Quantification of liver metastases from LS174T human colorectal cancer cells in nude rats by PCR.

Liver metastasis of colorectal cancer is a challenging problem and associated with poor prognosis. Appropriate experimental models based for example on xenografts of human colorectal cancer (HCRC) cells may help to find new therapeutic options. To establish an orthotopic liver metastasis model, 9 HCRC cell lines (HDC8, HDC63, HDC101, Isreco-1, Isreco-2, Isreco-3, SW480, SW620, LS174T) were tested for their appropriateness after subcutaneous (s.c.), intrasplenic, intrahepatic and intraportal injection into rnu-rats. The growth curve of the most appropriate cell line (LS174T) was established in a subsequent experiment. For early tumor detection, a quantitative nested PCR-assay using an internal standard was developed. The detection limit of the assay was 10 HCRC cells/mg liver tissue, which was 100-1000 fold more sensitive than histological examination. LS174T cells showed an exponential, but somewhat irregular growth in the liver of nude rats within the observation period of 6 weeks. The model will be useful for future therapeutic studies.

Technology assessment status evaluation: balloon dilation of gastrointestinal tract strictures. American Society for Gastrointestinal Endoscopy.

Balloon dilation is an acceptable modality for the dilation of stenoses at various sites in the gastrointestinal tract. In the esophagus its reported efficacy and safety is similar to bougienage; in other sites it offers an alternative to surgical treatment, in most cases as the definitive therapy.

Technology assessment status evaluation: monitoring equipment for endoscopy. American Society for Gastrointestinal Endoscopy.

An understanding of the principles and limitations of monitoring devices is valuable for their appropriate use and interpretation. Reliable monitoring de available as an adjunct to skilled personnel to detect changes in patient condition during endoscopy. Combination units that provide pulse oximetry, automated sphygmomanometry and ECG monitoring appear to be the most convenient and cost effective products.

Technology assessment status evaluation: disposable endoscopic accessories. American Society for Gastrointestinal Endoscopy.

Data supporting the preferential use of disposable endoscopic accessories is limited. These devices have been widely disseminated without careful evaluation of their impact on the environment and medical costs. In addition, current facility reimbursement for endoscopic procedures does not adequately cover the costs of these accessories. Re-use of accessories labelled "for single use only" as a potential means to reduce costs has not been carefully evaluated. More prospective data comparing the efficacy, safety, and cost effectiveness of disposable versus reusable accessories is needed.

Effect of sample preparation on analysis of superoxide dismutase activity and isoenzymes.

The effect of superoxide dismutase (SOD) activity and isoenzyme pattern of detergents, incubation time, and sonication in the preparation of rat liver samples was investigated. The activity of the manganese form of the enzyme (Mn-SOD) was found to decrease significantly after 4 hr of incubation at room temperature, and activity of the copper, zinc form of the enzyme (Cu, Zn-SOD) was not changed significantly even after 24 hr, although levels were somewhat decreased. Sonication of the sample did not affect Cu, Zn-SOD activity, but total Mn-SOD activity was increased. Addition of detergents did not increase Mn-SOD activity when homogenates were sonicated, indicating that Mn-SOD is not membrane bound. Detergents also had no effect on Cu, Zn-SOD activity. None of the treatments investigated altered the isoenzyme patterns, providing evidence that these isoenzymes are not degradation products.

Studies on the active center of D- and L-lactate dehydrogenases using oxamate-diaminohexyl-Sepharose affinity chromatography.

Vertebrate and invertebrate L-lactate dehydrogenases (L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) are effectively bound to oxamate-diaminohexyl-Sepharose, whereas several D-lactate dehydrogenases (D-lactate:NAD+ oxidoreductase, EC 1.1.1.28) do not bind to the same Sepharose. One explanation for our findings is that the enzymes' substrate is oriented in a reversed manner in the active center of the D- and L-lactate dehydrogenases.

Superoxide dismutase isoenzymes in bovine and human milk.

The presence of superoxide dismutase in bovine and human milk was investigated by ultrafiltration, gel filtration, and isoelectric focusing. Conclusive evidence for the presence of this enzyme in both milks is presented. The molecular weight of the enzyme was estimated by gel filtration on Sephadex G-100 to be 30,000, which is consistent with reported values for the copper, zinc form of superoxide dismutase. In addition, enzyme activity was inhibited by cyanide, thus eliminating the possibility that the enzyme was present in the manganese form. Several isoenzymes were detected by isoelectric focusing in polyacrylamide gel, and the isoenzyme pattern in bovine milk was the same as that found for bovine plasma, suggesting that milk superoxide dismutase originates from plasma. It may be that the presence of copper, zinc superoxide dismutase in milk is important for the maintenance of its oxidative stability.