An experimental model of malignant glioma growth involving implantation of spheroids into a gel matrix of collagen type I has been developed. This model has been used to characterize changes in glioma cell invasion in response to single dose and fractionated radiation treatment. Suspensions of C6 astrocytoma cells were grown in spinner culture flasks to yield spheroids of varying size (300-1000 microm). Implantation of spheroids into a gel matrix of collagen type I was associated with measurable invasion of the surrounding gel by individual tumor cells. Changes in the distance of invasion in response to single dose and fractionated radiation were measured. Changes in apoptosis and proliferative indices in different regions of the spheroids in response to radiation were also assessed. In unirradiated gels, maximum depth of invasion, 1300-1750 microm, was achieved by 5 days after implantation. A radiation dose-dependent inhibition of invasion was noted and was most profound for larger spheroids. Fractionation of the radiation dose was associated with a partial recovery of invasion. Changes in apoptotic and proliferative indices in response to radiation depended on the region of the spheroid examined. Increases in apoptosis were noted for cells at the surface of the spheroid and invading cells while cells at the centre of the spheroid demonstrated virtually no increase in apoptosis. Likewise, a dose-dependent decrease in proliferative indices following radiation was noted among the invading cells and cells at the surface of the spheroid but not at the centre of the spheroid. We have described a model of malignant glioma invasion which possesses many of the qualities of in vivo malignant gliomas. Within this model, invasion appeared to be inhibited by radiation in a dose- and fractionation-dependent fashion. Measurement of apoptotic and cell proliferation indices favour a direct cytotoxic effect on the invading cells as the most likely mechanism for this phenomenon.

Animals↗

PubMedDate not supplied

Acceptance of an injury-prevention program in rural communities: a preliminary study.

INTRODUCTION: Considerable attention is being addressed to injury prevention. This study addresses the acceptance of a home injury-prevention survey as an injury-prevention tool in rural communities. PURPOSE: The purpose of this study was to evaluate public acceptance of a home injury-prevention survey as a tool to educate and enlighten the public about home injuries. METHODS: All patients with home injuries who came to Wetzel County Hospital Emergency Department were asked if they would participate in a home injury-prevention survey. The study was conducted from 01 May to 01 July 1995. Paramedics were used as interviewers because of the closeness they enjoy with the community. RESULTS: During the study period, 2,104 patients came to the emergency department of Wetzel County Hospital. Of these, 386 sought care because of an injury sustained in their homes. From this group, 23 (5.9%) patients agreed to participate in a home injury-prevention study; 363 (94.1%) refused. CONCLUSION: A home injury-prevention survey alone does not seem to be an effective tool to aid in the reduction of home injuries, because it is not embraced by the general public.

Accidents, Home↗

PubMedDate not supplied

A case-control study to investigate the association between indices of dust exposure and the development of radiologic pneumoconiosis.

A case-control study on employees at an iron ore surface mining plant was undertaken to determine which indices of occupational dust exposure related most closely to radiologic categories for pneumoconiosis. Forty cases, with radiographs compatible with the ILO Categories (1980) for simple pneumoconiosis, were matched for age, smoking habit, and date of entry into the workforce with 80 control subjects whose radiographs were read as normal. The six indices of dust exposure were cumulative and "peak" respirable dust, quartz, and iron oxide. Both iron oxide indices were not significant at the 5% level for either ILO Category 1 or Categories 2,3. The association between dust composition and ILO radiologic category for simple pneumoconiosis was consistent, with respirable quartz being the best differentiating index between the case and control groups.

Dust↗

PubMedDate not supplied

Case report. Small bowel obstruction due to phytobezoar formation within Meckel diverticulum: CT findings.

Intestinal obstruction due to a phytobezoar within a Meckel diverticulum is exceedingly rare, with only seven reported cases in the surgical literature. The most important precipitating factor is the ingestion of agents high in fiber and cellulose. Small bowel obstruction in all but one case was due to retrograde propagation of the bezoar into the small bowel lumen. We report the clinical and CT findings in such a patient following a vegetarian diet.

Bezoars↗

PubMedDate not supplied

More realistic soil cleanup standards with dual-equilibrium desorption.

The desorption of contaminants from soils/sediments is one of the most important processes controlling contaminant transport and environmental risks. None of the currently adopted desorption models can accurately quantify desorption at relatively low concentrations; these models often overestimate the desorption and thus the risks of hydrophobic organic chemicals, such as benzene and chlorinated solvents. In reality, desorption is generally found to be biphasic, with two soil-phase compartments. A new dual-equilibrium desorption (DED) model has been developed to account for the biphasic desorption. This model has been tested using a wide range of laboratory and field data and has been used to explain key observations related to underground storage tank plumes. The DED model relates the amount of a chemical sorbed to the aqueous concentration, with simple parameters including octanol-water partition coefficient, solubility, and fractional organic carbon; thus, it is the only biphasic model, to date, that is based on readily available parameters. The DED model can be easily incorporated into standard risk and transport models. According to this model, many regulatory standards of soils and sediments could be increased without increasing the risks.

Adsorption↗