Citations

AbstractB-cell chronic lymphocytic leukemia (CLL) is characterized by accumulation of clonal lymphocytes resistant to apoptosis. We evaluated the ability of the investigational antileukemic agent adaphostin to induce apoptosis in CLL B cells and synergize with fludarabine in vitro. Analysis by annexin V/propidium iodide (PI) staining revealed that the concentration of adaphostin required to induce 50% cell death (IC50) at 24 hours was 4.2 μM (range, 1.10-11.25 μM; median, 4.25 μM; n = 29) for CLL isolates and more than 10 μM for B and T cells from healthy donors. Immunoblots demonstrated adaphostin induced poly(adenosine diphosphate-ribose) polymerase (PARP) cleavage and cleavage of caspase-3 substrates, suggesting that adaphostin induces apoptosis. Adaphostin increased the level of reactive oxygen species (ROS) within CLL B cells, and the antioxidant N-acetylcysteine blocked both adaphostin-induced ROS generation and apoptosis. Adaphostin also caused a decrease in the level of the antiapoptotic protein Bcl-2. When adaphostin was combined with fludarabine (F-ARA-AMP), a synergistic effect on cell death was observed in all 10 CLL samples. These findings not only indicate that adaphostin induces apoptosis selectively in CLL B cells through a mechanism that involves ROS generation but also demonstrate its ability to augment the effects of fludarabine. Further preclinical development of adaphostin as a novel agent for the treatment of CLL appears warranted.

Eosinophils are often dominant inflammatory cells present in the lungs of asthma patients. Nonetheless, the role of these leukocytes remains poorly understood. We have created a transgenic line of mice (PHIL) that are specifically devoid of eosinophils, but otherwise have a full complement of hematopoietically derived cells. Allergen challenge of PHIL mice demonstrated that eosinophils were required for pulmonary mucus accumulation and the airway hyperresponsiveness associated with asthma. The development of an eosinophil-less mouse now permits an unambiguous assessment of a number of human diseases that have been linked to this granulocyte, including allergic diseases, parasite infections, and tumorigenesis.

Purpose To evaluate changes in left ventricular ejection fraction (LVEF) after four cycles of adjuvant doxorubicin plus cyclophosphamide (AC) in women with human epidermal growth factor receptor 2–positive (node-positive or node-negative) breast cancer enrolled onto the North Central Cancer Treatment Group N9831 Intergroup Adjuvant Trial. Patients and Methods Patients were randomly assigned to receive standard doxorubicin (60 mg/m2) plus cyclophosphamide (600 mg/m2) every 3 weeks for four cycles followed by (1) weekly paclitaxel for 12 weeks; (2) weekly paclitaxel for 12 weeks, then weekly trastuzumab for 52 weeks; or (3) weekly paclitaxel plus trastuzumab for 12 weeks, then weekly trastuzumab for 40 weeks. LVEF was monitored before and after AC. Results Of the 1,576 eligible patients who completed AC, 1,458 had pre- and post-AC LVEF measurements taken using the same methodology (multiple-gated acquisition in 1,153 patients and echocardiogram in 305 patients). Among these 1,458 patients, 745 (51.1%) had ≤ 15% decrease in LVEF and LVEF that remained at or above the radiologic lower limit of normal (LLN); 42 patients (2.9%) had ≤ 15% decrease in LVEF and LVEF that decreased to or below the LLN; and 37 patients (2.5%) had an LVEF decrease of more than 15%. There was grade 2 LVEF toxicity in 96 (6.6%) of the 1,458 patients. Conclusion Standard AC chemotherapy is associated with frequent decreases in LVEF, which are noted when measured 3 weeks after completion of the fourth cycle. Patients are being observed to determine the long-term significance of this and the potential impact on subsequent treatment options.

Objective.To determine why people do or do not wear helmets while bicycling.Methods.A survey was conducted from August through October 1999. Two survey areas were chosen for this study: local public schools and paved bicycle trails. For the school arm of the study, 3 public elementary, middle, and high schools were selected from 3 different regions of Rochester, Minnesota, for participation in the study. For the bicycle arm of the study, 3 paved trails located in southeastern Minnesota were selected. A total of 2970 surveys were distributed to the public school system, and 463 surveys were collected from bicyclists on the paved bicycle trails. The survey population was split into 3 age categories for analysis: child (7–10), adolescent (11–19), and adult (older than 19).Results.Of the 2970 surveys distributed to Rochester public schools, 2039 (69%) were returned for analysis. Seventy-eight of the surveys that were completed in the public school system were discarded for the following reasons: age <10 years (35), insufficient completion (24), and selection of every reason for not wearing a bicycle helmet (19). A total of 463 surveys were completed on the 3 paved bicycle trails. One survey from the paved bicycle trail arm of the study was discarded because of insufficient completion. The total number of surveys used for statistical analysis was 2424. The distribution of male (52.7%) and female (47.3%) participants was similar. No significant difference in bicycle helmet use was found between genders.The age groups with the highest rate of bicycle helmet use were 50 to 59 years (62%) and older than 59 years (70%). The age groups with the lowest rate of bicycle helmet use were 11 to 19 years (31%) and 30 to 39 years (30%). The most common reasons given for not wearing a bicycle helmet were “uncomfortable,” “annoying,” “it's hot,” “don't need it,” and “don't own one.” Bicycle helmet use was significantly influenced by peer helmet use in all 3 age groups. Children also were more likely to wear a bicycle helmet when their parents wore bicycle helmets.A majority of respondents in all 3 age groups indicated that bicycle helmets provided either “moderate” or “great” protection from head injury, although significantly more adults (65.9%) than adolescents (43.9%) believed that the protection afforded by bicycle helmets was “great.” Despite this belief, a majority of adolescents and adults indicated that there was only a “slight risk” of head injury when bicycling without a helmet. Participants in all 3 categories were more likely to wear a bicycle helmet when they indicated either that there was a “great risk” of head injury when bicycling without a helmet or that helmets provided “great protection” from head injury. Adolescents and adults who believed that bicycling without a helmet put one at “great risk” for head injury also were more likely to indicate that helmets provided “great protection” from head injury.Conclusions.The prevalence of bicycle helmet use remains low despite research indicating the high level of head injury risk when bicycling without a helmet and the significant protection afforded by bicycle helmets. With the information provided by this survey, a well-designed intervention to increase the use of bicycle helmets can be implemented. Suggestions for a campaign to promote an increase in bicycle helmet use include focusing efforts on males and females between 11 and 19 years and 30 and 39 years of age; educating the public on new bicycle helmet designs that address comfort, ventilation, and fashion; educating adolescents on the significant protection from head injury afforded by bicycle helmets; and educating the public on the risk and severity of head injury associated with bicycling without a helmet. The influence of parents and peers on bicycle helmet use may be targeted through education and statements such as, “If you wear a bicycle helmet, you are not only protecting yourself, you are also helping to protect your friends and/or children.” bicycle, helmet, injury, accident, prevention.

Two of the four principal cationic proteins of the eosinophil granule, major basic protein (MBP) and eosinophil peroxidase (EPO), were shown to be platelet agonists. Both MBP and EPO evoked a dose-dependent nonlytic secretion of platelet 5-hydroxytryptamine in unstirred platelet suspensions even in the presence of 10 microM indomethacin. MBP also evoked secretion of platelet alpha granule and lysosome components. Secretion by MBP and EPO was inhibited by 1 microM PGE1, but the nature of the inhibition differed from that observed with thrombin. Thus, MBP and EPO can be classified as strong platelet agonists with a distinct mechanism of activation.

AbstractEosinophil degranulation is thought to play a pivotal role in the pathogenesis of allergic disorders. Although mouse models of allergic disorders have been used extensively to identify the contribution of eosinophils to disease, ultrastructural evidence of active granule disassembly has not been reported. In this investigation, we characterized the degree of eosinophil activation in the bone marrow, blood, lung tissue, and airways lumen [bronchoalveolar lavage fluid (BALF)] of ovalbumin-sensitized and aero-challenged wild-type and interleukin-5 transgenic mice. Degranulation was most prominent in and primarily compartmentalized to the airways lumen. Eosinophils released granule proteins by the process of piecemeal degranulation (PMD). Accordingly, recruitment and activation of eosinophils in the lung correlated with the detection of cell-free eosinophil peroxidase in BALF and with the induction of airways hyper-reactivity. As in previous studies with human eosinophils, degranulation of isolated mouse cells did not occur until after adherence to extracellular matrix. However, higher concentrations of exogenous stimuli appear to be required to trigger adherence and degranulation (piecemeal) of mouse eosinophils when compared with values reported for studies of human eosinophils. Thus, mouse eosinophils undergo PMD during allergic inflammation, and in turn, this process may contribute to pathogenesis. However, the degranulation process in the allergic lung of mice is primarily compartmentalized to the airway lumen. Understanding the mechanism of eosinophil degranulation in the airway lumen may provide important insights into how this process occurs in human respiratory diseases.

AbstractWe recently reported that chronic lymphocytic leukemia (CLL) cells synthesize and release vascular endothelial growth factor (VEGF) under normoxic and hypoxic conditions. CLL B cells also express VEGF membrane receptors (VEGF-R1 and VEGF-R2), suggesting that they use VEGF as a survival factor. To assess the mechanism of apoptosis resistance related to VEGF, we determined the impact of VEGF on CLL B cells, and we studied the impact of epigallocatechin-3-gallate (EGCG), a known receptor tyrosine kinase (RTK) inhibitor, on VEGF receptor status and viability of CLL B cells. VEGF165 significantly increased apoptotic resistance of CLL B cells, and immunoblotting revealed that VEGF-R1 and VEGF-R2 are spontaneously phosphorylated on CLL B cells. EGCG significantly increased apoptosis/cell death in 8 of 10 CLL samples measured by annexin V/propidium iodide (PI) staining. The increase in annexin V/PI staining was accompanied by caspase-3 activation and poly–adenosine diphosphate ribose polymerase (PARP) cleavage at low concentrations of EGCG (3 μg/mL). Moreover, EGCG suppressed the proteins B-cell leukemia/lymphoma-2 protein (Bcl-2), X-linked inhibitor of apoptosis protein (XIAP), and myeloid cell leukemia-1 (Mcl-1) in CLL B cells. Finally, EGCG (3-25 μg/mL) suppressed VEGF-R1 and VEGF-R2 phosphorylation, albeit incompletely. Thus, these results suggest that VEGF signaling regulates survival signals in CLL cells and that interruption of this autocrine pathway results in caspase activation and subsequent leukemic cell death.