Role for c-jun N-terminal kinase in treatment-refractory acute myeloid leukemia (AML): signaling to multidrug-efflux and hyperproliferation.

A relationship was proved between constitutive activity of leukemic cell c-jun-N-terminal kinase (JNK) and treatment failure in AML. Specifically, early treatment failure was predicted by the presence of constitutive JNK activity. The mechanistic origins of this association was sought. A multidrug resistant leukemic cell line, HL-60/ADR, characterized by hyperexpression of c-jun and JNK activity, was transfected with a mutant c-jun vector, whose substrate N-terminal c-jun serines were mutated. Down-regulated expression occurred of c-jun/AP-1-dependent genes, catalase and glutathione-S-transferase (GST) pi, which participate in cellular homeostasis to oxidative stress and xenobiotic exposure. MRP-efflux was abrogated in HL-60/ADR cells with dominant-negative c-jun, perhaps because MRP1 protein expression was also lost. Heightened sensitivity to daunorubicin resulted in cells subjected to this change. Biochemical analysis in 67 primary adult AML samples established a statistical correlation between cellular expression of c-jun and JNK activity, JNK activity with hyperleukocytosis at presentation of disease, and with exuberant MRP efflux. These findings reflect the survival role for c-jun/AP-1 and its regulatory kinase previously demonstrated for yeast in homeostatic response to oxidative stress and in operation of ATP-binding cassette efflux pumps, and may support evolutionary conservation of such function. Thus, JNK and c-jun may be salient drug targets in multidrug resistant AML.

The effects of time delay and temperature on capillary blood gas measurements.

Monitoring of blood gas measurements is an important part of the assessment of patients with chronic lung disease. Increasingly, this is being done in the patients' homes by specialist nurses. This makes it important to know the effect of time delay and storage temperature on the reliability of capillary blood gas analysis results. In this study, the effect of a delay of 1 and 2 h and of storage at both room temperature and in ice, on blood stored in glass capillary tubes was investigated. Samples, initially taken from the earlobes, were transferred to glass capillary tubes and used to provide duplicate initial samples for immediate analysis, and then single samples at 1 and 2 h stored at room temperature or in ice. The duplicate baseline measurements showed good reproducibility. There was a small, but statistically significant, increase in PCO2 when samples were stored in capillaries at room temperature, or in ice, both at 1 and 2 h. Small changes in PO2 were not statistically significant, either in ice or at room temperature. None of the changes was considered to be sufficient to be of clinical significance, thus supporting the use of capillary blood sampling even when there might be a delay of 1-2 h and transport is at room temperature, as might be the case when taking domiciliary samples.

A novel ELISA format for the rapid and sensitive detection of staphylococcal enterotoxin A.

Staphylococcal food poisoning is one of the leading causes of bacterial food poisoning each year. Detection kits for staphylococcal enterotoxins are commercially available and the assays can require from one and a half to twenty-four hours to complete with detection limits ranging from 0.5 to 2 ng enterotoxin per gram of food. We have successfully demonstrated a microsphere-packed capillary (MPC) ELISA for the detection of staphylococcal enterotoxin A (SEA) and have compared it to two commercially available kits. The MPC assay detected a lower amount of SEA in ham, chicken, cheese, and bean sprouts than either of the two commercially available kits. In addition, the novel MPC assay was completed in less than ten minutes, as compared to three and twenty-four hours for the two commercially available kits. This research also demonstrated that the MPC ELISA can contain integrated positive and negative controls and has the potential to simultaneously detect and identify multiple enterotoxins.

Diagnostic equipment outside the laboratory.

A questionnaire was circulated to clinical biochemistry laboratories in the North West Thames region of the United Kingdom requesting information on extralaboratory equipment. Data on the types and numbers of instruments in use, their relationship with the laboratory, and quality assurance procedures were obtained. Laboratories were prepared to maintain equipment over which they had no responsibility for purchase, training of users, or use. The quality assurance of these instruments gave even greater cause for concern. Although internal quality control procedures were performed on many of the instruments, laboratories were involved in only a minority of these procedures. Quality control procedures and training of users were undertaken on site in less than 50% of blood gas analysers and bilirubin meters and in less than 25% of glucose meters. External quality assessment procedures were non-existent for all of the instruments in use with the exception of glucose stick meters in two laboratories.

Stick testing: a cause for concern.

A questionnaire was sent to biochemistry laboratories in the NW Thames Region regarding stick testing and the use of reflectance meters for the measurement of blood glucose. Some disturbing facts were reported, particularly with regard to training of staff and the quality of results.

Regional quality assessment of pH and blood gas analysers.

The performance of 41 pH and blood gas analysers in 20 hospitals was assessed using commercially available blood gas ampoules provided by seven manufacturers. The stability of the material and the effect of ambient temperature on Po2 was assessed. The overall mean values were outside the manufacturers' assigned values on eight out of 64 values. Using IL413 analysers as a basis for comparison, significant differences were found for Pco2 on ABL1, Corning 168 and 178 analysers and for Po2 on ABL1 and 2 and Corning 178. No significant differences were found for pH. Poor performers were identified in terms of imprecision. Analysers within or associated with clinical biochemistry departments gave better performance than those outside the laboratory. The five analysers that provided insufficient data for inclusion in the study were all situated outside the laboratory. Analysers from different manufacturers performed equally well provided they were used regularly and in accordance with manufacturers' instructions.

Effects of trimethoprim and sulphonamide preparations on the pituitary-thyroid axis of rodents.

The effects on pituitary-thyroid function of the commonly prescribed anti-bacterial preparations co-trimoxazole and co-trifamole, and their component drugs, have been studied in the rat and compared to the changes caused by propylthiouracil. Co-trimoxazole and co-trifamole, in doses 20-fold in excess of a pharmacological dose administered for 10 days, produced marked changes in hormone levels consistent with blocking of hyperplastic goitre formation, were also demonstrated. Propylthiouracil produced less marked changes of thyroid hormone levels but higher levels of thyroid-stimulating hormone. Pharmacological doses of co-trimoxazole and co-trifamole and sulphamoxole, the sulphonamide component of co-trifamole, caused significant changes in thyroid hormone levels consistent with anti-thyroidal activity. In contrast, there was no evidence that trimethoprim, which is common to both preparations, or sulphamethoxazole, the sulphonamide component of co-trimoxazole, had an anti-thyroidal action, indeed, serum thyroxine levels were significantly increased at pharmacological dosage. We have concluded that the new commonly prescribed combination preparations retain the goitrogenic properties of the earlier sulphonamides.

Predictive value of derived calcium figures based on the measurement of ionised calcium.

The algorithms used in this hospital to assess calcium status are calculated ionised serum calcium and the serum calcium concentration adjusted for albumin. In order to establish their clinical usefulness, they were compared with the ionised calcium concentration measured on the Nova 2 instrument in patients with various calcium and protein abnormalities. Good correlation was found between the measured and calculated values. The predictive values for the calculated results and for total serum calcium concentrations are presented. In this series, the derived values were useful in predicting the serum ionised calcium concentration of the patients studied.

Preparation of material to control precision of calcium selective electrodes.

A simple procedure is described for the preparation of a stable precision quality control material for use in the measurement of level of ionised calcium in serum at or near the reference range. Repeat analyses on a Nova 2 ionised calcium analyser of serum pools stored at different temperatures over a period of three months showed coefficients of variation less of less than 4%.