Ubiquitination capabilities in response to neocarzinostatin and H(2)O(2) stress in cell lines from patients with ataxia-telangiectasia

The human genetic disorder ataxia-telangiectasia (A-T) is due to lack of functional ATM, a protein kinase which is involved in cellular responses to DNA double strand breaks (DSBs) and possibly other oxidative stresses, as well as in regulation of several fundamental cellular functions. Studies regarding responses in A-T cells to the induction of DSBs utilize ionizing radiation or radiomimetic chemicals, such as neocarzinostatin (NCS), which induce DNA DSBs. This critical DNA lesion activates many defense systems, such as the cell cycle checkpoints. The cell cycle is also regulated through a timed and coordinated degradation of regulatory proteins via the ubiquitin pathway. Our recent studies indicate that the ubiquitin pathway is influenced by the cellular redox status and that it is the major cellular pathway for removal of oxidized proteins. Accordingly, we hypothesized that the absence of a functional ATM protein might involve perturbations to the ubiquitin pathway as well. We show here that upon treatment with NCS, there was a transient 50-70% increase in endogenous ubiquitin conjugates in A-T and wt lymphoblastoid cells. Ubiquitin conjugation capabilities per se and levels of substrates for conjugation were also similarly enhanced in wt and A-T cells upon NCS treatment. We also compared the ubiquitination response in A-T and wt cells using H(2)O(2) as the stress, in view of preexisting evidence of the effects of H(2)O(2) on ubiquitination capabilities in other types of cells. As with NCS treatment, there was an approximately 45% increase in endogenous ubiquitin conjugates by 2-4 h after exposure to H(2)O(2). Both cell types showed a rapid 50-150% increase in de novo formed 125I-ubiquitin conjugates. As compared with wt cells, unexposed A-T cells had higher endogenous levels of conjugates and enhanced conjugation capability. However, A-T cells mounted a more muted ubiquitination response to the stress. The enhanced ubiquitin conjugation in unstressed A-T cells and attenuated ability of these cells to respond to stress are consistent with the A-T cells being under oxidative stress and with their having an 'aged' phenotype. The indication that ubiquitin conjugate levels and ubiquitin conjugation capabilities are enhanced upon oxidative stress without significant changes in GSSG/GSH ratios indicates that assays of ubiquitination provide a sensitive measure of cellular stress. The data also add support to the impression that potentiated ubiquitination response to mild oxidative stress is a generalizable phenomenon.     

Association between alopecia and response to chemotherapy in patients with Hodgkin lymphoma

Alopecia and bone marrow suppression are prominent effects of doxorubicin-containing chemotherapy. The aim of the study was to validate our preliminary clinical observation that the lack of alopecia in Hodgkin lymphoma patients may predict poor response to chemotherapy and low rate of bone marrow suppression. Sixty-six patients with Hodgkin lymphoma were reviewed. They were treated between 1991 and 2001 with at least 4 courses of doxorubicin-containing chemotherapy (MOPP/ABV or ABVD) in 2 university-affiliated hematology departments. Thirty-four patients exhibited complete or near complete alopecia, and 32 retained their hair or had only minimal hair loss. The 2 groups were compared by response to treatment and episodes of bone marrow suppression. Alopecia was associated with a high rate of remission (OR 8.48, 95% CI 2.77-25.95), episodes of neutropenia (OR 3.55, 95% CI 1.28-9.84), leukopenia (OR 1.83, 95% CI 0.68-4.92), delays in scheduled treatments (OR 1.61, 95% CI 0.607-4.30), or number of courses with dose reduction (OR 1.63, 95% CI 0.56-4.74). Significantly more patients with alopecia had at least 1 of these parameters (88% versus 62%, P=0.015; OR 4.50, 95% CI 1.27-15.94). In conclusion, in patients with Hodgkin lymphoma treated with doxorubicin-containing chemotherapy, the absence of alopecia may predict poor response to treatment along with fewer episodes of bone marrow suppression. The absence of alopecia in such patients should alert clinicians to the possibility of treatment failure.     

No-touch aorta off-pump coronary surgery: the effect on stroke

OBJECTIVE: Studies examining the neuroprotective effects of off-pump coronary artery bypass grafting have shown inconsistent results. Most studies, however, have not differentiated between clampless and clamp off-pump techniques. The aim of this study was to evaluate the effect of avoiding aortic manipulation on major neurologic outcomes after off-pump coronary artery bypass grafting. METHODS: A total of 700 consecutive patients undergoing multiple-vessel off-pump coronary artery bypass grafting between 2000 and 2003 were included. The 429 patients undergoing aortic no-touch technique were compared with 271 patients in whom partial aortic clamps were applied. The aorta was screened by manual palpation, and epiaortic ultrasonography was used selectively. RESULTS: The frequency of detected atherosclerotic aortic disease was higher in the no-touch group (17.4% vs 5.1%, P < .0001). No-touch revascularization was achieved with arterial conduits, arranged in T-graft or in situ configurations (50%). The respective graft/patient ratios were 2.5 +/- 0.6 and 2.6 +/- 0.6 in the side-clamp and no-touch groups ( P = .009); however, revascularization of the posterolateral myocardial territory was comparable (87% vs 90%, difference not significant). The incidence of stroke (0.2% vs 2.2%, P = .01) was significantly lower in the no-touch group (1/429). Logistic regression identified partial aortic clamping as the only independent predictor of stroke (odds ratio 28.5, confidence interval 0.22-333, P = .009), increasing this risk 28-fold. Peripheral vascular disease ( P = .068), diabetes ( P = .072), and history of stroke ( P = .074) trended toward stroke. CONCLUSIONS: Avoiding partial aortic clamping during off-pump coronary artery bypass grafting provides superior neurologic outcome. The results are reproducible and irrespective of the severity of aortic disease or the method of aortic screening. This technique is recommended whenever technically feasible.     

Effectiveness of an herbal preparation containing echinacea, propolis, and vitamin C in preventing respiratory tract infections in children: a randomized, double-blind, placebo-controlled, multicenter study

OBJECTIVE: To evaluate the effectiveness and safety of a preparation containing echinacea, propolis, and vitamin C in the prevention of respiratory tract infections in children during a 12-week winter period. DESIGN: Randomized, double-blind, placebo-controlled study. SUBJECTS: Four hundred thirty children, aged 1 to 5 years, were randomized to an herbal extract preparation (n = 215) or a placebo elixir (n = 215). INTERVENTION: Administration of an herbal preparation (Chizukit) containing 50 mg/mL of echinacea, 50 mg/mL of propolis, and 10 mg/mL of vitamin C, or placebo (5.0 mL and 7.5 mL twice daily for ages 1 to 3 years and 4 to 5 years, respectively) for 12 weeks. RESULTS: Significant mean +/- SD reductions of illnesses were seen in the Chizukit group in the number of illness episodes, 138 vs 308 (55% reduction); number of episodes per child, 0.9 +/- 1.1 vs 1.8 +/- 1.3 (50% reduction, P<.001); and number of days with fever per child, 2.1 +/- 2.9 vs 5.4 +/- 4.4) (62% reduction, P<.001). The total number of illness days and duration of individual episodes were also significantly lower in the Chizukit group. Adverse drug reactions were rare, mild, and transient. CONCLUSION: A preventive effect of a product containing echinacea, propolis, and vitamin C on the incidence of respiratory tract infections was observed.     

Homocysteine effect on protein degradation rates

OBJECTIVES: To show the effect of homocysteine (Hcy) on the degradation rates of proteins. DESIGN AND METHODS: Degradation rates of short-lived proteins in neutrophils were measured in in vivo human model of elevated plasma Hcy and lower vitamin status and in animal model of Hcy added in vitro to rat neutrophils. RESULTS: In the human study, we found significant coefficients of correlation between plasma total homocysteine (tHcy) and the degradation rates of 21 protein fractions. In the animal model, Hcy significantly increased degradation rates of 57 protein fractions. CONCLUSIONS: The increase in protein degradation rates, induced by Hcy, may provide a clue to our understanding of the mechanism of Hcy detrimental effects. Hcy may amplify the specific effect of cellular solutes on protein conformation, thereby monitor protein degradation rates to control enzyme activity. Consequently, the cell may lose its ability to maintain an efficient control of some crucial metabolic pathways, possibly leading to atherogenesis.