Molecular remedy of complex I defects: Rotenone-insensitive internal NADH-quinone oxidoreductase of Saccharomyces cerevisiae mitochondria restores the NADH oxidase activity of complex I-deficient mammalian cells

The NDI1 gene encoding rotenone-insensitive internal NADH-quinone oxidoreductase of Saccharomyces cerevisiae mitochondria was cotransfected into the complex I-deficient Chinese hamster CCL16-B2 cells. Stable NDI1-transfected cells were obtained by screening with antibiotic G418. The NDI1 gene was shown to be expressed in the transfected cells. The expressed Ndi1 enzyme was recognized to be localized to mitochondria by immunoblotting and confocal immunofluorescence microscopic analyses. Using digitonin-permeabilized cells, it was shown that the transfected cells, but not nontransfected control cells, exhibited the electron transfer activities with glutamate/malate as the respiratory substrate. The activities were inhibited by flavone, antimycin A, and KCN but not by rotenone. Added NADH did not serve as the substrate, suggesting that the expressed Ndi1 enzyme was located on the matrix side of the inner mitochondrial membranes. Furthermore, although nontransfected cells could not survive in a medium low in glucose (0.6 mM), which is a substrate of glycolysis, the NDI1-transfected cells were able to grow in the absence of added glucose. When glycolysis is slow, either at low glucose concentrations or in the presence of galactose, respiration is required for cells to survive. The mutant cells do not survive at low glucose or in galactose, but they can be rescued by Ndi1. These results indicated that the S. cerevisiae Ndi1 was expressed functionally in CCL16-B2 cells and catalyzed electron transfer from NADH in the matrix to ubiquinone-10 in the inner mitochondrial membranes. It is concluded that the NDI1 gene provides a potentially useful tool for gene therapy of mitochondrial diseases caused by complex I deficiency.     

The Risk Factors for Bleeding of Fundal Varices in Patients with Liver Cirrhosis

Background/Aims

The relationship between portal hemodynamics and fundal varices has not been well documented. The purpose of this study was to understand the pathophysiology of fundal varices and to investigate bleeding risk factors related to the presence of spontaneous portosystemic shunts, and to examine the hepatic venous pressure gradient (HVPG) between fundal varices and other varices.

Methods

In total, 85 patients with cirrhosis who underwent HVPG and gastroscopic examination between July 2009 and March 2011 were included in this study. The interrelationship between HVPG and the types of varices or the presence of spontaneous portosystemic shunts was studied.

Results

There was no significant difference in the HVPG between fundal varices (n=12) and esophageal varices and gastroesophageal varices type 1 (GOV1) groups (n=73) (17.1±7.7 mm Hg vs 19.7±5.3 mm Hg). Additionally, there was no significant difference in the HVPG between varices with spontaneous portosystemic shunts (n=28) and varices without these shunts (n=57) (18.3±5.8 mm Hg vs 17.0±8.1 mm Hg). Spontaneous portosystemic shunts increased in fundal varices compared with esophageal varices and GOV1 (8/12 patients [66.7%] vs 20/73 patients [27.4%]; p=0.016).

Conclusions

Fundal varices had a high prevalence of spontaneous portosystemic shunts compared with other varices. However, the portal pressure in fundal varices was not different from the pressure in esophageal varices and GOV1.