Citations

The proliferation of antigen-activated T cells is mediated by the T cell-derived growth factor, interleukin 2 (IL-2). The biochemical signaling cascades initiating IL-2-induced growth are dependent upon protein tyrosine kinase (PTK) activity. One IL-2-regulated PTK implicated in this cascade is the Src-family kinase, Fyn. Previous studies have described a physical association between Fyn and a potential downstream substrate, phosphatidylinositol 3-kinase (PI3-kinase) as well as the IL-2-dependent activation of PI3-kinase in T cells; however, the role of Fyn in IL-2-induced PI3-kinase activation remains unclear. In this report, we demonstrate that IL-2 stimulation triggers tyrosine phosphorylation of the p85 subunit of PI3-kinase in the murine T cell line, CTLL-2. Lysates prepared from growth factor-deprived and IL-2-stimulated T cells reconstituted both the binding of CTLL-2 cell-derived Fyn to and the IL-2-inducible tyrosine phosphorylation of exogenously added recombinant p85. Furthermore, overexpression of wild-type Fyn in these cells enhanced both the basal and IL-2-mediated activation of PI3-kinase. Additional studies of the Fyn-PI3-kinase interaction demonstrated that the Src homology 3 (SH3) domain of Fyn constitutes a direct binding site for the p85 subunit of PI3-kinase. These results support the notion that Fyn may be directly involved in the activation of the downstream signaling enzyme, PI3-kinase, in IL-2-stimulated T cells.

Obstructive sleep apnea (OSA) has been increasingly linked to cardiovascular disease, endothelial dysfunction, and oxidative stress, generated by repetitive nocturnal hypoxemia and reperfusion. Circulating free nitrotyrosine has been reported as a novel biomarker of nitric oxide (NO)-induced oxidative/nitrosative stress. Nitrosative stress has been implicated as a possible mechanism for development of cardiovascular diseases. We tested the hypothesis that repetitive severe hypoxemia resulting from OSA would increase NO-mediated oxidative stress. We studied 10 men with newly diagnosed moderate to severe OSA who were free of other diseases, had never been treated for OSA, and were taking no medications. Nitrotyrosine measurements, performed by liquid chromatography-tandem mass spectrometry, were made before and after untreated apneic sleep. We compared free nitrotyrosine levels in these patients with those obtained at similar times in 10 healthy male control subjects without OSA, with similar age and body mass index. Evening baseline nitrotyrosine levels were similar before sleep in the control and OSA groups [0.16 ± 0.01 and 0.15 ± 0.01 ng/ml, respectively, P = not significant (NS)]. Neither normal nor disturbed apneic sleep led to significant changes of plasma nitrotyrosine (morning levels: control group 0.14 ± 0.01 ng/ml; OSA group 0.15 ± 0.01 ng/ml, P = NS). OSA was not accompanied by increased circulating free nitrotyrosine either at baseline or after sleep. This observation suggests that repetitive hypoxemia during OSA does not result in increased NO-mediated oxidative/nitrosative stress in otherwise healthy subjects with OSA.

Purpose To evaluate the spectrum of and determine the risk factors for the development of liver toxicity (hepatopathy) after therapy with vincristine, dactinomycin, and cyclophosphamide (VAC) for rhabdomyosarcoma in children and adolescents. Patients and Methods We prospectively captured all events of hepatopathy occurring on the ongoing Children's Oncology Group intermediate risk protocol, D9803, for children with rhabdomyosarcoma. Patients enrolled onto this trial were randomly assigned to receive either VAC alone or VAC alternating with vincristine, topotecan, and cyclophosphamide. In addition, we reviewed the toxicity database and requested additional information for all patients with elevated bilirubin or transaminase levels. Risk factors were analyzed. Results Of 339 patients enrolled through August 2002, 18 developed hepatopathy. All events were captured by mandated toxicity reporting and filing of MedWatch forms, with no additional cases found after the additional search of the database. Four children died after developing this toxicity. All cases occurred after cycles of VAC (n = 16) or vincristine and cyclophosphamide with concomitant abdominal radiotherapy (n = 2). The onset of hepatopathy was 5 to 16 days from the start of a treatment cycle. For the 89 patients under 36 months of age, the risk of hepatopathy was 15%, with two deaths. For the 239 children 3 years of age or older, the risk for hepatopathy was 4%, with two deaths. Conclusion The greatest risk factor for development of hepatopathy after VAC therapy was age. Dose modifications for younger children receiving VAC therapy are recommended.

Purpose Molecular studies of colon cancer have provided insights into pathogenesis, yet it is unclear how important these markers are in predicting prognosis. This study investigated the prognostic significance of TUNEL, bcl-2, p53, proliferation marker Ki-67 and DNA mismatch repair (MMR) status in patients with Dukes' stage B2 and C colorectal adenocarcinomas. Patients and Methods Tumor tissue from 366 patients (75% Dukes' C, 25% Dukes' B2) from four randomized North Central Cancer Treatment Group phase III surgical adjuvant trials were used. Eighty-one percent of patients received adjuvant treatment, which was primarily fluorouracil (FU) based (90%). Tumor location was predominantly (87%) the colon. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), Ki-67, p53, bcl-2, and MMR were assayed using immunohistochemistry. Stage, grade, MMR, Ki-67, and previously determined flow cytometry markers (ploidy and S phase) were explored for associations with each other and with overall survival (OS) and disease-free survival (DFS). Results Univariately, stage B2, low grade, diploid, Ki-67 more than 27%, normal p53, and FU-based adjuvant treatment were significantly associated with improved OS and DFS (P < .05). After adjusting for stage, grade, and ploidy in multivariate analysis, Ki-67 remained significantly related to both OS and DFS (P < .01). Active FU-based adjuvant treatment was significant only for OS in this multivariate model. Neither bcl-2 nor TUNEL were significant. Conclusion This retrospective study indicates that Ki-67 and ploidy may have stronger prognostic impact on OS and DFS than other parameters investigated after adjusting for stage and tumor grade. Prospective studies to elucidate the mechanism and prognostic significance of these findings are necessary.

Purpose To determine the effectiveness of an infusional chemotherapy regimen in patients with HIV-associated lymphoma treated before and after the use of highly active antiretroviral therapy (HAART) in routine clinical practice. Patients and Methods Ninety-eight assessable patients with HIV-associated intermediate- or high-grade non-Hodgkin’s lymphoma received cyclophosphamide 200 mg/m2/d, doxorubicin 12.5 mg/m2/d, and etoposide 60 mg/m2/d (CDE) given by continuous intravenous infusion for 4 days (96 hours) every 4 weeks plus filgrastim. Concurrent antiretroviral treatment consisted of the nucleoside analog didanosine in the first 43 patients enrolled before December 1996 (pre-HAART group), or HAART in the remaining 55 patients enrolled after that time (HAART group). Results Complete response occurred in 44 patients (45%; 95% CI, 35% to 55%). Failure-free survival and overall survival (OS) at 2 years was 36% (95% CI, 26% to 46%) and 43% (95% CI, 33% to 53%), respectively. At the time of the analysis, 30% in the pre-HAART group were alive compared with 47% in the HAART group; when adjusted for varying length of follow-up, patients in the HAART group had improved OS (P = .039). Patients in the HAART group experienced less grade 4 nonhematologic toxicity (22% v 42%; P = .037), thrombocytopenia (31% v 52%; P = .033), and anemia (9% v 27%; P = .021), and had fewer treatment-associated deaths (0% v 10%; P = .013). Conclusion Infusional CDE is an effective and potentially curative regimen for patients with HIV-associated lymphoma. Patients treated in the HAART era have less chemotherapy-associated toxicity and improved survival.