In Vivo Evaluation of Cervical Stiffness Evolution during Induced Ripening Using Shear Wave Elastography, Histology and 2 Photon Excitation Microscopy: Insight from an Animal Model

Prematurity affects 11% of the births and is the main cause of infant mortality. On the opposite case, the failure of induction of parturition in the case of delayed spontaneous birth is associated with fetal suffering. Both conditions are associated with precocious and/or delayed cervical ripening. Quantitative and objective information about the temporal evolution of the cervical ripening may provide a complementary method to identify cases at risk of preterm delivery and to assess the likelihood of successful induction of labour. In this study, the cervical stiffness was measured in vivo in pregnant sheep by using Shear Wave Elastography (SWE). This technique assesses the stiffness of tissue through the measurement of shear waves speed (SWS). In the present study, 9 pregnant ewes were used. Cervical ripening was induced at 127 days of pregnancy (term: 145 days) by dexamethasone injection in 5 animals, while 4 animals were used as control. Elastographic images of the cervix were obtained by two independent operators every 4 hours during 24 hours after injection to monitor the cervical maturation induced by the dexamethasone. Based on the measurements of SWS during vaginal ultrasound examination, the stiffness in the second ring of the cervix was quantified over a circular region of interest of 5 mm diameter. SWS was found to decrease significantly in the first 4–8 hours after dexamethasone compared to controls, which was associated with cervical ripening induced by dexamethasone (from 1.779 m/s ± 0.548 m/s, p < 0.0005, to 1.291 m/s ± 0.516 m/s, p < 0.000). Consequently a drop in the cervical elasticity was quantified too (from 9.5 kPa ± 0.9 kPa, p < 0.0005, to 5.0 kPa ± 0.8 kPa, p < 0.000). Moreover, SWE measurements were highly reproducible between both operators at all times. Cervical ripening induced by dexamethasone was confirmed by the significant increase in maternal plasma Prostaglandin E2 (PGE2), as evidenced by the assay of its metabolite PGEM. Histological analyses and two-photon excitation microscopy, combining both Second Harmonic Generation (SHG) and Two-photon Fluorescence microscopy (2PF) contrasts, were used to investigate, at the microscopic scale, the structure of cervical tissue. Results show that both collagen and 2PF-active fibrillar structures could be closely related to the mechanical properties of cervical tissue that are perceptible in elastography. In conclusion, SWE may be a valuable method to objectively quantify the cervical stiffness and as a complementary diagnostic tool for preterm birth and for labour induction success

Goodbye Hartmann trial: a prospective, international, multicenter, observational study on the current use of a surgical procedure developed a century ago

Background: Literature suggests colonic resection and primary anastomosis (RPA) instead of Hartmann's procedure (HP) for the treatment of left-sided colonic emergencies. We aim to evaluate the surgical options globally used to treat patients with acute left-sided colonic emergencies and the factors that leading to the choice of treatment, comparing HP and RPA. Methods: This is a prospective, international, multicenter, observational study registered on ClinicalTrials.gov. A total 1215 patients with left-sided colonic emergencies who required surgery were included from 204 centers during the period of March 1, 2020, to May 31, 2020. with a 1-year follow-up. Results: 564 patients (43.1%) were females. The mean age was 65.9 ± 15.6&nbsp;years. HP was performed in 697 (57.3%) patients and RPA in 384 (31.6%) cases. Complicated acute diverticulitis was the most common cause of left-sided colonic emergencies (40.2%), followed by colorectal malignancy (36.6%). Severe complications (Clavien-Dindo ≥ 3b) were higher in the HP group (P &lt; 0.001). 30-day mortality was higher in HP patients (13.7%), especially in case of bowel perforation and diffused peritonitis. 1-year follow-up showed no differences on ostomy reversal rate between HP and RPA. (P = 0.127). A backward likelihood logistic regression model showed that RPA was preferred in younger patients, having low ASA score (≤ 3), in case of large bowel obstruction, absence of colonic ischemia, longer time from admission to surgery, operating early at the day working hours, by a surgeon who performed more than 50 colorectal resections. Conclusions: After 100&nbsp;years since the first Hartmann's procedure, HP remains the most common treatment for left-sided colorectal emergencies. Treatment's choice depends on patient characteristics, the time of surgery and the experience of the surgeon. RPA should be considered as the gold standard for surgery, with HP being an exception

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

High-speed polarization-resolved coherent Raman scattering imaging

International audiencePolarization-resolved coherent Raman scattering (polar-CRS) provides rich information on molecular orientational organization, with the strong advantages of being a label-free and chemically specific imaging method. Its implementation , however, strongly reduces the imaging acquisition rate, due to limits imposed by polarization tuning. Here we demonstrate fast-polar-CRS imaging based on combined electro-optic polarization and acousto-optic amplitude modulations , applicable to both stimulated Raman scattering and coherent anti-Stokes Raman scattering imaging. The proposed scheme adds polarization information without compromising the capacities of regular CRS intensity imaging ; increases the speed of orientational imaging by two orders of magnitude as compared with previous approaches; and does not require post-processing analyses. We show that this method permits sub-second timescale imaging of lipid order packing and local lipid membrane deformations in artificial lipid multilayers, but also in red blood cell ghosts, demonstrating its high sensitivity down to a single lipid bilayer membrane

Lipid Order Degradation in Autoimmune Demyelination Probed by Polarized Coherent Raman Microscopy

International audienc

Label-free non-linear multimodal optical microscopy—basics, development, and applications

Non-linear optical (NLO) microscopy has proven to be a powerful tool especially for tissue imaging with sub-cellular resolution, high penetration depth, endogenous contrast specificity, pinhole-less optical sectioning capability. In this review, we discuss label-free non-linear optical microscopes including the two-photon fluorescence (TPF), fluorescence lifetime imaging microscopy (FLIM), polarization-resolved second harmonic generation (SHG) and coherent anti-Stokes Raman scattering (CARS) techniques with various samples. The non-linear signals are generated from collagen in tissue (SHG), amylopectin from starch granules (SHG), sarcomere structure of fresh muscle (SHG), elastin in skin (TPF), nicotinamide adenine dinucleotide (NADH) in cells (TPF), and lipid droplets in cells (CARS). Again, the non-linear signals are very specific to the molecular structure of the sample and its relative orientation to the polarization of the incident light. Thus, polarization-resolved non-linear optical microscopy provides high image contrast and quantitative estimate of sample orientation. An overview of the advancements on polarization-resolved SHG microscopy including Stokes vector based polarimetry, circular dichroism, and susceptibility are also presented in this review article. The working principles and corresponding implements of above-mentioned microscopy techniques are elucidated. The potential of time-resolved TPF lifetime imaging microscopy (TP-FLIM) is explored by imaging endogenous fluorescence of NAD(P)H, a key coenzyme in cellular metabolic processes. We also discuss single laser source time-resolved multimodal CARS-FLIM microscopy using time-correlated single-photon counting (TCSPC) in combination with continuum generation from photonic crystal fiber (PCF). Using examples, we demonstrate that the multimodal NLO microscopy is a powerful tool to assess the molecular specificity with high resolution

Effects of Excitonic Resonance on Second and Third Order Nonlinear Scattering from Few-Layer MoS₂

Nonlinear optical scattering from single- and few-layer MoS₂ contains important information about the orientation, inversion symmetry, and degree of interlayer coupling between the layers. We simultaneously map second harmonic generation (SHG) and four wave mixing (FWM) signals in chemical vapor deposition (CVD) grown 2H-phase MoS₂ from single to five layers. We tune the excitation wavelengths to compare cases where the nonlinear signals are on and off resonance with the <i>A</i>-exciton band. The SHG signal shows the expected 4-fold symmetry, however, the FWM signal depends on the incident laser polarization only, and is independent of the crystallographic orientation. We show using the symmetry of the χ⁽³⁾ tensor that this results from out of plane FWM dipoles. We explore the scaling of SHG and FWM signals with layer number on and off excitonic resonance When a nonlinear scattered signal overlaps with the <i>A</i> excitonic band, the scaling of the signals with layer number deviates from the expected values, due to the layer dependent red shift in the exciton absorption peak due to interlayer coupling. Finally we show that circularly polarized excitation significantly enhances nonlinear scattering which overlaps with the <i>A</i> excitonic band and indicates the presence of spin splitting of valence bands at the energy degenerate points (<i>K</i>, <i>K</i>′) of the Brillouin zone

Effects of Excitonic Resonance on Second and Third Order Nonlinear Scattering from Few-Layer MoS₂

Nonlinear optical scattering from single- and few-layer MoS₂ contains important information about the orientation, inversion symmetry, and degree of interlayer coupling between the layers. We simultaneously map second harmonic generation (SHG) and four wave mixing (FWM) signals in chemical vapor deposition (CVD) grown 2H-phase MoS₂ from single to five layers. We tune the excitation wavelengths to compare cases where the nonlinear signals are on and off resonance with the <i>A</i>-exciton band. The SHG signal shows the expected 4-fold symmetry, however, the FWM signal depends on the incident laser polarization only, and is independent of the crystallographic orientation. We show using the symmetry of the χ⁽³⁾ tensor that this results from out of plane FWM dipoles. We explore the scaling of SHG and FWM signals with layer number on and off excitonic resonance When a nonlinear scattered signal overlaps with the <i>A</i> excitonic band, the scaling of the signals with layer number deviates from the expected values, due to the layer dependent red shift in the exciton absorption peak due to interlayer coupling. Finally we show that circularly polarized excitation significantly enhances nonlinear scattering which overlaps with the <i>A</i> excitonic band and indicates the presence of spin splitting of valence bands at the energy degenerate points (<i>K</i>, <i>K</i>′) of the Brillouin zone

Effects of Excitonic Resonance on Second and Third Order Nonlinear Scattering from Few-Layer MoS₂

Nonlinear optical scattering from single- and few-layer MoS₂ contains important information about the orientation, inversion symmetry, and degree of interlayer coupling between the layers. We simultaneously map second harmonic generation (SHG) and four wave mixing (FWM) signals in chemical vapor deposition (CVD) grown 2H-phase MoS₂ from single to five layers. We tune the excitation wavelengths to compare cases where the nonlinear signals are on and off resonance with the <i>A</i>-exciton band. The SHG signal shows the expected 4-fold symmetry, however, the FWM signal depends on the incident laser polarization only, and is independent of the crystallographic orientation. We show using the symmetry of the χ⁽³⁾ tensor that this results from out of plane FWM dipoles. We explore the scaling of SHG and FWM signals with layer number on and off excitonic resonance When a nonlinear scattered signal overlaps with the <i>A</i> excitonic band, the scaling of the signals with layer number deviates from the expected values, due to the layer dependent red shift in the exciton absorption peak due to interlayer coupling. Finally we show that circularly polarized excitation significantly enhances nonlinear scattering which overlaps with the <i>A</i> excitonic band and indicates the presence of spin splitting of valence bands at the energy degenerate points (<i>K</i>, <i>K</i>′) of the Brillouin zone

Effects of Excitonic Resonance on Second and Third Order Nonlinear Scattering from Few-Layer MoS₂

Nonlinear optical scattering from single- and few-layer MoS₂ contains important information about the orientation, inversion symmetry, and degree of interlayer coupling between the layers. We simultaneously map second harmonic generation (SHG) and four wave mixing (FWM) signals in chemical vapor deposition (CVD) grown 2H-phase MoS₂ from single to five layers. We tune the excitation wavelengths to compare cases where the nonlinear signals are on and off resonance with the <i>A</i>-exciton band. The SHG signal shows the expected 4-fold symmetry, however, the FWM signal depends on the incident laser polarization only, and is independent of the crystallographic orientation. We show using the symmetry of the χ⁽³⁾ tensor that this results from out of plane FWM dipoles. We explore the scaling of SHG and FWM signals with layer number on and off excitonic resonance When a nonlinear scattered signal overlaps with the <i>A</i> excitonic band, the scaling of the signals with layer number deviates from the expected values, due to the layer dependent red shift in the exciton absorption peak due to interlayer coupling. Finally we show that circularly polarized excitation significantly enhances nonlinear scattering which overlaps with the <i>A</i> excitonic band and indicates the presence of spin splitting of valence bands at the energy degenerate points (<i>K</i>, <i>K</i>′) of the Brillouin zone