The established renal epithelial cell line LLC-PK1 retained in tissue culture several differentiated properties of renal proximal tubular cells. By adapting LLC-PK1 cells to glucose-free culture conditions, we recently succeeded in isolating a gluconeogenic strain of LLC-PK1 cells capable of growing in the absence of hexoses. In contrast to the parental wild type, the isolated strain expressed fructose-1,6-bisphosphatase activity and was, therefore, designated LLC-PK1-FBPase+. Besides the differences in glucose metabolism, the isolated gluconeogenic substrain differs form the parental wild type with respect to morphological appearance and the expression of apical membrane marker enzymes. LLC-PK1-FBPase+ cells display a drastic accumulation of autophagic vacuoles, disappearance of apical membrane alkaline phosphatase activity, and increased gamma-glutamyltranspeptidase activity. In order to find out whether or not a low alkaline phosphatase activity in combination with the enhanced formation of autophagic vacuoles is related to a change in apical membrane surface, we utilized a combined light and electron microscopic morphometric procedure to determine the absolute amount of organelle volumes and membrane surface areas. This stereologic approach shows that LLC-PK1-FBPase+ cells display a tenfold increase in the volume of autophagic vacuoles and the lysosomal compartment. Analysis of lysosomal enzyme activities, however, revealed no changes as compared to wild-type cells. The apical membrane surface of gluconeogenic cells was found to be increased by 80%. Karyotype analysis revealed that LLC-PK1 wild-type cells were diploid, whereas FBPase+ cells exhibited polyploidy with a high percentage of tetraploid nuclei. Culturing LLC-PK1-FBPase+ cells in the presence of 5 mM glucose does not abolish the morphological and biochemical changes described, indicating the stability of the FBPase+ strain.

Adaptation, Physiological↗

PubMedDate not supplied

[Deep venous thrombosis in pregnancy: risk factors and possibilities for prevention].

Twenty-two cases of acute venous thrombosis in pregnancy (0.64%) were studied. Concomitant pulmonary embolism was documented in 0.23%. Prophylactic heparinization was performed in 32 gravidae. In the acute thrombosis group therapy was instituted in the 26th week, and in the prophylaxis group in the 20th week of pregnancy. Recurrent thromboses after cesarean section occurred in 4.5% of the patients with acute venous thrombosis and in 5.6% of those in the prophylaxis group. Reduced red blood cell deformability, low antithrombin III and high leukocyte count were identified as risk factors. Heparinization did not prevent increased red blood cell aggregation and plasma viscosity at birth. Rheologic factors played only a secondary role in the prophylaxis group. Prophylactic heparinization in pregnancy is currently the only means of reducing the thrombosis recurrence rate in patients with a history of thromboembolism.

Adolescent↗