Modulation of Aβ42 low-n oligomerization using a novel yeast reporter system

Background  

While traditional models of Alzheimer's disease focused on large fibrillar deposits of the Aβ₄₂ amyloid peptide in the brain, recent work suggests that the major pathogenic effects may be attributed to SDS-stable oligomers of Aβ₄₂. These Aβ₄₂ oligomers represent a rational target for therapeutic intervention, yet factors governing their assembly are poorly understood.     

Transient and long-term differential modulations of branched-chain α-keto acid decarboxylase activity in hypophysectomized rats

Hypophysectomy caused a marked but transient increase in branched-chain α-keto acid decarboxylase activities in rat liver mitochondria, peaking at about nine days post-surgery. The magnitude of increase is different for each of the three branched-chain α-keto acids. The activities then fall to a new steady state in three weeks with α-ketoisovalerate decarboxylase activity within the normal range, α-keto-β-methylvalerate decarboxylase activity at twice normal, and α-ketoisocaproate decarboxylase activity decreased to a level too low for accurate measurements.     

Development and characterization of a human cell line from an ovarian mixed mullerian tumor (carcinosarcoma)

Summary A cell line derived from a human ovarian carcinosarcoma was established in tissue culture and in nude mice. Two sublines, LDF and HDF, separated by discontinuous density centrifugation were also established from the parent line JoN. The cloning efficiency of the JoN line was 21%. Morphologic features of adenocarcinoma cells characteristic of the parent JoN cells were retained in the sublines and clones; all lines showed the same karyotype and DNA content (pseudodiploid and pseudotetraploid). Keratin, as demonstrated immunohistochemically, was strongly expressed in the parent line JoN and the xenograft tumor, but not at all in the LDF sublines and only moderately in the HDF sublines. Vimentin, however, was expressed in neither the parent line JoN nor the xenograft tumor, but was present in both sublines. Transglutaminase and plasminogen activator activity was high in the parent line JoN. Neither, sublines nor clones showed the same high enzyme activity as the parent line. It is concluded that this human tumor line JoN is comprised of epithelial cells, capable of multidirectional differentiation.     

Secretory IgA as a measure of immunocompetence

The field of psychoimmunology has rapidly expanded in recent years and various parameters of the immune system have been examined in relation to psychological factors. The secretory immune system is one of the more interesting aspects of the entire immune system because it protects mucosal membranes from invading organisms. Stress-produced changes in secretory immunoglobulin A (s-IgA) as measured by radial immunodiffusion assays have been reported in several studies. We present three reasons why total s-IgA protein, the measure derived from radial immunodiffusion assays, may not be a reasonable measure of immune system functioning, and we suggest an alternative method for examining secretory IgA that focuses on s-IgA antibody response to a novel antigen.     

Inhibition of DNA methylation in Friend erythroleukemia cells by actinomycin D

Actinomycin D caused the production of hypomethylated DNA in cultured Friend erythroleukemia cells at cell culture concentrations of 1-4 ng per ml. Inhibition of DNA methyltransferase in cell-free assays was kinetically complex, with mixed-type inhibition. Cornish-Bowden graphical analysis was used to derive a Ki of about 35 nmol Act D per mg DNA. Although nuclei from drug-treated cells were found to contain hypomethylated DNA and DNA methyltransferase could be extracted from the nuclei, the methyl-accepting ability of DNA in whole nuclei themselves was not elevated. We conclude that the low level of Act D bound to DNA in the nuclei is sufficient to prevent the remethylation of hypomethylated sites.