Effect of irrigation method on transmission to and persistence of Escherichia coli O157:H7 on lettuce

In this study, the transmission of Escherichia coli O157:H7 to lettuce plants through spray and surface irrigation was demonstrated. For all treatments combined, the number of plants testing positive following a single exposure to E. coli O157: H7 through spray irrigation (29 of 32 plants) was larger than the number testing positive following surface irrigation (6 of 32 plants). E. coli O157:H7 persisted on 9 of 11 plants for 20 days following spray irrigation with contaminated water. Immersion of harvested lettuce heads for 1 min in a 200 ppm chlorine solution did not eliminate all E. coli O157:H7 cells. The results of this study suggest that regardless of the irrigation method used, crops can become contaminated; therefore, the irrigation of food crops with water of unknown microbial quality should be avoided.     

Maximum-tolerated dose, toxicity, and efficacy of (131)I-Lym-1 antibody for fractionated radioimmunotherapy of non-Hodgkin's lymphoma

PURPOSE: Lym-1, a monoclonal antibody that preferentially targets malignant lymphocytes, has induced remissions in patients with non-Hodgkin's lymphoma (NHL) when labeled with iodine 131 ((131)I). Based on the strategy of fractionating the total dose, this study was designed to define the maximum-tolerated dose (MTD) and efficacy of the first two, of a maximum of four, doses of (131)I-Lym-1 given 4 weeks apart. Additionally, toxicity and radiation dosimetry were assessed. MATERIALS AND METHODS: Twenty patients with advanced NHL entered the study a total of 21 times. Thirteen (62%) of the 21 entries had diffuse large-cell histologies. All patients had disease resistant to standard therapy and had received a mean of four chemotherapy regimens. (131)I-Lym-1 was given after Lym-1 and (131)I was escalated in cohorts of patients from 40 to 100 mCi (1.5 to 3.7 GBq)/m2 body surface area. RESULTS: Mean radiation dose to the bone marrow from body and blood (131)I was 0.34 (range, 0. 1 6 to 0.63) rad/mCi (0.09 mGy/MBq; range, 0.04 to 0.17 mGy/ MBq). Dose-limiting toxicity was grade 3 to 4 thrombocytopenia with an MTD of 100 mCi/m2 (3.7 GBq/m2) for each of the first two doses of (131)I-Lym-1 given 4 weeks apart. Nonhematologic toxicities did not exceed grade 2 except for one instance of grade 3 hypotension. Ten (71 %) of 14 entries who received at least two doses of (131)I-Lym-1 therapy and 11 (52%) of 21 total entries responded. Seven of the responses were complete, with a mean duration of 14 months. All three entries in the 100 mCi/m2 (3.7 MBq/m2) cohort had complete remissions (CRs). All responders had at least a partial remission (PR) after the first therapy dose of (131)I-Lym-1. CONCLUSION: (131)I-Lym-1 induced durable remissions in patients with NHL resistant to chemotherapy and was associated with acceptable toxicity. The nonmyeloablative MTD for each of the first two doses of (131)I-Lym-1 was 100 mCi/m2 (total, 200 mCi/m2) (3.7 GBq/m2; total, 7.4 GBq/m2).     

Evaluation of atypical cytochrome P450 kinetics with two-substrate models: evidence that multiple substrates can simultaneously bind to cytochrome P450 active sites

Some cytochrome P450 catalyzed reactions show atypical kinetics, and these kinetic processes can be grouped into five categories: activation, autoactivation, partial inhibition, substrate inhibition, and biphasic saturation curves. A two-site model in which the enzyme can bind two substrate molecules simultaneously is presented which can be used to describe all of these observed kinetic properties. Sigmoidal kinetic characteristics were observed for carbamazepine metabolism by CYP3A4 and naphthalene metabolism by CYPs 2B6, 2C8, 2C9, and 3A5 as well as dapsone metabolism by CYP2C9. Naphthalene metabolism by CYP3A4 and naproxen metabolism by CYP2C9 demonstrated nonhyperbolic enzyme kinetics suggestive of a low Km, low Vmax component for the first substrate molecule and a high Km, high Vmax component for the second substrate molecule. 7, 8-Benzoflavone activation of phenanthrene metabolism by CYP3A4 and dapsone activation of flurbiprofen and naproxen metabolism by CYP2C9 were also observed. Furthermore, partial inhibition of 7, 8-benzoflavone metabolism by phenanthrene was observed. These results demonstrate that various P450 isoforms may exhibit atypical enzyme kinetics depending on the substrate(s) employed and that these results may be explained by a model which includes simultaneous binding of two substrate molecules in the active site.     

Rapid-fractionation preoperative chemoradiation, pancreaticoduodenectomy, and intraoperative radiation therapy for resectable pancreatic adenocarcinoma

PURPOSE: To evaluate the toxicities, radiographic and pathologic responses, and event-free outcomes with combined modality treatment that involves preoperative rapid-fractionation chemoradiation, pancreaticoduodenectomy, and electron-beam intraoperative radiation therapy (EB-IORT) for patients with resectable pancreatic adenocarcinoma. PATIENTS AND METHODS: Patients with radiographically resectable localized adenocarcinoma of the pancreatic head were entered onto a preoperative protocol that consisted of a 2-week course of fluorouracil (5-FU) 300 mg/m2 daily 5 days per week and concomitant rapid-fractionation radiation 30 Gy, 3 Gy daily 5 days per week. Radiographic restaging was performed 4 weeks after chemoradiation, and patients with localized disease underwent pancreaticoduodenectomy with EB-IORT 10 to 15 Gy. RESULTS: Thirty-five patients were entered onto the study and completed chemoradiation, 34 (97%) as outpatients. Three patients (9%) experienced grade 3 nausea and vomiting; no other grade 3 or 4 toxicities were observed. Of the 27 patients taken to surgery, 20 patients (74%) underwent pancreaticoduodenectomy with EB-IORT. All patients had a less than grade III pathologic response to preoperative chemoradiation. At a median follow-up of 37 months, the 3-year survival rate in patients who underwent combined modality therapy was 23%. CONCLUSION: Combined modality treatment with preoperative rapid-fractionation chemoradiation, pancreaticoduodenectomy, and EB-IORT is associated with minimal toxicity and excellent locoregional control. This represents one approach to maximize the proportion of patients who receive all components of combined modality therapy and avoids the toxicity of pancreaticoduodenectomy in patients found to have metastatic disease at the time of restaging.     

Canine neosporosis: clinical signs, diagnosis, treatment and isolation of Neospora caninum in mice and cell culture

Clinical signs, diagnosis, treatment and isolation of Neospora caninum from two littermate dogs are described. Three of six pups from a Labrador bitch developed paralysis. Neosporosis was diagnosed ante mortem by serological examination in two of the affected pups. At necropsy, tissue cysts were seen in unstained smears and in histologic sections of their brains. Tissue cysts were often thin-walled (approximately 1 micron) but antigenically and ultrastructurally identified as N. caninum. Furthermore, N. caninum (isolates NC-4, NC-5) was isolated in mice and in cell cultures inoculated with neural tissues of these two dogs. Serological diagnosis of neosporosis using a variety of tests is discussed.     

Endotoxin and cytokines increase hepatic sphingolipid biosynthesis and produce lipoproteins enriched in ceramides and sphingomyelin

Alterations in triglyceride and cholesterol metabolism often accompany inflammatory diseases and infections. We studied the effects of endotoxin (lipopolysaccharide [LPS]) and cytokines on hepatic sphingolipid synthesis, activity of serine palmitoyltransferase (SPT), the first and rate-limiting enzyme in sphingolipid synthesis, and lipoprotein sphingolipid content in Syrian hamsters. Administration of LPS induced a 2-fold increase in hepatic SPT activity. The increase in activity first occurred at 16 hours, peaked at 24 hours, and was sustained for at least 48 hours. Low doses of LPS produced maximal increases in SPT activity, with half-maximal effect seen at approximately 0.3 microg LPS/100 g body weight. LPS increased hepatic SPT mRNA levels 2-fold, suggesting that the increase in SPT activity was due to an increase in SPT mRNA. LPS treatment also produced 75% and 2.5-fold increases in hepatic sphingomyelin and ceramide synthesis, respectively. Many of the metabolic effects of LPS are mediated by cytokines. Interleukin 1 (IL-1), but not tumor necrosis factor, increased both SPT activity and mRNA levels in the liver of intact animals, whereas both IL-1 and tumor necrosis factor increased SPT mRNA levels in HepG2 cells. IL- produced a 3-fold increase in SPT mRNA in HepG2 cells, and the half-maximal dose was 2 ng/mL. IL-1 also increased the secretion of sphingolipids into the medium. Analysis of serum lipoprotein fractions demonstrated that very low density lipoprotein, intermediate density lipoprotein, and low density lipoprotein isolated from animals treated with LPS contained significantly higher amounts of ceramide, glucosylceramide, and sphingomyelin. Taken together, these results indicate that LPS and cytokines stimulate hepatic sphingolipid synthesis, which results in an altered structure of circulating lipoproteins and may promote atherogenesis.     

Managing data caches using selective cache line replacement

As processor performance continues to improve, more demands are being placed on the performance of the memory system. The caches employed in current processor designs are very similar to those described in early cache studies. In this paper, a detailed characterization of data cache behavior for individual load instructions is given. It will be shown that by selectively allocating cache lines according the characteristics of individual load instructions, overall performance can be improved for both the data cache and the memory system. This approach can improve some aspects of memory performance by as much as 60 percent on existing executables. This work was supported by National Science Foundation Grants CCR-94-03651, CCR-92-13651, CCR-92-13627, MIP-92-57259, and generous grants from the SUN Microsystems and Tektronix corporations.     

Prognostic significance of allelic losses in primary melanoma

Loss of genetic material, including loss of loci on chromosome arms 6q, 9p, and 10q, occurs frequently in cutaneous melanoma but infrequently in benign melanocytic nevi or other melanocytic lesions, suggesting that these genetic alterations are important in the development and progression of melanoma. To examine whether allelic loss is of prognostic importance in melanoma, disease-free survival was related to loss of heterozygosity on 6q, 9p and 10q in 83 individuals with sporadic primary cutaneous melanoma. Loss of chromosome arms 6q and 10q were each significantly associated with a poorer clinical outcome (P=0.013 and P=0.001 respectively). In a subgroup of 41 subjects whose primary tumours were allelotyped, the fractional allelic loss (FAL) at 39 autosomal arms also significantly correlated with disease-free survival (P=0.013), with an increase in FAL associated with a poorer outcome; this association remained significant when controlled for tumour thickness (P=0.035). In addition, a greater proportion of cells were immunopositive for Ki67 antigen, p53 and p21WAF1 protein in the primary melanomas than in the benign melanocytic nevi, however, only p53 over-expression was significantly associated with improved survival (P=0.041).