Mass Gatherings and Diarrheal Disease Transmission Among Rural Communities in Coastal Ecuador.

Mass gatherings exacerbate infectious disease risks by creating crowded, high-contact conditions and straining the capacity of local infrastructure. While mass gatherings have been extensively studied in the context of epidemic disease transmission, the role of gatherings in incidence of high-burden, endemic infections has not been previously studied. Here, we examine diarrheal incidence among 17 communities in Esmeraldas, Ecuador, in relation to recurrent gatherings characterized using ethnographic data collected during and after the epidemiologic surveillance period (2004-2007). Using distributed-lag generalized estimating equations, adjusted for seasonality, trend, and heavy rainfall events, we found significant increases in diarrhea risk in host villages, peaking 2 weeks after an event's conclusion (incidence rate ratio, 1.21; confidence interval, adjusted for false coverage rate of ≤0.05: 1.02, 1.43). Stratified analysis revealed heightened risks associated with events where crowding and travel were most likely (2-week-lag incidence rate ratio, 1.51; confidence interval, adjusted for false coverage rate of ≤0.05: 1.09, 2.10). Our findings suggest that community-scale mass gatherings might play an important role in endemic diarrheal disease transmission and could be an important focus for interventions to improve community health in low-resource settings.

Computer-based self-help therapy: A qualitative analysis of attrition.

The impact of computer-based cognitive-behavioral self-help therapy programs is limited by high attrition. This study explored reactions to computer-based cognitive-behavioral self-help therapy use among individuals not completing a full treatment course. Individuals receiving outpatient substance use disorder treatment at a Veterans Health Administration clinic who enrolled in a study implementing a computer-based cognitive-behavioral self-help therapy for insomnia, but subsequently dropped out prior to completion, were interviewed. Reactions to use and reasons for attrition were explored through thematic analysis of interviews. Among barriers to use, themes of competing demands, personal attributes, the computer-based format of computer-based cognitive-behavioral self-help therapies, and negative experiences with the specific program used were identified. Among facilitators of use, themes of personal support, the computer-based cognitive-behavioral self-help therapy format, and personal attributes were identified. Recommendations for future implementation efforts to include additional person-to-person contact during computer-based cognitive-behavioral self-help therapy participation were made. These themes may be employed to develop strategies for computer-based cognitive-behavioral self-help therapy implementation in order to maximize program engagement and completion.

Age-associated telomere attrition of lymphocytes in vivo is co-ordinated with changes in telomerase activity, composition of lymphocyte subsets and health conditions.

Telomeres are essential in maintaining chromosome integrity and in controlling cellular replication. Attrition of telomere length in peripheral blood mononuclear cells (PBMCs) with age is well documented from cross-sectional studies. But the actual in vivo changes in telomere lengths and its relationship with the contributing factors within the individuals with age have not been fully addressed. In the present paper, we report a longitudinal analysis of telomere length in the PBMCs, lymphocytes and monocytes of 216 human subjects aged from 20-90 years assessed at 0-, 5- and 12-year follow-up. For the 5- and 12-year follow-up, telomere length in the PBMCs decreased in 34% and 46%, exhibited no detectable change in 56% and 47% and increased in 10% and 7% of the subjects respectively. The rate of telomere change was distinct for T-cells, B-cells and monocytes for any given subject. Telomerase activity declined with age in the resting T-cells and B-cells and the activated T-cells. Finally, a significant portion of telomere attrition in T-cells with age was explained by a decline in the telomerase activity, decreased naïve cells and the change in physiological conditions such as elevated blood glucose and interleukin (IL)-6 levels. These findings show that changes in the telomere length of the PBMCs with age in vivo occur at different rates in different individuals and cell types and reveal that changes in the telomere length in the T-cells with age is influenced by the telomerase activity, naïve T-cell percentage and changes in health conditions.

Delineation of WRN helicase function with EXO1 in the replicational stress response.

The WRN gene defective in the premature aging disorder Werner syndrome encodes a helicase/exonuclease. We examined the ability of WRN to rescue DNA damage sensitivity of a yeast mutant defective in the Rad50 subunit of Mre11-Rad50-Xrs2 nuclease complex implicated in homologous recombination repair. Genetic studies revealed WRN operates in a yEXO1-dependent pathway to rescue rad50 sensitivity to methylmethane sulfonate (MMS). WRN helicase, but not exonuclease, is required for MMS resistance. WRN missense mutations in helicase or RecQ C-terminal domains interfered with the ability of WRN to rescue rad50 MMS sensitivity. WRN does not rescue rad50 ionizing radiation (IR) sensitivity, suggesting that WRN, in collaboration with yEXO1, is tailored to relieve replicational stress imposed by alkylated base damage. WRN and yEXO1 are associated with each other in vivo. Purified WRN stimulates hEXO1 nuclease activity on DNA substrates associated with a stalled or regressed replication fork. We propose WRN helicase operates in an EXO1-dependent pathway to help cells survive replicational stress. In contrast to WRN, BLM helicase defective in Bloom's syndrome failed to rescue rad50 MMS sensitivity, but partially restored IR resistance, suggesting a delineation of function by the human RecQ helicases.

Filamin A modulates kinase activation and intracellular trafficking of epidermal growth factor receptors in human melanoma cells.

The actin-binding protein filamin A (FLNa) affects the intracellular trafficking of various classes of receptors and has a potential role in oncogenesis. However, it is unclear whether FLNa regulates the signaling capacity and/or down-regulation of the activated epidermal growth factor receptor (EGFR). Here it is shown that partial knockdown of FLNa gene expression blocked ligand-induced EGFR responses in metastatic human melanomas. To gain greater insights into the role of FLNa in EGFR activation and intracellular sorting, we used M2 melanoma cells that lack endogenous FLNa and a subclone in which human FLNa cDNA has been stably reintroduced (M2A7 cells). Both tyrosine phosphorylation and ubiquitination of EGFR were significantly lower in epidermal growth factor (EGF)-stimulated M2 cells when compared with M2A7 cells. Moreover, the lack of FLNa interfered with EGFR interaction with the ubiquitin ligase c-Cbl. M2 cells exhibited marked resistance to EGF-induced receptor degradation, which was very active in M2A7 cells. Despite comparable rates of EGF-mediated receptor endocytosis, internalized EGFR colocalized with the lysosomal marker lysosome-associated membrane protein-1 in M2A7 cells but not M2 cells, in which EGFR was found to be sequestered in large vesicles and subsequently accumulated in punctated perinuclear structures after EGF stimulation. These results suggest the requirement of FLNa for efficient EGFR kinase activation and the sorting of endocytosed receptors into the degradation pathway.

WRN is required for ATM activation and the S-phase checkpoint in response to interstrand cross-link-induced DNA double-strand breaks.

Werner syndrome (WS) is a human genetic disorder characterized by extensive clinical features of premature aging. Ataxia-telengiectasia (A-T) is a multisystem human genomic instability syndrome that includes premature aging in some of the patients. WRN and ATM, the proteins defective in WS and A-T, respectively, play significant roles in the maintenance of genomic stability and are involved in several DNA metabolic pathways. A role for WRN in DNA repair has been proposed; however, this study provides evidence that WRN is also involved in ATM pathway activation and in a S-phase checkpoint in cells exposed to DNA interstrand cross-link-induced double-strand breaks. Depletion of WRN in such cells by RNA interference results in an intra-S checkpoint defect, and interferes with activation of ATM as well as downstream phosphorylation of ATM target proteins. Treatment of cells under replication stress with the ATM kinase inhibitor KU 55933 results in a S-phase checkpoint defect similar to that observed in WRN shRNA cells. Moreover, gamma H2AX levels are higher in WRN shRNA cells than in control cells 6 and 16 h after exposure to psoralen DNA cross-links. These results suggest that WRN and ATM participate in a replication checkpoint response, in which WRN facilitates ATM activation in cells with psoralen DNA cross-link-induced collapsed replication forks.

Evidence for CALM in directing VAMP2 trafficking.

Clathrin assembly lymphoid myeloid leukemia protein (CALM) is a clathrin assembly protein with a domain structure similar to the neuron-specific assembly protein AP180. We have previously found that CALM is expressed in neurons and present in synapses. We now report that CALM has a neuron-related function: it facilitates the endocytosis of the synaptic vesicle protein VAMP2 from the plasma membrane. Overexpression of CALM leads to the reduction of cell surface VAMP2, whereas knockdown of CALM by RNA interference results in the accumulation of surface VAMP2. The AP180 N-terminal homology (ANTH) domain of CALM is required for its effect on VAMP2 trafficking, and the ANTH domain itself acts as a dominant-negative mutant. Thus, our results reveal a role for CALM in directing VAMP2 trafficking during endocytosis.

PTEN permits acute increases in D3-phosphoinositide levels following TCR stimulation but inhibits distal signaling events by reducing the basal activity of Akt.

Phosphoinositide 3-kinase (PI3K) is important in TCR signaling. PI3K generates phosphatidylinositol 3, 4, 5-trisphosphate (PI-3,4,5-P3), which regulates membrane localization and/or activity of multiple signaling proteins. PTEN (phosphatase and tensin homologue deleted on chromosome 10) opposes PI3K, reversing this reaction. Maintaining the balance between these two enzymes is important for normal T cell function. Here we use the PTEN-null Jurkat T cell line to address the role of PTEN in modulating proximal and distal TCR-signaling events. PTEN expression at levels that restored low basal Akt phosphorylation (an indicator of PI-3,4,5-P3 levels), but which were not themselves cytotoxic, had minimal effect on TCR-stimulated activation of phospholipase Cgamma1 and Ca2+ flux, but reduced the duration of extracellular signal-regulated kinase (Erk) activation. Distal signaling events, including nuclear factor of activated T cells (NFAT) activation, CD69 expression and IL-2 production, were all inhibited by PTEN expression. Notably, PTEN did not block TCR-stimulated PI-3,4,5-P3 accumulation. The effect of PTEN on distal TCR signaling events was strongly correlated with the loss of the constitutive Akt activation and glycogen synthase kinase-3 (GSK3) inhibition that is typical of Jurkat cells, and could be reversed by expression of activated Akt or pharmacologic inhibition of GSK3. These results suggest that PTEN acts in T cells primarily to control basal PI-3,4,5-P3 levels, rather than opposing PI3K acutely during TCR stimulation.