On the material dependency of peri-implant morphology and stability in healing bone.

The microstructural architecture of remodeled bone in the peri-implant region of screw implants plays a vital role in the distribution of strain energy and implant stability. We present a study in which screw implants made from titanium, polyetheretherketone and biodegradable magnesium-gadolinium alloys were implanted into rat tibia and subjected to a push-out test four, eight and twelve weeks after implantation. Screws were 4 mm in length and with an M2 thread. The loading experiment was accompanied by simultaneous three-dimensional imaging using synchrotron-radiation microcomputed tomography at 5 µm resolution. Bone deformation and strains were tracked by applying optical flow-based digital volume correlation to the recorded image sequences. Implant stabilities measured for screws of biodegradable alloys were comparable to pins whereas non-degradable biomaterials experienced additional mechanical stabilization. Peri-implant bone morphology and strain transfer from the loaded implant site depended heavily on the biomaterial utilized. Titanium implants stimulated rapid callus formation displaying a consistent monomodal strain profile whereas the bone volume fraction in the vicinity of magnesium-gadolinium alloys exhibited a minimum close to the interface of the implant and less ordered strain transfer. Correlations in our data suggest that implant stability benefits from disparate bone morphological properties depending on the biomaterial utilized. This leaves the choice of biomaterial as situational depending on local tissue properties.

High-resolution ex vivo analysis of the degradation and osseointegration of Mg-xGd implant screws in 3D.

Biodegradable magnesium (Mg) alloys can revolutionize osteosynthesis, because they have mechanical properties similar to those of the bone, and degrade over time, avoiding the need of removal surgery. However, they are not yet routinely applied because their degradation behavior is not fully understood. In this study we have investigated and quantified the degradation and osseointegration behavior of two biodegradable Mg alloys based on gadolinium (Gd) at high resolution. Mg-5Gd and Mg-10Gd screws were inserted in rat tibia for 4, 8 and 12 weeks. Afterward, the degradation rate and degradation homogeneity, as well as bone-to-implant interface, were studied with synchrotron radiation micro computed tomography and histology. Titanium (Ti) and polyether ether ketone (PEEK) were used as controls material to evaluate osseointegration. Our results showed that Mg-5Gd degraded faster and less homogeneously than Mg-10Gd. Both alloys gradually form a stable degradation layer at the interface and were surrounded by new bone tissue. The results were correlated to in vitro data obtained from the same material and shape. The average bone-to-implant contact of the Mg-xGd implants was comparable to that of Ti and higher than for PEEK. The results suggest that both Mg-xGd alloys are suitable as materials for bone implants.

Scaling the U-net: segmentation of biodegradable bone implants in high-resolution synchrotron radiation microtomograms.

Highly accurate segmentation of large 3D volumes is a demanding task. Challenging applications like the segmentation of synchrotron radiation microtomograms (SRµCT) at high-resolution, which suffer from low contrast, high spatial variability and measurement artifacts, readily exceed the capacities of conventional segmentation methods, including the manual segmentation by human experts. The quantitative characterization of the osseointegration and spatio-temporal biodegradation process of bone implants requires reliable, and very precise segmentation. We investigated the scaling of 2D U-net for high resolution grayscale volumes by three crucial model hyper-parameters (i.e., the model width, depth, and input size). To leverage the 3D information of high-resolution SRµCT, common three axes prediction fusing is extended, investigating the effect of adding more than three axes prediction. In a systematic evaluation we compare the performance of scaling the U-net by intersection over union (IoU) and quantitative measurements of osseointegration and degradation parameters. Overall, we observe that a compound scaling of the U-net and multi-axes prediction fusing with soft voting yields the highest IoU for the class "degradation layer". Finally, the quantitative analysis showed that the parameters calculated with model segmentation deviated less from the high quality results than those obtained by a semi-automatic segmentation method.

Multimodal ex vivo methods reveal that Gd-rich corrosion byproducts remain at the implant site of biodegradable Mg-Gd screws.

Extensive research is being conducted on magnesium (Mg) alloys for bone implant manufacturing, due to their biocompatibility, biodegradability and mechanical properties. Gadolinium (Gd) is among the most promising alloying elements for property control in Mg alloy implants; however, its toxicity is controversial. Investigating Gd behavior during implant corrosion is thus of utmost importance. In this study, we analyzed the degradation byproducts at the implant site of biodegradable Mg-5Gd and Mg-10Gd implants after 12 weeks healing time, using a combination of different imaging techniques: histology, energy-dispersive x-ray spectroscopy (EDX), x-ray microcomputed tomography (µCT) and neutron µCT. The main finding has been that, at the healing time in exam, the corrosion appears to have involved only the Mg component, which has been substituted by calcium and phosphorus, while the Gd remains localized at the implant site. This was observed in 2D by means of EDX maps and extended to 3D with a novel application of neutron tomography. X-ray fluorescence analysis of the main excretory organs also did not reveal any measurable accumulation of Gd, further reinforcing the conclusion that very limited or no removal at all of Gd-alloy happened during degradation. STATEMENT OF SIGNIFICANCE: Gadolinium is among the most promising alloying elements for property control in biodegradable magnesium alloy implants, but its toxicity is controversial and its behavior during corrosion needs to be investigated. We combine 2D energy dispersive x-ray spectroscopy and 3D neutron and x-ray tomography to image the degradation of magnesium-gadolinium implants after 12 weeks of healing time. We find that, at the time in exam, the corrosion has involved only the magnesium component, while the gadolinium remains localized at the implant site. X-ray fluorescence analysis of the main excretory organs also does not reveal any measurable accumulation of Gd, further reinforcing the conclusion that very limited or no removal at all of Gd-alloy has happened during degradation.

Maternal stress during pregnancy and early childhood development.

We estimate the impact of prenatal stress on early childhood development outcomes known as "middle years" or intermediate outcomes, which has not been studied previously. Using a unique measure of actual maternal stress induced by a large earthquake, we find that relative to children that were not exposed, in utero maternal stress reduces children's cognitive skills and socio-emotional problems by age 3, and that the effects are heterogeneous. The negative impacts on cognitive skills occur during the first trimester of pregnancy and are found among both low and high-income children, and boys and girls. The harmful effects on socio-emotional behaviors occur when stress is experienced in the last trimester of pregnancy.

Hormonally controlled ILC antigen presentation potential is reduced during pregnancy.

Strategically located in mucosal barriers, innate lymphoid cells (ILCs) are relevant in local containment and tolerance of commensal microflora. ILCs have been recently described at the fetomaternal interface, where the development of a semi-allogeneic fetus can only succeed in a well-controlled immune environment. We postulate that ILCs adapt their antigen presentation capacity to protect pregnancy from excessive immune responses. Human ILCs were studied in deciduae of term pregnancies, peripheral blood and in in vitro generated ILCs. Fresh isolated lymphocytes or cells treated with pregnancy-related factors were investigated. The fetal antigen rejection-based CBA/J × DBA/2J mouse model (poor outcome pregnant mice; POPM) was used to characterize ILC antigen presentation potential in normal and immunologically disturbed pregnancies. ILC antigen presentation potential was characterized by flow cytometry and qPCR. We discovered that the distribution of ILC subsets changed during both human and murine pregnancy. Moreover, the pregnancy was accompanied by reduced MHCII expression in splenic ILCs during normal pregnancy (CBA/J × BALB/c; good outcome pregnant mice; GOPM) but increased in splenic and intestinal ILCs of CBA/J × DBA/2J mice. In vitro, splenic ILCs from pregnant mice increased MHCII expression after stimulation with IL-1ß and IL-23. In contrast, uterine ILCs displayed lower MHCII expression, which remained unchanged after stimulation. Finally, pregnancy-related factors and hormones present in the uterine environment reduced antigen presentation potential of human ILCs in vitro. Together, these data indicate that, during pregnancy, peripheral and especially uterine ILCs adapt their antigen presenting potential to maintain a level of tolerance and support pregnancy.

Pregnancy status alters IL-21-mediated effects on murine B lymphocytes.

A favorable outcome of pregnancy depends greatly on an adequate balance of immune protection and fetal tolerance at the fetomaternal interface. IL-21 is a pro-inflammatory cytokine associated with altering immune responses in autoimmune diseases. IL-21 has pleiotropic functions, including induction of Th17 T cells, inhibition of Treg development, and modulation of antibody responses of B lymphocytes. Genetic polymorphisms of IL21 have been associated to poor pregnancy outcomes. However, the mechanism of IL-21 actions needs further evaluation. Here, we postulate that IL-21 affects splenic B cell function during pregnancy and shapes immune responses. We show that splenic B cells from CBA/J × BALB/c mice with favorable pregnancy outcome expressed lower IL21R levels than in CBA/J × DBA/2J mice, a mouse model for immune-induced bad pregnancy outcome. As a consequence, B cells from CBA/J × BALB/c mice reacted less sensitively to IL-21 than B cells from non-pregnant mice (NPM) or from CBA/J × DBA/2J mice. Also, LPS-induced apoptotic rates were altered in NPM and CBA/J × DBA/2J but not in CBA/J × BALB/c mice. This is accompanied by improved survival of B cells that produce the anti-inflammatory cytokine IL-10 upon stimulation with LPS. We also observed lower numbers of CD4+CXCR5+Bcl-6+ follicular T-helper cells (Tfh) in normal pregnant mice, compared to non-pregnant and mice with disturbed pregnancies. Our data indicate that alterations of the Tfh/IL-21/IL-10 axis may have important influence on pregnancy outcome.

Harsh parenting during early childhood and child development.

We study the relationship between harsh parenting strategies, including psychological and physical aggressions that do not constitute abuse, on early childhood cognitive and socio-emotional development. We estimate a value-added model that controls for a rich set of child, mother, and family characteristics, from a nationally representative sample of Chilean children aged 52-83 months. We find harsh parenting is significantly associated with lower verbal skills (Peabody Picture Vocabulary Test) of a magnitude of 0.06 standard deviations, and with increased behavioral problems (Child Behavior Check List), by 0.11 standard deviations, including internalization, externalization, and sleep problems. We also find that the more systematic (persistent) harsh parenting is, the stronger the association; the association is similar for boys and girls; reaches its peak at about 5 years of age; and it is stronger for children with less educated mothers.

Analysis of the bone ultrastructure around biodegradable Mg-xGd implants using small angle X-ray scattering and X-ray diffraction.

Magnesium alloys are increasingly researched as temporary biodegradable metal implants in bone applications due to their mechanical properties which are more similar to bone than conventional implant metals and the fact that Magnesium occurs naturally within the body. However, the degradation processes in vivo and in particular the interaction of the bone with the degrading material need to be further investigated. In this study we are presenting the first quantitative comparison of the bone ultrastructure formed at the interface of biodegradable Mg-5Gd and Mg-10Gd implants and titanium and PEEK implants after 4, 8 and 12 weeks healing time using two-dimensional small angle X-ray scattering and X-ray diffraction. Differences in mineralization, orientation and thickness of the hydroxyapatite are assessed. We find statistically significant (p < 0.05) differences for the lattice spacing of the (310)-reflex of hydroxyapatite between titanium and Mg-xGd materials, as well as for the (310) crystal size between titanium and Mg-5Gd, indicating a possible deposition of Mg within the bone matrix. The (310) lattice spacing and crystallite size further differ significantly between implant degradation layer and surrounding bone (p < 0.001 for Mg-10Gd), suggesting apatite formation with significant amounts of Gd and Mg within the degradation layer. STATEMENT OF SIGNIFICANCE: Biodegradable Magnesium-based alloys are emerging as a viable alternative for temporary bone implant applications. However, in order to understand if the degradation of the implant material influences the bone ultrastructure, it is necessary to study the bone structure using high-resolution techniques. We have therefore employed 2D small angle X-ray scattering and X-ray diffraction to study the bone ultrastructure surrounding Magnesium-Gadolinium alloys as well as Titanium and PEEK alloys at three different healing times. This is the first time, that the bone ultrastructure around these materials is directly compared and that a statistical evaluation is performed. We found differences indicating a possible deposition of Mg within the bone matrix as well as a local deposition of Mg and/or Gd at the implant site. DATA AVAILABILITY STATEMENT: The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.

Systematically Designed Periodic Electrophoretic Deposition for Decorating 3D Carbon-Based Scaffolds with Bioactive Nanoparticles.

The coating of porous scaffolds with nanoparticles is crucial in many applications, for example to generate scaffolds for catalysis or to make scaffolds bioactive. A standard and well-established method for coating surfaces with charged nanoparticles is electrophoresis, but when used on porous scaffolds, this method often leads to a blockage of the pores so that only the outermost layers of the scaffolds are coated. In this study, the electrophoretic coating process is monitored in situ and the kinetics of nanoparticle deposition are investigated. This concept can be extended to design a periodic electrophoretic deposition (PEPD) strategy, thus avoiding the typical blockage of surface pores. In the present work we demonstrate successful and homogeneous electrophoretic deposition of hydroxyapatite nanoparticles (HAn, diameter ≤200 nm) on a fibrous graphitic 3D structure (ultralightweight aerographite) using the PEPD strategy. The microfilaments of the resulting scaffold are covered with HAn both internally and on the surface. Furthermore, protein adsorption assays and cell proliferation assays were carried out and revealed that the HAn-decorated aerographite scaffolds are biocompatible. The HAn decoration of the scaffolds also significantly increases the alkaline phosphatase activity of osteoblast cells, showing that the scaffolds are able to promote their osteoblastic activity.

A Kinetic Study of CD83 Reveals an Upregulation and Higher Production of sCD83 in Lymphocytes from Pregnant Mice.

For the normal development of pregnancy, a balance between immune tolerance and defense is crucial. However, the mechanisms mediating such a balance are not fully understood. CD83 is a transmembrane protein whose expression has been linked to anti-inflammatory functions of T and B cells. The soluble form of CD83, released by cleavage of the membrane-bound protein, has strong anti-inflammatory properties and was successfully tested in different mouse models. It is assumed that this molecule contributes to the establishment of immune tolerance. Therefore, we postulated that the expression of CD83 is crucial for immune tolerance during pregnancy in mice. Here, we demonstrated that the membrane-bound form of CD83 was upregulated in T and B cells during allogeneic murine pregnancies. An upregulation was also evident in the main splenic B cell subtypes: marginal zone, follicular zone, and transitional B cells. We also showed that there was an augmentation in the number of CD83+ cells toward the end of pregnancy within splenic B and CD4+ T cells, while CD83+ dendritic cells were reduced in spleen and inguinal lymph nodes of pregnant mice. Additionally, B lymphocytes in late-pregnancy presented a markedly higher sensitivity to LPS in terms of CD83 expression and sCD83 release. Progesterone induced a dosis-dependent upregulation of CD83 on T cells. Our data suggest that the regulation of CD83 expression represents a novel pathway of fetal tolerance and protection against inflammatory threats during pregnancy.

Does adolescent motherhood affect education and labor market outcomes of mothers? A study on young adult women in Chile during 1990-2013.

OBJECTIVES: We analyze the impact of adolescent motherhood on several education and labor market outcomes in Chile over the 1990-2013 period. We explore whether effects are different across income levels, timing of adolescent births, and three sub-periods. METHODS: Using the CASEN national household survey, we applied propensity score-matching methods on two samples of women aged 24: one for women in the 2009-2013 period and another sample of 24-year-old women living with their mother between 1990-2013. RESULTS: In both samples, adolescent motherhood has negative effects on educational outcomes (high school completion, enrollment in technical institutes and universities, and years of education) and on labor outcomes of non-poor women. Childbearing in early adolescence is associated with worse outcomes, and the adverse effects of adolescent motherhood on education and labor outcomes have diminished over the period. CONCLUSIONS: Similar to results in developed countries, adolescent motherhood has negative consequences on women's education and labor outcomes, particularly on women that become mothers early in adolescence. Public policies aimed at reducing teen motherhood will have important effects on young women's education and employment.

Human embryonic stem cells express elevated levels of multiple pro-apoptotic BCL-2 family members.

Two of the greatest challenges in regenerative medicine today remain (1) the ability to culture human embryonic stem cells (hESCs) at a scale sufficient to satisfy clinical demand and (2) the ability to eliminate teratoma-forming cells from preparations of cells with clinically desirable phenotypes. Understanding the pathways governing apoptosis in hESCs may provide a means to address these issues. Limiting apoptosis could aid scaling efforts, whereas triggering selective apoptosis in hESCs could eliminate unwanted teratoma-forming cells. We focus here on the BCL-2 family of proteins, which regulate mitochondrial-dependent apoptosis. We used quantitative PCR to compare the steady-state expression profile of all human BCL-2 family members in hESCs with that of human primary cells from various origins and two cancer lines. Our findings indicate that hESCs express elevated levels of the pro-apoptotic BH3-only BCL-2 family members NOXA, BIK, BIM, BMF and PUMA when compared with differentiated cells and cancer cells. However, compensatory expression of pro-survival BCL-2 family members in hESCs was not observed, suggesting a possible explanation for the elevated rates of apoptosis observed in proliferating hESC cultures, as well as a mechanism that could be exploited to limit hESC-derived neoplasms.