Computer based simulation models are increasingly being used to predict the environmental fate of crop protection chemicals. Some considerations that need to be given in selecting appropriate models ...for regulatory purposes include model applicability, validation, capability, ease of use, and documentation. Problems commonly encountered in modeling include limited accuracy, lack of defined objectives and standard modeling practices, and misuse of models and results. Models will continue to play an important role in the regulation of crop protection chemicals. It is important that regulators and industry agree on appropriate models and practices, and that regulatory decisions are not based solely on model results but take into account all available data.
A cell line (LCC-18) from a neuroendocrine colonic tumour was established. The tumour cells retained their endocrine characteristics through more than 100 passages and showed positive ...immunocytochemistry for synaptophysin, vasoactive intestinal polypeptide (VIP) and glucagon. The culture medium also contained VIP and glucagon, which indicates that mechanisms for release of some of the active peptides were preserved. Transplantation of LCC-18 tumour cells into nude rats resulted in tumour formation with similar endocrine characteristics. The c-myc gene was amplified which might have been a prerequisite for establishment of the cell line. The chromosomes in LCC-18 were studied by G-banding and C-banding. The cell line had a distinctive mode in the hypotriploid region, at S = 61. The double minute (Dms) positive stemline karyotype showed numerical and structural aberrations more similar to findings in ordinary colonic adenocarcinomas than to observations in previously studied, pure intestinal neuroendocrine tumours. The Dms may be correlated with amplification of c-myc. LCC-18 may become valuable for studies of neuroendocrine differentiation, regulation of growth and production and release of hormones and for studies of drug effect.
Two new assays have been developed to measure tumor-associated antigens designated ovarian serum antigen (OSA) and cancer-associated serum antigen (CASA). Both assays are dual epitope ELISAs using ...the same capture monoclonal antibody (BC2); the second antibodies in the OSA and CASA assays are OM-1 and BC3, respectively. Using arbitrary cutoffs of 2.5 and 3.0 units/ml, 82 and 76% of 80 serum samples from ovarian cancer patients were positive for OSA and CASA, respectively, compared with 5 and 2.5% of samples from a control population of 40 women. A strong correlation was found between the two assays (r = 0.80, P less than 0.001). CA125 levels were obtained from 49 of the 80 samples; 82% of these samples were positive for CA125 (greater than 35 U/ml), 82% for OSA and 73% for CASA. Of the 9 samples negative for CA125, 3 were positive for OSA and 3 were positive for CASA. Serum OSA, CASA, and CA125 levels were determined in serial samples from 20 ovarian carcinoma patients throughout the course of their treatment. Clinical course was accurately reflected by CA125 levels in 85% of patients, by CASA in 65%, and by OSA in 75%. In 4 patients, a rise in CASA levels and, in 2 patients, a rise in OSA levels significantly predated rising CA125 levels to predict recurrence. Six of 7 serum samples obtained prior to positive second-look laparotomy were negative for CA125, while 4 were positive for OSA and 6 were positive for CASA. These results indicate that the OSA and CASA assays could be superior to CA125 for detection of small volume occult ovarian carcinoma.
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