Cytoskeletal reorganization by G protein-coupled receptors is dependent on phosphoinositide 3-kinase gamma, a Rac guanosine exchange factor, and Rac

Reorganization of the actin cytoskeleton is an early cellular response to a variety of extracellular signals. Dissection of pathways leading to actin rearrangement has focused largely on those initiated by growth factor receptors or integrins, although stimulation of G protein-coupled receptors also leads to cytoskeletal changes. In transfected Cos-7SH cells, activation of the chemoattractant formyl peptide receptor induces cortical actin polymerization and a decrease in the number of central actin bundles. In this report, we show that cytoskeletal reorganization can be transduced by G protein betagamma heterodimers (Gbetagamma), phosphoinositide 3-kinase gamma (PI3-Kgamma), a guanosine exchange factor (GEF) for Rac, and Rac. Expression of inactive variants of either PI3-Kgamma, the Rac GEF Vav, or Rac blocked the actin rearrangement. Neither wortmannin nor LY294002, pharmacologic inhibitors of PI3-K, could inhibit the actin rearrangement induced by a constitutively active Rac. The inhibition of cytoskeletal reorganization by the dominant negative Vav variants could be rescued by coexpression of a constitutively active form of Rac. In contrast, a Vav variant with its pleckstrin homology (PH) domain missing constitutively induced JNK activation and led to cytoskeletal reorganization, even without stimulation by PI3-Kgamma. This suggests that the PH domain of Vav controls the guanosine exchange activity of Vav, perhaps by a mechanism regulated by D3 phosphoinositides generated by PI3-K. Taken together, these findings delineate a pathway leading from activation of a G protein-coupled receptor to actin reorganization which sequentially involves Gbetagamma, PI3-Kgamma, a Rac GEF, and Rac.     

Cytokine production at the site of disease in human tuberculosis

Clinical and immunologic evidence suggests that tuberculous pleuritis provides a model to understand protective immune mechanisms against Mycobacterium tuberculosis. We therefore evaluated the pattern of cytokine mRNA expression and cytokine production in pleural fluid and blood of patients with tuberculous pleuritis. RNA was extracted from mononuclear cells, reverse transcribed to cDNA, and amplified by polymerase chain reaction (PCR). After normalization for T-cell cDNA, cDNA from pleural fluid cells and peripheral blood mononuclear cells (PBMC) was amplified with cytokine-specific primers. PCR product was quantified by Southern blot. For the Th1 cytokines gamma interferon (IFN-gamma) and interleukin-2 (IL-2), PCR product was greater in pleural fluid than in blood, whereas PCR product for the Th2 cytokine IL-4 was decreased in pleural fluid compared with blood. Concentrations of IFN-gamma were elevated in pleural fluid compared with serum, but IL-2, IL-4, and IL-5 were not detectable. Mean concentrations of IFN-gamma and IL-2 in supernatants of M. tuberculosis-stimulated pleural fluid cells were significantly greater than corresponding concentrations in supernatants of stimulated PBMC. In situ hybridization showed that increased IFN-gamma production by pleural fluid cells was associated with a 20- to 60-fold increase in the frequency of antigen-reactive IFN-gamma-mRNA-expressing cells. Because IL-10 can be produced by T cells and macrophages, pleural fluid cells and PBMC were normalized for beta-actin cDNA content and then amplified by PCR with IL-10-specific primers. IL-10 mRNA was greater in pleural fluid cells than in PBMC and was expressed predominantly by macrophages. IL-10 concentrations were elevated in pleural fluid versus serum. These data provide strong evidence for compartmentalization of Th1 cytokines and IL-10 at the site of disease in humans with a resistant immune response to mycobacterial infection.     

Carbachol does not correct the defect in the phagocytosis of outer segments by Royal College of Surgeons rat retinal pigment epithelial cells

PURPOSE: To investigate the effect of carbachol on the phagocytosis of photoreceptor outer segments (OS) in cultures of normal Long-Evans and dystrophic Royal College of Surgeons (RCS) rat retinal pigment epithelial (RPE) cells. METHODS: Retinal pigment epithelial cells from normal and RCS rats were grown in tissue culture. On reaching confluence, they were presented with OS suspended in Krebs-Henseleit buffer in the presence or absence of carbachol and LiCl. The number of bound and ingested OS was quantitated using double immunofluorescence staining. RESULTS: LiCl inhibited the ingestion of OS by more than 90% but had no effect on the binding of OS by Long-Evans RPE cells. The addition of carbachol further reduced OS ingestion. Carbachol alone decreased OS ingestion by normal RPE cells by 30% but had no effect on OS binding. The effect of LiCl and carbachol on RCS RPE cells was similar to their effect on normal RPE cells. CONCLUSIONS: Carbachol does not increase OS phagocytosis in normal or RCS rat RPE cells. The phagocytic defect in RCS rat RPE cannot be reversed or overcome by stimulation of the IP3 pathway by carbachol. LiCl strongly inhibits the ingestion of OS by normal and by RCS RPE cells, and this effect is enhanced by carbachol.     

Smoking cessation treatment on the Internet: content, quality, and usability.

The explosive growth in access to the Internet suggests that the Internet may be a viable channel through which we can reach and treat the large population of smokers who are unlikely to use other modes of intervention. We applied national guidelines from the U.S. Public Health Service to assess the quality of interventions for smoking cessation that are available on the Internet. The Public Health Service guidelines were codified into two instruments to record and to rate quality of the intervention contents. Usability guidelines established by the National Cancer Institute were used to develop an instrument to assess Web site usability. Of the 202 Web sites identified in searches, 77% did not provide direct intervention over the Internet and were excluded from analyses. A total of 46 Web sites were included in our review. Usability assessments showed mixed results. Web sites were visually well organized and used consistent graphical design; however, reading difficulty averaged above the 8th-grade level. Over 80% of Web sites provided no coverage of one or more of the key components of tobacco treatment recommended in the guidelines. Ironically, areas receiving the least coverage were those most amenable to the interactive capabilities of the Internet, such as providing tailored, personalized advice to quit and arranging follow-up contact. Smokers seeking quality tobacco dependence treatment on the Internet may have difficulty distinguishing among the numerous Web sites available. Web sites that provide direct treatment often fail to fully implement treatment guidelines and do not take full advantage of the interactive and tailoring capabilities of the Internet.     

Oculocentric coding of inhibited eye movements to recently attended locations.

Results are reported for experiments that examined eye movements directed toward recently cued objects. In 1 experiment participants were slower to initiate saccades toward the earlier location of an object that had been cued, even though the cued object had subsequently moved away from that location. Other experiments involved exploring the reference frame within which the inhibited eye movements are encoded. These experiments revealed that the eye movement that is inhibited is encoded in an oculocentric—rather than an environmental—reference frame. However, simple detection as indexed by manual keypress responses is encoded in an environmental reference frame. The results have implications for inhibition of return, for the link between eye movements and attention, and for the nature of the spatial reference frames in which both covert and overt movements of attention are encoded. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do younger and older adults’ communicative goals influence off-topic speech in autobiographical narratives?

The present research investigated younger and older adults’ communicative goals and their effects on off-topic speech for autobiographical narratives. Participants indicated their communicative goals by rating preferences among paired goals, for example, focus–fascinating, one of which was designated as an expressive goal, appropriate for producing elaborative speech, and one of which was an objective goal, suited to producing concise speech. The participants then told stories about episodic and procedural topics, which were rated by groups of younger and older listeners. Age differences emerged in communicative goals, where younger adults clearly favored expressive goals for episodic topics and objective goals for procedural topics. In contrast, older adults’ goals were more diverse, consisting of a mixture of expressive and objective goals for both topic types, without a clear preference. Younger adults’ goals predicted ratings of off-topic speech assessed by listeners: Younger and older adults were perceived as equivalently focused, coherent, and clear for episodic topics, but older adults were perceived as less focused, less clear, and more talkative than younger adults on procedural topics. These results suggest that age-related changes in off-topic speech emerge as a result of younger adults selecting goals designed to produce more succinct stories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual search for change in older adults.

Previous research has demonstrated that younger adults are surprisingly poor at detecting substantial changes to visual scenes. Little is known, however, about age differences in this phenomenon. In the 2 experiments reported here, older adults were slower than younger adults in detecting changes to simple visual stimuli. This age difference was beyond what would be expected given known age-related changes in processing speed. Examination of eye movement behavior during the search for change suggested that age-related changes in the useful field of view and degree of cautiousness play a significant role. Speed of processing and 3 age-related eye movement behaviors explained 85% of the variance in change detection latency, eliminating the effect of age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Brief coping skills treatment for cocaine abuse: 12-month substance use outcomes.

Patients (N?=?108) in a study of cocaine-specific coping skills training (CST), which was found to reduce cocaine use during a 3-month follow-up, were followed for an additional 9 months. CST involved coping skills training in the context of high-risk situations. Control treatment used meditation-relaxation. Both were added to comprehensive private substance abuse treatment. Patients in CST who relapsed had significantly fewer cocaine use days than did the control group during the first 6 months, then both conditions did equally well. Patients in CST also drank alcohol more frequently in the last 6 months than did contrast patients but did not differ in heavy drinking days. For cocaine use outcomes, no interaction of treatment was found with gender, education, route of administration, drug use severity, sociopathy, or depression. Implications include the need to investigate different lengths and combinations of treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)