Chlamydia trachomatis anorectal infections by LGV (L1, L2 and L2b) and non-LGV serotypes in symptomatic patients in Buenos Aires, Argentina.

BACKGROUND: Chlamydia trachomatis (CT) can infect the anorectum producing various signs and symptoms. There is scarce literature regarding the differences between LGV and non-LGV CT anorectal manifestations. We compare the clinical spectrum of LGV and non-LGV infections. METHODS: Patients over 18 years with presumptive infectious anorectal symptoms were examined in two healthcare centres in Buenos Aires. The patients were studied and treated according to current sexually transmitted infection guidelines. Anorectal swabs were collected to detect and genotype CT. RESULTS: A three-year-long study on 317 patients with anorectal symptoms showed 45.11% CT infection (85% LGV strains). Of 140 samples, 92 were sequenced: 80/119 LGV (L2b 45%, L1 32.5% and L2 22.5%) and 12/21 non-LGV. Older age and HIV+ status were significantly higher in the LGV group. Anal discharge, bleeding, severe proctitis and anal ulcers were more common in the LGV group. Multivariate logistic regression analysis revealed that HIV infection, anorectal bleeding and oro-anal sex are independent predictors of LGV infection. CONCLUSIONS: In patients with anorectal symptoms, LGV serovars predominate over non-LGV ones. Clinical manifestations are not pathognomonic of a specific biovar. If genotyping is not available, having clinical predictors may help to presume an LGV infection and define length of treatment.

High Plasticity of New Granule Cells in the Aging Hippocampus.

During aging, the brain undergoes changes that impair cognitive capacity and circuit plasticity, including a marked decrease in production of adult-born hippocampal neurons. It is unclear whether development and integration of those new neurons are also affected by age. Here, we show that adult-born granule cells (GCs) in aging mice are scarce and exhibit slow development, but they display a remarkable potential for structural plasticity. Retrovirally labeled 3-week-old GCs in middle-aged mice were small, underdeveloped, and disconnected. Neuronal development and integration were accelerated by voluntary exercise or environmental enrichment. Similar effects were observed via knockdown of Lrig1, an endogenous negative modulator of neurotrophin receptors. Consistently, blocking neurotrophin signaling by Lrig1 overexpression abolished the positive effects of exercise. These results demonstrate an unparalleled degree of plasticity in the aging brain mediated by neurotrophins, whereby new GCs remain immature until becoming rapidly recruited to the network by activity.

A disynaptic feedback network activated by experience promotes the integration of new granule cells.

Experience shapes the development and connectivity of adult-born granule cells (GCs) through mechanisms that are poorly understood. We examined the remodeling of dentate gyrus microcircuits in mice in an enriched environment (EE). Short exposure to EE during early development of new GCs accelerated their functional integration. This effect was mimicked by in vivo chemogenetic activation of a limited population of mature GCs. Slice recordings showed that mature GCs recruit parvalbumin γ-aminobutyric acid-releasing interneurons (PV-INs) that feed back onto developing GCs. Accordingly, chemogenetic stimulation of PV-INs or direct depolarization of developing GCs accelerated GC integration, whereas inactivation of PV-INs prevented the effects of EE. Our results reveal a mechanism for dynamic remodeling in which experience activates dentate networks that "prime" young GCs through a disynaptic feedback loop mediated by PV-INs.