Giving prophylactic platelets at a threshold of < or = 10,000/microL compared with < or = 20,000/microL can decrease the total utilization of platelets with only a small adverse effect on bleeding, and no statistically significant effect on morbidity.

Oxidizability of lipids in homogeneous solution varies linearly with the extent of their unsaturation. In vitro cellular, as well as in vivo, studies of oxidizability have generally relied upon chemical indicators of peroxidation such as thiobarbituric acid-reactive substances. To examine the oxidizability of lipids in cells, we have measured oxygen uptake and, using electron paramagnetic resonance spin trapping with alpha-(1-oxo-4-pyridyl)-N-tert-butylnitrone (POBN), the real time generation of lipid-derived free radicals. We have used our experimental in vitro cellular lipid modification model to examine the rate and extent of lipid peroxidation versus the degree of lipid unsaturation in L1210 murine leukemia cells. Lipid peroxidation was stimulated using the prooxidants iron, ascorbate, and the ether lipid compound 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine. We did a total cellular lipid analysis to determine the number of lipid carbon-carbon double bonds contained in L1210 cells enriched with eight fatty acids of different degrees of unsaturation. We found in cellular lipids that (i) lipid chain length had no apparent effect on the rate or extent of radical formation; (ii) the maximum amount of lipid radical generated increases with the total number of bis-allylic positions in the cellular lipids; and, most importantly, (iii) the rate of cellular lipid peroxidation increases exponentially with the number of bis-allylic positions. Our quantitative results clearly demonstrate, for the first time, that the number of bis-allylic positions contained in the cellular lipids of intact cells determines their susceptibility, i.e., oxidizability, to free radical-mediated peroxidative events.

The goal of this phase II multicenter clinical trial was to evaluate a new intensive chemotherapy program for adults with untreated acute lymphoblastic leukemia (ALL) and to examine prospectively the impact of clinical and biologic characteristics on the outcome. One hundred ninety-seven eligible and evaluable patients (16 to 80 years of age; median, 32 years of age) received cyclophosphamide, daunorubicin, vincristine, prednisone, and L-asparaginase; 167 patients (85%) achieved a complete remission (CR), 13 (7%) had refractory disease, and 17 (9%) died during induction. A higher CR rate was observed in younger patients (94% for those < 30 years old, 85% for those 30 to 59 years old, and 39% for those > or = 60 years old, P < .001) and in those who had a mediastinal mass (100%) or blasts with a T-cell immunophenotype. Eighty percent of B-lineage and 97% of T-cell ALL patients achieved a CR (P = .01). The coexpression of myeloid antigens did not affect the response rate or duration. Seventy percent of those with cytogenetic or molecular evidence of the Philadelphia (Ph) chromosome and 84% of those without such evidence achieved a CR (P = .11). Patients in remission received multiagent consolidation treatment, central nervous system prophylaxis, late intensification, and maintenance chemotherapy for a total of 24 months. After a median follow-up time of 43 months, the median survival for all 197 patients is 36 months; the median remission duration for the 167 CR patients is 29 months. Favorable pretreatment characteristics relative to remission duration or survival are younger age, the presence of a mediastinal mass or lymphadenopathy, a white blood cell count (WBC) less than 30,000/microL, L1 morphology, T or TMy immunophenotype, and the absence of the Ph chromosome. The estimates of the proportion surviving at 3 years are 69% for patients less than 30 years old, 39% for those 30 to 59 years old, 89% for those who had a mediastinal mass, 59% with WBC less than 30,000/microL, 63% with L1 morphology, 69% for T or TMy antigen expression, and 62% for those who lack the Ph chromosome. Fifteen patients (8%) had no unfavorable prognostic factors and have an estimated probability of survival at 5 years of 100% (95% confidence interval, 77% to 100%). This intensive chemotherapy regimen produces a high remission rate and a high proportion of durable remissions in adults with ALL.

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We examined the mechanism of H 2 O 2 -induced cytotoxicity and its relationship to oxidation in human leukemia cells. The HL-60 promyelocytic leukemia cell line was sensitive to H 2 O 2 , and at concentrations up to about 20 -25 M, the killing was mediated by apoptosis. There was limited evidence of lipid peroxidation, suggesting that the effects of H 2 O 2 do not involve hydroxyl radical. When HL-60 cells were exposed to H 2 O 2 in the presence of the spin trap ␣-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN), we detected a 12-line electron paramagnetic resonance spectrum assigned to the POBN/POBN ⅐ N-centered spin adduct previously described in peroxidase-containing cell-free systems. Generation of this radical by HL-60 cells had the same H 2 O 2 concentration dependence as initiation of apoptosis. In contrast, studies with the K562 human erythroleukemia cell line, which is often used for comparison with the HL-60, and with high passaged HL-60 cells (spent HL-60) studied under the same conditions failed to generate POBN ⅐ . Cellular levels of antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase did not explain the differences between these cell lines. Interestingly, the K562 and spent HL-60 cells, which did not generate the radical, also failed to undergo H 2 O 2 -induced apoptosis. Based on this we reasoned that the difference in H 2 O 2 -induced apoptosis might be due to the enzyme myeloperoxidase. Only the apoptosismanifesting HL-60 cells contained appreciable immunoreactive protein or enzymatic activity of this cellular enzyme. When HL-60 cells were incubated with methimazole or 4-aminobenzoic acid hydrazide, which are inhibitors of myeloperoxidase, they no longer underwent H 2 O 2 -induced apoptosis. Hypochlorous acid stimulated apoptosis in both HL-60 and spent HL-60 cells, indicating that another oxidant generated by myeloperoxidase induces apoptosis and that it may be the direct mediator of H 2 O 2 -induced apoptosis. Taken together these observations indicate that H 2 O 2 -induced apoptosis in the HL-60 human leukemia cell is mediated by myeloperoxidase and is linked to a non-Fenton oxidative event marked by POBN ⅐ .

We studied the effect of doxorubicin on the production of hydrogen peroxide by PC3 human prostate cancer cells, using a sensitive assay based on aminotriazole-mediated inhibition of catalase. PC3 cells exposed to increasing concentrations of doxorubicin had an increase in intracellular hydrogen peroxide that was concentration-dependent up to 1 μM doxorubicin. The apparent hydrogen peroxide concentration in the PC3 cells was 13 ± 4 pM under basal steady-state conditions and increased to 51 ± 13 pM after exposure to 1 μM doxorubicin for 30 min. The level of hydrogen peroxide in the medium as measured by Amplex Red did not increase as a result of doxorubicin treatment. PC3 cells overexpressing catalase were no more resistant to doxorubicin cytotoxicity as compared to non-transduced wild-type cells; therefore, the exact role of hydrogen peroxide in anthracycline cytotoxicity remains unproven. This study demonstrates that a specific oxidative event associated with the exposure of PC3 human prostate cancer cells to anthracyclines results in an increase in intracellular hydrogen peroxide. KeywordsHydrogen peroxide; Doxorubicin; PC3 cells; Catalase; Transduction; Amplex Red; Oxidative stress; Aminotriazole; Fluorescent probes; Reactive oxygen species There are reports that suggest that anthracycline anti-cancer drugs may increase the intracellular production of hydrogen peroxide. The metabolic reductive activation of doxorubicin to a semiquinone (Eq. 1) stimulates production of superoxide by the oneelectron reduction of oxygen (Eq. 2) [1]. The dismutation of the resulting superoxide,

BACKGROUNDThe authors undertook a multiinstitutional Phase II cooperative group study to examine the potential of oral fish oil fatty acid supplements administered at high doses to slow weight loss and to improve quality of life in patients with malignancy‐related cachexia.METHODSPatients with advanced malignancy and weight loss ≥ 2% of body weight in the preceding month took concentrated, high‐dose omega‐3 fatty acid capsules (7.5 g eicosapentaenoic acid plus docosahexaenoic acid for a 70 kg individual) that were supplied by the National Institutes of Health.RESULTSForty‐three patients with moderate or severe malnutrition were enrolled. The median time receiving treatment was 1.2 months. For the 36 patients who took at least 1 capsule and did not have edema, there was a weight change ranging from −6.2 kg to +3.5 kg and an overall median weight loss of 0.8 kg. Twenty‐four patients had weight stabilization (a gain of ≤ 5% or a loss of < 5%), 6 patients gained > 5% of their body weight, and 6 patients lost ≥ 5% of their body weight. There was marked variability in the tolerability of the capsules, and many patients had gastrointestinal side effects. There was a correlation between time receiving treatment and weight gain for the 22 patients who were able to tolerate the capsules for at least 1 month. Quality‐of‐life scores were superior for patients who gained weight.CONCLUSIONSA majority of patients did not gain weight, and in that sense, the results of the study were unfavorable. However, a small but definite subset of patients had weight stabilization or weight gain. This suggests that omega‐3 fatty acids have potential utility at the study doses, which were more than twice the doses used in published Phase III studies. Cancer 2004. © 2004 American Cancer Society.

Initiation of DNA synthesis in confluent quiescent 3T3 cell cultures stimulated by epidermal growth factor (EGF), vasopressin, and insulin was abolished by removing extracellular Na' . The inhibition was reversible, time-and Na'-concentration-dependent, and not due to an effect on binding or internalization of 125 1-EGF . Stimulation by combinations of other growth factors with diffrent mechanisms of action was also affected by decreasing extracellular Na', but with different half-maximal Na' concentrations . When choline was used as an osmotic substitute for Na', the decrease in DNA synthesis was correlated with the decrease in intracellular K+ . In contrast, when sucrose was used there was stimulation of the Na'-K' pump and maintenance of intracellular K+ that resulted in a somewhat higher rate of DNA synthesis at lowered extracellular Na' compared to choline . Mitogenesis induced by epidermal growth factor, vasopressin, and insulin led to cytoplasmic alkalinization as determined by an increase in uptake of the weak acid 5,5-dimethyloxazolidine-2,4-dione . Experimental decrease in extracellular Na' blocked this cellular alkalinization . Therefore, under some conditions the supply of extracellular Na' may limit cellular proliferation because of a reduction in the provision of Na' to the Na+/H+ antiport and resultant failure of alkalinization . We conclude that Na' flux and its effect on intracellular K and pH has a major role in the complex system that regulates proliferation .