The essentiality of arachidonic acid and docosahexaenoic acid

MCF-10A breast epithelial cells treated with docosahexaenoic acid (DHA) or oleic acid (OA) accumulated cytoplasmic lipid droplets containing both triacylglycerol and cholesteryl esters (CE). Interestingly, total CE mass was reduced in cells treated with DHA compared to cells treated with OA, and the CEs were rich in n-3 fatty acids. Thus, we hypothesized that DHA may be, in addition to a substrate, an inhibitor of cholesterol esterification in MCF-10A cells. We determined that the primary isoform of acyl-CoA: cholesterol acyltransferase expressed in MCF-10A cells is ACAT1. We investigated CE formation with DHA, OA, and the combination in intact cells and isolated microsomes. In both cells and microsomes, the rate of CE formation was faster and more CE was formed with OA compared to DHA. DHA substantially reduced CE formation when given in combination with OA. These data suggest for the first time that DHA can act as a substrate for ACAT1. In the manner of a poor substrate, DHA also inhibited the activity of ACAT1, a universally expressed enzyme involved in intracellular cholesterol homeostasis, in a cell type that does not secrete lipids or express ACAT2.     

Comparison of human uterine cervical electrical impedance measurements derived using two tetrapolar probes of different sizes

Background  

We sought to compare uterine cervical electrical impedance spectroscopy measurements employing two probes of different sizes, and to employ a finite element model to predict and compare the fraction of electrical current derived from subepithelial stromal tissue.     

Malignancy-associated changes in breast tissue detected by image cytometry.

In several tissues, nuclear differences have been described in normal-appearing cells from patients with invasive carcinomas compared to cases without invasive carcinoma, a phenomenon known as malignancy-associated changes (MACs). The aim of this study was to determine the presence of malignancy-associated changes in breast tissue. Image cytometry was performed on Feulgen stained tissue sections of patients with usual ductal hyperplasia with (n = 30) or without (n = 41) adjacent invasive breast carcinoma. Nuclear features of normal-appearing cells as well as of usual ductal hyperplastic cells were separately compared between the two groups. Many features of normal-appearing epithelial cells were significantly different between cases with and without invasive cancer. Significant differences were also found by measuring ductal hyperplastic nuclei instead of normal-appearing nuclei. Cases with or without cancer could be distinguished with a classification accuracy of 80% by discriminant analysis using 2 nuclear features derived from ductal hyperplastic cells. In conclusion, image cytometry on breast tissue sections shows that malignancy-associated changes can be found in normal as well as in usual ductal hyperplastic breast cells. This could be clinically relevant for the detection of occult breast cancer, for the prediction of risk in these lesions, and to monitor the effect of chemopreventive agents.     

DNA polymerase template switching at specific sites on the φ29 genome causes the in vivo accumulation of subgenomic φ29 DNA molecules

The accumulation of subgenomic phage φ29 DNA molecules with specific sizes was observed after prolonged infection times with delayed lysis phage mutants. Whereas the majority of the molecules had a size of 4 kb, additional DNA species were observed with sizes of 8.2, 6.5, 2.3, 2 and 1 kb. Most of the molecules were shown to originate from the right end of the linear Bacillus subtilis phage φ29 genome. The nature of the 4, 2.3, 2 and 1 kb molecules was studied. The 2 kb molecules were shown to be single-stranded self-complementary strands forming hairpin structures. The other molecules consisted of palindromic linear double-stranded DNA molecules. Most probably, the subgenomic DNA molecules were formed when the moving phage replication fork from the right origin encountered a block that induces the DNA polymerase to switch template. Once formed, the subgenomic molecules are then amplified in vivo . Determination of the centres of symmetry of the 4 and 1 kb molecules revealed that both contained the almost 16 bp perfect dyad symmetry element (DSE): 5'-TGTTtCAC-GTGgAACA-3' being a likely candidate for a protein binding site. Database analysis showed that this sequence occurs four times in the φ29 genome. In addition, the almost identical sequence 5'-TgGTTTCAC-GTGGAAtCA-3' was found once. These five DSEs are all located in the right half of the φ29 genome, and the same sequences are also present in the linear DNA of related B. subtilis phages. Most interestingly, this sequence is also found in the spoOJ gene of the B. subtilis chromosome. Recently, it has been shown that the SpoOJ protein is associated in vivo with the same DSE. As the same subgenomic φ29 DNA molecules accumulate after infection of B. subtilis spoOJ deletion strains, it is likely that, in addition to and/or independently of SpoOJ, other protein(s) bind to DSE.