Quantified 99mTc-MIBI scintigraphy for predicting chemotherapy response in breast cancer patients: factors that influence the level of 99m Tc-MIBI uptake.

The aim of this study was to establish whether tumour uptake of 99mTc-MIBI can predict response to chemotherapy in patients with breast carcinoma. Forty women suffering from breast carcinoma confirmed by tumour biopsy were studied prospectively. Fifteen patients subsequently underwent surgery and 25 were candidates for neoadjuvant chemotherapy. Breast scintigraphy was performed and planar and tomographic views (single photon emission computed tomography (SPECT)) were obtained after injection of 740 MBq of 99mTc-MIBI. The tumoural uptake was quantified by computer analysis. P-glycoprotein was evaluated by immunohistochemistry only in operable patients. The response to chemotherapy was evaluated at 3 months upon completion of treatment. The results of this study showed no relationship between 99mTc-MIBI uptake and the histological type or tumour size. There was an inverse correlation with the degree of tumour differentiation (P<0.05). 99mTc-MIBI uptake in negative P-glycoprotein lesions (2.36+/-1.72) was higher than in positive P-glycoprotein lesions (1.53+/-1.29), although the difference was not statistically significant. Lesions which responded to chemotherapy (16) showed higher 99mTc-MIBI uptake (7.70+/-5.20) than non-responding lesions (nine) (2.21+/-1.0) (P<0.001). In conclusion, there is a correlation between 99mTc-MIBI uptake in breast cancer and response to chemotherapy. Furthermore, 99mTc-MIBI uptake may be influenced by other factors such as the degree of tumour differentiation or tumour P-glycoprotein levels.

Methadone conversion to EDDP during GC-MS analysis of urine samples.

During validation of a gas chromatography-mass spectrometry (GC-MS) method for the methadone metabolite 2-ethylidine-1,5dimethyl-3,3-diphenylpyrrolidine (EDDP), it was noted that detectable levels of EDDP were found during analysis of extracts from drug-free urine samples spiked with methadone. Different amounts of EDDP were detected by GC-MS during confirmation analysis; however, levels consistently exceeded 50 ng/mL at methadone concentrations > 10,000 ng/mL. Quantitation of EDDP was determined by the addition of EDDP-d3 to methadone-spiked urine samples. Subsequent analysis of methadone-spiked urine extracts by high-performance liquid chromatography (HPLC) indicated no EDDP as a result of contaminated standard or conversion during solid-phase extraction. Reducing the GC injector-port temperature from 260 degrees C to 180 degrees C reduced the observed EDDP concentration in one sample from 201 ng/mL to 53 ng/mL at the initial methadone concentration of 10,000 ng/mL. These results indicate GC injector-port temperature induces thermal conversion of methadone to EDDP as an artifact. When confirmation of methadone and EDDP is critical to determining individual compliance with maintenance programs, alternative chromatographic methods (e.g., capillary electrophoresis, HPLC, or liquid chromatography-mass spectrometry) should be considered.

CEDIA--homogeneous immunoassays for the 1990s and beyond.

New homogeneous enzyme immunoassays have been developed for cortisol, digoxin, digitoxin, theophylline, phenytoin, and phenobarbital using the cloned enzyme donor immunoassay technology. As applied to Boehringer Mannheim/Hitachi analysis systems these methods provide rapid, accurate and precise quantification of analytes, with minimal interferences from endogenous serum constituents and low cross-reactivities to structurally-related hormonal precursors, drug metabolites and natural compounds. Additional significant features of the new assays are linear standard curves and two-point calibration. The six CEDIA assays join the two currently available CEDIA assays for determination of the thyroid parameters T4 and T Uptake. Additional new therapeutic drug and anemia monitoring assays are under development, demonstrating the versatility of the cloned enzyme donor immunoassay technology. These tests, in concert with Boehringer Mannheim/Hitachi analyzers, provide a high throughput, random access immunoassay system. The menu of available assays should continue to increase during the 1990s, providing efficient automation while allowing consolidation of testing on a limited number of instrument systems.