Developmental pattern and molecular identification of globin chains in Xenopus laevis.

High-resolution electrophoresis of larval and adult hemoglobins of Xenopus laevis reveals stage-specific differences in the number and mobility of the globin chains. To establish the relationship between the globin chains and the previously described globin genes, the corresponding mRNAs were hybrid-selected from total erythroblast RNA by representative cDNA clones, and translated in vitro. Electrophoretic separation of the translation products allowed identification of a major and a minor α-globin chain in the larval and adult stages. This also holds for the adult ß-chains, however in the larval stage a difference in abundance is only detectable in the ß-mRNAs, but not in the translation products, because they comigrate. The fact that major and minor globin chains can be assigned to genes, which are located in two clusters, suggests that the related genes are expressed coordinately, but at different levels. Analysis of the globin patterns during development reveals that transition from the larval to the adult globin chains coincides with metamorphosis. Moreover, there is evidence of two globin chains that are only expressed in early larval stages and hence might be related to additional larval ß-globin genes of as yet unknown genomic location.

[When should stable maturity-onset diabetics be switched to insulin?]. / Wann sollen stabile Altersdiabetiker auf Insulin umgestellt werden?

All 11 maturity-onset diabetics (age 55 to 79 years) switched from oral hypoglycemics to insulin during one year in our department, even though metabolically stable, have been followed up. The main reason for the change was a diminished sense of well-being combined with relatively ill-defined symptoms such as declining physical performance, fatigue, dizziness and pain in the legs. None of the patients was ketoacidotic and the 24-hour glucosuria was less than 15 g, although the average fasting blood sugar was markedly elevated to 296 mg/dl. After 6 months on insulin the 24-hour glucosuria had not changed but the fasting blood sugar had dropped to 183 mg/dl. This was accompanied by an improved sense of well-being (as measured by an analog scale) and by disappearance of the symptoms mentioned above. Even though 9 of the 11 patients were initially reluctant to change to insulin, all 11 were still on this drug after 6 months. The authors recommend broadening the indications for insulin therapy in stable adult-onset diabetics, particular attention being paid to vague symptoms such as fatigue and decreased physical performance.