2'-Deoxycytidine glycols, a missing link in the free radical-mediated oxidation of DNA.

2'-Deoxycytidine glycols (5,6-dihydroxy-5, 6-dihydro-2'-deoxycytidine) are major products of the hydroxyl radical-induced oxidation of 2'-deoxycytidine resulting from either a Fenton reaction or exposure to ionizing radiation. Because of their instability, however, the glycols have not previously been characterized. Instead, the impetus has been placed on the primary decomposition products of 2'-deoxycytidine glycols, which includes 5-hydroxy-2'-deoxycytidine, 5-hydroxy-2'-deoxyuridine, and 2'-deoxyuridine glycols.

Age-related impairment of p56lck and ZAP-70 activities in human T lymphocytes activated through the TcR/CD3 complex.

Cellular immune responses decrease with aging. Lymphocytes of aged individuals do not perform as well as cells from young subjects in a number of in vitro assays including cell proliferation, cytokine production, and protection against apoptosis. Here, we have tested the hypothesis that a decrease in T cell responses in tymphocytes from elderly subjects could parallel a decrease in the activity of protein tyrosine kinases (PTK) associated with signal transduction in T lymphocytes.

Effects of a cross-training exercise program in persons with osteoarthritis of the knee a randomized controlled trial.

This study was designed to evaluate, by means of a randomized controlled trial, the effects of a physical activity program incorporating aerobic, strength, and stretching exercises in individuals with osteoarthritis of the knee. We randomly assigned 137 volunteers ages >/=50 to an experimental group or a control group. The experimental group participated in three 1-hour sessions of supervised exercises per week over a 3-month period.

Glutathione and ascorbate are negatively correlated with oxidative DNA damage in human lymphocytes.

Intracellular antioxidants, glutathione and ascorbate, and two molecular markers of oxidative DNA damage, 5-hydroxy-2'-deoxycytidine (5-OH-dCyd) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGuo), were measured in lymphocytes from 105 healthy volunteers. The analysis of 5-OH-dCyd and 8-oxo-dGuo was carried out by HPLC with electrochemical detection such that both compounds were detected on the same chromatography run. There was no significant difference in oxidative DNA damage when the extraction of DNA from cells using phenol was carried out under anaerobic conditions or in the presence of metal ion chelators.

Age-related increased susceptibility of high-density lipoproteins (HDL) to in vitro oxidation induced by gamma-radiolysis of water.

In the present study, we investigated the age-related susceptibility of high-density lipoproteins (HDL) to oxidation. HDL were obtained from healthy, normolipidemic young, middle-aged and elderly subjects. Oxidation of HDL was induced in vitro by oxygen free radicals generated by water gamma-radiolysis, and followed by the decrease of endogenous vitamin E and the formation of conjugated dienes and thiobarbituric acid-reactive substances, as well as the alterations of apolipoproteins A-I/A-II.

A weight-bearing, water-based exercise program for osteopenic women: its impact on bone, functional fitness, and well-being.

Objective: To evaluate the effects of a weight-bearing, water-based, exercise program designed for women with low bone mass.

Design: A test-retest cross-sectional, prospective study.

Setting: Community-dwelling women from a Canadian city.

Isometric grip endurance of healthy elderly men and women.

Grip endurance is one of the important prerequisites for good performance of the upper extremity and hence it is important to evaluate it correctly. However, we know little about normal grip endurance, especially for elderly people. The main objective of this study was to examine the age-related changes in grip isometric endurance of healthy community-dwelling elderly people.

Incorporation of two deoxycytidine oxidation products into cellular DNA.

The oxidation of cytosine in DNA by free radicals and other oxidants leads to an assortment of products including pyrimidine ring 5,6-saturated, 5,6-unsaturated, contraction, and fragmentation products. The formation of these products in cellular DNA may explain in part the preponderance of C to T transitions induced spontaneously and by H2O2 or ionizing radiation. Our studies have focused on the biological effects of two major 5,6-unsaturated oxidation products of cytosine: 5- hydroxycytosine and 5-hydroxyuracil.