Decreased expression of J11d antigen during monocytic differentiation of M1 myeloid leukemic cells.

Four myeloid cell lines (M1, WEHI-3B D+, FDC-P1, and 32D) were screened for the presence of J11d antigen. One of these cell lines, the myeloid leukemia M1, was found to express a high level of J11d antigen on the cell surface. Recombinant mouse leukemic inhibitory factor (rm-LIF), recombinant human LIF (rh-LIF), and steroids (hydrocortisone and dexamethasone) could induce M1 cells to undergo monocytic differentiation. The level of J11d antigen was greatly reduced after treatment of the cells with LIF or steroids. Western blotting revealed that the apparent molecular weight of the J11d antigen on M1 cells was 45-48 kDa. Furthermore, the level of J11d mRNA was also reduced during LIF-induced differentiation of M1 cells.     

Alterations in high-affinity binding characteristics and levels of opioids in invertebrate ganglia during aging: Evidence for an opioid compensatory mechanism

In Mytilus and Leucophaea the high-affinity binding site density is significantly lower in old animals than in young animals, whereas the low-affinity site density remains unchanged. In Mytilus the estimated met-enkephalin and met-enkephalin-Arg6-Phe7 levels are significantly higher in old than in young animals. In Leucophaea only the met-enkephalin level can be determined, and it is also higher in old animals. The decrease in the high-affinity binding site density and the corresponding increase in endogenous enkephalin levels suggest the existence of an opioid compensatory mechanism associated with the aging process. In Mytilus there is a demonstrated decrease with age in intraganglionic dopamine levels in response to applied opiates. In addition, the inhibition of dopamine-stimulated adenylate cyclase activity by opiates also decreases in older animals. In Leucophaea the sex difference in opioid binding densities diminishes with age.     

Turnover of hepatic phosphofructokinase in normal and diabetic rats. Role of insulin and peptide stabilizing factor.

Earlier work demonstrated that the activity of liver phosphofructokinase (PFK-L2) and immunoreactive PFK-L2 were decreased in diabetic rats and increased to normal or super-normal amounts following insulin treatment (Dunaway, G.A., and Weber, G., (1974) Arch. Biochem. Biophys. 162, 629-637). This report indicates that the decrease in levels of PFK-L2 in diabetic rats is a result of an accelerated degradation rate while the synthetic rate remains nearly normal. Following insulin treatment, the rate of PFK-L2 synthesis is enhanced 2-fold, whereas the rate of degradation appears to be greatly diminished. An inverse relationship is shown to exist between the PFK-L2 levels and the rates of PFK-L2 degradation, suggesting that the levels of PFK-L2 are primarily regulated by degradation rate. In addition, the levels of the PFK-L2 peptide stabilizing factor are inversely proportional to rates of PFK-L2 degradation. These results indicate that insulin mediates the rate of degradation of PFK-L2 by controlling the level of the peptide stabilizing factor.     

Identity between the novel integrin beta 7 subunit and an antigen found highly expressed on intraepithelial lymphocytes in the small intestine.

A cDNA clone encoding the N-terminal sequence of the murine integrin beta 7 subunit, a novel member of the leukocyte cell adhesion molecule subset (Leu-CAM), has been isolated. An N-terminal region of 13 contiguous amino acids deduced from the cDNA shows complete identity with the N-terminus of the 120 kDa subunit of the M290 antigen, a surface molecule found highly expressed on mouse intestinal intraepithelial lymphocytes (IEL). This unexpected result focuses two previously unconnected areas of research and suggests that integrins may have a special role to play in the defence of the gut mucosa.     

A High-Content Small Molecule Screen Identifies Sensitivity of Glioblastoma Stem Cells to Inhibition of Polo-Like Kinase 1

Glioblastoma multiforme (GBM) is the most common primary brain cancer in adults and there are few effective treatments. GBMs contain cells with molecular and cellular characteristics of neural stem cells that drive tumour growth. Here we compare responses of human glioblastoma-derived neural stem (GNS) cells and genetically normal neural stem (NS) cells to a panel of 160 small molecule kinase inhibitors. We used live-cell imaging and high content image analysis tools and identified JNJ-10198409 (J101) as an agent that induces mitotic arrest at prometaphase in GNS cells but not NS cells. Antibody microarrays and kinase profiling suggested that J101 responses are triggered by suppression of the active phosphorylated form of polo-like kinase 1 (Plk1) (phospho T210), with resultant spindle defects and arrest at prometaphase. We found that potent and specific Plk1 inhibitors already in clinical development (BI 2536, BI 6727 and GSK 461364) phenocopied J101 and were selective against GNS cells. Using a porcine brain endothelial cell blood-brain barrier model we also observed that these compounds exhibited greater blood-brain barrier permeability in vitro than J101. Our analysis of mouse mutant NS cells (INK4a/ARF^−/−, or p53^−/−), as well as the acute genetic deletion of p53 from a conditional p53 floxed NS cell line, suggests that the sensitivity of GNS cells to BI 2536 or J101 may be explained by the lack of a p53-mediated compensatory pathway. Together these data indicate that GBM stem cells are acutely susceptible to proliferative disruption by Plk1 inhibitors and that such agents may have immediate therapeutic value.     

Cellulose-microfibril-orienting mechanisms in plant cells walls

A brief review is given of the changing views over the years, as knowledge of wall structure has developed, concerning the mechanism whereby cellulose chains may be oriented. This leads to an examination of current concepts, particularly those concerning microtubules. It is shown that none of the mechanisms suggested whereby microtubules might cause orientation of cellulose microfibrils is consistent with the known range of molecular architectures found in plant cell walls. It is further concluded that any mechanism which necessitates an indissoluble link between the plasmalemma and the cellulose-synthesising complex at the tip of a microfibril is unacceptable. A new proposal is presented in which it is speculated that both microtubules and microfibrils are oriented by a mechanism separate from both. It is shown that if two vectors are contemplated, one parallel to cell length and one at right angles, and a sensor exists on the plasmalemma surface which responds to changes in the vectors, then all known wall structures may be explained. The possible nature of the vectors and the sensor are considered.     

Growth of B95-8 cells and expression of Epstein-Barr virus lytic phase in serum-free medium.

Epstein-Barr virus (EBV)-transformed tamarin (Saguinus oedipus) cells (B95-8) were selected for growth in medium with reduced serum and then transferred to serum-free medium which consisted of RPMI 1640 supplemented with insulin, transferrin, and selenium. Serum-free cells in continuous passage for 1 year had a morphology, growth rate, and culture density which approached those of B95-8 cells grown with serum. The cells expressed virus-induced antigens, including the EBV-associated DNA polymerase. Cells exposed to EBV-inducing agents, n-butyric acid and phorbol 12-myristate-13-acetate, produced transforming virus with titers comparable to those of cultures grown with serum. These findings demonstrate that serum is neither required for the growth of B95-8 cells nor necessary for induction or full expression of the EBV lytic phase in these cells.     

Studies of the mortality of A-bomb survivors. 8. Cancer mortality, 1950-1982

This study extends an earlier one by 4 years (1979-1982) and includes mortality data on 11,393 additional Nagasaki survivors. Significant dose responses are observed for leukemia, multiple myeloma, and cancers of the lung, female breast, stomach, colon, esophagus, and urinary tract. Due to diagnostic difficulties, results for liver and ovarian cancers, while suggestive of significant dose responses, do not provide convincing evidence for radiogenic effects. No significant dose responses are seen for cancers of the gallbladder, prostate, rectum, pancreas, or uterus, or for lymphoma. For solid tumors, largely due to sex-specific differences in the background rates, the relative risk of radiation-induced mortality is greater for women than for men. For nonleukemic cancers the relative risk seen in those who were young when exposed has decreased with time, while the smaller risks for those who were older at exposure have tended to increase. While the absolute excess risks of radiation-induced mortality due to nonleukemic cancer have increased with time for all age-at-exposure groups, both excess and relative risks of leukemia have generally decreased with time. For leukemia, the rate of decrease in risk and the initial level of risk are inversely related to age at exposure.