A hydraulic feedback loop between mesendoderm cell migration and interstitial fluid relocalization promotes embryonic axis formation in zebrafish

Interstitial fluid (IF) accumulation between embryonic cells is thought to be important for embryo patterning and morphogenesis. Here, we identify a positive mechanical feedback loop between cell migration and IF relocalization and find that it promotes embryonic axis formation during zebrafish gastrulation. We show that anterior axial mesendoderm (prechordal plate [ppl]) cells, moving in between the yolk cell and deep cell tissue to extend the embryonic axis, compress the overlying deep cell layer, thereby causing IF to flow from the deep cell layer to the boundary between the yolk cell and the deep cell layer, directly ahead of the advancing ppl. This IF relocalization, in turn, facilitates ppl cell protrusion formation and migration by opening up the space into which the ppl moves and, thereby, the ability of the ppl to trigger IF relocalization by pushing against the overlying deep cell layer. Thus, embryonic axis formation relies on a hydraulic feedback loop between cell migration and IF relocalization

The effect of pH, aluminum, and chelator manipulations on the growth of acidic and circumneutral species of Asterionella

The growth rates of two diatoms, acidophilic Asterionella ralfsii and circumneutral A. formosa , were differentially affected by varying pH, Al, and EDTA in chemically defined media. Free Al ion concentration increased as pH and EDTA concentration decreased. Free trace metal ion concentration decreased as EDTA levels increased but increased by orders of magnitude upon addition of Al. pH had an overriding species specific effect on growth rate; at low pH A. ralfsii had higher growth rates than A. formosa and vice versa at high pH. For both species higher EDTA levels depressed growth rates. Moderate additions of Al generally resulted in growth stimulation. The growth rate stimulations, especially at 200 and 400 μg L −1 Al additions, correlate to increases in free trace metal ion concentrations. The EDTA-AI interaction effects on growth rate were both pH and concentration dependent: at pH 7 both species were stimulated by addition of Al at all EDTA levels (except A. ralfsii at 5.0 mM EDTA and A. formosa at 0.5 mNM EDTA); at pH 6 Al addition either stimulated or had no effect on the growth rates of both species (except at low EDTA and high Al levels); at pH 5 A. formosa did not grow and additions of 200 μg L −1 Al stimulated growth of A. ralfsii . It is likely that the effect of pH, Al, and EDTA on speciation of essential or toxic trace metals affects growth rates of these diatoms in a species specific manner.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43905/1/11270_2004_Article_BF00282626.pd

Are patient outcomes improved by models of professionally-led community HIV management which aim to be person-centred? A systematic review of the evidence

UNAIDS advocates person-centred care (PCC) for people living with HIV/AIDS (PLWHA) to improve outcomes and wellbeing. We appraised the evidence of person-centred models of community HIV care delivered or led by trained healthcare professionals and its impact on care outcomes. A systematic review was conducted in line with PRISMA guidance. Six electronic databases (CINAHL, Embase, PubMed, Medline, PsycINFO and Web of Science) were searched from January 1980 to April 2019. We included primary studies of any design of PCC models; for adults aged ≥15 years; that were delivered or led by trained HCP. Data were extracted including study location, design, quality, outcomes measured and effectiveness. Five out of 1393 studies met the inclusion criteria, of which four were from a high-income country and one a lower-middle income country. Of the PCC components (physical, psychological, social and spiritual wellbeing) delivered alongside HIV clinical management, one study delivered 2, two studies delivered 3 and two studies delivered all 4 components. This review highlights the lack of outcome evidence for person-centred HIV care, and of concurrent focus on all domains of concern for PLWHA within interventions. Clear articulation of the meaning, practice of PCC and implementation strategies are needed to meet policy recommendations