Intrinsically unidirectional chemically fuelled rotary molecular motors.

Biological systems mainly utilize chemical energy to fuel autonomous molecular motors, enabling the system to be driven out of equilibrium1. Taking inspiration from rotary motors such as the bacterial flagellar motor2 and adenosine triphosphate synthase3, and building on the success of light-powered unidirectional rotary molecular motors4-6, scientists have pursued the design of synthetic molecular motors solely driven by chemical energy7-13. However, designing artificial rotary molecular motors operating autonomously using a chemical fuel and simultaneously featuring the intrinsic structural design elements to allow full 360° unidirectional rotary motion like adenosine triphosphate synthase remains challenging. Here we show that a homochiral biaryl Motor-3, with three distinct stereochemical elements, is a rotary motor that undergoes repetitive and unidirectional 360° rotation of the two aryl groups around a single-bond axle driven by a chemical fuel. It undergoes sequential ester cyclization, helix inversion and ring opening, and up to 99% unidirectionality is realized over the autonomous rotary cycle. The molecular rotary motor can be operated in two modes: synchronized motion with pulses of a chemical fuel and acid-base oscillations; and autonomous motion in the presence of a chemical fuel under slightly basic aqueous conditions. This rotary motor design with intrinsic control over the direction of rotation, simple chemical fuelling for autonomous motion and near-perfect unidirectionality illustrates the potential for future generations of multicomponent machines to perform mechanical functions.

Ssc-mir-221-3p regulates melanin production in Xiang pigs melanocytes by targeting the TYRP1 gene.

BACKGROUND: MicroRNAs (miRNAs) are small endogenous non-coding RNAs that regulate gene expression by down-regulating it. Several studies have suggested that miRNAs plays a crucial role in mammalian skin color production. The TYRP1 gene, a member of the tyrosine family, is an important candidate gene that affects melanogenesis. This study aimed to identify genes and miRNAs that affect melanin production in Xiang pigs by transcriptome sequencing, and to validate their targeted regulatory relationships. RESULTS: 17 miRNAs and 1,230 genes were significantly differentially expressed (P < 0.05) in the black and white skin tissues of Jianbai Xiang pigs. miRNA-221-3p was identified as a candidate miRNA for melanin formation and its target gene, TYRP1, was selected. The TYRP1 gene is a member of the TYR gene family, which evolved from the TYR gene through chromosome segmental duplication. The function of the gene was highly conserved throughout the evolutionary process. overexpression of TYRP1 gene significantly increased the expression of TYR, TYRP1, and DCT genes P < 0.01, which led to an increase in the relative content of melanin. Silencing of TYRP1 through the use of TYRP1-siRNA significantly reduced the expression of TYR, TYRP1, and DCT genes in Jianbai Xiang pig melanocytes P < 0.01, which in turn decreased the relative melanin content. The targeted binding relationship between ssc-miR-221-3p and TYRP1 gene was validated. After transfection of porcine melanocytes with ssc-miR-221-3p mimic, the expression of ssc-miR-221-3p was significantly up-regulated (P < 0.01). Furthermore, the mRNA and protein levels of TYR, TYRP1, and DCT genes were significantly down-regulated (P < 0.01), and melanin content in cells was significantly reduced (P < 0.01). CONCLUSION: The TYRP1 gene affects melanogenesis in melanocytes of Jianbai Xiang pigs, and ssc-miR-221-3p targets the TYRP1 gene to regulate melanogenesis in melanocytes of Jianbai Xiang pigs.

The Effect of Intramolecular Hydrogen Bonds on the Rotational Barriers of the Biaryl C-C Axis.

Axially chiral compounds are attracting more attention recently. Although hydrogen bonds are reported as a vital weak force that influences the properties of compounds, the effect of intramolecular hydrogen bonds on the atropisomerization of the Caryl -Caryl single bonds has not yet been well quantitatively investigated. Here, a series of axially chiral biaryl compounds were synthesized to study the effect of hydrogen bonds on the rotational barriers of the biaryl C-C axis. Experimental studies demonstrated that the rotational barrier of hydrogen bonding biaryl 9 was significantly lower (46.7 kJ mol-1 ) than biaryl 10 without hydrogen bonds. Furthermore, theoretical studies revealed that the intramolecular hydrogen bond stabilized the transition state (TS) of tri-ortho-substituted biaryl 9, relieving the steric repulsion in the TS. We believe that this study will provide chemists with a deeper understanding of the atropisomerization process of axially chiral biaryl compounds.

Determinants of low birth weight among newborns delivered in China: a prospective nested case-control study in a mother and infant cohort.

This nested case-control study aimed to investigate the determinants of low birth weight among newborn babies delivered in Shenzhen, Guangdong, China. We recorded socio-demographic data, health status before pregnancy, pregnancy outcomes and complications in a Shenzhen mother and infant cohort. Among 8951 cases, 401 (4.48%) had low birth weight and 1.65% were full-term with LBW. Maternal body mass index, family income, history of pregnancy, hypertension before pregnancy, vaginal bleeding in 1st trimester, pregnancy-related diabetes, hypertension, placenta previa, placental abruption, premature rupture of membrane, oligohydramnios, and placental types were significantly associated with low birth weight (P < 0.05). In this study, high-risk and mainly preventable factors were linked to low birth weight. Adequate antenatal care, proper maternal nutrition and implementation of proven strategies to prevent high-risk factors may be effective ways to reduce the incidence of low birth weight.

What is already known on this subject? Low birth weight (LBW) is associated with adverse perinatal outcomes and neonatal disease and death. The aim of this study was to investigate the factors affecting low birth weight infants in a developed region in China.What the results of this study add? According to this study, the incidence of LBW in Shenzhen of China was 4.48%. Maternal body mass index, family income, history of pregnancy, hypertension before pregnancy, vaginal bleeding in 1st trimester, pregnancy-related diabetes, hypertension, placenta previa, placental abruption, premature rupture of membrane, oligohydramnios, and placental types were significantly associated with LBW.What the implications are of these findings for clinical practice and/or further research? This study suggests that good prenatal care, maternal nutrition and implementation of proven strategies to manage high-risk factors are needed to prevent and reduce the incidence of LBW. Health care providers could use our findings to identify good antenatal care and provide individualised interventions targeting women with risk factors.

Constructing High Efficiency CoZnx Mn2-x O4 Electrocatalyst by Regulating the Electronic Structure and Surface Reconstruction.

It is an effective strategy to develop novel electrocatalysts with controllable defects to enhance their electrocatalytic activity and stability. However, how to precisely design these catalysts on the atom scale remains very difficult. Herein, several vacancy-dependent CoZnx Mn2-x O4 catalysts are prepared through tailoring the concentration of Zn ions. The in situ activation of the obtained products accelerates the surface reconstruction. The superior electrocatalytic performance can be ascribed to the formations of MOOH (Mn, Co) active species and abundant oxygen vacancies, which are comparable to noble IrO2 and Pt/C catalysts. Zn-CoMn2 O4 -1.5 catalyst delivers a cell voltage of 1.63 V and long durability. Density functional theory calculations demonstrate that the appropriate Zn ion doping can improve the density states of p electron on the surface of catalysts significantly and benefit the d-band center closing to Fermi level, suggesting their high charge carrier density and low adsorption energy.

The novel indomethacin derivative CZ-212-3 exerts antitumor effects on castration-resistant prostate cancer by degrading androgen receptor and its variants.

Androgen receptor (AR) serves as a main therapeutic target for prostate cancer (PCa). However, resistance to anti-androgen therapy (SAT) inevitably occurs. Indomethacin is a nonsteroidal anti-inflammatory drug that exhibits activity against prostate cancer. Recently, we designed and synthesized a series of new indomethacin derivatives (CZ compounds) via Pd (II)-catalyzed synthesis of substituted N-benzoylindole. In this study, we evaluated the antitumor effect of these novel indomethacin derivatives in castration-resistant prostate cancer (CRPC). Upon employing CCK-8 cell viability assays and colony formation assays, we found that these derivatives had high efficacy against CRPC tumor growth in vitro. Among these derivatives, CZ-212-3 exhibited the most potent efficacy against CRPC cell survival and on apoptosis induction. Mechanistically, CZ-212-3 significantly suppressed the expression of AR target gene networks by degrading AR and its variants. Consistently, CZ-212-3 significantly inhibited tumor growth in CRPC cell line-based xenograft and PDX models in vivo. Taken together, the data show that the indomethacin derivative CZ-212-3 significantly inhibited CRPC tumor growth by degrading AR and its variants and could be a promising agent for CRPC therapy.

para-Selective Radical Trifluoromethylation of Benzamide Derivatives via Iminium Intermediates.

The direct C-H trifluoromethylation of arenes via a radical pathway has attracted considerable attention recently. However, a major challenge of C-H trifluoromethylation is the lack of site-selectivity on the phenyl ring especially para-selectivity. Herein we show a new strategy for para-selective C-H trifluoromethylation of benzamide derivatives using iminium activation. The reaction undergoes a radical-type nucleophilic substitution instead of a radical-type electrophilic substitution owing to iminium activation as a result of lowering the LUMO (lowest unoccupied molecular orbital). A wide range of substrates are compatible with this method giving almost exclusive para-trifluoromethylated products.

Age-specific definition of low anti-Mullerian hormone and associated pregnancy outcome in women undergoing IVF treatment.

BACKGROUND: The age-specific definition of low anti-müllerian hormone (AMH) is lacking. This study aims to define an age-specific reference for low AMH and to evaluate the associated outcome in women undergoing IVF treatment. METHODS: A retrospective study was performed in women receiving IVF treatment at the Shenzhen maternity and child healthcare hospital between September 2016 and September 2018. We excluded cases without AMH concentration. Polynomial least-squares regression was used to estimate the age-specific reference ranges for AMH after log-transformed. The age-specific 10th centile was defined as the threshold of low AMH concentration. RESULTS: A total of 909 patients were analyzed in this study. The age-specific reference ranges for AMH were established using linear regression model and resulted in an age-specific equation for mean: mean of LnAMH = (- 0.085 × age) + 3.722 (ng/ml, in unit). Women with AMH level higher than 10th centile had favorable outcomes in ovarian stimulation compared to those with low AMH level. In patients younger than 35 years, the rates of clinical pregnancy per transfer and ongoing pregnancy per transfer in the subgroup with AMH level higher than 10th centile were significantly higher than that in the subgroup of low AMH level, 57% versus 31.3% p = 0.003 and 51.9% versus 21.9% p = 0.001, respectively. CONCLUSION: Women with AMH lower than age-specific 10th centile had significantly unfavorable outcomes after IVF treatment. The age-specific 10th centile of AMH concentration may be useful to predict the outcome of IVF treatment.

Live birth rate of twin pregnancies after frozen embryo transfer: natural cycle versus ovulation induction regimens.

PURPOSE: Ovulation induction (OI) using letrozole or human menopausal hormone (hMG) is recently developed for endometrium preparation in frozen embryo transfer (FET) cycles. The purpose of this study is to compare the live birth rate of twin pregnancies between modified natural and OI regimens for endometrium preparation in FET cycles. STUDY DESIGN: This study included all consecutive twin pregnancies following FET with modified natural cycle (mNC-FET) or OI (OI-FET) regimen for endometrium preparation between January 2015 to June 2019. Primary outcome was the live birth of at least one twin per pregnancy. Multivariable logistic regression analysis was used to evaluate the potential association of endometrium preparation regimen and live birth. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated. RESULTS: During the study period, 269 twin pregnancies after mNC-FET and 177 twin pregnancies after OI-FET were included. The live birth rate of at least one twin per pregnancy was not significantly different between mNC-FET and OI-FET groups, 92.2% vs 90.4%; aOR 0.65; 95%CI 0.32-1.34. The multivariable regression analysis showed that twin pregnancies after OI-FET had decreased odds for gestational diabetes mellitus (aOR 0.37; 95% CI 0.16-0.87) in comparison to twin pregnancies after mNC-FET. In subgroup analysis, we found that the rate of live birth of at least one twin per pregnancy was significantly higher in OI-FET cycles using letrozole compared to those using hMG (94% vs 83.3%; aOR 3.45; 95%CI 1.24-9.57). CONCLUSION: The live birth rate in twin pregnancies after FET is comparable between mNC or OI regimens for endometrium preparation.

Screening for preeclampsia in low-risk twin pregnancies at early gestation.

INTRODUCTION: Preeclampsia affects about 10% of twin pregnancies and significantly increases the risk of adverse pregnancy outcomes. However, screening models for preeclampsia in twin pregnancies remain elusive. The present study aimed to evaluate the performance of a multi-marker first trimester preeclampsia screening model in low-risk twin pregnancies. MATERIAL AND METHODS: Between 2014 and 2017, we prospectively assessed first trimester biomarkers for preeclampsia in a 'low-risk' twin pregnancy cohort at a single center. Multiple logistic regression was used to determine significant predictors for early preeclampsia (occurring prior to 34 weeks) and late preeclampsia (occurring after 34 weeks). The performance of the screening models fitted using the significant predictors was calculated using receiver operating characteristics curves, and internal validation was performed using bootstrapping. RESULTS: A total of 769 twin pregnancies were included in the study. Early preeclampsia and late preeclampsia developed in 27 (3.5%) and 59 (7.7%) cases, respectively. Logistic regression analyses showed that maternal age, body mass index, mean artery pressure and placental growth factor were significant predictors for early preeclampsia. Maternal age, body mass index, mean artery pressure and pregnancy-associated plasma protein A were significant for late preeclampsia. Uterine artery pulsatility index was not predictive of either early or late preeclampsia. For the fitted screening model of early and late preeclampsia, the areas under receiver operating characteristics curves were 0.82 (95% confidence interval [CI] 0.76-0.88) and 0.66 (95% CI 0.59-0.73), which were expected to decrease to 0.77 and 0.60, respectively, based on bootstrapping; the positive predictive values were 10.2% and 12.5%; and the estimated detection rates were 40.7% and 22.0%, respectively, at a false-positive rate of 10%. CONCLUSIONS: A multi-marker screening model for preeclampsia in low-risk twin pregnancies, using a modified version of Fetal Medicine Foundation predictors in singletons, does not perform well. Uterine artery pulsatility index is of little value in screening for preeclampsia in low-risk twin pregnancies.

Synthesis of Functionalized Indoles via Palladium-Catalyzed Cyclization of N-(2-allylphenyl) Benzamide: A Method for Synthesis of Indomethacin Precursor.

We developed an efficient method for synthesis of substituted N-benzoylindole via Pd(II)-catalyzed C-H functionalization of substituted N-(2-allylphenyl)benzamide. The reaction showed a broad substrate scope (including N-acetyl and N-Ts substrates) and substituted indoles were obtained in good to excellent yields. The most distinctive feature of this method lies in the high selectivity for N-benzoylindole over benzoxazine, and this is the first example of Pd(II)-catalyzed synthesis of substituted N-benzoylindole. Notably, this new method was applied for the synthesis of key intermediate of indomethacin.

Regio- and Enantioselective Synthesis of Sulfone-Bearing Quaternary Carbon Stereocenters by Pd-Catalyzed Allylic Substitution.

Chiral sulfones are of great importance in medicinal chemistry and chemical synthesis. Efficient methods for preparing enantiomerically enriched sulfone-containing molecules can therefore be of significant value; such methods, however, are uncommon. Herein, we report the first general palladium-catalyzed sulfonylation of vinyl cyclic carbonates with sodium sulfinates. A series of enantiomerically enriched tertiary allylic sulfones were synthesized in good yields with excellent enantiomeric ratios. Both aliphatic- and aryl-substituted vinyl cyclic carbonates are suitable reactants with excellent results. This reaction features broad substrates scope, readily available starting materials, excellent regio- and enantioselectivity, and synthesis of sulfone-bearing quaternary carbon stereocenters. Through the sulfonylation of geranyl derived cyclic carbonate 1 h, we achieve the formal total synthesis of (+)-agelasidine A.

Identifying occult maternal malignancies from 1.93 million pregnant women undergoing noninvasive prenatal screening tests.

PURPOSE: Multiple chromosomal aneuploidies may be associated with maternal malignancies and can cause failure of noninvasive prenatal screening (NIPS) tests. However, multiple chromosomal aneuploidies show poor specificity and selectivity for diagnosing maternal malignancies. METHODS: This multicenter retrospective analysis evaluated 639 pregnant women who tested positive for multiple chromosomal aneuploidies on initial NIPS test between January 2016 and December 2017. Women were assessed using genome profiling of copy-number variations, which was translated to cancer risk using a novel bioinformatics algorithm called the cancer detection pipeline (CDP). Sensitivity, specificity, and positive predictive value (PPV) of diagnosing maternal malignancies were compared for multiple chromosomal aneuploidies, the CDP model, and the combination of CDP and plasma tumor markers. RESULTS: Of the 639 subjects, 41 maternal malignant cancer cases were diagnosed. Multiple chromosomal aneuploidies predicted maternal malignancies with a PPV of 7.6%. Application of the CDP algorithm to women with multiple chromosomal aneuploidies allowed 34 of the 41 (83%) cancer cases to be identified, while excluding 422 of 501 (84.2%) of the false positive cases. Combining the CDP with plasma tumor marker testing gave PPV of 75.0%. CONCLUSION: The CDP algorithm can diagnose occult maternal malignancies with a reasonable PPV in multiple chromosomal aneuploidies-positive pregnant women in NIPS tests. This performance can be further improved by incorporating findings for plasma tumor markers.

Sea-Sky Line and its Nearby Ships Detection Based on the Motion Attitude of Visible Light Sensors.

In the maritime scene, visible light sensors installed on ships have difficulty accurately detecting the sea-sky line (SSL) and its nearby ships due to complex environments and six-degrees-of-freedom movement. Aimed at this problem, this paper combines the camera and inertial sensor data, and proposes a novel maritime target detection algorithm based on camera motion attitude. The algorithm mainly includes three steps, namely, SSL estimation, SSL detection, and target saliency detection. Firstly, we constructed the camera motion attitude model by analyzing the camera's six-degrees-of-freedom motion at sea, estimated the candidate region (CR) of the SSL, then applied the improved edge detection algorithm and the straight-line fitting algorithm to extract the optimal SSL in the CR. Finally, in the region of ship detection (ROSD), an improved visual saliency detection algorithm was applied to extract the target ships. In the experiment, we constructed SSL and its nearby ship detection dataset that matches the camera's motion attitude data by real ship shooting, and verified the effectiveness of each model in the algorithm through comparative experiments. Experimental results show that compared with the other maritime target detection algorithm, the proposed algorithm achieves a higher detection accuracy in the detection of the SSL and its nearby ships, and provides reliable technical support for the visual development of unmanned ships.

Solvent Mixing To Induce Molecular Motor Aggregation into Bowl-Shaped Particles: Underlying Mechanism, Particle Nature, and Application To Control Motor Behavior.

Control over dynamic functions in larger assemblies is key to many molecular systems, ranging from responsive materials to molecular machines. Here we report a molecular motor that forms bowl-shaped particles in water and how confinement of the molecular motor affects rotary motion. Studying the aggregation process in a broader context, we provide evidence that, in the case of bowl-shaped particles, the structures are not the product of self-assembly, but a direct result of the mixing a good solvent and a (partial) non-solvent and highly independent of the molecular design. Under the influence of the non-solvent, droplets are formed, of which the exterior is hardened due to the increase in the glass transition temperature by the external medium, while the interior of the droplets remains plasticized by the solvent, resulting in the formation of stable bowl-shaped particles with a fluid interior, a glass-like exterior, and a very specific shape: dense spheres with a hole in their side. Applying this to a bulky first-generation molecular motor allowed us to change its isomerization behavior. Furthermore, the motor shows in situ photo-switchable aggregation-induced emission. Strong confinement prohibits the thermal helix inversion step while altering the energy barriers that determine the rotary motion, such that it introduces a reverse trans- cis isomerization upon heating. These studies show a remarkable control of forward and backward rotary motion by simply changing solvent ratios and extent of confinement.

Incidence and Causes of Intentional Fetal or Neonatal Demise in Twin-Twin Transfusion Syndrome.

INTRODUCTION: The aim of this study is to evaluate the incidence and causes of intentional fetal and neonatal demise in twin-twin transfusion syndrome (TTTS). MATERIAL AND METHODS: All TTTS pregnancies managed at our centre between 2000 and 2014 were included. We evaluated incidence and causes of intentional fetal/neonatal demise, defined as termination of pregnancy, selective fetal reduction, or withdrawal of neonatal intensive care. RESULTS: Intentional fetal/neonatal demise occurred in 9.8% (110/1,122) of fetuses and was due to termination of pregnancy (2.2%), selective fetal reduction (4.2%), or withdrawal of neonatal intensive care (3.4%). Reasons for termination of pregnancy included complications of laser treatment (72.0%), severe fetal anomaly (20.0%), and unwanted pregnancy (8.0%). Reasons for selective fetal reduction were technical difficulties to perform laser surgery (51.1%), fetal complications (38.3%), and parental preference for fetal reduction rather than laser treatment (10.6%). Reasons for withdrawal of neonatal intensive care treatment were severe cerebral injury (47.4%), severe pulmonary complications (15.8%), birth asphyxia (5.3%), multiple complications of TTTS and/or prematurity combined (21.1%), or other (10.5%). CONCLUSIONS: Intentional fetal or neonatal demise in TTTS occurs frequently and is often due to complications after laser surgery and/or severe (cerebral) injury in affected fetuses or neonates.

Crustacean hyperglycemic hormones directly modulate the immune response of hemocytes in shrimp Litopenaeus vannamei.

A robust immune response against invading pathogens is crucial for host to survive, which depends greatly on the well balance of metabolism. Increasing evidence has indicated that some metabolic hormones, such as insulin, could modulate immune responses directly. Crustacean hyperglycemic hormone (CHH) family is a group of ecdysozoans-specific peptide hormone involved in glucose metabolism and other biological events. In the present study, two members of CHH family (designated as LvCHH I and LvCHH II) in shrimp Litopenaeus vannamei with one and two crustacean neurohormone domains respectively were chosen to investigate their putative modulatory roles in both glucose metabolism and immune response. LvCHH I and LvCHH II were both expressed in the sinus gland and lamina ganglionalis of eyestalks and were significantly induced after white spot syndrome virus (WSSV) infection. Meanwhile, significant increases of hemolymph glucose levels were observed in shrimp at 12 and 24 h after WSSV infection while the glucose inside the hemocytes decreased at 6 h and then increased at 12 h. Gain-of-function of rLvCHHs was subsequently conducted in vivo by injecting the recombinant proteins (rLvCHH I and rLvCHH II). The hemolymph glucose increased significantly from 0.5 h to 3 h after the shrimps received an injection of rLvCHH I, while it decreased at 0.5 h and increased afterward at 3 h post rLvCHH II injection. At the meantime, significant decreases of reactive oxygen species level in hemocytes were observed at 3 h and 6 h post rLvCHH I injection, while it remained unchanged in rLvCHH II injection group. rLvCHH I and rLvCHH II could bind to the cytomembrane of primary shrimp hemocytes in vitro, and the expressions of superoxide dismutase and LvRelish increased when the hemocytes were incubated with rLvCHH I for 3 h. Meanwhile, the expression of antimicrobial peptides, crustin and penaeidin-4, were also induced by rLvCHH I and rLvCHH II. These results demonstrated that host immune response, in addition to glucose metabolism, could be directly modulated by LvCHH family, and the present study provided new insights into the immunomodulation role of metabolic hormones in invertebrate.

Ammonia exposure induces oxidative stress, endoplasmic reticulum stress and apoptosis in hepatopancreas of pacific white shrimp (Litopenaeus vannamei).

Ammonia is one of major environmental pollutants in the aquatic system that poses a great threat to the survival of shrimp. In the present study, the mRNA expression of endoplasmic reticulum (ER) stress marker and unfolded protein response (UPR) related genes, as well as the change of redox enzyme and apoptosis were investigated in hepatopancreas of the pacific white shrimp, Litopenaeus vannamei after the exposure of 20 mg L(-1) total ammonia nitrogen (TAN). Compared with the control group, the superoxide dismutase (SOD) activity in hepatopancreas decreased significantly (p < 0.05) at 96 h, whereas the malonyldialdehyde (MDA) concentration increased significantly (p < 0.05). The mRNA expression levels of ER stress marker-immunoglobulin heavy chain binding protein (Bip) gene and key UPR related genes including activating transcription factor 4 (ATF4) and the spliced form of X box binding protein 1 (XBP1) increased significantly (p < 0.05) in hepatopancreas at 96 h after exposure to ammonia. In addition, apoptosis was observed obviously in the hepatopancreas of L. vannamei after exposure to ammonia by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. The results indicated that ammonia exposure could induce oxidative stress, which further caused ER stress and apoptosis in hepatopancreas of L. vannamei.

Comparison Between Monochorionic and Dichorionic Placentas With Special Attention to Vascular Anastomoses and Placental Share.

Placental vascular anastomoses in twins lead to a shared circulation and may subsequently enable the development of severe complications such as twin-twin transfusion syndrome (TTTS) and twin anemia-polycythemia sequence (TAPS). The presence of vascular anastomoses has frequently and systematically been studied in monochorionic (MC) placentas, but only rarely in dichorionic (DC) placentas. The aim of this study was to compare the prevalence of vascular anastomoses and evaluate the sharing discordance in MC and DC placentas. All consecutive placentas of MC and DC twins delivered at the Leiden University Medical Center (the Netherlands) and Medical University of Warsaw (Poland) from 2012 to 2015 were routinely injected with colored dye and included in the study. We excluded twin pregnancies treated with fetoscopic laser surgery. A total of 258 placentas were analyzed in this study, including 134 MC placentas and 124 DC placentas. Vascular anastomoses were present in 99% (133/134) of MC placentas and 0% of DC placentas (p < .01). Placental share discordance between MC twins was significantly larger compared to DC twins, 19.8 (interquartile range [IQR] 8.1-33.3) and 10.8 (IQR 6.2-19.0), respectively (p < .01). Vascular anastomoses associated complications occurred in 16% (22/134) MC twins. Our findings show that vascular anastomoses are almost ubiquitous in MC placentas, but non-existent in DC placentas. In addition, unequal placental sharing appears to be more common in MC than in DC placentas.