4-Hydroxynonenal regulates mitochondrial function in human small airway epithelial cells

Prolonged exposure to oxidative stress causes Acute Lung Injury (ALI) and significantly impairs pulmonary function. Previously we have demonstrated that mitochondrial dysfunction is a key pathological factor in hyperoxic ALI. While it is known that hyperoxia induces the production of stable, but toxic 4-hydroxynonenal (4-HNE) molecule, it is unknown how the reactive aldehyde disrupts mitochondrial function. Our previous in vivo study indicated that exposure to hyperoxia significantly increases 4-HNE-Protein adducts, as well as levels of MDA in total lung homogenates. Based on the in vivo studies, we explored the effects of 4-HNE in human small airway epithelial cells (SAECs). Human SAECs treated with 25 μM of 4-HNE showed a significant decrease in cellular viability and increased caspase-3 activity. Moreover, 4-HNE treated SAECs showed impaired mitochondrial function and energy production indicated by reduced ATP levels, mitochondrial membrane potential, and aconitase activity. This was followed by a significant decrease in mitochondrial oxygen consumption and depletion of the reserve capacity. The direct effect of 4-HNE on the mitochondrial respiratory chain was confirmed using Rotenone. Furthermore, SAECs treated with 25 μM 4-HNE showed a time-dependent depletion of total Thioredoxin (Trx) proteins and Trx activity. Taken together, our results indicate that 4-HNE induces cellular and mitochondrial dysfunction in human SAECs, leading to an impaired endogenous antioxidant response.     

Risk factors for urological symptoms in a cohort of users of the HIV protease inhibitor indinavir sulfate: the ATHENA cohort

BACKGROUND: Nephrolithiasis is a well-known complication of indinavir treatment and may result in urological symptoms ranging from renal colic to renal insufficiency. OBJECTIVE: To obtain further knowledge regarding the incidence and risk factors of urological symptoms associated with indinavir sulfate use. METHODS: This study was performed in the ATHENA (AIDS Therapy Evaluation National AIDS Therapy Evaluation Centre) cohort of patients infected with human immunodeficiency virus (HIV) receiving antiretroviral therapy in the Netherlands. The incidence rate of urological symptoms was assessed in a subcohort of 1219 patients starting HIV protease inhibitor treatment after 1996. Urological symptoms were defined as an initial report of nephrolithiasis, renal colic, flank pain, hematuria, renal insufficiency, or nephropathy. Using multivariate Cox regression analysis, risk factors for urological symptoms during indinavir treatment were subsequently studied among the subset of 644 patients who started indinavir treatment after 1996. RESULTS: The incidence of urological symptoms was 8.3 per 100 treatment-years for indinavir vs 0.8 per 100 treatment-years for other HIV protease inhibitors. Risk factors for urological symptoms during indinavir treatment were low weight (relative risk [RR], 2.1; 95% confidence interval [CI], 1.1-3.9), low lean body mass (RR, 1.7; 95% CI, 1.0-2.9), undetectable HIV-1 RNA when starting indinavir treatment (RR, 3.2; 95% CI, 1.5-6.0), prior treatment change because of intolerance (RR, 2.4; 95% CI, 1.2-5.1), indinavir regimens of 1000 mg or more twice daily (RR, 3.1; 95% CI, 1.3-8.2), and warm environmental temperatures (RR, 3.9; 95% CI, 1.7-8.8). Risk estimates were highest among patients with a low lean body mass. CONCLUSION: Increased alertness for urological symptoms is warranted for patients starting indinavir treatment, particularly among those with a low lean body mass, during indinavir regimens of 1000 mg or more twice daily, and in warm weather environments.     

Effects of melatonin on the cell cycle kinetics and "estrogen-rescue" of MCF-7 human breast cancer cells in culture

Melatonin has been shown to have a direct inhibitory action on the proliferation of estrogen-responsive MCF-7 human breast cancer cells in culture. In the present study, we examined by flow cytometry whether this inhibitory effect might be exerted on the G1 phase of the cell cycle, thus causing a transition delay into the S phase. In order to further verify this hypothesis we tested the ability of estradiol to "rescue" MCF-7 cells from melatonin inhibition, and the potential of this indoleamine to block the ability of estradiol to rescue the cells from tamoxifen inhibition. Following five days of incubation, melatonin (10(-9)M) increased the fraction of cells in G1 of the cell cycle while simultaneously causing a 50% reduction in the proportion of cells in S phase. The antiproliferative effect of melatonin (10(-5)M) was prevented by the simultaneous treatment of the cells with estradiol (10(-8)M) in clonogenic soft agar culture, or reversed by the addition of estradiol to cells previously incubated with and inhibited by melatonin (10(-9)M) in monolayer culture. Additionally, melatonin blocked the estrogen-rescue of tamoxifen-inhibited cells in both types of culture systems. These results support the hypothesis that the antiproliferative effect of melatonin, like tamoxifen, is cell cycle specific by causing a G1-S transition delay. These results also indicate an important interaction of melatonin with estrogen-mediated mechanisms of MCF-7 cell proliferation.