Thixotropic Hydrogels Composed of Self-Assembled Nanofibers of Double-Hydrophobic Elastin-Like Block Polypeptides.

Physically crosslinked hydrogels with thixotropic properties attract considerable attention in the biomedical research field because their self-healing nature is useful in cell encapsulation, as injectable gels, and as bioinks for three-dimensional (3D) bioprinting. Here, we report the formation of thixotropic hydrogels containing nanofibers of double-hydrophobic elastin-like polypeptides (ELPs). The hydrogels are obtained with the double-hydrophobic ELPs at 0.5 wt%, the concentration of which is an order of magnitude lower than those for previously reported ELP hydrogels. Although the kinetics of hydrogel formation is slower for the double-hydrophobic ELP with a cell-binding sequence, the storage moduli G' of mature hydrogels are similar regardless of the presence of a cell-binding sequence. Reversible gel-sol transitions are demonstrated in step-strain rheological measurements. The degree of recovery of the storage modulus G' after the removal of high shear stress is improved by chemical crosslinking of nanofibers when intermolecular crosslinking is successful. This work would provide deeper insight into the structure-property relationships of the self-assembling polypeptides and a better design strategy for hydrogels with desired viscoelastic properties.

Remote-controlled regio- and diastereodifferentiating photodimerization of a dynamic helical peptide-bound 2-substituted anthracene.

Photodimerization of a novel 2-substituted anthracene linked to a right-handed 310-helical nonapeptide induced by long-range chiral information transfer from the remote chiral l-Val residue through a chiral domino effect proceeded in a highly regio- and diastereo-differentiating manner to produce the chiral head-to-head anti-photodimer in 90% relative yield with up to 97% diastereomeric excess.

Prediction of Neurodevelopmental Impairment in Congenital Cytomegalovirus Infection by Early Postnatal Magnetic Resonance Imaging.

INTRODUCTION: Congenital cytomegalovirus infection (CCMVI) may result in neurodevelopmental impairments (NDIs) such as hearing loss, developmental delay, epilepsy, and cerebral palsy. We aimed to investigate the potential for brain magnetic resonance imaging (MRI) to predict NDI in patients with CCMVI. METHODS: We studied infants with CCMVI who were referred to our hospital from April 2010 to October 2018 and underwent a brain MRI within 3 months since birth. We screened for 6 classic presentations of CCMVI including ventriculomegaly, periventricular cysts, hippocampal dysplasia, cerebellar hypoplasia, migration disorders, and white matter abnormalities. Images were interpreted by a blinded pediatric radiologist. NDI was defined as having a developmental quotient <80, hearing dysfunction, blindness, or epilepsy requiring anti-epileptic drugs at approximately 18 months of corrected age. RESULTS: The study involved 42 infants with CCMVI (median gestational age 38 weeks, birthweight 2,516 g). At least one abnormal finding was detected in 28 (67%) infants. Abnormal findings consisted of 3 cerebellar hypoplasia (7%), 7 migration disorders (17%), 26 white matter abnormalities (62%), 12 periventricular cysts (28%), 1 hippocampal dysplasia (2%), and 20 ventriculomegaly (48%). Abnormal findings were significantly more prevalent in infants with clinical symptoms (21/24, 91%) than in those without (7/19, 37%, p < 0.01). For NDI prediction, having ≥2 of ventriculomegaly, periventricular cysts, and white matter abnormality produced the highest Youden index values (0.78). CONCLUSION: Infants with CCMVI with at least 2 of the abovementioned specific brain image abnormalities may be at high risk of developing NDI.

Rheology of Dispersions of High-Aspect-Ratio Nanofibers Assembled from Elastin-Like Double-Hydrophobic Polypeptides.

Elastin-like polypeptides (ELPs) are promising candidates for fabricating tissue-engineering scaffolds that mimic the extracellular environment of elastic tissues. We have developed a "double-hydrophobic" block ELP, GPG, inspired by non-uniform distribution of two different hydrophobic domains in natural elastin. GPG has a block sequence of (VGGVG)5-(VPGXG)25-(VGGVG)5 that self-assembles to form nanofibers in water. Functional derivatives of GPG with appended amino acid motifs can also form nanofibers, a display of the block sequence's robust self-assembling properties. However, how the block length affects fiber formation has never been clarified. This study focuses on the synthesis and characterization of a novel ELP, GPPG, in which the central sequence (VPGVG)25 is repeated twice by a short linker sequence. The self-assembly behavior and the resultant nanostructures of GPG and GPPG were when compared through circular dichroism spectroscopy, atomic force microscopy, and transmission electron microscopy. Dynamic rheology measurements revealed that the nanofiber dispersions of both GPG and GPPG at an extremely low concentration (0.034 wt%) exhibited solid-like behavior with storage modulus G' > loss modulus G" over wide range of angular frequencies, which was most probably due to the high aspect ratio of the nanofibers that leads to the flocculation of nanofibers in the dispersion.

A new approach to risk stratification using fetal MRI to predict outcomes in congenital diaphragmatic hernia: the preliminary retrospective single institutional study.

BACKGROUND: Congenital diaphragmatic hernia (CDH) is a condition with a wide range of severity. Prenatal diagnosis is essential to optimize postnatal management, especially for severe cases. The lung to head ratio (LHR) and liver herniation estimated by prenatal ultrasound has been used as prenatal predictors in CDH. However, reliability of these factors remains to be proven and prediction of outcome from prenatal imaging is still challenging. We propose our new stratification system using lung to liver signal intensity ratio (LLSIR) in fetal MRI, which has been shown to be related to pulmonary maturation. METHODS: Retrospective chart review was conducted on 25 infants with CDH treated from 2009 through 2016 in our hospital. We stratified patients according to fetal T2-weighted MRI as Grade I, detectable ipsilateral lung at the apex; Grade II, undetectable ipsilateral lung at the apex and contralateral LLSR ≥2.0; Grade III, undetectable ipsilateral lung at the apex and contralateral LLSR <2.0. To evaluate this stratification system, we analyzed survival, severity [inhaled nitric oxide (iNO) usage with or without extracorporeal membrane oxygenation (ECMO)], and requirement of patch closure. RESULTS: All 15 patients survived in Grade I, while 2 out of 6 died in Grade II, and 3 out of 4 died in Grade III (P=0.003). Four were severe in Grade I, and all in Grade II and III who survived (P=0.007). One needed patch in Grade I, and all in Grade II and III (OR: 414,238,332; 95% CI, 0-∞). Liver herniation was noted in five patients, and significantly associated with survival (P=0.04), however, neither with severity (P=1.00) nor with the requirement of patch closure (P=0.52). CONCLUSIONS: The risk stratification algorithm using contralateral LLSIR in fetal MRI could be useful and more reliable than liver herniation to predict survival, severity, and need of patch closure. Further investigation is warranted.