Comparison between two policy strategies for scheduling trucks in a biomass logistic system.

Approximately 75% of the cost to load, haul, and deliver a weekly supply of herbaceous biomass from temporary storage locations near the production fields to a bioprocessing plant (50Mg/h average capacity, 24/7 operation) is truck cost. The management policy that a bioprocessing plant uses to schedule trucks determines the maximum number of trucks required, and thereby, the total cost for the logistic system. Three land use rates corresponding to 50%, 45%, and 40% of existing pastureland within a 3.2-km radius of chosen satellite storage locations were used to establish a production base surrounding the plant location. Total area harvested was 25,500 ha, or about 2.1% of the total land area in the 7-county region studied. Assumed average yield was 8.3Mg/ha. Two different management policies, one based on travel time (Policy 1) and another based on the assignment of trucks to given sectors of the surrounding production base (Policy 2) were used to develop truck schedules. The logistic system was modeled as a discrete event simulation model, and the schedule was validated. The maximum number of trucks needed for the logistic system was 32, 33 and 34 for 50%, 45% and 40% land use rates, respectively. In Policy 1, the maximum number of loads accumulated in the at-plant inventory was 384 truckloads at 50% land use rate (maximum inventory corresponds to about 3 days of plant operation). In Policy 2, the maximum number of loads accumulated in the at-plant inventory was 330 truckloads at 50% land use rate. Total number of loader and unloader operating hours for both the policies was computed, and the loader and unloader utilization rates were 83.5% and 70.8%, respectively. The delivered cost (load, haul, and unload) varied from USD14.68 (Policy 1) to USD16.14 per Mg (Policy 2) for 15% w.b. moisture content biomass.

Scale-up of microbubble dispersion generator for aerobic fermentation.

A laboratory-scale microbubble dispersion (MBD) generator was shown to improve oxygen transfer to aerobic microorganisms when coupled to the conventional air-sparger. However, the process was not demonstrated on a large scale to prove its practical application. We investigated the scale-up of a spinning-disk MBD generator for the aerobic fermentation of Saccharomyces cerevisiae (baker's yeast). A 1-L spinning-disk MBD generator was used to supply air for 1- and 50-L working volume fermentation of baker's yeast. For the two levels investigated, the MBD generator maintained an adequate supply of surfactant-stabilized air microbubbles to the microorganisms at a relatively low agitation rate (150 rpm). There was a significant improvement in oxygen transfer to the microorganism relative to the conventional sparger. The volumetric mass transfer coefficient, kLa, for the MBD system at 150 rpm was 765 h(-1) compared to 937 h(-1) for the conventional sparger at 500 rpm. It is plausible to surmise that fermentation using larger working volumes may further improve the kLa values and the dissolved oxygen (DO) levels because of longer hold-up times and, consequently, improve cell growth. There was no statistically significant difference between the cell mass yield on substrate (0.43 g/g) under the MBD regime at an agitation rate of 150 rpm and that achieved for the conventional air-sparged system (0.53 g/g) at an agitation rate of 500 rpm. The total power consumption per unit volume of broth in the 50-L conventional air-sparged system was threefold that for the MBD unit for a similar product yield. Practical application of the MBD technology can be expected to reduce power consumption and therefore operating costs for aerobic fermentation.

Parathyroid adenoma after radioactive iodine therapy for multinodular goiter.

The development of hyperparathyroidism after radioactive iodine (RAI) therapy has been reported in 38 cases in the literature. However, the development of a parathyroid adenoma after RAI therapy for a hyperfunctioning multinodular goiter has not been reported. This report describes the pathologic and operative finding on a patient with both hyperthyroidism and hyperparathyroidism, which was diagnosed after previous RAI therapy for a toxic, multinodular goiter.

Studies using recombinant fragments of human TSH receptor reveal apparent diversity in the binding specificities of antibodies that block TSH binding to its receptor or stimulate thyroid hormone production.

Patients with Graves' disease have autoantibodies that bind to the TSH receptor and stimulate the thyroid, leading to hyperthyroidism. Earlier studies have shown that the ectodomain of the glycosylated human TSH receptor contains epitopes that could adsorb these pathogenic antibodies. Further studies with mutated cDNAs, chimeric proteins, peptides, and antipeptide antibodies suggested that alterations in the conformation of the protein could lead to loss of reactivity, and that thyroid-stimulating antibodies interact with the N-terminal region of the TSH receptor. Although many of these studies provided valuable insights, they were somewhat inconclusive due to limitations inherent to each of the approaches. In an attempt to further define regions within the TSH receptor with which thyroid-stimulating antibodies interact, we expressed seven recombinant TSH receptor fragments in insect cells and tested them for their ability to neutralize TSH binding inhibitory Igs and thyroid-stimulating antibody activity in the sera of patients with Graves' disease. The fragments containing amino acids 22-305 were able to neutralize the TSH binding inhibitory Ig activity, whereas a fragment containing amino acids 54-254 was able to neutralize the thyroid-stimulating antibodies. Fragments containing additional amino acids, flanking residues 54-254, failed to neutralize the thyroid-stimulating antibody activity, suggesting that thyroid-stimulating antibody epitopes are masked. Our studies show that thyroid autoantibodies, with different functional properties, bind to distinct conformational epitopes on the TSH receptor.

Immunotoxicology of cigarette smoke condensates: suppression of macrophage responsiveness to interferon gamma.

We have investigated systematically the effects of short-term exposure to main stream cigarette smoke condensates (CSC-MS) on basal and inducible functional capacities of murine peritoneal exudate macrophages. Macrophages treated with CSC-MS form granules that fluoresce orange under blue excitation, consistent with the speculation that they are polycyclic aromatic hydrocarbons (PAH). CSC-MS selectively suppressed interferon gamma (IFN gamma) induction of four macrophage functional capacities: enhanced phagocytosis of immunoglobulin-opsonized sheep red blood cells, TPA-induced H2O2 production, class II major histocompatibility complex expression, and nitric oxide synthesis. In contrast, two macrophage functions that are not induced by IFN gamma, basal electron transport and LPS-induced TNF alpha production, were enhanced by treatment with CSC-MS. These results suggest that the suppressive effects of CSC-MS on macrophage responsiveness were selective and were not due to nonspecific inhibition of general functions such as RNA or protein synthesis. Since macrophage responsiveness to IFN gamma can result in induction of functional capacities that are fundamental to immunity, the data suggest that CSC-MS maybe deleterious to the general health of the smoker.

Postirradiation sarcomas in Sprague-Dawley rats.

A series of radiation-induced neoplasms occurred in Sprague-Dawley rats 4-8 months after irradiation of a single hind leg with 60Co gamma rays. The rats were exposed to fractionated cumulative doses that ranged from 0 to 106 Gy. Osteosarcomas, malignant fibrous histiocytomas and fibrosarcomas developed in the radiation fields of a number of the rats in the higher-dose groups. Tumors did not develop throughout an 8-month observation period in rats that received doses of only 0 or 46 Gy. The most common postirradiation sarcomas in humans are osteosarcoma, malignant fibrous histiocytoma and fibrosarcoma. The Sprague-Dawley rat may serve as a good animal model in studying the development of sarcoma in humans after regional radiotherapy.

Utilization of thermoluminescent dosimetry in total skin electron beam radiotherapy of mycosis fungoides.

PURPOSE: The purpose of this report is to discuss the utilization of thermoluminescent dosimetry (TLD) in total skin electron beam (TSEB) radiotherapy to: (a) compare patient dose distributions for similar techniques on different machines, (b) confirm beam calibration and monitor unit calculations, (c) provide data for making clinical decisions, and (d) study reasons for variations in individual dose readings. METHODS AND MATERIALS: We report dosimetric results for 72 cases of mycosis fungoides, using similar irradiation techniques on two different linear accelerators. All patients were treated using a modified Stanford 6-field technique. In vivo TLD was done on all patients, and the data for all patients treated on both machines was collected into a database for analysis. Means and standard deviations (SDs) were computed for all locations. Scatter plots of doses vs. height, weight, and obesity index were generated, and correlation coefficients with these variables were computed. RESULTS: The TLD results show that our current TSEB implementation is dosimetrically equivalent to the previous implementation, and that our beam calibration technique and monitor unit calculation is accurate. Correlations with obesity index were significant at several sites. Individual TLD results allow us to customize the boost treatment for each patient, in addition to revealing patient positioning problems and/or systematic variations in dose caused by patient variability. The data agree well with previously published TLD results for similar TSEB techniques. CONCLUSION: TLD is an important part of the treatment planning and quality assurance programs for TSEB, and routine use of TLD measurements for TSEB is recommended.

Ocular surface upregulation of intercellular adhesive molecule-1 (ICAM-1) by local interferon-gamma (IFN-gamma) in the rat.

Inflammatory mediators such as interferon-gamma (IFN-gamma) are known to induce the expression of class II HLA (HLA-DR) and intercellular adhesion molecule 1 (ICAM-1) in a variety of cell types including epithelial cells. The coexpression of ICAM-1 and HLA-DR has been implicated in the pathogenesis of immune mediated ocular disease. We investigated the expression of ICAM-1 on the ocular surface of the rat eye following subconjunctival administration of IFN-gamma. A dose response study was performed using 100, 1,000 and 10,000 IU IFN-gamma/dose. The presence of ICAM-1 was determined using a standard immuno-peroxidase staining technique. The cornea, limbus, and conjunctiva were evaluated. The degree of reaction product in each area was graded by a masked observer. We found constitutive expression of ICAM-1 on the conjunctiva but not on the cornea. There was a significant relationship between the dose of IFN-gamma and the intensity of ICAM-1 staining on the conjunctiva (p < or = 0.05) and on the limbus (p < or = 0.04). Subconjunctival IFN-gamma had no effect on the expression of ICAM-1 in the cornea.

The use of radiochromic film to measure dose distributions resulting from high dose rate 192Iridium single catheter treatments.

PURPOSE: Radiochromic film was used to measure and compare the dose distributions parallel to a high dose rate (HDR) 192Iridium (192Ir) brachytherapy afterloading catheter that resulted from optimized treatment plans using various combinations of prescribed dose magnitude and location as well as source spacing. METHODS AND MATERIALS: Differences exist among clinical investigators for specification of the magnitude and location of prescribed treatment dose for brachytherapy irradiations using HDR 192Ir afterloading. Typical prescriptions for endobronchial irradiation include 5 to 10 Gy at 10 mm or 15 Gy at 6 mm measured from the center of the afterloading catheter. The dose distributions that result from these irradiations are very difficult to quantify by conventional dosimetry methods. This study used radiochromic film to measure the dose distributions resulting from optimized treatment plans for source dwell position separations of 2.5 or 5.0 mm and for a prescribed treatment dose of either 15 Gy at 6 mm or 5 Gy at 10 mm, conditions that have been used at M. D. Anderson Cancer Center for the treatment of endobronchial lesions. An acrylic phantom was designed to allow for measurement of the dose distributions at 0.95 mm (catheter surface), 6 mm, and 10 mm from and parallel to the catheter for sources positioned along either 20 or 80 mm of the catheter. RESULTS: Radiochromic film is shown to be a suitable quality assurance and dosimetry modality for the measurement of the dose distribution along an afterloading catheter resulting from an HDR I92Ir source. Each of the treatment plans was about equally effective in being able to produce a uniform dose distribution at their respective planned target distances. Differences were more apparent when comparing the dose distributions at nontargeted distances. On the catheter surface the dose was very nonuniform and in the case of 2.5 mm source spacing along 20 mm of catheter with target dose planned to 10 mm, the central minimum dose was only 13 to 24% of the dose opposite to the most proximal and distal sources. The absolute doses measured at equivalent distances for the 15 Gy planned to 6 mm treatments are about 1.3 to 1.5 times higher than those measured for the 5 Gy planned to 10 mm treatments. It was also observed that the lateral positioning of the encapsulated source within the afterloading catheter can contribute to dose differences about the catheter that are greatest for measurements made in contact with the catheter surface (24 to 40%) but may also be large at the treatment planning distances of 6 (0 to 15%) and 10 mm (0 to 9%). CONCLUSION: At their respective treatment planning distances of 6 or 10 mm, each of the treatment plans produced dose distributions of comparable uniformity. Against the catheter, relatively more uniform dose distributions with higher minimum doses were obtained for (a) dose prescription at 6 mm, rather than at 10 mm; (b) source separation of 2.5 mm, rather than 5.0 mm (except for a 20 mm active catheter length with dose planned to 10 mm); and (c) longer active length of the catheter of 80 mm, rather than 20 mm.

Fetal dose from radiotherapy with photon beams: report of AAPM Radiation Therapy Committee Task Group No. 36.

Approximately 4000 women per year in the United States require radiotherapy during pregnancy. This report presents data and techniques that allow the medical physicist to estimate the radiation dose the fetus will receive and to reduce this dose with appropriate shielding. Out-of-beam data are presented for a variety of photon beams, including cobalt-60 gamma rays and x rays from 4 to 18 MV. Designs for simple and inexpensive to more complex and expensive types of shielding equipment are described. Clinical examples show that proper shielding can reduce the radiation dose to the fetus by 50%. In addition, a review of the biological aspects of irradiation enables estimates of the risks of lethality, growth retardation, mental retardation, malformation, sterility, cancer induction, and genetic defects to the fetus.

High dose endobronchial irradiation in recurrent bronchogenic carcinoma.

Between November 1988 and March 1990, 24 patients with endobronchial tumors that had recurred after external beam radiation therapy were treated with high dose rate intraluminal irradiation. A remote afterloading high dose rate unit was used, and most patients received two endobronchial treatments, separated by a two week interval. All patients were given the same dose and dose specification to assess the feasibility and complications of the therapy. At each treatment, 15 Gy were delivered with dose specified at a radius of 6 mm from the center of the source, which corresponds to a dose of 9 Gy at a radius of 1 cm. Overall, 21 of 24 patients (88%) showed good symptomatic improvement. Of 18 patients whose chest x-ray showed evidence of collapse or atelectasis caused by tumor obstruction, 15 (83%) had evidence of reaeration. The median duration of palliation, marked by symptoms or a chest x-ray that worsened, was 26 weeks, the range varying from seven to 40 weeks. No patient died as a result of therapy and only one had a complication, bronchospasm, which responded well to bronchodilators. One patient died of hemoptysis approximately three months after treatment. Five additional patients, who were treated off protocol because they had an Eastern Cooperative Oncology Group performance status of greater than two, also received endobronchial irradiation. All five died within one month from worsening pulmonary disease, and we do not recommend endobronchial irradiation for patients with an Eastern Cooperative Oncology Group performance status of greater than two. We conclude that high dose rate endobronchial brachytherapy effectively relieves the symptoms of endobronchial obstruction due to recurrent lung cancer and can be given safely as an outpatient procedure. As the complications were minimal in this series treated with a uniform dose of 15 Gy per treatment, future studies should aim at determining the maximum tolerated dose. This technique may also be helpful as a boost after maximal external beam irradiation or to open up areas of atelectasis prior to external beam irradiation.

Radiotherapy during pregnancy for clinical stages IA-IIA Hodgkin's disease.

Between 1956 and 1990, 775 women were treated for Hodgkin's disease at The University of Texas M.D. Anderson Cancer Center. Of these, 25 (3.2%) were pregnant at diagnosis. Seven of these women were in the first trimester, 10 in the second, and eight in the third. Prior to treatment, three women in the third trimester had normal deliveries, and six patients in the first trimester had abortions. Sixteen patients received radiotherapy for supradiaphragmatic presentations during their pregnancies. All these patients had nodular sclerosing Hodgkin's disease: Two had clinical stage IA presentations and 14 had clinical stage IIA. In two patients radiotherapy (35 Gy) was limited to the neck, three patients were treated definitively to the neck and mediastinum (40 Gy), and 11 patients received mantle irradiation (40 Gy). Four to five half-value layers of lead were used to shield the uterus during radiotherapy. The dose to the fetus was estimated individually in nine patients, using a combination of an Alderson-Rando and a water phantom. The estimated total dose to the mid-fetus ranged from 1.4 to 5.5 cGy for treatment with 6 MV photons, and from 10 to 13.6 cGy for Cobalt 60. All 16 patients subsequently delivered full-term, normal infants. Following delivery, all of the patients had further staging procedures; eight received additional treatment. Subsequently, the disease relapsed in four patients; two eventually died of Hodgkin's disease. The 10-year determinant and overall survival rates were 83% and 71%, respectively. Currently, all offspring are physically and mentally normal, and none has developed a malignancy. Radiotherapy is an appropriate initial treatment for supradiaphragmatic presentations of Hodgkin's disease during the second and third trimesters of pregnancy, provided special attention is paid to treatment and shielding techniques. The outcome for women treated with irradiation for clinical stage I and II Hodgkin's disease during pregnancy has not been shown to be adversely affected by pregnancy, and after the first 8 weeks of gestation, the risk to the fetus appears to be minimal.

Umbilical artery Doppler flow studies during pregnancy.

The fetus depends upon adequate uteroplacental blood flow for normal growth and development. Inaccessibility of the fetus has made assessment of uteroplacental blood flow difficult. Doppler ultrasound of umbilical artery blood flow provides a noninvasive method for assessing pregnancies at risk for poor outcomes. This article describes blood flow studies using the Doppler ultrasound technique and provides related nursing implications.

Recovery of spermatogenesis after treatment for Hodgkin's disease: limiting dose of MOPP chemotherapy.

The sperm production of 25 patients with Hodgkin's disease treated with mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) chemotherapy was studied retrospectively. All but two patients also received radiotherapy treatment to pelvic and/or non-pelvic fields. Sperm counts were obtained from patients treated either with three or fewer (MOPP-2 group) or with five or more (MOPP-6 group) chemotherapy cycles. Recovery of spermatogenesis following treatment-induced azoospermia was significantly higher among the MOPP-2 patients (Mann-Whitney rank sum test, p = 0.001). Patients in this group who did not receive pelvic irradiation appeared to have greater recovery rates (p = 0.06). The results suggest that three cycles of MOPP chemotherapy represent a maximum exposure compatible with the recovery of spermatogenesis.

Endocrine profiles of patients with testicular tumors treated with radiotherapy.

Blood samples for hormone analysis were obtained 5 to 20 years post-therapy from 12 men with testicular tumors who were originally treated by unilateral orchiectomy followed by abdominal and/or pelvic irradiation. In nine patients (75%) the levels of FSH and LH, and in one patient (8%) the testosterone values, were outside the ranges found in age- and sex-matched controls. From this retrospective study we conclude that, even when the remaining testis is kept outside the field of radiation, significant radiation damage occurs, mainly through scatter. This damage is more likely to occur if the hemiscrotum is irradiated. Methods of shielding are available to reduce the dose received by the contralateral testis.

Directional dependence of radiation fluence from 192Ir and 198Au sources.

Radiation fluence distribution around 192Ir and 198Au seeds of the type used for brachytherapy application was measured using a NaI crystal connected to a multi-channel analyzer. The radiation fluence, determined as a function of the angle between the seed axis and the direction of detection, is anisotropic with the fluence along the seed axis amounting to 78% of that perpendicular to the seed axis for seeds of both isotopes. The region of fluence reduction is broader for 198Au seeds, extending from 0-45 degrees; for 192Ir the decrease in fluence is evident for angles of 0-20 degrees. Integration of the angular distribution over 4 pi geometry indicated the effective activity of the implants to be 4% and 1% less than the nominal activity for the 198Au and 192Ir seeds, respectively, based on calibration measurements perpendicular to the seed axis.

Dose enhancement from backscattered radiation at tissue-metal interfaces irradiated with high energy electrons.

Irradiation of a tissue-metal interface with 13 MeV to 20 MeV electrons results in an increased dose to the tissue on the entrance side of the metal. Ionization measurements were made with a thin-window parallel-plate chamber to determine the magnitude of the dose enhancement as a function of incident electron energy, thickness and atomic number of metals introduced into the electron beam. The presence of a metal resulted in a dose ranging from 6% to approximately 50% greater than that measured with no metal in the beam. Most of this increase in dose may be eliminated by the addition of 1-2 g/cm2 of low Z material between tissue and metal.