Micropore size analysis in oil-well cement by proton nuclear relaxation.

The durability of cement depends mainly on cement microstructure parameters such as pore size distribution. In this study, we have observed pore size distribution in a Class G oil-well cement immersed for 1 year in brine at T = 293 K, P = 10(5) Pa and in a down-hole condition at T = 353 K, P = 7.10(6) Pa by proton nuclear magnetic spin-lattice relaxation (1H-NMR).

Co-incubation of pig islet cells with spleen cells from non-obese diabetic mice causes decreased insulin release by non-T-cell- and T-cell-mediated mechanisms.

In vitro studies were conducted in the non-obese diabetic (NOD) mouse, prone to Type 1 autoimmune diabetes, to investigate the mechanisms involved in cell-mediated rejection of pig islet xenografts. Our previous work concerning the mechanisms of proliferation of xenogeneic lymphocytes to pig islet cells (PIC) was not indicative of PIC impairment. Consequently, a test was developed based on perifusion analysis of the alteration of basal and stimulated insulin release from adult PIC incubated with mouse splenocytes or subsets.

In vitro xenorecognition of adult pig pancreatic islet cells by splenocytes from nonobese diabetic or non-diabetes-prone mice.

Background: In vitro studies of the nonobese diabetic (NOD) mouse prone to type 1 autoimmune diabetes were conducted in order to investigate the mechanisms possibly involved in cell-mediated rejection of adult pig islet xenografts. Mouse cellular proliferation in discordant situations was previously investigated only with stimulator lymphocytes and found to be low in intensity and due to an indirect recognition mechanism involving murine antigen-presenting cells (APC). It was also important to characterize murine anti-pig islet response.

Perifusion analysis of insulin secretion from specific pathogen-free large-white pig islets shows satisfactory functional characteristics for xenografts in humans.

Though the pig appears to be the islet donor of choice for grafts in diabetic patients, there may be a risk of transmission of infectious agents. In this context, we adopted a strategy of islet isolation from pigs raised and killed in specific pathogen-free (SPF) conditions as a minimum with regard to the concept of quality assurance. Accordingly, the present study investigated the function of SPF pig islets to determine whether they react qualitatively and quantitatively to nutriments, hormones and neuromediators with which they would be confronted in man and could therefore provide effective regulation during physiologic or physiopathologic situations.

Minimisation of microbial contamination for potential islet xenografts using specific pathogen-free pigs and a protected environment during tissue preparation.

One major risk of islet xenotransplantation is transmission of infections. We thus compared microbial contamination during preparation of islets from 4 pigs conventionally breeded and slaughtered or 8 specific pathogen free (SPF) pigs, and different environmental conditions during pancreas excision. Pancreas harvested in a slaughterhouse (for conventional pigs) or in a protected autopsy room (for SPF pigs) were soaked in betadine solution and submitted to enzymatic digestion with collagenase.