Plasma 8-Isoprostane Concentrations in Patients with Age-Related Cataracts

Biomarkers of lipid peroxidation related to hypertension in aging

The aim of this clinical study was to evaluate the influence of aging on the levels of lipid peroxidation (quantified as thiobarbituric acid-reactive substances (TBARS) content), lipid hydroperoxide (LOOH), hexanoyl lysine (HEL), 8-iso-prostaglandin F2α (8-iso-PGF2α) and total antioxidant capacity (TAC), and determine their relationships to the demographic and cardiovascular risk factors in elderly hypertensive (HT) patients. This study consisted of four groups: two elderly groups with 30 HT patients (11 males, 19 females) and 30 normotensive healthy volunteers (15 males, 15 females), and two young groups with 30 HT patients (13 males, 17 females) and 30 normotensive healthy volunteers (12 males, 18 females). In the elderly control group, the TBARS, LOOH, HEL and 8-iso-PGF2α levels, and the carotid intima media thickness (CIMT) were significantly higher than in the young control group. The TBARS, LOOH, HEL and 8-iso-PGF2α levels and the CIMT measurements were significantly higher in the elderly HT group than in the young HT group. In addition, the TAC levels were significantly lower in the elderly and young HT groups than in the elderly and young control groups. The CIMT was significantly positively correlated with TBARS (r=0.40, P<0.001), HEL (r= 0.30, P=0.001), LOOH (r= 0.44, P<0.001) and 8-iso-PGF2α (r= 0.32, P<0.001) in all of the HT groups. It seems that in elderly patients, the LOOH and TBARS are better biomarkers of lipid peroxidation in hypertension in terms of sensitivity. In all of the HT groups, 8-iso-PGF2α had the highest sensitivity. Hypertension is associated with lipid peroxidation due to an impaired oxidant/antioxidant status. Increased lipid peroxidation and decreased antioxidants with aging indicate that peroxidative damage further increases with higher blood pressure and the aging process.

Are increased levels of systemic oxidative stress and inflammation associated with age-related cataract?

Oxidative stress and inflammation may be involved in the etiology of age-related cataract. This study is the first to investigate the association between urinary levels of 8-iso-prostaglandin F₂α (PGF₂α; as a biomarker for systemic oxidative stress in vivo) and 15-keto-dihydro-PGF₂α (as a biomarker for systemic inflammation in vivo) and risk of age-related cataract. We observed in a nested case-control study, including 258 women with incident cataract diagnosis and/or cataract extraction and 258 women without cataract, matched on age and date of urine sample collection that, women with higher levels of urinary 8-iso-PGF₂α as compared with lower levels had an increased risk of age-related cataract. There was no difference in 15-keto-dihydro-PGF₂α levels between cases and controls. Our observations lead to the hypothesis that higher systemic oxidative stress increases the risk of developing age-related cataract.

Multimarker screening of oxidative stress in aging

Aging is a complex process of organism decline in physiological functions. There is no clear theory explaining this phenomenon, but the most accepted one is the oxidative stress theory of aging. Biomarkers of oxidative stress, substances, which are formed during oxidative damage of phospholipids, proteins, and nucleic acids, are present in body fluids of diseased people as well as the healthy ones (in a physiological concentration). 8-iso prostaglandin F_2α is the most prominent biomarker of phospholipid oxidative damage, o-tyrosine, 3-chlorotyrosine, and 3-nitrotyrosine are biomarkers of protein oxidative damage, and 8-hydroxy-2^′-deoxyguanosine and 8-hydroxyguanosine are biomarkers of oxidative damage of nucleic acids. It is thought that the concentration of biomarkers increases as the age of people increases. However, the concentration of biomarkers in body fluids is very low and, therefore, it is necessary to use a sensitive analytical method. A combination of HPLC and MS was chosen to determine biomarker concentration in three groups of healthy people of a different age (twenty, forty, and sixty years) in order to find a difference among the groups.

Evaluating age-associated phenotypes in a mouse model of protein dyshomeostasis

Proteotoxicity caused by an imbalanced protein quality control surveillance system is believed to contribute to the phenotypes associated with aging as well as many neurodegenerative diseases. Understanding and monitoring the impact of proteotoxicity in these processes offers researchers keen insight into the biology of aging, as well as other conditions that share similar pathological etiologies. In Section 2, we present various technical approaches that can be used to calculate and characterize the phenotypes associated with aging that are linked to increased proteotoxicity. Methods such as the measurement of oligomer protein expression and the capacity of proteasome function are useful tools in observing both aging phenotypes and neurodegenerative diseases, both of which share the phenomenon of impaired protein homeostasis.

Smoking and the risk of age-related macular degeneration: a meta-analysis

PURPOSE

Some studies were undertaken to evaluate the association between cigarette smoking and age-related macular degeneration (AMD). This meta-analysis summarized the risk estimate of smoking and AMD and provided robust evidence for the association.

METHODS

Relevant studies were identified by searching PubMed and MEDLINE (from 1966 to June 2007) and reviewing the reference lists of key articles. The summary relative risk ratio (RR) or odds ratio (OR) and 95% confidence interval (CI) were calculated. Study-specific risk estimates were pooled using a random-effects model.

RESULTS

Five prospective cohort and eight case-control studies met our inclusion criteria. Ever smoking was statistically significant associated with increased risk of AMD among cohort studies (RR, 1.61; 95% CI, 1.01-2.57) or case-control studies (RR, 1.76; 95% CI, 1.56-1.99). Current smokers were at higher risk of AMD than past smokers. Both geographic atrophy (GA) and neovascular AMD (NV) are subtypes of AMD. A significant relationship was found between smoking and GA risk. Smoking increased the risk of NV, with marginal nonsignificance (RR, 1.47; 95% CI, 0.92-2.37) in cohort studies and significance in case-control studies (RR, 1.96; 95% CI, 1.69-2.27).

CONCLUSIONS

This meta-analysis indicated smoking, especially current smoking, was significantly associated with increased risks of AMD and its subtypes.

Inhibitive effect of genistein on hypoxia-induced basic fibroblast growth factor expression in human retinal pigment epithelium cells

AIM

The time course changes of basic fibroblast growth factor (bFGF) expression induced by hypoxia and the effects of genistein on hypoxia-induced bFGF expression in the human retinal pigment epithelium (RPE) cells were studied.

METHODS

The bFGF mRNA expression was examined by reverse transcription polymerase chain reaction. The bFGF protein expression was detected by Western blot.

RESULTS

Hypoxia significantly increased bFGF mRNA expression. The maximal level detected at 24 h was approximately two times that at the start of treatment. With pretreatment of genistein (10, 20, 50, 100, and 200 microM) for 30 min, the elevated expression of bFGF mRNA was suppressed in a concentration-dependent manner. bFGF mRNA expression was reduced to 30.4% by 200 microM of genistein when compared with that untreated with genistein. Hypoxia treatment also remarkably increased the expression of bFGF protein. At 24 h after hypoxia, when the highest expression of bFGF protein was observed, it was approximately two times as much as that at the start of treatment. Genistein (10, 20, 50, 100, and 200 microM) could also suppress bFGF protein expression in a concentration-dependent manner. The highest suppression was observed when exposed to 200 microM of genistein, which was 43% of control.

CONCLUSIONS

These results suggested that suppression of bFGF expression in RPE cells might partly account for the inhibitive effect of genistein on retinal neovascularization in vivo.

Pegaptanib for the treatment of age-related macular degeneration

Although neovascular (wet) age-related macular degeneration (AMD) only accounts for 10-20% of all AMD, the majority (about 90%) of severe vision loss associated with AMD is due to this form. Results from recent studies have implied that vascular endothelial growth factor (VEGF), particularly VEGF(165), plays a predominant role in the development of ocular neovascularization and vascular leakage secondary to AMD. Thus VEGF is an important therapeutic target in neovascular AMD. Pegaptanib, an anti-VEGF aptamer, can selectively bind with VEGF(165) and inhibit both the growth of blood vessels and vascular leakage, and was approved by the Food and Drug Administration in the United States as the therapy for the treatment of all subtypes of neovascular AMD in December 2004. This review summaries the mechanism, preclinical and clinical studies, and adverse events of pegaptanib treatment.