Association of bcl-2, bax, bcl-xL and interleukin-1 beta-converting enzyme expression with initial response to chemotherapy in acute myeloid leukemia.

Bcl-2 expression is able to confer drug resistance to chemotherapy-induced programmed cell death. Bax, a partner protein of bcl-2 with extensive aminoacid homology, is a promoter of apoptosis. Apparently the equilibrium of bcl-2 and bax hetero- and homodimers is important for the susceptibility of cells for stimuli inducing apoptosis. In this study we determined the role of bcl-2 to bax expression ratio, bcl-xL and ICE expression level for predicting clinical response to chemotherapy in acute myelold leukemia (AML). Bone marrow samples from 14 patients with AML were examined using an immunophosphatase staining method. Initial bone marrow blast portion was over 80% in all cases. Clinical response was defined by bone marrow aspiration 4 weeks after treatment initiation. There was a significant correlation between bcl-2 to bax expression ratio and clinical response (P < 0.005). No patients with a bcl-2/bax ratio >1.0 achieved complete remission after induction therapy. No significant correlation between bcl-2- and p-glycoprotein-expression was observed in this group. Conversely a high expression of ICE indicated a good clinical response (P < 0.01), whereas expression of bcl-xL had no influence on therapeutic success in this group.

Transient decrease in number of motor units after immobilisation in man.

On the day after the removal of a long leg cast, when the patient could just bend his knee, the electrical activity in the disused quadriceps muscle showed changes that indicated a reduction in the number of motor units. At 10 to 75% of maximum force the number of turns and the mean amplitude of the needle-recorded EMG were reduced in the disused muscle. Eight days later, when half the initial loss of force had been regained, the electrical activity was normal. The electrical activity produced during a constant force of 5 kg did not differ in the disused and in the contralateral muscle. From the findings in normal subjects it was deduced that the compensatory increase in turns in the EMG pattern to be expected from the decrease in cross-sectional area of the muscle fibres was within the error of the method. The transient decrease in the number of turns and in mean amplitude of the EMG of the disused muscle are an indication of the plasticity of the motor system.

Diagnostic yield of the analysis of the pattern of electrical activity of muscle and of individual motor unit potentials in neurogenic involvement.

The pattern of electrical activity and the properties of individual motor unit potentials were analysed in the flexor muscles of the forearm of 15 patients with motor neurone disease and 15 patients with a lesion of the brachial plexus. The best diagnostic yield from the pattern of electrical activity was obtained when the force was 30% of maximum: The number of spikes (turns/15 s) was diminished in 70% of the patients; none showed the increase in turns characteristic of myopathy. The decrease in the number of turns was often associated with an increased incidence of long time intervals between turns and with an increased amplitude between turns. The mean duration of individual motor unit potentials was prolonged in 78% of the patients; none showed the decrease in mean duration characteristic of myopathy. Prolongation of the mean duration of motor unit potentials produced by cooling of normal muscle, led to a decrease in the number of turns. This suggested that the diminished number of turns in neurogenic involvement was due mainly to the prolonged duration of motor unit potentials.

Diagnostic yield of analysis of the pattern of electrical activity and of individual motor unit potentials in myopathy.

The analysis of the pattern of electrical activity and of individual motor unit potentials in the same muscle both identified about 90% of 41 patients as having a myopathy. The pattern of electrical activity was analysed during a force which was a fixed fraction of maximum; individual motor unit potentials were analysed during weak effort. The two methods supplement each other as some of the patients were identified only by one or by the other of the two procedures. The parameter of the pattern of electrical activity which was most often abnormal was the ratio: numbers of turns to mean amplitude between turns.