Telomere Dysfunction in Nonalcoholic Fatty Liver Disease and Cryptogenic Cirrhosis.

Nonalcoholic fatty liver disease (NAFLD) and cryptogenic cirrhosis (CC) are considered preneoplastic conditions that might progress to hepatocellular carcinoma. We evaluated parameters of telomere dysfunction in these patient groups to study the correlation between telomere length and the progression of NAFLD. We analyzed peripheral lymphocytes from 22 patients with NAFLD, 20 patients with CC, and 20 healthy, age-matched controls. Telomere length was analyzed using quantitative fluorescence in situ hybridization, and cellular senescence was evaluated by the percentage of cells with senescence-associated heterochromatin foci. The expression of telomerase reverse transcriptase (hTERT) mRNA was measured using polymerase chain reaction, and telomere capture (TC) was assessed with 2 Cytocell probes, 15qter and 13qter. Shorter telomere length and increased cellular senescence was demonstrated in patients with NAFLD, compared to the CC patients and healthy controls. While hTERT mRNA was significantly decreased, TC was increased in CC patients, compared to the NAFLD group and healthy individuals. Thus, there is a correlation between hTERT mRNA expression and telomere length in patients with NAFLD, which might be related to associated metabolic disorders and the risk of malignant transformation. Patients with CC, on the contrary, elongate their telomeres through the TC mechanism.

Aneuploidy and asynchronous replication in non-alcholic fatty liver disease and cryptogenic cirrhosis.

BACKGROUND/AIMS: Non-alcoholic fatty liver disease (NAFLD) and cryptogenic cirrhosis (CC), which is largely a late sequela of NAFLD, are considered pre-neoplastic conditions that might progress to hepatocellular carcinoma. Aneuploidy, telomere aggregates and synchronization of replication were evaluated as markers of genetic instability in these patients. METHODOLOGY: Peripheral blood lymphocytes from 22 patients with NAFLD, 20 patients with CC and 20 age-matched healthy controls were analyzed. To determine random aneuploidy, we used the fluorescence in situ hybridization (FISH) with probes for chromosomes 9 and 18. The rate of aneuploidy was inferred from the fraction of cells revealing one, three or more hybridization signals per cell. Aggregate size was divided into three fusion groups of 2-5, 6-10 and 11-15 telomeres, relative to the size of a single telomere. The replication pattern was determined by FISH in two pairs of alleles, 15qter and 13qter. Asynchrony was determined by the presence of one single and one set of double dots in the same cell. RESULTS: Significantly higher random aneuploidy rate was found in the CC patients than in the control group, and to a lesser degree in NAFLD patients. Telomere aggregates were insignificantly higher in both groups. Only patients with CC showed significantly higher rate of asynchronous replication with proportionately more cells with two single dots among the normal cells (p<0.001). CONCLUSIONS: These results likely reflect changes in gene replication and cell cycle progression in these conditions, possibly correlating with their malignant potential.

K-factor image deshadowing for three-dimensional fluorescence microscopy.

The ability to track single fluorescent particles within a three dimensional (3D) cellular environment can provide valuable insights into cellular processes. In this paper, we present a modified nonlinear image decomposition technique called K-factor that reshapes the 3D point spread function (PSF) of an XYZ image stack into a narrow Gaussian profile. The method increases localization accuracy by ~60% with compare to regular Gaussian fitting, and improves minimal resolvable distance between overlapping PSFs by ~50%. The algorithm was tested both on simulated data and experimentally.