Spatio-temporal co-ordination of RhoA, Rac1 and Cdc42 activation during prototypical edge protrusion and retraction dynamics

The three canonical Rho GTPases RhoA, Rac1 and Cdc42 co-ordinate cytoskeletal dynamics. Recent studies indicate that all three Rho GTPases are activated at the leading edge of motile fibroblasts, where their activity fluctuates at subminute time and micrometer length scales. Here, we use a microfluidic chip to acutely manipulate fibroblast edge dynamics by applying pulses of platelet-derived growth factor (PDGF) or the Rho kinase inhibitor Y-27632 (which lowers contractility). This induces acute and robust membrane protrusion and retraction events, that exhibit stereotyped cytoskeletal dynamics, allowing us to fairly compare specific morphodynamic states across experiments. Using a novel Cdc42, as well as previously described, second generation RhoA and Rac1 biosensors, we observe distinct spatio-temporal signaling programs that involve all three Rho GTPases, during protrusion/retraction edge dynamics. Our results suggest that Rac1, Cdc42 and RhoA regulate different cytoskeletal and adhesion processes to fine tune the highly plastic edge protrusion/retraction dynamics that power cell motility.

Chlamydia prevalence in young attenders of rural and regional primary care services in Australia: a cross-sectional survey.

OBJECTIVE To estimate chlamydia prevalence among 16-29-year-olds attending general practice clinics in Australia. DESIGN, PARTICIPANTS AND SETTING A cross-sectional survey was conducted from May 2010 to December 2012. Sexually experienced 16-29-year-olds were recruited from 134 general practice clinics in 54 rural and regional towns in four states and in nine metropolitan clinics (consecutive patients were invited to participate). Participants completed a questionnaire and were tested for chlamydia. MAIN OUTCOME MEASURE Chlamydia prevalence. RESULTS Of 4284 participants, 197 tested positive for chlamydia (4.6%; 95% CI, 3.9%-5.3%). Prevalence was similar in men (5.2% [65/1257]; 95% CI, 3.9%-6.4%) and women (4.4% [132/3027]; 95% CI, 3.5%-5.2%) (P = 0.25) and high in those reporting genital symptoms or a partner with a sexually transmissible infection (STI) - 17.0% in men (8/47; 95% CI, 2.8%-31.2%); 9.5% in women (16/169; 95% CI, 5.1%-13.8%). Nearly three-quarters of cases (73.4% [130/177]) were diagnosed in asymptomatic patients attending for non-sexual health reasons, and 83.8% of all participants (3258/3890) had attended for non-sexual health reasons. Prevalence was slightly higher in participants from rural and regional areas (4.8% [179/3724]; 95% CI, 4.0%-5.6%) than those from metropolitan areas (3.1% [17/548]; 95% CI, 1.5%-4.7%) (P = 0.08). In multivariable analysis, increasing partner numbers in previous 12 months (adjusted odds ratio [AOR] for three or more partners, 5.11 [95% CI, 2.35-11.08]), chlamydia diagnosis in previous 12 months (AOR, 4.35 [95% CI, 1.52-12.41]) and inconsistent condom use with most recent partner (AOR, 2.90 [95% CI, 1.31-6.40]) were significantly associated with chlamydia in men. In women, increasing partner numbers in previous 12 months (AOR for two partners, 2.59 [95% CI, 1.59-4.23]; AOR for three or more partners, 3.58 [95% CI, 2.26-5.68]), chlamydia diagnosis in previous 12 months (AOR, 3.13 [95% CI, 1.62-6.06]) and age (AOR for 25-29-year-olds, 0.23 [95% CI, 0.12-0.44]) were associated with chlamydia. CONCLUSIONS Chlamydia prevalence is similar in young men and women attending general practice. Testing only those with genital symptoms or a partner with an STI would have missed three-quarters of cases. Most men and women are amenable to being tested in general practice, even in rural and regional areas.