Spiral artery blood flow during pregnancy: a systematic review and meta-analysis.

BACKGROUND: Downstream remodeling of the spiral arteries (SpA) decreases utero-placental resistance drastically, allowing sustained and increased blood flow to the placenta under all circumstances. We systematically evaluated available reports to visualize adaptation of spiral arteries throughout pregnancy by ultra-sonographic measurements and evaluated when this process is completed. METHODS: A systematic review and meta-analysis of spiral artery flow (pulsatility index (PI), resistance index (RI) and peak systolic velocity (PSV)) was performed. English written articles were obtained from Pubmed, EMBASE and Cochrane Library and included articles were assessed on quality and risk of bias. Weighted means of Doppler indices were calculated using a random-effects model. RESULTS: In healthy pregnancies, PI and RI decreased from 0.80 (95% CI: 0.70-0.89) and 0.50 (95% CI: 0.47-0.54) in the first trimester to 0.50 (95% CI: 0.45-0.55, p < 0.001) and 0.39 (95% CI: 0.37-0.42, p < 0.001) in the second trimester and to 0.49 (95% CI: 0.44-0.53, p = 0.752) and 0.36 (95% CI: 0.35-0.38, p = 0.037) in the third trimester, respectively. In parallel, PSV altered from 0.22 m/s (95% CI: 0.13-0.30 m/s) to 0.28 m/s (95% CI: 0.17-0.40 m/s, p = 0.377) and to 0.25 m/s (95% CI: 0.20-0.30 m/s, p = 0.560) in the three trimesters. In absence of second and third trimester Doppler data in complicated gestation, only a difference in PI was observed between complicated and healthy pregnancies during the first trimester (1.49 vs 0.80, p < 0.001). Although individual studies have identified differences in PI between SpA located in the central part of the placental bed versus those located at its periphery, this meta-analysis could not confirm this (p = 0.349). CONCLUSIONS: This review and meta-analysis concludes that an observed decrease of SpA PI and RI from the first towards the second trimester parallels the physiological trophoblast invasion converting SpA during early gestation, a process completed in the midst of the second trimester. Higher PI was found in SpA of complicated pregnancies compared to healthy pregnancies, possibly reflecting suboptimal utero-placental circulation. Longitudinal studies examining comprehensively the predictive value of spiral artery Doppler for complicated pregnancies are yet to be carried out.

From flat to tilted: gradual interfaces in organic thin film growth.

We investigate domain formation and local morphology of thin films of α-sexithiophene (α-6T) on Au(100) beyond monolayer coverage by combining high resolution scanning tunneling microscopy (STM) experiments with electronic structure theory calculations and computational structure search. We report a layerwise growth of highly-ordered enantiopure domains. For the second and third layer, we show that the molecular orbitals of individual α-6T molecules can be well resolved by STM, providing access to detailed information on the molecular orientation. We find that already in the second layer the molecules abandon the flat adsorption structure of the monolayer and adopt a tilted conformation. Although the observed tilted arrangement resembles the orientation of α-6T in the bulk, the observed morphology does not yet correspond to a well-defined surface of the α-6T bulk structure. A similar behavior is found for the third layer indicating a growth mechanism where the bulk structure is gradually adopted over several layers.

Structural heterogeneity in a parent ground-state structure of AnPixJg2 revealed by theory and spectroscopy.

We investigated the red absorbing, dark stable state (Pr state) of the second GAF domain of the cyanobacteriochrome AnPixJ (AnPixJg2) by a molecular dynamics simulation of 1 µs duration. Our results reveal two distinct conformational isoforms of the chromophore, from which only one was known from crystallographic experiments. The interconversion between both isoforms is accompanied by alterations in the hydrogen bond pattern between the chromophore and the protein and the solvation structure of the chromophore binding pocket. The existence of sub-states in the Pr form of AnPixJg2 is supported by the results from experimental 13C MAS NMR spectroscopy. Our finding is consistent with the observation of structural heterogeneity in other cyanobacteriochromes and phytochromes.

Single-incision laparoscopic cholecystectomy versus conventional four-port laparoscopic cholecystectomy: a systematic review and meta-analysis.

BACKGROUND: Single-incision laparoscopic cholecystectomy (SILC) might maximize the advantages of laparoscopic cholecystectomy (LC) by reducing postoperative pain and improving cosmesis. However, the safety and feasibility of SILC has not yet been established. This study assesses safety, patient reported outcome measures and feasibility of SILC versus conventional LC. METHODS: Literature search for RCT's comparing SILC with conventional LC in gallstone-related disease was performed in PubMed and Embase. The conventional LC was defined as two 10-mm and two 5-mm ports. Study selection was done according to predefined criteria. Two reviewers assessed the risk of bias. Pooled outcomes were calculated for adverse events, pain, cosmesis, quality of life and feasibility using fixed-effect and random-effects models. RESULTS: Nine RCT's were included with total of 860 patients. No mortality was observed. More mild adverse events (RR 1.55; 95% CI 0.99-2.42) and significantly more serious adverse events (RR 3.00; 95% CI 1.05-8.58) occurred in the SILC group. Postoperative pain (MD -0.46; 95% CI -0.74 to -0.18) and cosmesis (SMD 2.38; 95% CI 1.50-3.26) showed significantly better results for the SILC group, but no differences were observed in quality of life. Operating time (MD 23.12; 95% CI 11.59-34.65) and the need for additional ports (RR 11.43; 95% CI 3.48-37.50) were significantly higher in the SILC group. No difference was observed in conversion to open cholecystectomy or hospital stay longer than 24 h. CONCLUSIONS: SILC does not provide any clear advantages over conventional LC except for less postoperative pain and improved cosmesis. It is questionable whether these advantages outweigh the higher occurrence of adverse events and shortcomings in feasibility. Considering considerable heterogeneity and low methodological quality of the studies it is advisable to perform well-designed RCT's in the future to address the safety and clinical benefits of SILC.

Molecular features contributing to the lower viscosity of phosphonium ionic liquids compared to their ammonium analogues.

Molecular features contributing to the lower viscosity of phosphonium based ionic liquids (ILs) compared to ammonium based ILs are investigated by static quantum chemistry calculations and classical molecular dynamics simulations. The larger bond distance and the higher flexibility of bond angles and dihedral angles in the phosphonium compounds tend to reduce their viscosity compared to ammonium analogues, while the strongly localized charge at the central atom has the opposite effect. Fast translational ion dynamics is also found to be related to a short counter-ion association lifetime in the investigated compounds. Furthermore, a weak structuring between the center of charges also seems to increase mobility. Interestingly, the order of ion pair interaction energies in the gas phase is reversed compared to the order of counter-ion association lifetimes in the liquid, which highlights the important role of solvation in ILs. Overall, the higher flexibility of the bond and dihedral angles of the phosphonium compounds appears to be the most important factor in producing the lower viscosity of these ILs compared to their ammonium analogues.