Human immunodeficiency virus 1 envelope-initiated G2-phase programmed cell death.

Despite intensive investigation, no clearly defined mechanism explaining human immunodeficiency virus (HIV)-induced cell killing has emerged. HIV-1 infection is initiated through a high-affinity interaction between the HIV-1 external envelope glycoprotein (gp120) and the CD4 receptor on T cells. Cell killing is a later event intimately linked by in vitro genetic analyses with the fusogenic properties of the HIV envelope glycoprotein gp120 and transmembrane glycoprotein gp41. In this report, we describe aberrancies in cell cycle regulatory proteins initiated by cell-cell contact between T cells expressing HIV-1 envelope glycoproteins and other T cells expressing CD4 receptors. Cells rapidly accumulate cyclin B protein and tyrosine-hyperphosphorylated p34cdc2 (cdk1) kinase, indicative of cell cycle arrest at G2 phase. Moreover, these cells continue to synthesize cyclin B protein, enlarge and display an abnormal ballooned morphology, and disappear from the cultures in a pattern previously described for cytotoxicity induced by DNA synthesis (S phase) inhibitors. Similar changes are observed in peripheral blood mononuclear cells infected in vitro with pathogenic primary isolates of HIV-1.

p53 controls both the G2/M and the G1 cell cycle checkpoints and mediates reversible growth arrest in human fibroblasts.

Increased expression of wild-type p53 in response to DNA damage arrests cells late in the G1 stage of the cell cycle by stimulating the synthesis of inhibitors of cyclin-dependent kinases, such as p21/WAF1. To study the effects of p53 without the complication of DNA damage, we used tetracycline to regulate its expression in MDAH041 human fibroblasts that lack endogenous p53. When p53 is expressed at a level comparable to that induced by DNA damage in other cells, most MDAH041 cells arrested in G1, but a significant fraction also arrested in G2/M. Cells released from a mimosine block early in S phase stopped predominantly in G2/M in the presence of p53, confirming that p53 can mediate arrest at this stage, as well as in G1. In these cells, there was appreciable induction of p21/WAF1. MDAH041 cells arrested by tetracycline-regulated p53 for as long as 20 days resumed growth when the p53 level was lowered, in striking contrast to the irreversible arrest mediated by DNA damage. Therefore, irreversible arrest must involve processes other than or in addition to the interaction of p53-induced p21/WAF1 with G1 and G2 cyclin-dependent kinases.

The US-China Joint Announcement on Climate Change: Can the G2 make a difference? CEPS Commentary, 26 November 2014

This Commentary finds that the US-China joint declaration on climate change, issued following the Asia-Pacific Economic Cooperation (APEC) Summit in Beijing on November 12th, is undoubtedly an important announcement by the two global economic giants responsible for emitting over 30% of the world’s GHG emissions. As such, it needs to be seen as important and relevant – a very positive development towards a new global climate change agreement in Paris. It is a challenge to those that have announced their pledges and are seen as capable of doing more, as well as to those that have not yet announced their intentions. It shows the importance and success of the UN climate change conference in Warsaw last year, when the decision was made that all Parties should announce their commitments by the first quarter of 2015. It also represents a total breakdown of the Kyoto Protocol-style separation in climate change negotiations between countries into Annex 1 and non-Annex 1, with China signalling that it is taking on the leadership role that comes with being a great economic power. In broader terms, it shows that there is scope for cooperation between the two main economic actors, even in the face of competition in other spheres. It is also a challenge to the EU, which was a leader and needs to show that there is a benefit in maintaining its leadership. Finally, agreements are deemed historic only by history. This one is important, and a potential game-changer, on the face of it. But it needs to live up to its promise. There is sufficient uncertainty for us to withhold final judgement and see if its promise materialises through implementation. But, as sober a judgement as we must make on such important matters, this announcement certainly gives us great hope that it is possible to do what needs to be done, and we must wholeheartedly welcome and applaud it.

Europe’s false alibi in the G2. EuropEos Commentary No. 9, 13 May 2011

In the wake of Osama Bin Ladin’s death and against the background of a more confident United States and a more anxious China, Marta Dassù explores in this EuropEos Commentary the prospect that these two leading countries could form a ‘G2’, further marginalising Europe.

NOR network transduction procedures : "merging of gates" and "substitution of gates" for fan-in and fan-out restricted networks, NETTRA-G3-FIFO and NETTRA-PG1-FIFO /

"December 1974."--T.p.

Network transduction based on permissible functions : general principles of NOR network transduction NETTRA programs /

Includes bibliographical references.

NOR network transduction based on error-compensation : principles of NOR network transduction programs NETTRA-E1, NETTRA-E2, and NETTRA-E3 /

Bibliography: p. 101-102.

NOR network transduction system : principles of the NETTRA system /

Bibliography: p. 209-212.

Program manual for the NETTRA system /

"UILU-ENG 77 1743."

NOR (NAND) network design : error-compensation procedures for fan-in and fan-out restricted networks (NETTRA-E1-FIFO and NETTRA-E2-FIFO /

Thesis (M. S.)--University of Illinois at Urbana-Champaign.

Program manual: NOR network pruning procedures using permissible functions : (reference manual of NOR network transduction programs NETTRA-PG1, NETTRA-P1, and NETTRA-P2) /

Includes bibliographical references (page 78).

Program manual, NOR network transduction by generalized gate merging and substitution : (reference manual of NOR network transduction programs NETTRA-G3 and NETTRA-G4) /

Includes bibliographical references.

Pruning procedures for NOR networks using permissible functions : principles of NOR network transduction programs NETTRA-PGI, NETTRA-P1, and NETTRA-P2 /

Bibliography: p. 49.

Program manual : NOR network transduction based on error-compensation : (Reference manual of NOR network transduction programs NETTRA-EL, NETTRA-E2, and NETTRA-E3) /

"Work supported in part by the National Science Foundation under Grant no. GJ-40221."

NOR network transduction by generalized gate merging and substitution procedures : (principles of NOR network transduction programs NETTRA-G3 and NETTRA-G4) /

Includes bibliographical references.