Multichannel detectors for profile measurements in clinical proton fields

Two beam profile measurement detectors have been developed at Indiana University Cyclotron Facility to address the need for a tool to efficiently verify dose distributions created with active methods of clinical proton beam delivery. The multipad ionization chamber (MPIC) has 128 ionization chambers arranged in one plane and is designed to measure lateral profiles in fields up to 38 cm in diameter. The MPIC pads have a 5 mm pitch for fields up to 20 cm in diameter and a 7 mm pitch for larger fields, providing the accuracy of field size determination about 0.5 mm. The multilayer ionization chamber (MLIC) detector contains 122 small-volume ionization chambers stacked at a 1.82 mm step (water-equivalent) for depth-dose profile measurements. The MLIC detector can measure profiles up to 20 cm in depth, and determine the 80% distal dose fall-off with about 0.1 mm precision. Both detectors can be connected to the same set of electronics modules, which comprise the detectors' data acquisition system. The detectors have been tested in clinical proton fields produced with active methods of beam delivery such as uniform scanning and energy stacking. This article describes detector performance tests and discusses their results. The test results indicate that the MPIC and MLIC detectors can be used for dosimetric characterization of clinical proton fields. The detectors offer significant time savings during measurements in actively delivered beams compared with traditional measurements using a water phantom.     

The nasal mucosa in softwood exposed furniture workers

Recent reports suggest that softwood exposed woodworkers may have an increased incidence of sinonasal carcinoma. The present study was undertaken in order to evaluate the histological changes, especially the presence of possible precancerous lesions, in the nasal mucosa of furniture workers exclusively exposed to softwood. Histological examination of nasal biopsies from 44 furniture workers and 37 controls revealed a higher degree of metaplastic changes in the former group. In addition we observed four cases (9%) of dysplasia among softwood exposed workers. Nasal epithelial dysplasia is morphologically similar to dysplasia in other organs where the precancerous state of this lesion has been proved. Acceptance of nasal dysplasia as a precancerous lesion means that histological examination of biopsies is an appropriate tool in identifying occupational groups with an increased incidence of sinonasal carcinoma.     

Chemiluminescence by polymorphonuclear leukocytes from patients with active bacterial infection

Polymorphonuclear leukocytes of 18 patients during 19 episodes of active bacterial infection produced increased chemiluminescence (mean +/- standard error [SE], 56.3 +/- 4.4 X 10(3) cpm) when the production was compared to that of 29 uninfected controls (35.3 +/- 2.4 X 10(3) cpm; P less than 0.01). Chemiluminescence production remained increased with persistent infection but fell to the levels of controls with appropriate therapy. Phagocytic uptake as determined with radiolabeled bacteria was increased, and chemotactic responsiveness was markedly enhanced in the patients (mean index +/- SE, 260 +/- 51) when these responses were compared with those of controls (77 +/- 18). Chemiluminescence and chemotactic activity correlated in the patients with bacterial infection (r = 0.76), but one function did not appear to depend upon the intactness of the other. The ratio of cyclic guanosine 3',5'-phosphate to cyclic adenosine 3',5'-hosphate in the polymorphonuclear leukocytes of patients with infections (mean +/- SE, 0.102 +/- 0.0008) was also significantly higher than in controls (0.067 +/- 0.007). These data indicate that the polymorphonuclear leukocytes of the majority of patients with active bacterial infection are in an activated state both functionally and metabolically.     

Histopathological outcome in 167 patients operated on with radical retropubic prostatectomy

OBJECTIVE: To evaluate the histopathological outcome in patients with prostate cancer operated on with radical retropubic prostatectomy. MATERIAL AND METHODS: A total of 167 patients with clinically organ-localized prostate cancer treated with open radical retropubic prostatectomy between 1996 and 2001 were divided into three equally sized consecutive cohorts (cohorts I-III). The prostatectomy specimens were re-examined by two pathologists with respect to pathological tumour stage, tumour grade and surgical tumour margins. RESULTS: The mean preoperative prostate-specific antigen (PSA) value was statistically significantly higher in cohort I compared to cohorts II and III: 13.2, 9.0 and 8.5 ng/ml, respectively (p<0.05). The incidence of locally advanced (pT3a-3b) tumours was 44% in cohort I and 20% in both cohorts II and III (p<0.05). The incidence of positive tumour margins was 58% in cohort I, compared to 30% in cohort II and 13% in cohort III (p<0.05). The incidence of positive intracapsular tumour margins was 55% in cohort I, compared to 25% in cohort II and 8.9% in cohort III (p<0.05). The incidence of positive tumour margins in the pT2 tumours in cohorts I-III was 57%, 26% and 8.9%, respectively (p<0.05). Cohort III had significantly more low-grade tumours (Gleason score 4-6; 58.9%) compared to cohorts I (31.5%) and II (34%). There was a higher incidence of Gleason score >or=7 in the pT3 tumours compared to the pT2 tumours (80% vs 46%) and in margin-positive compared to -negative tumours (69.6% vs 48.6%) (p<0.05). CONCLUSIONS: The decline in pT3 tumours and positive tumour margins between cohorts I-III is probably due to a gradually more strict selection of patients for radical retropubic prostatectomy. The successive reduction in positive intracapsular tumour margins is most likely due to an improved surgical technique.     

Measurement of nursing care time of specific interventions on a hematology-oncology unit related to diagnostic categories

The aim of this study was to develop a tool that can aid nurse managers in planning nurse staffing levels and assessing workload in hematology-oncology wards. A task-oriented method based on a time-and-motion study was used. Three general nursing procedures and 7 specific oncologic and hematologic activities were clocked. It was checked in the charts of the patient, for each day of the admission, how often selected nursing procedures were performed. Then total amount of time needed for each patient was calculated. Data from 29 admissions to the ward were analyzed and divided into 5 categories based upon the treatment performed during that admission. The categories chosen were: autologous stem cell transplantation, allogeneic stem cell transplantation, graft versus host reaction, leukemia treatment, and chemotherapy for solid neoplasm. The results obtained are an estimate of the different daily workload that is required for these categories of patients in selected nursing procedures.     

Biologic aspects of thrombopoietins and the development of therapeutic agents

Thrombopoiesis is a multistage process beginning with pluripotent hematopoietic stem cells, progressing through proliferating cells committed to megakaryocytopoiesis, to megakaryocytes, and eventually ending with the shedding of platelets from megakaryocytes. Many growth factors stimulate thrombopoiesis; this review addresses those that act through binding to the thrombopoietin receptor. The cloning of thrombopoietin in 1994 greatly accelerated progress in understanding the biology of thrombopoiesis and of hematopoiesis in general. Detailed structural and functional studies of the thrombopoietin receptor, coupled with novel molecular pharmacology approaches, have led to new classes of thrombopoietic mimetics. Initial clinical trials with recombinant thrombopoietins faltered as they encountered significant neutralizing antibodies or difficulty finding a significant clinical niche in support of chemotherapy. Ongoing studies with the new thrombopoietic agents have invigorated the field, with positive results now reported in idiopathic thrombocytopenic purpura.