Employing saline-impregnated cotton threads, an implanted-wick technique was adopted in dogs to obtain specimen from the subcutaneous interstitial compartment in order to estimate its glucose concentration. By measuring the protein, potassium and haemoglobin contents, the centrifuged wick fluid was shown to contain the interstitial concentration of solutes after an equilibration time of approximately 15 min. In normal and in diabetic animals the steady state subcutaneous glucose concentration was almost identical to the circulating glucose level when ranged between 2 and 25 mmol/l. Slow alterations in the circulating glucose profile such as those which appear during an oral glucose tolerance test are closely mirrored by the respective levels in the wick fluid. Fast alterations, however, show deviations. The wick-based glucose levels are well paralleled by the current of Clark type glucose oxidase sensors implanted at the same site. Since, on the basis of in vitro calibrations the sensor outputs have only indicated apparent tissue glucose concentrations of between 70 and 90% of glycaemia, another reference is needed for calibration. Under steady state conditions, the wick method, and on this basis in routine measurements the blood glucose concentration, may be recommended as a reference of implanted sensors which can otherwise not be calibrated in situ.

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Fetal hyperinsulinemia is assumed to play a key role in the pathogenesis of diabetic fetopathy. To investigate the role of enhanced fetal B-cell mass as one cause of fetal hyperinsulinemia during diabetic pregnancy, we studied human fetal pancreatic slices from diabetic women (FDW) with poor metabolic control and nondiabetic women (FNDW) between 11 and 26 wk of pregnancy, morphometrically and by in vitro incubation experiments. Abortions had been performed due to different medical indications. We found a good correlation between the calculated B-cell mass and the gestational age in both FDW and FNDW, but the increase in FDW was much more pronounced. Such a correlation was also found in vitro regarding the insulin response to glucose and IBMX. The FDW had significantly higher values than FNDW of the same age range. In contrast to this, we found in two diabetic patients with tight metabolic control during the whole pregnancy results similar to those in FNDW. Therefore, we assume that it could be possible to prevent fetal hyperinsulinemia and perhaps even diabetic fetopathy in diabetic women by tight metabolic control during the whole pregnancy, but further investigations are necessary.

The expression patterns of individual cytokeratin polypeptides in foetal and adult human pancreatic tissues were examined using monoclonal antibodies. We demonstrated that human pancreatic epithelia in early stages of development (14 weeks of gestation) contain cytokeratins 7, 8, 18 and 19, which are typical of simple epithelia, as well as cytokeratin 4 and 17, which are characteristic of stratified epithelia. In the pancreatic ducts, most of these cytokeratins appeared to be expressed together. Cytokeratins 1, 5, 10, 13, 16 and 20 were not detectable. In contrast, the pancreatic parenchyma was only positive for cytokeratins 8 and 18, except a transient expression of cytokeratins 7 and 19 in pancreatic islets and acinar cells during the foetal development. A focal cytokeratin 7 staining of single acinar cells was seen in newborn and in adult islets. In the stromal tissue, vascular smooth muscle cells were partly reactive with cytokeratin 8 and 18 specific antibodies. The results are discussed in the light of differentiation-dependent changes in the expression of individual cytokeratin polypeptides in developing epithelia.

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