New advances in biology and treatment of gastrointestinal stromal tumours (GISTs).

Gastrointestinal stromal tumours (GISTs) are a precise oncogenetic entity that has started the new era of targeted therapies in solid tumours. GISTs are now a model to understand the role of oncogenic kinase mutation in tumourigenesis, duplication, cell regulation, apoptosis and drug resistance. Ninety-five percent of GISTs have some activacting mutation of c-KIT or PDGFRA tyrosine kinase. The studies of the last two years have found concrete correlations between mutations and anatomical locations of GISTs, prognosis, response to therapy and resistance to therapy. Genotyping has increased of importance in the last years as a new field for translational researches. The important advances made in molecular studies are now a practical tool in diagnosis and therapy of GISTs.

Recombinant Escherichia coli for the biomonitoring of benzene and its derivatives in the air.

For protection against environmental deterioration, pollutants should be reduced as much as possible. Therefore, a sensitive detection method for air pollutants is required, particularly for benzene, a compound with mutagenic, teratogenic, and carcinogenic properties. Some microorganisms have a number of enzymes that degrade organic compounds. The genetic information for many of these enzymes is codified in plasmids that usually comprise some elements such as proteins and RNA for their replication, and proteins for cell division control. Some plasmids have been obtained from Pseudomonas putida, a ubiquitous microorganism that is able to degrade biologic and inorganic compounds. P. putida contains the TOL plasmid, responsible for the degradation of benzene and its derivatives. The TOL plasmid has been fused with the gene for firefly luciferase (pTNS316 plasmid) to produce a luminescent bacterium (Escherichia coli HB101), which can be applied to the environmental monitoring of these chemicals. The recombinant E. coli transformed with the plasmid (E. coli HB101-pTNS316) was applied to the environmental biosensing of benzene and its derivatives. Measurement of bacteria-generated photons was done using a color-coded device to estimate quantitatively the pollutant concentration. The expression of luciferase was induced in the presence of aromatic compounds but the E. coli sensitivity has a detection limit: this bacterium dies if the benzene concentration is higher than 0.5 ppm and at this concentration the luminescence decreases so it is impossible to detect. Another limit for this biodevice is that the microorganism, very likely, accumulates the benzene and its derivatives, and therefore it is very important to consider the time of exposure. This biomonitor potentially offers a rapid, inexpensive, and sensitive technique for environmental detection of aromatic pollutant compounds.

Static and ELF magnetic fields enhance the in vivo anti-tumor efficacy of cis-platin against lewis lung carcinoma, but not of cyclophosphamide against B16 melanotic melanoma.

Previous works showed that exposure to static and extremely low frequency (ELF) magnetic fields (MF) over 3 mT slows down the growth kinetics of human tumors engrafted s.c. in immunodeficient mice, reducing their metastatizing power and prolonging mouse survival. In the experiments reported here, immunocompetent mice bearing murine Lewis Lung carcinomas (LLCs) or B16 melanotic melanomas were exposed to MF and treated respectively with two commonly used anti-cancer drugs: cis-diamminedichloroplatinum (cis-platin) and N,N-bis (2-chloroethyl)tetra-hydro-2H-1,3,2-oxazaphosphorin-2-amine 2-oxide (cyclophosphamide). The experiment endpoint was survival time. The survival time of mice treated with cis-platin (3mg/kg i.p.) and exposed to MF was significantly (P<0.01) longer than that of mice treated only with cis-platin or only exposed to MF, superimposing that of mice treated with 10mg/kg i.p. of the drug, showing that MF act synergically with the pharmacological treatment. On the contrary, when mice treated with cyclophosphamide (50mg/kg i.p.) were exposed to MF no synergic effects were observed, the survival curve being exactly the same as that of mice treated with the drug alone. No clinical signs or toxicity were seen in any of the mice exposed to MF alone or along with cis-platin or cyclophosphamide treatment, compared to mice given only the two known drugs.A possible explanation for the synergic effect of MF being found in mice treated with cis-platin could be that the platinum ion stimulates radical production and that MF enhance active oxygen production bringing about changes in tumor cell membrane permeability, influencing positively the drug uptake. Alternatively, or in addition to this, it has been demonstrated that the rate of conversion of cis-platin to reactive species able to bind to DNA, is increased by localized production of free radicals by MF.

Simultaneous HPLC determination of 5-fluorouracil and its metabolites in plasma of cancer patients.

5-Fluorouracil (5-Fu) is a commonly used anticancer agent for treatment of solid tumours. Certain studies have reported conflicting results between individual plasma concentration levels and toxicity or therapeutic effects. For this reasons some authors proposed to evaluate the plasma levels of 5-Fu metabolites 5-fluorouridine, 5-fluoro-2'-deoxyuridine and 5-fluoro-5,6-dihydro-uracil. The aim of the present work is to develop and validate a new HPLC method simultaneously determining 5-fluorouracil and its three metabolites, to be used to study the plasma levels, therapeutic effects and toxicity in cancer patients. The analytes were separated on a 4.6 x 250 mm ODS1 (5 micro m) not end-capped column, operating at room temperature. Elution was performed under isocratic conditions, employing a 1.5 mM K(3)PO(4) mobile phase (pH 5). 5-Bromo-5,6-dihydro-uracil was used as internal standard. The limits of quantitation were 0.5 micro g/mL for 5-fluorouracil, 1 micro g/mL for 5-fluoro-5,6-dihydro-uracil, 3 micro g/mL for 5-fluoro-2'-deoxyuridine and 5-fluorouridine; the stability, recovery, linearity, accuracy and specificity of the compounds were evaluated according to the criteria widely accepted. Using this method we measured plasma samples of 18 cancer patients treated with folinic acid (100 mg/m(2)) by intravenous administration, followed by an i.v. bolus of 5-Fu (400 mg/m(2)). The concentration levels of 5-fluorouracil and for 5-fluoro-5,6-dihydro-uracil were detectable in all the subjects while 5-fluorouridine and 5-fluoro-2'-deoxyuridine were present only in eight patients.

Plasma erythropoietin concentrations in patients receiving intensive platinum or nonplatinum chemotherapy.

AIMS: Platinum chemotherapy has been shown to have potent antineoplastic activity against various tumours, especially testicular, bladder, ovarian, head and neck cancers. This activity is accompanied by side-effects of nephrotoxicity and cumulative myelosuppression, the latter frequently presenting as severe anaemia. Cisplatin and carboplatin nephrotoxicity might lower erythropoietin (Epo) secretion and, by this mechanism, contribute to the anaemia that follows therapy with this chemotherapeutic agent. The aim of the present work is to study the plasma immunoerythropoietin and haemoglobin levels of cancer patients treated with platinum or 5-fluorouracil-based chemotherapy. METHODS: Plasma was obtained from 25 patients who were about to receive chemotherapy for advanced malignancy: 15 treated with cisplatin or carboplatin and 10 with nonplatinum drugs. Blood was collected on the first day (before drug administration) and around day 15 of every chemotherapy course. Complete blood count, creatinine and immunoreactive Epo levels were also measured in 22 healthy volunteers. RESULTS: An increase in Epo levels occurred following every course of 5-FU or platinum based chemotherapy in patients with steady concentrations of creatinine and decreased levels of haemoglobin (Hb). In particular, we observed an increase after about 15 days of the chemotherapy treatment and the Epo levels declined toward normal just before the following course. This phenomenon was evident in every course. CONCLUSIONS: Our results suggest that chemotherapy administration, using the current standards of hydration and forced diuresis, slightly lowered Hb levels but did not depress Epo production, both in 5-FU and in platinum treated subjects.

Determination of Ibuprofen in human plasma by high-performance liquid chromatography: validation and application in pharmacokinetic study.

A specific method for the simultaneous determination of S-(+)Ibuprofen and R-(-)Ibuprofen enantiomers in human plasma is described. Adopting a high-performance liquid chromatographic (HPLC) system with spectrofluorometer detector, the compounds were extracted from plasma in alcohol medium and were separated on C18 column, using a solution of acetonitrile-water-acetic acid-triethylamine as mobile phase. The limit of quantitation was 0.1 microg/mL for both compounds. The method was validated by intra-day assays at three concentration levels and was used in a kinetic study in healthy volunteers. During the study we carried out inter-day assays to confirm the feasibility of the method.

Technetium99m-sestamibi scanning before initial neck exploration in patients with primary hyperparathyroidism.

Technetium99m (Tc) sestamibi(mibi) has been proposed as an alternative to the standard radionuclide imaging technique of thallium 201 chloride-99mTc pertechnetate subtraction scan (TTS) in patients with primary hyperparathyroidism. In the present study, mibi was evaluated as an alternative to TTS in 37 patients who had either mibi-99mTc pertechnetate subtraction scans, mibi-iodine123 (I) subtraction scans or mibi single isotope washout scans. There were 30 females and 7 males with an average age of 57 years (range, 27-78 years). Parathyroid adenomas were found in 35 patients and hyperplasia in 2. Twenty-eight mibi scans were positive and 25 of these correctly localized the parathyroid abnormality for a sensitivity of 68% (25 of 37) and a positive predictive value of 89% (25 of 28). There were 3 false-positives (8%) and 9 false-negatives (25%). The scan was not helpful in either patient with parathyroid gland hyperplasia. Mibi-123I subtraction was the most accurate scan and was diagnostic clinically in all 7 patients studied. Mibi scans were significantly more likely to identify inferior rather than superior adenomas (P = 0.01). Twenty-seven of the 37 patients also had a TTS which was correct in only 37% of cases while the mibi scan was correct in 68% (P = 0.02). However, routine use of nuclear scanning with mibi was still not supported by these data. Further clinical evaluation of various techniques may improve accuracy. Since mibi was significantly more accurate than TTS, it should be considered preferentially when radionuclide imaging is used in patients with recurrent hyperparathyroidism.