). CONCLUSIONS: We find that type 2 diabetes is a possible risk factor for RLS in the Japanese population, and that pramipexole treatment can improve the symptoms of RLS as well as the quality of sleep and glycaemic control in these patients. TRIAL REGISTRATION NUMBER: University hospital Medical Information Network in Japan (UMIN000008347).

Endogenous Wnt/beta-catenin signaling is required for cardiac differentiation in human embryonic stem cells.

BACKGROUND: Wnt/beta-catenin signaling is an important regulator of differentiation and morphogenesis that can also control stem cell fates. Our group has developed an efficient protocol to generate cardiomyocytes from human embryonic stem (ES) cells via induction with activin A and BMP4. METHODOLOGY/PRINCIPAL FINDINGS: We tested the hypothesis that Wnt/beta-catenin signals control both early mesoderm induction and later cardiac differentiation in this system. Addition of exogenous Wnt3a at the time of induction enhanced cardiac differentiation, while early inhibition of endogenous Wnt/beta-catenin signaling with Dkk1 inhibited cardiac differentiation, as indicated by quantitative RT-PCR analysis for beta-myosin heavy chain (beta-MHC), cardiac troponin T (cTnT), Nkx2.5, and flow cytometry analysis for sarcomeric myosin heavy chain (sMHC). Conversely, late antagonism of endogenously produced Wnts enhanced cardiogenesis, indicating a biphasic role for the pathway in human cardiac differentiation. Using quantitative RT-PCR, we show that canonical Wnt ligand expression is induced by activin A/BMP4 treatment, and the extent of early Wnt ligand expression can predict the subsequent efficiency of cardiogenesis. Measurement of Brachyury expression showed that addition of Wnt3a enhances mesoderm induction, whereas blockade of endogenously produced Wnts markedly inhibits mesoderm formation. Finally, we show that Wnt/beta-catenin signaling is required for Smad1 activation by BMP4. CONCLUSIONS/SIGNIFICANCE: Our data indicate that induction of mesoderm and subsequent cardiac differentiation from human ES cells requires fine-tuned cross talk between activin A/BMP4 and Wnt/beta-catenin pathways. Controlling these pathways permits efficient generation of cardiomyocytes for basic studies or cardiac repair applications.

A1C but not serum glycated albumin is elevated because of iron deficiency in late pregnancy in diabetic women.

OBJECTIVE We have already reported that A1C is elevated because of iron deficiency in late pregnancy among nondiabetic pregnant women. This report examined whether the same phenomenon is observed in pregnant women with diabetes. RESEARCH DESIGN AND METHODS This longitudinal study was conducted in 17 pregnant women with diabetes (20-35 weeks of pregnancy). A1C, serum glycated albumin, erythrocyte indexes, and iron metabolism indexes were measured. RESULTS A1C levels were significantly increased in late pregnancy, whereas serum glycated albumin showed no significant changes. Glycated albumin/A1C ratio, mean corpuscular hemoglobin, serum transferrin saturation, and serum ferritin were significantly decreased in late pregnancy. Serum transferrin saturation showed a significant positive correlation with glycated albumin/A1C ratio. CONCLUSIONS A1C levels, but not serum glycated albumin levels, are elevated in late pregnancy because of iron deficiency in diabetic women. Serum glycated albumin may offer an adequate marker for glycemic control during pregnancy.

Biphasic role for Wnt/beta-catenin signaling in cardiac specification in zebrafish and embryonic stem cells.

Understanding pathways controlling cardiac development may offer insights that are useful for stem cell-based cardiac repair. Developmental studies indicate that the Wnt/beta-catenin pathway negatively regulates cardiac differentiation, whereas studies with pluripotent embryonal carcinoma cells suggest that this pathway promotes cardiogenesis. This apparent contradiction led us to hypothesize that Wnt/beta-catenin signaling acts biphasically, either promoting or inhibiting cardiogenesis depending on timing. We used inducible promoters to activate or repress Wnt/beta-catenin signaling in zebrafish embryos at different times of development. We found that Wnt/beta-catenin signaling before gastrulation promotes cardiac differentiation, whereas signaling during gastrulation inhibits heart formation. Early treatment of differentiating mouse embryonic stem (ES) cells with Wnt-3A stimulates mesoderm induction, activates a feedback loop that subsequently represses the Wnt pathway, and increases cardiac differentiation. Conversely, late activation of beta-catenin signaling reduces cardiac differentiation in ES cells. Finally, constitutive overexpression of the beta-catenin-independent ligand Wnt-11 increases cardiogenesis in differentiating mouse ES cells. Thus, Wnt/beta-catenin signaling promotes cardiac differentiation at early developmental stages and inhibits it later. Control of this pathway may promote derivation of cardiomyocytes for basic research and cell therapy applications.

The Polycomb-group gene Rae28 sustains Nkx2.5/Csx expression and is essential for cardiac morphogenesis.

The Polycomb-group (PcG) gene Rae28 is a mammalian homologue of the Drosophila gene polyhomeotic. PcG genes are known to maintain transcription states, once initiated, probably by regulating chromatin structure. Since homozygous Rae28-deficient (Rae28(-/-)) mice displayed cardiac anomalies similar to congenital heart diseases in humans, we examined the role of Rae28 in cardiac morphogenesis at the molecular level. In Rae28(-/-) embryos, expression of the cardiac selector gene Nkx2.5/Csx (Nkx2.5) was initiated properly but was not sufficiently sustained later in development. This impaired expression of Nkx2.5 in the maintenance phase proved to have a crucial effect on cardiac morphogenesis, as demonstrated by the results of a genetic complementation experiment in which the cardiac anomalies were suppressed by overexpression of human NKX2.5/CSX1 in Rae28(-/-) embryos. Ubiquitous expression of exogenous Rae28 likewise restored the impaired Nkx2.5 expression in Rae28(-/-) embryos, further supporting the notion that Rae28 sustains Nkx2.5 expression in cardiomyocytes. Thus, our data show that a mammalian PcG gene can play a key role in organogenesis by helping to maintain the expression of a selector gene.

A case of hypereosinophilic syndrome presenting mid-ventricular obstruction.

A 59-year-old man with hypereosinophilic syndrome (HES) who had been maintained with low-dose prednisolone for 5 years developed the characteristic features of hypertrophic cardiomyopathy. Left ventricular endomyocardial biopsy revealed no eosinophilic infiltration but extensive myocardial fibrosis. Cardiac involvement in HES presents as endocardial fibrosis, resulting in a clinical presentation of restrictive cardiomyopathy. HES heart disease can also present dilated cardiomyopathy, but myocardial hypertrophy has only rarely been noted in conjunction with HES. This report concerns a patient with HES who had clinical and hemodynamic evidence of asymmetric septal hypertrophy with mid-ventricular obstruction.

Overexpression of Polycomb-group gene rae28 in cardiomyocytes does not complement abnormal cardiac morphogenesis in mice lacking rae28 but causes dilated cardiomyopathy.

The Polycomb-group genes (PcG) are widely conserved from Drosophila to mammals and are required for maintaining positional information during development. The rae28 gene (rae28) is a member of the mouse PcG. Mice deficient in rae28 (rae28(-/-)) demonstrated that rae28 has a role not only in anteroposterior patterning but also in cardiac morphogenesis. In this study we generated transgenic mice with ubiquitous or cardiomyocyte-specific exogenous rae28 expression. Genetic complementation experiments with these transgenic mice showed that ubiquitous expression of rae28 could reverse the cardiac anomalies in rae28(-/-), whereas cardiomyocyte-specific expression of rae28 could not, suggesting that rae28 is involved in cardiac morphogenesis through a noncardiomyocyte pathway. Interestingly, however, cardiomyocyte-specific overexpression of rae28 caused dilated cardiomyopathy, which was associated with cardiomyocyte apoptosis, abnormal myofibrils, and severe heart failure. Cardiac expression of rae28 was predominant in the early embryonic stage, whereas that of the other PcG members was relatively constitutive. Because rae28 forms multimeric complexes with other PcG proteins in the nucleus, it is presumed that constitutive cardiomyocyte-specific rae28 overexpression impaired authentic PcG functions in the heart. rae28-induced dilated cardiomyopathy may thus provide a clue for clarifying the direct role of PcG in the maintenance of cardiomyocytes.

Bcl-xl reduces doxorubicin-induced myocardial damage but fails to control cardiac gene downregulation.

OBJECTIVE: We recently reported that doxorubicin (Dox), an effective anti-cancer drug, induces apoptosis in cardiac myocytes in association with reduction of Bcl-xl expression. In the present study, we further examined whether overexpression of Bcl-xl ameliorates Dox-induced cardiac myocyte damage. METHODS AND RESULTS: Overexpression of the Bcl-xl gene by adenovirus vector resulted in an 11-fold increase in Bcl-xl protein in neonatal rat cardiac myocytes (BCL) compared to that in cells with beta-galactosidase gene transfection (CTL). Although Dox treatment generated similar amounts of reactive oxygen species (ROS) in BCL and CTL, cell viability was maintained and the number of apoptotic cardiac myocytes was significantly decreased in BCL. Cytochrome c release and enhanced caspase-3 activity after Dox treatment were significantly suppressed and Bax expression level was decreased in BCL. Cardiac-specific gene expression is known to be inhibited by Dox. The expression of cardiac alpha-actin and sarcoplasmic reticulum Ca(2+)-ATPase 2a mRNA was equally inhibited in BCL and CTL after Dox treatment. CONCLUSIONS: Overexpression of Bcl-xl in cardiac myocytes failed to regulate Dox-induced ROS generation and cardiac-specific gene downregulation but inhibited apoptosis accompanied by reduction of Bax protein.

Cardiac-specific activation of signal transducer and activator of transcription 3 promotes vascular formation in the heart.

Signal transducer and activator of transcription 3 (STAT3) functions in cell proliferation, differentiation, and cell survival. Previously, we have demonstrated that the activation of STAT3 is required for glycoprotein 130-mediated induction of VEGF in cardiac myocytes, but the functional importance of STAT3 as an angiogenic mediator remains to be determined. To address this issue, we first generated the adenoviral vector expressing constitutively active STAT3 (caSTAT3). Adenoviral gene transfer of caSTAT3 induced an increase in the expression of VEGF in cultured cardiomyocytes. The conditioned medium from caSTAT3-transfected cardiomyocyte culture promoted endothelial tubule formation, which was inhibited by anti-VEGF antibody. Next, we generated the transgenic (TG) mice with cardiac-specific overexpression of caSTAT3 and demonstrated that caSTAT3 TG mice showed evidence of VEGF induction in the hearts. The caSTAT3 TG hearts also demonstrated increased capillary density accompanied by an increase in the expression of VE-cadherin, an endothelial-specific component. These data indicate that caSTAT3 TG hearts exhibit an enriched vascular structure compared with non-transgenic hearts. The study presented here provides the first evidence that activation of STAT3 controls vessel growth in vivo and suggests that STAT3 contributes to cardiac adaptation by regulating vascular function under the conditions of stress.