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Articles by Y Chang
Total Records ( 6 ) for Y Chang
  Y Chang , H Zheng , Y Shang , Y Jin , G Wang , X Shen and X. Liu
 

The prototypic foot-and-mouth disease virus (FMDV) was shown more than a century ago to be the first filterable agent capable of causing FMD, and it has served as an important model for studying basic principles of Aphthovirus molecular biology. However, the complex structure and antigenic diversity of FMDV have posed a major obstacle to the attempts at manipulating the infectious virus by reverse genetic techniques. Here, we report the recovery of infectious FMDV from cDNAs based on an efficient in vivo RNA polymerase I (polI) transcription system. Intracellular transcription of the full-length viral genome from polI-based vectors resulted in efficient formation of infectious virus displaying a genetic marker. Compared with wild-type virus, an abundance of genomic mRNA and elevated expression levels of viral antigens were indicative of the hyperfunction throughout the life-cycle of this cDNA-derived virus at transcription, replication, and translation levels. The technology described here could be an extremely valuable molecular biology tool for studying FMDV complex infectious characteristics. It is an operating platform for studying FMDV functional genomics, molecular mechanism of pathogenicity and variation, and lays a solid foundation for the development of viral chimeras toward the prospect of a genetically engineered vaccine.

  D Nehra , A. M Goldstein , D. P Doody , D. P Ryan , Y Chang and P. T. Masiakos
 

Objective  To determine the efficacy of extracorporeal membrane oxygenation (ECMO) for nonneonatal acute respiratory failure.

Design  Single-institution, retrospective medical record review from February 1990 to March 2008.

Setting  Tertiary care hospital.

Patients  Eighty-one nonneonatal patients (mean age, 23 years; age range, 2 months to 61 years) with acute respiratory failure who had failed maximal ventilator support received ECMO therapy between 1990 and 2008. Patients were grouped into 6 categories based on diagnosis: sepsis (n = 8), bacterial or fungal pneumonia (n = 15), viral pneumonia (n = 9), trauma or burn (n = 10), immunocompromise (n = 15), and other (n = 24).

Main Outcome Measure  Survival to hospital discharge.

Results  Overall survival was 53%. Survival was highest in patients with viral pneumonia (78%), followed by bacterial pneumonia (53%), sepsis syndrome (44%), and immunocompromise (40%). Patients treated following trauma or burns had the lowest survival (33%). The average age was 19 years for survivors as compared with 27 years for nonsurvivors. Survival was lower in patients with multiple organ failure as compared with those with single organ failure (33% vs 60%, respectively), in patients who experienced mechanical ventilation for longer than 10 days prior to the initiation of ECMO as compared with those who received ventilatory support for less than 10 days prior to the initiation of ECMO (31% vs 57%, respectively), and in patients requiring more than 400 hours of ECMO support as compared with those requiring less than 400 hours of ECMO support (42% vs 55%, respectively).

Conclusions  Therapy with ECMO may provide a survival benefit in carefully selected patients with nonneonatal acute respiratory failure who have failed maximal ventilator support. Nonneonatal survival with ECMO therapy is strongly dependent on diagnosis, with the highest survival seen in those with viral or bacterial pneumonia. Older age, multiple organ failure, prolonged ventilation prior to ECMO initiation, and long ECMO runs are associated with decreased survival.

  E. A Sailhamer , K Carson , Y Chang , N Zacharias , K Spaniolas , M Tabbara , H. B Alam , M. A DeMoya and G. C. Velmahos
 

Hypothesis  There exist predictors of mortality and the need for colectomy among patients with fulminant Clostridium difficile colitis.

Design  Retrospective study.

Setting  Academic tertiary referral center.

Patients  We reviewed the records of 4796 inpatients diagnosed as having C difficile colitis from January 1, 1996, to December 31, 2007, and identified 199 (4.1%) with fulminant C difficile colitis, as defined by the need for colectomy or admission to the intensive care unit for C difficile colitis.

Main Outcome Measures  Risk of inpatient mortality was determined by multivariate analysis according to clinical predictors, colectomy, and medical team.

Results  The inhospital mortality rate for fulminant C difficile colitis was 34.7%. Independent predictors of mortality included the following: (1) age of 70 years or older, (2) severe leukocytosis or leukopenia (white blood cell count, ≥35 000/µL or <4000/µL) or bandemia (neutrophil bands, ≥10%), and (3) cardiorespiratory failure (intubation or vasopressors). When all 3 factors were present, the mortality rate was 57.1%; when all 3 were absent, the mortality rate was 0%. Patients who underwent colectomy had a trend toward decreased mortality rates (odds ratio, 0.49; 95% confidence interval, 0.21-1.1; P = .08). Among patients admitted primarily for fulminant C difficile colitis, care in the surgical department compared with the nonsurgical department resulted in a higher rate of operation (85.1% vs 11.2%; P < .001) and lower mortality rates (12.8% vs 39.3%; P = .001). Patients admitted directly to the surgical department had a shorter mean (SD) interval from admission to operation (0 vs 1.7 [2.8] days; P = .001).

Conclusions  Despite awareness and treatment, fulminant C difficile colitis remains a highly lethal disease. Reliable predictors of mortality exist and should be used to prompt aggressive surgical intervention. Survival rates are higher in patients who were cared for by surgical vs nonsurgical departments, possibly because of more frequent and earlier operations.

  D. E Singer , Y Chang , M. C Fang , L. H Borowsky , N. K Pomernacki , N Udaltsova and A. S. Go
 

Background— Randomized trials and observational studies support using an international normalized ratio (INR) target of 2.0 to 3.0 for preventing ischemic stroke in atrial fibrillation. We assessed whether the INR target should be adjusted based on selected patient characteristics.

Methods and Results— We conducted a case–control study nested within the ATRIA cohort’s 9217 atrial fibrillation patients taking warfarin to define the relationship between INR level and the odds of thromboembolism (TE; mainly stroke) and of intracranial hemorrhage (ICH) relative to INR 2.0 to 2.5. We identified 396 TE cases and 164 ICH cases during follow-up. Each case was compared with 4 randomly selected controls matched on calendar date and stroke risk factors using matched univariable analyses and conditional logistic regression. We explored modification of the INR–outcome relationships by the following stroke risk factors: prior stroke, age, and CHADS2 risk score. Overall, the odds of TE were low and stable above INR 1.8. Compared with INR 2.0 to 2.5, the relative odds of TE increased strikingly at INR <1.8 (eg, odds ratio, 3.72; 95% CI, 2.67 to 5.19, at INR 1.4 to 1.7). The odds of ICH increased markedly at INR values >3.5 (eg, odds ratio, 3.56; 95% CI: 1.70 to 7.46, at INR 3.6 to 4.5). The relative odds of ICH were consistently low at INR <3.6. There was no evidence of lower ICH risk at INR levels <2.0. These patterns of risk did not differ substantially by history of stroke, age, or CHADS2 risk score.

Conclusions— Our results confirm that the current standard of INR 2.0 to 3.0 for atrial fibrillation falls in the optimal INR range. Our findings do not support adjustment of INR targets according to previously defined stroke risk factors.

  M. C Fang , A. S Go , Y Chang , L. H Borowsky , N. K Pomernacki , N Udaltsova and D. E. Singer
  Background—

Although warfarin is widely recommended to prevent atrial fibrillation-related thromboembolism, many eligible patients do not take warfarin. The objective of this study was to describe factors associated with warfarin discontinuation in patients newly starting warfarin for atrial fibrillation.

Methods and Results—

We identified 4188 subjects newly starting warfarin in the Anticoagulation and Risk Factors in Atrial Fibrillation Study and tracked longitudinal warfarin use through pharmacy and laboratory databases. Data on patient characteristics, international normalized ratio (INR) tests, and incident hospitalizations for hemorrhage were obtained from clinical and laboratory databases. Multivariable Cox regression analysis was used to identify independent predictors of prolonged warfarin discontinuation, defined as ≥180 consecutive days off warfarin. Within 1 year after warfarin initiation, 26.3% of subjects discontinued therapy despite few hospitalizations for hemorrhage (2.3% of patients). The risk of discontinuation was higher in patients aged <65 years (adjusted hazard ratio [HR], 1.33 [95% CI, 1.03 to 1.72] compared to those aged ≥85 years), patients with poorer anticoagulation control (HR, 1.46 [95% CI, 1.42 to 1.49] for every 10% decrease in time in therapeutic INR range), and patients with lower stroke risk (HR, 2.54 [95% CI, 1.86 to 3.47] for CHADS2 stroke risk index of 0 compared to 4 to 6).

Conclusions—

More than 1 in 4 patients newly starting warfarin for atrial fibrillation discontinued therapy in the first year despite a low overall hemorrhage rate. Individuals deriving potentially less benefit from warfarin, including those with younger age, fewer stroke risk factors, and poorer INR control, were less likely to remain on warfarin. Maximizing the benefits of anticoagulation for atrial fibrillation depends on determining which patients are most appropriately initiated and maintained on therapy.

  E. R Park , Y Chang , V Quinn , S Regan , L Cohen , A Viguera , C Psaros , K Ross and N. Rigotti
  Introduction

The aim of this prospective repeated measures, mixed-methods observational study was to assess whether depressive, anxiety, and stress symptoms are associated with postpartum relapse to smoking.

Methods

A total of 65 women who smoked prior to pregnancy and had not smoked during the last month of pregnancy were recruited at delivery and followed for 24 weeks. Surveys administered at baseline and at 2, 6, 12, and 24 weeks postpartum assessed smoking status and symptoms of depression (Beck Depression Inventory [BDI]), anxiety (Beck Anxiety Inventory [BAI]), and stress (Perceived Stress Scale [PSS]). In-depth interviews were conducted with women who reported smoking.

Results

Although 92% of the participants reported a strong desire to stay quit, 47% resumed smoking by 24 weeks postpartum. Baseline factors associated with smoking at 24 weeks were having had a prior delivery, not being happy about the pregnancy, undergoing counseling for depression or anxiety during pregnancy, and ever having struggled with depression (p < .05). In a repeated measures regression model, the slope of BDI scores from baseline to the 12-week follow-up differed between nonsmokers and smokers (–0.12 vs. +0.11 units/week, p = .03). The slope of PSS scores also differed between nonsmokers and smokers (–0.05 vs. +0.08 units/week, p = .04). In qualitative interviews, most women who relapsed attributed their relapse and continued smoking to negative emotions.

Discussion

Among women who quit smoking during pregnancy, a worsening of depressive and stress symptoms over 12 weeks postpartum was associated with an increased risk of smoking by 24 weeks.

 
 
 
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