Faculty Bibliography
Searched for:
person:zhengh02
Total Results:
15
Physical review. D, Particles, fields, gravitation, & cosmology. 2006:73(7).DOI: 10.1103/PhysRevD.73.072002
First observations of separated atmospheric nu(mu) and (nu)over-bar(mu) events in the MINOS detector
The complete 5.4 kton MINOS far detector has been taking data since the beginning of August 2003 at a depth of 2070 meters water-equivalent in the Soudan mine, Minnesota. This paper presents the first MINOS observations of nu(mu) and (nu) over bar (mu) charged-current atmospheric neutrino interactions based on an exposure of 418 days. The ratio of upward- to downward-going events in the data is compared to the Monte Carlo expectation in the absence of neutrino oscillations, giving R(up/down)(data)/R(up/down)(MC)=0.62(-0.14)(+0.19)(stat.)+/- 0.02(sys.). An extended maximum likelihood analysis of the observed L/E distributions excludes the null hypothesis of no neutrino oscillations at the 98% confidence level. Using the curvature of the observed muons in the 1.3 T MINOS magnetic field nu(mu) and (nu) over bar (mu) interactions are separated. The ratio of (nu) over bar (mu) to nu(mu) events in the data is compared to the Monte Carlo expectation assuming neutrinos and antineutrinos oscillate in the same manner, giving R((nu) over bar mu)/nu(data)(mu)/R((nu) over bar mu)/nu(MC)(mu)=0.96(-0.27)(+0.38)(stat.)+/- 0.15(sys.), where the errors are the statistical and systematic uncertainties. Although the statistics are limited, this is the first direct observation of atmospheric neutrino interactions separately for nu(mu) and (nu) over bar (mu).
ISI:000237158500008
ISSN: 1550-7998
CID: 1971462
Arteriosclerosis, thrombosis, & vascular biology. 2005:25(8):1577-83.DOI: 10.1161/01.ATV.0000174126.28201.61
Iron stores and vascular function in voluntary blood donors
BACKGROUND: Iron is a pro-oxidant cofactor that may be linked to atherosclerosis progression. Reduction of body iron stores secondary to blood donation has been hypothesized to reduce coronary risk, but retrospective studies have yielded inconsistent findings. We sought to assess the effects of blood donation frequency on body iron stores and physiological and biochemical biomarkers of vascular function associated with atherosclerosis progression. METHODS AND RESULTS: Forty high-frequency voluntary blood donors (> or =8 donations in past 2 years) and 42 low-frequency blood donors (1 to 2 donations in past 2 years) aged 50 to 75 years were randomly selected from American Red Cross of Connecticut blood donor records. Flow-mediated dilation in the brachial artery, serum markers of iron stores, vascular inflammation and oxidative stress, and cardiac risk factors were assessed in all subjects. Serum ferritin was significantly decreased in high-frequency blood donors when compared with low-frequency blood donors (median values 17 versus 52 ng/mL; P<0.001), but hematocrit did not differ between groups. Flow-mediated dilation in the brachial artery was significantly greater in high-frequency donors when compared with low-frequency donors in univariate analysis (5.5+/-2.6% versus 3.8+/-1.6%; P=0.0003) and in multivariate analysis adjusting for cardiac risk factors and other potential confounders. Serum biomarkers of vascular inflammation did not differ between groups but 3-nitrotyrosine, a marker of oxidative stress, was decreased in high-frequency donors when compared with low-frequency donors. CONCLUSIONS: High-frequency blood donors had evidence of decreased body iron stores, decreased oxidative stress, and enhanced vascular function when compared with low-frequency donors. These findings support a potential link between blood donation and reduced cardiovascular risk that warrants further investigation in prospective outcome studies
PMID: 15961703
ISSN: 1524-4636
CID: 83199
Inhibition of angiotensin-converting enzyme and phosphodiesterase type 5 improves endothelial function in heart failure
ACE (angiotensin-converting enzyme) inhibitors and PDE5 (phosphodiesterase type 5) inhibitors have each been reported to improve endothelial function in cardiovascular disease patients, but the comparative and combined effects of these two classes have not been studied previously. We sought to characterize the acute effects of ramipril alone, sildenafil alone, or their combination on endothelial function in patients with CHF (chronic heart failure). CHF subjects (n=64) were randomized to receive placebo, 10 mg of ramipril alone, 50 mg of sildenafil alone or a combination of ramipril and sildenafil in a double-blind manner. FMD (flow-mediated dilation) of the brachial artery was determined by high-resolution ultrasound imaging before and at 1, 2 and 4 h after administration of the study drug. Ramipril alone increased FMD at 4 h compared with placebo (+2.3+/-1.3%, P=0.02). Sildenafil alone increased FMD at 1, 2 and 4 h compared with placebo (+3.9+/-1.4, +4.6+/-1.8 and +3.7+/-1.3% respectively, all P<0.02). Sildenafil in combination with ramipril increased FMD at 1, 2 and 4 h when compared with placebo (+3.5+/-1.5, +4.5+/-1.8 and +4.8+/-1.3% respectively, all P<0.03). Ramipril and sildenafil both acutely improved FMD in patients with CHF, with additive effects evident at 4 h during combination therapy. Therefore further work to characterize chronic effects of combined ACE and PDE5 inhibition on endothelial function are warranted
PMID: 15574127
ISSN: 0143-5221
CID: 83192
Arteriosclerosis, thrombosis, & vascular biology. 2002:22(7):E15-8.DOI: 10.1161/01.atv.0000023187.25914.5b
Effect of dexrazoxane on homocysteine-induced endothelial dysfunction in normal subjects
OBJECTIVE: Dexrazoxane is an antioxidant prodrug that on hydrolysis is converted into an intracellular iron chelator. We hypothesized that the antioxidant effects of dexrazoxane would prevent homocysteine-induced endothelial dysfunction in the brachial artery of normal human subjects. METHODS AND RESULTS: Ten healthy volunteers completed a randomized, double-blind, crossover study. Plasma homocysteine levels and brachial artery endothelium-dependent (flow-mediated dilation [FMD]) and endothelium-independent (sublingual nitroglycerin) responses were measured before and 4 hours after ingestion of L-methionine (100 mg/kg), preceded by intravenous administration of dexrazoxane (500 mg/m2) or placebo over 30 minutes. After placebo, oral methionine increased plasma homocysteine (from 5.1+/-0.4 micromol/L at baseline to 14.2+/-1.3 micromol/L at 4 hours, P<0.001) and decreased FMD (from 3.8+/-0.7% at baseline to 1.2+/-0.5% at 4 hours, P=0.02). Dexrazoxane did not change homocysteine concentrations after methionine administration (14.9+/-1.1 micromol/L at 4 hours, P=0.29 versus placebo) but did completely abrogate the homocysteine-induced reduction in FMD (from 3.5+/-0.5% at baseline to 5.9+/-1.1% at 4 hours, P<0.01 versus placebo). Endothelium-independent responses to sublingual nitroglycerin did not differ after the administration of placebo and dexrazoxane. CONCLUSIONS: Administration of the novel antioxidant agent dexrazoxane prevents homocysteine-induced impairment of vascular endothelial function in the brachial artery of healthy subjects
PMID: 12117747
ISSN: 1524-4636
CID: 83145
Peripheral limitations of maximal aerobic capacity in patients with chronic heart failure
PMID: 11986567
ISSN: 1071-3581
CID: 83142
