Chun An Chen

Early Detection of Pompe Disease by Newborn Screening Is Feasible: Results From the Taiwan Screening Program

OBJECTIVE. Pompe disease is an autosomal recessive lysosomal storage disorder that is caused by deficient acid α-glucosidase activity and results in progressive, debilitating, and often life-threatening symptoms involving the musculoskeletal, respiratory, and cardiac systems. Recently, enzyme replacement therapy with alglucosidase α has become possible, but the best outcomes in motor function have been achieved when treatment was initiated early. The aim of this study was to test the feasibility of screening newborns in Taiwan for Pompe disease by using a fluorometric enzymatic assay to determine acid α-glucosidase activity in dried blood spots. METHODS. We conducted a large-scale newborn screening pilot program between October 2005 and March 2007. The screening involved measuring acid α-glucosidase activity in dried blood spots of ∼45% of newborns in Taiwan. The unscreened population was monitored as a control. RESULTS. Of the 132 538 newborns screened, 1093 (0.82%) repeat dried blood-spot samples were requested and retested, and 121 (0.091%) newborns were recalled for additional evaluation. Pompe disease was confirmed in 4 newborns. This number was similar to the number of infants who received a diagnosis of Pompe disease in the control group (n = 3); however, newborn screening resulted in an earlier diagnosis of Pompe disease: patients were <1 month old compared with 3 to 6 months old in the control group. CONCLUSIONS. To our knowledge, this is the first large-scale study to show that newborn screening for Pompe disease is feasible. Newborn screening allows for earlier diagnosis of Pompe disease and, thus, for assessment of the value of an earlier start of treatment.

Losartan Added to β-Blockade Therapy for Aortic Root Dilation in Marfan Syndrome: A Randomized, Open-Label Pilot Study

OBJECTIVE To assess the tolerability and efficacy of the investigational use of the angiotensin II receptor blocker losartan added to β-blockade (BB) to prevent progressive aortic root dilation in patients with Marfan syndrome (MFS). PATIENTS AND METHODS Between May 1, 2007, and September 31, 2011, 28 patients with MFS (11 males [39%]; mean ± SD age, 13.1±6.3 years) with recognized aortic root dilation (z score >2.0) and receiving BB (atenolol or propranolol) treatment were enrolled. They were randomized to receive BB (BB: 13 patients) or β-blockade and losartan (BB-L: 15 patients) for 35 months. RESULTS In the BB-L group, aortic root dilation was reduced with treatment, and the annual dilation rate of the aortic root was significantly lower than that of the BB group (0.10 mm/yr vs 0.89 mm/yr; P=.02). The absolute aortic diameters at the sinus of Valsalva, annulus, and sinotubular junction showed similar trends, with a reduced rate of dilation in the BB-L group (P=.02, P=.03, and P=.03, respectively). Five patients (33%) treated with BB-L were noted to have a reduced aortic root diameter. However, the differences between the groups regarding changes in aortic stiffness and cross-sectional compliance were not statistically significant. CONCLUSION This randomized, open-label, active controlled trial mostly based on a pediatric population demonstrated for the first time that losartan add-on BB therapy is safe and provides more effective protection to slow the progression of aortic root dilation than does BB treatment alone in patients with MFS. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00651235.

Long-Term Prognosis of Patients with Infantile-Onset Pompe Disease Diagnosed by Newborn Screening and Treated since Birth

OBJECTIVE To determine the benefit of newborn screening for the long-term prognosis of patients with classic infantile-onset Pompe disease (IOPD). STUDY DESIGN A cohort of patients with classic IOPD were diagnosed by newborn screening, treated with recombinant human acid α-glucosidase (rhGAA), and followed prospectively. Outcome measurements included survival, left ventricular mass, serum creatinine kinase, motor function, mental development, and systemic manifestations. RESULTS Ten patients who presented with left ventricular hypertrophy at diagnosis received rhGAA infusions starting at a median age of 16 days (6-34 days). All patients were cross-reactive immunologic material-positive. After a median treatment time of 63 months (range 28-90 months), all could walk independently, and none required mechanical ventilation. All patients had motor capability sufficient for participating in daily activities, but muscle weakness over the pelvic girdle appeared gradually after 2 years of age. Ptosis was present in one-half of the patients, and speech disorders were common. Anti-rhGAA antibody titers were low (median maximal titer value 1:1600, range: undetectable ∼ 1:12,800). CONCLUSION By studying patients treated since birth who have no significant anti-rhGAA antibody interference, this prospective study demonstrates that the efficacy of rhGAA therapy is high and consistent for the treatment of classic IOPD. This study also exposes limitations of rhGAA treatment. The etiology of the manifestations in these early-treated patients will require further study.

Quality of life in adults with congenital heart disease: biopsychosocial determinants and sex-related differences

Objectives To assess the quality of life (QoL) in adults with congenital heart disease (ACHD) and to explore the sex-related differences and biopsychosocial determinants in an Asian cohort. Design Prospective cross-sectional clinical study. Setting One tertiary medical centre in Taiwan. Patients and methods The QoL of ACHD (≥20 years) was investigated using the Taiwanese version of the QoL questionnaire designed by the WHO, which assesses four domains of QoL (physical, psychological, social and environmental). Personality, psychological distress and family support were assessed using the Maudsley Personality Inventory, Brief Symptom Rating Scale, and the Family APGAR score, respectively. Results A total of 289 patients (age 33.2±10.6 years; 36% men) were studied. ACHD women had significantly lower QoL scores in the physical and psychological domains compared to the age-matched general population, whereas no differences were observed between ACHD men and the general population. Multivariate analysis showed that female gender was associated with poorer physical QoL; the sex difference in the psychological QoL was mediated by psychological distress. Interaction analysis showed that the effect of family support on the psychological domain of QoL may be different by sex. The determinants of QoL varied between different domains. Extroversion personality trait, psychological distress and family support were common determinants of most domains of QoL. Conclusions In ACHD, female gender was associated with poor physical and psychological QoL. The common denominators for QoL were primarily personality trait, psychological distress and family support, but not disease severity.

Comparison of 3 risk estimation methods for predicting cardiac outcomes in pregnant women with congenital heart disease

BACKGROUND Three risk estimation methods for predicting the cardiac outcomes of pregnancy in women with heart disease have been proposed. This study was designed to compare their prediction performance in an Asian cohort with congenital heart disease (CHD). METHODS AND RESULTS This study enrolled pregnant women with CHD who delivered their babies after the 20th gestational week between 1985 and 2011. Of 268 pregnancies in 190 women with CHD, 18 (6.7%) had cardiac complications. The incidence of maternal cardiac events among women with a CARPREG index of 0, 1 or 2 was 3.4%, 27.3% and 100%. The incidence was 2.7%, 8.6%, 11.1%, 40% and 17.6% for those with a ZAHARA score 0-0.5, 0.51-1.5, 1.51-2.5, 2.51-3.5 and >3.5. Among patients with a modified World Health Organization (WHO) classification I, II, III and IV, the incidence of maternal cardiac events was 0%, 4.0%, 12.2% and 25.7%. The c-statistic was 0.732 (95% confidence interval (CI): 0.589, 0.876; P<0.001) for the CARPREG score, 0.737 (95% CI: 0.611, 0.864; P=0.001) for the ZAHARA score and 0.827 (95% CI: 0.745, 0.909; P<0.001) for the WHO classification. CONCLUSIONS All 3 risk estimation methods had good performance in predicting maternal cardiac outcomes; however, the modified WHO classification demonstrated superior discrimination and calibration.

Characterization and enhanced field emission properties of IrO2-coated carbon nanotube bundle arrays.

In order to enhance field emission (FE) property of carbon nanotubes (CNTs), IrO<inf>2</inf> nanocrystals (NCs) were coated on the patterned CNT bundle arrays via reactive RF magnetron sputtering. The properties of IrO<inf>2</inf>/CNTs composites were characterized by field-emission scanning electron microscopy and transmission electron microscopy. Based on the combined effects of geometrical structure of IrO<inf>2</inf>/CNTs composites, and the natural conductor and enhanced resistance to oxidation properties of IrO<inf>2</inf>, a low turn-on field of 0.7 V/µm at a current density of 0.1 µA/cm², a low threshold field of 2.3 V/µm at a current density of 1 mA/cm², a high field enhancement factor of 4 × 10⁵, and a long-term stability have been achieved for the IrO<inf>2</inf> coated patterned CNT bundle arrays.

Ultrahigh efficient single-crystalline TiO2 nanorod photoconductors

Photoconductive gain and normalized gain, which determine the device and material properties on photoconduction, respectively, have been defined for single-crystalline titanium dioxide (TiO2) nanorods (NRs) with various diameter sizes. The gain values of the NR photodetectors can reach 105 easily at a low bias of 0.1 V. By excluding the contributions of experimental parameters, the optimal normalized gain of the indirect-bandgap TiO2 NRs at 5.4 × 10−5 m2V−1 is comparable with that estimated from the direct-bandgap ZnO nanowires. The average normalized gain value at 3.3 ± 2.2 × 10−5 m2V−1 obtained from eight individual TiO2 NRs with diameters ranging from 120 to 1250 nm is also over three orders of magnitude higher than the polycrystalline nanotube counterpart. The results demonstrate the superior photoconductivity efficiency in boundary-free titania one-dimensional nanostructure, which is crucial for ultraviolet photodetector, dye-sensitized solar cell, and photochemical device applications.

Left ventricular geometry, global function, and dyssynchrony in infants and children with pompe cardiomyopathy undergoing enzyme replacement therapy.

BACKGROUND Enzyme replacement therapy (ERT) for infantile-onset Pompe disease effectively reduces the left ventricular (LV) mass. This study sought to explore detailed process of LV reverse remodeling after ERT with the use of tissue Doppler and stain rate imaging. METHODS AND RESULTS Nine infants and children with Pompe cardiomyopathy undergoing ERT for ≥1 year, as well as 36 healthy control subjects, were studied. Global systolic and diastolic function was evaluated by peak systolic and early-diastolic velocity at mitral annulus. Temporal systolic and diastolic dyssynchrony was evaluated by the coefficient of variation of the time from the QRS complex to peak systolic and early-diastolic strain rate among 12 LV segments. All pre-ERT patients had impaired global systolic and diastolic function as well as increased regional dyssynchrony (P < .001 for each of all). During the regression of LV hypertrophy, all of these functional indices improved (P for trend <.001), with temporal diastolic dyssynchrony being a significant factor linking to LV mass index in multivariate analysis (P < .001). CONCLUSIONS ERT improved global LV function and dyssynchrony in Pompe patients. The relationship between LV mass and temporal diastolic dyssynchrony during reverse remodeling suggested a pathophysiologic role of dyssynchrony in Pompe cardiomyopathy.

Transport properties in single-crystalline rutile TiO2 nanorods

Electronic transport properties of the single-crystalline titanium dioxide (TiO2) nanorods (NRs) with single rutile phase have been investigated. The conductivity values for the individual TiO2 NRs grown by metal-organic chemical vapor deposition are in the range of 1−10 Ω−1 cm−1. The temperature-dependent measurement shows the presence of two shallow donor levels/bands with activation energies at 8 and 28 meV, respectively. On the photoconductivity (PC), the TiO2 NRs exhibit the much higher normalized PC gain and sensitive excitation-power dependence than the polycrystalline nanotubes. The results demonstrate the superior photoconduction efficiency and distinct mechanism in the monocrystalline one-dimensional TiO2 nanostructures in comparison to the polycrystalline or nanoporous counterparts.

Increased microvolt T-wave alternans in patients with repaired tetralogy of Fallot

BACKGROUND Microvolt T wave alternans (MTWA) is an indicator of repolarization heterogeneity and a predictor of ventricular arrhythmia in adults with ischemic or dilated cardiomyopathy. Its implication in patients with repaired tetralogy of Fallot (TOF) is still unclear. This study sought to define the changes and the clinical implication of MTWA in these patients. METHODS Treadmill examination with modified moving average beat analysis (MMA) for MTWA was performed in 101 repaired TOF patients (60.4% male). Data from 103 age- and sex-matched subjects with normal hearts served as controls. RESULTS The age at latest follow-up was 20.0 ± 10.6 years. Total repair (60.4% received a transannular right ventricular outflow patch) was performed at a mean age of 4.8(± 5.8) years. After excluding 11 patients with indeterminate data, the MTWA data in 90 TOF patients revealed higher values than those in the control (25.1 ± 14.0 vs. 17.6 ± 9.2 μV, p<0.001). The values were best correlated to the presence of severe pulmonary regurgitation (p=0.006). Ten (9.9%) patients experienced late ventricular arrhythmic events. They tended to have higher MTWA values than those without (34.0 ± 16.5 vs. 24.2 ± 13.5 and p=0.053). Although the MTWA per se would not predict the late arrhythmia events better than QRS duration alone, the positive and negative predictive values increased slightly after adding the MTWA to QRS duration. CONCLUSIONS MTWA, as measured by MMA, increased in repaired TOF patients particularly in those with severe pulmonary regurgitation and late arrhythmia events. To predict late ventricular arrhythmia, MTWA however was not superior to QRS duration alone.