infections Widad Al-Nakib, FRCPath, FIDSA; Sahar Essa, BSc, MSc, PhD; Haya Altawalah, BSc, MBBS, FRCPath; Abdullah Owayed; Mousa Khadadah; Nasser Behbehani; Microbiology Department Kuwait University, Faculty of Medicine, Kuwait; Virology Unit, Ministry of Health, Mubarak Hospital, Kuwait; Paediatrics, Kuwait University, Faculty of Medicine, Kuwait; Medicine, Kuwait University, Faculty of Medici...

Background and Aim: Stress has been associated with recurrent aphthous stomatitis (RAS). The common treatment of RAS is a topical steroid. This study aimed to investigate the difference of salivary cortisol between RAS patients treated with a topi-cal steroid and those without treatment. Materials and Methods: Thirty-two female patients with RAS participated in this case-control study and were...

In Focus • THE JOURNAL OF CELL BIOLOGY p53 cuts off invading cells T he tumor suppressor p53 does all it can to prevent oncogenes from inducing tumorigenesis, killing defective cells or pushing them into senes-cence. Sometimes, oncogenes manage to initiate tumor development in the presence of p53, but, even then, the tumor suppressor doesn't give up and focuses its efforts instead on limiting t...

The signaling pathways by which light and activity shift the circadian clock are not well understood. In this issue of Neuron, Cheng et al. analyze mice lacking Dexras1 (a Ras family GTPase protein) and demonstrate an important role for G(i/o) signaling mediating both photic and nonphotic phase shifts of the circadian clock.

Many bacterial pathogens use a specialized "type III" secretion system to deliver virulence effector proteins into host mammalian cells. In this issue of Cell, Alto et al. (2006) describe a new family of effectors that share a WxxxE sequence motif. These effectors directly stimulate host signaling pathways by mimicking activated Ras-like cellular GTPases.

Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is a negatively charged phospholipid that plays a major role in recruiting and regulating proteins at the plasma membrane-cytosol interface. In this issue, Chen et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201606047) demonstrate that RAS association domain family 4 (RASSF4) positively influences PI(4,5)P2 synthesis through ARF6-depend...

In the formation of long-term memories, a "spaced" distribution of study sessions is more beneficial than closely spaced "massed" study sessions. Pagani et al. (2009) examine the molecular basis of this spacing effect in Drosophila and find a role for the SHP2 homolog, corkscrew, an activator of Ras/MAPK signaling, in establishing optimal spacing intervals.

Neuroimaging, the topic of this Neurobiology Select, continues to advance our understanding of brain function at both the molecular and systems levels. Recent reports include the use of two-photon microscopy to study crosstalk between neighboring dendritic spines, the differences in activity between cortical layers, and the effects of presynaptic glutamate release on neuromuscular junction deve...

A bundant, well-accepted evidence demonstrates a complete tissue renin-angiotensin system (RAS) within the kidney that plays many roles in the control of the intrarenal vasculature, as well in the control of glomerular and tubular processes (1). Substantial clinical and experimental data suggest that the intrarenal RAS is important, if not central, to the development and progression of diabetic...

Low molecularweight GTP-binding proteins are molecular switches that control a diverse array of biological processes (Bourne et al., 1991). When bound to GTP, these proteins transduce signals to effector proteins. When bound to GDP, these proteins are in an inactive state. The cycling between the active, GTP-bound state and the inactive, GDP-bound state is controlled by positive and negative mo...