Upward movement of tritium from contaminated groundwaters: a numerical analysis.

This paper describes a research-oriented modelling exercise that addresses the problem of assessing the movement of tritium from a contaminated perched aquifer to the land surface. Participants were provided with information on water table depth, soil characteristics, hourly meteorological and evapotranspiration data. They were asked to predict the upward migration of tritium through the unsaturated soil into the atmosphere. Eight different numerical models were used to calculate the movement of tritium. The modelling results agree within a factor of two, if very small time and space increments are used. The agreement is not so good when the near-surface soil becomes dry. The modelling of the alternate upward and downward transport of tritium close to the ground surface generally requires rather complex models and detailed input because tritium concentration varies sharply over short distances and is very sensitive to many interactive factors including rainfall amount, evapotranspiration rate, rooting depth and water table position.

A biosphere modeling methodology for dose assessments of the potential Yucca Mountain deep geological high level radioactive waste repository.

Recent developments in performance standards for proposed high level radioactive waste disposal at Yucca Mountain suggest that health risk or dose rate limits will likely be part of future standards. Approaches to the development of biosphere modeling and dose assessments for Yucca Mountain have been relatively lacking in previous performance assessments due to the absence of such a requirement. This paper describes a practical methodology used to develop a biosphere model appropriate for calculating doses from use of well water by hypothetical individuals due to discharges of contaminated groundwater into a deep well. The biosphere model methodology, developed in parallel with the BIOMOVS II international study, allows a transparent recording of the decisions at each step, from the specification of the biosphere assessment context through to model development and analysis of results. A list of features, events, and processes relevant to Yucca Mountain was recorded and an interaction matrix developed to help identify relationships between them. Special consideration was given to critical/potential exposure group issues and approaches. The conceptual model of the biosphere system was then developed, based on the interaction matrix, to show how radionuclides migrate and accumulate in the biosphere media and result in potential exposure pathways. A mathematical dose assessment model was specified using the flexible AMBER software application, which allows users to construct their own compartment models. The starting point for the biosphere calculations was a unit flux of each radionuclide from the groundwater in the geosphere into the drinking water in the well. For each of the 26 radionuclides considered, the most significant exposure pathways for hypothetical individuals were identified. For 14 of the radionuclides, the primary exposure pathways were identified as consumption of various crops and animal products following assumed agricultural use of the contaminated water derived from the deep well. Inhalation of dust (11 radionuclides) and external irradiation (1 radionuclide) were also identified as significant exposure modes. Contribution to the total flux to dose conversion factor from the drinking water pathway for each radionuclide was also assessed and for most radionuclides was found to be less than 10% of the total flux to dose conversion factor summed across all pathways. Some of the uncertainties related to the results were considered. The biosphere modeling results have been applied within an EPRI Total Systems Performance Assessment of Yucca Mountain. Conclusions and recommendations for future performance assessments are provided.

Hepatozoon griseisciuri in grey squirrels (Sciurus carolinensis): changes of blood leucocyte numbers resulting from infection.

Numbers of leucocytes in squirrels with gametocytes of Hepatozoon in their blood (infected) were compared with animals without gametocytes (uninfected). Typical values for leucocytes/mm3 blood in uninfected squirrels were: leucocytes 5.7 x 10(3), granulocytes 3.4 x 10(3), lymphocytes 2.0 x 10(3) and monocytes 0.3 x 10(3) cells. Infection caused an increase in monocytes, lymphocytes and granulocytes, and there was a significant positive association between parasitaemia level and numbers of both total leucocytes and monocytes. Infected animals had more uninfected monocytes/mm3 blood than did uninfected animals. The proportions of monocytes were more variable over time in infected animals, but no shift between infected and uninfected status was detected. Transfer of serum from infected squirrels to mice resulted in elevated counts of total blood leucocytes, monocytes and granulocytes, but not of lymphocytes, as compared with controls. Serum from squirrels with high parasitaemias had a more marked effect than serum from squirrels with low parasitaemias. Results indicate an infection-related monocytosis, possibly controlled by cytokines, that increases the number of cells available for invasion by gametocytes, thus enhancing the chances of parasite transmission.

Delayed presentation of pericardial rupture with luxation of the heart following blunt trauma: a case report.

OBJECTIVE: To present an unusual case of delayed presentation of pericardial rupture with luxation of the heart 6 months after the initial injury. DESIGN: Diagnosis, outcome, associated injuries, and treatment are discussed. METHODS: A high index of suspicion is required to make the diagnosis; no single diagnostic test can be used as a screening tool. CONCLUSION: Once recognized, treatment of pericardial rupture is relatively simple.

Delayed gastric ulcer healing after extirpation of submandibular glands is sex-dependent.

This study examines the effect of excision of the submandibular salivary glands, the main source of epidermal growth factor (EGF), and the role of gender on the healing of acetic acid-induced gastric ulcers in rats. In male rats excision of the submandibular glands delayed ulcer healing. At 15 and 25 days the unhealed ulcer areas were significantly larger in the sialoadenectomy group than in control animals, and fewer completely healed ulcers were seen in this group at 25 days. Ulcer healing in female rats was slower. At day 25 ulcers were healed in 12% of female rats with intact salivary glands, compared with 68% in males. Female rats also showed larger unhealed ulcer areas after sialoadenectomy than controls. We conclude that removal of the main source of EGF in the gastrointestinal tract is associated with a delay in healing of gastric ulcers. The significant difference in healing observed between female and male rats may be influenced by the known androgenic regulation of EGF production in the salivary glands.

Nonsteroidal-induced benign strictures of the colon: a case report and review of the literature.

Colonic strictures are a rare complication reported to result from chronic use of sustained release formulations of indomethacin and diclofenac. Such strictures often present with associated mucosal ulceration and are thought to result from nonsteroidal antiinflammatory drug-induced alterations in enterocyte homeostasis. Strictures generally occur in the cecum, ascending, and proximal transverse colon with symptoms of occult blood loss, obstruction, changes in bowel habits, and rarely, perforation. The first reported case of a 69-year-old woman who developed recurrent colonic strictures with inflammatory changes and mucosal ulceration while taking Lodine (etodolac) is presented. A brief review of the relevant literature and suggested preventative therapies are discussed.