Growth-related expression of a double-stranded RNA-dependent protein kinase in 3T3 cells

Cultured mouse 3T3-F442A and 3T3-C2 fibroblasts exhibit a transient double-stranded RNA (dsRNA)-dependent phosphorylation of a 67,000-dalton protein (67K) without prior treatment with interferon (IFN). This phosphoprotein is similar but not identical to the dsRNA-dependent eukaryotic initiation factor-2 (eIF-2) alpha protein kinase (dsI), which regulates protein synthesis in rabbit reticulocytes. We have studied the relationship between cell growth and phosphorylation of the 67K protein (designated 3T3-dsRNA-dependent eIF-2 alpha kinase). A low level of dsRNA-dependent phosphorylation of 3T3-dsI was detectable in extracts prepared from cells not treated with IFN and grown at a low cell density. The phosphorylation of dsI and the phosphorylation of a 38K protein identified as the alpha-subunit (38K) of 3T3-eIF-2 (eIF-2 alpha) occurred concomitantly; the levels of these phosphorylations confluent and thereafter decreased markedly. Treatment of cells with IFN at all stages of growth resulted in an increase in phosphorylation of dsI. 3T3-F442A and 3T3-C2 fibroblasts were found to produce and secrete IFN at levels sufficient to induce an elevated dsI activity.     

Comparison of Effects of Long-term Corticotrophin and Corticosteroid Treatment on Responses of Plasma Growth Hormone,ACTH, and Corticosteroid to Hypoglycaemia

The development of the highly sensitive cytochemical bioassay for ACTH has permitted the measurement of plasma ACTH levels during the insulin hypoglycaemia test (I.H.T.) in patients treated with corticosteroids and corticotrophin. The ACTH, corticosteroid, and growth hormone (GH) responses in the I.H.T. were measured in three groups of 12 rheumatoid arthritis patients. One group was receiving long-term corticotrophin treatment, the second was undergoing long-term corticosteroid treatment, and the third had never received systemic hormone therapy. The increments in plasma ACTH, corticosteroids, and GH were diminished in the corticosteroid-treated group, as were increments in plasma GH and ACTH in the corticotrophin-treated group; but in this group the corticosteroid increment was normal. Examination of the area under the curve of the ACTH response showed that the total amount of ACTH secreted was normal though the rate of secretion was reduced. In the corticosteroid-treated group both rate and total secretion were diminished.     

Infection of macaque monkeys with simian immunodeficiency virus from African green monkeys: virulence and activation of latent infection

The virulence of three isolates of simian immunodeficiency virus from African green monkeys (SIVagm) was studied in rhesus and pigtailed macaques. None of 15 rhesus monkeys and one of four pigtailed monkeys died from infection during the time they were studied (up to 33 months). SIVagm was only isolated from rhesus monkeys for up to 2 months after inoculation. However, when these animals were secondarily infected with Simian acquired immunodeficiency syndrome retrovirus type 1 (SRV-1), SIVagm was activated and isolated. Dual infection caused increased mortality.     

Characterization of cDNA clones for human glycophorin A. Use for gene localization and for analysis of normal of glycophorin-A-deficient (Finnish type) genomic DNA

Glycophorin A is the major membrane sialoglycoprotein of human erythrocytes and represents a typical example of a transmembrane glycoprotein. The functional role of this cell-surface component is not known but it represents a receptor for viruses, bacteria and parasites like Plasmodium falciparum. 1. Two cDNA clones encoding glycophorin A have been characterized from human fetal cDNA libraries. The longer cDNA extended from the coding region of glycophorin A (residues 4-131) to the 3' untranslated region which included two polyadenylation signals and a poly(A) tail. 2. The structural gene for glycophorin A is located on chromosome 4, q28-q31 as shown by in situ hybridization, thus confirming the previous localization by genetic linkage analysis. 3. Three distinct mRNA species (1.0 kb, 1.7 kb and 2.2 kb) have been identified in erythroid spleen. Northern blot analyses with a probe directed against the 3' untranslated region of the mRNAs indicated that all these species share a homologous 3' non-coding region and that the first polyadenylation signal downstream the stop codon is not used. 4. Preliminary studies by Southern blot analysis of the genomic DNA from normal En(a+) and rare En(a-) donors suggest that the glycophorin A gene has a complex organization and is largely deleted in donors of the En(a-) phenotype (Finnish type) who lack glycophorin A on their red cells.