Prospective study of Hepatitis E Virus infection among pregnant women in France.

International audienceBACKGROUND: Hepatitis E Virus (HEV) infection has a poor prognosis among pregnant women from high endemic countries. HEV-prevalence and incidence among pregnant women is unknown in high-income countries such as France. This prospective study was conducted to assess HEV infection in this setting. FINDINGS: An overall HEV prevalence of 7.74% was observed among 315 pregnant women. Seroprevalence was higher in south than in north of France (29.3% vs. 3.6%, p < 0.0001), and women with detectable IgG were older. No IgG seroconversion or IgM detection were observed during pregnancy. CONCLUSIONS: Data suggest that HEV infection is a rare occurrence during pregnancy even in regions of western countries with high seroprevalence rates

Ultraslow Myosin Molecular Motors of Placental Contractile Stem Villi in Humans

Human placental stem villi (PSV) present contractile properties. In vitro mechanics were investigated in 40 human PSV. Contraction of PSV was induced by both KCl exposure (n = 20) and electrical tetanic stimulation (n = 20). Isotonic contractions were registered at several load levels ranging from zero-load up to isometric load. The tension-velocity relationship was found to be hyperbolic. This made it possible to apply the A. Huxley formalism for determining the rate constants for myosin cross-bridge (CB) attachment and detachment, CB single force, catalytic constant, myosin content, and maximum myosin ATPase activity. These molecular characteristics of myosin CBs did not differ under either KCl exposure or tetanus. A comparative approach was established from studies previously published in the literature and driven by mean of a similar method. As compared to that described in mammalian striated muscles, we showed that in human PSV, myosin CB rate constants for attachment and detachment were about 103 times lower whereas myosin ATPase activity was 105 times lower. Up to now, CB kinetics of contractile cells arranged along the long axis of the placental sheath appeared to be the slowest ever observed in any mammalian contractile tissue

Changes in PSV contractile activity were induced by means of either electrical tetanus (panels A and B) or KCl exposure (panels C and D).

<p>Panels A and C: PSV shortening length versus time curves; Panels B and D: PSV tension versus time curves. Just after the onset of stimulus, a slow isotonic shortening at basal tone began, and reached a plateau. Basal tone was the load imposed to the PSV which induced neither shortening nor lengthening of PSV before both KCl exposure and electrical tetanus. PSV was then abruptly submitted to isometric conditions. After a brief overshoot due to the load clamp, PSV tension progressively decreased towards a plateau representing the total isometric tension.</p

Mechanical parameters of human placental stem villi (PSV) and molecular myosin characteristics under electrical tetanus and KCl [0.05M].

<p>Vo: PSV maximum velocity at zero-load; Po: PSV peak isometric tension; G: curvature of the hyperbolic T-V relationship; CB attachment (f₁) and detachment (g₁ and g₂) constants; π: CB unitary force; k_cat: catalytic constant; max.ATPase: maximum myosin ATPase activity. Values are means ±SD. For all parameters presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0108814#pone-0108814-t001" target="_blank">Table 1</a>, there was no statistical difference between tetanus and KCl exposure by applying the unpaired t test and as attested by the p-values.</p><p>Mechanical parameters of human placental stem villi (PSV) and molecular myosin characteristics under electrical tetanus and KCl [0.05M].</p