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R Wagman

Publications and source records attributed to R Wagman.

7 recordsLinked to original sources
PubMed2002

Evaluation of respiratory movement during gated radiotherapy using film and electronic portal imaging.

PURPOSE: To evaluate the effectiveness of a commercial system(1) in reducing respiration-induced treatment uncertainty by gating the radiation delivery. METHODS AND MATERIALS: The gating system considered here measures respiration from the position of a reflective marker on the patient's chest. Respiration-triggered planning CT scans were obtained for 8 patients (4 lung, 4 liver) at the intended phase of respiration (6 at end expiration and 2 at end inspiration). In addition, fluoroscopic movies were recorded simultaneously with the respiratory waveform. During the treatment sessions, gated localization films were used to measure the position of the diaphragm relative to the vertebral bodies, which was compared to the reference digitally reconstructed radiograph derived from the respiration-triggered planning CT. Variability was quantified by the standard deviation about the mean position. We also assessed the interfraction variability of soft tissue structures during gated treatment in 2 patients using an amorphous silicon electronic portal imaging device. RESULTS: The gated localization films revealed an interfraction patient-averaged diaphragm variability of 2.8 +/- 1.0 mm (error bars indicate standard deviation in the patient population). The fluoroscopic data yielded a patient-averaged intrafraction diaphragm variability of 2.6 +/- 1.7 mm. With no gating, this intrafraction excursion became 6.9 +/- 2.1 mm. In gated localization films, the patient-averaged mean displacement of the diaphragm from the planning position was 0.0 +/- 3.9 mm. However, in 4 of the 8 patients, the mean (over localization films) displacement was >4 mm, indicating a systematic displacement in treatment position from the planned one. The position of soft tissue features observed in portal images during gated treatments over several fractions showed a mean variability between 2.6 and 5.7 mm. The intrafraction variability, however, was between 0.6 and 1.4 mm, indicating that most of the variability was due to patient setup errors rather than to respiratory motion. CONCLUSIONS: The gating system evaluated here reduces the intra- and interfraction variability of anatomy due to respiratory motion. However, systematic displacements were observed in some cases between the location of an anatomic feature at simulation and its location during treatment. Frequent monitoring is advisable with film or portal imaging.

Algorithms↗
PubMed2001

Cell autonomous apoptosis defects in acid sphingomyelinase knockout fibroblasts.

A body of evidence suggests that stress-induced sphingomyelin hydrolysis to the second messenger ceramide initiates apoptosis in some cells. Although studies using lymphoblasts from Niemann-Pick disease patients or acid sphingomyelinase (ASMase)-deficient mice have provided genetic support for this hypothesis, these models have not been universally accepted as definitive. Here, we show that mouse embryonic fibroblasts (MEFs) prepared from asmase mice manifest cell autonomous defects in apoptosis in response to several stresses. In particular, asmase(-/-) MEFs failed to generate ceramide and were totally resistant to radiation-induced apoptosis but remained sensitive to staurosporine, which did not induce ceramide. asmase(-/-) MEFs were also partially resistant to tumor necrosis factor alpha/ actinomycin D and serum withdrawal. Thus, resistance to apoptosis in asmase(-/-) MEFs was not global but rather stress type specific. Most importantly, the sensitivity to stress could be restored in the asmase(-/-) MEFs by administration of natural ceramide. Overcoming apoptosis resistance by natural ceramide is evidence that it is the lack of ceramide, not ASMase, that determines apoptosis sensitivity. The ability to rescue the apoptotic phenotype without reversing the genotype by the product of the enzymatic deficiency provides proof that ceramide is obligate for apoptosis induction in response to some stresses.

Animals↗
PubMed1999

Conservative management of rectal cancer with local excision and postoperative adjuvant therapy.

BACKGROUND: To determine the local control, survival, and functional outcome of local excision plus postoperative therapy for patients with rectal cancer. METHODS: A total of 39 patients underwent a local excision (2 with snare excision of a T1 polyp and 37 with full-thickness local excision) followed by postoperative radiation therapy +/- 5-FU-based chemotherapy. The median follow-up was 41 months, and 11 patients had positive margins. RESULTS: The 5-year actuarial colostomy-free survival was 87% and overall survival was 70%. Crude local failure increased with T stage: 0% T1, 24% T2, and 25% T3. Of the 8 patients (21%) who developed local failure, 5 underwent salvage APR and were locally controlled. Actuarial local failure at 5 years was 31% for T2 disease and 27% for the total patient group. In the 32 patients with an intact sphincter, 94% had good to excellent sphincter function. CONCLUSION: Although local failure in patients with T2 tumors has increased since our prior report, the survival, sphincter function, and local salvage rates are acceptable. Local excision and postoperative therapy remains a reasonable alternative to APR in selected patients.

Adenocarcinoma↗
PubMed1998

Sphincter preservation in rectal cancer with preoperative radiation therapy and coloanal anastomosis: long term follow-up.

BACKGROUND: To determine if preoperative radiation therapy allows sphincter preservation in the treatment of rectal cancer. METHODS: Thirty six patients with the diagnosis of invasive, resectable, primary adenocarcinoma of the rectum limited to the pelvis were enrolled on a Phase I/II trial of preoperative radiation therapy plus low anterior resection/coloanal anastomosis. By preoperative assessment, all patients had invasive tumors (5,T2; 31,T3) involving the distal half of the rectum and clinically required an abdominoperineal resection. The median tumor size was 3.8 cm [range: 1.5-7 cm] and the median distance from the anal verge was 4 cm [range: 3-7 cm]. The whole pelvis received 46.80 Gy followed by a 3.60 Gy boost to the primary tumor bed. The median follow-up was 56 months [range: 4-121 months]. RESULTS: Of the 35 patients who underwent resection, 5 (14%) had a complete pathologic response and 27 (77%) were able to successfully undergo a low anterior resection/coloanal anastomosis. The incidence of local failure was crude: 17% and 5-year actuarial: 21%. The 5-year actuarial survival was 64%. Analysis of sphincter function using a previously published scale was performed at the time of last follow-up in the 27 patients who underwent a low anterior resection/coloanal anastomosis. Function was good or excellent in 85%. The median number of bowel movements/day was 2 (range: 0-8). CONCLUSIONS: Our data suggest that preoperative radiation therapy allows sphincter preservation in 77% of selected patients who would otherwise require an abdominoperineal resection, and 85% have good to excellent sphincter function. Given the moderate local failure rate, we now routinely use preoperative combined modality therapy plus postoperative chemotherapy for patients with clinical T3 disease.

Adenocarcinoma↗
PubMed1993

Single-cell analysis of Hodgkin and Reed-Sternberg cells: molecular heterogeneity of gene expression and p53 mutations.

We have used a single-cell based polymerase chain reaction (PCR) amplification technique to examine the gene expression pattern in single Hodgkin's and Reed-Sternberg (H&RS) cells from seven patients with Hodgkin's disease. Single cells were isolated from lymph nodes obtained at diagnosis (5 of 7 patients) or in first or second relapse (2 of 7 patients). Gene expression was examined by hybridization to a panel of 22 cDNA probes. Forty-nine H&RS cells (and 23 CD3+ or CD20+ lymphocytes as controls) from four patients with nodular sclerosing Hodgkin's disease (HD) and one patient each with lymphocyte predominant and mixed-cellularity HD were successfully analyzed by PCR. This analysis provides evidence that single H&RS cells can coexpress genes characteristic of several hematopoietic lineages (monocytes and lymphocytes). Genes characteristic of activated lymphoid cells are expressed in most H&RS cells. Heterogeneity of expression for certain genes between different cases was found and may eventually define molecular subgroups of HD. These findings indicate that H&RS cells of HD resemble activated hematopoietic cells. Phenotypically similar cells from different cases exhibit characteristic molecular differences. In one patient, 5 of 7 single RS cells showed identical p53 cDNA mutations at codon 246 on specific reverse transcriptase [RT]-PCR and sequencing of exons 5 through 8. The novel experimental approach may provide a valuable tool for understanding the molecular events in newly diagnosed Hodgkin's disease and progression of the disease.

Adolescent↗