[The ISE 2020 electrolyte analyzer: results of a multicenter evaluation]. / Elektrolytanalysator ISE 2020 Ergebnisse einer multizentrischen Evaluierung.

The ISE 2020 electrolyte analyzer has been investigated within the framework of a multicentre evaluation in 5 laboratories. The users quickly learnt how to operate the instrument, and changes of personnel in the course of the trial had no influence upon the quality of the results. Regardless of the sample material (blood, serum, plasma) and the manner of introduction of the sample (manual or with the sampler), the in-series precision averaged 0.8% for sodium and 1.0% for potassium. The day-to-day precision was only slightly worse, at 1% (Na) and 2% (K). The recover, referred to the nominal values of control sera, averaged 100.3%. Investigations of linearity for potassium in the range from 0 to 12 mmol/l and for sodium in the range from 80 to 180 mmol/l confirmed a linear course of the measurements in the range of electrolyte concentrations of diagnostic interest. In extensive investigations by the testers with serum and plasma samples, the results showed good comparability with those from flame emission photometry. The mean values obtained by the two methods differed from one another only minimally in the case of sodium and potassium. The results with whole blood and with plasma prepared from it were in very close agreement. The ISE 2020 is regarded as highly suitable for routine work and emergency investigations in the central laboratory as well as for wards and operating rooms.

Does ethylene mediate root growth inhibition by indole-3-acetic Acid?

The effects of ethylene and of indole-3-acetic acid (IAA) on growth of excised pea root sections have been compared under a variety of conditions. After 16 hours treatment the inhibitory action of IAA is fully reversible on transfer of the root sections to IAA-free solutions. In contrast, inhibition by ethylene is almost totally irreversible. IAA inhibits growth from zero time; ethylene is generally without effect during the first 3 to 6 hours. The inhibitory action of ethylene is dependent on factors such as tissue age and solution composition which have no major effect on IAA inhibition. Ethylene production is enhanced by 100 mum IAA, but conditions which reduce the rate of ethylene evolution 2 to 3-fold at the same IAA concentration fail to affect the inhibitory action of IAA on elongation. It seems unlikely that ethylene can play more than a minor role in mediating inhibition of pea root growth by IAA.