Cryopreservation of isolated islets of Langerhans will be a necessary procedure if pancreatic islet transplantation crosses the threshold for clinical treatment of diabetes mellitus. Although successful cryopreservation of rodent, canine, porcine and human islets has been documented in the past few years, little is known about the influence of the freeze-thaw procedure on the islet’s potential to induce angiogenesis and revascularization, a process which is of crucial importance after free transplantation. We have analyzed the process of revascularîzation of 1- and 10-week-cryopreserved hamster islet isografts using intravital fluorescence microscopy. First signs of angiogenesis of cryopreserved islet grafts were observed on day 2 after transplantation, characterized by the protrusion of capillary sprouts. During the following days these sprouts formed a microvascular network, and revascularîzation was completed on day 10 after transplantation. Quantitative analysis of functional capillary density, capillary red blood cell velocity, capillary diameter and flow of individual capillaries did neither show differences between 1-and 10-week-cryopreserved islets, nor differences between cryopreserved islets and islets transplanted without cryopreservation were observed. From these results we conclude that cryopreservation of isolated pancreatic islet grafts is an adequate technique for long-term storage prior to transplantation.

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In 9 asthmatic patients log(dose)-response curves were obtained on 4 successive days with the Wiesbadener Doppelinhalator (WDI) and the De Vilbiss (De V) 645 nebulizer, respectively. log(dose)-response was expressed as a quadratic regression equation. From those equations the dose, causing a fall in response (FEV₁) of 10% of the initial value, was obtained and defined as the provocative concentration (PC(10)) or sensitivity. Moreover, the reactivity was defined as the slope of the linear regression through the steeper part of the curve. Although we compared the De V and the WDI log(dose)-response curves after correction for the different liquid output, a significantly greater sensitivity was found for the De V nebulizer. As to the reactivity, no significant differences were found. The difference in sensitivity could perhaps be explained by the fact that, as compared with the De V nebulizer, the WDI may cause a larger deposition of aerosol on the throat and the pharynx, due to the much greater linear velocity of its aerosol jet.