Cationic Half-Sandwich Tetrahydrofluorenyl Rare-Earth Metal Complexes as Stable Single-Site Catalysts for (Co)Polymerization of Styrene and Butadiene.

As indenyl-derivates, the tetrahydrofluorenyl ligands had an expanded "wingspan" with considerable steric hindrance. In this text, the rare-earth metal complexes bearing tetrahydrofluorenyl ligands have been synthesized and fully characterized by NMR (1H and 13C) and X-ray diffraction analyses. Upon the activation by [Ph3C][B(C6F5)4], all the scandium complexes exhibited excellent catalytic activity for highly syndioselective polymerization of styrene with a narrow molecular weight distribution (Mw/Mn < 2.0), suggesting the beneficial influence of tetrahydrofluorenyl ligands in stabilizing the single-site active species during the polymerization. Moreover, the scandium-based catalytic systems also promoted the 1,4-regular polymerization of butadiene and its copolymerization with styrene, affording diblock copolymers featuring a highly syndiotactic polystyrene block and a 1,4-specific PBD block. The kinetics investigation revealed the huge gap in TMS-Sc-catalyzed polymerization reactivity ratios (rBD/rSt > 300) between butadiene and styrene, and this further proved the block structure of styrene-butadiene copolymers. The morphology and mechanical property of the selected diblock copolymer were, respectively, investigated by atomic force microscopy and stress-strain experiments.

Rare-Earth-Metal Complexes Bearing an Iminodibenzyl-PNP Pincer Ligand: Synthesis and Reactivity toward 3,4-Selective Polymerization of 1,3-Dienes.

A PNP-pincer ligand provides a versatile ligation framework, which is highly useful in organometallic chemistry and catalytic chemistry. In this work, by a de novo strategy, a simple and efficient synthetic pathway, has been developed to prepare the new iminodibenzyl-based PNP pincer proligand imin-RPNP(Li or H) (R = isopropyl, phenyl). By employing salt metathesis or direct alkyl elimination, we successfully synthesized a series of iminodibenzyl-PNP rare-earth-metal (Ln = Sc, Y, Dy, Ho, Er, Tm, Lu) complexes and characterized them by NMR and X-ray diffraction analyses. Upon addition of a borate and triisobutylaluminum (TIBA), the rare-earth-metal complexes 2-Y, 2-Dy, 2-Ho, 2-Er, and 2-Tm bearing the imin-PhPNP ligand exhibited unexpectedly high 3,4-selectivity (up to 95%) for the polymerization of 1,3-dienes (isoprene and myrcene); in particular, the chosen yttrium complex 2-Y promoted the 1,3-diene polymerization in a living manner. A computational study suggested that the sterically congested configuration around the metal center imposed by the imin-RPNP ligand might be the main reason for this unusual selectivity.

Long Non-coding RNA TPT1-AS1 Suppresses APC Transcription in a STAT1-Dependent Manner to Increase the Stemness of Colorectal Cancer Stem Cells.

Cancer stem cells (CSCs) are the major culprits leading to a new level of complexity and the consequential therapy resistance and disease recurrence in colorectal cancer (CRC). This study focuses on the effect of long non-coding RNA (lncRNA) TPT1-AS1 and its associated molecules on the stemness maintenance of CRC stem cells. TPT1-AS1 was identified as a significantly upregulated gene in CRC using the GSE146587 dataset. Stem cells from CRC HCT116 and CACO2 cells were isolated. TPT1-AS1 was significantly highly expressed in the CSCs compared to non-stem cells. Downregulation of TPT1-AS1 reduced the stemness of the CRC stem cells. TPT1-AS1 recruited STAT1 to the promoter region of APC to suppress APC transcription. Further upregulation of STAT1 or downregulation of APC blocked the role of TPT1-AS1 silencing and restored the malignant behaviors of CSC stem cells. APC inactivated the Wnt/ß-catenin pathway. Overexpression of STAT1 restored the levels of cyclin D1 and ß-catenin in cells suppressed by TPT1-AS1 silencing. In summary, this work demonstrates that TPT1-AS1 recruits STAT1 to suppress APC transcription and increase the stemness of colorectal CSCs via Wnt/ß-catenin activation.

Access to Derivatizable Octahydrofluorenyl Ligand: Half-Sandwich Rare-Earth Metal Complexes for Highly Syndiospecific (Co)Polymerization of Styrene.

A simple and facile synthetic pathway for accessing new derivatizable bulky-demanding octahydrofluorenyl (OHF) ligands has been developed, and a series of half-sandwich rare-earth metal (Sc, Y, Lu) complexes bearing the OHF ancillary ligands have been synthesized. In conjunction with a borate, the OHF-ligated Sc complexes exhibited high catalytic activity for styrene (co)polymerization to afford polymers with highly syndiotactic polystyrene sequence (>99% rrrr).

Can perinatal outcomes of fetal omphalocele be improved at a tertiary center in South China?

OBJECTIVE: To assess the efficacy of positive feedback closed-loop management system (PFCMS) protocol in influencing parents' decision about pregnancy continuation in pregnancies diagnosed with omphalocele. METHODS: This was a retrospective cohort study of patients who were diagnosed with fetal omphalocele prior to 20 weeks' gestation by ultrasound and were referred to Fetal Care Center at a mainland Chinese medical center during an 11-year period. Two management strategies were offered during the two stages of the study period: a single consultant with a routine protocol and a multidisciplinary support team with PFCMS, respectively. We analyzed the two protocols influencing parents' decision about pregnancy continuation. RESULTS: Forty-nine patients diagnosed with fetal omphalocele were included in this study. In Group A including 16 patients with routine protocol during the first stage of the study period, the majority opted for termination, and only five continued the pregnancy. In Group B including 33 patients with PFCMS during the second stage of the study period, less than one third chose TOP, and 23 ended in live births. There was a significantly lower TOP rate in patients treated with the PFCMS protocol. CONCLUSION: The PFCMS protocol may be an efficient approach in managing pregnancies complicated by omphalocele, which may help in preventing unnecessary pregnancy terminations.

Analysis of the clinical outcomes of fetal bowel dilatation combined with other abnormal ultrasonographic features.

OBJECTIVES: To explore the significance of fetal bowel dilatation combined with other abnormal ultrasound features in the diagnosis of gastrointestinal malformation. METHODS: A retrospective study of fetuses with bowel dilatation was performed, from August 2012 to October 2015. All the cases were identified from the ultrasound database and all observations of the relationship of prenatal abnormal abdominal ultrasound features and intestinal malformation were performed through the infancy stage. RESULTS: We found 52 fetuses with prenatal suspicion of bowel dilatation. Of these, 20 cases were surgically confirmed to have intestinal malformation, 13 cases had no abnormal bowel loops after birth, 8 cases had abnormal intestinal features while no surgical intervention was performed after birth, 10 cases were lost to follow-up and 1 fetus died in utero at 34 weeks of gestation. Forty cases with full data were divided into three groups, including Group A (Small bowel dilatation combined with other features vs. Isolated small bowel dilatation), Group B (Colonic bowel dilatation combined with other features vs. Isolated colonic bowel dilatation) and Group C (Bowel dilatation combined with other features vs. Isolated bowel dilatation). The intestinal malformation occurrence rates were 73.33% vs. 31.25% in Group A, 50% vs. 25% in Group B, and 70% vs. 30% in Group C. These results suggest that malformation occurs at a lesser frequency in simple bowel dilatation versus bowel dilatation in combination with other abnormal ultrasound features (p = .026), similarly in simple small bowel dilatation versus small bowel dilatation in combination with other abnormal ultrasound features (p = .032). CONCLUSIONS: Prenatal bowel dilatation in combination with other abnormal ultrasound features, especially small bowel dilatation in combination with other abnormal ultrasound features, detected in the second and third trimesters, tended to indicate intestinal malformation, which contributes to enhance the accuracy of prenatal diagnosis of intestinal malformation.