Biomedical subjects

G-S Ying

Publications and source records attributed to G-S Ying.

4 recordsLinked to original sources

PubMed2006

Effect of systemic hypertension on foveolar choroidal blood flow in age related macular degeneration.

AIM: To investigate the effect of systemic hypertension (SH) on the foveolar choroidal circulation in patients with age related macular degeneration (AMD). METHODS: This study included 163 study eyes with early AMD characteristics of 124 AMD patients. Study eyes had visual acuity of 20/40 or better, drusen > or =63 microm, and/or RPE hypertrophy. 56 of the AMD patients had a history of SH and 47 of these patients were receiving antihypertensive medications. Laser Doppler flowmetry (Oculix) was used to assess relative choroidal blood velocity (ChBVel), volume (ChBVol), and flow (ChBFlow) in the centre of the fovea of the study eyes. Differences in the mean haemodynamic parameters between groups of eyes were assessed using analysis of variance (ANOVA) and a test of linear trend, with adjustment for the correlation between eyes of the same patient. RESULTS: AMD patients with SH showed decreased ChBFlow in comparison with those without SH (ANOVA, p = 0.02). This association was maintained after adjustments for multiple factors (p = 0.04). CONCLUSIONS: AMD patients with SH have lower ChBFlow than those without SH. This decrease in choroidal blood circulation may help explain the mechanism by which systemic hypertension may contribute to the progression of AMD and the development of choroidal neovascularisation.

Aged↗

PubMed2004

Deficiency of Bax and Bak protects photoreceptors from light damage in vivo.

Photoreceptors of bax(-/-)bak(-/-) but neither bax(-/-) mice nor bak(-/-) mice are protected from developmental apoptosis, suggesting that bax(-/-)bak(-/-) photoreceptors may also be protected from pathologic apoptosis. To test this possibility, we exposed bax(-/-)bak(-/-) and bax(-/-) mice to bright light, which normally induces photoreceptor death. Photoreceptors in bax(-/-)bak(-/-) mice were protected from death compared to bax(-/-) mice as indicated by a reduction in the number of TUNEL-positive photoreceptor nuclei 24 h following light damage and almost complete preservation of photoreceptors 7 days following light damage. These results provide the first in vivo evidence that combined deficiency of Bax and Bak can rescue cells from a pathologic stimulus more effectively than Bax deficiency and suggest that combined deficiency of Bax and Bak may also protect cells from other insults.

Animals↗

PubMed2004

Effect of niacin on the choroidal circulation of patients with age related macular degeneration.

AIM: To investigate the effects of niacin on choroidal blood flow in age related macular degeneration (AMD). METHODS: 12 AMD patients with bilateral drusen and visual acuity of 20/40 or better in the study eye received a single oral dose of niacin (six subjects received 500 mg and six received 250 mg) or matching placebo on two separate occasions. Laser Doppler flowmetry was used to assess relative choroidal blood velocity (ChB(Vel)), volume (ChB(Vol)), and flow (ChB(Flow)) in the foveola of the study eye at baseline, 30, and 90 minutes after dosing. RESULTS: In comparison with placebo, a statistically significant 24% increase in ChB(Vol) was observed 30 minutes after niacin administration (ANOVA, p = 0.01). In comparison with placebo, a significant decrease in ChB(Vel) of 23% was observed in the 500 mg group (p = 0.04) and no significant change in ChB(Vel) was seen in the 250 mg group at 30 minutes. No significant changes in ChB(Flow) were detected at 30 or 90 minutes. Also, there were no statistically significant changes in ChB(Vol) or ChB(Vel) at 90 minutes. CONCLUSION: In comparison with placebo, a significant 24% increase in ChB(Vol) was observed 30 minutes after niacin administration. Owing to simultaneous decrease in ChB(Vel), however, no significant change in ChB(Flow) was detected.

Administration, Oral↗

PubMed2003

Contrast letter acuity as a visual component for the Multiple Sclerosis Functional Composite.

BACKGROUND: Visual dysfunction is one of the most common causes of disability in multiple sclerosis (MS). The Multiple Sclerosis Functional Composite (MSFC), a new clinical trial outcome measure, does not currently include a test of visual function. OBJECTIVE: To examine contrast letter acuity as a candidate visual function test for the MSFC. METHODS: Binocular contrast letter acuity testing (Sloan charts) was performed in a subgroup of participants from the International Multiple Sclerosis Secondary Progressive Avonex Controlled Trial (IMPACT Substudy) and in MS patients and disease-free control subjects from a cross-sectional study of visual outcome measures (Multiple Sclerosis Vision Prospective cohort [MVP cohort]). High-contrast visual acuity was measured in both studies; MVP cohort participants underwent additional binocular testing for contrast sensitivity (Pelli-Robson chart), color vision (D-15 desaturated test), and visual field (Esterman test, Humphrey Field Analyzer II). RESULTS: Contrast letter acuity (Sloan charts, p < 0.0001, receiver operating characteristic curve analysis) and contrast sensitivity (Pelli-Robson chart, p = 0.003) best distinguished MS patients from disease-free control subjects in the MVP cohort. Correlations of Sloan chart scores with MSFC and Expanded Disability Statue Scale (EDSS) scores in both studies were significant and moderate in magnitude, demonstrating that Sloan chart scores reflect visual and neurologic dysfunction not entirely captured by the EDSS or MSFC. CONCLUSIONS: Among clinical measures, contrast letter acuity (Sloan charts) and contrast sensitivity (Pelli-Robson chart) demonstrate the greatest capacity to identify binocular visual dysfunction in MS. Sloan chart testing also captures unique aspects of neurologic dysfunction not captured by current EDSS or MSFC components, making it a strong candidate visual function test for the MSFC.

Adult↗