Nanoscale segregation of actin nucleation and elongation factors determines dendritic spine protrusion

Actin dynamics drive morphological remodeling of neuronal dendritic spines and changes in synaptic transmission. Yet, the spatiotemporal coordination of actin regulators in spines is unknown. Using single protein tracking and super‐resolution imaging, we revealed the nanoscale organization and dynamics of branched F‐actin regulators in spines. Branched F‐actin nucleation occurs at the PSD vicinity, while elongation occurs at the tip of finger‐like protrusions. This spatial segregation differs from lamellipodia where both branched F‐actin nucleation and elongation occur at protrusion tips. The PSD is a persistent confinement zone for IRSp53 and the WAVE complex, an activator of the Arp2/3 complex. In contrast, filament elongators like VASP and formin‐like protein‐2 move outwards from the PSD with protrusion tips. Accordingly, Arp2/3 complexes associated with F‐actin are immobile and surround the PSD. Arp2/3 and Rac1 GTPase converge to the PSD, respectively, by cytosolic and free‐diffusion on the membrane. Enhanced Rac1 activation and Shank3 over‐expression, both associated with spine enlargement, induce delocalization of the WAVE complex from the PSD. Thus, the specific localization of branched F‐actin regulators in spines might be reorganized during spine morphological remodeling often associated with synaptic plasticity.     

Postpartum depressive symptoms following implementation of the 10 steps to successful breastfeeding program in Kinshasa,Democratic Republic of Congo: A cohort study

BackgroundSocial support and relevant skills training can reduce the risk of postpartum depression (PPD) by reducing the impact of stressors. The 10-step program to encourage exclusive breastfeeding that forms the basis of the Baby-Friendly Hospital Initiative (BFHI) provides both, suggesting it may lessen depressive symptoms directly or by reducing difficulties associated with infant feeding. Our objective was to quantify the association of implementing Steps 1–9 or Steps 1–10 on postpartum depressive symptoms and test whether this association was mediated by breastfeeding difficulties.Methods and findingsWe used data from a breastfeeding promotion trial of all women who gave birth to a healthy singleton between May 24 and August 25, 2012 in 1 of the 6 facilities comparing different BFHI implementations (Steps 1–9, Steps 1–10) to the standard of care (SOC) randomized by facility in Kinshasa, Democratic Republic of Congo. Depressive symptoms, a non-registered trial outcome, was assessed at 14 weeks via the Edinburgh Postnatal Depression Scale (EPDS). Inverse probability weighting (IPW) was used to estimate the association of BFHI implementations on depressive symptoms and the controlled direct association through breastfeeding difficulties at 10 weeks postpartum.A total of 903 mother–infant pairs were included in the analysis. Most women enrolled had previously given birth (76%) and exclusively breastfed at 10 weeks (55%). The median age was 27 (interquartile range (IQR): 23, 32 years). The proportion of women reporting breastfeeding difficulties at week 10 was higher in both Steps 1–9 (75%) and Steps 1–10 (91%) relative to the SOC (67%). However, the number of reported difficulties was similar between Steps 1–9 (median: 2; IQR: 0, 3) and SOC (2; IQR: 0, 3), with slightly more in Steps 1–10 (2; IQR: 1, 3). The prevalence of symptoms consistent with probable depression (EPDS score >13) was 18% for SOC, 11% for Steps 1–9 (prevalence difference [PD] = −0.08; 95% confidence interval (CI): −0.14 to −0.01, p = 0.019), and 8% for Steps 1–10 (PD = −0.11, −0.16 to −0.05; p < 0.001). We found mediation by breastfeeding difficulties. In the presence of any difficulties, the PD was reduced for both Steps 1–9 (−0.15; 95% confidence level (CL): −0.25, −0.06; p < 0.01) and Steps 1–10 (−0.16; 95% CL: −0.25, −0.06; p < 0.01). If no breastfeeding difficulties occurred in the population, there was no difference in the prevalence of probable depression for Steps 1–9 (0.21; 95% CL: −0.24, 0.66; p = 0.365) and Steps 1–10 (−0.03; 95% CL: −0.19, 0.13; p = 0.735). However, a limitation of the study is that the results are based on 2 hospitals randomized to each group.ConclusionsIn conclusion, in this cohort, the implementation of the BFHI steps was associated with a reduction in depressive symptoms in the groups implementing BFHI Steps 1–9 or 1–10 relative to the SOC, with the implementation of Steps 1–10 associated with the largest decrease. Specifically, the reduction in depressive symptoms was observed for women reporting breastfeeding difficulties. PPD has a negative impact on the mother, her partner, and the baby, with long-lasting consequences. This additional benefit of BFHI steps suggests that renewed effort to scale its implementation globally may be beneficial to mitigate the negative impacts of PPD on the mother, her partner, and the baby.Trial registrationClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01428232","term_id":"NCT01428232"}}NCT01428232

In a cohort study, Robert Agler and colleagues investigate the associations between postnatal depression symptoms and implementation of a Baby-Friendly Hospital Initiative in Kinshasa, Democratic Republic of Congo.     

Improvement of a Continuous-Culture Apparatus for Long-Term Use

A glass and plastic apparatus was designed to meet requirements for continuous culture of cells. Some of the improvements incorporated into this apparatus include an all-glass growth vessel with a self-cleaning bottom, special compression fittings to connect tubing to glass tubing, a removable yield reservoir, and a nonwetting gas exhaust assembly. All portions of the system can be autoclaved for sterilization, and medium bottles and pump lines are replaced aseptically.     

The prolactin response to intravenous dextroamphetamine in normal young men and postmenopausal women

D-amphetamine was administered intravenously in doses of 0.1 mg/kg and 0.15 mg/kg to normal young men and postmenopausal women in both morning and evening. No suppression of PRL secretion after amphetamine was found, and, in the postmenopausal women, no significant change in PRL levels in any dose or time condition occured. However, a significant and relatively consistent PRL release was induced in the young men in the evening by the higher dose. This latter response suggests that, in humans, dextroamphetamine can actually stimulate prolactin perhaps by a mechanism other than alteration in dopaminergic tone.